Invented by Davis Dang Hoang Nhan, Mark M. Mleziva, Lawrence H. Sawyer, Peiguang Zhou, Kimberly Clark Worldwide Inc
The Kimberly Clark Worldwide Inc invention works as followsThe steps for making an absorbent product include applying a layer to a stretchable surface and then applying a particulate superabsorbent layer to the stretchable surface.
Background for Method of making a stretchable absorbent product
The present invention is a general description of absorbent articles for wear on the body, more specifically such absorbent items that have an absorbent composite attached to a stretchable substrate.
Absorbent products such as diapers and training pants. Incontinence clothing, feminine hygiene products etc. The absorbent articles consist of a liquid-permeable liner facing the body, an outer cover that is impermeable to liquid, and an inner core (also known as an absorbent body, or absorbent structure), which is positioned between the outer cover and the liner. This core serves as a reservoir for liquids (e.g. urine, menses) that are expelled by the user. Some absorbent articles have an outer cover or liner that can be stretched to allow for some expansion to better fit the wearer. During use, forces are generated from the loading of the absorbent articles and the movement of the user. These forces may cause the absorbent to move within the absorbent, tear or otherwise permanently distort, reducing the intended absorbent properties of the core.
It is well known that the separate absorbent structure can be attached to the outer cover or liner using adhesive, thermal or ultrasonic bonds, or other methods to stop the core shifting when the article is being stretched or un-stretched. The absorbent core can be secured to the outer cover and/or liner, but this reduces the stretchability of that substrate, which in turn decreases the flexibility of the article. While securing the core to the cover or liner can reduce the risk of distortion and shifting, stretching the substrate on which the core is attached to separate from the outer cover may still cause the core to tear.
Also conventional absorbent cores consist of hydrophilic and superabsorbent fibers that are loosely mixed together and entangled to form an absorbent batting. Some absorbent cores concentrate the superabsorbent materials in specific target areas where the article needs more absorption. The superabsorbent fibers and particles are displaced as the absorbent is stretched or unstretched. If the hydrophilic fibers and superabsorbent particle are displaced from their target areas, it can cause leakage. In cases where superabsorbent grains accumulate, the swelling of these particles can be uncomfortable. This can also result in a degraded look and perception of low quality.
In a second embodiment, the method consists of applying a layer to a substrate that is liquid impermeable and stretchable. The adhesive composition is open for a certain period of time. After the adhesive composition has been applied to a stretchable substrate, a layer of particulate material superabsorbent is added to the adhesive. The stretchable substrate passes through a nip during the open time of adhesive composition in order to promote adhesive bonding. The stretchable substrate remains attached to the substrate with the adhesive even after stretching.
In a further embodiment of the method, a liquid-impermeable stretchable substrate is moved in a direction in which the flow of adhesive composition is directed onto the substrate. The adhesive composition is viscous at temperatures below or equal to 250 degrees Fahrenheit. The flow of superabsorbent particulate is introduced into the flow adhesive composition in order to create a mixture consisting of the adhesive composition and superabsorbent. The mixture is applied to the stretchable material in liquid form, whereby the adhesive composition adheres the superabsorbent materials on the substrate.
Other features” of the invention will be partly apparent and partially pointed out in this document.
Referring to FIG. The toilet training pants of children are one example of a form of an absorbent product of the invention. It is shown in full by the number 20. The absorbent article may or may not have been designed to be disposable. This refers to articles intended to be thrown away after a short period of time, rather than being washed or otherwise prepared for reuse. The present invention can be used with other absorbent articles for personal use, such as diapers, feminine products, incontinence items, medical garments and surgical pads, or other garments for personal care and health care.
By way only of illustration, different materials and methods of constructing training trousers such as the pants of FIG. PCT Patent Application No. WO 00/37009, published on Jun. 29, 2000 by A. Fletcher et al; U.S. Pat. No. No. 4,940 464 issued July. Van Gompel and others received a patent number 4,940,464 on July 10, 1990. U.S. Pat. No. No. No. 16 1998 to Brandon and others, which is incorporated by reference herein.
The pair of training trousers 20 is shown in FIG. In a partially-fastened state, FIG. 1 comprises longitudinal end areas, also referred herein to as a forward waist region 22, and a rear waist region 24, as well as a central region, also referred herein to as a “crotch area 26”, extending between and interconnecting both the front and rear waist regions. The pants 20 have an inner surface 28, which faces the wearer, and an outer face 30, which faces away. The front and rear waist regions 22, 24, are those parts of the pants that, when worn, completely or partially cover the waist, mid-lower torso, or both. The crotch area 26 is generally that part of the pants which covers the lower torso, crotch and lower torso of the wearer when worn. Referring to FIGS. “With additional reference to FIGS.
The illustrated pants 20 consist of a centrally located absorbent assembly (generally indicated as 32), a pair lateral opposite side panels (34), extending from the front waist area 22 and a couple lateral opposite side panels (134), extending from the back waist area 24. The central absorbent 32 is rectangular in the illustrated embodiment. It is possible that the central assembly 32 could be other shapes than rectangular. For example, hourglass-shaped, T shaped, I shaped and similar.
Still refering to FIGS. The central absorbent assembly comprises an outer cover (broadly referred to as a substrate), and a bodyside lining 42 (FIGS. The outer cover (also referred to in general as a “substrate”) is attached to the outer covering by adhesive, ultrasonic, thermal or other conventional methods. The liner 42 has been positioned (relative to other components of pants 20) in a way that it is contiguous with the skin of the wearer when the pants are on. The absorbent assembly includes an absorbent composite (FIG. The outer cover 40 is disposed between the bodyside liner and the outer cover 42 to absorb liquid exudates from the wearer. Two containment flaps (FIG. The bodyside liner (FIG.
The central absorbent assembly 32 in the illustration has opposite edges that form the front and rear waist edges 38, 39 and the opposite side edges 47 that form the side edges 36 (FIGS. The two figures are shown in Figures 2 and 3. “For further reference, the arrows 48 & 49 show the orientation of both the longitudinal and transverse or side axis of the training pants 20, respectively.
The training pants 20 are fastened in the manner partially shown in FIG. In Figure 1, the front-and-back side panels 34 and 134 are fastened together in a three dimensional configuration to form a waist opening of 50 and two leg openings of 52. The front and rear side panels 34, 134 are the portions of the pants 20 that are placed on the hips. The training pants 20 have front and rear waist edges 38, 39 that are designed to wrap around the waist of wearer and define the waist opening (FIG. The pants are defined by the side edges 36, which are laterally opposite. “The leg openings of the pants are defined by the side edges 36 and the sides 52 of the pant 20.
In the embodiment illustrated, each flap elastic member 53 is attached to an unattached edge of the flap. The flaps are secured to the unattached edge along the length of the flap. This allows the flaps to assume a generally upright position in the crotch area 26 of the pants 20 and form a seal with the body of the wearer. The containment flaps 48 are preferably located adjacent to the side edges 36. They can extend longitudinally across the entire length or only partially of the absorbent assemblies 32. U.S. Pat. describes the suitable constructions and arrangements of the containment flaps. No. No. The containment flaps may also be omitted from this invention without departing its scope.
The training pants 20 may also include a front waist member 54 (FIG. As is well known by those with knowledge of the field, 3), a back waist elastic member, 56, and leg elastomers 58 are included. The waist elastic members 56 and 54 can be operatively attached to the outer cover and/or bodyside liner along the opposite edges of the waist 38 and 39. They can also extend laterally over all or a portion each waist edge. Leg elastic members 58 may be operatively attached to the outer covering 40 (e.g. between the inner cover and outer cover, as shown in FIG. The bodyside liner (FIG. 4) or the outer cover 40 can be joined operatively to the leg elastic members 58. They extend longitudinally along the opposite side edges of the training pant 20. Each leg elastic member has a front terminus point 63, and a rear terminal point 65. These represent the longitudinal ends caused by the elastic gathering created by the leg members.
The side panels 34 and 134 can be permanently attached to the central absorbent 32 along the seams 66 in the front and rear waist regions 22 and 24, respectively. As best seen in FIGS. The front side panels can be permanently attached to the absorbent assemblies 32 and can extend transversely beyond their side edges 47 at the front waist area 22. The back side panels can also be permanently attached to the absorbent assemblies and can extend transversely beyond its side edges at the rear waist region 24. The side panels 134, 34 may be bonded with the absorbent assembly using adhesives, thermal or ultrasonic bonds, or other suitable techniques. The side panels 34 and 134 can be replaced by a stretchable cover, as described below, in part or whole. This stretchability will contribute to the elastomeric characteristics required for the fit and function. In alternative embodiments the side panels 34 and 134 can be integrally formed with the bodyside lining 42 or another component of absorbent assembly 32.
The front and rear side panels 34 and 134 have an outer edge (68) spaced laterally away from the seam (66), a leg edge 70 that is positioned toward the longitudinal middle of the training pant 20, and a waist edge 72 that is positioned toward a longitudinal edge of the pants. The leg end edges 70 and 72 extend from side edges 47 to outer edges 68 of the absorbent assemblies 32. Leg end edges 70 from the side panels 134 and 34 form part of side edges 36 on the training pants 20. Leg end edges 70 in the illustrated embodiment can be curved or angled to better fit the legs of the wearer. It is understood, however, that one or both of the leg edge edges 70 can be curved and/or angled. For example, the leg edge edge of the back waist area 24. Or, neither of the two leg edges may be curled or angled without departing the scope of the invention. The waist end edge 72 is parallel to the transverse direction 49. The waist end edge 72 of front side panels 34 forms part of front waist edge 38 and back waist edge 39.
The side panels 34,134 may, but need not, be made of an elastic material that can stretch in a general direction parallel to the transverse plane 49 of the training pant 20. The following U.S. Patent describes suitable elastic materials as well as a method of incorporating elastic panels into training pant. No. No. 4,940 464 issued July. Van Gompel and others received U.S. Pat. No. 4,940,464 on July 10, 1990. ; U.S. Pat. No. No. 5,224,405 issued July. Pohjola, U.S. Pat. No. No. No. 5,104,116 issued April 14, 1992 to Pohjola; and U.S. Pat. Pohjola, Apr. 14, 1992; U.S. Pat. No. No. All of which are incorporated by reference. In certain embodiments, elastic materials suitable for the construction of side panels 34,134 include stretch-thermal (STL) laminates, neck-bonded (NBL), reversibly-necked (RNL), or stretch-bonded (SBL). The methods of making these materials are well-known to those in the industry and described in U.S. Pat. No. No. 4,663,220, issued to Wisneski and others on May 5, 1987. ; U.S. Pat. No. No. 5,226,992 issued July. Morman, 13 September 1993; European Patent Application No. EP 0 217 022 published in April. Taylor et al. published EP 0 217 032 on Apr. WO 01/88245, filed by Welch et al. All of which are incorporated by reference. The side panel material can also be made of other materials such as non-wovens or wovens, as described in the following paragraphs as suitable for the construction of the outer cover and/or bodyside liner, mechanically prestrained composites, or materials that are extensible, but not stretchable (e.g. inelastic).Click here to view the patent on Google Patents.