JP5716606B2 - SAP sheet - Google Patents

Description

  The present invention relates to an SAP sheet used for an absorbent body or the like constituting an absorbent article.

  In absorbent articles such as disposable diapers, urine pads, and sanitary products, pulp and super absorbent polymer (SAP) are used as absorbents that absorb urine and body fluids.

  Usually, these absorbent materials are disposed on the skin contact surface side of the absorbent article as an absorbent body formed into a thin sheet shape, mat shape or the like. For example, an absorber in which SAP particles are dispersedly arranged in a pulp mat and an absorber in which the SAP particles are arranged in layers between a plurality of pulp mats are known.

  By the way, in recent years, in addition to the basic function that the absorbent article is excellent in excretion absorbability and has no leakage, it is required to improve the feeling of wearing and the appearance when worn. Therefore, it has been proposed to reduce the thickness of the relatively bulky absorber among the constituent members of the absorbent article.

  By making the absorbent body thinner, the absorbent article can be easily fitted to the wearer's body, and the absorbent article can be neatly accommodated in the wearer's clothes. Therefore, a feeling of wearing improves. Moreover, when the absorbent article fits in the wearer's clothes, the absorbent article becomes inconspicuous when viewed from outside the clothes. Therefore, the appearance when worn is also improved.

  However, if the absorber is thinned with the conventional structure, the absolute amount of the absorbent material is reduced. Therefore, there is a possibility that urine and body fluid cannot be sufficiently absorbed. Therefore, in order to reduce the thickness of the absorber while maintaining the amount of absorption of urine and body fluid, a method of reducing the proportion of pulp in the entire absorbent material and increasing the proportion of SAP has been considered.

  According to the said method, a bulky pulp can be reduced compared with SAP. Therefore, the absorber can be thinned. Moreover, the absorption amount of the whole absorbent material can also be maintained by increasing the ratio of SAP having a large absorption amount per unit volume. Therefore, even if the absorber is thinned, the absorption amount of the entire absorber can be maintained.

  As such a thin absorbent body, a water-absorbing composite having an increased SAP ratio has been developed by fixing (supporting) SAP to a nonwoven fabric base material using a binder such as a thermoplastic resin. (See Patent Documents 1 and 2).

Japanese Patent No. 3196933 Japanese Unexamined Patent Publication No. 2000-24033

  In the water-absorbing composite and the like, in addition to fixing the SAP to the nonwoven fabric base material and the like, in order to prevent the granular and powdery SAP from leaking to the outside of the absorbent article, the tissue or the nonwoven fabric sheet or the like It is common to encapsulate an SAP layer with a sheet material.

  However, when SAP absorbs excreta, its volume swells up to about 50 times. Therefore, the form as described above has a problem that the sheet material encapsulating the SAP layer prevents the swelling of the SAP at the time of water absorption, making it difficult to sufficiently exhibit the SAP absorption performance. This problem is expected to become more apparent as the absorber becomes thinner and the amount and ratio of SAP increase.

  The present invention has been made in view of the problems of the prior art as described above. That is, the present invention provides an SAP sheet that can exhibit sufficient absorption performance without hindering the swelling of SAP.

  As a result of intensive investigations to solve the problems of the prior art as described above, the present inventor constituted the covering sheet covering the SAP layer with a paper that is easily tearable, and the covering sheet had a predetermined density. In the wet state, a configuration that forms a fragile portion (a portion having a lower mechanical strength than other portions. For example, a penetrating portion or an embossed portion) is adopted, and when the SAP absorbs water and swells, the fragile portion starts. As a result, the present invention was completed by conceiving that the above-mentioned problems could be solved by breaking the covering sheet. Specifically, the following SAP sheet is provided by the present invention.

[1] An SAP sheet having an SAP layer containing superabsorbent polymer (SAP) particles, the supporting sheet serving as a support for the SAP layer, and a fibrous material formed on the surface of the supporting sheet An SAP receiving layer, an SAP layer formed on the surface of the SAP receiving layer, which does not contain a fibrous material and is made of an SAP particle composition containing at least the SAP particles, and covers the surface of the SAP layer And a coated sheet made of a hydrophilic material, and the SAP layer is fixed to the support sheet via the SAP receiving layer, and the SAP particles Is a plate-like layer in which the SAP particles are fixed to each other by hydrogen bonding between SAP molecules constituting the SAP particles, and the supported amount is 100 to 400 g / m ² . The cover sheet is made of paper and includes a penetration portion that is an opening that penetrates the cover sheet. The weakened portion in a wet state has a density of 900 to 100,000 pieces / m ^{2 in} the cover sheet. , SAP sheet that have been made form.

[2] The SAP sheet according to [1], wherein the paper constituting the covering sheet is tissue or absorbent paper.

[3] In the above [1] or [2], the covering sheet and the SAP layer are fixed to each other by hydrogen bonding between cellulose molecules contained in the covering sheet and SAP molecules contained in the SAP layer. The SAP sheet as described.

[4] The supporting sheet is made of paper and includes a penetrating portion that is an opening penetrating the supporting sheet. The weakened portion in a wet state is 900 to 100,000 pieces / m ^{2 in the} supporting sheet. at a density of, made form, the SAP-receiving layer is formed by pulp short fibers, by hydrogen bonding of the cellulose molecules contained in the cellulose molecule SAP-receiving layer included in the support sheet, the SAP receptor and the support sheet The SAP sheet according to any one of [1] to [3], wherein the layers are fixed to each other.

[5] The SAP sheet according to [4], wherein the paper constituting the support sheet is tissue or absorbent paper.

[6] In the above [4] or [5], the SAP receiving layer and the SAP layer are fixed to each other by hydrogen bonding between cellulose molecules contained in the SAP receiving layer and SAP molecules contained in the SAP layer. The SAP sheet as described.

[7] The SAP particle composition according to [1], wherein the SAP particle composition does not include a fibrous material, and the SAP particles account for 70 to 100% by mass of the SAP particles in the total mass of the SAP particle composition. ] The SAP sheet as described in any one of [6].

[8] The SAP sheet according to any one of [1] to [7], wherein a moisturizing agent is added to the sheet on which the fragile portion is formed and the SAP layer.

  The SAP sheet of the present invention can exhibit sufficient absorption performance without hindering SAP swelling.

It is a schematic end view which shows typically the cut end surface which cut | disconnected the SAP sheet of this invention in the thickness direction. FIG. 2 is a schematic end view illustrating a state in which the SAP sheet illustrated in FIG. 1 absorbs water and SAP particles are swollen.

  Hereinafter, the form for implementing the SAP sheet | seat of this invention is demonstrated concretely.

[1] SAP sheet:
The SAP sheet of the present invention has an SAP layer 4 containing highly water-absorbing polymer particles (SAP particles 2) like the SAP sheet 1 shown in FIG. And in the SAP sheet of this invention, the laminated body by which the support sheet 6, the SAP receiving layer 8, the SAP layer 4, and the coating sheet 10 were laminated | stacked like the SAP sheet 1 shown in FIG. The covering sheet 10 is made of paper and has a density of 900 to 100,000 pieces / m ² , and a weakened portion in the wet state (the through portion 12 in the illustrated example) is formed.

[1-1] Cover sheet:
The “covering sheet” is a hydrophilic sheet that serves as a covering material for the SAP layer. The covering sheet is placed so as to cover the surface of the SAP layer. Usually, the covering sheet is used by being disposed on the side of the surface facing the wearer's skin. A covering sheet plays the role which prevents drop-off | omission of SAP with a support sheet.

  The covering sheet is made of paper. In the present specification, “paper” means a sheet or web formed by entanglement of cellulosic fibers. Since paper is a hydrophilic material, excrement such as urine can pass through and SAP can absorb the excretion. Further, the paper on which the fragile portion is formed easily tears from the fragile portion as a starting point when the SAP swells. Therefore, swelling of SAP is hardly hindered by the covering sheet, and the SAP sheet can exhibit sufficient absorption performance.

  Examples of cellulosic fibers constituting paper include, for example, softwood and hardwood wood pulp, waste paper pulp, non-wood pulp such as hemp and cotton, chemically synthesized pulp, cellulose fibers derived from cotton, etc., rayon (regenerated cellulose fibers), Cellulosic synthetic fibers such as lyocell (purified cellulose fibers) are also included. Two or more types of cellulosic fibers or a mixed fiber of cellulosic fibers and non-cellulosic synthetic fibers (fibers such as PP and PET) can also be used.

  As described above, in order that the swelling of the SAP is not hindered by the covering sheet and the SAP sheet exhibits sufficient absorption performance, the paper constituting the covering sheet is preferably tissue or absorbent paper. Tissue and absorbent paper are superior to other papers in that they are easy to tear starting from the penetrating part. Accordingly, the SAP sheet of the present invention can be suitably used as a material for the covering sheet.

The SAP sheet of the present invention, like the SAP sheet 1 shown in FIG. 1, has at least a covering sheet 10 with a density of 900 to 100,000 pieces / m ^{2 and} a fragile portion in a wet state (in the illustrated example, a penetration portion 12). ) Is formed. In such a configuration, as shown in FIG. 2, the weakened portion (penetrating portion 12) is spread by the SAP particles 2 that have absorbed water and swollen, and the covering sheet 10 is broken. Therefore, it is possible to prevent the covering sheet 10 from preventing the SAP particles 2 from swelling. Such a configuration also contributes to the solution of the gel blocking problem described later. Even when the amount of the SAP particles 2 supported is large, the absorption performance can be increased according to the amount.

  The “fragile part in a wet state” is a part formed in the covering sheet and having a lower mechanical strength than other parts. The “wet state” refers to a state where the sheet is wet by excrement such as urine. As said weak part, a penetration part and an embossing part can be mentioned, for example. The “penetrating portion” is an opening that penetrates the sheet. For example, a tear, a slit, a hole, etc. can be mentioned. “Embossed part” means an embossing process or a similar method, which means that a part of the sheet is deformed under pressure but the paper layer is damaged by the embossing or similar method. It is preferable that the fragile portion is formed in a linear shape so that the breakage of the covering sheet easily progresses. For example, a tear or a slit is preferable. The fragile portion may be formed in advance when the sheet itself is manufactured, or may be formed afterwards when the SAP sheet is formed.

  In the case of a linear weak part, it is preferable that the length is 0.5-10 mm. By setting the thickness to 0.5 mm or more, it is possible to function as a starting point for breaking the coating sheet when the SAP swells. By making it less than 10 mm, it is possible to prevent the SAP particles from dropping through the fragile portion before the SAP absorbs water. In order to reliably obtain the effect, it is more preferable that the length of the fragile portion is 1 to 5 mm.

The fragile portion (penetrating portion 12 in the illustrated example) is the density of 900～100,000 pieces / ^{m 2,} it is formed on the cover sheet 10. By setting the density to 900 pieces / m ² or more, the covering sheet can be reliably broken. On the other hand, the intensity | strength of the coating sheet in the state before SAP particle | grains swell can be ensured by setting it as 100,000 pieces / m < ² > or less.

  In this invention, the said weak part is formed in the coating sheet. Therefore, in a dry state before use, it is preferable that the covering sheet is fixed to the SAP layer and the covering sheet and the SAP layer are integrated. By integrating the covering sheet and the SAP layer, the strength reduction of the covering sheet due to the formation of the fragile portion can be compensated.

  As a method for fixing the covering sheet to the SAP layer, adhesion with an adhesive, thermal fusion, or the like can be used. For example, the covering sheet can be fixed to the SAP layer by spraying heat-bonding fibers or heat-bonding particles between the SAP layer and the covering sheet and heating. As the heat-sealing fiber, for example, a core-sheath fiber having a lower melting point (or softening point) than the core can be used. As the core-sheath fiber, a core-sheath fiber whose core part is made of polyethylene terephthalate or polypropylene and whose sheath part is made of polyethylene is preferable.

  However, in the present invention, since the covering sheet is made of paper, it is preferable to employ a fixing method using hydrogen bonding. Specifically, it is preferable that the covering sheet and the SAP layer are fixed to each other by hydrogen bonding between the cellulose molecules contained in the covering sheet and the SAP molecules contained in the SAP layer. The fixing method using hydrogen bonding is preferable in that it does not require an adhesive or a heat-sealing fiber and can firmly fix the covering sheet and the SAP layer.

  In addition, the hydrogen bond firmly adheres the covering sheet and the SAP layer in a dry state to integrate the two, and compensates for a decrease in strength of the covering sheet due to the fragile portions (such as tears, slits, and embossed portions). However, hydrogen bonds dissociate under wet conditions where SAP swells. Therefore, there exists an advantage that the coupling | bonding of a coating sheet and a SAP layer does not prevent swelling of SAP.

  Further, in a wet state, the covering sheet and the SAP layer are separated from each other, and the strength of the covering sheet is lowered by the fragile portion. That is, when the SAP swells in a state where the covering sheet and the SAP layer are separated from each other, the fragile portion is expanded by the expansion force of the swollen SAP, and the covering sheet that restrains the SAP layer from the fragile portion is broken. The And once a fracture | rupture part is formed in a coating sheet, even when SAP swells further, a fracture | rupture part will be extended and the restraint force of the coating sheet with respect to a SAP layer will fall further. Therefore, even when the amount of SAP loaded is large, the swelling of the SAP is not hindered, and the absorbability of the SAP is hardly inhibited. Thus, the form in which the covering sheet and the SAP layer are fixed to each other by hydrogen bonding is preferable in that the effect of the present invention can be further improved.

  As described above, the cover sheet and the SAP layer are preferably fixed by hydrogen bonding. However, hydrogen bonding and bonding with an adhesive or heat fusion may be used in combination. In this case, it is preferable that the use of an adhesive, a heat-fusible fiber, or the like is kept to the minimum necessary so as not to inhibit the SAP swelling.

[1-2] Support sheet:
The “support sheet” refers to a sheet that serves as a support for the SAP layer. That is, the support sheet is a member serving as a carrier for supporting SAP particles. Usually, the SAP sheet is used by arranging the support sheet on the side facing away from the wearer's skin. The support sheet also serves as a covering material that prevents the SAP from falling off together with the covering sheet.

  The support sheet is preferably made of a flexible material. By configuring the support sheet with a flexible material, the sheet can be bent at the time of manufacturing (when embossing along a roll, etc.) or at the time of use (when deforming following the movement of the wearer). In addition, the state in which the SAP particles are fixed (supported) to the support sheet can be maintained. Examples of the flexible material include a plastic film, paper, and nonwoven fabric described later.

  Unlike the cover sheet, the support sheet does not necessarily need to be made of a hydrophilic material. For example, it may be made of a liquid impermeable material or a water repellent material. Examples of the liquid impermeable material include a plastic film. Examples of the water repellent material include nonwoven fabrics made of synthetic fibers such as polypropylene (PP) fibers and polyethylene terephthalate (PET) fibers.

  In the present specification, the “nonwoven fabric” means a sheet or web formed by bonding or entanglement of short fibers and filaments made of non-cellulosic synthetic fibers.

  However, the support sheet is preferably made of a hydrophilic material. In the said structure, it becomes possible to absorb excrement also from the surface at the side of a support sheet. Therefore, SAP can be used effectively and the absorption efficiency of the entire SAP sheet can be improved. It is also possible to use the SAP sheet by arranging the support sheet on the side of the face facing the wearer's skin.

  Examples of the hydrophilic material include hydrophilic nonwoven fabrics. For example, a non-cellulosic synthetic fiber such as polypropylene (PP) fiber or polyethylene terephthalate (PET) fiber is subjected to a hydrophilic treatment such as applying, spraying, or impregnating a surfactant, and then using a non-woven fabric. Can do.

  The manufacturing method of a nonwoven fabric is not specifically limited. The production of a nonwoven fabric consists of two steps: a step of forming a fiber fleece and a step of bonding the fleece. Therefore, a nonwoven fabric may be manufactured by appropriately selecting a fleece forming method and a fleece bonding method. Examples of the method for forming the fleece include a dry method (such as a card method and an airlaid method), a wet method, a spunbond method, and a melt blow method. Examples of the fleece bonding method include a thermal bond method, a chemical bond method, a needle punch method, a spunlace method (hydroentanglement method), and a stitch bond method. Among them, a nonwoven fabric obtained by forming a fleece by an airlaid method and fleece bonding by a thermal bond method is preferable.

The basis weight of the nonwoven fabric is preferably 10 to 100 g / m ² . The intensity | strength of a support sheet is securable by setting it as 10 g / m < ² > or more. On the other hand, the softness | flexibility and flexibility of a support sheet are securable by setting it as 100 g / m < ² > or less. In addition, the entire SAP sheet can be reduced in thickness. In order to acquire the said effect more reliably, it is still more preferable that basic weight is 20-40 g / m < ² >.

  However, the hydrophilic material is preferably paper rather than the nonwoven fabric. By configuring the support sheet with paper, the same configuration as that of the cover sheet can be applied to the support sheet. That is, a weak part in a wet state is formed on the support sheet, and the support sheet can be broken by the swollen SAP particles. According to the said structure, it is less likely that swelling of SAP is prevented by the support sheet in addition to the covering sheet. Therefore, the SAP sheet can exhibit better absorption performance.

Also in the support sheet, it is desirable to form the fragile portion at a density of 900 to 100,000 pieces / m ² . The paper constituting the support sheet is preferably tissue or absorbent paper. About the kind of cellulose fiber which comprises paper, the shape and density of a weak part (a penetration part and an embossed part), and the preferable length of a linear weak part, it is preferable to employ | adopt the structure described in the term of the coating sheet. .

[1-3] SAP receiving layer:
The “SAP receiving layer” is a layer made of a fibrous material formed on the surface of the support sheet. This layer is a layer having a function as a saucer of SAP particles. Compared with the case where the surface of the support sheet is filled with SAP particles by laminating fibrous materials (pulp short fibers, etc.) on the surface of the support sheet to form a thin layer of cotton. Is easy to fill. Therefore, the SAP particles can be stably filled, and the filling amount of the SAP particles can be increased.

  The material of the fibrous material which comprises a SAP receiving layer is not specifically limited. However, when the support sheet is made of cellulosic fibers such as paper, the fibrous material constituting the SAP receiving layer is also preferably made of cellulosic fibers.

  And it is preferable that the support sheet and the SAP receptive layer are mutually fixed by the hydrogen bond of the cellulose molecule contained in the support sheet and the cellulose molecule contained in the SAP receptive layer. Furthermore, it is particularly preferable that the SAP receiving layer and the SAP layer are fixed to each other by hydrogen bonding between cellulose molecules contained in the SAP receiving layer and SAP molecules contained in the SAP layer. The fixing method by hydrogen bonding does not require an adhesive or a heat-bonding fiber, and can firmly fix the support sheet and the SAP receiving layer, and the SAP layer and the SAP receiving layer. In addition, the hydrogen bond is dissociated under wet conditions in which SAP swells, and the bond between the support sheet and the SAP receiving layer and the bond between the SAP receiving layer and the SAP layer do not hinder the swelling of SAP.

  As the cellulosic fibers constituting the SAP receiving layer, it is preferable to use pulp short fibers derived from pulp. “Short fiber” means a fiber having a fiber length of 0.01 to 10 mm. The kind of the pulp may be any of the wood pulp, the waste paper pulp, the non-wood pulp, and the chemically synthesized pulp which have already been exemplified.

  When the support sheet is not composed of cellulosic fibers, a fixing method using hydrogen bonding cannot be employed. In that case, the SAP receiving layer is not necessarily composed of cellulosic fibers. For example, the SAP receiving layer may be composed of general thermoplastic fibers such as PP fibers and PET fibers. Moreover, you may comprise a SAP receiving layer with the thermoplastic fiber which has a core-sheath structure like the said heat-fusion fiber. When these thermoplastic fibers are used, the SAP receiving layer can be fixed to the support sheet by thermal fusion. Furthermore, a fiber having no thermoplasticity can be used as the fibrous material. In this case, the SAP receiving layer is fixed to the support sheet by a method other than heat fusion, such as using an adhesive.

  In addition to the fibrous material, the SAP receiving layer may contain a thermoplastic binder. The thermoplastic binder can bind the support sheet and the fibrous material (that is, the SAP receiving layer) or the fibrous materials to each other. The use of the thermoplastic binder is effective not only when non-cellulosic synthetic fibers are used as the fibrous material, but also when cellulosic fibers are used. The hydrogen bond can be reinforced by a thermoplastic binder. That is, the cellulosic fiber and the thermoplastic binder combine to improve the binding force between the support sheet and the SAP layer. Further, even when the support sheet is made of non-cellulosic fibers, the SAP receiving layer can be fixed to the support sheet.

  A “thermoplastic binder” is a thermoplastic substance that melts by heating and solidifies and exhibits bonding strength when the temperature decreases. For example, a hot-melt adhesive agent etc. can be mentioned. Also, a general thermoplastic resin such as PP, PET, polyethylene (PE), polyamide (PA), polyvinyl chloride (PVC) or the like, or a product obtained by processing the heat-sealing fiber into a short fiber shape, a powder shape, or the like. Can also be used. The definition of “short fiber” is synonymous with the case of pulp short fiber. Among these, high-density polyethylene fibers having a fiber length of 0.8 to 1.5 mm and a melting point of about 131 ° C. are preferable.

  The thermoplastic binder may be used in a form in which a binder layer is formed on the surface of the support sheet, and an SAP receiving layer is formed on the surface of the binder layer, or a fibrous material and a thermoplastic binder are mixed, and the mixture May be used in the form of forming an SAP receiving layer.

  In the form of forming the binder layer, the amount of the thermoplastic binder with respect to the total mass of the fibrous material is preferably 0.1 to 30 parts by mass. By setting it as 0.1 mass part or more, it becomes possible to exhibit binding force and can fix a SAP receiving layer stably. On the other hand, the flexibility fall of a SAP sheet can be suppressed by setting it as 30 mass parts or less. In order to acquire the said effect more reliably, it is still more preferable to set it as 1-15 mass parts.

  In the form in which the SAP receiving layer is formed by a mixture of the fibrous material and the thermoplastic binder, the amount of the binder is preferably increased as compared with the form in which the binder layer is formed in order to sufficiently bind the fibrous materials. Specifically, the amount of the thermoplastic binder with respect to the total mass of the fibrous material is preferably 0.1 to 50 parts by mass (preferably 1 to 50 parts by mass).

An object of the present invention is to reduce the amount of fibrous material such as pulp and to construct an absorbent article mainly composed of SAP. Therefore, it is preferable that the amount of the fibrous material constituting the SAP receiving layer is 80 g / m ² or less. Order to reliably exhibit the effects of the SAP-receiving layer, more preferably in the amount of fibrous material and 10 to 80 g / ^{m 2,} and particularly preferably to 20 to 80 g / ^{m 2.}

[1-4] SAP layer:
An “SAP layer” is a layer containing superabsorbent polymer (SAP) particles. More specifically, it is a layer that is formed on the surface of the SAP receiving layer, does not contain a fibrous material, and consists of an SAP particle composition containing at least the SAP particles.

[1-4-1] Superabsorbent polymer (SAP):
“Super Absorbent Polymer (SAP)” refers to a polymer that has the ability to absorb 20-30 times its own weight physiological saline (salt concentration: 0.9 mass%).

  As long as it is a polymer having the above properties, there is no particular limitation on the chemical structure of SAP. For example, SAP having the following structure can be given. Among the following SAPs, SAPs (1) to (4) are preferable, SAPs (1), (2) and (4) are more preferable, and SAPs (2) and (4) are particularly preferable. Note that the SAP in (15) is a biodegradable SAP. The SAP (17) is an SAP obtained by a biological technique.

(1) Starch-acrylic acid (salt) graft-crosslinked copolymer (Japanese Patent Publication No. 53-46199),
(2) Cross-linked polyacrylic acid (salt) obtained by aqueous solution polymerization (adiabatic polymerization, thin film polymerization, spray polymerization, etc.) (JP 55-133413 A),
(3) Cross-linked polyacrylic acid (salt) obtained by reverse phase suspension polymerization (Japanese Patent Publication No. Sho 54-30710),
(4) Other cross-linked polyacrylic acid (salt) (Japanese Patent Laid-Open No. 2003-057422 etc.),
(5) Saponification products of copolymers of vinyl esters and unsaturated carboxylic acids or derivatives thereof (Japanese Patent Laid-Open No. 52-14689, etc.)
(6) A copolymer of acrylic acid (salt) and a sulfo (sulfonate) group-containing monomer (Japanese Patent Laid-Open No. 58-2312 etc.),
(7) Saponified product of isobutylene-maleic anhydride copolymer crosslinked product (US Pat. No. 4,389,513 etc.),
(8) Hydrolyzate of starch-acrylonitrile copolymer (JP-A-46-43995, etc.),
(9) Cross-linked carboxymethyl cellulose (US Pat. No. 4,650,716 etc.),
(10) Cross-linked polyalkylene glycol ("Latest trend of polymer gel"<CMC Publishing Co., Ltd., published in 2004>, etc.),
(11) Cross-linked polyvinyl alcohol (the above-mentioned “Latest trend of polymer gel”, etc.),
(12) a starch radiation cross-linked product (JP-A-2003-48997, etc.),
(13) carboxyl group-containing crosslinked cellulose (JP-A-9-85080, etc.),
(14) a polyamino acid radiation cross-linked product (JP-A-10-251402, etc.),
(15) Cross-linked polyaspartic acid (JP 2002-179770 A, etc.),
(16) Polysaccharide polyvalent metal ion cross-linked product (Japanese Patent Laid-Open No. 2001-120992, etc.),
(17) Culture product from Alcaligenes Latus.

[1-4-2] SAP particles:
“SAP particles” refer to particles of a resin composition containing SAP.

  The “resin composition containing SAP” means (a) a composition composed only of SAP, and (b) a composition containing SAP as a main component and other substances to the extent that it does not adversely affect water absorption. It is a concept that includes both. Examples of the “other substances” include additives (surface modifiers added for the purpose of hydrophobizing the particle surface), unreacted monomers remaining during the synthesis of SAP, and the like.

  The mass of SAP in the mass of the entire composition is preferably 90% by mass or more. By setting it as 90 mass% or more, the water absorption which is the original characteristic of SAP can be exhibited. In order to obtain the above effect more reliably, the mass of SAP is more preferably 95% by mass or more, and particularly preferably 97% by mass or more. An upper limit is not specifically limited, The composition may be comprised only from SAP. However, it is preferable to add the surface modifier by setting the mass of SAP to 99% by mass or less.

  “Granular” includes shapes such as granular and granular. With these shapes, a uniform SAP layer can be formed when SAP particles are dispersed.

  There are no particular restrictions on the particle size or particle size distribution of the SAP particles. Absorption characteristics required for SAP can be exhibited, and those having a particle size and particle size distribution that can form a uniform SAP layer when sprayed may be appropriately selected and used. However, in the present invention, the SAP particles preferably have a mass average particle diameter of 300 to 400 μm. When the thickness is 300 μm or more, SAP particles can be easily stacked, and the yield is hardly lowered when the SAP layer is formed. In addition, the liquid permeability of the SAP layer is hardly lowered. On the other hand, by setting it as 400 micrometers or more, it can prevent the specific surface area of SAP particle | grains becoming small, and can suppress the malfunction which an absorption rate falls.

The “mass average particle diameter” in the present invention means the mass average particle diameter measured by the following sieving method.
<Mass average particle diameter>
Using the low-tap test sieve shaker and standard sieve (JIS Z8801-1: 2000), the method described in Perry's Chemical Engineers Handbook 6th Edition (McGlow Hill Book Campany, 1984, p. 21) Measure with Specifically, it is measured by the following method.
(1) Prepare JIS standard sieves with openings of 1000 μm, 850 μm, 710 μm, and 500 μm. Then, on a low-tap test sieve shaker, a sieve having an opening of 1000 μm is arranged on the uppermost stage, the sieves are arranged in order so that the opening becomes smaller downward, and a tray is arranged on the lowermost stage.
(2) 50 g of SAP particles are put in a 1000 μm sieve located at the uppermost stage, and a low-tap test sieve shaker is shaken for 5 minutes. Then, the mass of the SAP particles on each sieve and the tray is weighed.
(3) The mass fraction of the SAP particles on each sieve and the saucer in the total amount of the weighed SAP particles is determined. Then, after plotting the horizontal axis of the logarithmic probability paper as a sieve mesh and the vertical axis as the mass fraction, a line connecting the points is drawn, and the particle diameter corresponding to the mass fraction of 50% by mass is defined as the mass average particle diameter. And

  Among the SAP particles as described above, the SAP particles constituting the SAP layer include SAP (A) derived from the water-soluble vinyl monomer (a1) and the crosslinkable monomer (a2), and the SAP (A And composite SAP particles (D) obtained by complexing SAP particles (B) whose surfaces are treated with a surface modifier (C) made of a hydrophobic substance (Japanese Patent Application Laid-Open No. 2009-35657). See the official gazette).

  SAP (A) is a polymer derived from a water-soluble vinyl monomer (a1) and a crosslinkable monomer (a2) (see JP 2005-075982 A). The “water-soluble vinyl monomer (a1)” is a water-soluble monomer having a polymerizable double bond (vinyl skeleton). Here, “water-soluble” means a property of dissolving at least 100 g in 100 g of water (25 ° C.). Examples thereof include a vinyl monomer having at least one hydrophilic group selected from the group consisting of a carboxy group, a sulfo group, a phosphono group, a hydroxyl group, a carbamoyl group, an amino group, and an ammonio group (Japanese Patent Laid-Open No. 2005-2005). No. 075982). Specific examples of the compound include (meth) acrylic acid, a salt of (meth) acrylic acid, and (meth) acrylamide.

  The “water-soluble vinyl monomer (a1)” in the present specification includes a monomer that becomes a water-soluble vinyl monomer (a1) by hydrolysis. Here, “becomes water-soluble vinyl monomer (a1) by hydrolysis” means water-soluble vinyl monomer (a1) hydrolyzed by the action of water at 50 ° C. and, if necessary, a catalyst (acid or base). Means that

  Examples of the “monomer that becomes a water-soluble vinyl monomer (a1) by hydrolysis” include a vinyl monomer having at least one hydrolyzable group. Examples of the “hydrolyzable group” include a 1,3-oxo-2-oxapropylene (—CO—O—CO—) group, an acyl group, and a cyano group. Specific examples of the compound include maleic anhydride, methyl (meth) acrylate, (meth) acrylonitrile and the like.

  The “crosslinkable monomer (a2)” is a monomer having two or more reactive functional groups (see JP 2005-075982 A). Examples of the “reactive functional group” include a vinyl group, an allyl group, and a hydroxyl group. Examples include divinylbenzene, diallyl phthalate, (poly) alkylene glycol di (meth) acrylate, and the like.

  SAP (A) may have a repeating unit derived from a monomer (a3) other than the water-soluble vinyl monomer (a1) and the crosslinkable monomer (a2). For example, aromatic vinyl monomers (styrene, etc.), C2-C20 aliphatic vinyl monomer monomers (ethylene, butadiene, etc.), C5-C15 alicyclic vinyl monomers (pinene, cyclohexane, etc.) And repeating units derived from pentadiene and the like.

  In SAP (A), the mass of the repeating unit derived from the crosslinkable monomer (a2) in all repeating units is preferably 0.001 to 20% by mass. In order to surely obtain the effect, it is more preferably 0.005 to 10% by mass, and particularly preferably 0.01 to 5% by mass.

  In SAP (A), it is preferable that the mass of the repeating unit derived from the monomer (a3) in all the repeating units is 0.01 to 50% by mass. In order to surely obtain the effect, it is more preferably 0.02 to 25% by mass, and particularly preferably 0.05 to 10% by mass.

  The SAP particles (B) are made of the SAP (A) and the surfaces thereof are treated with a surface modifier (C) made of a hydrophobic substance. The “surface modifier (C)” referred to in the present specification may be any substance that can impart hydrophobicity to the surface of the SAP particles. For example, it is preferably a hydrophobic polymer, more preferably a polymer having a hydrocarbon group (polypropylene or the like), or a polymer having a polysiloxane structure (silicone or amino-modified polysiloxane or the like).

  “Treatment” means that the surface of the SAP particles (B) is coated with the surface modifier (C), or the SAP particles (B) are impregnated with the surface modifier (C). For example, the surface modifier (C) is dissolved in a solvent, emulsified / dispersed in a dispersion medium, heated and melted, and the like, and the liquid surface modifier (C) is sprayed on the SAP particles (B). Alternatively, the SAP particles (B) may be attached by a method such as dipping the liquid surface modifier (C). Spraying and dipping can be performed using an apparatus such as a Nauter mixer and a turbulizer.

  The mass of the surface modifier (C) in the composite SAP particles (D) is preferably 0.0001 to 10% by mass. By setting it to 0.0001% by mass or more, hydrophobicity can be imparted to the surface of the SAP particles, and the water permeability of the SAP layer can be ensured even if the filling amount of the SAP particles in the SAP layer is increased. By setting it as 10 mass% or less, it can prevent that the water absorption of SAP particle | grains is inhibited more than necessary. In order to surely obtain the effect, it is more preferably 0.05 to 5% by mass, and particularly preferably 0.07 to 3% by mass.

  The composite SAP particle (D) is a composite of SAP (A) and SAP particles (B) treated with the surface modifier (C).

  “Composite” means that SAP (A) and SAP particles (B) treated with the surface modifier (C) are mixed. For example, SAP (A) and SAP particles (B) treated with surface modifier (C) are mixed and kneaded to form a composite, SAP particles (B) treated with surface modifier (C) ) In the presence of a water-soluble vinyl monomer (a1) and a cross-linkable monomer (a2) to synthesize SAP (A) and combine them in a polymerization solution. Mixing and kneading can be performed using an apparatus such as a Bex mill or a rubber chopper. Compounding in the polymerization solution can be performed using an apparatus such as a homomixer or a biomixer.

  At the time of compounding, it is preferable to add 1 to 60 parts by mass of SAP (A) constituting the SAP particles (B) with respect to 100 parts by mass of SAP (A). In order to surely obtain the effect, the content is more preferably 10 to 50 parts by mass, and particularly preferably 20 to 40 parts by mass.

  In addition to having a mass average particle diameter of 300 to 400 μm, the SAP particles have a gel flow rate v calculated by the following formula (1) of 1 to 10 ml / sec and the following formula (2). SAP particles having a moisture absorption blocking ratio r of 10 to 100% are preferable.

<Gel flow rate v>
(1) 0.32 g of the SAP particles adjusted to have a mass average particle diameter of 300 to 400 μm are immersed in 150 ml of physiological saline (0.9 mass% saline) for 30 minutes to make the SAP particles hydrous gel.
(2) A cylindrical container having an inner diameter of 25.4 mm and having a filter having a diameter of 25 mm and an opening of 150 μm at the bottom is filled with the mixture of the hydrated gel and the physiological saline.
(3) The physiological saline is allowed to flow out of the filter in a state where a load of 2.1 kPa (0.3 psi) is applied to the hydrated gel through a wire mesh having a diameter of 25 mm and an opening of 150 μm.
(4) The time t (second) at which the constant amount a (ml) flows out is measured, and the gel flow rate v (flow amount per second (ml / second)) is calculated by the following equation (1).
v = a / t: (1)

  The “gel flow rate v” is an index relating to the water permeability of the SAP layer when the SAP particles absorb and swell. By using SAP particles having a gel flow rate v of 1 ml / second or more, even if the filling rate of the SAP particles in the SAP layer is increased, it is possible to fix them all with hydrogen bonds. That is, an SAP layer having a high filling rate can be formed. Fixing by hydrogen bonding is performed by watering the SAP layer and then heating. This is because by setting the gel flow rate to a predetermined value or more, the water permeability of the SAP layer is improved, and water spreads throughout the SAP layer. On the other hand, the SAP water absorption is maintained at a certain level or more by using SAP particles having a gel flow rate v of 10 ml / second or less.

<Hygroscopic blocking ratio r>
(1) To 10 g of SAP particles adjusted to a mass average particle size of 300 to 400 μm, 0.8 g of physiological saline (0.9 mass% saline) is added to absorb the SAP particles.
(2) An acrylic plate having a size of 100 mm × 100 mm and a thickness of 4 mm is placed on top of the moisture-absorbed SAP particles, and a load of 50 g is applied and left for 1 minute.
(3) Place the SAP particles after standing on a small standard JIS sieve having an opening of 1.40 mm and a diameter of 80 mm, and shake by hand 10 times.
(4) The mass W1 (g) of the SAP particles remaining on the sieve and the mass W2 (g) of the SAP particles dropped under the sieve are measured, and the moisture absorption blocking ratio r (%) is calculated by the following formula (2). To do.
r = {W1 / (W1 + W2)} × 100: (2)

  The “moisture absorption blocking rate r” is an index of the ease of aggregation (easy hydrogen bonding) during water absorption and swelling in the SAP particles. By using SAP particles having a moisture absorption blocking ratio r of 10% or more, the SAP particles can be firmly fixed to each other by hydrogen bonding. On the other hand, by using SAP particles having a moisture absorption blocking rate r of 100% or less, the SAP particles do not aggregate more than necessary, and the water permeability of the SAP layer is hardly inhibited.

[1-4-3] Composition, arrangement, etc .:
The SAP layer is formed on the surface of the SAP receiving layer. The SAP layer is fixed to the support sheet via the SAP receiving layer.

The SAP layer is a plate-like layer in which the amount of SAP particles supported is 100 to 400 g / m ² and the SAP particles are fixed to each other by hydrogen bonding between SAP molecules constituting the SAP particles. It is.

The configuration of the present invention is effective for an SAP sheet having a large amount of SAP supported as described above. This is because when the supported amount of SAP particles is 100 g / m ² or more, the swelling of the SAP is disturbed at the time of water absorption, and the absorbed amount tends to decrease. On the other hand, even if the SAP sheet having an SAP particle loading of 400 g / m ² or more adopts the configuration of the present invention, there is a possibility that the problem of reduced absorption cannot be solved sufficiently. In order to reliably obtain the effect, it is preferable that the supported amount of SAP particles is 100 to 350 g / m ² .

  The SAP layer is composed of an SAP particle composition containing no fibrous material and containing at least SAP particles.

  “SAP particle composition” is composed of both SAP particles and a mixture of SAP particles and fine cellulose fibers (microfibrillated cellulose, hereinafter abbreviated as “MFC”). It is a concept that includes The “SAP particle composition” does not include any fibrous material other than MFC (pulp, synthetic fiber, or a mixture thereof). Examples of the “pulp” include the pulp exemplified as the cellulose fiber in the section of the support sheet. Examples of the “synthetic fiber” include polyolefin (PE, PP, etc.), polyester (PET, etc.), rayon and the like.

  MFC is a short fiber obtained by finely opening cellulose fibers. And MFC exhibits a bonding force by hydrogen bonds between constituent molecules. Therefore, it has the property of reinforcing hydrogen bonds between SAP particles.

  The SAP particle composition is preferably an SAP particle composition in which the mass of SAP particles in the mass of the entire composition is 70 to 100% by mass. When the content of the SAP particles is 70% by mass or more, high absorption performance can be imparted, and a thin SAP sheet with excellent absorption performance can be configured. However, when it is desired to prevent the SAP particles from falling off using the binding force of MFC, it is preferably 70 to 90% by mass.

  In the SAP sheet of the present invention, the SAP layer is formed into a plate by bonding the SAP particles to each other by hydrogen bonding between the SAP molecules constituting the SAP particles. Such a configuration takes a structure in which SAP particles are densely arranged. Therefore, the structure is fundamentally different from that of an SAP sheet in which SAP particles are dispersed and disposed between pulp mat layers. In such a configuration, when excrement such as urine comes into contact and the SAP layer gets wet, the hydrogen bonds between the SAP particles are dissociated, and the fixed state between the SAP particles is released. That is, since the plate-like structure of the SAP layer is destroyed, gel blocking hardly occurs.

  In the SAP layer, it is preferable to break a part of hydrogen bonds between SAP molecules constituting the SAP particles in advance.

  This “breakage” means breakage of hydrogen bonds in the plate-like SAP layer formed by bonding SAP particles to each other, and does not mean breakage of the SAP layer itself. In other words, the term “breakage” as used in the present specification mainly refers to the surface direction (horizontal direction) of the SAP layer among the hydrogen bonds between the SAP particles while maintaining the state where the SAP particles are fixed to the hydrophilic sheet. ) Means that the hydrogen bond to is broken. By this “destruction”, the SAP layer is in a state in which many cracks (voids) are formed in the thickness direction (vertical direction). This void can reduce the rigidity of the SAP layer, and can impart flexibility to the rigid SAP layer. Moreover, since the space | gap which SAP swells by forming a space | gap in a SAP layer when SAP absorbs water, the problem of gel blocking is also eliminated. Therefore, it is possible to exhibit absorption performance according to the amount of SAP particles carried on the SAP layer.

  In the “breakage”, as long as most of the SAP particles are retained in the SAP layer, the state in which the SAP particles are not maintained fixed to the hydrophilic sheet or the thickness direction of the SAP layer (vertical) The state in which hydrogen bonds in the direction) are broken is also included.

[1-5] Laminate:
In the SAP sheet of the present invention, a laminate in which at least a support sheet, an SAP receiving layer, an SAP layer, and a covering sheet are laminated is configured.

  There is no restriction | limiting in particular about the thickness of this laminated body. However, it is preferably 0.5 to 5.0 mm, and more preferably 0.5 to 2.0 mm. By setting the thickness to 0.5 mm or more, the content of SAP particles can be increased, and necessary water absorption performance can be ensured. Moreover, by making it 5.0 mm or less, the amount of absorption can be large and a thin absorbent material can be comprised, and application to an absorbent article (disposable diaper etc.) becomes easy.

  In the present invention, it is preferable that moisture is added to the sheet on which the fragile portion is formed and the SAP layer. Specifically, it is preferable that 5 to 10 parts by mass of water is added to 100 parts by mass of the dry mass of the entire laminate. By setting it as 5 mass parts or more, the hydrogen bond of a SAP layer can be loosened and a SAP layer can be made flexible. On the other hand, when the amount is 10 parts by mass or less, SAP can be prevented from being yellowed due to a change with time. In order to exhibit the effect more reliably, it is preferable to add 7 to 10 parts by mass of water.

  "The sheet | seat in which the said weak part was formed" is a coating sheet at least, and when the said weak part is formed also in the support sheet, it is a coating sheet and a support sheet. In the present invention, it is preferable that a moisturizing agent is added to the sheet on which the fragile portion is formed and the SAP layer.

  The humectant has an effect of maintaining the flexibility of the SAP layer. In addition, since the moisturizing agent absorbs water faster than SAP, the moisturizing agent first absorbs water and captures water, and the water captured by the moisturizing agent can be absorbed by the SAP. Such a configuration is preferable in that even when it comes into contact with a large amount of water at one time, the water can be absorbed without missing. Furthermore, since the humectant is difficult to release water after absorbing water and has a high effect of retaining water, it is possible to impart an effect of preventing the SAP layer from being cured by drying and maintaining flexibility. . Therefore, even when applied to an absorbent article such as a disposable diaper that is in direct contact with the wearer's skin, a comfortable fit and wearing feeling can be provided.

  As the humectant, polyhydric alcohols (glycol humectants) such as ethylene glycol, glycerin, diglycerin, triglycerin, 1,3-butylene glycol and propylene glycol are preferable, and glycerin is more preferable.

  The “humectant” may be used alone or in combination of two or more. The amount of the humectant is preferably 0.01 to 10 parts by mass when the mass of the entire laminate is 100 parts by mass. By setting it as 0.01 mass part or more, the effect of the said moisturizing agent can be exhibited. On the other hand, by setting it as 10 mass parts or less, it can prevent that a moisturizing agent elutes in urine etc., and an absorber and by extension a wearer's skin become sticky. In order to exhibit the effect more reliably, it is preferable to add 0.1 to 5 parts by mass. The humectant may be marketed in the form of an aqueous solution or the like, but the amount of the humectant here means the amount of the active ingredient of the humectant.

[2] Manufacturing method:
In the SAP sheet of the present invention, for example, an SAP receiving layer is formed on a support sheet, an SAP layer is formed on the surface of the SAP receiving layer, a covering sheet is disposed on the surface of the SAP layer, and SAP particles are bonded by hydrogen bonding. And can be manufactured by a method such as forming a fragile portion (through portion, embossed portion, etc.) in the covering sheet. Hereinafter, the manufacturing method of the SAP sheet of the present invention will be described focusing on the above method.

[2-1] Formation of SAP receiving layer:
First, a fibrous material is laminated on the surface of a support sheet serving as a support for the SAP layer to form an SAP receiving layer. When short pulp fibers are used as the constituent material of the SAP receiving layer, the short pulp fibers are formed by a method such as pulverizing a pulp sheet. The pulp short fibers are laminated on a support sheet by a mat former and formed into a mat shape, whereby a SAP receiving layer having a uniform thickness can be formed relatively easily. In forming the SAP receiving layer, when forming a binder layer made of a thermoplastic binder, the SAP receiving layer may be formed after the binder is dispersed using a powder feeder or the like.

[2-2] Formation of SAP layer:
Next, an SAP particle composition containing no fibrous material and containing at least SAP particles is laminated on the surface of the SAP receiving layer to form an SAP layer having an SAP particle loading of 100 to 400 g / m ^2. To do. For example, the SAP layer is formed by spraying a predetermined amount of the SAP particle composition on the surface of the SAP receiving layer formed as described above using a powder feeder or the like.

[2-3] Formation of laminate:
Furthermore, a covering sheet serving as a covering material for the SAP layer is placed on the surface of the SAP layer to form a laminate in which the support sheet, the SAP receiving layer, the SAP layer, and the covering sheet are stacked.

  When a thermoplastic binder is used in forming the SAP receiving layer, the laminate is heated, and the thermoplastic binder is once melted and then cooled and solidified, so that the SAP receiving layer and the SAP layer are attached to the support sheet. And fix. For example, the laminated body is sucked under reduced pressure from the lower surface side of the wire on which the support sheet is placed, and in that state, the laminated body is heated using an infrared dryer, and the thermoplastic binder is melted and cooled and solidified, whereby the SAP layer is formed. Fix to the support sheet.

[2-4] Placing SAP layer:
Furthermore, after adhering water to the SAP layer, the laminate is pressed under heating, and the SAP particles are fixed to each other by hydrogen bonding between the SAP molecules constituting the SAP particles. Turn into. For example, the laminate is sprayed with water and heated and pressed with a hot-pressing roll to remove moisture and dry it to hydrogen bond SAP molecules together. Thereby, the SAP layer is formed into a plate shape. When the support sheet, the SAP receiving layer, and the covering sheet are cellulosic fibers, the SAP layer and these members and layers are also bound by hydrogen bonding.

  In place of water, for example, a humectant aqueous solution such as a glycerin aqueous solution is preferably attached because water and humectant can be attached simultaneously.

[2-5] Formation of weak part:
In the case where the weakened portion is not formed in advance on the covering sheet, the weakened portion is formed on the covering sheet (the covering sheet and the support sheet depending on the case) after performing the plate-like formation. For example, the fragile portion can be formed by treating the covering sheet by the same method as embossing. The shape and arrangement density of the fragile portions can be controlled by the shape and arrangement density of the convex pattern of the embossing roll.

  At this time, it is preferable to perform the treatment after adhering water (preferably water and a humectant) to the covering sheet and the SAP layer. By doing so, a problem that the covering sheet or the like is excessively broken is suppressed. This method is also effective when an embossed portion is formed as the fragile portion instead of the through portion. Note that the SAP layer can be destroyed at the time of forming the fragile portion.

  The SAP sheet of the present invention will be described more specifically with reference to the drawings. However, the SAP sheet of the present invention includes all SAP sheets having the invention-specific matters, and is not limited to the following examples.

[Example 1]
As shown in FIG. 1, a four-layer SAP sheet 1 in which a support sheet 6, an SAP receiving layer 8, an SAP layer 4, and a covering sheet 10 were laminated was manufactured.

[1] Formation of SAP receiving layer:
A binder layer was formed by spraying a powdery thermoplastic resin so as to have a uniform thickness on the surface of the support sheet fed onto the wire using a powder feeder. As the support sheet, a tissue having a basis weight of 14 g / m ² was used. As the thermoplastic resin, polyethylene resin powder (PE powder) and PE / PP core-sheath fiber having a fiber length of 5 mm and a fineness of 1.7 dtex were used. The PE powder was laminated at 8 g / m ² , and the core-sheath fiber was laminated at 8 g / m ² .

A SAP receiving layer was formed by laminating short pulp fibers with a mat former on the surface of the binder layer. As the short pulp fibers, pulp fibers having a fiber length of 0.05 to 5 mm (trade name: NBKP, manufactured by Oji Paper Co., Ltd.) were used. The pulp short fiber was laminated at 35 g / m ² .

[2] Formation of SAP layer:
The SAP layer was formed by spraying the SAP particle composition on the surface of the SAP receiving layer formed as described above using a powder feeder. As the SAP particles, SAP particles having a mass average particle diameter of 375 μm, a gel flow rate v of 190 ml / min, and a moisture absorption blocking rate r of 95.1% were used. As the SAP particle composition, the SAP particle was 100% by mass and did not contain MFC. This SAP particle composition was laminated so that the supported amount of SAP particles was 390 g / m ² to form an SAP layer.

[3] Formation of laminate:
A coating sheet serving as a coating material for the SAP layer was placed on the surface of the SAP layer to form a laminate in which the support sheet, the binder layer, the SAP layer, and the coating sheet were laminated. As the covering sheet, a tissue having a basis weight of 14 g / m ² was used.

  The laminated body is sucked under reduced pressure from the lower surface side of the wire on which the support sheet is placed, and in that state, the laminated body is heated using an infrared dryer, and the thermoplastic resin constituting the binder layer is melted to support the SAP receiving layer. Fixed to the sheet.

[4] Plate the SAP layer:
3 mass% glycerol aqueous solution was sprayed with respect to the said laminated body (a support sheet, a SAP layer, a covering sheet, etc.) from the support sheet side and cover sheet side of the said laminate. Subsequently, the moisture was removed and dried by heating and pressing with a heat and pressure roll, and SAP molecules were hydrogen-bonded to each other. Thereby, the SAP layer was formed into a plate shape.

[5] Formation of penetration part:
From the support sheet side and the cover sheet side of the laminate, after attaching a 3% by mass glycerin aqueous solution to the laminate (support sheet, SAP layer, cover sheet, etc.), from the cover sheet side to the laminate The embossing roll was pressed, the embossing-like process was performed to the said laminated body, and the fine penetration part was formed in the coating sheet.

The embossing pattern of the embossing roll has a density of 81632 / m ² and a staggered arrangement in which 3.5 mmφ cylindrical pins are arranged at a pitch of 3.5 mm, and a plurality of rows are arranged at a pitch of 3.5 mm. The thing of was used. After the treatment, 3.5 mmφ circular through-holes were formed at a density of 81632 / m ^{2 in} the coated sheet, and the SAP sheet of the present invention was obtained. The moisture content and glycerin adhesion amount of the laminate (SAP sheet) after the treatment were 12 parts by mass of water and 0.5 parts by mass of glycerin when the dry mass of the entire laminate was 100 parts by mass.

  The SAP sheet of the present invention can be used as an absorbent article such as a pants-type disposable diaper, a tape-type disposable diaper, a urine pad, and a sanitary product.

1: SAP sheet, 2: SAP particles, 4: SAP layer, 6: support sheet, 8: SAP receiving layer, 10: coating sheet, 12: penetration part.

Claims (8)

An SAP sheet having an SAP layer comprising superabsorbent polymer (SAP) particles,
A support sheet as a support for the SAP layer;
An SAP receiving layer made of a fibrous material, formed on the surface of the support sheet;
An SAP layer which is formed on the surface of the SAP receiving layer and does not contain a fibrous material and is composed of an SAP particle composition containing at least the SAP particles;
A laminated body in which a covering sheet made of a hydrophilic material and placed so as to cover the surface of the SAP layer is laminated,
The SAP layer is fixed to the support sheet via the SAP receiving layer, the supported amount of the SAP particles is 100 to 400 g / m ² , and hydrogen bonds between SAP molecules constituting the SAP particles The SAP particles are fixed to each other and are formed into a plate-like layer,
The cover sheet is made of paper and includes a penetration portion that is an opening that penetrates the cover sheet. The weakened portion in a wet state has a density of 900 to 100,000 pieces / m ^{2 in} the cover sheet. , SAP sheet that have been made form.   The SAP sheet according to claim 1, wherein the paper constituting the covering sheet is tissue or absorbent paper.   The SAP sheet according to claim 1 or 2, wherein the covering sheet and the SAP layer are fixed to each other by hydrogen bonding between cellulose molecules contained in the covering sheet and SAP molecules contained in the SAP layer. The supporting sheet is made of paper and includes a penetrating portion that is an opening that penetrates the supporting sheet. The weakened portion in a wet state has a density of 900 to 100,000 pieces / m ^{2 in} the supporting sheet. , made form,
The SAP receiving layer is composed of short pulp fibers,
The support sheet and the SAP receiving layer are fixed to each other by hydrogen bonding between cellulose molecules contained in the supporting sheet and cellulose molecules contained in the SAP receiving layer. SAP sheet.   The SAP sheet according to claim 4, wherein the paper constituting the support sheet is tissue or absorbent paper.   The SAP sheet according to claim 4 or 5, wherein the SAP receiving layer and the SAP layer are fixed to each other by hydrogen bonding between cellulose molecules contained in the SAP receiving layer and SAP molecules contained in the SAP layer.   The SAP particle composition according to claim 1, wherein the SAP particle composition does not contain a fibrous material, and the SAP particle composition accounts for 70 to 100% by mass of the SAP particles in the total mass of the SAP particle composition. The SAP sheet according to any one of the above.   The SAP sheet according to any one of claims 1 to 7, wherein a humectant is added to the sheet on which the fragile portion is formed and the SAP layer.

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