MXPA01000164A - A method for cutting and sealing an absorbent member - Google Patents

Abstract

A web including a fibrous material and superabsorbent material is fed to a station. The web has a first surface, a second surface, a first side edge and a second side edge. At the station, the operations of applying a superabsorbent material movement obstruction agent and cutting the web into individual absorbent members having a pair of opposing cut ends are carried out simultaneously.

Description

A METHOD FOR CUTTING AND SEALING A ABSORBENT MEMBER FIELD OF THE INVENTION This invention relates to a method for cutting and sealing an absorbent member, and more particularly to a method for cutting and sealing an absorbent member that is suitable for use as an absorbent core in a disposable absorbent article.

BACKGROUND OF THE INVENTION Absorbent webs comprising fiber masses, i.e. fibrous webs, are well known in the art. These wefts can imbibe liquids, such as fluids discharged from the body, both by means of an absorption mechanism where the fluid is captured by the fiber material itself and by a capillary absorption mechanism where the fluid is acquired by, distributed through and it is stored inside the capillary interstices between the fibers. A means to improve the absorbency characteristics of these fibrous web structures is to incorporate superabsorbent material therein, such as polymeric gelling material (also referred to as hydrogel-forming material, superabsorbent polymers, etc.), the cusils imbibe the fluid. The superabsorbent material serves to retain fluid such as liquids discharged from the body. Such an absorbent structure incorporating particulate hydrogel-forming materials in fibrous webs is disclosed by Weisman and Goldman, U.S. Patent No. 4,610,678, issued September 9, 1986.

The improvement in absorbency provided by the incorporation of gelling absorbent materials has allowed the realization of absorbent articles such as disposable diapers, which employ relatively thin absorbent cores and which are, therefore, relatively thin products. Notwithstanding the existence of absorbent cores as described above, there remains the need to provide absorbent cores that reduce and preferably eliminate the phenomenon referred to as gel on the skin. The gel on the skin is the situation where the gelling absorbent materials escape from the absorbent core and travel through the liner or back sheet on the body side of the absorbent article where they are brought into contact with the wearer's skin. In the continuous placing operations of the prior art, the fibrsis and the superabsorbent materials are mixed together in a continuous web. The continuous web is then cut into individual absorbent members or cores. The individual absorbent members are then placed between a liquid permeable top sheet and a liquid impermeable back sheet to form an absorbent article. Unfortunately, this configuration provides an unsatisfactory product since the gelling absorbent material easily penetrates through the top sheet creating unacceptable amounts of gel on the skin. A solution to the above continuous laying operation was to place another weft such as a tissue or a non-woven web over the top of the continuous web and then cut both the tissue and the continuous web into individual members comprising the core and the web. tissue. The individual members were then placed in the product with the tissue placed between the topsheet and the absorbent core substantially preventing the gelling absorbent material from escaping from the upper surface of the absorbent core and thus reducing the amount of gel on the skin. . r -: ^. ?, ^^. - ^ ^ "- ^ a &tite * J # tix.

Unfortunately, when for example, the tissue and the continuous weft are cut into individual members, the ends of the absorbent core are left open, ie, the ends of the absorbent core are not covered by the suture, allowing the absorbent material to escape from the absorbent core. gelation through the ends of the absorbent core. It is an object of this invention to provide a method for cutting and sealing an absorbent core via a continuous positioning operation which avoids problems of the gel on the skin.

BRIEF DESCRIPTION OF THE INVENTION The invention is a method for cutting and sealing an absorbent member. To form the absorbent member, a web comprising a fibrous material and absorbent material is fed to a station. The weft has a first surface, a second surface, a first side edge and a second side edge. In the station, the operations of applying an agent of obstruction of the movement of the superabsorbent material and cutting the weft into individual absorbent members having a pair of opposite cut ends are carried out simultaneously. The individual absorbent members have a first surface, a second surface, a first side edge, a second side edge, a first end edge and a second end edge with the first and second end edges corresponding to the cutting ends. The obstructing agent of the movement of the superabsorbent material preferably extends from the first lateral edge towards the second lateral edge, and from the first surface towards the second surface of the individual absorbent members.

The absorbent individual members preferably form an absorbent core in a disposable absorbent article and are placed between the liquid permeable topsheet and a liquid impermeable backsheet. As used herein the term "superabsorbent material movement obstructing agent" refers to an external agent applied to a web comprising the fibrous material and the superabsorbent material, which obstructs the movement of the superabsorbent material through the cut end of the superabsorbent material. the plot.

BRIEF DESCRIPTION OF THE DRAWINGS Although the description concludes with the claims that point out in a particular way and claim the present invention differently, it is believed that it will be better understood by the following drawings taken in combination with the accompanying description wherein similar components are given with the same reference number. Figure 1 is a plan view of an absorbent article comprising an absorbent core made in accordance with the method of the present invention. Figure 2 is a simplified schematic illustration of a continuous placement method for forming absorbent cores of the present invention. Figure 3 is an enlarged cross-sectional illustration of a portion of the blade shown in Figure 2. Figure 4 is an enlarged cross-sectional illustration of the simultaneous operation of applying the motion obstructing agent of the superabsorbent material and cutting the plot in absorbent individual members. Figure 5 is a plan view of an individual absorbent member.

Figure 6 is an enlarged cross-sectional illustration of another blade embodiment of the present invention. Figure 7 is an enlarged cross-sectional illustration of another blade embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The method of the present invention is particularly suitable for manufacturing absorbent cores for use in disposable absorbent articles. As used herein, the term "absorbent article" refers to devices that absorb and contain exudates from the body, and, more specifically, refer to devices that are placed against or close to the user's body to absorb and contain the various discharged exudates. coming from the body. The term "disposable" is used herein to describe absorbent articles that are not intended to be washed or restored or reused in another way as an absorbent article (ie, they are intended to be discarded after a simple use and , preferably, to be recycled, composted or otherwise disposed of in an environmentally compatible manner). A "unitary" absorbent article refers to absorbent articles that are formed of separate parts joined together to form a coordinated entity such that they do not require separate manipulated parts such as a separate fastener or liners. A preferred embodiment of a unitary absorbent article comprising an absorbent core manufactured by the method of the present invention is the unitary disposable absorbent article., diaper 20, shown in Figure 1. As used herein, the term "diaper" refers to an absorbent article generally worn by infants and adult incontinent persons and worn around the wearer's lower torso. HE it should be understood, however, that the present invention is also applicable to other absorbent articles such as incontinence briefs, incontinence undergarments, absorbent inserts, diaper liners and liners, feminine hygiene garments, and the like. With reference to Figure 1, an absorbent article, such as diaper 20, generally comprises a liquid-permeable topsheet 22, a liquid-impermeable backsheet 24 bonded to the topsheet 22; and an absorbent core 26 intermediate the topsheet 22 and to the backsheet 24. The diaper 20 preferably further comprises a waist front region 36, a waist back region 38, a crotch region 37 positioned between the waist front region 36 and the rear waist region 38, elasticized leg cuffs 28, ear flaps 30, an elastic waist feature 32 and a fastening system 34 comprising at least one tape tab 40. An example of an absorbent article suitable for which can be inserted the absorbent core of the present invention is more fully and fully described in U.S. Patent No. 5,151,092 issued to Buell et al. On September 29, 1992. The absorbent core 26 of the present invention can be produced on the apparatus 100, as shown in Figure 2. In a preferred embodiment, the apparatus 100 is integrated into an article manufacturing line. disposable absorbent such that the absorbent core 26 of the present invention can be manufactured "in line". (As used herein, the term "integrated" means interconnected process modules that operate concurrently to produce finished products from raw materials.) The term "inline" is used to refer to the manufacturing process of the absorbent cores of the invention. present on an apparatus that is integral with the manufacturing line that produces the disposable absorbent articles to which the tape tabs will be attached. and ^ H ^ Examining the apparatus 100 in greater detail, a web 110 is provided. The web 110 comprises fibrous material and superabsorbent material. The fibrous material may comprise cellulose fibers, in the form of fluff; modified cellulose fibers such as hardened cellulose fibers; synthetic fibers such as those made from cellulose acetate, polyvinyl fluoride, polyvinylidene chloride, acrylics, polyvinyl acetate, non-soluble polyvinyl alcohol, polyethylene, polypropylene, polyamides (such as nylon), polyesters, two-component fibers, fibers of three components, mixtures thereof and the like. Preferred synthetic fibers have a denier of about 3 denier per filament at about 25 denier per filament, more preferably about 5 denier per filament at about denier per filament. Also preferably, the surfaces of the fiber are hydrophilic or are treated to be hydrophilic. Suitable superabsorbent materials include but are not limited to discrete particles of gelling absorbent material and fibrous superabsorbent material such as grafted acrylate fibers and modified superabsorbent fibers. The superabsorbent material can be in any form that can be incorporated in a flexible web or sheet to form the web 110. The superabsorbent material, when in contact with fluids such as water or body fluids, absorbs these fluids. The superabsorbent is typically in the form of discrete particles of gelling absorbent material. The continuous weft 110 is fed to the station 120 in the direction indicated by the arrows shown in Figure 2. The weft 110 has a first surface or uppermost surface 156, a second surface or lowermost opposed surface 148, a first side edge 140 (not shown in Figure 2), and a second side edge 142 opposite. In the station 120 the simultaneous operations of applying the blocking agent of the movement of the superabsorbent material 122 are carried out.

? M? T? T? I screen 110 and cut the weft into individual absorbent members 26 having a pair of opposite cutting ends. The blade 130 performs the simultaneous operations of applying the motion obstructing agent of the superabsorbent material 122 to the weft 110 and cutting the weft into individual absorbent members 26. Of course other wefts can be fed with the continuous weft 110 to station 120. For example, a non-woven fabric or weft can be placed adjacent to the first surface 146 and / or the second surface 148 and the composite material is then fed to station 120. However, for simplicity, it is only shows a simple weft 110 in Figure 2. Figure 3 shows an enlarged cross-sectional illustration of a portion of the blade 130. The blade 130 has a blade 131 defined by the first and second surfaces, 132 and 133, which converge and intersecting one another on the cutting edge 134. The first and second surfaces 132 and 133 each comprise at least, and preferably, a plurality of openings 136 through which the matting obstruction agent can flow. Superabsorbent rial 122. The openings 136 can also be of any shape and size. The number, pattern and spacing of the openings 136 can also be selected as desired. Referring now to Figure 4, as the sheet 131 cuts through the weft 110, the motion obstructing agent of the superabsorbent material 122 flows through the openings 136 and over the cutting ends of the weft 110. Referring now to Figures 4 and 5, the absorbent individual members 26 have first and second end edges 163 and 165 corresponding to the cut ends of the first part. weft 110, a first side edge 160, and a second side edge 162, a first surface or uppermost surface 246, and a second surface or lowermost surface 248. . ^ - * v-.táü, &; *,,. . - - - 2 * Í '< J. * Z¿ ° Á. , > ? ^ ^ ¿_ '. "E-. ^ _ ?.

Preferably, a sufficient amount of superabsorbent material movement blocking agent 122 is applied to the first and second end edges 163 and 165 to completely seal the ends thus preventing the gelling absorbent material from escaping through the ends of the absorbent material. the absorbent members 26. By applying the motion obstructing agent of the superabsorbent material 122 to only the end edges 163 and 165, each individual absorbent member 26 has a pair of discrete, separate spacing zones 243 and 245. 243 is located adjacent the first end edge 163 and the zone 245 is located adjacent the end edge 165. Preferably, a thin film of motion obstructing agent of the superabsorbent material 122 is applied to the weft such that each zone 243 and 245 is relatively thin. However, the motion obstructing agent of the superabsorbent material 122 can migrate inward from the end edges 163 and 165. Preferably, the migration amount of the movement obstructing agent of the superabsorbent material 122 is minimal such that the area 243 and 245 each have a width dimension 270 of less than about 10 cm, more preferably, less than about 5 cm, and most preferably less than about 1 cm. As can be seen in Figure 4 the motion obstructing agent of the absorbent material extends along the end edges 163 and 165 through the total absorbent member 26 from the first surface 246 to the second surface 248. The areas 243 and 245 preferably occupy less than 30% of the volume of the absorbent member 26, more preferably less than 20% of the volume of the absorbent member 26, and most preferably less than 10% of the volume of the absorbent member 26.

The agents suitable for the motion obstructing agent of the superabsorbent material include, but are not limited to, polymeric solutions or emulsions, both natural (eg, natural rubber latex) and synthetic, in which the liquid is water or any other liquid or liquid mixtures suitable. Floating emulsions are preferred and most preferred are floating emulsions of acrylic or vinyl adhesive polymers. Other suitable agents for the motion obstructing agent of the superabsorbent material also include thermoplastic polymers or polymer compositions having a softening point, as determined by the ASTM E28"Ring and Ball" method, within the range of 50 ° C to 50 ° C. 300 ° C.

Preferably, this thermoplastic polymer or polymer composition is a wax or a composition containing at least 50% by weight of a wax, this wax or composition preferably having a softening point less than about 180 ° C: More preferably said thermoplastic agent (being a polymer, a wax or a composition derived therefrom) is or contains at least 50% by weight of a copolymer having at least one of its comonomers, acrylic acid, acrylamide, acrylic esters and / or derived from them. The motion obstructing agent of the superabsorbent material is preferably not applied to the total web, but only in discrete discrete zones. Although the motion obstructing agent of the superabsorbent material provides the benefit of obstructing the movement of the superabsorbent material through the cut end of a weft, it may have some negative effects if applied to the entire weft. For example, the agent may increase the rigidity of the frame such that it becomes uncomfortable for the user if the overall screen is applied. The agent can inhibit some of the absorbent properties of the weft and thus negatively impact the absorbent article which employs a weft having the agent applied to the total weft. Therefore, in order to achieve the desired effect of obstructing the movement of the superabsorbent material through the cut end of a weft without negatively impacting the operation, comfort or other characteristics of the weft and an absorbent article employing said weft , the movement obstruction agent of the superabsorbent material is applied to the weft in only discrete, separate zones. Referring now to Figure 6 there is shown an enlarged cross-sectional illustration of another blade embodiment of the present invention. The blade 330 has a blade 331 defined by the first and second surfaces, 332, and 333. Unlike the blade 130 illustrated in Figure 3, the first and second surfaces 332 and 333 of the blade 330 do not intersect each other at the individual cut edge. In contrast, the first and second surfaces 332 and 333 converge towards a pair of cutting edges 334 and 335. Between the cutting edges 334 and 335 is a slot 336 through which the motion obstruction agent of the superabsorbent material. Referring now to Figure 7 there is shown an enlarged cross-sectional illustration of another blade embodiment of the present invention. The blade 430 has a blade 431 defined by the first and second surfaces, 432 and 433. Similar to the blade 330 shown in Figure 6, the first and second surfaces 432 and 433, do not intersect one another on a single cutting edge. . Instead, they converge towards a pair of cutting edges 434 and 435. Furthermore, a third cutting edge 437 is positioned between cutting edges 434 and 435. The third cutting edge 437 may extend outwardly from the blade 430 to the same distance as the edges 434 and 435, greater than the edges 434 and 435, or less than the edges 434 and 435. Preferably, the third cutting edge 437 extends outwardly of the blade 430 more than the edges 434 and 435. Between the cutting edges 434 and 437 there is a first slot 438 and between the cutting edges 4 and 5 and ^^? ^^^ g * ^ j ^^^ 437 is a second slot 439. The motion obstructing agent of the superabsorbent material can flow through each of the slots 438 and 439. In another embodiment of the method of the present invention, the movement obstructing agent of the superabsorbent material is transferred to the blade from an external device such as a rubber roller, a slot coater, a spray gun, or any other suitable means known in the art. Subsequently, the motion obstructing agent of the superabsorbent material is transferred. When incorporated into an absorbent article, such as the diaper 20 shown in Figure 1, the areas 243 and 245 of the absorbent member 26 are preferably positioned within the waist front region 36 and the waist rear region 38, respectively. Although the zones 243 and 245 may be of such a dimension that they extend into the crotch region 37, this is not preferred. Although the particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to protect in the appended claims all these changes and modifications that are within the scope of this invention.

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Claims (10)

1. A method for cutting and sealing an absorbent member (26), the method comprising the steps of: a) feeding a web (110) comprising a fibrous material and a superabsorbent material, the web having a first side edge (140) and a second side lateral bank (142); and b) simultaneously applying a motion obstructing agent of the superabsorbent material (122) to said weft and cutting the weft into individual absorbent members (26) having a pair of opposite cut ends.

The method according to claim 1, wherein the individual members (26) have a first surface (246), a second surface (248), a first side edge (160), a second side edge (162), a first end edge (163) and a second end edge (165), said first and second end edges corresponding to the cut ends, and discrete, spaced sealing zones (243, 245).

3. The method according to claim 2, wherein each zone extends from the first lateral edge to the second lateral edge and from the first surface to the second surface.

4. The method according to any of claim 2 or 3, wherein the areas of the movement obstructing agent of the superabsorbent material have a width less than about 10 cm.

The method according to any of claim 2 or 3, wherein the areas of the movement obstruction agent of the superabsorbent material have a width of less than about 5 cm. - - »^« s- - ^ a-a > -. »> --- - ,""TO.

6. The method according to any of claim 2 or 3, wherein the areas of the movement obstruction agent of the superabsorbent material have a width of less than about 1 cm. The method according to any of the preceding claims, wherein the movement obstruction agent of the superabsorbent material is a material selected from the group of solutions, or polymeric emulsions. The method according to any of claims 1 to 6, wherein the movement obstructing agent of the superabsorbent material is a thermoplastic polymer or a polymeric composition having a softening point within the range of 50 ° Celsius and 300 ° Celsius. The method according to claim 8, wherein the thermoplastic polymer or the polymer composition is a wax or a composition containing at least 50% by weight of a wax. The method according to claim 7, wherein the polymeric solutions or emulsions are either natural or synthetic. • > L- ^ ¿«i ^ ~. ,, ._ ^ ._ ^ faith., .1 .- »*. < * AM¡b! Í ~ *, _ ^^ Ai, V ^. _ ", -.-,., ..