JP2001019514A - Cement admixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement admixture capable of giving excellent initial dispersibility and slump-holding ability by formulating a polyalkylene glycol mono(meth)acrylate-based polymer and a polyalkylene glycol monoalkenyl ether- based polymer. SOLUTION: This cement admixture is obtained by formulating (A) a polymer having respective structural units of formula I (R1 and R2 are each H or methyl; R3O is a 2-18C oxyalkylene; m is 15-100; R4 is H or a 1-5C alkyl) and formula II (R5 and R6 are each the same as R1; X is H, a univalent metal, bivalent metal, ammonium group or the like) as the essential constituents and also containing 1.0-1.3 meq/g of carboxyl group in terms of unneutralized form and (B) a polymer having respective structural units of formula III (R7O is a 2-18C oxyalkylene; n is 20-70) and formula IV (R8 and R9 are each H or methyl; M1 and M2 are each the same as X in the formula II) as the essential constituents and also containing 0.8-3.5 meq/g of carboxyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture, and more particularly to a blend of a polymer (A) having a specific range of carboxyl groups and a polymer (B) having a specific range of carboxyl groups. And a cement admixture having excellent initial dispersibility and slump retention.

[0002]

2. Description of the Related Art Cement paste in which water is added to cement, mortar in which sand is mixed with fine aggregate, and concrete in which pebbles are mixed are used for various purposes such as structural materials, foundations and fire-resistant walls. The amount is also large. However, mortar and concrete exhibit strength through agglomeration and hardening due to a hydration reaction between cement and water, so that workability generally decreases with time after the addition of water. Various cement admixtures have been developed to ensure such cement dispersibility.

For example, Japanese Patent Publication No. 59-18338 discloses a cement dispersant obtained by copolymerizing a polyalkylene glycol mono (meth) acrylate monomer and a (meth) acrylate monomer. Have been. The cement dispersant disclosed in this publication has a nonionic hydrophilic group called ethylene oxide adduct and an anionic carboxyl group in one molecule, and the hydrophilicity and steric hindrance of the former disperse the latter into cement particles. To suppress the adsorption of
It is said that it has little setting delay effect and exhibits excellent dispersion performance.

Japanese Patent Application Laid-Open No. 4-175254 discloses a cement dispersant containing two kinds of polymers. The first component is a copolymer of maleic anhydride and an allyl alkyl ether of a polyalkylene glycol. Polymer
Further, it is a polyether compound monoesterified with an alkyl polyalkylene glycol, and the second component is a salt of a polycarboxylic acid which is a polymer such as (meth) acrylic acid. In the cement dispersant described in the publication, the polycarboxylate salt of the second component is blended, so that it is preferentially adsorbed on the cement particles to disperse the cement particles in water, and then the cement dispersant contained in the first component is used. Polyether compounds with a lower adsorption rate to cement adsorb to cement,
It is said that cement dispersibility can be secured over a long period of time.

Japanese Patent Application Laid-Open No. 5-345647 also discloses a cement dispersant containing two kinds of polymers, wherein the first component has an addition mole number of maleic anhydride and oxyalkylene group of 100 or more. It is a copolymer with alkenyl ether (a), and the second component is a polycarboxylic acid cement dispersant (b). In this publication, the component (b) acts to enhance the cement dispersibility at an early stage and the polyoxyalkylene extending from the copolymer adsorbed on the cement particles by the component (a) in which the number of moles of added oxyalkylene group is increased to 100 or more. It states that a hydration layer is formed around the group, and the steric hindrance accompanying the hydration layer keeps the dispersibility of the cement particles for a long time, and the longer the polyether chain in the component (a), the more the slump tends to increase. I do.

Further, Japanese Patent Application Laid-Open No. Hei 7-267705 discloses a cement dispersant containing three kinds of polymers. The first component comprises a polyalkylene glycol mono (meth) acrylate compound and a (meth) acrylate compound. ) A copolymer with an acrylic acid compound (a), the second component is a copolymer of a polyalkylene glycol mono (meth) allyl ether compound and maleic anhydride (b), and the third component is a polyalkylene glycol mono compound. It is a copolymer (c) of a (meth) allyl ether compound and a maleic acid ester of a polyalkylene glycol compound. According to the publication, the component (a) alone increases the fluidity of the cement at the initial stage, but has poor slump retention performance and a high viscosity of the cement composition.
With the component (b) alone, it takes time to increase the initial fluidity, and even when the initial amount of fluidity is increased by increasing the amount of addition, the cement composition is separated over time. It further states that an effect that cannot be obtained by itself alone can be obtained by blending three components at a specific ratio because of poor cement dispersibility. That is, the reason why the mechanism of action of each component on cement is different is due to the molecular structure of each component, and the effect of increasing the initial fluidity is different because the polymer (a) having a (meth) acrylic acid functional group Component) is presumed to have a higher adsorption rate to cement particles than the polymer having maleic acid functional groups (components b and c). Furthermore, it is described that a substance having a high adsorption rate has a poor ability to retain fluidity thereafter.

[0007]

As described above, as a cement admixture, a polyalkylene glycol (meth) acrylate compound has conventionally been blended in order to ensure initial dispersibility, and to ensure subsequent dispersibility. In addition, a polyalkylene glycol mono (meth) allyl ether-based compound is compounded, but the dispersibility of the cement composition over a long period of time and the slump retention are not sufficient.

[0008]

The above object is achieved by the following means (1).

(1) A polymer containing a structural unit (I) represented by the following general formula (1) and a structural unit (II) represented by the following general formula (2) as essential structural units: A) and a polymer (B) containing, as essential structural units, a structural unit (III) represented by the following general formula (3) and a structural unit (IV) represented by the following general formula (4) ) As an essential component, and the number of carboxyl groups in the polymer (A) in terms of an unneutralized type is 1.0 g per 1 g of the polymer (meq / g).
And the number of milliequivalents (meq / g) of carboxyl groups per 1 g of the polymer obtained by converting the carboxyl groups in the polymer (B) into an unneutralized form is from 0.8 to 3.0. A cement admixture characterized by being in the range of 0.5.

General formula (1)

[0011]

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(Wherein, R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and R ³ O represents one or a mixture of two or more oxyalkylene groups having 2 to 18 carbon atoms.) In the case where two or more kinds are used, they may be added in blocks or in random form, and m is the average number of moles of the oxyalkylene group added, and
Represents an integer of 00, and R ⁴ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. ), General formula (2)

[0013]

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Wherein R ⁵ and R ⁶ each independently represent a hydrogen atom or a methyl group, and X represents hydrogen, a monovalent metal, a divalent metal, an ammonium group or an organic amine group. (3)

[0015]

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(Wherein R ⁷ O represents 2 to 18 carbon atoms)
Represents one or a mixture of two or more oxyalkylene groups, and in the case of two or more, they may be added in a block form or in a random form, and n is the average number of moles of the oxyalkylene group added. And represents an integer of 20 to 70. ), General formula (4)

[0017]

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(Wherein, R ⁸ and R ⁹ each independently represent a hydrogen atom or a methyl group, and M ₁ and M ₂ each independently represent hydrogen, a monovalent metal, a divalent metal, an ammonium group or an organic amine group. Where COOM ₁ and COOM ₂ are bonded to form an acid anhydride group (—CO—O—C
O-). In this case M ₁ and M ₂ does not exist. ).

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Conventional cement dispersants are prepared by adding a carboxyl group and an oxyalkylene group to a polyalkylene glycol (meth) acrylate compound contained in a compound and a polyalkylene glycol mono (meth) allyl ether compound. Focusing on the number of moles, the initial dispersibility was ensured by the quick adsorption of the carboxyl group to the cement particles, and the subsequent slump retention was ensured by the steric hindrance of the oxyalkylene group.

However, conventional polyalkylene glycol mono (meth) allyl ether compounds cannot provide sufficient dispersibility even when the number of moles of oxyalkylene groups added is increased, and therefore polyalkylene glycol mono (meth) allyl ether compounds are not used. Even when blended with a (meth) acrylate-based compound, it was not possible to achieve both a sufficient initial dispersibility and a sufficient slump retention. Accordingly, the present inventors have developed a specific polyalkylene glycol alkenyl ether compound having a structure different from that of a conventionally used polyalkylene glycol mono (meth) allyl ether compound and a polyalkylene glycol mono (meth) acrylate compound. When the compounds combined with the compound were examined in detail, when a compound in which the content of the carboxyl group and the number of moles of the polyalkylene glycol chain length of these compounds were in a specific range were used in combination, the compound was superior to conventional products. The inventors have found that initial dispersibility and slump retention can be obtained, and have completed the present invention. Hereinafter, the present invention will be described in detail.

The cement admixture according to the present invention contains the polymer (A) and the polymer (B) as essential components,
Two types of polymer (A) and polymer (B) synthesized separately
Can be obtained by mixing Each of these will be described.

The polymer (A) contains the structural unit (I) represented by the general formula (1) and the structural unit (II) represented by the general formula (2) as essential structural units. In addition, the number of milliequivalents of carboxyl groups (meq / g) per 1 g of the polymer (meq / g) in which the carboxyl groups in the polymer (A) are converted into an unneutralized type is 1.0 to 3.0, more preferably 1 to 3.0. 0.2 to 2.5. When the number of milliequivalents of the carboxyl group is more than 3.0, the slump retention decreases, and when it is less than 1.0, the initial dispersibility decreases, which is not preferable.

The polymer (A) is a polymer containing the structural units (I) and (II) as essential structural units, but contains a carboxyl group represented by the above general formula (4). It may include another structural unit (IV), and may further include another structural unit (V) described later. Therefore, the number of milliequivalents of the carboxyl group contained in the polymer (A) is not limited to the case where it is derived from the structural unit (II).

The content of each structural unit constituting the polymer (A) is determined by converting the number of carboxyl groups in the polymer (A) into an unneutralized type by the number of milliequivalents of carboxyl groups per 1 g of the polymer (meq / G) is not particularly limited as long as it is in the range of 1.0 to 3.0. However, the content of the structural unit (I) is suitably 10 to 94% by weight of the whole polymer (A), preferably 20 to 94% by weight, more preferably 30 to 93% by weight, and 50 to 92% by weight. % Is particularly preferred.
If the content is less than 10% by weight, the content of the oxyalkylene group is small, so that the slump retention may be poor. On the other hand, if it exceeds 94% by weight, the amount of carboxyl groups cannot be secured.

On the other hand, as for the content of the structural unit (II), it is necessary to secure the milliequivalent number (meq / g) of the carboxyl group in the polymer (A) in the above range, and therefore, the polymer has another carboxyl group. Structural unit (for example, structural unit (I
Although it depends on the content of V)) and the type of X in the general formula (2), 1% by weight or more of the entire polymer (A) is appropriate, preferably 6 to 90% by weight, and 6 to 80% by weight.
% By weight, more preferably from 7 to 70% by weight, and particularly preferably from 8 to 50% by weight. For example, in the general formula (2), one of the structural units (II) in which one of R ⁵ and R ⁶ is a methyl group, the other is a hydrogen atom, and X is sodium has a carboxyl group. When used as a unit, the number of milliequivalents of the carboxyl group in the above range in the polymer (A) (meq /
In order to secure g), the content of the structural unit (II) is 1
It needs to be in the range of 0.6 to 30.4% by weight.

Further, as described above, the content of the structural unit (IV) also needs to secure the milliequivalent number (meq / g) of the carboxyl group in the above-mentioned range in the polymer (A). (For example, the structural unit (I
Although it depends on the content of I)) and the types of M ₁ and M ₂ in the general formula (4), 0 to 50% by weight of the entire polymer (A) is preferable, 0 to 30% by weight is more preferable, 0-20% by weight is particularly preferred.

The content of the structural unit (V) is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 0 to 50% by weight of the whole polymer (A),
-30% by weight is more preferred.

The polymer (A) contains the structural units (I) and (II) as essential components in order to secure a carboxyl group and an oxyalkylene group as described above. Other structural units containing a group (I
V) and other structural units (V).

The polymer (A) includes, for example, a monomer (for example, a monomer (a) described below) that provides the structural unit (I) and a monomer (for example, a monomer (for example) described below) that provides the structural unit (II). It can be produced by copolymerizing a monomer component containing the monomer (b)) as an essential component. The monomer component may further include a monomer (for example, a monomer (d) described below) that provides the structural unit (IV), or a monomer (for example, described later) that provides the structural unit (V). (E)). When using the method of producing the polymer (A) by copolymerization of each of the above monomer components, the mixing ratio of each of the monomer components is such that the monomer (a) and the monomer (b) are essential components. The carboxyl group in the polymer (A) is converted into an unneutralized type and the number of milliequivalents of carboxyl groups per 1 g of the polymer (meq / g) is in the range of 1.0 to 3.0; It is not particularly limited as long as the ratio is preferably in the range of 1.2 to 2.5, but the following compounding ratio is preferably based on 100% by weight of the total of each monomer component used.

That is, the mixing ratio of the monomer (a) is suitably from 10 to 94% by weight of the total amount of the monomer components, and from 20 to 94% by weight.
% By weight, preferably 30 to 93% by weight,
50-92% by weight is particularly preferred. On the other hand, the mixing ratio of the monomer (b) is such that the number of milliequivalents of carboxyl groups per 1 g of the polymer (meq / g) obtained by converting the carboxyl groups in the polymer (A) into an unneutralized type is 1. Since it is necessary to set so as to be in the range of 0 to 3.0, the mixing ratio of other monomer components having a carboxyl group (for example, monomer (d)) and the type of the counter ion of the carboxyl group 1% by weight or more of the total amount of the monomer components is appropriate, preferably 6 to 90% by weight, more preferably 6 to 80% by weight, still more preferably 7 to 70% by weight, and more preferably 8 to 50%.
% By weight is particularly preferred. Also, as described above, the compounding ratio of the monomer (d) needs to secure the milliequivalent number (meq / g) of the carboxyl group in the monomer (A) within the above range. Having monomers (for example,
Although it depends on the mixing ratio of the monomer (b)) and the type of the counter ion of the carboxyl group, 0 to 0 of the total monomer component amount
It is preferably 50% by weight, more preferably 0 to 30% by weight, particularly preferably 0 to 20% by weight. The mixing ratio of the monomer (e) is not particularly limited as long as the effect of the present invention is not impaired.
0% by weight is preferable, and 0 to 30% by weight is more preferable.

In the structural unit (I) represented by the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and R ³ O has 2 to 1 carbon atoms.
8 represents one or a mixture of two or more oxyalkylene groups, and in the case of two or more, they may be added in block form or in random form, and m is an average addition mole of oxyalkylene group. It is a number and represents an integer of 15 to 100. m is suitably an integer of 15 to 100,
Since the initial dispersibility decreases as the average number of moles decreases, the slump retention decreases as the average number of moles increases.
An integer from 0 to 90 is more preferred.

The number of carbon atoms of the oxyalkylene group R ³ O is suitably in the range of 2 to 18,
Is preferably in the range of from 8 to 8, more preferably in the range of from 2 to 4.
Further, ethylene oxide, propylene oxide, butylene oxide, any two or more alkylene oxide adducts selected from styrene oxide and the like,
Any of random addition, block addition, and alternate addition can be used.

Further, in the general formula (1), R ⁴ may be a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, but if it is a hydrogen atom, a crosslinked structure is easily formed during polymerization. Since a polymerization reaction becomes difficult, an alkyl group having 1 to 5 carbon atoms is preferable.

The monomer (a) which provides the structural unit (I) used in the present invention includes (meth) acrylic acid or crotonic acid, an alkylene oxide adduct having 2 to 18 carbon atoms; methanol, ethanol, 2-propanol,
Esters of alkoxypolyalkylene glycols obtained by adding alkylene oxides having 2 to 18 carbon atoms to alkyl alcohols having 1 to 5 carbon atoms such as 1-butanol and (meth) acrylic acid or crotonic acid Compounds; and the like.

Specific examples of the monomer (a) include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene (poly) propylene glycol mono (meth) acrylate, and polyethylene (poly) butylene glycol mono (meth) acrylate. C2-C18 alkylene oxide adducts to (meth) acrylic acid such as (meth) acrylate; methoxypolyethylene glycol mono (meth) acrylate, polyethylene (poly) butylene 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 Rumono (meth) acrylate, 2-butoxy polyethylene glycol mono (meth)
Various alkoxy polyethylene glycol mono (meth) acrylates such as acrylate; methoxy polypropylene glycol mono (meth) acrylate, ethoxy polypropylene glycol mono (meth) acrylate, 1-
Various alkoxy polypropylene glycol mono (meth) such as propoxy polypropylene glycol mono (meth) acrylate, 2-propoxy polypropylene glycol mono (meth) acrylate, 1-butoxy polypropylene glycol mono (meth) acrylate, and 2-butoxy polypropylene glycol mono (meth) acrylate )
Acrylates: methoxy polyethylene (poly) propylene glycol mono (meth) acrylate, methoxy polyethylene (poly) butylene glycol mono (meth) acrylate, ethoxy polyethylene (poly) propylene glycol mono (meth) acrylate, ethoxy polyethylene (poly) butylene glycol mono (Meth) acrylate, 1-propoxy polyethylene (poly) propylene glycol mono (meth) acrylate, 1-propoxy polyethylene (poly) butylene glycol mono (meth) acrylate, 2-propoxy polyethylene (poly) propylene glycol mono (meth) acrylate,
Two or more kinds of 2-propoxy polyethylene (poly) butylene glycol mono (meth) acrylate, 1-butoxy polyethylene (poly) propylene glycol mono (meth) acrylate, 1-butoxy polyethylene (poly) butylene glycol mono (meth) acrylate, etc. Various alkoxypolyalkylene glycol mono (meth) acrylates, such as an esterified product of an alcohol to which an alkylene oxide has been added and (meth) acrylic acid; and the like.

In the present invention, as the structural unit (I) or the monomer (a), one of these may be used alone, or two or more may be used in combination. In any case, it is preferable that the oxyalkylene group contains an oxyethylene group as an essential component. Thereby, the balance between hydrophilicity and hydrophobicity is ensured.

The monomer (b) for providing the structural unit (II) used in the present invention is an unsaturated monocarboxylic acid monomer, and specific examples thereof include acrylic acid, methacrylic acid, crotonic acid and Examples thereof include metal salts, ammonium salts, and amine salts, with (meth) acrylic acid and salts thereof being preferred. The monomer (b) may be used alone or in combination of two or more.

In the present invention, "the number of milliequivalents of carboxyl groups per 1 g of the polymer (meq / g) in which the carboxyl groups in the polymer (A) are converted into an unneutralized type" refers to the polymer (A) ) Takes into account the case where a salt is formed, and the calculation methods for the case of an acid and the case of forming a salt are described below.
In the following calculation, only the carboxyl group derived from the structural unit (II) is exemplified. However, when the structural unit (IV) is contained, this must also be included in the number of milliequivalents of the carboxyl group.

(Calculation Example 1): Acrylic acid was used as monomer (b), and monomer (a) / monomer (b) = 90/10
(% By weight), the molecular weight of acrylic acid was 72, so that the carboxyl groups derived from the monomer (b) were converted to the non-neutralized type, and the carboxyl groups per 1 g of the polymer were converted. Milliequivalent number (meq / g) = (0.1 / 7
2) × 1000 = 1.39.

(Calculation Example 2): Monomer (a) / monomer (b) using sodium methacrylate as monomer (b)
= 80/20 (% by weight), the sodium methacrylate has a molecular weight of 108 and the methacrylic acid has a molecular weight of 86, so that the carboxyl group derived from the monomer (b) is not neutralized. Milliequivalent number of carboxyl groups per 1 g of the polymer converted into a mold (meq / g) = (0.2
× 86/108) / (0.8 + 0.2 × 86/108)
/86×1000=1.93. Note that the same applies to the calculation example when methacrylic acid is used at the time of polymerization and the carboxyl group derived from methacrylic acid is completely neutralized with sodium hydroxide after the polymerization.

The carboxyl groups in the polymer (A) were converted to the non-neutralized type, and the number of milliequivalents of carboxyl groups per 1 g of the polymer (meq / g) was based on the above monomers. By calculating the acid value of the polymer in consideration of the type of the counter ion species of the carboxyl group of the polymer (for example, X in the general formula (2)) in addition to the calculation by the above calculation method. Can be calculated.

The monomer (e) giving the structural unit (V) capable of constituting the polymer (A) is a monomer copolymerizable with other monomer components. Specific examples of the monomer (e) include half esters and diesters of unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid with alcohols having 1 to 30 carbon atoms; Amides and diamides of amines having 1 to 30 carbon atoms; alkyl (poly) alkylene glycols obtained by adding 1 to 500 moles of alkylene oxides having 2 to 18 carbon atoms to the alcohol or amine, and the unsaturated dicarboxylic acids Half-esters and diesters of the above; unsaturated dicarboxylic acids and glycols having 2 to 18 carbon atoms or the number of moles of addition of these glycols 2
Half-esters and diesters with polyalkylene glycols having a molecular weight of up to 500; maleamic acid and glycols having 2 to 18 carbon atoms or the number of moles of addition of these glycols being 2
A half amide with a polyalkylene glycol of ~ 500; triethylene glycol di (meth) acrylate;
(Poly) ethylene glycol di (meth) acrylate,
Polypropylene glycol di (meth) acrylate,
(Poly) alkylene glycol di (meth) acrylates such as (poly) ethylene glycol (poly) propylene glycol di (meth) acrylate; hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane di Bifunctional (meth) acrylates such as (meth) acrylate;
(Poly) alkylene glycol dimaleates such as triethylene glycol dimaleate and polyethylene glycol dimaleate; vinyl sulfonate, (meth) allyl sulfonate, 2- (meth) acryloxyethyl sulfonate, 3- (meth) acryloxypropyl sulfonate;
3- (meth) acryloxy-2-hydroxypropylsulfonate, 3- (meth) acryloxy-2-hydroxypropylsulfophenyl ether, 3- (meth) acryloxy-2-hydroxypropyloxysulfobenzoate, 4- (meth) acryloxy Unsaturated sulfonic acids such as butylsulfonate, (meth) acrylamidomethylsulfonic acid, (meth) acrylamidoethylsulfonic acid, 2-methylpropanesulfonic acid (meth) acrylamide and styrenesulfonic acid, and monovalent metal salts and divalent salts thereof Metal salts, ammonium salts and organic amine salts; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, glycidyl (meth) acrylate, methyl crotonate, ethyl crotonate, propyl acrylate Esters of unsaturated monocarboxylic acids such as tonates and alcohols having 1 to 30 carbon atoms; amides of unsaturated monocarboxylic acids and amines having 1 to 30 carbon atoms such as methyl (meth) acrylamide; styrene 1,4-vinyl aromatics such as α-methylstyrene, vinyltoluene and p-methylstyrene;
Alkanediol mono (meth) acrylates such as butanediol mono (meth) acrylate, 1,5-pentanediol mono (meth) acrylate, and 1,6-hexanediol mono (meth) acrylate; butadiene, isoprene, 2-methyl- Dienes such as 1,3-butadiene and 2-chloro-1,3-butadiene; (meth) acrylamide, (meth) acrylalkylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide and the like Unsaturated amides such as (meth) acrylonitrile and α-chloroacrylonitrile; unsaturated esters such as vinyl acetate and vinyl propionate; aminoethyl (meth) acrylate and methylamino (meth) acrylate Ethyl, dimethylamino (meth) acrylate Unsaturated amines such as dimethylaminopropyl (meth) acrylate, dibutylaminoethyl (meth) acrylate, and vinylpyridine; divinyl aromatics such as divinylbenzene; cyanurates such as triallyl cyanurate; (meth) Allyls such as allyl alcohol and glycidyl (meth) allyl ether; unsaturated amino compounds such as dimethylaminoethyl (meth) acrylate; methoxy polyethylene glycol monovinyl ether, polyethylene glycol monovinyl ether;
Vinyl ethers or allyl ethers such as methoxypolyethylene glycol mono (meth) allyl ether and polyethylene glycol mono (meth) allyl ether; polydimethylsiloxane propylaminomaleamic acid, polydimethylsiloxane aminopropyleneaminomaleamic acid, polydimethylsiloxane-bis -(Propylaminomaleamic acid), polydimethylsiloxane-bis- (dipropyleneaminomaleamic acid), polydimethylsiloxane- (1-propyl-3-
Acrylate), polydimethylsiloxane- (1-propyl-3-methacrylate), polydimethylsiloxane-bis- (1-propyl-3-acrylate), polydimethylsiloxane-bis- (1-propyl-3-methacrylate) and the like. Siloxane derivatives; and the like, and one or more of these can be used.

The polymer (B) contains the structural unit (III) represented by the general formula (3) and the structural unit (IV) represented by the general formula (4) as essential structural units. In addition, the carboxyl group in the polymer (B) is converted to an unneutralized form, and the number of milliequivalent carboxyl groups per 1 g of the polymer (meq / g) is 0.8 to 3.5, preferably 0. It is a polymer having a range of 0.9 to 3.0, more preferably 1.0 to 2.5. In either case where the number of milliequivalents of the carboxyl group is larger than 3.5 or smaller than 0.8, the dispersibility decreases, which is not preferable.

The polymer (B) contains a structural unit (III) in order to secure a carboxyl group and an oxyalkylene group.
And the structural unit (IV) as essential components, but may include the structural unit (II) and another structural unit (V). Accordingly, the number of milliequivalents of the carboxyl group contained in the polymer (B) is not limited to the case where the number is derived from the structural unit (IV).

The content of each structural unit constituting the polymer (B) is determined by converting the number of carboxyl groups in the polymer (B) into an unneutralized type by the number of milliequivalents of carboxyl groups per gram of the polymer (meq / G) is not particularly limited as long as it is in the range of 0.8 to 3.5. However, the content of the structural unit (III) is suitably from 10 to 96% by weight of the whole polymer (B), preferably from 20 to 96% by weight, and more preferably from 30 to 95% by weight.
Is more preferable, and 50 to 95% by weight is particularly preferable. If the content is less than 10% by weight, the content of the oxyalkylene group is small, so that the slump retention may be poor. On the other hand, if it exceeds 96% by weight, the amount of carboxyl groups cannot be secured.

On the other hand, as for the content of the structural unit (IV), it is necessary to secure the milliequivalent number (meq / g) of the carboxyl group in the above range in the polymer (B), Although it differs depending on the content of the unit (for example, the structural unit (II)) and the type of M ₁ and M _{2 in} the above formula (4), 1% by weight or more of the whole polymer (B) is appropriate, and % By weight, preferably 4 to 80% by weight, more preferably 5 to 70% by weight,
Particularly preferred is 5 to 50% by weight. For example, in the general formula (4), a structural unit (I) in which both R ⁸ and R ⁹ are hydrogen atoms and M ₁ and M ₂ are sodium
V) When only one type is used as the structural unit having a carboxyl group, in order to secure the milliequivalent number (meq / g) of the carbosyl group in the above range in the polymer (B),
The content of the structural unit (IV) is 6.3 to 26.0% by weight.
Must be within the range.

As described above, the content of the structural unit (II) also needs to ensure the milliequivalent number (meq / g) of the carboxyl group in the polymer (B) within the above range, (For example, the structural unit (I
Although it depends on the content of V)) and the type of X in the general formula (2), it is preferably 0 to 50% by weight, more preferably 0 to 30% by weight, and more preferably 0 to 30% by weight of the whole polymer (B).
20% by weight is particularly preferred.

The content of the structural unit (V) is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 0 to 50% by weight of the whole polymer (B),
-30% by weight is more preferred.

The polymer (B) includes, for example, a structural unit (II)
A monomer containing, as essential components, a monomer (for example, a monomer (c) described below) that provides I) and a monomer (for example, a monomer (d) described below) that provides a structural unit (IV) It can be produced by polymerizing the components. The monomer component may further include a monomer that provides the structural unit (II) (for example, the above-described monomer (b)), or a monomer that provides the structural unit (V) ( For example, the monomer (e) described above)
May be further included. When using the method of producing the polymer (B) by copolymerization of each of the above monomer components,
The mixing ratio of each monomer component is such that the monomer (c) and the monomer (d) are contained as essential components, and the carboxyl group in the polymer (B) is converted to an unneutralized type. The number of milliequivalents of carboxyl groups per 1 g of coalescence (meq / g)
0.8 to 3.5, preferably 0.9 to 3.0,
More preferably, the ratio is not particularly limited as long as the ratio is in the range of 1.0 to 2.5, but the total of each monomer component used is 1
The following compounding ratio is preferably based on 00% by weight.

That is, the mixing ratio of the monomer (c) is suitably from 10 to 96% by weight of the total amount of the monomer components, and from 20 to 96% by weight.
% By weight, preferably 30 to 95% by weight,
50-95% by weight is particularly preferred. On the other hand, the mixing ratio of the monomer (d) is such that the number of carboxyl groups in the polymer (B) in terms of unneutralized carboxyl groups per milligram of the polymer (meq / g) is 1. Since it is necessary to set the ratio within a range of 0 to 3.0, the compounding ratio of other monomer components having a carboxyl group (for example, monomer (b)) and the type of the counter ion of the carboxyl group 1% by weight or more of the total amount of the monomer components is appropriate, preferably 4 to 90% by weight, more preferably 4 to 80% by weight, still more preferably 5 to 70% by weight, and more preferably 5 to 50% by weight.
% By weight is particularly preferred. Also, as described above, the compounding ratio of the monomer (b) needs to secure the milliequivalent number (meq / g) of the carboxyl group in the monomer (B) within the above range. Having monomers (for example,
Although it varies depending on the blending ratio of the monomer (d)) and the type of the counter ion of the carboxyl group, 0 to 0
It is preferably 50% by weight, more preferably 0 to 30% by weight, particularly preferably 0 to 20% by weight. The mixing ratio of the monomer (e) is not particularly limited as long as the effect of the present invention is not impaired.
0% by weight is preferable, and 0 to 30% by weight is more preferable.

The structural unit (II) represented by the general formula (3)
In I), R ⁷ O represents one or a mixture of two or more oxyalkylene groups having 2 to 18 carbon atoms.
In the case of more than one kind, they may be added in block form or in random form, and n is the average number of moles of oxyalkylene group added and represents an integer of 20 to 70. n
Is suitably an integer of 20 to 70, but the dispersibility decreases as the average addition mole number decreases, and the polymerizability decreases as the average addition mole number increases.
Is preferable, and an integer of 40 to 60 is more preferable.

The number of carbon atoms of the oxyalkylene group R ⁷ O is suitably in the range of 2 to 18,
Is preferably in the range of from 8 to 8, more preferably in the range of from 2 to 4.
Further, ethylene oxide, propylene oxide, butylene oxide, any two or more alkylene oxide adducts selected from styrene oxide and the like,
Any of random addition, block addition, and alternate addition can be used.

The monomer (c) giving such a structural unit (III) can be obtained by adding an alkylene oxide having 2 to 18 carbon atoms to 3-methyl-3-buten-1-ol. Polyalkylene glycol 3
-Methyl-3-butenyl ether.

Specific examples of the monomer (c) include polyethylene glycol 3-methyl-3-butenyl ether, polypropylene glycol 3-methyl-3-butenyl ether, and polyethylene (poly) propylene glycol 3-
Methyl-3-butenyl ether, polyethylene (poly)
Butylene glycol 3-methyl-3-butenyl ether; and the like. In the present invention, the structural unit (III)
Alternatively, as the monomer (c), one of these can be used alone, or two or more can be used in combination. In addition,
In any case, it is preferable to include an oxyethylene group as an essential component in the oxyalkylene group in order to secure a balance between hydrophilicity and hydrophobicity. Although the reason is not clear in the present invention, in particular, polyalkylene glycol 3
By using -methyl 3-butenyl ether, an extremely excellent synergistic effect described later can be obtained.

The monomer (d) that gives the structural unit (IV) used in the present invention is an unsaturated dicarboxylic acid monomer, and specific examples thereof include maleic acid, citraconic acid,
Fumaric acid, metal salts, ammonium salts, amine salts and the like thereof, and examples of the anhydrides thereof include maleic anhydride and citraconic anhydride. Among them, maleic acid and salts thereof, or maleic anhydride is preferred. In addition, two or more of these monomers (d) may be used in combination.

In the present invention, "the number of milliequivalents of carboxyl groups per gram of the polymer (B) converted to an unneutralized type (meq / g)" refers to the polymer (B). ) Takes into account the case of forming a salt, and the calculation method for an acid is given below. In the following calculation, only the carboxyl group derived from the structural unit (IV) is exemplified, but when the structural unit (II) is contained, this must also be included in the number of milliequivalents of the carboxyl group.

(Calculation example) When maleic acid is used as the monomer (d) and copolymerized at a composition ratio of monomer (c) / monomer (d) = 90/10 (% by weight), Since the acid has a molecular weight of 116 and maleic acid is a divalent acid having two carboxyl groups in one molecule, the carboxyl group derived from the monomer (d) is converted into an unneutralized form. The number of milliequivalents of carboxyl groups per 1 g of the polymer (me
q / g) = 0.1 / (0.9 + 0.1) / (116 /
2) × 1000 = 1.72.

Incidentally, the number of milliequivalents of carboxyl groups per 1 g of the polymer (meq / g) obtained by converting the carboxyl groups in the polymer (B) into an unneutralized type is based on the above-mentioned monomers. In addition to the above calculation, the acid value of the polymer is determined in consideration of the type of the counter ion species of the carboxyl group of the polymer (for example, M ₁ and M ₂ in the general formula (4)). It can be calculated by measuring.

The monomer (e) which gives the structural unit (V) in the polymer (B) is a monomer copolymerizable with other monomer components, and specific examples of the monomer (e) Examples include the above-mentioned monomers.

In order to obtain the polymer (A) and the polymer (B), the above monomer component may be polymerized using a polymerization initiator. The polymerization can be performed by a method such as polymerization in a solvent or bulk polymerization.

The polymerization in a solvent can be carried out batchwise or continuously, with the solvent used being water;
Lower alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane and n-hexane; ester compounds such as ethyl acetate;
Ketone compounds such as acetone and methyl ethyl ketone; and the like. It is selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms in view of the solubility of the raw material monomers, the resulting polymer (A) and polymer (B), and the convenience in using the polymer. It is preferable to use at least one of them. In that case, among lower alcohols having 1 to 4 carbon atoms, methyl alcohol, ethyl alcohol, isopropyl alcohol and the like are particularly effective.

When the polymerization is carried out in an aqueous medium, a water-soluble polymerization initiator such as ammonium or alkali metal persulfate, hydrogen peroxide, 2,2'-azobis-2-methylpropionamidine hydrochloride is used as a polymerization initiator. Agent is used. At this time, an accelerator such as sodium bisulfite and Mohr's salt can be used in combination. For polymerization using a lower alcohol, an aromatic hydrocarbon, an aliphatic hydrocarbon, an ester compound or a ketone compound as a solvent, a peroxide such as benzoyl peroxide or lauroyl peroxide; a hydroperoxide such as cumene hydroperoxide; An azo compound such as bisisobutyronitrile is used as a polymerization initiator. In this case, an accelerator such as an amine compound may be used in combination. Further, when a water-lower alcohol mixed solvent is used, it can be appropriately selected from the above-mentioned various polymerization initiators or a combination of the polymerization initiator and the accelerator. The polymerization temperature is appropriately determined depending on the solvent and the polymerization initiator used, but is usually in the range of 0 to 120 ° C.

The bulk polymerization is carried out using a polymerization initiator such as a peroxide such as benzoyl peroxide or lauroyl peroxide; a hydroperoxide such as cumene hydroperoxide; an azo compound such as azobisisobutyronitrile at 50 to 200 ° C. Within the temperature range of

Further, a thiol chain transfer agent may be used in combination for controlling the molecular weight of the resulting polymer (A) and polymer (B). Thiol chain transfer agents used in this case, the general formula HS-R ¹⁰ -Eg (provided that wherein R ¹⁰ represents an alkyl group having a carbon number of 1 to 2, E is -
OH, —COOM ₃ , —COOR _4, or SO ₃ represents a M ₃ group, M ₃ represents hydrogen, a monovalent metal, a divalent metal, an ammonium group or an organic amine group, and R ₄ has 1 to 1 carbon atoms.
Represents an alkyl group of 10, and g represents an integer of 1 to 2. And, for example, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, and octyl 3-mercaptopropionate. One or more of these can be used.

The polymer (A) and the polymer (B) thus obtained can be used as they are as components of the cement admixture of the present invention. However, if necessary, the polymer is further neutralized with an alkaline substance. The resulting polymer salt may be used as a component of the cement admixture of the present invention. Preferred examples of the alkaline substance include inorganic substances such as hydroxides and carbonates of monovalent metals and divalent metals represented by sodium hydroxide; ammonia; and organic amines. When an anhydride such as maleic anhydride or citraconic anhydride is used for copolymerization, the obtained polymer may be used as it is as a cement admixture or may be used after being hydrolyzed.

The weight average molecular weight of the polymers (A) and (B) is preferably in the range of 500 to 500,000, more preferably in the range of 5,000 to 300,000, and more preferably in the range of 10,000 to 100,000. The range is more preferred. A weight average molecular weight of less than 500, or 500,
If it exceeds 000, the water-reducing performance of the cement admixture is undesirably reduced.

The blending ratio (% by weight) of the polymers (A) and (B) varies depending on the performance balance of the polymer used in combination, but is preferably in the range of 10:90 to 90: 10% by weight, and 20:80 to 90%. A range of 80: 20% by weight is more preferred. Incidentally, two or more polymers (A) or two or more polymers (B) may be used in combination.

The cement admixture of the present invention can be used for hydraulic cements such as portland cement, high-belite cement, alumina cement, various mixed cements, and hydraulic materials other than cements such as gypsum.

When the cement admixture of the present invention is used for mortar or concrete using hydraulic cement,
0.01 to 2.0% by weight of the cement weight, preferably 0.02 to 1.0% by weight, more preferably 0.03 to 1.0% by weight.
What is necessary is just to add the amount of 0.5 weight% at the time of kneading. By this addition, various preferable effects such as achievement of high water reduction rate, improvement of slump loss prevention performance, reduction of unit water amount, increase of strength, and improvement of durability are brought about. If the addition amount is less than 0.01% by weight, the performance is insufficient,
Conversely, even when a large amount exceeding 2.0% by weight is used, the effect thereof substantially reaches a plateau, which is disadvantageous in terms of economy.

In the cement composition of the present invention containing the cement admixture, cement and water as essential components, the amount of cement used per 1 m ^{3 of the} cement composition and the unit water amount are not particularly limited. 185
kg / m ³ , water / cement weight ratio = 0.10-0.7,
Preferably, a unit water volume of 120 to 175 kg / m ³ and a water / cement weight ratio of 0.20 to 0.65 are recommended. If necessary, aggregates such as sand and gravel are added to the cement composition. Further, the cement admixture of the present invention is also effective for mortar and concrete requiring high fluidity such as high fluidity concrete.

The cement admixture of the present invention can be used in combination with a known cement water reducing agent. Known cement water reducing agents to be used in combination include, for example, lignin sulfonic acid salt; naphthalene sulfonic acid formalin condensate; melamine sulfonic acid formalin condensate; polystyrene sulfonic acid salt; aminoaryl sulfonic acid-phenol as described in JP-A-1-113419. An aminosulfonic acid such as a formaldehyde condensate; and a plurality of these known cement water reducing agents can be used in combination.

Further, the cement admixture of the present invention can be used in combination with other known cement additives (materials) as exemplified below.

(1) Water-soluble polymer: unsaturated carboxylic acid polymerization such as polyacrylic acid (sodium), polymethacrylic acid (sodium), polymaleic acid (sodium), and sodium salt of acrylic acid / maleic acid copolymer object;
Polyoxyethylene or polyoxypropylene polymers such as polyethylene glycol and polypropylene glycol or copolymers thereof; methylcellulose, ethylcellulose, hydroxymethylcellulose,
Non-ionic cellulose ethers such as hydroxyethylcellulose, carboxymethylcellulose, carboxyethylcellulose and hydroxypropylcellulose; alkylated or hydroxyalkylated derivatives of polysaccharides such as methylcellulose, ethylcellulose, hydroxyethylcellulose and hydroxypropylcellulose Hydrogen atoms of some or all of the hydroxyl groups are a hydrophobic substituent having a hydrocarbon chain having 8 to 40 carbon atoms as a partial structure, and an ionic hydrophilic substituent containing a sulfonic acid group or a salt thereof as a partial structure. Non-ionic cellulose ethers; yeast glucan, xanthan gum, and β-1.3 glucans (which may be linear or branched; for example, curdlan, baramiron, Bakiman, School Polysaccharides produced by microbial fermentation such as loglucan and laminaran); polyacrylamide; polyvinyl alcohol; starch; starch phosphate; sodium alginate; gelatin; a copolymer of acrylic acid having an amino group in the molecule and a quaternary compound thereof. etc.

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

(3) retarders: gluconic acid, glucoheptonic acid, arabic acid, malic acid or citric acid, and
Oxycarboxylic acids such as inorganic salts or organic salts such as sodium, potassium, calcium, magnesium, ammonium and triethanolamine; monosaccharides such as glucose, fructose, galactose, saccharose, xylose, abitose, repose, isomerized sugar and the like And
Oligosaccharides such as disaccharides and trisaccharides, or oligosaccharides such as dextrin, or polysaccharides such as dextran; saccharides such as molasses containing them; sugar alcohols such as sorbitol;
Magnesium silicofluoride; phosphoric acid and its salts or borate esters; aminocarboxylic acids and their salts; alkali-soluble proteins; humic acid; tannic acid; phenol; polyhydric alcohols such as glycerin; aminotri (methylene phosphonic acid); 1-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) Oil-based antifoaming agents: animal and vegetable oils, sesame oil,
Castor oil, their alkylene oxide adducts and the like.

(7) Fatty acid-based 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, oxyethylene oxypropylene adducts to higher alcohols having 12 to 14 carbon atoms; polyoxypropylene phenyl ether, poly (Poly) oxyalkylene (alkyl) aryl ethers such as oxyethylene nonylphenyl ether; 2,4,7,9-tetramethyl-5-decyne-
4,7-diol, 2,5-dimethyl-3-hexyne-
Acetylene ethers obtained by addition-polymerizing an alkylene oxide to acetylene alcohol such as 2,5-diol, 3-methyl-1-butyn-3-ol; diethylene glycol oleate, diethylene glycol laurate, ethylene glycol distearate, etc. (Poly) oxyalkylene fatty acid esters;
(Poly) oxyalkylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan trioleate; (poly) oxy such as sodium polyoxypropylene methyl ether sulfate and sodium polyoxyethylene dodecyl phenol ether sulfate Alkylene alkyl (aryl) ether sulfates; (poly)
(Poly) such as oxyethylene stearyl phosphate
Oxyalkylene alkyl phosphates; (poly) oxyalkylene alkylamines such as polyoxyethylene laurylamine; polyoxyalkylene amide;

(10) Alcohol-based 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-based 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 (alkylbenzenesulfonic acid), LAS (linear alkylbenzenesulfonic acid), alkane sulfonate, polyoxyethylene alkyl ( Phenyl) ether, polyoxyethylene alkyl (phenyl) ether sulfate or a salt thereof, polyoxyethylene alkyl (phenyl) ether phosphate or a salt thereof, a protein material, alkenyl sulfosuccinic acid,
α-olefin sulfonate and the like.

(16) Other surfactants: 6 to 3 per molecule such as octadecyl alcohol and stearyl alcohol.
Aliphatic monohydric alcohol having 0 carbon atoms, alicyclic monohydric alcohol having 6 to 30 carbon atoms in a molecule such as abiethyl alcohol, 6 to 30 carbon atoms in a molecule such as dodecyl mercaptan, etc. Monovalent mercaptans having atoms, nonylphenols and the like, alkylphenols having 6 to 30 carbon atoms in the molecule, dodecylamines and the like having 6 to 30 carbon atoms in the molecule, molecules such as lauric acid and stearic acid Polyalkylene oxide derivatives in which an alkylene oxide such as ethylene oxide or propylene oxide is added in an amount of 10 mol or more to a carboxylic acid having 6 to 30 carbon atoms therein; and may have an alkyl group or an alkoxy group as a substituent. Alkyl diphenyl ether in which two phenyl groups having a sulfone group are ether-bonded Sulfonates; various anionic 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, silicone, paraffin, asphalt,
Wax and the like.

(18) Rust inhibitors: nitrites, phosphates, zinc oxide, etc.

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

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

Other known cement additives (materials) include cement wetting agents, thickening agents, separation reducing agents, flocculants,
Drying shrinkage reducing agent, strength enhancer, self-leveling agent, rust inhibitor, coloring agent, fungicide, blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, silica fume, silica powder, pozzolan, zeolite, etc. A plurality of these known cement additives (materials) can be used in combination.

Particularly preferred embodiments include the following (i) to
(Ii). (I) A combination in which two components of the cement admixture of the present invention and an antifoaming agent are essential. In addition, as the compounding weight ratio of the defoamer,
0.01 to 10% by weight based on the cement admixture of the present invention
Is preferable, and as the defoaming agent to be used, an oxyalkylene defoaming agent is particularly preferable. (Ii) A combination essentially comprising the two components of the cement admixture of the present invention and lignin sulfonate. The compounding weight ratio of the cement admixture of the present invention to the lignin sulfonate is preferably in the range of 5 to 95:95 to 5, and 10 to 90:
A range of 90 to 10 is more preferred.

[0095]

The present invention will be described more specifically with reference to the following examples. In the examples,% is% by weight unless otherwise specified.
And parts represent parts by weight.

(Production Example 1: Production of Polymer (1)) A glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser was charged with 1698 parts of water and reacted under stirring. Replace the inside of the container with nitrogen, and at 80 ° C
Until heated. Next, 1668 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 25), 332 parts of methacrylic acid and 500 parts of ion-exchanged water were mixed, and 16.7 parts of mercaptopropionic acid as a chain transfer agent were uniformly mixed. By mixing, a monomer mixture aqueous solution was prepared. This monomer mixture aqueous solution and 10% ammonium persulfate aqueous solution 1
84 parts were added dropwise over 4 hours, and 10 minutes after the addition was completed.
A 46% aqueous solution of ammonium persulfate was added dropwise over 1 hour. Thereafter, the temperature was maintained at 80 ° C. continuously for 1 hour to complete the polymerization reaction. Then, the mixture is neutralized with a 30% aqueous sodium hydroxide solution to obtain a weight average molecular weight (converted into polyethylene glycol by GPC; the same applies hereinafter).
Thus, a polymer (1) corresponding to the polymer (A) of the present invention consisting of the polymer aqueous solution No. 00 was obtained.

Thereafter, the same operation as in Production Example 1 was performed to produce Polymers (2) to (6). The contents are summarized in Table 1.

(Production Example 2: Production of Polymer (7)) In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, 1291 parts of ion-exchanged water were added.
1812 parts of polyethylene glycol monoalkenyl ether obtained by adding an average of 50 moles of ethylene oxide to 3-methyl-3-buten-1-ol, 188 maleic acid
The reaction vessel was charged with nitrogen while stirring, and the temperature was raised to 60 ° C. in a nitrogen atmosphere. 50 parts of a 15% aqueous solution of NC-32W (87% 2,2'-azobis-2-methylpropionamidine hydrochloride manufactured by Niho Chemical Co., Ltd.) was added, and the mixture was stirred for 7 hours. The temperature was further raised to 80 ° C. for 1 hour. The polymerization reaction was completed by stirring. And it neutralized with 30% sodium hydroxide aqueous solution, and obtained the polymer (7) corresponding to the polymer (B) of this invention which consists of a polymer aqueous solution with a weight average molecular weight of 26,200.

Thereafter, the same operation as in Production Example 2 was performed to produce Polymers (8) to (11). The contents are shown in Table 2.

[Molecular Weight Distribution Measurement Conditions] Model Waters LCM1 (Millenium)
System) Detector Waters 410 RI detector Eluent type Acetonitrile / ion exchange water = 40 /
60Vol% (PH6.0) Flow rate 0.6 (ml / min) Column type TSK-GEL G4000SWXL + G3000SW manufactured by Tosoh Corporation
XL + G2000SWXL + GUARD COLUMN 7.8 × 300mm, 6.0 × 40mm each Calibration curve Combining polymers of polyethylene glycol standard (mortar test) or more, and adding mortar to which the cement admixture of the present invention or a cement admixture to be compared is added. Prepared and mortar tested.

The mortar test was performed using a material adjusted to 25 ° C. in an atmosphere of 25 ° C. The materials and mortar composition used in the test are as follows. (Formulation A): 800 g of ordinary Portland cement manufactured by Taiheiyo Cement Co., 400 g of Toyoura standard sand, and 240 g of ion-exchanged water containing the present or comparative cement admixture. Table 3 shows the amount of each cement admixture (% by weight of solids relative to cement).

(Formulation B): Same as Formulation A, except that the amount of water was changed to 210 g.

(Measurement of Mortar Flow Value) The mortar was prepared by kneading only cement and sand at a low speed for 30 seconds with a Hobart mortar mixer (model number N-50, manufactured by Hobart), and then adding the above ion-exchanged water for 3 minutes. It was prepared by kneading at medium speed. 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 abrasion, and after 5 minutes from the start of kneading, the cylinder is gently lifted vertically and then spread over the table. And the minor axis were measured, and the average value was taken as the mortar flow value. Thereafter, after the entire amount of the mortar was allowed to stand in a closed container for a predetermined time, the same operation as above was repeated, and the change over time in the mortar flow value was measured. Table 3 shows the results.

The performance evaluation was performed according to the following.

Initial dispersibility (mortar flow value after 5 minutes): ：: 80 mm or more, ×: less than 80 mm (insufficient fluidity) Slump retention (mortar flow value after 60 minutes): ：: 80 mm or more, ×: Less than 80mm (insufficient fluidity)

[0106]

[Table 1]

[0107]

[Table 2]

[0108]

[Table 3]

(Results) (a) In the polymer (1) and the polymer (7), the milliequivalent number of the carboxyl group and the number of moles of the oxyalkylene group both belong to the preferable ranges of the present invention. This alone could not satisfy both initial dispersibility and slump retention. However, in any of Examples 1 to 3, 4 and 6 in which this was mixed, the initial dispersibility and the slump retention were able to be satisfied at the same time.

(B) Furthermore, the blending amounts of the polymer (A) and the polymer (B) in Examples 1 to 4 and 6 were
10 to 90% by weight and the polymer (B) range from 90 to 10% by weight, which is nothing but a synergistic effect of both components. For example, as can be seen from a comparison between Example 3 and Comparative Example 2, even when the blending amount of the polymer (A) is only 10% by weight, the flow value after 5 minutes in the case of using the polymer (B) alone is not significant. Although it was 70, it showed a high flow value of 92, which is much higher than this, and excellent initial dispersibility could be secured. Further, as can be seen from the comparison between Example 2 and Comparative Example 1, even when the blending amount of the polymer (B) is only 10% by weight, 5 minutes and 30 minutes after the case of the polymer (A) alone. Is 92-76 = 16, whereas 101-98 = 3, which is very small, and excellent slump retention can be secured.

(C) As can be seen from the comparison between Example 4 and Comparative Examples 3 and 4, when the amount of the carboxyl group of the polymer (A) exceeds the range of 1.0 to 3.0, Examples 1 to 3 were used. It was apparent that the polymer (A) and the polymer (B) observed in 4 did not exhibit the extremely excellent synergistic effect at all, and in particular, had poor initial dispersibility. This indicated that an excellent synergistic effect was exhibited only by the amount of carboxyl groups disclosed by the present invention.

(D) Similarly, in Comparative Examples 5 and 6, only the EO chain length, that is, the average number of moles of ethylene oxide added was outside the range disclosed in the present invention, and the polymers (A) and (B) Did not show any synergistic effect. In addition, EO
Although a correlation between the chain length and the slump retention was pointed out, it was not always preferable that the EO chain length be long. The results of Example 4 also revealed that extremely excellent slump retention could be ensured even with an added mole number of only 25.

(E) Comparative Examples 7 and 8 as in (c) above
From this, it was found that the preferred amount of carboxyl groups of the polymer (B) was present, and that only within this range, an excellent synergistic effect between the polymers (A) and (B) could be obtained.

(F) As in the case of (d), Comparative Examples 9 and 1
From 0, it was found that a preferable EO chain length of the polymer (B) was present. That is, in Comparative Examples 9 and 10, the flow values after 5 minutes were 66 and 78, respectively, whereas in Example 6 in which the polymers (A) and (B) were blended, the flow values after 5 minutes Was 94, and an extremely high synergistic effect could be obtained. Moreover, the slump retention was excellent.

[0115]

As described above, the cement admixture according to the present invention has excellent dispersibility and slump retention. The cement admixture of the present invention has a general strength to a high strength.
It is effective for mortar and concrete for ultra-high-strength concrete products, and for mortar and concrete requiring high fluidity such as high-fluidity concrete requiring self-filling property.

Claims (1)

[Claims] 1. A polymer (A) containing a structural unit (I) represented by the following general formula (1) and a structural unit (II) represented by the following general formula (2) as essential structural units. And a polymer (B) containing, as essential structural units, a structural unit (III) represented by the following general formula (3) and a structural unit (IV) represented by the following general formula (4). And the carboxyl group in the polymer (A) is converted to an unneutralized form, and the number of milliequivalents of carboxyl groups per 1 g of the polymer (meq / g) is 1.0.
And the number of milliequivalents (meq / g) of carboxyl groups per 1 g of the polymer obtained by converting the carboxyl groups in the polymer (B) into an unneutralized form is from 0.8 to 3.0. A cement admixture characterized by being in the range of 0.5. General formula (1) (Wherein, R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and R ³ O has 2 to 18 carbon atoms.
Represents one or a mixture of two or more kinds of oxyalkylene groups, and in the case of two or more kinds, they may be added in blocks or in random form, and m is the average number of moles of oxyalkylene groups added. And represents an integer of 15 to 100, and R ⁴ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. ) General formula (2) (Wherein, R ⁵ and R ⁶ each independently represent a hydrogen atom or a methyl group, and X represents hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group). Chemical formula 3] (However, in the formula, R ⁷ O represents one kind or a mixture of two or more kinds of oxyalkylene groups having 2 to 18 carbon atoms. N is an average number of moles of the oxyalkylene group, and represents an integer of 20 to 70.) General formula (4) (Wherein, R ⁸ and R ⁹ each independently represent a hydrogen atom or a methyl group, and M ₁ and M ₂ each independently represent hydrogen, a monovalent metal, a divalent metal, an ammonium group or an organic amine group. However, it includes those in which the COOM ₁ group and the COOM ₂ group are combined to form an acid anhydride group (—CO—O—CO—). In this case, M ₁ and M ₂ do not exist.)