KR100256468B1 - Crimping of a fibrous web to a tissue - Google Patents

Abstract

The present invention relates to an absorbent article having an absorbent core 16 comprising a plurality of absorbent layers 10, 16 connected to one another. In particular, the present invention relates to an absorbent structure in which one of the absorbent layers 16 is shorter in the manufacturing direction than at least one other layer 10 and is connected by crimps 14 to at least one other layer 10. The invention also relates to a method of crimping a central patch of a fibrous web onto a tissue.

Description

Multilayer structured absorbent core with fiber web crimped on tissue and its manufacturing method {CRIMPING OF A FIBROUS WEB TO A TISSUE}

U. S. Patent No. 3,661, 680 discloses a method for producing an absorbent core comprising a tissue, an air layer and a laminated structure of tissue. However, this method does not disclose joining the absorbent core by crimping it along the longitudinal line selected by the pressure roll. No mention is made of crosslinked fibers and superabsorbent polymers.

EP 593 relates to improving pad integrity by the use of selected tissues located between the fiber pads. This is therefore the closest prior art to the basic core configuration according to the invention. However, only compression for compaction was mentioned, not crimping for connecting the fiber pad to the tissue at all.

EP 21662 relates to the improvement of wicking force by the use of a specific pattern of embossing the fiber core on tissue. However, no advantages are indicated for core integrity and the method for making the absorbent core construction does not mention crimping other than showing the patterned compression rolls.

EP 214190 discloses crimping of multilayer tissues for immobilizing the particles trapped between the layers. The basic principle of the longitudinal crimping line is also described but no crosslinked fiber patches are mentioned.

EP 214867 discloses a fibrous structure having an embossed suction line. It is not about core integrity, but about the location of the structure in the product. No crimping of the tissue for the fiber material is mentioned and no crosslinked fibers are disclosed.

EP 399564 discloses an improvement in wicking force due to the selective density of the web of crosslinked cellulose. However, although densification by calendering is disclosed, there is no discussion of tissue crimping or core integrity improvement to the pad.

When making an absorbent article, it is desirable to have discrete patches of absorbent patches disposed on continuous bands of absorbent material (eg tissue). This is especially true for high efficiency but expensive crosslinked fibers that are currently being used even more in the industry. In particular, when using high speed machines, discrete patches must be connected to a continuous band, otherwise they will not be able to transport them. This is usually done by adhering the patch to a tissue.

However, the induced and induced ends of the patch suffer from adhesion problems due to the on-off nature of the adhesive delivery and application device, and may also impair manufacturing efficiency due to adhesive contamination. Therefore, the inducing end of the patch and the inducing end of the patch are only attached to the tissue only occasionally in the center without being attached to the tissue. However, non-bonded patches are more likely to be produced during the manufacturing process, which further reduces productivity. If the method of making the absorbent core includes a point of rotation (known to be useful for obtaining a particular product) in which the band of material already bound is reversed, all of these problems will be further exacerbated.

It is therefore a problem underlying the present invention to provide an absorbent core comprising a first absorbent structure, a tissue and a second absorbent fibrous structure that is shorter than the tissue in one direction and otherwise does not extend out of the perimeter of the tissue. The tissue is crimped to the second absorbent structure.

Preferably the crimping is carried out along one or several separate lines. Although not essential to the present invention, it is preferred that the interface between the tissue and the second absorbent structure contain no adhesive.

A further aspect of the invention is a continuous tissue placed on a conveyor belt; Forming a second absorbent fibrous structure in a discontinuous arrangement on the continuous tissue; The tissue and the second absorbent fibrous structure are connected to each other by crimping; After forming the first absorbent structure as a continuous band and placing it onto the tissue on the opposite side from which the second fiber structure is located, finally the continuous band of tissue and the first absorbent structure is formed with one second absorbent structure and its A continuous process for producing an absorbent core in accordance with the disclosure, comprising cutting between the following second absorbent structures.

The present invention relates to an absorbent article having an absorbent core comprising a plurality of absorbent layers connected to one another. In particular, the present invention relates to an absorbent structure in which one of the absorbent layers is shorter in the machine direction of the absorbent article than at least one other layer and is connected by crimping to at least one other layer. The present invention also relates to a method of crimping a central patch of a fibrous web on a tissue to replace an adhesive that was previously necessary and to each of the methods for making such an absorbent structure or an embodiment of the invention.

1 shows a plan view of tissue continuously crimped on a second absorbent fibrous structure.

2 is a cross-sectional view of the embodiment of the invention of FIG. 1 along line 2/2.

3 is a cross-sectional view of the embodiment of the invention of FIG. 1 along line 3/3.

4 is a plan view of a prior art tissue and second absorbent fibrous structure bonded to each other.

5 is a cross-sectional view of the prior art embodiment of FIG. 4 along line 5/5.

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

The invention relates to an absorbent core which extends along a first axis and a second axis perpendicular to it and which is produced in the direction of the first axis. The absorbent core includes a first absorbent structure, a tissue and a second absorbent structure having the same first axis and second axis as the absorbent core. Such tissue has a first surface and a second surface and has a length substantially equal to the first absorbent structure along the first axis.

The second absorbent structure is shorter than the tissue along the first axis and does not extend beyond the circumference of the tissue in the direction of the first axis, preferably in any direction. Typically the second absorbent structure is preferably an absorbent fibrous structure comprising crosslinked fibers.

The first absorbent structure can be selected from a variety of absorbent structures, but also preferably comprises fibers, in particular together with the polymeric absorbent gelling material (most preferably in particulate form). Such absorbent gelling material may also be present in the second absorbent structure.

The first absorbent structure is adjacent to the first surface of the tissue and extends together along the first axis with the tissue. The absorbent core is configured such that the second surface of the tissue and the second absorbent structure are connected to each other by crimping.

In a preferred embodiment according to the invention, the second absorbent structure does not extend to the circumference of the tissue. However, the crimping portion extends along at least one end of the second absorbent structure along the first axis, preferably the crimping portion extends to both ends of the second absorbent structure along the first axis and the crimping portion is continuous for simplicity of manufacture. Most preferably it extends along the entire length of the tissue along the first axis.

The crimp can form one of several separate lines along the first axis, and is preferably used to replace the adhesive on the second surface of the tissue so that the surface is not blocked by the adhesive, the adhesive heating, adhesive delivery and application device, And by eliminating the problems associated with the on-off cycle of adhesive application required.

The present invention therefore also relates to a continuous process for the production of the absorbent core of the present invention. This method involves placing a continuous tissue on a conveyor belt; Forming a second absorbent fibrous structure in a discontinuous arrangement on the second side of the tissue; The tissue and the second absorbent fibrous structure are connected to each other by crimping; Forming a first absorbent structure as a continuous band and placing it on the first side of the tissue; Cutting the continuous band of tissue and the first absorbent structure between one second absorbent structure and the next second absorbent structure.

The absorbent cores according to the invention can be used in all kinds of absorbent articles, in particular disposable absorbent diapers for infants, children or adults as well as incontinence inserts or sanitary napkins.

1 shows a continuous tissue 10 having a first axis 100 and a second axis 200 perpendicular thereto. The tissue is underneath the second absorbent structure 16, which shares the axes 10 and axes 100 and 200. The tissue 10 and the second absorbent structure 16 are connected by a crimp line 14. The direction of movement during the manufacturing process is parallel to the first axis 100. In cross-section of this core portion according to the invention in FIG. 2, it can be seen that the second absorbent structure 16 is located on the second surface of the tissue 10 and connected to the tissue along the crimp line 14. Can be. Although not shown in the figures, part of the absorbent core of the present invention is a continuous first absorbent structure located on the first side of the tissue 10, ie opposite the second side.

In another cross section along line 3-3 of FIG. 1, we can see the crimp line 14 in which the second absorbent structure 16 and the tissue 10 are compressed together in the crimping process.

4 shows a prior art structure which also has a first axis 100, a second axis 200 of the tissue 10 and the second absorbent structure 16. However, in this prior art embodiment, the connection between the second absorbent structure 16 and the tissue 10 leaves an unbonded end 18 between the second absorbent structure 16 and the tissue 10. Provided by 12.

As can be seen from FIG. 5, the unbonded end 18 of the second absorbent structure 16 can be easily lifted from the tissue 10 as the tissue moves in a direction parallel to the first axis 100. Also, the butterfly / length of the adhesive line 12 is considered, since the liquid deposited on one side of the absorbent core must be communicated through a plane, where the adhesive blocks the butterfly and the communication across the length of the adhesive line 12. Should be.

As used herein, the term "disposable absorbent product" refers to a product that absorbs and sequesters body secretions, and more specifically, absorbs various secretions that are discharged from the body of the wearer opposite or located closely to the wearer's body. And other methods that are encapsulated absorbent products that are not intended to be washed or otherwise restored or reused as absorbent products (ie, intended for disposal after single use, preferably recycled, fertilized or environmentally acceptable). Product intended for disposal). An embodiment of the disposable absorbent article of the present invention is an adult incontinence brief or infant, child's diaper. Examples of the type of diaper to which the present invention is easily applied are shown in US Patent RE 26,151, US Patent 3,860,003, 4,253,461 and 7,704,115.

Generally the absorbent core according to the invention is useful in all disposable absorbent articles.

As used herein, the term "absorbent core" refers to all absorbent means in a disposable absorbent article. According to the invention, the absorbent core comprises first and second absorbent structures separated by tissues located therebetween. However, additional absorbent layers may be included in the absorbent core if deemed appropriate for the particular use of the absorbent article.

With reference to absorbent diapers hereinafter, sanitary napkins, menstrual articles, panty liners or incontinence inserts may be the final product in which the absorbent structure according to the invention may be used, so the following description should not be misunderstood.

The outer surface of the diaper is generally the surface furthest from the wearer while using the diaper. The back sheet preferably forms most of the outer surface. The inner surface is the surface of the diaper opposite the outer surface and is preferably formed by the top sheet. Preferably, the inner surface of the diaper extends along with the outer surface and in general the larger portion that the wearer contacts when the diaper is used is the inner surface. In general, the outer and inner surfaces comprise absorbent cores such that the top and back sheets extend beyond the core and are connected to each other.

The first and second absorbent structures of the present invention are generally compressible, comfortable and non-irritating to the wearer's skin and may include any absorbing means capable of absorbing and retaining liquids such as urine, menstrual blood and other body secretions. . Absorbent structures are of a variety of liquids commonly used in disposable absorbent products of various sizes and shapes (e.g. rectangular, hourglass, asymmetric, T-shaped, etc.) and also finely divided wood pulp, commonly referred to as air felts. It can be prepared from an absorbent material. Examples of other suitable absorbent materials include creped cellulose filler, meltblown polymers comprising co-formed and crosslinked cellulose fibers, tissues including tissue wraps and tissue laminates, absorbent foams, absorbent sponges, superabsorbent polymers, Absorbent gelling materials or any equivalent materials or mixtures of such materials. The arrangement and configuration of the absorbent core may also vary, for example, the absorbent core may have varying caliper regions, hydrophilic gradients, superabsorbent gradients (such as in the concentration or particle size of granular superabsorbents) or lower average density and more. May have a low average basis weight capture zone; Or one or more layers or structures. However, the total absorbent capacity of the absorbent core must be compatible with the intended secretion load and the intended use of the core.

A preferred embodiment of the diaper is an hourglass absorbent core. Exemplary absorbent structures that can be easily adapted for use in the absorbent core of the present invention are disclosed in US Pat. Nos. 4,610,678, 4,673,402 and 4,888,231. The absorbent core can also be applied from commercially successful absorbent members described in US Pat. No. 4,834,735 entitled "High Density Absorbing Members with Lower Density and Lower Basis Weight Capture Zones." Other preferred absorbent cores are disclosed in US Pat. Nos. 4,685,915 and 4,781,710, including fiber structures having regions of different absorption capacities, densities or liquid capture rates. Optional thin absorbent cores useful in the present invention can be found in US Pat. No. 4,600,458. Another preferred absorbent core design provides a crosslinked cellulose patch that is essentially free of a superabsorbent on top of the airfelt, with a superabsorbent mixture comprising more than 30% superabsorbent.

Preferably the second absorbent structure comprises crosslinked fibers, in particular crosslinked cellulose fibers. In general, the first and second absorbent structures may comprise the same absorbent material, which may be any known in the art. The difference between the first and second absorbent structures according to the invention depends on the application of the individual structures to the specific function in the particular absorbent product, in which the absorbent core is designed to suit this.

The tissue used between the first and second absorbent structures according to the present invention may be any kind of crimpable tissue useful in the art. Tissues comprising wood pulp fibers are generally used, but the tissue fibers may comprise natural fibers as well as synthetic fibers or the tissue itself may be interposed between laminates or layers comprising several layers of various tissue-like materials. It may also be a laminate structure comprising certain materials such as, for example, superabsorbent polymers.

The absorbent core is superimposed on the back sheet and is preferably connected to the back sheet by core attachment means.

The back sheet is impermeable to liquids (eg urine) and is preferably made from thin plastic films, preferably thermoplastic films, although other flexible liquid impermeable materials may also be used. As used herein, the term "flexible" refers to a material that is free to move and easily adheres to the general shape and contour of the human body. The back sheet is absorbed in the absorbent core and prevents the contained secretions from contaminating products facing diapers such as bed sheets and undergarments.

The back sheet may thus comprise a polymeric film, such as a thermoplastic film of polyethylene or polypropylene, or a composite material, such as a film-coated nonwoven material. For economic, aesthetic and ecological reasons, the back sheet preferably has an average nominal thickness of less than about 0.051 mm, ie a calculated thickness, more preferably a calculated thickness of 0.020 to 0.036 mm. Preferably, the back sheet is a flexible polyethylene film. Exemplary films for use as the back sheet of the present invention include BP, Tredegar Industries, Inc., Ter Haute, Indiana, USA, or Rothbuchenstrasse 1, De-8000 Munich, Germany. It is made from BP-Chemical PlasTec.

The top sheet, which forms the inner surface of the absorbent article, is free to move, soft to the touch and non-irritating to the wearer's skin. The top sheet is also liquid permeable, allowing liquid (eg, urine) to be easily permeable through its thickness. Suitable top sheets include porous foams, reticulated foams, perforated films; Or from a wide variety of materials, such as woven or nonwoven webs of natural fibers (wood or cotton fibers), synthetic fibers (such as polyester or polypropylene fibers) or mixtures of natural and synthetic fibers. Preferably, it is made of a material that isolates the wearer's skin from the liquid retained in the absorbent core.

The diaper preferably further comprises one or several resilient leg cuffs to provide improved liquid and other body secretion retention. Each resilient leg cuff may include several different embodiments to reduce leakage of body secretions in the leg area (leg cuffs may be referred to as leg bands, side flaps, blocking cuffs or elastic cuffs as the case may be). Can be). U.S. Patent No. 3,860,003, entitled "Shrinkable Sides for Disposable Diapers," discloses a disposable product that provides a retractable leg opening with a side flap and an elastic member to provide an elasticized leg cuff. have. U.S. Patent No. 4,909,803 entitled "Disposable Absorbent Products with Elasticized Flaps" discloses disposable diapers with "stand-up" resilient flaps (blocking cuffs) to enhance the barrier area. It is. U.S. Patent No. 4,695,278, entitled "Absorbent Product with Double Cuffs," discloses disposable diapers having double cuffs that include cuffs and blocking cuffs. US Pat. No. 4,704,115, entitled “Disposable Waist Blocking Garment,” describes a disposable diaper or incontinence with side-edge-leakage-guard gutters arranged to contain glass liquid in the garment. A garment is disclosed.

The diaper may also further comprise an elastic waist that provides improved wear and barrier properties or any other element generally provided on diapers or incontinence garments known in the art.

The crimping according to the present invention typically applies a high pressure between the hammer and the anvil roll so that a local high density pattern (here, the tissue and the second absorbent fibrous structure are pressed against each other, due to their cohesion and adhesion, Absorbent structure efficiently connected to tissue).

There is no special requirement for the crimping pattern. However, since high density lines in absorbent products are known to be advantageous for liquid distribution in such absorbent products and crimp lines represent high density lines, crimp lines can be formed to perform some or all of the liquid dispensing function, individually The high density lines formed can be incorporated into the absorbent core in other ways. The crimp lines can also be replaced by other patterns that are known to be advantageous for liquid distribution, aesthetic considerations, and the like.

For crimping, heated or cold crimping rolls can be used. The primary purpose of the crimp is to securely secure the ends of the absorbent second structure to the tissue so that they do not separate during the manufacturing process. However, if properly manufactured, the crimping line will continue to hold the second absorbent structure in the tissue while using the absorbent article, thus improving core integrity without the need for other core bonding means.

Claims (12)

1. An absorbent core extending along a first axis and a second axis perpendicular to the first axis and manufactured in the direction of the first axis, wherein A first absorbent structure having the same first axis and second axis as the absorbent core; A tissue having a first surface and a second surface, the tissue having a length substantially the same as the first absorbent structure along the first axis; And a second absorbent structure having the same first axis and second axis as the absorbent core, fibrous and shorter than the tissue along the first axis and not extending beyond the circumference of the tissue in the direction of the first axis. Wherein the first absorbent structure is adjacent to the first surface of the tissue and extends along with the tissue along the first axis, wherein the second surface of the tissue and the second absorbent structure are crimped. Absorbent core, characterized in that configured to be connected to each other by. The method of claim 1, And wherein the second absorbent structure does not extend to the circumference of the tissue in any direction. The method according to claim 1 or 2, An absorbent core in which said second absorbent structure comprises crosslinked fibers. The method of claim 1, And the first absorbent structure comprises a polymeric absorbent gelling material. The method of claim 1, And the crimp is formed along at least one end of the second absorbent structure along the first axis. The method of claim 1, Said crimp forming an one or several distinct lines along said first axis. The method of claim 1, An absorbent core wherein the second surface of the tissue does not contain an adhesive. The method of claim 1, Absorbent cores included in disposable absorbent diapers, incontinence inserts or sanitary napkins for infants, children or adults. A continuous tissue is placed on the conveyor belt; Forming a second absorbent fibrous structure in a discontinuous arrangement on the second face of the continuous tissue; Connecting the tissue and the second structure by crimping; Forming a first absorbent structure as a continuous band and placing it on the first side of the tissue; And cutting the continuous band of tissue and the first absorbent structure between one second absorbent structure and the second absorbent structure following. The method of claim 9, And wherein the crimp is continuously made between the one second absorbent fibrous structure and the next second absorbent fibrous structure. The method of claim 4, wherein And the second absorbent structure comprises a polymeric absorbent gelling material. The method of claim 5, And the crimp is over the entire length of the tissue along the first axis.