JP2002012461A - Cement admixture and cement composition using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement admixture which shows both good effect on prevention of cracking and good flowability with an addition of a small quantity, and a cement composition using it. SOLUTION: The cement admixture contains polyalkylene glycol (A) and polyalkylene glycol mono (meta) acrylate/unsaturated carboxylic acid copolymer (B). It is characterized in that the average molecular weight (X) of the (A) is 400-10000, and the average molecular weight (X) of (A) and average molecular weight (Y) of chain part of the polyalkylene glycol of the (B) satisfy that 0.9<(X/Y)<1.1, and a weight ratio of the (A) and the (B) satisfies (A)/(B)=0.02-0.3. The cement composition contains at least the cement admixture, water and cement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement admixture and a cement composition using the same. More specifically, the present invention relates to a cement admixture capable of imparting an excellent anti-cracking effect and fluidity by being mixed with a cement mixture such as cement paste, mortar, and concrete, and a cement composition containing the admixture. It is.

[0002]

2. Description of the Related Art Generally, cement paste, mortar,
Cement compounds such as concrete are used to construct civil engineering and building structures.However, conventionally, depending on the outside air temperature, humidity conditions, etc., unreacted moisture in the poured cement compound is Dissipation may cause drying shrinkage to progress, resulting in cracks in the cured product, and these cracks cause a problem in that strength of the structure is reduced and water tightness is reduced. Moreover, in recent years, there has been a movement to require guarantees against cracks due to drying shrinkage, for example, the Act on the Promotion of Ensuring Quality of Houses was enacted, where cracks in concrete were also subject to defect guarantees. Effective measures for suppressing shrinkage and preventing cracking have been demanded.

[0003] As a means for suppressing the drying shrinkage of the cement composition, the mixing water amount (unit water amount) of concrete is used.
Is effective. For example, the Architectural Institute of Japan has set an upper limit of 175 k
g. In order to satisfy this requirement, a high-performance water reducing agent such as, for example, a β-naphthalenesulfonic acid formaldehyde condensate salt has been generally used.

[0004] However, when a high-performance water reducing agent is used, the chemical and physical aggregation of the cement particles progresses with the lapse of time after mixing, and the fluidity tends to decrease over time, causing a problem in the construction work. There was a problem such as letting.

[0005] On the other hand, various studies have been made on a shrinkage reducing agent for suppressing drying shrinkage of a cement composition to a small value.
For example, Japanese Patent Publication No. 56-51148 discloses that
In Japanese Patent Publication No. 1-53214, a co-adduct of ethylene oxide and propylene oxide of a divalent to octavalent alcohol is used, and in Japanese Patent Publication No. 1-53215, an alkylene oxide adduct of a lower alkylamine is added. In JP-A-59-152253, polypropylene glycol in the oligomer region is used. In JP-B-6-6500, low-molecular-weight alcohols are used.
Alkylene oxide adducts of ethylhexanol have each been proposed.

However, since all of these shrinkage reducing agents are oligomers or low-molecular compounds having a molecular weight of about several hundreds or less, for example, “Development of Concrete Admixture and Latest Technology” (First Edition, September 1995) (Published by CMC Co., Ltd. on March 18), it is necessary to use a large amount of the standard amount of cement of 2 to 6% based on the weight of unit cement, and the cost of concrete increases. There was a problem.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cement admixture which exhibits an excellent effect of preventing cracking with a small amount of addition, and which has good fluidity.
And a cement composition using the same.

[0008]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that a polyalkylene glycol having a specific molecular weight is substantially equal to the average molecular weight of the polyalkylene glycol (the difference is constant). Polyalkylene glycol mono (meth) acrylates having a polyalkylene glycol chain portion of average molecular weight
The present inventors have found that the coexistence of an unsaturated carboxylic acid-based copolymer at a specific ratio results in a cement admixture which is extremely excellent in both the drying shrinkage reducing property and the dispersing property, and completed the present invention.

That is, the cement admixture of the present invention is a cement admixture containing a polyalkylene glycol (A) and a polyalkylene glycol mono (meth) acrylate / unsaturated carboxylic acid copolymer (B). The average molecular weight (X) of the polyalkylene glycol (A) is from 400 to 10,000, and the average molecular weight (X) of the polyalkylene glycol (A) and the polyalkylene glycol mono (meth) acrylate / unsaturated carboxylic acid The polyalkylene glycol chain portion of the acid copolymer (B) has an average molecular weight (Y) satisfying the following formula (1): 0.9 <(X / Y) <1.1 (1) The polyalkylene The weight ratio of the glycol (A) to the polyalkylene glycol mono (meth) acrylate / unsaturated carboxylic acid copolymer (B) is as follows: A) / (B) =
0.02 to 0.3.

The cement composition of the present invention contains at least the cement admixture of the present invention, water and cement.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The cement admixture of the present invention comprises a polyalkylene glycol (A) (hereinafter, may be simply referred to as component A) and a polyalkylene glycol mono (meth) acrylate / unsaturated carboxylic acid copolymer. Polymer (B)
(Hereinafter, may be simply abbreviated as B component). Hereinafter, each will be described in detail.

<Polyalkylene glycol (A)> The component A in the present invention is, for example, one represented by the following general formula (2).

R ¹ O (AO) m H (2) (In the formula (2), AO represents an oxyalkylene group having 2 to 18 carbon atoms (where the repeating units of each AO are the same and Or AO is 2
When it is in the form of a mixture of more than one kind, the repeating units of each AO may be added in block form or may be added in random form, and may be added alternately),
m is the average number of added moles of the oxyalkylene group,
R ¹ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. ) As R ¹ in the formula (2), in particular, 1 to 30 carbon atoms
Are preferable, a hydrocarbon group having 1 to 22 carbon atoms is more preferable, a hydrocarbon group having 1 to 18 carbon atoms is further preferable, and a hydrocarbon group having 1 to 12 carbon atoms is particularly preferable. In particular, in order to obtain a high drying shrinkage reduction property, a hydrocarbon group having 4 to 12 carbon atoms is preferable. Specific examples of R ¹ include, for example, an alkyl group having 1 to 30 carbon atoms; a phenyl group having 6 to 30 carbon atoms, an alkylphenyl group, a phenylalkyl group, a phenyl group substituted with an alkyl or phenyl group, and naphthyl. Aromatic group having a benzene ring such as a group; having 2 to 3 carbon atoms
0 alkenyl group; and the like.

AO in the formula (2) is particularly preferably a linear or branched oxyalkylene group having 2 to 8 carbon atoms. For example, an oxyethylene group, an oxypropylene group, an oxybutylene group, an oxystyrene group, etc. are mentioned, and among these, an oxyethylene group, an oxypropylene group, and an oxybutylene group are preferable.

Specific examples of the component A include carbon atoms such as methanol, ethanol, 2-propanol, 1-butanol, octanol, 2-ethyl-1-hexanol, nonyl alcohol, lauryl alcohol, cetyl alcohol, and stearyl alcohol. Unsaturated aliphatic alcohols having 3 to 30 carbon atoms, such as saturated aliphatic alcohols of all numbers 1 to 30, allyl alcohol, methallyl alcohol, crotyl alcohol, oleyl alcohol, and 3 to 30 carbon atoms, such as cyclohexanol Alicyclic alcohols, phenol, phenylmethanol (benzyl alcohol), methylphenol (cresol), p-
Ethylphenol, dimethylphenol (xylenol), pt-butylphenol, nonylphenol,
Alkoxypolyalkylene glycols obtained by adding an alkylene oxide having 2 to 18 carbon atoms to any of aromatic alcohols having 6 to 30 carbon atoms such as dodecylphenol, phenylphenol, and naphthol; polyethylene glycol, polypropylene And polyalkylene glycols such as glycol and polyethylene polypropylene glycol.

In the present invention, it is important that the component A has an average molecular weight (X) of 400 to 10,000. When the average molecular weight (X) of the component A is less than 400 and in the case where it exceeds 10,000, it is difficult to develop a sufficient drying shrinkage reducing property with a small amount. Preferably, component A has an average molecular weight (X) of 500 to 9,000, more preferably 700 to 8,000, even more preferably 900 to 7,000, and most preferably 1,000 to 6,000. It is good to be 000. In the present invention, the average molecular weight (X) of the component A can be easily calculated from the types of the terminal group and the oxyalkylene group of the component A and the average number of moles added. For example, in the general formula (2), when R ¹ is a methyl group, AO is ethylene oxide, and m is 25, the average molecular weight (X) of the component A is 32 + 44 × 25 = 1132. A
In order for the average molecular weight (X) of the component to be in the above-mentioned preferred range, the average addition mole number (m in the formula (2)) of the oxyalkylene group of the component A is preferably 10 to 220, and preferably 1 to 220.
5-200 is more preferable, 20-170 is still more preferable, and 22-150 is the most preferable.

<Polyalkylene glycol mono (meth)
Acrylate / unsaturated carboxylic acid copolymer (B)> The component B in the present invention is composed of a unit (I) derived from a polyalkylene glycol mono (meth) acrylate monomer represented by the following general formula (3). And a unit (II) derived from an unsaturated carboxylic acid monomer represented by the following general formula (4) as an essential constituent unit.

[0018]

Embedded image

(In the formula (3), R^Two, R^ThreeIs German
Stands for a hydrogen atom or a methyl group;^FourO is carbon
Represents an oxyalkylene group having 2 to 18 atoms (this
When each R ^FourO repeating units may be the same or
May be different, R^FourForm of a mixture of two or more types of O
If R^FourO repeating unit in block
May be added or randomly added
And may be added alternately), n is oxyalkyl
It is the average number of moles of the ene group, and the number of
I, R^FiveIs a hydrogen atom or a carbon atom having 1 to 30 carbon atoms.
Represents a hydride group. )

[0020]

Embedded image

(In the formula (4), R ⁶ , R ⁷ and R ⁸ each independently represent a hydrogen atom, a methyl group or (CH ₂ ) pCO
Represents an OX group, X represents hydrogen, a monovalent metal, a divalent metal, an ammonium group or an organic amine group;
Represents an integer of 2 (however, when two or more COOX groups are present in the formula (4), an anhydride may be formed). ) The R ⁵ in formula (3), in particular, from 1 to 30 carbon atoms
Are preferable, a hydrocarbon group having 1 to 22 carbon atoms is more preferable, a hydrocarbon group having 1 to 18 carbon atoms is further preferable, and a hydrocarbon group having 1 to 12 carbon atoms is particularly preferable. Examples of the hydrocarbon group having 1 to 30 carbon atoms include the same groups as those described as examples of R ¹ in the formula (2).

As R ⁴ O in the formula (3), a linear or branched oxyalkylene group having 2 to 8, preferably 2 to 4 carbon atoms is particularly suitable. For example, oxyethylene group, oxypropylene group, oxybutylene group, oxystyrene group and the like, among them,
An oxyethylene group, an oxypropylene group, and an oxybutylene group are preferred.

Examples of the monomer (a) giving the structural unit (I) represented by the formula (3) include, for example, an adduct obtained by adding an alkylene oxide having 2 to 18 carbon atoms to (meth) acrylic acid. Methanol, ethanol, 2-propanol, 1-butanol, octanol, 2-ethyl-1-
Hexanol, nonyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, etc., having 1 to 30 carbon atoms, such as saturated aliphatic alcohols, allyl alcohol, methallyl alcohol, crotyl alcohol, and oleyl alcohol, having 3 to 30 carbon atoms. 3 carbon atoms such as unsaturated aliphatic alcohols and cyclohexanol
To 30 alicyclic alcohols, phenol, phenylmethanol (benzyl alcohol), methylphenol (cresol), p-ethylphenol, dimethylphenol (xylenol), pt-butylphenol,
An alkoxypolyalkylene glycol obtained by adding an alkylene oxide having 2 to 18 carbon atoms to any of aromatic alcohols having 6 to 30 carbon atoms such as nonylphenol, dodecylphenol, phenylphenol, and naphthol; and (meth) acrylic Ester compounds with acids;
And the like.

Specific examples of the monomer (a) include, for example,
Various polyalkylene glycol mono (meth) acrylates such as polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and polybutylene glycol mono (meth) acrylate; methoxy polyethylene glycol mono (meth) acrylate, ethoxy polyethylene glycol mono (Meth) acrylate, 1-propoxy polyethylene glycol mono (meth) acrylate, 2-propoxy polyethylene glycol mono (meth) acrylate, 1-butoxy polyethylene glycol mono (meth) acrylate, 2-butoxy polyethylene glycol mono (meth)
Acrylate, 2-methyl-1-propoxy polyethylene glycol mono (meth) acrylate, 2-methyl-
2-propoxy polyethylene glycol mono (meth) acrylate, cyclohexyloxy polyethylene glycol mono (meth) acrylate, 1-octyloxy polyethylene glycol mono (meth) acrylate, 2-
Ethyl-1-hexyloxy polyethylene glycol mono (meth) acrylate, nonylalkoxy polyethylene glycol mono (meth) acrylate, lauryl alkoxy polyethylene glycol mono (meth) acrylate, cetyl alkoxy polyethylene glycol mono (meth) acrylate, stearyl alkoxy polyethylene glycol mono ( (Meth) acrylate, phenoxy polyethylene glycol mono (meth) acrylate, phenylmethoxy polyethylene glycol mono (meth) acrylate, methylphenoxy polyethylene glycol mono (meth) acrylate, p-ethylphenoxy polyethylene glycol mono (meth) acrylate, dimethylphenoxy polyethylene glycol mono (Meth) acrylate, pt-butyl Ruphenoxy polyethylene glycol mono (meth) acrylate, nonylphenoxy polyethylene glycol mono (meth) acrylate, dodecylphenoxy polyethylene glycol mono (meth) acrylate, phenylphenoxy polyethylene glycol mono (meth) acrylate, naphthoxy polyethylene glycol mono (meth) acrylate, Various alkoxy such as esterified products of allyl alcohol and acrylic acid with ethylene oxide added, esterified products of methallyl alcohol with added ethylene oxide and acrylic acid, and esterified products of crotyl alcohol and acrylic acid with added ethylene oxide Polyethylene glycol mono (meth) acrylates; methoxy polypropylene glycol mono (meth) acrylate, Toxic polypropylene glycol mono (meth) acrylate, 1-propoxy polypropylene glycol mono (meth) acrylate, 2-propoxy polypropylene glycol mono (meth) acrylate, 1-butoxy polypropylene glycol mono (meth) acrylate, 2-butoxy polypropylene glycol mono (meth) ) Acrylates, esterified products of allyl alcohol and acrylic acid to which propylene oxide has been added, esterified products of methallyl alcohol to which propylene oxide has been added and acrylic acid, and crotyl alcohol to which propylene oxide has been added and acrylic acid Various alkoxypolypropylene glycol mono (meth) acrylates such as esterified products; methoxypolybutylene glycol mono (meth) acrylate, Toxipolybutylene glycol mono (meth) acrylate, 1-propoxypolybutylene glycol mono (meth) acrylate, 2-propoxypolybutylene glycol mono (meth) acrylate, 1-butoxypolybutylene glycol mono (meth) acrylate, 2-butoxypoly Butylene glycol mono (meth) acrylate,
Esterified product of allyl alcohol and acrylic acid added with butylene oxide, esterified product of methallyl alcohol added with butylene oxide and acrylic acid,
Various alkoxypolybutylene glycol mono (meth) acrylates such as esterified crotyl alcohol and acrylic acid to which butylene oxide is added; methoxypolyethylene glycol polypropylene glycol mono (meth) acrylate, methoxypolyethylene glycol polybutylene glycol mono (meth) acrylate ) Acrylate,
Various alkoxypolyalkylene glycol mono (meth) acrylates such as esterified products of alcohol and (meth) acrylic acid to which two or more kinds of alkylene oxides are added, such as methoxypolyethylene glycol polystyrene glycol mono (meth) acrylate; Can be These monomers (a) may be used alone or in combination of two or more.

The monomer (a) and the structural unit (I)
The average number of moles of addition of the oxyalkylene group (n in the formula (3)) is from 8 to 250. If the average number of moles is small, the hydrophilicity decreases, while the average number of moles increases. Since the reactivity tends to decrease as the amount increases, the average number of moles added is preferably from 10 to 220, more preferably from 15 to 200, still more preferably from 20 to 170, and further preferably from 22 to 170.
150 is particularly preferred.

As the monomer (a) (structural unit (I)), one type may be used alone, or two or more types may be used in combination. In order to ensure the balance between the properties and the hydrophobicity, it is preferable that an oxyethylene group is essential as the oxyalkylene group, and it is more preferable that 50 mol% or more is an oxyethylene group. When two or more monomers (a) (structural units (I)) are used, at least one of the monomers (a)
The oxyalkylene group of (Structural Unit (I)) preferably contains an oxyethylene group.

The content of the structural unit (I) is not particularly limited, but is suitably at least 5% by weight, preferably at least 10% by weight, and more preferably at least 10% by weight of the whole copolymer as the component B.
% By weight or more, more preferably 30% by weight or more, particularly preferably 40% by weight or more, and most preferably 50% by weight or more.

Specific examples of the monomer (b) which provides the structural unit (II) represented by the formula (4) include, for example, acrylic acid, methacrylic acid, crotonic acid and metal salts thereof.
Unsaturated monocarboxylic acid monomers such as ammonium salts and amine salts; unsaturated dicarboxylic acid monomers such as maleic acid, itaconic acid, citraconic acid and fumaric acid, and their metal salts, ammonium salts and amine salts And anhydrides of unsaturated dicarboxylic acid monomers such as maleic anhydride, itaconic anhydride and citraconic anhydride. Among these, unsaturated monocarboxylic acid monomers are preferable, and (meth) acrylic acid and salts thereof are particularly preferable. These monomers (b) may be used alone or in combination of two or more.

The content of the structural unit (II) is not particularly limited, but in the present invention, particularly, the number of carboxyl group milliequivalents when all the carboxyl groups in the component B are converted into an unneutralized type. Is preferably set to 0.25 to 5.00 meq per 1 g of the copolymer as the B component. This carboxyl group milliequivalent number is more preferably 0.25 to 4.50 meq / g, further preferably 0.25 to 4.00 meq / g, particularly preferably 0.25 to 3.50 meq / g, and most preferably. It is good to be 0.30 to 3.00 meq / g. When the carboxyl group milliequivalent number is less than 0.25 meq / g, the dispersibility of the copolymer as the B component is significantly reduced,
When it is used as a cement composition, it is difficult to obtain sufficient fluidity. On the other hand, when it exceeds 5.00 meq / g, the fluidity of the cement composition tends to decrease with time.

The number of carboxyl group milliequivalents when all the carboxyl groups in the component B are converted into an unneutralized type can be calculated as follows. For example,
Using acrylic acid as the monomer (b), the monomer (a) /
When copolymerized at a composition ratio of monomer (b) = 90/10 (% by weight), the molecular weight of acrylic acid is 72, so that the number of carboxyl group milliequivalents per gram of the copolymer is (0.
1/72) × 1000 = 1.39 (meq / g) (calculation example 1). Further, for example, when sodium methacrylate is used as the monomer (b) and copolymerized at a composition ratio of monomer (a) / monomer (b) = 90/10 (% by weight), sodium methacrylate is used. Has a molecular weight of 108,
Since the molecular weight of methacrylic acid is 86, 1 g of the copolymer
The number of carboxyl groups per milliequivalent is (0.1 × 86
/108)/｛(0.9+0.1×86/108)×8
6｝ × 1000 = 0.95 (meq / g) (calculation example 2). In addition, when methacrylic acid is used at the time of polymerization and the carboxyl group derived from methacrylic acid is neutralized with sodium hydroxide after polymerization, the same calculation as in Calculation Example 2 can be performed. Further, for example, using sodium maleate as the monomer (b), the monomer (a) / monomer (b) = 90/1
When copolymerized at a composition ratio of 0 (% by weight), the molecular weight of sodium maleate is 160, the molecular weight of maleic acid is 116, and maleic acid has two carboxyl groups in one molecule. , The number of carboxyl group milliequivalents per gram of the copolymer is (0.1 × 116/16
0) / ｛(0.9 + 0.1 × 116/160) × 116
/2｝×1000=1.29 (meq / g) (calculation example 3).

The structural unit (I) and the structural unit (I
The ratio with (I) is not particularly limited as long as it satisfies the range of the number of carboxyl groups in terms of the number of milliequivalents of carboxyl groups when all the carboxyl groups in the component B are converted into an unneutralized form. I) / Structural unit (II) = 50-
99/1 to 50 (% by weight) is preferred. More preferably, the structural unit (I) / the structural unit (II) = 55 to 99/1 to 1
45 (% by weight), more preferably 60 to 98/2 to 4
0 (% by weight), particularly preferably 65 to 98/2 to 3
5 (% by weight), most preferably 70 to 97/3 to 30
(% By weight).

The copolymer as the component B may be, if necessary, in addition to the structural unit (I) represented by the general formula (3) and the structural unit (II) represented by the general formula (4). And other structural units (III).

Monomer (c) giving structural unit (III)
Is not particularly limited as long as it is a monomer copolymerizable with the monomers (a) and (b). For example, unsaturated monomers such as maleic acid, fumaric acid, itaconic acid and citraconic acid can be used. Half-esters and diesters of dicarboxylic acids and alcohols having 1 to 30 carbon atoms; half-amides and diamides of the unsaturated dicarboxylic acids and amines having 1 to 30 carbon atoms; Half-esters and diesters of an alkyl (poly) alkylene glycol obtained by adding 1 to 500 moles of an alkylene oxide of the above and the unsaturated dicarboxylic acids; glycols having 2 to 18 carbon atoms with the unsaturated dicarboxylic acids or addition of these glycols Half ester and diester with a polyalkylene glycol having 2 to 500 moles;
Half amide of maleamic acid and a glycol having 2 to 18 carbon atoms or a polyalkylene glycol having an addition mole number of 2 to 500 of these glycols; triethylene glycol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate (Poly) alkylene glycol di (meth) acrylates such as propylene glycol di (meth) acrylate and (poly) ethylene glycol (poly) propylene glycol di (meth) acrylate; hexanediol di (meth) acrylate, trimethylolpropanetri Polyfunctional (meth) acrylates such as (meth) acrylate and trimethylolpropane di (meth) acrylate; (poly) alkylene such as triethylene glycol dimaleate and polyethylene glycol dimaleate Glycol dimaleate like; vinyl sulfonate, (meth) allyl sulfonate, 2- (meth) acryloxyethyl sulfonate, 3- (meth) acryloxy propyl sulfonate, 3- (meth) acryloxy-2-hydroxypropyl sulfonate, 3-
(Meth) acryloxy-2-hydroxypropylsulfophenyl ether, 3- (meth) acryloxy-2-hydroxypropyloxysulfobenzoate, 4- (meth) acryloxybutylsulfonate, (meth) acrylamide methylsulfonic acid, (meth) acrylamide Unsaturated sulfonic acids such as ethylsulfonic acid, 2-methylpropanesulfonic acid (meth) acrylamide and styrenesulfonic acid, and monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts thereof; methyl (meth)
Esters of unsaturated monocarboxylic acids such as acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, glycidyl (meth) acrylate, methyl crotonate, ethyl crotonate, propyl crotonate and alcohols having 1 to 30 carbon atoms ; Methyl (meth)
Amides of unsaturated monocarboxylic acids such as acrylamide with amines having 1 to 30 carbon atoms; styrene, α
Vinyl aromatics such as -methylstyrene, vinyltoluene and p-methylstyrene; 1,4-butanediol mono (meth) acrylate, 1,5-pentanediol mono (meth) acrylate, 1,6-hexanediol mono ( Alkanediol mono (meth) acrylates such as meth) acrylates; dienes such as butadiene, isoprene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene; (meth) acrylamide, (meth) Acrylic alkyl amide, N-methylol (meth)
Unsaturated amides such as acrylamide and N, N-dimethyl (meth) acrylamide; (meth) acrylonitrile,
unsaturated cyanides such as α-chloroacrylonitrile; unsaturated esters such as vinyl acetate and vinyl propionate;
Unsaturations such as aminoethyl (meth) acrylate, methylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, dibutylaminoethyl (meth) acrylate, and vinylpyridine Amines; divinyl aromatics such as divinylbenzene; cyanurates such as triallyl cyanurate; allyls such as (meth) allyl alcohol and glycidyl (meth) allyl ether; methoxy polyethylene glycol monovinyl ether, polyethylene glycol monovinyl ether and methoxy Vinyl ethers or allyl ethers such as polyethylene glycol mono (meth) allyl ether and polyethylene glycol mono (meth) allyl ether; polydimethylsiloxane propylaminomaleina De acid, polydimethylsiloxane aminopropylene amino maleamic acid, polydimethylsiloxane - bis - (propylamino maleamic acid), polydimethylsiloxane - bis - (dipropylene amino maleamic acid), polydimethylsiloxane -
(1-propyl-3-acrylate), polydimethylsiloxane- (1-propyl-3-methacrylate), polydimethylsiloxane-bis- (1-propyl-3-acrylate), polydimethylsiloxane-bis- (1-
Siloxane derivatives such as propyl-3-methacrylate); and one or more of these can be used.

The content of the structural unit (III) is not particularly limited as long as the effect of the present invention is not impaired.
It is preferably 70% by weight or less, more preferably 60% by weight or less, further preferably 50% by weight or less, particularly preferably 40% by weight or less of the whole copolymer as the component B.
Most preferred is 30% by weight or less.

The ratio of each structural unit constituting the copolymer as the component B is as follows: structural unit (I) / structural unit (II) / structural unit (III) = 5 to 99/1 to 50/0 to 70 ( % By weight), and furthermore, the structural unit (I) / the structural unit (II) / the structural unit (III) = 10 to 99/1 to 4
5/0 to 60 (% by weight) is preferred, and 20 to 98/2 to
40/0 to 50 (% by weight) is more preferable, and 30 to 98
/ 2 to 35/0 to 50 (% by weight) is more preferable.
0 to 98/2 to 35/0 to 40 (% by weight) are particularly preferred, and 50 to 97/3 to 30/0 to 30 (% by weight) are most preferred. However, the structural unit (I) and the structural unit (I
The sum of I) and structural unit (III) is always 100% by weight.

The method for obtaining the copolymer as the component B is not particularly limited. For example, the monomer (for example, the monomer (a)) and the structural unit (II) which give the structural unit (I) can be obtained. (For example, the monomer (b))
As an essential component, and if necessary, a structural unit (II
What is necessary is just to polymerize the monomer component containing the monomer which gives I) (for example, the said monomer (c)) using a polymerization initiator. The polymerization can be performed by a known method such as polymerization in a solvent or bulk polymerization. Specifically, for example, a polymerization initiator such as ammonium or an alkali metal persulfate, hydrogen peroxide, or an azo compound is used in water or a lower alcohol such as methyl alcohol, ethyl alcohol, or isopropyl alcohol. What is necessary is just to perform a polymerization reaction in the range of -120 degreeC.

In order to control the molecular weight of the obtained copolymer, a thiol chain transfer agent such as mercaptoethanol and 3-mercaptopropionic acid can be used in combination.

The copolymer thus obtained may be used as it is as the B component, but if necessary, may be further neutralized with an alkaline substance and used as a polymer salt. Preferable examples of the alkaline substance include inorganic substances such as hydroxides and carbonates of monovalent or divalent metals represented by sodium hydroxide; ammonia; organic amines; and the like. Further, the solvent used in producing the copolymer may be evaporated and solidified before use.

In the present invention, it is important that the average molecular weight (Y) of the polyalkylene glycol chain portion of the component B satisfies the following formula (1) with respect to the average molecular weight (X) of the component A. is there.

0.9 <(X / Y) <1.1 (1) When (X / Y) is within this range, that is, the average molecular weight (X) of the component A and the polyalkylene glycol chain portion of the component B Only when the average molecular weights (Y) are substantially equal to each other, the polyalkylene glycol of the component A and the polyalkylene glycol chain portion of the component B show a specific interaction, and a small amount of the polyalkylene glycol can sufficiently reduce the drying shrinkage. It can be expressed. In the present invention, the average molecular weight (Y) of the polyalkylene glycol chain portion of the component B is an average molecular weight of a portion corresponding to O (R ⁴ O) n-R ⁵ in the general formula (3), and It can be easily calculated as follows. For example, in the general formula (3), R
^{When 5} is a methyl group, R ⁴ O is ethylene oxide, and n is 25, the average molecular weight (Y) of the polyalkylene glycol chain portion of the B component is 31 + 44 × 25
= 1131.

As described above, the weight average molecular weight of the copolymer as the component B is not particularly limited as long as the average molecular weight (Y) of the polyalkylene glycol chain portion satisfies the above formula (1). , Preferably 1,000 to 500,0
00, more preferably in the range of 5,000 to 300,000. Component B has a weight average molecular weight of 1,0
If it is less than 00, or if it exceeds 500,000, any case is not preferable because the dispersion performance is reduced.

In the cement admixture of the present invention, the weight ratio of the component A and the component B is (A) / (B) = 0.02.
It is important that it is contained so as to be 0.3.
The weight ratio of the component A and the component B is (A) / (B) = 0.02
If less than, the drying shrinkage reduction effect is low, while
If it exceeds 0.3, the fluidity will be low. Only when the weight ratio (A) / (B) of the component A and the component B is within the above range, the drying shrinkage reducing property and the fluidity can be satisfied at the same time.

The method for producing the cement admixture of the present invention is not particularly limited. For example, as described above, the monomer (a) and the monomer (b) are copolymerized to obtain the component B. May be synthesized, and both components may be mixed such that the B component and the A component are in the above-mentioned weight ratio range. In this case, A component and B
Components having the same structure as the polyalkylene glycol chain portion of the component can also be easily produced.

As another method for producing the cement admixture of the present invention, for example, when an esterification reaction is carried out using polyalkylene glycol and (meth) acrylic acid, unreacted polyalkylene glycol (= A component) The reaction is stopped under the condition that the carboxylic acid remains, and then the polymerization reaction is carried out while the unreacted polyalkylene glycol (= A component) remains, and the B component (polyalkylene glycol mono (meth) acrylate / unsaturated carboxylic acid-based (Polymer) may be synthesized so that the weight ratio of the component A and the component B is within the above-mentioned weight ratio range. Further, the component A may be further added later to adjust the weight ratio of the component A to the component B so as to be within the above range.

As another method for producing the cement admixture of the present invention, for example, an unsaturated carboxylic acid monomer (b)
Is directly esterified with an alkoxypolyalkylene glycol having a hydrocarbon group having 1 to 30 carbon atoms at one end with respect to at least a part of a carboxyl group of a polymer obtained by polymerizing a monomer component containing as an essential component. The component B is synthesized by a so-called “polymer post-esterification reaction”, and the esterification reaction is stopped so that the weight ratio between the polyalkylene glycol (= A component) and the B component falls within the above-mentioned weight ratio range. It may be. In this case, the component A may be further added later to adjust the weight ratio of the component A to the component B so as to be within the above range. As described above, when the component B is obtained by the so-called “polymer post-esterification reaction”, the carboxyl group milliequivalent number when all the carboxyl groups in the component B are converted to the non-neutralized type is as described above. Since it cannot be calculated by a calculation example based on the monomer, it may be calculated by measuring the acid value of the polymer in consideration of the counter ion species of the carboxyl group of the polymer.

<Cement composition> The cement composition of the present invention contains the cement admixture of the present invention, cement and water as essential components. Examples thereof include cement paste and bone such as sand and gravel. It is used as a mortar, concrete, self-leveling material, plaster, etc. by blending materials. In particular, it can be suitably used for mortar and concrete requiring high fluidity such as high fluidity concrete and self-compacting concrete.

The cement is a substance having a property of being hardened by a hydration reaction, and specifically, various kinds of Portland cements such as ordinary, fast and super fast, etc .; blast furnace slag, fly ash, Various cements obtained by mixing Cinder Ash, Clinker Ash, Husk Ash, Silica, etc .; white cement; ultra-rapid hardening cement; hydraulic cement such as alumina cement; hydraulic material such as gypsum;

In the cement composition of the present invention, (1)
The amount of cement used per m ³ and the amount of water used (unit water amount) are not particularly limited, but are, for example, 100 to 185 kg / m ³ , preferably 120 to 17 kg / m ³ .
5 kg / m ³ , cement consumption 250-800 kg / m
³ , preferably 270 to 800 kg / m ³ , water / cement (weight ratio) = 0.10 to 0.7, preferably 0.2 to 0.7
0.65 is recommended. As described above, the cement composition of the present invention can be widely used from poor blending to rich blending, and can be used for any of high-strength concrete with a large unit cement content and poor blended concrete with a unit cement amount of 300 kg / m ³ or less. Is also effective.

In the cement composition of the present invention, the proportion of the cement admixture of the present invention (component A + component B) is as follows:
Although not particularly limited, the cement admixture (A component + B component) of the present invention is added in an amount of 0.001 to 15 with respect to the weight of the cement.
% By weight, preferably 0.01 to 10% by weight, more preferably 0.02 to 5% by weight, still more preferably 0.05 to 5% by weight.
The content is preferably 3% by weight, particularly preferably 0.1 to 2% by weight. In particular, when using hydraulic cement for mortar or concrete, the cement admixture of the present invention (A component + B component) is used in an amount of 0.01 to 10% by weight, preferably 0.01 to 10% by weight, based on the weight of the hydraulic cement. The content is preferably 0.02 to 5% by weight, more preferably 0.05 to 3% by weight, particularly preferably 0.1 to 2% by weight. If the total amount of the component A and the component B is less than 0.01% by weight, it is difficult to obtain sufficient drying shrinkage reduction and fluidity. In effect, it will plateau and become economically disadvantageous.

The cement composition of the present invention may contain a known cement dispersant. The known cement dispersant that can be used is not particularly limited, and various sulfonic acid-based dispersants having a sulfonic acid group in the molecule and various polycarboxylic acid-based compounds having a polyoxyalkylene chain and a carboxyl group in the molecule. And dispersants.

Examples of the sulfonic acid-based dispersants include lignin sulfonic acid salt, naphthalene sulfonic acid formaldehyde condensate, melamine sulfonic acid formaldehyde condensate, polystyrene sulfonic acid salt, aminoaryl sulfonic acid-phenol-formaldehyde condensate, and the like. Examples include aminosulfonic acid-based dispersants.

Examples of the polycarboxylic acid-based dispersant include polyalkylene glycol mono (meth) acrylate having a polyoxyalkylene chain obtained by adding an alkylene oxide having 2 to 3 carbon atoms in an average addition mole number of 2 to 300. Obtained by copolymerizing a monomer component containing as essential components three types of monomers consisting of a terpolymer monomer, a (meth) acrylic acid monomer and an alkyl (meth) acrylate A polyalkylene glycol mono (meth) acrylate monomer and a (meth) acrylic monomer having a polyoxyalkylene chain obtained by adding an alkylene oxide having 2 to 3 carbon atoms in an average addition mole number of 2 to 300; And (meth) allylsulfonic acid (salt) or vinylsulfonic acid (salt) or p- (meth) allyloxybenzenesulfonic acid (salt) 2-5 ethylene oxide average addition molar number; copolymers obtained by copolymerizing a monomer component containing as essential components three monomers consisting and either
Monomers of three kinds consisting of a polyalkylene glycol mono (meth) acrylate monomer having a polyoxyalkylene chain to which 0 is added, a (meth) acrylic acid monomer, and (meth) allylsulfonic acid (salt) A copolymer obtained by graft-polymerizing (meth) acrylamide and / or 2- (meth) acrylamido-2-methylpropanesulfonic acid to a copolymer obtained by copolymerizing a monomer component containing a polymer as an essential component; A polyethylene glycol mono (meth) acrylate monomer having a polyoxyalkylene chain obtained by adding 5 to 50 ethylene oxide at an average addition mole number and ethylene oxide at an average addition mole number of 1 to 50
Polyethylene glycol mono (meth) allyl ether-based monomer having 30-added polyoxyalkylene chain, (meth) acrylic acid-based monomer and (meth) allylsulfonic acid (salt) or p- (meth) allyloxybenzene A copolymer obtained by copolymerizing a monomer component containing as an essential component four types of monomers composed of any one of sulfonic acids (salts); an alkylene oxide having 2 to 18 carbon atoms in an average addition mole number A copolymer obtained by copolymerizing a monomer component containing, as essential components, a polyalkylene glycol mono (meth) allyl ether-based monomer having a polyoxyalkylene chain having 2 to 300 additions and a maleic acid-based monomer. Combined; alkylene oxide having 2 to 4 carbon atoms is added in an average addition mole number of 2 to 2.
Obtained by copolymerizing a monomer component containing, as essential components, a polyalkylene glycol mono (meth) allyl ether-based monomer having a 300-added polyoxyalkylene chain and a polyalkylene glycol ester-based monomer of maleic acid. Copolymer obtained; polyalkylene glycol 3-methyl-3-butenyl ether monomer having a polyoxyalkylene chain obtained by adding alkylene oxide having 2 to 4 carbon atoms by an average addition mole number of 2 to 300, and maleic acid A copolymer obtained by copolymerizing a monomer component containing a monomer as an essential component; and the like. In addition, these publicly known cement dispersants may be used in combination of two or more.

When the above-mentioned known cement dispersant is used,
Although the ratio of the cement admixture of the present invention (A component + B component) to the known cement dispersant cannot be univocally determined depending on the type, blending and test conditions of the known cement dispersant used, It is preferably in the range of 5:95 to 95: 5 (weight ratio), and more preferably in the range of 10:90 to 90:10 (weight ratio).

The cement composition of the present invention may further comprise, for example, the following (1) to (20) in addition to the above-mentioned known cement dispersants.
And other known cement additives (materials).

(1) Water-soluble polymer substance: Polymerization of unsaturated carboxylic acid such as polyacrylic acid (sodium), polymethacrylic acid (sodium), polymaleic acid (sodium), and sodium salt of acrylic acid / maleic acid copolymer object;
Nonionic cellulose ethers such as methylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, carboxyethylcellulose, and hydroxypropylcellulose; yeast glucan, xanthan gum, β-1,
Polysaccharides produced by microbial fermentation such as 3-glucans (either linear or branched and, for example, curdlan, paramylon, bakiman, scleroglucan, laminaran, etc.); polyacrylamide; polyvinyl Alcohol; starch; starch phosphate; sodium alginate; gelatin; copolymers of acrylic acid having an amino group in the molecule and quaternary compounds thereof.

(2) Polymer emulsion: copolymers of various vinyl monomers such as alkyl (meth) acrylate and the like.

(3) Retardants: gluconic acid, glucoheptonic acid, arabonic acid, malic acid or citric acid, and oxy acids such as inorganic salts or organic salts thereof such as sodium, potassium, calcium, magnesium, ammonium and triethanolamine. Carboxylic acids; glucose, fructose, galactose, saccharose, xylose, apiose, ribose, monosaccharides such as isomerized sugars, disaccharides, oligosaccharides such as trisaccharides, oligosaccharides such as dextrins, and polysaccharides such as dextran; Saccharides such as molasses and the like containing them; sugar alcohols such as sorbitol; magnesium silicofluoride; phosphoric acid and salts or borates thereof;
Aminocarboxylic acids and salts thereof; alkali-soluble proteins;
Humic acid; tannic acid; phenol; polyhydric alcohols such as glycerin; aminotri (methylene phosphonic acid);
-Hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and phosphonic acids such as alkali metal salts and alkaline earth metal salts thereof, and derivatives thereof.

(4) Early strength agent / promoter: calcium chloride,
Calcium nitrite, calcium nitrate, calcium bromide,
Soluble calcium salts such as calcium iodide; chlorides such as iron chloride and magnesium chloride; sulfates; potassium hydroxide;
Sodium hydroxide; carbonate; thiosulfate; formate such as formic acid and calcium formate; alkanolamine; alumina cement; calcium aluminate silicate;

(5) Mineral oil-based antifoaming agents: kerosene, liquid paraffin and the like.

(6) Fat / oil type antifoaming agent: animal / vegetable oil, sesame oil,
Castor oil, their alkylene oxide adducts and the like.

(7) Fatty acid antifoaming agents: oleic acid, stearic acid, alkylene oxide adducts thereof and the like.

(8) Fatty acid ester antifoaming agents: glycerin monoricinoleate, alkenyl succinic acid derivatives, sorbitol monolaurate, sorbitol trioleate, natural wax and the like.

(9) Oxyalkylene-based antifoaming agents: polyoxyalkylenes such as (poly) oxyethylene (poly) oxypropylene adduct; diethylene glycol heptyl ether, polyoxyethylene oleyl ether;
(Poly) oxyalkyl ethers such as polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene-2-ethylhexyl ether, and adducts of oxyethylene oxypropylene added to higher alcohols having 12 to 14 carbon atoms; polyoxypropylene phenyl (Poly) oxyalkylene (alkyl) aryl ethers such as ether and polyoxyethylene nonylphenyl ether; 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2,5-dimethyl-3 -Hexyne-2,5-diol, 3-methyl-1-butyne-3-
Acetylene ethers obtained by addition polymerization of alkylene oxide to acetylene alcohol such as all; (poly) oxyalkylene fatty acid esters such as diethylene glycol oleate, diethylene glycol laurate, ethylene glycol distearate; (poly) oxyethylene sorbitan monolaurin (Poly) oxyalkylene sorbitan fatty acid esters such as acid esters and (poly) oxyethylene sorbitan trioleate; (poly) oxyalkylene alkyls such as sodium polyoxypropylene methyl ether sulfate and sodium polyoxyethylene dodecyl phenol ether sulfate; Aryl) ether sulfates; (poly) oxy such as (poly) oxyethylene stearyl phosphate Ruki alkylene alkyl phosphate esters; polyoxyethylene such as polyoxyethylene lauryl amine (poly) oxyalkylene alkyl amines; polyoxyalkylene amide.

(10) Alcohol antifoaming agents: octyl alcohol, hexadecyl alcohol, acetylene alcohol, glycols and the like.

(11) Amide-based antifoaming agent: acrylate polyamine and the like.

(12) Phosphate ester antifoaming agents: tributyl phosphate, sodium octyl phosphate and the like.

(13) Metallic soap-based antifoaming agents: aluminum stearate, calcium oleate and the like.

(14) Silicone antifoaming agents: dimethyl silicone oil, silicone paste, silicone emulsion, organically modified polysiloxane (polyorganosiloxane such as dimethylpolysiloxane), fluorosilicone oil and the like.

(15) AE agent: resin soap, saturated or unsaturated fatty acid, sodium hydroxystearate, lauryl sulfate, ABS (alkylbenzene sulfonic acid), LAS (linear alkylbenzene sulfonic acid),
Alkane sulfonate, polyoxyethylene alkyl (phenyl) ether, polyoxyethylene alkyl (phenyl) ether sulfate or salt thereof, polyoxyethylene alkyl (phenyl) ether phosphate or salt thereof, protein material, alkenyl sulfosuccinic acid, α- Olefin sulfonates and the like.

(16) Other surfactants: Alkyl diphenyl ether sulfonates which may have an alkyl group or an alkoxy group as a substituent, and two phenyl groups having a sulfone group are ether-bonded; various anionic surfactants Surfactants; various cationic surfactants such as alkylamine acetate and alkyltrimethylammonium chloride; various nonionic surfactants; various amphoteric surfactants.

(17) Waterproofing agent: fatty acid (salt), fatty acid ester, oil and fat, silicon, paraffin, asphalt,
Wax and the like.

(18) Rust inhibitors: nitrites, phosphates, zinc oxide and the like.

(19) Crack reducing agent: polyoxyalkyl ether and the like.

(20) Expansive materials: ettringite, lime, etc.

[0075] The cement composition of the present invention may contain a known cement additive (material) other than those described above, for example, a cement wetting agent,
It may contain a thickener, a coagulant, a strength enhancer, a self-leveling agent, a coloring agent, a fungicide, a pozzolan, a zeolite, and the like. In addition, these cement additives (materials)
It is possible to contain not only species but also two or more species.

In the cement composition of the present invention, particularly preferred embodiments of components other than cement and water include the following 1) to 6).

1) Combination essentially comprising two components of the cement admixture of the present invention and an oxyalkylene antifoaming agent.
The compounding weight ratio of the oxyalkylene-based defoaming agent was 0.01% with respect to the B component in the cement admixture.
A range of from 10 to 10% by weight is preferred.

2) Combination of two essential components of the cement admixture of the present invention and a sulfonic acid-based dispersant having a sulfonic acid group in the molecule. The weight ratio of the cement admixture to the sulfonic acid-based dispersant was 5: 9.
A range of 5 to 95: 5 is preferred, and 10:90 to 90: 1.
A range of 0 is more preferred.

3) A combination comprising two components of the cement admixture of the present invention and lignin sulfonate as essential components. The compounding weight ratio of the cement admixture to the lignin sulfonate is preferably in the range of 5:95 to 95: 5, more preferably in the range of 10:90 to 90:10.

4) Combination of two essential components of the cement admixture and the material separation reducing agent of the present invention. Examples of the material separation reducing agent include various thickeners such as nonionic cellulose ethers, and the average addition of a hydrophobic substituent composed of a hydrocarbon chain having 4 to 30 carbon atoms and an alkylene oxide having 2 to 18 carbon atoms as a partial structure. A compound having a polyoxyalkylene chain added with 2 to 300 moles can be used.
The mixing weight ratio of the cement admixture to the material separation reducing agent was 10:90 to 99.99: 0.01.
Is preferable, and the range of 50:50 to 99.9: 0.1 is more preferable. The cement composition comprising this combination is suitable as a high fluidity concrete, a self-compacting concrete, and a self-leveling material.

5) A combination comprising two components of the cement admixture and the retarder of the present invention as essential components. The mixing weight ratio of the cement admixture to the retarder was 50: 5.
The range of 0-99.9: 0.1 is preferable, and 70: 30-
A range of 99: 1 is more preferred.

6) Combination of two essential components of the cement admixture and the accelerator of the present invention. The weight ratio of the cement admixture to the accelerator was 10: 9.
The range of 0-99.9: 0.1 is preferable, and 20: 80-
A range of 99: 1 is more preferred.

[0083]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the examples. Unless otherwise specified, “parts” in Examples and Comparative Examples indicate “parts by weight”,
“%” Indicates “% by weight”. Further, the weight average molecular weight of the copolymer (B) indicates a weight average molecular weight in terms of polyethylene glycol by gel permeation chromatography (GPC).

The following four kinds were used as the polyalkylene glycol (A) as a raw material.

[Polyalkylene glycol (A)] (A-1): 1-butoxy polyethylene glycol (average number of added moles of ethylene oxide: 25; calculated from the types of terminal groups and oxyalkylene groups and the average number of moles added) The average molecular weight (X) is 1,174.) (A-2): 1-butoxypolyethylene glycol (average number of moles of added ethylene oxide: 75; average calculated from the types of terminal groups and oxyalkylene groups and the average number of moles added) (A-3): methoxypolyethylene glycol (average number of moles added of ethylene oxide: 25; average molecular weight (X) calculated from the types of terminal groups and oxyalkylene groups and the average number of moles added) ) Is 1,132) (A-4): polyethylene glycol (average number of moles of added ethylene oxide: 5) The average molecular weight (X) calculated from the types of terminal groups and oxyalkylene groups and the average number of moles added is 238) The raw material polyalkylene glycol mono (meth) acrylate / (meth) acrylic acid copolymer (B ) Was obtained as follows.

[Production Example 1 (Production of copolymer (B-1))] Ion-exchanged water was placed in a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser.
98 parts were charged, the inside of the reaction vessel was replaced with nitrogen under stirring, and heated to 80 ° C. in a nitrogen atmosphere. Then, 1668 parts of 1-butoxy polyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 25), 332 parts of methacrylic acid, 500 parts of ion-exchanged water, and 16.7 parts of 3-mercaptopropionic acid as a chain transfer agent were mixed. The monomer aqueous solution was dropped into the reaction vessel over 4 hours, and at the same time as the dropping of the monomer aqueous solution, an initiator aqueous solution comprising 23 parts of ammonium persulfate and 207 parts of ion-exchanged water was dropped into the reaction vessel over 5 hours. did. After the completion of the dropwise addition of the aqueous initiator solution, the inside of the reaction vessel was maintained at 80 ° C. for 1 hour to complete the polymerization reaction. Thereafter, the mixture was neutralized with a 30% aqueous sodium hydroxide solution to obtain an aqueous solution of a copolymer (B-1) having a weight average molecular weight of 27,000.
In addition, when the carboxyl group in the copolymer (B-1) was converted into an unneutralized type, the number of milliequivalents of the carboxyl group was 1.93 (meq / g) per 1 g of the copolymer (B-1).
And the average molecular weight (Y) of the polyalkylene glycol chain portion calculated from the structure of the monomer used is 1,173.
Met.

[Production Example 2 (Production of Copolymer (B-2))] Ion-exchanged water 84 was placed in the same reaction vessel as in Production Example 1.
7.7 parts were charged, and the inside of the reaction vessel was replaced with nitrogen under stirring.
Heated to 80 ° C. under a nitrogen atmosphere. Then, 275.6 parts of 1-butoxy polyethylene glycol monomethacrylate (average number of moles of added ethylene oxide: 75),
24.4 parts of methacrylic acid, 200 parts of ion-exchanged water, and 2.3 as a chain transfer agent 2.3 mercaptopropionic acid
Of the monomer aqueous solution was dropped into the reaction vessel over 4 hours, and 3.4 parts of ammonium persulfate and 14 parts of ion-exchanged water were simultaneously added to the monomer aqueous solution.
An initiator aqueous solution consisting of 6.6 parts was dropped into the reaction vessel over 5 hours. After the completion of the dropwise addition of the aqueous initiator solution, the inside of the reaction vessel was maintained at 80 ° C. for 1 hour to complete the polymerization reaction. Thereafter, the mixture was neutralized with a 30% aqueous sodium hydroxide solution to obtain an aqueous solution of a copolymer (B-2) having a weight average molecular weight of 38,000. In addition, when the carboxyl group in the copolymer (B-2) was converted into an unneutralized type, the number of milliequivalents of the carboxyl group was 0.95 per 1 g of the copolymer (B-2).
(Meq / g), and the average molecular weight (Y) of the polyalkylene glycol chain portion calculated from the structure of the used monomer was 3,373.

[Production Example 3 (Production of copolymer (B-3))] Ion-exchanged water 169 was placed in the same reaction vessel as in Production Example 1.
8 parts were charged, the inside of the reaction vessel was replaced with nitrogen under stirring, and heated to 80 ° C. under a nitrogen atmosphere. Then, a monomer aqueous solution obtained by mixing 1668 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of added ethylene oxide: 25), 332 parts of methacrylic acid, 500 parts of ion-exchanged water, and 16.7 parts of 3-mercaptopropionic acid as a chain transfer agent Is dropped into the reaction vessel over 4 hours,
Further, simultaneously with the start of the dropping of the monomer aqueous solution, an initiator aqueous solution comprising 23 parts of ammonium persulfate and 207 parts of ion-exchanged water was dropped into the reaction vessel over 5 hours. After completion of the dropwise addition of the initiator aqueous solution, the inside of the reaction vessel is continuously operated for 8 hours
The temperature was maintained at 0 ° C. to complete the polymerization reaction. Then 30%
Neutralized with aqueous sodium hydroxide solution, weight average molecular weight 24
000 copolymer (B-3) aqueous solution was obtained. In addition, when the carboxyl group in the copolymer (B-3) was converted into an unneutralized type, the number of milliequivalents of the carboxyl group was 1.93 (meq / g) per 1 g of the copolymer (B-3). ,
The average molecular weight (Y) of the polyalkylene glycol chain portion calculated from the structure of the used monomer was 1,131.

(Examples 1 to 10 and Comparative Examples 1 to 8) Ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd.) 4
Using a Hobart type mortar mixer (model number N-50, manufactured by Hobart Co.)
After kneading at a low speed for 0 second, the polyalkylene glycol (A) and the copolymer (B) were mixed in Table 1 or Table 2
, Weighed at a ratio shown in Table 2, diluted with ion-exchanged water to a total of 240 g, and kneaded at a medium speed for 3 minutes to obtain a mortar. In addition, the compounding amount (%) of each component in the table is the weight% of each component (solid content) with respect to cement.
It is.

The obtained mortar was evaluated as follows.

[Fluidity (mortar flow value)] The obtained mortar is filled into a hollow cylinder placed on a horizontal table and having both an inner diameter and a height of 55 mm until it is cut off, and kneading is started.
After a minute, the cylinder was gently lifted vertically, the major axis and minor axis of the mortar spread on the table were measured, and the average value was taken as the mortar flow value (mm). In addition, if the entrained air amount is large, the flow value and the shrinkage amount become apparently large. Therefore, in order to keep the entrained air amount constant, appropriately use an antifoaming agent (oxyalkylene type) and reduce the air amount to 5 ± 1%. It was adjusted. The results are shown in Tables 1 and 2. In addition, it can be said that fluidity is so high that this mortar flow value (mm) is large.

[Shrinkage Reduction (Length Change)] First, JIS
A specimen (4 × 4 × 16 cm) was prepared according to -A-1129. Apply silicone grease to the mold in advance to stop the water and make it easy to remove the mold.
Gauge plugs were attached to both ends of the specimen. And after pouring the obtained mortar into this mold, the temperature 20
Initial curing was carried out in a thermo-hygrostat (manufactured by Tabai Espec, PL-2G) set at a temperature of 60 ° C. and a humidity of 60%. After 4 days, the mold was released, and the silicone grease adhering to the surface of the test piece was washed with water using a sponge scourer. continue,
The test specimen was cured in still water at 20 ° C. for 7 days.

After wiping the water on the surface of the specimen cured in still water for 7 days with a paper towel, immediately measure the length using a dial gauge (manufactured by West Japan Testing Machine Co., Ltd.) according to JIS-A-1129. , Based on the length at this time. Thereafter, the test specimen was stored in a thermo-hygrostat set at a temperature of 20 ° C. and a humidity of 60%, and measured again 28 days after the end of the underwater curing, to change the length, that is, the reference date (the end of the underwater curing). ) Was calculated by subtracting the length of the test sample after 28 days from the length of the test sample in ()). (For example, when the length change is 247 μm)
In the case of m, it indicates that the specimen contracted by 247 μm from the length of the specimen on the reference day. The results are shown in Tables 1 and 2. In addition, length change (μm)
The smaller the value, the greater the effect of reducing the amount of shrinkage,
It can be said that there is little cracking of the structure due to shrinkage.

[0094]

[Table 1]

[0095]

[Table 2]

From Table 2, Comparative Examples 1, 3, 5 and 6 show that
Since the blending ratio of the component A was too small as compared with the range of the present invention, it was found that although the fluidity was high, a sufficient shrinkage reduction effect could not be obtained. On the other hand, in Comparative Examples 2, 4 and 7, it was found that although the mixing ratio of the component A was too large, the shrinkage reduction effect was large, but sufficient fluidity could not be obtained. In Comparative Example 8, the average molecular weight of component A (X)
Is too small compared to the average molecular weight (Y) of the polyalkylene glycol chain portion of the component B, so that the fluidity is high,
It was found that a sufficient shrinkage reduction effect could not be obtained.

On the other hand, from Table 1, it was found that all of the examples which are the cement compositions of the present invention exhibit excellent shrinkage reduction and fluidity.

[0098]

According to the present invention, an excellent effect of preventing cracking can be exhibited with a small amount of addition, and at the same time, good fluidity can be exhibited.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 28/02 C04B 28/02 28/14 28/14 // C04B 103: 32 103: 32 111: 34 111 : 34 (72) Inventor Ken Hirata 5-8 Nishiburi-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. F-term (reference) 4G012 PA04 PB31 PB32 PB33 PB36

Claims (3)

[Claims] 1. A cement admixture comprising a polyalkylene glycol (A) and a polyalkylene glycol mono (meth) acrylate / unsaturated carboxylic acid copolymer (B), wherein the polyalkylene glycol (A) Has an average molecular weight (X) of 400 to 10000, and the average molecular weight (X) of the polyalkylene glycol (A) and the polyalkylene glycol mono (meth) acrylate / unsaturated carboxylic acid copolymer (B) Average molecular weight (Y) of the polyalkylene glycol chain portion of the formula (1) satisfies the following formula (1): 0.9 <(X / Y) <1.1 (1) The polyalkylene glycol (A) and the polyalkylene The weight ratio of glycol mono (meth) acrylate / unsaturated carboxylic acid copolymer (B) is (A) / (B) =
A cement admixture, which is 0.02 to 0.3. 2. The polyalkylene glycol mono (meth) acrylate / unsaturated carboxylic acid copolymer (B)
The carboxyl group milliequivalent number when all the carboxyl groups in the above were converted to the non-neutralized type was 0.25 to 5.00 m
The cement admixture according to claim 1, which is eq / g. 3. A cement composition comprising at least the cement admixture according to claim 1 or 2, water and cement.