Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
  • B01J20/26—Synthetic macromolecular compounds
  • B01J20/264—Synthetic macromolecular compounds derived from different types of monomers, e.g. linear or branched copolymers, block copolymers, graft copolymers
• • 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
  • C08F293/00—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule
  • C08F293/005—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B2/00—Preservation of foods or foodstuffs, in general
  • A23B2/70—Preservation of foods or foodstuffs, in general by treatment with chemicals
  • A23B2/725—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of liquids or solids
  • A23B2/729—Organic compounds; Microorganisms; Enzymes
  • A23B2/742—Organic compounds containing oxygen
  • A23B2/754—Organic compounds containing oxygen containing carboxyl groups
  • A23B2/758—Carboxylic acid esters
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
  • B01J20/28016—Particle form
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/3085—Chemical treatments not covered by groups B01J20/3007 - B01J20/3078
• • 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
  • C08F297/00—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer
  • C08F297/02—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer using a catalyst of the anionic type
  • C08F297/026—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer using a catalyst of the anionic type polymerising acrylic acid, methacrylic acid or derivatives thereof
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
  • A01G24/00—Growth substrates; Culture media; Apparatus or methods therefor
  • A01G24/30—Growth substrates; Culture media; Apparatus or methods therefor based on or containing synthetic organic compounds
  • A01G24/35—Growth substrates; Culture media; Apparatus or methods therefor based on or containing synthetic organic compounds containing water-absorbing polymers
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
  • A01K1/00—Housing animals; Equipment therefor
  • A01K1/015—Floor coverings, e.g. bedding-down sheets ; Stable floors
  • A01K1/0152—Litter
  • A01K1/0155—Litter comprising organic material
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
  • A01K1/00—Housing animals; Equipment therefor
  • A01K1/015—Floor coverings, e.g. bedding-down sheets ; Stable floors
  • A01K1/0157—Mats; Sheets
• • 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
  • A61F2013/530481—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 having superabsorbent materials, i.e. highly absorbent polymer gel materials
• • 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
  • C08F218/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid
  • C08F218/02—Esters of monocarboxylic acids
  • C08F218/04—Vinyl esters
  • C08F218/08—Vinyl acetate
• • 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
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/12—Hydrolysis

Definitions

• the present invention relates to a block copolymer having excellent absorbability to water, salt water, etc., and a method for producing the same.
• the present invention also relates to an absorbent and an absorbent article using the block copolymer.
• highly water-absorbent resins have been widely used for sanitary products, sanitary materials such as disposable diapers, and soil water-retaining agents.
• a highly water-absorbent resin include a polyacrylate crosslinked product, a self-crosslinked polyacrylic acid salt, a starch-acrylate graft copolymer crosslinked product, and a hydrolyzate of an acrylamide copolymer crosslinked product.
• Cross-linked isobutylene-neutralized products of maleic anhydride copolymers, cross-linked products of carboxyalkyl cellulose salts and the like are known.
• Patent Document 1 describes a highly water-absorbent resin using a crosslinked polymer of an ethylenically unsaturated monomer having acrylic acid and / or an acrylate as a main constituent unit.
• a crosslinked polymer is water-insoluble and has insufficient biodegradability.
• Patent Document 2 describes an absorbent obtained by further cross-linking a biodegradable water-absorbent resin obtained by cross-linking a carboxyalkyl cellulose salt or the like with an amino acid or the like with a surface cross-linking agent.
• the absorbent is insoluble in water and may still have insufficient biodegradability.
• polyvinyl alcohol is a crystalline water-soluble polymer material, and by utilizing its excellent water solubility and film properties (strength, oil resistance, film-forming property, oxygen gas barrier property, etc.), it is an emulsifier and a suspending agent. , Surfactants, fiber processing agents, various binders, paper processing agents, adhesives, films and the like.
• Non-Patent Document 1 and Non-Patent Document 2 describe block copolymers containing a polyacrylic acid block and a polyvinyl alcohol block, and block copolymers containing a potassium polyacrylate block and a polyvinyl alcohol block.
• these block copolymers may have insufficient water absorption or it may be difficult to maintain their shape after water absorption.
• these documents do not describe anything about the water absorption of block copolymers.
• the present invention has been made to solve the above problems, and an object of the present invention is to provide a block copolymer having high absorbency to water, salt water, etc., gel shape retention, and water solubility.
• the above-mentioned problem is to provide a vinyl alcohol-based polymer block (b) and an ionic polymer block (c) containing a monomer unit having an ionic group forming a salt and a vinyl alcohol-based monomer unit.
• the block copolymer (A) containing the ionic group is a carboxylic acid group, a sulfonic acid group or an ammonium group, and the number average molecular weight (Mn b ) of the polymer block (b) is 15,000 to 220.
• the content of the vinyl alcohol-based monomer unit in the ionic polymer block (c) is 5 to 95 mol% with respect to the total monomer unit, and the content of the block copolymer (A) is 000.
• the number average molecular weight (Mn a) is 20,000 to a 440,000, and number average molecular weight number average molecular weight for (Mn a) (Mn b) the ratio of (Mn b / Mn a) from 0.1 to zero. It is solved by providing what is 9.
• the ionic group is a carboxylic acid group. It is also preferable that the counter ion of the ionic group is an ion of a group 1, 2, 12, 13 or 17 element of the periodic table.
• the content of the monomer unit having an ionic group which forms the salt (J A) is from 2 to 90 mol% preferable. It is also preferable that the content (K c ) of the monomer unit having an ionic group forming the salt in the polymer block (c) is 5 to 95 mol% with respect to all the monomer units. ..
• the degree of saponification of the block copolymer (A) is 80 to 99.99 mol%. It is also preferable that the molecular weight distribution (Mw A / Mn A ) of the block copolymer (A) is 1.05 to 1.95. It is also preferable that the block copolymer (A) is biodegradable.
• the amount of deionized water absorbed per 0.1 g of the block copolymer (A) at 20 ° C. is 20 g or more. It is also preferable that the absorption amount of the 0.9 mass% sodium chloride aqueous solution per 1 g of the block copolymer (A) at 20 ° C. is 20 g or more.
• the soluble content when dissolved in water at 95 ° C. is preferably 95% by mass or more, and the soluble content when dissolved in water at 20 ° C. is more preferably 95% by mass or more.
• An absorbent material containing the block copolymer (A) is a preferred embodiment of the present invention. It is preferable that the absorbent is particles.
• An absorbent article having the absorbent material is a more preferred embodiment. It is preferable that the absorbent article is for hygiene, daily necessities, construction / civil engineering, industrial, agricultural, medical or food.
• the above-mentioned problems are the polymerization of a vinyl ester monomer by controlled radical polymerization in the presence of a radical polymerization initiator and a control agent, and the copolymerization of a vinyl ester monomer and an ionic monomer having an ionic group or a derivative thereof.
• a vinyl ester-based block copolymer containing a vinyl ester polymer block (b1) and an ionic polymer block (c1) containing a vinyl ester monomer unit and an ionic monomer unit.
• An essential step includes a polymerization step of obtaining the polymer and a saponification step of forming the vinyl alcohol monomer unit by saponifying the vinyl ester monomer unit in the vinyl ester-based block copolymer obtained in the polymerization step. It is also solved by providing a method for producing a block polymer (A) having a salt forming step of forming a salt in the ionic monomer unit as an optional step.
• the block copolymer (A) of the present invention has both high absorbency to water, salt water, etc., gel shape retention, and water solubility. Therefore, the block copolymer (A) is suitably used as an absorbent or an absorbent article for water, salt water, or the like. According to the production method of the present invention, the block copolymer (A) can be produced.
• the block copolymer (A) of the present invention contains a vinyl alcohol-based polymer block (b), a monomer unit having an ionic group forming a salt, and a vinyl alcohol-based monomer unit. It contains the sex polymer block (c), the ionic group is a carboxylic acid group, a sulfonic acid group or an ammonium group, and the number average molecular weight (Mn b ) of the polymer block (b) is 15,000.
• the content of the vinyl alcohol-based monomer unit in the ionic polymer block (c) is 5 to 95 mol% with respect to the total monomer unit, and the block copolymer (A) is obtained.
• the number average molecular weight of) (Mn a) is 20,000 to 440,000, and number average molecular weight (number average molecular weight for Mn a) (Mn b ratio) (Mn b / Mn a) is 0.1 to It is 0.9.
• the block copolymer (A) of the present invention has both high absorbency to water, salt water, etc., gel shape retention, and water solubility. It is considered that the high absorbency is caused by the ionic polymer block (c), and the gel shape retention and water solubility are caused by the vinyl alcohol-based polymer block (b).
• a preferred method for producing the block copolymer (A) of the present invention is to polymerize a vinyl ester monomer by controlled radical polymerization in the presence of a radical polymerization initiator and a controlling agent, and to polymerize the vinyl ester monomer and an ionic group.
• the ionic monomer having the derivative thereof is polymerized, and the vinyl ester polymer block (b1) and the ionic polymer block (c1) containing the vinyl ester monomer unit and the ionic monomer unit are carried out.
• the vinyl alcohol monomer unit in the vinyl ester block copolymer obtained in the polymerization step is saponified. It has a saponification step for forming the polymer as an essential step.
• the manufacturing method will be described in detail.
• the polymerization process will be described.
• the vinyl ester monomer is polymerized and the vinyl ester monomer and the ionic monomer are polymerized by controlled radical polymerization in the presence of a radical initiator and a control agent.
• the vinyl ester polymer block (b1) is synthesized by polymerizing the vinyl ester
• the ionic polymer block (c1) is synthesized by polymerizing the vinyl ester monomer and the ionic monomer.
• the ionic monomer unit and the vinyl ester monomer unit are separated by copolymerizing the ionic monomer and the vinyl ester monomer.
• Examples of the vinyl ester monomer used in the production method of the present invention include vinyl formate, vinyl acetate, trifluorovinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, and capric acid.
• Examples thereof include vinyl, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versaticate and the like, but vinyl acetate is preferably used from an economical point of view.
• the ionic monomer used in the production method of the present invention is a monomer having an ionic group or a derivative thereof.
• the ionic group is a carboxylic acid group, a sulfonic acid group or an ammonium group. These may be used alone or in combination of two or more.
• a carboxylic acid group is preferable.
• the monomer having an ionic group may or may not form a salt.
• Examples of the monomer having an ionic group or a derivative thereof used as the ionic monomer include a monomer having a carboxylic acid group such as (meth) acrylic acid, maleic acid, itaconic acid, and fumaric acid, or a derivative thereof.
• Sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, 2- (meth) acryloyl ethane sulfonic acid, 2- (meth) acryloyl propane sulfonic acid.
• Monomer having a group or a derivative thereof vinyloxyethyltrimethylammonium chloride, vinyloxybutyltrimethylammonium chloride, N-acrylamidemethyltrimethylammonium chloride, 3- (methacrylamide) propyltrimethylammonium chloride, N-acrylamideethyltrimethylammonium chloride , Allyltrimethylammonium chloride, methallyltrimethylammonium chloride and other monomers having an ammonium group or derivatives thereof, and among them, a monomer having a carboxylic acid group or a derivative thereof is preferable, and a single amount having a carboxylic acid group. The body or ester thereof is more preferred.
• a (meth) acrylic acid ester is preferable.
• the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, N-propyl (meth) acrylate, i-propyl (meth) acrylate, and N-butyl (meth) acrylate.
• Methyl acrylate is more preferred.
• the (meth) acrylic acid ester may be a methacrylic acid ester or an acrylic acid ester, but an acrylic acid ester is more preferable.
• a (meth) acrylamide-based monomer is preferable, 2- (meth) acrylamide-2-methylpropanesulfonic acid is preferable, and 2-acrylamide-2-methylpropanesulfonic acid is preferable. More preferred.
• a (meth) acrylamide-based monomer is preferable, and 3- (methacrylamide) propyltrimethylammonium chloride is preferable.
• block copolymer (A) of the present invention is an ethylenically unsaturated monomer (e) that can be copolymerized with the vinyl ester monomer and the ionic monomer as long as the effect of the present invention is not impaired. ) May be contained.
• Examples of the ethylenically unsaturated monomer (e) include olefins such as ethylene, propylene, 1-butene and isobutene; acrylamides such as acrylamide and N-alkyl (1 to 18 carbon atoms) acrylamide and acrylamides such as N and N-dimethylacrylamide; Methacrylate, N-alkyl (1-18 carbon atoms) Methacrylate, N, N-dimethylmethacrylate and other methacrylicamides; N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide and other N-vinylamides; acrylonitrile, Vinyl cyanide such as methacrylonitrile; vinyl ether such as alkyl (1 to 18 carbon atoms) vinyl ether, hydroxyalkyl vinyl ether, alkoxyalkyl vinyl ether; halogen such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl
• Vinyl carbonate; vinyl silane such as trimethoxyvinyl silane; allyl compounds such as allyl acetate, allyl chloride, allyl alcohol, dimethyl allyl alcohol and the like can be mentioned.
• the ethylenically unsaturated monomer (e) it may be polymerized at the time of the polymerization of the vinyl ester polymer block (b1), or it may be polymerized at the time of the polymerization of the ionic polymer block (c1). It may be polymerized separately from the polymerization of the vinyl ester polymer block (b1) and the ionic polymer block (c1).
• the content of the ethylenically unsaturated monomer (e) in the vinyl alcohol-based polymer block (b) and the ionic polymer block (c) constituting the block copolymer (A) is in each block. It is preferably 10 mol% or less, more preferably 3 mol% or less, still more preferably 1 mol% or less, and particularly preferably not substantially contained in the total monomer unit. Further, the content of the ethylenically unsaturated monomer (e) is preferably 10 mol% or less, more preferably 3 mol% or less, with respect to all the monomer units of the block copolymer (A). It is more preferably mol% or less, and particularly preferably not substantially contained.
• the controlled radical polymerization adopted in the production method of the present invention is a polymerization reaction in which a growth radical terminal (active species) is placed in an equilibrium state with a covalent bond species (dormant species) bonded to a control agent and the reaction proceeds. That is.
• the control agent used in the production method of the present invention include an organic cobalt complex, an organic iodine compound, a thiocarbonyl compound, an organic tellurium compound, an organic compound having an oxidation-reduction center, an organic compound having a stable radical, and the like, and among them, organic. Cobalt complexes are preferred.
• organic cobalt complex examples include those containing a divalent cobalt atom and an organic ligand.
• Suitable organic cobalt complexes include, for example, cobalt (II) acetylacetonate [Co (acac) 2 ], cobalt (II) porphyrin complex and the like. Of these, cobalt (II) acetylacetonate is preferable from the viewpoint of manufacturing cost.
• Examples of the polymerization method include known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among them, a bulk polymerization method of polymerizing without a solvent or a solution polymerization method of polymerizing in various organic solvents is usually adopted. In order to obtain a polymer having a narrow molecular weight distribution, a massive polymerization method that does not use a solvent or dispersion medium that may cause side reactions such as chain transfer is preferable.
• solution polymerization may be preferable from the viewpoint of adjusting the viscosity of the reaction solution and controlling the polymerization rate.
• organic solvent used as a solvent in solution polymerization include esters such as methyl acetate and ethyl acetate; aromatic hydrocarbons such as benzene and toluene; lower alcohols such as methanol and ethanol; and the like. Of these, esters and aromatic hydrocarbons are preferably used to prevent chain transfer.
• the amount of the solvent used may be determined in consideration of the viscosity of the reaction solution according to the number average molecular weight of the target block copolymer (A).
• the mass ratio (solvent / monomer) may be selected from the range of 0.01 to 10.
• the mass ratio (solvent / monomer) is preferably 0.1 or more, and preferably 5 or less.
• azo-based initiators As the radical initiator used in the polymerization step, conventionally known azo-based initiators, peroxide-based initiators, redox-based initiators and the like are appropriately selected.
• the azo-based initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2'-azobis (4-methoxy-2,4-). Dimethylvaleronitrile) and the like
• peroxide-based initiator include percarbonate compounds such as diisopropylperoxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethylperoxydicarbonate; t-butyl.
• Perester compounds such as peroxyneodecaneto, ⁇ -cumylperoxyneodecaneate, t-butylperoxyneodecanete; acetylcyclohexylsulfonyl peroxide, diisobutyryl peroxide; 2,4,4-trimethylpentyl-2 -Peroxyphenoxyacetate and the like can be mentioned. Further, potassium persulfate, ammonium persulfate, hydrogen peroxide and the like can be combined with the above-mentioned initiator to prepare the initiator.
• redox-based initiator examples include a combination of the above-mentioned peroxide and a reducing agent such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, and longalit.
• a reducing agent such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, and longalit.
• the amount of the initiator used differs depending on the polymerization catalyst and cannot be unconditionally determined, and is arbitrarily selected according to the polymerization rate.
• the radical generated by the decomposition of the radical initiator is bonded to a small number of monomers, and the radical at the growth end of the short-chain polymer is covalently bonded to the controlling agent.
• the resulting dormant species is produced.
• a short-chain polymer is produced and only converted into a dormant species, and the degree of polymerization does not substantially increase. This period is called the induction period.
• the control agent is consumed, the growth period in which the degree of polymerization increases progresses, and the molecular weight of most of the molecular chains in the reaction system increases in proportion to the polymerization time in the same manner. This makes it possible to obtain a vinyl ester-based block copolymer having a narrow molecular weight distribution.
• the time required for the monomer polymerization step is usually 3 to 50 hours including the induction period and the growth period.
• the amount of the control agent added to the reaction solution is determined in consideration of the target number average molecular weight and the polymerization rate. Usually, it is preferable to use 0.001 to 1 mol of the control agent with respect to 100 mol of the monomer.
• the number of moles of radicals generated is not greater than the number of moles of the regulator, the polymerization reaction proceeds only by the mechanism by which the regulator is thermally dissociated from the Dormant species, so that the polymerization rate becomes extremely small depending on the reaction temperature. It ends up. Therefore, considering that the radical initiator generates two radicals, the number of moles of the radical initiator used needs to be more than 1/2 times the number of moles of the control agent. In general, the amount of active radicals supplied by the initiator depends on the initiator efficiency, so some initiators are not actually used to form the dormant and are inactivated. Therefore, the number of moles of the radical initiator used is preferably 1 times or more, more preferably 1.5 times or more the number of moles of the control agent.
• the number of moles of the radical initiator used is preferably 10 times or less, more preferably 6 times or less the number of moles of the control agent.
• the method for mixing the radical initiator, the control agent and the monomer is not particularly limited as long as the method can control the high degree of polymerization of the polymer by producing the dormant species.
• a method of mixing the obtained mixture and the monomer after mixing the radical initiator and the control agent a method of mixing the radical initiator, the control agent and the monomer at once, the control agent and the monomer.
• examples thereof include a method of mixing the obtained mixture with the radical initiator after mixing.
• the radical initiator, the control agent, and the monomer may be divided and mixed.
• the control agent produces a dormant species covalently bonded to the polymer terminal of a short chain, and then the dormant species and the monomer are produced.
• Examples thereof include a method of mixing the balance to increase the degree of polymerization.
• the Dormant species may be isolated as a macroinitiator and then mixed with the rest of the monomer to increase the degree of polymerization.
• either the vinyl ester polymer block (b1) or the ionic polymer block (c1) may be synthesized first.
• the vinyl ester polymer block (b1) is first synthesized, the vinyl ester monomer, optionally the ethylenically unsaturated monomer (e), the radical initiator and the control agent are mixed by the method described above. This initiates the polymerization of the vinyl ester monomer. It is preferable not to use an ionic monomer in the synthesis of the vinyl ester polymer block (b1).
• the vinyl ester monomer and the ionic monomer are polymerized to obtain the ionic polymer block (c1). Perform synthesis.
• the ionic monomer may be added to the reaction solution to start the polymerization of the ionic monomer, but the gel shape retention is improved. From the viewpoint of further improvement, the ionic monomer is added to the reaction solution without removing the vinyl ester monomer, and the copolymerization of the remaining vinyl ester monomer and the ionic monomer is started. It is preferable to do so.
• the method of adding the ionic monomer is not particularly limited, and examples thereof include a method of batch addition and a method of feeding over time. However, the gel shape retention is maintained by uniformly introducing the ionic monomer unit. The latter is preferable from the viewpoint of further improving. Further, if necessary, an additional vinyl ester monomer or ethylenically unsaturated monomer (e) may be added together with the ionic monomer.
• the number average degree of polymerization of the polymer can be confirmed by a GPC (gel permeation chromatography) method, and specifically, the method described in Examples described later is adopted.
• the vinyl ester polymer block (b1) When the vinyl ester polymer block (b1) is first synthesized, the vinyl ester polymer block (b1) and the polymer block (c1) containing the vinyl ester monomer unit and the ionic monomer unit are used.
• the vinyl ester polymer block (b1) and the polymer block (c1) containing the vinyl ester monomer unit and the ionic monomer unit are used.
• a ternary vinyl ester block copolymer of block (b1) -block (c1) -block (b1) can be obtained.
• the portion obtained by polymerizing the vinyl ester in a state where the molar ratio (ionic monomer / vinyl ester) of the ionic monomer unit to the vinyl ester in the reaction solution is 0.00001 or less is vinyl. It is an ester polymer block (b1).
• the time point at which the molar ratio (ionic monomer / vinyl ester) reaches 0.00001 is determined by the method described in Examples.
• the reaction may be stopped when the number-average degree of polymerization of the vinyl ester-based block copolymer reaches the desired value.
• the ionic monomer may be added again to the reaction solution of the ternary vinyl ester block copolymer to continue the polymerization. ..
• the polymerization is started by mixing the ionic monomer, the radical initiator and the organic cobalt complex by the above-mentioned method.
• the ethylenically unsaturated monomer (e) may be further added. In this way, after synthesizing the polymer block (c1) containing the vinyl ester monomer unit and the ionic monomer unit, each block is sequentially formed.
• the polymerization temperature when synthesizing the vinyl ester polymer block (b1) and the ionic polymer block (c1) is preferably, for example, 0 ° C to 80 ° C.
• the polymerization temperature is more preferably 10 ° C. or higher, further preferably 20 ° C. or higher.
• the polymerization temperature exceeds 80 ° C., the molecular weight distribution of the obtained block copolymer (A) tends to be widened. From this point, the polymerization temperature is more preferably 65 ° C. or lower, and even more preferably 50 ° C. or lower.
• the number average degree of polymerization or the polymerization rate of the vinyl ester-based block copolymer reaches the desired value in the polymerization step, it is preferable to carry out a termination step of stopping the polymerization reaction by adding a polymerization terminator.
• the polymerization terminator include 1,1-diphenylethylene; styrene compounds such as styrene, ⁇ -methylstyrene and 4-tert-butylstyrene; p-methoxyphenol, hydroquinone, cresol, t-butylcatechol, p-nitrosophenol and the like.
• the number of moles of the polymerization inhibitor added is preferably 1 to 100 mol with respect to 1 mol of the added control agent. If the number of moles of the polymerization inhibitor is too small, the radicals at the end of the polymer cannot be sufficiently captured, and the color tone of the obtained block copolymer (A) may be deteriorated. On the other hand, if the number of moles of the polymerization inhibitor is too large, the production cost may increase.
• the temperature of the reaction solution in the shutdown step may be any temperature as long as the polymerization terminator can react with the radical at the terminal of the vinyl ester block copolymer, and is preferably 0 to 80 ° C.
• the time required for the stop process is usually 10 minutes to 5 hours.
• the obtained vinyl ester-based block copolymer solution is brought into contact with an aqueous solution containing a water-soluble ligand before the saponification step to bring the vinyl ester-based block copolymer into contact with the aqueous solution. It is preferable to carry out an extraction step of extracting and removing the cobalt complex from the solution.
• the block copolymer (A) having a good hue can be obtained by performing the saponification step after removing the cobalt complex contained in the vinyl ester-based block copolymer solution in advance.
• the aqueous solution that does not dissolve in each other and the vinyl ester block copolymer solution were vigorously stirred so that the area of the interface between the two was large, and then allowed to stand, and separated into an oil layer and an aqueous layer.
• the operation of removing the aqueous layer may be performed later. This operation may be repeated a plurality of times.
• the water-soluble ligand used in the extraction step is preferably an acid having a pKa of 0 to 12 at 25 ° C.
• the pKa is preferably 2 or more.
• the pKa is preferably 7 or less.
• the acid is a polyvalent acid, the first dissociation constant (pKa1) needs to be in the above range.
• the acid having a pKa of 0 to 12 is preferably a carboxylic acid or a phosphoric acid (pKa1 is 2.1), and more preferably a carboxylic acid.
• pKa1 is 2.1
• acetic acid pKa is 4.76 is particularly preferable.
• the pH of the aqueous solution containing the water-soluble ligand is preferably 0 to 5.
• the pH is more preferably 1 or more, and even more preferably 1.5 or more.
• the pH is more preferably 4 or less, still more preferably 3 or less.
• the vinyl ester monomer unit contained in the vinyl ester polymer block (b1) or the ionic polymer block (c1) in the vinyl ester block copolymer obtained in the polymerization step is saponified.
• the vinyl ester polymer block (b1) is converted into the vinyl alcohol-based polymer block (b).
• the vinyl ester-based block copolymer produced by the above method is saponified in a state of being dissolved in alcohol, so that the vinyl ester monomer unit in the vinyl ester-based block copolymer is a single amount of vinyl alcohol. Converted to body units.
• the acrylic acid ester monomer unit in the copolymer is converted into an acrylic acid monomer unit. Or the converted acrylic acid monomer unit may form a salt. Further, the acrylic acid ester monomer unit or the acrylic acid monomer unit may form a lactone ring with an adjacent vinyl alcohol monomer unit.
• Examples of the alcohol used for the saponification reaction include lower alcohols such as methanol and ethanol, and methanol is particularly preferably used. Further, the alcohol may be a hydrous alcohol or a dehydrated alcohol.
• the alcohol used in the saponification reaction may contain acetone, an ester such as methyl acetate or ethyl acetate, or a solvent such as toluene.
• Examples of the catalyst used for the saponification reaction include hydroxides of alkali metals such as potassium hydroxide and sodium hydroxide; alkaline catalysts such as sodium methylate; and acid catalysts such as inorganic acids.
• the temperature of the saponification reaction for example, the range of 20 to 70 ° C. is appropriate. If a gel-like product precipitates as the saponification reaction progresses, the product is crushed at that point, washed, and then dried.
• the production method of the present invention has, as an optional step, a salt forming step of forming a salt in the ionic monomer unit in the block copolymer after the saponification step.
• the method for forming the salt in the ionic monomer unit is not particularly limited, and a known method may be appropriately adopted depending on the type of the ionic monomer unit.
• the ionic polymer block (c1) is an ionic polymer block (c1) containing a monomer unit having an ionic group forming a salt and a vinyl alcohol-based monomer unit. It is converted to c).
• the block (c1) after the saponification step contains a monomer unit having an ionic group forming a salt
• the block (c1) corresponds to the block (c). Therefore, the block copolymer (A) of the present invention can be obtained without going through the salt forming step.
• acrylic acid ester When acrylic acid ester is used as the ionic monomer, it is preferable to perform the salt forming step on the block copolymer after the saponification step. As a result, the acrylic acid ester unit, the acrylic acid unit and the lactone ring are converted into the acrylic acid monomer unit forming the salt.
• Specific examples thereof include a method of mixing the block copolymer after the saponification step with an aqueous solution of a metal hydroxide and an alcohol.
• the metal hydroxide include sodium hydroxide, potassium hydroxide, calcium hydroxide and the like.
• the alcohol include methanol, ethanol and the like. It is appropriate that the salt forming step is carried out in the range of, for example, 20 to 100 ° C.
• the monomer unit having an ionic group in the ionic polymer block (c) is formed by the above-mentioned ionic monomer.
• the ionic group is a carboxylic acid group, a sulfonic acid group or an ammonium group, and a carboxylic acid group is preferable.
• the monomer unit having an ionic group is as described above, but among them, the monomer unit having a carboxylic acid group is preferable, and the acrylic acid monomer unit is more preferable.
• the monomer unit having an ionic group in the ionic polymer block (c) forms a salt.
• the counter ion of the monomer unit is not particularly limited, but is preferably an ion of Group 1, 2, 12, 13 or 17 of the periodic table, and among them, sodium ion, potassium ion, magnesium ion, calcium ion, and the like. Cations such as zinc ion and aluminum ion, and anions such as chloride ion are preferable. As the cation, sodium ion and calcium ion are more preferable, and sodium ion is further preferable.
• the block copolymer (A) of the present invention thus obtained comprises a vinyl alcohol-based polymer block (b), a monomer unit having an ionic group forming a salt, and a vinyl alcohol-based monomer unit. It contains the ionic polymer block (c) contained therein.
• the block copolymer (A) may be a binary block copolymer consisting of one block (b) and one block (c), or one block (b) and two blocks ( c) or a ternary block copolymer consisting of two blocks (b) and one block (c), or a total of four or more blocks (b) and blocks (c). It may be a multi-block copolymer.
• the block copolymer (A) is a binary block copolymer or a ternary block copolymer.
• the bonding form of the block (b) and the block (c) is preferably linear.
• the block copolymer (A) may contain blocks other than the block (b) and the block (c), but the content thereof is preferably 10 mol% or less, preferably 1 mol% or less. Is more preferable.
• the degree of saponification of the block copolymer (A) of the present invention is preferably 80 to 99.99 mol%.
• the degree of saponification is the ratio of the number of moles of the vinyl alcohol monomer unit to the total number of moles of the vinyl ester monomer unit and the vinyl alcohol monomer unit in the block copolymer (A) ( Mol%). If the degree of saponification is less than 80 mol%, the crystallinity of the block copolymer may be too low to maintain the gel shape, and the desired absorption performance may not be obtained.
• the degree of saponification is preferably 85 mol% or more, more preferably 90 mol% or more, and further preferably 95 mol% or more.
• the degree of saponification is preferably 99.95 mol% or less.
• the degree of saponification can be determined by 1 H-NMR measurement of the vinyl alcohol-based block copolymer (A), and specifically, the method described in Examples is adopted.
• the content of units derived from an ionic monomer having an ionic group or derivatives thereof (Z A) is 2 to 90 mol% It is preferable to have.
• the unit derived from the ionic monomer includes an acrylic acid monomer unit forming a salt and an acrylic acid single amount not forming a salt.
• body unit includes an acrylic acid ester monomer unit and a lactone ring, the content (Z a) is the total amount of these units.
• the content of (Z A) is 2 mol% or more, absorption of the block copolymer (A) is further increased.
• the content (Z A) is more preferably not less than 3 mol%, more preferably at least 4 mol%, particularly preferably at least 5 mol%.
• the content (Z A) is not more than 90 mol%, the gel shape retention of the block copolymer (A) is further improved.
• the content (Z A) is more preferably 60 mol% or less, more preferably 40 mol% or less, particularly preferably 20 mol% or less.
• the content of the monomer unit having an ionic group which forms the salt (J A) is 2 to 90 mol% It is preferable to have.
• the content of (J A) is 2 mol% or more, absorption of the block copolymer (A) is further increased.
• the content (J A) is more preferably not less than 3 mol%, more preferably at least 4 mol%, particularly preferably at least 5 mol%.
• the content (J A) is not more than 90 mol%, the gel shape retention of the block copolymer (A) is further improved.
• the content (J A) is more preferably 60 mol% or less, more preferably 40 mol% or less, particularly preferably 20 mol% or less.
• the content of the vinyl alcohol-based monomer unit in the vinyl alcohol-based polymer block (b) with respect to all the monomer units is preferably 80 mol% or more, more preferably 90 mol% or more. Yes, more preferably 95 mol% or more, and particularly preferably 99 mol% or more.
• the vinyl alcohol-based monomer unit means a vinyl ester monomer unit and a vinyl alcohol monomer unit, and the content of the vinyl alcohol-based monomer unit is a vinyl ester monomer unit. And the total content of vinyl alcohol monomer units.
• the content of the vinyl alcohol monomer unit in the vinyl alcohol-based polymer block (b) with respect to all the monomer units is preferably 80 mol% or more, more preferably 90 mol% or more. Yes, more preferably 95 mol% or more, and particularly preferably 99 mol% or more.
• the content of the unit derived from the ionic monomer in the vinyl alcohol-based polymer block (b) with respect to all the monomer units is usually less than 0.1 mol%.
• the content (R c ) of the unit derived from the ionic monomer is preferably 5 to 95 mol% with respect to all the monomer units in the ionic polymer block (c).
• the content (R c ) is more preferably 6 mol% or more, further preferably 8 mol% or more, and particularly preferably 10 mol% or more.
• the content (R c ) is more preferably 80 mol% or less, further preferably 40 mol% or less, and 25 mol% or less from the viewpoint of further improving the gel shape retention of the block copolymer (A). Especially preferable.
• the content (K c ) of the monomer unit having an ionic group forming the salt in the ionic polymer block (c) is 5 to 95 mol% with respect to all the monomer units. Is preferable. When the content (K c ) is 5 mol% or more, the absorbability of the block copolymer (A) is further enhanced.
• the content (K c ) is more preferably 6 mol% or more, further preferably 8 mol% or more, and particularly preferably 10 mol% or more.
• the content (K c ) is more preferably 80 mol% or less, further preferably 40 mol% or less, and 25 mol% or less from the viewpoint of further improving the gel shape retention of the block copolymer (A). Especially preferable.
• the ionic polymer block (c) contains a vinyl alcohol-based monomer unit. This improves the gel shape retention and absorbability of the block copolymer (A).
• the content of the vinyl alcohol-based monomer unit (total content of the vinyl alcohol unit and the vinyl ester unit) in the ionic polymer block (c) with respect to all the monomer units is 5 to 95 mol%. If the content is less than 5 mol, the effect of improving the gel shape retention and absorbability of the block copolymer (A) cannot be obtained.
• the content is preferably 20 mol% or more, more preferably 60 mol% or more, still more preferably 75 mol% or more.
• the absorbability of the block copolymer (A) is lowered.
• the content is preferably 94 mol% or less, more preferably 92 mol% or less, still more preferably 90 mol% or less.
• the number average molecular weight (Mn A ) of the block copolymer (A) of the present invention is 20,000 to 440,000.
• Mn A the absorbability of the block copolymer (A) is improved.
• Mn A is preferably 30,000 or more, more preferably 40,000 or more, still more preferably 50,000 or more, and particularly preferably 60,000 or more.
• Mn A is 440,000 or less, the gel shape retention is improved.
• Mn A is preferably 300,000 or less, more preferably 250,000 or less, and even more preferably 200,000 or less.
• the number average molecular weight (Mn A ) and molecular weight distribution (Mw A / Mn A ) are the values obtained by measuring the block copolymer (A) with a tetrahydrofuran (THF) -based column using polymethylmethacrylate as a standard substance by the GPC method. be. The measuring method is as described in the examples.
• the number average molecular weight (Mn b ) of the vinyl alcohol polymer block (b) is 15,000 to 220,000.
• Mn b the number average molecular weight of each vinyl alcohol-based polymer block (b) is taken as the number average molecular weight (Mn b ). do.
• Mn b is 15,000 or more, the gel shape retention is improved while maintaining the absorbability.
• Mn b is preferably 20,000 or more, more preferably 30,000 or more, further preferably 35,000 or more, and particularly preferably 40,000 or more.
• Mn b exceeds 220,000, the absorbability decreases.
• Mn b is preferably 180,000 or less, more preferably 150,000 or less, still more preferably 120,000 or less.
• Mn b is the number average molecular weight of the obtained polymer and the content of each monomer unit after GPC measurement of the polymer sampled from the reaction solution during polymerization and 1 H-NMR measurement as necessary. It is calculated from the above, and specifically, the method described in the examples described later is adopted.
• the ratio (Mn b / Mn A ) of the number average molecular weight (Mn b ) of the vinyl alcohol polymer block (b) to the number average molecular weight (Mn A ) of the block copolymer (A) is 0.1 to 0.9. Is. When the ratio (Mn b / Mn A ) is 0.1 or more, the gel shape retention and water solubility of the block copolymer (A) are improved.
• the ratio (Mn b / Mn A ) is preferably 0.2 or more, more preferably 0.3 or more. On the other hand, when the ratio (Mn b / Mn A ) is 0.9 or less, the absorbability of the block copolymer (A) is improved.
• the ratio (Mn b / Mn A ) is preferably 0.8 or less, more preferably 0.7 or less.
• the molecular weight distribution (Mw A / Mn A ) of the block copolymer (A) of the present invention is preferably 1.05 to 1.95.
• a block copolymer (A) having a narrow molecular weight distribution can be obtained.
• the molecular weight distribution (Mw A / Mn A ) is preferably 1.80 or less, more preferably 1.65 or less, and further preferably 1.55 or less.
• the polymerization of the monomer containing the vinyl ester monomer and the polymerization of the monomer containing the ionic monomer and the vinyl ester monomer are performed to carry out the polymerization of the vinyl ester polymer block (b1).
• a vinyl ester-based block copolymer containing an ionic polymer block (c1) can be obtained.
• the vinyl alcohol-based block (b) and the ionic group forming the salt are formed.
• a block copolymer (A) containing an ionic polymer block (c) containing a monomer unit having a monomer unit and a vinyl alcohol-based monomer unit can be obtained.
• (meth) acrylic acid or (meth) acrylic acid ester is used as the ionic monomer
• the molar ratio (VA ) of the lactone ring to the total of the acid monomer unit and the lactone ring [total of the lactone ring / acrylic acid monomer unit and the lactone ring] is preferably 0.75 or more.
• the molar ratio ( VA ) [total of lactone ring / acrylic acid monomer unit and lactone ring] is high. That is, the molar ratio ( VA ) [lactone ring / total of acrylic acid monomer unit and lactone ring] is ionic including vinyl alcohol-based monomer unit and acrylic acid monomer unit forming a salt. It is an index of the randomness of the polymer block (c).
• the molar ratio ( VA ) [total of lactone ring / acrylic acid monomer unit and lactone ring] is 0.75 or more, the gel shape retention of the block copolymer (A) is further improved.
• the molar ratio ( VA ) [total of lactone ring / acrylic acid monomer unit and lactone ring] is more preferably 0.80 or more, further preferably 0.85 or more, and particularly preferably 0.90 or more.
• the conditions for heat treatment and drying of the block copolymer (A) the conditions described in Examples are adopted.
• block copolymer crystalline melting temperature of the re-saponified polymer (A) above saponification degree 99 mol% (Q A) [°C] is 210 ° C. or higher.
• Q A crystalline melting temperatures
• Q A is more preferably equal to or greater than 215 ° C., and even more preferably 220 ° C..
• Q A can be measured by a method described in Examples.
• the amount of deionized water absorbed per 0.1 g of the block copolymer (A) at 20 ° C. is 20 g or more. There is no particular upper limit, but it is usually less than 100 g. It is also preferable that the absorption amount of the 0.9 mass% sodium chloride aqueous solution per 1 g of the block copolymer (A) at 20 ° C. is 20 g or more. There is no particular upper limit, but it is usually less than 100 g.
• the absorption amount of deionized water or aqueous sodium chloride solution is measured by the method described in Examples. As described above, the block copolymer (A) having high absorbability of deionized water or saline solution is suitably used for various uses.
• the soluble content is preferably 95% by mass or more, and when dissolved in 1000 ml of water at 20 ° C, it is soluble. It is more preferable that the amount is 95% by mass or more.
• the block copolymer (A) having high solubility in water is excellent in terms of the environment. Further, since the block copolymer (A) can absorb water, salt water, or the like and then discharge the block copolymer (A) into the sewage, the amount of waste can be reduced. Furthermore, it is considered possible to develop new applications by utilizing the performance of such block copolymer (A).
• the soluble content is calculated by the method described in the Examples.
• the block copolymer (A) preferably has a high biodegradation rate. Due to its high biodegradation rate, it is environmentally friendly. Further, since both the soluble content and the biodegradation rate when dissolved in water described above are high, the waste of the block copolymer (A) can be further reduced.
• the biodegradation rate is preferably 20% or more, more preferably 40% or more. The biodegradation rate can be determined by the method described in Examples.
• the absorbability and water solubility of the block copolymer (A) of the present invention can be appropriately changed depending on the design of the block copolymer (A).
• the amount of deionized water absorbed per 0.1 g is X DIW [g]
• the amount of soluble component when 1 g of block copolymer (A) is dissolved in 1000 ml of water at 95 ° C. is Y 95 [mass]. %]
• X DIW is 20 or more and Y 95 is 95 or more and Y 20 of 95 or more; X DIW of 20 or more, Y 95 of 95 or more, Y 20 of 0 or more and 95 or less; X DIW of 40 or more, Y 95 of 95 or more, Y 20 95 more copolymers; can be made of such a block copolymer (a); X DIW over 40, Y 95 95 or more, Y 20 is 0 or more 95 or less of the copolymer. Further, the amount of soluble in water may be adjusted in a temperature range other than the above-mentioned 95 ° C. and 20 ° C. depending on the intended use.
• An absorbent material containing the block copolymer (A) is a preferred embodiment of the present invention.
• the form of the absorbent material is not particularly limited, and examples thereof include particles, sheets, tapes, gels, plasters, films, fibers, and the like, and particles are particularly preferable.
• the content of the block copolymer (A) in the absorbent material is not particularly limited, but is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more.
• a material that prevents the block copolymer (A) from falling off and does not prevent the permeation of the liquid is appropriately used, for example, tissue paper or the like.
• tissue paper or the like Paper and pulp, various non-woven fabrics (spunbond non-woven fabric, melt blown non-woven fabric, thermal bond non-woven fabric, needle punch non-woven fabric, spunlace non-woven fabric, air-laid non-woven fabric, etc.), and the like. These may be subjected to water solubilization treatment, hydrolyzability treatment, hydrophilization treatment, and pore opening treatment, if necessary.
• polymers such as polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyurethane, polylactic acid, starch, cellulose, polyoxyalkylene, polyethylene, polypropylene, and polyethylene terephthalate may be used alone or in combination. ..
• An absorbent article having the absorbent material is a more preferable embodiment.
• the absorbent article is suitably used for hygiene, daily necessities, construction / civil engineering, industrial use, agricultural use, medical use, food use and the like.
• the absorbent article is a hygienic absorbent article such as a paper diaper, a urine pad, a sanitary napkin, a breast milk pad, an incontinence pad, a sweat band, a water-soluble sanitary material; a gel fragrance, a disposable cairo material, a cat.
• Absorbent articles such as soil water retention agents, seedling raising sheets, seed coatings, sustained-release fertilizers, pesticide / fertilizer disintegration aids; moisturizers, wound protection dressing materials, waste blood solidifying agents, medical care Medical absorbent articles such as underpads, spreading agents, and body fluid absorbents; preferably used as food absorbent articles such as ice packs and freshness preservatives.
• An absorbent article having an absorbent material composed of water-soluble and water-decomposable components can easily dispose of, for example, the absorbent article itself or the absorbent portion desorbed from the absorbent article in water after absorbing body fluid. Therefore, the absorbent article can be suitably used as a sanitary material that can be flushed with water without pretreatment such as crushing.
• a block copolymer having excellent biodegradability By using a block copolymer having excellent biodegradability, it can be decomposed by activated sludge and can be disposed of in sewage. In addition, it is possible to control the release of an absorbent material that absorbs and retains components such as detergents, pesticides, and fertilizers by using the amount of water as a trigger.
• the polymer block (b) is formed by saponifying the vinyl ester polymer block (b1) in the vinyl ester block copolymer. Since the number average degree of polymerization DP b of the polymer does not change substantially before and after the saponification, the number average degree of polymerization obtained from the results of GPC measurement of the polymer before saponification is used as the number average degree of polymerization DP of the polymer block (b). It was designated as b . Similarly, the number average degree of polymerization obtained from the results of GPC measurement of the polymer after the polymerization was stopped and before the saponification was defined as the number average degree of polymerization DP A of the copolymer (A).
• the vinyl ester polymer block (b1) is a block (b1) obtained by polymerizing a vinyl ester in the absence of an ionic monomer such as an acrylic acid ester, and is used at the initial stage of polymerization or during polymerization. After polymerizing the vinyl ester in the presence of the ionic monomer to obtain a copolymer block (c1) containing the vinyl ester monomer unit and the ionic monomer unit, the ionic monomer becomes the vinyl ester.
• the vinyl ester-based monomer is polymerized in a state where the molar ratio (ionic monomer / vinyl ester) of the ionic monomer to the vinyl ester in the reaction solution is 0.00001 or less. Refers to the obtained block (b1).
• the content of the ionic monomer unit contained in the vinyl ester polymer block (b1) formed in a state where the molar ratio (ionic monomer / vinyl ester) is 0.0001 or less is 0.1. Less than mol%.
• the number average degree of polymerization (DP) of the sampled polymer is the number average molecular weight Mn of the polymer obtained by GPC and 1 H-NMR, and the content (U) (mol%) of the acrylic acid-based monomer unit.
• the molecular weights of the acrylic acid ester monomer unit and the vinyl ester monomer unit (MA: 86, VAc: 86) were calculated by the following formulas.
• (DP) Mn / ⁇ (U / 100) ⁇ 86 + [(100-U) / 100] ⁇ 86 ⁇
• the number average degree of polymerization DP A of the copolymer (A) was determined by the above formula using the values obtained by GPC and 1 H-NMR of the vinyl ester block copolymer after the polymerization was stopped.
• a vinyl ester-based polymer block was obtained at the beginning of polymerization, the polymer sampled immediately before the addition of the ionic monomer was measured to determine the number average degree of polymerization DP b of the polymer block (b).
• a vinyl ester-based polymer block is obtained after copolymerization of an acrylic acid ester and a vinyl ester, the polymer sampled at the time point as the boundary of the block and the vinyl ester-based block copolymer after the polymerization is stopped are measured. From the difference in the number average degree of polymerization obtained in the above process, the number average degree of polymerization DP b of the polymer block (b) was obtained.
• the copolymer was washed with methanol to remove salts, and then dried under reduced pressure at 90 ° C. for 2 days. In this way, a polymer obtained by heat-treating in an acidic aqueous solution and then drying was obtained.
• a nuclear magnetic resonance apparatus "LAMBDA 500" manufactured by JEOL Ltd.
• 1 H-NMR measurement of the copolymer was performed at 40 ° C and 95 ° C. rice field.
• DMSO-d6 was used as the solvent.
• the content of acrylic acid monomer units relative to all the monomer units in the copolymer (A) (Z A) (mol%) was calculated as follows.
• Y Integral value of peak derived from side chain proton (-CH 2 CH (COOH)-) of acrylic acid (broad peak detected in the range of 11.0 to 13.0 ppm)
• X the backbone of the methine of the lactone ring in the acrylic acid (-CH 2 C H (R 1 ) CH 2 CH (R 2) -)
• R 1 -R 2 peak here resulting from the formation of bond with each other -R 1 -R 2- means the -CO-O- structure) total integral value (double peak of 2.6 ppm to 3.0 ppm).
• Biodegradation rate (%) ⁇ (FG) / H ⁇ ⁇ 100
• the polymerization induction period for obtaining the block b was 6 hours, and the growth period from the start of increasing the degree of polymerization to the addition of the polymerization inhibitor was 4 hours.
• the vinyl ester-based block copolymer was recovered by a filtration operation and dried in a vacuum dryer at 40 ° C. for 24 hours to obtain a vinyl ester-based block copolymer.
• the details of the above polymerization steps are shown in Table 1.
• ⁇ Salt formation process 46.5 parts by mass of sodium hydroxide, 2000 parts by mass of dehydrated methanol and 210 parts by mass of ion-exchanged water were added to the saponified product obtained by deflation, and heating was continued at 65 ° C. for another 1 hour. After the liquid was removed, a phenolphthalein solution was added to the washing solution (methanol), and the mixture was washed with methanol until no alkaline reaction was observed to remove sodium hydroxide and sodium acetate. The solid obtained by centrifugal dehydration was dried at 40 ° C. for 24 hours in a vacuum dryer to obtain the desired copolymer (A) (binary block copolymer of block b-block c).
• Example 2 Copolymer (A) (binary block co-weight of block b-block c) in the same manner as in Example 1 except that [Synthesis of block c] in ⁇ Polymerization step> in Example 1 was changed as shown in Table 1. Combined) was obtained. The evaluation results of the obtained copolymer (A) are shown in Table 2.
• the polymerization induction period for obtaining the block b was 6 hours, and the growth period from the start of increasing the degree of polymerization to the addition of the banning agent was 3 hours.
• Copolymer (A) (binary block co-weight of block b-block c) in the same manner as in Example 3 except that [Synthesis of block c] in ⁇ Polymerization step> in Example 3 was changed as shown in Table 1. Combined) was obtained. The evaluation results of the obtained copolymer (A) are shown in Table 2.
• Example 5 The target copolymer (A) (block b-block c 2) is the same as in Example 3 except that [Synthesis of block c] in ⁇ Polymerization step> in Example 3 is changed as shown in Table 1. Original block copolymer) was obtained. The evaluation results of the obtained copolymer (A) are shown in Table 2.
• Example 6 The desired copolymer was obtained in the same manner as in Example 3 except that the changes were made as shown in Table 1 in [Synthesis of block b] and [Synthesis of block c] of ⁇ Polymerization step> in Example 3. .. The evaluation results of the obtained copolymer are shown in Table 2.
• Example 6 in the procedure corresponding to [Synthesis of block c], the polymerization was continuously carried out even after the MA of the comonomer was completely consumed, and then the polymerization inhibitor was added. Therefore, the finally obtained copolymer becomes a triblock called block b-block c-block b.
• Example 7 In the ⁇ copolymerization step> in Example 1, the object was the same as in Example 1 except that 46.5 parts by mass of calcium hydroxide was used instead of 46.5 parts by mass of sodium hydroxide as shown in Table 1.
• a copolymer (A) (a binary block copolymer of block b-block c) was obtained. The evaluation results of the obtained copolymer are shown in Table 2.
• Polymerization was carried out while feeding the MA40% by mass methanol solution over time, sampling was performed as appropriate, the progress of the polymerization was confirmed from the solid content concentration, and when the total conversion of VAc and MA reached 35% by mass, p-benzoquinone was used. 0.15 parts by mass was added to terminate the polymerization. The total feed amount of MA fed over time at this point was equivalent to 11.4 parts by mass (corresponding to the feed of additional monomers in Table 1).
• the polymerization induction period for obtaining the block c was 0 hours, and the growth period from the start of increasing the degree of polymerization to the addition of the banning agent was 3 hours.
• Example 2 The ⁇ saponification step> in Example 3 was changed as follows. To 100 parts by mass of the vinyl ester block copolymer obtained in the ⁇ polymerization step> of Example 3, 46.5 parts by mass of acetic acid and 2000 parts by mass of methanol were added and heated at 65 ° C. for 1 hour. After the liquid was removed, the solid was washed with methanol and dehydrated by centrifugation and dried in a vacuum dryer at 40 ° C. for 24 hours to obtain the desired block copolymer. ⁇ Salt formation step> was not performed. The results of measurement and evaluation of the obtained block copolymer are summarized in Table 2.
• Example 3 The copolymer (A) (block b-block) is the same as in Example 1 except that [Synthesis of block b] and [Synthesis of block c] of ⁇ Polymerization step> in Example 1 are changed as shown in Table 1. A binary block copolymer of c) was obtained. The evaluation results of the obtained copolymer (A) are shown in Table 2.
• Table 2 summarizes the results of evaluations carried out using a chemically crosslinked polyacrylic acid-based highly water-absorbent resin [Sumitomo Seika Chemical Co., Ltd., trade name: Aquakeep SA60S].
• the induction period until block b polymerization was 5 hours, and the growth period until the addition of the prohibitive agent was 4 hours.
• the block copolymers (A) of Examples 1 to 7 were excellent in absorption of DIW and saline and retention of saline (gel shape retention), and also excellent in water solubility (water solubility). Although only Example 6 has been measured for the biodegradation rate, it is considered that all of Examples 1 to 8 show the same good biodegradation rate.
• the copolymer of Comparative Example 1 is a random copolymer having no block (b) and block (c).
• the copolymer of Comparative Example 2 has a block (b) but does not have an ionic polymer block (c) containing a monomer unit having an ionic group forming a salt. It is a coalescence.
• the copolymer of Comparative Example 3 is a copolymer having Mn A of less than 20,000 and Mn b of less than 15,000.
• the copolymer of Comparative Example 5 is a copolymer in which the vinyl alcohol-based monomer unit is not contained in the ionic polymer block (c).
• the copolymers of Comparative Examples 1 to 3 and 5 did not have sufficient absorbability and saline retention of DIW and saline.
• the copolymer of Comparative Example 2 was also inferior in water solubility.
• the polyacrylic acid-based highly water-absorbent resin of Comparative Example 4 does not have a block (b), and although it is excellent in water absorption performance and the like, it is inferior in water solubility (water solubility) and biodegrades. The rate was also bad.

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