JP2003509162A - Grooved absorbent composite - Google Patents

Abstract

(57) Abstract: A fiber-absorbing composite material containing an absorbent material, a method for forming the same, and an absorbent article containing the composite material are described. The composite material (10) is a fibrous structure and includes dispersed absorbent material throughout the composite material (14) and at increased concentrations in the stripes (12) extending along the length of the composite material. .

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates generally to absorbent composites, and more particularly to air-laid composites that include absorbent materials. BACKGROUND OF THE INVENTION Cellulose fibers derived from wood pulp are used in various absorbent articles such as diapers, incontinence products, and feminine hygiene products. The absorbent article should have large liquid absorption capacity, rapid liquid entrapment, low rewet, and good dry and wet strength properties for durability in use and effective fluid handling. Is desirable. The absorbent capacity of articles made from cellulosic fibers is
Often enhanced by the addition of absorbent materials such as superabsorbent polymers. Superabsorbent polymers known in the art have the ability to absorb 5-100 times their weight or more liquids. Therefore, in the presence of superabsorbent polymer,
The liquid holding capacity of absorbent articles made from cellulose is significantly increased.

However, absorbent composite materials containing superabsorbent materials generally suffer from gel blocking. Upon absorption of liquid, the superabsorbent material tends to agglomerate to form a gelatinous mass that prevents liquid wicking into the non-wetting portion of the composite. By blocking the distribution of the entrapped liquid in the non-wetting part of the composite, gel blocking interferes with the effective and efficient use of superabsorbent materials in fiber composites. In general, the wicking capacity of conventional fiber composites containing a relatively uniform distribution of superabsorbent material is significantly reduced after the initial liquid insult.
The reduced volume of such fiber composites is due to the narrowing of the capillary capture and distribution channels as the superabsorbent material swells. The reduced absorption capacity and concomitant loss of the capillary distribution channel in conventional absorbent cores containing absorbent material is manifested by reduced liquid capture rates and liquid distribution in continuous liquid inserts far from ideal. Become.

Accordingly, an absorbent composite material that includes a superabsorbent material and that effectively captures and wicks liquid throughout the composite material and distributes the captured liquid to the absorbent material, wherein the liquid There is a need for absorbent composites that absorb and retain efficiently without gel blocking. There is also a need for absorbent composites that continue to capture and distribute liquid throughout the composite in continuous liquid inserts. In addition, there is a need for absorbent composite compositions containing superabsorbent materials that exhibit advantages over wet-laid composites, including wet strength, absorption capacity and scavenging, liquid distribution, softness, and resilience. is there. The present invention aims to meet these needs and provides further related advantages. SUMMARY OF THE INVENTION In one aspect, the present invention provides a fiber-absorbent composite material that includes the absorbent material distributed throughout the composite material and in selected areas of the composite material. Varying the concentration of absorbent material in these regions can provide composite materials with varying concentrations of absorbent material. In one aspect, the composite material comprises striped dispersed absorbent material that extends across the width of the composite material and extends along the length of the composite material. Upon contact with a liquid, the absorbent material-rich stripes of the composite material swell with the entrapped liquid and expand to rise from the wet surface of the composite material to form a ridge and provide a grooved structure. . The grooved structure of the wet composite improves liquid wicking, entrapment, and subsequent distribution in liquid inserts.

In another aspect of the invention, there is provided a method of forming an absorbent composite material having a variety of absorbent material contents. In one aspect, the method comprises increasing the concentration of absorbent material in the composite material by adding absorbent material to selective regions of the composite material. In another aspect, the method provides for selectively increasing the basis weight of the composite material to form regions of increased absorbent material concentration in the composite material. In the method, a composite material is formed by selectively densifying a substantially homogeneous composite material containing fibers and absorbent material. Detailed Description of the Preferred Embodiments Many of the foregoing aspects and related advantages of the present invention will be better understood by taking the following detailed description into consideration when taken in conjunction with the accompanying drawings. , Will be more easily understood.

The absorbent composites of the present invention are fiber composites and include absorbent material distributed throughout the composite and in selected areas of the composite. Varying the concentration of absorbent material in these regions can provide composite materials with varying absorbent material content. In one aspect, the absorbent composite has a width of the composite (
That is, it includes striped dispersed absorbent material that extends across the cross-machine direction and extends along the length of the composite (ie, the machine direction). The distribution zones, which consist mainly of fibers, lie between the absorbent material-rich stripes of the composite. The fiber distribution zone of the composite material serves to trap the liquid that contacts the composite material, distribute the captured liquid throughout the composite material, and ultimately to the absorbent material. The absorbent material serves to absorb and retain the liquid entrapped by the composite material.

[0006] Absorbent composite materials are used in a variety of absorbent articles, such as diapers, including disposable diapers and training pants; feminine care products, including sanitary napkins, tampons, and panty liners; adult incontinence products; toweling fabrics. It can be advantageously incorporated into surgical and dental sponges; bandages; food tray pads and the like. Since the composite material is highly absorbent, the composite material can be included as a liquid storage core in an absorbent article. In such a structure, the composite material may be one or more of:
It can be combined with other composite materials or layers, including, for example, acquisition and / or distribution layers. Because of the capacity of the composite material to rapidly capture and dispense liquid, the composite material can also serve as a liquid treatment layer that captures and releases a portion of the captured liquid to the underlying storage core. Thus, in other embodiments, absorbent composites can be combined with storage cores to provide useful absorbent structures for absorbent articles.

The absorbent composite material of the present invention is a grooved storage composite material. As used herein, the term "grooved" refers to the property of composite materials that, when wet, causes the absorbent material to expand, resulting in ridges and a grooved structure. As noted above, the composite material includes regions rich in absorbent material (ie, stripes) distributed across the width of the composite material and extending in stripes along the length of the composite material. Upon contact with the liquid captured by the fibrous composite, the absorbent material swells into a wet composite having ridges containing the swollen absorbent material. The ridges of the composite material are separated by distribution zones or channels, which are fiber regions of the composite material that contain a lower amount of absorbent material as compared to the absorbent material-rich region of the composite material. .

The fringe properties of the inventive grooved absorbent composite are illustrated in FIGS. With reference to FIGS. 1 and 2, an exemplary grooved absorbent composite formed in accordance with the present invention and indicated generally by the reference numeral 10 is an absorbent material-rich region 12 (ie, a liquid storage zone) and generally fibers. Region, and includes region 14 (ie, the liquid distribution zone) that contains a relatively smaller amount of absorbent material than region 12.

When the absorbent composite material comes into contact with the liquid, the liquid is rapidly captured, primarily by the fibrous regions of the composite material. The fiber regions are relatively open and porous in nature, facilitating rapid liquid capture, wicking, and dispensing. The liquid captured by the composite material generally travels rapidly through the distribution zone (ie, region 14), longitudinally through the fibrous composite material along the length of the composite material, and the composite material rich in absorbent material. It is absorbed by a region of material (ie region 12). The entrapped liquid is generally wicked laterally into the absorbent material as the liquid is distributed along the length of the composite material.

For grooved composites, continuous liquid inserts are absorbed at an even faster rate due to the establishment of grooves and corresponding channels in the initial liquid insert. Upon wetting, the composite material of the present invention becomes a grooved structure having a channel for rapid capture of additional liquid and distribution of the liquid to a site remote from the insert. . For grooved composites, the subsequent liquid insult capture time is generally shorter than for the first capture. Reduced acquisition time of continuous liquid inserts is generally not observed in conventional absorbent structures. The capture time of these structures is generally long with continuous liquid insults, as conventional absorbent structures are unable to form grooved structures and therefore lack channels for additional liquid distribution. Become. The increased capture time is believed to be due to the fact that the liquid is only gradually captured and is distributed through the saturated region of the composite material to more distant regions of the composite material that can absorb the liquid. To be Thus, the grooved absorbent composite material generally provides an initial liquid capture rate that is comparable to or faster than that of conventional absorbent structures. The composite material also has a significantly higher liquid capture rate for continuous liquid capture compared to conventional composite materials.

The wetting structure of the grooved absorbent composite of the present invention is shown in FIGS. 3 and 4. These figures illustrate the groove nature of the composite material, which is due to contact with liquid and swelling and expansion of the absorbent material. With reference to FIGS. 3 and 4, regions 12 (ie, liquid storage regions) rich in absorbent material are shown as ridges separated by regions 14 (ie, liquid distribution zones), where regions 14 are ridges. Forming a valley floor or flow path. Due at least in part to the grooved structure of the wet fiber composite, the subsequent liquid insult may be a composite material that contains the absorbent material in another arrangement, e.g., the absorbent material substantially throughout the composite material. Absorbed more quickly by the composite material as compared to the evenly distributed composite material.

Fibers are the major component of the grooved absorbent composites of the present invention. Fibers suitable for use in the present invention are known to those of skill in the art and include any fiber capable of forming an absorbent composite. Suitable fibers include natural and synthetic fibers. Fiber combinations, including synthetic and natural fibers and combinations of treated and untreated fibers, can also be suitably used in the composite. In a preferred embodiment, the absorbent composites of the present invention include cellulosic fibers, hardwood fibers, chemisothermomechanical pulp fibers (ie, CTMP), and more preferably crosslinked cellulosic fibers.

[0013] Generally, the fibers are present in the composite in an amount of about 20 to about 90% by weight, preferably about 50 to about 70% by weight, based on the total weight of the composite. In a preferred embodiment, the composite material comprises about 60% by weight fiber.

Cellulosic fibers can be a basic component of grooved absorbent composites.
Although available from other sources, cellulosic fibers are primarily derived from wood pulp. Wood pulp fibers suitable for use in the present invention can be obtained by well known chemical methods such as the Kraft method and the sulfite method, with or without subsequent bleaching. Pulp fibers may also be processed by thermomechanical methods, chemithermomechanical methods, or combinations thereof. Preferred pulp fibers are produced by chemical methods. Ground wood fiber, recycled or secondary wood pulp fiber,
And bleached and unbleached wood pulp fibers can be used. The details of selecting wood pulp fibers are well known to those skilled in the art. These fibers are
It is commercially available from many companies, including the Weyerhaeuser Company, the assignee of the present invention. For example, suitable cellulosic fibers made from Southern Pine that can be used in the present invention are CF416, NF405, PL416.
, FR516, and NB416 under the name Weyerhaeuser Comp
Available from any.

The wood pulp fibers of the present invention can also be pretreated prior to use in the present invention.
This pretreatment may be a physical treatment, such as exposing the fibers to steam, or a chemical treatment, such as
It may include crosslinking the cellulosic fibers with any one of a variety of crosslinking agents. Crosslinking increases the bulk and resilience of the fibers, which can improve the absorbency of the composite. Generally, crosslinked fibers are twisted or crimped. The use of crosslinked fibers allows the composite material to be more elastic, softer, bulkier and have improved wicking. Suitable crosslinked cellulosic fibers made from Southern Pine are available from Weyerhaeuser Company under the name NHB416. Crosslinked cellulosic fibers and methods for their preparation are described in Graef et.
al. U.S. Pat. Nos. 5,437,418 and 5,225,047, which are specifically incorporated herein by reference.

Crosslinked fibers are prepared by treating the fibers with a crosslinking agent. Suitable cellulosic crosslinkers include adducts of aldehydes and urea-based formaldehyde. For example, U.S. Pat. Nos. 3,224,926, 3,241,533, 3,932,209, 4,035,147, 3,756,913, 4,689,118, and 4822.
453, U.S. Pat. No. 3,440,135 issued to Chung, Lash e
t al. U.S. Pat. No. 4,935,022 issued to Herron et a
l. U.S. Pat. No. 4,889,595, Shaw et al. No. 3819470, issued to Steijer et al. U.S. Pat. No. 3,658,613, issued to Graef et al. See U.S. Pat. No. 4,853,086 issued to U.S. Pat. All of these are specifically incorporated herein by reference in their entireties. Cellulose fibers are also crosslinked with carboxylic acid crosslinkers including polycarboxylic acids. U.S. Patent Nos. 5,137,537, 51837
The 07 items, and No. 5,190,563, at least three of C ₂ -C ₉ polycarboxylic acids containing carboxyl groups (e.g., citric acid and oxy disuccinic acid) used as a crosslinking agent is described.

Suitable urea crosslinkers include methylolated urea, methylolated cyclic urea, methylolated lower alkyl cyclic urea, methylolated dihydroxy cyclic urea, dihydroxy cyclic urea, and lower alkyl substituted cyclic urea. Specific preferred urea crosslinking agents include dimethyldihydroxyurea (DMDHU, 1,3-dimethyl-
4,5-dihydroxy-2-imidazolidinone), dimethylol-dihydroxyethyleneurea (DMDHEU, 1,3-dihydroxymethyl-4,5-dihydroxy-2-imidazolidinone), dimethylolurea (DMU, bis [N- (Hydroxymethyl] urea), dihydroxyethyleneurea (DHEU, 4,5-dihydroxy-2-imidazolidinone), dimethylolethyleneurea (DMEU, 1,3)
-Dihydroxymethyl-2-imidazolidinone) and dimethyldihydroxyethyleneurea (DDI, 4,5-dihydroxy-1,3-dimethyl-2-imidazolidinone).

Suitable polycarboxylic acid crosslinkers include citric acid, tartaric acid, malic acid, succinic acid,
Glutaric acid, citraconic acid, itaconic acid, tartrate monosuccinic acid (tartrate mo
nosuccinic acid), and maleic acid. Other polycarboxylic acid crosslinking agents include poly (acrylic acid), poly (methacrylic acid), poly (maleic acid), poly (
Included are polymeric polycarboxylic acids such as methyl vinyl ether-co-maleate) copolymers, poly (methyl vinyl ether-co-itaconate) copolymers, copolymers of acrylic acid, and copolymers of maleic acid. The use of polymeric polycarboxylic acid crosslinkers, such as polyacrylic acid polymers, polymaleic acid polymers, copolymers of acrylic acid, and copolymers of maleic acid, was reported December 12, 1997.
It is described in US patent application Ser. No. 08/989697 assigned to Weyerhaeuser Company. Mixtures or blends of crosslinkers may also be used.

The cross-linking agent can include a catalyst for promoting the bonding reaction between the cross-linking agent and the cellulose fiber. Suitable catalysts include ammonium chloride, ammonium sulfate, aluminum chloride, magnesium chloride, and acid salts such as alkali metal salts of phosphorus-containing acids.

While not to be construed as limiting, examples of fiber pretreatments include the application of surfactants or other liquids that modify the surface chemistry of the fibers. Other pretreatments include the incorporation of antimicrobials, pigments, dyes and densifying or softening agents. Fibers pretreated with other chemicals such as thermoplastics and thermosets may also be used. A combination of pretreatments can also be used. Similar treatments can be applied after composite material formation in the post treatment step.

Cellulosic fibers treated with particulate binders and / or densification / softening aids known in the art can also be used in accordance with the present invention. The particulate binder serves to attach other materials such as cellulosic fiber superabsorbent polymers as well as others to cellulosic fibers. Suitable particle binder and / or densification /
Cellulosic fibers treated with softening aids and methods of combining them with cellulosic fibers are disclosed in the following US patents and patent applications: (1) "Po
Lymeic Binders for Binding Particles
Patent No. 5543215 entitled "s to Fibers"; (2) "No
n-Polymeric Organic Binders for Bind
Patent No. 553 entitled "ing Particles to Fibers"
8783; (3) "Wet-laid Fiber Sheet Manuf.
activating With Reactable Binders
Patent No. 53000192 named for binding Particles to Fibers; (4) "Method for Binding"
Particles to Fibers Using Reactivat
Patent No. 5352480 entitled "Able Binders"; (5) "
Particle Binders for High-Bulk Fiber
No. 5308896 entitled "s"; (6) Filed August 17, 1992, entitled "Particle Binders that Enhance Fi".
No. 07/931279 entitled "ber Densification";
(7) Filed on August 17, 1993, "Particle Binders"
No. 08/107469; (8) filed August 17, 1993; "Particle Binding to Fibers" No. 08/107219; (9) filed August 17, 1993 , "Bind
ers for Binding Water Soluble Partic
No. 08/107467 entitled "les to Fibers"; (10)
Patent No. 5547745 entitled "Particle Binders";
(11) Filed on August 17, 1993, "Particle Bindin"
No. 08/108218 entitled "g to Fibers"; and (12
) "Particle Binders for High-Bulk Fiber
No. 5,308,896 entitled "ers"; all are specifically incorporated herein by reference.

In addition to natural fibers, synthetic fibers including polymeric fibers such as polyolefins, polyamides, polyesters, polyvinyl alcohol, and polyvinyl acetate fibers can also be used in the absorbent composites of the present invention. Suitable polyolefin fibers include
Includes polyethylene and polypropylene fibers. Suitable polyester fibers include polyethylene terephthalate fibers. Other suitable synthetic fibers include, for example, nylon and rayon fibers. The absorbent composite material may include a combination of natural and synthetic fibers.

In a preferred embodiment, the absorbent composite material includes pulp fibers (eg, Wey).
erhaeuser name NB416) and cross-linked cellulosic fibers (eg We
The combination of the yerhaeuser name NBH 416) is included. Pulp fibers are preferably present in such combinations in an amount of about 15 to about 85% by weight.
In another preferred embodiment, the absorbent composite material comprises pulp fibers present in the composite material at about 50% by weight, and crosslinked cellulosic fibers present in the composite material at about 50% by weight, based on the total weight of the fibers. Is included.

The grooved absorbent composite of the present invention, when incorporated into an absorbent article, can serve as a storage layer for entrapped liquid. To efficiently retain the captured liquid,
The composite material includes an absorbent material.

As noted above, the absorbent material is generally throughout the composite material, and
It is located at an increased concentration in selected areas of the composite. These selected areas include streaks embedded in the composite material. The stripes are positioned across the width of the composite material and extend along the length of the composite material. The fringes of the composite material are areas of the absorbent material rich in the composite material. The fringes of absorbent material can be placed on virtually any shape, size, and location of composite material. Suitable placement of the stripes of composite material does not significantly impede liquid entrapment, i.e. promotes gel blocking,
All arrangements are included. The distribution zone of the composite material also contains some absorbent material. However, the liquid absorption capacity of the absorbent material in the fringes of the composite material is much higher than the absorbent material present in the distribution zone of the composite material.

The term “absorbent material” as used herein refers to a material that absorbs water and generally has a greater absorption capacity than the cellulosic fiber component of the composite material. Preferably, the absorbent material is a water-swellable, generally water-insoluble material, having an absorption capacity in water of at least about 5 times its weight, desirably about 20 times, and preferably about 100 times or more. . The absorbent material can swell in the dispersion medium used in the composite material forming method. In a preferred embodiment, the absorbent material is untreated,
It can swell in the dispersion medium.

The amount of absorbent material present in the composite material can vary widely depending on the intended use of the composite material. The amount of absorbent material present in the composite material incorporated into a baby diaper as an absorbent core is from about 10 to about 80% by weight, preferably from about 30 to about 50% by weight, based on the total weight of the composite material. be able to.

Absorbent materials may include natural materials such as agar, pectin and guar gum, as well as synthetic materials such as synthetic hydrogel polymers. Synthetic hydrogel polymers include, for example, carboxymethyl cellulose, alkali metal salts of polyacrylic acid, polyacrylamide, polyvinyl alcohol, ethylene maleic anhydride copolymer, polyvinyl ether, hydroxypropyl cellulose, polyvinyl morpholinone, polymers and copolymers of vinyl sulfonic acid, Included are polyacrylates, polyacrylamides, and especially polyvinyl pyridine. In a preferred embodiment, the absorbent material is a superabsorbent material. The term "superabsorbent material" as used herein refers to a polymeric material capable of absorbing large amounts of fluid by swelling and forming a hydrated gel (ie, a hydrogel).
In addition to absorbing large amounts of fluid, superabsorbent polymers are also capable of retaining large amounts of body fluids under moderate pressure.

Superabsorbent materials are generally classified into three types: starch graft copolymers,
Crosslinked carboxymethylcellulose derivatives and modified hydrophilic polyacrylates. Examples of such absorbent polymers include hydrolyzed starch-acrylonitrile graft copolymers, neutralized starch-acrylic acid graft copolymers, saponified acrylate-vinyl acetate copolymers, hydrolyzed acrylonitrile copolymers or acrylamide copolymers, modified Included are modified crosslinked polyvinyl alcohol, neutralized self-crosslinking polyacrylic acid, crosslinked polyacrylate, carboxylated cellulose, and neutralized crosslinked isobutylene-maleic anhydride copolymer.

Superabsorbent polymers are commercially available, for example Portsmouth, Vir.
It is a polyacrylate from Clariant of ginia. These superabsorbent polymers come in a variety of sizes, morphologies and absorption properties (IM3500
And available from Clariant under trade names such as IM3900). Other superabsorbent polymers are SANWET (supplied by Sanyo Kasei Co., Ltd.), and SXM77 and SR1001 (Greensboro, No.
Rth Carolina (supplied by Stockhausen)). Other superabsorbent materials include US Pat. No. 4160059; US Pat. No. 4676784; US Pat. No. 4673402; US Pat. No. 5002.
814; U.S. Pat. No. 5,057,166; U.S. Pat. No. 4,012,340; and U.S. Pat. No. 4,818,598, all of which are specifically incorporated herein by reference. Products such as diapers incorporating superabsorbent materials are described in US Pat.
99103 and U.S. Pat. No. 3,670,731.

Suitable superabsorbent materials useful in the absorbent composites of the present invention include superabsorbent particles and superabsorbent fibers. The grooved absorbent composite material of the present invention can be formed by an airlaid method known to those skilled in the pulp processing industry. A typical airlaid method is generally described in US Pat.
No. 640810 and 4065832, both of which are specifically incorporated herein by reference. Generally, airlaid fibrous webs that include absorbent materials such as superabsorbent materials are known in the art. In these webs, the absorbent material has traditionally been uniformly distributed throughout the web. Conventional airlaid webs containing absorbent materials typically suffer from gel blocking, which can limit liquid capture rate, distribution, and adversely affect absorption capacity.
Airlaid webs also tend to have poorer capture rates, absorption capacities and tensile strengths compared to wet fiber webs. Despite these constraints, airlaid composites formed in accordance with the present invention have improved liquid absorption properties, including increased absorption rates, as compared to airlaid composites that have absorbent material uniformly distributed throughout the web. Have.

The grooved absorbent composite material of the present invention is a composite material having an absorbent material concentration that varies between adjacent regions of the composite material. Variations in absorbent material concentration provide composite materials with specific liquid absorption and swelling properties.

The composite material can be formed by any method that provides a fiber composite material with varying absorbent material content. For example, a composite material is formed by varying the basis weight of a composite material (eg, a fiber composite material having a relatively uniform concentration of absorbent material) formed from a homogeneous blend of absorbent material and fibers. be able to. Alternatively, by varying the absorbent material concentration selectively within the composite material (ie, across the width of the composite material to provide absorbent material-rich stripes or regions). Can be formed.

Composite materials of varying basis weight are formed by a number of methods, including methods that affect the laydown of materials (ie, fibers and absorbent materials) during the air-lay process. can do. For example, a composite material having various basis weights, for example, a perforated support on which the composite material is formed (eg, forming wire)
It can be formed by creating zones of different porosity or breathability on top. The air flow carrying the fibers and the absorbent material is biased towards the zone of lower resistance on the support (ie the material flow is biased towards the highly porous part). Such a method creates regions of high basis weight in the composite where the flow through the support is almost unrestricted, and regions of lower basis weight where the flow is more restricted. Be done.

The support plate of the support can be shaped in a pattern that causes the forming air to exit the support area at a faster rate than other areas. Such a method also biases the laydown of the material to provide a composite material having areas of high basis weight (ie, areas with high air flow) and areas with low basis weight (ie, area with low air flow). To do.

The above method can also provide a fibrous web having a concentration gradient of absorbent material. In these methods, a pre-deposited fibrous web can be applied to a shaped air stream carrying an absorbent material. In such a method, the absorbent material applied to the deposited web is distributed throughout the web based on the airflow through the deposited web.

Alternatively, the absorbent material can be added to the fibrous web by any other method that provides for the formation of stripes or other areas rich in absorbent material in the composite.

A composite material of the present invention having various basis weights and various absorbent material concentrations is a composite material that is a relatively homogeneous blend of fibers and absorbent material (ie, a relatively uniform concentration of absorbent material). It can also be formed from a composite material having The method provides a composite material having a homogeneous blend of fibers and absorbent material, first on the porous support with the fibers and absorbent material. After deposition, the top surface of the homogeneous airlaid web is scraped (ie, removed) to provide a web with ridges and valleys. A representative homogeneous web formed by air laying fibers and absorbent material, and then ground is shown in FIG. Referring to FIG. 5, the web 20 is
Includes ridges 22 and valleys 24. After scouring, the homogeneous composite material is subsequently densified, for example to a relatively uniform thickness (ie, caliper). The densification compresses the material in the ridges of the warped web. In a preferred embodiment, the densification provides the airlaid web with a relatively uniform thickness. As a result of densification, the method provides a composite material that includes regions having an increased basis weight and regions having an increased absorbent material concentration. When densification results in a web having a relatively uniform thickness, the method provides a composite material that can be represented by composite material 10 shown in FIG. Referring again to FIG. 1, the composite material 10 includes a region 12 rich in absorbent material.
including. In accordance with the above method, region 12 has an increased absorbent material concentration compared to region 14. In addition, region 12 also has an increased basis weight as compared to region 14.

The grooved absorbent composite of the present invention can be incorporated as an absorbent core or storage layer into absorbent articles, including, for example, diapers or feminine care products. The absorbent composite material can be used alone or, as illustrated in FIGS. 6 and 7,
It can be used in combination with one or more layers. FIG. 6 shows a composite material 10
The absorbent structure 30 is illustrated by using as a storage layer in combination with the upper acquisition layer 32. As illustrated in FIG. 7, the structure 40 includes a third layer 42 (eg, a distribution layer), which may be used if desired, with the composite material 10 and the acquisition layer 32.

Alternatively, the structure 30 can be formed by placing a capture layer on the warped web and then densifying. With reference to FIG. 8, structure 50 includes warped web 20.
And a trapping layer 32. Depending on the desired amount of contact between the acquisition layer and the storage core, the acquisition layer can be formed to substantially occupy the valleys formed in the warped web. With reference to FIG. 9, structure 60 includes warped web 20 and acquisition layer 32, which substantially occupy the valleys of the web. When the structure 50 or 60 is densified, the structure 30 is obtained.

A variety of suitable structures can be made from the absorbent composite. The most common include feminine hygiene products such as diapers, feminine napkins, and absorbent consumer products such as adult incontinence products. For example, referring to FIG. 10, absorbent article 70 includes absorbent composite material 10 and has a liquid permeable topsheet 52 and a liquid impermeable backsheet 54. 11, the absorbent article 80 is
It includes an absorbent composite material 10 and an overlying acquisition layer 32. Liquid permeable surface sheet 5
2 is on the acquisition layer 32 and the liquid impermeable backsheet 54 is the absorbent composite 10
Below. These absorbent composites will provide advantageous liquid absorption performance, eg, for use in diapers. FIG. 12 illustrates an absorbent structure 90, which further includes a distribution layer 42 disposed between acquisition layer 32 and composite material 10.

A technician could use the concepts taught herein to create a variety of different structures. For example, a typical structure of an absorbent structure for adult incontinence is shown in FIG. Referring to FIG. 13, article 100 includes topsheet 52, acquisition layer 3
2, including the absorbent composite material 10 and the backsheet 54. The topsheet 22 is liquid permeable and the backsheet 24 is liquid impermeable. In this structure, a liquid permeable tissue 44 made of polar fiber material is used to absorb the absorbent composite material 10 and the acquisition layer 32.
It is positioned between and.

The present invention provides a fiber-absorbent composite material containing an absorbent material and a method of forming the same. The absorbent composite is a fibrous structure that absorbs the dispersed absorption throughout the composite and at increased concentrations in stripes that extend across the width of the composite and along the length of the composite. Including sexual material. Between the stripes of absorbent material, the absorbent composite includes fiber distribution zones that prevent gel blocking in the composite.
After the first liquid insult, the composite material produces ridges that open up the fibrous structure and increase the rate of liquid entrapment in the subsequent liquid insult. The combination of the ridges rich in absorbent material and the fiber distribution zone allows for the general use of the absorbent composite as a storage core when incorporated into an absorbent article such as a diaper.

While the preferred embodiments of the invention have been illustrated and described, it will be appreciated that various changes can be made to the invention without departing from the spirit and scope of the invention.

[0045]   The aspects of the invention that claim a proprietary property or patent are defined above.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an exemplary grooved absorbent composite formed in accordance with the present invention.

FIG. 2 is a perspective view of the composite material shown in FIG.

FIG. 3 is a cross-sectional view of an exemplary grooved absorbent composite of the present invention in a wet state.

FIG. 4 is a perspective view of the wet composite material shown in FIG.

FIG. 5 is a cross-sectional view of an exemplary composite material that includes a relatively homogeneous distribution of fibers and absorbent material.

FIG. 6 is a cross-sectional view of an absorbent structure including an exemplary grooved absorbent composite formed in accordance with the present invention.

FIG. 7 is a cross-sectional view of another absorbent structure including an exemplary grooved absorbent composite formed in accordance with the present invention.

FIG. 8 is a cross-sectional view of the composite material shown in FIG. 5 with an acquisition layer thereon.

FIG. 9 is a cross-sectional view of the composite material shown in FIG. 5 with an acquisition layer thereon.

FIG. 10 is a cross-sectional view of a portion of an absorbent article incorporating an exemplary grooved absorbent composite formed in accordance with the present invention.

FIG. 11 is a cross-sectional view of a portion of another absorbent article incorporating an exemplary grooved absorbent composite formed in accordance with the present invention.

FIG. 12 is a cross-sectional view of a portion of another absorbent article incorporating an exemplary grooved absorbent composite formed in accordance with the present invention.

FIG. 13 is a cross-sectional view of a portion of another absorbent article incorporating an exemplary grooved absorbent composite formed in accordance with the present invention.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, BZ, C A, CH, CN, CR, CU, CZ, DE, DK, DM , DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, K E, KG, KP, KR, KZ, LC, LK, LR, LS , LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, R U, SD, SE, SG, SI, SK, SL, TJ, TM , TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW

Claims (23)

[Claims] 1. An absorbent composite material comprising a first region comprising an absorbent material in a fiber matrix, wherein the first region comprises a first density and a first absorbent material concentration. And; at least one second region comprising an absorbent material in the fiber matrix,
Wherein the second region comprises a second density and a second absorbent material concentration, wherein the second density is greater than the first density and the second absorbent material concentration is second. Composite material, higher than the absorbent material concentration of. 2. The composite material of claim 1, wherein at least one second region comprises stripes along the length of the composite material. 3. The composite material of claim 1, wherein at least one second region comprises multiple stripes along the length of the composite material. 4. The composite material of claim 3, wherein the multiple stripes are substantially parallel. 5. The composite material of claim 1, wherein the at least one second region is continuous along the length of the composite material. 6. The composite material of claim 1, wherein the at least one second region is discontinuous along the length of the composite material. 7. The composite material of claim 1, wherein the composite material is an airlaid composite material. 8. The composite material of claim 1, wherein the fiber matrix comprises fluff pulp fibers. 9. The fluff pulp fibers are about 1 based on the total weight of fibers in the composite.
9. The composite material of claim 8, which is present in the composite material in an amount of 5 to about 85% by weight. 10. The composite material of claim 1, wherein the fiber matrix comprises crosslinked cellulosic fibers. 11. The crosslinked fibers comprise about 15 to about 15 weight percent based on the total weight of fibers in the composite.
11. The composite material of claim 10, present in the composite material in an amount of about 85% by weight. 12. The composite material of claim 1, wherein the absorbent material comprises a superabsorbent material. 13. The absorbent material comprises from about 10 to about 80 based on the total weight of the composite material.
13. The composite material of claim 12, which is present in the composite material in an amount of wt%. 14. A method of forming a fiber composite, the method comprising combining a cellulosic fiber and an absorbent material to provide a fiber furnish; depositing the fiber furnish on a perforated support to substantially Providing a fibrous web having a uniform thickness; removing a portion of the fibrous web to provide a web having a first region and a second region, where the first region has a first thickness And the second region has a second thickness and the first and second thicknesses are different; and a web having first and second regions having first and second thicknesses. Compressing to provide a fiber composite material having a substantially uniform thickness. 15. The method of claim 14, further comprising applying a capture material to the web having a first region and a second region prior to compressing the web. 16. A composite material formed by the method of claim 14. 17. A composite material formed by the method of claim 15. 18. A method of forming a fiber composite, the method comprising combining a cellulosic fiber and an absorbent material to provide a fiber furnish; depositing the fiber furnish on a biased perforated support. The first area and the second
Providing a fibrous web having regions of, where the first regions have a first density,
The second region has a second density and the first and second densities are different; and compressing the web to provide a fiber composite material. 19. A composite material formed by the method of claim 18. 20. An absorbent article comprising the composite material of claim 1. 21. An absorbent article comprising the composite material of claim 16. 22. An absorbent article comprising the composite material of claim 17. 23. An absorbent article comprising the composite material of claim 19.