Consumer Products – Jose Siqueira, Ann L. McCormack, Norman Brown, Wing-Chak Ng, Howard M. Welch, Margaret G. Latimer, Kimberly Clark Worldwide Inc
Abstract for “Nonwoven composite containing an apertured Elastic film”
“A nonwoven elastic composite is a nonwoven elastic composite that includes an elastic film laminated with one or more nonwoven Web materials. To bond the film to nonwoven web materials, the composite is made by passing the film through an nip. The elastic film also forms apertures. Apertures are small enough to give the composite desired texture, softness and hand feel without affecting its elastic properties. The present invention allows for selective control of certain parameters such as the film content, bonding pattern and degree of film tension.
Background for “Nonwoven composite containing an apertured Elastic film”
Elastic composites are often used in products such as diapers, training pants and garments. To improve their ability to fit better to the contours and body. The elastic composite could be made from an elastic film combined with one or more nonwoven Web materials. The film may be stretched so that the nonwoven material can adhere to it. The elastic composite will stretch to the point that the nonwoven web material between the bond points allows the elastic film’s length to increase. Elastic films can often feel tacky or rubbery to the touch. This makes them uncomfortable and unattractive for the skin. To improve these properties, there have been attempts to open the composite. U.S. Pat. No. 6,830,800 to Curro, et al. This describes a technique in which elastic material is joined between two Webs. The bond sites are aligned so that the elastic material is apertured. There is still much to be done, despite the many benefits.
“In accordance to one embodiment of the invention, a method for forming a nonwoven-composite is disclosed. This method involves forming an elastic material from a polymer mixture and passing it and a nonwoven web through a nip made by at least one pattern roll. The film and nonwoven web materials are melt fused at the nip. At the apertures, the film is simultaneously formed without significantly softening its polymer. Each aperture has a minimum of 200-5000 micrometers in length. The film is also under tension at a stretch ratio between 1.5 and 1.5 in the machine direction at each nip.
“According to another embodiment of the invention, a nonwoven composition is disclosed. It comprises an elastic film that has been positioned adjacent and melt fused with a nonwoven web at a plurality discrete bond locations. The elastic film creates a number of apertures around which the discrete bond site are located. Each aperture has a minimum of 200-5000 micrometers in length.
“Another feature and aspect of the present invention is described in greater detail below.”
“Definitions”
“Nonwoven web” is the term used herein. A web that is composed of individual threads or fibers interwoven in a structured manner, but not in the same way as a knitted fabric. Some examples of nonwoven fabrics and webs that are suitable include: meltblown webs; spunbond webs; bonded carded Webs; coform webs; hydraulically entangled Webs, and so on.
“Meltblown web” is the term used herein. A nonwoven web is a nonwoven material that has been formed using molten thermoplastic material extruded through several fine, often circular, die capillaries. The molten fibers are then ejected into high velocity gas (e.g. air) streams which attenuate the molten thermoplastic material’s fibers to reduce their diameter. The meltblown fibers are then carried by the high-velocity gas stream and deposited on a collecting area to form a web consisting of randomly distributed meltblown fibers. This process is described in U.S. Pat. No. No. Meltblown fibers can be either microfibers that are substantially continuous, or discontinuous, usually smaller than 10 microns in size, and tacky when they are deposited onto a collecting area.
“Spunbond web” is the term used herein. A web with small diameter, substantially continuous fibers is generally referred to as?spunbond web? The fibers are made by extruding molten thermoplastic material through a number of fine, often circular, capillaries from a spinnerette. The diameter of the extruded fibres is then rapidly reduced by, for instance, eductive drawing or other well-known spinningbonding methods. U.S. Pat. explains and illustrates how spunbond webs are made. No. 4,340,563 to Appel, et al., U.S. Pat. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. When spunbond fibers are deposited onto a collecting area, they are not tacky. Spunbond fibers can sometimes have diameters of less than 40 microns and may be between 5 and 20 microns.
“Machine direction” is a term that’s commonly used in this document. “Machine direction” or “MD?” The direction in which a material was produced is generally referred to as?cross-machine direction? Cross-machine direction is also known as? The term?cross-machine direction? or?CD? Refers to the direction perpendicular the machine direction.
“As used herein, the terms ‘extensible? “Extensibility” or “extensible?” A material that can stretch or extend in the direction of an applied force of at least 25%, in some cases about 50% and in others at least 75% of its relaxed length. An extensible material doesn’t necessarily have recovery properties. An elastomeric materials, for example, is an extensible material with recovery properties. Meltblown webs can be extensible but may not have recovery properties. Therefore, they could be an extensible, elastic material.
“Elastomeric” is the term used herein. “Elastomeric” and “elastic?” The material is elastic when it can be stretched in one direction (such the CD direction) and then contracts/returns to its original dimensions upon the release of the stretching force. A stretched material might have a length that is at most 50% longer than its relaxed untretched length. However, it will recover to a minimum of 50% of its original length after the stretching force is released. One (1) inch of material, which is stretchable to at most 1.50 inches, would be an example. It will then recover to a length not exceeding 1.25 inches after the stretching force has been released. It is desirable that the material contract or recovers at minimum 50%. Even more desirable, it should recover at least 80%.
“As used herein the terms ‘necked’? “necked material” and “necked?” Generally, a material that has been drawn in at most one dimension (e.g. machine direction) to reduce its transverse dimensions (e.g. cross-machine direction). This allows the material to be pulled back to its original width when the drawing force is removed. The basis weight of necked materials is generally higher per unit area than that of un-necked materials. The basis weight of the necked material should be approximately the same as that of the un-necked. This is different from a film whose orientation is altered by thinning and reducing the basis weight. Necking involves taking material from a supply roll, and passing it through a brake roll assembly at a certain linear speed. The material is drawn by a take-up or nip that operates at a higher linear speed than the brake roll and creates the tension necessary to lengthen and neck it.
“The term thermal point bonding is used herein. It is a process that involves passing material between two rolls (e.g. calender roll and anvil roll), which can or cannot be patterned. Usually, one or both of these rolls are heated.
“Ultrasonic bonding” is the term used herein. The term “ultrasonic bonding” is used to describe a process that involves passing material between a sonic-horn and a pattern roll (e.g. anvil roll). U.S. Pat. describes ultrasonic bonding using a stationary horn and rotating patterned anvil rolls. No. 3,939,033 to Grgach, et al., U.S. Pat. No. No. No. No. U.S. Pat. describes ultrasonic bonding using a rotaryhorn with a rotating pattern anvil roll. No. No. No. No. No. No. 5,817199 to Brennecke, and others. These documents are incorporated in their entirety herein by reference thereto for any purposes. Any other ultrasonic bonding method may be used in accordance with the present invention.
“Reference will now be made in detail at various embodiments the invention. One or more examples are given below. Each example is given for explanation purposes only and not to limit the invention. It will be obvious to anyone skilled in the art that the invention can be modified and adapted without departing from its scope or spirit. To illustrate one example, features described in one embodiment may be applied to another embodiment. This is why the invention covers such modifications and variations.
“The present invention is directed at a nonwoven composite that includes an elastic film laminated with one or more nonwoven Web materials. To form the composite, the film is passed through a nip. This bonding process bonds the film to the nonwoven material(s). The elastic film also forms apertures. Apertures are small enough to give the composite desired texture, softness and hand feel without affecting its elastic properties. The present invention allows for selective control of certain parameters such as the film content, bonding pattern and degree of film tension. The present invention’s various embodiments will be discussed in greater detail.
“I. Elastic Film.”
“The elastic film of this invention is made from one or more melt-processable elastomeric polymers, i.e. thermoplastic. The present invention may be used with any of the following thermoplastic elastomeric elastomeric polmers: elastomeric polyesters; elastomeric urethanes; elastomeric amides; elastomeric copolymers; elastomeric olefins; and so forth. One embodiment uses elastomeric semicrystalline polyolefins because of their unique combination in mechanical and elastic properties. These semi-crystalline polyolefins’ mechanical properties allow for films to easily aperture during thermal bonding but still retain their elasticity.
Polyethylene, polypropylene and blends or copolymers of them are examples of semi-crystalline polyolefins. One particular embodiment uses a copolymer between ethylene and an “olefin”, such as C3-C20 or C3?C12??olefin. The?-olefins that are suitable may be either linear or branched (e.g. one or more C1?C3 alkyl branches or an aryl group). Specific examples include 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-substituted I-decene; 1-dodecene; and styrene. 1-butene; 1-hexene; and 1-octene are all desirable?-olefin copolymers. These copolymers can have a ethylene content of about 60 mole% to 99 mole%. In some embodiments, it may range from about 80 mole% to approximately 98.5 mole% and in others, from about 87 to 97.5 mole%. The?-olefin contents can also vary from approximately 1 mole% to around 40 mole% in some embodiments to about 1.5 mole% to 15 mole% and in others from about 2.5 mole% to 13 mole% in some embodiments.
The density of polyethylene can vary depending on the type of plastic used, but it generally ranges between 0.85 and 0.96 grams per cubic cm (?g/cm3?)? For example, polyethylene?plastomers can have a density of 0.85 to 0.91g/cm3. The same goes for?linear low-density polyethylene. (?LLDPE?) (?LLDPE?) (?LOPE?) (?LOPE?) (?HOPE?) (?HOPE?) ASTM 1505 may be used to measure densities.
“Particularly appropriate polyethylene copolymers” are those that are linear. Or?substantially linear. The term “substantially linear” is used. The term?substantially linear? refers to the fact that in addition to the short chains branches due to comonomer incorporation the ethylene polymer also has long chain branches in the polymer backbone. What is long chain branching? A chain with at least 6 carbons is considered long chain branching. Each long chain branch can have the same comonomer distribution and length as the polymer backingbone. Preferably substantially linear polymers can be substituted with 0.01 long chains branches per 1000 atoms to 1 longer chain branch for 1000 atoms and, in some embodiments, with 0.05 long branch per 1000 atoms to 1 extra long branch per 1,000 atoms. The term “linear” is a different term to the term “substantially linear”. The term?linear? refers to a polymer that lacks demonstrable or measurable long chain branches. This means that the average number of long chain branches per 1000 carbons in the substituted polymer is less than 0.01.
The length and the amount of the??-olefin are both factors that determine the density of a linear line of ethylene/?olefin copolymer. The copolymer’s density is affected by the length and amount of??-olefin. While not required, linear polyethylene?plastomers are desirable. are particularly desirable in that the content of ?-olefin short chain branching content is such that the ethylene copolymer exhibits both plastic and elastomeric characteristics?i.e., a ?plastomer.? The density of plastomers resulting from polymerization with??olefin-comonomers is lower than that of polyethylene thermoplastic copolymers (e.g. LLDPE), but close to or overlapping that of an elastic material. The density of polyethylene plastomer can range from 0.85 to 0.88 grams per cubic cm3 (g/cm3) in some embodiments and from 0.85 g/cm3 up to 0.87g/cm3 in others. Although plastomers have a similar density to elastomers they are generally more crystallin and less sticky than elastomers. They can also be made into pellets that are not-adhesive, relatively free-flowing, and may even be non-adhesive.
“The preferred plastomers for the invention are the ethylene-based copolymer plastic plastomers that are available under the name EXACT?” ExxonMobil Chemical Company, Houston, Tex. You can also find other suitable polyethylene plastomers under the name ENGAGE. ENGAGE? und AFFINITY? Dow Chemical Company of Midland (Mich.) Other suitable ethylene polymers can also be purchased from Dow Chemical Company, under the DOWLEX designation. (LLDPE and ATTANE). (ULDPE). U.S. Pat. No. 4,937,299 to Ewen and al. ; U.S. Pat. No. 5,218,071 to Tsutsui et al. ; U.S. Pat. No. 5,272,236 to Lai, et al. ; and U.S. Pat. No. No.
“Of course the invention is not limited to ethylene polymers. Propylene polymers can also be used as semi-crystalline polyolefins. Propylene polymers that are suitable for plastomeric use may include, for example, copolymers and terpolymers of propylene. These include copolymers with propylene, such as 1-octene or 1-nonene. The propylene polymer’s comonomer concentration may reach 35 wt. In some embodiments, it may be less than 1%. % to around 20 wt. % to about 20 wt. in some embodiments. % to approximately 10 wt. %. Preferably, the density polypropylene (e.g. propylene/??-olefin copolymer), may be 0.91 grams/cm3. In some embodiments, this can range from 0.85 to 0.88g/cm3 and in others, 0.85 g/cm3 or 0.87g/cm3. VISTAMAXX is the commercial name for suitable propylene polymers. ExxonMobil Chemical Co., Houston, Tex. ; FINA? (e.g. 8573) available from Atofina Chemicals of Feluy in Belgium; TAFMER Available from Mitsui Petrochemical Industries. Available from Mitsui Petrochemical Industries; and VERSIFY? No. 6,500,563 to Datta, et al. ; U.S. Pat. No. 5,539,056 to Yang, et al. ; and U.S. Pat. No. No.
Semi-crystalline polyolefins can be formed using any of the many known methods. Olefin polymers can be made using either a free radical (e.g. Ziegler-Natta) or a coordination catalyst (e.g., Ziegler?Natta). The olefin polymer should be formed using a single-site coordination catalyst such as a metallocene catalyst. This catalyst system creates ethylene copolymers where the comonomer is distributed randomly within a molecular chains and uniformly distributed across different molecular weight fractions. Metallocene-catalyzed polyolefins are described, for instance, in U.S. Pat. No. McAlpin and al. 5,571,619 ; U.S. Pat. No. 5,322,728 to Davis et al. ; U.S. Pat. No. 5,472,775 to Obijeski et al. ; U.S. Pat. No. 5,272,236 to Lai and al. ; and U.S. Pat. No. No. 6,090,325 is to Wheat, et. al. and are incorporated in their entirety herein by reference thereto. Examples of metallocene catalysts include bis(n-butylcyclopentadienyl)titanium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconium dichloride, bis(methylcyclopentadienyl)titanium dichloride, bis(methylcyclopentadienyl)zirconium dichloride, cobaltocene, cyclopentadienyltitanium trichloride, ferrocene, hafnocene dichloride, isopropyl(cyclopentadienyl,-1-flourenyl)zirconium dichloride, molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene, titanocene dichloride, zirconocene chloride hydride, zirconocene dichloride, and so forth. The molecular weight range of polymers produced using metallocene catalysts is typically very narrow. For instance, metallocene-catalyzed polymers may have polydispersity numbers (Mw/Mn) of below 4, controlled short chain branching distribution, and controlled isotacticity.”
“Of course other thermoplastic polymers can also be used to make the elastic film. They may be used alone or in combination with semi-crystalline polyolefins. A substantially amorphous block copolymer, which has at least two blocks each of a monoalkenylarene polymer and at least one block each of a saturated conjugated dene polymer, may be used. Monoalkenyl-arene blocks can include styrene, p?methyl styrene, p?tert-butyl-styrene, 1,3 dimethyl, p?methyl styrene, etc. as well as other monoalkenyl-polycyclic aromatic compounds such as vinyl anthrycene, vinyl naphthalene, and so forth. The most preferred monoalkenyl isnes are styrene or p-methyl. Conjugated diene blocks can include homopolymers with conjugated monomers, copolymers from two or more conjugated dene monomers, and copolymers containing one or more dienes with another monomer. The conjugated dienes should contain between 4 and 8 carbon atoms. These include 1,3 butadiene, 2-methyl-1.3 butadiene, isoprene, 2,3 dimethyl-1.3 butadiene, 1,3 pentadiene, piperylene, 1,3 hexadiene, and so on.
“The monoalkenylarene (e.g. polystyrene), blocks can vary in amount, but they typically comprise between 8 and 55 wt. % to approximately 55 wt. %, in certain embodiments, from around 10 wt. % to 35 wt. % and in certain embodiments, between about 25 M.% and about 35 wt. % of copolymer. Block copolymers that are suitable for use may include monoalkenyl-arene endblocks with a number of average molecular masses from approximately 5,000 to around 35,000, and saturated conjugated dene midblocks with a number of average molecular masses from about 20,000 up to about 170,000. The block polymer’s total average molecular weight may range from approximately 30,000 to around 250,000.
The amount of elastomeric Polymer(s), used in the film can vary, but it is usually about 30 wt. About 50 wt. in some embodiments, whereas a greater percentage of the film is used. % or more and in some embodiments about 80 wt. % or more of film. For example, semi-crystalline polyolefins (semi-crystalline polyolefins) make up about 70% of the film in one embodiment. The film may comprise a minimum of 5%, and in some cases as much as 80%. % or more of film. In some embodiments about 80 wt. % or more of film. Other embodiments may use blends of semicrystalline polyolefin(s), and elastomeric blocks copolymer(s). These block copolymers may comprise from approximately 5 to 50 wt. % to 50 wt. % in some embodiments, from around 10 wt. % to 40 wt. % to about 40 wt. in some embodiments. % to 35 wt. % of the mixture. The semi-crystalline polyolefin(s), may also make up about 50 wt. % to 95 wt. %, in certain embodiments, from around 60 wt. % to approximately 90 wt. % to about 90 wt. % to 85 wt. % of the mixture. You should be aware that the film may contain other elastomeric or non-elastomeric polymers.
The present invention’s elastic film may contain additional components, such as polymers. One embodiment of the elastic film includes a filler, for instance. Particulates and other materials can be added to the film extrusion mix. They will not chemically alter the film but may be evenly distributed throughout the film. Fillers can be used for a variety purposes. They may enhance film opacity or breathability (vapor-permeable, substantially liquid-impermeable). By stretching filled films, the polymer is forced to separate from the filler, making them breathable and creating microporous passageways. U.S. Pat. describes microporous elastic films that can be breathed. Nos. Nos. ; U.S. Pat. No. 5,932,497 to Morman, et al. ; U.S. Pat. No. No.
Fillers can have either a non-spherical or spherical shape, with average particle sizes ranging from about 0.1 to 7 microns. Calcium carbonate and various types of clay are all suitable fillers. If desired, a suitable coating such as stearic acids may be applied to the filler particles. The filler content can vary depending on how it is used, for example, from 25 to 75 wt. % to 75 wt. In some embodiments, % from around 30 wt. % to 70 wt. % to about 70 wt. in some instances. % to 60 wt. % of the film.”
The elastic film of the invention can be mono- or multilayered. Multilayer films can be made by co-extrusion, extrusion coating or any other conventional layering method. Multilayer films are usually composed of at least one layer (the base layer) and one layer (the skin layer), but can contain as many layers as you like. The multilayer film could be made from a base layer, one or more skin layers and a semi-crystalline, polyolefin base layer. The skin layer(s), in such embodiments can be made from any film-forming plastic. The skin layer(s), if desired, may contain a lower melting or softer layer of polymer. This makes the layer(s), more suitable for heat seal bonding layers to thermally bond the film to nonwoven webs. The skin layer may be made from an olefin or blends of it, as mentioned above. The present invention may also be used in combination with other polymers such as ethylene vinyl acetate and ethylene ethylacrylate.
The thickness of the skin layers is chosen to not significantly impair the film’s elastomeric properties. Each skin layer can be as little as 0.5% to 15% of the total film thickness, or, in certain embodiments, from 1% to 10%. Each skin layer can have a thickness of about 0.1 to 10 micrometers in some embodiments and from about 5 to about 5 micrometers in others. In some cases, it may be as thin as 1 to 2.5 micrometers. The base layer can also have a thickness of about 1 to 40 micrometers. In some embodiments, it may be between about 2 and about 25 micrometers. In some, it could be between about 5 and about 20 micrometers.
The properties of the film can vary depending on what you want. The film’s basis weight is typically about 100g per square meter before stretching. In some cases, it can be as high as 50-75g per square meter. The film’s basis weight is typically 60 grams per square meters or less upon stretching. In some embodiments, it can range from 15 to 35 grams per sq meter. The film can also be stretched to a thickness of about 1 to 100 micrometers in certain embodiments. In some embodiments, the thickness may range from 10 to 80 micrometers to 60 micrometers in others.
“II. “II.
The nonwoven web material can be made from monocomponent or multicomponent fibers. Monocomponent fibers are typically made from a combination of polymers or polymers extruded by one extruder. Multicomponent fibers, such as bicomponent or multicomponent fibers, are usually made from multiple polymers (e.g. bicomponent) extruded using separate extruders. The components can be placed in zones that are substantially constant across the fibers’ cross-section. You can arrange the components in any configuration you like: sheath-core or side-by-side, pie or island-in-thesea, bull’seye, three islands, bullseye, and other known arrangements. You can go on and on. U.S. Pat. describes a variety of methods to form multicomponent fibers. No. Taniguchi and colleagues. U.S. Pat. No. No. No. 5,108,820 to Kaneko, et al., U.S. Pat. No. 4,795,668 to Krueqe, et al., U.S. Pat. No. 5,382,400 to Pike, et al., U.S. Pat. No. No. No. No. Multicomponent fibers with different irregular shapes can also be made, as described in U.S. Pat. No. 5,277,976 to Hogle, et al., U.S. Pat. No. No. No. No. No. No. No. No.
“Even though any combination of polymers can be used, the polymers in the multicomponent fibres are usually made from thermoplastic materials that have different glass transitions or melting temperatures. This means that a first component (e.g. sheath), melts at a lower temperature than a second component, e.g. core. Multicomponent fibers can be softened or melted to form a tacky structure that, upon cooling, stabilizes the fibrous structure. Multicomponent fibers can have a range of 20 to 80 percent, with some embodiments ranging from 40% to 60% in terms of low melting polymer. Multicomponent fibers can have as much as 80% to 20% and, in certain embodiments, as much to 40% to 60%, depending on the weight of high melting polymer. KoSa Inc., Charlotte, N.C., has two types of sheath-core bicomponent fibres. They are T-255 (which uses a polyolefin sheath) and T-256 (which uses a co-polyester sheath). Other bicomponent fibers are also available from Fibervisions LLC in Wilmington, Del.
Staple fibers and continuous fibers can be used. One embodiment may use staple fibers that have a length of about 1 to 150 millimeters. In some embodiments, this ranges from approximately 5 to 50 millimeters. In some embodiments, about 10-40 millimeters. In some embodiments, about 10 to 40 millimeters. Some embodiments range from 10 to 25 millimeters. Carding techniques can be used to create fibrous layers using staple fibers, although this is not necessary. By placing the fibers in a picker, which separates them, the fibers can be made into a carded Web. The fibers are then sent to a combing unit or carding unit, which further breaks down and aligns them in the machine direction. This creates a machine-oriented fibrous web. To form a bonded nonwoven web, the carded web can be bonded using well-known techniques.
A spunbond web is another example of a multilayered structure. It is made on multiple spin banks machines. In these machines, a spin bank deposits fibers onto a layer of fibers that was previously deposited from a previous spinning bank. This individual spunbond nonwoven web can also be considered multi-layered. The nonwoven web’s layers of deposited fibers may be identical or different in weight, composition, type, size, crimp level, and/or form. Another example is a nonwoven web that may include multiple layers of spunbond web or carded webs, each individually produced and bonded together to make the web. As discussed above, these layers can differ in terms production method, basis weight and composition.
A nonwoven web material can also include a fibrous component, making it a composite. A nonwoven web can be entangled with another fibrous material using any of the many entanglement methods known in the art, such as hydraulic, air, mechanical, and others. One embodiment of the nonwoven web includes integral entanglement with cellulosic fibres by hydraulic entanglement. Hydraulic entanglement is a process that uses high pressure jet streams to entangle fibers and form a densely consolidated fibrous structure. U.S. Pat. reveals nonwoven webs that are hydraulically entangled using both continuous and staple fibers. No. No. No. 4,144,370 to Boulton. These are incorporated in their entirety by reference thereto herein for all purposes. U.S. Pat. 102/030/01 reveals hydraulically entangled composite webs of continuous fiber nonwoven webs and a pulp layer. No. 5,284,703 to Everhart, et al. U.S. Pat. No. No. The composite’s fibrous component may contain any amount of the resulting substrate. The composite may have a fibrous component that is greater than 50% in weight, or, in certain embodiments, as much as 60% to 90%. The nonwoven web can also contain less than 50% of the composite’s weight, and in certain embodiments as low as 10% to 40%.
“The nonwoven web material can be necked in one or several directions before lamination to the film according to the present invention, although this is not necessary. U.S. Patent describes suitable necking techniques. Nos. Nos. 2004/0121687 to Morman, et al. Alternativly, the nonwoven Web may be relatively inextensible in at most one direction before lamination to the film. The nonwoven web can optionally be stretched in any direction after lamination.
“The basis weight for nonwoven web material can vary from approximately 5 grams per square meter (‘gsm?). To 120 gsm in some embodiments, or from about 10 to 70 gsm in others. In some cases, to around 35 gsm in others. Multiple nonwoven web materials can have different basis weights.
“III. Lamination Technique”
“To simultaneously form apertures or bonds between the film, the nonwoven web material and the film, lamination can be achieved in the present invention using a patterned bonding method (e.g., ultrasonic bonding and thermal point bonding). Materials are supplied to a nip that is defined by at most one patterned roll. For example, thermal point bonding uses a nip that is formed between two rolls. At least one of these rolls must be patterned. Ultrasonic bonding uses a nip between a pattern roll and a Sonic Horn. The patterned roll, regardless of the method used, contains multiple raised bonding elements that simultaneously bond the film to the nonwoven material(s). These bonding elements also form apertures in film. You can tailor the size of the bonding elements to help form apertures in the film or increase bonding between the film, nonwoven material(s), and the film. The bonding elements have a large dimension, so they are often chosen to be relatively long. The bonding elements’ length dimension can range from 300 to about 5000 millimeters in some embodiments to 500 to about 4000, while in others, it may be as high as about 1000 to 2000 millimeters. The width dimension for bonding elements can also vary from 20 to 500 micrometers in some embodiments to 40 to 200 micrometers in others, and from 50 to 150 micrometers in some. The ‘element aspect ratio’ (the ratio of the length of an element to its width) is also important. The?element aspect ratio? (the ratio of the element’s length to its width) can range from 2 to 100 in some embodiments to 4 to 50 in others and from 5 to 20 in some other embodiments.
The nonwoven composite’s total bond area should be less than 50%, as determined by optical microscopic methods. In some cases, it may even be less than 30%. The bond density is typically higher than 50 bonds per square inches, with some embodiments ranging from 75 to 500 pin bonds per sq inch. The?S-weave’ is a suitable bonding pattern that can be used in the present invention. Pattern and is described in U.S. Pat. No. No. 5,964,742 McCormack, and al. S-weave patterns have a typical bonding element density between about 50 and about 500 bonding entities per square inch. In some embodiments, this may be as high as 75 to 150 bonding components per square inch. A suitable?S?weave? FIG. FIG. 2 shows S-shaped bonding elements 88 with a length dimension of?L? 2. This illustrates S-shaped bonding elements 88 having a length dimension?L? and a width dimension?W.? The?rib-knit’ bonding pattern is another suitable choice. Pattern and is described in U.S. Pat. No. No. Rib-knit patterns generally have a density of between 150 and about 400 bonding components per square inch. In some instances, it may be as high as 200 to 300 bonding elements. A suitable rib-knit is shown in FIG. FIG. 3 shows an example of a suitable?rib-knit? pattern. FIG. 3 shows bonding elements 90 and 91 that are oriented in different directions. Another suitable pattern is the “wire weave”. The pattern has a density of between 200 and 500 bonding elements/square inch. In some instances, it can have as high as 250 to 350 bonding elements/square inch. A suitable wire-weave is shown in FIG. FIG. 4 shows an example of a suitable?wire-weave? pattern. FIG. 4 illustrates bonding element 93 and bonding element 95 which are oriented in different directions. U.S. Pat. describes other bond patterns that could be used in this invention. No. 3,855,046 to Hansen et al. ; U.S. Pat. No. 5,962,112 to Haynes et al. ; U.S. Pat. No. 6,093,665 to Sayovitz et al. ; U.S. Pat. No. D375,844 Edwards, and al. ; U.S. Pat. No. D428,267 to Romano et al. ; and U.S. Pat. No. No.
“A proper bonding temperature (e.g. the temperature at which a heated roll is heated) will melt or soften the low-softening points elastomeric polymer(s). This will be done in regions that are adjacent to the bonding element. The softened elastomeric polmer(s), which may have been melted, can then flow and be displaced by bonding pressures such as those exerted on the bonding elements. The film around the apertures may also fusion to the nonwoven web material(s), creating an integral nonwoven composite. Because the elastomeric plasticmer(s), may physically entrap, adhere to the fibers at bond sites, sufficient bond formation may not be required without substantial softening the polymer(s). The nonwoven web material is not bonded to film or other materials in the areas that are directly adjacent (e.g. Above or below the apertures. The nonwoven web material is generally unapertured. However, it can develop small cuts or tears during processing.
“Another factor that affects concurrent aperture and bond formation, as stated, is the level of tension in the film during laminate. A decrease in film tension is often correlated with an increase in aperture size. Film tension too high can adversely affect the film’s integrity. To achieve the desired level of tension during lamination, most embodiments employ a stretch ratio between 1.5 and 7.0 in certain embodiments. In some embodiments, this is from 3.0 to 5.5. You can determine the stretch ratio by multiplying the final length of your film by its initial length. The draw ratio can also be approximated by the stretch ratio. This is calculated by dividing the final length of the film by its original length.
“Various embodiments and uses of the invention will be described in more detail. It should be noted that the above description is only an example and that other methods can be used in accordance with the present invention. Referring to FIG. FIG. 1 shows an example of a method to form a composite using an elastic film and nonwoven web material. The raw materials for the film, such as elastomeric polymer, can be dried mixed (i.e. without a solvent) before being added to an extrusion machine 40. Alternately, the raw materials can be mixed with a solvent. The materials are mixed in the melt in the hopper and compounded using any technique known, including batch and/or continuous compounding techniques, which employ, for instance, a Banbury mixer or Farrel continuous mixer as well as single and twin screw extruders and other screw extruders.
“Referring to FIG. “Referring again to FIG. 1, we show one method of forming uniaxially stretched films. The illustrated embodiment shows how the film 10 is stretched in machine direction. This is done by passing it through a film orientation unit (or machine direction orienter?). 44, which is commercially available at Marshall and Willams, Co. Providence, R.I. The MDO is equipped with a number of stretching rolls 46 which progressively stretch the film 10 in the machine’s direction. FIG. 1 shows four pairs of rolls 46. FIG. 1 shows four pairs of rolls 46. However, it is important to understand that the number of rolls can be increased or decreased depending on how stretchy the roll needs to be. Film 10 can be stretched using either one or multiple discrete stretching operations. You can also stretch the film 10 in different directions. The film can be held at its lateral edges with chain clips, and then transferred into a tenter oven. Chain clips may be used to draw the film in the cross-machine direction, achieving the desired stretch ratio.
A nonwoven web material can also be used to laminate the elastic film. The nonwoven web material can be simply unwound from a supply reel. As shown in FIG. A nonwoven web material 30, such as the one shown in FIG. 1, can be made in-line using spunbond extruders 48. The 48 extruders deposit 50 fibers onto a 52-gauge forming wire, which forms part of a continuous belt that runs around a series rolls. To maintain the fibers on forming wire 52, a vacuum (not illustrated) can be used if desired. The mat 54 formed by the spunbond fibers 50 may be optionally compressed using compaction rolls 56. A second material 30a, which is not required, may be laminated to elastic film 10. A second nonwoven web material, film or other material may be used as the second material 30a.
“Regardless, thermal bonding techniques can be used to laminate the material(s), to the elastic film. FIG. FIG. 1. For example, the materials 30a and 30a are directed at a nip between rolls 58 to laminate to the elastic film 10. The rolls 58 can contain multiple raised bonding elements or may be heated. The elastic film 10 is melted fused to nonwoven web materials 30 and 30, at a number of discrete bond locations 31. (See FIG. 7). This means that the elastomeric plastics in the film 10 can be softened and/or melt so as to physically trap fibers from the nonwoven web materials 30, and 30 a. The elastic film 10 may have a certain amount of tack to ensure that it adheres to the fibers during lamination. FIG. FIG. 7 shows that the bond sites 31 can be found proximate to (or near) a perimeter 37, defined by the corresponding apertures 33. These apertures are formed by the displacement of the film 10. By strengthening the area around the apertures 33, the specific location of bond sites 31 may improve the integrity of the resulting 32 composite. Thermal bonding is not a process that melts the nonwoven web material polymers 30 and 30a at sufficiently low temperatures to cause significant softening. The composite 32 will retain the physical properties of individual nonwoven web material materials (e.g. liquid permeability and softness, bulk and hand feel) better.
The composite 32 can then be wound up and stored on a takeup roll 60. The composite 32 can be kept under tension by using the same line velocity as one or more stretching rolls 46 to maintain tension. The composite 32 should be allowed to retract slightly before winding onto the take-up roller 60. You can achieve this by using a slower linear speed for the roll 60. The elastic film 10 is previously tensioned before lamination. It will then retract in its original direction and become shorter in the machine directions, buckling the composite or creating gathers. The elastic composite becomes extensible in the machine direction, so that any gathers or buckles may be pulled out flat. This will allow the elastic film 10 elongate.
“Which is not shown in FIG. “While not shown in FIG. 1, additional processing steps and/or finishing steps may be used without departing from its spirit and scope. To increase extensibility, the composite can optionally be mechanically stretched in cross-machine or machine directions. One embodiment may include a plurality of rolls with grooves in the CD or MD directions. U.S. Patent Application Publication Nos. explains such grooved satellite/anvil roll arrangements. 2004/0110442 to Rhim, et al. Rhim, et. al. 2006/0151914 Gerndt, and others are incorporated herein in full by reference thereto. The laminate can be run through multiple rolls with grooves in the CD or MD directions. The grooved rolls can be made of steel or another hard material (such a hard rubber).
“FIGS. “FIGS.5” 5-6 illustrates how groove rolls can incrementally stretch the composite. Satellite rolls 182 can engage an anvil rolls 184. Each of these rolls may have a plurality ridges 183 that define a plurality 185 of grooves 185. These grooves are positioned in the cross-machine direction. The grooves 185 are generally perpendicular with the direction of stretch. The grooves 185 are therefore oriented in the machine direction to stretch composite in the cross-machine directions. To stretch the composite in the machine direction, the grooves 185 can also be oriented in cross-machine. Satellite roll 182’s ridges 183 are intermingled with the grooves 185, 185, and 185 of anvil rolls 184. Satellite roll 182’s grooves 185 are intermingled with anvil roll184’s ridges 183.
The dimensions and parameters for the grooves 185, ridges 183 can have a significant effect on the extent of extensibility provided to the rolls 182 or 184. The number of grooves 185 on a roll can vary from approximately 3 to 15 per inch in some embodiments to about 5 or 12 per inch in others. In some embodiments, it may be between 5 and 10 per inch and in others, 5 and 10. A certain depth?D’ may be assigned to the grooves 185. This can range from 0.25 to about 1.25 centimeters and in some cases, from 0.4 to 0.6 centimeters. The peak-to-peak distance (?P?) is also important. The distance between grooves 185 is usually from about 0.01 to about 9.9 centimeters. In some embodiments, it may be as low as 0.2 centimeters to as 0.5 centimeters. The groove roll engagement distance E? The distance between grooves 185 & ridges 183 may be as high as 0.8 centimeters. In some embodiments, it could be 0.15 to 0.4 centimeters. The composite 32 (FIG. The composite 32 (FIG. To relax the composite and allow for extension, heat can be applied to it prior to or during incremental stretch. Any suitable heat application method is possible, including heated air, infrared heating, heated nipped roll, partial wrapping of laminate around one or several heated rolls or steam canisters. The grooved rolls can also be heated. You should also know that other arrangements of grooved rolls are equally acceptable, such as two grooved rolling positioned adjacently to each other.”
Other than the grooved rolls described above, there are other methods that can mechanically stretch the composite. The composite could be stretched by passing it through a tenter frame. These tenter frames are well-known in the art. They are described in U.S. Patent Application Publication No. 2004/0121687 to Morman, et al. The composite can also be necked. U.S. Patent. Describes suitable techniques for necking the composite. Nos. Nos. 2004/0121687 Morman, et. al. are all incorporated herein in full by reference thereto for any purposes.
The nonwoven composite of this invention can be used in many different applications. The nonwoven composite can be used as an absorbent article, as we have already mentioned. An ?absorbent article? An?absorbent article? is any article that can absorb water or other fluids. Some examples of absorbent items include personal care absorbent article, including diapers and training pants, absorbent underpants and feminine hygiene products (e.g. sanitary napkins), swimwear, baby wipes and so forth; medical absorbent article, such as garments and fenestration material, underpads and bedpads as well as bandages, bandages, absorbent drapes and medical wipes; food service wipers; clothing articles and so on. The art of making absorbent articles is well-known to those who are skilled in the field. An absorbent article may contain a substantially liquid-impermeable (e.g. the outer cover), or a liquid permeable (e.g. bodyside liner, surge, etc.). An absorbent core is also available.
“In one embodiment, the nonwoven composition of the present invention can be used to form an absorbent article’s liquid-permeable coating (e.g. bodyside liner, surge layers). The elastic film is bonded with the nonwoven web material at discrete bond points located around the perimeter of the apertures. The conditions of lamination can be controlled to ensure that the nonwoven web material is not substantially bonded (e.g. not substantially melt fused together), in the areas adjacent to the apertures. The elastic film can be placed between two nonwoven materials to create melt bond sites. The lamination conditions may allow the nonwoven web materials to be generally unapertured in areas adjacent to the elastic film apertures. These generally unbonded and unapertured areas in the nonwoven web materials (s) increase the composite’s ability to be used as a liquid-permeable coating in an absorbent article. Because the nonwoven material is not fused at the film apertures, liquids may flow more easily through the material and into the aperture. The nonwoven web material’s lack of significant aperturing allows it to maintain other desirable properties, such as bulk, softness, and handfeel
“Besides liquid-permeable materials (e.g., liners, surge layers, etc. The nonwoven composite of this invention can be used in many other ways, including providing elastic waists, leg cuff/gasketings, stretchable ears, side panels, outer covers, and any other component with elastic properties.
We will now discuss in greater detail the various embodiments of absorbent articles that can be made according to the invention. FIG. 8 shows an example of an absorbent article. 8 is a diaper 201. The invention can also be used in diapers 201, as well as other absorbent articles such as incontinence articles and diaper pants. The diaper 201 in the illustrated embodiment is shown to have an hourglass shape, unfastened. Other shapes can be used, however, including a rectangular, T-shape or I-shape. The diaper 201 is made up of a number of components. These include an outer cover 217 and bodyside liner205. An absorbent core 203 and surge layer207. However, other layers can be used in accordance with the present invention. The FIG. 8 diagram also shows that one or more layers may be eliminated. 8. In certain embodiments, the present invention may also allow for 8 to be removed.
The bodyside liner (205) is used to protect the skin from liquids contained in the absorbent core (203). The liner 205 is a bodyfacing material that is usually soft, flexible, and non-irritating. The liner 205 is typically less hydrophilic than its absorbent core 203, so its surface stays relatively dry for the wearer. The liner 205 could be liquid-permeable, allowing liquids to easily penetrate its thickness as mentioned above. U.S. Pat. describes exemplary liner constructions that include a nonwoven web. No. 5,192,606 to Proxmire, et al. ; U.S. Pat. No. 5,702,377 to Collier, IV, et al. ; U.S. Pat. No. 5,931,823 to Stokes, et al. ; U.S. Pat. No. 6,060,638 to Paul, et al. ; and U.S. Pat. No. 6,150,002 to Varona; U.S. Patent Application Publication Nos. 2004/0102750 was given to Jameson; 2005/0054255 was given to Morman, and others. ; and 2005/0059941 (Baldwin, et. al.) are all incorporated herein in full by reference thereto. The present invention’s nonwoven composite is included in one embodiment of the liner.
“As shown in FIG. 8 shows that the diaper 201 can also have a surge layer (207), which helps to diffuse and decelerate surges or gushes that are quickly introduced into the absorbent center 203. The surge layer 207 is designed to quickly accept and temporarily hold the liquid before releasing it into storage or retention areas of the absorbent center 203. The illustrated embodiment shows the surge layer 207 interposed between the inwardly facing surface 218 of the bodyside liners 205 and absorbent core 203. Alternately, the surge layer may be found on the outwardly facing surface 218 in the bodyside liners 205. The surge layer 207 is usually made from highly liquid-permeable substances. U.S. Pat. 207 provides examples of suitable surge layers. No. 5,486,166 to Ellis, et al. U.S. Pat. No. No. The present invention’s nonwoven composite is included in the surge layer 207 of one embodiment.
The outer cover 217 is usually made from a material that is impermeable to liquids. The outer cover 217 can be made from either a flexible liquid-impermeable plastic film or another thin plastic film. One embodiment of the outer cover 217 is made from a polyethylene sheet with a thickness between 0.01 and 0.05 millimeters. Although the film is impermeable for liquids, it can be permeable to gases, water vapor, and other gases (i.e., breathable). The outer cover 217 prevents liquid exudates, but allows vapors to escape the absorbent core203. The outer cover 217 can be made from a polyolefin laminated to nonwoven web if you prefer a clothier feel. A stretch-thinned, polypropylene film can be thermally laminated to form a spunbond web of phenol fibers.
The diaper 201 could also include other components that are well-known in the art. The diaper 201 could also include a substantially hydrophilic tissue wrappingsheet (not illustrated), which helps to maintain the integrity and fibrous structure of absorbent core203. The tissue wrapsheet is usually placed around the absorbent core203, covering at least two of its major facing surfaces. It is made from an absorbent cellulosic substance such as creped wadding, or a high-wet-strength material. A tissue wrapsheet can be designed to distribute liquid quickly over the absorbent fibers of 203. To effectively trap the absorbent core, 203, the wrapsheet material may be attached to the wrapsheet on the other side of the fibrous bulk. The diaper 201 may also have a ventilation layer (not illustrated) that is placed between the absorbent core203 and the outer covering 217. The ventilation layer can be used to insulate the outer covering 217 from the absorbent 203 and reduce dampness in the 217. One example of such ventilation layers is a nonwoven web laminated with a breathable layer, as described in U.S. Pat. No. No.
“In some embodiments, the diaper201 may include a pair or ears (not shown), which extend from the diaper’s side edges 232 into the waist region. Side panels can be integrated with a particular diaper component. The side panels can be formed from either the outer cover 217, or the material used to create the top surface. Alternate configurations include members that are connected to the outer covering 217, top surface, between outer cover 217 & top surface or other configurations. The elastic nonwoven composite of this invention can be used to make the side panels elasticized or made elastomeric. Examples of absorbent articles that have elasticized side panels and selectly configured fastener buttons are described in PCT Patent Application (WO 95/16425) to Roessler; U.S. Patent. No. 5,399,219 to Roessler et al. ; U.S. Pat. No. No. No. No.
FIG. 8 shows that the diaper 201 could also have a pair containment flaps, 212 which are designed to prevent and contain the lateral flow exudates. The containment flaps may be found along the laterally opposing side edges 232 of bodyside liner205, adjacent to the sides of the absorbent center 203. The containment flaps may be extended longitudinally along the length of absorbent core203 or only partially. The containment flaps, 212 may be placed in a specific location along the sides 232 and 210 of diaper 201. To better contain body exudates, one embodiment of the containment flaps212 extends along the length of the absorbent 203. These containment flaps 212 can be used to protect the body exudates. U.S. Pat. 212 describes suitable constructions and arrangements of containment flaps 212. No. No.
The diaper 201 can be elasticized with appropriate elastic members to improve fit and reduce body exudates leakage. FIG. 8 shows an example of this, 8 shows an example of leg elastics 206 that may be used to tension the diaper 201’s side margins. These elasticized leg bands can close fit around the legs to reduce leakage, improve comfort, and enhance the appearance of the diaper. To provide elasticized waistbands, elasticized diaper 201 may include waist elastics 208. The waist elastics of 208 are designed to fit comfortably around the waist. The present invention’s elastic nonwoven composite is compatible with the leg elastics (206) and waist elastics (208). Laminate sheets are a good example of such materials. They can either be attached to or comprise the outer cover 217, so that they impart elastic constrictive forces.
“The diaper 201 could also contain one or more fasteners 233. FIG. 2 illustrates two flexible fasteners (230). FIG. 8 shows two flexible fasteners 230 placed on opposite sides of the waist region to create a waist opening as well as a pair of leg openings around the wearer. Although the shape of fasteners 230 can vary widely, they may be rectangular, square, circular, triangular, oval, linear, or other shapes. For example, the fasteners can include a hook-and?loop material, buttons and pins, snaps or adhesive tape fasteners. They also may contain cohesives and fabric-and?loop fasteners. One embodiment includes a piece of hook material attached to the flexible backing.
“The different regions and/or parts of the diaper 201 can be attached using any known attachment mechanism such as adhesives, ultrasonics, thermal bonds, or other. You can use hot melt adhesives or pressure-sensitive adhesives as suitable adhesives. The adhesive can be used as a single layer or a pattern. It can also be applied in a swirled or dot pattern. The illustrated embodiment shows the outer cover 217 and the bodyside liner205 being attached to one another and the absorbent core 203. This is done using adhesive. Alternately, the absorbent core may be attached to the outer cover 217 with conventional fasteners such as buttons or hook and loop fasteners. Other components such as the waist elastic members 208, the leg elastic members 226 and fasteners 227 can also be attached to the diaper 201 with any attachment method.
“Although different configurations of diapers have been described, it is important to understand that the present invention also covers other diaper and absorbent articles configurations. The present invention does not only cover diapers. Any other absorbent article can be made in accordance to the present invention. This includes, but is not limited, to personal care absorbent articles such as diapers, training pants, absorbent underpants and feminine hygiene products (e.g., sanitary nappy pads), swimwear, baby wipes and so forth; medical absorbent items such as medical absorbent articles such as clothing, garments, fenestration material, underpads and bandages, absorbent drapes and medical wipes; food service wis; and clothing articles U.S. Pat. provides several examples of absorbent articles. No. 5,649,916 to DiPalma, et al. ; U.S. Pat. No. No. No. No. Other suitable articles can be found in U.S. Patent Application Publication No. 2004/0060112A1 to Fell et al. and U.S. Pat. No. 4,886,512 to Damico et al. ; U.S. Pat. No. No. ; U.S. Pat. No. Fell et al. ; and U.S. Pat. No. No.
“The following examples may help you better understand the invention.”
“Test Methods”
“Cycle Testing”
“The materials were subject to cyclical testing in order to determine percent set and load loss. One-cycle testing was used to determine 150% defined length. The sample size for this test was 3 inches cross-machine and 6 inches in machine directions. The grip size was 3 inches wide. The grip separation was four inches. The sample were loaded so that the machine direction was vertical. The preload was approximately 10 to 15%. The sample was pulled to 100% elongation at 20 inches per hour. After that, the sample returned to zero at 20 inches per second. All the results are from the first cycle. Testing was performed on a Sintech Corp. constant-rate of extension tester 2S equipped with a RenewMTS mongoose (control) and TESTWORKS 4.07b software. (Sintech Corp., Cary, N.C.). The tests were done under ambient conditions.
“Air Permeability:”
“Air permeability was measured using the?Frazier permeability?. This is the standard cubic feet per hour of air flow across a material. It is determined as the square foot of material with an average air pressure differential of 0.5 in water (125 Pa). The test was done at ambient conditions.
“Peel Strength:”
“Strain:”
“The materials were tested for elongation and strain. The sample was measured in inches across the machine direction and 7 inches in cross-machine directions. Intermeshing grips were used to ensure that the material did not slip during testing. The grip separation was four inches. The sample were loaded so that the sample’s machine direction was in the vertical direction. The preload was approximately 10 to 15%. After the sample was pulled to produce 2000 grams of tension, the test was stopped. The speed of the test was 500 millimeters per hour for strain or extension. The test measured the strain or elongation in percent starting at 2000 grams tension in the material. Sintech Corp. constant-rate of extension tester 2S was used for testing. It was controlled by a RenewMTS mongoose (controller), and TESTWORKS 4.07b software. (Sintech Corp., Cary, N.C.). The tests were done under ambient conditions.
“EXAMPLE 1”
“FIGS. 9-17 are scanning electron microphotographs showing the resulting sample. FIG. FIG. 9 shows, for example, the roughly rectangular apertures 333 formed by the bars in the rib-knit design (See e.g. FIG. FIG. 3 shows the rectangular apertures 333 a formed by the bars of the rib-knit pattern (See e.g., FIG. FIG. 10 shows the circular apertures 333 formed by the pins in the rib-knit design. FIG. shows a perspective view of the apertures. 11. FIGS. 14-17. The microphotographs not only illustrate apertures but also show the melt fusion between the elastic film and the fibers of nonwoven webs. FIGS. 12-13 show an example of this. FIGS. 12-13 depict an elastic film 310 which is melt fused into a nonwoven web at discrete bond site 331 Apertures 333 define the perimeter of bond sites 331 and locate them proximately to each other.
“EXAMPLE 2”
“EXAMPLE 3”
Summary for “Nonwoven composite containing an apertured Elastic film”
Elastic composites are often used in products such as diapers, training pants and garments. To improve their ability to fit better to the contours and body. The elastic composite could be made from an elastic film combined with one or more nonwoven Web materials. The film may be stretched so that the nonwoven material can adhere to it. The elastic composite will stretch to the point that the nonwoven web material between the bond points allows the elastic film’s length to increase. Elastic films can often feel tacky or rubbery to the touch. This makes them uncomfortable and unattractive for the skin. To improve these properties, there have been attempts to open the composite. U.S. Pat. No. 6,830,800 to Curro, et al. This describes a technique in which elastic material is joined between two Webs. The bond sites are aligned so that the elastic material is apertured. There is still much to be done, despite the many benefits.
“In accordance to one embodiment of the invention, a method for forming a nonwoven-composite is disclosed. This method involves forming an elastic material from a polymer mixture and passing it and a nonwoven web through a nip made by at least one pattern roll. The film and nonwoven web materials are melt fused at the nip. At the apertures, the film is simultaneously formed without significantly softening its polymer. Each aperture has a minimum of 200-5000 micrometers in length. The film is also under tension at a stretch ratio between 1.5 and 1.5 in the machine direction at each nip.
“According to another embodiment of the invention, a nonwoven composition is disclosed. It comprises an elastic film that has been positioned adjacent and melt fused with a nonwoven web at a plurality discrete bond locations. The elastic film creates a number of apertures around which the discrete bond site are located. Each aperture has a minimum of 200-5000 micrometers in length.
“Another feature and aspect of the present invention is described in greater detail below.”
“Definitions”
“Nonwoven web” is the term used herein. A web that is composed of individual threads or fibers interwoven in a structured manner, but not in the same way as a knitted fabric. Some examples of nonwoven fabrics and webs that are suitable include: meltblown webs; spunbond webs; bonded carded Webs; coform webs; hydraulically entangled Webs, and so on.
“Meltblown web” is the term used herein. A nonwoven web is a nonwoven material that has been formed using molten thermoplastic material extruded through several fine, often circular, die capillaries. The molten fibers are then ejected into high velocity gas (e.g. air) streams which attenuate the molten thermoplastic material’s fibers to reduce their diameter. The meltblown fibers are then carried by the high-velocity gas stream and deposited on a collecting area to form a web consisting of randomly distributed meltblown fibers. This process is described in U.S. Pat. No. No. Meltblown fibers can be either microfibers that are substantially continuous, or discontinuous, usually smaller than 10 microns in size, and tacky when they are deposited onto a collecting area.
“Spunbond web” is the term used herein. A web with small diameter, substantially continuous fibers is generally referred to as?spunbond web? The fibers are made by extruding molten thermoplastic material through a number of fine, often circular, capillaries from a spinnerette. The diameter of the extruded fibres is then rapidly reduced by, for instance, eductive drawing or other well-known spinningbonding methods. U.S. Pat. explains and illustrates how spunbond webs are made. No. 4,340,563 to Appel, et al., U.S. Pat. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. When spunbond fibers are deposited onto a collecting area, they are not tacky. Spunbond fibers can sometimes have diameters of less than 40 microns and may be between 5 and 20 microns.
“Machine direction” is a term that’s commonly used in this document. “Machine direction” or “MD?” The direction in which a material was produced is generally referred to as?cross-machine direction? Cross-machine direction is also known as? The term?cross-machine direction? or?CD? Refers to the direction perpendicular the machine direction.
“As used herein, the terms ‘extensible? “Extensibility” or “extensible?” A material that can stretch or extend in the direction of an applied force of at least 25%, in some cases about 50% and in others at least 75% of its relaxed length. An extensible material doesn’t necessarily have recovery properties. An elastomeric materials, for example, is an extensible material with recovery properties. Meltblown webs can be extensible but may not have recovery properties. Therefore, they could be an extensible, elastic material.
“Elastomeric” is the term used herein. “Elastomeric” and “elastic?” The material is elastic when it can be stretched in one direction (such the CD direction) and then contracts/returns to its original dimensions upon the release of the stretching force. A stretched material might have a length that is at most 50% longer than its relaxed untretched length. However, it will recover to a minimum of 50% of its original length after the stretching force is released. One (1) inch of material, which is stretchable to at most 1.50 inches, would be an example. It will then recover to a length not exceeding 1.25 inches after the stretching force has been released. It is desirable that the material contract or recovers at minimum 50%. Even more desirable, it should recover at least 80%.
“As used herein the terms ‘necked’? “necked material” and “necked?” Generally, a material that has been drawn in at most one dimension (e.g. machine direction) to reduce its transverse dimensions (e.g. cross-machine direction). This allows the material to be pulled back to its original width when the drawing force is removed. The basis weight of necked materials is generally higher per unit area than that of un-necked materials. The basis weight of the necked material should be approximately the same as that of the un-necked. This is different from a film whose orientation is altered by thinning and reducing the basis weight. Necking involves taking material from a supply roll, and passing it through a brake roll assembly at a certain linear speed. The material is drawn by a take-up or nip that operates at a higher linear speed than the brake roll and creates the tension necessary to lengthen and neck it.
“The term thermal point bonding is used herein. It is a process that involves passing material between two rolls (e.g. calender roll and anvil roll), which can or cannot be patterned. Usually, one or both of these rolls are heated.
“Ultrasonic bonding” is the term used herein. The term “ultrasonic bonding” is used to describe a process that involves passing material between a sonic-horn and a pattern roll (e.g. anvil roll). U.S. Pat. describes ultrasonic bonding using a stationary horn and rotating patterned anvil rolls. No. 3,939,033 to Grgach, et al., U.S. Pat. No. No. No. No. U.S. Pat. describes ultrasonic bonding using a rotaryhorn with a rotating pattern anvil roll. No. No. No. No. No. No. 5,817199 to Brennecke, and others. These documents are incorporated in their entirety herein by reference thereto for any purposes. Any other ultrasonic bonding method may be used in accordance with the present invention.
“Reference will now be made in detail at various embodiments the invention. One or more examples are given below. Each example is given for explanation purposes only and not to limit the invention. It will be obvious to anyone skilled in the art that the invention can be modified and adapted without departing from its scope or spirit. To illustrate one example, features described in one embodiment may be applied to another embodiment. This is why the invention covers such modifications and variations.
“The present invention is directed at a nonwoven composite that includes an elastic film laminated with one or more nonwoven Web materials. To form the composite, the film is passed through a nip. This bonding process bonds the film to the nonwoven material(s). The elastic film also forms apertures. Apertures are small enough to give the composite desired texture, softness and hand feel without affecting its elastic properties. The present invention allows for selective control of certain parameters such as the film content, bonding pattern and degree of film tension. The present invention’s various embodiments will be discussed in greater detail.
“I. Elastic Film.”
“The elastic film of this invention is made from one or more melt-processable elastomeric polymers, i.e. thermoplastic. The present invention may be used with any of the following thermoplastic elastomeric elastomeric polmers: elastomeric polyesters; elastomeric urethanes; elastomeric amides; elastomeric copolymers; elastomeric olefins; and so forth. One embodiment uses elastomeric semicrystalline polyolefins because of their unique combination in mechanical and elastic properties. These semi-crystalline polyolefins’ mechanical properties allow for films to easily aperture during thermal bonding but still retain their elasticity.
Polyethylene, polypropylene and blends or copolymers of them are examples of semi-crystalline polyolefins. One particular embodiment uses a copolymer between ethylene and an “olefin”, such as C3-C20 or C3?C12??olefin. The?-olefins that are suitable may be either linear or branched (e.g. one or more C1?C3 alkyl branches or an aryl group). Specific examples include 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-substituted I-decene; 1-dodecene; and styrene. 1-butene; 1-hexene; and 1-octene are all desirable?-olefin copolymers. These copolymers can have a ethylene content of about 60 mole% to 99 mole%. In some embodiments, it may range from about 80 mole% to approximately 98.5 mole% and in others, from about 87 to 97.5 mole%. The?-olefin contents can also vary from approximately 1 mole% to around 40 mole% in some embodiments to about 1.5 mole% to 15 mole% and in others from about 2.5 mole% to 13 mole% in some embodiments.
The density of polyethylene can vary depending on the type of plastic used, but it generally ranges between 0.85 and 0.96 grams per cubic cm (?g/cm3?)? For example, polyethylene?plastomers can have a density of 0.85 to 0.91g/cm3. The same goes for?linear low-density polyethylene. (?LLDPE?) (?LLDPE?) (?LOPE?) (?LOPE?) (?HOPE?) (?HOPE?) ASTM 1505 may be used to measure densities.
“Particularly appropriate polyethylene copolymers” are those that are linear. Or?substantially linear. The term “substantially linear” is used. The term?substantially linear? refers to the fact that in addition to the short chains branches due to comonomer incorporation the ethylene polymer also has long chain branches in the polymer backbone. What is long chain branching? A chain with at least 6 carbons is considered long chain branching. Each long chain branch can have the same comonomer distribution and length as the polymer backingbone. Preferably substantially linear polymers can be substituted with 0.01 long chains branches per 1000 atoms to 1 longer chain branch for 1000 atoms and, in some embodiments, with 0.05 long branch per 1000 atoms to 1 extra long branch per 1,000 atoms. The term “linear” is a different term to the term “substantially linear”. The term?linear? refers to a polymer that lacks demonstrable or measurable long chain branches. This means that the average number of long chain branches per 1000 carbons in the substituted polymer is less than 0.01.
The length and the amount of the??-olefin are both factors that determine the density of a linear line of ethylene/?olefin copolymer. The copolymer’s density is affected by the length and amount of??-olefin. While not required, linear polyethylene?plastomers are desirable. are particularly desirable in that the content of ?-olefin short chain branching content is such that the ethylene copolymer exhibits both plastic and elastomeric characteristics?i.e., a ?plastomer.? The density of plastomers resulting from polymerization with??olefin-comonomers is lower than that of polyethylene thermoplastic copolymers (e.g. LLDPE), but close to or overlapping that of an elastic material. The density of polyethylene plastomer can range from 0.85 to 0.88 grams per cubic cm3 (g/cm3) in some embodiments and from 0.85 g/cm3 up to 0.87g/cm3 in others. Although plastomers have a similar density to elastomers they are generally more crystallin and less sticky than elastomers. They can also be made into pellets that are not-adhesive, relatively free-flowing, and may even be non-adhesive.
“The preferred plastomers for the invention are the ethylene-based copolymer plastic plastomers that are available under the name EXACT?” ExxonMobil Chemical Company, Houston, Tex. You can also find other suitable polyethylene plastomers under the name ENGAGE. ENGAGE? und AFFINITY? Dow Chemical Company of Midland (Mich.) Other suitable ethylene polymers can also be purchased from Dow Chemical Company, under the DOWLEX designation. (LLDPE and ATTANE). (ULDPE). U.S. Pat. No. 4,937,299 to Ewen and al. ; U.S. Pat. No. 5,218,071 to Tsutsui et al. ; U.S. Pat. No. 5,272,236 to Lai, et al. ; and U.S. Pat. No. No.
“Of course the invention is not limited to ethylene polymers. Propylene polymers can also be used as semi-crystalline polyolefins. Propylene polymers that are suitable for plastomeric use may include, for example, copolymers and terpolymers of propylene. These include copolymers with propylene, such as 1-octene or 1-nonene. The propylene polymer’s comonomer concentration may reach 35 wt. In some embodiments, it may be less than 1%. % to around 20 wt. % to about 20 wt. in some embodiments. % to approximately 10 wt. %. Preferably, the density polypropylene (e.g. propylene/??-olefin copolymer), may be 0.91 grams/cm3. In some embodiments, this can range from 0.85 to 0.88g/cm3 and in others, 0.85 g/cm3 or 0.87g/cm3. VISTAMAXX is the commercial name for suitable propylene polymers. ExxonMobil Chemical Co., Houston, Tex. ; FINA? (e.g. 8573) available from Atofina Chemicals of Feluy in Belgium; TAFMER Available from Mitsui Petrochemical Industries. Available from Mitsui Petrochemical Industries; and VERSIFY? No. 6,500,563 to Datta, et al. ; U.S. Pat. No. 5,539,056 to Yang, et al. ; and U.S. Pat. No. No.
Semi-crystalline polyolefins can be formed using any of the many known methods. Olefin polymers can be made using either a free radical (e.g. Ziegler-Natta) or a coordination catalyst (e.g., Ziegler?Natta). The olefin polymer should be formed using a single-site coordination catalyst such as a metallocene catalyst. This catalyst system creates ethylene copolymers where the comonomer is distributed randomly within a molecular chains and uniformly distributed across different molecular weight fractions. Metallocene-catalyzed polyolefins are described, for instance, in U.S. Pat. No. McAlpin and al. 5,571,619 ; U.S. Pat. No. 5,322,728 to Davis et al. ; U.S. Pat. No. 5,472,775 to Obijeski et al. ; U.S. Pat. No. 5,272,236 to Lai and al. ; and U.S. Pat. No. No. 6,090,325 is to Wheat, et. al. and are incorporated in their entirety herein by reference thereto. Examples of metallocene catalysts include bis(n-butylcyclopentadienyl)titanium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconium dichloride, bis(methylcyclopentadienyl)titanium dichloride, bis(methylcyclopentadienyl)zirconium dichloride, cobaltocene, cyclopentadienyltitanium trichloride, ferrocene, hafnocene dichloride, isopropyl(cyclopentadienyl,-1-flourenyl)zirconium dichloride, molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene, titanocene dichloride, zirconocene chloride hydride, zirconocene dichloride, and so forth. The molecular weight range of polymers produced using metallocene catalysts is typically very narrow. For instance, metallocene-catalyzed polymers may have polydispersity numbers (Mw/Mn) of below 4, controlled short chain branching distribution, and controlled isotacticity.”
“Of course other thermoplastic polymers can also be used to make the elastic film. They may be used alone or in combination with semi-crystalline polyolefins. A substantially amorphous block copolymer, which has at least two blocks each of a monoalkenylarene polymer and at least one block each of a saturated conjugated dene polymer, may be used. Monoalkenyl-arene blocks can include styrene, p?methyl styrene, p?tert-butyl-styrene, 1,3 dimethyl, p?methyl styrene, etc. as well as other monoalkenyl-polycyclic aromatic compounds such as vinyl anthrycene, vinyl naphthalene, and so forth. The most preferred monoalkenyl isnes are styrene or p-methyl. Conjugated diene blocks can include homopolymers with conjugated monomers, copolymers from two or more conjugated dene monomers, and copolymers containing one or more dienes with another monomer. The conjugated dienes should contain between 4 and 8 carbon atoms. These include 1,3 butadiene, 2-methyl-1.3 butadiene, isoprene, 2,3 dimethyl-1.3 butadiene, 1,3 pentadiene, piperylene, 1,3 hexadiene, and so on.
“The monoalkenylarene (e.g. polystyrene), blocks can vary in amount, but they typically comprise between 8 and 55 wt. % to approximately 55 wt. %, in certain embodiments, from around 10 wt. % to 35 wt. % and in certain embodiments, between about 25 M.% and about 35 wt. % of copolymer. Block copolymers that are suitable for use may include monoalkenyl-arene endblocks with a number of average molecular masses from approximately 5,000 to around 35,000, and saturated conjugated dene midblocks with a number of average molecular masses from about 20,000 up to about 170,000. The block polymer’s total average molecular weight may range from approximately 30,000 to around 250,000.
The amount of elastomeric Polymer(s), used in the film can vary, but it is usually about 30 wt. About 50 wt. in some embodiments, whereas a greater percentage of the film is used. % or more and in some embodiments about 80 wt. % or more of film. For example, semi-crystalline polyolefins (semi-crystalline polyolefins) make up about 70% of the film in one embodiment. The film may comprise a minimum of 5%, and in some cases as much as 80%. % or more of film. In some embodiments about 80 wt. % or more of film. Other embodiments may use blends of semicrystalline polyolefin(s), and elastomeric blocks copolymer(s). These block copolymers may comprise from approximately 5 to 50 wt. % to 50 wt. % in some embodiments, from around 10 wt. % to 40 wt. % to about 40 wt. in some embodiments. % to 35 wt. % of the mixture. The semi-crystalline polyolefin(s), may also make up about 50 wt. % to 95 wt. %, in certain embodiments, from around 60 wt. % to approximately 90 wt. % to about 90 wt. % to 85 wt. % of the mixture. You should be aware that the film may contain other elastomeric or non-elastomeric polymers.
The present invention’s elastic film may contain additional components, such as polymers. One embodiment of the elastic film includes a filler, for instance. Particulates and other materials can be added to the film extrusion mix. They will not chemically alter the film but may be evenly distributed throughout the film. Fillers can be used for a variety purposes. They may enhance film opacity or breathability (vapor-permeable, substantially liquid-impermeable). By stretching filled films, the polymer is forced to separate from the filler, making them breathable and creating microporous passageways. U.S. Pat. describes microporous elastic films that can be breathed. Nos. Nos. ; U.S. Pat. No. 5,932,497 to Morman, et al. ; U.S. Pat. No. No.
Fillers can have either a non-spherical or spherical shape, with average particle sizes ranging from about 0.1 to 7 microns. Calcium carbonate and various types of clay are all suitable fillers. If desired, a suitable coating such as stearic acids may be applied to the filler particles. The filler content can vary depending on how it is used, for example, from 25 to 75 wt. % to 75 wt. In some embodiments, % from around 30 wt. % to 70 wt. % to about 70 wt. in some instances. % to 60 wt. % of the film.”
The elastic film of the invention can be mono- or multilayered. Multilayer films can be made by co-extrusion, extrusion coating or any other conventional layering method. Multilayer films are usually composed of at least one layer (the base layer) and one layer (the skin layer), but can contain as many layers as you like. The multilayer film could be made from a base layer, one or more skin layers and a semi-crystalline, polyolefin base layer. The skin layer(s), in such embodiments can be made from any film-forming plastic. The skin layer(s), if desired, may contain a lower melting or softer layer of polymer. This makes the layer(s), more suitable for heat seal bonding layers to thermally bond the film to nonwoven webs. The skin layer may be made from an olefin or blends of it, as mentioned above. The present invention may also be used in combination with other polymers such as ethylene vinyl acetate and ethylene ethylacrylate.
The thickness of the skin layers is chosen to not significantly impair the film’s elastomeric properties. Each skin layer can be as little as 0.5% to 15% of the total film thickness, or, in certain embodiments, from 1% to 10%. Each skin layer can have a thickness of about 0.1 to 10 micrometers in some embodiments and from about 5 to about 5 micrometers in others. In some cases, it may be as thin as 1 to 2.5 micrometers. The base layer can also have a thickness of about 1 to 40 micrometers. In some embodiments, it may be between about 2 and about 25 micrometers. In some, it could be between about 5 and about 20 micrometers.
The properties of the film can vary depending on what you want. The film’s basis weight is typically about 100g per square meter before stretching. In some cases, it can be as high as 50-75g per square meter. The film’s basis weight is typically 60 grams per square meters or less upon stretching. In some embodiments, it can range from 15 to 35 grams per sq meter. The film can also be stretched to a thickness of about 1 to 100 micrometers in certain embodiments. In some embodiments, the thickness may range from 10 to 80 micrometers to 60 micrometers in others.
“II. “II.
The nonwoven web material can be made from monocomponent or multicomponent fibers. Monocomponent fibers are typically made from a combination of polymers or polymers extruded by one extruder. Multicomponent fibers, such as bicomponent or multicomponent fibers, are usually made from multiple polymers (e.g. bicomponent) extruded using separate extruders. The components can be placed in zones that are substantially constant across the fibers’ cross-section. You can arrange the components in any configuration you like: sheath-core or side-by-side, pie or island-in-thesea, bull’seye, three islands, bullseye, and other known arrangements. You can go on and on. U.S. Pat. describes a variety of methods to form multicomponent fibers. No. Taniguchi and colleagues. U.S. Pat. No. No. No. 5,108,820 to Kaneko, et al., U.S. Pat. No. 4,795,668 to Krueqe, et al., U.S. Pat. No. 5,382,400 to Pike, et al., U.S. Pat. No. No. No. No. Multicomponent fibers with different irregular shapes can also be made, as described in U.S. Pat. No. 5,277,976 to Hogle, et al., U.S. Pat. No. No. No. No. No. No. No. No.
“Even though any combination of polymers can be used, the polymers in the multicomponent fibres are usually made from thermoplastic materials that have different glass transitions or melting temperatures. This means that a first component (e.g. sheath), melts at a lower temperature than a second component, e.g. core. Multicomponent fibers can be softened or melted to form a tacky structure that, upon cooling, stabilizes the fibrous structure. Multicomponent fibers can have a range of 20 to 80 percent, with some embodiments ranging from 40% to 60% in terms of low melting polymer. Multicomponent fibers can have as much as 80% to 20% and, in certain embodiments, as much to 40% to 60%, depending on the weight of high melting polymer. KoSa Inc., Charlotte, N.C., has two types of sheath-core bicomponent fibres. They are T-255 (which uses a polyolefin sheath) and T-256 (which uses a co-polyester sheath). Other bicomponent fibers are also available from Fibervisions LLC in Wilmington, Del.
Staple fibers and continuous fibers can be used. One embodiment may use staple fibers that have a length of about 1 to 150 millimeters. In some embodiments, this ranges from approximately 5 to 50 millimeters. In some embodiments, about 10-40 millimeters. In some embodiments, about 10 to 40 millimeters. Some embodiments range from 10 to 25 millimeters. Carding techniques can be used to create fibrous layers using staple fibers, although this is not necessary. By placing the fibers in a picker, which separates them, the fibers can be made into a carded Web. The fibers are then sent to a combing unit or carding unit, which further breaks down and aligns them in the machine direction. This creates a machine-oriented fibrous web. To form a bonded nonwoven web, the carded web can be bonded using well-known techniques.
A spunbond web is another example of a multilayered structure. It is made on multiple spin banks machines. In these machines, a spin bank deposits fibers onto a layer of fibers that was previously deposited from a previous spinning bank. This individual spunbond nonwoven web can also be considered multi-layered. The nonwoven web’s layers of deposited fibers may be identical or different in weight, composition, type, size, crimp level, and/or form. Another example is a nonwoven web that may include multiple layers of spunbond web or carded webs, each individually produced and bonded together to make the web. As discussed above, these layers can differ in terms production method, basis weight and composition.
A nonwoven web material can also include a fibrous component, making it a composite. A nonwoven web can be entangled with another fibrous material using any of the many entanglement methods known in the art, such as hydraulic, air, mechanical, and others. One embodiment of the nonwoven web includes integral entanglement with cellulosic fibres by hydraulic entanglement. Hydraulic entanglement is a process that uses high pressure jet streams to entangle fibers and form a densely consolidated fibrous structure. U.S. Pat. reveals nonwoven webs that are hydraulically entangled using both continuous and staple fibers. No. No. No. 4,144,370 to Boulton. These are incorporated in their entirety by reference thereto herein for all purposes. U.S. Pat. 102/030/01 reveals hydraulically entangled composite webs of continuous fiber nonwoven webs and a pulp layer. No. 5,284,703 to Everhart, et al. U.S. Pat. No. No. The composite’s fibrous component may contain any amount of the resulting substrate. The composite may have a fibrous component that is greater than 50% in weight, or, in certain embodiments, as much as 60% to 90%. The nonwoven web can also contain less than 50% of the composite’s weight, and in certain embodiments as low as 10% to 40%.
“The nonwoven web material can be necked in one or several directions before lamination to the film according to the present invention, although this is not necessary. U.S. Patent describes suitable necking techniques. Nos. Nos. 2004/0121687 to Morman, et al. Alternativly, the nonwoven Web may be relatively inextensible in at most one direction before lamination to the film. The nonwoven web can optionally be stretched in any direction after lamination.
“The basis weight for nonwoven web material can vary from approximately 5 grams per square meter (‘gsm?). To 120 gsm in some embodiments, or from about 10 to 70 gsm in others. In some cases, to around 35 gsm in others. Multiple nonwoven web materials can have different basis weights.
“III. Lamination Technique”
“To simultaneously form apertures or bonds between the film, the nonwoven web material and the film, lamination can be achieved in the present invention using a patterned bonding method (e.g., ultrasonic bonding and thermal point bonding). Materials are supplied to a nip that is defined by at most one patterned roll. For example, thermal point bonding uses a nip that is formed between two rolls. At least one of these rolls must be patterned. Ultrasonic bonding uses a nip between a pattern roll and a Sonic Horn. The patterned roll, regardless of the method used, contains multiple raised bonding elements that simultaneously bond the film to the nonwoven material(s). These bonding elements also form apertures in film. You can tailor the size of the bonding elements to help form apertures in the film or increase bonding between the film, nonwoven material(s), and the film. The bonding elements have a large dimension, so they are often chosen to be relatively long. The bonding elements’ length dimension can range from 300 to about 5000 millimeters in some embodiments to 500 to about 4000, while in others, it may be as high as about 1000 to 2000 millimeters. The width dimension for bonding elements can also vary from 20 to 500 micrometers in some embodiments to 40 to 200 micrometers in others, and from 50 to 150 micrometers in some. The ‘element aspect ratio’ (the ratio of the length of an element to its width) is also important. The?element aspect ratio? (the ratio of the element’s length to its width) can range from 2 to 100 in some embodiments to 4 to 50 in others and from 5 to 20 in some other embodiments.
The nonwoven composite’s total bond area should be less than 50%, as determined by optical microscopic methods. In some cases, it may even be less than 30%. The bond density is typically higher than 50 bonds per square inches, with some embodiments ranging from 75 to 500 pin bonds per sq inch. The?S-weave’ is a suitable bonding pattern that can be used in the present invention. Pattern and is described in U.S. Pat. No. No. 5,964,742 McCormack, and al. S-weave patterns have a typical bonding element density between about 50 and about 500 bonding entities per square inch. In some embodiments, this may be as high as 75 to 150 bonding components per square inch. A suitable?S?weave? FIG. FIG. 2 shows S-shaped bonding elements 88 with a length dimension of?L? 2. This illustrates S-shaped bonding elements 88 having a length dimension?L? and a width dimension?W.? The?rib-knit’ bonding pattern is another suitable choice. Pattern and is described in U.S. Pat. No. No. Rib-knit patterns generally have a density of between 150 and about 400 bonding components per square inch. In some instances, it may be as high as 200 to 300 bonding elements. A suitable rib-knit is shown in FIG. FIG. 3 shows an example of a suitable?rib-knit? pattern. FIG. 3 shows bonding elements 90 and 91 that are oriented in different directions. Another suitable pattern is the “wire weave”. The pattern has a density of between 200 and 500 bonding elements/square inch. In some instances, it can have as high as 250 to 350 bonding elements/square inch. A suitable wire-weave is shown in FIG. FIG. 4 shows an example of a suitable?wire-weave? pattern. FIG. 4 illustrates bonding element 93 and bonding element 95 which are oriented in different directions. U.S. Pat. describes other bond patterns that could be used in this invention. No. 3,855,046 to Hansen et al. ; U.S. Pat. No. 5,962,112 to Haynes et al. ; U.S. Pat. No. 6,093,665 to Sayovitz et al. ; U.S. Pat. No. D375,844 Edwards, and al. ; U.S. Pat. No. D428,267 to Romano et al. ; and U.S. Pat. No. No.
“A proper bonding temperature (e.g. the temperature at which a heated roll is heated) will melt or soften the low-softening points elastomeric polymer(s). This will be done in regions that are adjacent to the bonding element. The softened elastomeric polmer(s), which may have been melted, can then flow and be displaced by bonding pressures such as those exerted on the bonding elements. The film around the apertures may also fusion to the nonwoven web material(s), creating an integral nonwoven composite. Because the elastomeric plasticmer(s), may physically entrap, adhere to the fibers at bond sites, sufficient bond formation may not be required without substantial softening the polymer(s). The nonwoven web material is not bonded to film or other materials in the areas that are directly adjacent (e.g. Above or below the apertures. The nonwoven web material is generally unapertured. However, it can develop small cuts or tears during processing.
“Another factor that affects concurrent aperture and bond formation, as stated, is the level of tension in the film during laminate. A decrease in film tension is often correlated with an increase in aperture size. Film tension too high can adversely affect the film’s integrity. To achieve the desired level of tension during lamination, most embodiments employ a stretch ratio between 1.5 and 7.0 in certain embodiments. In some embodiments, this is from 3.0 to 5.5. You can determine the stretch ratio by multiplying the final length of your film by its initial length. The draw ratio can also be approximated by the stretch ratio. This is calculated by dividing the final length of the film by its original length.
“Various embodiments and uses of the invention will be described in more detail. It should be noted that the above description is only an example and that other methods can be used in accordance with the present invention. Referring to FIG. FIG. 1 shows an example of a method to form a composite using an elastic film and nonwoven web material. The raw materials for the film, such as elastomeric polymer, can be dried mixed (i.e. without a solvent) before being added to an extrusion machine 40. Alternately, the raw materials can be mixed with a solvent. The materials are mixed in the melt in the hopper and compounded using any technique known, including batch and/or continuous compounding techniques, which employ, for instance, a Banbury mixer or Farrel continuous mixer as well as single and twin screw extruders and other screw extruders.
“Referring to FIG. “Referring again to FIG. 1, we show one method of forming uniaxially stretched films. The illustrated embodiment shows how the film 10 is stretched in machine direction. This is done by passing it through a film orientation unit (or machine direction orienter?). 44, which is commercially available at Marshall and Willams, Co. Providence, R.I. The MDO is equipped with a number of stretching rolls 46 which progressively stretch the film 10 in the machine’s direction. FIG. 1 shows four pairs of rolls 46. FIG. 1 shows four pairs of rolls 46. However, it is important to understand that the number of rolls can be increased or decreased depending on how stretchy the roll needs to be. Film 10 can be stretched using either one or multiple discrete stretching operations. You can also stretch the film 10 in different directions. The film can be held at its lateral edges with chain clips, and then transferred into a tenter oven. Chain clips may be used to draw the film in the cross-machine direction, achieving the desired stretch ratio.
A nonwoven web material can also be used to laminate the elastic film. The nonwoven web material can be simply unwound from a supply reel. As shown in FIG. A nonwoven web material 30, such as the one shown in FIG. 1, can be made in-line using spunbond extruders 48. The 48 extruders deposit 50 fibers onto a 52-gauge forming wire, which forms part of a continuous belt that runs around a series rolls. To maintain the fibers on forming wire 52, a vacuum (not illustrated) can be used if desired. The mat 54 formed by the spunbond fibers 50 may be optionally compressed using compaction rolls 56. A second material 30a, which is not required, may be laminated to elastic film 10. A second nonwoven web material, film or other material may be used as the second material 30a.
“Regardless, thermal bonding techniques can be used to laminate the material(s), to the elastic film. FIG. FIG. 1. For example, the materials 30a and 30a are directed at a nip between rolls 58 to laminate to the elastic film 10. The rolls 58 can contain multiple raised bonding elements or may be heated. The elastic film 10 is melted fused to nonwoven web materials 30 and 30, at a number of discrete bond locations 31. (See FIG. 7). This means that the elastomeric plastics in the film 10 can be softened and/or melt so as to physically trap fibers from the nonwoven web materials 30, and 30 a. The elastic film 10 may have a certain amount of tack to ensure that it adheres to the fibers during lamination. FIG. FIG. 7 shows that the bond sites 31 can be found proximate to (or near) a perimeter 37, defined by the corresponding apertures 33. These apertures are formed by the displacement of the film 10. By strengthening the area around the apertures 33, the specific location of bond sites 31 may improve the integrity of the resulting 32 composite. Thermal bonding is not a process that melts the nonwoven web material polymers 30 and 30a at sufficiently low temperatures to cause significant softening. The composite 32 will retain the physical properties of individual nonwoven web material materials (e.g. liquid permeability and softness, bulk and hand feel) better.
The composite 32 can then be wound up and stored on a takeup roll 60. The composite 32 can be kept under tension by using the same line velocity as one or more stretching rolls 46 to maintain tension. The composite 32 should be allowed to retract slightly before winding onto the take-up roller 60. You can achieve this by using a slower linear speed for the roll 60. The elastic film 10 is previously tensioned before lamination. It will then retract in its original direction and become shorter in the machine directions, buckling the composite or creating gathers. The elastic composite becomes extensible in the machine direction, so that any gathers or buckles may be pulled out flat. This will allow the elastic film 10 elongate.
“Which is not shown in FIG. “While not shown in FIG. 1, additional processing steps and/or finishing steps may be used without departing from its spirit and scope. To increase extensibility, the composite can optionally be mechanically stretched in cross-machine or machine directions. One embodiment may include a plurality of rolls with grooves in the CD or MD directions. U.S. Patent Application Publication Nos. explains such grooved satellite/anvil roll arrangements. 2004/0110442 to Rhim, et al. Rhim, et. al. 2006/0151914 Gerndt, and others are incorporated herein in full by reference thereto. The laminate can be run through multiple rolls with grooves in the CD or MD directions. The grooved rolls can be made of steel or another hard material (such a hard rubber).
“FIGS. “FIGS.5” 5-6 illustrates how groove rolls can incrementally stretch the composite. Satellite rolls 182 can engage an anvil rolls 184. Each of these rolls may have a plurality ridges 183 that define a plurality 185 of grooves 185. These grooves are positioned in the cross-machine direction. The grooves 185 are generally perpendicular with the direction of stretch. The grooves 185 are therefore oriented in the machine direction to stretch composite in the cross-machine directions. To stretch the composite in the machine direction, the grooves 185 can also be oriented in cross-machine. Satellite roll 182’s ridges 183 are intermingled with the grooves 185, 185, and 185 of anvil rolls 184. Satellite roll 182’s grooves 185 are intermingled with anvil roll184’s ridges 183.
The dimensions and parameters for the grooves 185, ridges 183 can have a significant effect on the extent of extensibility provided to the rolls 182 or 184. The number of grooves 185 on a roll can vary from approximately 3 to 15 per inch in some embodiments to about 5 or 12 per inch in others. In some embodiments, it may be between 5 and 10 per inch and in others, 5 and 10. A certain depth?D’ may be assigned to the grooves 185. This can range from 0.25 to about 1.25 centimeters and in some cases, from 0.4 to 0.6 centimeters. The peak-to-peak distance (?P?) is also important. The distance between grooves 185 is usually from about 0.01 to about 9.9 centimeters. In some embodiments, it may be as low as 0.2 centimeters to as 0.5 centimeters. The groove roll engagement distance E? The distance between grooves 185 & ridges 183 may be as high as 0.8 centimeters. In some embodiments, it could be 0.15 to 0.4 centimeters. The composite 32 (FIG. The composite 32 (FIG. To relax the composite and allow for extension, heat can be applied to it prior to or during incremental stretch. Any suitable heat application method is possible, including heated air, infrared heating, heated nipped roll, partial wrapping of laminate around one or several heated rolls or steam canisters. The grooved rolls can also be heated. You should also know that other arrangements of grooved rolls are equally acceptable, such as two grooved rolling positioned adjacently to each other.”
Other than the grooved rolls described above, there are other methods that can mechanically stretch the composite. The composite could be stretched by passing it through a tenter frame. These tenter frames are well-known in the art. They are described in U.S. Patent Application Publication No. 2004/0121687 to Morman, et al. The composite can also be necked. U.S. Patent. Describes suitable techniques for necking the composite. Nos. Nos. 2004/0121687 Morman, et. al. are all incorporated herein in full by reference thereto for any purposes.
The nonwoven composite of this invention can be used in many different applications. The nonwoven composite can be used as an absorbent article, as we have already mentioned. An ?absorbent article? An?absorbent article? is any article that can absorb water or other fluids. Some examples of absorbent items include personal care absorbent article, including diapers and training pants, absorbent underpants and feminine hygiene products (e.g. sanitary napkins), swimwear, baby wipes and so forth; medical absorbent article, such as garments and fenestration material, underpads and bedpads as well as bandages, bandages, absorbent drapes and medical wipes; food service wipers; clothing articles and so on. The art of making absorbent articles is well-known to those who are skilled in the field. An absorbent article may contain a substantially liquid-impermeable (e.g. the outer cover), or a liquid permeable (e.g. bodyside liner, surge, etc.). An absorbent core is also available.
“In one embodiment, the nonwoven composition of the present invention can be used to form an absorbent article’s liquid-permeable coating (e.g. bodyside liner, surge layers). The elastic film is bonded with the nonwoven web material at discrete bond points located around the perimeter of the apertures. The conditions of lamination can be controlled to ensure that the nonwoven web material is not substantially bonded (e.g. not substantially melt fused together), in the areas adjacent to the apertures. The elastic film can be placed between two nonwoven materials to create melt bond sites. The lamination conditions may allow the nonwoven web materials to be generally unapertured in areas adjacent to the elastic film apertures. These generally unbonded and unapertured areas in the nonwoven web materials (s) increase the composite’s ability to be used as a liquid-permeable coating in an absorbent article. Because the nonwoven material is not fused at the film apertures, liquids may flow more easily through the material and into the aperture. The nonwoven web material’s lack of significant aperturing allows it to maintain other desirable properties, such as bulk, softness, and handfeel
“Besides liquid-permeable materials (e.g., liners, surge layers, etc. The nonwoven composite of this invention can be used in many other ways, including providing elastic waists, leg cuff/gasketings, stretchable ears, side panels, outer covers, and any other component with elastic properties.
We will now discuss in greater detail the various embodiments of absorbent articles that can be made according to the invention. FIG. 8 shows an example of an absorbent article. 8 is a diaper 201. The invention can also be used in diapers 201, as well as other absorbent articles such as incontinence articles and diaper pants. The diaper 201 in the illustrated embodiment is shown to have an hourglass shape, unfastened. Other shapes can be used, however, including a rectangular, T-shape or I-shape. The diaper 201 is made up of a number of components. These include an outer cover 217 and bodyside liner205. An absorbent core 203 and surge layer207. However, other layers can be used in accordance with the present invention. The FIG. 8 diagram also shows that one or more layers may be eliminated. 8. In certain embodiments, the present invention may also allow for 8 to be removed.
The bodyside liner (205) is used to protect the skin from liquids contained in the absorbent core (203). The liner 205 is a bodyfacing material that is usually soft, flexible, and non-irritating. The liner 205 is typically less hydrophilic than its absorbent core 203, so its surface stays relatively dry for the wearer. The liner 205 could be liquid-permeable, allowing liquids to easily penetrate its thickness as mentioned above. U.S. Pat. describes exemplary liner constructions that include a nonwoven web. No. 5,192,606 to Proxmire, et al. ; U.S. Pat. No. 5,702,377 to Collier, IV, et al. ; U.S. Pat. No. 5,931,823 to Stokes, et al. ; U.S. Pat. No. 6,060,638 to Paul, et al. ; and U.S. Pat. No. 6,150,002 to Varona; U.S. Patent Application Publication Nos. 2004/0102750 was given to Jameson; 2005/0054255 was given to Morman, and others. ; and 2005/0059941 (Baldwin, et. al.) are all incorporated herein in full by reference thereto. The present invention’s nonwoven composite is included in one embodiment of the liner.
“As shown in FIG. 8 shows that the diaper 201 can also have a surge layer (207), which helps to diffuse and decelerate surges or gushes that are quickly introduced into the absorbent center 203. The surge layer 207 is designed to quickly accept and temporarily hold the liquid before releasing it into storage or retention areas of the absorbent center 203. The illustrated embodiment shows the surge layer 207 interposed between the inwardly facing surface 218 of the bodyside liners 205 and absorbent core 203. Alternately, the surge layer may be found on the outwardly facing surface 218 in the bodyside liners 205. The surge layer 207 is usually made from highly liquid-permeable substances. U.S. Pat. 207 provides examples of suitable surge layers. No. 5,486,166 to Ellis, et al. U.S. Pat. No. No. The present invention’s nonwoven composite is included in the surge layer 207 of one embodiment.
The outer cover 217 is usually made from a material that is impermeable to liquids. The outer cover 217 can be made from either a flexible liquid-impermeable plastic film or another thin plastic film. One embodiment of the outer cover 217 is made from a polyethylene sheet with a thickness between 0.01 and 0.05 millimeters. Although the film is impermeable for liquids, it can be permeable to gases, water vapor, and other gases (i.e., breathable). The outer cover 217 prevents liquid exudates, but allows vapors to escape the absorbent core203. The outer cover 217 can be made from a polyolefin laminated to nonwoven web if you prefer a clothier feel. A stretch-thinned, polypropylene film can be thermally laminated to form a spunbond web of phenol fibers.
The diaper 201 could also include other components that are well-known in the art. The diaper 201 could also include a substantially hydrophilic tissue wrappingsheet (not illustrated), which helps to maintain the integrity and fibrous structure of absorbent core203. The tissue wrapsheet is usually placed around the absorbent core203, covering at least two of its major facing surfaces. It is made from an absorbent cellulosic substance such as creped wadding, or a high-wet-strength material. A tissue wrapsheet can be designed to distribute liquid quickly over the absorbent fibers of 203. To effectively trap the absorbent core, 203, the wrapsheet material may be attached to the wrapsheet on the other side of the fibrous bulk. The diaper 201 may also have a ventilation layer (not illustrated) that is placed between the absorbent core203 and the outer covering 217. The ventilation layer can be used to insulate the outer covering 217 from the absorbent 203 and reduce dampness in the 217. One example of such ventilation layers is a nonwoven web laminated with a breathable layer, as described in U.S. Pat. No. No.
“In some embodiments, the diaper201 may include a pair or ears (not shown), which extend from the diaper’s side edges 232 into the waist region. Side panels can be integrated with a particular diaper component. The side panels can be formed from either the outer cover 217, or the material used to create the top surface. Alternate configurations include members that are connected to the outer covering 217, top surface, between outer cover 217 & top surface or other configurations. The elastic nonwoven composite of this invention can be used to make the side panels elasticized or made elastomeric. Examples of absorbent articles that have elasticized side panels and selectly configured fastener buttons are described in PCT Patent Application (WO 95/16425) to Roessler; U.S. Patent. No. 5,399,219 to Roessler et al. ; U.S. Pat. No. No. No. No.
FIG. 8 shows that the diaper 201 could also have a pair containment flaps, 212 which are designed to prevent and contain the lateral flow exudates. The containment flaps may be found along the laterally opposing side edges 232 of bodyside liner205, adjacent to the sides of the absorbent center 203. The containment flaps may be extended longitudinally along the length of absorbent core203 or only partially. The containment flaps, 212 may be placed in a specific location along the sides 232 and 210 of diaper 201. To better contain body exudates, one embodiment of the containment flaps212 extends along the length of the absorbent 203. These containment flaps 212 can be used to protect the body exudates. U.S. Pat. 212 describes suitable constructions and arrangements of containment flaps 212. No. No.
The diaper 201 can be elasticized with appropriate elastic members to improve fit and reduce body exudates leakage. FIG. 8 shows an example of this, 8 shows an example of leg elastics 206 that may be used to tension the diaper 201’s side margins. These elasticized leg bands can close fit around the legs to reduce leakage, improve comfort, and enhance the appearance of the diaper. To provide elasticized waistbands, elasticized diaper 201 may include waist elastics 208. The waist elastics of 208 are designed to fit comfortably around the waist. The present invention’s elastic nonwoven composite is compatible with the leg elastics (206) and waist elastics (208). Laminate sheets are a good example of such materials. They can either be attached to or comprise the outer cover 217, so that they impart elastic constrictive forces.
“The diaper 201 could also contain one or more fasteners 233. FIG. 2 illustrates two flexible fasteners (230). FIG. 8 shows two flexible fasteners 230 placed on opposite sides of the waist region to create a waist opening as well as a pair of leg openings around the wearer. Although the shape of fasteners 230 can vary widely, they may be rectangular, square, circular, triangular, oval, linear, or other shapes. For example, the fasteners can include a hook-and?loop material, buttons and pins, snaps or adhesive tape fasteners. They also may contain cohesives and fabric-and?loop fasteners. One embodiment includes a piece of hook material attached to the flexible backing.
“The different regions and/or parts of the diaper 201 can be attached using any known attachment mechanism such as adhesives, ultrasonics, thermal bonds, or other. You can use hot melt adhesives or pressure-sensitive adhesives as suitable adhesives. The adhesive can be used as a single layer or a pattern. It can also be applied in a swirled or dot pattern. The illustrated embodiment shows the outer cover 217 and the bodyside liner205 being attached to one another and the absorbent core 203. This is done using adhesive. Alternately, the absorbent core may be attached to the outer cover 217 with conventional fasteners such as buttons or hook and loop fasteners. Other components such as the waist elastic members 208, the leg elastic members 226 and fasteners 227 can also be attached to the diaper 201 with any attachment method.
“Although different configurations of diapers have been described, it is important to understand that the present invention also covers other diaper and absorbent articles configurations. The present invention does not only cover diapers. Any other absorbent article can be made in accordance to the present invention. This includes, but is not limited, to personal care absorbent articles such as diapers, training pants, absorbent underpants and feminine hygiene products (e.g., sanitary nappy pads), swimwear, baby wipes and so forth; medical absorbent items such as medical absorbent articles such as clothing, garments, fenestration material, underpads and bandages, absorbent drapes and medical wipes; food service wis; and clothing articles U.S. Pat. provides several examples of absorbent articles. No. 5,649,916 to DiPalma, et al. ; U.S. Pat. No. No. No. No. Other suitable articles can be found in U.S. Patent Application Publication No. 2004/0060112A1 to Fell et al. and U.S. Pat. No. 4,886,512 to Damico et al. ; U.S. Pat. No. No. ; U.S. Pat. No. Fell et al. ; and U.S. Pat. No. No.
“The following examples may help you better understand the invention.”
“Test Methods”
“Cycle Testing”
“The materials were subject to cyclical testing in order to determine percent set and load loss. One-cycle testing was used to determine 150% defined length. The sample size for this test was 3 inches cross-machine and 6 inches in machine directions. The grip size was 3 inches wide. The grip separation was four inches. The sample were loaded so that the machine direction was vertical. The preload was approximately 10 to 15%. The sample was pulled to 100% elongation at 20 inches per hour. After that, the sample returned to zero at 20 inches per second. All the results are from the first cycle. Testing was performed on a Sintech Corp. constant-rate of extension tester 2S equipped with a RenewMTS mongoose (control) and TESTWORKS 4.07b software. (Sintech Corp., Cary, N.C.). The tests were done under ambient conditions.
“Air Permeability:”
“Air permeability was measured using the?Frazier permeability?. This is the standard cubic feet per hour of air flow across a material. It is determined as the square foot of material with an average air pressure differential of 0.5 in water (125 Pa). The test was done at ambient conditions.
“Peel Strength:”
“Strain:”
“The materials were tested for elongation and strain. The sample was measured in inches across the machine direction and 7 inches in cross-machine directions. Intermeshing grips were used to ensure that the material did not slip during testing. The grip separation was four inches. The sample were loaded so that the sample’s machine direction was in the vertical direction. The preload was approximately 10 to 15%. After the sample was pulled to produce 2000 grams of tension, the test was stopped. The speed of the test was 500 millimeters per hour for strain or extension. The test measured the strain or elongation in percent starting at 2000 grams tension in the material. Sintech Corp. constant-rate of extension tester 2S was used for testing. It was controlled by a RenewMTS mongoose (controller), and TESTWORKS 4.07b software. (Sintech Corp., Cary, N.C.). The tests were done under ambient conditions.
“EXAMPLE 1”
“FIGS. 9-17 are scanning electron microphotographs showing the resulting sample. FIG. FIG. 9 shows, for example, the roughly rectangular apertures 333 formed by the bars in the rib-knit design (See e.g. FIG. FIG. 3 shows the rectangular apertures 333 a formed by the bars of the rib-knit pattern (See e.g., FIG. FIG. 10 shows the circular apertures 333 formed by the pins in the rib-knit design. FIG. shows a perspective view of the apertures. 11. FIGS. 14-17. The microphotographs not only illustrate apertures but also show the melt fusion between the elastic film and the fibers of nonwoven webs. FIGS. 12-13 show an example of this. FIGS. 12-13 depict an elastic film 310 which is melt fused into a nonwoven web at discrete bond site 331 Apertures 333 define the perimeter of bond sites 331 and locate them proximately to each other.
“EXAMPLE 2”
“EXAMPLE 3”
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