JPH06321596A - Concrete admixture - Google Patents

Abstract

PURPOSE:To provide a concrete admixture facilitating the quality control of concrete with small variations in the air quantity and fluidity of concrete for a long time, containing, as the essential ingredient, a copolymer prepared by copolymerization between a specific polyethylene-polypropylene glycol monoester (of formula A or B) and an acrylic acid monomer or unsaturated dicarboxylic acid monomer (of formula C). CONSTITUTION:The objective concrete admixture containing, as the essential ingredient, a copolymer prepared by copolymerization between (1) a compound of formula A (symbols in the formula are common with those in formulas B and C; R1-R5 are each H or methyl; R6 and R7 are each (CH2)m3COOM2, H or methyl; m1-m3 are each 0-2; n1 and n4 are each 1-10; n2 and n3 are each 4-50; X1 and X2 are each H or 1-3C alkyl; M1 and M2 are each H, monovalent metal, NH4, NH2 or substituted amino group) or formula B and (2) a compound of formula C at a weight ratio of (10-99): (90-1) (this proportion is suitable for the foam stability of the resultant concrete.). The weight-average molecular weight of this copolymer is preferably 1000-1000000. The amount of the admixture to be added to concrete is preferably 0.02-1.0wt.%, on a solid basis, based on cement.

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]

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 known as high-performance water reducing agents.

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 listed according to known patents (the aforementioned copolymer patents). However, no mention is made of the bonding form of these oxyalkylene chains, and the present situation still has the above-mentioned problems.

[0007]

Means for Solving the Problems As a result of intensive research to improve the above-mentioned problems, the present inventors have found that the bonding form and copolymerization form of the alkylene glycol chain of the polyalkylene glycol monoester monomer are It was found that it affects the foamability and bubble retention. Specifically, in the polyalkylene glycol monoester-based monomer, propylene oxide was added to the root of the ester or the terminal of ethylene oxide rather than the copolymer using a random addition product of ethylene oxide or propylene oxide. By polymerizing acrylic acid monomer and unsaturated dicarboxylic acid monomer, etc. using an ester, this polymer exhibits high fluidity with a low addition amount and exhibits extremely stable bubble retention. Found.

That is, the present invention comprises a copolymer obtained by polymerizing a compound represented by the following general formula (A) or (B) and a compound represented by the following general formula (C) as an essential component. And concrete admixtures.

[0009]

[Chemical 2]

(Wherein R _{1 to} R _{5 are} hydrogen or a methyl group R ₆ , R ₇ : (CH ₂ ) _{m 3} COOM ₂ , hydrogen or a methyl group m _{1 to} m ₃ are integers n ₁ and n of 0 to ₂ ) ₄ : integers 1 to 10 n ₂ , n ₃ : integers _{4 to} 50 X ₁ , X ₂ : hydrogen or an alkyl group having 1 to 3 carbon atoms M ₁ , M ₂ : hydrogen, monovalent metal, ammonium group, amino Group or a substituted amino group.) Generally, it is known that addition of propylene oxide (hereinafter referred to as PO) causes foam-breaking property and defoaming property. However, in order to keep the amount of bubbles in the concrete constant as in the object of the present invention, it is necessary to balance the bubble property and the defoaming property. Therefore, if either is too strong, the desired effect cannot be obtained. The admixture of the present invention takes into account the hydrophilic / hydrophobic balance and the interfacial orientation with respect to the retention of bubbles, so that 1 to 10 mol of PO is added to the root of the ester or the end of ethylene oxide (hereinafter referred to as EO). It exhibits bubble stability in a particularly limited region.

That is, random addition of EO / PO, or EO / PO
Alternatively, in the PO / EO block addition, if the number of moles of PO added exceeds 10, the bubble retention cannot be satisfied.

In the present invention, the compound represented by the general formula (A) (hereinafter referred to as the monomer (A)) is obtained by adding 1 to 10 mol of PO to the base of acrylic acid or methacrylic acid, and further adding EO.
Is added in an amount of 4 to 50 mol. Also, the carbon number is 1 to 3.
After the addition of 4 to 50 mol of EO to the lower alcohol of 1, the esterification of the alcohol with acrylic acid or methacrylic acid to which 1 to 10 mol of PO was further added, the monomer (A ) Is obtained.

In the present invention, the compound represented by the general formula (B) (hereinafter referred to as the monomer (B)) is a compound in which PO is added to the terminal of acrylic acid or methacrylic acid. After adding 4 to 50 mol of EO to the acid, 1 to 10 mol of PO was further added. Also, carbon number 1
After adding 1 to 10 mol of PO to the lower alcohol of 3 to 3,
Furthermore, by esterifying the alcohol added with 4 to 50 mol of EO with acrylic acid or methacrylic acid,
A monomer (B) having PO added is obtained.

The number of moles of PO added to the monomers (A) and (B) is 10
If it exceeds the range, the defoaming property becomes large, which is not preferable. If the number of moles of EO added is less than 4, the dispersibility is reduced, and if it exceeds 50, the reactivity is reduced, which is not preferable.

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. or,
Examples of unsaturated dicarboxylic acid-based monomers include maleic anhydride, maleic acid, itaconic anhydride, itaconic acid, citraconic anhydride, citraconic acid, fumaric acid, or metal salts thereof, ammonium salts, amine salts and the like. .

The proportion (% by weight) of the monomers (A) or (B) and (C) in the copolymer of the present invention is (A) or (B) :( C) = 10 to 99:90. The range of 1 to 1 is suitable for bubble stability, and more preferably (A) or (B):
(C) The range of 40 to 99:60 to 1 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.
00 to 500,000 is more preferable. If the weight average molecular weight is less than 1,000, the dispersibility is insufficient. Further, if it exceeds 1,000,000, the 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.

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

[0022]

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

The number of moles of PO and EO added to the monomers (A) and (B) is shown by the average number of moles.

The contents and symbols of the monomer (A) used in the polymerization of the present invention are shown below. A-1 Acrylic acid PO 2 mol / EO 6 mol adduct A-2 EO / PO adduct Methanol and methacrylic acid monoester (EO = 9.3 / PO = 1.2) A-3 EO / PO adduct Methanol and acrylic acid Monoester (EO = 23.2 / PO = 3.2) A-4 EO / PO addition Monoester of methanol and methacrylic acid (EO = 45.5 / PO = 8.5).

The contents and symbols of the monomer (B) used in the polymerization of the present invention are shown below. B-1 Methacrylic acid 9 mol / EO 1.5 mol adduct B-2 PO / EO adduct Methanol / methacrylic acid monoester (PO = 2.4 / EO = 15.3) B-3 PO / EO adduct Methanol / acrylic acid monoester Ester (PO = 4.3 / EO = 25.5) B-4 PO / EO addition Monoester of methanol and methacrylic acid (PO = 7.9 / EO = 47.3).

The contents and symbols of the polyethylene oxide and propylene oxide adduct monomers used as comparative examples are shown below. D-1 EO-added methanol and methacrylic acid monoester (EO = 23.5) D-2 EO / PO random-added methanol and acrylic acid monoester (EO = 23.2 / PO = 3.5) Show. Production Example 1 (Symbol AC-1 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-
50 parts of 1 and 50 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 8 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 21,000.

Production Example 2 (Symbol AC-2 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-
60 parts of 2 and 40 parts of sodium methacrylate are charged, 30%
The pH was adjusted to 9 with an 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, 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 3 (Symbol AC-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-
70 parts of 3 and 30 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 12 parts of 25% ammonium persulfate aqueous solution. After reaction for 5 hours and completion of polymerization, the mixture was completely neutralized with a 30% aqueous sodium hydroxide solution to obtain a copolymer having a molecular weight of 11,000.

Production Example 4 (Symbol AC-4 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 4 and 55 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 reaction for 5 hours and completion of polymerization, the mixture was completely neutralized with a 30% aqueous sodium hydroxide solution to obtain a copolymer having a molecular weight of 21,000.

Production Example 5 (Symbol BC-1 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. B-
1 part 55 parts, sodium methacrylate 45 parts 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 8 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 19,000.

Production Example 6 (Symbol BC-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. B-
60 parts of 2 and 40 parts of sodium methacrylate are charged, 30%
The pH was adjusted to 9 with an 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, the mixture was completely neutralized with a 30% aqueous sodium hydroxide solution to obtain a copolymer having a molecular weight of 18,000.

Production Example 7 (Symbol BC-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. B-
70 parts of 3 and 30 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 12 parts of 25% ammonium persulfate aqueous solution. After reaction for 5 hours and completion of polymerization, the mixture was completely neutralized with a 30% aqueous sodium hydroxide solution to obtain a copolymer having a molecular weight of 16,000.

Production Example 8 (Symbol BC-4 of 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. B-
55 parts of 4 and 45 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 reaction for 5 hours and completion of polymerization, the mixture was completely neutralized with a 30% aqueous sodium hydroxide solution to obtain a copolymer having a molecular weight of 23,000.

Production Example 9 (Symbol DC-1 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. D-
70 parts of 1 and 30 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 12 parts of 25% ammonium persulfate aqueous solution. After reaction for 5 hours and completion of polymerization, the mixture was completely neutralized with a 30% aqueous sodium hydroxide solution to obtain a copolymer having a molecular weight of 13,000.

Production Example 10 (Symbol DC-2 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. D-
45 parts of 2 and 55 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 20,000.

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 in the Examples: naphthalene-based admixture (Mighty 150
Manufactured by Kao Co., Ltd. Symbol MS in Examples: Melamine admixture (Mighty 150V-
2; Mixing conditions of evaluation concrete as a concrete admixture manufactured by Kao Corporation are shown in Table 1.

[0037]

[Table 1]

The concrete was evaluated according to the concrete composition shown in Table 1 by mixing the material and the admixture with a tilting mixer at 25 rpm.
× 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 evaluation results are shown in Table 2.

[0039]

[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.

[0041]

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