Particulate absorbent resin composition, absorbent, and absorbent article

Abstract

The present invention provides a particulate absorbent resin composition capable of suppressing trimethylamine odor in addition to acetaldehyde odor, that is, capable of simultaneously suppressing complex odors. The particulate absorbent resin composition comprises a hydrazide compound carrier and a particulate absorbent resin, wherein the median particle diameter of the particulate absorbent resin is 100 to 600 μm.

Description

Technology Field

[0001] The present invention relates to a particulate absorbent resin composition, an absorbent body, and an absorbent article, and more specifically, to a particulate absorbent resin composition constituting an absorbent body suitable for use in sanitary materials such as paper diapers, sanitary pads, and incontinence pads, and an absorbent article using the absorbent body. Background Technology

[0002] Absorbent resins have recently been widely used in the field of hygiene materials, such as paper diapers, sanitary pads, and incontinence pads.

[0003] As such an absorbent resin, a crosslinked polymer of a water-soluble ethylenically unsaturated monomer, more specifically, a crosslinked polymer of a polyacrylic acid partial neutralization, is considered a desirable absorbent resin because it has excellent water absorption capacity, and at the same time, since the raw material acrylic acid is easily available industrially, it has consistent quality, can be manufactured at a low cost, and is less prone to spoilage or deterioration.

[0004] Meanwhile, absorbent articles such as paper diapers, sanitary pads, and incontinence pads are composed of an absorbent material placed in the center that absorbs and retains bodily fluids such as urine and menstrual blood excreted from the body; a liquid-permeable surface sheet (top sheet) placed on the side in contact with the body; and a liquid-impermeable back sheet (back sheet) placed on the opposite side in contact with the body. In addition, the absorbent material is typically composed of hydrophilic fibers such as pulp and an absorbent resin.

[0005] When such absorbents are used, for example, in sanitary materials, unpleasant odors such as acetaldehyde may be emitted from the absorbent after absorbing body fluids, particularly urine, blood, and sweat.

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

[0007] Patent Document 1: Japanese Patent Publication No. 2001-323155 The problem to be solved

[0008] In addition to deodorizing unpleasant odors based on acetaldehyde, the absorbent material described above is also expected to deodorize unpleasant odors based on trimethylamine.

[0009] However, as a result of the inventors' review, it was found that while the hydrazide compound is effective in suppressing acetaldehyde odor, its effect in suppressing trimethylamine odor is insufficient.

[0010] The main objective of the present invention is to provide a particulate absorbent resin composition capable of suppressing trimethylamine odor in addition to acetaldehyde odor, that is, capable of simultaneously suppressing complex odors. means of solving the problem

[0011] The inventors carefully examined the above problem. As a result, they discovered that complex odors can be simultaneously suppressed by using a carrier loaded with a hydrazide compound together with a particulate absorbent resin.

[0012] Based on these findings, the present invention is an invention completed through further careful consideration.

[0013] That is, the present invention provides an invention having the following configuration.

[0014] Claim 1. A particulate absorbent resin composition comprising a hydrazide compound support and a particulate absorbent resin, wherein

[0015] A particulate absorbent resin composition having a median particle diameter of 100 to 600 μm.

[0016] Claim 2. A particulate absorbent resin composition as described in Claim 1, wherein the form of the particulate absorbent resin is selected from at least one of the form of primary particles that are approximately spherical, irregularly fragmented, or plate-like, and the form of secondary particles in which the primary particles are aggregated.

[0017] Claim 3. A particulate absorbent resin composition as described in Claim 1 or 2, wherein the hydrazide compound carrier is present on at least one of the surface and the interior of the particulate absorbent resin.

[0018] Claim 4. A particulate absorbent resin composition described in Claims 1 to 3, wherein the carrier of the hydrazide compound carrier is at least one of silicic acid and silicate.

[0019] Claim 5. A particulate absorbent resin composition as described in any one of Claims 1 to 4, wherein the content of a hydrazide compound carrier is 0.001 to 10 mass%.

[0020] Claim 6. A particulate absorbent resin composition as described in any one of Claims 1 to 5, wherein the content of the hydrazide compound in the hydrazide compound carrier is 0.1 to 30 mass%.

[0021] Claim 7. A particulate absorbent resin composition described in any one of Claims 1 to 6, used for deodorizing odors caused by acetaldehyde and trimethylamine.

[0022] Claim 8. An absorbent comprising a particulate absorbent resin composition as described in any one of Claims 1 to 7.

[0023] Claim 9. An absorbent article formed by maintaining the absorbent described in Claim 8 between a liquid-permeable sheet and a liquid-impermeable sheet. Effects of the invention

[0024] According to the present invention, a particulate absorbent resin composition that preferably suppresses acetaldehyde odor and trimethylamine odor can be provided. Furthermore, according to the present invention, an absorbent article and an absorbent body using said particulate absorbent resin composition can also be provided.

[0025] Conventionally, hydrazide compounds are known to exhibit an effect against acetaldehyde when a liquid, such as water, is provided. Therefore, it is presumed that when a hydrazide compound is added to an absorbent resin, the hydrazide compound exhibits an effect against acetaldehyde because the absorbent resin attracts the liquid. In contrast, in the absorbent resin composition of the present invention, the hydrazide compound is included in the particulate absorbent resin composition as a carrier, and thus the effect against acetaldehyde can be exhibited even without a liquid being provided to the particulate absorbent resin composition. Therefore, for example, when the particulate absorbent resin composition of the present invention is used in an absorbent article or absorbent body, an additional effect of suppressing acetaldehyde odor and furthermore trimethylamine odor can be exhibited even in the portion of the particulate absorbent resin composition that has not absorbed. Specific details for implementing the invention

[0026] 1. Particulate absorbent resin composition

[0027] The particulate absorbent resin composition of the present invention comprises a hydrazide compound carrier and a particulate absorbent resin, and is characterized in that the median particle diameter of the particulate absorbent resin is 100 to 600 μm. By including a hydrazide compound carrier in the particulate absorbent resin composition, acetaldehyde odor and trimethylamine odor can be appropriately suppressed. Below, the particulate absorbent resin composition of the present invention will be described in detail.

[0028] (Hydrazide compound carrier)

[0029] The hydrazide compound carrier included in the particulate absorbent resin composition of the present invention is one in which a hydrazide compound is supported on a carrier. In order to more appropriately exhibit the effects of the present invention, the hydrazide compounds are formhydrazide, acethydrazide, hydrazide propionic acid, 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, Monohydrazide compounds such as 4-methoxybenzhydrazide, methylmaleate hydrazide, 1-naphthohydrazide, nicotinate hydrazide, 3-nitrobenzhydrazide, 4-nitrobenzhydrazide, 3-nitrophthalate hydrazide, 4-nitrophthalate hydrazide, n-octanohydrazide, palmitate hydrazide, 2-phenoxybenzhydrazide, phenylacetic acid hydrazide, 2-pyridinecarboxylic acid hydrazide, stearate hydrazide, 2-thiophenecarboxylic acid hydrazide, L-tyrosine hydrazide; Examples of dihydrazide compounds include dihydrazide malonic acid, dihydrazide succinic acid, dihydrazide adipic acid, carbohydrazide, dihydrazide isophthalic acid, dihydrazide phthalic acid, dihydrazide terephthalic acid, dihydrazide azelaic acid, dihydrazide sebacic acid, dihydrazide oxalic acid, dihydrazide dodecanedioic acid, dihydrazide oxalyl dihydrazide, and dihydrazide adipic acid; additionally, polyhydrazide compounds having tri, tetra, and more than hydrazide groups may be included.Preferably, it is a dihydrazide compound, more preferably dihydrazide malonic acid, dihydrazide succinic acid, dihydrazide adipic acid, carbohydrazide, dihydrazide isophthalic acid, dihydrazide phthalic acid, dihydrazide terephthalic acid, dihydrazide azelaic acid, dihydrazide sebacic acid, dihydrazide oxalic acid, dihydrazide dodecanedioic acid, dihydrazide oxalyl dihydrazide, etc., and even more preferably, it is dihydrazide malonic acid. The hydrazide compound supported on the carrier may be of one type or two or more types.

[0030] In addition, the carrier supporting the hydrazide compound is preferably a silicate or silicic acid, and more preferably a silicate, in order to more appropriately exhibit the effects of the present invention. Furthermore, the silicate is preferably a layered silicate mineral (phyllosilicate mineral). In addition, as a layered silicate mineral, kaolin (e.g., lizardite (Mg3Si2O5(OH)4), kaolinite (Al2Si2O5(OH)4), burchellin (Fe 2.5 Al 0.5 )[Si 1.5 Al 0.5 [O5(OH)4] etc.), mica viscous minerals (e.g., fluorinated phlogopite (KMg3(AlSi3)O) 10 F2), Phloem (KMg3(AlSi3)O 10 (F,OH)2), polylithionite (KLi2AlSi4O 10 (F,OH)2), Istonite (KMg2Al(Al2Si2)O 10 (F,OH)2) and other fluorine-containing materials), smectite (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., clinoclor ((Mg,Fe2+ )5Al(Si3Al)O 10 (OH)8), chamosite((Fe 2+ ,Mg,Fe 3+ )5Al(Si3Al)O 10 (OH)8) etc.), vermiculite, etc. The carrier supporting the hydrazide compound may be of one type or two or more types.

[0031] Preferred specific examples of hydrazide compound supports include silicates supported with malonic acid dihydrazide (in particular, layered silicate minerals supported with malonic acid dihydrazide). Hydrazide compound supports can be prepared by known methods. In addition, commercially available products satisfying the requirements described in the present invention may be used.

[0032] In order to more appropriately exhibit the effects of the present invention, the content of the hydrazide compound in the hydrazide compound support is preferably 0.1 to 30 mass%, more preferably 0.5 to 20 mass%, and even more preferably 1.0 to 10 mass%.

[0033] In addition, the median particle diameter of the hydrazide compound support 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 support is a value measured according to the laser diffraction and scattering method (JIS Z8825: 2013).

[0034] In the particulate absorbent resin composition of the present invention, the content of the hydrazide compound carrier 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%.

[0035] As described below, the absorbent resin composition of the present invention is in the form of particles. It is preferable that the hydrazide compound carrier be present on at least one of the surface and the interior of the particulate absorbent resin, and it is more preferable that it be present on the surface of the particulate absorbent resin. For example, the hydrazide compound carrier may be present on the surface of the particulate absorbent resin composition by mixing the particulate absorbent resin and the hydrazide compound carrier in a solid state. Alternatively, the particulate absorbent resin composition of the present invention may be prepared by mixing the particulate absorbent resin with the hydrazide compound carrier in a state in which the hydrazide compound carrier is dissolved or dispersed in a liquid medium. Furthermore, the hydrazide compound carrier may be included inside the particulate absorbent resin.

[0036] (Particulate absorbent resin)

[0037] The particulate absorbent resin included in the particulate absorbent resin composition of the present invention is a cross-linked polymer of a water-soluble ethylenically unsaturated monomer, that is, a cross-linked polymer having structural units derived from a water-soluble ethylenically unsaturated monomer.

[0038] The particulate absorbent resin has an intermediate particle diameter of 100 to 600 μm, preferably 200 to 500 μm, more preferably 250 to 450 μm, and more preferably 300 to 425 μm.

[0039] In addition, particulate absorbent resins may be in the form of aggregated fine particles (primary particles) (secondary particles), in addition to each being composed of single particles. Examples of the shapes of the primary particles include approximately spherical, irregularly shaped, and plate-shaped. In the case of primary particles produced by reverse-phase suspension polymerization, examples include single particles that are approximately spherical and have a smooth surface shape such as a perfect sphere or an elliptical sphere. Primary particles of this shape have a smooth surface shape, which increases fluidity as a powder and makes it easy for aggregated particles to be densely packed, so they are resistant to destruction even when subjected to impact and become absorbent resins with high particle strength.

[0040] The median particle diameter of the particulate absorbent resin can be measured using a JIS standard sieve, and specifically, it is a value measured according to the method described in the example.

[0041] Representative polymerization methods for water-soluble ethylenically unsaturated monomers include aqueous solution polymerization, emulsion polymerization, and reverse-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 needed. In reverse-phase suspension polymerization, polymerization is carried out by heating a water-soluble ethylenically unsaturated monomer in a hydrocarbon dispersion medium under stirring. Reverse-phase suspension polymerization is preferably used from the perspective that it enables precise control of the polymerization reaction and control of a wide range of particle diameters.

[0042] Regarding particulate absorbent resins, an example of a method for manufacturing them is described below.

[0043] Specific examples of methods for manufacturing particulate absorbent resins include a method for manufacturing particulate absorbent resins by reverse-phase suspension polymerization of water-soluble ethylenically unsaturated monomers in a hydrocarbon dispersion medium, wherein the method comprises a process of polymerizing in the presence of a radical polymerization initiator and a process of post-crosslinking the hydrated gel-like material obtained from the polymerization in the presence of a post-crosslinking agent. Additionally, in the method for manufacturing particulate absorbent resins, if necessary, an internal crosslinking agent may be added to the water-soluble ethylenically unsaturated monomers to form a hydrated gel-like material having an internal crosslinking structure.

[0044] Polymerization Process

[0045] [Water-soluble ethylenically unsaturated monomer]

[0046] Examples of water-soluble ethylenically unsaturated monomers include (meth)acrylic acid (in this specification, "acryl" and "methacryl" are combined and denoted as "(meth)acryl"; hereinafter the same applies) and its salts; 2-(meth)acrylamide-2-methylpropanesulfonic acid and its salts; nonionic monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, 2-hydroxyethyl(meth)acrylate, N-methylol(meth)acrylamide, polyethylene glycol mono(meth)acrylate; amino group-containing unsaturated monomers such as N,N-diethylaminoethyl(meth)acrylate, N,N-diethylaminopropyl(meth)acrylate, diethylaminopropyl(meth)acrylamide, and their quaternary compounds. Among these water-soluble ethylenically unsaturated monomers, (meth)acrylic acid or its salt, (meth)acrylamide, and N,N-dimethylacrylamide are preferred from the perspective of ease of industrial availability, and (meth)acrylic acid and its salt are more preferred. In addition, these water-soluble ethylenically unsaturated monomers may be used alone or in combination of two or more types.

[0047] Among these, acrylic acid and its salts are widely used as raw materials for absorbent resins, and there are also cases where other water-soluble ethylenically unsaturated monomers described above are copolymerized with such acrylic acid and / or its salts and used. In this case, acrylic acid and / or its salts are preferably used as the main water-soluble ethylenically unsaturated monomers in an amount of 70 to 100 mol% relative to the total water-soluble ethylenically unsaturated monomers.

[0048] It is preferable that the water-soluble ethylenically unsaturated monomer be dispersed in a hydrocarbon dispersion medium in an aqueous solution state and provided for reverse-phase suspension polymerization. By making the water-soluble ethylenically unsaturated monomer an aqueous solution, the dispersion efficiency in the hydrocarbon dispersion medium can be increased. The concentration of the water-soluble ethylenically unsaturated monomer in such an aqueous solution is preferably in the range of 20 mass% to or less than the saturation concentration. Furthermore, it is more preferable that the concentration of the water-soluble ethylenically unsaturated monomer is 55 mass% or less, more preferable that it is 50 mass% or less, and more preferable that it is 45 mass% or less. On the other hand, it is more preferable that the concentration of the water-soluble ethylenically unsaturated monomer is 25 mass% or more, more preferable that it is 28 mass% or more, and more preferable that it is 30 mass% or more.

[0049] In cases where a water-soluble ethylenically unsaturated monomer has an acid group, such as (meth)acrylic acid or 2-(meth)acrylamide-2-methylpropanesulfonic acid, the acid group may be pre-neutralized by an alkaline neutralizing agent as needed. Examples of such alkaline neutralizing agents include alkali metal salts such as sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, and potassium carbonate; and ammonia. Furthermore, such alkaline neutralizing agents may be used in the form of an aqueous solution to simplify the neutralization operation. Additionally, the aforementioned alkaline neutralizing agents may be used alone or in combination of two or more types.

[0050] As for the degree of neutralization of a water-soluble ethylenically unsaturated monomer by an alkaline neutralizing agent, as the degree of neutralization for all acid groups of the water-soluble ethylenically unsaturated monomer, it is preferably 10 to 100 mol%, more preferably 30 to 90 mol%, more preferably 40 to 85 mol%, and more preferably 50 to 80 mol%.

[0051] [Radical Polymerization Initiator]

[0052] As radical polymerization initiators added to the polymerization process, for example, 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-butyl cumyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisobutylate, t-butyl peroxypivalate, and hydrogen peroxide; and 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(N-phenylamidino)propane]dihydrochloride, and 2,2'-azobis[2-(N-allylamidino)propane]dihydrochloride. Examples of azo compounds include 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazoline-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-cyanogielacetic acid). Among these radical polymerization initiators, potassium persulfate, ammonium persulfate, sodium persulfate, and 2,2'-azobis(2-amidinopropane)dihydrochloride are preferably used from the perspective of being easy to obtain and easy to handle. These radical polymerization initiators may be used alone or in combination of two or more types. In addition, the above radical polymerization initiator may also be used as an oxidation-reduction polymerization initiator in combination with reducing agents such as sodium sulfite, sodium bisulfite, ferrous sulfate, and L-ascorbic acid.

[0053] As for the amount of radical polymerization initiator used, for example, 0.00005 to 0.01 mole per 1 mole of water-soluble ethylenically unsaturated monomer can be used. By satisfying this amount, rapid polymerization reactions can be avoided, and the polymerization reaction can also be completed within an appropriate time.

[0054] [Internal crosslinking agent]

[0055] Examples of internal crosslinking agents include those capable of crosslinking the polymer of the water-soluble ethylenically unsaturated monomer used, such as (poly)ethylene glycol [(poly) refers to cases with and without the prefix "poly". The same applies hereinafter], (poly)propylene glycol, 1,4-butanediol, trimethylolpropane, (poly)glycerin, etc., polyols such as diols and triols, and unsaturated polyesters obtained by reacting them with unsaturated acids such as (meth)acrylic acid, maleic acid, and fumaric acid; bisacrylamides such as N,N-methylenebisacrylamide; and 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 (meth)acrylic acid hydroxyethyl; Compounds having two or more polymerizable unsaturated groups, such as allylated starch, allylated cellulose, diallyl phthalate, N,N',N"-triallyl isocyanurate, and divinylbenzene; polyglycidyl compounds, such as diglycidyl compounds like (poly)ethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, and (poly)glycerin diglycidyl ether, and triglycidyl compounds; epihalohydrin compounds such as epichlorohydrin, epibromohydrin, and α-methyl epichlorohydrin; compounds having two or more reactive functional groups, such as isocyanate compounds like 2,4-tolylene diisocyanate and hexamethylene diisocyanate; 3-methyl-3-oxetanemethanol, 3-ethyl-3-oxetanemethanol, and 3-butyl-3-oxetanemethanol, Examples include oxetane compounds such as 3-methyl-3-oxetaneethanol, 3-ethyl-3-oxetaneethanol, and 3-butyl-3-oxetaneethanol.Among these internal crosslinking agents, it is preferable to use unsaturated polyesters or polyglycidyl compounds, more preferable to use diglycidyl ether compounds, and more 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 types.

[0056] As for the amount of internal crosslinking agent used, it is preferable to have 0.000001 to 0.02 moles per 1 mole of water-soluble ethylenically unsaturated monomer, more preferable to have 0.00001 to 0.01 moles, more preferable to have 0.00001 to 0.005 moles, and more preferable to have 0.00005 to 0.002 moles.

[0057] [Hydrocarbon dispersion medium]

[0058] 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 suitable for use because they are industrially readily available, have stable quality, and are inexpensive. These hydrocarbon dispersion media may be used individually or in combination of two or more types. In addition, as an example of a mixture of hydrocarbon dispersion media, commercial products such as exolheptane (manufactured by ExxonMobil; containing 75 to 85 mass% of hydrocarbons of heptane and its isomers) can be used to obtain suitable results.

[0059] Regarding the amount of hydrocarbon dispersion medium used, from the perspective of uniformly dispersing the water-soluble ethylenically unsaturated monomer and facilitating the control of the polymerization temperature, it is preferable to use 100 to 1500 parts by mass and more preferable to use 200 to 1400 parts by mass for 100 parts by mass of the water-soluble ethylenically unsaturated monomer in the first stage. Furthermore, as described below, reverse-phase suspension polymerization is carried out in one stage (single stage) or in two or more stages, and the polymerization in the first stage mentioned above refers to the polymerization reaction in the first stage of single-stage polymerization or multi-stage polymerization (the same applies hereinafter).

[0060] [Dispersion Stabilizer]

[0061] (Surfactant)

[0062] In reverse-phase suspension polymerization, a dispersion stabilizer may be used to improve the dispersion stability of a water-soluble ethylenically unsaturated monomer in a hydrocarbon dispersion medium. Surfactants may be used as such dispersion stabilizers.

[0063] As surfactants, for example, 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 hardened castor oil, alkylallyl formaldehyde condensed polyoxyethylene ethers, polyoxyethylene polyoxypropylene block copolymers, polyoxyethylene polyoxypropyl alkyl ethers, polyethylene glycol fatty acid esters, alkyl glucosides, N-alkylgluconamides, polyoxyethylene fatty acid amides, polyoxyethylene alkylamines, phosphate esters of polyoxyethylene alkyl ethers, phosphate esters of polyoxyethylene alkylaryl ethers, etc. Among these surfactants, it is particularly preferable to use sorbitan fatty acid esters, polyglycerin fatty acid esters, and sucrose fatty acid esters in terms of monomer dispersion stability. These surfactants may be used alone or in combination of two or more types.

[0064] As for the amount of surfactant used, it is preferably 0.1 to 30 parts by mass and more preferably 0.3 to 20 parts by mass with respect to 100 parts by mass of the water-soluble ethylenically unsaturated monomer of the first step.

[0065] (Polymer-based dispersant)

[0066] In addition, as a dispersion stabilizer used in reverse-phase suspension polymerization, a polymer-based dispersant may be used in combination with the aforementioned surfactant.

[0067] Examples of polymer-based dispersants include maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified ethylene-propylene copolymer, maleic anhydride-modified EPDM (ethylene-propylene-diene monomer), 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, ethylcellulose, ethylhydroxyethylcellulose, etc. Among these polymer-based dispersants, in particular, in terms of monomer dispersion stability, it is 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. These polymer-based dispersants may be used alone or in combination of two or more types.

[0068] As for the amount of polymeric dispersant used, it is preferable to use 0.1 to 30 parts by mass with respect to 100 parts by mass of the water-soluble ethylenically unsaturated monomer of the first step, and more preferable to use 0.3 to 20 parts by mass.

[0069] [Other ingredients]

[0070] In a method for manufacturing particulate absorbent resin, other components may optionally 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 thickeners and chain transfer agents may be added.

[0071] As an example, reverse-phase suspension polymerization can be carried out by adding a thickening agent to an aqueous solution containing a water-soluble ethylenically unsaturated monomer. By adjusting the viscosity of the aqueous solution by adding a thickening agent in this way, it is possible to control the intermediate particle diameter obtained in reverse-phase suspension polymerization.

[0072] As a thickening agent, for example, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, carboxymethylcellulose, polyacrylic acid, polyacrylic acid (partial) neutralized product, polyethylene glycol, polyacrylamide, polyethyleneimine, dextrin, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, etc., may be used. In addition, if the stirring speed during polymerization is the same, the higher the viscosity of the aqueous solution of the water-soluble ethylenically unsaturated monomer, the larger the primary particles and / or secondary particles of the obtained particles tend to be.

[0073] [Reverse Phase Suspension Polymerization]

[0074] In carrying out reverse-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. At this time, if the polymerization reaction has not yet started, the timing of adding the dispersion stabilizer (surfactant or polymer-based dispersant) does not matter, whether before or after adding the aqueous monomer solution.

[0075] In particular, from the perspective of easily reducing the amount of residual hydrocarbon dispersion medium in the obtained particulate absorbent resin, it is preferable to disperse an aqueous monomer solution in a hydrocarbon dispersion medium in which a polymeric dispersant is dispersed, and then further disperse a surfactant before carrying out polymerization.

[0076] This reverse-phase suspension polymerization can be carried out in one step or in multiple steps of two or more. In addition, it is desirable to carry out the process in two to three steps to increase productivity.

[0077] When performing reverse-phase suspension polymerization in two or more stages, after performing the reverse-phase suspension polymerization in the first stage, a water-soluble ethylenically unsaturated monomer is added to the reaction mixture obtained from the polymerization reaction in the first stage and mixed, and the reverse-phase suspension polymerization in the second stage and subsequent stages is performed in the same manner as in the first stage. In the reverse-phase suspension polymerization in each stage from the second stage onwards, in addition to the water-soluble ethylenically unsaturated monomer, it is preferable to perform the reverse-phase suspension polymerization by adding a radical polymerization initiator within the range of the molar ratio of each component to the aforementioned water-soluble ethylenically unsaturated monomer, based on the amount of water-soluble ethylenically unsaturated monomer added during the reverse-phase suspension polymerization in each stage from the second stage onwards. Furthermore, in the polymerization in the second stage and subsequent stages, an internal crosslinking agent may be added to the water-soluble ethylenically unsaturated monomer if necessary.

[0078] As for the reaction temperature of the polymerization reaction, it is preferable to have a temperature of 20 to 110°C, and more preferable to have a temperature of 40 to 90°C, from the perspective of increasing economic efficiency by rapidly proceeding with the polymerization and shortening the polymerization time, and easily removing the heat of polymerization to facilitate the reaction.

[0079] Post-crosslinking process

[0080] Next, the particulate absorbent resin can be obtained by adding a post-crosslinking agent to a water-soluble ethylenically unsaturated monomer and crosslinking it (post-crosslinking reaction) to a water-soluble gel-like material having an internal crosslinking structure obtained by polymerizing the water-soluble ethylenically unsaturated monomer. It is preferable to carry out this post-crosslinking reaction in the presence of a post-crosslinking agent after the polymerization of the water-soluble ethylenically unsaturated monomer. In this way, by carrying out a post-crosslinking reaction on a water-soluble gel-like material having an internal crosslinking structure after polymerization, the crosslinking density near the surface of the particulate absorbent resin is increased, thereby obtaining a particulate absorbent resin with improved overall performance, such as absorption capacity under load.

[0081] Examples of post-crosslinking agents include compounds having two or more reactive functional groups. For instance, 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; haloepoxy compounds such as epichlorohydrin, epibromohydrin, and α-methyl epichlorohydrin; and isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate. Examples include 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, 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 are preferred. These post-crosslinking agents may be used alone or in combination of two or more types.

[0082] As for the amount of post-crosslinking agent used, it is preferable to have 0.00001 to 0.01 moles per 1 mole of the total amount of water-soluble ethylenically unsaturated monomer used in polymerization, more preferable to have 0.00005 to 0.005 moles, and even more preferable to have 0.0001 to 0.002 moles.

[0083] Regarding the method of adding a post-crosslinking agent, the post-crosslinking agent may be added as is or as an aqueous solution, but if necessary, it may also be added as a solution using a hydrophilic organic solvent as a solvent. 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 of two or more types, or as a mixed solvent with water.

[0084] The timing for adding the post-crosslinking agent is when the polymerization reaction of the water-soluble ethylenically unsaturated monomer is almost complete. It is preferable to add it in the presence of moisture in the range of 1 to 400 parts by mass per 100 parts by mass of the water-soluble ethylenically unsaturated monomer, more preferable to add it in the presence of moisture in the range of 5 to 200 parts by mass, more preferable to add it in the presence of moisture in the range of 10 to 100 parts by mass, and even more preferable to add it in the presence of moisture in the range of 20 to 60 parts by mass. In addition, the amount of moisture refers to the total amount of moisture included in the reaction system and moisture used as needed when adding the post-crosslinking agent.

[0085] As for the reaction temperature in the post-crosslinking reaction, it is preferably 50 to 250°C, more preferably 60 to 180°C, more preferably 60 to 140°C, and more preferably 70 to 120°C. In addition, as for the reaction time of the post-crosslinking reaction, it is preferably 1 to 300 minutes, and more preferably 5 to 200 minutes.

[0086] Drying Process

[0087] After performing the aforementioned reverse-phase suspension polymerization, a drying process may be included to remove water, hydrocarbon dispersion medium, etc., by distillation through the application of external energy, such as heat. When dehydrating the aqueous gel after reverse-phase suspension polymerization, the system in which the aqueous gel is dispersed in the hydrocarbon dispersion medium is heated to remove water and the hydrocarbon dispersion medium by distillation to the outside of the system. At this time, if only the hydrocarbon dispersion medium removed by distillation is returned to the inside of the system, continuous azeotropic distillation becomes possible. In this case, since the temperature inside the system during drying is maintained below the azeotropic temperature with the hydrocarbon dispersion medium, it is desirable from the perspective that the resin is less likely to deteriorate. Subsequently, particles of the absorbent resin can be obtained by distilling off the water and the hydrocarbon dispersion medium. By controlling the processing conditions of the drying process after such polymerization and adjusting the amount of dehydration, it is possible to control the overall performance of the obtained particulate absorbent resin.

[0088] In the drying process, the drying treatment by distillation may be carried out under atmospheric pressure or under reduced pressure. Additionally, from the perspective of increasing drying efficiency, it may be carried out under an air stream such as nitrogen. When the drying treatment is carried out under atmospheric pressure, the drying temperature is preferably 70 to 250°C, more preferably 80 to 180°C, more preferably 80 to 140°C, and more preferably 90 to 130°C. Furthermore, 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.

[0089] In addition, if a post-crosslinking process using a post-crosslinking agent is performed after polymerizing the monomer by reverse-phase suspension polymerization, the drying process by distillation described above is performed after the completion of the post-crosslinking process. Alternatively, the post-crosslinking process and the drying process may be performed simultaneously.

[0090] The particulate absorbent resin composition of the present invention may include additives according to the purpose in addition to the hydrazide compound carrier above. 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 absorbent resin can be improved by adding 0.05 to 5 parts by mass of amorphous silica as an inorganic powder per 100 parts by mass of the absorbent resin.

[0091] In addition, in the particulate absorbent resin composition of the present invention, the content of the particulate absorbent resin (excluding additives) is preferably 80 mass% or more, more preferably 90 mass% or more, and even more preferably 98 mass% or more.

[0092] The particulate absorbent resin composition of the present invention is suitable for use in suppressing odors caused by acetaldehyde and trimethylamine.

[0093] 2. Absorbent material, absorbent article

[0094] The particulate absorbent resin composition of the present invention constitutes an absorbent body used in sanitary materials, such as sanitary products and paper diapers, for example, and is suitably used in absorbent articles containing said absorbent body.

[0095] Here, the absorbent using the particulate absorbent resin composition of the present invention comprises the particulate absorbent resin composition of the present invention. The absorbent may further comprise hydrophilic fibers. Examples of the composition of the absorbent include a sheet-like structure in which the absorbent resin is fixed on a nonwoven fabric or between multiple nonwoven fabrics, a mixed dispersion obtained by mixing the particulate absorbent resin composition and hydrophilic fibers to obtain a uniform composition, a sandwich structure in which the particulate absorbent resin composition is sandwiched between layered hydrophilic fibers, and a structure in which the particulate absorbent resin composition and hydrophilic fibers are wrapped in tissue. In addition, the absorbent may be formulated with a separate component, for example, an adhesive binder such as a heat-sealable synthetic fiber, a hot-melt adhesive, or an adhesive emulsion to enhance the shape retention of the absorbent.

[0096] The content of the absorbent resin in the absorbent body is preferably 5 to 100 mass%, more preferably 10 to 95 mass%, more preferably 20 to 90 mass%, and more preferably 30 to 80 mass%.

[0097] Examples of hydrophilic fibers include cellulose fibers such as cotton pulp, mechanical pulp, chemical pulp, and semi-chemical pulp obtained from wood, artificial cellulose fibers such as rayon and acetate, and fibers made of synthetic resins such as hydrophilized polyamide, polyester, and polyolefin. The average fiber length of hydrophilic fibers is typically 0.1 to 10 mm, or 0.5 to 5 mm.

[0098] An absorbent body using the particulate absorbent resin composition of the present invention can be made into an absorbent article of the present invention by maintaining it 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 positioned on the side in contact with the body, and the liquid-impermeable sheet is positioned on the opposite side from the body.

[0099] Examples of liquid-permeable sheets include nonwoven fabrics such as air-through, spunbonded, chemical bond, and needle-punched types made of fibers such as polyethylene, polypropylene, and polyester, as well as porous synthetic resin sheets. Additionally, examples of liquid-impermeable sheets include synthetic resin films made of resins such as polyethylene, polypropylene, and polyvinyl chloride. It is preferable that the liquid-permeable sheet be at least one type selected from the group consisting of thermal bond nonwoven fabric, air-through nonwoven fabric, spunbond nonwoven fabric, and spunbond / meltblown / spunbond nonwoven fabric.

[0100] The mass per unit area of ​​the liquid-permeable sheet is 5 g / m² 2 100g / m² or more 2 It is preferable that it be less than or equal to 10 g / m² 2 60g / m² or more 2 It is more preferable that it be as follows. In addition, the liquid permeable sheet may have embossing or perforation processes performed on its surface to improve the diffusion of the liquid. The embossing or perforation processes may be performed using known methods.

[0101] 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 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 (e.g., spunbond nonwoven fabric, spunlace nonwoven fabric). As a liquid-impermeable sheet, a sheet made of a synthetic resin mainly composed of low-density polyethylene (LDPE) resin may also be used. The liquid-impermeable sheet has, for example, a mass per unit area of ​​10 to 50 g / m² 2 It may be a sheet made of synthetic resin.

[0102] Examples

[0103] The present invention will be described in detail below by presenting examples and comparative examples. However, the present invention is not limited to the examples.

[0104] In addition, the particulate absorbent resin compositions obtained in the following examples and comparative examples were evaluated in the various tests below. The methods for each evaluation test are described below.

[0105] <Median Particle Diameter>

[0106] Measurements were performed under conditions of a temperature of 25±2℃ and a humidity of 50±10%. The JIS standard sieves were assembled in the order from top to bottom: a sieve with a mesh size of 850μm, a sieve with a mesh size of 600μm, a sieve with a mesh size of 500μm, a sieve with a mesh size of 425μm, a sieve with a mesh size of 300μm, a sieve with a mesh size of 250μm, a sieve with a mesh size of 150μm, and a tray.

[0107] 50g of particulate absorbent resin composition was placed in the top layer of the combined sieve and classified by shaking for 10 minutes using a RO-TAP shaker. After classification, the mass of the particulate absorbent resin composition remaining on each sieve was calculated as a mass percentage relative to the total amount to obtain the particle size distribution. Regarding this particle size distribution, the relationship between the sieve mesh size and the accumulated value of the mass percentage of the particulate absorbent resin composition remaining on the sieve was plotted on a logarithm positivity paper by accumulating the sieves in order from largest to smallest particle diameter. By connecting the plots on the positivity paper with a straight line, the particle diameter corresponding to an accumulated mass percentage of 50 mass% was defined as the median particle diameter.

[0108] <Test for Suppression of Complex Odors Containing Acetaldehyde and Trimethylamine>

[0109] (Preparation of complex malodorous gases)

[0110] Under conditions of 25±2℃, 9L of standard gas (manufactured by Sumitomo Seika Co., Ltd., diluted with nitrogen) adjusted to an acetaldehyde concentration of 19.3 ppm was sealed in a 10L Tedlar bag, and gas obtained by vaporizing an aqueous trimethylamine solution was sealed in a syringe to prepare a complex odor gas with a trimethylamine concentration of 22 ppm in the Tedlar bag. The concentrations of each odor component in the Tedlar bag were measured using a gas detector tube (manufactured by Gas Tech Co., Ltd., detector tube: acetaldehyde 92L and trimethylamine 180). In addition, the trimethylamine concentration was calculated using the following formula with the correction value specified in the detector tube, and the acetaldehyde concentration was used as is from the indicated concentration on the detector tube.

[0111] (Trimethylamine Concentration) = (Detector Tube Indicated Concentration) × (Material Count: 0.9) × (Temperature Count: 0.7)

[0112] The suppression test for complex odors was conducted under an environment of 25℃±2℃. 1.00g of a particulate absorbent resin composition was placed in a plastic petri dish with an inner diameter of 10cm and a height of 1.5cm. The petri dish containing the particulate absorbent resin composition was placed into a 2L Tedlar bag (with a single cap) equipped with a three-way stopcock through a silicone tube with an inner diameter of 5mm, and sealed by heat sealing. Subsequently, a glass syringe (humidity-controlled glass syringe, 200mL, manufactured by Yugen Kaisha Tsuji Seisakusho) was connected to the three-way stopcock to extract all the air from the Tedlar bag. Afterward, 900mL of a pre-prepared complex odor gas was sealed into the Tedlar bag using the aforementioned glass syringe. Sixty minutes after the completion of filling the complex malodorous gas, the three-way stopcock was removed from the Tedla bag, and a gas detector tube with an open tip (manufactured by Gas Tech Co., Ltd., detector tube: Trimethylamine 180) was attached to measure the trimethylamine concentration in the gas phase of the Tedla bag. Immediately after the measurement of the trimethylamine concentration was completed, the aforementioned gas detector tube for trimethylamine was removed, and a separate gas detector tube with an open tip (manufactured by Gas Tech Co., Ltd., detector tube: Acetaldehyde 92L) was attached in the same manner to measure the acetaldehyde concentration. Furthermore, the trimethylamine concentration was calculated using the following formula utilizing the correction value specified on the detector tube, while the acetaldehyde concentration was used as is, based on the indicated concentration on the detector tube. The measurement results are shown in Table 1. (Trimethylamine Concentration) = (Detector Tube Indicated Concentration) × (Material Count: 0.9) × (Temperature Count: 0.7)

[0113] <Manufacture of Particulate Absorbent Resins>

[0114] (Preparation Example 1)

[0115] A round-bottomed cylindrical separable flask with an inner diameter of 11 cm and a volume of 2 L was prepared, equipped with a reflux condenser, a dropping funnel, a nitrogen gas inlet tube, and a stirring blade having two stages of four inclined paddle blades with a blade diameter of 5 cm. In this flask, 293 g of n-heptane was taken as a hydrocarbon dispersion medium, and 0.736 g of maleic anhydride-modified ethylene-propylene copolymer (Mitsui Kagaku Co., Ltd., Hi-Wax 1105A) was added as a polymeric dispersant. The temperature was raised to 80°C while stirring to dissolve the dispersant, and then cooled to 50°C.

[0116] Meanwhile, 92.0 g (1.03 mol) of an 80.5 mass% aqueous acrylic acid solution as a water-soluble ethylenically unsaturated monomer was taken into a beaker with an internal volume of 300 mL, and while cooling with ice water, 147.7 g of a 20.9 mass% aqueous sodium hydroxide solution was added dropwise to neutralize it to 75 mol%. Then, 0.092 g of hydroxyethylcellulose (Sumitomo Seika Co., Ltd., HECAW-15F) as a thickening agent, 0.0736 g (0.272 mmol) of potassium persulfate as a water-soluble radical polymerizing agent, and 0.010 g (0.057 mmol) of ethylene glycol diglycidyl ether as an internal crosslinking agent were added and dissolved to prepare the monomer aqueous solution of the first step.

[0117] Then, the monomer aqueous solution prepared above was added to a separable flask and stirred for 10 minutes, and then a surfactant solution was further added in which 0.736 g of HLB3 sucrose stearic acid ester (Mitsubishi Chemical Foods Co., Ltd., Ryoto Sugar Ester S-370) was heated and dissolved in 6.62 g of n-heptane in a 20 mL vial. After stirring with the stirrer rotation speed set to 550 rpm and sufficiently purging the system with nitrogen, the flask was immersed in a water bath at 70°C for 60 minutes to obtain the polymerization slurry of the first stage.

[0118] Meanwhile, 128.8 g (1.43 mol) of an 80.5 mass% aqueous acrylic acid solution as a water-soluble ethylenically unsaturated monomer was taken into a separate beaker with an internal volume of 500 mL, and while cooling with ice water, 159.0 g of a 27 mass% aqueous sodium hydroxide solution was added dropwise to neutralize it to 75 mol%. Then, 0.103 g (0.381 mmol) of potassium persulfate was added as a water-soluble radical polymerization initiator and 0.0116 g (0.067 mmol) of ethylene glycol diglycidyl ether was added as an internal crosslinking agent and dissolved to prepare a second-stage monomer aqueous solution.

[0119] While stirring with the stirrer at a rotation speed of 1000 rpm, the above separable flask system was cooled to 25°C, the entire amount of the monomer aqueous solution of the second stage was added to the polymerization slurry of the first stage, the system was purged with nitrogen for 30 minutes, and then the flask was immersed again in a water bath at 70°C for 60 minutes to obtain the aqueous gel polymer of the second stage.

[0120] 0.589 g of a 45 mass% aqueous solution of sodium diethylenetriamine pentaacetic acid was added to the hydrated gel polymer after the second stage of polymerization under stirring. Then, the flask was immersed in an oil bath set to 125°C, and 257.7 g of water was withdrawn from the system while refluxing n-heptane by azeotropic distillation of n-heptane and water. Subsequently, 4.42 g (0.507 mmol) of a 2 mass% aqueous solution of ethylene glycol diglycidyl ether was added to the flask as a post-crosslinking agent, and the mixture was maintained at 83°C for 2 hours.

[0121] Subsequently, a particulate crosslinked polymer (dry product) was obtained by evaporating and drying n-heptane at 125°C. This particulate crosslinked polymer was passed through a sieve with a mesh size of 850 μm, and 0.1 mass% of amorphous silica (Oriental Silicas Corporation, Tokuseal NP-S) relative to the mass of the particulate crosslinked polymer was mixed with the particulate crosslinked polymer to obtain 228.0 g of a particulate absorbent resin containing amorphous silica. The median particle diameter of the particulate absorbent resin was 352 μm.

[0122] <Preparation of Particulate Absorbent Resin Composition>

[0123] (Example 1)

[0124] A particulate absorbent resin composition was obtained by powder mixing 1.0 mass of a silicate compound loaded with a hydrazide compound (Kabushiki Kaisha Shinanen Zeomics, Dash Light M, loading amount of hydrazide compound: 7 mass%, median particle diameter 6 μm) with respect to 100 mass of the particulate absorbent resin obtained in Preparation 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.

[0125] (Example 2)

[0126] In Example 1, a particulate absorbent resin composition was obtained in the same manner as in Example 1, except that the silicate compound supporting the hydrazide compound was changed to 0.5 parts by mass per 100 parts by mass of the particulate absorbent resin. After the complex odor suppression test, the acetaldehyde concentration in the gas phase was 11 ppm and the trimethylamine concentration was 4 ppm.

[0127] (Comparative Example 1)

[0128] The particulate absorbent resin obtained in Preparation Example 1 was used as the particulate absorbent resin of Comparative Example 1 for a deodorization test. After the complex odor suppression test, the acetaldehyde concentration in the gas phase was 16 ppm and the trimethylamine concentration was 10 ppm.

[0129] (Comparative Example 2)

[0130] A particulate absorbent resin composition was obtained by powder mixing 0.07 parts by mass of malonic acid dihydrazide with 100 parts by mass of the particulate absorbent resin obtained in Preparation Example 1. After the complex odor suppression test, the acetaldehyde concentration in the gas phase was 13 ppm and the trimethylamine concentration was 12 ppm.

[0131] (Comparative Example 3)

[0132] A particulate absorbent resin composition was obtained by powder mixing 1.0 part by mass of zeolite (synthetic zeolite available as a reagent, with an intermediate particle diameter of 2 μm) with 100 parts by mass of the particulate absorbent resin obtained in Preparation Example 1. After the complex odor suppression test, the acetaldehyde concentration in the gas phase was 16 ppm and the trimethylamine concentration was 16 ppm.

[0133] (Reference Example)

[0134] As a comparison, the concentrations of acetaldehyde and trimethylamine in the gas phase of a sample containing only a petri dish placed in a Tedlar bag without the addition of the particulate absorbent resin composition were measured. The results are shown in Table 1.

[0135]

Claims

Claim 1 A particulate absorbent resin composition comprising a hydrazide compound carrier and a particulate absorbent resin, wherein the content of the hydrazide compound carrier is 0.001 to 10 mass% and the median particle diameter of the particulate absorbent resin is 100 to 600 μm. Claim 2 A particulate absorbent resin composition according to claim 1, wherein the form of the particulate absorbent resin is a particulate absorbent resin selected from at least one of the form of primary particles that are spherical, irregularly fragmented, or plate-shaped, and the form of secondary particles in which the primary particles are aggregated. Claim 3 A particulate absorbent resin composition according to claim 1, wherein the hydrazide compound carrier is present on at least one of the surface and the interior of the particulate absorbent resin. Claim 4 A particulate absorbent resin composition according to claim 1, wherein the carrier of the hydrazide compound carrier is at least one of silicic acid and silicate. Claim 5 A particulate absorbent resin composition according to claim 1, wherein the content of the hydrazide compound carrier is 0.01 to 5 mass%. Claim 6 A particulate absorbent resin composition according to claim 1, wherein the content of the hydrazide compound in the hydrazide compound carrier is 0.1 to 30 mass%. Claim 7 A particulate absorbent resin composition used for deodorizing odors caused by acetaldehyde and trimethylamine, according to claim 1. Claim 8 An absorbent comprising a particulate absorbent resin composition as described in any one of claims 1 to 7. Claim 9 An absorbent article formed by maintaining the absorbent described in claim 8 between a liquid-permeable sheet and a liquid-impermeable sheet.

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