JP2014166948A - Method of producing copolymer (salt) for cement admixture, and cement composition using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means enabling performances of a cement admixture (especially slump retention performance and freeze-thaw resistance) to be more improved.SOLUTION: There is provided a method of producing copolymer for a cement admixture including a step of obtaining a copolymer by copolymerizing a monomer composition containing Xwt.% of a specific first (poly)alkylene glycol (meth)acrylate monomer(a), Xwt.% of a specific second (poly)alkylene glycol (meth)acrylate monomer (b), Y wt.% of a specific carboxylic acid monomer (c) and Z wt.% of other monomers (d) copolymerizable with the (a) to (c). In the method, X:X:Y:Z=5 to 90:5 to 90:5 to 40:0 to 35 and X+X=60 to 95, and an absolute value of difference between a chain length distribution coefficient of the first (poly)alkylene glycol (meth)acrylate monomer (a) and the chain length distribution coefficient of the second (poly)alkylene glycol (meth)acrylate monomer (b) is 100 or more.

Description

  The present invention relates to a copolymer (salt) for a cement admixture, a production method thereof, and a cement composition using the same. More specifically, in a so-called cement composition such as cement paste, mortar, and concrete, a copolymer (salt) used in a slump-retaining cement admixture that prevents its fluidity from decreasing over time, and a method for producing the same, The present invention also relates to a cement composition containing the copolymer (salt).

  Since the early deterioration of concrete structures became a social problem in 1981, there has been a strong demand to reduce the unit water volume in concrete and improve its workability and durability. There has been a lot of technological innovation for cement dispersants that have great influence.

  As a conventional method, raw concrete with low fluidity (hereinafter referred to as “slump”) to which an AE agent or an AE water reducing agent is added is manufactured at a plant, transported to a setting site by a raw concrete car, and then flows into this. A fluidization method has been adopted in which a slumping agent is added and fluidized to increase the slump to a predetermined value. However, this method involves the environmental problems of noise and exhaust gas generated when adding a fluidizing agent to concrete in a concrete car and stirring and mixing, the responsibility for the quality of the obtained fluidized concrete, fluidized concrete. There were various problems such as a significant decrease in aging of slumps.

  Thus, development of so-called high-performance AE water reducing agents that can be added in a raw plant has been vigorously conducted by each admixture maker, and currently naphthalene-based, aminosulfonic acid-based and polycarboxylic acid-based ones are commercially available. Among them, the polycarboxylic acid-based high-performance AE water reducing agent has an excellent feature that the highest water reduction rate can be obtained, but it is used severely such as transporting the obtained ready-mixed concrete to a remote place in summer. Under the conditions, like other high-performance AE water reducing agents, there was a problem that slump loss could not be sufficiently suppressed.

  Here, the polycarboxylic acid-based high performance AE water reducing agent comprises a monomer component containing (poly) alkylene glycol (meth) acrylate and (meth) acrylic acid (salt) as essential components in the presence of a polymerization initiator. It has the structure of the copolymer obtained by superposing | polymerizing by. And as improvement technology of the said polycarboxylic acid type high performance AE water reducing agent for solving the subject mentioned above, for example, in patent documents 1, as (poly) alkylene glycol (meth) acrylate which is a component of a monomer ingredient Using at least two kinds, the average added mole number of oxyalkylene groups in these at least two kinds of (poly) alkylene glycol (meth) acrylates is in the range of 1 to 97 and in the range of 4 to 100 so that the difference is 3 or more. Further, a technique for configuring a cement admixture by setting a mixing ratio of three kinds of essential components including (meth) acrylic acid (salt) within a predetermined range is proposed.

Japanese Patent No. 3423553

  Although the cement admixture disclosed in Patent Document 1 described above exhibits certain excellent effects, there is still a strong demand for the development of a higher performance cement admixture.

  Then, an object of this invention is to provide the means which can improve the performance (especially slump retention performance and freeze-thaw resistance) of a cement admixture further.

  The present inventor has intensively studied in view of the above problems. As a result, surprisingly, a copolymer (salt) for a cement admixture was obtained using a monomer component essentially containing a (poly) alkylene glycol (meth) acrylate monomer and a carboxylic acid monomer. When manufacturing, using two or more kinds of (poly) alkylene glycol (meth) acrylate monomers that differ in the distribution of the average number of added moles of oxyalkylene groups by a certain degree, slump retention performance and freeze-thaw resistance It has been found that a copolymer (salt) having a further improved performance as a cement admixture such as a property can be obtained. Based on this knowledge, the present inventor has completed the present invention.

  That is, the method for producing a copolymer (salt) for a cement admixture according to the present invention has the following general formula (1):

In the formula, R ₁ represents a hydrogen atom or a methyl group, R ₂ O represents an oxyalkylene group, m represents an average added mole number of the oxyalkylene group, represents a number of 1 to 100, and R ₃ represents a hydrogen atom. Or an alkyl group having 1 to 22 carbon atoms,
₁ % by weight of a first (poly) alkylene glycol (meth) acrylate monomer (a) X represented by
The following general formula (2):

In the formula, R ₄ represents a hydrogen atom or a methyl group, R ₅ O represents an oxyalkylene group, n represents an average addition mole number of the oxyalkylene group, represents a number of 1 to 100, and R ₆ represents a hydrogen atom. Or an alkyl group having 1 to 22 carbon atoms,
₂ % by weight of a second (poly) alkylene glycol (meth) acrylate monomer (b) X
The following general formula (3):

In the formula, R ₇ represents a hydrogen atom or a methyl group, M ¹ represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group, or an organic amine group.
A carboxylic acid monomer represented by (c) Y wt%, and
Other monomers copolymerizable with the above (a) to (c) (d) Z wt%,
A step of polymerizing a monomer component containing a copolymer to obtain a copolymer, and
A step of neutralizing the copolymer with an alkaline substance, if necessary,
A method for producing a cement admixture copolymer (salt), comprising:
When X ₁ + X ₂ + Y + Z = 100, X ₁ : X ₂ : Y: Z = 5 to 90: 5 to 90: 5 to 40: 0 to 35 and X ₁ + X ₂ = 60 to 95,
Chain length distribution coefficient B1 of the first (poly) alkylene glycol (meth) acrylate monomer (a) and chain length distribution of the second (poly) alkylene glycol (meth) acrylate monomer (b) It is characterized in that the absolute value (| B1-B2 |) of the difference from the coefficient B2 is 100 or more.

  According to the present invention, a copolymer (salt) having further improved performance as a cement admixture (particularly slump retention performance and freeze-thaw resistance) can be obtained.

In the measurement of the chain length distribution coefficient A and the chain length distribution coefficient B, it is a chromatogram 1 obtained by liquid chromatography and having a peak separated for each chain length (added mole number of oxyalkylene group). From the chromatogram 1, the peak area, the area percentage, and the retention time (RT) for each added mole number of the oxyalkylene group are calculated, and the calculated area percentage value for each added mole number of the oxyalkylene group is calculated. It is the chart 2 obtained by plotting with respect to holding time. For a plurality of (poly) alkylene glycol (meth) acrylate monomers having different average addition mole numbers of oxyalkylene groups synthesized by the same synthesis method, the chain length distribution coefficient A was plotted against the average addition mole number. It is a graph. As shown in FIG. 3, the chain length distribution coefficient A of a plurality of (poly) alkylene glycol (meth) acrylate monomers synthesized by the same synthesis method exhibits linearity with respect to the average number of added moles (1 It gets on the next function).

According to one form of this invention, the manufacturing method of the copolymer (salt) for cement admixtures is provided. This manufacturing method is
₁ % by weight of the first (poly) alkylene glycol (meth) acrylate monomer (a) X represented by the general formula (1),
₂ % by weight of the second (poly) alkylene glycol (meth) acrylate monomer (b) X represented by the general formula (2),
-Carboxylic acid monomer represented by the general formula (3) (c) Y wt%, and
-Other monomer copolymerizable with the above (a) to (c) (d) Z wt%,
And a step of polymerizing a monomer component containing a copolymer to obtain a copolymer. Moreover, the process of neutralizing the said copolymer with an alkaline substance is included as needed. In the following, the above (a) to (d) will be described first.

[First (poly) alkylene glycol (meth) acrylate monomer (a) represented by general formula (1)]
Component (a) is represented by the following general formula (1):

(Poly) alkylene glycol (meth) acrylate monomer (also referred to herein as “first (poly) alkylene glycol (meth) acrylate monomer”).

In the general formula (1), R ₁ represents a hydrogen atom or a methyl group, preferably a methyl group.

In the general formula (1), R ₂ O represents an oxyalkylene group (that is, R ₂ represents an alkylene group). Here, the number of carbon atoms of R ₂ is preferably 2-18. That is, the oxyalkylene group represented by R ₂ O is preferably an alkylene oxide adduct having 2 to 18 carbon atoms. The structure of such an alkylene oxide adduct is, for example, a structure formed by one or more of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, isobutylene oxide, 1-butene oxide, and 2-butene oxide. is there. Among such alkylene oxide adducts, ethylene oxide, propylene oxide, and butylene oxide adducts are more preferable, and ethylene oxide adducts are particularly preferable.

Further, in the general formula (1), m is an average addition mol number of the oxyalkylene group _(R 2 O), the number of 1 to 100, preferably a number of 1 to 80, more preferably 4 to The number is 70, more preferably 4 to 70, and particularly preferably 4 to 60. If m is less than 1, sufficient cement dispersion performance may not be exhibited. On the other hand, if m exceeds 100, the cement composition may become viscous and difficult to handle. In the present specification, the “average added mole number” means an arithmetic average value of the mole number of the oxyalkylene group added in 1 mole of each component of the general formulas (1) to (2). Moreover, when m is a number of 2 or more, two or more oxyalkylene groups represented by R ₂ O in the general formula (1) are essential in the same compound, but are represented by R ₂ O. Each of the oxyalkylene groups may have any addition form such as random addition, block addition, and alternate addition (the same applies to R ₅ O described later).

Further, in the general formula (1), R ₃ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms. The number of carbon atoms of R ₃ is preferably 1 to 15, more preferably 1 to 8, still more preferably 1 to 4, particularly preferably 1 to 2, and most preferably 1. Specific examples of such R ₃ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, nonyl group, 2-ethylhexyl. Group, decyl group, dodecyl group, undecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, heneicosyl group, docosyl group, etc., among them methyl group, ethyl Group, n-propyl group, isopropyl group, n-butyl group or tert-butyl group is preferable, methyl group or ethyl group is more preferable, and methyl group is particularly preferable.

[Second (poly) alkylene glycol (meth) acrylate (b) represented by the general formula (2)]
Component (b) is represented by the following general formula (2):

A (poly) alkylene glycol (meth) acrylate monomer (also referred to herein as “second (poly) alkylene glycol (meth) acrylate monomer”).

In the general formula (2), R ₄ represents a hydrogen atom or a methyl group, preferably a methyl group.

In the general formula (2), R ₅ O represents an oxyalkylene group, and its definition and preferred embodiments are the same as R ₂ O in the general formula (1) described above. Omitted.

Further, in the general formula (2), n is the average number of added moles of the oxyalkylene group (R ₅ O), and the definition and preferred embodiments thereof are the same as m in the general formula (1) described above. Detailed description is omitted here.

In the general formula (2), R ₅ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and the definition and preferred embodiment thereof are the same as R ₃ in the above general formula (1). Detailed description is omitted here.

  In the above description, the first (poly) alkylene glycol (meth) acrylate monomer in the present invention is apparent from the fact that the structural definitions of the general formula (1) and the general formula (2) are the same. The body and the second (poly) alkylene glycol (meth) acrylate monomer may be the same substance in terms of molecular structure. However, even in such a case, if the chain length distribution coefficients (corresponding to B1 and B2) whose details will be described later are different, they are treated as different substances in the definition of the present invention, and the first ( Satisfies the requirement that two (poly) alkylene glycol (meth) acrylate monomers are used, a poly) alkylene glycol (meth) acrylate monomer and a second (poly) alkylene glycol (meth) acrylate monomer It shall be.

  The present invention relates to the chain length distribution coefficient B1 of the first (poly) alkylene glycol (meth) acrylate monomer (a) described above and the second (poly) alkylene glycol (meth) acrylate monomer ( It is characterized in that the absolute value (| B1-B2 |) of the difference from the chain length distribution coefficient B2 in b) is 100 or more. As described above, the monomer component of the copolymer (salt) for cement admixture according to the present invention is constructed, so that the performance as a cement admixture (especially slump retention performance and freeze-thaw resistance) is further improved. The present inventors have found that the obtained copolymer (salt) can be obtained. The “chain length distribution coefficient B1” and the “chain length distribution coefficient B2” are the chain length distribution coefficient B and the second chain length distribution coefficient B of the first (poly) alkylene glycol (meth) acrylate monomer (a), respectively. This means the chain length distribution coefficient B of the (poly) alkylene glycol (meth) acrylate monomer (b), and the “chain length distribution coefficient B” is a value calculated by the method described in the column of Examples described later. is there.

  The value of | B1-B2 | is preferably 100 or more, more preferably 100 to 500, still more preferably 100 to 400, and particularly preferably 100 to 300.

  Here, the average addition mole number (m) of the oxyalkylene group in the first (poly) alkylene glycol (meth) acrylate monomer (a) described above and the second (poly) alkylene glycol (meth) described above. A preferred embodiment is defined when the average added mole number (n) of the oxyalkylene group in the acrylate monomer (b) is substantially the same. In such a case, the chain length distribution coefficient A1 of the first (poly) alkylene glycol (meth) acrylate monomer (a) described above and the second (poly) alkylene glycol (meth) acrylate monomer described above The absolute value (| A1-A2 |) of the difference from the chain length distribution coefficient A2 of the body (b) is preferably 10 or more, more preferably 10-50, and even more preferably 10-30. By setting it as such a structure, the copolymer (salt) which shows the performance (especially slump retention performance and freeze-thaw resistance) as the more excellent cement admixture can be obtained. In addition, “the average added mole number of the oxyalkylene group in the first (poly) alkylene glycol (meth) acrylate monomer (a) and the second (poly) alkylene glycol (meth) acrylate monomer (b) Is substantially the same as the average number of added moles of the oxyalkylene group in | m−n | / min {m, n} (where | m−n | is the difference between m and n). This means that the value of min {m, n} represents the lesser of m and n) is 10 or less, and based on the difference in chain length distribution coefficient A when this definition is satisfied Comparison is possible. The “chain length distribution coefficient A1” and “chain length distribution coefficient A2” are the chain length distribution coefficient A and the second chain length distribution coefficient A of the first (poly) alkylene glycol (meth) acrylate monomer (a), respectively. This means the chain length distribution coefficient A of the (poly) alkylene glycol (meth) acrylate monomer (b), and the “chain length distribution coefficient A” is a value calculated by the method described in the column of Examples described later. is there.

  In addition, the value of the chain length distribution coefficient A and the chain length distribution coefficient B of the (poly) alkylene glycol (meth) acrylate monomer is the reaction temperature at the time of synthesizing the (poly) alkylene glycol (meth) acrylate monomer, It can be controlled by appropriately adjusting synthesis conditions such as reaction time. For example, when the reaction temperature is increased and / or the reaction time is increased, the chain length distribution coefficient can be adjusted to be increased. Further, among the raw materials of the (poly) alkylene glycol (meth) acrylate monomer, for the raw material having a (poly) alkylene glycol structure, by selecting a material having a larger distribution of the number of added oxyalkylene groups, It can adjust so that the chain length distribution coefficient of a (poly) alkylene glycol (meth) acrylate monomer may become large.

[Carboxylic acid monomer (c)]
Component (c) is represented by the general formula (3):

It is a carboxylic acid monomer represented by

In the general formula (3), R ₇ represents a hydrogen atom or a methyl group, preferably a methyl group.

In the general formula (3), M ¹ represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group or an organic amine group. Among these, M is preferably a monovalent metal atom or a divalent metal atom. Here, examples of the monovalent metal atom include alkali metal atoms such as lithium, sodium, and potassium, and examples of the divalent metal atom include alkaline earth metal atoms such as calcium and magnesium. The ammonium group is a functional group represented by “—NH 4 ⁺ ”. Examples of the organic amine group include residues derived from organic amines such as alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine; alkylamines such as monoethylamine, diethylamine, and triethylamine; and polyamines such as ethylenediamine and triethylenediamine. Groups.

  Examples of the carboxylic acid monomer (c) represented by the general formula (3) include acrylic acid, methacrylic acid, sodium acrylate, sodium methacrylate, ammonium acrylate, and ammonium methacrylate. Two or more of these may be used in combination. Among these, as the carboxylic acid monomer (c), (meth) acrylic acid is preferably used, and methacrylic acid is most preferably used. These compounds may use commercially available compounds, or may be prepared by self-synthesis.

[Other monomers (d) copolymerizable with (a) to (c)]
Component (d) is another monomer copolymerizable with the above-described (a) to (c). There is no restriction | limiting in particular about the specific structure of another monomer, What is necessary is just a compound copolymerizable with (a)-(c) mentioned above. As an example, the following compounds may be mentioned. Of course, compounds other than the following compounds may be used as other monomers.

  Half esters and diesters of unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, fumaric acid, itaconic acid and citraconic acid and alcohols having 1 to 30 carbon atoms; the above unsaturated dicarboxylic acids and 1 to 30 carbon atoms Half-amides and diamides of the above-mentioned amines: Half-esters and diesters of alkyl (poly) alkylene glycols obtained by adding 1 to 500 moles of alkylene oxides having 2 to 18 carbon atoms to the above alcohols and amines and the above-mentioned unsaturated dicarboxylic acids Half-esters and diesters of the above unsaturated dicarboxylic acids with glycols having 2 to 18 carbon atoms or polyalkylene glycols having 2 to 500 addition moles of these glycols; methyl (meth) acrylate, ethyl (meth) acrylate , Propyl (meth) acrylate, Esters of unsaturated monocarboxylic acids such as lysidyl (meth) acrylate, methyl crotonate, ethyl crotonate, propyl crotonate and alcohols having 1 to 30 carbon atoms; alcohols having 1 to 30 carbon atoms and carbon atoms Esters of alkoxy (poly) alkylene glycols to which 1 to 500 moles of 2 to 18 alkylene oxides are added and unsaturated monocarboxylic acids such as (meth) acrylic acid; (poly) ethylene glycol monomethacrylate, (poly) propylene 1-500 mole adducts of alkylene oxides of 2-18 carbon atoms to unsaturated monocarboxylic acids such as (meth) acrylic acid, such as glycol monomethacrylate, (poly) butylene glycol monomethacrylate; maleamic acid and carbon Glycols having 2 to 18 atoms or Half amides of polyalkylene glycols of addition mole number 2 to 500 of these glycols.

  Such as triethylene glycol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, (poly) ethylene glycol (poly) propylene glycol di (meth) acrylate, etc. ) Alkylene glycol di (meth) acrylates; polyfunctional (meth) acrylates such as hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate and trimethylolpropane di (meth) acrylate; triethylene glycol dimaleate (Poly) alkylene glycol dimaleates such as (poly) ethylene glycol dimaleate; vinyl sulfonate, (meth) allyl sulfonate, 2- (meth) acryloxyethyl sulfonate, 3- (meta Acryloxypropyl sulfonate, 3- (meth) acryloxy-2-hydroxypropyl sulfonate, 3- (meth) acryloxy-2-hydroxypropylsulfophenyl ether, 3- (meth) acryloxy-2-hydroxypropyloxysulfobenzoate, 4- Unsaturated sulfonic acids such as (meth) acryloxybutyl sulfonate, (meth) acrylamide methyl sulfonic acid, (meth) acrylamide ethyl sulfonic acid, 2-methylpropane sulfonic acid (meth) acrylamide, styrene sulfonic acid, and one of them Valent metal salts, divalent metal salts, ammonium salts and organic amine salts; amides of unsaturated monocarboxylic acids and amines having 1 to 30 carbon atoms such as methyl (meth) acrylamide; styrene, α-methylstyrene, Bi Vinyl aromatics such as nyltoluene and p-methylstyrene; 1,4-butanediol mono (meth) acrylate, 1,5-pentanediol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, etc. Alkanediol mono (meth) acrylates; dienes such as butadiene, isoprene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene and the like.

  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, methylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, Unsaturated amines such as dibutylaminoethyl acrylate and vinyl pyridine; divinyl aromatics such as divinylbenzene; cyanurates such as triallyl cyanurate; (meth) allyl alcohol, glycidyl (meth) allyl ether, etc. Allyls; methoxy (poly ) Ethylene glycol monovinyl ether, (poly) ethylene glycol monovinyl ether, methoxy (poly) ethylene glycol mono (meth) allyl ether, (poly) ethylene glycol mono (meth) allyl ether, vinyl ethers or allyl ethers; (poly) Dimethylsiloxanepropylaminomaleamic acid, (poly) dimethylsiloxaneaminopropylaminomaleamic acid, (poly) dimethylsiloxane-bis- (propylaminomaleamic acid), (poly) dimethylsiloxane-bis- (dipropyleneaminomaleamide) Acid), (poly) dimethylsiloxane- (1-propyl-3-acrylate), (poly) dimethylsiloxane- (1-propyl-3-methacrylate), (poly) dimethylsiloxane Siloxane derivatives such as sun-bis- (1-propyl-3-acrylate) and (poly) dimethylsiloxane-bis- (1-propyl-3-methacrylate).

  In addition, the (poly) alkylene glycol (meth) acrylate monomer applicable to the compound represented by General formula (1) or General formula (2) may be used as another monomer (d). In this case, at least three (poly) alkylene glycol (meth) acrylate monomers are included in the monomer component. In such a case, the at least three (poly) alkylene glycols described above are included. When any two of the (meth) acrylate monomers are used as the first (poly) alkylene glycol (meth) acrylate monomer and the second (poly) alkylene glycol (meth) acrylate monomer, respectively. As long as the essential constituent requirements in the present invention are satisfied, such a case is also included in the technical scope of the present invention.

  According to the method for producing a cement admixture copolymer (salt) according to the present embodiment described above, a copolymer (salt) in which components (a) to (d) are derived at a specific ratio is obtained. Here, in the obtained copolymer (salt), the double bonds contained in the components (a) to (d) are cleaved to form single bonds, which are further linked to adjacent monomers via single bonds. The structure made is a series. Also, the arrangement of each component is not particularly limited, and random polymerization, block polymerization, and the like are conceivable, but they are usually arranged in the form of random polymerization.

The method for producing a copolymer (salt) for a cement admixture according to the present invention is also characterized in that the amount of components (a) to (d) used is defined. Hereinafter, the regulation of the contents of the components (a) to (d) will be described. In the present specification, the contents of the components (a) to (d) are determined as follows:
Ingredient (a) X ₁ % by weight
-Component (b) X ₂ % by weight
-Component (c) Y wt%
-Component (d) Z wt%
The amount of each component used in the method for producing a cement admixture copolymer (salt) according to the present invention is characterized by X ₁ : X ₂ : Y: Z = 5 when X ₁ + X ₂ + Y + Z = 100. 90: 5-90: 5-40: 0-35 and in satisfy the relation of _X 1 _{+ X} 2 = _60~95. Preferably _{X 1: X 2: Y:} Z = 10~80: 10~80: 5~35: 0~30 and are _X 1 _{+ X} 2 = _65~95, more preferably _{X 1: X 2: Y:} Z = 20 to 60:20 to 60: 5 to 30: 0 to 30 and X ₁ + X ₂ = 70 to 95, more preferably X ₁ : X ₂ : Y: Z = 30 to 50:30 to 50: 5-20: 0 to 25 and _X 1 _{+ X} 2 = _70~90. When the amount of each component used is within such a range, the dispersibility as a cement admixture is improved.

(Details of manufacturing method)
In order to obtain a copolymer using the above-described monomer component, a monomer component containing the above (a) to (d) in the above amount may be copolymerized using a polymerization initiator. Here, there is no restriction | limiting in particular about the specific method of preparing the monomer component which contains said (a)-(d) in said quantity, For example, prepare the component of (a)-(d) separately, respectively. The monomer component may be prepared by mixing them.

  The copolymerization can be performed by a method such as polymerization in a solvent or bulk polymerization.

  Polymerization in a solvent can be carried out either batchwise or continuously. The solvent used here is water; lower alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol; benzene, toluene, xylene, cyclohexane, n -Aromatic or aliphatic hydrocarbons such as hexane; ester compounds such as ethyl acetate; ketone compounds such as acetone and methyl ethyl ketone; From the solubility of the raw material monomer and the resulting copolymer and the convenience during use of the copolymer, use at least one selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms. Is preferred. In that case, methyl alcohol, ethyl alcohol, isopropyl alcohol and the like are particularly effective among the lower alcohols having 1 to 4 carbon atoms.

  When polymerization is performed in an aqueous medium, a water-soluble polymerization initiator such as ammonium or alkali metal persulfate or hydrogen peroxide is used as the polymerization initiator. In this case, an accelerator such as sodium hydrogen sulfite or a molle salt can be used in combination. For polymerization using a lower alcohol, aromatic hydrocarbon, aliphatic hydrocarbon, ester compound or ketone compound as a solvent, peroxides such as benzoyl peroxide and lauroyl peroxide; hydroperoxides such as cumene hydroperoxide; azo An aromatic azo compound such as bisisobutyronitrile is used as a polymerization initiator. In this case, an accelerator such as an amine compound can be used in combination. Furthermore, when a water-lower alcohol mixed solvent is used, it can be appropriately selected from the above-mentioned various polymerization initiators or combinations of polymerization initiators and accelerators. The polymerization temperature is appropriately determined depending on the solvent to be used and the polymerization initiator, but is usually within a range of 0 to 120 ° C.

  Bulk polymerization uses a peroxide such as benzoyl peroxide or lauroyl peroxide as a polymerization initiator; a hydroperoxide such as cumene hydroperoxide; an aliphatic azo compound such as azobisisobutyronitrile, and the like. Performed within the temperature range.

Moreover, a thiol chain transfer agent can be used in combination for adjusting the molecular weight of the obtained copolymer. The thiol chain transfer agent used in this case has a general formula HS-R ₈ -E _g (wherein R ₈ represents an alkyl group having 1 to 2 carbon atoms, and E represents —OH, —COOM ^2. , -COOR ₉ or -SO ₃ M ² group, M ² represents hydrogen, monovalent metal, divalent metal, ammonium group or organic amine group, and R ₉ represents an alkyl group having 1 to 10 carbon atoms. G represents an integer of 1 to 2, for example, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, 3- Examples thereof include octyl mercaptopropionate, and one or more of these can be used.

[Other forms]
The copolymer thus obtained can be used as a main component of the cement dispersant as it is, but if necessary, a copolymer salt obtained by further neutralization with an alkaline substance can be used as a cement admixture. May be. Preferred examples of such alkaline substances include inorganic substances such as hydroxides, chlorides and carbon salts of monovalent metals and divalent metals; ammonia; organic amines and the like.

  The weight average molecular weight (Mw) of the admixture copolymer (salt) according to the present invention is 500 to 500,000 in terms of polyethylene glycol by gel permeation chromatography (hereinafter also referred to as “GPC”). In particular, the range is preferably 5,000 to 300,000. A weight average molecular weight of less than 500 is not preferable because water reducing performance as a cement admixture is reduced. On the other hand, if the weight average molecular weight exceeds 500,000, the water reducing performance as a cement admixture and the ability to prevent slump loss are not preferable.

  The copolymer (salt) according to the present invention can be used as a cement admixture alone or as a mixture of two or more. Moreover, it can also be used combining a copolymer (salt) as a main component and another well-known cement admixture. Such known cement admixtures include, for example, conventional cement dispersants, air entrainers, cement wetting agents, expansion agents, waterproofing agents, retarders, quick setting agents, water-soluble polymer substances, thickeners, and agglomerates. Agents, drying shrinkage reducing agents, strength enhancers, curing accelerators, antifoaming agents and the like.

  In addition, when using a known cement dispersant, the blending mass ratio of the copolymer (salt) for cement admixture of the present invention and the known cement dispersant is the type, blending and testing of the known cement dispersant to be used. Although it is not uniquely determined depending on the difference in conditions and the like, 1 to 99/99 to 1 is preferable, and 5 to 95/95 to 5 is more preferable as the weight ratio (% by weight) in terms of solid content. -90 / 90-10 are more preferable. Examples of the known cement dispersant used in combination include cement dispersants as described below.

  Polyalkylaryl sulfonates such as naphthalene sulfonic acid formaldehyde condensates; Melamine formalin sulfonates such as melamine sulfonic acid formaldehyde condensates; Aromatic amino sulfonates such as aminoaryl sulfonic acid-phenol-formaldehyde condensates Various sulfonic acid-based dispersants having a sulfonic acid group in the molecule such as lignin sulfonates such as lignin sulfonates and modified lignin sulfonates; polystyrene sulfonates.

  As described in JP-B-59-18338 and JP-A-7-223852, polyalkylene glycol mono (meth) acrylic acid ester monomers, (meth) acrylic acid monomers, and single amounts thereof A copolymer obtained from a monomer copolymerizable with a polymer; described in JP-A-10-236858, JP-A-2001-220417, JP-A-2002-121055, JP-A-2002-121056 (Poly) oxyalkylene group and carboxyl group in the molecule such as copolymer obtained from unsaturated (poly) alkylene glycol ether monomer, maleic acid monomer or (meth) acrylic acid monomer And various polycarboxylic acid-based dispersants.

  In a molecule such as a copolymer obtained from (alkoxy) polyalkylene glycol mono (meth) acrylate, phosphoric monoester monomer, and phosphoric diester monomer as described in JP-A-2006-52381 And various phosphate dispersants having a (poly) oxyalkylene group and a phosphate group.

Moreover, as an antifoamer, the well-known antifoamers which are illustrated to the following (1)-(2) are suitable.
(1) Oxyalkylene-based antifoaming agent: polyoxyalkylenes such as (poly) oxyethylene (poly) oxypropylene adducts; polyoxyalkylene alkyl ethers such as diethylene glycol heptyl ether; polyoxyalkylene acetylene ethers; ) Oxyalkylene fatty acid esters; polyoxyalkylene sorbitan fatty acid esters; polyoxyalkylene alkyl (aryl) ether sulfate salts; polyoxyalkylene alkyl phosphate esters; polyoxypropylene polyoxyethylene laurylamine (propylene oxide 1-20) Mole additions, ethylene oxide 1-20 mol adducts, etc.), fatty acid-derived amines obtained from cured beef tallow added with alkylene oxide (propylene oxide 1-20 mol) Additionally, polyoxyalkylene alkyl amines ethylene oxide 20 mol adduct) or the like; polyoxyalkylene amide.
(2) Antifoaming agents other than oxyalkylene type: Mineral oil type, fat type, fatty acid type, fatty acid ester type, alcohol type, amide type, phosphate ester type, metal soap type, silicone type and the like.

  The cement admixture according to the present invention can be used for hydraulic cements such as Portland cement, belite-rich cement, alumina cement, various mixed cements, or hydraulic materials other than cement such as gypsum.

  The cement admixture according to the present invention exhibits an excellent effect even when added in a small amount as compared with the conventional cement admixture. For example, when used for mortar or concrete using hydraulic cement, 0.01 to 1.0%, preferably 0.02 to 0.5% of the cement weight is mixed at the time of mixing. It may be added to. By this addition, various desirable effects such as achievement of a high water reduction rate, improvement of slump loss prevention performance, reduction of unit water volume, increase of strength (compression strength), and improvement of durability are brought about. If the addition amount is 0.01% or more, sufficient performance is exhibited, and if it is 1.0% or less, it is advantageous from the economical aspect.

In the cement composition according to the present invention, the amount of cement used per 1 m ^{3 of} the cement composition and the unit water amount are not limited, but the unit water amount is 120 to 185 kg / m ³ , and the water / cement weight ratio = 0.15 It is recommended that 0.7, preferably a unit water amount of 120 to 175 kg / m ³ and a water / cement weight ratio of 0.2 to 0.5.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and the present invention is not limited to the following examples. It is also possible to implement, and they are all included in the technical scope of the present invention.

[Production example]
(Production Example 1)
A SUS autoclave reaction vessel equipped with a thermometer, a stirrer, a raw material introduction tube and a nitrogen introduction tube was charged with 180 parts by weight of methanol and 1.3 parts by weight of sodium hydroxide, and the inside of the reaction vessel was purged with nitrogen under stirring. The temperature was raised to 150 ° C. in a nitrogen atmosphere. While maintaining 150 ° C., 2477.8 parts by weight of ethylene oxide was added while maintaining a pressure below 45% of the partial pressure of ethylene oxide, and the target methoxypolyethylene glycol (average added mole number of oxyethylene groups: 10 Mol) [1] was obtained.

(Production Example 2)
Into a SUS autoclave reaction vessel equipped with a thermometer, a stirrer, a raw material introduction tube and a nitrogen introduction tube, 1200 parts by weight of methoxypolyethylene glycol (average number of moles of oxyethylene group added: 10 mol) was charged, and the reaction vessel was stirred. The inside was replaced with nitrogen, and the temperature was raised to 150 ° C. in a nitrogen atmosphere. While maintaining 150 ° C., 1454.3 parts by weight of ethylene oxide was added while maintaining a pressure below 45% of the partial pressure of ethylene oxide, and the target methoxypolyethylene glycol (average added mole number of oxyethylene groups: 23 Mol) [2] was obtained.

(Production Example 3)
A SUS autoclave reaction vessel equipped with a thermometer, a stirrer, a raw material introduction tube and a nitrogen introduction tube was charged with 180 parts by weight of methanol and 1.1 parts by weight of sodium hydroxide, and the reaction vessel was purged with nitrogen under stirring. The temperature was raised to 150 ° C. in a nitrogen atmosphere. 1982.3 parts by weight of ethylene oxide was added while maintaining the pressure below 45% while maintaining the temperature at 150 ° C, and then low added moles of alcohol was removed from the system at 100 ° C, 50 Torr, 2 hours. To obtain methoxypolyethylene glycol (average added mole number of oxyethylene group: 8 moles).

  Subsequently, in an SUS autoclave reaction vessel equipped with a thermometer, a stirrer, a raw material introduction tube and a nitrogen introduction tube, 1200 parts by weight of the methoxypolyethylene glycol obtained above (average added mole number of oxyethylene group: 8 moles) was added. The reaction vessel was purged with nitrogen while stirring, and the temperature was raised to 150 ° C. in a nitrogen atmosphere. While maintaining the temperature at 150 ° C., while maintaining the pressure below 45% of ethylene oxide, 2062.7 parts by weight of ethylene oxide was added, and the target methoxypolyethylene glycol (average added mole number of oxyethylene groups: 23 Mol) [3] was obtained.

(Production Example 4)
A SUS autoclave reaction vessel equipped with a thermometer, a stirrer, a raw material introduction tube and a nitrogen introduction tube was charged with 180 parts by weight of methanol and 1.1 parts by weight of sodium hydroxide, and the reaction vessel was purged with nitrogen under stirring. The temperature was raised to 120 ° C. under a nitrogen atmosphere. 1982.3 parts by weight of ethylene oxide was added while maintaining the pressure below 120% while maintaining the temperature at 120 ° C, and then the low addition mole number of alcohol was removed from the system at 100 ° C, 50 Torr, 2 hours. To obtain methoxypolyethylene glycol (average added mole number of oxyethylene group: 8 moles).

  Subsequently, in an SUS autoclave reaction vessel equipped with a thermometer, a stirrer, a raw material introduction tube and a nitrogen introduction tube, 1200 parts by weight of the methoxypolyethylene glycol obtained above (average added mole number of oxyethylene group: 8 moles) was added. The reaction vessel was purged with nitrogen while stirring, and the temperature was raised to 150 ° C. in a nitrogen atmosphere. While maintaining the temperature at 120 ° C., 2062.7 parts by weight of ethylene oxide was added while maintaining the pressure below the ethylene oxide partial pressure to be 45% or less, and the target methoxypolyethylene glycol (average added mole number of oxyethylene groups: 23 Mol) [4] was obtained.

  Table 1 below summarizes the structure and the distribution of the number of added moles of oxyalkylene groups for the methoxypolyethylene glycol (MPEG) obtained in Production Examples 1 to 4 above.

  The distribution of the number of added moles was determined by performing liquid chromatography under the following measurement conditions and comparing the peaks of the obtained chromatograms with the same average added mole number.

(Measurement condition)
Column used: TSK guard column SWXL manufactured by Tosoh Corporation
Two TSKgel G2500PWXL eluents: A solution of 540 g of acetonitrile and 1260 g of water in which 17.0 g of sodium nitrate was dissolved was used.
Sample: The MPEG obtained in Production Examples 1 to 4 was dissolved in the eluent so as to be 0.5% by mass.
Sample injection amount: 100 μL
Flow rate: 1.0 mL / min Column temperature: 40 ° C
Detector: Japan Waters 2414 Differential Refractometer Detector Analysis: Japan Waters Empower Software

  As shown in Table 1, it can be seen that by synthesizing using different synthesis methods, a difference occurs in the distribution of the added mole number even if the average added mole number of the oxyalkylene group is the same.

(Production Example 5)
A 1000 ml separable flask was provided with a packed tower filled with a thermometer, a stirrer and a Raschig ring so that the reflux ratio could be changed arbitrarily. In this packed column, 606 g of methyl methacrylate, 408 g of methoxypolyethylene glycol (average number of moles of oxyethylene group added: 10 mol) obtained by the method described in Production Example 1, and 0.10 g of phenothiazine as a polymerization inhibitor were added. When the tower top temperature reached 50 ° C., 2.65 g of 49 wt% sodium hydroxide was added dropwise over 1 hour 30 minutes. The methanol-methyl methacrylate azeotrope was distilled off under reduced pressure to obtain the desired methoxypolyethylene glycol monomethacrylate [A].

(Production Example 6)
In a glass reaction vessel, 200 parts by weight of methoxypolyethylene glycol (average number of moles of oxyethylene group added: 10 moles) [1] obtained by the method described in Production Example 1 was charged. Next, 0.19 part by weight of hydroquinone and 16.0 parts by weight of p-toluenesulfonic acid were added. While introducing air and nitrogen, 423.8 parts by weight of methyl methacrylate was added, and heating and decompression in the reaction vessel were started. The reaction was carried out while controlling the pressure at 30 to 80 kPa and maintaining the reaction solution temperature at 100 ° C. After 12 hours from the start of the reaction, the pressure is returned to normal pressure, and neutralization is performed by adding a 49% by weight aqueous sodium hydroxide solution of 1.1 times equivalent to p-toluenesulfonic acid to complete the reaction. It was.

  After completion of the reaction, the reaction solution temperature was maintained at 130 ° C. or lower, and unreacted methyl methacrylate was recovered by vacuum distillation to obtain the desired methoxypolyethylene glycol methacrylate [B].

(Production Example 7)
Methoxypolyethylene glycol (average number of moles of oxyethylene group added: 23) obtained by the method of Production Example 3 in a glass reaction vessel equipped with a thermometer, a stirrer, a generated water separator, and a reflux condenser [3] 1000 parts by weight, 222.4 parts by weight of methacrylic acid, 0.61 part by weight of phenothiazine, 244.5 parts by weight of cyclohexane and 12.2 parts by weight of paratoluenesulfonic acid are charged and heated to 105 ° C. with stirring to perform esterification The reaction was started. After confirming that a predetermined amount of generated water had been distilled off, 2.8 parts by weight of sodium hydroxide was added. After the cyclohexane was distilled off, a predetermined amount of water was added to obtain an 80% by weight aqueous solution of a monomer mixture [C] containing methoxypolyethylene glycol methacrylate.

(Production Example 8)
In a glass reaction vessel equipped with a thermometer, stirrer, produced water separator, gas inlet, and reflux condenser, methoxypolyethylene glycol obtained by the method of Production Example 4 (average number of moles of oxyethylene group added: 23) ) [4] A nitrogen / oxygen mixed gas adjusted to an oxygen concentration of 5% by volume was charged by introducing 1000 parts by weight, 222.4 parts by weight of methacrylic acid, 0.24 parts by weight of phenothiazine, and 12.2 parts by weight of paratoluenesulfonic acid. To do. The pressure was reduced to 50 Torr with stirring, and then the temperature was raised to 90 ° C. to start the esterification reaction. After confirming that a predetermined amount of generated water had been distilled off and returning to normal pressure, 2.8 parts by weight of sodium hydroxide was added. After the cyclohexane was distilled off, a predetermined amount of water was added to obtain an 80% by weight aqueous solution of a monomer mixture [D] containing methoxypolyethylene glycol methacrylate.

(Production Example 9)
Methoxypolyethylene glycol (average number of moles of oxyethylene group added: 23) obtained by the method of Production Example 2 in a glass reaction vessel equipped with a thermometer, a stirrer, a generated water separator, and a reflux condenser [2] 1000 parts by weight, 222.4 parts by weight of methacrylic acid, 0.24 parts by weight of phenothiazine, 61.1 parts by weight of cyclohexane and 61.1 parts by weight of paratoluenesulfonic acid are heated to 120 ° C. with stirring, and the ester The conversion reaction was started. After confirming that a predetermined amount of generated water had been distilled off, 14.2 parts by weight of sodium hydroxide was added. After the cyclohexane was distilled off, a predetermined amount of water was added to obtain an 80% by weight aqueous solution of a monomer mixture [E] containing methoxypolyethylene glycol methacrylate.

(Production Example 10)
To a glass reaction vessel equipped with a thermometer, stirrer, produced water separator, gas inlet, and reflux condenser, methoxypolyethylene glycol obtained by the method of Production Example 3 (average number of moles of oxyethylene group added: 23 ) [3] A nitrogen / oxygen mixed gas adjusted to an oxygen concentration of 5% by volume was charged by introducing 1000 parts by weight, 222.4 parts by weight of methacrylic acid, 0.24 parts by weight of phenothiazine, and 12.2 parts by weight of paratoluenesulfonic acid. To do. The pressure was reduced to 50 Torr with stirring, and then the temperature was raised to 90 ° C. to start the esterification reaction. After confirming that a predetermined amount of generated water had been distilled off and returning to normal pressure, 2.8 parts by weight of sodium hydroxide was added. After the cyclohexane was distilled off, a predetermined amount of water was added to obtain an 80% by weight aqueous solution of a monomer mixture [D] containing methoxypolyethylene glycol methacrylate.

  The methoxypolyethylene glycol methacrylate (MPEGMA) obtained in the above Production Examples 5 to 10 is summarized in the following Table 2 with the structure and the distribution of the number of added moles of oxyalkylene groups.

  As shown in Table 2, methoxypolyethylene glycol methacrylate (MPEGMA) is also synthesized using a different synthesis method, so that even if the average number of moles of oxyalkylene groups added is the same, You can see the difference. For example, Production Example 5 and Production Example 6 use the same raw material alcohol having the same added mole number distribution, but the method of the esterification step with methacrylic acid is different, so that the MPEGMA finally obtained can be obtained. There is a difference in the added mole number distribution at the stage.

  As described above, the distribution of the number of added oxyalkylene groups in the (poly) alkylene glycol (meth) acrylate monomer is determined by the steps of addition reaction of alkylene oxide and the esterification step for obtaining the monomer. It is affected by both.

[Measurement of chain length distribution coefficients A and B]
About the methoxypolyethyleneglycol methacrylate which is a polyalkylene glycol (meth) acrylate monomer obtained by said manufacture examples 5-10, chain length distribution coefficient A and B was measured with the following methods, respectively. In the following description, the chain length distribution coefficient A of Blemmer (registered trademark) PME-400 (manufactured by NOF Corporation), which is a commercial product of methoxypolyethylene glycol methacrylate (average number of added moles of oxyethylene group: 9), and An example of measuring the chain length distribution coefficient B will be described.

First, liquid chromatography is performed under the following conditions to obtain a chromatogram 1 in which peaks are separated for each chain length (non-molar number of oxyalkylene groups) as shown in FIG.
Column used: ODS-80Ts manufactured by Tosoh Corporation
ODS-120T
Eluent: A mixture of acetonitrile and PW in a ratio of 25: 70% by volume.
Sample: A substance to be measured dissolved in the above solution so that the solid content concentration of the measured substance is 10%.
Sample injection amount: 100 μl
Column temperature: 40 ° C
Flow rate: 1.0 mL / min Detector: Japan Waters 2998 photodiode array detector (wavelength 230 nm)
Analysis: Emperor Software made by Waters, Japan
From the obtained chromatogram 1, the peak area, area percentage, and retention time (RT) for each non-mol number of oxyalkylene groups are calculated (Table 3 below).

  And the value of the area percentage for every addition mole number of the oxyalkylene group calculated above is plotted with respect to the retention time to obtain a chart 2 as shown in FIG.

  The half-value width of the retention time for the maximum peak of Chart 2 obtained in this way is defined as “chain length distribution coefficient A”. In the chart 2 shown in FIG. 2, the area percentage of the maximum peak is 21%, and the retention times corresponding to this half value (10.5%) are 34 minutes and 60 minutes, so that the Blemmer® PME-400 The chain length distribution coefficient A is calculated as 60−34 = 26 minutes.

  The chain length distribution coefficient A indicates the degree of distribution of the number of added oxyalkylene groups in the (poly) alkylene glycol (meth) acrylate monomer. The smaller the value, the smaller the spread of the distribution and the sharper distribution. Indicates that Here, when comparing the degree of distribution of the number of added oxyalkylene groups in two or more different (poly) alkylene glycol (meth) acrylate monomers, the average added number of moles of monomers are the same. If there is, it is possible to compare the degree of distribution of the added moles of oxyalkylene groups by simply comparing the chain length distribution coefficient A. However, in general, as the average addition mole number of the oxyalkylene group in the monomer increases, the degree of distribution of the addition mole number of the oxyalkylene group tends to increase, so the average addition mole number of the oxyalkylene group differs. In order to enable comparison of the degree of distribution between monomers, it is necessary to use a chain length distribution coefficient B calculated as follows.

  First, the inventor synthesized a plurality of (poly) alkylene glycol (meth) acrylate monomers having different average addition mole numbers of oxyalkylene groups by the same synthesis method. And the chain length distribution coefficient A calculated | required by the method mentioned above about each monomer was plotted with respect to the average addition mole number. As such, the chain length distribution coefficient A of a plurality of (poly) alkylene glycol (meth) acrylate monomers synthesized by the same synthesis method shows linearity with respect to the average number of added moles (on a linear function). I found it). This linear function is expressed by the following formula 1 (see also the graph shown in FIG. 3):

  When this equation is transformed, the following equation 2 is obtained.

  If the (oxy) alkylene group (poly) alkylene glycol (meth) acrylate monomer has the same average added mole number of oxyalkylene groups, the above relationship should theoretically be satisfied regardless of the synthesis method. However, according to the study by the present inventors, (poly) alkylene glycol (meth) acrylate monomers having different synthesis methods do not satisfy the above relationship even if the average number of added moles is the same. I found out. Therefore, a parameter obtained by multiplying the left side of Equation 2 by 100 is defined as a chain length distribution coefficient B as a parameter to be used for comparison of chain length distributions of (poly) alkylene glycol (meth) acrylate monomers having different synthesis methods. did. That is, the chain length distribution coefficient B is defined as Equation 3 below.

  Table 4 below summarizes the results of calculating the chain length distribution coefficient A and the chain length distribution coefficient B for the methoxypolyethylene glycol methacrylate (MPEGMA) obtained in Production Examples 5 to 10 above. is there.

〔Example〕
Example 1
A glass reaction vessel equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube, and reflux condenser was charged with 129.6 parts by weight of water, and the reactor was purged with nitrogen under stirring. The temperature was raised to 95 ° C. An aqueous solution obtained by mixing 21.4 parts by weight of the monomer [B] obtained by the method of Production Example 6 and 10 parts by weight of water, 150 parts by weight of the monomer [A] obtained by the method of Production Example 5 and water 40 parts by weight mixed aqueous solution, methacrylic acid 42.9 parts by weight, 3-mercaptopropionic acid 3.5 parts by weight and water 20 parts by weight mixed, ammonium persulfate 1.8 parts by weight and water 20 parts by weight The resulting aqueous solution was dropped into the reactor over 4 hours each. And after completion | finish of dripping, 95 degreeC was further maintained for 2 hours, and the polycarboxylic acid (1) of the weight average molecular weight 13000 was obtained. In addition, the measurement conditions of the weight average molecular weight of the obtained polycarboxylic acid are as follows.

(GPC measurement conditions)
Used column: TSK guard column SWXL manufactured by Tosoh Corporation
TSKgel G4000SWXL
TSKgel G3000SWXL
TSKgel G2000SWXL connected in this order.
Eluent: A solution prepared by dissolving 115.6 g of sodium acetate trihydrate in a solution of 6000 g of acetonitrile and 11000 g of water, and adjusting the pH to 6.0 with acetic acid was used.
Sample: A polymer aqueous solution dissolved in the eluent so that the polymer concentration is 0.5% by mass.
Sample injection amount: 100 μL
Flow rate: 1.0 mL / min Column temperature: 40 ° C
Detector: Japan Waters 2414 Differential Refractometer Detector Analysis: Japan Waters Empower Software
Standard material for preparing calibration curve: polyethylene glycol [peak top molecular weight (Mp) 272500, 219300, 107000, 50000, 24000, 11840, 6450, 4250, 1470]
Calibration curve: Prepared by a cubic equation based on the Mp value and elution time of the above polyethylene glycol.

(Example 2)
A glass reaction vessel equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube, and reflux condenser was charged with 179.2 parts by weight of water, and the reactor was purged with nitrogen under stirring. The temperature was raised to 95 ° C. An aqueous solution obtained by mixing 70.7 parts by weight of the monomer [A] obtained by the method of Production Example 5 and 20 parts by weight of water, 200 parts by weight of the monomer [E] obtained by the method of Production Example 9, methacryl Reaction of 5.0 parts by weight of acid, 2.3 parts by weight of 3-mercaptopropionic acid and 20 parts by weight of water, and an aqueous solution of 1.2 parts by weight of ammonium persulfate and 20 parts by weight of water over 4 hours each It was dripped in the vessel. And after completion | finish of dripping, 95 degreeC was further maintained for 2 hours, and the polycarboxylic acid (2) of the weight average molecular weight 20000 was obtained.

(Example 3)
A glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube, and a reflux condenser was charged with 158.3 parts by weight of water, and the reactor was purged with nitrogen under stirring. The temperature was raised to 95 ° C. 110.0 parts by weight of the monomer [C] obtained by the method of Production Example 7, 110.0 parts by weight of the monomer [D] obtained by the method of Production Example 8, 18.5 parts by weight of methacrylic acid, An aqueous solution in which 2.5 parts by weight of 3-mercaptopropionic acid and 20 parts by weight of water were mixed, and an aqueous solution in which 1.3 parts by weight of ammonium persulfate and 20 parts by weight of water were mixed were dropped into the reactor over 4 hours. And after completion | finish of dripping, 95 degreeC was further maintained for 2 hours, and the polycarboxylic acid (3) of the weight average molecular weight 22000 was obtained.

Example 4
Into a glass reaction vessel equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube, and reflux condenser, 167.1 parts by weight of water was charged, and the inside of the reactor was purged with nitrogen under stirring. The temperature was raised to 95 ° C. An aqueous solution obtained by mixing 42.4 parts by weight of the monomer [A] obtained by the method of Production Example 5 and 20 parts by weight of water, 150 parts by weight of the monomer [E] obtained by the method of Production Example 9, An aqueous solution obtained by mixing 60 parts by weight of the monomer [D] obtained by the method of Production Example 8, 1.7 parts by weight of methacrylic acid, 1.9 parts by weight of 3-mercaptopropionic acid and 20 parts by weight of water, ammonium persulfate 1 An aqueous solution in which 0.0 part by weight and 20 parts by weight of water were mixed was dropped into the reactor over 4 hours each. And after completion | finish of dripping, 95 degreeC was further maintained for 2 hours, and the polycarboxylic acid (4) of the weight average molecular weight 23000 was obtained.

(Example 5)
A glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube, and a reflux condenser was charged with 181.4 parts by weight of water, and the reactor was purged with nitrogen under stirring. The temperature was raised to 95 ° C. An aqueous solution obtained by mixing 70.7 parts by weight of the monomer [B] obtained by the method of Production Example 6 and 20 parts by weight of water, 150 parts by weight of the monomer [F] obtained by the method of Production Example 10, methacryl Methyl acid (MMA) 23.6 parts by weight, methacrylic acid 21.4 parts by weight, 3-mercaptopropionic acid 3.7 parts by weight and water 20 parts by weight, aqueous solution of ammonium persulfate 2.0 parts by weight and water 20 parts by weight The aqueous solution in which the parts were mixed was dropped into the reactor over 4 hours. And after completion | finish of dripping, 95 degreeC was further maintained for 2 hours, and the polycarboxylic acid (5) of the weight average molecular weight 20000 was obtained.

(Comparative Example 1)
A glass reaction vessel equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube, and reflux condenser was charged with 129.6 parts by weight of water, and the reactor was purged with nitrogen under stirring. The temperature was raised to 95 ° C. An aqueous solution obtained by mixing 171.4 parts by weight of monomer [A] obtained by the method of Production Example 5 and 50 parts by weight of water, 42.9 parts by weight of methacrylic acid, 3.5 parts by weight of 3-mercaptopropionic acid and water An aqueous solution mixed with 20 parts by weight and an aqueous solution mixed with 1.8 parts by weight of ammonium persulfate and 20 parts by weight of water were dropped into the reactor over 4 hours each. And after completion | finish of dripping, 95 degreeC was further maintained for 2 hours, and the comparison polycarboxylic acid (6) of the weight average molecular weight 12000 was obtained.

(Comparative Example 2)
A glass reaction vessel equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube, and reflux condenser was charged with 179.2 parts by weight of water, and the reactor was purged with nitrogen under stirring. The temperature was raised to 95 ° C. An aqueous solution obtained by mixing 70.7 parts by weight of the monomer [B] obtained by the method of Production Example 6 and 20 parts by weight of water, 200 parts by weight of the monomer [E] obtained by the method of Production Example 9, methacryl Reaction of 5.0 parts by weight of acid, 2.3 parts by weight of 3-mercaptopropionic acid and 20 parts by weight of water, and an aqueous solution of 1.2 parts by weight of ammonium persulfate and 20 parts by weight of water over 4 hours each It was dripped in the vessel. And after completion | finish of dripping, 95 degreeC was further maintained for 2 hours, and the comparison polycarboxylic acid (7) of the weight average molecular weight 21000 was obtained.

(Comparative Example 3)
A glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube, and a reflux condenser was charged with 158.3 parts by weight of water, and the reactor was purged with nitrogen under stirring. The temperature was raised to 95 ° C. 110.0 parts by weight of monomer [D] obtained by the method of Production Example 8, 110.0 parts by weight of monomer [F] obtained by the method of Production Example 10, 18.5 parts by weight of methacrylic acid, An aqueous solution in which 2.5 parts by weight of 3-mercaptopropionic acid and 20 parts by weight of water were mixed, and an aqueous solution in which 1.3 parts by weight of ammonium persulfate and 20 parts by weight of water were mixed were dropped into the reactor over 4 hours. And after completion | finish of dripping, 95 degreeC was further maintained for 2 hours, and the polycarboxylic acid (8) of the weight average molecular weight 21000 was obtained.

  The following table summarizes the details of the polycarboxylic acids (1) to (5) and the polycarboxylic acids (6) to (8) obtained in the above Examples 1 to 5 and Comparative Examples 1 to 3. 5.

[Concrete test]
Using each of the polycarboxylic acids (1) to (5) of Examples obtained above and the polycarboxylic acids (6) to (8) of Comparative Examples as cement admixtures, the cement composition was obtained according to the following concrete test method. A slump flow value, a change over time in the slump flow value, an air amount, and a bubble spacing coefficient were measured by the following methods. In addition, the material used for the test, the forced kneading mixer, and the measuring instruments are conditioned under the test temperature atmosphere so that the temperature of the concrete composition is 20 ° C. The kneading and each measurement are performed at the test temperature. Performed under atmosphere.

(Concrete test mix)
Unit cement amount: 573.3 kg / m ³
Unit water amount: 172.0 kg / m ³ (including admixtures such as polymer and antifoaming agent)
Unit fine bone agent amount: 737.2 kg / m ³
Unit coarse bone amount: 866.0 kg / m ³
Water / cement ratio (W / C): 30.0%
Aggregate amount ratio (s / a): 47.0%
Cement: Taiheiyo Cement Co., Ltd. Ordinary Portland cement fine bone agent: Combining Kimitsu mountain sand and Kakegawa water-based land sand in 3/7 Coarse bone agent: Ome crushed stone (adjustment of concrete composition)
Each material was weighed so that the amount of kneading became 30 L depending on the above concrete raw materials and blending, and the materials were kneaded by the method described below using a bread mixer.

  First, the fine aggregate was kneaded for 10 seconds, then cement was added and kneaded for 10 seconds. Thereafter, a predetermined amount of tap water containing a cement admixture was added and kneaded for 90 seconds. After that, coarse aggregate was further added and kneaded for 90 seconds to obtain a concrete composition. In the evaluation test, the kneading start time after adding tap water containing a cement admixture was set to zero minutes.

(Adjustment of cement admixture)
It adjusted using the cement dispersing agent and the antifoamer. As the cement dispersant, any one of polycarboxylic acids (1) to (5) and comparative polycarboxylic acids (6) to (8) according to Examples was used. The required amount of cement dispersant was calculated using the amount of non-volatile content in the cement dispersant measured by the following method. A commercially available oxyalkylene-based antifoaming agent was used as the antifoaming agent, and the air amount was adjusted to 5.0 ± 1.0% by volume.

(Measurement of non-volatile content)
About 0.5 g of the polymer aqueous solution was measured in an aluminum cup, and about 1 g of ion-exchanged water was added to spread it uniformly. This was dried at 130 ° C. for 1 hour in a nitrogen atmosphere, and the nonvolatile content was calculated from the weight difference before and after drying.

(Evaluation test items and measurement methods)
Slump flow value: JIS-A-1101
Compressive strength: JIS-A-1108 (specimen preparation: JIS-A-1132)
Air volume: JIS-A-1128
Bubble spacing coefficient: details of measurement method for bubble spacing coefficient The air gap analyzer (AVA; trade name, manufactured by German Instruments Co., Ltd.) was used to measure the bubble spacing coefficient, which is an index of freeze-thaw resistance. In advance, glycerin (reagent (manufactured by Wako Pure Chemical Industries, Ltd.)) and water were mixed at a weight ratio of glycerin / water = 83/17 to prepare an AVA measurement solution.

  After measuring the air amount of fresh concrete taken out from the mixer (air amount = 5 ± 1%), aggregates of 6 mm or more were removed, and 20 ml of mortar for evaluating the air gap coefficient was collected in a dedicated syringe. About 2000 ml of water was injected into the measurement column and air bubbles adhering to the column wall were removed with a brush, and then 250 ml of the AVA measurement solution prepared in advance was injected into the bottom of the column using a dedicated instrument. After the injection, a bubble collecting Petri dish was installed near the water surface of the column and fixed to the measurement part. After 20 ml of the mortar collected in the syringe was injected into the bottom of the column, the mortar was stirred for 30 seconds to sufficiently release the entrained air of the mortar into the liquid. The bubble spacing coefficient was measured by measuring the bubbles released over time.

  In calculating the bubble spacing coefficient, in addition to the amount of fresh concrete air, a value (mortar volume ratio) excluding the volume occupied by aggregates of 6 mm or more from the total concrete volume and the volume occupied by the paste (paste volume ratio) are required. The mortar volume ratio and paste volume ratio were calculated from the following formulas (I) and (II).

Mortar volume ratio (%) = [(V _B + V _W + V _S ) / 1000] × 100 (I)
Paste volume ratio (%) = [(V _B + V _W ) / 1000] × 100 (II)
V _B : volume of binder (= unit weight of binder (kg) / specific gravity of binder)
V _W : Volume of water and admixture (same as unit water volume)
V _S : Volume of aggregate of 6 mm or less (= unit amount of fine aggregate / specific gravity of fine aggregate)
(Test results)
The following three results are shown in Table 6 below.
(1) Addition amount (addition amount) = (use amount of cement admixture) / (cement weight) × 100 when the flow value immediately after preparation of the concrete composition is 500 ± 50 mm
(2) Retention rate after 60 minutes = (flow value after 60 minutes) / (flow value immediately after) × 100
(3) Bubble spacing coefficient

  From the results shown in Table 5 and Table 6, the difference in chain length distribution coefficient B between the two types of (poly) alkylene glycol (meth) acrylate monomers (polyethylene glycol methacrylate) used in the synthesis of polycarboxylic acid is 100 or more. It can be seen that in Examples 1 to 3, excellent slump retention performance (retention rate) is exhibited without increasing the addition amount as compared with Comparative Examples 1 and 2. In addition, since the bubble spacing coefficient is small, it was shown that a copolymer for cement admixture having excellent freeze-thaw resistance is provided.

  In addition, looking at the chain length distribution coefficient A that can be compared when the average number of added moles is the same, both of Example 1 and Example 3 are the two (poly) alkylene glycols used in the synthesis of the polycarboxylic acid. It can be seen that when the difference in chain length distribution coefficient A of the (meth) acrylate monomer (polyethylene glycol methacrylate) is 10 or more, more excellent slump retention performance (retention rate) is exhibited. As shown in Table 5, in Comparative Example 1, the difference in chain length distribution coefficient A between the two types of (poly) alkylene glycol (meth) acrylate monomers (polyethylene glycol methacrylate) used in the synthesis of polycarboxylic acid. Was 0.

Claims (4)

The following general formula (1):
In the formula, R ₁ represents a hydrogen atom or a methyl group, R ₂ O represents an oxyalkylene group, m represents an average added mole number of the oxyalkylene group, represents a number of 1 to 100, and R ₃ represents a hydrogen atom. Or an alkyl group having 1 to 22 carbon atoms,
₁ % by weight of a first (poly) alkylene glycol (meth) acrylate monomer (a) X represented by
The following general formula (2):
In the formula, R ₄ represents a hydrogen atom or a methyl group, R ₅ O represents an oxyalkylene group, n represents an average addition mole number of the oxyalkylene group, represents a number of 1 to 100, and R ₆ represents a hydrogen atom. Or an alkyl group having 1 to 22 carbon atoms,
₂ % by weight of a second (poly) alkylene glycol (meth) acrylate monomer (b) X
The following general formula (3):
In the formula, R ₇ represents a hydrogen atom or a methyl group, M ¹ represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group, or an organic amine group.
A carboxylic acid monomer represented by (c) Y wt%, and
Other monomers copolymerizable with the above (a) to (c) (d) Z wt%,
A step of polymerizing a monomer component containing a copolymer to obtain a copolymer, and
A step of neutralizing the copolymer with an alkaline substance, if necessary,
A method for producing a cement admixture copolymer (salt), comprising:
When X ₁ + X ₂ + Y + Z = 100, X ₁ : X ₂ : Y: Z = 5 to 90: 5 to 90: 5 to 40: 0 to 35 and X ₁ + X ₂ = 60 to 95,
Chain length distribution coefficient B1 of the first (poly) alkylene glycol (meth) acrylate monomer (a) and chain length distribution of the second (poly) alkylene glycol (meth) acrylate monomer (b) The manufacturing method, wherein the absolute value (| B1-B2 |) of the difference from the coefficient B2 is 100 or more. The average added mole number (m) of the oxyalkylene group in the first (poly) alkylene glycol (meth) acrylate monomer (a), and the second (poly) alkylene glycol (meth) acrylate monomer ( the average added mole number (n) of the oxyalkylene group in b) is substantially the same;
Chain length distribution coefficient A1 of the first (poly) alkylene glycol (meth) acrylate monomer (a) and chain length distribution of the second (poly) alkylene glycol (meth) acrylate monomer (b) The manufacturing method according to claim 1, wherein an absolute value (| A1-A2 |) of a difference from the coefficient A2 is 10 or more.   A cement composition comprising at least a copolymer (salt) for cement admixture produced by the production method according to claim 1, cement and water.   The content of the copolymer for cement admixture is 0.01 to 1.0% by weight with respect to cement, and the weight ratio of water / cement is 0.15 to 0.7. 4. The cement composition according to 3.