TW201336481A - Water-absorbent sheet composite - Google Patents

Abstract

A water-absorbent sheet composite (10) having such a structure that an absorbent layer which contains both a water-absorbent resin (12) and an adhesive (11) is sandwiched by non-woven fabric sheets (16, 17), wherein: the absorbent layer is thicknesswise divided by a textile substrate (15) into a primary absorbent layer (13) and a secondary absorbent layer (14); the content of the water-absorbent resin (12) is 100 to 600g/m2; the content of the adhesive (11) is 0.05 to 2.0 times (by mass) that of the water-absorbent resin (12); and the ratio of the mass of the water-absorbent resin (12) in the primary absorbent layer (13) to the total mass of the water-absorbent resin (12) in the primary and secondary absorbent layers (13, 14) is 15 to less than 50%. An absorbent article wherein the water-absorbent sheet composite (10) is sandwiched between a liquid-permeable sheet and a liquid -impermeable sheet.

Description

Water-absorbent sheet structure

The present invention relates to a water-absorbent sheet structure which can be used in the fields of sanitary materials, agriculture, and building materials. More specifically, it relates to a water-absorbent sheet structure which is thin and can be preferably used for an absorbent article such as an incontinence pad. Further, the present invention relates to an absorbent article using an incontinence pad or the like having the water-absorbent sheet structure.

An absorbent article represented by an incontinence pad or the like has a structure in which a liquid absorbent body such as a body fluid is absorbed by a soft liquid permeable surface sheet (front side sheet) disposed on a side in contact with the body, and The liquid-impermeable back sheet (rear sheet) is placed on the opposite side to the side in contact with the body.

In the past, from the viewpoints of design, convenience to the body, and convenience in carrying, the demand for thinning and weight reduction of absorbent articles has been increasing. Further, in recent years, from the viewpoint of environmental protection, demand is increasingly focused on the efficient use of resources, and the use of an eco-friendly orientation such as a tree-like natural material that needs to grow for a long period of time is avoided as much as possible.

Therefore, a water-absorbent sheet structure is proposed which is used as a disintegrating pulp fiber of wood, and has a basic content (fast liquid penetration speed, sufficient liquid absorption capacity, less liquid return flow, and less). The water-absorbent sheet structure which is excellent in the amount of liquid leakage, the shape retention property, and the like, and has a specific amount of the water-absorbent resin and a specific amount of the hot-melt adhesive having a specific basis weight by two or more sheets. Hydrophilic non-woven fabric The structure of the clamp (for example, refer to Patent Document 1).

In addition, in order to further improve the performance, a water-absorbent sheet structure having a structure in which an absorbent layer containing a water-absorbent resin and an adhesive is divided by a specific water-permeable substrate is proposed (for example, refer to Patent Document 2) And a water-absorbent sheet structure in which an absorbent layer comprising a water-absorbent resin and an adhesive is divided into a primary absorbent layer and a secondary absorbent layer, and is used for the primary absorbent layer and the secondary absorbent layer. Each of the water absorbent resins has specific properties (for example, refer to Patent Document 3).

Prior technical literature Patent literature

Patent Document 1: International Publication No. 2010/004894

Patent Document 2: International Publication No. 2010/076857

Patent Document 3: International Publication No. 2010/082373

The water-absorbent sheet structure disclosed in Patent Documents 1 to 3 is excellent in the above-described basic properties, but a water-absorbent sheet structure in which performance is further improved is constantly required. In particular, in an absorbent article such as an incontinence pad, the wet touch is avoided, the demand for dry touch is strong, and a liquid permeation speed is required for a water-absorbent sheet structure for the same, Further performance improvements such as less liquid return flow.

An object of the present invention is to provide a water-absorbent sheet structure and an absorbent article using the same. Although the water-absorbent sheet structure is thin, its form retention is good, so that it does not occur before and after absorption of liquid. change Shape, and has excellent liquid permeability, less liquid return flow and the like.

The present invention relates to a water-absorbent sheet structure and an absorbent article, that is, [1] the water-absorbent sheet structure system having an absorbent layer comprising a water-absorbent resin and an adhesive agent is formed by weaving from above the absorbent layer and a structure for sandwiching the lower portion, and having a structure in which the absorption layer is divided into a primary absorption layer and a secondary absorption layer by a fibrous substrate, and the content of the water absorbent resin is 100 to 600 g/m ² . The content of the above-mentioned adhesive is 0.05 to 2.0 times the content (mass basis) of the water-absorbent resin, and the mass of the water-absorbent resin of the primary absorbent layer is based on the total mass of the absorbent resin of the primary absorbent layer and the secondary absorbent layer. In the absorbent article, the water-absorbent sheet structure according to the above (1) is sandwiched between the liquid-permeable sheet and the liquid-impermeable sheet. By.

Although the water-absorbent sheet structure of the present invention is thin, it has good form retention, and thus is not deformed before and after absorption of liquid, and can sufficiently exhibit excellent liquid permeation and less liquid flow rate. Excellent effect of absorption capacity. Therefore, by using the water-absorbent sheet structure of the present invention as an absorbent body such as an incontinence pad or the like, it is possible to provide an absorbent article which is thin and excellent in appearance.

The water-absorbent sheet structure of the present invention is characterized in that it has an absorbent layer containing a water-absorbent resin and an adhesive agent from the upper side of the absorbent layer by a nonwoven fabric. And a structure for sandwiching below, and having a structure in which an absorbent layer is formed between the nonwoven fabrics by using a specific amount of the water absorbent resin and the adhesive, and the absorbent layer is vertically divided into the primary absorbent layer by the fibrous substrate and 2 Further, the ratio of the mass of the water absorbent resin of the primary absorbent layer to the total mass of the water absorbent resin of the primary absorbent layer and the secondary absorbent layer is within a specific range. By forming this structure, a thin water-absorbent sheet structure excellent in liquid absorbing properties such as liquid permeability and liquid reflux flow can be realized.

Further, since the water-absorbent resin of the water-absorbent sheet structure system of the present invention is fixed to the nonwoven fabric by an adhesive, even if the hydrophilic fiber such as pulp fibers is not substantially contained, the water-absorbent resin can be prevented from being displaced or dissipated, and Morphological retention is also well maintained. Further, since the adhesive dose is in a specific range, the entire surface of the water absorbent resin is not covered by the adhesive, and one of the water absorbent resins is partially fixed. Therefore, it is considered that the water absorbability of the water absorbent resin is hardly affected. The barrier property is such that the water absorbent resin is sufficiently swollen.

The water-absorbent sheet structure of the present invention may be such that the hydrophilic fibers such as pulp fibers are present in a non-woven fabric together with the water-absorbent resin in an amount that does not impair the effects of the present invention, but are thin. From the viewpoint of chemical conversion, it is preferred that the hydrophilic fiber is not substantially contained.

As a kind of the water-absorbent resin in the water-absorbent sheet structure of the present invention, a commercially available water-absorbent resin can be used, and examples thereof include a hydrolyzate of a starch-acrylonitrile graft copolymer and a starch-acrylic graft polymer. A water-absorbent resin such as a neutralizer, a saponified product of a vinyl acetate-acrylate copolymer, a cross-linker of an acrylic partial neutralized polymer, a neutralized substance of a polyacrylic acid, or the like Wait. Among these, a crosslinked product of an acrylic partial neutralizer polymer is preferred from the viewpoint of industrial availability such as supply ability or cost. Examples of the method for synthesizing the crosslinked product of the acrylic acid partial neutralized polymer include a reverse phase suspension polymerization method, an aqueous solution polymerization method, and the like.

The water-absorbent sheet structure according to the present invention is also used for the absorbent article, and the water-absorbent resin in the water-absorbent sheet structure (adding the primary absorbent layer to the secondary absorbent layer) The content is 100 to 600 g (i.e., 100 to 600 g/m ² ) per square meter of the water-absorbent sheet structure, preferably 150 to 550 g/m ² , more preferably 200 to 500 g/m ² . The content is 100 g/m ² or more from the viewpoint of exerting sufficient liquid absorption performance as a water-absorbent sheet structure, particularly suppressing liquid reflux, and the content is 600 g/m ^{2 from} the viewpoint of improving the permeation speed of the liquid. the following.

The ratio of the mass of the water-absorbent resin of the primary absorbent layer to the total mass of the water-absorbent resin of the primary absorbent layer and the secondary absorbent layer is 15% or more and less than 50%, preferably 20 to 45%, more preferably It is 25~45%. From the viewpoint of increasing the permeation rate of the liquid, the ratio of the primary absorption layer is less than 50%, and the ratio of the primary absorption layer is 15% or more from the viewpoint of improving the dry feeling after liquid absorption and reducing the reflux of the liquid.

The liquid absorbing property of the water-absorbent sheet structure of the present invention is affected by the water absorbing property of the water-absorbent resin to be used. Therefore, in consideration of the constitution of each component of the water-absorbent sheet structure, etc., it is preferred that the water-absorbent resin used in the present invention has a preferred water absorbing property. Further, the water absorbing resin of the primary absorbent layer and the secondary absorbent layer may be the same or different.

In this specification, the water absorption capacity of the water-absorbent resin is absorbed as physiological saline. Water capacity is assessed. The water absorption capacity of the physiological saline solution of the water absorbent resin is preferably 20 g/g or more, more preferably 20 to 80 g, from the viewpoint of more absorbing liquid and strongly maintaining the gel at the time of absorption and preventing gelation. /g, and then preferably 30~70 g/g. The physiological saline water absorption capacity of the water absorbent resin is a value obtained by the measurement methods described in the following examples.

According to the viewpoint of preventing the dissipation of the water-absorbent resin in the water-absorbent sheet structure and the gel agglomeration phenomenon when water is absorbed, and reducing the roughness of the water-absorbent sheet structure and improving the feeling of touch, the water-repellent resin has a larger particle size. Preferably, it is 100 to 600 μm, more preferably 150 to 550 μm, and further preferably 200 to 500 μm. The median particle diameter of the water-absorbent resin is a value obtained by the measurement methods described in the following examples.

Examples of the adhesive used in the water-absorbent sheet structure of the present invention include rubber-based adhesives such as natural rubber, butyl rubber, and polyisoprene; and styrene-isoprene-styrene. Styrene-isoprene-styrene block polymer (SIS), Styrene-butadiene-styrene block polymer (SBS), styrene-isobutylene-styrene block Styrene-isoprene-butadiene-styrene block polymer (SIBS), styrene-ethylene-butylene-styrene block polymer (SEBS) Next agent; Ethylene vinyl acetate (EVA) adhesive; Ethylene ethyl acrylate (EEA), Ethylene butyl acrylate (EBA), etc. Ethylene-acrylic acid derivatives Polymeric adhesive; Ethylene Acrylic Acid (EAA) adhesive; polyamine-based adhesive such as copolymerized nylon, dimer acid polyamide; polyethylene, polypropylene, random polypropylene, A polyolefin-based adhesive such as a copolymerized polyolefin; a polyethylene terephthalate (PET), a polybutylene terephthalate (PBT), a copolymerized polyester, or the like. A polyester-based adhesive; an acrylic-based adhesive or the like. In the present invention, it is preferably selected from the group consisting of ethylene-vinyl acetate copolymer adhesives and styrene based on the viewpoint that the adhesion is strong and the release of the nonwoven fabric in the water-absorbent sheet structure and the dissipation of the water-absorbent resin are prevented. At least one of the group consisting of an elastomeric adhesive, a polyolefin-based adhesive, and a polyester-based adhesive. These adhesives may be used singly or in combination of two or more.

In the case of using a hot-melt type adhesive, the melting temperature or softening point of the adhesive is preferably from 50 to 180 ° C from the viewpoint of sufficiently fixing the water-absorbent resin to the nonwoven fabric and preventing thermal deterioration or deformation of the nonwoven fabric. More preferably 70~150 °C.

The content (multiple) of the adhesive in the water-absorbent sheet structure is 0.05 to 2.0 times, preferably 0.08 to 1.5 times, more preferably 0.1 to 1.0 times, relative to the content (mass basis) of the water absorbent resin. The content of the adhesive agent is preferably 0.05 times or more from the viewpoint of preventing the peeling of the nonwoven fabric or the dissipation of the water-absorbent resin and improving the form retention of the water-absorbent sheet structure by sufficient adhesion, and avoiding being too strong due to the subsequent adhesion. The content of the adhesive agent is 2.0 times or less from the viewpoint of hindering the swelling of the water-absorbent resin and improving the liquid permeation rate and the reflux flow rate of the water-absorbent sheet structure.

The non-woven fabric to be used in the present invention is not particularly limited as long as it is a nonwoven fabric known in the related art, but polyethylene (Polyethylene) can be cited from the viewpoints of liquid permeability, flexibility, and strength as a water-absorbent sheet structure. , PE), polypropylene (Polypropylene, PP) and other polyolefin fibers, polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polyethylene naphthalate Polyester fibers such as polyethylene naphthalene (PEN), polyamide fibers such as nylon, non-woven fabrics made of rayon fibers and other synthetic fibers, or mixed cotton, enamel, hemp, pulp (cellulose) fibers, etc. Made of non-woven fabrics, etc. From the viewpoint of improving the strength of the water-absorbent sheet structure and the like, it is preferable to use a non-woven fabric made of synthetic fibers in the nonwoven fabric, and it is particularly preferably selected from non-woven fabrics made of rayon fibers, non-woven fabrics made of polyolefin fibers, and non-woven fabrics made of polyester fibers. At least one of the group consisting of. These nonwoven fabrics may be non-woven fabrics composed of the above-mentioned fibers alone, or may be non-woven fabrics in which two or more kinds of fibers are combined.

More specifically, from the viewpoint of improving the form retention of the water-absorbent sheet structure and preventing the water-absorbent resin from falling off due to the perforation, it is more preferably selected from a mixture of polyolefin fibers, polyester fibers, and the like. a spunbonded non-woven fabric made of fibers in the group, and a hot-water non-woven fabric of water-needle non-woven fabric or polyolefin fiber containing yttrium fiber as a main component, from the viewpoint of further improving the liquid absorbing performance and flexibility at the time of forming the sheet. The non-woven fabric used in the present invention is also more preferable. In the above spunbonded nonwoven fabric, it is more preferable to use a multilayer structure of polyolefin fibers, that is, Spunbond-Meltblow-Spunbond (SMS) non-woven fabric, and spunbond-meltblown-meltblown-spun Spunbond-Meltblow-Meltblow-Spunbond (SMMS) is not woven, and it is particularly preferable to use SMS non-woven fabric and SMMS non-woven fabric mainly composed of polypropylene fibers. On the other hand, as the water needle non-woven fabric, it is preferable to suitably blend polyolefin fibers and/or polyester fibers into the ruthenium fibers of the main component, and it is preferable to use ruthenium/PET nonwoven fabric, and嫘萦/PET/PE non-woven. In the above nonwoven fabric, a small amount of pulp fibers may be contained without increasing the thickness of the water-absorbent sheet structure.

When the hydrophilicity of the non-woven fabric is too low, the liquid absorbing property of the water-absorbent sheet structure is deteriorated. On the other hand, even if the hydrophilicity is higher than necessary, the liquid absorbing performance is not improved to the extent that it is compatible. It is desirable to have moderate hydrophilicity. From this point of view, it is preferable to use a measurement method according to the following "hydrophilicity of non-woven fabric" to measure a degree of hydrophilicity of 5 to 200, more preferably 8 to 150, and still preferably 10 to 100, and further preferably For 12~80. The non-woven fabric having such hydrophilicity is not particularly limited, but those having a moderate degree of hydrophilicity in the nonwoven fabric as described above may be used, and may be used in a known manner such as polyolefin fiber or polyester fiber. The hydrophobic chemical fiber is hydrophilized to give it a moderate degree of hydrophilicity. The method of hydrophilization treatment is, for example, a method in which a non-woven fabric is obtained by a spunbonding method in which a hydrophilizing agent is mixed with a hydrophobic chemical fiber for a spunbonded nonwoven fabric; and a hydrophobic chemical fiber is produced. A method of simultaneously using a hydrophilizing agent when spunbonding a non-woven fabric; or a method of impregnating a hydrophilizing agent after obtaining a spunbonded non-woven fabric with a hydrophobic chemical fiber. As the hydrophilizing agent, an anionic surfactant such as an aliphatic sulfonate or a higher alcohol sulfate; an cation boundary such as a quaternary ammonium salt is used. Surfactant; non-ionic surfactant such as polyethylene glycol fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester; polyoxyalkylene modified polyoxane a surfactant; and a detergent comprising a polyester-based, polyamidiamine-based, acrylic-based, urethane-based resin.

The non-woven fabric that sandwiches the absorbent layer is preferably hydrophilic, from the viewpoint of further improving the liquid absorbing property of the water-absorbent sheet structure, but is particularly preferably hydrophilic for use in the nonwoven fabric under the absorbent layer, from the viewpoint of preventing liquid leakage. The hydrophilicity of the nonwoven fabric used above is equal or higher than that of the nonwoven fabric. The upper side of the absorbent layer in the present specification means the side to which the liquid to be absorbed is supplied when the absorbent article is produced using the obtained water-absorbent sheet structure, and the lower side of the absorbent layer means the opposite side.

From the viewpoint of imparting good liquid permeability, flexibility, form retention or cushioning property to the water-absorbent sheet structure of the present invention, and improving the liquid permeation rate of the water-absorbent sheet structure, the nonwoven fabric is preferably moderately bulky and has a unit area. Non-woven fabric with a large weight. The weight per unit area is preferably from 5 to 300 g/m ² , more preferably from 8 to 200 g/m ² , further preferably from 10 to 100 g/m ² , and further preferably from 11 to 50 g/m ² . Further, as the thickness of the nonwoven fabric, it is preferably 20 to 800 μm, more preferably 50 to 600 μm, and still more preferably 80 to 450 μm. As a method of measuring the thickness of the nonwoven fabric, the following method for measuring the thickness of the water-absorbent sheet structure in a dry state can be employed.

One of the features of the present invention is that, by using a fibrous substrate, the entire surface or a portion of the absorbent layer of the water-absorbent sheet structure is divided into the upper primary absorbent layer and the lower secondary layer in the vertical direction (the thickness direction of the sheet). The construction of the absorbent layer. The fibrous matrix used herein facilitates feeding into the absorbent sheet structure The liquid is diffused and is expected to have a temporary water retention effect before the water absorbent resin absorbs the liquid.

When the material of the fibrous substrate is selected, if the fiber having excessive diffusion of the liquid is selected, there is a possibility that the secondary absorption layer is not effectively used to cause liquid leakage. Further, when a fiber having excessive water permeation is selected, there is a possibility that the absorption layer is not used efficiently and the liquid is rapidly distributed to the secondary absorption layer to cause gelation. Further, when the water retaining effect is too high, the absorption of the water-absorbent resin is hindered, and the performance of the liquid return flow of the water-absorbent sheet structure is deteriorated. The degree of hydrophilicity measured according to the measurement method of the "hydrophilicity of non-woven fabric" described above is preferably from 8 to 100, more preferably from 10 to 80, and even more preferably from 12 to 60, from the viewpoint of the above-mentioned liquid diffusion and water permeability. Preferred examples of the fibrous substrate include sanitary paper, synthetic fiber nonwoven fabric containing cellulose, synthetic fiber nonwoven fabric containing enamel, and synthetic fiber nonwoven fabric after hydrophilization treatment.

Examples of the sanitary paper include toilet paper, absorbent paper, and towel paper. Examples of the cellulose-containing synthetic fiber nonwoven fabric include an air-laid nonwoven fabric comprising pulp/PET/polyethylene (PE), pulp/PET/polypropylene (PP), pulp/PE/PP, and the like. Examples of the synthetic fiber nonwoven fabric containing ruthenium include a water needle nonwoven fabric comprising 嫘萦/PET, 嫘萦/PE, 嫘萦/PET/PE, and the like. The synthetic fiber nonwoven fabric after the hydrophilization treatment may, for example, be coated with a fatty acid ester type nonionic surfactant or a polyglycerin fat on a hot air non-woven fabric or a spunbonded nonwoven fabric containing a polyolefin of PE, PP, PE/PP. Non-woven fabric of a hydrophilic surfactant such as an acid ester. Among the fibrous substrates, depending on the strength of the fibrous substrate or From the viewpoint of various performance surfaces (liquid reflux, form retention, etc.) of the obtained water-absorbent sheet structure, it is preferred to use a group consisting of a synthetic fiber nonwoven fabric selected from a synthetic fiber nonwoven fabric containing ruthenium and a hydrophilized treatment. One of them is more preferably a synthetic fiber non-woven fabric after hydrophilization treatment. Further, the fibrous base may be a non-woven fabric using a single fiber or a non-woven fabric in which two or more kinds of fibers are combined.

The thickness of the fibrous substrate is preferably 80 μm or more, more preferably 100 to 2000 μm, and still more preferably 150 to 1000 μm. Further, the basis weight of the fibrous substrate is preferably 10 g/m ² or more, and more preferably 12 to 200 g/m ² . From the viewpoint of making the water-absorbent sheet structure thin, the thickness of the fibrous substrate is 2000 μm or less, and the basis weight of the fibrous substrate is preferably 200 g/m ² or less, and on the other hand, the structure of the water-absorbent sheet is ensured. The viewpoint of the sufficient strength for stretching or wrinkling at the time of manufacture and use, and the viewpoint that the various properties of the water-absorbent sheet structure under load are good, the thickness of the fibrous substrate is 80 μm, and the unit area of the fibrous substrate A weight of 10 g/m ² or more is preferred. As a method of measuring the thickness of the fibrous substrate, a method of measuring the thickness of the following water-absorbent sheet structure in a dry state can be employed.

The water-absorbent sheet structure of the present invention can be produced, for example, by the following method.

(a) The mixed powder of the water-absorbent resin and the adhesive is uniformly spread on the non-woven fabric, and the fibrous substrate is laminated, and the semi-finished product is obtained by heat-compression bonding in the vicinity of the melting temperature of the adhesive. On the semi-finished product, the mixed powder was dispersed in the same manner as described above, and the non-woven fabric was placed thereon, and the pressure-bonding was performed by heating.

(b) Spreading the water-absorbent resin and the adhesive evenly on the non-woven fabric After the powder is mixed and the fibrous substrate is overlapped, the mixed powder is again dispersed, and the non-woven fabric is superposed and heated and pressure-bonded.

(c) uniformly dispersing a mixed powder of a water-absorbent resin and an adhesive on a non-woven fabric, and passing it through a heating furnace to fix the powder to such an extent that it does not escape. After the fiber matrix is overlapped, the mixed powder is again dispersed, and the non-woven fabric is superimposed and heated and crimped.

(d) Immediately after melt-coating the adhesive on the nonwoven fabric, the water-absorbent resin is uniformly dispersed to form a layer, and further, the adhesive is applied from the upper portion and the fibrous substrate is superposed to obtain a semi-finished product. After the adhesive is melt-coated in the same manner as described above, the water-absorbent resin is uniformly dispersed to form a layer, and further, the adhesive is applied from the upper portion and the nonwoven fabric is superposed thereon, and the pressure-bonding is performed in a unified manner.

Further, the method of exemplifying the methods of (a) to (d) may be carried out by separately selecting and combining the absorption method of the primary absorption layer and the secondary absorption layer. It is also possible to improve the touch of the water-absorbent sheet structure and to improve the shape retention property, and perform embossing processing at the time of heat-pressure bonding in the production of the water-absorbent sheet structure or after the production of the water-absorbent sheet structure.

Further, in the water-absorbent sheet structure of the present invention, an additive such as a deodorant, an antibacterial agent or a gel stabilizer may be appropriately formulated.

The water-absorbent sheet structure of the present invention has the advantage of being thinner, and in consideration of the absorbent article, the thickness of the water-absorbent sheet structure is preferably 4 mm or less, more preferably 3 mm or less in a dry state. Further preferably 1.0 to 2.5 mm. The dry state refers to a state before the water-absorbent sheet structure absorbs liquid. In the present specification, the thickness of the dried state of the water-absorbent sheet structure is The values obtained by the measurement methods described in the following examples.

Further, the water-absorbent sheet structure of the present invention has a characteristic that the liquid permeation rate is fast, and in consideration of the absorbent article, the total liquid permeation rate of the water-absorbent sheet structure is preferably 400 seconds or less, more preferably 350. Less than seconds. In the present specification, the total liquid permeation rate of the water-absorbent sheet structure is a value obtained by the measurement method described in the following examples.

Further, the water-absorbent sheet structure of the present invention has a characteristic that the liquid return flow rate is small, and in consideration of the absorbent article, the liquid return flow rate of the water-absorbent sheet structure is preferably 12 g or less, more preferably 10 g. the following. In the present specification, the liquid return flow rate of the water-absorbent sheet structure is a value obtained by the measurement method described in the following examples.

Further, the water-absorbent sheet structure of the present invention has a characteristic that the leakage of the liquid at the time of tilting is small, and the total amount of leakage due to the inclination of the water-absorbent sheet structure is preferably 14 g in consideration of the absorbent article. Hereinafter, it is more preferably 12 g or less, and further preferably 10 g or less. In the present specification, the total amount of leakage caused by the inclination of the water-absorbent sheet structure is a value obtained by the measurement method described in the following examples.

As the water-absorbent sheet structure of the present invention, it is preferred that the thickness in the dry state, the total liquid permeation rate, the liquid return flow rate, and the total amount of leakage caused by the inclination have specific characteristics.

Further, in the water-absorbent sheet structure of the present invention, since the amount of the natural-derived material is extremely small, it is high in terms of the thickness, the permeation rate, and the liquid return flow rate described above, and is also completed in consideration of the environment. . The use ratio of the natural material is preferably 30% by mass or less, more preferably 20% by mass or less. Further, it is preferably 15% by mass or less. The ratio of use of the natural material is calculated by dividing the total content of pulp, cotton, hemp, and enamel contained in a small amount in each constituent component of the water-absorbent sheet structure by the mass of the water-absorbent sheet structure.

Next, the structure of the water-absorbent sheet structure of the present invention will be described with reference to Fig. 1 . Here, Fig. 1 is an enlarged cross-sectional view schematically showing the structure of the water-absorbent sheet structure of the present invention.

The water-absorbent sheet structure 10 shown in Fig. 1 includes a primary absorbent layer 13 containing a water-absorbent resin 12 and an adhesive 11, and a secondary absorbent layer 14 comprising a water-absorbent resin 12 and an adhesive 11. Here, the primary absorption layer refers to the side to which the liquid to be absorbed is supplied when the absorbent article is produced using the water-absorbent sheet structure, and the secondary absorption layer refers to the primary absorption of the fiber matrix 15 The opposite side of the layer.

Further, the primary absorbent layer 13 and the secondary absorbent layer 14 are divided by the fibrous substrate 15, and the water-absorbent sheet structure 10 includes a primary absorbent layer 13, a secondary absorbent layer 14, a fibrous substrate 15, and is contained therein. a five-layer structure of two layers of the front and back layers of the non-woven fabrics 16 and 17 on the outer surfaces of the primary absorbent layer 13 and the secondary absorbent layer 14, the absorbent layer being above and below the absorbent layer by the nonwoven fabrics 16 and 17. The structure of the clamp.

Moreover, the water-absorbent sheet structure shown in Fig. 2 is also an example of another form of the water-absorbent sheet structure of the present invention. In Fig. 2, an example in which the adhesive 18 is melt-coated on the nonwoven fabric 17 or the like is used.

The absorbent sheet of the present invention can be obtained by sandwiching the water-absorbent sheet structure of the present invention between a liquid-permeable sheet and a liquid-impermeable sheet. Further, the liquid-permeable sheet is placed on the upper side and the liquid-impermeable sheet is placed on the lower side. The liquid permeable sheet and the liquid-impermeable sheet can be used without any particular limitation, and those skilled in the art can be used without any particular limitation. Further, the absorbent article can be produced by a known method.

Examples of the absorbent article include a disposable diaper, an incontinence pad, a menstrual sanitary napkin, a pet urine pad, a drip pad for food, and a water stopping agent for a power cable.

Example

Hereinafter, the present invention will be described in detail by way of examples, but the invention is not limited thereto.

The properties of the water-absorbent resin were measured by the following methods.

<Water absorption capacity of physiological saline of water-absorbent resin>

500 g of a 0.9% by mass aqueous solution of sodium chloride (physiological saline) was weighed and stirred in a 500 mL beaker at a rate of 600 r/min while 2.0 g of the water-absorbent resin was allowed to form no caking. And scattered. The mixture was allowed to stand for 60 minutes while stirring, and the water absorbent resin was sufficiently swollen. Thereafter, the mass Wa (g) of the mesh sieve of 75 μm was measured in advance, and the contents of the beaker were filtered using the standard sieve, and the sieve was placed in a state of being inclined at an inclination angle of about 30 degrees with respect to the horizontal for 30 minutes. In order to filter out the remaining moisture. The mass Wb (g) of the sieve containing the swelled water-absorbent resin was measured, and the water absorption capacity of the physiological saline of the water-absorbent resin was determined according to the following formula.

Water absorption capacity of water-absorbent resin (g/g) = [Wb-Wa] (g) / water absorption Quality of resin (g)

<Waterborne resin medium particle size>

0.25 g of amorphous cerium oxide (Degussa Japan, Siperant 200) was mixed as a lubricant in 50 g of the water-absorbent resin.

The water-absorbent resin was passed through a mesh of 250 μm in a mesh of a JIS (Japanese Industrial Standard) standard sieve, and the median was measured using a combination of the sieves of (A) when it was passed at 50% by mass or more. The particle size, and in the case where the amount exceeds 50% by mass on the sieve, the combination of the sieve of (B) is used to determine the median diameter.

(A) JIS standard sieve from the top, according to the mesh 425 μm sieve, mesh 250 μm sieve, mesh 180 μm sieve, mesh 150 μm sieve, mesh 106 μm sieve, mesh 75 The order of μm sieve, mesh 45 μm sieve and tray is combined.

(B) JIS standard sieve from the top, according to the mesh 850 μm sieve, mesh 600 μm sieve, mesh 500 μm sieve, mesh 425 μm sieve, mesh 300 μm sieve, mesh 250 The order of μm sieve, mesh 150 μm sieve and tray is combined.

The above water-absorbent resin was placed in the uppermost sieve to be combined, and it was classified by shaking with a shaker shaker for 20 minutes.

After the classification, the mass percentage of the mass of the water-absorbent resin remaining on each sieve relative to the total amount is calculated, and is accumulated sequentially from the larger particle size, thereby the mesh of the sieve and the residue remaining on the sieve The relationship between the cumulative values of the mass percentages of the water-absorbing resin is plotted on a logarithmic probability paper. Draw a point on a straight line of continuous probability paper, which will be equivalent to a cumulative mass percentage of 50% by mass. The particle size is used as the median diameter.

<Water resistance of non-woven fabric>

In the present specification, the hydrophilicity of the nonwoven fabric is measured by using the apparatus described in the "water repellency test method" of the pulp test method No. 68 (2000).

In other words, the test piece mounting device having an inclination of 45 degrees is cut in a short strip shape having a width × length of 10 cm × 30 cm and the longitudinal direction is the longitudinal direction (mechanical direction) of the nonwoven fabric. Test piece. For the time being, the burette opening portion of the burette has been adjusted to supply 10 g of distilled water burette every 30 seconds for drying, and the burette is disposed at the front end of the burette from the uppermost portion of the test piece attached to the device having the inclination. The part of the direction of 5 mm is fixed. About 60 g of distilled water was added from the upper portion of the burette, and the time (seconds) from when the liquid was dropped from the tip end of the burette to the non-woven test piece until the test piece could not hold the liquid and the liquid leaked from the lower portion was measured, and it was used as the hydrophilicity of the nonwoven fabric. The larger the value, the higher the degree of hydrophilicity.

Usually, the non-woven fabric having hydrophilicity of the material itself or the non-woven fabric subjected to the hydrophilization treatment has a hydrophilicity value of 5 or more. On the other hand, for the non-woven fabric of the less hydrophilic material, there is a liquid on the surface. Flows nearby and leaks out from the lower part faster.

(Example 1)

On a hot melt coater (manufactured by Hallys Co., Marshall 150) with a heating temperature of 150 ° C, a water needle non-woven fabric having a width of 15 cm was laid (the fiber was 嫘萦/PET, and the basis weight was 35 g/m ^{2 ).} Having a thickness of 300 μm, a hydrophilicity of 38, and a "non-woven fabric A", the styrene-butadiene-styrene block copolymer (SBS, softening point 85 ° C) as an adhesive is based on the weight per unit area. 15 g/m ^{2 was} coated on the nonwoven fabric.

Next, a cross-linked polymer of a partially neutralized acrylic acid polymer was added to the inlet of a roll type spreader (manufactured by Hashima Co., Ltd., SINTERACE M/C) (Aquarium SA60S, manufactured by Sumitomo Seika Co., Ltd., and the water absorption capacity of the saline was 61 g/g, a median particle size of 330 μm; as a "water-absorbent resin"). On the other hand, on the conveyor belt at the lower portion of the spreader, the above-mentioned adhesive-coated nonwoven fabric A is laid so that the adhesive-coated surface becomes the upper surface. Then, the spreading roller and the lower conveyor belt were operated, whereby the water absorbent resin was uniformly laminated on the nonwoven fabric at a basis weight of 250 g/m ² .

Using a hot air non-woven fabric (fiber is PP/PE, thickness is 300 μm, weight per unit area is 23 g/m ² , hydrophilicity = 33, and is set to "non-woven fabric B") as a weight per unit area in the same manner as above. g/m ^{2 is} coated with the fiber substrate of the above-mentioned SBS as an adhesive, and after laminating the obtained laminate from the upper portion, by a laminator having a heating temperature of 100 ° C (manufactured by Hashima Co., Ltd., a straight line) Then, the press machine HP-600 LF) is thermally welded to integrate the same, thereby obtaining a water-absorbent sheet structural semi-finished product.

In the same manner as described above, the SBS was applied as an adhesive to the non-woven fabric B of the semi-finished product of the water-absorbent sheet structure at a basis weight of 6 g/m ² on the hot-melt coater having a heating temperature of 150 °C. .

Next, a water-absorbent resin is added to the inlet of the roll type spreader. On the other hand, on the conveyor belt at the lower portion of the spreader, the water-absorbent sheet structure semi-finished product is laid so that the adhesive-coated surface becomes the upper surface. Then, the dispersion roller and the lower conveyor belt were operated, whereby the water absorbent resin was uniformly laminated on the above-mentioned water-absorbent sheet structure blank by a basis weight of 100 g/m ² .

By laminating the obtained non-woven fabric B coated with the above SBS at a weight per unit area of 6 g/m ² from the upper portion, the layer having the heating temperature set to 100 ° C is used. A press (manufactured by Hashima Co., Ltd., a linear press press HP-600 LF) was thermally welded to integrate the same, thereby obtaining a water-absorbent sheet structure. If the cross section of the structure of the obtained water-absorbent sheet composition is schematically shown, it is a structure as shown in FIG.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 100 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

(Examples 2 and 3)

The water-absorbent sheet structure was obtained in the same manner as in Example 1 except that the content of the water-absorbent resin and the adhesive used in Example 1 was changed as described in Table 1.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 120 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

(Example 4)

The water-absorbent sheet structure was obtained in the same manner as in Example 1 except that the content of the water-absorbent resin and the adhesive used in Example 1 was changed as described in Table 1.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 150 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

(Example 5)

To the inlet of a roll-type spreader (manufactured by Hashima Co., Ltd., SINTERACE M/C), 105 parts by mass of an ethylene-vinyl acetate copolymer (EVA, melting temperature: 95 ° C) as an adhesive was added, and a water-absorbent resin was added. 350 parts by mass are evenly mixed. On the other hand, a non-woven fabric A having a width of 15 cm was laid on the conveyor belt at the lower portion of the roll type spreader. Then, the spreading roller and the lower conveyor belt were operated, whereby the above mixture was uniformly laminated on the above-mentioned nonwoven fabric at a basis weight of 455 g/m ² .

After the laminate obtained by sandwiching the non-woven fabric B as a fibrous substrate from the upper portion, it was passed through a laminator (manufactured by Hashima Co., Ltd., linear extrusion press HP-600 LF) having a heating temperature of 130 ° C. These are integrated by heat welding to obtain a semi-finished product of the water-absorbent sheet structure.

Then, 45 parts by mass of EVA as an adhesive and 150 parts by mass of a water-absorbent resin were uniformly mixed in the same manner as described above in the inlet of the roll-type spreader. On the other hand, on the conveyor belt of the roll type spreader, the obtained water-absorbent sheet structure semi-finished product was laid so that the nonwoven fabric B side became the upper part. The spreading roller and the lower conveyor belt were operated, whereby the above mixture was uniformly laminated on the non-woven fabric B of the above-mentioned water-absorbent sheet structural semi-finished product at a basis weight of 195 g/m ² .

After the laminate obtained by sandwiching the nonwoven fabric B from the upper portion, the laminate was obtained by a laminator (manufactured by Hashima Co., Ltd., linear extrusion press HP-600 LF) having a heating temperature of 130 ° C. These are integrated by heat welding to obtain a water-absorbent sheet structure. If the cross section of the structure of the obtained water-absorbent sheet composition is schematically shown, it is a configuration as shown in FIG.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 150 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

(Comparative Example 1)

The water-absorbent sheet structure was obtained in the same manner as in Example 1 except that the content of the water-absorbent resin and the adhesive used in Example 1 was changed as described in Table 1.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 140 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

(Comparative Example 2)

The content of the water-absorbent resin and the adhesive used in Example 5 was changed as described in Table 1, and the same as in Example 1 was used. The water-absorbent sheet structure was obtained by the method.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 70 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

(Comparative Example 3)

The water-absorbent sheet structure was obtained in the same manner as in Example 1 except that the content of the water-absorbent resin and the adhesive used in Example 5 was changed as described in Table 1.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 320 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

(Comparative Example 4)

The water-absorbent sheet structure was obtained in the same manner as in Example 1 except that the content of the water-absorbent resin and the adhesive used in Example 1 was changed as described in Table 1.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 20 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

(Comparative Example 5)

The content of the water-absorbent resin and the adhesive used in Example 5 was changed as described in Table 1, and the same as in Example 1 was used. The water-absorbent sheet structure was obtained by the method.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 120 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

(Comparative Example 6)

The water-absorbent sheet structure was obtained in the same manner as in Example 1 except that the content of the water-absorbent resin and the adhesive used in Example 5 was changed as described in Table 1.

The obtained water-absorbent sheet structure was cut into a specific size, and an absorbent layer having a water-absorbent resin having a basis weight of 150 g/m ² was used as an upper layer (primary absorption layer), and various types described below were used. Determination and evaluation. The results are shown in Table 1.

<Measurement of Thickness of Water Absorbing Sheet Structure>

The thickness of the obtained water-absorbent sheet structure was measured using a thickness measuring device (manufactured by Ozaki Seisakusho Co., Ltd., model: J-B). The three parts of the left end, the center, and the right end are arbitrarily selected as the measurement site in the longitudinal direction. For example, in the case of 7.5×20 cm, the 5 cm from the left is the left end, the 10 cm is the center, and the 15 cm is the right end. . The width direction is measured at the center of the equal.

The measured value of the thickness was measured three times at each site and the average value thereof was taken. Further, the average value of the values of the left end, the center, and the right end was taken as the thickness of the entire water-absorbent sheet structure.

<Form retention of water-absorbent sheet structure>

The form retention of the water-absorbent sheet structure was evaluated by the following method.

The obtained water-absorbent sheet structure was cut into a size of 10 × 10 cm. Then, double-sided tape was adhered to the entire surface of each of two sheets of 10 × 10 cm acrylic sheets (about 60 g in mass). As shown in FIG. 3, the diagonal lines of the acrylic sheets 21 and 22 are 45 degrees, and the double-sided tape is clamped from the upper and lower sides so as to face the water-absorbent sheet structure 23 side. So that it can't move.

The test piece of the water-absorbent sheet structure thus prepared is placed in a metal tray for the sieve used in the above-mentioned <water-absorbent resin medium-sized particle size> and capped, and then shaken by a shaker type. The machine performs a 3-minute rotary tap (at this time, between the tray and the beater, the mesh screen as a spacer may be any layer). The form retention of the water-absorbent sheet structure was evaluated based on the appearance after the tapping and based on the following criteria.

A: There is no change in appearance, and even if an attempt is made to offset the acrylic sheet, it does not easily move.

B: There is no change in appearance, but if the acrylic sheet is displaced, the water-absorbent sheet structure peels off from the center.

C: The water-absorbent sheet structure was split into two parts from the center, and the contents were scattered.

<Evaluation of liquid permeation rate and liquid return flow of water-absorbent sheet structure>

The water-absorbent sheet structure was cut into a short strip shape of 7.5 × 20 cm and the longitudinal direction was the longitudinal direction (mechanical direction) of the nonwoven fabric, and was used as a sample.

In a 10 L volume container, add 60 g of sodium chloride, calcium chloride dihydrate and 1.8 g, magnesium chloride hexahydrate and 3.6 g, and an appropriate amount of distilled water to make it completely Dissolved. Next, 15 g of a 1% by mass aqueous solution of poly(oxyethylene)isooctylphenyl ether was added, and further, distilled water was added thereto, and the mass of the entire aqueous solution was adjusted to 6000 g, and then a small amount of blue No. 1 was colored to prepare a test solution.

The upper part of the sample (water-absorbent sheet structure) was placed with a hot air type porous liquid permeability made of polyethylene having the same size (7.5 × 20 cm) and a basis weight of 22 g/m ² . Sheet. Further, under the sample, a liquid-impermeable sheet made of polyethylene having the same size and basis weight as the sheet was placed, and a simple absorbent article was produced. In the vicinity of the center of the absorbent article, an acrylic plate having a bottom area of 16.8 cm ² having an inner diameter of 1.9 cm and a height of 20 cm is placed in the center, and the weight is placed on the acrylic plate to form a total A load of 780 g is applied to the state of the sample. 50 mL of the test solution was dispensed into the cylinder at a time, and the time until the test solution was completely infiltrated into the absorbent article was measured using a stopwatch as the first liquid permeation rate (sec). Then, the same operation was carried out 3 minutes after the end of the absorption of the test solution, and the second liquid permeation rate (second) was measured. The total number of seconds of the first and second liquid permeation rates is taken as the total liquid permeation rate.

The acrylic plate was removed 10 minutes after the end of the absorption of the test solution of the second time, and a mass of 55 mm in diameter (Wc (g), about 3 g) was placed in advance near the liquid input position on the absorbent article. Filter paper (10 pieces) with a weight of 700 g on a 50 mm diameter. After a load of 1 minute was applied, the mass (Wd(g)) of the filter paper was measured, and the mass added was taken as the liquid reflux (g).

Liquid return flow (g)=Wd-Wc(g)

<Evaluation of the amount of leakage when tilting>

The amount of leakage at the time of tilting was measured using the apparatus shown in Fig. 4.

Roughly speaking, it is a mechanism for putting the test solution into the plate by using the dropping funnel 34 from the vertical upper side, using the gantry 31 for commercially available experimental equipment, and tilting and fixing the acrylic plate 32. In the upper absorbent article 33, the amount of leakage is weighed using the balance 35. The detailed specifications are shown below.

The acryl plate 32 has a length of 45 cm in the direction of the inclined surface, and is fixed by the gantry 31 at an angle of 45 ± 2° with respect to the horizontal. The acrylic plate 32 has a width of 100 cm and a thickness of 1 cm, and a plurality of water-absorbent sheet structures 33 can be simultaneously measured. Since the surface of the acrylic plate 32 is smooth, there is no case where liquid is retained on the plate or absorbed by the plate.

Using the gantry 31, the dropping funnel 34 is fixed to the vertical upper side of the inclined acryl plate 32. The dropping funnel 34 has a capacity of 100 mL, and the inner diameter of the front end portion is about 4 mm, and the plug valve is adjusted by inputting the liquid at 10 mL/sec.

At the lower portion of the acrylic plate 32, a balance 35 on which the tray 36 is placed is provided, and all the test liquid which has flowed as a leak is received, and its mass is recorded with an accuracy of 0.1 g.

The leak test when tilting using such a device is performed in the following order. After measuring the mass of the water-absorbent sheet structure which was cut into a strip shape having a width of 7.5 cm and a length of 20 cm and which was cut in the longitudinal direction (mechanical direction) of the nonwoven fabric, the same size was attached from above. A liquid-permeable non-woven fabric (having a weight per unit area of 22 g/m ² ) made of hot-air polyethylene, and further, a liquid-impermeable sheet made of polyethylene of the same size and weight per unit area is attached from below to make a simple absorption. The article 33 is adhered to the acrylic sheet 32 (the lower end of the absorbent article 33 is not adhered to the acrylic sheet 32 because the leakage is not artificially prevented).

The portion in the direction of 2 cm from the upper end of the absorbent article 33 was marked, and the inlet of the dropping funnel 34 was fixed so that the distance from the mark was 10 ± 1 mm.

After the balance 35 is started, the display is corrected to zero, and 50 mL of the test solution is once introduced into the dropping funnel 34. The amount of liquid that the test solution is not absorbed by the absorbent article 33 and flows along the inclined acrylic plate 32 and flows into the tray 36 is measured, and this is used as the first leakage amount (g).

The second test solution was injected in the same manner every 10 minutes from the start of the first injection, and the second leakage amount (g) was measured. The total (g) of the first and second leakage amounts is taken as the total leakage amount at the time of inclination.

According to the above results, compared with the water-absorbent sheet structures of Comparative Examples 1 to 6, the water-absorbing sheet structures of Examples 1 to 5 had a faster liquid permeation rate, a smaller liquid flow rate, and a leakage amount at the time of tilting. Less, the liquid absorption performance is good, and the form retention is also excellent.

On the other hand, in the case of the comparative example, when the ratio of the water absorbent resin of the primary absorbent layer is 50% or more (Comparative Example 1), the ratio of the secondary absorbent layer is relatively small, so the amount of leakage at the time of tilting In particular, the evaluation of the first leak is low. When the ratio of the water-absorbent resin in the primary absorbent layer is less than 15% (Comparative Example 2), the ratio of the secondary absorbent layer is relatively large, so that gelation occurs, and the amount of leakage at the time of tilting is particularly large. The evaluation of the two-time leakage and liquid return flow is low. When the content of the water-absorbent resin used in the water-absorbent sheet structure exceeds 600 g/m ² (Comparative Example 3), the water-absorbent resin is liable to cause gelation agglomeration, and the liquid permeation rate or the leakage at the time of tilting The assessment of the amount is lower. On the contrary, when the content of the water-absorbent resin is less than 100 g/m ² (Comparative Example 4), the water absorbing ability of the water-absorbent sheet structure as a whole is lowered, thereby causing an evaluation of the amount of leakage when the liquid is returned or tilted. low. When the ratio of the subsequent dose to the water-absorbent resin is large (Comparative Example 5), the swelling of the water-absorbent resin at the time of liquid absorption is hindered, and gelation agglomeration occurs, so that the liquid permeation rate and the liquid return The assessment of leakage and flow rate is lower. On the other hand, when the ratio of the subsequent dose to the water-absorbent resin is small (Comparative Example 6), although the water absorption performance is a usable level, there is a problem in strength, and thus the form retention property is insufficient, and it is used as a water-absorbent sheet. The material structure can not be fully satisfied.

Industrial availability

The water-absorbent sheet structure of the present invention can be used for absorbent articles in the fields of sanitary materials, agriculture, and building materials, and particularly, it can be preferably used for absorbent articles such as incontinence pads in the field of sanitary materials.

10‧‧‧Water-absorbing sheet structure

11‧‧‧Binder

12‧‧‧Water-absorbent resin

13‧‧1 times absorption layer

14‧‧2 times absorption layer

15‧‧‧Fiber matrix

16‧‧‧Nonwoven

17‧‧‧Nonwoven

18‧‧‧Adhesive

21‧‧‧Acrylic sheet

22‧‧‧Acrylic sheet

23‧‧‧Water-absorbing sheet structure

31‧‧‧ 台台

32‧‧‧Acrylic sheet

33‧‧‧Absorbables

34‧‧‧ dripping funnel

35‧‧‧ Balance

36‧‧‧Tray

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing an example of a water-absorbent sheet structure of the present invention.

Fig. 2 is a schematic cross-sectional view showing another example of the water-absorbent sheet structure of the present invention.

Fig. 3 is a schematic view showing a schematic configuration of an apparatus for measuring the form retention of a water-absorbent sheet structure.

Fig. 4 is a schematic view showing a schematic configuration of an apparatus for measuring a leak test when the water-absorbent sheet structure is inclined.

10‧‧‧Water-absorbing sheet structure

11‧‧‧Binder

12‧‧‧Water-absorbent resin

13‧‧1 times absorption layer

14‧‧2 times absorption layer

15‧‧‧Fiber matrix

16‧‧‧Nonwoven

17‧‧‧Nonwoven

Claims (6)

A water-absorbent sheet structure having a structure in which an absorbent layer comprising a water-absorbent resin and an adhesive is sandwiched from above and below the absorbent layer by a nonwoven fabric, and having the absorbent layer by a fibrous substrate The structure in which the upper absorbent layer is divided into the primary absorbent layer and the secondary absorbent layer, the content of the water-absorbent resin is 100 to 600 g/m ² , and the content of the above-mentioned adhesive is relative to the content of the water-absorbent resin (mass basis). 0.05 to 2.0 times, the ratio of the mass of the water absorbent resin of the primary absorbent layer to the total mass of the water absorbent resin of the primary absorbent layer and the secondary absorbent layer is 15% or more and less than 50%. The water-absorbent sheet structure according to claim 1, wherein the fibrous substrate is at least one selected from the group consisting of a synthetic fiber nonwoven fabric containing enamel and a synthetic fiber nonwoven fabric after hydrophilization treatment. The water-absorbent sheet structure according to claim 1, wherein the nonwoven fabric is at least one selected from the group consisting of rayon nonwoven fabric, polyolefin fiber nonwoven fabric, and polyester fiber nonwoven fabric. The water-absorbent sheet structure according to claim 2, wherein the nonwoven fabric is at least one selected from the group consisting of a nonwoven fabric nonwoven fabric, a polyolefin fiber nonwoven fabric, and a polyester fiber nonwoven fabric. The water-absorbent sheet structure according to any one of claims 1 to 4, wherein the adhesive is selected from the group consisting of an ethylene-vinyl acetate copolymer adhesive, a styrene-based elastomer adhesive, a polyolefin-based adhesive, and a polyester system. At least one of the group consisting of the following agents. An absorbent article which is obtained by sandwiching a water-absorbent sheet structure according to any one of claims 1 to 5 between a liquid-permeable sheet and a liquid-impermeable sheet.