JP2000191355A - Cement admixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement admixture which efficiently produces a shrinkage reducing effect as well as a superior fluidizing effect and a water reducing effect by incorporating monomers having specified structure as copolymerizable monomer components. SOLUTION: The cement admixture contains a monomer (a) of formula I [where R1 and R2 are each H or methyl; X is O, CH2O or COO; and (m) is 7-100], e.g. a polyoxyethylene (meth)allyl ether, a monomer (b) of formula II [where R3 is H or methyl; R4 is a 1-24C hydrocarbon; Y is O or CH2O; A is a 2-4C alkylene oxide; (n) is 1-4 when R4 is 1C hydrocarbon and (n) is 2-100 when R4 is a 2-24C hydrocarbon], e.g. polyoxyethylene methylvinyl ether, a monomer (c) which is an unsaturated polycarboxylic acid or its salt, e.g. maleic anhydride and a monomer (d) which is a sulfonic acid-containing monomer, e.g. vinylsulfonic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a dispersant, a water reducing agent,
The present invention relates to a multifunctional cement admixture which has excellent performance as a fluidizing agent and also has an effect of reducing concrete shrinkage, and a cement composition containing the cement admixture.

[0002]

2. Description of the Related Art Recently, higher requirements have been demanded for concrete in terms of function, quality, workability and the like. For example, there is an increasing need for durable high-strength concrete and high-fluidity concrete with good workability without the need for compaction by vibrators. For the production of these concretes, concrete kneaded materials are indispensable in order to impart water reduction and fluidity, and sulfonic acids such as naphthalene sulfonic acid formalin condensate, melamine sulfonate and amino sulfonate are used as cement admixtures. Admixtures based on carboxylic acids and admixtures based on carboxylic acids are widely used. On the other hand, concrete has a serious drawback of drying and shrinking upon hardening. Particularly in the case of concrete having a small water / cement ratio, self-shrinkage accompanying a decrease in the volume of constituent minerals overlaps, causing cracks. ing.
In order to improve the problem of drying shrinkage, a conventional admixture for imparting water-reducing and fluidity is ineffective, and for the purpose of reducing shrinkage, a lower alcohol alkylene oxide adduct is disclosed in JP-B-56-51148. Japanese Patent Application Laid-Open No. Sho 59-152253 discloses a polyoxypropylene derivative, and Japanese Patent Publication No. 1-53214 discloses an adduct of a polyhydric alcohol alkylene oxide, and a method using the alkylene oxide derivative is widely used. However, in order to produce high-strength concrete or high-fluidity concrete in which cracks caused by the shrinkage are suppressed, it is necessary to use a large amount of a shrinkage reducing agent together with a cement admixture, and the concrete becomes expensive. Therefore, there is a problem that the operation is complicated, and there is a demand for improvement.

[0003]

DISCLOSURE OF THE INVENTION In order to solve the above-mentioned problems, the present inventors have conducted detailed studies on the water-reducing and fluidizing effects of a cement admixture and the mechanism of action of a shrinkage reducing agent. By bonding molecules that give the effect of reducing shrinkage to the agent molecules in a chemically stable form,
It has been found that the shrinkage reducing effect can be efficiently exhibited. That is, the present invention relates to a multifunctional cement admixture having excellent performance as a dispersant, a water reducing agent, a fluidizing agent, etc., and at the same time, having a concrete shrinkage reducing effect, and a cement composition containing the cement admixture. It is.

[0004]

According to the present invention, 5 to 70 mol% of a monomer (a) represented by the following general formula (1) is used.
And monomers (b) 5 to 8 represented by the following general formula (2)
There is provided a cement admixture comprising a copolymer containing 0 mol% and 5 to 50 mol% of an unsaturated polycarboxylic acid or a salt monomer (c) thereof. Further, there is provided a cement admixture characterized by comprising a copolymer containing 0.1 to 40 mol% of the sulfonic acid group-containing monomer (d). General formula (1):

Embedded image (Wherein, R1, R2: hydrogen or a methyl group X: O, CH ₂ O or COO m:. Represents the average condensation number 7-100) In formula (2):

Embedded image (Wherein, R3: hydrogen or a methyl group R4: a hydrocarbon group having 1 to 24 carbon atoms Y: O or CH ₂ O A: an alkylene oxide group having 2 to 4 carbon atoms, used alone or as a mixture n: R4 When the number of carbon atoms is 1, the average condensation number is 1 to 4, and when the number of carbon atoms is 2 to 24, the average condensation number is 2 to 100.
Represents According to the present invention, there is also provided a cement composition containing the cement admixture.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The cement admixture of the present invention comprises monomers (a), (b),
(C) and, if necessary, a monomer (d). The monomer (a) is represented by the general formula (1). In this case, X represents O, CH ₂ O or COO. From the viewpoint of hydrolysis resistance, use of an ether type in which X is O or CH ₂ O is preferable. m is the average degree of polymerization of ethylene oxide, and is from 7 to 100, preferably from 7 to 30, from the viewpoint of the dispersion effect of concrete (mixed concrete or cement kneaded material) and the maintenance of fluidity. Examples of the monomer (a) include polyoxyethylene (meth) allyl ether, polyoxyethylene vinyl ether, and polyoxyethylene (meth)
Examples include acrylate, polyoxyethylene methyl (meth) allyl ether, polyoxyethylene methyl vinyl ether, and polyoxyethylene methyl (meth) acrylate. This monomer (a) is a segment that has the effect of dispersing the cement admixture and maintaining fluidity. In the present invention, from the viewpoint of the long-term stability of the cement admixture at high temperatures, polyoxyethylene (meth) allyl ether, polyoxyethylene vinyl ether, or polyoxyethylene methyl (meth) allyl ether, polyoxyethylene methyl vinyl ether is used. It is preferably used.

The monomer (b) is represented by the general formula (2). R4 represents a hydrocarbon group, and includes a chain or cyclic alkyl group. Carbon number is 1-24,
It is preferably 1 to 18 from the viewpoint of the shrinkage reducing effect. R4
Examples of methyl, ethyl, normal-propyl, iso-propyl, normal-butyl, iso-butyl, tert-butyl, hexyl, heptyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl,
Octadecyl, undecyl, cyclohexyl, methylcyclohexyl, cyclooctyl, 2-octyldecyl,
2-nonyldecyl, 2-decyldecyl, 2-octyldodecyl, 2-nonyldodecyl, 2-decyldodecyl, 2
-Decyltetradecyl and the like. Y represents O or CH ₂ O. A is an alkylene oxide group having 2 to 4 carbon atoms, and specific examples include ethylene oxide, propylene oxide, and butylene oxide. They are selected according to the type of R4 from the point of shrinkage reduction effect,
Each is used alone or in combination. n is the average degree of polymerization of the alkylene oxide group, and the range of n is selected from the viewpoint of the effect of reducing the shrinkage, and the optimum number is selected according to the chain length of R4 and the kind of the alkylene oxide group. When R4 is a methyl group having 1 carbon atom, n is 1 to 4, preferably 1 to 3, and when R4 has 2 or more carbon atoms, n is 2 to 100, preferably 3 to 80. When ethylene oxide and propylene oxide are used in combination as alkylene oxide, the mixing ratio is C ₂ H ₄ O / C ₃ H ₆ O in molar ratio.
= 0.25 to 5.0, and preferably 0.3 to 3.0 from the viewpoint of shrinkage reduction effect. Specific examples of the monomer (b) include those having various substituents R4. For example, polyoxyethylene methyl vinyl ether, polyoxypropylene methyl vinyl ether, polyoxyethylene polyoxypropylene methyl vinyl ether, polyoxyethylene methyl ( (Meth) allyl ether, polyoxypropylene methyl (meth) allyl ether, polyoxyethylene polyoxypropylene methyl (meth) allyl ether, polyoxyethylene butyl vinyl ether, polyoxypropylene butyl vinyl ether, polyoxyethylene polyoxypropylene butyl vinyl ether, poly Oxyethylene butyl (meth) allyl ether, polyoxypropylene butyl (meth) allyl ether, polyoxyethylene polyoxypropylene Tyl (meth) allyl ether, polyoxyethylene hexyl vinyl ether, polyoxyethylene polyoxypropylene hexyl vinyl ether, polyoxyethylene hexyl (meth) allyl ether, polyoxyethylene polyoxypropylene hexyl (meth) allyl ether, polyoxyethylene-2 Octyl dodecyl vinyl ether, polyoxyethylene polyoxypropylene-2-octyl dodecyl vinyl ether, polyoxyethylene-2-octyl dodecyl (meth) allyl ether, polyoxyethylene polyoxypropylene-2-octyl dodecyl (meth) allyl ether, etc. No. The monomer (b) is a segment that stably exhibits a concrete shrinkage reducing effect over a long period of time.

Specific examples of the monomer (c) include maleic anhydride, maleic acid, fumaric acid, itaconic acid and the like or alkali metal salts, alkaline earth metal salts, and ammonium salts, amine salts, alkanolamine salts and the like thereof. Organic ammonium salts and the like. These are segments that combine the copolymer of the present invention with cement particles to exhibit a dispersing and water reducing effect.

The monomer (d) is a monomer (a),
A sulfonic acid monomer copolymerizable with (b) and (c), which, together with the monomer (c), participates in binding of the cement admixture to cement and aggregate, and is also negatively charged by a sulfonic acid group. It is a segment that imparts a dispersing effect by electrostatic repulsion to further improve the fluidizing effect of the copolymer of the present invention. Specific examples of the monomer (d) include vinyl sulfonic acid, (meth) allyl sulfonic acid,
-Acrylamide-2-methylpropanesulfonic acid, 2
-Acrylamidoethanesulfonic acid, 2-methacrylamidoethanesulfonic acid, 3-methacrylamidopropanesulfonic acid, styrenesulfonic acid and the like, or alkali metal salts, alkaline earth metal salts, and ammonium salts, amine salts, alkanolamine salts thereof And the like. Preferably, methallylsulfonic acid and 2-acrylamide-
2-methylpropanesulfonic acid, and salts thereof.
In the copolymer of the present invention, the content of the monomer (a) is 5 to 70 mol%, and preferably 20 to 60 mol% from the viewpoint of fluidization effect. The amount of the monomer (b) is 5 to 80 mol%, and preferably 10 to 70 mol% from the viewpoint of the effect of reducing shrinkage. The amount of the monomer (c) is 1 to 50 mol%, preferably 5 to 4 mol% in view of the fluidization effect.
0 mol%. When the monomer (d) is further copolymerized, the ratio to the monomers (a), (b) and (c) is molar ratio (d) / ((a) + (b) + (c)) = 0. 1 /
99.9-40 / 60, preferably 5 / 95-30 / 70 from the viewpoint of fluidization effect. ((A), (b),
(The sum of (c) and (d) is 100 mol%)

The molecular weight of the copolymer of the present invention is 5,000 in terms of average molecular weight in view of the viscosity of the aqueous solution of the admixture and the fluidization effect.
It must be in the range of 0 to 200,000, preferably 10,000 to 150,000.

The copolymer of the present invention can be prepared by using a polymerization initiator to copolymerize the above monomers by a method such as solution polymerization or bulk polymerization. For example, polymerization initiators for radical polymerization include organic peroxides such as di-tert-butyl peroxide, benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, sodium persulfate, ammonium persulfate, and peroxides. Inorganic peroxides such as potassium sulfate, sodium perphosphate and potassium perphosphate are exemplified. Solvents used for solution polymerization include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as normal-hexane and cyclohexane; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane. , Carbon tetrachloride, halogenated hydrocarbons such as chloroform, water and the like. The polymerization conditions are appropriately selected depending on the type of polymerization initiator, the type of monomer, the ratio, the concentration, and the like. Preferred conditions for polymerization rate and fluidity of the product are polymerization temperature of 45 to 180 ° C and polymerization time of 3 to It takes about 10 hours. After completion of the polymerization reaction, when the solvent is distilled off from the reaction mixture or when water is used as the solvent, the copolymer of the present invention can be obtained as it is.

In the copolymerization reaction, an initiator may be added to the mixture of the monomers (a), (b), (c) (and (d)).
The initiator may be added to (b), (c) (and (d)) at a predetermined ratio and mixed. Further, monomers (a),
The copolymer comprising (b) and (c) may be graft-polymerized with the monomer (d), or the monomer (a),
The monomer (b) may be graft-polymerized to the copolymer composed of (c) and (d). In addition, other copolymerizable monomer components such as styrene, acrylonitrile, acrylamide, and acrylate may be added to the monomers (a), (b), (c), and (d) as long as the effects of the present invention are not impaired. , Methacrylate, vinyl acetate,
Maleic acid esters, fumaric acid esters and the like may be copolymerized. The cement admixture of the present invention can be used for all hydraulic cements such as ordinary Portland cement, early-strength Portland cement, moderately heated Portland cement, expanded cement, rapid-hardened cement, blast furnace cement, and alumina cement. In addition, a part of the cement can be replaced with a flysh, a blast furnace slag fine powder, a limestone fine powder, a silica fume or the like.

The amount of the cement admixture of the present invention varies depending on the water-cement ratio and the slump. However, from the viewpoint of the fluidization effect of the cement kneaded material, aggregate separation and setting time, etc., the amount of cement admixture is 0.1 to 0.1%. 5.0% by weight is preferable, and 0.3% is more preferable from the viewpoint of the fluidizing effect and the shrinkage reducing effect.
~ 3.0% by weight. The admixture of the present invention can be used in the form of an aqueous solution or a powder, and the method of use is the same as a normal high-performance water reducing agent or a high-performance AE water reducing agent.
By delaying the addition during the preparation of the cement kneaded material and / or adding it later after the preparation, the shrinkage can be reduced with an excellent fluidizing effect with a smaller addition amount. When used in an aqueous solution, it is desirable to use it by adding it to kneading water instead of cement. In use, the cement admixture of the present invention can be used in combination with other optional components. As such optional components, known cement hardening accelerators of organic amines such as monoethanolamine and triethanolamine, alcohols, saccharides, starch, cellulose, known cement hardening retarders such as glycerin, sodium nitrite, A known reinforcing steel rust inhibitor such as calcium nitrite, and if necessary, a known AE agent, an antifoaming agent, a setting retarder,
Concrete admixtures such as early strength agents, aggregate separation reducing agents, thickeners, water retention agents, waterproofing agents, swelling agents, polymer additives, lignin sulfonate, melamine sulfonate, amino sulfonate, naphthalene sulfonic acid It can be used in combination with formalin condensates, carboxylic acid cement admixtures of various chemical structures, and the like. The method of applying mortar or concrete using the cement admixture of the present invention may be the same as in the conventional case, and may employ methods such as ironing, filling into a mold, spraying, and pouring with a caulking gun. In the case where curing is performed, the method may be any of air-dry curing, wet-air curing, underwater curing, and heat-curing curing (the above-described curing, autoclave curing, etc.), or a combination thereof.

[0013]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. still,
Samples of the copolymer used in the examples were prepared by the following method.

REFERENCE EXAMPLE 1 A polyoxyethylene methyl allyl ether (average number of moles of added ethylene oxide: 7, CH ₂ = CHCH ₂ O) was introduced into a four-neck flask having a capacity of 2000 ml equipped with a reflux condenser, a dropping funnel and a gas inlet tube. _{C 2 H 4 O) 7 CH} 3) 3
80.6 g (1.0 mol), polyoxyethylene methyl allyl ether (average number of moles of ethylene oxide added 2,
_{CH 2 = CHCH 2 O (C} 2 H 4 O) 2 CH 3) 12
8.2 g (0.8 mol), maleic anhydride 19.6 g
(0.2 mol) (polyoxyethylene methyl allyl ether (average addition mole number of ethylene oxide: 7) / polyoxyethylene methyl allyl ether (average addition mole number of ethylene oxide: 2) / maleic anhydride = 50: 40: 10
(Molar ratio)), 300 ml of toluene was charged, the inside of the flask was replaced with nitrogen, and then heated to 80 ° C. A solution of 3.5 g of benzoyl peroxide dissolved in 100 ml of toluene was added dropwise thereto over 5 hours. After completion of the dropping, the mixture was stirred and aged at the same temperature for 3 hours, and then the solvent was distilled off under reduced pressure.
The resulting solids are dissolved in a 20% aqueous solution of caustic soda and p
An aqueous solution of a copolymer having an H7.5 weight average molecular weight of 15,000 (by GPC analysis) was obtained (Copolymer 1).

Reference Example 2 Polymerization was carried out in the same manner as in Reference Example 1 except that the types of monomers and the amounts charged were changed as described below. 248.3 parts by weight of polyoxyethylene methyl methacrylate (average number of moles of ethylene oxide added 9) polyoxyethylene polyoxypropylene butyl allyl ether (average number of moles of added ethylene oxide and propylene oxide is 2) (CH ₂ ＣＨCHCH ₂ O (C _{3 H 6 O) 2 (C} 2 H 4 O) 2 C 4 H 9) 329.1 parts by weight of maleic anhydride 13.1 parts by weight (polyoxyethylene methyl methacrylate / polyoxyethylene profile propylene butyl allyl ether / (Maleic anhydride = 30: 62: 8 (molar ratio)) The weight average molecular weight of the copolymer obtained above was 25,000.
(By GPC analysis) (Copolymer 2).

Reference Example 3 Polymerization was carried out in the same manner as in Reference Example 1, except that the types of monomers and the amounts charged were changed as follows. 190.2 parts by weight of polyoxyethylene methyl allyl ether (average number of moles of ethylene oxide added: 7) Polyoxyethylene polyoxypropylene butyl vinyl ether (CH ₂ ＣＨCHO (C ₃ H ₆ O) ₂ (C ₂ H ₄ O) ₂ C ₄ H ₉ ) 456.6 parts by weight maleic anhydride 24.5 parts by weight 2-acrylamido-2-methylpropanesulfonic acid 48.3 parts by weight (polyoxyethylene methyl allyl ether / polyoxyethylene polyoxypropylene butyl vinyl ether / anhydrous) Maleic acid / 2-acrylamide-2-methylpropanesulfonic acid = 20: 60: 10: 10 (molar ratio)) The weight average molecular weight of the copolymer obtained above was 30,000.
(By GPC analysis) (Copolymer 3).

Reference Example 4 Polymerization was carried out in the same manner as in Reference Example 1, except that the types of monomers and the amounts charged were changed as follows. Polyoxyethylene methyl allyl ether 190.2 parts by weight (average addition mole number of ethylene oxide 7) Polyoxyethylene isopropyl methallyl ether 205.3 parts by weight (average addition mole number of ethylene oxide 3) Maleic anhydride 24.5 parts by weight 2-acrylamide 16.1 parts by weight of 2-methylpropanesulfonic acid (polyoxyethylene methyl allyl ether / polyoxyethylene isopropyl methallyl ether / maleic anhydride / 2-acrylamido-2-methylpropanesulfonic acid = 30: 50: 15: 5 ( Molar ratio)) The weight average molecular weight of the copolymer obtained above is 15,000.
(By GPC analysis) (Copolymer 4).

Comparative Reference Example 1 Polymerization was carried out in the same manner as in Reference Example 1, except that the types of monomers and the amounts charged were changed as follows. Polyoxyethylene methyl allyl ether 380.5 parts by weight (average number of moles of ethylene oxide added: 7) Maleic anhydride 28.0 parts by weight 2-acrylamido-2-methylpropanesulfonic acid 27.6 parts by weight (polyoxyethylene methyl allyl ether / (Maleic anhydride / 2-acrylamide-2-methylpropanesulfonic acid = 70: 20: 10 (molar ratio)) The weight average molecular weight of the copolymer obtained above was 25,000.
(By GPC analysis) (Copolymer 5).

Examples 1 to 4 and Comparative Example 1 The evaluation method of the cement admixture used in Examples and Comparative Examples is as follows. 1) Concrete test The mixture was prepared so as to have a capacity of 30 liters. First, fine aggregate and cement are put into a 50-liter pan-type forced kneading mixer, and after kneading for 60 seconds, coarse aggregate is put in and further mixed for 90 minutes.
Kneaded for seconds. Subsequently, a cement admixture dissolved in a predetermined amount of water was added and kneaded for 3 minutes to prepare a test concrete. After a predetermined time, the mixture taken out of the mixer was measured for slump and air volume according to JISA1101 and JISA1128, respectively. Further, the compressive strength and the drying shrinkage of the concrete after hardening for a predetermined time were measured according to JIS A1108,
The measurement was performed according to JIS A1129 (dial gauge method). Table 1 shows the evaluation results. The water / cement ratio was 50% and the sand / cement ratio was 200%. Curing was carried out one week after curing in water, and further left in an atmosphere at 20 ° C. and a relative humidity of 50% for a predetermined period.

[0020]

[Table 1]

[0021]

The cement admixture of the present invention is a copolymer in which a shrinkage-reducing component is incorporated in the cement admixture molecule. When used for cement, the cement admixture has excellent fluidizing and water-reducing effects as well as shrinkage. The feature is that the reduction effect can be measured efficiently. Further, unlike the conventional case, it is not necessary to use a high-performance water reducing agent or a high-performance AE water reducing agent and a shrinkage reducing agent in combination, so that work efficiency can be improved. Therefore, the cement kneaded material using the cement admixture of the present invention can be used for ordinary concrete, high-strength concrete, and high-fluidity concrete, and can increase the work efficiency and produce high-quality concrete. be able to.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 103: 40

Claims (4)

[Claims] 1. A monomer (a) represented by the following general formula (1): 5 to 70 mol%; a monomer (b) represented by the following general formula (2): 5 to 80 mol%; A cement admixture comprising a copolymer containing 1 to 50 mol% of a polyvalent carboxylic acid or a salt monomer (c) thereof, represented by the following general formula (1): (Wherein, R ₁ , R ₂ : hydrogen or a methyl group X: O, CH ₂ O, or COO m: represents an average condensation number of 7 to 100) General formula (2): (Wherein, R3: hydrogen or a methyl group R4: a hydrocarbon group having 1 to 24 carbon atoms Y: O or CH ₂ O A: an alkylene oxide group having 2 to 4 carbon atoms, used alone or as a mixture n: R4 When the number of carbon atoms is 1, the average condensation number is 1 to 4, and when the number of carbon atoms is 2 to 24, the average condensation number is 2 to 100.
Represents ) 2. The polyalkylene oxide group of the compound represented by the general formula (2) comprises C ₂ H ₅ O and C ₃ H ₆ O, and C ₂ H ₅ O / C ₃ H ₆ O = 0.25 to 0.25. The cement admixture according to claim 1, which is 5.0. 3. A sulfonic acid group-containing monomer (d)
The cement admixture according to claim 1 or 2, comprising a copolymer containing 0.1 to 40 mol%. 4. A cement composition comprising the cement admixture according to any one of claims 1 to 3.