JP2002517281A - Absorbing structure with fluid dispersion and storage layer - Google Patents

Abstract

  (57) [Summary] An absorbent structure is described that includes a liquid acquisition layer and a fibrous liquid storage layer that is fluid exchangeable with the liquid acquisition layer. The storage layer contains SAP particles. The acquisition layer includes synthetic fibers that are latex bound. A fluid acquisition layer and / or dispersion layer (ADL) comprising at least two layers, an upper layer composed of latex-bound synthetic fibers and a lower layer composed of latex and / or heat-bound cellulose fibers, and a method of preparing the same are described. The synthetic fiber layer is highly porous and exhibits rapid fluid entrapment. The cellulosic layer provides a capillary force in the z-direction that pulls the fluid to the absorbent product, provides temporary fluid fixation, and directs the fluid to be pulled to the unsaturated portion of the permanent fluid storage layer. The ADLs of the present invention provide better protection against leakage as compared to single layer ADLS.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an improved fibrous absorbent structure having separate layers for fluid capture, dispersion and storage. The acquisition layer includes latex-bound synthetic fibers and is useful in providing improved disposable absorbent articles, such as diapers, adult incontinence pads, and sanitary napkins.

[0002]

[Prior art]

Absorbents, such as disposable diapers, adult incontinence pads, sanitary napkins, and the like, are generally provided with an absorbent core, or storage layer, for receiving and retaining bodily fluids. The absorbent core is sandwiched between a liquid permeable upper sheet that has the function of allowing the fluid to pass through the core and a liquid impermeable backsheet that contains the fluid and prevents the fluid from passing through the absorber. Absorbent cores (eg, for diapers and adult incontinence pads) typically include a fiber bat or web of loose, fluff, hydrophilic cellulose fibers that have not been broken down into fibers. The core is made of superabsorbent polymer (SAP)
(superabsorbent polymer)) including particles, granules, flakes or fibers. further,
The absorber may include a dispersion layer to help transport liquid quickly from the acquisition layer to the storage layer of the core.

In recent years, the market demand for thinner and more comfortable absorbers has increased. Such articles reduce the thickness of the diamond core, increase the amount of SAP particles,
It can be obtained by reducing the amount of fiber material used in the core and calendering or compressing the core to reduce the thickness and thus increase the density. However, high density cores do not absorb liquid as quickly as low density cores. This is because densification of the core results in a smaller effective pore size. Accordingly, there is a need to provide a low density layer having a larger pore size than the high density absorbent core in order to increase the rate of uptake of liquid released into the absorber to maintain an adequate liquid absorption rate. The low density layer is commonly referred to as an acquisition layer.

[0004] The storage layer portion of a disposable diamond core, for example, is generally formed from loose, fluff, cellulose, in place in a processing step. The superabsorbent powder is blended with the fluff cellulose fibers when the absorbent core is formed in a diaper processing line. Such cellulosic materials are generally not available in pre-formed (preformed) roll form because they exhibit insufficient web strength due to lack of interfiber bonding or entanglement.

[0005] The acquisition layer of disposable diapers is generally a thermally bonded, latex bonded or point bonded, carded synthetic tress fiber web. Typically, the tress fibers of the acquisition layer are curled (crimped) polyester (PET) or polypropylene fibers having a length of at least 40 mm and a size of 6 to 15 denier. The acquisition layer is formed as a homogeneous rolled good on a non-woven textile manufacturing line, bonded and cut. The slit roll of acquisition layer material is then deployed on a diaper processing line that is secured above the absorbent core and below the topsheet. An example of a commercial infant dialer with bonded, carded, bunched fibers is Huggies Diapers manufactured by Kimberly-Clark Corp. (Dallas, TX) and Paragon Trade Brands (Atlanta, GA) Is a private label diaper manufactured from.

[0006] Modern infant disposable diaper processing machines are known as elastations.
Many features, such as ication), and numerous nonwovens have become extremely complex as they have been implemented to improve the performance of the diaper. This complexity has created significant raw material handling problems and the resulting loss of processing line productivity. Thick and cumbersome fluff pulp and superabsorbent powder forming systems need to be replaced with a single material that can be sent directly from a roll or other suitable compact package to the processing line. Since the acquisition layer and the absorbent core are co-located in the final product, matching the fluid acquisition layer and the absorbent core to one material allows the efficiency of the processing operation to be maximized.

[0007] Ultra-thin women's napkins are generally manufactured from nonwoven materials based on rollgoods. Such rolls of preformed absorbent core material are directly unwound in the absorbent processing equipment without the de-fibrillation step required for fluff-based products such as diapers and incontinence pads. Nonwoven webs are usually bonded or consolidated in such a way as to provide sufficient strength to be handled in the processing. The web may include SAP particles.

[0008] The web consolidation mechanisms used in the roll-good approach to make preformed cores impart strength and dimensional stability to the web. Such mechanisms include latex bonding, thermoplastic or biocomponent fibers or thermoplastic powders, hydrogen bonding, needle punching, carding, and the like.

[0009] Capture and dispersion layers ("ADL") typically found in die-cut feminine hygiene pads
) Is an airlaid cellulose web bonded with a dried and cured aqueous binder resin. Airlaid materials typically maintain up to 16 g of fluid per gram of material against gravity under negligible loading. Thus, the ADL is capable of absorbing fluid waves within the absorbent product and ultimately in storage containing the superabsorbent particles until the superabsorbent particles of the absorbent core are able to absorb the fluid maintained outside the airlaid cellulose ADL. Can be captured.

An example of a common airlaid cellulose material is Vicell 6002 (Buckeye Technologies
Inc., Memphis TN), which is a 105 gsm (gram per square meter) airlaid cellulose nonwoven laminated with a vinyl acetate binder resin. Vicell 6002 is prepared by spraying an aqueous emulsion of a vinyl acetate binder resin onto an airlaid cellulose web, followed by drying and curing in a hot air oven. It is used commercially in ADLs for feminine hygiene pads.

A disadvantage of some commercially available airlaid cellulose structures is that they can collapse under normal use. This usually occurs when the structure is pressed with the weight of the user, especially when the structure is wet. This structural collapse significantly reduces the fluid capture rate of the absorbent product, thus increasing the chance of leakage. If the fluid-saturated airlaid cellulose structure collapses completely or partially, fluid escapes from the ADL,
The product gives a wet feeling to the user's skin.

A thin absorbent core material that facilitates liquid transport from the capture area to the storage area, has high absorbency in use, and can be transported in a roll-good form that simplifies manufacturing and processing steps Is needed.

[0013]

[Problems to be solved by the invention]

Applicants have surprisingly found an improved ADL comprising at least two separate layers, an upper layer and a lower layer, which overcomes the shortcomings of the above commercially available products. The upper layer of the ADL of the present invention (ie, the layer in contact with the user's skin) is highly porous, thus preventing structural collapse and minimizing leakage problems.

[0014]

[Means for Solving the Problems]

The present invention provides a highly absorbent, high bulk, low density object having an absorbent structure comprising a liquid acquisition layer and, optionally, a dispersion layer and a fibrous liquid storage layer associated with the acquisition layer. The storage layer comprises SAP particles, latex binding fibers, heat binding fibers, or a combination thereof.

In one embodiment, the present invention provides an improved acquisition and dispersion layer having at least two layers that can be used in a disposable absorbent product, ie, an upper layer that contacts the user of the absorber (an acquisition layer); A lower layer (dispersion layer) between the upper layer and the storage layer. According to one aspect of the present invention, there is provided an improved ADL having a highly porous capture layer.

In another aspect of the invention, an air-rolled good comprising an ADL of the invention is provided.
laid rolled good) and a method of manufacturing the same.

In yet another aspect of the present invention, there is provided a disposable absorbent product comprising the ADL of the present invention, and a method of making the same.

The absorbing structure of the present invention has the following advantages. That is, (i) it is made of a low density material and has high bulk properties, so it is highly absorbent; (ii) superabsorbent particles are deposited in the layer to provide an absorbent web, thus providing increased absorbent power (Iii) the functionality of the multiple materials can be made more economical to provide an absorber because it is incorporated into a single roll; (iv) the acquisition layer formation step The wettability of the product can be controlled by the addition of a surfactant therein.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

All patents, patent applications and publications cited herein are hereby incorporated by reference in their entirety.

The present invention provides an improved fibrous absorbent structure that includes a low density liquid acquisition layer and a relatively high density fibrous storage layer. The structure is a composite that includes at least these two layers that give the structure the ability to capture and disperse fluid through a density gradient. The capture layer can rapidly capture liquid from the insult. The storage layer is
Absorb and store the liquid obtained from the acquisition layer.

Further, the present invention preferably comprises a dispersion layer, which provides an improved ADL in combination with a fluid acquisition layer, which comprises at least two layers, an upper acquisition layer and a dispersion layer. When used in a disposable absorbent, the acquisition layer is close to the user's skin and away from the storage layer; the dispersion layer is close to the storage layer and away from the user's skin. The acquisition layer provides for rapid fluid acquisition. The dispersing layer separates from the user's skin,
Applying a capillary force in the z-direction to pull the fluid to the absorption storage layer, temporarily fixing the fluid,
It acts as a conduit for fluid drawn into the unsaturated sites of the reservoir. The absorbent structure of the present invention has a high absorbency, especially for diapers, adult incontinence pads and briefs,
It can also be used as an absorbent core for disposable absorbent products such as sanitary napkins.

The fluff cellulose fibers decomposed into fibers used in the storage layer or ADL of the composite structure of the present invention may be made of wood cellulose such as Foley fluff, cotton linter pulp, crosslinked cellulose fiber or high purity cellulose fiber such as cellulose fiber. Modified cellulose can be selected from, for example, Buckeye HPF.

The present invention provides a latex-bound, synthetic fiber in the acquisition layer that has improved acquisition and retention properties (ie, improved retention and retention properties, as compared to an absorbent structure using an acquisition layer that lacks such fibers.
(Absorptivity). An advantage of utilizing synthetic fibers is that such fibers maximize surface drying of the absorbent product. Use synthetic fibers, including polyester fibers such as polyethylene terephthalate (PET), polypropylene, nylon and acrylic, and combinations thereof, if the layer has the property of forming large pores to resist collapse when wetted. be able to.

[0024] The melting point of the synthetic fibers should be taken into account during the manufacturing process and the temperature should be adjusted to avoid melting of the fibers. For the purposes of this disclosure, "large pores" means pores that are larger than the pores formed by the cellulose fibers and are more resistant to collapse. Because the large pores contained within the synthetic fiber matrix are resistant to collapse under wet pressure, the top layer captures fluid waves rapidly as the fluid passes through the liner or topsheet of the absorbent product. be able to. The size of the hole is
It depends on fiber composition, fiber size (ie fiber diameter), fiber elasticity and latex elasticity. Those skilled in the art will have ordinary knowledge in the art (for example,
(See Cohen U.S. Patent Nos. 5,569,226 and 5,505,719) and mechanical experiments can be used to optimize the pore size to meet specific requirements.

The upper synthetic fiber is combined with an aqueous dispersion (emulsion) of a natural or synthetic polymer latex. Any latex may be used in the present invention. The synthetic polymer may be, for example, an alkyl acrylate, vinyl acetate, or styrene-butadiene polymer or copolymer. Other polymers known in the art may be used. For the purpose of industrial hygiene and drainage of the solvent recycling process, the synthetic latex is applied as an aqueous-based emulsion rather than an organic solvent emulsion. In the present invention, the preferred matrix fibers of the acquisition layer are 3 to 20 denier crimped PET fibers having a cut length of 3 to 15 mm.

The dispersed layer of the improved ADL preferably comprises latex and / or thermally bound cellulose fibers. Wood fibers such as any fluff cellulose fibers, preferably airlaid fluff cellulose, chemically modified cellulose fibers (eg, cross-linked cellulose fibers), high-purity cellulose, cotton linter fibers, or mixtures thereof, are added to this layer. Can be used. For bonding purposes, a latex dispersion used to bond the upper layer fibers may be used. Alternatively or in combination with a latex binder, a thermoplastic fiber or powder may be used to heat and bond to the melting point of the thermoplastic fiber or powder. Bicomponent fibers having a PET core surrounded by a polyethylene sheath, such as Hoec
hst-Trevira Type-255 (Charlotte, NC) and polyethylene powder can be used.

The improved dispersion layer of ADL provides both a temporary holding area and a liquid distribution channel to the final storage layer. The cellulose fibers in this layer form micropores that spontaneously disperse the fluid from the point of fluid insult to the unsaturated portion of the dispersion layer through a combination of surface tension propulsion and gravity. When fluid diffused from the insult contacts the unsaturated portion of the storage layer having a higher surface tension than ADL, fluid in the dispersed phase flows to the storage layer until surface tension equilibrium is reached. Higher surface tension of the storage layer can be produced by providing a higher density of cellulosic fibers and / or superabsorbent particles. Thus, the distribution layer becomes both a fluid reservoir and a fluid channel for the storage layer. Fluid channel function is particularly important in some thin absorbent pads where the ADL covers a significantly larger surface area than the absorbent core or storage layer.

[0028] Optionally, other components such as surfactants, pigments and opacifiers may be added to the acquisition or dispersion layer without affecting absorbency.

The ADL of the present invention has a basis weight of about 30 to 150 gsm, preferably about 60 to 100 gsm, and most preferably about 80 gsm. In some embodiments, A
Each basis weight of the DL capture and dispersion layer can range from about 15 to 60 gsm. Preferably, the basis weight of each layer is at least about 25% of the total ADL basis weight. In some embodiments, the top layer is about 25-50% of the total ADL basis weight.

The ADL of the present invention may include an optional intermediate layer. The intermediate layer comprises 100% fluff cellulose and / or chemically modified cellulose fibers and can also have a composite fiber composition of synthetic fibers and cellulose fibers.

In one embodiment of the ADL, the acquisition layer is made up of 6 mm cut length polyester (PET) fibers combined with 10-20% by weight aqueous binder resin.
. About 80-90% by weight of 7 dtex (weight / fiber length). The lower layer is 10-2
It contains 80-90% fiber-degraded fluff cellulose fibers bound with 0% aqueous binder. The fluff cellulose fibers decomposed into fibers are made from wood cellulose such as Buckeye Foley fluff (Buckeye Technologies Inc.), Buckeye HPF (Buckeye HPF).
eye Technologies Inc.), or chemically modified cellulose such as cross-linked cellulose fibers. In another embodiment, the upper and lower layers of ADL are as described above, but there may be an intermediate layer comprising a composite of PET and cellulose fibers. In this embodiment, the upper layer is at least 10% of the total ADL weight and the lower layer is less than 50% of the total ADL basis weight.

A preferred overall basis weight range of the composite absorbent structure of the present invention is 100-500 grams per square meter (gsm). The composite absorbent structure includes a fluid acquisition layer and a fluid distribution layer (described above) and a fluid storage layer. The fluid storage layer is below the fluid dispersion layer and consists of fluff cellulose or chemically modified fluff cellulose matrix fibers, superabsorbent polymer (SAP) and binding elements. The bonding element is preferably a bicomponent fiber at a concentration of 5 to 20%, but may also comprise a thermoplastic powder. Preferably, the SAP pigment is 10-70% by weight of the absorbing structure.

As used herein, “superabsorbent polymer” or “SAP” means a suitable hydrophilic polymer that is mixed with the fibers of the present invention. Superabsorbent polymers are water-soluble compounds that are crosslinked and rendered water-insoluble, but are capable of swelling in saline at least about 15 times their weight. These superabsorbent materials generally fall into three classes: starch graft copolymers, crosslinked carboxymethylcellulose derivatives, and modified hydrophilic polyacrylates. Examples of absorbent polymers include hydrolyzed starch-acrylonitrile graft copolymer, saponified acrylate-vinyl copolymer, modified crosslinked polyvinyl alcohol, neutralized crosslinked polyacrylic acid, crosslinked polyacrylate and carboxylated cellulose. Including. Preferred superabsorbent materials absorb fluid to form a hydrogel.

Superabsorbent polymeric materials have a relatively high gel volume and relatively high gel strength, as measured by the shear modulus of the hydrogel. Such preferred materials include relatively low levels of polymeric materials that are extracted in contact with synthetic urine. Superabsorbent polymers are well known and are commercially available. One example is IM1000 (Hoechst-Celanese, P
ortsmouth, VA) is a starch grafted polyacrylate hydrogel commercially available. Other commercially available superabsorbent polymers are trademarks of Sanwet (San
yo Kasei Kogyo Kabushiki, Japan), Sumika Gel (Sumitomo Kagaku Kabushiki H
aishi, Japan), Favor (Stockhausen, Garyville, LA) and ASAP series (Chemda
1, Aberdeen, MS). Superabsorbent particle polymers are disclosed in US Pat.
No. 340 and Re32649. An example of a suitable SAP is
Powder based on surface crosslinked acrylic acid, such as Stockhausen 9350 or SX FAM70 (Greensboro, NC).

The preferred basis weight range and SAP content may vary with the intended application. For women's hygiene and light volume adult incontinence applications, for example, basis weight and SA
The P content is at the lower end of the range described in Table 1. For infant diapers and heavy volume adult incontinence applications, the preferred basis weight and SAP content are at the higher end of the range specified in Table 1.

While multi-matrix fibers are used in the absorbent of the present invention, it is preferred that the matrix fibers collectively make up most of the fibers of the material (eg, at least 75%). The term matrix fiber as used herein refers to a synthetic or cellulosic fiber that does not melt or dissolve during the formation or bonding of the airlaid absorbent structure.
The term "thermal bonding" or "heat" is used herein to refer to a blend of thermoplastic materials such that the matrix fibers and SAP bond to the absorbent layer when heat is applied (eg, the bonding method described in Table 1). ).

[0037] Examples of suitable thermoplastic materials include thermoplastic microfibers, thermoplastic powders, bonding fibers in fiber form, and bicomponent fibers. Bicomponent fibers are characterized by a high melting point core polymer (typically polyethylene terephthalate (PET) or polypropylene) surrounded by a low melting point sheath polymer (typically polyethylene, modified polyethylene or copolyester). In a preferred embodiment of the invention, the bicomponent fibers provide a means for thermal bonding.

Table 1 provides a general outline of an embodiment of the present invention.

[Table 1]

In one embodiment of the feminine hygiene and light adult incontinence product, the absorbent product of the present invention comprises an acquisition layer, a dispersion layer and a storage layer having a total basis weight of 120 gsm to 290 gsm. The acquisition layer comprising latex-bound PET matrix fibers comprises 20
It has a total basis weight of な い し 60 gsm. The matrix fibers are 6 to 15 denier in size, 3 to 12 mm in length, and have 2 to 5 crimps (c
rimps) / cm. Latex is ethylene vinyl acetate, styrene-
Butadiene or acrylic polymer. The latex binder is about 5 to 25% by weight of the acquisition layer. The dispersion layer comprising thermally bonded fluff cellulose or chemically modified fluff cellulose fibers has a total basis weight of 30 to 90 gsm. Cellulose fibers are thermally bonded to 5-20% by weight sheath / core bicomponent fibers (eg, 3 denier T-255 bicomponent fibers from Hoechst-Celanese, Charlotte, NC). A storage layer of heat-bonded fluff cellulose having 20 to 50% SAP has a total basis weight of 70 to 130 gsm. The fluff cellulose / SAP mixture is thermally bonded with 5-10% by weight of the sheath / core bicomponent fibers. Specific embodiments are described in Examples 3, 9, 14, 15, 16.

In another embodiment used in infant diapers and heavy adult incontinence products, the acquisition, dispersion and storage layers have a total basis weight of 300 gsm to 500 gsm. The acquisition layer containing latex-bound PET matrix fibers may be 20 to 6
It has a total weight of 0 gsm. The matrix fibers are 6 to 15 denier in size, 3 to 12 mm long and have a 2 to 5 shrinkage / cm. The latex is an emulsion of ethylene vinyl acetate, styrene butadiene or an acrylic polymer, and is about 5 to 25% by weight of the acquisition layer. The dispersing layer contains thermally bonded fluff cellulose or chemically modified fluff cellulose fibers, and has a thickness of 30 to 100%.
gsm has a total basis weight. Cellulose fibers are thermally bonded with 5 to 20% by weight sheath / core bicomponent fibers. The storage layer of thermally bonded fluff cellulose with 40-75% SAP has a total basis weight of 250-340 gsm. The fluff cellulose / SAP mixture is thermally bonded with 5-10% by weight of the sheath / core bicomponent fibers. Specific embodiments are described in Examples 8 and 10.

The absorber of the present invention can be obtained from M & J Fibertech (Horsens, Denmark) or Dan-Web (Aarhus,
It can be prepared in a series of ways utilizing air forming equipment such as those commercially available from Denmark). An underlayer or cellulosic fiber layer is formed on the moving collection wire and a synthetic fiber layer is airlaid directly on the cellulosic fiber layer. The resulting composite structure is then sent to a deposition application station, usually a set of spray nozzles or a foam coater, which applies the adhesive directly to the synthetic fiber layer. This is passed through a hot air oven or other suitable heating device to join the structures. In a preferred embodiment, the deposit is applied to the cellulosic fiber side of the composite structure and the object is passed through a second oven to dry the deposit. A third heating station may be provided to ensure that the deposit is completely cured. The absorption structure of the present invention is a roll good foam (rol)
It may be completely contained and stored in l-goods form).

[0042] Preferably, the absorbent structures of the present invention are prepared as an airlaid web. The composite material is a series of operations if the production line has at least three separate forming heads, a synthetic fiber dosing system capable of simultaneously handling at least two different synthetic fibers, a superabsorbent powder dosing system and a latex deposition application system. Can be manufactured.

Airlaid webs are prepared by disintegrating or disintegrating the cellulose pulp sheet or sheet into fibers, usually by a hammer mill, to provide individualized fibers. The individualized fibers are pneumatically conveyed to a forming head on an airlaid web forming machine. The forming head includes a rotating or agitating drum in a race track configuration that maintains fiber separation on a stoma concentrating drum or stoma forming conveyor (or forming wire) until the fibers are drawn by vacuum. In M & J equipment, the forming head includes a rotary mixer above the screen. Other fibers, such as synthetic thermoplastic fibers, may be introduced into the forming head through a fiber dosing system including a fiber opener, a dosing unit and an air conditioner. If two distinct layers are desired, for example a fluff pulp dispersion layer and a synthetic fiber acquisition layer, two separate forming heads are provided, one for each type of fiber.

The airlaid web is transferred from the forming wire to a calender or other compression stage to compress the web, increase strength, and adjust the thickness of the web. The fibers of the web are bonded by application of a latex spray or foam application system, followed by drying or curing. Alternatively or additionally, the thermoplastic fibers present in the web may be softened or partially melted by applying heat to bind the fibers of the web. The bonded web may be calendered twice to reinforce or decorate the web with the design or pattern. If thermoplastic fibers are present, thermal calendering may be used to impart a patterned bond to the web. Water may be added to the web as needed to maintain a specific or desired moisture content, minimize dusting, or reduce static buildup. The finished web is
Rolled for future use.

In one embodiment (eg, Example 1), the acquisition and distribution layers are air-formed independently of the fluid storage layer. The composite acquisition / dispersion layer is combined with the storage layer at the processing line. This embodiment can be used for absorbent product designs where the storage layer covers a different area than the acquisition / dispersion layer. Another embodiment of this type is described in Examples 11, 12 and 13.

The following non-limiting examples further describe the present invention, the scope of which is limited only by the claims.

[0047]

【Example】

Example 1-2 To test the rate of fluid capture using the ADLs of the present invention, a sample having a target basis weight of 80 gsm was formed on a laboratory airforming device. The upper layer of Example 1 was made of 34 gsm of 6.7 dtex, 6 mm long polyester (PET) fiber (
Hoechst Trevira, Charlotte, NC) and 6 gsm of AirFlex 192 latex binder (Air Products and Chemicals, Allentown, PA). The lower layer is 34
gsm Buckeye Foley fluff pulp and 6 gsm AirFlex 192 latex binder. A control sample, Example 2, was prepared on the same laboratory air forming apparatus and contained 68 gsm of Buckeye Foley fluffy wood cellulose fiber and 12 gm.
Includes a monolayer having a basis weight of 80 gsm, including AirFlex 192. Foley fluff cellulose typically consists of fibers used in conventional airlaid capture layers, such as Vicell 6002 (Buckeye Technologies Inc.).

Each sample was placed on a duplicate Zorbcore 5901 (Buckeye Technologies Inc.). It contains 250 gsm of thermally bonded air-laid Foley fluff material containing 25% Stockhausen SX FAM 70 SAP. The ADL / absorbent core stack was covered with an 18 gsm polypropylene topsheet. Three separate test and control samples for measurement, each sample having an area of 25 cm × 10 cm, were prepared. Each sample was wrapped with the appropriate coverstock material and placed on a bottom fluid uptake test ("FIT") board with the wire or carrier side facing down. The center of the sample was marked.

[0049] Capture rate evaluation was performed by subjecting the test samples to three consecutive 50 ml insults of 0.9% saline. The first 50 ml of 0.9% saline insult was poured into the clear addition tube of the FIT board as soon as possible without overflow. The time from the moment of injection until the saline reached the test sample was measured. The stopwatch was stopped as soon as all of the saline had passed through the bottom end of the tube. The time recorded was the time required for capture by the upper layer. 1
At intervals of minutes, the method was repeated with a second and third 50 ml insult.

The capture rate from each fluid insult was determined according to the following equation: Capture speed (ml / s) = [amount of fluid insult (ml)] / [capture time (s)]

The result of the capture rate is the milliliter per second (m) of fluid penetration through the top sheet.
1 / s) in Table 2.

[Table 2]

The results show that the sample with two layers of latex-bound PET / Foley fluff (
In other words, ADL prepared according to the present invention) and all three insults have about twice the fluid capture rate as compared to a control sample consisting of one layer lacking PET.

Another important function of the ADL is to separate the user of the absorbent product from the fluid contained within the absorbent product. While low density airlaid cellulose layers may have very fast fluid entrapment, conventional airlaid ADL cellulosic fibers often maintain fluid or leave the core out of the core when the ADL is under pressure. It provided a conduit for fluid to leak, thus wetting the user's skin. In contrast, Book A
The synthetic fibers in the upper layer of the DL form large pores, so that even under pressure, the upper layer does not retain fluid or form a conduit through which fluid leaks from the dispersing or storage layer to the user. This advantage has been demonstrated experimentally in this experiment.

The test sample described in Example 1 was placed on a double Zorbcore 5901 and under an 18 gsm nonwoven topsheet. The material of this stack is 0.9% saline that can be absorbed through the topsheet by a stack of filter papers under 0.1 psi pressure after each fluid insult, according to the rewet / fluid retention test described above. Tested by measuring the amount of water. 3
Test and control samples for two separate measurements (each 8
1/2 "x11") was prepared. Each sample was placed on a plastic platform, tissue side down, with its center marked. 50 ml of 0.
9% saline (first insult) was drained into the sample from the funnel from a distance of about 1.5 "above the center of the sample. The sample was left for 20 minutes. The stack of 12 filter papers was weighed, Placed in the center of the wet area and compressed by a circular weight placed on top.After 2 minutes, remove the wet filter paper,
Weighed again. The method was repeated with a second 50 ml saline insult and a stack of 16 filter papers, and with a third 50 ml saline insult and a stack of 20 filter papers. Rewet values and percent fluid retention were calculated for the first, second and third insults according to the following formula: Rewet _{1, 2 or 3} = wet filter paper weight-dry filter paper weight% hold = (50-rewet) 50 x 100%

The results are shown in Table 3 as the percentage of each 50 ml fluid insult retained by the core after the filter paper had been removed.

[Table 3]

The latex-bound PET / Foley fluff cellulose bilayer (ie, ADL prepared according to the present invention) has a significantly higher fluid retention than the sample containing only latex-bound fluff cellulose.

Examples 3-4 To test the absorbent cores of the present invention in a combination (Example 3), composite absorbent cores were placed on top of previously prepared Vizorb X479 material (Buckeye Technologies Inc.) for 10 minutes.
A layer of 0% 6 denier x 6 mm long PET fiber was prepared by first air forming. The PET fiber layer was then bonded by spraying a 15% by weight aqueous solution of AirFlex 192 latex binder (Air Products & Chemicals, Allentown, PA.). Vizorb X479 is a 30% SAP (Stockhausen S
X FAM 70; Greensboro, NC) latex / heat binding absorbent core fluff cellulose. Vizorb X479 also has an SAP-free top layer containing thermally bonded Buckeye HDF chemically modified fluff cellulose that becomes a fluid dispersion layer when a latex binding capture layer is formed over the X479 material. A 15 gsm cellulose tissue carrier sheet was provided below the bottom surface of Vizorb X479 material for SAP encapsulation during the web forming process to prevent fouling of the device by SAP separation from this structure.
The target composition and configuration of the absorption structure of Example 3 is shown in Table 4. This preparation was repeated using a composite absorbent core formed from 100% 6 den x 12 mm PET fibers.

The fluff cellulose fibers of the dispersing and storage layer consist of 67% by weight of Buckeye Foley Fluf
f and 33% by weight Weyerhaeuser PD 416 (Seattle, WA). The bicomponent fibers used were 3.1 dtex x 4 mm long Hoechst-Trevira T-255 (Charlo
tte, NC), the SAP powder was Stockhausen SX-70 (Greensboro, NC), and the latex binder resin was AirFlex 124 (Air Products). The term “dtex”
Refers to the amount in grams of 10,000 meters of fiber. The term "denier" refers to the amount of 9000 meters of fiber in grams.

The acquisition layer matrix fiber of Example 3a was a Hoechst-Trevira Type-224 crimped 6.7d with 6 mm long polyester (polyethylene terephthalate or PET).
tex and AirFlex 192 latex resin. Example 3b is PET
It was the same as 3a except that the fiber length was 12 mm. The binder of the fluff cellulose trapping layer is AirFlex 192 and the fluff cellulose is 100% Buckeye F
oley fluff.

[0060]

[Table 4]

A reference sample (Example 4) was prepared by air forming a 40 gsm layer of Foley fluff cellulose onto Vizorb X479 material. The reference sample is P
A conventional air forming structure lacking ET fibers is illustrated. Table 5 shows the target composition and composition of the reference sample.

[0062]

[Table 5]

[0063] Three separate test and control samples were further prepared as in Example 1. The capture rate evaluation was performed using 3 as described in Example 1-2.
This was done by treating the composite structure of Examples 3a, 3b and 4 by treating the sample in two consecutive insults.

The results of the capture rate are shown in Table 6 as milliliters per second of fluid penetration through the topsheet.

[Table 6]

Table 6 shows that the sample with the latex-bound PET capture layer has a 300-400 percent greater fluid capture rate than the sample with the latex-bound fluff cellulose capture layer.

The structures of Examples 3a, 3b and 4 were also subjected to the same liquid rewetting / retention test using the same 50 ml saline insults as in Example 1-2. Rewet values and percent liquid retention were calculated for the first, second and third insults according to the rewet equation of Example 2. The results are shown in Table 7, which shows the amount of liquid drawn in grams through the topsheet using filter paper.

[Table 7]

Table 8 shows that each 50 m retained by the core after the filter paper was removed
9 shows the results of Table 7 expressed as a percentage of 1 liquid insult.

[Table 8]

Tables 7 and 8 show that the latex-bound PET capture layer provides significantly better fluid retention than the conventional latex-bound fluff cellulose capture layer.

Examples 5-8 In this embodiment of the present invention, layers of 6den x 6 mm PET matrix fibers were bonded using a combination of latex bonding and thermal bonding (ie, two types of bonding techniques). Combination of multiple bonds). The first step is to form an airlaid absorbent core called DL-1. The basis weight of the DL-1 material is 425.0 gsm
Met. The DL-1 material comprises a dispersion layer containing predominantly airlaid Buckeye HPF and 1
5 gsm tissue carrier SAP / fluffy cellulose fluid storage layer (chemically purified cellulose fibers with a small percentage of bicomponent fibers). The DL-1 storage layer comprises 144.9 gsm of fluff pulp and 153 gsm.
Stockhausen 9350 SAP included. The dispersion layer of DL-1 material is 48.6 gsm
Contains Buckeye HPF fiber. In addition, 46.6 gsm of bicomponent thermal fiber was dispersed through the core and dispersion layer of the DL-1 material. The dispersion layer and the storage (core) layer were thermally bonded using a small amount of latex (17 gsm solids) sprayed into a dilute aqueous solution such that the layer contained SAP particles and cellulose fibers.

The DL-1 material 5 was collected on a roll and a portion of the roll was returned through an M & J web forming and bonding system (Horsens, Denmark). The capture layer is DL-1
Air-foamed on top of the dispersed layer of material. For each sample, the acquisition layer was applied by blending the matrix and bicomponent fibers and air-forming the layer in DL-1 material (see Table 9). Matrix Fiber Buck
eye HPF and Buckeye HPZU are chemically purified cellulose fibers. The bicomponent fiber was T255 fiber (Hoechst-Trivera). The latex was AirFlex 192 (Air Products).

[Table 9]

A liquid capture rate test was performed on the airlaid and multiple bond structures shown in Table 9 according to the method described in Example 1. The results are set forth in Table 10.

[Table 10]

The fluid capture rate of the sample material of Example 8, including a capture layer of latex bound polyester (PET) fibers, showed the highest fluid capture rate.

The airlaid, multiple bond structures of Examples 5-8 were subjected to a liquid retention test according to the method of Example 2. The results are set forth in Table 11.

[Table 11]

Table 11 shows that the sample volume of Example 8 including the PET fiber capture layer was higher in the composite structure than in the other structures employing the cellulose based capture layer (Examples 5-7). It shows that it has a significantly higher percentage of fluid retained below.

Examples 9-10 Examples 9 and 10 are thin sanitary pads and a light adult incontinence application (Example 9), and an infant diaper / training pants application (Example 10).
3 is a specific embodiment of the three-layer invention optimized for:

Example 9 Samples were prepared on an M & J type air forming line using the configurations and target compositions listed in Table 12. The storage layer is Foley fluff cellulose (Buckeye
Technologies Inc.) and the dispersion layer is made of HPF fluff cellulose (Buckeye Te
chnologies Inc.). The used binding fiber is T-255 3den x 4m
m (Hoechst-Trevira). The synthetic matrix fiber used was Type D264
It was a PET fiber (Hoechst-Trevira) with a shrinkage (4.2 cr / cm) of 56 den x 6 mm. The SAP used was a Stockhausen type 9350. The sample material is used to prevent air forming equipment from being contaminated with superabsorbent powder particles.
Formed on an 18 gsm tissue sheet. This three-layer structure + carrier structure is thermally bonded, has an overall material density of 0.094 g / cc and a basis weight of 219 gs.
m. The resulting ADL / core absorbent material is one embodiment of the present invention that can be used for thin hygiene pads and light adult incontinence applications.

[Table 12]

According to the method of Examples 1 and 2, except that the volume of each fluid insult was 10 ml, for two commercially available (N. American and European brand A) thin sanitary pads: This sample was tested for both fluid capture and retention. The results are shown in Table 13. Basis weight is the sum of the multiple absorbent components that make up the fluid acquisition, dispersion and storage layers of the product.

[Table 13]

Example 10 A sample was prepared according to Table 14 and the fluff cellulose in the storage layer was ND-416 (Weye
rhaeuser, Tacoma, WA) and the dispersed layer fluff cellulose is Foley fluff (Buckeye T
echnologies Inc.), except that it was manufactured in the same manner as the sample of Example 9.
The overall material density was 0.117 g / cc and the basis weight was 504 gsm.

[Table 14]

In accordance with the methods of Examples 1 and 2, Sample 1 was tested for both fluid capture and retention as compared to two commercially available infant diapers and training pants. The results are shown in Table 15. The basis weight of the capture, dispersion and storage components of the commercial product were as follows: A, 622 gsm; B, 792 g
sm; C, 522 gsm; and D, 840 gsm.

[Table 15]

Examples 11-13 These examples demonstrate that the present invention relates to the formation of the A of the present invention in a preformed and bonded absorbent core.
Figure 16 shows three embodiments of DL (see Table 16). These embodiments include 6 to 1
Compare the effect of matrix fiber size over a range of 5 denier. Example 1
The three dispersion layers have a combination of latex and thermal bonding.

Example 11 Two-layer ADL was prepared according to Table 16 using Foley fluff cellulose (Buckeye Tec)
hnologies Inc.), T255 3den x 4mm binding fiber (Hoechst-Trevira), Ai
rFlex 192 latex binder (Air Products), D2645 PET 6den x 6mm x 4.
Formed as in Example 1 using 2cr / cm synthetic matrix fiber (Trevira),
An 18 gsm wet laid tissue product was formed.

Example 12 In this example, the synthetic matrix fiber utilized for the acquisition layer was Trevira D2670
ADL was formed in the same manner as in Example 11, except that the PET synthetic matrix fiber (9den x 6 mm x 3.9 cr / in) was used.

Example 13 In this example, the synthetic matrix fibers utilized in the acquisition layer were Trevira D2660
An ADL was formed in the same manner as in Example 11, except that the PET synthetic matrix fiber (15 den x 6 mm x 3.2 cr / in) was used.

The samples of Examples 11-13 were prepared using Buckeye Airlaid grade 5901 core (Buc
keye Technologies Inc.) and examined for fluid capture rate and fluid retention according to the methods of Examples 1 and 2. 5901 material is 25% Stockhausen SX
A thermally bonded, homogeneously blended material containing FAM 77 superabsorbent powder, 10% Trevira T-255 bicomponent fibers, 6% tissue carrier sheet, and 59% Weyerhaeuser Super Soft Ultra fluff cellulose. .

The results in Table 17 show that the 9denPET fiber used in Example 12 provided the maximum fluid uptake rate; fluid retention was not significantly affected by the choice of matrix fiber in these examples.

[Table 16]

[Table 17]

Examples 14-16 These examples compare the various latex bonders used in the acquisition layer. In Examples 14-16, the latex-bound PET capture layer was Vizorb X4
79 was formed on an absorbent core (Buckeye Technologies Inc.) (see Example 3). The composition of the absorption sample is described in Table 18.

Example 14 The fluff cellulose used in the dispersion and storage layers was HPF and Foley fluff (Buckeye Technologies Inc.), respectively. The binding fiber is T-255
It was 3 den x 4 mm (Hoechst-Trevira). Latex binder is AirFlex
192 (Air Products). The synthetic matrix fibers were Type D2645 PET 6 denier x 6 mm x 4.2 cr / cm (Trevira, Inc., Germany). The sample was formed into an 18 gsm wet laid tissue.

[Table 18]

Example 15 A second sample was prepared containing GenFlo 3060 styrene-butadiene copolymer as a latex bonder (GenCorp Specialty Polymers, Akron, OH).

Example 16 A third sample containing a GenFlo 9355 styrene-butadiene-acrylic terpolymer as a latex binder was prepared (GenCorp Specialty Polymers, Akron,
OH). Two percent of the Aerosol OT 75 surfactant obtained from Van Waters & Rodgers, Memphis, TN was added to the aqueous latex bonder solution to render the acquisition layer hydrophilic.

The samples were tested for fluid capture rate and fluid retention at 0.9% saline according to the methods of Examples 1 and 2, except that the volume of each fluid insult was 10 ml.

[Table 19]

[0091] Two additional variants were made from the third sample. The first deformation is 1%
The second variant contains the Aerosol OT surfactant and no surfactant is added to the latex bonder emulsion. The sample (2.5 square inches) was placed on a horizontal surface. 5 ml of an insult of 0.9% saline was poured into each sample. Physiological saline immediately penetrated the sample with added surfactant.
In the sample without surfactant, the saline insult remained on the sample for one hour at the end of the test.

Examples 14-16 demonstrate that the wettability of the airlaid composite structure of the present invention can be adjusted during manufacture and to achieve acceptable fluid penetration even with large (6 denier) synthetic fibers. Shows that a minimum level of hydrophilicity must be present in the latex resin.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] September 26, 2000 (2000.9.26)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number 60 / 102,344 (32) Priority date September 29, 1998 (September 29, 1998) (33) Priority claim country United States (US) ( 31) Priority claim number 09 / 232,783 (32) Priority date January 19, 1999 (Jan. 19, 1999) (33) Priority claim country United States (US) (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ , TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD, GE, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW , MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor John P. Elspammer United States Tennessee 38139 Bartlett Oak Burke Lane 3716 F-term (reference) 3B029 BA05 BA12 BA14 BA15 BA18 4C003 AA18 AA23 AA27 BA04 BA06 BA08 4C098 AA09 CC03 DD05 DD06 DD10 DD14 DD22 DD25 DD26 4F100 AJ04B AJ04C AJ06B AJ06C AJ07C AK01A AK01B AK01C AK04A AK07A AK25C AK25G AK27C AK42A AK68G AK73G AK74G AL01C AL04C BA03 BA07 BA10C DE01C DG06A DG06B DG17A DG17E DJA18J18 ECG

Claims (21)

[Claims] 1. A porous top layer comprising latex-bound synthetic matrix fibers having a length of about 3 to 15 mm, and (ii) air-laid cellulose fibers and thermoplastic fibers, latex and mixtures thereof. An absorber comprising a lower layer fluidly exchangeable with said upper layer, comprising a bonder selected from the group consisting of: 2. The synthetic matrix fiber has a length of about 6 to 12 mm.
The absorber according to claim 1. 3. The absorbent body according to claim 1, wherein the thickness of the synthetic matrix fiber is about 3 to 20 denier. 4. The absorbent body according to claim 3, wherein the thickness of the synthetic matrix fiber is about 6 to 15 denier. 5. The synthetic matrix fiber is polyethylene, polypropylene,
Selected from the group consisting of polyethylene terephthalate and mixtures thereof,
The absorber according to claim 1. 6. The absorber of claim 1, wherein the latex is selected from the group consisting of ethylene vinyl acetate, acrylic, styrene-butadiene, or an aqueous emulsion of styrene butadiene acrylic. 7. The absorbent body according to claim 1, wherein the cellulose fiber is selected from the group consisting of wood cellulose, cotton linter pulp, chemically modified cellulose, high-purity cellulose fiber, and a mixture thereof. 8. A capture layer comprising a latex-bound synthetic matrix fiber having a length of about 3 to 15 mm. (Ii) a thermal bond, a latex bond, or a combination thereof fluid exchangeable with said capture layer. And (iii) a storage layer comprising a thermally bonded cellulose fiber and superabsorbent polymer particles fluidly exchangeable with the dispersion layer. 9. The synthetic matrix fiber has a length of about 6 to 12 mm.
The structure according to claim 8. 10. The structure of claim 8, wherein the thickness of the synthetic matrix fiber is about 3 to 20 denier. 11. The structure of claim 10, wherein the thickness of the synthetic matrix fiber is about 6 to 15 denier. 12. The structure according to claim 8, wherein the synthetic matrix fibers are selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate and mixtures thereof. 13. The structure of claim 8, wherein the latex is selected from the group consisting of an aqueous emulsion of ethylene vinyl acetate, acrylic, styrene-butadiene, or styrene-butadiene acrylic. 14. The liquid dispersion layer and the liquid storage layer, wherein the cellulose fibers may be the same or different, and are selected from the group consisting of wood cellulose, cotton linter pulp, chemically modified cellulose, high purity cellulose fibers, and mixtures thereof. Done,
The structure according to claim 8. 15. The superabsorbent polymer particles comprise polyacrylate, starch graft copolymer, cross-linked carboxymethyl cellulose derivative, hydrolyzed starch-acrylonitrile graft copolymer, saponified acrylate ester.
9. The structure of claim 8, wherein the structure is selected from the group consisting of a vinyl copolymer, a modified crosslinked polyvinyl alcohol, a neutralized crosslinked polyacrylic acid, a crosslinked polyacrylate, and carboxylated cellulose. 16. The structure of claim 8, wherein the superabsorbent polymer particles are surface crosslinked. 17. The structure of claim 8, wherein the acquisition layer has a basis weight ranging from about 20 to 80 gsm. 18. The structure of claim 8, wherein the dispersion layer has a basis weight in a range from about 20 to 100 gsm. 19. The structure according to claim 8, wherein the storage layer has a basis weight in the range of about 60 to 400 gsm. 20. (i) a capture layer comprising latex-bound PET matrix fibers, wherein said matrix fibers have a length of about 3 to 12 mm and a thickness of about 6 to 15 denier, said capture layer comprising about 20 to 60 gsm; (Ii) a dispersion layer of cellulose fibers, said fibers being thermally bonded or chemically modified;
The dispersion layer has a basis weight in the range of about 30 to 90 gsm, the dispersion layer being fluid exchangeable with the acquisition layer); and (iii) a storage layer comprising cellulose fibers and superabsorbent polymer particles. (Wherein the fibers are thermally bonded and the storage layer has a basis weight in the range of about 70 to 130 gsm, and the storage layer is fluid exchangeable with the dispersion layer). 21. An acquisition layer comprising (i) a latex-bound PET matrix fiber, said matrix fiber being about 3 to 12 mm long and about 6 to 15 mm.
A denier thickness, wherein the capture layer has a basis weight in the range of about 20 to 60 gsm); (ii) a dispersion layer of cellulose fibers, wherein the fibers are thermally bonded or chemically modified;
The dispersion layer has a basis weight in the range of about 30 to 100 gsm,
And (iii) a storage layer comprising cellulose fibers and superabsorbent polymer particles, wherein the fibers are thermally bonded and the storage layer has a basis weight in the range of about 250 to 340 gsm. And the storage layer is fluid exchangeable with the dispersion layer).