JP5561953B2 - Process for producing polycarboxylic acid copolymer - Google Patents

Description

  The present invention relates to a method for producing a polycarboxylic acid copolymer. Specifically, the present invention relates to a method for producing a polycarboxylic acid copolymer suitable for a cement admixture.

  Cement admixtures are widely used in cement compositions such as cement paste, mortar and concrete.

  When the cement admixture is used, the fluidity of the cement composition can be increased, and the cement composition can be reduced in water. This water reduction can improve the strength and durability of the cured product.

  In recent years, cement admixtures composed mainly of polycarboxylic acid copolymers have been proposed as cement admixtures. A cement admixture mainly composed of a polycarboxylic acid copolymer (polycarboxylic acid cement admixture) can exhibit high water reduction performance.

  Structural units derived from unsaturated polyalkylene glycol ether monomers and structures derived from unsaturated carboxylic monomers as polycarboxylic acid copolymers that can exhibit high water reduction performance when used in cement admixtures Polycarboxylic acid copolymers containing units are known (see Patent Documents 1 to 9).

  However, the unsaturated polyalkylene glycol ether monomer has a problem that the copolymerizability is lower than that of the corresponding ester monomer, for example. Therefore, when producing a polycarboxylic acid-based copolymer comprising a structural unit derived from an unsaturated polyalkylene glycol ether monomer and a structural unit derived from an unsaturated carboxylic acid monomer, the desired copolymer is produced. When trying to obtain a polycarboxylic acid-based copolymer having a proportion, there is a problem that it is not obtained at all, and even if it is obtained, the purity of the polymer is lowered and the quality of the polymer is deteriorated. This may cause problems such as the need for polymerization and an increase in production cost.

  In addition, it has been reported so far to produce a polycarboxylic acid copolymer comprising a structural unit derived from an unsaturated polyalkylene glycol ether monomer and a structural unit derived from an unsaturated carboxylic acid monomer. In the copolymerization method, sufficient copolymerizability cannot be easily expressed for the unsaturated polyalkylene glycol ether monomer. Therefore, when producing a polycarboxylic acid copolymer comprising a structural unit derived from an unsaturated polyalkylene glycol ether monomer and a structural unit derived from an unsaturated carboxylic acid monomer, an unsaturated polyalkylene glycol is produced. If a technology capable of easily expressing sufficient copolymerizability for an ether-based monomer can be developed, it is possible not only to reduce the production cost of the copolymer, but also to provide an unprecedented high-performance cement admixture. There is a possibility that a carboxylic acid copolymer can be produced.

JP 2001-220417 A JP 2007-119337 A International Publication No. 01/014438 Pamphlet International Publication No. 2003/040194 Pamphlet JP 2006-248889 A JP 2007-327067 A International Publication No. 2006/129883 Pamphlet JP 2001-220417 A JP 2002-121055 A

  An object of the present invention is a method for producing a polycarboxylic acid copolymer comprising a structural unit derived from an unsaturated polyalkylene glycol ether monomer and a structural unit derived from an unsaturated carboxylic acid monomer. Another object of the present invention is to provide a method for producing a polycarboxylic acid copolymer, which can reduce the production cost of the copolymer and can provide an unprecedented high-performance cement admixture.

（一般式（１）中、Ｙは炭素数２〜８のアルケニル基を表す。Ｔは、同一または異なって、炭素数１〜５のアルキレン基または炭素数６〜９のアリール基を表す。Ｒ^１Ｏは炭素数２〜１８のオキシアルキレン基の１種または２種以上を表す。ｍは０または１を表す。ｎはオキシアルキレン基の平均付加モル数であり、ｎは１〜５００である。Ｒ^２は水素原子または炭素数１〜５のアルキル基を表す。）

（一般式（２）中、Ｒ^３、Ｒ^４、Ｒ^５は、同一または異なって、水素原子、メチル基、または−ＣＯＯＭ基を表す。Ｍは、水素原子、一価金属原子、二価金属原子、アンモニウム基、または有機アミン基を表す。） The method for producing the polycarboxylic acid copolymer of the present invention comprises:
Structural unit (I) derived from unsaturated polyalkylene glycol ether monomer (a) represented by general formula (1) and unsaturated carboxylic acid monomer (b) represented by general formula (2) A method for producing a polycarboxylic acid-based copolymer containing the derived structural unit (II),
Polymerization of the monomer component containing the monomer (a) and the monomer (b) is being performed in the presence of a pH adjuster using a peroxide and a reducing agent in combination as a polymerization initiator. The pH is controlled to 3 or less.

(In General Formula (1), Y represents an alkenyl group having 2 to 8 carbon atoms. T is the same or different and represents an alkylene group having 1 to 5 carbon atoms or an aryl group having 6 to 9 carbon atoms. ¹ O represents one or more oxyalkylene groups having 2 to 18 carbon atoms, m represents 0 or 1, n represents the average number of moles added of the oxyalkylene group, and n is 1 to 500. R ² represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)

(In General Formula (2), R ³ , R ⁴ , and R ⁵ are the same or different and each represents a hydrogen atom, a methyl group, or a —COOM group. M represents a hydrogen atom, a monovalent metal atom, or a divalent metal. Represents an atom, an ammonium group, or an organic amine group.)

  In a preferred embodiment, the pH adjuster is an organic sulfonic acid and / or a salt thereof.

  In a preferred embodiment, the peroxide is hydrogen peroxide and the reducing agent is L-ascorbic acid.

  In a preferred embodiment, the copolymer is a cement admixture copolymer.

  According to the present invention, there is provided a method for producing a polycarboxylic acid copolymer comprising a structural unit derived from an unsaturated polyalkylene glycol ether monomer and a structural unit derived from an unsaturated carboxylic acid monomer. Another object of the present invention is to provide a method for producing a polycarboxylic acid copolymer, which can reduce the production cost of the copolymer and can provide an unprecedented high-performance cement admixture.

The method for producing the polycarboxylic acid copolymer of the present invention comprises:
The structural unit (I) derived from the unsaturated polyalkylene glycol ether monomer (a) represented by the general formula (1) and the unsaturated carboxylic acid monomer represented by the general formula (2) ( This is a method for producing a polycarboxylic acid-based copolymer containing the structural unit (II) derived from b). In the present invention, the unsaturated polyalkylene glycol ether monomer (a) may be used alone or in combination of two or more. In the present invention, the unsaturated carboxylic acid monomer (b) may be used alone or in combination of two or more.

  The total content of the structural unit (I) and the structural unit (II) in the polycarboxylic acid copolymer obtained by the production method of the present invention is preferably 10 to 100% by mass, more preferably It is 20-100 mass%, More preferably, it is 30-100 mass%. If the total content of the structural unit (I) and the structural unit (II) in the polycarboxylic acid copolymer obtained by the production method of the present invention is within the above range, a high-performance cement admixture It is possible to provide a polycarboxylic acid copolymer that can provide

  The content ratio of the structural unit (I) in the polycarboxylic acid copolymer obtained by the production method of the present invention is preferably 10 to 99% by mass, more preferably 20 to 99% by mass, and still more preferably 30. It is -99 mass%. If the content of the structural unit (I) in the polycarboxylic acid copolymer obtained by the production method of the present invention is within the above range, the polycarboxylic acid copolymer can provide a high-performance cement admixture. Coalescence can be provided.

  The content ratio of the structural unit (II) in the polycarboxylic acid copolymer obtained by the production method of the present invention is preferably 1 to 90% by mass, more preferably 1 to 80% by mass, and still more preferably 1 -70 mass%. If the content ratio of the structural unit (II) in the polycarboxylic acid copolymer obtained by the production method of the present invention is within the above range, the polycarboxylic acid copolymer can provide a high-performance cement admixture. Coalescence can be provided.

  In general formula (1), Y represents an alkenyl group having 2 to 8 carbon atoms. Y is preferably an alkenyl group having 2 to 5 carbon atoms. Examples of Y include a vinyl group, allyl group, methallyl group, 3-butenyl group, 3-methyl-3-butenyl group, 3-methyl-2-butenyl group, 2-methyl-3-butenyl group, and 2-methyl. -2-butenyl group and 1,1-dimethyl-2-propenyl group. Among these, an allyl group, a methallyl group, and a 3-methyl-3-butenyl group are preferable.

  In general formula (1), T is the same or different and represents an alkylene group having 1 to 5 carbon atoms or an aryl group having 6 to 9 carbon atoms.

  In general formula (1), m represents 0 or 1.

In general formula (1), R ¹ O represents one or more of oxyalkylene groups having 2 to 18 carbon atoms. R ¹ O is preferably one or more types of oxyalkylene groups having 2 to 8 carbon atoms, and more preferably one or more types of oxyalkylene groups having 2 to 4 carbon atoms. Examples of R ¹ O include an oxyethylene group, an oxypropylene group, an oxybutylene group, and an oxystyrene group. Examples of the addition format of R ¹ O include random addition, block addition, and alternate addition. In order to secure a balance between hydrophilicity and hydrophobicity, it is preferable that an oxyethylene group contains an oxyethylene group as an essential component. More specifically, 50 mol% or more is more preferably an oxyethylene group, and more preferably 90 mol% or more is an oxyethylene group with respect to 100 mol% of all oxyalkylene groups.

  In general formula (1), n is the average addition mole number of an oxyalkylene group, and n is 1-500. n is preferably 2 to 300, more preferably 5 to 300, still more preferably 10 to 300, particularly preferably 15 to 300, and most preferably 20 to 300. The smaller n is, the lower the hydrophilicity of the resulting polymer and the lower the dispersion performance. When n exceeds 500, copolymerization reactivity may be reduced.

In general formula (1), R ² represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

In the general formula ^{(2), R 3, R} 4, R 5 are the same or different, represent a hydrogen atom, a methyl group or a -COOM group.

  M represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group, or an organic amine group.

  Any appropriate monovalent metal atom can be adopted as the monovalent metal atom. For example, lithium, sodium, and potassium are mentioned.

  Any appropriate divalent metal atom can be adopted as the divalent metal atom. Examples thereof include divalent metal atoms such as alkaline earth metal atoms such as calcium and magnesium.

  As the organic amine group, any appropriate organic amine group can be adopted as long as it is a protonated organic amine. Examples of the organic amine group include alkanolamine groups such as ethanolamine group, diethanolamine group, and triethanolamine group, and triethylamine group.

  Examples of the unsaturated polyalkylene glycol ether monomer (a) include 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-3-butene- Examples thereof include compounds obtained by adding 1 to 500 mol of alkylene oxide to unsaturated alcohols such as 2-ol, 2-methyl-2-buten-1-ol, and 2-methyl-3-buten-1-ol.

  Specific examples of the unsaturated polyalkylene glycol ether monomer (a) include polyethylene glycol mono (3-methyl-3-butenyl) ether and polyethylene glycol mono (3-methyl-2-butenyl) ether. Polyethylene glycol mono (2-methyl-3-butenyl) ether, polyethylene glycol mono (2-methyl-2-butenyl) ether, polyethylene glycol mono (1,1-dimethyl-2-propenyl) ether, polyethylene polypropylene glycol mono ( 3-methyl-3-butenyl) ether, methoxypolyethylene glycol mono (3-methyl-3-butenyl) ether, ethoxypolyethyleneglycol mono (3-methyl-3-butenyl) ether, 1-propoxypolyethyleneglycol Mono (3-methyl-3-butenyl) ether, cyclohexyloxypolyethyleneglycol mono (3-methyl-3-butenyl) ether, 1-octyloxypolyethyleneglycolmono (3-methyl-3-butenyl) ether, nonylalkoxypolyethyleneglycol Mono (3-methyl-3-butenyl) ether, laurylalkoxypolyethyleneglycolmono (3-methyl-3-butenyl) ether, stearylalkoxypolyethyleneglycolmono (3-methyl-3-butenyl) ether, phenoxypolyethyleneglycolmono (3- Methyl-3-butenyl) ether and naphthoxypolyethylene glycol mono (3-methyl-3-butenyl) ether.

  Examples of the unsaturated carboxylic acid monomer (b) include an unsaturated monocarboxylic acid monomer (b-1) and an unsaturated dicarboxylic acid monomer (b-2). The unsaturated carboxylic acid monomer (b) is preferably an unsaturated monocarboxylic acid monomer (b-1).

  Any appropriate unsaturated monocarboxylic acid monomer can be adopted as the unsaturated monocarboxylic acid monomer (b-1). The unsaturated monocarboxylic acid monomer (b-1) is preferably a (meth) acrylic acid monomer. Specific examples include acrylic acid, methacrylic acid, crotonic acid, and monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts thereof. From the viewpoint of copolymerization, the unsaturated monocarboxylic acid monomer (b-1) is more preferably (meth) acrylic acid and / or a salt thereof (monovalent metal salt, divalent metal salt, Ammonium salts, organic amine salts, and the like, and more preferably acrylic acid and / or salts thereof (monovalent metal salts, divalent metal salts, ammonium salts, organic amine salts, etc.).

  Any appropriate unsaturated dicarboxylic acid monomer can be adopted as the unsaturated dicarboxylic acid monomer (b-2). Specific examples of the unsaturated dicarboxylic acid monomer (b-2) include maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid, and monovalent metal salts and divalent metals thereof. Mention may be made of salts, ammonium salts and organic amine salts. As the unsaturated dicarboxylic acid monomer (b-2), maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid, and salts thereof (monovalent metal salt, divalent metal salt, Ammonium salts, organic amine salts, etc., more preferably maleic acid, maleic anhydride, fumaric acid, citraconic acid, and salts thereof (monovalent metal salts, divalent metal salts, ammonium salts, organic amine salts) Α, β-unsaturated dicarboxylic acid-based monomer.

  In producing the polycarboxylic acid copolymer in the present invention, the monomer component used for the polymerization is other than the unsaturated polyalkylene glycol ether monomer (a) and the unsaturated carboxylic acid monomer (b). Further, any appropriate monomer (a) and another monomer (c) copolymerizable with the monomer (b) may be included. Other monomers (c) may be used alone or in combination of two or more.

  Specific examples of the other monomer (c) include, for example, half esters and diesters of the unsaturated dicarboxylic acid monomer (b-2) and an alcohol having 1 to 30 carbon atoms; Half amide and diamide of unsaturated dicarboxylic acid monomer (b-2) and amine having 1 to 30 carbon atoms; alkyl (poly) alkylene glycol and unsaturated dicarboxylic acid monomer (b-2) ) And half esters and diesters; a half of the unsaturated dicarboxylic acid monomer (b-2) and a glycol having 2 to 18 carbon atoms or a polyalkylene glycol having 2 to 500 addition moles of these glycols Esters, diesters; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, glycidyl (meth) acrylate, methyl Esters of unsaturated monocarboxylic acid monomers (b-1) such as rotonate, ethyl crotonate, propyl crotonate and the like and alcohols having 1 to 30 carbon atoms; alcohols having 1 to 30 carbon atoms and 2 carbon atoms Esters of an alkoxy (poly) alkylene glycol to which 1 to 500 moles of alkylene oxide of -18 are added and an unsaturated monocarboxylic acid monomer (b-1) such as (meth) acrylic acid; (poly) ethylene 2 to 2 carbon atoms in unsaturated monocarboxylic acid monomer (b-1) such as (meth) acrylic acid such as glycol monomethacrylate, (poly) propylene glycol monomethacrylate, (poly) butylene glycol monomethacrylate, etc. 1-500 mole adducts of 18 alkylene oxides; maleamic acid and glycols having 2-18 carbon atoms Or half amides of these glycols with polyalkylene glycol having an addition mole number of 2 to 500; triethylene glycol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, (Poly) ethylene glycol (poly) propylene glycol di (meth) acrylate and other (poly) alkylene glycol di (meth) acrylates; hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropanedi Bifunctional (meth) acrylates such as (meth) acrylate; (poly) alkylene glycol dimaleates such as triethylene glycol dimaleate and polyethylene glycol dimaleate; vinyl sulfonate, (Meth) allyl sulfonate, 2- (meth) acryloxyethyl sulfonate, 3- (meth) acryloxypropyl sulfonate, 3- (meth) acryloxy-2-hydroxypropyl sulfonate, 3- (meth) acryloxy-2-hydroxypropyl Sulfophenyl ether, 3- (meth) acryloxy-2-hydroxypropyloxysulfobenzoate, 4- (meth) acryloxybutyl sulfonate, (meth) acrylamidomethylsulfonic acid, (meth) acrylamidoethylsulfonic acid, 2-methylpropanesulfone Unsaturated sulfonic acids such as acid (meth) acrylamide and styrene sulfonic acid, and monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts thereof; unsaturated monocarboxylic acids such as methyl (meth) acrylamide Amides of monomer (b-1) and amines having 1 to 30 carbon atoms; vinyl aromatics such as styrene, α-methylstyrene, vinyltoluene, p-methylstyrene; 1,4-butanediol mono Alkanediol mono (meth) acrylates such as (meth) acrylate, 1,5-pentanediol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate; butadiene, isoprene, 2-methyl-1,3 -Dienes such as butadiene and 2-chloro-1,3-butadiene; Unsaturation such as (meth) acrylamide, (meth) acrylalkylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, etc. Amides; Unsaturated cyanides such as (meth) acrylonitrile and α-chloroacrylonitrile; Vinyl acetate And unsaturated esters such as vinyl propionate; aminoethyl (meth) acrylate, methylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, (meth) Unsaturated amines such as dibutylaminoethyl acrylate and vinyl pyridine; divinyl aromatics such as divinylbenzene; cyanurates such as triallyl cyanurate; allyls such as (meth) allyl alcohol and glycidyl (meth) allyl ether; Unsaturated amino compounds such as dimethylaminoethyl (meth) acrylate; methoxypolyethylene glycol monovinyl ether, polyethylene glycol monovinyl ether, methoxypolyethylene glycol mono (meth) allyl ether, polyethylene glycol mono Vinyl ethers or allyl ethers such as (meth) allyl ether; polydimethylsiloxanepropylaminomaleamic acid, polydimethylsiloxaneaminopropylaminoaminomaleamic acid, polydimethylsiloxane-bis- (propylaminomaleamic acid), polydimethylsiloxane- Bis- (dipropylaminomaleamic acid), polydimethylsiloxane- (1-propyl-3-acrylate), polydimethylsiloxane- (1-propyl-3-methacrylate), polydimethylsiloxane-bis- (1-propyl- 3-acrylate), siloxane derivatives such as polydimethylsiloxane-bis- (1-propyl-3-methacrylate); and the like.

  In the method for producing a polycarboxylic acid copolymer of the present invention, polymerization of a monomer component containing the monomer (a) and the monomer (b) is started, and polymerization of a peroxide and a reducing agent is started. In combination with the agent, the pH during polymerization is controlled to 3 or less in the presence of a pH adjuster.

  The polymerization of the monomer component can be performed by any appropriate method. Examples thereof include solution polymerization and bulk polymerization. Examples of the solution polymerization method include a batch method and a continuous method. Solvents that can be used for solution polymerization include water; alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane, and n-hexane; esters such as ethyl acetate. Compounds; ketone compounds such as acetone and methyl ethyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane; and the like.

  In the polymerization of the monomer component, a chain transfer agent can be used. When a chain transfer agent is used, the molecular weight of the resulting copolymer can be easily adjusted.

  Any appropriate chain transfer agent can be adopted as the chain transfer agent. Specifically, for example, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionate, 2-mercaptoethanesulfonic acid Thiol chain transfer agents such as n-dodecyl mercaptan, octyl mercaptan, butyl thioglycolate; halides such as carbon tetrachloride, methylene chloride, bromoform, bromotrichloroethane; secondary alcohols such as isopropanol; phosphorous acid, next Phosphorous acid and its salts (sodium hypophosphite, potassium hypophosphite, etc.), sulfurous acid, hydrogen sulfite, dithionic acid, metabisulfite, and salts thereof (sodium sulfite, potassium sulfite, sodium hydrogen sulfite) , Sulfite water Potassium, sodium dithionite, potassium dithionite, sodium metabisulfite, meta lower oxides of potassium metabisulfite and the like) and salts thereof; and the like.

  In the production method of the present invention, a peroxide and a reducing agent are used in combination as a polymerization initiator.

  Any appropriate peroxide can be adopted as the peroxide. For example, persulfates such as ammonium persulfate, sodium persulfate and potassium persulfate; hydrogen peroxide; peroxides such as benzoyl peroxide, lauroyl peroxide, sodium peroxide, t-butyl hydroperoxide, cumene hydroperoxide; Etc.

Any appropriate reducing agent can be adopted as the reducing agent. For example, salts of metals in a low valence state such as iron (II), tin (II), titanium (III), chromium (II), V (II), Cu (II), etc. Amine compounds such as monoethanolamine, diethanolamine, triethanolamine, hydroxylamine, hydroxylamine hydrochloride, hydrazine and their salts; sodium dithionite, sodium formaldehyde sulfoxylate, sodium hydroxymethanesulfinate dihydrate; Organic compounds containing —SH group, —SO ₂ H group, —NHNH ₂ group, —COCH (OH) — group and salts thereof; alkali metal sulfites such as sodium sulfite, sodium bisulfite, metabisulfite; Phosphoric acid, sodium hypophosphite, sodium hydrosulfite, sodium hyponitrite Lower oxides such as D-fructose, D-glucose, etc .; thiourea compounds such as thiourea and thiourea dioxide; L-ascorbic acid (salt), L-ascorbic acid ester, erythorbic acid (salt), Erythorbic acid ester; and the like.

  The combination of the peroxide and the reducing agent is preferably a combination of a water-soluble peroxide and a reducing agent, such as a combination of hydrogen peroxide and L-ascorbic acid, hydrogen peroxide and erythorbic acid, and the like. A combination of hydrogen peroxide and a mole salt, and a combination of sodium persulfate and sodium bisulfite. A particularly preferable combination is a combination of hydrogen peroxide and L-ascorbic acid in that the effects of the present invention can be expressed more effectively.

  The amount of the peroxide used is preferably 0.01 to 30 mol%, more preferably 0.1 to 20 mol%, still more preferably 0.5 to 10 mol, based on the total amount of the monomer components. %. There exists a possibility that an unreacted monomer may increase that the usage-amount of the said peroxide is less than 0.01 mol% with respect to the total amount of a monomer component. When the amount of the peroxide used exceeds 30 mol% with respect to the total amount of the monomer components, a polycarboxylic acid having a large amount of oligomers may be obtained.

  The amount of the reducing agent used is preferably 0.1 to 500 mol%, more preferably 1 to 200 mol%, still more preferably 10 to 100 mol%, based on the peroxide. When the amount of the reducing agent used is less than 0.1 mol% with respect to the peroxide, active radicals are not sufficiently generated, and the amount of unreacted monomers may increase. When the amount of the reducing agent used exceeds 500 mol% with respect to the peroxide, there is a risk that the reducing agent remaining without reacting with hydrogen peroxide will increase.

  In the polymerization of the monomer component, it is preferable that at least one of the peroxide and the reducing agent is always present in the reaction system. Specifically, it is preferable that the peroxide and the reducing agent are not added simultaneously. If peroxide and reducing agent are simultaneously added at once, the peroxide and reducing agent react rapidly, generating a large amount of reaction heat immediately after the addition, making reaction control difficult, and then radical concentration Therefore, a large amount of unreacted monomer components may remain. Furthermore, the radical concentration with respect to the monomer component is extremely different between the initial and second half of the reaction, so the molecular weight distribution becomes extremely large, and the performance when the resulting copolymer is used as a cement admixture may be reduced. There is. Therefore, for example, it is preferable to employ a method in which both the peroxide and the reducing agent are added over a long period of time, such as a method of continuously adding them by dropping or the like, or a method of adding them separately. The time from when one of the peroxide and the reducing agent is charged to when the other is started is preferably within 5 hours, more preferably within 3 hours.

  The polymerization reaction temperature is preferably 30 to 90 ° C, more preferably 35 to 85 ° C, and further preferably 40 to 80 ° C. If the polymerization reaction temperature is out of the above range, the polymerization rate may be lowered or the productivity may be lowered.

  The polymerization time is preferably 0.5 to 10 hours, more preferably 0.5 to 8 hours, and further preferably 1 to 6 hours. If the polymerization time is out of the above range, the polymerization rate may be lowered or the productivity may be lowered.

  Any appropriate method can be adopted as a method of charging the monomer component into the reaction vessel. For example, a method in which the entire amount is initially charged into the reaction vessel, a method in which the entire amount is divided or continuously charged into the reaction vessel, a method in which a part is initially charged in the reaction vessel and the remainder is divided or continuously charged into the reaction vessel, etc. Can be mentioned. Specifically, a method in which the total amount of monomer (a) and the total amount of monomer (b) are continuously charged into the reaction vessel, a part of monomer (a) is initially charged into the reaction vessel, A method in which the remainder of the monomer (a) and the entire amount of the monomer (b) are continuously charged into the reaction vessel, a part of the monomer (a) and a part of the monomer (b) in the reaction vessel In the initial stage, and the remainder of the monomer (a) and the remainder of the monomer (b) are alternately charged into the reaction vessel in several batches. Furthermore, by changing the charging rate of each monomer into the reaction vessel during the reaction continuously or stepwise, the charging mass ratio per unit time of each monomer is changed continuously or stepwise, You may make it synthesize | combine simultaneously the 2 or more types of copolymer from which the ratio of structural unit (I) and structural unit (II) differs.

  In the production method of the present invention, the polymerization of the monomer components is carried out in the presence of a pH adjuster while controlling the pH during the polymerization to 3 or less. Preferably, the polymerization is carried out while controlling the pH at 2-3. Sufficient copolymerization of unsaturated polyalkylene glycol ether monomers can be easily expressed by performing polymerization of the above monomer components in the presence of a pH adjuster while controlling the pH during polymerization to 3 or less. Thus, the production cost of the polycarboxylic acid copolymer to be produced can be reduced, and a polycarboxylic acid copolymer that can provide an unprecedented high-performance cement admixture can be produced.

  Examples of the pH adjuster include phosphoric acid and / or a salt thereof, organic sulfonic acid and / or a salt thereof, hydrochloric acid and / or a salt thereof, nitric acid and / or a salt thereof, sulfuric acid and / or a salt thereof. Among these, at least one selected from phosphoric acid and / or a salt thereof and organic sulfonic acid and / or a salt thereof is preferable, and an organic sulfonic acid and / or a salt thereof is more preferable in that the addition amount can be reduced.

  Any appropriate salt can be adopted as the salt. Examples thereof include alkali metal salts, alkaline earth metal salts, ammonium salts, and organic ammonium salts. Only 1 type of pH adjuster may be used and it may use 2 or more types together.

  Specific examples of the organic sulfonic acid and / or salt thereof include p-toluenesulfonic acid and / or a hydrate thereof, methanesulfonic acid and / or a salt thereof, and the like.

  The amount of the pH adjuster used is preferably 0.01 to 5% by mass, more preferably 0.05 to 4% by mass, and still more preferably 0.05 to 2.5% by mass, based on the total amount of the monomer components. %. If the amount of the pH adjuster used is too large, the pH during the polymerization will be too low, which may lead to inappropriate polymerization conditions. Moreover, the ratio of the usage-amount of the pH adjuster with respect to the total amount of said monomer component is substantially the same as the mass ratio of the pH adjuster with respect to the mass of the copolymer in the composition obtained. Therefore, the mass ratio of the pH adjuster to the mass of the copolymer in the obtained composition is preferably 0.01 to 5 mass%, more preferably 0.05 to 4 mass%, and still more preferably 0.05. It is -2.5 mass%.

  In the production method of the present invention, the polymerization of the monomer component is performed in the presence of a pH adjuster while controlling the pH during the polymerization to 3 or less. After the polymerization, the pH is adjusted to any appropriate pH. good. In order to provide a high performance cement admixture, the pH is preferably adjusted to 4-7 after polymerization.

  The polycarboxylic acid copolymer obtained by the production method of the present invention has a mass average molecular weight (Mw) of preferably 10,000 to 300,000, more preferably 10,000 to 100,000, and still more preferably 10,000 to 80,000. When the mass average molecular weight (Mw) is within the above range, a high-performance cement admixture can be provided.

  The polycarboxylic acid copolymer obtained by the production method of the present invention can be suitably used as a copolymer for cement admixture.

  When the polycarboxylic acid copolymer obtained by the production method of the present invention is used as a copolymer for cement admixture, the content ratio of the polycarboxylic acid copolymer in the obtained cement admixture is preferably It is 5-100 mass%, More preferably, it is 10-100 mass%, More preferably, it is 15-100 mass%. This is because the effects of the present invention can be sufficiently exhibited.

  The cement admixture may contain any appropriate other component in addition to the polycarboxylic acid copolymer obtained by the production method of the present invention.

  The cement admixture can contain one or more kinds of any appropriate cement dispersant. When the above cement dispersant is used, the blending mass ratio of the polycarboxylic acid copolymer obtained by the production method of the present invention to the cement dispersant (cement admixture of the present invention / cement dispersant) is used. Although it is not uniquely determined by the difference in the type, blending conditions, test conditions, etc. of the cement dispersant, it is preferably 1-99 / 99-1, more preferably as a mass ratio (mass%) in terms of solid content. Is 5-95 / 95-5, more preferably 10-90 / 90-10.

  Examples of the cement dispersant that can be used in combination with the polycarboxylic acid copolymer obtained by the production method of the present invention include the following cement dispersants.

  Polyalkylaryl sulfonate system such as naphthalene sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate, anthracene sulfonic acid formaldehyde condensate; melamine formalin resin sulfonate system such as melamine sulfonic acid formaldehyde condensate; amino Aromatic aminosulfonates such as aryl sulfonic acid-phenol-formaldehyde condensates; lignin sulfonates such as lignin sulfonates and modified lignin sulfonates; polystyrene sulfonates; Various sulfonic acid-based dispersants having a sulfonic acid group.

  Polyalkylene glycol mono (meth) acrylic acid ester monomers, (meth) acrylic acid monomers, and their single amounts as described in JP-B-59-18338 and JP-A-7-223852 A copolymer obtained by polymerizing a monomer copolymerizable with a polymer; a polyether compound described in JP-A-7-53645, JP-A-8-208769, JP-A-8-208770; Various polycarboxylic acid dispersants having a (poly) oxyalkylene group and a carboxyl group in the molecule, such as a hydrophilic graft polymer obtained by graft polymerization of an unsaturated carboxylic acid monomer.

  The cement admixture may contain any appropriate cement additive (cement additive). For example, water-soluble polymer substances, polymer emulsions, curing retarders, early strengthening agents / accelerators, antifoaming agents, AE agents, waterproofing agents, rust prevention agents, crack reducing agents, swelling agents, cement wetting agents, thickening agents Agents, separation reducing agents, flocculants, drying shrinkage reducing agents, strength enhancers, self-leveling agents, coloring agents, antifungal agents and the like.

  Only one kind of cement additive (cement additive) as mentioned above may be used, or two or more kinds may be used in combination.

  The following (1) to (7) may be mentioned as particularly preferred embodiments of the cement admixture.

  (1) <1> Combination of the above cement admixture and <2> oxyalkylene-based antifoaming agent, which essentially comprises two components. Examples of the oxyalkylene-based antifoaming agent include polyoxyalkylenes, polyoxyalkylene alkyl ethers, polyoxyalkylene acetylene ethers and polyoxyalkylene alkylamines, preferably polyoxyalkylene alkylamines. . The blending mass ratio of <2> oxyalkylene-based antifoaming agent is preferably in the range of 0.01 to 20% by mass with respect to <1> the cement admixture.

  (2) A combination comprising essentially three components: <1> the cement admixture, <2> an oxyalkylene antifoaming agent, and <3> an AE agent. Examples of the oxyalkylene-based antifoaming agent include polyoxyalkylenes, polyoxyalkylene alkyl ethers, polyoxyalkylene acetylene ethers and polyoxyalkylene alkylamines, preferably polyoxyalkylene alkylamines. . The blending mass ratio of <2> oxyalkylene-based antifoaming agent is preferably in the range of 0.01 to 20% by mass with respect to <1> the cement admixture. Moreover, the blending mass ratio of <3> AE agent is preferably in the range of 0.001 to 2% by mass with respect to <1> the cement admixture.

  (3) <1> The above-mentioned cement admixture, <2> polyalkylene glycol mono (meth) acrylic acid ester having a polyoxyalkylene chain obtained by adding 2 to 300 average addition moles of an alkylene oxide having 2 to 18 carbon atoms. Copolymer obtained by polymerizing a monomer, a (meth) acrylic acid monomer, and a monomer copolymerizable with these monomers (for example, Japanese Patent Publication No. 59-18338, JP, 7-223852, A), and <3> oxyalkylene type antifoaming agent which requires three components as a combination. Examples of the oxyalkylene-based antifoaming agent include polyoxyalkylenes, polyoxyalkylene alkyl ethers, polyoxyalkylene acetylene ethers and polyoxyalkylene alkylamines, preferably polyoxyalkylene alkylamines. . The blending ratio of <1> the cement admixture and <2> copolymer is a mass ratio of <1> the cement admixture / <2> copolymer, preferably 5/95 to 95/5. More preferably, it is 10 / 90-90 / 10. The blending mass ratio of the <3> oxyalkylene-based antifoaming agent is preferably in the range of 0.01 to 20% by mass with respect to the total amount of <1> the cement admixture and <2> copolymer.

  (4) A combination comprising two components of <1> the cement admixture and <2> a sulfonic acid-based dispersant having a sulfonic acid group in the molecule. Examples of the sulfonic acid-based dispersant include aminosulfonic acid-based compounds such as lignin sulfonate, naphthalene sulfonic acid formalin condensate, melamine sulfonic acid formalin condensate, polystyrene sulfonate, and aminoaryl sulfonic acid-phenol-formaldehyde condensate. A dispersing agent is mentioned. The blending ratio of <1> the cement admixture and <2> sulfonic acid dispersant is a mass ratio of <1> the cement admixture / <2> sulfonic acid dispersant, preferably 5/95 to 95/5, more preferably 10/90 to 90/10.

  (5) A combination comprising two components, <1> the cement admixture and <2> a material separation reducing agent. Examples of the material separation reducing agent include various thickeners such as nonionic cellulose ethers, a hydrophobic substituent composed of a hydrocarbon chain having 4 to 30 carbon atoms as a partial structure, and an alkylene oxide having 2 to 18 carbon atoms. Examples thereof include compounds having a polyoxyalkylene chain added in an average addition mole number of 2 to 300. The mixing ratio of <1> the cement admixture and <2> the material separation reducing agent is a mass ratio of <1> the cement admixture / <2> the material separation reducing agent, and preferably 10/90 to 99.99. 99 / 0.01, more preferably 50/50 to 99.9 / 0.1. The cement admixture in this combination is suitable as high fluidity concrete, self-filling concrete, and self-leveling agent.

  (6) A combination of two components, <1> the cement admixture and <2> retarder. Examples of the retarder include oxycarboxylic acids such as gluconic acid (salt) and citric acid (salt), sugars such as glucose, sugar alcohols such as sorbitol, and phosphonic acids such as aminotri (methylenephosphonic acid), Oxycarboxylic acids are preferred. The mixing ratio of <1> the cement admixture and <2> retarder is the mass ratio of <1> the cement admixture / <2> retarder, and preferably 50/50 to 99.9 / 0. 1, more preferably 70/30 to 99/1.

  (7) A combination of <1> the above-mentioned cement admixture and <2> accelerator that essentially comprises two components. Examples of the accelerator include soluble calcium salts such as calcium chloride, calcium nitrite and calcium nitrate, chlorides such as iron chloride and magnesium chloride, formates such as thiosulfate, formic acid and calcium formate, and the like. The mixing ratio of <1> the cement admixture and <2> accelerator is a mass ratio of <1> the cement admixture / <2> accelerator, preferably 10/90 to 99.9 / 0. 1, more preferably 20/80 to 99/1.

  The cement admixture using the polycarboxylic acid copolymer obtained by the production method of the present invention can be used by adding to a cement composition such as cement paste, mortar or concrete.

  Any appropriate cement composition may be adopted as the cement composition. For example, what contains cement, water, an aggregate, and an antifoamer is mentioned.

  Any appropriate cement can be adopted as the cement. For example, Portland cement (ordinary, early strength, very early strength, moderate heat, sulfate-resistant and low alkali type of each), various mixed cements (blast furnace cement, silica cement, fly ash cement), white Portland cement, alumina cement, Super fast cement (1 clinker fast cement, 2 clinker fast cement, magnesium phosphate cement), grout cement, oil well cement, low exothermic cement (low exothermic blast furnace cement, fly ash mixed low exothermic blast furnace cement, belite High-content cement), ultra-high-strength cement, cement-based solidified material, and eco-cement (cement produced from one or more of municipal waste incineration ash and sewage sludge incineration ash). Further, fine powder such as blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, silica powder, limestone powder, or gypsum may be added.

  Any appropriate aggregate can be adopted as the aggregate. Examples include gravel, crushed stone, granulated slag, and recycled aggregate. In addition, refractory aggregates such as siliceous, clay, zircon, high alumina, silicon carbide, graphite, chromium, chromic, magnesia, etc. can be used.

  Any appropriate antifoaming agent can be adopted as the antifoaming agent. For example, the antifoaming agent described in paragraphs [0041] to [0042] of Japanese Patent No. 3683176 can be mentioned.

In the above cement composition, the blending amount and unit water amount per 1 m ³ of concrete are preferably 100 to 185 kg / m ³ , water / unit water amount, for example, in order to produce high durability and high strength concrete. The cement ratio is 10 to 70% by mass, more preferably the unit water amount is 120 to 175 kg / m ³ and the water / cement ratio is 20 to 65% by mass.

  The amount of the cement admixture added to the cement composition is preferably 0.01 to 10% by mass, more preferably 0.05 to 8% by mass, when the total amount of cement is 100% by mass. More preferably, it is 0.1-5 mass%. There exists a possibility that it may be inferior to the performance as a cement composition as the said addition amount is less than 0.01 mass%. If the amount added exceeds 10% by mass, the economy may be inferior.

  What is necessary is just to mix | blend said each component with arbitrary appropriate methods, and to adjust the said cement composition. For example, the method of kneading in a mixer is mentioned.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, parts and% in the examples are based on mass.

<Mass average molecular weight>
Device: Waters Alliance (2695)
Analysis software: Emper professional + GPC option manufactured by Waters Column: TSKgel guard column (inner diameter 6.0 × 40 mm) + G4000SWXL + G3000SWXL + G2000SWXL (each inner diameter 7.8 × 300 mm)
Detector: differential refractometer (RI) detector (Waters 2414), multi-wavelength visible ultraviolet (PDA) detector (Waters 2996)
Eluent: acetonitrile / sodium acetate (50 mM) ion exchange aqueous solution = 40/60 (volume%) mixed with acetic acid to adjust to pH 6.0 Flow rate: 1.0 ml / min Column / detector temperature: 40 ℃
Measurement time: 45 minutes Sample solution injection amount: 100 μl (eluent solution having a sample concentration of 0.5 mass%)
GPC standard sample: polyethylene glycol manufactured by Tosoh Corporation Mp = 272500, 219300, 107000, 50000, 24000, 11840, 6450, 4250, 1470 Calibration curve: cubic equation using Mp value of polyethylene glycol Created with

<Concrete test>
(1) Materials used Cement: Taiheiyo Cement Coarse aggregate: Ome crushed fine aggregate: Ogasayama / Chiba prefecture Kimitsu mountain sand (2) Unit amount (kg / m ³ )
W / C = 52
s / a = 49.0
Air = 45.0
Water = 166.0
Cement = 320.0
Stone = 942.0
Sand = 846
(3) Mixer used: Taiheiyo Kiko, TM55 (55 liter forced kneading bread type mixer), kneading amount 30 liters (4) Test method MA202 (Pozoris product) as an AE agent was blended in an amount of 0.0015% with respect to cement. Fine aggregate and cement were put into a mixer and kneaded for 10 seconds. Then, water containing cement admixture and coarse aggregate were added and kneaded for 90 seconds, and then the concrete was discharged. The slump value, slump flow value, and air amount of the obtained concrete were measured in accordance with Japanese Industrial Standards (JIS A1101, 1128, 6204).

[Example 1]
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser, 343.1 g of water and an ethylene oxide 50 mol adduct (polyethylene glycol) of 3-methyl-3-buten-1-ol were added. (Including 6.7% by mass) 857.12 g and 30.89 g of 15% paratoluenesulfonic acid monohydrate aqueous solution as a pH adjuster (pH = 2.7, 21 ° C.) After nitrogen substitution, the temperature was raised to 58 ° C. in a nitrogen atmosphere, and 37.9 g of 2% hydrogen peroxide water was added. After the temperature was stabilized at 58 ° C., an aqueous solution in which 53.3 g of acrylic acid was dissolved in 13.3 g of water was added dropwise over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.0 g of L-ascorbic acid and 1.9 g of 2-mercaptopropionic acid in 161.6 g of water was dropped over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was maintained at 3 or less. And after cooling (pH = 2.8, 21.4 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When the GPC of the obtained copolymer (1) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2289) was 34000, and the content of the polymer was 82.9%. It was. The results are shown in Table 1.
A concrete test was performed using the obtained copolymer (1) as a cement admixture. The results are shown in Table 2.

[Example 2]
In a glass reaction vessel equipped with a thermometer, a stirrer, a dripping device, a nitrogen inlet tube, and a reflux condenser, 339.9 g of water and an ethylene oxide 50 mol adduct (polyethylene glycol) of 3-methyl-3-buten-1-ol were added. (Containing 6.7% by mass) 849.9 g, and 30.93 g of 15% p-toluenesulfonic acid monohydrate aqueous solution as a pH adjusting agent (pH = 2.7, 20 ° C.), and the inside of the reaction vessel was stirred. After nitrogen substitution, the temperature was raised to 58 ° C. in a nitrogen atmosphere, and 41.2 g of 2% hydrogen peroxide water was added. After the temperature was stabilized at 58 ° C., an aqueous solution in which 60.5 g of acrylic acid was dissolved in 15.1 g of water was dropped over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.1 g of L-ascorbic acid and 2.9 g of 2-mercaptopropionic acid in 159.2 g of water was added dropwise over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was maintained at 3 or less. And after cooling (pH = 2.7, 21.6 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (2) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2289) was 37000, and the content of the polymer was 84.3%. It was. The results are shown in Table 1.
A concrete test was performed using the obtained copolymer (2) as a cement admixture. The results are shown in Table 2.

Example 3
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser, 343.1 g of water and an ethylene oxide 50 mol adduct (polyethylene glycol) of 3-methyl-3-buten-1-ol were added. (Containing 6.7% by mass) 829.7 g, and 31.2 g of a 15% paratoluenesulfonic acid monohydrate aqueous solution as a pH adjusting agent (pH = 2.6, 21 ° C.), and the inside of the reaction vessel was stirred. After nitrogen substitution, the temperature was raised to 58 ° C. in a nitrogen atmosphere, and 50.4 g of 2% hydrogen peroxide water was added. After the temperature was stabilized at 58 ° C., an aqueous solution in which 80.6 g of acrylic acid was dissolved in 20.1 g of water was dropped over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.3 g of L-ascorbic acid and 2.7 g of 2-mercaptopropionic acid in 156.9 g of water was added dropwise over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was maintained at 3 or less. And after cooling (pH = 2.6, 26.0 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When the GPC of the obtained copolymer (3) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2289) was 36500, and the content of the polymer was 88.7%. It was. The results are shown in Table 1.

Example 4
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser, 339.9 g of water, 849.9 g of an ethylene oxide 50 mol adduct of 2-methyl-2-propen-1-ol, As a pH adjuster, 30.93 g of 15% paratoluenesulfonic acid monohydrate aqueous solution was charged (pH = 2.4, 27 ° C.), and the inside of the reaction vessel was purged with nitrogen under stirring, and the temperature was adjusted to 58 ° C. under a nitrogen atmosphere. After raising the temperature, 41.2 g of 2% hydrogen peroxide water was added. After the temperature was stabilized at 58 ° C., an aqueous solution in which 60.5 g of acrylic acid was dissolved in 15.1 g of water was dropped over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.1 g of L-ascorbic acid and 2.9 g of 2-mercaptopropionic acid in 159.2 g of water was added dropwise over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was maintained at 3 or less. And after cooling (pH = 2.7, 21 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When the GPC of the obtained copolymer (4) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2274) was 36500, and the content of the polymer was 83.7%. It was. The results are shown in Table 1.

Example 5
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube, and a reflux condenser, 294.1 g of water and an ethylene oxide 50 mol adduct of allyl alcohol (containing 5.0% by mass of polyethylene glycol) 605. 3 g, 30.0 g of 15% aqueous solution of paratoluenesulfonic acid monohydrate as a pH adjuster (pH = 2.5, 27 ° C.) were added, and the inside of the reaction vessel was purged with nitrogen under stirring, and 58 under a nitrogen atmosphere. After raising the temperature to 0 ° C., 39.0 g of 2% hydrogen peroxide water was added. After the temperature was stabilized at 58 ° C., an aqueous solution in which 63.3 g of acrylic acid was dissolved in 15.8 g of water was added dropwise over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.0 g of L-ascorbic acid and 2.2 g of 2-mercaptopropionic acid in 156.4 g of water was added dropwise over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was maintained at 3 or less. And after cooling (pH = 2.6, 21.4 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (5) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2260) was 37500, and the content of the polymer was 67.8%. It was. The results are shown in Table 1.

Example 6
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser, 343.1 g of water and an ethylene oxide 50 mol adduct (polyethylene glycol) of 3-methyl-3-buten-1-ol were added. (Including 6.7% by mass) 857.12 g, and 30.89 g of a 7.5% aqueous methanesulfonic acid solution as a pH adjusting agent (pH = 2.5, 27 ° C.), and the inside of the reaction vessel was purged with nitrogen under stirring. After raising the temperature to 58 ° C. in a nitrogen atmosphere, 37.9 g of 2% hydrogen peroxide water was added. After the temperature was stabilized at 58 ° C., an aqueous solution in which 53.3 g of acrylic acid was dissolved in 13.3 g of water was added dropwise over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.0 g of L-ascorbic acid and 1.9 g of 2-mercaptopropionic acid in 161.6 g of water was dropped over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was maintained at 3 or less. And after cooling (pH = 2.7, 21.4 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (6) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2289) was 34500, and the content of the polymer was 82.5%. It was. The results are shown in Table 1.

Example 7
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser, 58.7 g of water, 234.8 g of an ethylene oxide 150 mol adduct of 2-methyl-2-propen-1-ol, As a pH adjuster, 11.0 g of a 15% paratoluenesulfonic acid monohydrate aqueous solution was charged (pH = 2.5, 27 ° C.), the inside of the reaction vessel was purged with nitrogen under stirring, and the temperature was adjusted to 58 ° C. under a nitrogen atmosphere. After raising the temperature, 16.8 g of 2% hydrogen peroxide water was added. After the temperature was stabilized at 58 ° C., an aqueous solution in which 12.7 g of acrylic acid was dissolved in 7.2 g of water was dropped over 3 hours. At the same time as the dropping of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 0.9 g of L-ascorbic acid and 0.8 g of 2-mercaptopropionic acid in 43.3 g of water was dropped over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was maintained at 3 or less. And after cooling (pH = 2.7, 20.5 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (7) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 6680) was 48040, and the content of the polymer was 83.9%. It was. The results are shown in Table 1.

[Comparative Example 1]
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser, 343.1 g of water and an ethylene oxide 50 mol adduct (polyethylene glycol) of 3-methyl-3-buten-1-ol were added. (Containing 6.7% by mass) 857.12 g (pH = 7.4, 23 ° C.), the reaction vessel was purged with nitrogen under stirring, and the temperature was raised to 58 ° C. in a nitrogen atmosphere, followed by 2% peroxidation Hydrogen water 37.9g was thrown in. After the temperature was stabilized at 58 ° C., an aqueous solution in which 53.3 g of acrylic acid was dissolved in 13.3 g of water was added dropwise over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.0 g of L-ascorbic acid and 1.9 g of 2-mercaptopropionic acid in 161.6 g of water was dropped over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was greater than 3. And after cooling (pH = 5.1, 21.4 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (C1) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2289) was 34000, and the content of the polymer was 74.7%. It was. The results are shown in Table 1.
A concrete test was performed using the obtained copolymer (C1) as a cement admixture. The results are shown in Table 2.

[Comparative Example 2]
In a glass reaction vessel equipped with a thermometer, a stirrer, a dripping device, a nitrogen inlet tube, and a reflux condenser, 339.9 g of water and an ethylene oxide 50 mol adduct (polyethylene glycol) of 3-methyl-3-buten-1-ol were added. (Containing 6.7% by mass) 849.9 g (pH = 7.2, 28 ° C.), the inside of the reaction vessel was purged with nitrogen under stirring, and the temperature was raised to 58 ° C. in a nitrogen atmosphere, followed by 2% peroxidation. 41.2 g of hydrogen water was added. After the temperature was stabilized at 58 ° C., an aqueous solution in which 60.5 g of acrylic acid was dissolved in 15.1 g of water was dropped over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.1 g of L-ascorbic acid and 2.9 g of 2-mercaptopropionic acid in 159.2 g of water was added dropwise over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was greater than 3. And after cooling (pH = 5.0, 21.6 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (C2) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2289) was 33400, and the content of the polymer was 77.2%. It was. The results are shown in Table 1.
A concrete test was performed using the obtained copolymer (C2) as a cement admixture. The results are shown in Table 2.

[Comparative Example 3]
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser, 343.1 g of water and an ethylene oxide 50 mol adduct (polyethylene glycol) of 3-methyl-3-buten-1-ol were added. (Containing 6.7% by mass) 829.7 g (pH = 7.3, 23 ° C.), the reaction vessel was purged with nitrogen under stirring, and the temperature was raised to 58 ° C. in a nitrogen atmosphere, followed by 2% peroxidation. Hydrogen water 50.4g was thrown in. After the temperature was stabilized at 58 ° C., an aqueous solution in which 80.6 g of acrylic acid was dissolved in 20.1 g of water was dropped over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.3 g of L-ascorbic acid and 2.7 g of 2-mercaptopropionic acid in 156.9 g of water was added dropwise over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was greater than 3. And after cooling (pH = 4.95, 26.0 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (C3) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2289) was 36000, and the content of the polymer was 81.9%. It was. The results are shown in Table 1.
A concrete test was performed using the obtained copolymer (C3) as a cement admixture. The results are shown in Table 2.

[Comparative Example 4]
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube, and a reflux condenser, 339.9 g of water and 849.9 g of an ethylene oxide 50 mol adduct of 2-methyl-2-propen-1-ol were added. The reactor was charged (pH = 7.4, 21 ° C.), the inside of the reaction vessel was purged with nitrogen under stirring, and the temperature was raised to 58 ° C. in a nitrogen atmosphere, and then 41.2 g of 2% hydrogen peroxide water was added. After the temperature was stabilized at 58 ° C., an aqueous solution in which 60.5 g of acrylic acid was dissolved in 15.1 g of water was dropped over 3 hours. At the same time as the dropwise addition of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 1.1 g of L-ascorbic acid and 2.9 g of 2-mercaptopropionic acid in 159.2 g of water was added dropwise over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was greater than 3. And after cooling (pH = 4.95, 21.6 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (C4) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2274) was 36200, and the content of the polymer was 76.4%. It was. The results are shown in Table 1.

[Comparative Example 5]
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser, 313.9 g of water and an ethylene oxide 50 mol adduct of allyl alcohol (containing 5.0% by mass of polyethylene glycol) 608. 4 g and 1.1 g of acrylic acid were charged (pH = 5.5, 27 ° C.), the inside of the reaction vessel was purged with nitrogen under stirring, and the temperature was raised to 58 ° C. in a nitrogen atmosphere. .6 g was charged. After the temperature was stabilized at 58 ° C., an aqueous solution in which 62.5 g of acrylic acid was dissolved in 24.8 g of water was added dropwise over 3 hours. At the same time as the dropping of the acrylic acid aqueous solution, an aqueous solution in which 1.0 g of L-ascorbic acid and 2.2 g of 2-mercaptopropionic acid were dissolved in 146.8 g of water was dropped over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was greater than 3. And after cooling (pH = 5.0, 20.1 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (C5) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 2260) was 36000, and the content of the polymer was 64.5%. It was. The results are shown in Table 1.

[Comparative Example 6]
In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen inlet tube, and a reflux condenser, 58.7 g of water, 234.8 g of an ethylene oxide 150 mol adduct of 2-methyl-2-propen-1-ol, 0.4 g of acrylic acid was added (pH = 5.5, 27 ° C.), the inside of the reaction vessel was purged with nitrogen under stirring, and the temperature was raised to 58 ° C. in a nitrogen atmosphere. Was introduced. After the temperature was stabilized at 58 ° C., an aqueous solution in which 12.3 g of acrylic acid was dissolved in 7.2 g of water was added dropwise over 3 hours. At the same time as the dropping of the acrylic acid aqueous solution, an aqueous solution prepared by dissolving 0.9 g of L-ascorbic acid and 0.7 g of 2-mercaptopropionic acid in 43.4 g of water was dropped over 3.5 hours. Thereafter, the temperature was continuously maintained at 58 ° C. for 1 hour to complete the polymerization reaction. The pH during the polymerization reaction was greater than 3. And after cooling (pH = 5.0, 21.6 degreeC), it neutralized to pH = 6 with 30% NaOH aqueous solution.
When GPC of the obtained copolymer (C6) was measured, the mass average molecular weight of the polymer excluding the peak corresponding to the monomer (Mw = 6680) was 50670, and the content of the polymer was 80.9%. It was. The results are shown in Table 1.

表２における酸量は仕込みアクリル酸をアクリル酸ナトリウム換算した数値である。

The acid amount in Table 2 is a numerical value obtained by converting charged acrylic acid into sodium acrylate.

  From the results of Example 1 and Comparative Example 1, the flow value is higher in Comparative Example 1 than in Comparative Example 1 in Example 1 in which the polymer content is the same and the polymer content is high. This shows that the copolymer (1) obtained in Example 1 has higher fluidity when used as a cement admixture than the copolymer (C1) obtained in Comparative Example 1. .

  Also from the results of Example 2 and Comparative Examples 2 and 3, in Example 2 where the polymer content is the same in the polymer having the same acid amount, the flow value is larger than in Comparative Examples 2 and 3. From this, the copolymer (2) obtained in Example 2 is more fluid when used as a cement admixture than the copolymers (C2) and (C3) obtained in Comparative Examples 2 and 3. It turns out that the nature is high. Moreover, it turns out that the addition amount reduction | decrease rate is 5% or more from the flow value of Comparative Examples 2, 3 and Example 2. FIG.

  The polycarboxylic acid copolymer obtained by the production method of the present invention is suitably used as a cement admixture. The cement admixture is suitably used for cement compositions such as cement paste, mortar, and concrete.

Claims (5)

Structural unit (I) derived from unsaturated polyalkylene glycol ether monomer (a) represented by general formula (1) and unsaturated carboxylic acid monomer (b) represented by general formula (2) A method for producing a polycarboxylic acid-based copolymer containing the derived structural unit (II),
Polymerization of the monomer component containing the monomer (a) and the monomer (b) is being performed in the presence of a pH adjuster using a peroxide and a reducing agent in combination as a polymerization initiator. The pH is controlled to 2-3 .
A method for producing a polycarboxylic acid copolymer.

(In General Formula (1), Y represents an alkenyl group having 2 to 8 carbon atoms. T is the same or different and represents an alkylene group having 1 to 5 carbon atoms or an aryl group having 6 to 9 carbon atoms. ¹ O represents one or more oxyalkylene groups having 2 to 18 carbon atoms, m represents 0 or 1, n represents the average number of moles added of the oxyalkylene group, and n is 1 to 500. R ² represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)

(In General Formula (2), R ³ , R ⁴ , and R ⁵ are the same or different and each represents a hydrogen atom, a methyl group, or a —COOM group. M represents a hydrogen atom, a monovalent metal atom, or a divalent metal. Represents an atom, an ammonium group, or an organic amine group.)   The production method according to claim 1, wherein Y in the general formula (1) is at least one selected from a 3-methyl-3-butenyl group and a 2-methyl-2-propenyl group.   The manufacturing method of Claim 1 or 2 whose said pH adjuster is organic sulfonic acid and / or its salt.   The production method according to any one of claims 1 to 3, wherein the peroxide is hydrogen peroxide and the reducing agent is L-ascorbic acid. The manufacturing method in any one of Claim 1 to 4 whose said copolymer is a copolymer for cement admixtures.