Particulate water-absorbent resin composition, absorbent body, and absorbent article

Abstract

A particulate water-absorbent resin composition is provided which can suppress the odor of trimethylamine in addition to the odor of acetaldehyde, in other words, which can simultaneously suppress complex odors.　In this particulate water-absorbent resin composition, which contains a hydrazide compound support and a particulate water-absorbent resin, the median particle diameter of the particulate water-absorbent resin is 100-600μm.

Description

[Technical Field]

[0001] The present invention relates to a particulate water-absorbent resin composition, an absorbent body, and an absorbent article, and more particularly to a particulate water-absorbent resin composition constituting an absorbent body suitable for use in hygiene materials such as disposable diapers, sanitary napkins, and incontinence pads, and an absorbent article using the absorbent body. [Background technology]

[0002] BACKGROUND ART In recent years, water-absorbent resins have been widely used in the field of sanitary materials such as disposable diapers, sanitary napkins, and incontinence pads.

[0003] As such a water-absorbent resin, a crosslinked product of a polymer of a water-soluble ethylenically unsaturated monomer, more specifically a crosslinked product of a polymer of a partially neutralized polyacrylic acid, has excellent water-absorbing ability, and since acrylic acid, which is the raw material thereof, is easily available industrially, it can be produced at low cost with constant quality, and is less susceptible to decay and deterioration, and therefore, it is considered to be a preferred water-absorbent resin.

[0004] On the other hand, absorbent articles such as disposable diapers, sanitary napkins, and incontinence pads are mainly composed of an absorbent core located in the center that absorbs and retains body fluids such as urine and menstrual blood excreted from the body, a liquid-permeable surface sheet (top sheet) located on the side that comes into contact with the body, and a liquid-impermeable back sheet (back sheet) located on the opposite side that comes into contact with the body. The absorbent core is usually composed of hydrophilic fibers such as pulp and a water-absorbent resin.

[0005] When such an absorbent is used in, for example, a sanitary material, the absorbent may emit unpleasant odors such as acetaldehyde after absorbing body fluids, particularly urine, blood, sweat, and the like.

[0006] As a method for suppressing such unpleasant odors, for example, a method is known in which an organic amine compound such as a hydrazide compound is added to a water-absorbent resin as an adsorbent for aldehyde compounds (see Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-323155 Summary of the Invention [Problem to be solved by the invention]

[0008] The absorbent material as described above is expected to be effective in deodorizing unpleasant odors due to trimethylamine as well as acetaldehyde. However, the inventors' investigations revealed that although hydrazide compounds are effective in suppressing the odor of acetaldehyde, they are not effective enough in suppressing the odor of trimethylamine.

[0009] A main object of the present invention is to provide a particulate water-absorbing resin composition that can suppress not only the odor of acetaldehyde but also the odor of trimethylamine, that is, that can simultaneously suppress composite odors. [Means for solving the problem]

[0010] The present inventors have conducted extensive research to solve the above problems, and as a result have found that by using a support carrying a hydrazide compound together with a particulate water-absorbent resin, it is possible to simultaneously suppress complex odors. The present invention was completed based on these findings and through further intensive research.

[0011] That is, the present invention provides the following configuration. Item 1. A particulate water-absorbing resin composition comprising a hydrazide compound carrier and a particulate water-absorbing resin, A particulate water-absorbing resin composition, wherein the particulate water-absorbing resin has a median particle diameter of 100 to 600 μm. Item 2. A particulate water-absorbing resin composition according to Item 1, wherein the particulate water-absorbing resin has a form selected from at least one of a form of primary particles that are substantially spherical, irregularly crushed, or plate-like, and a form of secondary particles formed by aggregation of the primary particles. Item 3. A particulate water-absorbing resin composition according to Item 1 or 2, wherein the hydrazide compound-supporting material is present on at least one of the surface and the interior of the particulate water-absorbing resin. Item 4. The particulate water-absorbing resin composition according to any one of Items 1 to 3, wherein the support of the hydrazide compound-supporting material is at least one of silicic acid and silicate. Item 5. The particulate water-absorbing resin composition according to any one of Items 1 to 4, wherein the content of the hydrazide compound-supporting material is 0.001 to 10% by mass. Item 6. The particulate water-absorbing resin composition according to any one of Items 1 to 5, wherein the content of the hydrazide compound in the hydrazide compound-supporting material is 0.1 to 30% by mass. Item 7. The particulate water-absorbing resin composition according to any one of Items 1 to 6, which is used to deodorize odors caused by acetaldehyde and trimethylamine. Item 8. An absorbent material comprising the particulate water-absorbing resin composition according to any one of items 1 to 7. Item 9. An absorbent article comprising the absorbent body according to item 8 held between a liquid-permeable sheet and a liquid-impermeable sheet. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a particulate water-absorbing resin composition that effectively suppresses acetaldehyde odor and trimethylamine odor. Furthermore, according to the present invention, it is also possible to provide an absorbent article and an absorbent body using the particulate water-absorbing resin composition.

[0013] It has been known that hydrazide compounds exert their effect against acetaldehyde when provided with a liquid such as water. Therefore, it is presumed that when a hydrazide compound is added to a water-absorbent resin, the water-absorbent resin absorbs the liquid, and the hydrazide compound exerts its effect against acetaldehyde. In contrast, in the particulate water-absorbent resin composition of the present invention, the hydrazide compound is contained in the particulate water-absorbent resin composition as a carrier, and the effect against acetaldehyde can be exerted even when a liquid is not provided to the particulate water-absorbent resin composition. Therefore, for example, when the particulate water-absorbent resin composition of the present invention is used in an absorbent article or absorber, the part of the particulate water-absorbent resin composition that has not absorbed water can also exert an additional effect of suppressing acetaldehyde odor and even trimethylamine odor. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1. Particulate water absorbent resin composition The particulate water-absorbent resin composition of the present invention comprises a hydrazide compound carrier and a particulate water-absorbent resin, and is characterized in that the particulate water-absorbent resin has a median particle diameter of 100 to 600 μm. By containing the hydrazide compound carrier in the particulate water-absorbent resin composition, acetaldehyde odor and trimethylamine odor can be suitably suppressed. The particulate water-absorbent resin composition of the present invention will be described in detail below.

[0015] (Hydrazide Compound Support) The hydrazide compound-supported material contained in the particulate water-absorbent resin composition of the present invention is a hydrazide compound supported on a carrier. From the viewpoint of more suitably exhibiting the effects of the present invention, the hydrazide compound is formohydrazide, acetohydrazide, propionic acid hydrazide, 4-methylbenzohydrazide, biphenyl-4-carboxylic acid hydrazide, 2-bromobenzohydrazide, 3-bromobenzohydrazide, 4-bromobenzohydrazide, 2-chlorobenzohydrazide, 3-chlorobenzohydrazide, 4-chlorobenzohydrazide, 3,4-dichlorobenzohydrazide, 2,4-dichlorobenzohydrazide, 2,4-dihydroxybenzohydrazide, 3-hydroxybenzohydrazide, 4-hydroxybenzohydrazide, isobutyric acid hydrazide, 3-methoxybenzohydrazide, 4-methoxybenzohydrazide, methylmaleic acid hydrazide, 1-naphthohydrazide, nicotinic acid hydrazide, 3-nitrobenzhydrazide, 4-nitrobenzhydrazide, Monohydrazide compounds such as 3-nitrophthalic acid hydrazide, 4-nitrophthalic acid hydrazide, n-octanohydrazide, palmitic acid hydrazide, 2-phenoxybenzohydrazide, phenylacetic acid hydrazide, 2-pyridinecarboxylic acid hydrazide, stearic acid hydrazide, 2-thiophenecarboxylic acid hydrazide, and L-tyrosine hydrazide; malonic acid dihydrazide, succinic acid dihydrazide, and adipine. Examples of the dihydrazide compounds include acid dihydrazide, carbohydrazide, isophthalic acid dihydrazide, phthalic acid dihydrazide, terephthalic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, oxalic acid dihydrazide, dodecanedioic acid dihydrazide, oxalyl dihydrazide, and adipodihydrazide; and further examples include polyhydrazide compounds having tri-, tetra-, or higher hydrazide groups. Dihydrazide compounds are preferred, and more preferred are malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, carbohydrazide, isophthalic acid dihydrazide, phthalic acid dihydrazide, terephthalic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, oxalic acid dihydrazide, dodecanedioic acid dihydrazide, oxalyl dihydrazide, and the like, and even more preferred is malonic acid dihydrazide.The hydrazide compound supported on the carrier may be of one type or two or more types.

[0016] Furthermore, from the viewpoint of more suitably exhibiting the effects of the present invention, the carrier for supporting the hydrazide compound is preferably a silicate or silicic acid, and more preferably a silicate. Furthermore, the silicate is preferably a layered silicate mineral (phyllosilicate mineral). Furthermore, the layered silicate mineral is preferably kaolin (for example, liesardite (Mg3SiO5(OH)4)), kaolinite (Al2SiO5(OH)4), berthierine (Fe 2.5 Al 0.5 )[Si 1.5 Al 0.5 O5(OH)4], mica clay minerals (e.g., fluorphlogopite (KMg3(AlSi3)O 10 F2), phlogopite (KMg3(AlSi3)O 10 (F,OH)2), polylithionite (KLi2AlSi4O 10 (F,OH)2), eastnite (KMg2Al(Al2Si2)O 10 (F,OH)2) and sucmetite (e.g., montmorillonite (Ca / 2,Na) 0.3 (Mg,Fe 2+ )3(Si,Al)4O 10 (OH)2 / 4H2O, etc.), mixed layer minerals, serpentine minerals (e.g., serpentine (Mg3Si2O5(OH)4), talc ((Mg3Si4O 10 (OH)2), chlorite (e.g., clinochlore ((Mg,Fe 2+ )5Al(Si3Al)O 10 (OH)8, chamosite ((Fe 2+ ,Mg,Fe 3+ )5Al(Si3Al)O 10 (OH)8), vermiculite, etc. The carrier for supporting the hydrazide compound may be one type or two or more types.

[0017] A preferred example of the hydrazide compound-supported material is a silicate supported by malonic acid dihydrazide (particularly, a layered silicate mineral supported by malonic acid dihydrazide). The hydrazide compound-supported material can be prepared by a known method. Alternatively, a commercially available product that meets the requirements described in the present invention can be used.

[0018] To more suitably exert the effects of the present invention, the content of the hydrazide compound in the hydrazide compound-supported carrier is preferably 0.1 to 30 mass %, more preferably 0.5 to 20 mass %, and even more preferably 1.0 to 10 mass %.

[0019] The median particle diameter of the hydrazide compound-supported carrier is preferably 0.01 to 100 μm, more preferably 0.1 to 50 μm, and even more preferably 1.0 to 10 μm. The median particle diameter of the hydrazide compound-supported carrier is a value measured according to the laser diffraction / scattering method (JIS Z8825:2013).

[0020] In the particulate water-absorbing resin composition of the present invention, the content of the hydrazide compound-supporting material is preferably 0.001 to 10 mass %, more preferably 0.01 to 5.0 mass %, and even more preferably 0.05 to 2.0 mass %.

[0021] As described below, the water-absorbent resin composition of the present invention is in a particulate form. The hydrazide compound-supported material is preferably present on at least one of the surface and the interior of the particulate water-absorbent resin, and more preferably present on the surface of the particulate water-absorbent resin. For example, by mixing the particulate water-absorbent resin and the hydrazide compound-supported material in a solid phase, the hydrazide compound-supported material can be present on the surface of the particulate water-absorbent resin. Alternatively, the particulate water-absorbent resin composition of the present invention may be prepared by mixing the hydrazide compound-supported material dissolved or dispersed in a liquid medium with the particulate water-absorbent resin. Alternatively, the hydrazide compound-supported material may be contained inside the particulate water-absorbent resin.

[0022] (Particulate water absorbent resin) The particulate water-absorbing resin contained in the particulate water-absorbing resin composition of the present invention is constituted by a crosslinked polymer of a water-soluble ethylenically unsaturated monomer, i.e., a crosslinked polymer having a structural unit derived from a water-soluble ethylenically unsaturated monomer.

[0023] The particulate water-absorbing resin has a median particle size of 100 to 600 μm, preferably 200 to 500 μm, more preferably 250 to 450 μm, and even more preferably 300 to 425 μm.

[0024] The particulate water-absorbing resin may be in a form consisting of a single particle, or in a form (secondary particles) in which fine particles (primary particles) are aggregated. Examples of the shape of the primary particles include an approximately spherical shape, an irregularly crushed shape, a plate shape, etc. In the case of primary particles produced by reverse-phase suspension polymerization, examples include approximately spherical single particle shapes having a smooth surface shape such as a perfect sphere or an oval sphere. Primary particles of such a shape have a smooth surface shape, which increases the fluidity as a powder, and the aggregated particles tend to be densely packed, which makes the water-absorbing resin less likely to be broken even when subjected to impact, resulting in a water-absorbing resin with high particle strength.

[0025] The median particle size of the particulate water-absorbent resin can be measured using a JIS standard sieve, and specifically, it is a value measured by the method described in the examples.

[0026] Typical polymerization methods for water-soluble ethylenically unsaturated monomers include aqueous solution polymerization, emulsion polymerization, and reversed-phase suspension polymerization. In aqueous solution polymerization, polymerization is carried out by heating an aqueous solution of a water-soluble ethylenically unsaturated monomer while stirring as necessary. In reversed-phase suspension polymerization, polymerization is carried out by heating a water-soluble ethylenically unsaturated monomer in a hydrocarbon dispersion medium while stirring. Reversed-phase suspension polymerization is preferably used from the viewpoint of precise control of the polymerization reaction and wide range of particle size control.

[0027] An example of a method for producing the particulate water-absorbing resin will be described below.

[0028] A specific example of the method for producing a particulate water-absorbing resin is a method for producing a particulate water-absorbing resin by reversed-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a hydrocarbon dispersion medium, which comprises a step of carrying out polymerization in the presence of a radical polymerization initiator and a step of post-crosslinking the hydrogel-like material obtained by the polymerization in the presence of a post-crosslinking agent. Note that, in the method for producing a particulate water-absorbing resin, an internal crosslinking agent may be added to the water-soluble ethylenically unsaturated monomer to form a hydrogel-like material having an internal crosslinking structure, if necessary.

[0029] <Polymerization process> [Water-soluble ethylenically unsaturated monomers] Examples of water-soluble ethylenically unsaturated monomers include (meth)acrylic acid (herein, "acrylic" and "methacrylic" are collectively referred to as "(meth)acrylic"; the same applies hereinafter) and salts thereof; 2-(meth)acrylamido-2-methylpropanesulfonic acid and salts thereof; nonionic monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, 2-hydroxyethyl(meth)acrylate, N-methylol(meth)acrylamide, and polyethylene glycol mono(meth)acrylate; and amino group-containing unsaturated monomers and quaternized products thereof such as N,N-diethylaminoethyl(meth)acrylate, N,N-diethylaminopropyl(meth)acrylate, and diethylaminopropyl(meth)acrylamide. Among these water-soluble ethylenically unsaturated monomers, (meth)acrylic acid or salts thereof, (meth)acrylamide, and N,N-dimethylacrylamide are preferred, and (meth)acrylic acid and salts thereof are more preferred, from the viewpoint of industrial availability. These water-soluble ethylenically unsaturated monomers may be used alone or in combination of two or more.

[0030] Among these, acrylic acid and its salts are widely used as raw materials for water-absorbent resins, and these acrylic acid and / or its salts may be copolymerized with the other water-soluble ethylenically unsaturated monomers described above. In this case, it is preferable that acrylic acid and / or its salts are used as the main water-soluble ethylenically unsaturated monomer in an amount of 70 to 100 mol % based on the total amount of water-soluble ethylenically unsaturated monomers.

[0031] The water-soluble ethylenically unsaturated monomer is preferably dispersed in a hydrocarbon dispersion medium in the form of an aqueous solution and subjected to reversed-phase suspension polymerization. By forming the water-soluble ethylenically unsaturated monomer into an aqueous solution, the dispersion efficiency in the hydrocarbon dispersion medium can be increased. The concentration of the water-soluble ethylenically unsaturated monomer in this aqueous solution is preferably in the range of 20% by mass to the saturated concentration. The concentration of the water-soluble ethylenically unsaturated monomer is more preferably 55% by mass or less, even more preferably 50% by mass or less, and even more preferably 45% by mass or less. Meanwhile, the concentration of the water-soluble ethylenically unsaturated monomer is more preferably 25% by mass or more, even more preferably 28% by mass or more, and even more preferably 30% by mass or more.

[0032] When the water-soluble ethylenically unsaturated monomer has an acid group, such as (meth)acrylic acid or 2-(meth)acrylamido-2-methylpropanesulfonic acid, the acid group may be neutralized in advance with an alkaline neutralizer, if necessary. Examples of such alkaline neutralizers include alkali metal salts such as sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, and potassium carbonate; and ammonia. These alkaline neutralizers may be used in the form of an aqueous solution to simplify the neutralization process. The alkaline neutralizers described above may be used alone or in combination of two or more.

[0033] The degree of neutralization of the water-soluble ethylenically unsaturated monomer with the alkaline neutralizing agent is preferably 10 to 100 mol%, more preferably 30 to 90 mol%, even more preferably 40 to 85 mol%, and even more preferably 50 to 80 mol%, in terms of the degree of neutralization of all acid groups possessed by the water-soluble ethylenically unsaturated monomer.

[0034] [Radical polymerization initiator] Examples of the radical polymerization initiator added to the polymerization step include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate, peroxides such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxypivalate, and hydrogen peroxide, as well as 2,2'-azobis(2-amidinopropane) dihydrochloride and 2,2'-azobis[2-(N-phenyl)propane]. Examples of suitable radical polymerization initiators include azo compounds such as 2,2'-azobis[2-(N-allylamidino)propane] dihydrochloride, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], and 4,4'-azobis(4-cyanovaleric acid). Among these radical polymerization initiators, potassium persulfate, ammonium persulfate, sodium persulfate, and 2,2'-azobis(2-amidinopropane) dihydrochloride are preferred due to their ease of availability and ease of handling. These radical polymerization initiators may be used alone or in combination of two or more. The radical polymerization initiator can also be used as a redox polymerization initiator in combination with a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, or L-ascorbic acid.

[0035] The amount of radical polymerization initiator used is, for example, 0.00005 to 0.01 mole per mole of the water-soluble ethylenically unsaturated monomer. By using such an amount, it is possible to avoid a rapid polymerization reaction and complete the polymerization reaction within an appropriate time.

[0036] [Internal crosslinking agent] The internal crosslinking agent can crosslink the polymer of the water-soluble ethylenically unsaturated monomer used, for example, (poly)ethylene glycol ("(poly)" refers to the agent with or without the prefix "poly"). the same applies hereinafter)], unsaturated polyesters obtained by reacting polyols such as diols and triols, such as (poly)propylene glycol, 1,4-butanediol, trimethylolpropane, and (poly)glycerin, with unsaturated acids, such as (meth)acrylic acid, maleic acid, and fumaric acid; bisacrylamides such as N,N-methylenebisacrylamide; di(meth)acrylic acid esters or tri(meth)acrylic acid esters obtained by reacting polyepoxides with (meth)acrylic acid; di(meth)acrylic acid carbamyl esters obtained by reacting polyisocyanates, such as tolylene diisocyanate and hexamethylene diisocyanate, with hydroxyethyl (meth)acrylate; allylated starch, allylated cellulose, diallyl phthalate, N,N',N''-triallyl isocyanurate, and divinylbenzene. Examples of the compound include compounds having two or more polymerizable unsaturated groups; diglycidyl compounds such as (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, and (poly)glycerin diglycidyl ether, and polyglycidyl compounds such as triglycidyl compounds; epihalohydrin compounds such as epichlorohydrin, epibromohydrin, and α-methylepichlorohydrin; compounds having two or more reactive functional groups, such as isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; and oxetane compounds such as 3-methyl-3-oxetanemethanol, 3-ethyl-3-oxetanemethanol, 3-butyl-3-oxetanemethanol, 3-methyl-3-oxetaneethanol, 3-ethyl-3-oxetaneethanol, and 3-butyl-3-oxetaneethanol. Among these internal cross-linking agents, it is preferable to use unsaturated polyesters or polyglycidyl compounds, it is more preferable to use diglycidyl ether compounds, and it is preferable to use (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, or (poly)glycerin diglycidyl ether.These internal crosslinking agents may be used alone or in combination of two or more.

[0037] The amount of the internal crosslinking agent used is preferably 0.000001 to 0.02 mol, more preferably 0.00001 to 0.01 mol, even more preferably 0.00001 to 0.005 mol, and even more preferably 0.00005 to 0.002 mol, relative to 1 mol of the water-soluble ethylenically unsaturated monomer.

[0038] [Hydrocarbon dispersion medium] Examples of hydrocarbon dispersion media include aliphatic hydrocarbons having 6 to 8 carbon atoms, such as n-hexane, n-heptane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 3-ethylpentane, and n-octane; alicyclic hydrocarbons, such as cyclohexane, methylcyclohexane, cyclopentane, methylcyclopentane, trans-1,2-dimethylcyclopentane, cis-1,3-dimethylcyclopentane, and trans-1,3-dimethylcyclopentane; and aromatic hydrocarbons, such as benzene, toluene, and xylene. Among these hydrocarbon dispersion media, n-hexane, n-heptane, and cyclohexane are particularly preferred due to their industrial availability, stable quality, and low cost. These hydrocarbon dispersion media may be used alone or in combination of two or more. Suitable results can also be obtained using a mixture of hydrocarbon dispersion media, such as commercially available Exxol Heptane (manufactured by ExxonMobil Corporation; containing 75 to 85% by mass of heptane and its isomeric hydrocarbons).

[0039] The amount of hydrocarbon dispersion medium used is preferably 100 to 1500 parts by mass, more preferably 200 to 1400 parts by mass, per 100 parts by mass of the water-soluble ethylenically unsaturated monomer in the first stage, from the viewpoints of uniformly dispersing the water-soluble ethylenically unsaturated monomer and facilitating control of the polymerization temperature. As will be described later, the reversed-phase suspension polymerization is carried out in one stage (single stage) or in multiple stages of two or more stages, and the above-mentioned first stage polymerization refers to the polymerization reaction in a single stage or a first stage in a multistage polymerization (the same applies hereinafter).

[0040] [Dispersion stabilizer] (surfactant) In the reversed-phase suspension polymerization, a dispersion stabilizer can be used to improve the dispersion stability of the water-soluble ethylenically unsaturated monomer in the hydrocarbon dispersion medium. As the dispersion stabilizer, a surfactant can be used.

[0041] Examples of surfactants that can be used include sucrose fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerin fatty acid esters, sorbitol fatty acid esters, polyoxyethylene sorbitol fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, alkylaryl formaldehyde condensed polyoxyethylene ethers, polyoxyethylene polyoxypropylene block copolymers, polyoxyethylene polyoxypropyl alkyl ethers, polyethylene glycol fatty acid esters, alkyl glucosides, N-alkyl gluconamides, polyoxyethylene fatty acid amides, polyoxyethylene alkylamines, polyoxyethylene alkyl ether phosphate esters, and polyoxyethylene alkyl allyl ether phosphate esters. Among these surfactants, sorbitan fatty acid esters, polyglycerin fatty acid esters, and sucrose fatty acid esters are particularly preferred in terms of dispersion stability of the monomer. These surfactants may be used alone or in combination of two or more.

[0042] The amount of surfactant used is preferably 0.1 to 30 parts by mass, more preferably 0.3 to 20 parts by mass, per 100 parts by mass of the first stage water-soluble ethylenically unsaturated monomer.

[0043] (polymer dispersant) As a dispersion stabilizer used in the reversed phase suspension polymerization, a polymeric dispersant may be used in combination with the surfactant described above.

[0044] Examples of polymeric dispersants include maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified ethylene-propylene copolymer, maleic anhydride-modified EPDM (ethylene-propylene-diene terpolymer), maleic anhydride-modified polybutadiene, maleic anhydride-ethylene copolymer, maleic anhydride-propylene copolymer, maleic anhydride-ethylene-propylene copolymer, maleic anhydride-butadiene copolymer, polyethylene, polypropylene, ethylene-propylene copolymer, oxidized polyethylene, oxidized polypropylene, oxidized ethylene-propylene copolymer, ethylene-acrylic acid copolymer, ethyl cellulose, and ethylhydroxyethyl cellulose. Among these polymeric dispersants, it is particularly preferable to use maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified ethylene-propylene copolymer, maleic anhydride-ethylene copolymer, maleic anhydride-propylene copolymer, maleic anhydride-ethylene-propylene copolymer, polyethylene, polypropylene, ethylene-propylene copolymer, oxidized polyethylene, oxidized polypropylene, and oxidized ethylene-propylene copolymer from the viewpoint of dispersion stability of the monomer. These polymeric dispersants may be used alone or in combination of two or more.

[0045] The amount of polymeric dispersant used is preferably 0.1 to 30 parts by mass, more preferably 0.3 to 20 parts by mass, per 100 parts by mass of the first stage water-soluble ethylenically unsaturated monomer.

[0046] [Other ingredients] In the method for producing a particulate water-absorbing resin, if desired, other components may be added to an aqueous solution containing a water-soluble ethylenically unsaturated monomer to carry out reverse phase suspension polymerization. As other components, various additives such as a thickener and a chain transfer agent can be added.

[0047] For example, a thickener can be added to an aqueous solution containing a water-soluble ethylenically unsaturated monomer to carry out reversed-phase suspension polymerization. By adjusting the viscosity of the aqueous solution by adding a thickener in this way, it is possible to control the median particle size obtained in the reversed-phase suspension polymerization.

[0048] Examples of thickeners that can be used include hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, carboxymethyl cellulose, polyacrylic acid, (partially) neutralized polyacrylic acid, polyethylene glycol, polyacrylamide, polyethyleneimine, dextrin, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, etc. If the stirring speed during polymerization is the same, the higher the viscosity of the water-soluble ethylenically unsaturated monomer aqueous solution, the larger the primary particles and / or secondary particles of the resulting particles tend to be.

[0049] [Reverse Phase Suspension Polymerization] In performing reversed-phase suspension polymerization, for example, an aqueous monomer solution containing a water-soluble ethylenically unsaturated monomer is dispersed in a hydrocarbon dispersion medium in the presence of a dispersion stabilizer. In this case, the dispersion stabilizer (surfactant or polymeric dispersant) may be added either before or after the addition of the aqueous monomer solution, as long as it is before the start of the polymerization reaction.

[0050] Among these, from the viewpoint of easily reducing the amount of hydrocarbon dispersion medium remaining in an obtained particulate water absorbent resin, it is preferable to disperse an aqueous monomer solution in a hydrocarbon dispersion medium having a polymeric dispersant dispersed therein, and then further disperse a surfactant therein, and then carry out polymerization.

[0051] Such reversed-phase suspension polymerization can be carried out in one stage or in multiple stages of two or more stages, and is preferably carried out in two to three stages from the viewpoint of increasing productivity.

[0052] When performing reversed-phase suspension polymerization in two or more stages, after performing the first-stage reversed-phase suspension polymerization, a water-soluble ethylenically unsaturated monomer is added to and mixed with the reaction mixture obtained in the first-stage polymerization reaction, and reversed-phase suspension polymerization in the second and subsequent stages can be performed in the same manner as in the first stage. In the reversed-phase suspension polymerization in each stage from the second stage onwards, it is preferable to perform the reversed-phase suspension polymerization by adding, in addition to the water-soluble ethylenically unsaturated monomer, a radical polymerization initiator within the molar ratio of each component to the water-soluble ethylenically unsaturated monomer as described above, based on the amount of water-soluble ethylenically unsaturated monomer added during the reversed-phase suspension polymerization in each stage from the second stage onwards. Note that, in the second and subsequent polymerization stages, an internal crosslinking agent may also be added to the water-soluble ethylenically unsaturated monomer, if necessary.

[0053] The reaction temperature of the polymerization reaction is preferably 20 to 110°C, and more preferably 40 to 90°C, from the viewpoints of improving economy by rapidly progressing the polymerization and shortening the polymerization time, and also of easily removing the heat of polymerization to smoothly carry out the reaction.

[0054] <Post-crosslinking process> Next, the particulate water-absorbing resin is obtained by adding a post-crosslinking agent to a hydrogel-like substance having an internal crosslinked structure obtained by polymerizing a water-soluble ethylenically unsaturated monomer to crosslink it (post-crosslinking reaction). This post-crosslinking reaction is preferably carried out in the presence of a post-crosslinking agent after the polymerization of the water-soluble ethylenically unsaturated monomer. In this way, by subjecting a hydrogel-like substance having an internal crosslinked structure to a post-crosslinking reaction after the polymerization, the crosslink density near the surface of the particulate water-absorbing resin can be increased, and a particulate water-absorbing resin with improved performance such as water absorption capacity under load can be obtained.

[0055] Examples of the post-crosslinking agent include compounds having two or more reactive functional groups. For example, polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; polyglycidyl compounds such as (poly)ethylene glycol diglycidyl ether, (poly)glycerin diglycidyl ether, (poly)glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, (poly)propylene glycol polyglycidyl ether, and (poly)glycerol polyglycidyl ether; epichlorohydrin, epibromohydrin, α-methylepichlorohydrin, isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; oxetane compounds such as 3-methyl-3-oxetanemethanol, 3-ethyl-3-oxetanemethanol, 3-butyl-3-oxetanemethanol, 3-methyl-3-oxetaneethanol, 3-ethyl-3-oxetaneethanol, and 3-butyl-3-oxetaneethanol; oxazoline compounds such as 1,2-ethylenebisoxazoline; carbonate compounds such as ethylene carbonate; and hydroxyalkylamide compounds such as bis[N,N-di(β-hydroxyethyl)]adipamide. Among these post-crosslinking agents, preferred are polyglycidyl compounds such as (poly)ethylene glycol diglycidyl ether, (poly)glycerin diglycidyl ether, (poly)glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, (poly)propylene glycol polyglycidyl ether, (poly)glycerol polyglycidyl ether, etc. These post-crosslinking agents may be used alone or in combination of two or more.

[0056] The amount of the post-crosslinking agent used is preferably 0.00001 to 0.01 mol, more preferably 0.00005 to 0.005 mol, and even more preferably 0.0001 to 0.002 mol, per mol of the total amount of water-soluble ethylenically unsaturated monomers used in the polymerization.

[0057] The post-crosslinking agent may be added as it is or as an aqueous solution, or may be added as a solution using a hydrophilic organic solvent as a solvent, if necessary. Examples of hydrophilic organic solvents include lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol; ketones such as acetone and methyl ethyl ketone; ethers such as diethyl ether, dioxane, and tetrahydrofuran; amides such as N,N-dimethylformamide; and sulfoxides such as dimethyl sulfoxide. These hydrophilic organic solvents may be used alone, in combination with two or more, or as a mixed solvent with water.

[0058] The timing of adding the post-crosslinking agent may be after the polymerization reaction of the water-soluble ethylenically unsaturated monomer has almost completely finished, and it is preferably added in the presence of water in the range of 1 to 400 parts by mass, more preferably in the range of 5 to 200 parts by mass, even more preferably in the range of 10 to 100 parts by mass, and still more preferably in the range of 20 to 60 parts by mass, relative to 100 parts by mass of the water-soluble ethylenically unsaturated monomer. Note that the amount of water means the total amount of water contained in the reaction system and water used as needed when adding the post-crosslinking agent.

[0059] The reaction temperature in the post-crosslinking reaction is preferably 50 to 250° C., more preferably 60 to 180° C., even more preferably 60 to 140° C., and even more preferably 70 to 120° C. The reaction time in the post-crosslinking reaction is preferably 1 to 300 minutes, and more preferably 5 to 200 minutes.

[0060] <Drying process> After the above-mentioned reversed-phase suspension polymerization, a drying step may be included in which water, hydrocarbon dispersion medium, etc. are removed by distillation by applying energy such as heat from the outside. When dehydrating the hydrogel after reversed-phase suspension polymerization, the system in which the hydrogel is dispersed in the hydrocarbon dispersion medium is heated, and the water and hydrocarbon dispersion medium are temporarily distilled out of the system by azeotropic distillation. In this case, if only the distilled hydrocarbon dispersion medium is returned to the system, continuous azeotropic distillation is possible. In this case, the temperature in the system during drying is maintained below the azeotropic temperature with the hydrocarbon dispersion medium, which is preferable from the viewpoint of preventing deterioration of the resin. Subsequently, water and hydrocarbon dispersion medium are distilled off to obtain water-absorbent resin particles. By controlling the processing conditions of this drying step after polymerization to adjust the amount of dehydration, it is possible to control the various properties of the obtained particulate water-absorbent resin.

[0061] In the drying step, the drying treatment by distillation may be carried out under normal pressure or under reduced pressure. Furthermore, from the viewpoint of increasing the drying efficiency, the drying treatment may be carried out under a stream of gas such as nitrogen. When the drying treatment is carried out under normal pressure, the drying temperature is preferably 70 to 250°C, more preferably 80 to 180°C, even more preferably 80 to 140°C, and even more preferably 90 to 130°C. When the drying treatment is carried out under reduced pressure, the drying temperature is preferably 40 to 160°C, and more preferably 50 to 110°C.

[0062] In addition, when a post-crosslinking step using a post-crosslinking agent is carried out after the polymerization of the monomer by reversed-phase suspension polymerization, the drying step by distillation described above is carried out after the end of the post-crosslinking step. Alternatively, the post-crosslinking step and the drying step may be carried out simultaneously.

[0063] The particulate water-absorbent resin composition of the present invention may contain additives according to the purpose in addition to the hydrazide compound carrier. Examples of such additives include inorganic powders, surfactants, oxidizing agents, reducing agents, metal chelating agents, radical chain inhibitors, antioxidants, antibacterial agents, etc. For example, the fluidity of the water-absorbent resin can be improved by adding 0.05 to 5 parts by mass of amorphous silica as inorganic powder to 100 parts by mass of the water-absorbent resin.

[0064] In the particulate water-absorbing resin composition of the present invention, the content of the particulate water-absorbing resin (excluding additives) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 98% by mass or more.

[0065] The particulate water-absorbing resin composition of the present invention is suitably used to suppress odors caused by acetaldehyde and trimethylamine.

[0066] 2. Absorbent materials and absorbent articles The particulate water-absorbing resin composition of the present invention constitutes an absorbent material used in hygiene materials such as sanitary products and disposable diapers, and is suitably used in absorbent articles containing the absorbent material.

[0067] Here, an absorbent using the particulate water-absorbent resin composition of the present invention contains the particulate water-absorbent resin composition of the present invention. The absorbent may further contain hydrophilic fibers. Examples of the configuration of the absorbent include a sheet-like structure in which a water-absorbent resin is fixed on a nonwoven fabric or between multiple nonwoven fabrics, a mixed dispersion obtained by mixing the particulate water-absorbent resin composition and hydrophilic fibers to form a uniform composition, a sandwich structure in which the particulate water-absorbent resin composition is sandwiched between layered hydrophilic fibers, and a structure in which the particulate water-absorbent resin composition and hydrophilic fibers are wrapped in tissue. The absorbent may also contain other components, such as adhesive binders such as heat-fusible synthetic fibers, hot-melt adhesives, and adhesive emulsions, to improve the shape retention of the absorbent.

[0068] The content of the water-absorbent resin in the absorbent body is preferably 5 to 100% by mass, more preferably 10 to 95% by mass, even more preferably 20 to 90% by mass, and even more preferably 30 to 80% by mass.

[0069] Examples of hydrophilic fibers include cellulose fibers such as cotton-like pulp obtained from wood, mechanical pulp, chemical pulp, and semi-chemical pulp, artificial cellulose fibers such as rayon and acetate, and fibers made of synthetic resins such as hydrophilically treated polyamide, polyester, and polyolefin. The average fiber length of the hydrophilic fibers is usually 0.1 to 10 mm, or may be 0.5 to 5 mm.

[0070] The absorbent article of the present invention can be produced by holding an absorbent body using the particulate water-absorbing resin composition of the present invention between a liquid-permeable sheet (top sheet) through which liquid can pass and a liquid-impermeable sheet (back sheet) through which liquid cannot pass. The liquid-permeable sheet is arranged on the side that comes into contact with the body, and the liquid-impermeable sheet is arranged on the opposite side that comes into contact with the body.

[0071] Examples of liquid-permeable sheets include air-through, spunbond, chemical-bond, and needle-punched nonwoven fabrics made of fibers such as polyethylene, polypropylene, and polyester, as well as porous synthetic resin sheets. Examples of liquid-impermeable sheets include synthetic resin films made of resins such as polyethylene, polypropylene, and polyvinyl chloride. The liquid-permeable sheet is preferably at least one selected from the group consisting of thermal-bonded nonwoven fabrics, air-through nonwoven fabrics, spunbonded nonwoven fabrics, and spunbonded / meltblown / spunbonded nonwoven fabrics.

[0072] The weight of the liquid-permeable sheet is 5g / m 2 More than 100g / m 2 Preferably, it is 10 g / m or less. 2 More than 60g / m 2It is more preferable that the liquid-permeable sheet has a surface embossed or perforated to improve the liquid diffusibility. The embossing or perforation can be carried out by a known method.

[0073] Examples of liquid-impermeable sheets include sheets made of synthetic resins such as polyethylene, polypropylene, and polyvinyl chloride; sheets made of nonwoven fabrics such as spunbond / meltblown / spunbond (SMS) nonwoven fabrics in which a water-resistant meltblown nonwoven fabric is sandwiched between high-strength spunbond nonwoven fabrics; and sheets made of composite materials of these synthetic resins and nonwoven fabrics (for example, spunbond nonwoven fabrics, spunlace nonwoven fabrics). A sheet made of a synthetic resin primarily composed of low-density polyethylene (LDPE) resin can also be used as the liquid-impermeable sheet. The liquid-impermeable sheet has, for example, a basis weight of 10 to 50 g / m. 2 The sheet may be made of a synthetic resin. [Example]

[0074] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0075] The particulate water-absorbing resin compositions obtained in the following Examples and Comparative Examples were evaluated by the following various tests, each of which will be described below.

[0076] <Median particle size> The measurements were carried out in an environment with a temperature of 25±2°C and a humidity of 50±10%. JIS standard sieves were arranged in the following order from top to bottom: a sieve with an opening of 850 μm, a sieve with an opening of 600 μm, a sieve with an opening of 500 μm, a sieve with an opening of 425 μm, a sieve with an opening of 300 μm, a sieve with an opening of 250 μm, a sieve with an opening of 150 μm, and a tray.

[0077] 50 g of the particulate water-absorbent resin composition was placed on the top sieve of the combination, and the composition was shaken for 10 minutes using a rotary shaker to classify it. After classification, the mass of the particulate water-absorbent resin composition remaining on each sieve was calculated as a mass percentage relative to the total amount, and the particle size distribution was determined. The particles on the sieves were integrated in descending order of particle size in this particle size distribution, and the relationship between the sieve openings and the integrated value of the mass percentage of the particulate water-absorbent resin composition remaining on the sieves was plotted on a logarithmic probability paper. The particle size corresponding to an integrated mass percentage of 50% by mass was determined as the median particle size by connecting the plots on the probability paper with a straight line.

[0078] <Test for suppression of complex odors containing acetaldehyde and trimethylamine> (Preparation of composite odor gases) In an environment of 25±2°C, 9 L of standard gas (Sumitomo Seika Chemicals Co., Ltd., nitrogen-diluted) adjusted to an acetaldehyde concentration of 19.3 ppm was sealed in a 10 L Tedlar bag, and then vaporized trimethylamine aqueous solution was added using a syringe to prepare a complex odorous gas with a trimethylamine concentration of 22 ppm inside the Tedlar bag. The concentrations of each odor component inside the Tedlar bag were measured using gas detector tubes (Gastec Corporation, detector tubes: acetaldehyde 92 L, trimethylamine 180 L). The trimethylamine concentration was calculated using the following formula using the correction value specified for the detector tube, and the acetaldehyde concentration was measured using the concentration displayed on the detector tube. (Trimethylamine concentration) = (detector tube displayed concentration) x (substance coefficient: 0.9) x (temperature coefficient: 0.7)

[0079] The complex odor suppression test was conducted in an environment of 25°C ± 2°C. 1.00 g of the particulate water-absorbent resin composition was placed in a plastic petri dish with an inner diameter of 10 cm and a height of 1.5 cm. The petri dish containing the particulate water-absorbent resin composition was placed in a 2 L Tedlar bag (with a single-mouth cap) equipped with a three-way cock via a silicone tube with an inner diameter of 5 mm, and the bag was sealed by heat sealing. Next, a glass syringe (humidity-controlled glass syringe, 200 mL, manufactured by Tsuji Manufacturing Co., Ltd.) was connected to the three-way cock, and all of the air in the Tedlar bag was extracted. Thereafter, 900 mL of the previously prepared complex odor gas was sealed into the Tedlar bag using the above-mentioned glass syringe. 60 minutes after the completion of the sealing of the complex odor gas, the three-way cock was removed from the Tedlar bag, and a gas detector tube (manufactured by Gastec Corporation, detector tube: trimethylamine: 180) with an open tip was attached to measure the trimethylamine concentration in the gas phase of the Tedlar bag. Immediately after completing the measurement of the trimethylamine concentration, the above-mentioned gas detector tube for trimethylamine was removed, and another gas detector tube with an open tip (manufactured by Gastec Corporation, detector tube: acetaldehyde: 92 L) was attached in the same manner, and the acetaldehyde concentration was measured. The trimethylamine concentration was calculated using the following formula using the correction value specified for the detector tube, and the acetaldehyde concentration was used as is as the concentration indicated on the detector tube. The measurement results are shown in Table 1. (Trimethylamine concentration) = (detector tube indicated concentration) x (substance coefficient: 0.9) x (temperature coefficient: 0.7)

[0080] <Production of particulate water-absorbent resin> (Production Example 1) A 2-L round-bottom cylindrical separable flask with an inner diameter of 11 cm and equipped with a reflux condenser, a dropping funnel, a nitrogen gas inlet, and a stirrer with a two-stage, four-paddle blade arrangement with a blade diameter of 5 cm was prepared. 293 g of n-heptane was added to the flask as a hydrocarbon dispersion medium, and 0.736 g of maleic anhydride-modified ethylene-propylene copolymer (Hiwax 1105A, Mitsui Chemicals, Inc.) was added as a polymeric dispersant. The flask was heated to 80°C with stirring to dissolve the dispersant, and then cooled to 50°C.

[0081] Separately, 92.0 g (1.03 mol) of an 80.5 mass% aqueous acrylic acid solution was placed in a 300 mL beaker as a water-soluble ethylenically unsaturated monomer, and while cooling with ice water, 147.7 g of a 20.9 mass% aqueous sodium hydroxide solution was added dropwise to neutralize the solution to 75 mol%, followed by adding and dissolving 0.092 g of hydroxyethyl cellulose (Sumitomo Seika Chemicals Co., Ltd., HECAW-15F) as a thickener, 0.0736 g (0.272 mmol) of potassium persulfate as a water-soluble radical polymerization agent, and 0.010 g (0.057 mmol) of ethylene glycol diglycidyl ether as an internal crosslinking agent to prepare a first-stage aqueous monomer solution.

[0082] The aqueous monomer solution prepared above was added to a separable flask and stirred for 10 minutes. A surfactant solution prepared by heating and dissolving 0.736 g of sucrose stearate with HLB3 (Ryoto Sugar Ester S-370, Mitsubishi Chemical Foods Corporation) as a surfactant in 6.62 g of n-heptane in a 20 mL vial was then added. The system was thoroughly purged with nitrogen while stirring at a stirrer speed of 550 rpm, and the flask was then immersed in a water bath at 70°C for 60 minutes to obtain a first-stage polymerization slurry.

[0083] Meanwhile, 128.8 g (1.43 mol) of an 80.5 mass% aqueous acrylic acid solution was placed in a separate 500 mL beaker as a water-soluble ethylenically unsaturated monomer, and while cooling with ice water, 159.0 g of a 27 mass% aqueous sodium hydroxide solution was added dropwise to carry out 75 mol% neutralization. Thereafter, 0.103 g (0.381 mmol) of potassium persulfate as a water-soluble radical polymerization initiator and 0.0116 g (0.067 mmol) of ethylene glycol diglycidyl ether as an internal crosslinking agent were added and dissolved to prepare a second-stage aqueous monomer solution.

[0084] The contents of the separable flask system were cooled to 25°C while stirring at a stirrer speed of 1000 rpm, and then the entire amount of the second-stage aqueous monomer solution was added to the first-stage polymerization slurry. The atmosphere in the system was replaced with nitrogen for 30 minutes, and the flask was again immersed in a water bath at 70°C for 60 minutes to obtain a second-stage hydrogel polymer. After the second-stage polymerization, 0.589 g of a 45% by weight aqueous solution of pentasodium diethylenetriamine pentacetate was added to the hydrogel polymer under stirring. The flask was then immersed in an oil bath set at 125°C, and 257.7 g of water was extracted from the system by azeotropic distillation of n-heptane and water while refluxing the n-heptane. 4.42 g (0.507 mmol) of a 2% by weight aqueous solution of ethylene glycol diglycidyl ether was then added to the flask as a post-crosslinking agent, and the mixture was maintained at 83°C for 2 hours.

[0085] Thereafter, n-heptane was evaporated at 125°C and dried to obtain a particulate crosslinked polymer (dried product). This particulate crosslinked polymer was passed through a sieve with an opening of 850 μm, and 0.1% by mass of amorphous silica (Oriental Silicas Corporation, Tokusil NP-S) relative to the mass of the particulate crosslinked polymer was mixed with the particulate crosslinked polymer to obtain 228.0 g of particulate water absorbent resin containing amorphous silica. The median particle diameter of this particulate water absorbent resin was 352 μm.

[0086] <Production of Particulate Water-Absorbent Resin Composition> Example 1 A particulate water-absorbent resin composition was obtained by powder-mixing 1.0 part by mass of a silicate compound carrying a hydrazide compound (Shinanen Zeomic Corporation, Dashlite M, amount of hydrazide compound carried: 7 mass%, median particle diameter: 6 μm) with 100 parts by mass of the particulate water-absorbent resin obtained in Production Example 1. After the complex odor suppression test, the acetaldehyde concentration in the gas phase was 3 ppm, and the trimethylamine concentration was less than 0.5 ppm.

[0087] Example 2 A particulate water absorbent resin composition was obtained in the same manner as in Example 1, except that the amount of the silicate compound supporting a hydrazide compound was changed to 0.5 parts by mass relative to 100 parts by mass of the particulate water absorbent resin in Example 1. After the composite odor suppression test, the acetaldehyde concentration in the gas phase was 11 ppm, and the trimethylamine concentration was 4 ppm.

[0088] (Comparative Example 1) A deodorization test was carried out using the particulate water absorbent resin obtained in Production Example 1 as the particulate water absorbent resin of Comparative Example 1. After the test for suppressing complex odors, the acetaldehyde concentration in the gas phase was 16 ppm, and the trimethylamine concentration was 10 ppm.

[0089] (Comparative Example 2) A particulate water absorbent resin composition was obtained by powder-mixing 0.07 part by mass of malonic acid dihydrazide with 100 parts by mass of the particulate water absorbent resin obtained in Production Example 1. After the composite odor suppression test, the acetaldehyde concentration in the gas phase was 13 ppm, and the trimethylamine concentration was 12 ppm.

[0090] (Comparative Example 3) A particulate water absorbent resin composition was obtained by powder-mixing 1.0 part by mass of zeolite (synthetic zeolite available as a reagent, median particle diameter 2 μm) with 100 parts by mass of the particulate water absorbent resin obtained in Production Example 1. After the composite odor suppression test, the acetaldehyde concentration in the gas phase was 16 ppm, and the trimethylamine concentration was 16 ppm.

[0091] (Reference example) For comparison, the concentrations of acetaldehyde and trimethylamine in the gas phase of a sample in which the particulate water-absorbing resin composition was not added and only the petri dish was placed in a Tedlar bag were measured. The results are shown in Table 1.

[0092] [Table 1]

Claims

1. A particulate water-absorbent resin composition comprising a hydrazide compound carrier and a particulate water-absorbent resin, the hydrazide compound carrier is present on the surface of the particulate water absorbent resin, the support of the hydrazide compound supporter is a silicate, The particulate water-absorbing resin has a median particle diameter of 100 to 600 μm, the content of the hydrazide compound-supported material is 0.001 to 2.0 mass %, A particulate water-absorbing resin composition capable of suppressing odors caused by acetaldehyde and trimethylamine.

2. 2. A particulate water-absorbing resin composition according to claim 1, wherein the particulate water-absorbing resin has a form selected from at least one of a form of primary particles that are substantially spherical, irregularly crushed, or plate-like, and a form of secondary particles formed by aggregation of the primary particles.

3. The particulate water-absorbing resin composition according to claim 1, wherein the content of the hydrazide compound carrier is 0.01 to 2.0% by mass.

4. 4. The particulate water-absorbing resin composition according to claim 1, wherein the content of the hydrazide compound in the hydrazide compound-supporting material is 0.1 to 30% by mass.

5. The particulate water-absorbing resin composition according to any one of claims 1 to 4, which is used for deodorizing odors caused by acetaldehyde and trimethylamine.

6. An absorbent material comprising the particulate water-absorbing resin composition according to any one of claims 1 to 5.

7. An absorbent article comprising the absorbent body according to claim 6 held between a liquid-permeable sheet and a liquid-impermeable sheet.

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