JP2001089212A - Liquid cement admixture and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a one-pack type concrete admixture having water reducing performance and also separation reducing performance. SOLUTION: This one-pack type liquid cement admixture is obtained by blending a copolymer 1 and a copolymer 2, which consist of a monomer containing carboxyl group as a structure component. The whole of the carboxyl group incorporated in each copolymer is an acid type. Thus the liquid cement admixture excellent in preservable stability, cement separation reducing property and also cement water reducing property is obtained. These copolymer 1, 2 obtained separately by copolymerization may be mixed with each other, but the copolymer 1 is obtaine by the multistage polymerization, and then the copolymer 2 is copolymerzed step by step in the reaction liquid, thereby obtaing the liquid cement admixture very excellent in compatibility between these copolymers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a concrete admixture and a method for producing the same, and more particularly, to a one-pack type concrete admixture having both water reducing performance and separation reducing performance, and a method for producing the same.

[0002]

2. Description of the Related Art 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. However, simply increasing the fluidity of the concrete may impair the homogeneity of the concrete due to the difference in specific gravity of each component of the concrete, causing a portion of the concrete to precipitate, which may adversely affect the strength and durability of the concrete structure. Use of additives having a water reducing effect is required.

On the other hand, there is an initial crack of concrete as a factor relating to deterioration of concrete, which is caused by sinking of concrete components, uneven expansion and drying shrinkage due to heat of hydration. Here, sinking of concrete is a phenomenon in which mortar components and water are separated before setting, and occurs when the amount of water mixed with cement is increased in order to improve workability. Cracking due to heat of hydration is caused by a temperature difference between the concrete surface and the central portion, and is a serious problem when setting or hardening mass concrete such as a dam or a pier. Furthermore, cracks due to drying shrinkage are caused by water evaporating and drying before setting. Therefore, in order to prevent such deterioration of the concrete, it is required to use a separation reducing agent for the purpose of adjusting the slump characteristics of the highly fluidized concrete. Further, the separation reducing agent is also used for the purpose of preventing bleeding, preventing drying during curing, reducing material separation during casting in water, and suppressing generation of dust in a spray concrete method.

[0004] However, in many cases, the ready-mixed concrete factories are often in a small space, and it is difficult to add tanks for each chemical when mixing two chemicals into cement. That is, it is often difficult to install a tank for separation reducing agent in addition to the tank for cement reducing agent, and there is a demand for a cement admixture having both separation reducing performance and cement water reducing performance. For example, Japanese Patent Application Laid-Open No. Hei 9-71447 discloses a high-performance water reducing agent composition capable of simultaneously stably imparting high fluidity and resistance to material separation reduction to a cement composition.

[0005]

The invention disclosed in the above publication discloses a high-performance water reducing agent composition comprising an aqueous emulsion of a vinyl polymer as a thickener and a water-soluble vinyl copolymer as a dispersant. Things. The aqueous emulsion is
This is an aqueous emulsion of a vinyl polymer obtained by copolymerizing a vinyl monomer having a carboxylic acid group in an amount of 3 to 75% by weight in all the vinyl monomers, and has a liquid property of pH 4 to 8. On the other hand, the water-soluble vinyl copolymer is a water-soluble vinyl copolymer having a sulfonic acid group, a carboxylic acid group and a polyoxyethylene group in a molecule.
According to the description in the above publication, when the pH is increased to 9 or more by a basic hydroxide generated by the hydration reaction of cement, typically calcium hydroxide, the vinyl polymer becomes a carboxylate and the solubility is reduced. Due to the action of the water-soluble vinyl copolymer containing a sulfonate group and the like, the viscosity of the high-performance water reducing agent composition becomes at least twice or more, usually five times or more, even in the region of pH 9 or more. Thus, when the composition is added during the preparation of a cement formulation,
The increase in pH due to the basic hydroxide formed by the hydration reaction of the cement significantly increases the viscosity of the high-performance water reducing agent composition, and as a result, the prepared cement composition has a high fluidity as expected. And material separation resistance can be simultaneously provided.

However, the high-performance water reducing agent composition has high viscosity and is difficult to handle, and in actual use, it may be difficult to provide sufficient fluidity because the amount of use cannot be adjusted.

On the other hand, JP-A-8-225353 discloses a highly fluid admixture for concrete containing a copolymer emulsion having a free carboxylic acid group obtained from a monomer component in a polymer chain. Have been. The admixture is obtained by emulsion polymerization of an ethylenically unsaturated carboxylic acid and an unsaturated monomer copolymerizable with the ethylenically unsaturated carboxylic acid. Since the polymer chain has a free carboxylic acid group obtained from the monomer component, the carboxylic acid group swells and thickens due to the alkali component of the cement paste in the concrete to which the carboxylic acid group is added, thereby impairing the fluidity of the concrete. In addition, it exhibits separation resistance and maintains good flowability of concrete and uniformity of concrete composition.

However, simply copolymerizing a carboxylic acid group-containing compound cannot provide an admixture having sufficient cement separation reducing ability and dispersibility.

[0009]

Means for Solving the Problems In view of the above situation, the present inventors have made intensive studies on a cement admixture,
In a copolymer of a monomer containing a carboxyl group such as acrylic acid, by adjusting the molecular weight and the acid amount, it is possible to adjust the viscosity of the cement composition, and found that it can also provide a cement water reducing effect, The present invention has been completed. That is,
The present invention provides the following (1) to (5).

(1) Weight obtained by copolymerizing at least a monomer composition containing the monomer (a1) represented by the general formula (1) and the monomer (a2) represented by the general formula (2) A copolymer (1) having an average molecular weight of 10,000 to 500,000;
A polymerizable monomer having at least a carboxyl group (b
Weight average molecular weight 1 obtained by copolymerizing a monomer composition containing 1) and (meth) acrylate (b2)
00,000 to 10,000,000 copolymer (2)
(However, the weight average molecular weight of the copolymer (2) is larger than the weight average molecular weight of the copolymer (1)) and 99% to 50% by weight of the copolymer (1) and the copolymer ( 2) A cement admixture characterized by containing 1% by weight to 50% by weight.

[0011]

Embedded image

(Wherein R ¹ , R ² , and R ³ each independently represent a hydrogen atom or a methyl group, and R ⁴ represents —CH
_{2 -, - (CH 2)} 2 -, - (CH 2) 3 -, or -CO
And YO represents one or a mixture of two or more oxyalkylene groups having 2 to 4 carbon atoms. In the case of two or more, YO may be added in block form or in random form. , R ⁵ represents a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, n is a numerical value indicating the average number of added moles of the oxyalkylene group, and represents an integer of 1 to 100. )

[0013]

Embedded image

(Where A ¹ and A ² each independently represent a hydrogen atom or a methyl group or —COOH, and A ¹ and A ² are not simultaneously —COOH, and A ³ is a hydrogen atom , A methyl group or —CH ₂ COOH, and when A ³ is —CH ₂ COOH, both A ¹ and A ² represent a hydrogen atom.) (2) A single unit constituting the copolymer (1) Monomer composition,
5 to 98% by weight of monomer (a1), 95 to 95% of monomer (a2)
2% by weight, and 0 to 50% by weight of another monomer (a3) copolymerizable with these monomers, and the copolymer (2)
Is 5 to 60% by weight of the monomer (b1) and 10 to 95% of the (meth) acrylate (b2).
(1) The cement admixture according to the above (1), which is 0 to 30% by weight, and 0 to 30% by weight of another monomer (b3) copolymerizable with these monomers.

(3) The cement admixture according to the above (1) or (2), wherein the copolymer (2) is obtained by emulsion polymerization.

(4) The copolymer (1) according to the above (1)
And a copolymer (2) according to the above (1), and then adjusting the pH of the mixture to 7 to 9.

(5) The polymerizable monomer having at least a carboxyl group according to claim 1, wherein the copolymer (1) and the copolymer (2) are mixed in the presence of the copolymer (1). The method for producing a cement admixture according to the above (4), wherein a monomer composition containing (b1) and a (meth) acrylate (b2) is copolymerized.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a one-component cement admixture prepared by blending a copolymer (1) having a carboxyl group-containing monomer as a constituent component and a copolymer (2). .
All the carboxyl groups contained in each copolymer are of an acid type. Among the carboxyl group-containing copolymers, a combination of a copolymer excellent in cement dispersibility and a copolymer excellent in cement separation reducing ability is used. The liquid type provides better operability when adding cement compared to the case where a single agent is separately added, and separates cement without excessively increasing the viscosity of the cement composition by using an acid group. This is because it has been found that they exhibit a reducing performance and a cement water reducing effect can be obtained. Further, in order to produce the cement admixture of the present invention, each of the copolymers (1) and (2) obtained by copolymerization may be mixed separately. After obtaining the polymer (1),
By stepwise copolymerizing the copolymer (2) in the reaction solution, it is possible to obtain a cement admixture having extremely excellent compatibility of each copolymer. Hereinafter, the present invention will be described in detail.

The copolymer (1) used in the present invention is a monomer containing at least the monomer (a1) represented by the general formula (1) and the monomer (a2) represented by the general formula (2). Weight average molecular weight of 10,000 to 50 obtained by copolymerizing the body composition.
It is a 000 copolymer.

Here, the monomer (a) represented by the formula (1)
In 1), R ¹ , R ² , and R ³ each independently represent a hydrogen atom or a methyl group, and R ⁴ represents —CH ₂ —, —
(CH ₂ ) ₂ —, — (CH ₂ ) ₃ — or —CO—, YO represents one or a mixture of two or more oxyalkylene groups having 2 to 4 carbon atoms, and ethylene oxide, propylene oxide, For any two or more alkylene oxide adducts selected from among butylene oxide and styrene oxide, random addition, block addition,
Any of alternate addition and the like can be used. In the case of two or more kinds, they may be added in a block shape or in a random shape. R ⁵ represents a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, n is a numerical value indicating the average number of added moles of the oxyalkylene group, and n is preferably an integer of 1 to 100. Since the viscosity increases with a decrease in the average number of moles, an integer of 5 to 80 is preferable, and
An integer from 0 to 60 is more preferred.

Examples of the monomer (a1) wherein R ⁴ is --CO-- include an alkylene oxide adduct of 1 to 100 carbon atoms to (meth) acrylic acid; methanol, ethanol,
1 to 1 carbon atoms such as 2-propanol and 1-butanol
And ester compounds of (meth) acrylic acid with alkoxypolyalkylene glycols obtained by adding an alkylene oxide having 1 to 100 carbon atoms to 30 alkyl alcohols. More specifically, (meth) such as 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 C1-C100 alkylene oxide adduct to acrylic acid; 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-
Various alkoxy polyethylene glycol mono (meth) acrylates such as propoxy polyethylene glycol mono (meth) acrylate, 1-butoxy polyethylene glycol mono (meth) acrylate, and 2-butoxy polyethylene glycol mono (meth) acrylate; methoxy polypropylene glycol mono (meth) Acrylate, ethoxy 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 Various alkoxypolypropylene glycol mono (meth) acrylates such as (meth) acrylate Relates: methoxypolyethylene (poly) propylene glycol mono (meth) acrylate, methoxypolyethylene (poly) butylene glycol mono (meth) acrylate, ethoxypolyethylene (poly) propylene glycol mono (meth) acrylate, ethoxypolyethylene (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, 2-propoxypolyethylene (poly) butylene glycol mono (meth) acrylate, 1
An ester of (meth) acrylic acid with an alcohol to which two or more alkylene oxides such as butoxy polyethylene (poly) propylene glycol mono (meth) acrylate and 1-butoxy polyethylene (poly) butylene glycol mono (meth) acrylate are added; And various alkoxy polyalkylene glycol mono (meth) acrylates;

R ⁴ is —CH ₂ —, — (CH ₂ )
₂ -, or - (CH _{2) 3} - The monomer is allyl alcohol, methallyl alcohol, 2-butene-1
-Ol, 2-methyl-2-buten-1-ol, 3-
Alkylene oxide is added to unsaturated alcohol such as methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-3-buten-2-ol, etc.
Compounds added in an amount of 100 mol can be mentioned, and one or more of these compounds can be used. More specifically, polyethylene glycol 3-methyl-3-butenyl ether, polypropylene glycol 3-methyl-3
-Butenyl ether, 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, one of these may be used alone as the monomer (a1), or two or more thereof may be used in combination. In any case, in order to ensure a balance between hydrophilicity and hydrophobicity,
The oxyalkylene group preferably contains an oxyethylene group as an essential component.

The monomer (a2) is represented by the above formula (2), wherein A ¹ and A ² each independently represent a hydrogen atom or a methyl group, —COOH, and A ¹ , A ² are not simultaneously -COOH, A ³ is a hydrogen atom,
It represents a methyl group or -CH ₂ COOH, and A ³ is -C
In the case of H ₂ COOH, A ¹ and A ² are both hydrogen atoms.

As such a monomer (a2), (meth) acrylic acid, maleic acid, maleic anhydride, crotonic acid, isocrotonic acid, fumaric acid, citraconic acid, mesaconic acid and the like can be used. . In the present invention,
One of these can be used alone, or two or more can be used in combination.

The copolymer (1) used in the present invention comprises 5 to 98% by weight of the monomer (a1) and the monomer (a2) 2
To 95% by weight, more preferably the monomer (a1) 1
5 to 90% by weight of the monomer (a2) with respect to 0 to 95% by weight,
It is particularly preferable to mix the monomer (a2) in the range of 10 to 80% by weight with respect to the monomer (a1) in the range of 20 to 90% by weight. In the copolymer (1), another monomer (a3) copolymerizable therewith in the above range is further contained in a range of 0 to 50% by weight, more preferably 0 to 40% by weight, and particularly preferably. It can be blended in the range of 0 to 30% by weight.

Examples of such a monomer (a3) include an ester of an aliphatic alcohol having 1 to 20 carbon atoms and (meth) acrylic acid; and an addition mole number of a glycol having 2 to 4 carbon atoms of 1 to 100. (Poly) glycol has 1 to 3 carbon atoms
A half ester or diester of an alkyl (poly) alkylene glycol to which an alkylene oxide of 0 is added and an unsaturated dicarboxylic acid such as maleic acid, fumaric acid, itaconic acid, or citraconic acid; maleamic acid and a glycol having 2 to 4 carbon atoms Or a half amide of these glycols with a polyalkylene glycol having an addition mole number of 2 to 100; triethylene glycol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, (poly ) (Poly) alkylene glycol di (meth) acrylates such as ethylene glycol (poly) propylene glycol di (meth) acrylate; hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acyl And bifunctional (meth) acrylates such as trimethylolpropane di (meth) acrylate; (poly) alkylene glycol dimaleates such as triethylene glycol dimaleate and polyethylene glycol dimaleate; vinyl sulfonate, (meth) allyl sulfonate, 2- (meth) acryloxyethyl sulfonate, 3- (meth) acryloxypropyl sulfonate, 3- (meth) acryloxy-2-hydroxypropyl sulfonate, 3- (meth) acryloxy-2-hydroxypropyl sulfophenyl ether, 3- (Meth) acryloxy-2-hydroxypropyloxysulfobenzoate, 4- (meth) acryloxybutylsulfonate, (meth) acrylamidomethylsulfonic acid,
Unsaturated sulfonic acids such as (meth) acrylamidoethylsulfonic acid, 2-methylpropanesulfonic acid (meth) acrylamide, and styrenesulfonic acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, glycidyl (meth) ) Esters of unsaturated monocarboxylic acids such as acrylate, methyl crotonate, ethyl crotonate, propyl crotonate and alcohols having 1 to 30 carbon atoms; unsaturated monocarboxylic acids such as methyl (meth) acrylamide and carbon Amides with an amine having 1 to 30 atoms; styrene,
vinyl aromatics such as α-methylstyrene, vinyltoluene, 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) acrylate; dienes such as butadiene, isoprene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene; (meth) acrylamide, (meth) ) Acrylic alkylamide, 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; unsaturated aminos such as dimethylaminoethyl (meth) acrylate Compounds; vinyl ethers such as methoxypolyethylene glycol monovinyl ether, polyethylene glycol monovinyl ether, methoxypolyethylene glycol mono (meth) allyl ether, and polyethylene glycol mono (meth) allyl ether; Rirueteru like; polydimethylsiloxane propylamino maleamic acid, polydimethylsiloxane aminopropylene amino maleamic acid, polydimethylsiloxane - bis - (propylamino maleamic acid), polydimethylsiloxane - bis -
(Dipropyleneaminomaleamic acid), polydimethylsiloxane- (1-propyl-3-acrylate),
Siloxane derivatives such as polydimethylsiloxane- (1-propyl-3-methacrylate), polydimethylsiloxane-bis- (1-propyl-3-acrylate), polydimethylsiloxane-bis- (1-propyl-3-methacrylate); And the like, and one or more of these can be used.

The monomer (b1) constituting the copolymer (2) used in the present invention is not particularly limited as long as it is a polymerizable monomer having a carboxyl group. For example, unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and isocrotonic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid; A monoester with an aliphatic alcohol of 20; an alkylene oxide monoadduct having 2 to 18 carbon atoms to the unsaturated dicarboxylic acid; a monoester having 1 to 5 carbon atoms such as methanol, ethanol, 2-propanol and 1-butanol. A monoester compound of an alkoxypolyalkylene glycol obtained by adding an alkylene oxide having 2 to 18 carbon atoms to an alkyl alcohol, and the unsaturated dicarboxylic acid;
And the like.

The monomer (b2) is not particularly limited as long as it is a (meth) acrylic acid ester, and is preferably an ester of (meth) acrylic acid and an aliphatic alcohol having 1 to 8 carbon atoms. More preferably, it is an ester with an alcohol having 1 to 6 carbon atoms, particularly preferably an ester with an alcohol having 1 to 4 carbon atoms. Copolymer (2)
By using such a (meth) acrylic ester as a structural unit, a cement admixture excellent in cement separation reducing effect can be obtained.

Monomer (b1) constituting copolymer (2)
And the monomer (b2) are mixed at a ratio of 5-6
(Meth) acrylic acid ester 10 to 9% by weight
5% by weight, more preferably 7 to 55% by weight of the monomer (b1), 20 to 93% by weight of the (meth) acrylate, particularly preferably 10 to 50% by weight of the monomer (b1) (Meth) acrylic acid ester is 30 to 90% by weight. In the copolymer (2), another monomer (b3) copolymerizable therewith in the above range is further contained in an amount of 0 to 30% by weight.
, More preferably 0 to 25% by weight, particularly preferably 0 to 20% by weight. As such a monomer (b3), the above-mentioned monomer (a1),
Those described as the monomer (a2) and the monomer (a3) can be used.

In order to obtain the copolymer (1) or the copolymer (2) used in the present invention, the monomer component may be polymerized using a polymerization initiator. The polymerization can be carried out by a method such as emulsion polymerization, 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. Raw material monomer and obtained copolymer (1)
From the viewpoint of the solubility of the copolymer (2) and the convenience in using the polymer, it is preferable to use at least one selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms. In that case, among the 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

The emulsion polymerization may be carried out by a conventionally known emulsion polymerization method using a known emulsifier, a polymerization initiator, a chain transfer agent or the like, or may be a soap-free emulsion polymerization using no emulsifier.

Examples of the anionic surfactant include alkyl sulfate salts such as sodium dodecyl sulfate, potassium dodecyl sulfate and ammonium alkyl sulfate; sodium dodecyl polyglycol ether sulfate; sodium sulfolisinoate; sulfonated paraffin salts and the like. Alkyl sulfonates such as sodium dodecylbenzene sulfonate, alkali metal sulfate of alkali phenol hydroxyethylene; high alkyl naphthalene sulfonate; naphthalene sulfonic acid formalin condensate, sodium laurate, triethanolamine oleate, triethanolamine Fatty acid salts such as ahiate; polyoxyalkyl ether sulfates; poly Reactive anionic emulsifiers having a double bond such as xylethylene carboxylate sulfate, polyoxyethylene phenyl ether sulfate; dialkyl succinate sulfonate; polyoxyethylene alkylaryl sulfate, etc. can be used. .

Examples of the nonionic surfactant include polyoxyethylene alkyl ether; polyoxyethylene alkyl aryl ether; sorbitan aliphatic ester; polyoxyethylene sorbitan aliphatic ester; and glycerol monolaurate. Aliphatic monoglyceride; polyoxyethyleneoxypropylene copolymer, ethylene oxide and aliphatic amine,
Condensation products with amides or acids can be used.

As the above-mentioned polymer surfactant, for example,
Polyvinyl alcohol and modified products thereof; (meth) acrylic acid-based water-soluble polymer; hydroxyethyl (meth) acrylic acid-based water-soluble polymer; hydroxypropyl (meth) acrylic acid-based water-soluble polymer; .

When the above-mentioned emulsifier is used, the amount of the emulsifier is not particularly limited as long as it can produce an emulsion and can exert a desired function of stabilizing the produced emulsion. Therefore, the amount used is usually 0.1 to 10% by weight, preferably 1 to 10% by weight, based on the total amount of the polymerizable monomer.
5% by weight. If the amount of the emulsifier is less than 0.1% by weight, the stability of the emulsion polymerization is remarkably lost, a large amount of aggregates are generated, or the whole is aggregated. on the other hand,
If the amount of the emulsifier exceeds 10% by weight, it is not preferable because the setting of the cement composition is delayed or excessive air is entrained.

As the above-mentioned polymerization initiator, for example, persulfates such as potassium persulfate, ammonium persulfate and sodium persulfate, which are substances that decompose by heat to generate molecules having radicals; 2,2'-azobis ( Water-soluble azo compounds such as 2-amidinopropane) dihydrochloride and 4,4'-azobis (4-cyanopentanoic acid); a thermal decomposition initiator such as hydrogen peroxide; and a combination of an oxidizing agent and a reducing agent. Redox polymerization initiators such as hydrogen peroxide and ascorbic acid, t-butyl hydroperoxide and Rongalit, potassium persulfate and metal salts, and ammonium persulfate and sodium bisulfite to generate molecules having radicals in the oxidation-reduction reaction. And one or more of these can be used as a mixture.

The amount of the above-mentioned polymerization initiator may be any amount as long as it can easily generate free radicals or ions and exhibit a desired function of initiating polymerization by a chain reaction. Is usually 0.
001 to 1% by weight, preferably 0.01 to 0.5% by weight
It is. If the amount of the polymerization initiator is less than 0.001% by weight, the polymerization will be remarkably slow or the polymerization will not start. On the other hand, when the amount of the polymerization initiator exceeds 1% by weight, the polymerization becomes unstable and aggregates increase.

Further, at the time of the above-mentioned emulsion polymerization, it is possible to appropriately add various conventionally known hydrophilic solvents and additives as described below as needed, as long as the physical properties are not adversely affected. .

In order to promote emulsion polymerization, for example, reducing agents such as sodium pyrobisulfite, sodium sulfite, sodium bisulfite, ferrous sulfate, sodium formaldehyde sulfoxylate, L-ascorbic acid and salts thereof are used. Alternatively, for example, a chelating agent such as sodium ethylenediaminetetraacetate and glycine may be used in combination. In addition, for example, a dispersant such as sodium polyacrylate, an electrolyte such as potassium chloride, disodium phosphate, trisodium phosphate, diammonium phosphate, sodium pyrophosphate, sodium tripolyphosphate, a pH adjuster, and the like. They can be used together.

The method of adding the polymerizable monomer to the polymerization reaction system is not particularly limited, and any method such as a batch addition method, a monomer dropping method, a pre-emulsion method, a power feed method, a seed method, and a multi-stage addition method can be used. Can be used.

In preparing the cement admixture of the present invention, a chain transfer agent may be used to control the molecular weight of the copolymer (1) and copolymer (2) obtained. Examples of the chain transfer agent include t-dodecylmercaptan (1,1-dimethyldecane-1-thiol), 1-hexadecanethiol, 1,10-decanethiol, 1,8
-Dimercapto-3,6-dioxaoctane, 1,5
10-decanetrithiol, mercaptopropionic acid 2
-Ethylhexyl ester, octanoic acid 2-mercaptoethyl ester, carbon tetrachloride, carbon tetrabromide, α-methylstyrene dimer, terpinolene, α-terpinene,
β-terpinene, dipentene, allyl alcohol, 2-
Amino-propanol and the like.

The weight average molecular weight of the copolymers (1) and (2) thus obtained is preferably 10,000 to 500,000 for the copolymer (1). Preferably 10,000-400,
000, particularly preferably 10,000 to 300,00
0. If the weight-average molecular weight is less than 10,000 or more than 500,000, the water-reducing ability of the cement admixture is undesirably reduced. The weight average molecular weight of the copolymer (2) is from 100,000 to 10,000.
00,000, more preferably 2
00,000,000 to 8,000,000, particularly preferably 3
It is between 00,000 and 5,000,000. This is because in this range, the copolymers (1) and (2) are excellent in compatibility, and excellent in water reducing performance and cement separation reducing performance. Here, the weight average molecular weight is a numerical value expressed in terms of styrene by gel permeation chromatography. However, the weight average molecular weight of the copolymer (2) is larger than the weight average molecular weight of the copolymer (1). Preferably,
The weight average molecular weight of the copolymer (2) is at least twice the weight average molecular weight of the copolymer (1).

The cement admixture of the present invention comprises the copolymers (1) and (2) in an amount of 99 to 50% by weight of the copolymer (1) and 1% by weight of the copolymer (2). To 50% by weight, more preferably 98 to 98% by weight of the copolymer (1).
55%, 2 to 45% by weight of copolymer (2), particularly preferably 97 to 60% of copolymer (1), 3 to 4 of copolymer (2)
0% by weight. This is because in this range, both the cement separation reducing ability and the dispersibility are excellent.

In addition, the copolymer (1) and copolymer (2) obtained as described above can be used as they are as components of the cement admixture of the present invention. Adjust to pH 7-9,
It is preferred to completely dissolve the emulsion. Depending on the preparation method of each copolymer, the obtained copolymers (1) and (2) may be inferior in compatibility, but by adjusting the pH to 7 to 9, the copolymer (2) This is because particles can be dissolved to obtain a cement admixture having a uniform composition. In the cement admixture thus obtained, an acid group such as a carboxyl group becomes a base. Such a cement admixture also effectively exhibits cement dispersibility and separation reducing effect in actual use.

Preferred examples of the alkaline substance which can be used for adjusting the pH include inorganic substances such as hydroxides and carbonates of monovalent metals and divalent metals represented by sodium hydroxide; ammonia; and organic amines. It is listed as. When an anhydride such as maleic anhydride or citraconic anhydride is used for the copolymerization, the obtained copolymer may be used as it is as a cement admixture or may be used after being hydrolyzed.

The liquid cement mixture of the present invention is prepared by first polymerizing the copolymer (1) with an aqueous solution, and then using the resulting copolymer (1) -containing solution as an emulsifier. ) Can be used to prepare a cement admixture having the above composition by two-stage polymerization in which the monomer components constituting component (1) are added. This is achieved because the copolymer (1) is in the acid form. That is, when the copolymer (1) is a base type,
When the copolymer (2) is polymerized by two-stage polymerization after the initial polymerization, the pH of the reaction solution becomes high, so that the polymerizable monomer (b1) having a carboxyl group is not subjected to emulsion polymerization, but to an aqueous solution. To polymerize, copolymer (2)
Is not sufficiently large, and it is difficult to obtain a copolymer (2) having a sufficient separation-reducing effect.
However, in the present invention, since the copolymer (1) is of the acid type, the copolymer (2) excellent in cement separation reducing ability can be prepared very easily by two-stage polymerization. In addition, a cement admixture having excellent dispersion stability and storage stability can be obtained without using an emulsifier substantially.

In other words, the cement admixture of the present invention is characterized in that the composition of the above-mentioned specific copolymer (1) is excellent as a cement dispersant and also effective as an emulsifier. In preparing a one-part admixture having both cement dispersibility and cement separation reducing property, the copolymer (1) acts as an emulsifier, and the copolymer (2) is obtained by emulsion polymerization. As a result, the finally prepared cement admixture has a form in which the copolymer (1) is present around the copolymer (2). When the thus prepared cement admixture is mixed with cement, the cement (1) exhibits sufficient cement dispersibility at an early stage of cement admixture due to the action of the copolymer (1). The carboxyl group of (1) is neutralized by the alkali of the cement, the copolymer (2) is dissolved, and the action of the copolymer (2) exerts a stable cement separation reducing action. In addition, since the copolymer (1) acts as a dispersion stabilizer for the particles of the copolymer (2) in the stability of the liquid preparation, it is excellent in storage stability.

The liquid cement mixture of the present invention can be used for cement and hydraulic materials other than cement such as gypsum. Here, the cement is not particularly limited as long as it can be used for paste, mortar or concrete.For example, various kinds of Portland cement such as ordinary, fast strong, super fast, moderate heat, white, etc. Cement, belite-rich cement, alumina cement, fly ash cement, blast furnace cement, silica cement, various mixed cements, and the like.

When the cement admixture of the present invention is used for mortar or concrete using hydraulic cement, it is used in an amount of 0.01 to 10% by weight, preferably 0.05 to 5% by weight, more preferably 0.05 to 5% by weight of the cement weight. 0.1-3% by weight
May be added 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. 0.0
If the amount is less than 1% by weight, the performance is insufficient. Conversely, even if a large amount exceeding 10% by weight is used, the effect is substantially flattened, and the economical efficiency is disadvantageous.

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

(1) Water-soluble polymer substance: 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 emulsions: 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 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 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 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 molecules 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 inhibitor: nitrite, phosphate, zinc oxide, etc.

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

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

Other known cement additives include:
Cement wetting agent, thickener, separation reducing agent, flocculant, drying shrinkage reducing agent, strength enhancer, self-leveling agent, rust inhibitor,
Colorants, fungicides, blast furnace slag, fly ash, cinder ash, clinker ash, husk ash,
Examples thereof include silica fume, silica powder, pozzolan, zeolite, and the like, and a plurality of these known cement additives can be used in combination.

The appropriate amount of the additives which can be blended varies depending on the intended use, the kind used, and the like, and can be appropriately selected. It has useful properties such as thickening action, material separation reducing action, etc.
Concrete and mortar, if blending a more effective amount within the range in which the effect excellent in workability at the time of the preparation of the cement composition such as cement paste can be usefully expressed,
It is not particularly limited, and can be blended in a known amount.

The apparatus for kneading these cement compositions can be applied to various mixers (mixers) conventionally used for preparing such cement compositions such as concrete. A forced mixing mixer, a horizontal single-shaft type, a horizontal twin-shaft type, a drum type, a tilting type, a continuous type mixer, or the like can be used.

[0077]

EXAMPLES Examples of the present invention will be shown below, but these are given for illustrative purposes and do not limit the spots of the present invention. In the following, parts and% are parts by weight,
It represents% by weight.

REFERENCE EXAMPLE 1 1698 parts of water was charged into a glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, and the reactor was replaced with nitrogen under stirring.
Heated to 0 ° C. Next, 1668 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 25), methacrylic acid 332
And 500 parts of water, and 16.7 parts of mercaptopropionic acid as a chain transfer agent were uniformly mixed to prepare an aqueous monomer mixture solution. This monomer mixture aqueous solution and 10% ammonium persulfate aqueous solution 18
4 parts were added dropwise over 4 hours, and 10%
46 parts of an aqueous ammonium persulfate solution was added dropwise over 1 hour.
Thereafter, the temperature was maintained at 80 ° C. continuously for 1 hour to complete the polymerization reaction. Weight average molecular weight (calculated as polyethylene glycol by GPC; hereinafter the same) 23,8
00, peak top molecular weight 18,200, nonvolatile concentration 4
A 5.1% copolymer solution (1) was obtained.

Reference Example 2 In a flask equipped with two dropping funnels, a stirrer, a thermometer, a nitrogen inlet tube and a condenser, 327 parts of ion-exchanged water, an emulsifier polyoxyethylene nonylphenyl ether sulfate ammonium (Daiichi Kogyo Seiyaku Co., Ltd.) 4 parts of Hytenol N-08 (trade name, manufactured by the company) were charged, and Hytenol N-08 was completely dissolved at 72 ° C under stirring. Internal temperature 72 ° C
Nitrogen was slowly flowed as it was, and the atmosphere in the flask was replaced with nitrogen. After sufficient nitrogen replacement, 105 parts of methacrylic acid and methyl acrylate 1 prepared in advance were dropped from the dropping funnel.
30 parts of a pre-emulsion mixture obtained by vigorously stirring 95 parts of a 1.6% hytenol N-08 aqueous solution of 300 parts was added thereto, followed by stirring for 5 minutes. Next, 1 part of a 5% aqueous sodium sulfite solution and 4 parts of a 1% ammonium persulfate aqueous solution were added, and stirring was continued for 20 minutes while keeping the internal temperature at 72 ° C. to carry out initial polymerization. The remaining 570 parts of the pre-emulsion mixture and 64 parts of 1% ammonium persulfate were added dropwise thereto over 2 hours. After completion of the dropwise addition, the temperature was raised to 80 ° C., and stirring was continued for 1 hour, followed by cooling to complete the polymerization, thereby obtaining a copolymer solution (2) having a nonvolatile content of 30.8%. This was diluted and dissolved by adding an aqueous sodium hydroxide solution, and the weight average molecular weight was about 1,420,000 and the peak top molecular weight was 2,030,000.

Example 1 A copolymer solution (1) 250 was added to 320 parts of ion-exchanged water.
And 30 parts of the copolymer solution (2), and neutralized with 30 parts of a 30% aqueous sodium hydroxide solution to obtain a nonvolatile content of 20.
A 7% cement admixture (1) was obtained. Table 1 shows the properties of the cement admixture (1).

Example 2 A flask equipped with three dropping funnels, a stirrer, a thermometer, a nitrogen inlet tube and a cooler was charged with 505 parts of ion-exchanged water and 300 parts of the copolymer solution (1). 45 ° C
, Nitrogen was gently flown, and the atmosphere in the flask was replaced with nitrogen. After sufficiently purging with nitrogen, 22.7 parts of methacrylic acid and ethyl acrylate prepared in advance from a dropping funnel.
6.5 parts of 3 parts of the monomer mixture were charged and stirred for 5 minutes. Next, 6.5 parts of a 0.2% aqueous hydrogen persulfate solution and 6.5 parts of a 0.31% ascorbic acid aqueous solution were charged, and stirring was continued for 10 minutes while maintaining the internal temperature at 45 ° C. to perform initial polymerization.
The remaining 58.5 parts of the monomer mixture and 0.2%
An aqueous hydrogen persulfate solution (58.5 parts) was added dropwise over 2 hours. After completion of the dropwise addition, stirring was continued for 1 hour to complete polymerization, followed by cooling to obtain a cement admixture (2) having a nonvolatile content of 20.9%.

This was diluted, and an aqueous solution of sodium hydroxide was added and dissolved to measure the weight average molecular weight. As a result of measuring the molecular weight by GPC, two peak tops of about 18,200 and 780,000 were observed. Using a waveform processing software, the molecular weight distribution chart of the copolymer solution (1) measured above was subtracted from the molecular weight distribution curve by adjusting the peak intensity to obtain an average molecular weight of 1,050,000 and a peak top. Molecular weight 800,0
00. Table 1 shows the properties of the cement admixture (2).

Comparative Reference Examples 1 and 2 Copolymer solution (1) 25 was added to 301.4 parts of ion-exchanged water.
0 parts, biopolymer separation and reduction agent (Takeda Pharmaceutical Co., Ltd.)
48.6 parts, and 30%
The mixture was neutralized with 30 parts of an aqueous sodium hydroxide solution to prepare a comparative cement admixture (1) having a nonvolatile content of 27.0%. Similarly, instead of biopoly, a cellulosic separation-reducing agent (trade name: Cell Crate, manufactured by Daicel Chemical Industries, Ltd.)
Was added in the same amount to prepare a comparative cement admixture (2). Table 1 shows the properties of the comparative cement admixtures (1) and (2).

[0084]

[Table 1]

Examples 3 and 4 Ordinary Portland cement (Chichibu Onoda cement, specific gravity 3.16) as cement, Oigawa-based land sand (specific gravity 2.62, FM 2.71) as fine aggregate, and Ome product as coarse aggregate Crushed hard sandstone (specific gravity 2.64, MS 20 mm) was used.

As the cement admixture, the above-mentioned Example 1,
The cement admixtures (1) and (2) obtained in 2 were used. In order to adjust the amount of air, a commercially available antifoaming agent (Aqualen 3062, manufactured by Kyoeisha Chemical Co., Ltd.) was used.

The compounding conditions of the cement composition were a unit cement amount of 500 kg / m ³ , a unit water amount of 165 kg / m ³ and a fine aggregate ratio of 45%.

Concrete was prepared according to the following procedure under the mixing conditions of the above-mentioned raw materials and cement composition.

(1) 44.2 kg of fine aggregate and 25.0 kg of ordinary Portland cement were charged into a 50 liter pan-type forced kneading mixer and kneaded for 10 seconds.

(2) A cement admixture having the amount shown in Table 2 below was kneaded, and 8.11 kg of water was added to the fine aggregate / cement prepared in (1) above and kneaded until the mortar became uniform. Was measured. The mortar became uniform at the kneading times shown in Table 2 below. After the mortar became uniform, kneading was further continued for 30 seconds each.

(3) Thereafter, 44.2 kg of the coarse aggregate was put into the mortar prepared in the above (2), and kneaded for further 90 seconds to produce each concrete.

The above methods (1) to (4) for preparing the concrete
Slump value and flow value were measured for each concrete manufactured by the procedure shown in (3).

Measurement Method Slump value and flow value were measured according to JIS A11.
01. Table 2 shows the results. In addition, the addition amount of the cement admixture is a solid content ratio to the cement.

[0094]

[Table 2]

Comparative Examples 1 and 2 Ordinary Portland cement (Chichibu Onoda Cement, specific gravity 3.16) as cement, Oigawa-based land sand (specific gravity 2.62, FM 2.71) as fine aggregate, and Ome as coarse aggregate Crushed hard sandstone (specific gravity 2.64, MS 20 mm) was used.

As the cement admixtures, the comparative cement admixtures (1) and (2) obtained in Comparative Reference Examples 1 and 2 were used. In order to adjust the amount of air, a commercially available defoamer (manufactured by Kyoeisha Chemical Co., Ltd .: trade name Aqualen 30)
62) was used.

The compounding conditions of the cement composition were a unit cement amount of 500 kg / m ³ , a unit water amount of 165 kg / m ³ and a fine aggregate ratio of 45%.

Concrete was prepared according to the following procedure under the mixing conditions of the above-mentioned raw materials and cement composition.

(1) 44.2 kg of fine aggregate and 25.0 kg of ordinary Portland cement were put into a 50 liter pan-type forced kneading mixer and kneaded for 10 seconds.

(2) 8.11 kg of kneading water containing 324 g of each of the comparative cement admixtures (1) and (2) was added to the fine aggregate / cement prepared in (1) above, and kneaded. The time until uniformity was measured. When the comparative cement admixture was weighed, it was well stirred and weighed before separation. The mortar became uniform at the kneading times shown in Table 3 below. After the mortar became uniform, kneading was further continued for 30 seconds each.

(3) Thereafter, 44.2 kg of the coarse aggregate was charged into the mortar prepared in the above (2), and the mixture was further kneaded for 90 seconds to produce each concrete.

The above methods (1) to (5) for preparing the concrete
The slump value and the flow value of each concrete manufactured by the procedure shown in (3) were measured in the same manner as in Examples 3 and 4. Table 3 shows the results.

[0103]

[Table 3]

[0104]

(1) The cement admixture of the present invention is excellent in separation reduction and cement dispersibility. The comparative cement admixture (1) in Table 3 is the copolymer (1) of the present invention.
And a separation reducing agent of a conventional product, which is 22 compared to the slump value of 25 or more shown in the cement admixtures (1) and (2) of the present invention. ) And (2) do not cause separation, but use of the comparative cement admixture (1) clearly shows separation.

(2) According to the present invention, the copolymer (1) and the copolymer (2) can be separately prepared, and then these can be combined to obtain a one-component cement admixture. The cement admixture can also be obtained by two-stage polymerization in which the copolymer (1) is initially polymerized and the copolymer (2) is copolymerized. In particular, the two-stage polymerization was made possible by the use of the acid-type copolymer (1). As a result, as shown in Example 2, storage stability, separation reduction,
A cement admixture having excellent fluidity can be obtained.

(3) Since the cement admixture of the present invention has excellent compatibility between the copolymer (1) and the copolymer (2), it is stable in an emulsion or solution as shown in Table 1. Excellent. Therefore, there is no need to mix before use, and use is simple. This is common in that the cement admixtures (1) and (2) in Tables 2 and 3 and the comparative cement admixture (2) do not separate when used for cement. It is also evident from the fact that the comparative cement admixture itself is separated and requires agitation to achieve the same effect.

Claims (5)

[Claims] 1. A weight average obtained by copolymerizing at least a monomer composition containing a monomer (a1) represented by the general formula (1) and a monomer (a2) represented by the general formula (2). Molecular weight 1
000 to 500,000 copolymer (1) and a polymerizable monomer (b) having at least a carboxyl group.
Weight average molecular weight 1 obtained by copolymerizing a monomer composition containing 1), (meth) acrylate and (b2)
00,000 to 10,000,000 copolymer (2)
(However, the weight average molecular weight of the copolymer (2) is larger than the weight average molecular weight of the copolymer (1).) The copolymer (1) is 99% to 50% by weight, and the copolymer ( 2) A cement admixture characterized by containing 1% by weight to 50% by weight. Embedded image (Wherein, R ¹ , R ² , and R ³ each independently represent a hydrogen atom or a methyl group, and R ⁴ represents —CH ₂ —, — (C
H ₂ ) ₂ —, — (CH ₂ ) ₃ — or —CO—;
O represents an oxyalkylene group having 2 to 4 carbon atoms, and n is 2
In the above cases, the same kind or two or more kinds may be used, and in the case of two or more kinds, they may be added in block form or in random form, and R ⁵ is a hydrogen atom or Represents an alkyl group having 1 to 30 carbon atoms, n is a numerical value indicating the average number of added moles of the oxyalkylene group,
Indicates an integer. ) (However, in the formula, A ¹ and A ² each independently represent a hydrogen atom or a methyl group or —COOH, and A ¹ and A ² are not simultaneously —COOH, and A ³ is a hydrogen atom or a methyl group. or indicates -CH ₂ COOH, and a ³ is -CH ₂ C
In the case of OOH, both A ¹ and A ² represent a hydrogen atom. ) 2. A monomer composition constituting the copolymer (1) comprises 5 to 98% by weight of a monomer (a1) and a monomer (a2).
95 to 2% by weight, and 0 to 50% by weight of another monomer (a3) copolymerizable with these monomers, and the monomer composition constituting the copolymer (2) is: 5 to 60% by weight of the monomer (b1), 10 to 95% by weight of the (meth) acrylate (b2), and 0 to 30% by weight of another monomer (b3) copolymerizable with these monomers. %. 3. The cement admixture according to claim 1, wherein 3. The cement admixture according to claim 1, wherein the copolymer (2) is obtained by emulsion polymerization. 4. The method according to claim 1, wherein the copolymer (1) according to claim 1 and the copolymer (2) are mixed, and the pH of the mixture is adjusted to 7 to 9. Of producing a cement admixture. 5. A mixture of the copolymer (1) and the copolymer (2), wherein the monomer (b1) and the (meth) acrylate (b2) are mixed in the presence of the copolymer (1). The method for producing a cement admixture according to claim 4, which is obtained by copolymerizing a monomer composition containing