JPH06298557A - Concrete admixture - Google Patents

Abstract

PURPOSE:To improve fluidity, fluidity retention, foaming properties and foaming retention and to facilitate quality control, comprising a copolymer prepared by polymerizing specific three kinds of compounds. CONSTITUTION:(A) A monomer of formula I (R1-2 are H or methyl; m1 is 0-2; n1 is 1-100; x1 is H or 1-3C alkyl; x1 is H or 1-3C alkyl) having 1-100 ethylene oxide addition mols on the average is polymerized with (B) a monomer of formula II (R3-4 is H or methyl; m2 is 0-2; n2 is 1-50; x2 is H or 1-3C alkyl) having 1-50 propylene oxide addition mols on the average and (C) an acrylic acid-based or unsaturated dicarboxylic acid-based monomer of formula III [R5 is H or methyl; R6-7 is (CH2)m3COOM4, H or methyl; m3 is 0-2; M3-4 are H, monovalent metal ammonium, amino or substituted amino] in the ratio of (A)/(B)/(C)=10-90/1-30/10-90 with water in a nitrogen atmosphere at pH9 at about 60 deg.C to give a copolymer having 1,000-1,000,000 weight-average molecular weight.

Description

Detailed Description of the Invention

[0001]

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

[0002]

BACKGROUND OF THE INVENTION Among concrete admixtures, naphthalene sulfonate formaldehyde condensate (hereinafter referred to as naphthalene type) and melamine sulfonate formaldehyde are typical examples of concrete admixture having a great fluidizing effect. There are substances called high performance water reducing agents such as condensates (hereinafter referred to as melamine-based) and polycarboxylic acid salts (hereinafter referred to as polycarboxylic acid-based).

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

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-based 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. 2-78978). No., Japanese Patent Publication No. 2-7898, Japanese Patent Publication No. 2-7901,
JP-B-2-11542, JP-A-3-75252, JP-A-59-
Water-soluble vinyl copolymers such as No. 162163).

However, the polycarboxylic acid system having these alkylene chains has a high entrainment property of bubbles, and the fluctuation due to the increase of the air amount during the period from concrete production to transportation is extremely large. 4 together
The current situation is that it is difficult to manage (about%). These problems are addressed by blending defoaming agents, etc.
The amount of air greatly varies depending on the mixing conditions, the agitator conditions of the mixer truck, and the transportation time, and the addition of the defoaming agent has not reached the basic solution, and improvement of the admixture itself is desired.

More specifically, it has been speculated that the excellent dispersion mechanism of a water-soluble vinyl copolymer having an oxyalkylene group is conventionally a dispersion mechanism in which the graft structure of the oxyalkylene chain serves as a steric barrier to prevent particle adhesion. As the oxyalkylene group, ethylene oxide, propylene oxide, butylene oxide and the like are mentioned in a known patent (the above-mentioned copolymer patent). However, no mention is made of the bond form of these oxyalkylene chains and the copolymer form of the water-soluble vinyl copolymer, and the present situation is that the above-mentioned problems are held.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to improve the above-mentioned problems. As a result, the bonding form or copolymerization form of the alkylene glycol chain of the polyalkylene glycol monoester monomer is a bubble. It has been found that it affects the properties and bubble retention. Specifically, in the polyalkylene glycol monoester-based monomer, by copolymerizing the block or random adducts of ethylene oxide and propylene oxide as the starting materials, respectively, extremely stable bubble retention is achieved. It was found that sex is expressed.

That is, the present invention has the following general formula (A):
The present invention relates to a concrete admixture containing a copolymer obtained by polymerizing three kinds of compounds represented by (B) and (C) as an essential component.

[0009]

[Chemical 2]

(Wherein R _{1 to} R _{5 are} hydrogen or a methyl group R ₆ , R ₇ : (CH ₂ ) _{m 3} COOM ₄ , hydrogen or a methyl group m _{1 to} m ₃ are integers 0 to 2 n ₁ : 1 100 integer n _2: an integer X ₁ of 1 to 50, X _2: hydrogen or an alkyl group having 1 to 3 carbon atoms M _3, M _4: hydrogen, a monovalent metal, an ammonium group, an amino group or a substituted amino group In the present invention, the compound represented by the general formula (A) (hereinafter referred to as a monomer (A)) is a polyethylene glycol monoester such as polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, etc. The numbers are 1-100 on average. Since the reactivity decreases as the number of moles of ethylene oxide added increases, polyethylene glycol monoesters having a number of moles of addition of 100 or less are preferred.

In the present invention, the compound represented by the general formula (B) (hereinafter referred to as the monomer (B)) is a polypropylene glycol monoester such as polypropylene glycol monoacrylate or polypropylene glycol monomethacrylate, and a propylene oxide addition mole. The number is 1 to 50 on average. Since the water solubility decreases as the number of moles of propylene oxide added increases, polypropylene glycol monoesters having a number of moles of addition of 50 or less are preferred.

The compound represented by the general formula (C) (hereinafter referred to as the monomer (C)) used in the present invention includes an acrylic acid type monomer and an unsaturated dicarboxylic acid type monomer. Examples of acrylic acid-based monomers include acrylic acid, methacrylic acid, crotonic acid, and metal salts thereof. As the unsaturated dicarboxylic acid type monomer, maleic anhydride,
Examples thereof include maleic acid, itaconic anhydride, itaconic acid, citraconic anhydride, citraconic acid, fumaric acid, or metal salts, ammonium salts, amine salts or the like thereof.

The monomer (A) in the copolymer of the present invention,
The ratio (% by weight) of (B) and (C) is (A) / (B) /
The range of (C) = 10 to 90/1 to 30/10 to 90 is suitable for bubble stability, and more preferably (A) / (B) / (C).
= 40 to 60/1 to 20/40 to 60 is preferable.

The weight average molecular weight (gel permeation chromatography method / polystyrene sulfonic acid conversion) of the copolymer of the present invention is preferably in the range of 1,000 to 1,000,000, and 5,000 to
The range of 500,000 is more preferable. When the weight average molecular weight is 5,000 or less, dispersibility is insufficient. Further, if it is 1,000,000 or more, cohesiveness becomes remarkable, which is not preferable.

The polymer of the present invention can be produced by a known method. For example, JP-A-59-162163, Japanese Patent Publication No. 2-11542, Japanese Patent Publication No. 2-7901, and Japanese Patent Publication No. 2-7897.
No. and the like.

The amount of the concrete admixture of the present invention added to concrete is 0.02-1.
0% by weight is preferable, and 0.05 to 0.5% by weight is more preferable.

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 its contents are not limited.

[0019]

EXAMPLES The present invention will be specifically described below, but the present invention is not limited to these examples. In addition,% in the following examples is% by weight.

The contents and symbols of the monomer (A) used in the polymerization of the present invention are shown below. A-1 Polyethylene glycol monoacrylate (ethylene oxide addition mole number = 3.4) A-2 Polyethylene glycol monoacrylate (ethylene oxide addition mole number = 9.1) A-3 Polyethylene glycol monomethacrylate (ethylene oxide addition mole number = 23.2) A-4 Polyethylene glycol monomethacrylate (ethylene oxide addition mole number = 85.5).

The contents and symbols of the monomer (B) used in the polymerization of the present invention are shown below. B-1 Polypropylene glycol monoacrylate (Propylene oxide addition mole number = 2.2) B-2 Polypropylene glycol monoacrylate (Propylene oxide addition mole number = 9.4) B-3 Polypropylene glycol monomethacrylate (Propylene oxide addition mole number = 18.5) B- 4 Polypropylene glycol monomethacrylate (the number of moles of propylene oxide added = 40.2).

The contents and symbols of the polyethylene oxide and polypropylene oxide adduct monomers used as comparative examples are shown below. C-1 Polyethylene / polypropylene glycol monoacrylate (random addition product of ethylene oxide addition mole number = 5.6 and propylene oxide addition mole number = 3.2).

The production examples of the copolymer are shown below. Production Example 1 (symbol AB-1 in the example) 150 parts by weight 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 60 ° C in a nitrogen atmosphere. A-
1 part (25 parts), B-1 (5 parts) and sodium methacrylate (70 parts) were charged and the pH was adjusted to 9 with a 30% aqueous sodium hydroxide solution. After purging with nitrogen, 10 parts of 25% ammonium persulfate aqueous solution is added to start polymerization. After reacting for 8 hours and completing the polymerization, 30
% Neutralized with 2% sodium hydroxide aqueous solution, molecular weight 2400
A copolymer of 0 was obtained.

Production Example 2 (Symbol AB-2 in Example) 150 parts by weight 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 60 ° C. in a nitrogen atmosphere. A-
45 parts of 2, 2, 5 parts of B-2 and 50 parts of sodium methacrylate were charged, and the pH was adjusted to 9 with a 30% aqueous sodium hydroxide solution. After purging with nitrogen, 11 parts of a 25% ammonium persulfate aqueous solution is added to start polymerization. After reacting for 7 hours and completing the polymerization, 30
% Neutralized with aqueous sodium hydroxide solution, molecular weight 1800
A copolymer of 0 was obtained.

Production Example 3 (Symbol AB-3 in the Example) 130 parts by weight 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 60 ° C in a nitrogen atmosphere. A-
60 parts of 3, 3 parts of B-3 and 30 parts of sodium acrylate were charged, and the pH was adjusted to 9 with a 30% aqueous sodium hydroxide solution. After purging with nitrogen, 12 parts of 25% ammonium persulfate aqueous solution is added to start polymerization. After reacting for 5 hours and completing the polymerization, 30
% Neutralized with aqueous sodium hydroxide solution, molecular weight 1100
A copolymer of 0 was obtained.

Production Example 4 (Symbol AB-4 in Example) 130 parts by weight 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 60 ° C in a nitrogen atmosphere. A-
45 parts of 4, 4, 5 parts of B-3 and 50 parts of sodium acrylate were charged, and the pH was adjusted to 9 with a 30% aqueous sodium hydroxide solution. After purging with nitrogen, 10 parts of 25% ammonium persulfate aqueous solution is added to start polymerization. After reacting for 5 hours and completing the polymerization, 30
% Completely neutralized with 2% sodium hydroxide aqueous solution, molecular weight 2100
A copolymer of 0 was obtained.

Production Example 5 (Symbol AB-5 in Example) 120 parts by weight 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 60 ° C. in a nitrogen atmosphere. A-
45 parts of 3, B-1 of 5 parts and sodium methacrylate of 50 parts were charged, and the pH was adjusted to 9 with a 30% aqueous sodium hydroxide solution. After purging with nitrogen, 10 parts of 25% ammonium persulfate aqueous solution is added to start polymerization. After reacting for 6 hours and completing the polymerization, 30
% Neutralized with aqueous sodium hydroxide solution, molecular weight 1800
A copolymer of 0 was obtained.

Production Example 6 (Symbol AB-6 in Example) 130 parts by weight 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 60 ° C. in a nitrogen atmosphere. A-
45 parts of 2, 2, 5 parts of B-1 and 50 parts of sodium methacrylate were charged, and the pH was adjusted to 9 with a 30% aqueous sodium hydroxide solution. After purging with nitrogen, 11 parts of a 25% ammonium persulfate aqueous solution is added to start polymerization. After reacting for 5 hours and completing the polymerization, 30
% Neutralized with 2% sodium hydroxide aqueous solution, molecular weight 2400
A copolymer of 0 was obtained.

Production Example 7 (symbol AB-7 in the example (comparison
Example)) 130 parts by weight 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 60 ° C in a nitrogen atmosphere. A-
50 parts of 3 and 50 parts of sodium acrylate were charged and the pH was adjusted to 9 with a 30% aqueous sodium hydroxide solution. After nitrogen replacement,
Polymerization is started by adding 10 parts of 25% ammonium persulfate aqueous solution. After reacting for 5 hours and completing the polymerization, the mixture was completely neutralized with a 30% aqueous sodium hydroxide solution to obtain a copolymer having a molecular weight of 17,000.

Production Example 8 (symbol AB-8 of the example (comparative
Example)) 130 parts by weight 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 60 ° C in a nitrogen atmosphere. C-
40 parts of 1 and 60 parts of sodium methacrylate were charged, 30%
The pH was adjusted to 9 with an aqueous sodium hydroxide solution. After purging with nitrogen, 10 parts of 25% ammonium persulfate aqueous solution is added to start polymerization. After reacting for 6 hours and completing the polymerization, the mixture was completely neutralized with a 30% aqueous sodium hydroxide solution to obtain a copolymer having a molecular weight of 22000.

The contents and symbols of the comparative admixtures used in the examples other than the comparative polymer of the copolymer are shown below.

Reference symbol NS: Naphthalene-based admixture (Mighty 150; manufactured by Kao Corporation) Reference symbol MS: Melamine-based admixture (Mighty 150V-
2; Mixing conditions of evaluation concrete as a concrete admixture manufactured by Kao Corporation are shown in Table 1.

[0033]

[Table 1]

The concrete was evaluated by mixing the materials and admixtures in a tilting mixer at 25 rpm with the concrete composition shown in Table 1.
× It kneaded for 3 minutes and adjusted. After measuring the air amount and the fluidity (slump value), it was further rotated at 4 rpm for 60 minutes, and after 60 minutes, the air amount and the slump value were measured. After adjusting the concrete, the amount of air was adjusted to 4 ± 0.5% with an air bubble entraining agent (Vinsol: manufactured by Yamasou Chemical Co., Ltd.). Slump value is JIS-
It was measured by the A 1101 method. Also, the initial slump value is 20 ±
The amount of the present invention and the comparative admixture was adjusted to 1 cm. The measurement results are shown in Table 2.

[0035]

[Table 2]

Evaluation Results As is clear from Table 2, the admixture of the present invention has a remarkable air bubble retention property as compared with the comparative product. Moreover, it has excellent fluidity,
The slump exhibits excellent effects with little change over time.

[0037]

When the concrete admixture according to the present invention is added to the concrete composition, the quality control of the concrete becomes easy because the change of the air amount and the fluidity is small over a long period of time.

Claims (1)

[Claims] 1. A concrete admixture containing as an essential component a copolymer obtained by polymerizing three kinds of compounds represented by the following general formulas (A), (B) and (C). [Chemical 1] (In the formula, R _{1 to} R _{5 are} hydrogen or a methyl group R ₆ , R ₇ : (CH ₂ ) _m3 COOM ₄ , hydrogen or a methyl group m _{1 to} m ₃ are integers 0 to 2 of n ₁ : 1 to 100 Integer n ₂ : integers _{1 to} 50: X ₁ and X ₂ : hydrogen or an alkyl group having 1 to 3 carbon atoms M ₃ , M ₄ : hydrogen, a monovalent metal, an ammonium group, an amino group or a substituted amino group.)