JPH09142905A - Concrete admixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a concrete admixture excellent in dispersibility, the fluidity holding property of concrete or the like by incorporating a water soluble copolymer of a specific monomer and a copolymerizable monomer or its water soluble salt as essential components. SOLUTION: The water soluble copolymer or its water soluble salt is produced by copolymerizing a monomer expressed by the formula (AO is a 2-3C oxyalkylene and (n) is 50-300 in average) and a monomer copolymerizable with the monomer. And the concrete admixture is obtained by incorporating the water soluble copolymer (salt) as an essential component and as necessary, blending additives such as a high performance water reducing agent, a fluidizing agent and a foaming agent. Further, the monomer expressed by the formula is a polyalkylene glycol monoallyl ether and is obtained by addition-reacting ethylene oxide or propylene oxide to an allyl alcohol. And as the copolymerizable monomer, maleic acid, citraconic acid or a monomer obtained by introducing a 2-3C oxyalkylene group to these acids is suitably used.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a concrete admixture. More specifically, the present invention relates to a concrete admixture exhibiting excellent effects on fluidity and fluidity retention of hydraulic compositions such as cement paste, mortar and concrete.

[0002]

2. Description of the Related Art Among concrete admixtures, naphthalene sulfonic acid formaldehyde condensate (hereinafter referred to as naphthalene type) and melamine sulfonic acid formaldehyde condensate are typical concrete admixtures having a great fluidizing effect. (Hereinafter referred to as "melamine-based"), polycarboxylic acid salts (hereinafter referred to as "polycarboxylic acid-based"), and the like are called high-performance water reducing agents.

While these admixtures each have excellent characteristics, they have problems. For example, although naphthalene type and melamine type have excellent curing characteristics, they have a problem in fluidity retention (called slump loss), and polycarboxylic acid type has a problem that curing delay is large.

In recent years, with the development of a polycarboxylic acid system exhibiting excellent fluidity, it becomes possible to obtain dispersibility with a low addition amount, and curing delay is being improved. For example, copolymers of a polyalkylene glycol monoester monomer having an unsaturated bond and an acrylic acid-based and / or unsaturated dicarboxylic acid-based monomer (Japanese Patent Publication No. 59-18338, Japanese Patent Publication No.
78978, Tokuhei 2-7898, Tokuhei 2-7901, Tokuhei 2-
11542, JP-A-3-75252, JP-A-59-162163) and the like.

However, the slump loss has not been solved even in the polycarboxylic acid system having these alkylene chains, and it is the current situation that it is difficult to control the quality from the production of concrete to the transportation and setting.

[0006]

Conventionally, it has been speculated that the excellent dispersion mechanism of a water-soluble vinyl copolymer having an oxyalkylene group is a dispersion mechanism in which the graft structure of the oxyalkylene chain serves as a steric barrier to prevent particle adhesion. There is.

As a result of various studies on the relationship between the chain length of the oxyalkylene group and the functional group serving as an adsorption point on cement, the inventors have found that the dispersibility, slump retention and curing retardation are excellent. We have completed an improved water-soluble vinyl copolymer with the structure shown.

That is, the present invention provides a water-soluble copolymer of a monomer (a) represented by the following general formula (A) and a copolymerizable monomer (b) or a water-soluble salt thereof. It is a concrete admixture contained as the main component.

[0009]

Embedded image

(In the formula, AO: an oxyalkylene group having 2 to 3 carbon atoms, n: an average number of 50 to 300).

The concrete admixture of the present invention has an average number of added oxyalkylene groups in the general formula (A) of 50.
The long chain alkylene oxide chain serves as a steric barrier to enhance the dispersibility and is excellent in maintaining the fluidity over time. Further, in the range of 110 to 300 mol on average, the fluidity and the fluid retention are extremely excellent. When n is less than 50 moles or exceeds 300 moles, the dispersibility tends to decrease, which is not preferable.

Incidentally, in JP-A-57-118058, the number of added moles n of oxyalkylene group in the general formula (A) is 1
Compounds in the range of up to 100 mol are disclosed, but specific description is found only for compounds having n of 30 or less. No retentivity is obtained and no effect on the chain length of the oxyalkylene group is described.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the monomer (a) represented by the general formula (A) is polyalkylene glycol monoallyl ether, which is an alkylene oxide having 2 to 3 carbon atoms into allyl alcohol, That is, they are ethylene oxide and propylene oxide adducts, and both adducts of ethylene oxide and propylene oxide can be used in any of random addition, block addition and alternating addition.

In the present invention, the monomer (b) copolymerizable with the monomer (a) may be a compound represented by the following general formula (B). Examples thereof include maleic acid, fumaric acid, citraconic acid, mesaconic acid, water-soluble salts thereof, and monomers in which an oxyalkylene group having 2 to 3 carbon atoms is introduced. Of these, maleic acid, citraconic acid, monomers in which an oxyalkylene group having 2 to 3 carbon atoms is introduced, and water-soluble salts thereof are preferable because of excellent copolymerizability and dispersibility.

[0015]

Embedded image

(Wherein R ₁ and R _{2 are} hydrogen or a methyl group X, Y: (MO) _m R ₃ , provided that either one of X and Y is hydrogen, MO is an oxy group having 2 to 3 carbon atoms. Alkylene group m: a number of 0 to 300 R ₃ : hydrogen or an alkyl or alkenyl group having 1 to 5 carbon atoms).

Further, as the copolymerizable monomer, maleic acid, fumaric acid, citraconic acid, a diester obtained from mesaconic acid and an alcohol, a primary alcohol having 1 to 20 carbon atoms and (meth) acrylic acid are obtained. (Meth) acrylic acid ester, (meth) acrylamide, vinyl acetate, propenyl acetate, styrene, aromatic vinyl compounds such as p-methylstyrene, vinyl chloride and the like can be mentioned, and it is possible to use one or more of these. it can.

As the water-soluble salt, an alkali metal salt, an alkaline earth metal salt, an ammonium salt, an amine salt or the like is used.

In the copolymer of the present invention, the copolymerization composition ratio of the monomer (a) component and the monomer (b) component constituting the copolymer is monomer (a) / monomer amount. Body (b) = 1/99 ~
90/10 range has excellent fluidity and flow retention, 10 / 90-60
The / 40 range is better.

Further, the copolymer of the present invention has excellent fluidity in the range of 1,000 to 500,000 (gel permeation chromatography method (water system) / sodium polystyrene sulfonate conversion) in terms of molecular weight, and in the range of 5,000 to 50,000. More preferable.

The copolymer of the present invention can be produced by a known method. For example, JP-A-57-11805
No. 8, JP 59-162163, JP-B 2-11542, JP-B
Solvent polymerization methods such as 2-7901 and Japanese Patent Publication No. 2-7897 are mentioned.

The solvent used in the solvent polymerization is water,
Methyl alcohol, ethyl alcohol, isopropyl alcohol, benzene, toluene, xylene, cyclohexane, n-hexane, aliphatic hydrocarbons, ethyl acetate, acetone, methyl ethyl ketone and the like can be mentioned. Water and primary to quaternary alcohols are preferable in consideration of handling and reaction equipment.

As the water-based polymerization initiator, a water-soluble initiator such as ammonium or alkali metal persulfate or hydrogen peroxide is used. Benzoyl peroxide, lauroyl peroxide or the like is used as a polymerization initiator in solvent polymerization using a solvent other than an aqueous solvent.

It is also possible to use sodium bisulfite, mercaptoethanol, or an amine compound as an accelerator in combination with the polymerization initiator, and these polymerization initiators or accelerators can be appropriately selected and used.

The amount of the concrete admixture of the present invention added to concrete is preferably 0.02 to 1.0% by weight and more preferably 0.05 to 0.5% by weight based on the solid content of cement.

The concrete admixture of the present invention can be used in combination with known additives (materials). For example, AE
Agent, AE water reducing agent, superplasticizer, high performance water reducing agent, retarder, early strengthening agent, accelerator, foaming agent, foaming agent, defoaming agent, thickener, waterproofing agent, antifoaming agent, silica sand, blast furnace Examples include slag, fly ash and silica fume.

Further, the concrete admixture of the present invention is to be added to cement paste, mortar, concrete, etc. having a composition of hydraulic cement, and the content thereof is not limited.

[0028]

EXAMPLES Hereinafter, the present invention will be described specifically, but the present invention is not limited to these examples.

The contents and symbols of the monomer (a) used in the polymerization of the present invention are shown below. However, EO is ethylene oxide,
PO represents propylene oxide, and the number represents the average number of added moles.

A-1: Allyl alcohol EO adduct (EO average addition mole number = 60) A-2: Allyl alcohol EO adduct (EO average addition mole number = 120) A-3: Allyl alcohol EO adduct (EO Average addition mole number = 150) A-4: Allyl alcohol EO adduct (EO average addition mole number = 220) A-5: Allyl alcohol EO adduct (EO average addition mole number = 270) A-6: Allyl alcohol EO -PO block adduct (EO average added mole number = 120, PO average added mole number = 20) A-7: Allyl alcohol EO / PO random adduct (EO average added mole number = 120, PO average added mole number = 20) ) A-8 (comparison): allyl alcohol EO adduct (EO average addition mole number = 30) A-9 (comparison): allyl alcohol EO adduct (EO average addition mole number = 350) Here is an example:

Production Example 1 (symbol C-1 of admixture) 10 mol of water was charged into a reaction vessel equipped with a stirrer, nitrogen substitution was carried out with stirring, and the temperature was raised to 95 ° C in a nitrogen atmosphere. A-1
0.1 mol, O, 4 mol of maleic acid (molar ratio = 20/80), a mixture of 10 mol of water and 0.1 mol of a 20% ammonium persulfate aqueous solution are simultaneously added dropwise to the reaction system over 2 hours.
Next, 0.1 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, followed by aging at the same temperature (95 ° C) for 1 hour. After completion of the aging, 1.5 mol of 48% sodium hydroxide was added to neutralize and obtain a copolymer having a molecular weight of 12,000.

Production Example 2 (symbol C-2 of admixture) 15 mol of water was charged into a reaction vessel equipped with a stirrer, nitrogen substitution was carried out with stirring, and the temperature was raised to 95 ° C. in a nitrogen atmosphere. A-2
0.1 mol, monosodium maleate O, 4 mol (molar ratio = 20/80), dissolved and mixed with 15 mol of water and 0.1 mol of 20% ammonium persulfate aqueous solution are simultaneously added dropwise to the reaction system over 2 hours. Next, 20% ammonium persulfate aqueous solution 0.1
Mole is added dropwise over 30 minutes and aged at the same temperature (95 ° C) for 1 hour. After aging, a copolymer having a molecular weight of 24,000 was obtained.

Production Example 3 (symbol C-3 of admixture) 15 mol of water was charged into a reaction vessel equipped with a stirrer, nitrogen substitution was carried out with stirring, and the temperature was raised to 95 ° C in a nitrogen atmosphere. A-3
20% with 0.05 mol, EO adduct of maleic acid (EO = 3 mol) 0.45 mol (molar ratio = 10/90), 15 mol of water mixed and dissolved
Simultaneously add 0.1 mol of ammonium persulfate aqueous solution to the reaction system.
Drip over time. Next, 0.1 mol of 20% ammonium persulfate aqueous solution was added dropwise over 30 minutes, and the temperature was kept at the same temperature (95 ° C) for 1 hour.
And mature. After completion of the aging, 0.6 mol of 48% sodium hydroxide was added for neutralization to obtain a copolymer having a molecular weight of 32,000.

Production Example 4 (symbol C-4 of admixture) 20 mol of water was charged into a reaction vessel equipped with a stirrer, and the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 95 ° C in a nitrogen atmosphere. A-4
A mixture of 0.03 mol of maleic acid monomethyl ester (0.47 mol) (molar ratio = 6/94) and 20 mol of water and 0.1 mol of 20% ammonium persulfate aqueous solution are simultaneously added dropwise to the reaction system over 2 hours. Next, a 20% ammonium persulfate aqueous solution
0.1 mol is added dropwise over 30 minutes, and the mixture is aged at the same temperature (95 ° C) for 1 hour. After completion of aging, 0.6 mol of 48% sodium hydroxide was added for neutralization to obtain a copolymer having a molecular weight of 47,000.

Production Example 5 (symbol C-5 as an admixture) 20 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 95 ° C in a nitrogen atmosphere. A-5
0.03 mol, 0.47 mol of maleic acid monomethyl ester (molar ratio = 6/94) mixed and dissolved in 20 mol of water, and 0.1 mol of 20% ammonium persulfate aqueous solution are simultaneously added dropwise to the reaction system over 2 hours. Next, a 20% ammonium persulfate aqueous solution
0.1 mol is added dropwise over 30 minutes, and the mixture is aged at the same temperature (95 ° C) for 1 hour. After completion of aging, 0.6 mol of 48% sodium hydroxide was added for neutralization to obtain a copolymer having a molecular weight of 47,000.

Production Example 6 (symbol C-6 as an admixture) 15 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 95 ° C in a nitrogen atmosphere. A-6
0.15 mol, O, 35 mol of maleic acid (molar ratio = 30/70), a mixture of 15 mol of water and 0.1 mol of a 20% ammonium persulfate aqueous solution are simultaneously added dropwise to the reaction system over 2 hours.
Next, 0.1 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, followed by aging at the same temperature (95 ° C) for 1 hour. After completion of the aging, 1.5 mol of 48% sodium hydroxide was added to neutralize and a copolymer having a molecular weight of 35,000 was obtained.

Production Example 7 (symbol C-7 as an admixture) 15 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 95 ° C in a nitrogen atmosphere. A-7
0.10 mol, O, 40 mol of maleic acid (molar ratio = 20/80), dissolved and mixed with 15 mol of water, and 0.1 mol of 20% ammonium persulfate aqueous solution are simultaneously added dropwise to the reaction system over 2 hours.
Next, 0.1 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, followed by aging at the same temperature (95 ° C) for 1 hour. After completion of the aging, 1.5 mol of 48% sodium hydroxide was added to neutralize and obtain a copolymer having a molecular weight of 33,000.

Production Example 8 (symbol C-8 as an admixture) 5 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 95 ° C in a nitrogen atmosphere. A-8
0.50 mol, 2.00 mol of maleic acid (molar ratio = 20/80), 5 mol of water mixed and dissolved, and 0.1 mol of 20% ammonium persulfate aqueous solution were simultaneously added dropwise to the reaction system over 2 hours.
Next, 0.1 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, followed by aging at the same temperature (95 ° C) for 1 hour. After completion of the aging, 1.5 mol of 48% sodium hydroxide was added to neutralize the mixture to obtain a copolymer having a molecular weight of 26,000.

Production Example 9 (symbol C-9 as an admixture) 20 mol of water was charged into a reaction vessel equipped with a stirrer, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 95 ° C in a nitrogen atmosphere. A-9
A mixture of 0.02 mol, O, 18 mol of maleic acid (molar ratio = 10/90) and 20 mol of water and 0.1 mol of a 20% ammonium persulfate aqueous solution were simultaneously added dropwise to the reaction system over 2 hours.
Next, 0.1 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, followed by aging at the same temperature (95 ° C) for 1 hour. After completion of the aging, 1.5 mol of 48% sodium hydroxide was added to neutralize and a copolymer having a molecular weight of 45,000 was obtained.

The contents and symbols of the comparative admixtures used in the examples are shown below in addition to the comparative polymer of the copolymer. Admixture symbol NS: naphthalene-based admixture (Mighty 150
; Kao Co., Ltd. Admixture symbol MS: Melamine admixture (Mighty 150-V
2; manufactured by Kao Corporation.

The concrete evaluation methods for the copolymer of the present invention, the comparative polymer and the comparative admixture obtained in the above production examples are shown below.

<Evaluation as Concrete Admixture> The mixing conditions of concrete are shown in Table 1.

[0043]

[Table 1]

The concrete was prepared by mixing the materials and admixtures in a tilting mixer at 25
The mixture was adjusted by kneading at pm × 3 minutes. Liquidity (slump value)
After the measurement, was further rotated at 4 rpm for 60 minutes, and the slump value (cm) up to 90 minutes and the setting time of concrete were measured. The slump value was measured according to JIS A 1101 and the setting time was measured according to ASTM C403. Further, the initial slump value was adjusted by the addition amount of the present invention and the comparative admixture so as to be 20 ± 1 cm. Table 2 shows the measurement results.

[0045]

[Table 2]

<Evaluation Results> As is clear from Table 2, the concrete admixture of the present invention is superior in fluidity as compared with the comparative product, and the slump is less deteriorated.

[0047]

When the concrete admixture of the present invention is added to the cement composition, the quality control of the concrete becomes easy because the slump does not change over a long period of time.
Furthermore, since there is little delay in setting, troubles in construction time can be improved and the construction period can be shortened.

Claims (5)

[Claims] 1. A water-soluble copolymer of a monomer (a) represented by the following general formula (A) and a copolymerizable monomer (b) or a water-soluble salt thereof is contained as a main component. A concrete admixture. Embedded image (In the formula, AO: an oxyalkylene group having 2 to 3 carbon atoms n: represents an average number of 50 to 300) 2. The average n in the general formula (A) is 110 to 300.
2. The concrete admixture according to claim 1, wherein 3. The concrete admixture according to claim 1 or 2, wherein the copolymerizable monomer is a compound represented by the following general formula (B). Embedded image (In the formula, R ₁ and R ₂ : hydrogen or a methyl group X, Y: (MO) _m R ₃ , provided that either X or Y is hydrogen MO: an oxyalkylene group having 2 to 3 carbon atoms m : A number of 0 to 300 R ₃ : hydrogen or an alkyl or alkenyl group having 1 to 5 carbon atoms) 4. The copolymerization composition ratio of the monomer (a) component and the monomer (b) component constituting the copolymer is monomer (a) /
Monomer (b) = 1/99 to 90/10, Concrete admixture according to any one of claims 1 to 3, characterized in that 5. The concrete admixture according to any one of claims 1 to 4, wherein the copolymer has a molecular weight of 1,000 to 500,000.