MXPA96006410A - Folding a fibrous band to a g - Google Patents

Abstract

The present invention relates to an absorbent core that extends along a first axis and perpendicular thereto along a second axis and being produced in the direction of said first axis, said core being produced in the direction of the first axis, said core comprising: (a) a first absorbent structure having the same first and second axes as said absorbent core, (b) a gauze having first and second surfaces and substantially the same length as said first absorbent structure along the first axis: (c) a second absorbent structure having the same first and second axes as said absorbent core, which is fibrous and which is shorter than the gauze along said first axis, said second absorbent structure which does not extend beyond the periphery of said gauze in the direction of said first axis, said first absorbent structure being contiguous with said first surface of the gauze and coexte Nsiva along the first axis with said gauze, characterized in that said absorbent core is constructed in a continuous process comprising the steps of: (i) placing said continuous gauze on a conveyor belt, characterized in that said gauze is continuous on said conveyor belt (ii) forming and depositing, in discrete sequence said second fibrous absorbent structures on the second side of said continuous gauze, (iii) attaching the gauze and said second absorbent structures, by folding, forming said first absorbent structure as a continuous band, and placing it on the first side of said gauze, corat the gauze web and the first absorbent structure between one and the following ones of said second structure absorb

Description

FOLDING A FIBROUS BAND TO A FAT ) FIELD OF THE INVENTION The present invention relates to absorbent articles having absorbent cores comprising multiple absorbent layers, which are bonded together. In particular, the present invention relates to absorbent article structures, which have one of the absorbent article layers shorter in the direction of manufacture of the absorbent articles than at least one of the other layers, and which are attached to each other. at least one of the other layers by folding. The present invention also relates to a method for folding a central patch from a fibrous web to a gauze to replace the previously necessary adhesive, and the respective method for making said absorbent structures or embodiments of the present invention.

BACKGROUND OF THE INVENTION US Pat. No. 3,661,680 discloses a method for making an absorbent core comprising a layered construction of gauze, air felt and gauze. However, the method is indicated for combining the absorbent core by pressure rollers by folding along selected longitudinal lines. Interlaced fibers or superabsorbent polymers are not mentioned. EP-A-593 refers to integrity improvements in pads by the use of a selected tissue, which is placed between the fibrous pads. Therefore, this is the closest prior art for the basic construction of the core according to the present invention. However, compression is only mentioned for densifying, but not folding to attach the fibrous pads to the tissue. EP-A-21662 refers to an improvement of impregnation by the use of a special pattern of enhancement of a fibrous core to a gauze. However, no benefit is indicated for the integrity of the core and the procedure for making the absorbent core construction does not mention folding, but shows a patterned compression roll. EP-A-214190 describes the folding of multiple layers of gauze to immobilize the particles trapped between the layers. The basic principle of the longitudinal fold lines is also described, however, no interlaced fibrous patch is mentioned. EP-A-214867 describes fibrous structures with enhanced impregnation lines. This does not refer to the integrity of the core, but to the placement of the structure within the product. No folding of the gauze into the fibrous material is mentioned and interlaced fibers are not described. EP-A-399564 describes impregnation improvements due to the selective density of interlaced cellulose bands. Densification is described by calendering, however padding of gauze to the pad is not mentioned or improvements in core integrity are discussed. In making the absorbent article, it is desirable to have discontinuous patches of absorbent patches disposed on continuous strips of absorbent material, e.g., gauze. This is particularly true for the highly effective but expensive interlaced fibers, which are now beginning to be used more and more in the industry. In particular, when using high-speed machinery, the discontinuous patches have to be attached to the continuous bands or in any part it could not be possible to transport them. This has typically been done by attaching the patches to the gauze. However, the front and back ends of a patch are problematic to be glued due to the sticking-peel characteristics of the supply and glue application equipment, it can also cause losses in manufacturing efficiency due to glue contamination. Therefore, the patches were only glued to the gauze in its central part, leaving the anterior and posterior ends without joining the gauze. However, this easily leads to patches being loose during production, even reducing productivity more. All these problems are aggravated more if the process for making absorbent cores includes a turning point, where the band of the already combined material is turned down, which has been found useful to obtain particular products. Therefore, the problem underlining the present invention is to provide an absorbent core comprising a first absorbent structure, a gauze and a second fibrous, absorbent structure, which is shorter than the gauze in one orientation and is otherwise not extend beyond the periphery of the gauze. The gauze being joined to the second absorbent structure by folding. Preferably, the folding is carried out on one or several discrete lines. Although not necessary for the present invention, it is preferred, if the abutting surface between the gauze and the second absorbent structure is free of adhesives. A further aspect of the present invention is a continuous process for the manufacture of absorbent cores according to the above description, comprising the steps of placing a continuous gauze on a conveyor belt; forming and depositing, in discrete sequence, a second fibrous, absorbent structure on the continuous gauze; joining the gauze and the second fibrous structure, absorbent therebetween by folding; forming the first absorbent structure as a continuous band and placing it on the gauze on the opposite side from where said first fibrous structure is placed, and finally cutting the gauze web and the first absorbent structure between one and the following ones of the second ones absorbent structures.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to an absorbent core that extends along a first axis and perpendicular thereto along a second axis and that is produced in the direction of a first axis. The absorbent core comprises a first absorbent structure, which has the same first and second axes as the absorbent core, a gauze and a second absorbent structure. The gauze has a first and a second surface and has substantially the same length as the first absorbent structure along the first axis. The second absorbent structure is shorter than the gauze along the first axis and does not extend beyond the periphery of the gauze in the direction of the first axis, preferably in no direction. The second absorbent structure is usually a fibrous, absorbent structure, preferably comprising interlaced fibers. The first absorbent structure can be selected from a variety of absorbent structures, but preferably, it also comprises fibers, in particular, in combination with absorbent polymer gelling material, most preferably in the form of particles. These absorbent gelling materials may also be present in the second absorbent structure. The first absorbent structure is contiguous with the first surface of the gauze and is coextensive along the first axis with that gauze. The absorbent core is constructed so that the gauze on its second surface and the second absorbent structure are joined together by folding. In the preferred embodiments, according to the present invention, the second absorbent structure does not extend towards the periphery of the gauze. However, the folding extends along the first axis at least towards one end of the second absorbent structure, preferably the folding extends along the first axis towards both ends of the second absorbent structure and to simplify the manufacture is most preferably that the folding is continuous, thus extending along the entire length of the gauze along the first axis.

The folding can form one of several discrete lines along the first axis and is preferably used to replace the adhesive on the second surface on the gauze in order to avoid clogging of the surface by the adhesive, improves manufacturing by the Glue heating elimination, glue application and supply equipment and the problems associated with the required glue-release cycle of glue applications. Accordingly, the present invention also relates to a continuous process for the manufacture of the absorbent core of the present invention. This method comprises the steps of: placing a continuous gauze on a conveyor belt; - forming and depositing, in discrete sequence, second fibrous, absorbent structures on the second side of the gauze; - joining the gauze and the second absorbent structure, between them, by folding; - forming the first absorbent structure as a continuous band, and placing it on the first side of the gauze; cutting the gauze web and the first absorbent structure between one and the following ones of the second absorbent structure.

" The absorbent core, according to the present invention, can be used in all kinds of absorbent products, particularly in disposable absorbent diapers for babies, children or adults, as well as in incontinence inserter or in sanitary napkins.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a top plan view of a gauze continuously folded towards a second fibrous, absorbent structure. Figure 2 is a cross-sectional view of the embodiment of the invention of Figure 1 along line 2/2. Figure 3 is a cross-sectional view of the embodiment of the invention of Figure 1 along the line 3/3. Figure 4 is a top plan view of a gauze and a second absorbent fibrous structure of the prior art, glued together. Figure 5 is a cross-sectional view of the prior art embodiment of Figure 4 along line 5/5.

Figure 6 is a cross-sectional view of the prior art embodiment of Figure 4 along line 6/6.

DETAILED DESCRIPTION OF THE INVENTION AND OF THE DRAWINGS Figure 1 shows a continuous gauze 10 having a first axis 100 and perpendicular to it a second axis 200. The gauze is overlapping a second absorbent structure 16 sharing the axis 100 and 200 with the gauze 10. The gauze 10 and the second structure absorbent 16 are joined by folding lines 14. The direction of movement during manufacture is parallel to the first axis 100. When looking at a cross section of this part of the core, according to the invention, in Figure 2, it can be see that the second absorbent structure 16 is placed on the second surface of the gauze 10 and joined along the fold line 14 to that gauze. Not shown in the figures, but which is part of the absorbent cores of the present invention, is a first continuous absorbent structure, which is placed on the first side, that is, the side opposite the second side of the gauze 10. In an alternate cross-section, along line 3-3 of Figure 1, fold lines 14 can be seen, in which the second absorbent structure 16 and the gauze 10 are compressed together in a folding process. Figure 4 shows a structure of the prior art which also has a first axis 100, a second axis 200 of a gauze 10 and a second absorbent structure 16. However, in this prior art embodiment, the union between the second structure absorbent 16 and gauze 10 is provided by adhesive lines 12 that leave non-adhered ends 18 between the second absorbent structure 16 and the gauze 10. As can be seen in Figure 5, the non-adhered ends 18 of the second e The absorbent structure 16 could easily be lifted from the gauze 10, when the gauze is moved in a direction parallel to the first axis 100. Also, the width / length of the adhesive lines 12 should be considered, since the liquid deposited on one side of the The absorbent core can communicate through the plane where the adhesive prevents such communication through the width and length of the adhesive lines 12. As used herein, the term "disposable absorbent articles" refers to articles, which absorb and contain exudates from the body, and more specifically, refers to articles, which are placed against or close to the body of a user to absorb and contain the various exudates discarded from the body of the user, and which do not intend to be washed or another "" way restored or reused as an absorbent article (ie, they are intended to be discarded after a single use and preferably to be recirculated, converted, or otherwise disposed in an environmentally compatible manner). The embodiments of the absorbent article, disposable of the present invention, are incontinence briefs for adults, or diapers for babies or children. Examples of diaper types, to which the present invention readily adapts, are shown in U.S. Pat. RE 26,151; patent of E.U.A. 3,860,003; 4,253,461; and 7,704,115. In general, absorbent cores, in accordance with the present invention, are useful in all disposable absorbent articles. As used herein, the term "absorbent core" refers to all absorbent media in a disposable, absorbent article. In accordance with the present invention, the absorbent cores comprise a first and a second absorbent structure separated by a gauze therebetween. However, the absorbent cores may be composed of other absorbent layers, if they are suitable for the particular use of the absorbent article. In the following, reference will always be made to absorbent diapers, which, however, should not be misleading, since sanitary napkins, catamenials, linings for panties or inserts for incontinence represent possible, end products, in which the absorbent structures according to the present invention can be used. The external surface of a diaper is usually the furthest user surface during the use of the diaper. The backsheet preferably forms most of the outer surface. The inner surface is that surface of the diaper opposite the outer surface and is preferably formed by the topsheet.

Preferably, the inner surface of the diaper is coextensive with the outer surface and, in general, the inner surface is most in contact with the wearer when the diaper is used. Typically, the outer surface and the inner surface include the absorbent core, so that the topsheet and the backsheet extend beyond the periphery of the core and are bonded together. The first and second absorbent structures of the present invention can comprise any absorbent means, which are generally compressible, conformable, non-irritating to the user's skin, and capable of absorbing and retaining liquids, such as urine, menstruation and other exudates. of the body. The absorbent structure can be manufactured in a wide variety of shapes and sizes (eg, rectangular, hourglass, asymmetric, T-shaped, etc.) and from a wide variety of commonly used liquid absorbent materials in disposable absorbent articles, such as crushed wood pulp, which is generally referred to as air felt. Examples of other suitable absorbent materials include creped cellulose wadding, meltblown polymers, including coform, interlaced cellulosic fibers, gauze including gauze wraps and gauze laminates, absorbent foams, absorbent sponges, superabsorbent polymers, gelling materials, absorbers or any equivalent materials or combinations of materials. The configuration and construction of the absorbent core can also be varied, eg, the absorbent core can have varying gauge zones, a hydrophilic gradient, a superabsorbent gradient (as in concentration or particle size for granulated superabsorbents), or average density lower and acquisition zones with a lower average basis weight; or may comprise one or more layers or structures. The total absorbent capacity of the absorbent core, however, must be compatible with the design of the exudate load and the intended use of the core. A preferred embodiment of a diaper has an absorbent core in the shape of an hourglass. An illustrative absorbent structure, readily adaptable for use in the absorbent core of the present invention, is described in the U.S.A. 4,610,678, 4,673,402, 4,888,231. The absorbent core can also be adapted from the commercially successful absorbent member described in US Pat. 4,834,735, entitled "High Density Absorbing Members Having Lower Density and Lower Basis Weight Aquisition Zones" ("High Density Absorbing Members Having Low Density and Lower Base Weight Acquisition Zones"). Other preferred absorbent cores are described in the U.S.A. 4,685,915 and 4,781,710, which comprise fibrous structures that have different areas of absorptive capacity, density, or liquid acquisition speed. An absorbent, thin, alternative core useful in the present invention can be found in the US patent. 4,600,458. Another preferred absorbent core design provides an interlaced cellulose patch essentially without superabsorbent on the top of an air felt, the superabsorbent mixture comprising more than 30% superabsorbent. Preferably, the second absorbent structure comprises interlaced fibers, in particular interlaced cellulose fibers. In general, the first and second absorbent structures may comprise the same absorbent materials, which may be any known in the art. The difference between the first and the second absorbent structure, according to the invention, will depend on the adaptation of the respective structure to the particular function in the context of the specific absorbent article, for which the absorbent core is designed.

The gauze used between the first and the second absorbent structure, according to the invention, can be any type of folding gauze as is usual in the art. Typically, gauzes comprising wood pulp fibers are used, but the gauze fibers can comprise synthetic fibers as well as natural fibers, or the gauze can even be a laminate by itself comprising several layers of various gauze materials, or even a laminated structure, which comprises particulate materials such as, for example, superabsorbent polymers between the layers. The absorbent core is superimposed on the backing sheet and is preferably bonded thereto by means of core joining means. The backing sheet is impervious to liquids (e.g., urine) and is preferably manufactured from a thin plastic film, preferably a thermoplastic film, although other flexible liquid impervious materials may also be used. As used herein, the term "flexible" refers to materials, which are condescending, and which will readily conform to the general shape and contours of the human body. The backsheet prevents the exudates absorbed and contained in the absorbent core from staining items that are in contact with the diaper, such as sheets and underwear. The backing sheet of this form may comprise polymeric films, such as polyethylene or polypropylene thermoplastic films, or mixed materials such as film-coated nonwoven material. For economic, aesthetic and ecological reasons, the backsheet preferably has an average nominal gauge, ie, a calculated gauge, less than about 0.051 mm, most preferably a caliber calculated from 0.020 mm to 0.036 mm. Preferably, the backing sheet is a flexible polyethylene film. Illustrative films to be used as the backsheet of the present invention are manufactured by Tredegar Industries, Inc., of Terre Haute, Indiana, U.S.A. or BP-Chemical PlasTec Rotbuchenstrasse l, D-8000 MUNCHEN, Germany. The upper sheet forming the inner surface of the absorbent article is condescending, soft feeling, and non-irritating to the wearer's skin. In addition, the upper sheet is permeable to liquids, allowing liquids (eg, urine) easily penetrate through its thickness. A suitable topsheet can be manufactured from a wide variety of materials, such as porous foam, cross-linked foams, apertured films; or woven or nonwoven webs of natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polyester or polypropylene fibers), or from a combination of natural and synthetic fibers. Preferably, it is made of a material that isolates liquids from the wearer's skin, retained in the absorbent core. The diaper preferably further comprises one or more elastic folds in the legs to provide improved containment of liquids and other exudates from the body. Each elastic fold of the legs can comprise several different modalities to reduce the effusion of body exudates in the leg regions. (The fold of the legs can be, and is sometimes also referred to as leg bands, side flaps, barrier folds, or elastic folds). The patent of E.U.A. 3,860,003, entitled "Contractable Side Portions for a disposable diaper" ("Shrinkable side portions for a disposable diaper"), describes a diaper, which provides a collapsible opening in the leg having a lateral flap and elastic members to provide an elastic fold in the legs (packing fold). The patent of E.U.A. 4,909,803, entitled "Disposable Absorbent Article Having Elasticized flaps", describes a disposable diaper having "firm" elastic flaps (barrier folds) to improve containment of the leg regions. The patent of E.U.A. No. 4,695,278, entitled "Absorbent Article having dual Cuffs", describes a disposable diaper having dual folds including a packing fold and a barrier fold. The patent of E.U.A. 4,704,115, entitled "Disposable waist containment garment", describes a disposable diaper or incontinence garment having side-edge spill safety channels, configured to contain free liquids within the garment . The diaper may also comprise an elastic waist fitting that provides improved hold and hold, or any other accessory typically provided on incontinent nappies or piping such as those known in the art. The folding, according to the invention, is usually conducted by applying high pressure between a hammer and an anvil set, which compresses the gauze and the second absorbent structure to form a localized pattern of high density, in which the gauze and the fibers of the second absorbent structure are compressed with one another, so that their cohesive and adhesive strength allows the second absorbent structure to be effectively bound to the gauze. There is no particular requirement regarding the folding pattern. However, since it is known that the high density lines in the absorbent article can be beneficial for the distribution of liquids in said absorbent article and the fold lines represent high density lines, they can be formed in a way that they perform part or all of the function of liquid distribution, otherwise incorporated by high density lines formed separately in an absorbent core. The folding lines can also be replaced by other patterns that are known to be beneficial for the distribution of liquids, aesthetic consideration, among others. For folding, hot or cold folding rollers can be used. The main purpose of folding is to ensure that the ends of the second absorbent structure are held in the gauze so as not to separate during manufacture. However, if the folding lines, properly made, continue to hold the second absorbent structure to the gauze also during the use of the absorbent article and therefore improve the integrity of the core without the need for other means of adhesion to the core.

Claims (10)

1. - An absorbent core that extends along a first axis and perpendicular thereto along a second axis and being produced in the direction of said first axis, the core characterized in that it comprises: a first absorbent structure having the same first and second axes as said absorbent core; a gauze having a first and a second surface and substantially the same length as said first absorbent structure along the first axis; a second absorbent structure having the same first and second axes as said absorbent core, being fibrous and being shorter than the gauze along the first axis and not extending beyond the periphery of the gauze in the direction of said first axis; said first absorbent structure being contiguous with the first surface of the gauze and coextensive along the first axis with said gauze; and said absorbent core being constructed, such that said gauze on the second surface and the second structure are joined by folding.

2. - An absorbent core according to claim 1, further characterized in that said second absorbent structure does not extend towards the periphery of the gauze in any direction.

3. - An absorbent core according to any of the preceding claims, further characterized in that said second absorbent structure comprises interlaced fibers.

4. An absorbent core according to any of the preceding claims, further characterized in that said first absorbent structure, and preferably said second absorbent structure, comprises gelling, absorbent, polymeric materials.

5. An absorbent core according to any of the preceding claims, further characterized in that said folding extends along the first axis at least towards one end of the second absorbent structure, preferably said folding extends through all the length of the gauze along said first axis.

6. - An absorbent core according to any of the preceding claims, further characterized in that said folding forms one or several discrete lines along the first axis.

7. An absorbent core according to any of the preceding claims, further characterized in that said second surface of the gauze is free of adhesive.

8. An absorbent core according to any of the preceding claims, further characterized in that said absorbent core is comprised in a disposable absorbent diaper for infants, children or adults, in an incontinence insert or in a sanitary napkin.

9. - A continuous process for the manufacture of the absorbent core of claim 1, comprising the steps of: placing said continuous gauze on a conveyor belt; forming and depositing, in discrete sequence, said second fibrous, absorbent structures on the second side of said continuous gauze; joining the gauze and said second absorbent structures, by folding; forming said first absorbent structure as a continuous band, and placing it on the first side of said gauze; cutting the gauze web and the first absorbent structure between one and the following of said second absorbent structure.

10. - A continuous process according to claim 9, further characterized in that said folding is continuous between one and the following of said second fibrous, absorbent structures.