WO2012132902A1 - 吸水性樹脂の製造方法 - Google Patents
吸水性樹脂の製造方法 Download PDFInfo
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- WO2012132902A1 WO2012132902A1 PCT/JP2012/056554 JP2012056554W WO2012132902A1 WO 2012132902 A1 WO2012132902 A1 WO 2012132902A1 JP 2012056554 W JP2012056554 W JP 2012056554W WO 2012132902 A1 WO2012132902 A1 WO 2012132902A1
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- water
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- absorbent resin
- absorbent
- ethylenically unsaturated
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/45—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the shape
- A61F13/49—Absorbent articles specially adapted to be worn around the waist, e.g. diapers
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
- A61L15/24—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/42—Use of materials characterised by their function or physical properties
- A61L15/60—Liquid-swellable gel-forming materials, e.g. super-absorbents
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- 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
- C08F2/00—Processes of polymerisation
- C08F2/04—Polymerisation in solution
- C08F2/10—Aqueous solvent
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- 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
- C08F2/00—Processes of polymerisation
- C08F2/32—Polymerisation in water-in-oil emulsions
-
- 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
- C08F20/00—Homopolymers and 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
- C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
- C08F20/04—Acids, Metal salts or ammonium salts thereof
- C08F20/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
-
- 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
- C08F20/00—Homopolymers and 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
- C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
- C08F20/52—Amides or imides
- C08F20/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
- C08F20/56—Acrylamide; Methacrylamide
-
- 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
- C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
-
- 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
- C08F220/52—Amides or imides
- C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
- C08F220/56—Acrylamide; Methacrylamide
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- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/31504—Composite [nonstructural laminate]
- Y10T428/31855—Of addition polymer from unsaturated monomers
- Y10T428/31938—Polymer of monoethylenically unsaturated hydrocarbon
Definitions
- the present invention relates to a method for producing a water absorbent resin and a water absorbent resin obtained thereby. More specifically, in a method for producing a water-absorbent resin by reversed-phase suspension polymerization, a method for obtaining a water-absorbent resin having excellent liquid passing performance, a water-absorbent resin obtained by the method, and an absorber and an absorption using the water-absorbent resin. It relates to sex goods.
- water-absorbent resins have been widely used in various fields such as sanitary materials such as disposable diapers and sanitary products, agricultural and horticultural materials such as water retention agents and soil conditioners, and industrial materials such as water-stopping agents and anti-condensation agents. Yes. Among these fields, it is often used for sanitary materials such as disposable diapers and sanitary products.
- a water-absorbing resin include a hydrolyzate of starch-acrylonitrile graft copolymer, a neutralized product of starch-acrylic acid graft copolymer, a saponified product of vinyl acetate-acrylic acid ester copolymer, and an acrylic resin.
- Cross-linked products of acid partial neutralized polymers are known.
- Absorbent articles typified by paper diapers have an absorbent body that absorbs liquids such as body fluids, a flexible liquid-permeable surface sheet (top sheet) disposed on the side in contact with the body, and an opposite side in contact with the body. It has a structure sandwiched between a liquid-impermeable back sheet (back sheet) disposed.
- an absorber consists of a mixture of a water absorbing resin and a hydrophilic fiber.
- This “gel blocking phenomenon” means that when a dense absorbent body absorbs a liquid, the water absorbent resin existing near the surface layer absorbs the liquid, and the soft gel becomes denser near the surface layer. This is a phenomenon in which the penetration of liquid into the absorbent body is hindered, and the water absorbent resin inside cannot absorb the liquid efficiently, and this phenomenon occurs as the proportion of fine powder in the water absorbent resin increases. It tends to be easy. For this reason, there is a need for a water-absorbing resin that is unlikely to cause a gel blocking phenomenon and that has high liquid passing performance after absorbing and swelling liquid.
- Water-absorbing resins are mainly produced by reverse-phase suspension polymerization or aqueous solution polymerization of water-soluble ethylenically unsaturated monomers.
- the conventional reversed-phase suspension polymerization has a drawback that it is difficult to produce a water-absorbing resin having a large particle size, and it is difficult to obtain an appropriate particle size suitable for sanitary materials.
- Patent Document 3 After a water-absorbing resin is produced by polymerization, a specific surfactant of HLB7 or higher is added to a polymerization reaction liquid in which polymer particles are suspended, and then a monomer is added again to polymerize this. Then, a method for obtaining a large water-absorbing resin (see Patent Document 3), after the water-absorbing resin is produced by the polymerization of the first-stage monomer, the polymerization reaction liquid in which the polymer particles are suspended in the presence of inorganic powder, There has been proposed a method of obtaining a large water-absorbent resin by adding a monomer again and polymerizing it (see Patent Document 4).
- an object of the present invention is to provide a method for obtaining a water-absorbing resin excellent in liquid-permeating performance, a water-absorbing resin obtained by the method, and an absorbent body and an absorbent article using the water-absorbing resin.
- the gist of the present invention is as follows. [1] Using a water-soluble ethylenically unsaturated monomer to which an internal cross-linking agent is added, primary particles obtained by reverse-phase suspension polymerization in the first stage are subjected to reverse-phase suspension in the second stage.
- a method for producing a water-absorbent resin that is aggregated by polymerization wherein the amount of addition of the first-stage internal cross-linking agent is A mol with respect to 100 mol of the water-soluble ethylenically unsaturated monomer used in the first step, And when the addition amount of the internal crosslinking agent in the second stage is set to B moles with respect to 100 moles of the water-soluble ethylenically unsaturated monomer used in the second stage, A and B are A ⁇ 5.0.
- a method for producing a water-absorbent resin characterized by satisfying a relationship of ⁇ 10 ⁇ 3 and 2 ⁇ B / A ⁇ 10; [2] A water-absorbent resin obtained by the production method according to [1]; [3] An absorbent body comprising the water-absorbent resin according to [2] and a hydrophilic fiber; and [4] The absorbent body according to [3], between the liquid permeable sheet and the liquid impermeable sheet. An absorbent article in which is held.
- the production method according to the present invention can provide a water-absorbent resin excellent in liquid permeation performance, an absorbent body including the same, and an absorbent article.
- First-stage reversed-phase suspension polymerization The production method according to the present invention is carried out by two-stage reversed-phase suspension polymerization. Hereinafter, the first-stage reversed-phase suspension polymerization will be described.
- a water-soluble ethylenically unsaturated monomer in which an internal crosslinking agent is added in a petroleum hydrocarbon dispersion medium in the presence of a dispersion stabilizer is first used in the first stage using a radical polymerization initiator. Perform reverse phase suspension polymerization of the eye.
- water-soluble ethylenically unsaturated monomer to be used examples include (meth) acrylic acid and / or a salt thereof (in this specification, “acryl” and “methacryl” are collectively referred to as “(meth) acryl”).
- the water-soluble ethylenically unsaturated monomer can usually be used as an aqueous solution.
- concentration of the monomer in the aqueous monomer solution is preferably 20% by mass or more and a saturated concentration or less, more preferably 25 to 70% by mass, and further preferably 30 to 55% by mass.
- the acid group is removed by an alkaline neutralizing agent. It may be neutralized.
- alkaline neutralizer include aqueous solutions of sodium hydroxide, potassium hydroxide, and ammonia. These alkaline neutralizers may be used alone or in combination of two or more.
- the degree of neutralization of all acid groups of the water-soluble ethylenically unsaturated monomer by the alkaline neutralizer increases the water absorption capacity by increasing the osmotic pressure of the resulting water-absorbent resin, and the excess alkaline neutralizer
- the range of 10 to 100 mol% is preferable, and the range of 30 to 80 mol% is more preferable from the viewpoint of preventing the occurrence of problems in safety and the like due to the presence.
- Examples of petroleum hydrocarbon dispersion media include aliphatic hydrocarbons such as n-hexane, n-heptane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 3-ethylpentane, and n-octane.
- Cycloaliphatic hydrocarbons such as cyclohexane, methylcyclohexane, cyclopentane, methylcyclopentane, trans-1,2-dimethylcyclopentane, cis-1,3-dimethylcyclopentane, trans-1,3-dimethylcyclopentane;
- Aromatic hydrocarbons such as benzene, toluene, xylene and the like can be mentioned.
- These petroleum hydrocarbon dispersion media may be used alone or in combination of two or more.
- n-hexane, n-heptane, and cyclohexane are preferably used because they are easily available industrially, have stable quality, and are inexpensive.
- Exol heptane (ExxonMobil Corp .: containing 75 to 85% of heptane and isomer hydrocarbons) is preferably used as an example of the mixture of the above petroleum hydrocarbon dispersion medium. .
- the amount of the petroleum hydrocarbon dispersion medium used is usually the water solubility used in the first stage polymerization from the viewpoint of uniformly dispersing the water-soluble ethylenically unsaturated monomer and facilitating the control of the polymerization temperature.
- the amount is preferably 100 to 1200 parts by weight and more preferably 200 to 1000 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated monomer.
- a surfactant may be used.
- sucrose fatty acid ester polyglycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerin fatty acid ester, sorbitol fatty acid ester, polyoxy Ethylene sorbitol fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene polyoxypropylene block copolymer, poly Oxyethylene polyoxypropylene alkyl ether, polyethylene glycol fatty acid ester, alkyl glucosi , N- alkyl gluconamide, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amines, phosphoric esters of polyoxyethylene alkyl ethers
- surfactants sorbitan fatty acid ester, polyglycerin fatty acid ester and sucrose fatty acid ester are preferable from the viewpoint of dispersion stability of the monomer. These surfactants may be used alone or in combination of two or more.
- a polymeric dispersant may be used in combination with a surfactant.
- the polymer dispersant used include maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified ethylene / propylene copolymer, maleic anhydride-modified EPDM (ethylene / propylene / diene / terpolymer), Maleic anhydride-modified polybutadiene, maleic anhydride / ethylene copolymer, maleic anhydride / propylene copolymer, maleic anhydride / ethylene / propylene copolymer, maleic anhydride / butadiene copolymer, polyethylene, polypropylene, ethylene Examples include propylene copolymer, oxidized polyethylene, oxidized polypropylene, oxidized ethylene / propylene copolymer, ethylene / acrylic acid copolymer, eth
- polymeric dispersants from the viewpoint of dispersion stability of monomers, maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified ethylene / propylene copolymer, maleic anhydride / ethylene Copolymer, maleic anhydride / propylene copolymer, maleic anhydride / ethylene / propylene copolymer, polyethylene, polypropylene, ethylene / propylene copolymer, oxidized polyethylene, oxidized polypropylene and oxidized ethylene / propylene copolymer Coalescence is preferred.
- These polymer dispersants may be used alone or in combination of two or more.
- the amount of the dispersion stabilizer used is the water-solubility used in the first stage polymerization in order to maintain a good dispersion state of the monomer in the petroleum hydrocarbon dispersion medium and to obtain a dispersion effect commensurate with the amount used.
- the amount is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the ethylenically unsaturated monomer.
- radical polymerization initiator examples include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate; methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide , T-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxypivalate, and peroxides such as hydrogen peroxide; 2,2′-azobis (2-amidinopropane) dihydrochloride Salt, 2,2′-azobis [2- (N-phenylamidino) propane] dihydrochloride, 2,2′-azobis [2- (N-allylamidino) propane] dihydrochloride, 2,2′-azobis ⁇ 2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane ⁇ dihydrochloride
- radical polymerization initiators potassium persulfate, ammonium persulfate, sodium persulfate and 2,2'-azobis (2-amidinopropane) dihydrochloride are preferable from the viewpoint of easy availability and easy handling.
- These radical polymerization initiators may be used alone or in combination of two or more.
- the amount of the radical polymerization initiator used is usually preferably 0.005 to 1 mol with respect to 100 mol of the water-soluble ethylenically unsaturated monomer used for the first stage polymerization.
- the amount used is less than 0.005 mol, the polymerization reaction may take a long time.
- the amount used exceeds 1 mol, a rapid polymerization reaction may occur.
- the radical polymerization initiator can also be used as a redox polymerization initiator in combination with a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, and L-ascorbic acid.
- a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, and L-ascorbic acid.
- the reaction temperature of the polymerization reaction varies depending on the radical polymerization initiator used, but is usually preferably 20 to 110 ° C, more preferably 40 to 90 ° C.
- the reaction temperature is lower than 20 ° C., the polymerization rate is slow and the polymerization time becomes long, which is not economically preferable.
- the reaction temperature is higher than 110 ° C., it is difficult to remove the heat of polymerization, and thus it may be difficult to carry out the reaction smoothly.
- the reaction time is preferably 0.1 to 4 hours.
- the internal crosslinking agent added to the monomer for example, a compound having two or more polymerizable unsaturated groups is used.
- (poly) ethylene glycol in the present specification, for example, “polyethylene glycol” and “ethylene glycol” are collectively referred to as “(poly) ethylene glycol”.
- Unsaturated polyesters obtained
- a compound having two or more reactive functional groups can be used as the internal cross-linking agent.
- glycidyl group-containing compounds such as (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether; (poly) ethylene glycol, (poly) propylene glycol, (poly) Examples include glycerin, pentaerythritol, ethylenediamine, polyethyleneimine, and glycidyl (meth) acrylate.
- These internal cross-linking agents may be used alone or in combination of two or more.
- the amount A mole of the internal crosslinking agent added to the monomer (per 100 moles) used in the first-phase reversed-phase suspension polymerization is the first-stage polymerization.
- One feature is that it is 5.0 ⁇ 10 ⁇ 3 mol or less with respect to 100 mol of the water-soluble ethylenically unsaturated monomer used in the above, and preferably 4.8 ⁇ 10 ⁇ 3 mol or less. 7 ⁇ 10 ⁇ 3 mol or less is more preferable.
- the A mole is preferably in the range of 0.9 to 5.0 ⁇ 10 ⁇ 3 mole, more preferably in the range of 1.0 to 5.0 ⁇ 10 ⁇ 3 mole, and 1.4 to 4.8 ⁇ .
- the range of 10 ⁇ 3 mol is more preferable, and the range of 1.6 to 4.7 ⁇ 10 ⁇ 3 mol is even more preferable.
- the addition amount A mole of the first-stage internal cross-linking agent exceeds 5.0 ⁇ 10 ⁇ 3 mol, the primary particles of the polymer obtained by the first-stage reverse phase suspension polymerization are liquid-absorbed. Since the expansion at the time is hindered by the internal crosslinking, the monomer added during the second stage polymerization tends not to be sufficiently absorbed. As a result, the monomer that has not been absorbed becomes a fine water-absorbing resin that causes a gel blocking phenomenon by the second-phase reverse phase suspension polymerization, and the liquid passing performance is lowered.
- a chain transfer agent may be added in order to control the water absorption performance of the water absorbent resin.
- chain transfer agents include hypophosphites, thiols, thiolic acids, secondary alcohols, amines and the like.
- Second Step Reverse Phase Suspension Polymerization Next, the second step reverse phase suspension polymerization will be described.
- the monomer is added and the monomer is polymerized. Thereby, the primary particles dispersed in the slurry are aggregated.
- the slurry obtained in the first-stage reversed-phase suspension polymerization is cooled and contained in the slurry before the monomer polymerization reaction.
- a step of precipitating the dispersion stabilizer may be included.
- the cooling temperature is not particularly limited, and is usually about 10 to 50 ° C.
- the precipitation of the dispersion stabilizer may be confirmed by the white turbidity in the slurry. For example, it may be confirmed by visual observation or a technique such as a turbidimeter.
- the kind of water-soluble ethylenically unsaturated monomer used in the second stage, the degree of neutralization, the neutralization salt, and the monomer aqueous solution concentration are as follows. It is preferable to employ the types, numerical ranges, etc. described in the description. In this case, the water-soluble ethylenically unsaturated monomer used for the first stage polymerization can be read as the water-soluble ethylenically unsaturated monomer used for the second stage polymerization. At this time, the type and value of the first stage may be the same or different.
- the addition amount of the water-soluble ethylenically unsaturated monomer in the second stage is 100 parts by mass of the water-soluble ethylenically unsaturated monomer in the first stage from the viewpoint of obtaining a water-absorbing resin excellent in liquid passing performance.
- the amount is preferably 80 to 200 parts by mass, and more preferably 100 to 160 parts by mass.
- the radical polymerization initiator added to the water-soluble ethylenically unsaturated monomer in the second stage and the amount used thereof are also exemplified as the radical polymerization initiator used in the first stage polymerization and the amount used. Can be appropriately selected and used.
- the radical polymerization initiator used for the first stage polymerization can be read as the radical polymerization initiator used for the second stage polymerization.
- the type and value of the first stage may be the same or different.
- the reaction temperature in the second-phase reversed-phase suspension polymerization is also preferably 20 to 110 ° C., more preferably 40 to 90 ° C., although it varies depending on the radical polymerization initiator used.
- the internal cross-linking agent added to the water-soluble ethylenically unsaturated monomer at the second stage can be selected from those exemplified in the polymerization at the first stage.
- the internal cross-linking agent used for the first stage polymerization can be read as the internal cross-linking agent used for the second stage polymerization. At this time, it may be the same as or different from the first stage type.
- a chain transfer agent may be added.
- the amount B mole of the second-stage internal cross-linking agent added to the monomer (per 100 moles) used in the second stage is 2 ⁇
- One characteristic is that the relationship of B / A ⁇ 10 is satisfied.
- the range of B / A is preferably 3 ⁇ B / A ⁇ 9, and more preferably 3 ⁇ B / A ⁇ 8.
- the water-absorbent resin obtained by reverse phase suspension polymerization according to the present invention is obtained by agglomeration of primary particles.
- B / A between the amount B mol of the second-stage internal cross-linking agent and the amount A mol of the first-stage internal cross-linking agent is less than 2
- the force to prevent the particles from expanding is weak and the particles expand when absorbing water.
- the gaps between the particles are easily blocked, and the liquid passing performance tends to decrease.
- B / A exceeds 10
- the cohesive force is too strong, so that the gap between the particles becomes smaller due to the bonding of the particles, and the gap is easily blocked by the expansion of the particles upon water absorption, resulting in a decrease in the liquid passing performance.
- a post-crosslinking treatment by adding a post-crosslinking agent between the second stage polymerization of the water-soluble ethylenically unsaturated monomer and the drying.
- a water-absorbing resin suitable for hygiene material use with increased performance such as water absorption capacity under load, water absorption speed, gel strength, and the like can be obtained.
- Examples of such a post-crosslinking agent include compounds having two or more reactive functional groups. Examples thereof include diglycidyl group-containing compounds such as (poly) ethylene glycol diglycidyl ether, (poly) glycerol (poly) glycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether; ) Ethylene glycol, (poly) propylene glycol, (poly) glycerin, pentaerythritol, ethylenediamine, and polyethyleneimine.
- diglycidyl group-containing compounds such as (poly) ethylene glycol diglycidyl ether, (poly) glycerol (poly) glycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether; ) Ethylene glycol,
- post-crosslinking agents (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether are preferable. These post-crosslinking agents may be used alone or in combination of two or more.
- the amount of the post-crosslinking agent added is the water-soluble ethylenic property used for the polymerization from the viewpoint of enhancing various performances without increasing the water-absorbing ability of the obtained water-absorbing resin and increasing the cross-linking density near the surface of the water-absorbent resin. It is preferably in the range of 0.005 to 1 mol, more preferably in the range of 0.01 to 0.5 mol, based on 100 mol of the unsaturated monomers.
- the post-crosslinking agent may be added after completion of the polymerization, and is not particularly limited, but is 1 to 400 with respect to 100 parts by mass of the total amount of the water-soluble ethylenically unsaturated monomer used to obtain the water-absorbent resin. It is preferably added in the presence of moisture in the range of parts by mass, more preferably in the presence of moisture in the range of 5 to 200 parts by mass, and added in the presence of moisture in the range of 10 to 100 parts by mass. More preferably.
- crosslinking in the vicinity of the surface of the water-absorbent resin can be more suitably performed, and as a result, excellent water absorption performance can be achieved.
- the post-crosslinking agent When the post-crosslinking agent is added, the post-crosslinking agent may be added as it is or as an aqueous solution, but a hydrophilic organic solvent may be used as a solvent if necessary.
- the hydrophilic organic solvent include lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol; ketones such as acetone and methyl ethyl ketone; ethers such as diethyl ether, dioxane, and tetrahydrofuran; Examples thereof include amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide. These hydrophilic organic solvents may be used alone or in combination of two or more or as a mixed solvent with water.
- the temperature in the post-crosslinking reaction is preferably 50 to 250 ° C, more preferably 60 to 180 ° C, still more preferably 60 to 140 ° C, and still more preferably 70 to 120 ° C.
- the drying step may be performed under normal pressure or under reduced pressure, and may be performed under an air stream such as nitrogen in order to increase the drying efficiency.
- the drying temperature is preferably 70 to 250 ° C, more preferably 80 to 180 ° C, further preferably 80 to 140 ° C, and still more preferably 90 to 130 ° C.
- the drying temperature is preferably 60 to 100 ° C, more preferably 70 to 90 ° C.
- water-absorbent resin according to the present invention obtained in this way is excellent in liquid passing performance, it is suitably used for absorbent bodies and absorbent articles using the same.
- Water-absorbing resin The water content of the water-absorbing resin is preferably 20% by mass or less, and more preferably 10% by mass or less from the viewpoint of providing fluidity. Moreover, in order to improve fluidity
- the physiological saline water retention ability of the water-absorbent resin is preferably 32 g / g or less, and preferably 27 to 31 g / g from the viewpoint of obtaining a water-absorbent resin that has excellent liquid-passing performance after absorbing and swelling a liquid and has a high absorption capacity. Is more preferable.
- the physiological saline water retention capacity of the water-absorbent resin is a value obtained by the measurement method described in Examples described later.
- the liquid-permeable performance of the water-absorbent resin is represented by the liquid-flow rate of a 0.69 mass% sodium chloride aqueous solution.
- the flow rate of the 0.69% by mass sodium chloride aqueous solution of the water absorbent resin is 100 [g / 10 minutes] or more from the viewpoint of enhancing the performance such as penetration time and liquid diffusibility in the absorbent body using the water absorbent resin. It is preferable that it is 120 [g / 10 min] or more.
- the liquid passing rate of the 0.69 mass% sodium chloride aqueous solution of the water absorbent resin is a value obtained by the measuring method described in the examples described later.
- the median particle diameter of the water absorbent resin is preferably 200 to 600 ⁇ m, more preferably 250 to 500 ⁇ m, and even more preferably 300 to 450 ⁇ m.
- Such a water-absorbent resin having a median particle diameter is suitable for an absorbent body and an absorbent article using the same.
- the median particle diameter of the water-absorbent resin is a value obtained by the measurement method described in Examples described later.
- the absorbent body using the water absorbent resin according to the present invention is composed of a water absorbent resin and hydrophilic fibers.
- a water absorbent resin and hydrophilic fibers As the structure of the absorbent body, for example, a mixed dispersion obtained by mixing the water absorbent resin and the hydrophilic fiber so as to have a uniform composition, the water absorbent resin is sandwiched between the layered hydrophilic fibers. Examples include a sandwich structure, a structure in which a water-absorbing resin and hydrophilic fibers are wrapped with a tissue, and the like, but the present invention is not limited to such examples.
- the absorbent body may be added with other components, for example, an adhesive binder such as a heat-fusible synthetic fiber, a hot melt adhesive, and an adhesive emulsion for improving the shape retention of the absorbent body.
- an adhesive binder such as a heat-fusible synthetic fiber, a hot melt adhesive, and an adhesive emulsion for improving the shape retention of the absorbent body.
- hydrophilic fibers examples include cellulose fibers such as cotton-like pulp, mechanical pulp, chemical pulp, and semi-chemical pulp obtained from wood; artificial cellulose fibers such as rayon and acetate; And fibers made of a synthetic resin.
- the absorbent article using the water absorbent resin according to the present invention has a structure in which the absorber is held between a liquid permeable sheet and a liquid impermeable sheet.
- liquid permeable sheet examples include air-through type, spun bond type, chemical bond type, needle punch type nonwoven fabrics made of fibers such as polyethylene, polypropylene, and polyester.
- liquid impermeable sheet examples include synthetic resin films made of resins such as polyethylene, polypropylene, and polyvinyl chloride.
- the type of absorbent article is not particularly limited. Typical examples include sanitary materials such as paper diapers, sanitary napkins, incontinence pads, urine absorbing materials for pets, civil engineering and building materials such as packing materials, drip absorbents, cold preservation agents, etc. Agricultural and horticultural articles such as materials for use and soil water retention materials.
- the water-absorbing resin obtained in each Example and Comparative Example was evaluated for the water content, physiological saline water retention capacity, median particle diameter, and the flow rate of 0.69 mass% sodium chloride aqueous solution by the methods shown below. .
- ⁇ Saline retention capacity> In a 500 mL beaker, 500 g of 0.9 mass% sodium chloride aqueous solution (physiological saline) was weighed, and while stirring at 600 r / min, 2.0 g of the water-absorbing resin was dispersed so as not to generate mako. The mixture was allowed to stand for 30 minutes in a stirred state to sufficiently swell the water absorbent resin. Then, it was poured into a cotton bag (Membroad No. 60, width 100 mm x length 200 mm), the upper part of the cotton bag was tied with a rubber band, and a centrifugal force was set to 167 G.
- a cotton bag Membroad No. 60, width 100 mm x length 200 mm
- amorphous silica (Degussa Japan Co., Ltd., Sipernat 200) was mixed as a lubricant to obtain a water-absorbing resin for measurement.
- the mass of the water-absorbent resin remaining on each sieve is calculated as a percentage by mass with respect to the total amount, and the mass of the water-absorbent resin remaining on the sieve opening and the sieve is calculated by integrating in order from the larger particle size.
- the relationship between percentage and integrated value was plotted on a logarithmic probability paper. By connecting the plots on the probability paper with a straight line, the particle diameter corresponding to an integrated mass percentage of 50 mass% was defined as the median particle diameter.
- FIG. 1 Installation of measuring apparatus
- the measuring apparatus having the schematic configuration shown in FIG. 1 was used.
- the tank 11 is provided with a glass tube 12 for adjusting static pressure, and the lower end of the glass tube 12 is swollen by the height of the liquid surface in the cylinder 22 of the 0.69 mass% sodium chloride aqueous solution 13. It arrange
- the 0.69 mass% sodium chloride aqueous solution 13 in the tank 11 was supplied into the cylinder 22 through the L-shaped tube 14 with a cock.
- a container 33 that collects the liquid that has passed is disposed under the cylinder 22, and the collection container 33 is disposed on an upper pan balance 34.
- the inner diameter of the cylinder 22 is 6 cm.
- a 400 stainless steel wire mesh (aperture 38 ⁇ m) 26 was installed.
- the 0.69 mass% sodium chloride aqueous solution 13 is maintained at a height of 5 cm above the bottom of the swollen gel 25 in the cylinder 22 of the aqueous solution 13 under a load of 2.07 kPa. It was supplied from the tank 11 to the swollen gel 25 at a constant hydrostatic pressure.
- the mass of the aqueous solution 13 that passed through the swollen gel 25 and entered the collection container 33 was measured and taken as the liquid passing speed ([g / 10 minutes]). This measurement was performed at room temperature (20 to 25 ° C.).
- Example 1 A 2 L round bottom cylindrical separable flask equipped with a stirrer, a two-stage paddle blade, a reflux condenser, a dropping funnel and a nitrogen gas introduction tube was prepared. 340 g of n-heptane was taken into this flask, 0.92 g of sucrose stearate (Mitsubishi Chemical Foods, Ltd., Ryoto Sugar Ester S-370) and maleic anhydride modified ethylene / propylene copolymer ( 0.92 g of Mitsui Chemical Co., Ltd., High Wax 1105A) was added, the temperature was raised to 80 ° C. with stirring, the surfactant was dissolved, and then cooled to 50 ° C.
- sucrose stearate Mitsubishi Chemical Foods, Ltd., Ryoto Sugar Ester S-370
- maleic anhydride modified ethylene / propylene copolymer 0.92 g of Mitsui Chemical Co., Ltd., High Wax 1105A
- the flask After adding the entire amount of the first stage monomer aqueous solution to the separable flask and sufficiently replacing the inside with nitrogen, the flask was immersed in a 70 ° C. water bath and heated. The first stage polymerization was carried out for 30 minutes to obtain a reaction mixture for the first stage polymerization.
- the first-stage reaction mixture was cooled to 22 ° C., and the second-stage monomer aqueous solution at the same temperature was added to the system and absorbed for 30 minutes. At the same time, the system was sufficiently replaced with nitrogen. Thereafter, the flask was again immersed in a 70 ° C. water bath and the temperature was raised, and the second stage polymerization was carried out for 30 minutes.
- Example 2 In Example 1, the addition amount of the internal crosslinking agent in the first stage was 2.8 mg (0.16 ⁇ 10 ⁇ 1 mmol, 1.6 ⁇ 10 ⁇ 3 with respect to 100 mol of the first stage monomer). Mol), and the addition amount of the second stage was changed to 0.03 g (1.72 ⁇ 10 ⁇ 1 mmol, 12.0 ⁇ 10 ⁇ 3 mol with respect to 100 mol of the second stage monomer). Performed the same operation as Example 1, and obtained 230.1 g of water-absorbing resin (B). The median particle diameter of the water absorbent resin was 370 ⁇ m, and the water content was 7.6%. Table 1 shows the measurement results of each performance.
- Example 3 In Example 1, the internal cross-linking agent was N, N′-methylenebisacrylamide, and the addition amount of the first stage was 4.6 mg (0.30 ⁇ 10 ⁇ 1 mmol, the first stage of monomer 100 mol). 2.9 ⁇ 10 ⁇ 3 mol with respect to the second stage), and 0.03 g (1.95 ⁇ 10 ⁇ 1 mmol of the second stage addition, 13.6 with respect to 100 mol of the second stage monomer). Except for changing to x10 -3 mol), the same operation as in Example 1 was carried out to obtain 229.5 g of a water absorbent resin (C). The median particle size of the water-absorbent resin was 350 ⁇ m, and the moisture content was 7.5%. Table 1 shows the measurement results of each performance.
- C water absorbent resin
- Example 4 In Example 2, the amount of the internal crosslinking agent added in the first stage was 8.3 mg (0.48 ⁇ 10 ⁇ 1 mmol, 4.7 ⁇ 10 ⁇ 3 per 100 moles of the first stage monomer). Except for changing to mol), the same operation as in Example 2 was performed to obtain 227.9 g of a water absorbent resin (D). The median particle diameter of the water absorbent resin was 330 ⁇ m, and the water content was 7.3%. Table 1 shows the measurement results of each performance.
- Example 5 In Example 4, the added amount of the internal crosslinking agent in the second stage was 0.07 g (4.02 ⁇ 10 ⁇ 1 mmol, 28.1 ⁇ 10 ⁇ 3 with respect to 100 mol of the second stage monomer). Except for the change to (mol), the same operation as in Example 4 was performed to obtain 229.9 g of a water absorbent resin (E). The median particle diameter of the water absorbent resin was 320 ⁇ m, and the moisture content was 7.5%. Table 1 shows the measurement results of each performance.
- Example 5 the addition amount of the first stage of the internal crosslinking agent was 0.01 g (0.57 ⁇ 10 ⁇ 1 mmol, 5.6 ⁇ 10 ⁇ 3 to 100 mol of the first stage monomer). Except for changing to (mol), the same operation as in Example 5 was performed to obtain 230.4 g of a water absorbent resin (F). The median particle diameter of the water absorbent resin was 280 ⁇ m, and the moisture content was 7.7%. Table 1 shows the measurement results of each performance.
- Example 2 the addition amount of the second stage of the internal crosslinking agent was 4.0 mg (0.23 ⁇ 10 ⁇ 1 mmol, 1.6 ⁇ 10 ⁇ 3 with respect to 100 mol of the second stage monomer). Except for changing to (mol), the same operation as in Example 2 was performed to obtain 225.8 g of a water absorbent resin (G). The median particle size of the water-absorbent resin was 380 ⁇ m, and the moisture content was 7.0%. Table 1 shows the measurement results of each performance.
- Example 4 the amount of addition of the internal crosslinking agent in the second stage was 0.01 g (0.57 ⁇ 10 ⁇ 1 mmol, 4.0 ⁇ 10 ⁇ 3 with respect to 100 mol of the second stage monomer). Except for the change to (mol), the same operation as in Example 4 was performed to obtain 227.4 g of a water absorbent resin (H). The median particle diameter of the water-absorbent resin was 310 ⁇ m, and the water content was 7.2%. Table 1 shows the measurement results of each performance.
- Example 2 the addition amount of the internal crosslinking agent in the second stage was 0.05 g (2.87 ⁇ 10 ⁇ 1 mmol, 20.1 ⁇ 10 ⁇ 3 with respect to 100 mol of the second stage monomer). Except for the change to (mol), the same operation as in Example 2 was performed to obtain 229.1 g of a water absorbent resin (I). The median particle diameter of the water absorbent resin was 370 ⁇ m, and the water content was 7.6%. Table 1 shows the measurement results of each performance.
- Example 5 the addition amount of the second stage of the internal crosslinking agent was 0.13 g (7.46 ⁇ 10 ⁇ 1 mmol, 52.2 ⁇ 10 ⁇ 3 with respect to 100 mol of the second stage monomer). Except for changing to (mol), the same operation as in Example 4 was performed to obtain 228.5 g of a water absorbent resin (J). The median particle size of the water-absorbent resin was 310 ⁇ m, and the moisture content was 7.5%. Table 1 shows the measurement results of each performance.
- absorbent bodies and absorbent articles were prepared using the water absorbent resins obtained in Examples 1 to 5 and Comparative Examples 1 to 5.
- Example 6 10 g of the water-absorbent resin (A) obtained in Example 1 and 10 g of pulverized pulp were dry-mixed using a mixer and sprayed onto a tissue having a size of 40 cm ⁇ 12 cm and a weight of 1 g, and then the same size. And the tissue of the weight was piled up from the upper part, it was made into a sheet form, the load of 196 kPa was applied to the whole for 30 seconds, and the absorber was obtained.
- the obtained absorbent body is sandwiched between a polyethylene air-through porous liquid-permeable sheet having a size of 40 cm ⁇ 12 cm and a basis weight of 20 g / m 2 and a polyethylene liquid-impermeable sheet having the same size and the same basis weight.
- a polyethylene air-through porous liquid-permeable sheet having a size of 40 cm ⁇ 12 cm and a basis weight of 20 g / m 2
- a polyethylene liquid-impermeable sheet having the same size and the same basis weight.
- Example 7 In Example 6, an absorbent body and an absorbent article using the same were obtained in the same manner as in Example 6 except that the water absorbent resin (B) obtained in Example 2 was used.
- Example 8 In Example 6, an absorbent body and an absorbent article using the same were obtained in the same manner as in Example 6 except that the water absorbent resin (C) obtained in Example 3 was used.
- Example 9 In Example 6, an absorbent body and an absorbent article using the same were obtained in the same manner as in Example 6 except that the water absorbent resin (D) obtained in Example 4 was used.
- Example 10 In Example 6, an absorbent body and an absorbent article using the same were obtained in the same manner as in Example 6 except that the water absorbent resin (E) obtained in Example 5 was used.
- Example 6 In Example 6, an absorbent body and an absorbent article using the same were obtained in the same manner as in Example 6 except that the water absorbent resin (F) obtained in Comparative Example 1 was used.
- Example 6 In Example 6, an absorbent body and an absorbent article using the same were obtained in the same manner as in Example 6 except that the water absorbent resin (G) obtained in Comparative Example 2 was used.
- Example 6 In Example 6, an absorbent body and an absorbent article using the same were obtained in the same manner as in Example 6 except that the water absorbent resin (H) obtained in Comparative Example 3 was used.
- Example 6 an absorbent body and an absorbent article using the same were obtained in the same manner as in Example 6 except that the water absorbent resin (I) obtained in Comparative Example 4 was used.
- Example 6 In Example 6, an absorbent body and an absorbent article using the same were obtained in the same manner as in Example 6 except that the water absorbent resin (J) obtained in Comparative Example 5 was used.
- the obtained absorbent article was evaluated according to the following method. The results are shown in Table 2.
- (B) Penetration time The absorbent article was placed on a horizontal table. A cylindrical cylinder with an inner diameter of 3 cm is placed near the center of the absorbent article, and 50 mL of the test solution is poured into the cylinder all at once, and the test solution is completely disappeared from the cylinder using a stopwatch. The time was measured and used as the first penetration time (seconds). Next, remove the cylinder, store the absorbent article as it is, and place the cylindrical cylinder in the same position as the first time 30 minutes and 60 minutes after the start of the first test liquid charging. The second and third permeation times (seconds) were measured. The total number of seconds from the first to the third time was taken as the total penetration time. It can be said that the shorter the total permeation time, the better the absorbent article. For example, the total penetration time is preferably 70 seconds or less, and more preferably 65 seconds or less.
- (C) Reversal amount 10 cm square filter paper whose mass (We (g), about 70 g) has been measured in advance near the test solution charging position on the absorbent article after 60 minutes have elapsed from the end of the permeation time measurement. (About 80 sheets) was placed, and a 5 kg weight having a bottom surface of 10 cm ⁇ 10 cm was placed thereon. After loading for 5 minutes, the mass of the filter paper (Wf (g)) was measured, and the increased mass was taken as the reversal amount (g). It can be said that the smaller the amount of reversion, the better the absorbent article.
- the water-absorbent articles of Examples 6 to 10 using the water-absorbing resins (A) to (E) excellent in the liquid flow rate have a short permeation time and a low reversal. Recognize.
- the amount of the internal crosslinking agent in the first stage is large and the performance of the liquid passing speed is inferior (Comparative Example 6)
- the ratio of the internal crosslinking agent in the second stage is small, and the liquid passing speed is low.
- Both the inferior performance (Comparative Examples 7 and 8) and the ratio of the second-stage internal cross-linking agent are large, and the liquid passing speed performance is inferior (Comparative Examples 9 and 10). Performance such as time and diffusion length was inferior.
- those with low physiological saline retention capacity (Comparative Examples 6 and 10) tended to increase the amount of reversion.
- the water-absorbent resin obtained by the production method according to the present invention is excellent in liquid passing performance, it can be suitably used particularly for sanitary materials such as sanitary goods and paper diapers that have been made thinner.
Abstract
Description
〔1〕 内部架橋剤が添加された水溶性エチレン性不飽和単量体を使用し、第1段目の逆相懸濁重合によって得られた1次粒子を第2段目の逆相懸濁重合によって凝集させる吸水性樹脂の製造方法であって、第1段目の内部架橋剤の添加量を第1段目に用いられる水溶性エチレン性不飽和単量体100モルに対してAモル、及び第2段目の内部架橋剤の添加量を第2段目に用いられる水溶性エチレン性不飽和単量体100モルに対してBモルとした場合、A及びBが、A≦5.0×10-3、かつ2≦B/A≦10の関係を満たすことを特徴とする、吸水性樹脂の製造方法;
〔2〕 前記〔1〕に記載の製造方法によって得られる吸水性樹脂;
〔3〕 前記〔2〕に記載の吸水性樹脂と親水性繊維とからなる吸収体;並びに
〔4〕 液体透過性シートと液体不透過性シートの間に、前記〔3〕に記載の吸収体が保持されてなる吸収性物品;に関するものである。
本発明にかかる製造方法は、2段階の逆相懸濁重合によって実施される。以下に第1段目の逆相懸濁重合について説明する。
次に、第2段目の逆相懸濁重合について説明する。第2段目の逆相懸濁重合では、第1段目の逆相懸濁重合にて得られる1次粒子が分散するスラリーに、内部架橋剤が添加された水溶性エチレン性不飽和単量体を加えて単量体を重合反応させる。これによって、該スラリー中に分散する1次粒子を凝集させる。
吸水性樹脂の水分率は、流動性を持たせる観点から20質量%以下であることが好ましく、10質量%以下であることがより好ましい。また、流動性を向上させるために、吸水性樹脂に非晶質シリカ粉末を添加してもよい。
本発明にかかる吸水性樹脂を用いた吸収体は、吸水性樹脂と親水性繊維より構成されている。吸収体の構成としては、例えば、吸水性樹脂と親水性繊維を均一な組成となるように混合することによって得られた混合分散体、層状の親水性繊維の間に吸水性樹脂が挟まれたサンドイッチ構造体、吸水性樹脂と親水性繊維とをティッシュで包んだ構造体等が挙げられるが、本発明はかかる例示に限定されるものではない。
吸水性樹脂約2gを、あらかじめ秤量したアルミホイールケース(8号)に精秤した(Wa(g))。上記サンプルを、内温を105℃に設定した熱風乾燥機(ADVANTEC社製)で2時間乾燥させた後、デシケーター中で放冷して、乾燥後の吸水性樹脂の質量Wb(g)を測定した。以下の式から、吸水性樹脂の水分率を算出した。
水分率(%)=[Wa-Wb]/Wa×100
500mL容のビーカーに、0.9質量%塩化ナトリウム水溶液(生理食塩水)500gを量り取り、600r/minで撹拌させながら、吸水性樹脂2.0gを、ママコが発生しないように分散させた。撹拌させた状態で30分間放置し、吸水性樹脂を十分に膨潤させた。その後、綿袋(メンブロード60番、横100mm×縦200mm)中に注ぎ込み、綿袋の上部を輪ゴムで縛り、遠心力が167Gとなるよう設定した脱水機(国産遠心機株式会社製、品番:H-122)を用いて綿袋を1分間脱水し、脱水後の膨潤ゲルを含んだ綿袋の質量Wc(g)を測定した。吸水性樹脂を添加せずに同様の操作を行ない、綿袋の湿潤時の空質量Wd(g)を測定し、以下の式から保水能を算出した。
生理食塩水保水能(g/g)=[Wc-Wd](g)/吸水性樹脂の質量(g)
吸水性樹脂50gに、滑剤として、0.25gの非晶質シリカ(デグサジャパン(株)、Sipernat200)を混合し、測定用の吸水性樹脂とした。
(a)合成尿の調製
1L容の容器に、塩化カリウム2g、無水硫酸ナトリウム2g、塩化カルシウム0.19g、塩化マグネシウム0.23g、リン酸二水素アンモニウム0.85g、リン酸一水素アンモニウム0.15g及び適量の蒸留水を入れ、完全に溶解した。更に蒸留水を追加して、水溶液全体の体積を1Lに調整した。
測定装置として、図1に概略構成を示したものを用いた。装置としては、タンク11には、静圧調整用ガラス管12が具備されており、ガラス管12の下端は、0.69質量%塩化ナトリウム水溶液13のシリンダー22内の液面の高さが膨潤ゲル25の底部から、5cm上の高さに維持できるように配置した。タンク11中の0.69質量%塩化ナトリウム水溶液13は、コック付L字管14を通じてシリンダー22内へ供給された。シリンダー22の下には、通過した液を捕集する容器33が配置されており、捕集容器33は上皿天秤34の上に配置されていた。シリンダー22の内径は6cmであり、下部の底面にはNo.400ステンレス製金網(目開き38μm)26が設置されていた。ピストン型重り21の下部には液が通過するのに十分な穴23があり、底部には吸水性樹脂あるいはそれらの膨潤ゲルが、穴23へ入り込まないように透過性の良いガラスフィルター24が取り付けてあった。
円筒状容器20に0.9gの吸水性樹脂を均一に入れ、吸水性樹脂を合成尿中で、ピストン型重り21を用いて2.07kPaの荷重下で60分間膨潤させ、膨潤ゲル25を形成した。
攪拌機、2段パドル翼、還流冷却器、滴下ロート及び窒素ガス導入管を備えた2L容の丸底円筒型セパラブルフラスコを準備した。このフラスコにn-ヘプタン340gをとり、分散安定剤としてショ糖ステアリン酸エステル(三菱化学フーズ(株)、リョートーシュガーエステルS-370)0.92g及び無水マレイン酸変性エチレン・プロピレン共重合体(三井化学(株)、ハイワックス1105A)0.92gを添加し、撹拌しつつ80℃まで昇温して界面活性剤を溶解した後、50℃まで冷却した。
実施例1において、内部架橋剤の第1段目の添加量を2.8mg(0.16×10-1ミリモル、第1段目の単量体100モルに対して1.6×10-3モル)、第2段目の添加量を0.03g(1.72×10-1ミリモル、第2段目の単量体100モルに対して12.0×10-3モル)に変更した以外は、実施例1と同様の操作を行い、吸水性樹脂(B)230.1gを得た。吸水性樹脂の中位粒子径は370μm、水分率は7.6%であった。各性能の測定結果を表1に示す。
実施例1において、内部架橋剤をN,N’-メチレンビスアクリルアミドに、第1段目の添加量を4.6mg(0.30×10-1ミリモル、第1段目の単量体100モルに対して2.9×10-3モル)、第2段目の添加量を0.03g(1.95×10-1ミリモル、第2段目の単量体100モルに対して13.6×10-3モル)に変更した以外は、実施例1と同様の操作を行い、吸水性樹脂(C)229.5gを得た。吸水性樹脂の中位粒子径は350μm、水分率は7.5%であった。各性能の測定結果を表1に示す。
実施例2において、内部架橋剤の第1段目の添加量を8.3mg(0.48×10-1ミリモル、第1段目の単量体100モルに対して4.7×10-3モル)に変更した以外は、実施例2と同様の操作を行い、吸水性樹脂(D)227.9gを得た。吸水性樹脂の中位粒子径は330μm、水分率は7.3%であった。各性能の測定結果を表1に示す。
実施例4において、内部架橋剤の第2段目の添加量を0.07g(4.02×10-1ミリモル、第2段目の単量体100モルに対して28.1×10-3モル)に変更した以外は、実施例4と同様の操作を行い、吸水性樹脂(E)229.9gを得た。吸水性樹脂の中位粒子径は320μm、水分率は7.5%であった。各性能の測定結果を表1に示す。
実施例5において、内部架橋剤の第1段目の添加量を0.01g(0.57×10-1ミリモル、第1段目の単量体100モルに対して5.6×10-3モル)に変更した以外は、実施例5と同様の操作を行い、吸水性樹脂(F)230.4gを得た。吸水性樹脂の中位粒子径は280μm、水分率は7.7%であった。各性能の測定結果を表1に示す。
実施例2において、内部架橋剤の第2段目の添加量を4.0mg(0.23×10-1ミリモル、第2段目の単量体100モルに対して1.6×10-3モル)に変更した以外は、実施例2と同様の操作を行い、吸水性樹脂(G)225.8gを得た。吸水性樹脂の中位粒子径は380μm、水分率は7.0%であった。各性能の測定結果を表1に示す。
実施例4において、内部架橋剤の第2段目の添加量を0.01g(0.57×10-1ミリモル、第2段目の単量体100モルに対して4.0×10-3モル)に変更した以外は、実施例4と同様の操作を行い、吸水性樹脂(H)227.4gを得た。吸水性樹脂の中位粒子径は310μm、水分率は7.2%であった。各性能の測定結果を表1に示す。
実施例2において、内部架橋剤の第2段目の添加量を0.05g(2.87×10-1ミリモル、第2段目の単量体100モルに対して20.1×10-3モル)に変更した以外は、実施例2と同様の操作を行い、吸水性樹脂(I)229.1gを得た。吸水性樹脂の中位粒子径は370μm、水分率は7.6%であった。各性能の測定結果を表1に示す。
実施例4において、内部架橋剤の第2段目の添加量を0.13g(7.46×10-1ミリモル、第2段目の単量体100モルに対して52.2×10-3モル)に変更した以外は、実施例4と同様の操作を行い、吸水性樹脂(J)228.5gを得た。吸水性樹脂の中位粒子径は310μm、水分率は7.5%であった。各性能の測定結果を表1に示す。
実施例1で得られた吸水性樹脂(A)10gと粉砕パルプ10gをミキサーを用いて乾式混合したものを、大きさが40cm×12cmで重さが1gのティッシュに吹き付けた後に、同じ大きさ及び重さのティッシュを上部から重ねてシート状にし、これの全体に196kPaの荷重を30秒間加えてプレスすることにより、吸収体を得た。得られた吸収体を大きさ40cm×12cm、坪量20g/m2のポリエチレン製エアスルー型多孔質液体透過性シートと、同じ大きさ、同じ坪量のポリエチレン製液体不透過性シートで挟みつけることにより吸収体を用いた吸収性物品を得た。
実施例6において、実施例2で得られた吸水性樹脂(B)を用いた以外は、実施例6と同様にして、吸収体及びそれを用いた吸収性物品を得た。
実施例6において、実施例3で得られた吸水性樹脂(C)を用いた以外は、実施例6と同様にして、吸収体及びそれを用いた吸収性物品を得た。
実施例6において、実施例4で得られた吸水性樹脂(D)を用いた以外は、実施例6と同様にして、吸収体及びそれを用いた吸収性物品を得た。
実施例6において、実施例5で得られた吸水性樹脂(E)を用いた以外は、実施例6と同様にして、吸収体及びそれを用いた吸収性物品を得た。
実施例6において、比較例1で得られた吸水性樹脂(F)を用いた以外は、実施例6と同様にして、吸収体及びそれを用いた吸収性物品を得た。
実施例6において、比較例2で得られた吸水性樹脂(G)を用いた以外は、実施例6と同様にして、吸収体及びそれを用いた吸収性物品を得た。
実施例6において、比較例3で得られた吸水性樹脂(H)を用いた以外は、実施例6と同様にして、吸収体及びそれを用いた吸収性物品を得た。
実施例6において、比較例4で得られた吸水性樹脂(I)を用いた以外は、実施例6と同様にして、吸収体及びそれを用いた吸収性物品を得た。
実施例6において、比較例5で得られた吸水性樹脂(J)を用いた以外は、実施例6と同様にして、吸収体及びそれを用いた吸収性物品を得た。
(a)試験液の調製
5L容の容器に、塩化ナトリウム30g、塩化カルシウム二水和物0.9g、塩化マグネシウム六水和物1.8g及び適量の蒸留水を入れ、完全に溶解させた。次に、1質量%ポリ(オキシエチレン)イソオクチルフェニルエーテル水溶液7.5gを添加し、さらに蒸留水を添加して、水溶液全体の質量を3000gに調整した後、少量の青色1号で着色して、試験液を調製した。
水平の台上に吸収性物品を置いた。吸収性物品の中心付近に、内径3cmの円筒型シリンダーを置き、50mLの試験液をそのシリンダー内に一度に投入するとともに、ストップウォッチを用いて、試験液がシリンダー内から完全に消失するまでの時間を測定し、1回目の浸透時間(秒)とした。次に、前記シリンダーをはずし、吸収性物品をそのままの状態で保存し、1回目の試験液投入開始から30分後及び60分後にも、1回目と同じ位置に前記円筒型シリンダーを置いて同様の操作を行い、2回目及び3回目の浸透時間(秒)を測定した。1回目~3回目の秒数の合計を合計浸透時間とした。合計浸透時間が短いほど、吸収性物品として好ましいと言える。例えば、合計浸透時間として70秒以下が好ましく、65秒以下がより好ましい。
前記浸透時間の測定終了から60分経過後、吸収性物品上の試験液投入位置付近に、あらかじめ質量(We(g)、約70g)を測定しておいた10cm四方の濾紙(約80枚)を置き、その上に底面が10cm×10cmの5kgの重りを載せた。5分間の荷重後、濾紙の質量(Wf(g))を測定し、増加した質量を逆戻り量(g)とした。逆戻り量が小さいほど、吸収性物品として好ましいと言える。例えば、逆戻り量として30g以下が好ましく、28g以下がより好ましい。
液体逆戻り量(g)=Wf-We
前記逆戻り量の測定後5分以内に、試験液が浸透したそれぞれの吸収性物品の長手方向の拡がり寸法(cm)を測定した。なお、小数点以下の数値は四捨五入した。拡散長の数値が大きいほど試験液の拡散性が良好なため、好ましいと言える。
12 静圧調整用ガラス管
13 0.69質量%塩化ナトリウム水溶液
14 コック付L字管
15 コック
20 円筒状容器
21 ピストン型重り
22 シリンダー
23 穴
24 ガラスフィルター
25 膨潤ゲル
26 ステンレス金網
31 漏斗
32 支持台
33 捕集容器
34 上皿天秤
Claims (7)
- 内部架橋剤が添加された水溶性エチレン性不飽和単量体を使用し、第1段目の逆相懸濁重合によって得られた1次粒子を第2段目の逆相懸濁重合によって凝集させる吸水性樹脂の製造方法であって、
第1段目の内部架橋剤の添加量を第1段目に用いられる水溶性エチレン性不飽和単量体100モルに対してAモル、及び第2段目の内部架橋剤の添加量を第2段目に用いられる水溶性エチレン性不飽和単量体100モルに対してBモルとした場合、A及びBが
A≦5.0×10-3、かつ2≦B/A≦10
の関係を満たすことを特徴とする、吸水性樹脂の製造方法。 - 内部架橋剤が、(ポリ)エチレングリコールジグリシジルエーテル、(ポリ)プロピレングリコールジグリシジルエーテル、(ポリ)グリセリンジグリシジルエーテル及びN,N’-メチレンビス(メタ)アクリルアミドからなる群より選ばれた少なくとも1種である請求項1に記載の吸水性樹脂の製造方法。
- 水溶性エチレン性不飽和単量体の第2段目の逆相懸濁重合終了後、後架橋剤を添加して後架橋を行う請求項1または2に記載の吸水性樹脂の製造方法。
- 水溶性エチレン性不飽和単量体が、(メタ)アクリル酸又はその塩、(メタ)アクリルアミド、並びに、N,N-ジメチルアクリルアミドからなる群より選ばれた少なくとも1種である請求項1~3のいずれか1項に記載の吸水性樹脂の製造方法。
- 請求項1~4のいずれか1項に記載の製造方法によって得られる吸水性樹脂。
- 請求項5に記載の吸水性樹脂と親水性繊維とからなる吸収体。
- 液体透過性シートと液体不透過性シートの間に、請求項6に記載の吸収体が保持されてなる吸収性物品。
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WO2014038324A1 (ja) * | 2012-09-10 | 2014-03-13 | 住友精化株式会社 | 吸水性樹脂、吸収体及び吸収性物品 |
CN104918964A (zh) * | 2014-07-11 | 2015-09-16 | 住友精化株式会社 | 吸水性树脂的制造方法 |
WO2016006135A1 (ja) * | 2014-07-11 | 2016-01-14 | 住友精化株式会社 | 吸水性樹脂の製造方法 |
US11136420B2 (en) | 2014-07-11 | 2021-10-05 | Sumitomo Seika Chemicals Co. Ltd. | Water-absorbent resin and method of producing water-absorbent resin |
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CN103864980B (zh) * | 2014-02-24 | 2016-02-24 | 杭州电子科技大学 | 一种三元共聚农用高吸水树脂的制备方法 |
CN105153350B (zh) * | 2015-07-28 | 2017-04-05 | 华南理工大学 | 一种三层网状结构的高加压吸收量吸水树脂及其制备方法 |
US11505690B2 (en) | 2017-02-16 | 2022-11-22 | Basf Se | Water-swellable polymer particles |
KR102513981B1 (ko) * | 2017-09-26 | 2023-03-23 | 주식회사 엘지화학 | 고흡수성 수지의 제조 방법 |
KR102626788B1 (ko) * | 2018-11-20 | 2024-01-17 | 주식회사 엘지화학 | 고흡수성 수지의 제조 방법 및 고흡수성 수지 |
CN113543877A (zh) * | 2019-03-08 | 2021-10-22 | 住友精化株式会社 | 吸水性树脂颗粒、吸收体、吸收性物品、吸水性树脂颗粒的通液维持率的测定方法及吸水性树脂颗粒的制造方法 |
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TWI507423B (zh) | 2015-11-11 |
JP5885735B2 (ja) | 2016-03-15 |
US20130330566A1 (en) | 2013-12-12 |
BR112013024775B1 (pt) | 2020-12-08 |
EP2692741A1 (en) | 2014-02-05 |
KR101841799B1 (ko) | 2018-03-23 |
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EP2692741A4 (en) | 2014-09-10 |
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