JP2011032132A - Method for production of polycarboxylic acid-based copolymer for cement admixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for production of a polycarboxylic acid-based copolymer for a cement admixture. <P>SOLUTION: The method for production of a polycarboxylic acid-based copolymer for a cement admixture includes a process of adding a polymerization initiator dropwise to a polymerization solution. The monomer component contained in the polymerization solution includes a monomer (a) represented by formula (1) and/or a monomer (b) represented by formula (2) and a monomer (c) represented by a specific formula. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a method for producing a polycarboxylic acid copolymer. More specifically, the present invention relates to a method for producing a polycarboxylic acid copolymer useful for a cement admixture.

The polycarboxylic acid-based copolymer has an oxyalkylene group together with a -COOM group (M represents an atom or atomic group that can be dissociated), and has hydrophilicity, dispersibility, etc. derived from these groups. It is used in various industrial fields as a polymer that exhibits the above properties. Among them, in recent years, since it can exhibit high water reduction performance as compared with conventional cement dispersants such as naphthalene, demand has increased as a raw material for cement admixtures and has attracted attention.

Examples of the polycarboxylic acid copolymer used as the main component of such a cement admixture include acrylic polymers modified with ester groups and amide groups, such as acrylic acid or methacrylic acid, and acrylic or methacryl methoxy. An essential component is an acrylic copolymer obtained by copolymerization of a polyalkylene glycol ester monomer with an acrylic or methacrylic ester of a tertiary alkanolamine, or a polyalkylene glycol monoalkenyl ether monomer and a maleic monomer. A structural unit derived from a polycarboxylic acid obtained by copolymerizing a monomer component or an unsaturated polyalkylene glycol ether monomer, and a structural unit derived from an unsaturated monocarboxylic acid monomer. Copolymers containing essential constituent units are disclosed. Are (for example, see Patent Documents 1, 2 and 3 and the like.).

JP 2002-3256 A (page 1-2) JP 2001-220416 A (page 1-2) JP 2001-220417 A (page 1-2)

As described above, polycarboxylic acid-based copolymers used for cement admixtures have been disclosed. Synthesis of these polycarboxylic acid-based copolymers is based on aqueous radicals using a polymerization initiator and a reducing agent. It is carried out by a polymerization reaction.
However, in this synthesis method, an unusual polymerization behavior may occur such that the polymerization rate during the polymerization reaction becomes too fast or a polymer having a high weight average molecular weight is obtained. In order to demonstrate stable performance as a cement admixture, it is important to stabilize the quality of the polymer used as a raw material. There is a demand for a production method capable of stably producing a system copolymer.
The present invention has been made in view of the above-described situation, and suppresses variation in physical properties of the synthesized polycarboxylic acid copolymer, and can be suitably used for a cement admixture. An object of the present invention is to provide a method capable of stably producing the product.

In the reaction system for synthesizing a polycarboxylic acid copolymer by polymerizing a polymerization solution containing a monomer component using a polymerization initiator and a reducing agent, the present inventors have a reducing action in the system. When a reducing substance such as a certain substance or transition metal is mixed, even if it is a trace amount of several hundreds ppb level, it affects the polymerization behavior and causes a variation in the quality of the obtained polymer. I found it. Then, various studies were made on a method for stably synthesizing a polycarboxylic acid copolymer even if a trace amount of a reducing substance is mixed in the synthesis reaction system. When there is a phenomenon that the polymerization rate of the synthesis becomes too fast or the weight average molecular weight of the synthesized polycarboxylic acid copolymer becomes too high, It was found that the polymerization initiator was added all at the beginning of the reaction, and a polycarboxylic acid was obtained by polymerizing a polymerization solution containing a monomer component having a specific structure using a polymerization initiator and a reducing agent. When synthesizing an acid copolymer, a polymerization initiator can be added dropwise to control the polymerization initiation reaction. Even if a reducing substance is mixed in the reaction system, the polymerization behavior is controlled. Affects The inventors have found that it is possible to synthesize a polycarboxylic acid-based copolymer with stable and small variation in physical properties without suffering from the problem, and arrived at the present invention by conceiving that the above-mentioned problems can be solved brilliantly. .

That is, the present invention is a method for producing a polycarboxylic acid copolymer for a cement admixture that polymerizes a polymerization solution containing a monomer component using a polymerization initiator and a reducing agent, and the production method includes polymerization. Including a step of dropping an initiator into the polymerization solution, wherein the monomer component is represented by the following general formula (1);

(In formula, R < ¹ >, R < ² > and R < ³ > are the same or different and represent a hydrogen atom or a methyl group. X represents a C1-C5 bivalent alkylene group, or R < ¹ > R. ^{When the} group represented by ³ C═CR ² — is a vinyl group, this represents that a carbon atom bonded to X and an oxygen atom are directly bonded to each other, and R ^a is the same or different and represents the number of carbon atoms. Represents an alkylene group of 2 to 5. m represents an average addition mole number of an oxyalkylene group represented by R ^a O, and is a number of 3 to 300. R ⁴ represents a hydrogen atom or a carbon number of 1 to 20; A monomer group (a) represented by the following general formula (2);

(In the formula, R ⁵ represents a hydrogen atom or a methyl group. R ^a is the same or different and represents an alkylene group having 2 to 5 carbon atoms. P represents an oxyalkylene group represented by R ^a O. The average added mole number is a number of 2 to 300. R ⁶ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.) And the following general formula (3);

(In the formula, R ⁷ represents a hydrogen atom or a methyl group. R ^a is the same or different and represents an alkylene group having 2 to 5 carbon atoms. Q represents an oxyalkylene group represented by R ^a O. The average addition mole number is a number of 0 to 1. M represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a metal atom, an ammonium group, or an organic ammonium group. It is a manufacturing method of the polycarboxylic acid type copolymer for cement admixtures containing (c).
The present invention is described in detail below.

The method for producing a polycarboxylic acid copolymer for cement admixture of the present invention is carried out by polymerizing a polymerization solution containing a monomer component using a polymerization initiator and a reducing agent. The polymerization reaction can be carried out by a usual polymerization method such as solution polymerization or bulk polymerization, and can also be carried out batchwise or continuously. Moreover, the manufacturing method of this invention may include another process, as long as it includes the process of superposing | polymerizing the polymerization solution containing a monomer component using a polymerization initiator and a reducing agent.

The method for producing a polycarboxylic acid copolymer for cement admixture of the present invention includes a step of dropping a polymerization initiator into a polymerization solution. The present invention can be suitably applied when a reducing substance such as a substance having a reducing action or a transition metal is present in the polymerization system. For example, when a reducing substance exists in the polymerization system, if a polymerization initiator is added all at once at the start of polymerization, the polymerization rate of the synthesis becomes too fast, or the polycarboxylic acid copolymer to be synthesized It has been clarified that the weight average molecular weight of the polymer becomes too high, but the reason why this occurs when the reducing substance is present in the polymerization system is considered as follows. . For example, when iron ions, which are transition metals, are present in the polymerization system, the trivalent iron ions are reduced to divalent iron ions by the reducing agent introduced into the reaction system, and the generated divalent iron ions are reduced. It is considered that a cycle of generating radicals from the polymerization initiator and returning to trivalent iron ions occurs in the reaction system by serving as an agent. In this radical generation cycle, the rotation speed of the radical generation cycle is faster due to the faster oxidation and reduction cycle of the iron ions interposed between the radical generation cycle and the radical generation only from the polymerization initiator and the reducing agent. It is considered that more radicals are generated in the reaction system in a short time. Due to this mechanism, even if a very small amount of reducing substance is present in the reaction system, the reaction system is greatly affected. If a polymerization initiator is added all at once at the start of polymerization, the polymerization reaction is controlled. You may not be able to do it. However, if the polymerization initiator is added dropwise, it is possible to prevent a large amount of radicals from being generated in a short time due to the presence of such a reducing substance.
Moreover, the manufacturing method of this invention may include another process, as long as it includes the process of dripping a polymerization initiator to a polymerization solution.

As described above, the reducing substance is generated only from the polymerization initiator and the reducing agent by repeating the cycle of oxidation and reduction interposed between the polymerization initiator and the reducing agent used in the present invention as described above. Anything that affects the behavior of the polymerization reaction by generating a large amount of radicals in the reaction system in a short period of time will be applicable. For example, monoethanolamine, diethanolamine, triethanolamine , Hydroxylamine, hydroxylamine hydrochloride, amine compounds such as ethylenediamine, sodium ethylenediaminetetraacetate, hydrazine, glycine and their salts; alkali metal sulfites such as sodium sulfite, sodium hydrogen sulfite, sodium pyrobisulfite, metabisulfite ; Sodium dithionite, sodium formaldehyde Ruhokishireto, such as hydroxymethanesulfinic acid sodium _{dihydrate, -SH, -SO 2 H, -NHNH} 2, -COCH (OH) - an organic compound containing a group such as and their salts; hypophosphorous acid Lower oxides such as sodium hypophosphite, sodium hydrosulfite and sodium hyponitrite and their salts; mol salts; invert sugars such as D-fructose and D-glucose; thiourea compounds such as thiourea and thiourea dioxide; L -Ascorbic acid and its salt, L-ascorbic acid ester, erythorbic acid and its salt, erythorbic acid ester and other substances having a reducing action, iron, manganese, cobalt, nickel, chromium, vanadium, copper, scandium, titanium, Examples thereof include transition metals such as zinc.
The reducing agent used in the production method of the present invention and the chain transfer agent described later are also substances having a reducing action, but the reducing substance in the present invention is a reducing agent and a chain transfer agent in the reaction system. It means a substance having a reducing action that does not contain added substances and exists in other reaction systems.

As a method of dropping the polymerization initiator into the polymerization solution, if a large amount of radical generation in a short time during the reaction can be prevented, and a polycarboxylic acid copolymer with small variations in physical properties can be stably synthesized, Although not particularly limited, for example, a method of continuously dropping all polymerization initiators from the start of polymerization, a method of dropping all polymerization initiators intermittently from the start of polymerization, a part of the polymerization initiator before the start of polymerization Preparation, dropping the remainder from the start of polymerization, charging a part of the polymerization initiator before the start of polymerization, dropping the remainder from the middle of the polymerization reaction, or preparing a part of the polymerization initiator before starting the polymerization And a method of intermittently dropping the rest. Among these, it is preferable to add dropwise by a method in which all of the polymerization initiator is continuously added from the start of polymerization.

In any of the above dropping methods, in the production method of the present invention, it is preferable that the polymerization initiator is dropped over 120 minutes from the start of the reaction. By carrying out over 120 minutes or more, it becomes possible to sufficiently suppress the influence of the iron ions. More preferably, it is performed over 150 minutes or more, and more preferably over 180 minutes.

The production method preferably includes a step of dropping a reducing agent into the polymerization solution separately from the polymerization initiator. By adding the reducing agent dropwise, radicals generated from the polymerization initiator can be generated at a stable concentration. Further, when the reducing agent is dropped together with the polymerization initiator, each of them reacts before the dropping to generate radicals or deactivate them, so there is a possibility that the radical concentration cannot be controlled constant. In addition, as a method of dripping a reducing agent to a polymerization solution, it can be set as the method similar to the method of dripping the polymerization initiator mentioned above to a polymerization solution.
Moreover, it is preferable to perform dripping of a reducing agent over 120 minutes or more from the reaction start. More preferably, it is performed over 150 minutes or more, and more preferably over 180 minutes.
The method of dropping the polymerization initiator into the polymerization solution and the method of dropping the reducing agent into the polymerization solution are preferably the same method. Moreover, it is preferable that the time required for each dropping is also the same.

With respect to all the components charged into the reaction system such as a monomer component other than the polymerization initiator and the reducing agent in the polymerization reaction, there are no particular restrictions on the method of charging into the reaction system, for example, before the start of polymerization. Alternatively, it may be added all at once at the start, or one monomer component may be added all at once before or at the start of polymerization, and the remaining monomer components may be added dropwise. The monomer may be added dropwise from the start of polymerization, or may be added in several portions at the start of polymerization and during the polymerization reaction. Since the monomer (a) generally does not exhibit homopolymerizability, it is particularly preferable that it is added all at once before or at the start of the polymerization from the viewpoint of improving the polymerization rate and the polymer content. Since the monomers (b) and (c) generally exhibit homopolymerizability, from the viewpoint of suppressing the explosive progress of the polymerization, it is preferable not to add them all before or at the start of the polymerization. It is particularly preferable to add it dropwise. All the components dropped into the reaction system may be dropped separately or as a mixed aqueous solution. Further, the methods such as the timing of addition of each component and the addition rate may be the same or different.

The amount of the polymerization initiator used is preferably 0.1 mol% or more and less than 1.0 mol% with respect to 100 mol% of all monomer components. When the amount of the polymerization initiator used is 0.1 mol% or more and less than 1.0 mol%, it is possible to synthesize a polycarboxylic acid copolymer having a small variation in physical properties effectively and stably. Become. The amount of the polymerization initiator used is more preferably 0.1 mol% or more and 0.9 mol% or less with respect to 100 mol% of all monomer components, and 0.2 mol% or more and 0.8 mol%. More preferably, it is as follows. Most preferably, it is 0.3 mol% or more and 0.7 mol% or less.

The amount of the reducing agent used is preferably set to an appropriate amount depending on the type and amount of the polymerization initiator. For example, in a system in which 2 mol of a polymerization initiator and 1 mol of a reducing agent theoretically generate 2 mol of radical, the reducing agent should be set to half the amount of the polymerization initiator, and the preferred range is also that of the polymerization initiator. This is equivalent to half the amount.

In the production method of the present invention, the preferred range of the ratio between the polymerization initiator and the reducing agent varies depending on the type of the polymerization initiator and the reducing agent used. Specifically, it is determined by the molar ratio of the polymerization initiator and the reducing agent necessary for generating 1 mol of radical. For example, when 2 mol of a polymerization initiator and 1 mol of a reducing agent theoretically generate 2 mol of radical, the ratio of the polymerization initiator to the reducing agent is 4: 1 to 0 as the polymerization initiator: reducing agent. The ratio is preferably 5: 1. More preferably, it is 3: 1 to 1: 1, and still more preferably 2.5: 1 to 1.5: 1.

Copolymerization conditions such as the copolymerization temperature in the production method of the present invention are appropriately set according to the copolymerization method used, the solvent, the polymerization initiator, the polymerization initiator, the chain transfer agent, etc. to be described later. However, the copolymerization temperature is usually preferably 0 ° C. or higher, and preferably 150 ° C. or lower. More preferably, it is 40 degreeC or more, More preferably, it is 45 degreeC or more, Most preferably, it is 50 degreeC or more. Further, it is more preferably 120 ° C. or lower, further preferably 100 ° C. or lower, and particularly preferably 85 ° C. or lower.

The polymerization initiator used in the production method of the present invention is not particularly limited as long as it is usually used, but persulfates such as ammonium persulfate, sodium persulfate, potassium persulfate; hydrogen peroxide; '-Azobis-2-methylpropionamidine hydrochloride, 2,2'-azobis-2- (2-imidazolin-2-yl) propane hydrochloride, azobisisobutyronitrile, 2-carbamoylazoisobutyronitrile, etc. Preferred are peroxides such as benzoyl peroxide, lauroyl peroxide, sodium peroxide, t-butyl hydroperoxide and cumene hydroperoxide. More preferred are hydrogen peroxide and ammonium persulfate, and particularly preferred is hydrogen peroxide.
These polymerization initiators may be used alone or in combination of two or more.

The reducing agent used in the production method of the present invention is not particularly limited as long as it has a reducing action and is usually used. Monoethanolamine, diethanolamine, triethanolamine, hydroxylamine, hydroxylamine hydrochloride Amine compounds such as ethylenediamine, sodium ethylenediaminetetraacetate, hydrazine, glycine and their salts; alkali metal sulfites such as sodium sulfite, sodium bisulfite, sodium pyrobisulfite, metabisulfite; sodium dithionite, formaldehyde Organic compounds containing groups such as —SH, —SO ₂ H, —NHNH ₂ , —COCH (OH) — and their salts, such as sodium sulfoxylate, sodium hydroxymethanesulfinate dihydrate and the like; Phosphorous acid, next Lower oxides such as sodium phosphite, sodium hydrosulfite and sodium hyponitrite and their salts; Mohr salts; Invert sugars such as D-fructose and D-glucose; Thiourea compounds such as thiourea and thiourea dioxide; L-ascorbine An acid and its salt, L-ascorbic acid ester, erythorbic acid and its salt, and erythorbic acid ester are suitable. More preferred are L-ascorbic acid and salts thereof and erythorbic acid and salts thereof, and particularly preferred are L-ascorbic acid and erythorbic acid.
These reducing agents may be used alone or in combination of two or more.

In the production method of the present invention, a chain transfer agent can also be used as necessary. The amount of the chain transfer agent used is preferably 0.5 to 5.0 mol% when the total monomer components are 100 mol%. If it is less than 0.5 mol%, a gel may be formed or the molecular weight becomes too large, and the desired copolymer may not be obtained. Moreover, when it exceeds 5.0 mol%, molecular weight will become small too much and there exists a possibility that the function as a cement dispersant may not be exhibited. More preferably, when the total monomer component is 100 mol%, it is 1.0 to 4.0 mol%, and more preferably 1.5 to 3.0 mol%.
Since the chain transfer agent can act as a reducing agent, the amount of chain transfer agent in the reaction system decreases when the chain transfer agent acts as a reducing agent in the radical generation cycle mediated by the reducing substance described above. However, this is considered to cause the molecular weight of the obtained polymer to be large. Therefore, the addition method of the chain transfer agent is not particularly limited, but the chain transfer agent is added dropwise to the polymerization solution from the viewpoint of stably producing a polymer with little variation in molecular weight. It is particularly preferred.

As the chain transfer agent, one or more commonly used ones can be used, but n-dodecyl mercaptan, octyl mercaptan, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercapto Thiol chain transfer agents such as propionic acid, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionate, 2-mercaptoethanesulfonic acid, butylthioglycolate; carbon tetrachloride, methylene chloride, bromoform, bromotrichloroethane, etc. Halogens; primary alcohols such as 2-aminopropan-1-ol; secondary alcohols such as isopropanol; phosphorous acid, hypophosphorous acid and their salts (sodium hypophosphite, potassium hypophosphite, etc.) Sulfite, hydrogen sulfite, nitrous acid Acid, metabisulfite and their salts (sodium sulfite, sodium bisulfite, sodium dithionite, sodium metabisulfite, potassium sulfite, potassium bisulfite, potassium dithionite, potassium metabisulfite, etc.) Oxides and salts thereof; α, β-unsaturated dicarboxylic acid compounds such as maleic acid, fumaric acid and citraconic acid and derivatives thereof and salts thereof; allyl compounds such as allyl alcohol and allylsulfonic acid (salt) and the like Preferred are methallyl compounds such as methallyl alcohol and methallyl sulfonic acid (salt) and their alkylene oxide adducts. More preferred are thioglycolic acid, 2-mercaptopropionic acid, and 3-mercaptopropionic acid, and particularly preferred is 3-mercaptopropionic acid.
In addition, 1 type may be used for a chain transfer agent and it may use it in combination of 2 or more types.

As the solvent used as necessary in the production method of the present invention, a commonly used solvent can be used; water; alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol; benzene, toluene, xylene, cyclohexane Aromatic or aliphatic hydrocarbons such as n-hexane and n-heptane; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; and cyclic ethers such as tetrahydrofuran and dioxane are preferred. These may be used alone or in combination of two or more. Among these, from the viewpoint of solubility of the monomer component and the resulting polycarboxylic acid polymer, one or two or more solvents selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms are used. It is preferable to use it.

The amount of the solvent used is preferably 20 to 300% by mass when the total monomer components are 100% by mass. When the amount of the solvent used is less than 20% by mass, the viscosity in the reaction solution becomes too high, and uniform stirring cannot be performed, and a stable copolymer may not be obtained. Moreover, since the density | concentration of the copolymer in a reaction solution will become thin when it exceeds 300 mass%, since the transportation cost starts and the consideration of a copolymer becomes high, there exists a possibility that the use which can be used may be limited. . More preferably, when the total monomer component is 100% by mass, it is 30 to 200% by mass, and more preferably 40 to 100% by mass.

The monomer component used in the production method of the present invention is represented by the following general formula (1);

(In formula, R < ¹ >, R < ² > and R < ³ > are the same or different and represent a hydrogen atom or a methyl group. X represents a C1-C5 bivalent alkylene group, or R < ¹ > R. ^{When the} group represented by ³ C═CR ² — is a vinyl group, this represents that a carbon atom bonded to X and an oxygen atom are directly bonded to each other, and R ^a is the same or different and represents the number of carbon atoms. Represents an alkylene group of 2 to 5. m represents an average addition mole number of an oxyalkylene group represented by R ^a O, and is a number of 3 to 300. R ⁴ represents a hydrogen atom or a carbon number of 1 to 20; A monomer group (a) represented by the following general formula (2);

(In the formula, R ⁵ represents a hydrogen atom or a methyl group. R ^a is the same or different and represents an alkylene group having 2 to 5 carbon atoms. P represents an oxyalkylene group represented by R ^a O. The average added mole number is a number of 2 to 300. R ⁶ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.) And the following general formula (3);

(In the formula, R ⁷ represents a hydrogen atom or a methyl group. R ^a is the same or different and represents an alkylene group having 2 to 5 carbon atoms. Q represents an oxyalkylene group represented by R ^a O. The average addition mole number is a number of 0 to 1. M represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a metal atom, an ammonium group, or an organic ammonium group. (C).
In addition, each monomer can use 1 type (s) or 2 or more types, respectively.

The ratio between the monomers of the monomer component is not particularly limited as long as the monomer (a) and / or the monomer (b) and the monomer (c) are essential. However, the ratio (mass%) of the monomer (a) and / or the monomer (b) and the monomer (c) is preferably 98/2 to 50/50. More preferably, it is 96 / 4-60 / 40, More preferably, it is 94 / 6-70 / 30.
However, the total of the monomer (a) and / or the monomer (b) and the monomer (c) is 100% by mass.

The monomer component may contain another monomer (d) other than the monomers (a) to (c). The content of the other monomer (d) is preferably 30% by mass or less with respect to 100% by mass of all monomer components. More preferably, it is 20 mass% or less, More preferably, it is 10 mass% or less.

In the general formula (1) representing the monomer (a), the average added mole number m of the oxyalkylene group represented by-(R ^a O) m- is suitably 3 to 300. If it is less than 3, the hydrophobicity becomes too strong to perform uniform polymerization, and there is a possibility that the effect as a cement admixture cannot be fully exhibited. Moreover, when it exceeds 300, polymerizability will fall large and there exists a possibility that the usage-amount of a cement admixture may be needed in large quantities. The lower limit value of m is preferably 4, more preferably 5, and the upper limit value is preferably 200, more preferably 150, and still more preferably 120.

In the general formula (1), the oxyalkylene group represented by R ^a O is an oxyalkylene group having 2 to 5 carbon atoms, and examples thereof include an oxyethylene group, an oxypropylene group, an oxybutylene group, and an oxyisobutylene. Group, etc., and an oxyethylene group and an oxypropylene group are preferable. Especially, it is especially preferable that an oxyethylene group is a main component from a viewpoint of the balance of hydrophilic property and hydrophobicity. Specifically, it is preferable that the proportion of oxyethylene groups is 50 mol% or more with respect to 100 mol% of all oxyalkylene groups constituting the monomer (a). More preferably, it is 70% or more, more preferably 80% or more, particularly preferably 90% or more, and most preferably 100%.
In addition, when two or more types of oxyalkylene groups are included, the addition form may be added with a block structure, may be added with a random structure, or may be added alternately.

In the general formula (1), R ⁴ is the side chain terminal group represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. Examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkyl group having 1 to 20 carbon atoms (aliphatic alkyl group or alicyclic alkyl group), a phenyl group having 6 to 20 carbon atoms, an alkylphenyl group, and phenylalkyl. Group, an aromatic group having a benzene ring such as a phenyl group substituted with an (alkyl) phenyl group, and a naphthyl group. Among these, from the viewpoint of water solubility, a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms is preferable. More preferably, they are a hydrogen atom or a C1-C5 hydrocarbon group. Among these, a hydrogen atom is more preferable.

In the general formula (1), X represents a divalent alkylene group having 1 to 5 carbon atoms, or when the group represented by R ¹ R ³ C═CR ² — is a vinyl group, It represents that the bonded carbon atom and oxygen atom are directly bonded. Examples of the divalent alkylene group having 1 to 5 carbon atoms include 3-methyl-3-butenyl group, 3-methyl-2-butenyl group, 2-methyl-3-butenyl group, 2-methyl-2-butenyl group Group, 1,1-dimethyl-2-propenyl group, 2-methyl-2-propenyl group and the like. Among these, it is preferable that it is a C1-C2 bivalent alkylene group. More preferred are a 3-methyl-3-butenyl group and a 2-methyl-2-propenyl group.

The monomer (a) represented by the general formula (1) may be a compound having a structure in which a polyalkylene glycol chain is added to an alcohol having an unsaturated group. For example, vinyl alcohol, allyl alcohol, Hydroxybutyl vinyl ether, 2-methyl-2-propen-1-ol, 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-3-buten-2- Adducts obtained by adding alkylene oxide to alkenyl alcohols such as all, 2-methyl-2-buten-1-ol, 2-methyl-3-buten-1-ol, etc., and compounds having alkenyl groups and halogens And a terminal alkyl polyalkylene glycol (for example, allyl chloride and methoxypolyethylene glycol) Etherification reaction) and the like.

As the monomer (a) represented by the general formula (1), specifically, polyethylene glycol monovinyl ether, methoxy polyethylene glycol monovinyl ether, polyethylene glycol monobutyl vinyl ether, polyethylene glycol mono (meth) allyl ether, Methoxy polyethylene glycol mono (meth) allyl ether, polyethylene glycol mono (2-methyl-2-propenyl) ether, polyethylene glycol mono (2-butenyl) ether, polyethylene glycol mono (3-methyl-3-butenyl) ether, polyethylene glycol Mono (3-methyl-2-butenyl) ether, polyethylene glycol mono (2-methyl-3-butenyl) ether, polyethylene glycol mono (2-methyl-2-butenyl) L) ether, polyethylene glycol mono (1,1-dimethyl-2-propenyl) ether, polyethylene polypropylene glycol mono (3-methyl-3-butenyl) ether, methoxy polyethylene glycol mono (3-methyl-3-butenyl) ether, Ethoxy polyethylene glycol mono (3-methyl-3-butenyl) ether, 1-propoxy polyethylene glycol mono (3-methyl-3-butenyl) ether, cyclohexyloxy polyethylene glycol mono (3-methyl-3-butenyl) ether, 1- Octyloxypolyethylene glycol mono (3-methyl-3-butenyl) ether, nonylalkoxypolyethyleneglycol mono (3-methyl-3-butenyl) ether, laurylalkoxypolyethylene Cole mono (3-methyl-3-butenyl) ether, stearyl alkoxy polyethylene glycol mono (3-methyl-3-butenyl) ether, phenoxy polyethylene glycol mono (3-methyl-3-butenyl) ether, naphthoxy polyethylene glycol mono ( 3-methyl-3-butenyl) ether, methoxy polyethylene glycol monoallyl ether, ethoxy polyethylene glycol monoallyl ether, phenoxy polyethylene glycol monoallyl ether, methoxy polyethylene glycol mono (2-methyl-2-propenyl) ether, ethoxy polyethylene glycol mono (2-Methyl-2-propenyl) ether and phenoxypolyethylene glycol mono (2-methyl-2-propenyl) ether are preferred. . Among these, polyethylene glycol mono (2-methyl-2-propenyl) ether and polyethylene glycol mono (3-methyl-3-butenyl) ether are more preferable, and polyethylene glycol mono (3-methyl-) is more preferable. 3-butenyl) ether.

In the general formula (2) representing the monomer (b), the average added mole number p of the oxyalkylene group represented by-(R ^a O) p- is suitably 2 to 300. If it is less than 2, the hydrophobicity becomes too strong and uniform polymerization cannot be performed, and there is a possibility that the effect as a cement admixture cannot be sufficiently exhibited. Moreover, when it exceeds 300, polymerizability will fall large and there exists a possibility that the usage-amount of a cement admixture may be needed in large quantities. The lower limit value of p is preferably 3, more preferably 4, and the upper limit value is preferably 200, more preferably 150, still more preferably 120.

In the general formula (2), the oxyalkylene group represented by R ^a O is an oxyalkylene group having 2 to 5 carbon atoms. For example, an oxyethylene group, an oxypropylene group, an oxybutylene group, and an oxyisobutylene Group, etc., and an oxyethylene group and an oxypropylene group are preferable. Especially, it is especially preferable that an oxyethylene group is a main component from a viewpoint of the balance of hydrophilic property and hydrophobicity. Specifically, it is preferable that the proportion of oxyethylene groups is 50 mol% or more with respect to 100 mol% of all oxyalkylene groups constituting the monomer (b). More preferably, it is 70% or more, more preferably 80% or more, particularly preferably 90% or more, and most preferably 100%.
In addition, when two or more types of oxyalkylene groups are included, the addition form may be added with a block structure, may be added with a random structure, or may be added alternately.

In the above formula (2), R ⁶ is the side chain terminal group represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. Examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkyl group having 1 to 20 carbon atoms (aliphatic alkyl group or alicyclic alkyl group), a phenyl group having 6 to 20 carbon atoms, an alkylphenyl group, and phenylalkyl. Group, an aromatic group having a benzene ring such as a phenyl group substituted with an (alkyl) phenyl group, and a naphthyl group. Among these, it is preferable that it is a C1-C10 hydrocarbon group or a hydrogen atom from the point of the water solubility of a copolymer, and a cement dispersibility. A hydrocarbon group having 10 or less carbon atoms is more preferable, a hydrocarbon group having 3 or less carbon atoms is more preferable, and a hydrocarbon group having 2 or less carbon atoms is particularly preferable. Of the hydrocarbon groups, a saturated alkyl group and an unsaturated alkyl group are preferable. These alkyl groups may be linear or branched. Of these, a methyl group is most preferred.

The monomer (b) represented by the general formula (2) may be a compound (monomer) having a structure in which an unsaturated group and a polyalkylene glycol chain are bonded via an ester bond. For example, unsaturated carboxylic acid polyalkylene glycol ester compounds are suitable. Among these, (alkoxy) polyalkylene glycol mono (meth) acrylic acid ester is particularly suitable.

Specific examples of the monomer (b) represented by the general formula (2) include methoxypolyethylene glycol mono (meth) acrylate, methoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate, methoxy {Polyethylene glycol (poly) butylene glycol} mono (meth) acrylate, methoxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, ethoxy polyethylene glycol mono (meth) acrylate, ethoxy {polyethylene glycol ( Poly) propylene glycol} mono (meth) acrylate, ethoxy {polyethylene glycol (poly) butylene glycol} mono (meth) acrylate, ethoxy {polyethylene glycol Poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, propoxypolyethylene glycol mono (meth) acrylate, propoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate, propoxy {polyethylene glycol (poly) butylene glycol } Mono (meth) acrylate, propoxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, butoxy polyethylene glycol mono (meth) acrylate, butoxy {polyethylene glycol (poly) propylene glycol} mono (meta ) Acrylate, butoxy {polyethylene glycol (poly) butylene glycol} mono (meth) acrylate, butyl Xy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, pentoxypolyethylene glycol mono (meth) acrylate, pentoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate, pentoxy {polyethylene Glycol (poly) butylene glycol} mono (meth) acrylate, pentoxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, hexoxypolyethylene glycol mono (meth) acrylate, hexoxy {polyethylene glycol (poly ) Propylene glycol} mono (meth) acrylate, hexoxy {polyethylene glycol (poly) butylene glyco Mono} (meth) acrylate, hexoxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, heptoxypolyethylene glycol mono (meth) acrylate, heptoxy {polyethylene glycol (poly) propylene glycol} Mono (meth) acrylate, heptoxy {polyethylene glycol (poly) butylene glycol} mono (meth) acrylate, heptoxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, octoxypolyethylene glycol mono (meta) ) Acrylate, octoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate, octoxy {polyethylene Lenglycol (poly) butylene glycol} mono (meth) acrylate, octoxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, nonanoxy polyethylene glycol mono (meth) acrylate, nonanoxy {polyethylene glycol ( Poly) propylene glycol} mono (meth) acrylate, nonanoxy {polyethylene glycol (poly) butylene glycol} mono (meth) acrylate, nonanoxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, etc. It is done.

As the above (alkoxy) polyalkylene glycol mono (meth) acrylic acid ester, in addition to the above-described compounds, phenoxy polyethylene glycol mono (meth) acrylate, phenoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate, Phenoxy {polyethylene glycol (poly) butylene glycol} mono (meth) acrylate, phenoxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate, (meth) allyloxypolyethylene glycol mono (meth) acrylate, (Meth) allyloxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate, (meth) allyloxy {polyethylene glycol Le (poly) butylene glycol} mono (meth) acrylate, (meth) allyloxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate.
Among these, the monomer (b) is more preferably methoxypolyethylene glycol mono (meth) acrylate or methoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate, and more preferably methoxypolyethylene. Glycol mono (meth) acrylate.

In the general formula (3) representing the monomer (c), the average added mole number q of the oxyalkylene group represented by-(R ^a O) q- is suitably 0-1. M represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a metal atom, an ammonium group, or an organic ammonium group. Accordingly, the monomer (c) is an unsaturated monocarboxylic acid monomer (c-1) in which q = 0 and M is a hydrogen atom, a metal atom, an ammonium group or an organic ammonium group, and Q = 0, M is an alkyl group having 1 to 5 carbon atoms, and an unsaturated monocarboxylic acid ester monomer (c-2), and q = 1, M is a hydrogen atom, a metal atom, An unsaturated monocarboxylic acid alkylene glycol ester monomer (c-3) which is an ammonium group or an organic ammonium group, and an alkoxy unsaturated group where q = 1 and M is an alkyl group having 1 to 5 carbon atoms And monocarboxylic acid alkylene glycol ester monomer (c-4).
In addition, since the unsaturated monocarboxylic acid monomer (c-1) contains an adsorbing group for dispersing cement particles, it is preferable to always use it. Moreover, when using 1 or more types of unsaturated monocarboxylic acid ester monomers (c-2) to (c-4), they are used in combination with unsaturated monocarboxylic acid monomers (c-1). It is preferred to use.

When M in the unsaturated monocarboxylic acid monomer (c-1) and unsaturated monocarboxylic acid alkylene glycol ester monomer (c-3) is a metal atom, the metal atom is lithium. Preferred are monovalent metal atoms such as alkali metal atoms such as sodium and potassium; divalent metal atoms such as alkaline earth metal atoms such as calcium and magnesium; and trivalent metal atoms such as aluminum and iron. When M is an organic ammonium group, examples of the organic ammonium group include alkanolamines such as ethanolamine group (ethanolammonium group), diethanolamine group (diethanolammonium group), and triethanolamine group (triethanolammonium group). A group (alkanolammonium group) and a triethylamine group (triethylammonium group) are preferable.

When M in the unsaturated monocarboxylic acid ester monomer (c-2) and alkoxy unsaturated monocarboxylic acid alkylene glycol ester monomer (c-4) is an alkyl group having 1 to 5 carbon atoms Is preferably a methyl group, an ethyl group, a propyl group, or a butyl group as the alkyl group having 1 to 5 carbon atoms.

Examples of the unsaturated monocarboxylic acid monomer (c-1) include acrylic acid, methacrylic acid, crotonic acid, and the like, and monovalent metal salts, divalent metal salts, ammonium salts, and organic ammonium salts thereof. Can be mentioned. Among these, acrylic acid, methacrylic acid, and their monovalent metal salts, divalent metal salts, ammonium salts, and organic ammonium salts are particularly preferable from the viewpoint of improving cement dispersion performance.

As the unsaturated monocarboxylic acid ester monomer (c-2), for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate and the like are suitable. Among these, it is particularly preferable that either ethyl acrylate or butyl acrylate is used.

As the unsaturated monocarboxylic acid alkylene glycol ester monomer (c-3), for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and the like are suitable. Among these, 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate are particularly preferable.

Examples of the alkoxy unsaturated monocarboxylic acid alkylene glycol ester monomer (c-4) include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, and 2-propoxyethyl (meth) acrylate. 2-methoxypropyl (meth) acrylate, 2-ethoxypropyl (meth) acrylate and the like are preferable. Among these, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are particularly preferable.

The monomer component used in the production method of the present invention may further contain a monomer (d) other than the monomers (a) to (c). Specific examples of such a monomer (d) include maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid and their monovalent metal salts, divalent metal salts, ammonium salts, and organic amines. Unsaturated dicarboxylic acid monomers such as salts; half esters and diesters of the unsaturated dicarboxylic acid monomers and alcohols having 1 to 30 carbon atoms; the unsaturated dicarboxylic acid monomers and carbon atoms 1 Alkyl (poly) alkylene glycol obtained by adding 1 to 500 moles of alkylene oxide having 2 to 18 carbon atoms to alcohol having 1 to 30 carbon atoms or amine having 1 to 30 carbon atoms And half esters and diesters of the above unsaturated dicarboxylic acid monomers; the above unsaturated dicarboxylic acid monomers and glycols having 2 to 18 carbon atoms or 2 to 2 carbon atoms Half-esters and diesters of polyalkylene glycols having 2 to 500 moles of addition of 8 glycols; polyalkylenes having 2 to 500 moles of addition of maleamic acid and glycols having 2 to 18 carbon atoms or glycols having 2 to 18 carbon atoms Half-amides with glycol; 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 (Poly) alkylene glycol di (meth) acrylates; bifunctional (meth) acrylates such as hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate Relates; (poly) alkylene glycol dimaleates such as triethylene glycol dimaleate and polyethylene glycol dimaleate; vinyl sulfonate, (meth) allyl sulfonate, 2- (meth) acryloxyethyl sulfonate, 3- (meth) acryloxy Propyl sulfonate, 3- (meth) acryloxy-2-hydroxypropyl sulfonate, 3- (meth) acryloxy-2-hydroxypropyl sulfophenyl ether, 3- (meth) acryloxy-2-hydroxypropyloxysulfobenzoate, 4- (meta ) Acryloxybutyl sulfonate, (meth) acrylamide methylsulfonic acid, (meth) acrylamide ethylsulfonic acid, 2-methylpropanesulfonic acid (meth) acrylamide, styrenesulfonic acid, etc. Unsaturated sulfonic acids and their monovalent metal salts, divalent metal salts, ammonium salts, organic amine salts; amides of unsaturated monocarboxylic acids such as methyl (meth) acrylamide and amines having 1 to 30 carbon atoms; Vinyl aromatics such as styrene, α-methylstyrene, vinyltoluene, and p-methylstyrene; dienes such as butadiene, isoprene, 2-methyl-1,3-butadiene, and 2-chloro-1,3-butadiene; Unsaturated amides such as (meth) acrylamide, (meth) acrylalkylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide; Unsaturated cyanides such as (meth) acrylonitrile and α-chloroacrylonitrile Unsaturated esters such as vinyl acetate and vinyl propionate; aminoethyl (meth) acrylate , Unsaturated amines such as methylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, dibutylaminoethyl (meth) acrylate, vinylpyridine, and the like; Divinyl aromatics; cyanurates such as triallyl cyanurate; allyls such as (meth) allyl alcohol and glycidyl (meth) allyl ether; unsaturated amino compounds such as dimethylaminoethyl (meth) acrylate; polydimethylsiloxanepropyl Aminomaleamic acid, polydimethylsiloxane aminopropylaminomaleamic acid, polydimethylsiloxane-bis- (propylaminomaleamic acid), polydimethylsiloxane-bis- (dipropyleneaminomaleamic acid), Ridimethylsiloxane- (1-propyl-3-acrylate), polydimethylsiloxane- (1-propyl-3-methacrylate), polydimethylsiloxane-bis- (1-propyl-3-acrylate), polydimethylsiloxane-bis- Examples thereof include siloxane derivatives such as (1-propyl-3-methacrylate), and one or more of these can be used. Among these, as the monomer (d), it is preferable to use unsaturated dicarboxylic acid monomers such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid and salts thereof, and more preferable. Is to use α, β-unsaturated dicarboxylic acid-based monomers such as maleic acid, maleic anhydride, fumaric acid, citraconic acid and their salts.

Suitable combinations of monomer components used in the production method of the present invention include the following combinations. Note that the present invention is not limited to these.
(1) Combination of monomer (a) and monomer (c-1) (2) Combination of monomer (b) and monomer (c-1) (3) Monomer A combination of (a), monomer (c-1) and monomer (c-2) (4) monomer (b), monomer (c-1) and monomer Combination with (c-2) (5) Combination of monomer (a), monomer (c-1) and monomer (c-3) (6) Monomer (b) A combination of the monomer (c-1) and the monomer (c-3) (7) the monomer (a), the monomer (c-1) and the monomer (c-4) (8) Combination of monomer (b), monomer (c-1) and monomer (c-4) (9) Monomer (a) and monomer A combination of (c-1), monomer (c-3) and monomer (d) (10) monomer (b) and monomer (c-1) The combination of the monomer (c-3), the monomer (d)

Among the above combinations, use the monomer (a) and do not use the monomer (b), and use any combination of (1), (3), (5), (7) and (9). Is more preferable. When the polycarboxylic acid copolymer is produced by the production method of the present invention using the monomer component (a) as the monomer component and the monomer component not using the monomer (b), more physical properties are obtained. A polycarboxylic acid copolymer with little variation can be stably produced. Among these, a more preferable combination is any one of (1), (5), and (7), and a particularly preferable combination is any one of (1) and (5).

The polycarboxylic acid copolymer in the present invention can be obtained by copolymerizing monomer components as described above. The molecular weight of the copolymer is 1,000 to 500,000. It is preferable. When the weight average molecular weight is 1000 to 500,000, the water reducing performance and slump loss preventing ability of the copolymer can be made sufficient. More preferably, it is 5000-300000, More preferably, it is 8000-100,000.
The weight average molecular weight of the polycarboxylic acid copolymer can be measured as a molecular weight in terms of polyethylene glycol under the following measurement conditions by, for example, gel permeation chromatography (hereinafter referred to as “GPC”).
Measurement condition:
Column TSKguardcolumn SWXL + TSKge1 G4000SWXL + G3000SWXL + G2000SWXL (manufactured by Tosoh Corporation)
Eluent solution: 115.6 g of sodium acetate trihydrate dissolved in a mixed solvent of 10999 g of water and 6001 g of acetonitrile, and further adjusted to pH 6.0 with acetic acid. 0.5% eluent solution 100 μL
Eluent flow rate 0.8mL / min
Column temperature 40 ° C
Standard substance Polyethylene glycol (Top peak molecular weight (Mp): 272500, 219300, 85000, 46000, 24000, 12600, 4250, 7100, 1470)
Calibration curve order Tertiary detector 410 Differential refraction detector (trade name, manufactured by Japan Waters)
Analysis software MILLENNIUM Ver. 3.21 (trade name, manufactured by Waters, Japan)

The content ratio of the polymer components of trimers or more of the polycarboxylic acid copolymer (also referred to as “polymer” in the present specification) is preferably 50% or more. When the polymer content is less than 50%, there are extremely few effective components that make the copolymer sufficiently water-reducing performance and slump loss prevention ability, and the effect as a cement dispersant may be lost. More preferably, it is 60% or more, still more preferably 70% or more, and particularly preferably 80% or more.
The polymer content of the polycarboxylic acid copolymer is determined from, for example, the monomer (a) and / or single monomer from the GPC chart when the GPC measurement of the polycarboxylic acid copolymer is performed as described above. The peak area of the portion corresponding to the molecular weight of the monomer (b) (hereinafter referred to as “Peak I”), the peak of the lowest molecule (hereinafter referred to as “Peak II”) on the polymer side of Peak I The peak area and the peak area of all the peaks (hereinafter referred to as “peak III”) on the polymer side relative to peak II can be obtained and calculated by the following formula.
Polymer content (%) = [(Area of peak III) / {(Area of peak I) + (Area of peak II) + (Area of peak III)}] × 100

The polycarboxylic acid copolymer for cement admixture obtained by the production method of the present invention can be used as it is as a main component of the cement admixture, but if necessary, it is further neutralized with an alkaline substance. May be. As the alkaline substance, it is preferable to use inorganic salts such as hydroxides, chlorides and carbonates of monovalent metals and divalent metals; ammonia; organic amines.
A polycarboxylic acid copolymer for cement admixture produced by such a production method of the present invention and a cement admixture containing the polycarboxylic acid copolymer for cement admixture are also included in 1 of the present invention. One.

The cement admixture can be used in addition to cement compositions such as cement paste, mortar and concrete, and can also be used for ultra high strength concrete. Thus, the cement composition containing the cement admixture of the present invention is also one aspect of the present invention.
As the cement composition, those usually used including cement, water, fine aggregate, coarse aggregate and the like are suitable. Moreover, what added fine powders, such as fly ash, blast furnace slag, a silica fume, and a limestone fine powder, may be used.

As the cement, portland cement such as normal, early strength, super early strength, moderate heat, white, etc .; mixed portland cement such as alumina cement, fly ash cement, blast furnace cement, silica cement and the like can be used.
The unit water amount per 1 m ^{3 of the} cement composition and the water / cement ratio can be within the range normally used. For example, in order to produce highly durable and high-strength concrete, the unit water amount is 100 to 100%. 185 kg / m ³ , water / cement ratio = 10 to 70%.
The volume ratio of the fine aggregate can be a range that is usually used, but for example, it can be 45 to 60% in order to produce high durability and high strength concrete.
The volume ratio of fine aggregate represents the volume of fine aggregate with respect to the total volume of fine aggregate and coarse aggregate.

As a method for evaluating the performance of mortar or concrete produced using the cement composition, there is a slump flow value that is a general index representing the flowability of fresh concrete. When the amount of the cement admixture added to the cement composition is increased, the cement dispersibility is increased, so that the slump flow value is increased. However, increasing the amount of cement additive increases the cost, so that it is required to obtain the fluidity required for mortar or concrete with the smallest possible amount.
From the above, when the slump flow value of various mortars or concretes manufactured by changing only the type of cement admixture with a constant amount of cement admixture added to the cement composition, the slump flow value The higher the value, the better the performance of the cement admixture.

The method for producing a polycarboxylic acid copolymer for cement admixture of the present invention has the above-described configuration, and even if a reducing substance is mixed in the reaction system of the copolymerization reaction, the influence on the polymerization behavior is sufficient. It is a production method capable of producing a polycarboxylic acid copolymer suitable for a cement admixture because a polycarboxylic acid copolymer with little variation in physical properties can be stably synthesized. .

FIG. 1 is a graph showing the relationship between the amount of hydrogen peroxide added in Production Examples 1 to 12 and the weight average molecular weight of the resulting copolymer. FIG. 2 is a graph showing the relationship between the amount of hydrogen peroxide added in Production Examples 1 to 12 and the polymer content of the resulting copolymer. FIG. 3 is a graph showing the relationship between the amount of hydrogen peroxide added in Production Example 1 to Production Example 12 and the slump flow value of concrete produced using the resulting copolymer. FIG. 4 is a graph showing the relationship between the amount of hydrogen peroxide added in Production Example 13 to Production Example 18 and the weight average molecular weight of the resulting copolymer. FIG. 5 is a graph showing the relationship between the amount of hydrogen peroxide added in Production Example 13 to Production Example 18 and the polymer content of the resulting copolymer. FIG. 6 is a graph showing the relationship between the amount of hydrogen peroxide added in Production Example 13 to Production Example 18 and the slump flow value of mortar produced using the obtained copolymer.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

In the following production examples, measurement was performed as follows, and evaluation was performed using the following calculation formula.
(1) A diluted hydrochloric acid solution was prepared by using 20% hydrochloric acid (for precision analysis = iron-free hydrochloric acid) commercially available as a quantitative reagent for iron ions in pure water. Using this, a sample solution in which the measurement sample was diluted 20 to 30 times was prepared. Using an ICP (inductively coupled plasma) mass spectrometer, the peak area detected at an iron wavelength of 259.9 nm was analyzed using a calibration curve, and the amount of iron ions contained in the sample was calculated. The calibration curve was prepared by using 1000 ppm of an atomic absorption iron standard solution commercially available as a reagent, and preparing a sample solution adjusted to have a concentration of 1000, 500, 100, or 30 ppb using a hydrochloric acid diluent. An ICP mass spectrometer was used to prepare a peak area detected at an iron wavelength of 259.9 nm.
(2) Measurement of weight average molecular weight of polycarboxylic acid copolymer The measurement was performed under the following GPC measurement conditions.
Measurement condition:
Column TSKguardcolumn SWXL + TSKge1 G4000SWXL + G3000SWXL + G2000SWXL (manufactured by Tosoh Corporation)
Eluent solution: 115.6 g of sodium acetate trihydrate dissolved in a mixed solvent of 10999 g of water and 6001 g of acetonitrile, and further adjusted to pH 6.0 with acetic acid. 0.5% eluent solution 100 μL
Eluent flow rate 0.8mL / min
Column temperature 40 ° C
Standard substance Polyethylene glycol (Top peak molecular weight (Mp): 272500, 219300, 85000, 46000, 24000, 12600, 4250, 7100, 1470)
Calibration curve order Tertiary detector 410 Differential refraction detector (trade name, manufactured by Japan Waters)
Analysis software MILLENNIUM Ver. 3.21 (trade name, manufactured by Waters, Japan)
(3) Content ratio of polymer component of trimer or higher (hereinafter also referred to as “polymer component”)
From the GPC chart obtained when measuring the weight average molecular weight of the polycarboxylic acid copolymer of (2) above, the peak corresponding to the molecular weight of a 50-methyl adduct of 3-methyl-3-buten-1-ol in ethylene oxide Peak area (hereinafter referred to as “Peak 1”), which is on the polymer side of Peak 1 and is the lowest molecule (hereinafter referred to as “Peak 2”), and higher than Peak 2 The peak areas of all the peaks on the side (hereinafter referred to as “peak 3”) were obtained and calculated according to the following formula.
Polymer content (%) = [(Area of peak 3) / {(Area of peak 1) + (Area of peak 2) + (Area of peak 3)}] × 100
(4) Volume ratio of fine aggregate Calculated by the following formula.
Fine Aggregate Volume Ratio (%) = [(Fine Aggregate Volume) / {(Fine Aggregate Volume) + (Coarse Aggregate Volume)}] × 100

<Production of polycarboxylic acid-based copolymer>
(Production Example 1)
An 80% aqueous solution of 3-methyl-3-buten-1-ol ethylene oxide 50 mol adduct was prepared, and the content of iron ions contained in the aqueous solution was analyzed by ICP mass spectrometry. As a result, the iron ion content was 85 ppb. A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introducing tube, and a cooling tube, 1223 g of the aqueous solution (hereinafter referred to as “80% aqueous solution of IPN-50A”), 1.8 g of acrylic acid, and 300 g of ion-exchanged water The temperature was raised to 58 ° C. Subsequently, 30 g of an aqueous solution containing 4.7 g of 35% hydrogen peroxide was added all at once, and then 270 g of an aqueous solution prepared by dissolving 66.4 g of acrylic acid and 118.6 g of 2-hydroxyethyl acrylate was added in 3 hours to L-ascorbic acid 2 175 g of an aqueous solution in which .1 g and 5.6 g of 3-mercaptopropionic acid were dissolved was simultaneously added dropwise at a constant rate for 3.5 hours. After completion of all the additions, stirring was continued for another 2 hours, and then an aqueous sodium hydroxide solution and ion-exchanged water for adjusting the concentration were added to obtain a pH of 5.5, a solid content concentration of 45%, a weight average molecular weight of 26300, and a polymer content of 81. An aqueous solution of 1% polycarboxylic acid copolymer (1) -A1 was obtained.

(Production Example 2)
A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube and a cooling tube was charged with 300 g of ion exchange water, 1223 g of an 80% aqueous solution of IPN-50A, and 1.8 g of acrylic acid, and the temperature was raised to 58 ° C. Subsequently, 30 g of an aqueous solution containing 0.7 g of 35% hydrogen peroxide was added all at once, and then 270 g of an aqueous solution in which 66.4 g of acrylic acid and 118.6 g of 2-hydroxyethyl acrylate had been dissolved was added in 3 hours to 0 L-ascorbic acid. 175 g of an aqueous solution in which .63 g and 5.6 g of 3-mercaptopropionic acid were dissolved was simultaneously added dropwise at a constant rate in 3.5 hours. After completion of the dropwise addition, stirring was continued for another 2 hours, and then an aqueous sodium hydroxide solution and ion-exchanged water for adjusting the concentration were added to obtain a pH of 5.5, a solid content concentration of 45%, a weight average molecular weight of 23400, and a polymer content of 80. An aqueous solution of 6% polycarboxylic acid copolymer (1) -A2 was obtained.

(Production Example 3)
A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube and a cooling tube was charged with 190 g of ion-exchanged water, 1223 g of an 80% aqueous solution of IPN-50A, and 1.8 g of acrylic acid, and the temperature was raised to 58 ° C. Subsequently, 235 g of an aqueous solution in which 66.4 g of acrylic acid and 118.6 g of 2-hydroxyethyl acrylate were dissolved was added in 3 hours, and 175 g of an aqueous solution in which 4.7 g of 35% hydrogen peroxide was dissolved was added in 3.5 hours. -175 g of an aqueous solution in which 2.1 g of ascorbic acid and 5.6 g of 3-mercaptopropionic acid were dissolved was dropped simultaneously at a constant rate for 3.5 hours. After completion of all the additions, stirring was continued for another 2 hours, and then an aqueous sodium hydroxide solution and ion-exchanged water for adjusting the concentration were added to obtain a pH of 5.5, a solid content concentration of 45%, a weight average molecular weight of 25900, and a polymer content of 82. A 4% aqueous solution of polycarboxylic acid copolymer (1) -A3 was obtained.

(Production Example 4)
A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube and a cooling tube was charged with 190 g of ion exchange water, 1223 g of an 80% aqueous solution of IPN-50A, and 1.8 g of acrylic acid, and the temperature was raised to 58 ° C. Subsequently, 235 g of an aqueous solution in which 66.4 g of acrylic acid and 118.6 g of 2-hydroxyethyl acrylate were dissolved was added in 3 hours, and 175 g of an aqueous solution in which 2.33 g of 35% hydrogen peroxide was dissolved in 3.5 hours. -175 g of an aqueous solution in which 2.11 g of ascorbic acid and 5.6 g of 3-mercaptopropionic acid were dissolved was dropped simultaneously at a constant rate for 3.5 hours. After completion of all the additions, stirring was further continued for 2 hours, and then an aqueous sodium hydroxide solution and ion-exchanged water for adjusting the concentration were added to obtain a pH of 5.5, a solid content concentration of 45%, a weight average molecular weight of 25700, and a polymer content of 82. An aqueous solution of 4% polycarboxylic acid copolymer (1) -A4 was obtained.

(Production Example 5)
A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube and a cooling tube was charged with 190 g of ion-exchanged water, 1223 g of an 80% aqueous solution of IPN-50A, and 1.8 g of acrylic acid, and the temperature was raised to 58 ° C. Subsequently, 235 g of an aqueous solution in which 66.4 g of acrylic acid and 118.6 g of 2-hydroxyethyl acrylate were dissolved was added in 3 hours, and 175 g of an aqueous solution in which 1.16 g of 35% hydrogen peroxide was dissolved was added in 3.5 hours. -175 g of an aqueous solution in which 1.06 g of ascorbic acid and 5.6 g of 3-mercaptopropionic acid were dissolved was added dropwise simultaneously at a constant rate for 3.5 hours. After completion of all the additions, stirring was continued for another 2 hours, and then an aqueous sodium hydroxide solution and ion-exchanged water for adjusting the concentration were added to obtain a pH of 5.5, a solid content concentration of 45%, a weight average molecular weight of 25100, and a polymer content of 81. An aqueous solution of 0.0% polycarboxylic acid copolymer (1) -A5 was obtained.

(Production Example 6)
A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube and a cooling tube was charged with 190 g of ion-exchanged water, 1223 g of an 80% aqueous solution of IPN-50A, and 1.8 g of acrylic acid, and the temperature was raised to 58 ° C. Subsequently, 235 g of an aqueous solution in which 66.4 g of acrylic acid and 118.6 g of 2-hydroxyethyl acrylate were dissolved was added in 3 hours, and 175 g of an aqueous solution in which 0.70 g of 35% hydrogen peroxide was dissolved was added in 3.5 hours. -175 g of an aqueous solution in which 0.63 g of ascorbic acid and 5.6 g of 3-mercaptopropionic acid were dissolved was dropped simultaneously at a constant rate for 3.5 hours. After completion of all the additions, stirring was further continued for 2 hours, and then an aqueous sodium hydroxide solution and ion-exchanged water for adjusting the concentration were added to obtain a pH of 5.5, a solid content concentration of 45%, a weight average molecular weight of 24500, and a polymer content of 81. A 4% aqueous solution of polycarboxylic acid copolymer (1) -A6 was obtained.

(Production Example 7)
An 80% aqueous solution of 3-methyl-3-buten-1-ol ethylene oxide 50 mol adduct was prepared, and the content of iron ions contained in the aqueous solution was analyzed by ICP mass spectrometry. As a result, the content of iron ions was 620 ppb. The same aqueous solution (hereinafter referred to as “80% aqueous solution of IPN-50B”) was used in the same apparatus and operation as in Production Example 1 except that the 80% aqueous solution of IPN-50A was used. Thus, an aqueous solution of polycarboxylic acid copolymer (1) -B1 having a pH of 5.5, a solid content concentration of 45%, a weight average molecular weight of 29300, and a polymer content of 83.8% was obtained.

(Production Example 8)
By using the same apparatus and operation as in Production Example 2 and using the same amount of raw material except that an 80% aqueous solution of IPN-50B is used instead of an 80% aqueous solution of IPN-50A, PH5. 5. An aqueous solution of polycarboxylic acid copolymer (1) -B2 having a solid content concentration of 45%, a weight average molecular weight of 25100, and a polymer content of 82.7% was obtained.

(Production Example 9)
By using the same apparatus and operation as in Production Example 3 and using the same amount of raw material except that an 80% aqueous solution of IPN-50B is used instead of an 80% aqueous solution of IPN-50A, PH5. 5. An aqueous solution of polycarboxylic acid copolymer (1) -B3 having a solid content concentration of 45%, a weight average molecular weight of 28900, and a polymer content of 84.2% was obtained.

(Production Example 10)
By using the same apparatus and operation as in Production Example 4 and using the same amount of raw material except that an 80% aqueous solution of IPN-50B is used instead of an 80% aqueous solution of IPN-50A, PH5. 5. An aqueous solution of polycarboxylic acid copolymer (1) -B4 having a solid content concentration of 45%, a weight average molecular weight of 28800, and a polymer content of 83.5% was obtained.

(Production Example 11)
By using the same apparatus and operation as in Production Example 5 and using the same amount of raw material except that an 80% aqueous solution of IPN-50B is used instead of an 80% aqueous solution of IPN-50A, PH5. 5. An aqueous solution of polycarboxylic acid copolymer (1) -B5 having a solid content concentration of 45%, a weight average molecular weight of 26600, and a polymer content of 82.2% was obtained.

(Production Example 12)
By using the same apparatus and operation as in Production Example 6 and using the same amount of raw material except that an 80% aqueous solution of IPN-50B is used instead of an 80% aqueous solution of IPN-50A, PH5. 5. An aqueous solution of polycarboxylic acid copolymer (1) -B6 having a solid content concentration of 45%, a weight average molecular weight of 24700, and a polymer content of 81.5% was obtained.

(Production Example 13)
A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube and a cooling tube was charged with 311 g of ion exchange water, 1262 g of an 80% aqueous solution of IPN-50A, and 1.8 g of acrylic acid, and the temperature was raised to 60 ° C. Subsequently, 30 g of an aqueous solution containing 4.5 g of 35% hydrogen peroxide was added all at once, and then 220 g of an aqueous solution in which 134.6 g of acrylic acid was dissolved was added in 2.1 hours to 2.1 g of L-ascorbic acid and 3-mercaptopropionic acid. 175 g of an aqueous solution in which 4.0 g was dissolved was dropped simultaneously at a constant rate for 3.5 hours. After completion of all the additions, stirring was further continued for 2 hours, and then an aqueous sodium hydroxide solution and ion-exchanged water for adjusting the concentration were added, PH 6.5, solid content concentration 45%, weight average molecular weight 32400, polymer content 81 An aqueous solution of 1% polycarboxylic acid copolymer (2) -A1 was obtained.

(Production Example 14)
A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube and a cooling tube was charged with 251 g of ion exchange water, 1262 g of an 80% aqueous solution of IPN-50A, and 1.8 g of acrylic acid, and the temperature was raised to 60 ° C. Subsequently, 235 g of an aqueous solution in which 134.6 g of acrylic acid was dissolved was added in 3 hours, 125 g of an aqueous solution in which 4.54 g of 35% hydrogen peroxide was dissolved was added in 3.5 hours, and 2.1 g of L-ascorbic acid and 3- 125 g of an aqueous solution in which 4.0 g of mercaptopropionic acid was dissolved was dropped simultaneously at a constant rate for 3.5 hours. After completion of all the drippings, stirring was further continued for 2 hours, and then an aqueous sodium hydroxide solution and ion-exchanged water for adjusting the concentration were added, PH 6.5, solid content concentration 45%, weight average molecular weight 33800, polymer content 82. An aqueous solution of 4% polycarboxylic acid copolymer (2) -A2 was obtained.

(Production Example 15)
A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube and a cooling tube was charged with 251 g of ion exchange water, 1262 g of an 80% aqueous solution of IPN-50A, and 1.8 g of acrylic acid, and the temperature was raised to 60 ° C. Subsequently, 235 g of an aqueous solution in which 134.6 g of acrylic acid was dissolved was added in 3 hours, 125 g of an aqueous solution in which 0.68 g of 35% hydrogen peroxide was dissolved was added in 3.5 hours, and 0.62 g of L-ascorbic acid and 3- 125 g of an aqueous solution in which 4.0 g of mercaptopropionic acid was dissolved was dropped simultaneously at a constant rate for 3.5 hours. After completion of all the additions, stirring was further continued for 2 hours, and then an aqueous sodium hydroxide solution and ion-exchanged water for adjusting the concentration were added, PH 6.5, solid content concentration 45%, weight average molecular weight 29300, polymer content 81 An aqueous solution of 4% polycarboxylic acid copolymer (2) -A3 was obtained.

(Production Example 16)
As a result of preparing an 80% aqueous solution of 3-methyl-3-buten-1-ol ethylene oxide 50 mol adduct and analyzing the content of iron ions contained in the aqueous solution by ICP mass spectrometry, the content of iron ions was 1110 ppb. The same aqueous solution (hereinafter referred to as “80% aqueous solution of IPN-50C”) was used in place of the 80% aqueous solution of IPN-50A. Thus, an aqueous solution of polycarboxylic acid copolymer (2) -B1 having a pH of 6.5, a solid content concentration of 45%, a weight average molecular weight of 41300, and a polymer content of 83.8% was obtained.

(Production Example 17)
By using the same apparatus and operation as in Production Example 14 and using the same amount of raw material, except that an 80% aqueous solution of IPN-50C is used instead of an 80% aqueous solution of IPN-50A, PH6. 5. An aqueous solution of polycarboxylic acid copolymer (2) -B2 having a solid content concentration of 45%, a weight average molecular weight of 42900, and a polymer content of 81.5% was obtained.

(Production Example 18)
By using the same apparatus and operation as in Production Example 15 and using the same amount of raw material, except that an 80% aqueous solution of IPN-50C is used instead of an 80% aqueous solution of IPN-50A, PH6. 5. An aqueous solution of polycarboxylic acid copolymer (2) -B3 having a solid content concentration of 45%, a weight average molecular weight of 31,500, and a polymer content of 81.5% was obtained.
Regarding the aqueous solution of the polycarboxylic acid copolymer obtained in Production Examples 1 to 18, the monomer composition of the copolymer is summarized in Table 1.
Abbreviations in Table 1 are as follows.
Monomer composition (wt%): wt% of each monomer used for polymerization
IPN-50: Ethylene oxide 50 mol adduct of 3-methyl-3-buten-1-ol SA: Sodium acrylate (In the production example, acrylic acid is used, but in calculating the monomer composition, sodium acrylate conversion Went on.)
HEA: 2-hydroxyethyl acrylate

Further, Production Example 1 to Production Example 12 are summarized in Table 2, and Production Example 13 to Production Example 18 are summarized in Table 3.
Abbreviations in Table 2 and Table 3 are as follows.
Iron content: The content of iron ions contained in the 80% aqueous solution of IPN-50A, the 80% aqueous solution of IPN-50B or the 80% aqueous solution of IPN-50C used. Amount of initiator: All the constituents of the polycarboxylic acid copolymer monomer component 100 moles moles of initiator to percentage _H 2 _{O 2:} Hydrogen peroxide L-the as: L-ascorbic acid Mw: weight-average molecular weight P content of the copolymer: trimer copolymer Content ratio of the above polymer components

(Examples 1-4, Comparative Examples 1-8)
<Concrete test>
Ordinary Portland cement (manufactured by Sumitomo Osaka Cement) as cement, mountain sand from Kimitsu (FM = 2.64) as fine aggregate, Ome hard sandstone crushed stone as coarse aggregate (5-10mm / 10-15mm / 15- 20 mm = 3/3/4 mixed and used). A concrete test was conducted using the aqueous solution of the polycarboxylic acid copolymer obtained in Production Example 1 to Production Example 12 as a cement admixture. The concrete mixing conditions were as shown in Table 4 below.
Abbreviations in Table 4 are as follows.
W / C (%): Mass ratio of water (W) to cement (C) (mass%)
s / a (%): Volume ratio of fine aggregate (%)

After adding stone, sand (half amount), cement, sand (half amount) in this order into a 100 L pan-type mixer in the blending conditions shown in Table 3 above and performing kneading for 10 seconds, Production Example 1 to Production Example 12 A predetermined amount of water (concentration of polycarboxylic acid copolymer relative to cement: 0.21% by mass) containing an aqueous solution of the polycarboxylic acid copolymer obtained in the above was added and kneaded for 120 seconds.
After the kneaded fresh concrete was discharged to the boat and repeated two reciprocations, the slump flow value was measured as an initial fluidity evaluation of the concrete. The measurement was performed according to Japanese Industrial Standard (JIS A1150). The results are shown in Table 5 below.

(Examples 5 and 6, Comparative Examples 9 to 12)
<Mortar test>
Ordinary Portland cement (Sumitomo Osaka Cement Co., Ltd.) was used as the cement, and standard sand for cement strength test (1350 g / bag) was used as the sand. A mortar test was conducted using the aqueous solution of the polycarboxylic acid copolymer obtained in Production Example 13 to Production Example 18 as a cement admixture. The mortar blending conditions were as shown in Table 6 below.
Abbreviations in Table 6 are as follows.
W / C (%): Mass ratio of water (W) to cement (C) (mass%)
s / a (%): Volume ratio of fine aggregate (%)

A Hobart mixer was mixed with a predetermined amount of water containing an aqueous solution of the polycarboxylic acid copolymer obtained in Production Examples 13 to 18 under the blending conditions shown in Table 6 above (polycarboxylic acid system for cement). Copolymer concentration: 0.15 mass%) was added and kneaded for 1 minute at low speed. While rotating, standard sand for cement strength test was added over 20 seconds, and further kneaded for 1 minute 30 seconds. The rotation was stopped and scraping was carried out over 30 seconds, and then kneaded at high speed for another 1 minute 30 seconds to produce a mortar.
As an initial fluidity evaluation of the obtained mortar, a slump flow value was measured using a mini slump cone (half the size used for a standard in a concrete test). In addition, the measurement was performed according to Japanese Industrial Standards (JIS A 1101, 1128, 6204). The results are shown in Table 7 below.

The relationship between the amount of hydrogen peroxide used in the polymerization reaction and the weight average molecular weight of the copolymer is shown in the graph as shown in FIGS. From FIG. 1 and FIG. 4, when hydrogen peroxide is added all at once, it is affected by iron ions existing in the reaction system, and the weight average molecular weight of the copolymer obtained by the iron ion concentration in the reaction system is I found it different. Even when hydrogen peroxide is added dropwise, if the amount of hydrogen peroxide to be added is 1 mol% or more, it may still be affected by iron ions present in the reaction system. I understood.
Further, the relationship between the amount of hydrogen peroxide used in the polymerization reaction and the polymer content of the copolymer is shown in the graphs as shown in FIGS. 2 and 5, when hydrogen peroxide is added all at once, it is affected by iron ions present in the reaction system, and the polymer content of the copolymer obtained varies depending on the iron ion concentration in the reaction system. I found out. Even when hydrogen peroxide is added dropwise, if the amount of hydrogen peroxide to be added is 1 mol% or more, it may still be affected by iron ions present in the reaction system. I understood.
Further, the relationship between the amount of hydrogen peroxide used in the polymerization reaction and the slump flow value of the concrete or mortar produced using the copolymer obtained is shown in FIG. 3 and FIG. As shown in FIGS. 1, 2, 4, and 6, it is manufactured when hydrogen peroxide is added all at once, or 1 mol% or more of hydrogen peroxide is added dropwise. It has been found that the difference in physical properties between the reaction systems of the copolymers affects the performance of the cement or mortar when the copolymer or cement is used as a cement admixture.
From these results, when hydrogen peroxide is added all at once or when hydrogen peroxide in an amount of 1 mol% or more is added dropwise, it is influenced by iron ions existing in the reaction system, Differences in the weight average molecular weight and polymer content of the copolymer obtained depending on the iron ion concentration are observed, and variations in physical properties are seen, whereas hydrogen peroxide in an amount of less than 1 mol% is dropped. When added, it has been clarified that a copolymer having no variation in physical properties can be stably produced without being influenced by iron ions in the reaction system. It has been clarified that a cement admixture and concrete having no variation in performance can be stably produced by stably producing a copolymer having no variation in physical properties.
In the above examples, the case where iron ions are present in the polymerization system is shown. However, if a reducing substance is used, the polymerization reaction system is affected by the same mechanism as in the case of iron ions. By applying the method of the present invention, even when other reducing substances are present in the polymerization system as in the case where iron ions are present in the polymerization system, the copolymer is not affected by this. It can be said that it can be manufactured stably. That is, from the results of the above production examples, examples, and comparative examples, it can be said that the present invention can be applied in various forms disclosed in the present specification and can exhibit advantageous effects.

Mw: Weight average molecular weight of copolymer P min: Content ratio of polymer component of copolymer or higher trimer

Claims (6)

A method for producing a polycarboxylic acid copolymer for a cement admixture for polymerizing a polymerization solution containing a monomer component using a polymerization initiator and a reducing agent,
The production method includes a step of dropping a polymerization initiator into a polymerization solution,
The monomer component has the following general formula (1);

(In formula, R < ¹ >, R < ² > and R < ³ > are the same or different and represent a hydrogen atom or a methyl group. X represents a C1-C5 bivalent alkylene group, or R < ¹ > R. ^{When the} group represented by ³ C═CR ² — is a vinyl group, this represents that a carbon atom bonded to X and an oxygen atom are directly bonded to each other, and R ^a is the same or different and represents the number of carbon atoms. Represents an alkylene group of 2 to 5. m represents an average addition mole number of an oxyalkylene group represented by R ^a O, and is a number of 3 to 300. R ⁴ represents a hydrogen atom or a carbon number of 1 to 20; A monomer group (a) represented by the following general formula (2);

(In the formula, R ⁵ represents a hydrogen atom or a methyl group. R ^a is the same or different and represents an alkylene group having 2 to 5 carbon atoms. P represents an oxyalkylene group represented by R ^a O. The average added mole number is a number of 2 to 300. R ⁶ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.) And the following general formula (3);

(In the formula, R ⁷ represents a hydrogen atom or a methyl group. R ^a is the same or different and represents an alkylene group having 2 to 5 carbon atoms. Q represents an oxyalkylene group represented by R ^a O. The average addition mole number is a number of 0 to 1. M represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a metal atom, an ammonium group, or an organic ammonium group. (C), The manufacturing method of the polycarboxylic acid-type copolymer for cement admixtures characterized by the above-mentioned. The amount of the polymerization initiator used is 0.1 mol% or more and less than 1.0 mol% with respect to 100 mol% of all monomer components. A method for producing a carboxylic acid copolymer. The method for producing a polycarboxylic acid copolymer for a cement admixture according to claim 1 or 2, wherein the production method includes a step of dropping a reducing agent into the polymerization solution separately from the polymerization initiator. A polycarboxylic acid copolymer for cement admixture, which is produced by the method according to claim 1. A cement admixture comprising the polycarboxylic acid copolymer for cement admixture according to claim 4. A cement composition comprising the cement admixture according to claim 5.

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