WO2023063182A1 - Method for producing water absorbent resin composition - Google Patents
Method for producing water absorbent resin composition Download PDFInfo
- Publication number
- WO2023063182A1 WO2023063182A1 PCT/JP2022/037238 JP2022037238W WO2023063182A1 WO 2023063182 A1 WO2023063182 A1 WO 2023063182A1 JP 2022037238 W JP2022037238 W JP 2022037238W WO 2023063182 A1 WO2023063182 A1 WO 2023063182A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- water
- resin composition
- absorbent resin
- parts
- cross
- Prior art date
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 128
- 239000011342 resin composition Substances 0.000 title claims abstract description 94
- 239000002250 absorbent Substances 0.000 title claims abstract description 79
- 230000002745 absorbent Effects 0.000 title claims abstract description 61
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 20
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 87
- 239000003431 cross linking reagent Substances 0.000 claims abstract description 77
- 239000000178 monomer Substances 0.000 claims abstract description 60
- 238000000034 method Methods 0.000 claims abstract description 57
- 229920006037 cross link polymer Polymers 0.000 claims abstract description 47
- 238000010521 absorption reaction Methods 0.000 claims abstract description 46
- 238000004132 cross linking Methods 0.000 claims abstract description 26
- 239000007800 oxidant agent Substances 0.000 claims abstract description 25
- 150000003839 salts Chemical class 0.000 claims abstract description 25
- 239000000203 mixture Substances 0.000 claims abstract description 22
- 150000002762 monocarboxylic acid derivatives Chemical class 0.000 claims abstract description 20
- 230000007062 hydrolysis Effects 0.000 claims abstract description 8
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 8
- 239000000243 solution Substances 0.000 claims description 57
- 150000002763 monocarboxylic acids Chemical class 0.000 claims description 23
- 239000002504 physiological saline solution Substances 0.000 claims description 17
- 238000000354 decomposition reaction Methods 0.000 claims description 16
- 239000000126 substance Substances 0.000 claims description 12
- 125000000217 alkyl group Chemical group 0.000 claims description 9
- 125000001424 substituent group Chemical group 0.000 claims description 9
- 125000003277 amino group Chemical group 0.000 claims description 8
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 claims description 8
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 8
- 125000003396 thiol group Chemical group [H]S* 0.000 claims description 8
- 239000000470 constituent Substances 0.000 claims description 6
- 239000001257 hydrogen Substances 0.000 claims description 5
- 229910052739 hydrogen Inorganic materials 0.000 claims description 5
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 3
- 239000011780 sodium chloride Substances 0.000 claims description 3
- 239000006096 absorbing agent Substances 0.000 claims description 2
- 230000000379 polymerizing effect Effects 0.000 abstract description 6
- 230000007613 environmental effect Effects 0.000 abstract description 5
- 230000009467 reduction Effects 0.000 abstract description 5
- 230000001590 oxidative effect Effects 0.000 abstract 1
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 60
- 239000000047 product Substances 0.000 description 47
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- 239000007864 aqueous solution Substances 0.000 description 29
- 238000001035 drying Methods 0.000 description 20
- -1 alkali metal salts Chemical class 0.000 description 19
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- 238000002156 mixing Methods 0.000 description 16
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 16
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- 239000002245 particle Substances 0.000 description 14
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 13
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 11
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- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 10
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- 239000003999 initiator Substances 0.000 description 10
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- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 235000006708 antioxidants Nutrition 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 150000001541 aziridines Chemical class 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 235000019400 benzoyl peroxide Nutrition 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- LDHQCZJRKDOVOX-NSCUHMNNSA-N crotonic acid Chemical compound C\C=C\C(O)=O LDHQCZJRKDOVOX-NSCUHMNNSA-N 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 125000004093 cyano group Chemical group *C#N 0.000 description 1
- 238000010908 decantation Methods 0.000 description 1
- 239000002781 deodorant agent Substances 0.000 description 1
- 239000000645 desinfectant Substances 0.000 description 1
- LSXWFXONGKSEMY-UHFFFAOYSA-N di-tert-butyl peroxide Chemical compound CC(C)(C)OOC(C)(C)C LSXWFXONGKSEMY-UHFFFAOYSA-N 0.000 description 1
- 150000001993 dienes Chemical class 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- VFHVQBAGLAREND-UHFFFAOYSA-N diphenylphosphoryl-(2,4,6-trimethylphenyl)methanone Chemical compound CC1=CC(C)=CC(C)=C1C(=O)P(=O)(C=1C=CC=CC=1)C1=CC=CC=C1 VFHVQBAGLAREND-UHFFFAOYSA-N 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 229940069096 dodecene Drugs 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000003205 fragrance Substances 0.000 description 1
- 238000004108 freeze drying Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000008202 granule composition Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000012456 homogeneous solution Substances 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 230000000415 inactivating effect Effects 0.000 description 1
- 238000007603 infrared drying Methods 0.000 description 1
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical compound II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000012948 isocyanate Substances 0.000 description 1
- 229940087305 limonene Drugs 0.000 description 1
- 235000001510 limonene Nutrition 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 235000013372 meat Nutrition 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- JESXATFQYMPTNL-UHFFFAOYSA-N mono-hydroxyphenyl-ethylene Natural products OC1=CC=CC=C1C=C JESXATFQYMPTNL-UHFFFAOYSA-N 0.000 description 1
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- CCCMONHAUSKTEQ-UHFFFAOYSA-N octadecene Natural products CCCCCCCCCCCCCCCCC=C CCCMONHAUSKTEQ-UHFFFAOYSA-N 0.000 description 1
- 235000019645 odor Nutrition 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 150000002918 oxazolines Chemical class 0.000 description 1
- FWFGVMYFCODZRD-UHFFFAOYSA-N oxidanium;hydrogen sulfate Chemical compound O.OS(O)(=O)=O FWFGVMYFCODZRD-UHFFFAOYSA-N 0.000 description 1
- 238000001139 pH measurement Methods 0.000 description 1
- 239000013618 particulate matter Substances 0.000 description 1
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 description 1
- KHIWWQKSHDUIBK-UHFFFAOYSA-N periodic acid Chemical compound OI(=O)(=O)=O KHIWWQKSHDUIBK-UHFFFAOYSA-N 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 239000012286 potassium permanganate Substances 0.000 description 1
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 1
- 239000003755 preservative agent Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- HJWLCRVIBGQPNF-UHFFFAOYSA-N prop-2-enylbenzene Chemical compound C=CCC1=CC=CC=C1 HJWLCRVIBGQPNF-UHFFFAOYSA-N 0.000 description 1
- 125000004368 propenyl group Chemical group C(=CC)* 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000013557 residual solvent Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 1
- 230000007928 solubilization Effects 0.000 description 1
- 238000005063 solubilization Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 150000003440 styrenes Chemical class 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000010557 suspension polymerization reaction Methods 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- LDHQCZJRKDOVOX-UHFFFAOYSA-N trans-crotonic acid Natural products CC=CC(O)=O LDHQCZJRKDOVOX-UHFFFAOYSA-N 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/04—Acids; Metal salts or ammonium salts thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/04—Recovery or working-up of waste materials of polymers
- C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
Definitions
- the present invention relates to a method for producing a water absorbent resin composition.
- paper diapers are usually incinerated, but since the percentage of water in diapers is close to 80%, incineration requires a large amount of combustion energy. For this reason, the treatment places a heavy load on the incinerator itself, which leads to shortening of the life of the incinerator. In addition, since incineration leads to air pollution and global warming, and is also a factor that places a burden on the environment, improvement is strongly desired. Moreover, in the field of nursing care, how to reduce the burden on caregivers to dispose of disposable diapers has become an issue.
- Sanitary products usually contain an absorbent body composed of pulp fibers and water-absorbent resin particles, and the pulp fibers and water-absorbent resin particles must be separated in order to reuse them as members.
- the water-absorbing resin particles in the absorbent body of the used sanitary goods absorb water and become swollen gel state, it is difficult to separate them as they are. Therefore, a technique has been proposed to decompose and solubilize the water-absorbent resin particles and separate the solubilized components of the pulp fibers and the water-absorbent resin particles.
- Patent Documents 1 and 2 There is a technique (Patent Documents 1 and 2) in which pulp fibers are recovered after decomposing and solubilizing water-absorbent resin particles by treatment with a contained aqueous solution.
- a technique for decomposing and solubilizing water-absorbing resin particles a technique using an oxidizing agent such as hydrogen peroxide as a decomposition method, and a method of irradiating electromagnetic waves (Patent Documents 3 to 6) are known.
- Patent Documents 3 to 6 a technique has been reported in which a crosslinked polymer compound is reacted with an oxidizing agent to selectively cut only the crosslinker unit portion to convert it into a water-soluble polyacrylic acid (salt) (Patent Document 7).
- a crosslinked polymer compound is reacted with an oxidizing agent to selectively cut only the crosslinker unit portion to convert it into a water-soluble polyacrylic acid (salt)
- salt water-soluble polyacrylic acid
- the purpose of the recycling technology for used sanitary products mentioned above is to collect pulp fibers and use them as recycled pulp. In most cases, it is not sufficient from the viewpoint of recycling.
- the water-absorbent resin particles are decomposed into acrylic acid, which is the main monomer component, and/or its salts and oligomers by electromagnetic irradiation. It requires an operation to swell to This is inefficient from the viewpoint of obtaining acrylic acid and/or its salts and oligomers because the concentration of acrylic acid and/or its salts and oligomers obtained after decomposition decreases, and is improved from the viewpoint of recycling. There is room.
- An object of the present invention is to provide a method for producing a water-absorbing resin composition that can efficiently decompose a crosslinked polymer with an oxidizing agent while satisfying the required water-absorbing performance at the time of use, and that can contribute to resource saving and environmental load reduction. is to provide
- the present invention provides one or more monomers selected from the group consisting of water-soluble unsaturated monocarboxylic acids (a1) and salts thereof, and monomers (a2) that become the water-soluble unsaturated monocarboxylic acids (a1) by hydrolysis.
- a polymerization solution containing a monomer composition containing (A1) and an internal cross-linking agent (b) represented by the following general formula (1) and having a pH of 1 to 12 Manufacture of a water-absorbing resin composition having a polymerization step of polymerizing in a water-containing gel containing a crosslinked polymer (A) and a surface cross-linking step of cross-linking the cross-linked polymer (A) with a surface cross-linking agent (c) The method.
- R1 is hydrogen, an alkyl group, a hydroxy group, an amino group, a mercapto group, a substituted carbonyl group, and one or more selected from a hydroxy group, an amino group, a mercapto group, and a substituted carbonyl group. It is one or more selected from arbitrary alkyl groups having as substituents.
- a method for producing a water-absorbing resin composition that has excellent water-absorbing performance and efficiently decomposes a crosslinked polymer with an oxidizing agent, thereby contributing to resource saving and reduction of environmental load. can do.
- the method for producing a water-absorbent resin composition of the present embodiment comprises a water-soluble unsaturated monocarboxylic acid (a1) and a salt thereof, and a monomer (a2) that becomes the water-soluble unsaturated monocarboxylic acid (a1) by hydrolysis.
- R1 is hydrogen, an alkyl group, a hydroxy group, an amino group, a mercapto group, a substituted carbonyl group, and one or more selected from a hydroxy group, an amino group, a mercapto group, and a substituted carbonyl group. It is one or more selected from arbitrary alkyl groups having as substituents.
- the water-absorbing resin has excellent water-absorbing performance, and the crosslinked polymer is efficiently decomposed by the oxidizing agent, contributing to resource saving and environmental load reduction.
- Compositions can be manufactured.
- the method for producing a water-absorbent resin composition of the present embodiment comprises a water-soluble unsaturated monocarboxylic acid (a1) and a salt thereof, and a monomer (a2) that becomes the water-soluble unsaturated monocarboxylic acid (a1) by hydrolysis.
- the water-soluble unsaturated monocarboxylic acid (a1) can be used without particular limitation as long as it is a water-soluble unsaturated monocarboxylic acid.
- the water-soluble unsaturated monocarboxylic acid (a1) is preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, and crotonic acid, from the viewpoint of water absorption performance when crosslinked and ease of availability. , acrylic acid, and methacrylic acid are more preferred.
- Examples of the salt of the water-soluble unsaturated monocarboxylic acid (a1) include alkali metal (lithium, sodium, potassium, etc.) salts, alkaline earth metal (magnesium, calcium, etc.) salts and ammonium (NH 4 ) salts. .
- alkali metal salts and ammonium salts are preferable, alkali metal salts are more preferable, and sodium salts are particularly preferable, from the viewpoint of absorption performance and the like.
- the monomer (a2) that becomes the water-soluble unsaturated monocarboxylic acid (a1) by hydrolysis can be used together with or instead of the water-soluble unsaturated monocarboxylic acid (a1).
- the monomer (a2) is not particularly limited, and a monomer having one hydrolyzable substituent that becomes a carboxy group by hydrolysis can be exemplified.
- hydrolyzable substituent examples include acid anhydride-containing groups (1,3-oxo-1-oxapropylene group, -COO-CO-), ester bond-containing groups (alkyloxycarbonyl, vinyloxycarbonyl, allyl oxycarbonyl or propenyloxycarbonyl, —COOR), cyano group and the like.
- R is an alkyl group having 1 to 3 carbon atoms (methyl, ethyl and propyl), vinyl, allyl and propenyl.
- water-soluble means that at least 100 g dissolves in 100 g of water at 25°C.
- hydrolyzability of the monomer (a2) means the property of being hydrolyzed by the action of water and, if necessary, a catalyst (acid, base, etc.) to become water-soluble.
- the hydrolysis of the monomer (a2) may be carried out during polymerization, after polymerization, or both of them, but from the viewpoint of the absorption performance of the resulting water-absorbent resin composition, it is preferably carried out after polymerization.
- the monomer composition may contain, in addition to the monomer (A1), another vinyl monomer (A2) copolymerizable therewith.
- A1 another vinyl monomer copolymerizable therewith.
- One of the vinyl monomers (A2) may be used alone, or two or more of them may be used in combination.
- the vinyl monomer (A2) is not particularly limited, and is known (for example, hydrophobic vinyl monomers disclosed in paragraphs 0028 to 0029 of Japanese Patent No. 3648553; 2005-75982, paragraph 0058) can be used, and specifically, vinyl monomers (i) to (iii) below can be used.
- (i) Aromatic ethylenic monomer having 8 to 30 carbon atoms Styrene such as styrene, ⁇ -methylstyrene, vinyltoluene and hydroxystyrene, vinylnaphthalene, and halogen-substituted styrene such as dichlorostyrene.
- Aliphatic ethylenic monomers having 2 to 20 carbon atoms Alkenes (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.); and alkadienes (butadiene, isoprene, etc.).
- the amount of the vinyl monomer (A2) in the monomer composition is preferably 0 to 5 mol parts, more preferably 0, with respect to 100 mol parts of the monomer (A1) from the viewpoint of absorption performance and the like. It is preferably 0 to 3 mol parts, particularly preferably 0 to 2 mol parts, and most preferably 0 to 1.5 mol parts, and most preferably 0 mol parts from the viewpoint of absorption performance.
- the internal cross-linking agent (b) has a diacylhydrazine skeleton (general formula: R3-CONHNHCO-R4; R3 and R4 are each independently arbitrary polymer chains).
- the diacylhydrazine skeleton of the internal cross-linking agent (b), which is a structural unit of the cross-linked polymer (A) is decomposed by reacting with an oxidizing agent other than oxygen to produce nitrogen and carboxylic acid. By this reaction, the diacylhydrazine chains that crosslink the polymer chains in the crosslinked polymer (A) are cut, and the three-dimensional crosslinked structure of the crosslinked polymer (A) is eliminated, resulting in a linear polymerization. It can be made water soluble by being converted into a coalescence.
- the two R1 in the general formula (1) are each independently hydrogen, an alkyl group, a hydroxy group, an amino group, a mercapto group, a substituted carbonyl group, and a hydroxy group, an amino group, a mercapto group, and a substituted carbonyl group. It is not particularly limited as long as it is one or more selected from any alkyl group having one or more selected as substituents, but solubility in aqueous solution, absorption performance of the water absorbent resin composition, and availability From the viewpoint of ease of use, both are preferably hydrogen.
- the amount of the internal cross-linking agent (b) in the monomer composition is 100 mol parts of the monomer (A1) and the other vinyl monomer (A2) from the viewpoint of absorption performance and absorption speed by the Vortex method.
- (A1) and (A2) with respect to a total of 100 mol parts, preferably 0.001 to 5 mol parts, more preferably 0.005 to 3 mol parts, particularly preferably 0.005 to 1 mol parts Department.
- a cross-linking agent having two or more ethylenically unsaturated groups disclosed in paragraphs 0031 to 0034 of Japanese Patent No. 3648553, a water-soluble substituent, and A cross-linking agent having at least one functional group capable of reacting and having at least one ethylenically unsaturated group and a cross-linking agent having at least two functional groups capable of reacting with a water-soluble substituent JP-A-2003-165883
- the substance amount of the internal cross-linking agent other than the internal cross-linking agent (b) is preferably 0 to 50 mol parts per 100 mol parts of the internal cross-linking agent (b) from the viewpoint of decomposition performance.
- an aqueous solution polymerization method or a reverse phase suspension polymerization method sustained polymerization in a hydrocarbon solvent
- a reverse phase suspension polymerization method sustained polymerization in a hydrocarbon solvent
- water or a mixed solvent containing water and an organic solvent can be used as a polymerization solvent.
- Organic solvents include methanol, ethanol, acetone, methyl ethyl ketone, N,N-dimethylformamide, dimethylsulfoxide and mixtures of two or more thereof.
- the polymerization solvent, water or a mixed solvent containing water and an organic solvent is mixed with the monomer composition to form a polymerization solution.
- the amount (% by weight) of the organic solvent used is preferably 40 or less, more preferably 30 or less, based on the weight of water.
- polymerization may be carried out in the presence of a conventionally known dispersant or surfactant, if necessary. Also, the polymerization can be carried out using conventionally known hydrocarbon solvents such as xylene, normal hexane and normal heptane.
- a polymerization solution containing the monomer (A1) and the internal cross-linking agent (b) is suspended in a hydrocarbon solvent, and the polymerization solution dispersed in the hydrocarbon solvent is polymerized. The method.
- the polymerization solution in the reversed-phase suspension polymerization method the same solution as used in the aqueous solution polymerization can be used.
- the aqueous solution polymerization method is preferable because it does not require the use of an organic solvent or the like and is advantageous in terms of production cost, and an aqueous liquid absorbent resin with a large water retention capacity and a small amount of water-soluble components is produced.
- the aqueous solution adiabatic polymerization method is more preferable because it can be obtained and temperature control during polymerization is unnecessary.
- the total weight percent concentration of the monomers contained in the polymerization solution is preferably 15 to 55% with respect to the total weight of the polymerization solution at the start of polymerization. If it is lower than this range, the productivity may deteriorate, and if it is higher than this range, sufficient gel strength may not be obtained.
- the pH range of the polymerization solution containing the monomer composition is 1-12, more preferably 1-10, and still more preferably 1-7. Within this range, surface cross-linking by a surface cross-linking agent, which will be described later, proceeds efficiently, and the required water absorption performance can be easily obtained. On the other hand, when the pH exceeds 12, the surface cross-linking by the surface cross-linking agent becomes difficult to proceed, and as a result, the required water absorption performance is not exhibited.
- the pH of the polymerization solution is measured at 25° C. using a glass electrode pH meter in accordance with JIS Z8802 pH measurement method using a sample for measurement without diluting the polymerization solution.
- the pH of the polymerization solution can be adjusted by the concentration of the monomer (A1) contained in the polymerization solution. Moreover, it may be adjusted by adding a known water-soluble acidic substance or water-soluble basic substance to the polymerization solution.
- a water-soluble acidic substance include hydrogen chloride, sulfuric acid, nitric acid, acetic acid, lactic acid and oxalic acid, more preferably sulfuric acid and lactic acid.
- preferable basic substances include sodium hydroxide and potassium hydroxide, more preferably sodium hydroxide.
- polymerization can be carried out by mixing a known radical initiator and a polymerization solution.
- the radical initiator and the polymerization solution are mixed, the polymerization reaction is initiated, making it difficult to measure the pH.
- the radical initiator is weakly acidic to neutral, even when the polymerization is performed by mixing the radical initiator, the pH before and after mixing the radical initiator hardly changes. Therefore, the pH of the polymerization solution when polymerization is performed by mixing the radical initiator and the polymerization solution is measured by the above method before mixing the radical initiator.
- Known radical initiators include azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid and 2,2′-azobis(2-amidinopropane) hydrochloride, 2,2′-azobis[2-methyl-N- (2-hydroxyethyl) propionamide], etc.], inorganic peroxides (hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate, etc.), organic peroxides [benzoyl peroxide, di-t-butyl peroxide , cumene hydroperoxide, succinic acid peroxide and di(2-ethoxyethyl)peroxydicarbonate, etc.], redox catalysts (alkali metal sulfites or bisulfites, ammonium sulfite, ammonium bisulfite and reduction of ascorbic acid, etc.
- azo compounds azobisisobutyronitrile, azobiscyanovaleric acid and 2,2′
- radical initiators such as alkali metal persulfates, ammonium persulfates, hydrogen peroxide and organic peroxides
- photoradical generators [2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 1-hydroxycyclohexyl-phenylketone-hydroxyalkylphenone, ⁇ -aminoalkylphenone, etc.] and the like.
- radical initiators may be used alone, or two or more of them may be used in combination.
- the amount of the radical initiator used is preferably 0.0005 to 5 mol parts, more preferably 0.001 to 2 mol parts, per 100 mol parts of the monomer (A1).
- a hydrous gel of the crosslinked polymer (A) having the monomer (A1) and the internal cross-linking agent (b) as constituent units is obtained, and this hydrous gel may be cut into small pieces as necessary. can be done.
- the size (longest diameter) of the water-containing gel after shredding is preferably 50 ⁇ m to 10 cm, more preferably 100 ⁇ m to 2 cm, particularly preferably 1 mm to 1 cm. Within this range, the drying property in the drying step is further improved.
- Shredding can be performed by a known method, and finely using a shredding device (e.g., Vex mill, rubber chopper, farmer mill, mincing machine (meat chopper), impact pulverizer, and roll pulverizer). can be cut off. Further, during the cutting, if necessary, the hydrous gel obtained as described above can be neutralized by mixing with an alkali.
- a shredding device e.g., Vex mill, rubber chopper, farmer mill, mincing machine (meat chopper), impact pulverizer, and roll pulverizer.
- the alkali a known one ⁇ Patent No. 3205168, etc. ⁇ can be used.
- lithium hydroxide, sodium hydroxide and potassium hydroxide are preferred, sodium hydroxide and potassium hydroxide are more preferred, and sodium hydroxide is particularly preferred, from the viewpoint of water absorption performance.
- the neutralization rate is preferably 20 to 100 mol %, more preferably 50 to 80 mol %, from the viewpoint of water absorption performance and handling. If the degree of neutralization is less than 50 mol %, the obtained hydrogel will be highly sticky, and workability during production and use may be deteriorated. Furthermore, the water-retaining capacity of the obtained water-absorbing resin may decrease. On the other hand, if the degree of neutralization exceeds 80%, the resulting resin will have a high pH and may be unsafe for human skin.
- the method for producing a water-absorbing resin composition of the present embodiment may have a drying step of drying the water-containing gel and distilling off the solvent (including water) in the water-containing gel.
- microwave drying As a drying method in the drying step, microwave drying, a thin film drying method using a drum dryer, etc., a (heating) vacuum drying method, a freeze drying method, an infrared drying method, decantation, filtration, and the like can be applied.
- the drying temperature in the drying step is 100-300°C, preferably 150-250°C. If the drying temperature is high, the drying time will be shortened, resulting in improved productivity. The color tone of the water absorbent resin composition may deteriorate. If the drying temperature is lower than 100°C, the water-absorbing resin composition cannot be sufficiently dried, resulting in a decrease in productivity.
- the drying time is preferably within 60 minutes, more preferably within 40 minutes, from the viewpoint of suppressing changes in soluble matter while suppressing changes in color after long-term storage in a hot and humid environment. preferable. Also, the drying time is generally preferably 10 minutes or longer. Short drying times can lead to undried material and clogging later in the milling process.
- the method for producing a water-absorbent resin composition of the present embodiment includes a pulverizing step of pulverizing the dried body of the hydrous gel obtained in the drying step to obtain a particulate dried body containing the crosslinked polymer (A). may have.
- the method for pulverizing the dried hydrogel is not particularly limited, and a pulverizer (for example, a hammer pulverizer, an impact pulverizer, a roll pulverizer, and a jet air pulverizer), etc. Available.
- the pulverized water absorbent resin composition can be adjusted in particle size by sieving or the like, if necessary.
- the method for producing a water-absorbing resin composition of the present embodiment includes a surface cross-linking step of cross-linking the surface of the cross-linked polymer (A) with a surface cross-linking agent after the polymerization step of obtaining a hydrous gel containing the cross-linked polymer (A).
- the water absorbent resin composition obtained through the surface cross-linking step has a structure in which the surface of the cross-linked polymer (A) is cross-linked by the surface cross-linking agent (c).
- the gel strength of the water-absorbing resin composition can be improved, and the water-absorbing resin composition satisfies the desired water retention capacity and absorption capacity under load. can be done.
- blocking on the surface of the water-absorbing resin composition can be suppressed and uniform water absorption can be achieved, even when decomposing with an oxidizing agent, an improvement in decomposition efficiency can be expected.
- Both inorganic and organic substances can be used as the surface cross-linking agent (c).
- the surface cross-linking agent (c) known (polyvalent glycidyl compounds, polyvalent amines, polyvalent aziridine compounds and polyvalent isocyanate compounds described in JP-A-59-189103, etc., JP-A-58-180233 And the polyhydric alcohol of JP-A-61-16903, the silane coupling agent described in JP-A-61-211305 and JP-A-61-252212, the JP-A-5-508425 described Organic surface cross-linking agents such as alkylene carbonates and polyvalent oxazoline compounds described in JP-A-11-240959 can be used.
- polyhydric glycidyl compounds, polyhydric alcohols and polyhydric amines are preferred, more preferred are polyhydric glycidyl compounds and polyhydric alcohols, and particularly preferred are polyhydric glycidyl compounds and polyhydric alcohols, from the viewpoint of economy and absorption properties.
- the surface cross-linking agent (c) may be used alone or in combination of two or more.
- the amount (% by weight) of the surface cross-linking agent (c) used is not particularly limited because it can be varied depending on the type of the surface cross-linking agent, cross-linking conditions, target performance, etc., but from the viewpoint of absorption characteristics, etc. Therefore, it is preferably 0.001 to 3, more preferably 0.005 to 2, and particularly preferably 0.01 to 1.5, based on the weight of the crosslinked polymer (A).
- the surface cross-linking of the cross-linked polymer (A) can be performed by mixing the cross-linked polymer (A) and the surface cross-linking agent (c) and heating the mixture.
- Examples of the method for mixing the crosslinked polymer (A) and the surface cross-linking agent (c) include a cylindrical mixer, a screw mixer, a screw extruder, a turbulizer, a Nauta mixer, a twin-arm kneader, a fluid
- a crosslinked polymer ( A) can be uniformly mixed with the surface cross-linking agent (c). At this time, the surface cross-linking agent (c) may be diluted with water and/or any solvent before use.
- Mixing of the crosslinked polymer (A) and the surface cross-linking agent (c) is preferably performed by mixing the dried hydrous gel containing the crosslinked polymer (A) obtained in the drying step with the surface cross-linking agent (c). It is more preferable to mix the particulate dry matter containing the crosslinked polymer (A) obtained in the pulverization step with the surface crosslinking agent (c).
- the temperature at which the crosslinked polymer (A) and the surface cross-linking agent (c) are mixed is not particularly limited, but is preferably 10 to 150°C, more preferably 20 to 100°C, and particularly preferably 25 to 80°C. .
- Heat treatment is preferably performed after mixing the crosslinked polymer (A) and the surface crosslinking agent (c).
- the heating temperature is preferably 100 to 180°C, more preferably 110 to 175°C, particularly preferably 120 to 170°C, from the viewpoint of breakage resistance of the water absorbent resin composition. Heating at 180° C. or less enables indirect heating using steam, which is advantageous in terms of facilities. Heating temperatures below 100° C. may result in poor absorption performance.
- the heating time can be appropriately set depending on the heating temperature, but from the viewpoint of absorption performance, it is preferably 5 to 60 minutes, more preferably 10 to 40 minutes. It is also possible to further surface-crosslink the water-absorbing resin composition obtained by surface-crosslinking using a surface-crosslinking agent that is the same as or different from the surface-crosslinking agent used first.
- the particle size is adjusted by sieving if necessary.
- the average particle size of the obtained particles is preferably 100-600 ⁇ m, more preferably 200-500 ⁇ m.
- the content of fine particles is preferably as small as possible, the content of particles of 100 ⁇ m or less is preferably 3% by weight or less, and the content of particles of 150 ⁇ m or less is more preferably 3% by weight or less.
- Water absorbent resin composition In the water-absorbing resin composition of the present embodiment, the water-soluble unsaturated monocarboxylic acid (a1) and its salt, and the crosslinked polymer (A) having the essential structural units of the internal cross-linking agent (b) have a surface A water-absorbing resin composition surface-crosslinked with a crosslinking agent (c) and satisfying the following (1) to (3).
- Water retention capacity of 0.9% by weight saline is 15 to 60 g/g per unit weight
- Absorption amount under load of 0.9 wt% physiological saline is 10 to 27 g/g per unit weight
- Absorption rate (sec) by Vortex method is 80 or less
- the water retention capacity (g/g) of the water-absorbing resin composition with respect to 0.9% by weight saline is 15 to 60, preferably 25 to 55, from the viewpoint of the absorption performance of sanitary goods. be.
- the water retention capacity of 0.9% by weight physiological saline is measured by the method described in Examples.
- the absorption under load (g/g) of the water-absorbent resin composition in 0.9% by weight physiological saline is 10 to 27, more preferably 12 or more. If it is less than 10, leakage tends to occur during repeated use, which is not preferable. Moreover, the upper limit is preferably 26 or less from the viewpoint of performance balance with other physical properties and productivity.
- the absorption under load can be appropriately adjusted by the types and amounts of the internal cross-linking agent (b) and the surface cross-linking agent. Therefore, for example, when it is necessary to increase the absorption under load, it can be easily achieved by increasing the amounts of the internal cross-linking agent (b) and the surface cross-linking agent.
- the absorbency under load (g/g) of the water absorbent resin composition can be measured by the method described in Examples.
- the Vortex test (seconds) of the water absorbent resin composition is 80 or less.
- the lower limit is preferably as low as possible, but is not particularly limited, but is preferably 70 or less from the viewpoint of performance balance with other physical properties and productivity. Within this range, it is possible to reduce the risk of liquid leakage when used as a sanitary article.
- the vortex test (seconds) of the water absorbent resin composition can be measured by the method described in Examples.
- the crosslinked polymer (A) is formed by crosslinking the crosslinked polymer (A) obtained by polymerizing the monomer composition described in the method for producing a water absorbent resin composition with the surface crosslinking agent (c).
- the amount of the internal cross-linking agent (b) with respect to the total amount (number of moles) of the monomers (A1) and (A2) to be the above-mentioned preferable amount
- the water-retaining amount of physiological saline of the water-absorbing resin composition the absorption under load in 0.9% by weight physiological saline, and the absorption rate according to the Vortex method can be adjusted within the above ranges.
- the amount of the vinyl monomer (A2) unit in the crosslinked polymer (A) is 100 in total for the structural unit of the water-soluble unsaturated monocarboxylic acid (a1) and the structural unit of its salt, from the viewpoint of absorption performance and the like. It is preferably 0 to 5 mol parts, more preferably 0 to 3 mol parts, particularly preferably 0 to 2 mol parts, and particularly preferably 0 to 1.5 mol parts with respect to mol parts, from the viewpoint of absorption performance and the like. Therefore, it is most preferable that the content of the vinyl monomer (A2) unit is 0 mol parts.
- the amount of the internal cross-linking agent (b) in the crosslinked polymer (A) is, from the viewpoint of absorption performance and the like, a total of 100 of the constituent units of the water-soluble unsaturated monocarboxylic acid (a1) and the constituent units of its salt. 100 molar parts, and when using other vinyl monomers (A2), a total of 100 of the structural units of the water-soluble unsaturated monocarboxylic acid (a1) and salts thereof, and the structural units of the vinyl monomer (A2) It is preferably from 0.001 to 5 molar parts, more preferably from 0.005 to 3 molar parts, and particularly preferably from 0.005 to 1 molar part.
- the substance amount of the internal cross-linking agent other than the internal cross-linking agent (b) is preferably 0 to 50 mol parts per 100 mol parts of the internal cross-linking agent (b) from the viewpoint of decomposition performance.
- the water-absorbing resin composition may contain some other components such as residual solvent and residual cross-linking components within a range that does not impair its performance.
- the other components include preservatives, antifungal agents, antibacterial agents, ultraviolet absorbers, antioxidants, colorants, fragrances, deodorants, liquid permeability improvers, inorganic powders and organic fibers. and the like.
- the amount is usually 5% by weight or less based on the weight of the water absorbent resin composition.
- the water absorbent resin composition preferably contains at least one typical element selected from the group consisting of iodine, tellurium, antimony and bismuth as the other component.
- the content of the typical element in the water absorbent resin composition is preferably 0.0005 to 0.1% by weight from the viewpoint of water absorption performance. 001 to 0.05% by weight is more preferred.
- the shape of the water-absorbing resin composition is not particularly limited, and examples thereof include irregular crushed shape, scaly shape, pearl-like shape, and rice grain-like shape. Of these, irregularly crushed forms are preferred from the viewpoints of good entanglement with fibrous materials for use in paper diapers and the like, and no fear of falling off from fibrous materials.
- the water-absorbing resin composition can be a component of sanitary products together with pulp fibers.
- sanitary products include paper diapers, sanitary napkins, incontinence products, and pet sheets.
- the method for producing the sanitary goods is the same as the known ones (described in JP-A-2003-225565, JP-A-2006-131767, JP-A-2005-097569, etc.).
- the internal cross-linking agent (b) site is selectively decomposed by an oxidizing agent, and the decomposed product can be water-soluble.
- the method for treating the water absorbent resin composition of the present embodiment includes a decomposition step of decomposing the water absorbent resin composition with an oxidizing agent.
- the crosslinked polymer (A) contained in the water absorbent resin composition is depolymerized by an oxidizing agent.
- the oxidizing agent used in the decomposition step is not particularly limited as long as it can decompose and depolymerize the crosslinked polymer (A).
- the water absorbent resin composition to be subjected to the decomposition treatment process may retain water.
- the crosslinked polymer (A) is depolymerized by selectively breaking specific bonds. Decomposition products produced by depolymerization are dissolved or suspended in the water retained in the water absorbent resin composition before decomposition.
- oxidizing agent used to decompose the water absorbent resin composition examples include hydrogen peroxide, ozone, hypochlorite, chlorite, chlorate, perchlorate, percarbonate, percarbonate, It is preferably one or more selected from the group consisting of borates, percarboxylic acids and nitroxyl radical compounds.
- atmospheric oxygen can also act as an oxidizing agent, but it is preferable to use an oxidizing agent other than oxygen as exemplified above. more preferred.
- the decomposition of the water-absorbing resin composition may be performed in an environment where simple oxygen coexists.
- the hydrogen peroxide is preferably dissolved in water to form a hydrogen peroxide aqueous solution, but it may be dissolved in an organic solvent.
- An aqueous solution of hydrogen peroxide having a concentration of 30% by weight is readily available, and it is preferable because it requires only a small amount of liquid.
- Hypochlorite, chlorite, chlorate, perchlorate, percarbonate, perborate, etc. are preferably alkali metal salts or alkaline earth metal salts because they are readily available, and sodium salts. , potassium salt, and calcium salt, and particularly preferably sodium hypochlorite (NaClO). These salts can also be dissolved in a solvent such as water and used. Furthermore, hypochlorite, chlorite, chlorate, and perchloric acid are also used when treating the crosslinked polymer (A) obtained by removing from used diapers or contained in used diapers.
- the water-absorbing resin composition When the water-absorbing resin composition is contained in sanitary goods, it is preferable, from the viewpoint of processing efficiency, to separate the water-absorbing resin composition from the sanitary goods and then decompose it.
- the water absorbent resin composition can be separated from the sanitary goods by a known method.
- a known method for separating the water absorbent resin composition from sanitary goods for example, in order to recover pulp from used diapers, an aqueous sodium hypochlorite solution and an aqueous potassium permanganate solution are used to absorb water.
- a method of water solubilization by breaking the bond of the resin composition JP 2021-001783), a method using a decomposing agent containing periodate (JP 2001-31659), using an alkaline aqueous solution (JP 2020-049398), and by using an acid such as citric acid as an inactivating aqueous solution, the neutralized portion in the water-absorbing resin composition is converted to an unneutralized state.
- a method of converting and promoting separation from the pulp JP 2019-085686, putting the pulverized diaper in a tank containing water, and utilizing the difference in specific gravity and sedimentation speed between the pulp and the water absorbent resin composition.
- a separation method Japanese Unexamined Patent Application Publication No. 2002-273731 can also be mentioned.
- the pulverizing step is a step of pulverizing sanitary goods to obtain pulverized products.
- a known pulverizer or crusher can be used, for example, a disposer-type crusher used in a kitchen garbage crusher (a turntable that rotates at high speed throws the sanitary product on the wall surface, and the peripheral edge of the turntable Crushing with a fixed or variable hammer and a fixed blade on the wall), cutter mill, single shaft crusher, twin shaft crusher, coaxial crusher, hammer crusher, ball mill, etc. Since materials for sanitary products include plastic sheets, non-woven fabrics, and stretchable materials, a disposer-type crusher or cutter mill that cuts with a blade while rotating at high speed is particularly suitable.
- the pulverized sanitary products may be contained in the aqueous suspension.
- Methods for obtaining an aqueous suspension containing pulverized sanitary products include a method of adding water to swell the sanitary products and then pulverizing them, a method of pulverizing by adding water while pulverizing, and a method of adding water after pulverizing.
- the preferred range of the size of the pulverized product of the sanitary product depends on the separation and recovery method by the centrifugal dehydration step, but from the viewpoint of transportability with a water stream, the length of one piece of the sanitary product is preferably 100 mm or less. be.
- the size of the pulverized product can be appropriately adjusted depending on the type of pulverizer or crusher described above, processing conditions, and the like.
- a dehydration treatment step of the water-absorbent resin composition may be further included in the treatment process (Japanese Patent Application Laid-Open No. 2020-116569).
- the dehydration step includes adding the water-absorbent resin composition to a treatment liquid containing an acid and/or a water-soluble polyvalent metal compound. It is preferable to have a dehydration pretreatment step of immersing and a centrifugal dehydration step of centrifugally dehydrating the water absorbent resin composition that has undergone the dehydration pretreatment step.
- the water absorbent resin composition to be subjected to the dehydration pretreatment step also includes the water absorbent resin composition contained in sanitary products such as used sanitary products and unused sanitary products.
- the water-absorbent resin compositions obtained in Examples and Comparative Examples have a water retention capacity with respect to 0.9 wt% physiological saline, an absorption capacity under load with respect to 0.9 wt% physiological saline, and an absorption rate according to the Vortex method, and The moisture absorption blocking rate was measured in a room at 25 ⁇ 2° C. and a humidity of 50 ⁇ 10% by the following methods.
- the temperature of the physiological saline used was previously adjusted to 25°C ⁇ 2°C.
- ⁇ Moisture absorption blocking rate> 5.00 g of the water-absorbent resin composition was placed uniformly in an aluminum cylindrical dish with a diameter of 5 cm, and allowed to stand in a constant temperature and humidity bath at 30 ⁇ 1° C. and 80 ⁇ 5% RH for 3 hours. Next, the aluminum cylindrical dish was gently removed from the constant temperature and humidity chamber, and a metal sieve with a diameter of 8.0 cm and an opening of 1.4 mm was attached to the bottom of the prepared metal sieve tray (diameter: 8.0 cm). The entire amount of 5.00 g of this water-absorbing resin composition was carefully transferred to the apparatus F, in which the saucer and the metal sieve were combined, so as not to lose its shape.
- the agglomeration sieve which is an accessory of the powder tester (manufactured by Hosokawa Micron Corporation, model number PT-X), is placed on the device F, the sieve holder is attached, and the conditions of the "vibration unit" in the powder tester are changed to amplitude was 0.8 mm, the operating time was 40 seconds, the slowdown was 0 seconds, and the frequency was 60 Hz.
- Example 1 157 parts (2.18 mol parts) of acrylic acid, 0.400 parts (0.0028 mol parts) of the internal cross-linking agent (b-1) (N,N-diacryloylhydrazine) and 344.65 parts of deionized water are stirred. - A polymerization solution was prepared by mixing. A polymerization solution whose temperature was adjusted to 24.9° C. was used as a measurement sample, and the pH measured using a pH meter (LAQUA desktop pH/conductivity meter, model F-74S, manufactured by Horiba, Ltd.) was 1.8. rice field. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C.
- b-1 N,N-diacryloylhydrazine
- Example 2 the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 15.2 parts (0.109 mol parts). A product (P-2) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
- Example 3 the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 0.004 parts (0.000029 mol parts). A product (P-3) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
- Example 6 157 parts (2.18 mol parts) of acrylic acid, 0.400 parts (0.0028 mol parts) of internal cross-linking agent (b-1) (N,N-diacryloylhydrazine), 48.5 wt% sodium hydroxide aqueous solution 179.8 parts (2.18 mol parts) and 252.05 parts of deionized water were stirred and mixed to prepare a polymerization solution.
- the pH of the polymerization solution measured in the same manner as in Example 1 was 7.0. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C.
- Example 7 157 parts of acrylic acid (2.18 mol parts), 0.400 parts of internal cross-linking agent (b-1) (N,N-diacryloylhydrazine), 180.3 parts of 48.5% by weight aqueous sodium hydroxide solution (2. 19 mol parts) and 252.05 parts of deionized water were stirred and mixed to prepare a polymerization solution.
- the pH of the polymerization solution measured in the same manner as in Example 1 was 10.2. Subsequently, nitrogen was introduced into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.045 part of 4,4′-azobis(4-cyanovaleric acid) was added.
- Aqueous solution adiabatic polymerization was initiated by mixing and putting into a heat insulating container which is a reaction vessel, and water-containing gel (3) was obtained by polymerizing for about 10 hours.
- water-containing gel (3) was obtained by polymerizing for about 10 hours.
- 13.9 parts of a 98% by weight aqueous solution of sulfuric acid was added to 502.27 parts of this hydrous gel (3) while being finely chopped with a mincing machine, followed by mixing with a ventilated band dryer ⁇ 150° C., wind speed of 2 m/sec. ⁇ to obtain a dry product.
- the dried product was pulverized with a juicer mixer to obtain a particulate dried product (3).
- Example 8 > 157 parts (2.18 mol parts) of acrylic acid, 0.0161 parts (0.00012 mol parts) of internal cross-linking agent (b-1) (N,N-diacryloylhydrazine), 48.5% by weight aqueous sodium hydroxide solution
- b-1 internal cross-linking agent
- a polymerization solution was prepared by stirring and mixing 180.4 parts (2.19 mol parts) and 252.05 parts of deionized water. The pH of the polymerization solution measured in the same manner as in Example 1 was 11.9. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3 ° C.
- Example 9 157 parts (2.18 mol parts) of acrylic acid, 0.0161 parts (0.00012 parts) of internal crosslinking agent (b-1) (N,N-diacryloylhydrazine), 30.1 parts of 98% by weight sulfuric acid water, and A polymerization solution was prepared by stirring and mixing 340.65 parts of deionized water. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.1. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.63 parts of 1% aqueous hydrogen peroxide solution and 1.1774 parts of 2% aqueous ascorbic acid solution were added.
- b-1 internal crosslinking agent
- the dried product was pulverized with a juicer mixer to obtain a particulate dried product (5).
- the mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-9) of the present invention.
- Example 10 the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 9.15 parts (0.0654 mol parts). A product (P-10) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
- Example 11 the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 3.05 parts (0.0218 mol parts). A product (P-11) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
- This water-containing gel was decanted with water three times and then Soxhlet washed with methanol for 22 hours to obtain a solid. This solid matter was vacuum-dried to obtain a dried product. This dried product was pulverized with a juicer mixer to obtain a particulate dried product (6). The obtained particulate dried body (6) was used as a water absorbent resin composition (R-1) for comparison.
- Table 1 shows the evaluation results.
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Abstract
The present invention provides a method for producing a water absorbent resin composition, the method comprising: a polymerization step in which a hydrous gel that contains a crosslinked polymer (A) is obtained by polymerizing a monomer composition, which contains one or more monomers (A1) selected from the group consisting of a water-soluble unsaturated monocarboxylic acid (a1), a salt thereof and a monomer (a2) that is formed into the water-soluble unsaturated monocarboxylic acid (a1) by means of hydrolysis, and an internal crosslinking agent (b) represented by general formula (1), in a polymerization solution that contains the monomer composition and has a pH of 1 to 12; and a surface crosslinking step in which the crosslinked polymer (A) is crosslinked by means of a surface crosslinking agent (c). The present invention is able to provide a method for producing a water absorbent resin composition which is capable of contributing to resource saving and environmental load reduction, and which is capable of efficiently decomposing a crosslinked polymer by means of an oxidant, while achieving a water absorption performance that is necessary when in use.
Description
本発明は、吸水性樹脂組成物の製造方法に関する。
The present invention relates to a method for producing a water absorbent resin composition.
衛生用品の使用量が増加するにつれて、使用後の衛生用品のごみ処理問題が深刻な問題となりつつある。衛生用品、特に紙おむつは社会が少子高齢化する時代に欠かせない用品として急激に普及し、その消費は急増している。
As the amount of sanitary products used increases, the issue of garbage disposal for sanitary products after use is becoming a serious problem. Sanitary goods, especially paper diapers, have rapidly spread as indispensable goods in an age of declining birthrate and aging society, and their consumption is increasing rapidly.
使用後の衛生用品のごみ処理に関し、紙おむつなどは、通常、焼却処理されているが、おむつ中の水分の割合は約８割近くであるため、焼却には大きな燃焼エネルギーが必要となる。このため処理には焼却炉自体に大きな負荷がかかり、結果として焼却炉の寿命を短くする原因に繋がる。また、焼却処理は大気汚染や地球の温暖化に繋がり、環境に負荷をかける要因にもなるため、改善が強く望まれている。また、介護の現場では、紙おむつの廃棄にかかる介護士への負担の軽減が課題になっている。
Regarding the disposal of sanitary goods after use, paper diapers are usually incinerated, but since the percentage of water in diapers is close to 80%, incineration requires a large amount of combustion energy. For this reason, the treatment places a heavy load on the incinerator itself, which leads to shortening of the life of the incinerator. In addition, since incineration leads to air pollution and global warming, and is also a factor that places a burden on the environment, improvement is strongly desired. Moreover, in the field of nursing care, how to reduce the burden on caregivers to dispose of disposable diapers has become an issue.
上記課題に対し、使用済み衛生用品から部材を回収し、再利用するための検討が進められている。通常、衛生用品はパルプ繊維と吸水性樹脂粒子から構成される吸収体を含み、部材として再利用するためにはパルプ繊維と吸水性樹脂粒子を分離する必要がある。しかし、使用済み衛生用品の吸収体中の吸水性樹脂粒子は水を吸収して膨潤したゲル状態となるため、そのままでは分離が難しい。そこで、吸水性樹脂粒子を分解して可溶化し、パルプ繊維と吸水性樹脂粒子の可溶化成分を分離する技術が提案されており、例えば、パルプ繊維及び吸水性樹脂粒子を含む衛生用品をオゾン含有水溶液で処理することで、吸水性樹脂粒子を分解・可溶化した後、パルプ繊維を回収する技術（特許文献１及び２）がある。また、吸水性樹脂粒子を分解して可溶化する技術としては、分解方法として過酸化水素等の酸化剤を使用する技術、更に電磁波を照射する方法（特許文献３～６）が知られている。また、架橋高分子化合物を酸化剤と反応させ、架橋剤単位部分のみを選択的に切断して水溶性のポリアクリル酸（塩）へと変換する方法が報告されている（特許文献７）。さらに、廃棄時の負担軽減のために、介護現場で使用済みの紙おむつを専用の設備によって処理し、殺菌処理および脱水処理を行うことで、廃棄時における臭気低減や廃棄物量の削減に対する取り組みも検討されている。
In response to the above issues, studies are underway to collect and reuse components from used sanitary products. Sanitary products usually contain an absorbent body composed of pulp fibers and water-absorbent resin particles, and the pulp fibers and water-absorbent resin particles must be separated in order to reuse them as members. However, since the water-absorbing resin particles in the absorbent body of the used sanitary goods absorb water and become swollen gel state, it is difficult to separate them as they are. Therefore, a technique has been proposed to decompose and solubilize the water-absorbent resin particles and separate the solubilized components of the pulp fibers and the water-absorbent resin particles. There is a technique (Patent Documents 1 and 2) in which pulp fibers are recovered after decomposing and solubilizing water-absorbent resin particles by treatment with a contained aqueous solution. In addition, as a technique for decomposing and solubilizing water-absorbing resin particles, a technique using an oxidizing agent such as hydrogen peroxide as a decomposition method, and a method of irradiating electromagnetic waves (Patent Documents 3 to 6) are known. . Also, a method has been reported in which a crosslinked polymer compound is reacted with an oxidizing agent to selectively cut only the crosslinker unit portion to convert it into a water-soluble polyacrylic acid (salt) (Patent Document 7). Furthermore, in order to reduce the burden at the time of disposal, we are considering measures to reduce odors at the time of disposal and reduce the amount of waste by treating used disposable diapers at nursing care sites with dedicated equipment, sterilizing and dehydrating. It is
前述した使用済み衛生用品の再利用技術は、パルプ繊維を回収し、再生パルプとして利用することが目的であり、吸水性樹脂粒子の分解・可溶化成分は廃棄されるか又は固形燃料等でリサイクルされている場合がほとんどであり、リサイクルの観点からは十分とは言い難い。また、電磁波照射によって吸水性樹脂粒子をそのモノマー主成分であるアクリル酸及び／又はその塩やオリゴマー体に分解する例もあるが、前処理として、吸水性樹脂粒子を超純水で１０倍程度に膨潤させる操作を必要とする。これは分解後に得られるアクリル酸及び／又はその塩やオリゴマー体の濃度が低下するため、アクリル酸及び／又はその塩やオリゴマー体を得るという観点から非効率であり、再利用の観点から改善する余地がある。
The purpose of the recycling technology for used sanitary products mentioned above is to collect pulp fibers and use them as recycled pulp. In most cases, it is not sufficient from the viewpoint of recycling. There is also an example in which the water-absorbent resin particles are decomposed into acrylic acid, which is the main monomer component, and/or its salts and oligomers by electromagnetic irradiation. It requires an operation to swell to This is inefficient from the viewpoint of obtaining acrylic acid and/or its salts and oligomers because the concentration of acrylic acid and/or its salts and oligomers obtained after decomposition decreases, and is improved from the viewpoint of recycling. There is room.
また、特許文献７で得られた架橋高分子化合物は、架橋剤を酸化剤で切断することでアクリル酸オリゴマーを得ることは可能であるが、本来吸水性樹脂に期待される吸水性能が十分でないとともに吸湿ブロッキングが発生するため酸化剤による分解効率が悪い。さらに、衛生物品に使用した際に肌への刺激性が強いことが想定され、実使用の観点から問題がある。さらに、介護現場で取り組みが始まっている使用済み紙おむつを処理して廃棄する際には、脱水処理時に紙おむつが破け、中に含まれる吸水性樹脂が漏れ出して下水に流れ込むことで、海洋汚染を引き起こし環境負荷に繋がる懸念が指摘されている。
In addition, although it is possible to obtain an acrylic acid oligomer from the crosslinked polymer compound obtained in Patent Document 7 by cleaving the crosslinker with an oxidizing agent, the water absorption performance originally expected for the water absorbent resin is not sufficient. Since moisture absorption blocking also occurs at the same time, the decomposition efficiency by an oxidizing agent is poor. Furthermore, it is assumed that when used in sanitary goods, it is highly irritating to the skin, which poses a problem from the standpoint of actual use. Furthermore, when treating and disposing of used disposable diapers, which nursing care sites have begun to work on, the disposable diapers break during the dehydration process, and the water-absorbing resin contained in them leaks out and flows into the sewage, resulting in marine pollution. Concerns have been pointed out that this will lead to environmental impacts.
本発明の目的は、使用時には必要な吸水性能を満たしつつ、酸化剤によって架橋重合体を効率的に分解処理でき、省資源及び環境負荷低減に寄与することができる吸水性樹脂組成物の製造方法を提供することである。
An object of the present invention is to provide a method for producing a water-absorbing resin composition that can efficiently decompose a crosslinked polymer with an oxidizing agent while satisfying the required water-absorbing performance at the time of use, and that can contribute to resource saving and environmental load reduction. is to provide
本発明は、水溶性不飽和モノカルボン酸（ａ１）及びその塩、並びに加水分解により前記水溶性不飽和モノカルボン酸（ａ１）となるモノマー（ａ２）からなる群より選ばれる１種以上のモノマー（Ａ１）と、下記一般式（１）で表される内部架橋剤（ｂ）と、を含む単量体組成物を、当該単量体組成物を含み、ｐＨが１～１２である重合溶液中で重合し、架橋重合体（Ａ）を含む含水ゲルを得る重合工程と、前記架橋重合体（Ａ）を表面架橋剤（ｃ）によって架橋する表面架橋工程を有する吸水性樹脂組成物の製造方法である。
（一般式（１）中、Ｒ１は水素、アルキル基、ヒドロキシ基、アミノ基、メルカプト基、置換カルボニル基、並びにヒドロキシ基、アミノ基、メルカプト基、及び置換カルボニル基から選択される１種類以上を置換基としてもつ任意のアルキル基から選択される１種類以上である。）
The present invention provides one or more monomers selected from the group consisting of water-soluble unsaturated monocarboxylic acids (a1) and salts thereof, and monomers (a2) that become the water-soluble unsaturated monocarboxylic acids (a1) by hydrolysis. A polymerization solution containing a monomer composition containing (A1) and an internal cross-linking agent (b) represented by the following general formula (1) and having a pH of 1 to 12 Manufacture of a water-absorbing resin composition having a polymerization step of polymerizing in a water-containing gel containing a crosslinked polymer (A) and a surface cross-linking step of cross-linking the cross-linked polymer (A) with a surface cross-linking agent (c) The method.
(In general formula (1), R1 is hydrogen, an alkyl group, a hydroxy group, an amino group, a mercapto group, a substituted carbonyl group, and one or more selected from a hydroxy group, an amino group, a mercapto group, and a substituted carbonyl group. It is one or more selected from arbitrary alkyl groups having as substituents.)
本発明によれば、優れた吸水性能を有しつつ、酸化剤によって架橋重合体が効率的に分解され、省資源及び環境負荷低減に寄与することができる吸水性樹脂組成物の製造方法を提供することができる。
According to the present invention, there is provided a method for producing a water-absorbing resin composition that has excellent water-absorbing performance and efficiently decomposes a crosslinked polymer with an oxidizing agent, thereby contributing to resource saving and reduction of environmental load. can do.
＜吸水性樹脂組成物の製造方法＞
本実施形態の吸水性樹脂組成物の製造方法は、水溶性不飽和モノカルボン酸（ａ１）及びその塩、並びに加水分解により前記水溶性不飽和モノカルボン酸（ａ１）となるモノマー（ａ２）からなる群より選ばれる１種以上のモノマー（Ａ１）と、下記一般式（１）で表される内部架橋剤（ｂ）と、を含む単量体組成物を、当該単量体組成物を含み、ｐＨが１～１２である重合溶液中で重合し、架橋重合体（Ａ）を含む含水ゲルを得る重合工程と、前記架橋重合体（Ａ）を表面架橋剤（ｃ）によって架橋する表面架橋工程を有する。
（一般式（１）中、Ｒ１は水素、アルキル基、ヒドロキシ基、アミノ基、メルカプト基、置換カルボニル基、並びにヒドロキシ基、アミノ基、メルカプト基、及び置換カルボニル基から選択される１種類以上を置換基としてもつ任意のアルキル基から選択される１種類以上である。）
<Method for producing water absorbent resin composition>
The method for producing a water-absorbent resin composition of the present embodiment comprises a water-soluble unsaturated monocarboxylic acid (a1) and a salt thereof, and a monomer (a2) that becomes the water-soluble unsaturated monocarboxylic acid (a1) by hydrolysis. a monomer composition containing one or more monomers (A1) selected from the group consisting of and an internal cross-linking agent (b) represented by the following general formula (1): , a polymerization step of polymerizing in a polymerization solution having a pH of 1 to 12 to obtain a water-containing gel containing a crosslinked polymer (A); have a process.
(In general formula (1), R1 is hydrogen, an alkyl group, a hydroxy group, an amino group, a mercapto group, a substituted carbonyl group, and one or more selected from a hydroxy group, an amino group, a mercapto group, and a substituted carbonyl group. It is one or more selected from arbitrary alkyl groups having as substituents.)
本実施形態の吸水性樹脂組成物の製造方法は、水溶性不飽和モノカルボン酸（ａ１）及びその塩、並びに加水分解により前記水溶性不飽和モノカルボン酸（ａ１）となるモノマー（ａ２）からなる群より選ばれる１種以上のモノマー（Ａ１）と、下記一般式（１）で表される内部架橋剤（ｂ）と、を含む単量体組成物を、当該単量体組成物を含み、ｐＨが１～１２である重合溶液中で重合し、架橋重合体（Ａ）を含む含水ゲルを得る重合工程と、前記架橋重合体（Ａ）を表面架橋剤（ｃ）によって架橋する表面架橋工程を有する。
The method for producing a water-absorbent resin composition of the present embodiment comprises a water-soluble unsaturated monocarboxylic acid (a1) and a salt thereof, and a monomer (a2) that becomes the water-soluble unsaturated monocarboxylic acid (a1) by hydrolysis. a monomer composition containing one or more monomers (A1) selected from the group consisting of and an internal cross-linking agent (b) represented by the following general formula (1): , a polymerization step of polymerizing in a polymerization solution having a pH of 1 to 12 to obtain a water-containing gel containing a crosslinked polymer (A); have a process.
本実施形態の吸水性樹脂組成物の製造方法によれば、優れた吸水性能を有しつつ、酸化剤によって架橋重合体が効率的に分解され、省資源及び環境負荷低減に寄与する吸水性樹脂組成物を製造することができる。
According to the method for producing a water-absorbing resin composition of the present embodiment, the water-absorbing resin has excellent water-absorbing performance, and the crosslinked polymer is efficiently decomposed by the oxidizing agent, contributing to resource saving and environmental load reduction. Compositions can be manufactured.
〔重合工程〕
本実施形態の吸水性樹脂組成物の製造方法は、水溶性不飽和モノカルボン酸（ａ１）及びその塩、並びに加水分解により前記水溶性不飽和モノカルボン酸（ａ１）となるモノマー（ａ２）からなる群より選ばれる１種以上のモノマー（Ａ１）と、下記一般式（１）で表される内部架橋剤（ｂ）と、を含む単量体組成物を、当該単量体組成物を含み、ｐＨが１～１２である重合溶液中で重合し、架橋重合体（Ａ）を含む含水ゲルを得る重合工程を有する。 [Polymerization process]
The method for producing a water-absorbent resin composition of the present embodiment comprises a water-soluble unsaturated monocarboxylic acid (a1) and a salt thereof, and a monomer (a2) that becomes the water-soluble unsaturated monocarboxylic acid (a1) by hydrolysis. a monomer composition containing one or more monomers (A1) selected from the group consisting of and an internal cross-linking agent (b) represented by the following general formula (1): , and a polymerization step of polymerizing in a polymerization solution having a pH of 1 to 12 to obtain a hydrous gel containing the crosslinked polymer (A).
本実施形態の吸水性樹脂組成物の製造方法は、水溶性不飽和モノカルボン酸（ａ１）及びその塩、並びに加水分解により前記水溶性不飽和モノカルボン酸（ａ１）となるモノマー（ａ２）からなる群より選ばれる１種以上のモノマー（Ａ１）と、下記一般式（１）で表される内部架橋剤（ｂ）と、を含む単量体組成物を、当該単量体組成物を含み、ｐＨが１～１２である重合溶液中で重合し、架橋重合体（Ａ）を含む含水ゲルを得る重合工程を有する。 [Polymerization process]
The method for producing a water-absorbent resin composition of the present embodiment comprises a water-soluble unsaturated monocarboxylic acid (a1) and a salt thereof, and a monomer (a2) that becomes the water-soluble unsaturated monocarboxylic acid (a1) by hydrolysis. a monomer composition containing one or more monomers (A1) selected from the group consisting of and an internal cross-linking agent (b) represented by the following general formula (1): , and a polymerization step of polymerizing in a polymerization solution having a pH of 1 to 12 to obtain a hydrous gel containing the crosslinked polymer (A).
［モノマー（Ａ１）］
（水溶性不飽和モノカルボン酸（ａ１）及びその塩）
前記水溶性不飽和モノカルボン酸（ａ１）は、水溶性を有する不飽和モノカルボン酸であれば特に限定されずに用いることができる。前記水溶性不飽和モノカルボン酸（ａ１）は、架橋体にした際の吸水性能や入手の容易さの観点から、アクリル酸、メタクリル酸、及びクロトン酸からなる郡より選ばれる少なくとも１種が好ましく、アクリル酸、メタクリル酸がより好ましい。 [Monomer (A1)]
(Water-soluble unsaturated monocarboxylic acid (a1) and its salt)
The water-soluble unsaturated monocarboxylic acid (a1) can be used without particular limitation as long as it is a water-soluble unsaturated monocarboxylic acid. The water-soluble unsaturated monocarboxylic acid (a1) is preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, and crotonic acid, from the viewpoint of water absorption performance when crosslinked and ease of availability. , acrylic acid, and methacrylic acid are more preferred.
（水溶性不飽和モノカルボン酸（ａ１）及びその塩）
前記水溶性不飽和モノカルボン酸（ａ１）は、水溶性を有する不飽和モノカルボン酸であれば特に限定されずに用いることができる。前記水溶性不飽和モノカルボン酸（ａ１）は、架橋体にした際の吸水性能や入手の容易さの観点から、アクリル酸、メタクリル酸、及びクロトン酸からなる郡より選ばれる少なくとも１種が好ましく、アクリル酸、メタクリル酸がより好ましい。 [Monomer (A1)]
(Water-soluble unsaturated monocarboxylic acid (a1) and its salt)
The water-soluble unsaturated monocarboxylic acid (a1) can be used without particular limitation as long as it is a water-soluble unsaturated monocarboxylic acid. The water-soluble unsaturated monocarboxylic acid (a1) is preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, and crotonic acid, from the viewpoint of water absorption performance when crosslinked and ease of availability. , acrylic acid, and methacrylic acid are more preferred.
前記水溶性不飽和モノカルボン酸（ａ１）の塩としては、アルカリ金属（リチウム、ナトリウム及びカリウム等）塩、アルカリ土類金属（マグネシウム及びカルシウム等）塩及びアンモニウム（ＮＨ４）塩等が挙げられる。これらの塩の内、吸収性能等の観点から、アルカリ金属塩及びアンモニウム塩が好ましく、更に好ましいのはアルカリ金属塩、特に好ましいのはナトリウム塩である。
Examples of the salt of the water-soluble unsaturated monocarboxylic acid (a1) include alkali metal (lithium, sodium, potassium, etc.) salts, alkaline earth metal (magnesium, calcium, etc.) salts and ammonium (NH 4 ) salts. . Among these salts, alkali metal salts and ammonium salts are preferable, alkali metal salts are more preferable, and sodium salts are particularly preferable, from the viewpoint of absorption performance and the like.
（モノマー（ａ２））
加水分解により前記水溶性不飽和モノカルボン酸（ａ１）となるモノマー（ａ２）を前記水溶性不飽和モノカルボン酸（ａ１）とともに、あるいはその代わりに使用することができる。前記モノマー（ａ２）は特に限定はなく、加水分解によりカルボキシ基となる加水分解性置換基を１個有するモノマー等が例示できる。前記加水分解性置換基としては、酸無水物を含む基（１，３－オキソ－１－オキサプロピレン基、－ＣＯＯ－ＣＯ－）、エステル結合を含む基（アルキルオキシカルボニル、ビニルオキシカルボニル、アリルオキシカルボニル又はプロペニルオキシカルボニル、－ＣＯＯＲ）及びシアノ基等が挙げられる。なお、Ｒは炭素数１～３のアルキル基（メチル、エチル及びプロピル）、ビニル、アリル及びプロペニルである。 (monomer (a2))
The monomer (a2) that becomes the water-soluble unsaturated monocarboxylic acid (a1) by hydrolysis can be used together with or instead of the water-soluble unsaturated monocarboxylic acid (a1). The monomer (a2) is not particularly limited, and a monomer having one hydrolyzable substituent that becomes a carboxy group by hydrolysis can be exemplified. Examples of the hydrolyzable substituent include acid anhydride-containing groups (1,3-oxo-1-oxapropylene group, -COO-CO-), ester bond-containing groups (alkyloxycarbonyl, vinyloxycarbonyl, allyl oxycarbonyl or propenyloxycarbonyl, —COOR), cyano group and the like. R is an alkyl group having 1 to 3 carbon atoms (methyl, ethyl and propyl), vinyl, allyl and propenyl.
加水分解により前記水溶性不飽和モノカルボン酸（ａ１）となるモノマー（ａ２）を前記水溶性不飽和モノカルボン酸（ａ１）とともに、あるいはその代わりに使用することができる。前記モノマー（ａ２）は特に限定はなく、加水分解によりカルボキシ基となる加水分解性置換基を１個有するモノマー等が例示できる。前記加水分解性置換基としては、酸無水物を含む基（１，３－オキソ－１－オキサプロピレン基、－ＣＯＯ－ＣＯ－）、エステル結合を含む基（アルキルオキシカルボニル、ビニルオキシカルボニル、アリルオキシカルボニル又はプロペニルオキシカルボニル、－ＣＯＯＲ）及びシアノ基等が挙げられる。なお、Ｒは炭素数１～３のアルキル基（メチル、エチル及びプロピル）、ビニル、アリル及びプロペニルである。 (monomer (a2))
The monomer (a2) that becomes the water-soluble unsaturated monocarboxylic acid (a1) by hydrolysis can be used together with or instead of the water-soluble unsaturated monocarboxylic acid (a1). The monomer (a2) is not particularly limited, and a monomer having one hydrolyzable substituent that becomes a carboxy group by hydrolysis can be exemplified. Examples of the hydrolyzable substituent include acid anhydride-containing groups (1,3-oxo-1-oxapropylene group, -COO-CO-), ester bond-containing groups (alkyloxycarbonyl, vinyloxycarbonyl, allyl oxycarbonyl or propenyloxycarbonyl, —COOR), cyano group and the like. R is an alkyl group having 1 to 3 carbon atoms (methyl, ethyl and propyl), vinyl, allyl and propenyl.
なお、本明細書において、水溶性とは、２５℃の水１００ｇに少なくとも１００ｇ溶解することを意味する。また、前記モノマー（ａ２）における加水分解性とは、水及び必要により触媒（酸又は塩基等）の作用により加水分解され、水溶性になる性質を意味する。前記モノマー（ａ２）の加水分解は、重合中、重合後及びこれらの両方のいずれで行っても良いが、得られる吸水性樹脂組成物の吸収性能の観点から、重合後が好ましい。
In this specification, "water-soluble" means that at least 100 g dissolves in 100 g of water at 25°C. Further, the hydrolyzability of the monomer (a2) means the property of being hydrolyzed by the action of water and, if necessary, a catalyst (acid, base, etc.) to become water-soluble. The hydrolysis of the monomer (a2) may be carried out during polymerization, after polymerization, or both of them, but from the viewpoint of the absorption performance of the resulting water-absorbent resin composition, it is preferably carried out after polymerization.
前記単量体組成物は、前記モノマー（Ａ１）の他に、これらと共重合可能なその他のビニルモノマー（Ａ２）を含有することができる。前記ビニルモノマー（Ａ２）は１種を単独で用いても、２種以上を併用してもよい。
The monomer composition may contain, in addition to the monomer (A1), another vinyl monomer (A2) copolymerizable therewith. One of the vinyl monomers (A2) may be used alone, or two or more of them may be used in combination.
前記ビニルモノマー（Ａ２）としては特に限定はなく、公知（例えば、特許第３６４８５５３号公報の００２８～００２９段落に開示されている疎水性ビニルモノマー、特開２００３－１６５８８３号公報の００２５段落及び特開２００５－７５９８２号公報の００５８段落に開示されているビニルモノマー等）の疎水性ビニルモノマー等が使用でき、具体的には例えば下記の（ｉ）～（ｉｉｉ）のビニルモノマー等が使用できる。
（ｉ）炭素数８～３０の芳香族エチレン性モノマー
スチレン、α－メチルスチレン、ビニルトルエン及びヒドロキシスチレン等のスチレン、並びにビニルナフタレン、並びにジクロルスチレン等のスチレンのハロゲン置換体等。
（ｉｉ）炭素数２～２０の脂肪族エチレン性モノマー
アルケン（エチレン、プロピレン、ブテン、イソブチレン、ペンテン、ヘプテン、ジイソブチレン、オクテン、ドデセン及びオクタデセン等）；並びにアルカジエン（ブタジエン及びイソプレン等）等。
（ｉｉｉ）炭素数５～１５の脂環式エチレン性モノマー
モノエチレン性不飽和モノマー（ピネン、リモネン及びインデン等）；並びにポリエチレン性ビニルモノマー［シクロペンタジエン、ビシクロペンタジエン及びエチリデンノルボルネン等］等。 The vinyl monomer (A2) is not particularly limited, and is known (for example, hydrophobic vinyl monomers disclosed in paragraphs 0028 to 0029 of Japanese Patent No. 3648553; 2005-75982, paragraph 0058) can be used, and specifically, vinyl monomers (i) to (iii) below can be used.
(i) Aromatic ethylenic monomer having 8 to 30 carbon atoms Styrene such as styrene, α-methylstyrene, vinyltoluene and hydroxystyrene, vinylnaphthalene, and halogen-substituted styrene such as dichlorostyrene.
(ii) Aliphatic ethylenic monomers having 2 to 20 carbon atoms Alkenes (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.); and alkadienes (butadiene, isoprene, etc.).
(iii) C5-C15 alicyclic ethylenic monomers monoethylenically unsaturated monomers (pinene, limonene, indene, etc.); and polyethylene vinyl monomers [cyclopentadiene, bicyclopentadiene, ethylidenenorbornene, etc.], and the like.
（ｉ）炭素数８～３０の芳香族エチレン性モノマー
スチレン、α－メチルスチレン、ビニルトルエン及びヒドロキシスチレン等のスチレン、並びにビニルナフタレン、並びにジクロルスチレン等のスチレンのハロゲン置換体等。
（ｉｉ）炭素数２～２０の脂肪族エチレン性モノマー
アルケン（エチレン、プロピレン、ブテン、イソブチレン、ペンテン、ヘプテン、ジイソブチレン、オクテン、ドデセン及びオクタデセン等）；並びにアルカジエン（ブタジエン及びイソプレン等）等。
（ｉｉｉ）炭素数５～１５の脂環式エチレン性モノマー
モノエチレン性不飽和モノマー（ピネン、リモネン及びインデン等）；並びにポリエチレン性ビニルモノマー［シクロペンタジエン、ビシクロペンタジエン及びエチリデンノルボルネン等］等。 The vinyl monomer (A2) is not particularly limited, and is known (for example, hydrophobic vinyl monomers disclosed in paragraphs 0028 to 0029 of Japanese Patent No. 3648553; 2005-75982, paragraph 0058) can be used, and specifically, vinyl monomers (i) to (iii) below can be used.
(i) Aromatic ethylenic monomer having 8 to 30 carbon atoms Styrene such as styrene, α-methylstyrene, vinyltoluene and hydroxystyrene, vinylnaphthalene, and halogen-substituted styrene such as dichlorostyrene.
(ii) Aliphatic ethylenic monomers having 2 to 20 carbon atoms Alkenes (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.); and alkadienes (butadiene, isoprene, etc.).
(iii) C5-C15 alicyclic ethylenic monomers monoethylenically unsaturated monomers (pinene, limonene, indene, etc.); and polyethylene vinyl monomers [cyclopentadiene, bicyclopentadiene, ethylidenenorbornene, etc.], and the like.
前記単量体組成物中の前記ビニルモノマー（Ａ２）の物質量は、吸収性能等の観点から、前記モノマー（Ａ１）１００モル部に対して、０～５モル部が好ましく、更に好ましくは０～３モル部、特に好ましくは０～２モル部、とりわけ好ましくは０～１．５モル部であり、吸収性能等の観点から、０モル部であることが最も好ましい。
The amount of the vinyl monomer (A2) in the monomer composition is preferably 0 to 5 mol parts, more preferably 0, with respect to 100 mol parts of the monomer (A1) from the viewpoint of absorption performance and the like. It is preferably 0 to 3 mol parts, particularly preferably 0 to 2 mol parts, and most preferably 0 to 1.5 mol parts, and most preferably 0 mol parts from the viewpoint of absorption performance.
［内部架橋剤（ｂ）］
前記内部架橋剤（ｂ）は、ジアシルヒドラジン骨格（一般式：Ｒ３－ＣＯＮＨＮＨＣＯ－Ｒ４。Ｒ３、及びＲ４はそれぞれ独立に任意の重合鎖）を有する。前記架橋重合体（Ａ）の構成単位である前記内部架橋剤（ｂ）が有するジアシルヒドラジン骨格は酸素以外の酸化剤と反応することで分解し、窒素とカルボン酸を生成する。この反応によって、前記架橋重合体（Ａ）において重合鎖を架橋しているジアシルヒドラジン鎖が切断されることで、前記架橋重合体（Ａ）の三次元架橋構造が解消されることでリニアな重合体へと変換されることで水溶化させることができる。 [Internal cross-linking agent (b)]
The internal cross-linking agent (b) has a diacylhydrazine skeleton (general formula: R3-CONHNHCO-R4; R3 and R4 are each independently arbitrary polymer chains). The diacylhydrazine skeleton of the internal cross-linking agent (b), which is a structural unit of the cross-linked polymer (A), is decomposed by reacting with an oxidizing agent other than oxygen to produce nitrogen and carboxylic acid. By this reaction, the diacylhydrazine chains that crosslink the polymer chains in the crosslinked polymer (A) are cut, and the three-dimensional crosslinked structure of the crosslinked polymer (A) is eliminated, resulting in a linear polymerization. It can be made water soluble by being converted into a coalescence.
前記内部架橋剤（ｂ）は、ジアシルヒドラジン骨格（一般式：Ｒ３－ＣＯＮＨＮＨＣＯ－Ｒ４。Ｒ３、及びＲ４はそれぞれ独立に任意の重合鎖）を有する。前記架橋重合体（Ａ）の構成単位である前記内部架橋剤（ｂ）が有するジアシルヒドラジン骨格は酸素以外の酸化剤と反応することで分解し、窒素とカルボン酸を生成する。この反応によって、前記架橋重合体（Ａ）において重合鎖を架橋しているジアシルヒドラジン鎖が切断されることで、前記架橋重合体（Ａ）の三次元架橋構造が解消されることでリニアな重合体へと変換されることで水溶化させることができる。 [Internal cross-linking agent (b)]
The internal cross-linking agent (b) has a diacylhydrazine skeleton (general formula: R3-CONHNHCO-R4; R3 and R4 are each independently arbitrary polymer chains). The diacylhydrazine skeleton of the internal cross-linking agent (b), which is a structural unit of the cross-linked polymer (A), is decomposed by reacting with an oxidizing agent other than oxygen to produce nitrogen and carboxylic acid. By this reaction, the diacylhydrazine chains that crosslink the polymer chains in the crosslinked polymer (A) are cut, and the three-dimensional crosslinked structure of the crosslinked polymer (A) is eliminated, resulting in a linear polymerization. It can be made water soluble by being converted into a coalescence.
前記一般式（１）における２つのＲ１は、それぞれ独立して、水素、アルキル基、ヒドロキシ基、アミノ基、メルカプト基、置換カルボニル基、並びにヒドロキシ基、アミノ基、メルカプト基、及び置換カルボニル基から選択される１種類以上を置換基としてもつ任意のアルキル基から選択される１種類以上であれば特に限定されないが、水溶液への溶解性や、吸水性樹脂組成物の吸収性能、及び入手のしやすさの観点からいずれも水素であることが好ましい。
The two R1 in the general formula (1) are each independently hydrogen, an alkyl group, a hydroxy group, an amino group, a mercapto group, a substituted carbonyl group, and a hydroxy group, an amino group, a mercapto group, and a substituted carbonyl group. It is not particularly limited as long as it is one or more selected from any alkyl group having one or more selected as substituents, but solubility in aqueous solution, absorption performance of the water absorbent resin composition, and availability From the viewpoint of ease of use, both are preferably hydrogen.
前記単量体組成物中の前記内部架橋剤（ｂ）の物質量は、吸収性能、およびＶｏｒｔｅｘ法による吸収速度等の観点から、前記モノマー（Ａ１）１００モル部、その他のビニルモノマー（Ａ２）を用いる場合は（Ａ１）及び（Ａ２）の合計１００モル部に対して、０．００１～５モル部が好ましく、更に好ましくは０．００５～３モル部、特に好ましくは０．００５～１モル部である。
The amount of the internal cross-linking agent (b) in the monomer composition is 100 mol parts of the monomer (A1) and the other vinyl monomer (A2) from the viewpoint of absorption performance and absorption speed by the Vortex method. When using (A1) and (A2) with respect to a total of 100 mol parts, preferably 0.001 to 5 mol parts, more preferably 0.005 to 3 mol parts, particularly preferably 0.005 to 1 mol parts Department.
また、前記内部架橋剤（ｂ）に加えて、公知（例えば、特許第３６４８５５３号公報の００３１～００３４段落に開示されているエチレン性不飽和基を２個以上有する架橋剤、水溶性置換基と反応し得る官能基を少なくとも１個有してかつ少なくとも１個のエチレン性不飽和基を有する架橋剤及び水溶性置換基と反応し得る官能基を少なくとも２個有する架橋剤、特開２００３－１６５８８３号公報の００２８～００３１段落に開示されているエチレン性不飽和基を２個以上有する架橋剤、エチレン性不飽和基と反応性官能基とを有する架橋剤及び反応性置換基を２個以上有する架橋剤、特開２００５－７５９８２号公報の００５９段落に開示されている架橋性ビニルモノマー並びに特開２００５－９５７５９号公報の００１５～００１６段落に開示されている架橋性ビニルモノマー）の架橋剤等も必要に応じて併用することができる。併用することで、吸水性能の向上が可能となる。
In addition to the internal cross-linking agent (b), a cross-linking agent having two or more ethylenically unsaturated groups disclosed in paragraphs 0031 to 0034 of Japanese Patent No. 3648553, a water-soluble substituent, and A cross-linking agent having at least one functional group capable of reacting and having at least one ethylenically unsaturated group and a cross-linking agent having at least two functional groups capable of reacting with a water-soluble substituent, JP-A-2003-165883 A cross-linking agent having two or more ethylenically unsaturated groups disclosed in paragraphs 0028 to 0031 of the publication, a cross-linking agent having an ethylenically unsaturated group and a reactive functional group, and two or more reactive substituents Cross-linking agents, cross-linking vinyl monomers disclosed in paragraph 0059 of JP-A-2005-75982 and cross-linking vinyl monomers disclosed in paragraphs 0015-0016 of JP-A-2005-95759). They can be used together as needed. By using them together, it is possible to improve the water absorption performance.
内部架橋剤（ｂ）以外の内部架橋剤の物質量は、内部架橋剤（ｂ）１００モル部に対して、分解性能の観点から０～５０モル部が好ましい。
The substance amount of the internal cross-linking agent other than the internal cross-linking agent (b) is preferably 0 to 50 mol parts per 100 mol parts of the internal cross-linking agent (b) from the viewpoint of decomposition performance.
重合工程における重合方法としては、水溶液重合法、又は逆相懸濁重合法（炭化水素系溶媒中での懸濁重合）を用いることができる。
As the polymerization method in the polymerization step, an aqueous solution polymerization method or a reverse phase suspension polymerization method (suspension polymerization in a hydrocarbon solvent) can be used.
水溶液重合を行う場合、水または、水と有機溶媒とを含む混合溶媒を重合溶媒として使用することができる。有機溶媒としては、メタノール、エタノール、アセトン、メチルエチルケトン、Ｎ，Ｎ－ジメチルホルムアミド、ジメチルスルホキシド及びこれらの２種以上の混合物を挙げられる。前記重合溶媒である、水または水と有機溶媒とを含む混合溶媒は、前記単量体組成物と混合され、重合溶液を構成する。
When performing aqueous polymerization, water or a mixed solvent containing water and an organic solvent can be used as a polymerization solvent. Organic solvents include methanol, ethanol, acetone, methyl ethyl ketone, N,N-dimethylformamide, dimethylsulfoxide and mixtures of two or more thereof. The polymerization solvent, water or a mixed solvent containing water and an organic solvent, is mixed with the monomer composition to form a polymerization solution.
水溶液重合を行う場合、有機溶媒の使用量（重量％）は、水の重量を基準として４０以下が好ましく、更に好ましくは３０以下である。
When performing aqueous polymerization, the amount (% by weight) of the organic solvent used is preferably 40 or less, more preferably 30 or less, based on the weight of water.
重合方法が逆相懸濁重合法である場合、必要に応じて、従来公知の分散剤又は界面活性剤の存在下に重合を行っても良い。また、従来公知のキシレン、ノルマルヘキサン及びノルマルヘプタン等の炭化水素系溶媒を使用して重合を行うことができる。逆相懸濁重合法は、前記のモノマー（Ａ１）と内部架橋剤（ｂ）とを含む重合溶液を炭化水素系溶媒に懸濁させ、炭化水素系溶媒中に分散した重合溶液を重合する重合方法である。逆相懸濁重合法における重合溶液としては、前記の水溶液重合で用いるものと同じものを用いることができる。
When the polymerization method is a reversed-phase suspension polymerization method, polymerization may be carried out in the presence of a conventionally known dispersant or surfactant, if necessary. Also, the polymerization can be carried out using conventionally known hydrocarbon solvents such as xylene, normal hexane and normal heptane. In the reverse phase suspension polymerization method, a polymerization solution containing the monomer (A1) and the internal cross-linking agent (b) is suspended in a hydrocarbon solvent, and the polymerization solution dispersed in the hydrocarbon solvent is polymerized. The method. As the polymerization solution in the reversed-phase suspension polymerization method, the same solution as used in the aqueous solution polymerization can be used.
重合方法のうち、有機溶媒等を使用する必要がなく生産コスト面で有利なことから、好ましいのは水溶液重合法であり、保水量が大きく、且つ水可溶性成分量の少ない水性液体吸収性樹脂が得られ、重合時の温度コントロールが不要である点から、水溶液断熱重合法が更に好ましい。
Of the polymerization methods, the aqueous solution polymerization method is preferable because it does not require the use of an organic solvent or the like and is advantageous in terms of production cost, and an aqueous liquid absorbent resin with a large water retention capacity and a small amount of water-soluble components is produced. The aqueous solution adiabatic polymerization method is more preferable because it can be obtained and temperature control during polymerization is unnecessary.
架橋重合体（Ａ）の構成単量体（モノマー（Ａ１）及び内部架橋剤（ｂ）、並びに必要に応じて用いるビニルモノマー（Ａ２）、および内部架橋剤（ｂ）以外の内部架橋剤）であって、重合溶液に含まれる単量体の合計重量パーセント濃度は重合開始時の重合溶液の総重量に対して１５～５５％が好ましい。この範囲より低い場合には生産性が悪くなる場合があり、高い場合には十分なゲル強度を得ることができない場合がある。
Constituent monomers of the crosslinked polymer (A) (monomer (A1) and internal crosslinking agent (b), vinyl monomer (A2) used as necessary, and internal crosslinking agent other than internal crosslinking agent (b)) The total weight percent concentration of the monomers contained in the polymerization solution is preferably 15 to 55% with respect to the total weight of the polymerization solution at the start of polymerization. If it is lower than this range, the productivity may deteriorate, and if it is higher than this range, sufficient gel strength may not be obtained.
前記単量体組成物を含む重合溶液のｐＨの範囲は１～１２であり、より好ましくは１～１０であり、さらに好ましくは１～７である。この範囲であると、後述する表面架橋剤による表面架橋が効率敵に進行し、必要となる吸水性能を得やすい。一方で、ｐＨが１２を超える場合、表面架橋剤による表面架橋が進行しづらくなり、結果として必要とする吸水性能が発現しない。なお、重合溶液のｐＨは、重合溶液を希釈することなく測定用試料とし、ＪＩＳ Ｚ８８０２ ｐＨ測定方法に準拠した方法で、ガラス電極ｐＨメーターを用いて２５℃で測定される。
The pH range of the polymerization solution containing the monomer composition is 1-12, more preferably 1-10, and still more preferably 1-7. Within this range, surface cross-linking by a surface cross-linking agent, which will be described later, proceeds efficiently, and the required water absorption performance can be easily obtained. On the other hand, when the pH exceeds 12, the surface cross-linking by the surface cross-linking agent becomes difficult to proceed, and as a result, the required water absorption performance is not exhibited. The pH of the polymerization solution is measured at 25° C. using a glass electrode pH meter in accordance with JIS Z8802 pH measurement method using a sample for measurement without diluting the polymerization solution.
重合溶液のｐＨは、重合溶液に含まれる前記のモノマー（Ａ１）の濃度で調整することができる。また、重合溶液に公知の水溶性の酸性物質あるいは水溶性の塩基性物質を重合溶液に添加することで調整してもよい。水溶性の酸性物質を添加する場合、好ましい酸性物質としては塩化水素、硫酸、硝酸、酢酸、乳酸、シュウ酸があげられ、より好ましくは硫酸、乳酸である。水溶性の塩基性物質を添加する場合、好ましくい塩基性物質としては水酸化ナトリウム、水酸化カリウムがあげられ、より好ましくは水酸化ナトリウムである。
The pH of the polymerization solution can be adjusted by the concentration of the monomer (A1) contained in the polymerization solution. Moreover, it may be adjusted by adding a known water-soluble acidic substance or water-soluble basic substance to the polymerization solution. When a water-soluble acidic substance is added, preferable acidic substances include hydrogen chloride, sulfuric acid, nitric acid, acetic acid, lactic acid and oxalic acid, more preferably sulfuric acid and lactic acid. When a water-soluble basic substance is added, preferable basic substances include sodium hydroxide and potassium hydroxide, more preferably sodium hydroxide.
前記重合工程において、必要に応じて公知のラジカル開始剤と重合溶液とを混合して重合を行うことが出来る。なお、ラジカル開始剤と重合溶液とを混合すると重合反応が開始されてしまいｐＨを測定することが難しい。一方、ラジカル開始剤は弱酸性～中性であるため、ラジカル開始剤を混合して重合を行う場合であっても、ラジカル開始剤を混合する前後のｐＨは殆ど変化することが無い。そのため、ラジカル開始剤と重合溶液とを混合して重合を行う場合の重合溶液のｐＨは、ラジカル開始剤を混合する前に前記の方法で測定する。
In the polymerization step, if necessary, polymerization can be carried out by mixing a known radical initiator and a polymerization solution. In addition, when the radical initiator and the polymerization solution are mixed, the polymerization reaction is initiated, making it difficult to measure the pH. On the other hand, since the radical initiator is weakly acidic to neutral, even when the polymerization is performed by mixing the radical initiator, the pH before and after mixing the radical initiator hardly changes. Therefore, the pH of the polymerization solution when polymerization is performed by mixing the radical initiator and the polymerization solution is measured by the above method before mixing the radical initiator.
公知のラジカル開始剤としては、アゾ化合物［アゾビスイソブチロニトリル、アゾビスシアノ吉草酸及び２，２’－アゾビス（２－アミジノプロパン）ハイドロクロライド、２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）プロピオンアミド］等］、無機過酸化物（過酸化水素、過硫酸アンモニウム、過硫酸カリウム及び過硫酸ナトリウム等）、有機過酸化物［過酸化ベンゾイル、ジ－ｔ－ブチルパーオキサイド、クメンヒドロパーオキサイド、コハク酸パーオキサイド及びジ（２－エトキシエチル）パーオキシジカーボネート等］、レドックス触媒（アルカリ金属の亜硫酸塩又は重亜硫酸塩、亜硫酸アンモニウム、重亜硫酸アンモニウム及びアスコルビン酸等の還元剤とアルカリ金属の過硫酸塩、過硫酸アンモニウム、過酸化水素及び有機過酸化物等の酸化剤との組み合わせよりなるもの）、光ラジカル発生剤［２，４，６－トリメチルベンゾイル－ジフェニル－フォスフィンオキサイド、１－ヒドロキシシクロヘキシル－フェニルケトン－ヒドロキシアルキルフェノン、α－アミノアルキルフェノン等］等があげられる。これらのラジカル開始剤は、単独で使用してもよく、これらの２種以上を併用しても良い。
Known radical initiators include azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid and 2,2′-azobis(2-amidinopropane) hydrochloride, 2,2′-azobis[2-methyl-N- (2-hydroxyethyl) propionamide], etc.], inorganic peroxides (hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate, etc.), organic peroxides [benzoyl peroxide, di-t-butyl peroxide , cumene hydroperoxide, succinic acid peroxide and di(2-ethoxyethyl)peroxydicarbonate, etc.], redox catalysts (alkali metal sulfites or bisulfites, ammonium sulfite, ammonium bisulfite and reduction of ascorbic acid, etc. and oxidizing agents such as alkali metal persulfates, ammonium persulfates, hydrogen peroxide and organic peroxides), photoradical generators [2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 1-hydroxycyclohexyl-phenylketone-hydroxyalkylphenone, α-aminoalkylphenone, etc.] and the like. These radical initiators may be used alone, or two or more of them may be used in combination.
ラジカル開始剤の使用量は、モノマー（Ａ１）１００モル部に対して、０．０００５～５モル部が好ましく、更に好ましくは０．００１～２モル部である。
The amount of the radical initiator used is preferably 0.0005 to 5 mol parts, more preferably 0.001 to 2 mol parts, per 100 mol parts of the monomer (A1).
前記の重合工程によって、前記モノマー（Ａ１）及び前記内部架橋剤（ｂ）を構成単位として有する架橋重合体（Ａ）の含水ゲルが得られ、この含水ゲルは、必要に応じて細断することができる。細断後の含水ゲルの大きさ（最長径）は５０μｍ～１０ｃｍが好ましく、更に好ましくは１００μｍ～２ｃｍ、特に好ましくは１ｍｍ～１ｃｍである。この範囲であると、乾燥工程での乾燥性が更に良好となる。
Through the polymerization step, a hydrous gel of the crosslinked polymer (A) having the monomer (A1) and the internal cross-linking agent (b) as constituent units is obtained, and this hydrous gel may be cut into small pieces as necessary. can be done. The size (longest diameter) of the water-containing gel after shredding is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, particularly preferably 1 mm to 1 cm. Within this range, the drying property in the drying step is further improved.
細断は、公知の方法で行うことができ、細断装置（例えば、ベックスミル、ラバーチョッパ、ファーマミル、ミンチ機（ミートチョッパー）、衝撃式粉砕機及びロール式粉砕機）等を使用して細断できる。また、裁断中に、必要に応じて、上記のようにして得られる含水ゲルにアルカリを混合して中和することもできる。
Shredding can be performed by a known method, and finely using a shredding device (e.g., Vex mill, rubber chopper, farmer mill, mincing machine (meat chopper), impact pulverizer, and roll pulverizer). can be cut off. Further, during the cutting, if necessary, the hydrous gel obtained as described above can be neutralized by mixing with an alkali.
アルカリは、公知｛特許第３２０５１６８号公報等｝のものが使用できる。これらのうち、吸水性能の観点から、水酸化リチウム、水酸化ナトリウム及び水酸化カリウムが好ましく、さらに好ましくは水酸化ナトリウム及び水酸化カリウム、特に好ましくは水酸化ナトリウムである。中和率は、吸水性能やハンドリングの観点から、２０～１００モル％が好ましく、更に好ましくは、５０～８０モル％である。中和度が５０モル％未満の場合、得られる含水ゲルの粘着性が高くなり、製造時及び使用時の作業性が悪化する場合がある。更に得られる吸水性樹脂の保水量が低下する場合がある。一方、中和度が８０％を超える場合、得られた樹脂のｐＨが高くなり人体の皮膚に対する安全性が懸念される場合がある。
As for the alkali, a known one {Patent No. 3205168, etc.} can be used. Among these, lithium hydroxide, sodium hydroxide and potassium hydroxide are preferred, sodium hydroxide and potassium hydroxide are more preferred, and sodium hydroxide is particularly preferred, from the viewpoint of water absorption performance. The neutralization rate is preferably 20 to 100 mol %, more preferably 50 to 80 mol %, from the viewpoint of water absorption performance and handling. If the degree of neutralization is less than 50 mol %, the obtained hydrogel will be highly sticky, and workability during production and use may be deteriorated. Furthermore, the water-retaining capacity of the obtained water-absorbing resin may decrease. On the other hand, if the degree of neutralization exceeds 80%, the resulting resin will have a high pH and may be unsafe for human skin.
〔乾燥工程〕
本実施形態の吸水性樹脂組成物の製造方法は、前記含水ゲルを乾燥し、含水ゲル中の溶媒（水を含む）を留去する乾燥工程を有してもよい。 [Drying process]
The method for producing a water-absorbing resin composition of the present embodiment may have a drying step of drying the water-containing gel and distilling off the solvent (including water) in the water-containing gel.
本実施形態の吸水性樹脂組成物の製造方法は、前記含水ゲルを乾燥し、含水ゲル中の溶媒（水を含む）を留去する乾燥工程を有してもよい。 [Drying process]
The method for producing a water-absorbing resin composition of the present embodiment may have a drying step of drying the water-containing gel and distilling off the solvent (including water) in the water-containing gel.
前記乾燥工程における乾燥方法としては、マイクロ波乾燥、ドラムドライヤー等による薄膜乾燥法、（加熱）減圧乾燥法、凍結乾燥法、赤外線による乾燥法、デカンテーション及び濾過等が適用できる。
As a drying method in the drying step, microwave drying, a thin film drying method using a drum dryer, etc., a (heating) vacuum drying method, a freeze drying method, an infrared drying method, decantation, filtration, and the like can be applied.
前記乾燥工程での乾燥温度は、１００～３００℃であり、好ましくは１５０～２５０℃である。乾燥温度が高いと乾燥時間が短くなる結果、生産性が向上するが、乾燥温度が高いと、吸水性樹脂組成物の熱劣化により保水能や荷重下吸収量及び通液速度が低下する恐れおよび吸水性樹脂組成物の色調が悪化する恐れがある。乾燥温度が１００℃未満では、吸水性樹脂組成物を十分に乾燥することができず、生産性が低下してしまう。
The drying temperature in the drying step is 100-300°C, preferably 150-250°C. If the drying temperature is high, the drying time will be shortened, resulting in improved productivity. The color tone of the water absorbent resin composition may deteriorate. If the drying temperature is lower than 100°C, the water-absorbing resin composition cannot be sufficiently dried, resulting in a decrease in productivity.
前記乾燥工程において、高温多湿の環境下における長期間保管後の色味の変化を抑制しながら、可溶分の変化を抑制する観点から、乾燥時間は６０分以内が好ましく、４０分以内がより好ましい。また、乾燥時間は、一般には１０分以上が好ましい。乾燥時間が短いと、未乾燥物が生成し、後の粉砕工程に詰まりが生じ得る。
In the drying step, the drying time is preferably within 60 minutes, more preferably within 40 minutes, from the viewpoint of suppressing changes in soluble matter while suppressing changes in color after long-term storage in a hot and humid environment. preferable. Also, the drying time is generally preferably 10 minutes or longer. Short drying times can lead to undried material and clogging later in the milling process.
〔粉砕工程〕
本実施形態の吸水性樹脂組成物の製造方法は、前記乾燥工程で得られた含水ゲルの乾燥体を粉砕し、前記架橋重合体（Ａ）を含有する粒子状の乾燥体を得る粉砕工程を有していてもよい。 [Pulverization process]
The method for producing a water-absorbent resin composition of the present embodiment includes a pulverizing step of pulverizing the dried body of the hydrous gel obtained in the drying step to obtain a particulate dried body containing the crosslinked polymer (A). may have.
本実施形態の吸水性樹脂組成物の製造方法は、前記乾燥工程で得られた含水ゲルの乾燥体を粉砕し、前記架橋重合体（Ａ）を含有する粒子状の乾燥体を得る粉砕工程を有していてもよい。 [Pulverization process]
The method for producing a water-absorbent resin composition of the present embodiment includes a pulverizing step of pulverizing the dried body of the hydrous gel obtained in the drying step to obtain a particulate dried body containing the crosslinked polymer (A). may have.
前記粉砕工程において、含水ゲルの乾燥体を粉砕する方法については、特に限定はなく、粉砕装置（例えば、ハンマー式粉砕機、衝撃式粉砕機、ロール式粉砕機及びシェット気流式粉砕機）等が使用できる。粉砕された吸水性樹脂組成物は、必要によりふるい分け等により粒度調整できる。
In the pulverization step, the method for pulverizing the dried hydrogel is not particularly limited, and a pulverizer (for example, a hammer pulverizer, an impact pulverizer, a roll pulverizer, and a jet air pulverizer), etc. Available. The pulverized water absorbent resin composition can be adjusted in particle size by sieving or the like, if necessary.
〔表面架橋工程〕
本実施形態の吸水性樹脂組成物の製造方法は、前記架橋重合体（Ａ）を含む含水ゲルを得る重合工程の後、架橋重合体（Ａ）の表面を表面架橋剤によって架橋する表面架橋工程を有する。 [Surface cross-linking step]
The method for producing a water-absorbing resin composition of the present embodiment includes a surface cross-linking step of cross-linking the surface of the cross-linked polymer (A) with a surface cross-linking agent after the polymerization step of obtaining a hydrous gel containing the cross-linked polymer (A). have
本実施形態の吸水性樹脂組成物の製造方法は、前記架橋重合体（Ａ）を含む含水ゲルを得る重合工程の後、架橋重合体（Ａ）の表面を表面架橋剤によって架橋する表面架橋工程を有する。 [Surface cross-linking step]
The method for producing a water-absorbing resin composition of the present embodiment includes a surface cross-linking step of cross-linking the surface of the cross-linked polymer (A) with a surface cross-linking agent after the polymerization step of obtaining a hydrous gel containing the cross-linked polymer (A). have
表面架橋工程を経て得られた吸水性樹脂組成物は、前記架橋重合体（Ａ）の表面が表面架橋剤（ｃ）により架橋された構造を有する。架橋重合体（Ａ）の表面を架橋することにより前記吸水性樹脂組成物のゲル強度を向上させることができ、前記吸水性樹脂組成物の望ましい保水量と荷重下における吸収量とを満足させることができる。また、吸水性樹脂組成物の表面のブロッキングが抑制され、均一吸水が達成できるので酸化剤で分解する際にも、分解効率の向上が期待できる。
The water absorbent resin composition obtained through the surface cross-linking step has a structure in which the surface of the cross-linked polymer (A) is cross-linked by the surface cross-linking agent (c). By cross-linking the surface of the crosslinked polymer (A), the gel strength of the water-absorbing resin composition can be improved, and the water-absorbing resin composition satisfies the desired water retention capacity and absorption capacity under load. can be done. In addition, since blocking on the surface of the water-absorbing resin composition can be suppressed and uniform water absorption can be achieved, even when decomposing with an oxidizing agent, an improvement in decomposition efficiency can be expected.
表面架橋剤（ｃ）は、無機物でも有機物でも用いることができる。表面架橋剤（ｃ）としては、公知（特開昭５９－１８９１０３号公報に記載の多価グリシジル化合物、多価アミン、多価アジリジン化合物及び多価イソシアネート化合物等、特開昭５８－１８０２３３号公報及び特開昭６１－１６９０３号公報の多価アルコール、特開昭６１－２１１３０５号公報及び特開昭６１－２５２２１２号公報に記載のシランカップリング剤、特表平５－５０８４２５号公報に記載のアルキレンカーボネート、特開平１１－２４０９５９号公報に記載の多価オキサゾリン化合物等）の有機表面架橋剤等が使用できる。これらの表面架橋剤（ｃ）のうち、経済性及び吸収特性の観点から、多価グリシジル化合物、多価アルコール及び多価アミンが好ましく、更に好ましいのは多価グリシジル化合物及び多価アルコール、特に好ましいのは多価グリシジル化合物、最も好ましいのはエチレングリコールジグリシジルエーテルである。表面架橋剤（ｃ）は１種を単独で用いても良いし、２種以上を併用しても良い。
Both inorganic and organic substances can be used as the surface cross-linking agent (c). As the surface cross-linking agent (c), known (polyvalent glycidyl compounds, polyvalent amines, polyvalent aziridine compounds and polyvalent isocyanate compounds described in JP-A-59-189103, etc., JP-A-58-180233 And the polyhydric alcohol of JP-A-61-16903, the silane coupling agent described in JP-A-61-211305 and JP-A-61-252212, the JP-A-5-508425 described Organic surface cross-linking agents such as alkylene carbonates and polyvalent oxazoline compounds described in JP-A-11-240959 can be used. Among these surface cross-linking agents (c), polyhydric glycidyl compounds, polyhydric alcohols and polyhydric amines are preferred, more preferred are polyhydric glycidyl compounds and polyhydric alcohols, and particularly preferred are polyhydric glycidyl compounds and polyhydric alcohols, from the viewpoint of economy and absorption properties. are polyhydric glycidyl compounds, most preferably ethylene glycol diglycidyl ether. The surface cross-linking agent (c) may be used alone or in combination of two or more.
前記表面架橋剤（ｃ）の使用量（重量％）は、表面架橋剤の種類、架橋させる条件、目標とする性能等により種々変化させることができるため特に限定はないが、吸収特性の観点等から、架橋重合体（Ａ）の重量に基づいて、０．００１～３が好ましく、更に好ましくは０．００５～２、特に好ましくは０．０１～１．５である。
The amount (% by weight) of the surface cross-linking agent (c) used is not particularly limited because it can be varied depending on the type of the surface cross-linking agent, cross-linking conditions, target performance, etc., but from the viewpoint of absorption characteristics, etc. Therefore, it is preferably 0.001 to 3, more preferably 0.005 to 2, and particularly preferably 0.01 to 1.5, based on the weight of the crosslinked polymer (A).
架橋重合体（Ａ）の表面架橋は、架橋重合体（Ａ）と表面架橋剤（ｃ）とを混合し、加熱することで行うことができる。架橋重合体（Ａ）と表面架橋剤（ｃ）との混合方法としては、円筒型混合機、スクリュー型混合機、スクリュー型押出機、タービュライザー、ナウター型混合機、双腕型ニーダー、流動式混合機、Ｖ型混合機、ミンチ混合機、リボン型混合機、流動式混合機、気流型混合機、回転円盤型混合機、コニカルブレンダー及びロールミキサー等の混合装置を用いて架橋重合体（Ａ）と表面架橋剤（ｃ）とを均一混合する方法が挙げられる。この際、表面架橋剤（ｃ）は、水及び／又は任意の溶剤で希釈して使用しても良い。架橋重合体（Ａ）と表面架橋剤（ｃ）の混合は、前記乾燥工程で得られた、架橋重合体（Ａ）を含む含水ゲルの乾燥体と表面架橋剤（ｃ）の混合が好ましく、前記粉砕工程で得られた架橋重合体（Ａ）を含む粒子状乾燥体と表面架橋剤（ｃ）の混合がさらに好ましい。
The surface cross-linking of the cross-linked polymer (A) can be performed by mixing the cross-linked polymer (A) and the surface cross-linking agent (c) and heating the mixture. Examples of the method for mixing the crosslinked polymer (A) and the surface cross-linking agent (c) include a cylindrical mixer, a screw mixer, a screw extruder, a turbulizer, a Nauta mixer, a twin-arm kneader, a fluid A crosslinked polymer ( A) can be uniformly mixed with the surface cross-linking agent (c). At this time, the surface cross-linking agent (c) may be diluted with water and/or any solvent before use. Mixing of the crosslinked polymer (A) and the surface cross-linking agent (c) is preferably performed by mixing the dried hydrous gel containing the crosslinked polymer (A) obtained in the drying step with the surface cross-linking agent (c). It is more preferable to mix the particulate dry matter containing the crosslinked polymer (A) obtained in the pulverization step with the surface crosslinking agent (c).
架橋重合体（Ａ）と表面架橋剤（ｃ）とを混合する際の温度は特に限定されないが、１０～１５０℃が好ましく、更に好ましくは２０～１００℃、特に好ましくは２５～８０℃である。
The temperature at which the crosslinked polymer (A) and the surface cross-linking agent (c) are mixed is not particularly limited, but is preferably 10 to 150°C, more preferably 20 to 100°C, and particularly preferably 25 to 80°C. .
架橋重合体（Ａ）と表面架橋剤（ｃ）とを混合した後、加熱処理を行うことが好ましい。加熱温度は、吸水性樹脂組成物の耐壊れ性の観点から好ましくは１００～１８０℃、更に好ましくは１１０～１７５℃、特に好ましくは１２０～１７０℃である。１８０℃以下の加熱であれば蒸気を利用した間接加熱が可能であり設備上有利であり、１００℃未満の加熱温度では吸収性能が悪くなる場合がある。また、加熱時間は加熱温度により適宜設定することができるが、吸収性能の観点から、好ましくは５～６０分、更に好ましくは１０～４０分である。表面架橋して得られる吸水性樹脂組成物を、最初に用いた表面架橋剤と同種又は異種の表面架橋剤を用いて、更に表面架橋することも可能である。
Heat treatment is preferably performed after mixing the crosslinked polymer (A) and the surface crosslinking agent (c). The heating temperature is preferably 100 to 180°C, more preferably 110 to 175°C, particularly preferably 120 to 170°C, from the viewpoint of breakage resistance of the water absorbent resin composition. Heating at 180° C. or less enables indirect heating using steam, which is advantageous in terms of facilities. Heating temperatures below 100° C. may result in poor absorption performance. The heating time can be appropriately set depending on the heating temperature, but from the viewpoint of absorption performance, it is preferably 5 to 60 minutes, more preferably 10 to 40 minutes. It is also possible to further surface-crosslink the water-absorbing resin composition obtained by surface-crosslinking using a surface-crosslinking agent that is the same as or different from the surface-crosslinking agent used first.
架橋重合体（Ａ）の表面を表面架橋剤（ｃ）により架橋した後、必要により篩別して粒度調整する。得られた粒子の平均粒経は、好ましくは１００～６００μｍ、更に好ましくは２００～５００μｍである。微粒子の含有量は少ない方が好ましく、１００μｍ以下の粒子の含有量は３重量％以下であることが好ましく、１５０μｍ以下の粒子の含有量が３重量％以下であることが更に好ましい。
After cross-linking the surface of the cross-linked polymer (A) with the surface-cross-linking agent (c), the particle size is adjusted by sieving if necessary. The average particle size of the obtained particles is preferably 100-600 μm, more preferably 200-500 μm. The content of fine particles is preferably as small as possible, the content of particles of 100 μm or less is preferably 3% by weight or less, and the content of particles of 150 μm or less is more preferably 3% by weight or less.
＜吸水性樹脂組成物＞
本実施形態の吸水性樹脂組成物は、前記水溶性不飽和モノカルボン酸（ａ１）及びその塩、並びに前記内部架橋剤（ｂ）を必須構成単位とする架橋重合体（Ａ）の表面が表面架橋剤（ｃ）で表面架橋された吸水性樹脂組成物であって、下記（１）～（３）を満たす。
（１）０．９重量％生理食塩水の保水量が単位重量あたり１５～６０ｇ／ｇ
（２）０．９重量％生理食塩水の荷重下吸収量が単位重量あたり１０～２７ｇ／ｇ
（３）Ｖｏｒｔｅｘ法による吸収速度（秒）が８０以下 <Water absorbent resin composition>
In the water-absorbing resin composition of the present embodiment, the water-soluble unsaturated monocarboxylic acid (a1) and its salt, and the crosslinked polymer (A) having the essential structural units of the internal cross-linking agent (b) have a surface A water-absorbing resin composition surface-crosslinked with a crosslinking agent (c) and satisfying the following (1) to (3).
(1) Water retention capacity of 0.9% by weight saline is 15 to 60 g/g per unit weight
(2) Absorption amount under load of 0.9 wt% physiological saline is 10 to 27 g/g per unit weight
(3) Absorption rate (sec) by Vortex method is 80 or less
本実施形態の吸水性樹脂組成物は、前記水溶性不飽和モノカルボン酸（ａ１）及びその塩、並びに前記内部架橋剤（ｂ）を必須構成単位とする架橋重合体（Ａ）の表面が表面架橋剤（ｃ）で表面架橋された吸水性樹脂組成物であって、下記（１）～（３）を満たす。
（１）０．９重量％生理食塩水の保水量が単位重量あたり１５～６０ｇ／ｇ
（２）０．９重量％生理食塩水の荷重下吸収量が単位重量あたり１０～２７ｇ／ｇ
（３）Ｖｏｒｔｅｘ法による吸収速度（秒）が８０以下 <Water absorbent resin composition>
In the water-absorbing resin composition of the present embodiment, the water-soluble unsaturated monocarboxylic acid (a1) and its salt, and the crosslinked polymer (A) having the essential structural units of the internal cross-linking agent (b) have a surface A water-absorbing resin composition surface-crosslinked with a crosslinking agent (c) and satisfying the following (1) to (3).
(1) Water retention capacity of 0.9% by weight saline is 15 to 60 g/g per unit weight
(2) Absorption amount under load of 0.9 wt% physiological saline is 10 to 27 g/g per unit weight
(3) Absorption rate (sec) by Vortex method is 80 or less
前記吸水性樹脂組成物の０．９重量％生理食塩水に対する生理食塩水の保水量（ｇ／ｇ）は、衛生用品の吸収性能の観点から、１５～６０であり、好ましくは２５～５５である。なお、０．９重量％生理食塩水の保水量は実施例に記載の方法により測定される。
The water retention capacity (g/g) of the water-absorbing resin composition with respect to 0.9% by weight saline is 15 to 60, preferably 25 to 55, from the viewpoint of the absorption performance of sanitary goods. be. The water retention capacity of 0.9% by weight physiological saline is measured by the method described in Examples.
前記吸水性樹脂組成物の０．９重量％生理食塩水に対する荷重下吸収量（ｇ／ｇ）は、１０～２７であり、より好ましくは１２以上である。１０未満であると、繰り返し使用時に漏れが生じやすく好ましくない。また、上限値は、他物性との性能バランスや生産性の観点から、好ましくは２６以下である。荷重下吸収量は、内部架橋剤（ｂ）および表面架橋剤の種類と量で適宜調整することができる。従って、例えば、荷重下吸収量を上げる必要がある場合、内部架橋剤（ｂ）および表面架橋剤の使用量を上げることで容易に実現することができる。前記吸水性樹脂組成物の荷重下吸収量（ｇ／ｇ）は実施例に記載の方法で測定することができる。
The absorption under load (g/g) of the water-absorbent resin composition in 0.9% by weight physiological saline is 10 to 27, more preferably 12 or more. If it is less than 10, leakage tends to occur during repeated use, which is not preferable. Moreover, the upper limit is preferably 26 or less from the viewpoint of performance balance with other physical properties and productivity. The absorption under load can be appropriately adjusted by the types and amounts of the internal cross-linking agent (b) and the surface cross-linking agent. Therefore, for example, when it is necessary to increase the absorption under load, it can be easily achieved by increasing the amounts of the internal cross-linking agent (b) and the surface cross-linking agent. The absorbency under load (g/g) of the water absorbent resin composition can be measured by the method described in Examples.
前記吸水性樹脂組成物のＶｏｒｔｅｘ試験（秒）は、８０以下である。また、下限値は低いほど好ましく特に制限されないが、他物性との性能バランスや生産性の観点から、好ましくは７０以下である。この範囲であると、衛生物品にした際に、液漏れの懸念を低減させることができる。前記吸水性樹脂組成物のＶｏｒｔｅｘ試験（秒）は実施例に記載の方法で測定することができる。
The Vortex test (seconds) of the water absorbent resin composition is 80 or less. The lower limit is preferably as low as possible, but is not particularly limited, but is preferably 70 or less from the viewpoint of performance balance with other physical properties and productivity. Within this range, it is possible to reduce the risk of liquid leakage when used as a sanitary article. The vortex test (seconds) of the water absorbent resin composition can be measured by the method described in Examples.
前記の吸水性樹脂組成物の製造方法に記載の単量体組成物を重合して得られる架橋重合体（Ａ）を表面架橋剤（ｃ）によって架橋すること、架橋重合体（Ａ）を構成するモノマー（Ａ１）および（Ａ２）の合計物質量（モル数）に対する内部架橋剤（ｂ）の物質量を前記の好ましい量にすること等によって、吸水性樹脂組成物の生理食塩水の保水量、０．９重量％生理食塩水に対する荷重下吸収量、およびＶｏｒｔｅｘ法による吸収速度を前記の範囲に調整することができる。
The crosslinked polymer (A) is formed by crosslinking the crosslinked polymer (A) obtained by polymerizing the monomer composition described in the method for producing a water absorbent resin composition with the surface crosslinking agent (c). By adjusting the amount of the internal cross-linking agent (b) with respect to the total amount (number of moles) of the monomers (A1) and (A2) to be the above-mentioned preferable amount, the water-retaining amount of physiological saline of the water-absorbing resin composition , the absorption under load in 0.9% by weight physiological saline, and the absorption rate according to the Vortex method can be adjusted within the above ranges.
前記架橋重合体（Ａ）における前記ビニルモノマー（Ａ２）単位の物質量は、吸収性能等の観点から、前記水溶性不飽和モノカルボン酸（ａ１）の構成単位及びその塩の構成単位の合計１００モル部に対して、０～５モル部が好ましく、更に好ましくは０～３モル部、特に好ましくは０～２モル部、とりわけ好ましくは０～１．５モル部であり、吸収性能等の観点から、前記ビニルモノマー（Ａ２）単位の含有量が０モル部であることが最も好ましい。
The amount of the vinyl monomer (A2) unit in the crosslinked polymer (A) is 100 in total for the structural unit of the water-soluble unsaturated monocarboxylic acid (a1) and the structural unit of its salt, from the viewpoint of absorption performance and the like. It is preferably 0 to 5 mol parts, more preferably 0 to 3 mol parts, particularly preferably 0 to 2 mol parts, and particularly preferably 0 to 1.5 mol parts with respect to mol parts, from the viewpoint of absorption performance and the like. Therefore, it is most preferable that the content of the vinyl monomer (A2) unit is 0 mol parts.
前記架橋重合体（Ａ）における前記内部架橋剤（ｂ）の物質量は、吸収性能等の観点から、前記水溶性不飽和モノカルボン酸（ａ１）の構成単位及びその塩の構成単位の合計１００モル部１００モル部、その他のビニルモノマー（Ａ２）を用いる場合は前記水溶性不飽和モノカルボン酸（ａ１）の構成単位及びその塩の構成単位、並びにビニルモノマー（Ａ２）の構成単位の合計１００モル部に対して、０．００１～５モル部が好ましく、更に好ましくは０．００５～３モル部、特に好ましくは０．００５～１モル部である。
The amount of the internal cross-linking agent (b) in the crosslinked polymer (A) is, from the viewpoint of absorption performance and the like, a total of 100 of the constituent units of the water-soluble unsaturated monocarboxylic acid (a1) and the constituent units of its salt. 100 molar parts, and when using other vinyl monomers (A2), a total of 100 of the structural units of the water-soluble unsaturated monocarboxylic acid (a1) and salts thereof, and the structural units of the vinyl monomer (A2) It is preferably from 0.001 to 5 molar parts, more preferably from 0.005 to 3 molar parts, and particularly preferably from 0.005 to 1 molar part.
前記内部架橋剤（ｂ）以外の内部架橋剤の物質量は、内部架橋剤（ｂ）１００モル部に対して、分解性能の観点から０～５０モル部が好ましい。
The substance amount of the internal cross-linking agent other than the internal cross-linking agent (b) is preferably 0 to 50 mol parts per 100 mol parts of the internal cross-linking agent (b) from the viewpoint of decomposition performance.
前記吸水性樹脂組成物は、その性能を損なわない範囲で残留溶媒や残存架橋成分等の他の成分を多少含んでも良い。
The water-absorbing resin composition may contain some other components such as residual solvent and residual cross-linking components within a range that does not impair its performance.
前記他の成分のその他の例としては、防腐剤、防かび剤、抗菌剤、紫外線吸収剤、酸化防止剤、着色剤、芳香剤、消臭剤、通液性向上剤、無機質粉末及び有機質繊維状物等が挙げられる。その量は前記吸水性樹脂組成物の重量に基づいて、通常、５重量％以下である。
Other examples of the other components include preservatives, antifungal agents, antibacterial agents, ultraviolet absorbers, antioxidants, colorants, fragrances, deodorants, liquid permeability improvers, inorganic powders and organic fibers. and the like. The amount is usually 5% by weight or less based on the weight of the water absorbent resin composition.
前記吸水性樹脂組成物は、吸水性能の観点から、前記他の成分として、好ましくはヨウ素、テルル、アンチモン及びビスマスからなる群から選ばれる少なくとも１種の典型元素を含むことが好ましい。前記吸水性樹脂組成物が当該典型元素を含む場合、前記吸水性樹脂組成物中の当該典型元素の含有量は、吸水性能の観点から、０．０００５～０．１重量％が好ましく、０．００１～０．０５重量％がより好ましい。
From the viewpoint of water absorption performance, the water absorbent resin composition preferably contains at least one typical element selected from the group consisting of iodine, tellurium, antimony and bismuth as the other component. When the water absorbent resin composition contains the typical element, the content of the typical element in the water absorbent resin composition is preferably 0.0005 to 0.1% by weight from the viewpoint of water absorption performance. 001 to 0.05% by weight is more preferred.
前記吸水性樹脂組成物の形状については特に限定はなく、不定形破砕状、リン片状、パール状及び米粒状等が挙げられる。これらのうち、紙おむつ用途等での繊維状物とのからみが良く、繊維状物からの脱落の心配がないという観点から、不定形破砕状が好ましい。
The shape of the water-absorbing resin composition is not particularly limited, and examples thereof include irregular crushed shape, scaly shape, pearl-like shape, and rice grain-like shape. Of these, irregularly crushed forms are preferred from the viewpoints of good entanglement with fibrous materials for use in paper diapers and the like, and no fear of falling off from fibrous materials.
前記吸水性樹脂組成物は、パルプ繊維とともに衛生用品の構成成分となりうる。衛生用品としては、例えば、紙おむつ、生理用ナプキン、失禁製品、ペットシート等が挙げられる。衛生用品の製造方法等は、公知のもの（特開２００３－２２５５６５号公報、特開２００６－１３１７６７号公報及び特開２００５－０９７５６９号公報等に記載のもの）と同様である。
The water-absorbing resin composition can be a component of sanitary products together with pulp fibers. Examples of sanitary products include paper diapers, sanitary napkins, incontinence products, and pet sheets. The method for producing the sanitary goods is the same as the known ones (described in JP-A-2003-225565, JP-A-2006-131767, JP-A-2005-097569, etc.).
前記吸水性樹脂組成物は、酸化剤により、内部架橋剤（ｂ）部位が選択的に分解され、分解物は水溶化させることが可能である。
In the water-absorbing resin composition, the internal cross-linking agent (b) site is selectively decomposed by an oxidizing agent, and the decomposed product can be water-soluble.
＜吸水性樹脂組成物の処理方法＞
本実施形態の吸水性樹脂組成物の処理方法は、前記吸水性樹脂組成物を酸化剤で分解する分解工程を含む。前記吸水性樹脂組成物に含有される架橋重合体（Ａ）は、酸化剤により、解重合される。 <Method for treating water absorbent resin composition>
The method for treating the water absorbent resin composition of the present embodiment includes a decomposition step of decomposing the water absorbent resin composition with an oxidizing agent. The crosslinked polymer (A) contained in the water absorbent resin composition is depolymerized by an oxidizing agent.
本実施形態の吸水性樹脂組成物の処理方法は、前記吸水性樹脂組成物を酸化剤で分解する分解工程を含む。前記吸水性樹脂組成物に含有される架橋重合体（Ａ）は、酸化剤により、解重合される。 <Method for treating water absorbent resin composition>
The method for treating the water absorbent resin composition of the present embodiment includes a decomposition step of decomposing the water absorbent resin composition with an oxidizing agent. The crosslinked polymer (A) contained in the water absorbent resin composition is depolymerized by an oxidizing agent.
前記分解工程で使用する酸化剤は、前記架橋重合体（Ａ）を分解して解重合することができれば、特に限定されない。
The oxidizing agent used in the decomposition step is not particularly limited as long as it can decompose and depolymerize the crosslinked polymer (A).
分解処理工程に供される吸水性樹脂組成物は、水を保持していてもよい。酸化剤と反応することで、架橋重合体（Ａ）が有する特定の結合を選択的に切断することにより解重合される。そして解重合によって生成された分解物は分解前の吸水性樹脂組成物が保持していた水に溶解又は懸濁することとなる。
The water absorbent resin composition to be subjected to the decomposition treatment process may retain water. By reacting with an oxidizing agent, the crosslinked polymer (A) is depolymerized by selectively breaking specific bonds. Decomposition products produced by depolymerization are dissolved or suspended in the water retained in the water absorbent resin composition before decomposition.
前記吸水性樹脂組成物を分解するために使用する酸化剤として、例えば、過酸化水素、オゾン、次亜塩素酸塩、亜塩素酸塩、塩素酸塩、過塩素酸塩、過炭酸塩、過ホウ酸塩、過カルボン酸およびニトロキシルラジカル化合物からなる群より選ばれる１種以上であると好ましい。本発明の製造方法においては、大気中の酸素も酸化剤として作用しうるが、酸素以外の上記例示の酸化剤を用いるのが好ましく、上記の群より選ばれる１種類以上の酸化剤を用いるとより好ましい。また、単体の酸素が共存する環境下で、吸水性樹脂組成物の分解を行ってもよい。
Examples of the oxidizing agent used to decompose the water absorbent resin composition include hydrogen peroxide, ozone, hypochlorite, chlorite, chlorate, perchlorate, percarbonate, percarbonate, It is preferably one or more selected from the group consisting of borates, percarboxylic acids and nitroxyl radical compounds. In the production method of the present invention, atmospheric oxygen can also act as an oxidizing agent, but it is preferable to use an oxidizing agent other than oxygen as exemplified above. more preferred. Further, the decomposition of the water-absorbing resin composition may be performed in an environment where simple oxygen coexists.
過酸化水素としては、これを水に溶解し過酸化水素水溶液としたものが好ましいが、過酸化水素水を有機溶媒に溶解したものであってもよい。過酸化水素水溶液としては３０重量％濃度のものが入手しやすく、かつ液量が少なくて済み好ましい。
The hydrogen peroxide is preferably dissolved in water to form a hydrogen peroxide aqueous solution, but it may be dissolved in an organic solvent. An aqueous solution of hydrogen peroxide having a concentration of 30% by weight is readily available, and it is preferable because it requires only a small amount of liquid.
次亜塩素酸塩、亜塩素酸塩、塩素酸塩、過塩素酸塩、過炭酸塩、過ホウ酸塩などはアルカリ金属塩またはアルカリ土類金属塩であると入手しやすいので好ましく、ナトリウム塩、カリウム塩、カルシウム塩であるとより好ましく、次亜塩素酸ナトリウム塩（ＮａＣｌＯ）であると特に好ましい。これらの塩も水などの溶媒に溶解して用いることができる。更に、使用済おむつから取出して得られる、あるいは、使用済おむつ中に含まれる架橋重合体（Ａ）を処理する際にも次亜塩素酸塩、亜塩素酸塩、塩素酸塩、過塩素酸塩等を使用することで、殺菌や滅菌を行いつつ可溶化処理することができるため、例えば、使用済おむつに含まれるパルプを再利用する場合にも改めて殺菌や滅菌する必要がない、あるいは、殺菌剤の使用量を減らすことができるため、経済的である。
Hypochlorite, chlorite, chlorate, perchlorate, percarbonate, perborate, etc. are preferably alkali metal salts or alkaline earth metal salts because they are readily available, and sodium salts. , potassium salt, and calcium salt, and particularly preferably sodium hypochlorite (NaClO). These salts can also be dissolved in a solvent such as water and used. Furthermore, hypochlorite, chlorite, chlorate, and perchloric acid are also used when treating the crosslinked polymer (A) obtained by removing from used diapers or contained in used diapers. By using a salt or the like, it is possible to solubilize while sterilizing and sterilizing, so for example, when reusing the pulp contained in used diapers, there is no need to sterilize or sterilize it again, or It is economical because the amount of disinfectant used can be reduced.
前記吸水性樹脂組成物が衛生用品に含まれる場合、処理効率の観点から、衛生用品から前記吸水性樹脂組成物を分離した後、分解処理することが好ましい。
When the water-absorbing resin composition is contained in sanitary goods, it is preferable, from the viewpoint of processing efficiency, to separate the water-absorbing resin composition from the sanitary goods and then decompose it.
前記吸水性樹脂組成物の衛生用品からの分離は、公知の方法により行うことができる。衛生用品から前記吸水性樹脂組成物を分離する公知の方法としては、例えば、使用済おむつからパルプを回収するために、次亜塩素酸ナトリウム水溶液、及び過マンガン酸カリウム水溶液を用いることで、吸水性樹脂組成物の結合を切断することによる水溶化の方法（特開２０２１－００１７８３号公報）、過ヨウ素酸塩を含む分解剤を用いる方法（特開２００１－３１６５９号公報）、アルカリ水溶液を用いて加水分解することで水溶化する方法（特開２０２０－０４９３９８）、不活化水溶液としてクエン酸などの酸を用いることで、前記吸水性樹脂組成物中の中和部分を未中和状態へと変換し、パルプとの分離を促進する方法（特開２０１９－０８５６８６）、粉砕したおむつを水の入った槽に入れ、パルプと前記吸水性樹脂組成物との比重及び沈降速度の差を利用することで分離方法（特開２００２－２７３７３１）も挙げられる。
The water absorbent resin composition can be separated from the sanitary goods by a known method. As a known method for separating the water absorbent resin composition from sanitary goods, for example, in order to recover pulp from used diapers, an aqueous sodium hypochlorite solution and an aqueous potassium permanganate solution are used to absorb water. A method of water solubilization by breaking the bond of the resin composition (JP 2021-001783), a method using a decomposing agent containing periodate (JP 2001-31659), using an alkaline aqueous solution (JP 2020-049398), and by using an acid such as citric acid as an inactivating aqueous solution, the neutralized portion in the water-absorbing resin composition is converted to an unneutralized state. A method of converting and promoting separation from the pulp (JP 2019-085686), putting the pulverized diaper in a tank containing water, and utilizing the difference in specific gravity and sedimentation speed between the pulp and the water absorbent resin composition. A separation method (Japanese Unexamined Patent Application Publication No. 2002-273731) can also be mentioned.
前記吸水性樹脂組成物を含む衛生用品を分解処理する場合は、衛生用品を粉砕する工程（以下、「粉砕工程」と称する）を経た衛生用品を分解処理することが分解効率の観点から好ましい。
When the sanitary goods containing the water-absorbent resin composition are to be decomposed, it is preferable from the viewpoint of decomposition efficiency to decompose the sanitary goods that have undergone a process of pulverizing the sanitary goods (hereinafter referred to as a "pulverization process").
前記粉砕工程は、衛生用品を粉砕して粉砕物を得る工程である。粉砕は公知の粉砕機又は破砕機を使用することができ、例えば生ごみ粉砕機に使われているディスポーザー型破砕機（高速回転するターンテーブルで該衛生用品を壁面に飛ばし、ターンテーブル周縁部についている固定式、又は可変式のハンマーと壁面の固定刃等で破砕）、カッターミル、一軸型破砕機、二軸型破砕機、同軸心型破砕機、ハンマー式破砕機、ボールミル等が挙げられるが、衛生用品の素材にはプラスチック製のシートや不織布、伸縮性のある材料が含まれることから、高速回転しながら刃で切断するディスポーザー型破砕機やカッターミルが特に好適である。
The pulverizing step is a step of pulverizing sanitary goods to obtain pulverized products. For pulverization, a known pulverizer or crusher can be used, for example, a disposer-type crusher used in a kitchen garbage crusher (a turntable that rotates at high speed throws the sanitary product on the wall surface, and the peripheral edge of the turntable Crushing with a fixed or variable hammer and a fixed blade on the wall), cutter mill, single shaft crusher, twin shaft crusher, coaxial crusher, hammer crusher, ball mill, etc. Since materials for sanitary products include plastic sheets, non-woven fabrics, and stretchable materials, a disposer-type crusher or cutter mill that cuts with a blade while rotating at high speed is particularly suitable.
衛生用品の粉砕物は、水性懸濁液に含まれていてもよい。衛生用品の粉砕物が含まれる水性懸濁液を得る方法としては、水を加えて衛生用品を膨潤させた後粉砕する方法、粉砕しながら水を加えて粉砕する方法、粉砕後に水を加える方法があるが、粉砕機への負荷低減の観点から、水を加えて衛生用品を膨潤させた後粉砕する方法が好ましい。
The pulverized sanitary products may be contained in the aqueous suspension. Methods for obtaining an aqueous suspension containing pulverized sanitary products include a method of adding water to swell the sanitary products and then pulverizing them, a method of pulverizing by adding water while pulverizing, and a method of adding water after pulverizing. However, from the viewpoint of reducing the load on the pulverizer, it is preferable to add water to swell the sanitary goods and then pulverize them.
衛生用品の粉砕物の大きさの好適な範囲は、前記遠心脱水工程による分離回収方式にも依存するが、水流での輸送性の観点から、好ましくは衛生用品の一片の長さが１００ｍｍ以下である。粉砕物の大きさは、前述した粉砕機又は破砕機の種類、及び処理条件等により適宜調整可能である。
The preferred range of the size of the pulverized product of the sanitary product depends on the separation and recovery method by the centrifugal dehydration step, but from the viewpoint of transportability with a water stream, the length of one piece of the sanitary product is preferably 100 mm or less. be. The size of the pulverized product can be appropriately adjusted depending on the type of pulverizer or crusher described above, processing conditions, and the like.
前記吸水性樹脂組成物の分解処理の方法の際、さらに吸水性樹脂組成物の脱水処理工程を処理工程の中に含んでもよい（特開２０２０－１１６５６９公報）。特に限定されないが、架橋重合体（Ａ）を効率的に分解処理する観点から、前記脱水工程は、酸及び／又は水溶性多価金属化合物を含有する処理液に、前記吸水性樹脂組成物を浸漬させる脱水前処理工程、及び前記脱水前処理工程を経た前記吸水性樹脂組成物を遠心脱水する遠心脱水工程を有するのが好ましい。なお、脱水前処理工程に供される前記吸水性樹脂組成物は、使用済衛生用品や未使用衛生用品等の衛生用品に含まれる前記吸水性樹脂組成物も含まれる。
In the method of decomposing the water-absorbent resin composition, a dehydration treatment step of the water-absorbent resin composition may be further included in the treatment process (Japanese Patent Application Laid-Open No. 2020-116569). Although not particularly limited, from the viewpoint of efficiently decomposing the crosslinked polymer (A), the dehydration step includes adding the water-absorbent resin composition to a treatment liquid containing an acid and/or a water-soluble polyvalent metal compound. It is preferable to have a dehydration pretreatment step of immersing and a centrifugal dehydration step of centrifugally dehydrating the water absorbent resin composition that has undergone the dehydration pretreatment step. The water absorbent resin composition to be subjected to the dehydration pretreatment step also includes the water absorbent resin composition contained in sanitary products such as used sanitary products and unused sanitary products.
以下、実施例及び比較例により本発明を更に説明するが、本発明はこれらに限定されるものではない。以下、特に定めない限り、部は重量部、％は重量％を示す。
The present invention will be further described below with reference to Examples and Comparative Examples, but the present invention is not limited to these. Hereinafter, unless otherwise specified, parts indicate parts by weight and % indicates % by weight.
実施例および比較例で得られた吸水性樹脂組成物の、０．９重量％生理食塩水に対する保水量、０．９重量％生理食塩水に対する荷重下吸収量、及びＶｏｒｔｅｘ法による吸収速度、及び吸湿ブロッキング率は、２５±２℃、湿度５０±１０％の室内でそれぞれ以下の方法で測定した。なお、使用する生理食塩水の温度は予め２５℃±２℃に調整して使用した。
The water-absorbent resin compositions obtained in Examples and Comparative Examples have a water retention capacity with respect to 0.9 wt% physiological saline, an absorption capacity under load with respect to 0.9 wt% physiological saline, and an absorption rate according to the Vortex method, and The moisture absorption blocking rate was measured in a room at 25±2° C. and a humidity of 50±10% by the following methods. The temperature of the physiological saline used was previously adjusted to 25°C ± 2°C.
＜０．９重量％生理食塩水に対する保水量の測定方法＞
目開き６３μｍ（ＪＩＳ Ｚ８８０１－１：２００６）のナイロン網で作製したティーバッグ（縦２０ｃｍ、横１０ｃｍ）に測定試料１．００ｇを入れ、生理食塩水（食塩濃度０．９％）１，０００ｍｌ中に無撹拌下、１時間浸漬した後引き上げて、１５分間吊るして水切りした。その後、ティーバッグごと、遠心分離器にいれ、１５０Ｇで９０秒間遠心脱水して余剰の生理食塩水を取り除き、ティーバックを含めた重量（ｈ１）を測定し次式から保水量を求めた。なお、使用した生理食塩水及び測定雰囲気の温度は２５℃±２℃であった。
保水量（ｇ／ｇ）＝（ｈ１）－（ｈ２）
なお、（ｈ２）は、測定試料の無い場合について上記と同様の操作により計測したティーバックの重量である。 <Method for measuring water retention in 0.9% by weight physiological saline>
Put 1.00 g of the measurement sample in a tea bag (20 cm long, 10 cm wide) made of nylon mesh with an opening of 63 μm (JIS Z8801-1: 2006), and put it in 1,000 ml of physiological saline (salt concentration 0.9%). After being immersed for 1 hour without stirring, it was taken out and hung for 15 minutes to drain off the water. After that, the whole tea bag was placed in a centrifuge and dehydrated by centrifugation at 150 G for 90 seconds to remove excess physiological saline. The physiological saline used and the temperature of the measurement atmosphere were 25°C ± 2°C.
Water retention amount (g/g) = (h1) - (h2)
In addition, (h2) is the weight of the tea bag measured by the same operation as above without the measurement sample.
目開き６３μｍ（ＪＩＳ Ｚ８８０１－１：２００６）のナイロン網で作製したティーバッグ（縦２０ｃｍ、横１０ｃｍ）に測定試料１．００ｇを入れ、生理食塩水（食塩濃度０．９％）１，０００ｍｌ中に無撹拌下、１時間浸漬した後引き上げて、１５分間吊るして水切りした。その後、ティーバッグごと、遠心分離器にいれ、１５０Ｇで９０秒間遠心脱水して余剰の生理食塩水を取り除き、ティーバックを含めた重量（ｈ１）を測定し次式から保水量を求めた。なお、使用した生理食塩水及び測定雰囲気の温度は２５℃±２℃であった。
保水量（ｇ／ｇ）＝（ｈ１）－（ｈ２）
なお、（ｈ２）は、測定試料の無い場合について上記と同様の操作により計測したティーバックの重量である。 <Method for measuring water retention in 0.9% by weight physiological saline>
Put 1.00 g of the measurement sample in a tea bag (20 cm long, 10 cm wide) made of nylon mesh with an opening of 63 μm (JIS Z8801-1: 2006), and put it in 1,000 ml of physiological saline (salt concentration 0.9%). After being immersed for 1 hour without stirring, it was taken out and hung for 15 minutes to drain off the water. After that, the whole tea bag was placed in a centrifuge and dehydrated by centrifugation at 150 G for 90 seconds to remove excess physiological saline. The physiological saline used and the temperature of the measurement atmosphere were 25°C ± 2°C.
Water retention amount (g/g) = (h1) - (h2)
In addition, (h2) is the weight of the tea bag measured by the same operation as above without the measurement sample.
＜０．９重量％生理食塩水に対する荷重下吸収量の測定方法＞
目開き６３μｍ（ＪＩＳ Ｚ８８０１－１：２００６）のナイロン網を底面に貼った円筒型プラスチックチューブ（内径：２５ｍｍ、高さ：３４ｍｍ）内に、標準ふるいを用いて２５０～５００μｍの範囲にふるい分けした測定試料０．１６ｇを秤量し、円筒型プラスチックチューブを垂直にしてナイロン網上に測定試料がほぼ均一厚さになるように整えた後、この測定試料の上に分銅（重量：３１０．６ｇ、外径：２４．５ｍｍ、）を乗せる。この円筒型プラスチックチューブ全体の重量（Ｍ１）を計量した後、生理食塩水（食塩濃度０．９％）６０ｍｌの入ったシャーレ（直径：１２ｃｍ）の中に測定試料及び分銅の入った円筒型プラスチックチューブを垂直に立ててナイロン網側を下面にして浸し、６０分静置する。６０分後に、円筒型プラスチックチューブをシャーレから引き上げ、これを斜めに傾けて底部に付着した水を一箇所に集めて水滴として垂らすことで余分な水を除去した後、測定試料及び分銅の入った円筒型プラスチックチューブ全体の重量（Ｍ２）を計量し、次式から荷重下吸収量を求めた。なお、使用した生理食塩水及び測定雰囲気の温度は２５℃±２℃であった。
荷重下吸収量（ｇ／ｇ）＝｛（Ｍ２）－（Ｍ１）｝／０．１６ <Method for measuring absorbency under load with respect to 0.9% by weight physiological saline>
Measured by sieving into a range of 250 to 500 μm using a standard sieve in a cylindrical plastic tube (inner diameter: 25 mm, height: 34 mm) with a nylon mesh of 63 μm (JIS Z8801-1: 2006) attached to the bottom. A 0.16 g sample was weighed, and the cylindrical plastic tube was set vertically so that the sample to be measured had a uniform thickness on the nylon net. Diameter: 24.5 mm,) is placed. After measuring the weight (M1) of the entire cylindrical plastic tube, a cylindrical plastic tube containing a measurement sample and a weight in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline (salt concentration 0.9%) The tube is placed vertically with the nylon mesh side facing down, and left to stand for 60 minutes. After 60 minutes, the cylindrical plastic tube was pulled up from the petri dish, tilted to collect the water adhering to the bottom in one place, and dripped down to remove excess water. The weight (M2) of the entire cylindrical plastic tube was weighed, and the absorption under load was obtained from the following formula. The physiological saline used and the temperature of the measurement atmosphere were 25°C ± 2°C.
Absorption under load (g/g) = {(M2) - (M1)}/0.16
目開き６３μｍ（ＪＩＳ Ｚ８８０１－１：２００６）のナイロン網を底面に貼った円筒型プラスチックチューブ（内径：２５ｍｍ、高さ：３４ｍｍ）内に、標準ふるいを用いて２５０～５００μｍの範囲にふるい分けした測定試料０．１６ｇを秤量し、円筒型プラスチックチューブを垂直にしてナイロン網上に測定試料がほぼ均一厚さになるように整えた後、この測定試料の上に分銅（重量：３１０．６ｇ、外径：２４．５ｍｍ、）を乗せる。この円筒型プラスチックチューブ全体の重量（Ｍ１）を計量した後、生理食塩水（食塩濃度０．９％）６０ｍｌの入ったシャーレ（直径：１２ｃｍ）の中に測定試料及び分銅の入った円筒型プラスチックチューブを垂直に立ててナイロン網側を下面にして浸し、６０分静置する。６０分後に、円筒型プラスチックチューブをシャーレから引き上げ、これを斜めに傾けて底部に付着した水を一箇所に集めて水滴として垂らすことで余分な水を除去した後、測定試料及び分銅の入った円筒型プラスチックチューブ全体の重量（Ｍ２）を計量し、次式から荷重下吸収量を求めた。なお、使用した生理食塩水及び測定雰囲気の温度は２５℃±２℃であった。
荷重下吸収量（ｇ／ｇ）＝｛（Ｍ２）－（Ｍ１）｝／０．１６ <Method for measuring absorbency under load with respect to 0.9% by weight physiological saline>
Measured by sieving into a range of 250 to 500 μm using a standard sieve in a cylindrical plastic tube (inner diameter: 25 mm, height: 34 mm) with a nylon mesh of 63 μm (JIS Z8801-1: 2006) attached to the bottom. A 0.16 g sample was weighed, and the cylindrical plastic tube was set vertically so that the sample to be measured had a uniform thickness on the nylon net. Diameter: 24.5 mm,) is placed. After measuring the weight (M1) of the entire cylindrical plastic tube, a cylindrical plastic tube containing a measurement sample and a weight in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline (salt concentration 0.9%) The tube is placed vertically with the nylon mesh side facing down, and left to stand for 60 minutes. After 60 minutes, the cylindrical plastic tube was pulled up from the petri dish, tilted to collect the water adhering to the bottom in one place, and dripped down to remove excess water. The weight (M2) of the entire cylindrical plastic tube was weighed, and the absorption under load was obtained from the following formula. The physiological saline used and the temperature of the measurement atmosphere were 25°C ± 2°C.
Absorption under load (g/g) = {(M2) - (M1)}/0.16
＜Ｖｏｒｔｅｘ法による吸収速度＞
吸収性樹脂粒組成物２．０００ｇが、ＪＩＳ Ｒ ３５０３に規定する底面が平らな１００ｍｌのトールビーカー内で毎分６００回の回転数で撹拌されている生理食塩水５０ｇを吸収し終わるまでに必要とした時間（単位：秒）をＪＩＳ Ｋ７２２４－１９９６に準拠して測定し、Ｖｏｒｔｅｘ試験で測定される吸収速度とした。 <Absorption rate by Vortex method>
Required until 2.000 g of the absorbent resin granule composition absorbs 50 g of physiological saline stirred at 600 revolutions per minute in a 100 ml tall beaker with a flat bottom defined in JIS R 3503. The time (unit: seconds) was measured according to JIS K7224-1996, and was taken as the absorption rate measured by the Vortex test.
吸収性樹脂粒組成物２．０００ｇが、ＪＩＳ Ｒ ３５０３に規定する底面が平らな１００ｍｌのトールビーカー内で毎分６００回の回転数で撹拌されている生理食塩水５０ｇを吸収し終わるまでに必要とした時間（単位：秒）をＪＩＳ Ｋ７２２４－１９９６に準拠して測定し、Ｖｏｒｔｅｘ試験で測定される吸収速度とした。 <Absorption rate by Vortex method>
Required until 2.000 g of the absorbent resin granule composition absorbs 50 g of physiological saline stirred at 600 revolutions per minute in a 100 ml tall beaker with a flat bottom defined in JIS R 3503. The time (unit: seconds) was measured according to JIS K7224-1996, and was taken as the absorption rate measured by the Vortex test.
＜吸湿ブロッキング率＞
吸水性樹脂組成物５．００ｇを直径５ｃｍのアルミニウム製円柱皿内に均一になるように入れて、３０±１℃、８０±５％ＲＨの恒温恒湿槽内で３時間静置した。次に、恒温恒湿槽内から前記アルミニウム製円柱皿を静かに取出し、用意した皿金属ふるい受け皿（直径８．０ｃｍ）を下に付けた直径８．０ｃｍ、目開き１．４ｍｍの金属ふるい（受け皿と金属ふるいを併せて装置Ｆとする）に、この吸水性樹脂組成物５．００ｇを全量、その形状が崩れないように慎重に移した。さらに、パウダーテスター（ホソカワミクロン社製 型番 ＰＴ―Ｘ）の付属品である凝集度フルイオサエを前記装置Ｆの上に重ね、フルイホルダーを取り付け、前記パウダーテスター内にある「振動ユニット」の条件を、振幅を０．８ｍｍ、動作時間を４０秒、スローダウンを０秒、周波数を６０Ｈｚとし、振動させた。
前記金属ふるいと吸水性樹脂組成物の合計重量をＬ１、振動後、金属ふるいとそのふるい上に残った試料の重量の合計をＬ２、金属ふるいの重量をＬ０とした。
（吸湿ブロッキング率（％））＝（Ｌ２－Ｌ０）×１００／（Ｌ１－Ｌ０） <Moisture absorption blocking rate>
5.00 g of the water-absorbent resin composition was placed uniformly in an aluminum cylindrical dish with a diameter of 5 cm, and allowed to stand in a constant temperature and humidity bath at 30±1° C. and 80±5% RH for 3 hours. Next, the aluminum cylindrical dish was gently removed from the constant temperature and humidity chamber, and a metal sieve with a diameter of 8.0 cm and an opening of 1.4 mm was attached to the bottom of the prepared metal sieve tray (diameter: 8.0 cm). The entire amount of 5.00 g of this water-absorbing resin composition was carefully transferred to the apparatus F, in which the saucer and the metal sieve were combined, so as not to lose its shape. Furthermore, the agglomeration sieve, which is an accessory of the powder tester (manufactured by Hosokawa Micron Corporation, model number PT-X), is placed on the device F, the sieve holder is attached, and the conditions of the "vibration unit" in the powder tester are changed to amplitude was 0.8 mm, the operating time was 40 seconds, the slowdown was 0 seconds, and the frequency was 60 Hz.
The total weight of the metal sieve and the water absorbent resin composition was L1, the total weight of the metal sieve and the sample remaining on the sieve after vibration was L2, and the weight of the metal sieve was L0.
(Moisture absorption blocking rate (%)) = (L2-L0) x 100/(L1-L0)
吸水性樹脂組成物５．００ｇを直径５ｃｍのアルミニウム製円柱皿内に均一になるように入れて、３０±１℃、８０±５％ＲＨの恒温恒湿槽内で３時間静置した。次に、恒温恒湿槽内から前記アルミニウム製円柱皿を静かに取出し、用意した皿金属ふるい受け皿（直径８．０ｃｍ）を下に付けた直径８．０ｃｍ、目開き１．４ｍｍの金属ふるい（受け皿と金属ふるいを併せて装置Ｆとする）に、この吸水性樹脂組成物５．００ｇを全量、その形状が崩れないように慎重に移した。さらに、パウダーテスター（ホソカワミクロン社製 型番 ＰＴ―Ｘ）の付属品である凝集度フルイオサエを前記装置Ｆの上に重ね、フルイホルダーを取り付け、前記パウダーテスター内にある「振動ユニット」の条件を、振幅を０．８ｍｍ、動作時間を４０秒、スローダウンを０秒、周波数を６０Ｈｚとし、振動させた。
前記金属ふるいと吸水性樹脂組成物の合計重量をＬ１、振動後、金属ふるいとそのふるい上に残った試料の重量の合計をＬ２、金属ふるいの重量をＬ０とした。
（吸湿ブロッキング率（％））＝（Ｌ２－Ｌ０）×１００／（Ｌ１－Ｌ０） <Moisture absorption blocking rate>
5.00 g of the water-absorbent resin composition was placed uniformly in an aluminum cylindrical dish with a diameter of 5 cm, and allowed to stand in a constant temperature and humidity bath at 30±1° C. and 80±5% RH for 3 hours. Next, the aluminum cylindrical dish was gently removed from the constant temperature and humidity chamber, and a metal sieve with a diameter of 8.0 cm and an opening of 1.4 mm was attached to the bottom of the prepared metal sieve tray (diameter: 8.0 cm). The entire amount of 5.00 g of this water-absorbing resin composition was carefully transferred to the apparatus F, in which the saucer and the metal sieve were combined, so as not to lose its shape. Furthermore, the agglomeration sieve, which is an accessory of the powder tester (manufactured by Hosokawa Micron Corporation, model number PT-X), is placed on the device F, the sieve holder is attached, and the conditions of the "vibration unit" in the powder tester are changed to amplitude was 0.8 mm, the operating time was 40 seconds, the slowdown was 0 seconds, and the frequency was 60 Hz.
The total weight of the metal sieve and the water absorbent resin composition was L1, the total weight of the metal sieve and the sample remaining on the sieve after vibration was L2, and the weight of the metal sieve was L0.
(Moisture absorption blocking rate (%)) = (L2-L0) x 100/(L1-L0)
＜実施例１＞
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．４００部（０．００２８モル部）及び脱イオン水３４４．６５部を攪拌・混合して重合溶液を作製した。２４．９℃に温調した重合溶液を測定試料として使用し、ｐＨメーター（ＬＡＱＵＡ卓上ｐＨ・導電率計 形式Ｆ－７４Ｓ 株式会社堀場製作所社製）を用いて測定したｐＨは１．８であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液０．６３部、２％アスコルビン酸水溶液１．１７７４部及び２％の２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）－プロピオンアミド］水溶液２．３５５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させた。反応容器内の温度が９０℃に達した後、９０±２℃で約５時間重合を続けることにより含水ゲル（１）を得た。次にこの含水ゲル（１）５０２．２７部をミンチ機で細断しながら４８．５％水酸化ナトリウム水溶液１２８．４２部を添加して混合し、含水ゲル裁断物を得た。更に含水ゲル裁断物を通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（１）を得た。この粒子状乾燥体（１）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－１）を得た。 <Example 1>
157 parts (2.18 mol parts) of acrylic acid, 0.400 parts (0.0028 mol parts) of the internal cross-linking agent (b-1) (N,N-diacryloylhydrazine) and 344.65 parts of deionized water are stirred. - A polymerization solution was prepared by mixing. A polymerization solution whose temperature was adjusted to 24.9° C. was used as a measurement sample, and the pH measured using a pH meter (LAQUA desktop pH/conductivity meter, model F-74S, manufactured by Horiba, Ltd.) was 1.8. rice field. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.63 parts of 1% aqueous hydrogen peroxide solution and 1.1774 parts of 2% aqueous ascorbic acid solution were added. Part and 2.355 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] aqueous solution of 2% are added and mixed, and an aqueous solution is prepared by placing it in an insulated container that is a reaction vessel. Adiabatic polymerization was initiated. After the temperature in the reaction vessel reached 90° C., polymerization was continued at 90±2° C. for about 5 hours to obtain hydrous gel (1). Next, 128.42 parts of a 48.5% aqueous sodium hydroxide solution was added to and mixed with 502.27 parts of this hydrous gel (1) while chopping it with a mincing machine to obtain a cut hydrous gel. Further, the water-containing gel cut product was dried with a ventilated band dryer {150° C., wind speed 2 m/sec} to obtain a dry product. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (1). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was sprayed while stirring 100 parts of the dry particulate material (1) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-1) of the present invention.
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．４００部（０．００２８モル部）及び脱イオン水３４４．６５部を攪拌・混合して重合溶液を作製した。２４．９℃に温調した重合溶液を測定試料として使用し、ｐＨメーター（ＬＡＱＵＡ卓上ｐＨ・導電率計 形式Ｆ－７４Ｓ 株式会社堀場製作所社製）を用いて測定したｐＨは１．８であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液０．６３部、２％アスコルビン酸水溶液１．１７７４部及び２％の２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）－プロピオンアミド］水溶液２．３５５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させた。反応容器内の温度が９０℃に達した後、９０±２℃で約５時間重合を続けることにより含水ゲル（１）を得た。次にこの含水ゲル（１）５０２．２７部をミンチ機で細断しながら４８．５％水酸化ナトリウム水溶液１２８．４２部を添加して混合し、含水ゲル裁断物を得た。更に含水ゲル裁断物を通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（１）を得た。この粒子状乾燥体（１）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－１）を得た。 <Example 1>
157 parts (2.18 mol parts) of acrylic acid, 0.400 parts (0.0028 mol parts) of the internal cross-linking agent (b-1) (N,N-diacryloylhydrazine) and 344.65 parts of deionized water are stirred. - A polymerization solution was prepared by mixing. A polymerization solution whose temperature was adjusted to 24.9° C. was used as a measurement sample, and the pH measured using a pH meter (LAQUA desktop pH/conductivity meter, model F-74S, manufactured by Horiba, Ltd.) was 1.8. rice field. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.63 parts of 1% aqueous hydrogen peroxide solution and 1.1774 parts of 2% aqueous ascorbic acid solution were added. Part and 2.355 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] aqueous solution of 2% are added and mixed, and an aqueous solution is prepared by placing it in an insulated container that is a reaction vessel. Adiabatic polymerization was initiated. After the temperature in the reaction vessel reached 90° C., polymerization was continued at 90±2° C. for about 5 hours to obtain hydrous gel (1). Next, 128.42 parts of a 48.5% aqueous sodium hydroxide solution was added to and mixed with 502.27 parts of this hydrous gel (1) while chopping it with a mincing machine to obtain a cut hydrous gel. Further, the water-containing gel cut product was dried with a ventilated band dryer {150° C., wind speed 2 m/sec} to obtain a dry product. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (1). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was sprayed while stirring 100 parts of the dry particulate material (1) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-1) of the present invention.
＜実施例２＞
実施例１において、内部架橋剤（ｂ－１）０．４００部を１５．２部（０．１０９モル部）に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－２）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 2>
In Example 1, the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 15.2 parts (0.109 mol parts). A product (P-2) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
実施例１において、内部架橋剤（ｂ－１）０．４００部を１５．２部（０．１０９モル部）に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－２）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 2>
In Example 1, the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 15.2 parts (0.109 mol parts). A product (P-2) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
＜実施例３＞
実施例１において、内部架橋剤（ｂ－１）０．４００部を０．００４部（０．００００２９モル部）に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－３）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 3>
In Example 1, the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 0.004 parts (0.000029 mol parts). A product (P-3) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
実施例１において、内部架橋剤（ｂ－１）０．４００部を０．００４部（０．００００２９モル部）に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－３）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 3>
In Example 1, the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 0.004 parts (0.000029 mol parts). A product (P-3) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
＜実施例４＞
実施例１において、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部を７．５０部に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－４）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 4>
In Example 1, except that 5.00 parts of the 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water/methanol = 70/30) was changed to 7.50 parts. Similarly, a water absorbent resin composition (P-4) of the present invention was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
実施例１において、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部を７．５０部に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－４）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 4>
In Example 1, except that 5.00 parts of the 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water/methanol = 70/30) was changed to 7.50 parts. Similarly, a water absorbent resin composition (P-4) of the present invention was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
＜実施例５＞
実施例１において、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部を２．５０部に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－５）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 5>
In Example 1, except that 5.00 parts of the 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water/methanol = 70/30) was changed to 2.50 parts. Similarly, a water absorbent resin composition (P-5) of the present invention was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
実施例１において、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部を２．５０部に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－５）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 5>
In Example 1, except that 5.00 parts of the 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water/methanol = 70/30) was changed to 2.50 parts. Similarly, a water absorbent resin composition (P-5) of the present invention was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
＜実施例６＞
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．４００部（０．００２８モル部）、４８．５重量％水酸化ナトリウム水溶液１７９．８部（２．１８モル部）及び脱イオン水２５２．０５部を攪拌・混合して重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは７．０であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液０．６３部、２％アスコルビン酸水溶液１．１７７４部及び２％の２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）－プロピオンアミド］水溶液２．３５５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させ、約１０時間重合することにより含水ゲル（２）を得た。次にこの含水ゲル（２）５０２．２７部をミンチ機で細断しながら９８重量％硫酸水溶液２３．５部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（２）を得た。この粒子状乾燥体（２）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－６）を得た。 <Example 6>
157 parts (2.18 mol parts) of acrylic acid, 0.400 parts (0.0028 mol parts) of internal cross-linking agent (b-1) (N,N-diacryloylhydrazine), 48.5 wt% sodium hydroxide aqueous solution 179.8 parts (2.18 mol parts) and 252.05 parts of deionized water were stirred and mixed to prepare a polymerization solution. The pH of the polymerization solution measured in the same manner as in Example 1 was 7.0. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.63 parts of 1% aqueous hydrogen peroxide solution and 1.1774 parts of 2% aqueous ascorbic acid solution were added. Part and 2.355 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] aqueous solution of 2% are added and mixed, and an aqueous solution is prepared by placing it in an insulated container that is a reaction vessel. Adiabatic polymerization was started and polymerization was carried out for about 10 hours to obtain a hydrous gel (2). Next, while chopping 502.27 parts of this hydrous gel (2) with a mincing machine, 23.5 parts of a 98% by weight sulfuric acid aqueous solution was added and mixed, and further aerated band dryer {150 ° C., wind speed 2 m / sec. } to obtain a dry product. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (2). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water/methanol=70/30) was sprayed while stirring 100 parts of the dried particulate material (2) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-6) of the present invention.
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．４００部（０．００２８モル部）、４８．５重量％水酸化ナトリウム水溶液１７９．８部（２．１８モル部）及び脱イオン水２５２．０５部を攪拌・混合して重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは７．０であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液０．６３部、２％アスコルビン酸水溶液１．１７７４部及び２％の２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）－プロピオンアミド］水溶液２．３５５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させ、約１０時間重合することにより含水ゲル（２）を得た。次にこの含水ゲル（２）５０２．２７部をミンチ機で細断しながら９８重量％硫酸水溶液２３．５部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（２）を得た。この粒子状乾燥体（２）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－６）を得た。 <Example 6>
157 parts (2.18 mol parts) of acrylic acid, 0.400 parts (0.0028 mol parts) of internal cross-linking agent (b-1) (N,N-diacryloylhydrazine), 48.5 wt% sodium hydroxide aqueous solution 179.8 parts (2.18 mol parts) and 252.05 parts of deionized water were stirred and mixed to prepare a polymerization solution. The pH of the polymerization solution measured in the same manner as in Example 1 was 7.0. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.63 parts of 1% aqueous hydrogen peroxide solution and 1.1774 parts of 2% aqueous ascorbic acid solution were added. Part and 2.355 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] aqueous solution of 2% are added and mixed, and an aqueous solution is prepared by placing it in an insulated container that is a reaction vessel. Adiabatic polymerization was started and polymerization was carried out for about 10 hours to obtain a hydrous gel (2). Next, while chopping 502.27 parts of this hydrous gel (2) with a mincing machine, 23.5 parts of a 98% by weight sulfuric acid aqueous solution was added and mixed, and further aerated band dryer {150 ° C., wind speed 2 m / sec. } to obtain a dry product. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (2). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water/methanol=70/30) was sprayed while stirring 100 parts of the dried particulate material (2) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-6) of the present invention.
＜実施例７＞
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．４００部、４８．５重量％水酸化ナトリウム水溶液１８０．３部（２．１９モル部）及び脱イオン水２５２．０５部を攪拌・混合して重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは１０．２であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、４，４’－アゾビス（４－シアノ吉草酸）０．０４５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させ、約１０時間重合することにより含水ゲル（３）を得た。次にこの含水ゲル（３）５０２．２７部をミンチ機で細断しながら９８重量％硫酸水溶液１３．９部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（３）を得た。この粒子状乾燥体（３）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－７）を得た。 <Example 7>
157 parts of acrylic acid (2.18 mol parts), 0.400 parts of internal cross-linking agent (b-1) (N,N-diacryloylhydrazine), 180.3 parts of 48.5% by weight aqueous sodium hydroxide solution (2. 19 mol parts) and 252.05 parts of deionized water were stirred and mixed to prepare a polymerization solution. The pH of the polymerization solution measured in the same manner as in Example 1 was 10.2. Subsequently, nitrogen was introduced into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.045 part of 4,4′-azobis(4-cyanovaleric acid) was added. - Aqueous solution adiabatic polymerization was initiated by mixing and putting into a heat insulating container which is a reaction vessel, and water-containing gel (3) was obtained by polymerizing for about 10 hours. Next, 13.9 parts of a 98% by weight aqueous solution of sulfuric acid was added to 502.27 parts of this hydrous gel (3) while being finely chopped with a mincing machine, followed by mixing with a ventilated band dryer {150° C., wind speed of 2 m/sec. } to obtain a dry product. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (3). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was sprayed while stirring 100 parts of the dried particulate material (3) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-7) of the present invention.
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．４００部、４８．５重量％水酸化ナトリウム水溶液１８０．３部（２．１９モル部）及び脱イオン水２５２．０５部を攪拌・混合して重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは１０．２であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、４，４’－アゾビス（４－シアノ吉草酸）０．０４５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させ、約１０時間重合することにより含水ゲル（３）を得た。次にこの含水ゲル（３）５０２．２７部をミンチ機で細断しながら９８重量％硫酸水溶液１３．９部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（３）を得た。この粒子状乾燥体（３）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－７）を得た。 <Example 7>
157 parts of acrylic acid (2.18 mol parts), 0.400 parts of internal cross-linking agent (b-1) (N,N-diacryloylhydrazine), 180.3 parts of 48.5% by weight aqueous sodium hydroxide solution (2. 19 mol parts) and 252.05 parts of deionized water were stirred and mixed to prepare a polymerization solution. The pH of the polymerization solution measured in the same manner as in Example 1 was 10.2. Subsequently, nitrogen was introduced into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.045 part of 4,4′-azobis(4-cyanovaleric acid) was added. - Aqueous solution adiabatic polymerization was initiated by mixing and putting into a heat insulating container which is a reaction vessel, and water-containing gel (3) was obtained by polymerizing for about 10 hours. Next, 13.9 parts of a 98% by weight aqueous solution of sulfuric acid was added to 502.27 parts of this hydrous gel (3) while being finely chopped with a mincing machine, followed by mixing with a ventilated band dryer {150° C., wind speed of 2 m/sec. } to obtain a dry product. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (3). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was sprayed while stirring 100 parts of the dried particulate material (3) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-7) of the present invention.
＜実施例８＞
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．０１６１部（０．０００１２モル部）、４８．５重量％水酸化ナトリウム水溶液１８０．４部（２．１９モル部）及び脱イオン水２５２．０５部を攪拌・混合して重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは１１．９であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、４，４’－アゾビス（４－シアノ吉草酸）０．４１２部（富士フィルム和光純薬株式会社製 Ｖ－５０１）を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させ、約１０時間重合することにより含水ゲル（４）を得た。次にこの含水ゲル（４）５０２．２７部をミンチ機で細断しながら９８重量％硫酸水溶液１３．９部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（４）を得た。この粒子状乾燥体（４）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－８）を得た。 <Example 8>
157 parts (2.18 mol parts) of acrylic acid, 0.0161 parts (0.00012 mol parts) of internal cross-linking agent (b-1) (N,N-diacryloylhydrazine), 48.5% by weight aqueous sodium hydroxide solution A polymerization solution was prepared by stirring and mixing 180.4 parts (2.19 mol parts) and 252.05 parts of deionized water. The pH of the polymerization solution measured in the same manner as in Example 1 was 11.9. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3 ° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.412 parts of 4,4'-azobis (4-cyanovaleric acid) (Fuji Film V-501 manufactured by Wako Pure Chemical Industries, Ltd.) was added and mixed, and the mixture was placed in a heat-insulated reaction vessel to initiate aqueous solution adiabatic polymerization, and polymerization was performed for about 10 hours to obtain a hydrous gel (4). Next, while 502.27 parts of this hydrous gel (4) was finely chopped with a mincing machine, 13.9 parts of a 98% by weight sulfuric acid aqueous solution was added and mixed, and further aerated band dryer {150 ° C., wind speed 2 m / sec. } to obtain a dry product. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (4). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was sprayed while stirring 100 parts of the dry particulate material (4) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-8) of the present invention.
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．０１６１部（０．０００１２モル部）、４８．５重量％水酸化ナトリウム水溶液１８０．４部（２．１９モル部）及び脱イオン水２５２．０５部を攪拌・混合して重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは１１．９であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、４，４’－アゾビス（４－シアノ吉草酸）０．４１２部（富士フィルム和光純薬株式会社製 Ｖ－５０１）を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させ、約１０時間重合することにより含水ゲル（４）を得た。次にこの含水ゲル（４）５０２．２７部をミンチ機で細断しながら９８重量％硫酸水溶液１３．９部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（４）を得た。この粒子状乾燥体（４）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－８）を得た。 <Example 8>
157 parts (2.18 mol parts) of acrylic acid, 0.0161 parts (0.00012 mol parts) of internal cross-linking agent (b-1) (N,N-diacryloylhydrazine), 48.5% by weight aqueous sodium hydroxide solution A polymerization solution was prepared by stirring and mixing 180.4 parts (2.19 mol parts) and 252.05 parts of deionized water. The pH of the polymerization solution measured in the same manner as in Example 1 was 11.9. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3 ° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.412 parts of 4,4'-azobis (4-cyanovaleric acid) (Fuji Film V-501 manufactured by Wako Pure Chemical Industries, Ltd.) was added and mixed, and the mixture was placed in a heat-insulated reaction vessel to initiate aqueous solution adiabatic polymerization, and polymerization was performed for about 10 hours to obtain a hydrous gel (4). Next, while 502.27 parts of this hydrous gel (4) was finely chopped with a mincing machine, 13.9 parts of a 98% by weight sulfuric acid aqueous solution was added and mixed, and further aerated band dryer {150 ° C., wind speed 2 m / sec. } to obtain a dry product. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (4). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was sprayed while stirring 100 parts of the dry particulate material (4) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-8) of the present invention.
＜実施例９＞
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．０１６１部（０．０００１２部）９８重量％硫酸水３０．１部、及び脱イオン水３４０．６５部を攪拌・混合して重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは１．１であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液０．６３部、２％アスコルビン酸水溶液１．１７７４部及び２％の２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）－プロピオンアミド］水溶液２．３５５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させた。反応容器内の温度が９０℃に達した後、更に９０±２℃で約５時間重合を続けることにより含水ゲル（５）を得た。次にこの含水ゲル（５）５０２．２７部をミンチ機で細断しながら４８．５％水酸化ナトリウム水溶液１４７．９４部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（５）を得た。この粒子状乾燥体（５）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－９）を得た。 <Example 9>
157 parts (2.18 mol parts) of acrylic acid, 0.0161 parts (0.00012 parts) of internal crosslinking agent (b-1) (N,N-diacryloylhydrazine), 30.1 parts of 98% by weight sulfuric acid water, and A polymerization solution was prepared by stirring and mixing 340.65 parts of deionized water. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.1. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.63 parts of 1% aqueous hydrogen peroxide solution and 1.1774 parts of 2% aqueous ascorbic acid solution were added. Part and 2.355 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] aqueous solution of 2% are added and mixed, and an aqueous solution is prepared by placing it in an insulated container that is a reaction vessel. Adiabatic polymerization was initiated. After the temperature in the reaction vessel reached 90° C., the polymerization was continued at 90±2° C. for about 5 hours to obtain hydrous gel (5). Next, 147.94 parts of 48.5% aqueous sodium hydroxide solution was added to 502.27 parts of this hydrous gel (5) and mixed with a mincing machine. 2 m/sec} to obtain a dried body. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (5). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was sprayed while stirring 100 parts of the dried particulate material (5) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-9) of the present invention.
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．０１６１部（０．０００１２部）９８重量％硫酸水３０．１部、及び脱イオン水３４０．６５部を攪拌・混合して重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは１．１であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液０．６３部、２％アスコルビン酸水溶液１．１７７４部及び２％の２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）－プロピオンアミド］水溶液２．３５５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させた。反応容器内の温度が９０℃に達した後、更に９０±２℃で約５時間重合を続けることにより含水ゲル（５）を得た。次にこの含水ゲル（５）５０２．２７部をミンチ機で細断しながら４８．５％水酸化ナトリウム水溶液１４７．９４部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（５）を得た。この粒子状乾燥体（５）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、本発明の吸水性樹脂組成物（Ｐ－９）を得た。 <Example 9>
157 parts (2.18 mol parts) of acrylic acid, 0.0161 parts (0.00012 parts) of internal crosslinking agent (b-1) (N,N-diacryloylhydrazine), 30.1 parts of 98% by weight sulfuric acid water, and A polymerization solution was prepared by stirring and mixing 340.65 parts of deionized water. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.1. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.63 parts of 1% aqueous hydrogen peroxide solution and 1.1774 parts of 2% aqueous ascorbic acid solution were added. Part and 2.355 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] aqueous solution of 2% are added and mixed, and an aqueous solution is prepared by placing it in an insulated container that is a reaction vessel. Adiabatic polymerization was initiated. After the temperature in the reaction vessel reached 90° C., the polymerization was continued at 90±2° C. for about 5 hours to obtain hydrous gel (5). Next, 147.94 parts of 48.5% aqueous sodium hydroxide solution was added to 502.27 parts of this hydrous gel (5) and mixed with a mincing machine. 2 m/sec} to obtain a dried body. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (5). 5.00 parts of a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was sprayed while stirring 100 parts of the dried particulate material (5) at high speed. The mixture was added and mixed while standing at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (P-9) of the present invention.
＜実施例１０＞
実施例１において、内部架橋剤（ｂ－１）０．４００部を９．１５部（０．０６５４モル部）に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－１０）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 10>
In Example 1, the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 9.15 parts (0.0654 mol parts). A product (P-10) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
実施例１において、内部架橋剤（ｂ－１）０．４００部を９．１５部（０．０６５４モル部）に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－１０）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 10>
In Example 1, the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 9.15 parts (0.0654 mol parts). A product (P-10) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
＜実施例１１＞
実施例１において、内部架橋剤（ｂ－１）０．４００部を３．０５部（０．０２１８モル部）に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－１１）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 11>
In Example 1, the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 3.05 parts (0.0218 mol parts). A product (P-11) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
実施例１において、内部架橋剤（ｂ－１）０．４００部を３．０５部（０．０２１８モル部）に変更した以外は、実施例１と同様にして、本発明の吸水性樹脂組成物（Ｐ－１１）を得た。実施例１と同様に測定した重合溶液のｐＨは１．８であった。 <Example 11>
In Example 1, the water absorbent resin composition of the present invention was prepared in the same manner as in Example 1, except that 0.400 parts of the internal cross-linking agent (b-1) was changed to 3.05 parts (0.0218 mol parts). A product (P-11) was obtained. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8.
＜比較例１＞
アクリル酸２．０００部、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．２０６部、水酸化ナトリウム１．５３６部、４，４’－アゾビス（４－シアノ吉草酸）０．４１２部（富士フィルム和光純薬株式会社製 Ｖ－５０１）を水１５部に溶解させ比較用の重合溶液である水溶液を得た。実施例１と同様に測定した水溶液のｐＨは１３．２であった。次いで該水溶液を凍結脱気し、アルゴン雰囲気下８０℃で２１時間加熱することで含水ゲルを得た。この含水ゲルを水で３回デカンテーションし、次いでメタノール２２時間ソックスレー洗浄し、固形物を得た。この固形物を真空乾燥し乾燥体を得た。この乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（６）を得た。得られた粒子状乾燥体（６）を比較用の吸水性樹脂組成物（Ｒ－１）とした。 <Comparative Example 1>
Acrylic acid 2.000 parts, internal cross-linking agent (b-1) (N,N-diacryloylhydrazine) 0.206 parts, sodium hydroxide 1.536 parts, 4,4'-azobis (4-cyanovaleric acid) 0.412 parts (V-501 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 15 parts of water to obtain an aqueous solution as a polymerization solution for comparison. The pH of the aqueous solution measured in the same manner as in Example 1 was 13.2. Then, the aqueous solution was freeze-degassed and heated at 80° C. for 21 hours in an argon atmosphere to obtain a hydrous gel. This water-containing gel was decanted with water three times and then Soxhlet washed with methanol for 22 hours to obtain a solid. This solid matter was vacuum-dried to obtain a dried product. This dried product was pulverized with a juicer mixer to obtain a particulate dried product (6). The obtained particulate dried body (6) was used as a water absorbent resin composition (R-1) for comparison.
アクリル酸２．０００部、内部架橋剤（ｂ－１）（Ｎ，Ｎ－ジアクリロイルヒドラジン）０．２０６部、水酸化ナトリウム１．５３６部、４，４’－アゾビス（４－シアノ吉草酸）０．４１２部（富士フィルム和光純薬株式会社製 Ｖ－５０１）を水１５部に溶解させ比較用の重合溶液である水溶液を得た。実施例１と同様に測定した水溶液のｐＨは１３．２であった。次いで該水溶液を凍結脱気し、アルゴン雰囲気下８０℃で２１時間加熱することで含水ゲルを得た。この含水ゲルを水で３回デカンテーションし、次いでメタノール２２時間ソックスレー洗浄し、固形物を得た。この固形物を真空乾燥し乾燥体を得た。この乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（６）を得た。得られた粒子状乾燥体（６）を比較用の吸水性樹脂組成物（Ｒ－１）とした。 <Comparative Example 1>
Acrylic acid 2.000 parts, internal cross-linking agent (b-1) (N,N-diacryloylhydrazine) 0.206 parts, sodium hydroxide 1.536 parts, 4,4'-azobis (4-cyanovaleric acid) 0.412 parts (V-501 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 15 parts of water to obtain an aqueous solution as a polymerization solution for comparison. The pH of the aqueous solution measured in the same manner as in Example 1 was 13.2. Then, the aqueous solution was freeze-degassed and heated at 80° C. for 21 hours in an argon atmosphere to obtain a hydrous gel. This water-containing gel was decanted with water three times and then Soxhlet washed with methanol for 22 hours to obtain a solid. This solid matter was vacuum-dried to obtain a dried product. This dried product was pulverized with a juicer mixer to obtain a particulate dried product (6). The obtained particulate dried body (6) was used as a water absorbent resin composition (R-1) for comparison.
＜比較例２＞
比較例１で得た粒子状乾燥体（６）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して比較用の吸水性樹脂組成物（Ｒ－２）を得た。 <Comparative Example 2>
While stirring 100 parts of the dry particulate matter (6) obtained in Comparative Example 1 at high speed, a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water/methanol = 70/30) was added at 5.00. were mixed while spraying, and allowed to stand at 150° C. for 30 minutes to obtain a water absorbent resin composition (R-2) for comparison.
比較例１で得た粒子状乾燥体（６）１００部を高速攪拌しながら、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して比較用の吸水性樹脂組成物（Ｒ－２）を得た。 <Comparative Example 2>
While stirring 100 parts of the dry particulate matter (6) obtained in Comparative Example 1 at high speed, a 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water/methanol = 70/30) was added at 5.00. were mixed while spraying, and allowed to stand at 150° C. for 30 minutes to obtain a water absorbent resin composition (R-2) for comparison.
＜比較例３＞
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－２）｛ペンタエリスリトールトリアリルエーテル｝０．６３０５部（０．００２４モル部）及び脱イオン水３４４．６５部を攪拌・混合して比較用の重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは１．８であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液０．６３部、２％アスコルビン酸水溶液１．１７７４部及び２％の２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）－プロピオンアミド］水溶液２．３５５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させた。反応容器内の温度が９０℃に達した後、９０±２℃で約５時間重合を続けることにより含水ゲル（７）を得た。次にこの含水ゲル（７）５０２．２７部をミンチ機で細断しながら４８．５％水酸化ナトリウム水溶液１２８．４２部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（７）を得た。この粒子状乾燥体（７）１００部を高速攪拌しながら硫酸ナトリウムアルミニウムミョウバン１２水和物を０．５部、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、比較用の吸水性樹脂組成物（Ｒ－３）を得た。 <Comparative Example 3>
157 parts (2.18 mol parts) of acrylic acid, 0.6305 parts (0.0024 mol parts) of internal cross-linking agent (b-2) {pentaerythritol triallyl ether} and 344.65 parts of deionized water are stirred and mixed. Then, a polymerization solution for comparison was prepared. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.63 parts of 1% aqueous hydrogen peroxide solution and 1.1774 parts of 2% aqueous ascorbic acid solution were added. Part and 2.355 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] aqueous solution of 2% are added and mixed, and an aqueous solution is prepared by placing it in an insulated container that is a reaction vessel. Adiabatic polymerization was initiated. After the temperature in the reaction vessel reached 90°C, polymerization was continued at 90±2°C for about 5 hours to obtain a hydrous gel (7). Next, 128.42 parts of a 48.5% sodium hydroxide aqueous solution was added to 502.27 parts of this hydrous gel (7) while being finely chopped with a mincing machine, and mixed. 2 m/sec} to obtain a dried body. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (7). While stirring 100 parts of this dried particulate material (7) at high speed, 0.5 parts of sodium aluminum alum dodecahydrate and 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was added while spraying and mixed, and the mixture was allowed to stand at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (R-3) for comparison.
アクリル酸１５７部（２．１８モル部）、内部架橋剤（ｂ－２）｛ペンタエリスリトールトリアリルエーテル｝０．６３０５部（０．００２４モル部）及び脱イオン水３４４．６５部を攪拌・混合して比較用の重合溶液を作製した。実施例１と同様に測定した重合溶液のｐＨは１．８であった。続いて、インキュベータを用いて３℃に冷却した重合溶液中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液０．６３部、２％アスコルビン酸水溶液１．１７７４部及び２％の２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）－プロピオンアミド］水溶液２．３５５部を添加・混合し、反応容器である断熱容器に入れることで水溶液断熱重合を開始させた。反応容器内の温度が９０℃に達した後、９０±２℃で約５時間重合を続けることにより含水ゲル（７）を得た。次にこの含水ゲル（７）５０２．２７部をミンチ機で細断しながら４８．５％水酸化ナトリウム水溶液１２８．４２部を添加して混合し、更に通気型バンド乾燥機｛１５０℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサーにて粉砕し粒子状乾燥体（７）を得た。この粒子状乾燥体（７）１００部を高速攪拌しながら硫酸ナトリウムアルミニウムミョウバン１２水和物を０．５部、エチレングリコールジグリシジルエーテルの２％水／メタノール混合溶液（水／メタノールの重量比＝７０／３０）の５．００部をスプレー噴霧しながら加えて混合し、１５０℃で３０分間静置して表面架橋して、比較用の吸水性樹脂組成物（Ｒ－３）を得た。 <Comparative Example 3>
157 parts (2.18 mol parts) of acrylic acid, 0.6305 parts (0.0024 mol parts) of internal cross-linking agent (b-2) {pentaerythritol triallyl ether} and 344.65 parts of deionized water are stirred and mixed. Then, a polymerization solution for comparison was prepared. The pH of the polymerization solution measured in the same manner as in Example 1 was 1.8. Subsequently, nitrogen was flowed into the polymerization solution cooled to 3° C. using an incubator to make the dissolved oxygen content 1 ppm or less, and then 0.63 parts of 1% aqueous hydrogen peroxide solution and 1.1774 parts of 2% aqueous ascorbic acid solution were added. Part and 2.355 parts of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] aqueous solution of 2% are added and mixed, and an aqueous solution is prepared by placing it in an insulated container that is a reaction vessel. Adiabatic polymerization was initiated. After the temperature in the reaction vessel reached 90°C, polymerization was continued at 90±2°C for about 5 hours to obtain a hydrous gel (7). Next, 128.42 parts of a 48.5% sodium hydroxide aqueous solution was added to 502.27 parts of this hydrous gel (7) while being finely chopped with a mincing machine, and mixed. 2 m/sec} to obtain a dried body. The dried product was pulverized with a juicer mixer to obtain a particulate dried product (7). While stirring 100 parts of this dried particulate material (7) at high speed, 0.5 parts of sodium aluminum alum dodecahydrate and 2% water/methanol mixed solution of ethylene glycol diglycidyl ether (water/methanol weight ratio = 70/30) was added while spraying and mixed, and the mixture was allowed to stand at 150° C. for 30 minutes for surface cross-linking to obtain a water absorbent resin composition (R-3) for comparison.
＜酸化剤による分解性の確認＞
実施例１で得られた吸水性樹脂組成物（Ｐ－１）０．６００ｇを５０ｍｌコニカルビーカーにはかり取り、次いで、５％次亜塩素酸ナトリウム水溶液２０ｍｌに添加して２５℃で、テフロン（登録商標）スパーテル（株式会社エスケー社製）を用いて２００ｒｐｍの速度で攪拌しながら目視で観察し、吸水性樹脂組成物がゲル状から、完全にゲルが消失し、均一な溶液となるまでの時間を５分ごとに測定した。均一な溶液になった時点を酸化剤による分解の終点（酸化剤によって完全に分解された）として、均一な溶液となるまでの経過時間を表１に記載した。吸水性樹脂組成物（Ｐ－２）～（Ｐ－１１）、及び比較例（Ｒ－１）～（Ｒ－３）も同様の操作を行い、分解性を確認した。 <Confirmation of degradability by oxidizing agent>
0.600 g of the water absorbent resin composition (P-1) obtained in Example 1 was weighed into a 50 ml conical beaker, then added to 20 ml of a 5% sodium hypochlorite aqueous solution and heated at 25 ° C. with Teflon (registered (trademark) spatula (manufactured by SK Co., Ltd.) while stirring at a speed of 200 rpm and visually observed. was measured every 5 minutes. Table 1 shows the elapsed time until a homogeneous solution was obtained, with the point at which the solution became homogeneous as the end point of decomposition by the oxidizing agent (completely decomposed by the oxidizing agent). Water absorbent resin compositions (P-2) to (P-11) and comparative examples (R-1) to (R-3) were also subjected to the same operation to confirm the degradability.
実施例１で得られた吸水性樹脂組成物（Ｐ－１）０．６００ｇを５０ｍｌコニカルビーカーにはかり取り、次いで、５％次亜塩素酸ナトリウム水溶液２０ｍｌに添加して２５℃で、テフロン（登録商標）スパーテル（株式会社エスケー社製）を用いて２００ｒｐｍの速度で攪拌しながら目視で観察し、吸水性樹脂組成物がゲル状から、完全にゲルが消失し、均一な溶液となるまでの時間を５分ごとに測定した。均一な溶液になった時点を酸化剤による分解の終点（酸化剤によって完全に分解された）として、均一な溶液となるまでの経過時間を表１に記載した。吸水性樹脂組成物（Ｐ－２）～（Ｐ－１１）、及び比較例（Ｒ－１）～（Ｒ－３）も同様の操作を行い、分解性を確認した。 <Confirmation of degradability by oxidizing agent>
0.600 g of the water absorbent resin composition (P-1) obtained in Example 1 was weighed into a 50 ml conical beaker, then added to 20 ml of a 5% sodium hypochlorite aqueous solution and heated at 25 ° C. with Teflon (registered (trademark) spatula (manufactured by SK Co., Ltd.) while stirring at a speed of 200 rpm and visually observed. was measured every 5 minutes. Table 1 shows the elapsed time until a homogeneous solution was obtained, with the point at which the solution became homogeneous as the end point of decomposition by the oxidizing agent (completely decomposed by the oxidizing agent). Water absorbent resin compositions (P-2) to (P-11) and comparative examples (R-1) to (R-3) were also subjected to the same operation to confirm the degradability.
評価結果を表１に示す。
Table 1 shows the evaluation results.
表１に示す結果から、実施例に係る吸水性樹脂組成物の酸化剤による分解率は比較例１および２と比べて極めて高い。これは吸水性樹脂組成物の表面においてブロッキング率が小さいために、酸化剤が吸水性樹脂組成物の内部に浸透しやすいため、効率的に反応が進行したものと推測される。
From the results shown in Table 1, the decomposition rate of the water-absorbent resin composition according to Example by an oxidizing agent is extremely high compared to Comparative Examples 1 and 2. It is presumed that this is because the oxidizing agent easily permeates into the inside of the water-absorbing resin composition because the blocking rate is small on the surface of the water-absorbing resin composition, and the reaction proceeds efficiently.
Claims (6)
- 水溶性不飽和モノカルボン酸（ａ１）及びその塩、並びに加水分解により前記水溶性不飽和モノカルボン酸（ａ１）となるモノマー（ａ２）からなる群より選ばれる１種以上のモノマー（Ａ１）と、下記一般式（１）で表される内部架橋剤（ｂ）と、を含む単量体組成物を、当該単量体組成物を含み、ｐＨが１～１２である重合溶液中で重合し、架橋重合体（Ａ）を含む含水ゲルを得る重合工程と、
前記架橋重合体（Ａ）を表面架橋剤（ｃ）によって架橋する表面架橋工程を有する吸水性樹脂組成物の製造方法。
A method for producing a water absorbent resin composition comprising a surface cross-linking step of cross-linking the cross-linked polymer (A) with a surface cross-linking agent (c).
- 水溶性不飽和モノカルボン酸（ａ１）及びその塩、並びに下記一般式（１）で表される内部架橋剤（ｂ）を必須構成単位とする架橋重合体（Ａ）の表面が表面架橋剤（ｃ）で表面架橋された吸水性樹脂組成物であって、下記（１）～（３）を満たす吸水性樹脂組成物。
（１）０．９重量％生理食塩水の保水量が単位重量あたり１５～６０ｇ／ｇ
（２）０．９重量％生理食塩水の荷重下吸収量が単位重量あたり１０～２７ｇ／ｇ
（３）Ｖｏｒｔｅｘ法による吸収速度（秒）が８０以下
(1) Water retention capacity of 0.9% by weight saline is 15 to 60 g/g per unit weight
(2) Absorption amount under load of 0.9 wt% physiological saline is 10 to 27 g/g per unit weight
(3) Absorption rate (sec) by Vortex method is 80 or less
- 前記架橋重合体（Ａ）における前記内部架橋剤（ｂ）の物質量の割合が、水溶性不飽和モノカルボン酸（ａ１）の構成単位及びその塩の構成単位の合計１００モル部に対して、０．００１～５モル部である、請求項２に記載の吸水性樹脂組成物。 The ratio of the substance amount of the internal cross-linking agent (b) in the crosslinked polymer (A) is, with respect to a total of 100 mol parts of the constituent units of the water-soluble unsaturated monocarboxylic acid (a1) and the constituent units of its salt, The water absorbent resin composition according to claim 2, which is 0.001 to 5 mol parts.
- 請求項２又は３に記載の吸水性樹脂組成物を含む吸収体。 An absorbent body containing the water absorbent resin composition according to claim 2 or 3.
- 請求項４に記載の吸収体を含む衛生用品。 A sanitary product comprising the absorber according to claim 4.
- 請求項２又は３に記載の吸水性樹脂組成物を酸化剤で分解する分解工程を含む、吸水性樹脂組成物の処理方法。 A method for treating a water absorbent resin composition, comprising a decomposition step of decomposing the water absorbent resin composition according to claim 2 or 3 with an oxidizing agent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2021-167589 | 2021-10-12 | ||
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10101735A (en) * | 1996-08-07 | 1998-04-21 | Nippon Shokubai Co Ltd | Water absorbent and its production |
| WO2021042113A1 (en) * | 2019-08-23 | 2021-03-04 | The Procter & Gamble Company | Degradation of superabsorbent polymer via oxidative degradation |
| WO2021131003A1 (en) * | 2019-12-26 | 2021-07-01 | 学校法人神奈川大学 | Crosslinked polymer compound and method for producing same, absorbent article, paper diaper, sanitary article, disposal container, and disposal method |
| JP2021516720A (en) * | 2018-12-10 | 2021-07-08 | エルジー・ケム・リミテッド | Manufacturing method of highly water-absorbent resin |
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- 2022-10-05 WO PCT/JP2022/037238 patent/WO2023063182A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10101735A (en) * | 1996-08-07 | 1998-04-21 | Nippon Shokubai Co Ltd | Water absorbent and its production |
| JP2021516720A (en) * | 2018-12-10 | 2021-07-08 | エルジー・ケム・リミテッド | Manufacturing method of highly water-absorbent resin |
| WO2021042113A1 (en) * | 2019-08-23 | 2021-03-04 | The Procter & Gamble Company | Degradation of superabsorbent polymer via oxidative degradation |
| WO2021131003A1 (en) * | 2019-12-26 | 2021-07-01 | 学校法人神奈川大学 | Crosslinked polymer compound and method for producing same, absorbent article, paper diaper, sanitary article, disposal container, and disposal method |
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