JPH0812396A - Concrete admixture - Google Patents

Abstract

PURPOSE:To improve hardening time, to eliminate the delay of demolding time and to facilitate job schedule control by allowing an admixture to consist of a copolymer obtained by polymerizing a specific monomer and one or more kinds of monomers selected between two kinds of compounds. CONSTITUTION:The copolymer having the weight-average molecular weight of 1000-500000 is obtained by polymerizing the monomer (a) of a dehydrogenation reaction product of a one terminal alkyl blocked polyalkylene glycol expressed by formula I (each of R1 and R2 is hydrogen or methyl, M1 is 0-2, AO is a 2-3C oxyalkylene, (n) is 50-100 and X is H or a 1-3C alkyl) with (metha)acrylic acid or a fatty acid, or an ethylene oxide or propylene oxide adduct (the mol number of adduct part is 50-100) to this dehydrogenation reaction product and one or more kinds of the monomers (b) selected from the compounds expressed by formula II and III (each of R3-R5 is H, methyl or (CH2)m2COOM2, R6 is H or methyl, each of M1, M2 and Y is an alkali metal, alkaline earth metal, ammonium, an alkylammonium and m2 is 0-2) in the reaction unit of (a)/(b)=1/99-80/20 (mol ratio).

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 that exhibits fluidity of hydraulic compositions such as cement paste, mortar, and concrete, and does not delay the curing time.

[0002]

BACKGROUND OF THE INVENTION Among concrete admixtures, naphthalene sulfonic acid formaldehyde condensate (hereinafter referred to as naphthalene type) and melamine sulfonic acid formaldehyde condensate are typical ones having a great fluidizing effect. (Hereinafter, referred to as melamine-based), polycarboxylic acid salts (hereinafter referred to as polycarboxylic acid-based), and so on, which 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 (referred to as 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, even in the polycarboxylic acid system having these alkylene chains, it has not been solved in a high strength region where a large amount of addition is required, and delay of finishing process of concrete placing surface and demolding of formwork. However, a solution is desired because it will be significantly delayed.

More specifically, it has been speculated that the excellent dispersion mechanism of a water-soluble vinyl copolymer having an oxyalkylene group is a dispersion mechanism which suppresses the adhesion of particles because the graft structure of the oxyalkylene chain serves as a steric barrier. . And
Regarding the oxyalkylene group, the aforementioned copolymer patent defines the number of moles of ethylene oxide and / or propylene oxide as 2 to 100 moles. However, in the examples of these known patents, ethylene oxide 23
The upper limit is the molar addition (Japanese Examined Patent Publication No. 59-18338), no mention is made of 23 to 100 moles, and no mention is made of the relationship between curing retardation and alkylene groups.

[0007]

As a result of various studies on the chain length of an oxyalkylene group, the present inventors have found that the dispersibility is better than that of a naphthalene type in the range of the chain length (addition mole number 50 to 100) of a specific region. It was also found that the curing time was dramatically improved as compared with the conventional water-soluble vinyl copolymer having an oxyalkylene group.

That is, the present invention is one selected from a monomer (a) represented by the following general formula (A) and a compound represented by the following general formulas (B) and (C). The present invention relates to a concrete admixture containing a copolymer obtained by polymerizing the above-mentioned monomer (b) as an essential component.

[0009]

Embedded image

(Wherein R ₁ and R _{2 are} hydrogen and a methyl group m ₁ is an integer of 0 to 2 AO is an oxyalkylene group having 2 to 3 carbon atoms n is an integer of 50 to 100 X is hydrogen or a carbon number of 1 ~ Represents an alkyl group of 3).

[0011]

[Chemical 4]

(In the formula, R _{3 to} R ₅ : hydrogen, methyl group, (CH ₂ ) m
₂ COOM ₂ R ₆ : hydrogen, methyl group M ₁ , M ₂ , Y: alkali metal, alkaline earth metal, ammonium or alkylammonium m ₂ : represents an integer of 0 to 2 ) Considering the present invention from the condensation mechanism, in the limited region where the chain length of the oxyalkylene group is 50 to 100 mol,
It is considered that the hydration reaction of cement proceeds without being hindered. That is, in the region where the chain length of the oxyalkylene group is less than 50 mol, the amount of the carboxyl group in the admixture structure is large, the hydration reaction due to the calcium chelate is delayed, and the chain length of the oxyalkylene group is 100 mol. If the amount exceeds the limit, it is presumed that water is strongly bound to the oxyalkylene group chain portion of the admixture adsorbed on the cement surface, inhibiting the hydration reaction with cement.

Further, in the present invention, the oxyalkylene group having a chain length of 60 to 90 mol is particularly excellent in curing characteristics.

In the present invention, the monomer (a) represented by the general formula (A) is methoxypolyethylene glycol,
Methoxy polypropylene glycol, methoxy polyethylene polypropylene glycol, ethoxy polyethylene glycol, ethoxy polypropylene glycol, ethoxy polyethylene polypropylene glycol, propoxy polyethylene glycol, propoxy polypropylene glycol, propoxy polyethylene polypropylene glycol, etc. Dehydrogenation (oxidation) of fatty acids
An esterification product with a reaction product or an ethylene oxide or propylene oxide addition product to a dehydrogenation (oxidation) reaction product of (meth) acrylic acid or a fatty acid is used. The number of added moles of polyalkylene glycol is 50 to 100, preferably 60 to 90, and both addition products of ethylene oxide and propylene oxide can be used in any of random addition, block addition, alternate addition and the like.

As the compound represented by the general formula (B), acrylic acid-based monomers such as acrylic acid, methacrylic acid and crotonic acid, and their alkali metal salts,
Examples thereof include alkaline earth metal salts, ammonium salts and amine salts. Further, as the unsaturated dicarboxylic acid-based monomer, maleic anhydride, maleic acid, itaconic anhydride, itaconic acid, citraconic anhydride, citraconic acid and fumaric acid, and their alkali metal salts, alkaline earth metal salts, ammonium Salts, amine salts and the like are used.

As the compound represented by the general formula (C), allylsulfonic acid and methallylsulfonic acid, and their alkali metal salts, alkaline earth metal salts, ammonium salts and amine salts are used.

Monomers constituting the copolymer in the present invention
The reaction unit of (a) and monomer (b) is monomer (a) / monomer (b) =
The range of 1/99 to 80/20 (molar ratio) is particularly excellent because the curing time is short. When it is smaller than 1/99 or larger than 80/20, dispersibility is deteriorated, which is not preferable.

Further, the copolymer of the present invention may be reacted with another copolymerizable monomer within a range that does not impair the effects of the present invention. For example, acrylonitrile, acrylic ester, acrylamide, methacrylamide, styrene, styrene sulfonic acid, etc. may be mentioned.

The polymer of the present invention can be produced by a known method. For example, JP-A-59-16216
No. 3, Special Fair 2-11542, Special Fair 2-7901, Special Fair 2-78
The method described in Japanese Patent Publication No. 97 etc. may be mentioned.

The solvent used for solution 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. From the viewpoint of handling and reaction equipment, water and alcohol having 1 to 4 carbon atoms are preferable.

For aqueous solution polymerization, a water-soluble polymerization initiator such as ammonium or alkali metal persulfate or hydrogen peroxide is used. Further, benzoyl peroxide, lauroyl peroxide and the like are used as a polymerization initiator for solution polymerization other than the aqueous system.

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

Weight average molecular weight of the copolymer in the present invention
The range of 1,000 to 500,000 is preferable (gel permeation chromatography method / polystyrene sulfonic acid conversion), and the range of 5,000 to 100,000 is more preferable for dispersibility.
If the weight average molecular weight is too large, the dispersibility is insufficient, and if the weight average molecular weight is too small, the slump retention tends to decrease, so that it is not suitable as an admixture.

Further, the concrete admixture of the present invention can be used in combination with a known cement admixture. As an example of a known cement admixture, naphthalene sulfonate formaldehyde condensate, melamine sulfonate formaldehyde condensate, lignin sulfonate, phenol / sulfanylate formaldehyde condensate, and
One or more selected from (meth) acrylic acid / (meth) acrylic acid ester copolymer salts may be mentioned. The addition amount is 0.01 to 0.5% by weight (solid content) with respect to cement.
Is preferred.

The amount of the concrete admixture of the present invention added to concrete is preferably 0.05 to 1.0% by weight (solid content) relative to cement, and 0.1 to 0.5% by weight (solid content).
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,
Examples include accelerators, foaming agents, foaming agents, defoaming agents, thickeners, waterproofing agents, antifoaming agents, silica sand, blast furnace 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 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" unless otherwise specified.

The contents and symbols of the monomer (a) used in the polymerization and the contents and symbols of Comparative Example of the monomer (a) are shown below. However, EO represents ethylene oxide and PO represents propylene oxide. <Contents of Monomer (a)> A-1: Methoxypolyethylene glycol methacrylic acid ester (EO addition mole number = 53) A-2: Methoxypolyethylene glycol acrylate (EO addition mole number = 75) A-3: Methoxy polyethylene glycol methacrylic acid ester (EO addition mole number = 95) A-4: acrylic acid EO addition product (EO addition mole number = 60) A-5: acrylic acid PO / EO addition product (PO addition mole number = 5,
EO addition mole number = 70 block addition product) A-6: acrylic acid PO / EO addition product (PO addition mole number = 10,
Random adduct with EO addition mole number = 60) A-7: Methoxypolyethylene glycol methacrylic acid ester (EO addition mole number = 90) <Contents of Comparative Example of Monomer (a)> A-8: Methoxypolyethylene glycol methacryl Acid ester (mole number of EO addition = 23) A-9: methoxypolyethylene glycol methacrylic acid ester (mole number of EO addition = 122) A production example of a copolymer is shown below. Production Example 1 (symbol AB-1 of admixture) 70 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 75 ° C in a nitrogen atmosphere. A-1
0.7 mol, methacrylic acid 0.3 mol (molar ratio = 3/7),
A mixture of 30 mol of water, 0.01 mol of 20% ammonium persulfate aqueous solution and 6 g of 2-mercaptoethanol
Each of them is simultaneously dropped into the reaction system over 2 hours. Next, 0.03 mol of 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C) for 1 hour. After aging 95 ℃
The temperature is raised to 18%, and 18 g of 35% hydrogen peroxide is added dropwise over 1 hour, followed by aging at the same temperature (95 ° C) for 2 hours. After aging, 48
Add 0.21 mol% sodium hydroxide to neutralize, molecular weight 25,0
A copolymer of 00 was obtained.

Production Example 2 (Symbol AB-2) A reaction vessel equipped with a stirrer was charged with 30 mol of water, the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-2
0.3 mol, sodium acrylate 0.7 mol (molar ratio = 3/7), water 15 mol mixed and dissolved, and 20% ammonium persulfate aqueous solution 0.01 mol and 2-mercaptoethanol 5 g, respectively, were used as reaction systems at the same time. Add dropwise over 2 hours. Next, add 0.03 mol of 20% ammonium persulfate aqueous solution to 30%.
Drop over a period of minutes and age for 1 hour at the same temperature (75 ° C). After aging, the temperature is raised to 95 ° C., 15 g of 35% hydrogen peroxide is added dropwise over 1 hour, and aging is performed at the same temperature (95 ° C.) for 2 hours. After completion of aging, pH was adjusted to 8 by adding 10% sodium hydroxide to obtain a copolymer having a molecular weight of 42,000.

Production Example 3 (symbol AB-3 for admixture) 5 mol of water was charged in a reaction vessel equipped with a stirrer, and the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-3
0.02 mol, monosodium maleate 0.98 mol (molar ratio = 2/98), 5 mol of water mixed and dissolved, 0.01 mol of 20% ammonium persulfate aqueous solution and 3 g of 2-mercaptoethanol 3g at the same time Over 2 hours. Next, 0.03 mol of 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C) for 1 hour. After aging, the temperature is raised to 95 ° C., 15 g of 35% hydrogen peroxide is added dropwise over 1 hour, and aging is performed at the same temperature (95 ° C.) for 2 hours. After the aging, 10% sodium hydroxide was added to adjust the pH to 8 to obtain a copolymer having a molecular weight of 55,000.

Production Example 4 (Symbol AB-4) A reaction vessel equipped with a stirrer was charged with 20 mol of water, and the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-4
0.2 mol, acrylic acid 0.7 mol, allyl sulfonic acid
0.1 mol (molar ratio = 2/7/1), 10 mol of water mixed and dissolved, 0.01 mol of 20% ammonium persulfate aqueous solution and 6 g of 2-mercaptoethanol are added dropwise to the reaction system simultaneously over 2 hours. . Next, 0.03 mol of 20% ammonium persulfate aqueous solution was added dropwise over 30 minutes, and the temperature (75
Aging). After aging, the temperature is raised to 95 ° C., 18 g of 35% hydrogen peroxide is added dropwise over 1 hour, and aging is performed at the same temperature (95 ° C.) for 2 hours. After completion of the aging, 0.5 mol of 48% sodium hydroxide was added to neutralize and obtain a copolymer having a molecular weight of 9,500.

Production Example 5 (Symbol AB-5) A reaction vessel equipped with a stirrer was charged with 10 mol of water, and the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-5
0.1 mol, acrylic acid 0.8 mol, methallyl sulfonic acid 0.1 mol (molar ratio = 1/8/1), water 10 mol mixed and dissolved, and 20% ammonium persulfate aqueous solution 0.01 mol and 2-
3 g of mercaptoethanol (5 g) is simultaneously added dropwise to the reaction system over 2 hours. Next, 0.03 mol of a 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the temperature is kept at the same temperature for 1 hour.
Aging at (75 ℃). After aging, the temperature was raised to 95 ° C, 15g of 35% hydrogen peroxide was added dropwise over 1 hour, and the temperature (95%) was maintained for 2 hours.
Aging). After aging, 48% sodium hydroxide
0.6 mol was added to neutralize and obtain a copolymer having a molecular weight of 14,000.

Production Example 6 (symbol AB-6 as an admixture) 70 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 75 ° C in a nitrogen atmosphere. A-6
Is 0.3 mol, methacrylic acid is 0.7 mol (molar ratio = 3/7),
A mixture of 30 mol of water, 0.01 mol of 20% ammonium persulfate aqueous solution and 3 g of 2-mercaptoethanol
Each of them is simultaneously dropped into the reaction system over 2 hours. Next, 0.03 mol of 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C) for 1 hour. After aging 95 ℃
The temperature is raised to 15, and 15 g of 35% hydrogen peroxide is added dropwise over 1 hour, followed by aging at the same temperature (95 ° C) for 2 hours. After aging, 48
Add 0.21 mol% sodium hydroxide to neutralize, molecular weight 95,0
A copolymer of 00 was obtained.

Production Example 7 (symbol AB-7 as an admixture) 80 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 75 ° C in a nitrogen atmosphere. A-7
Is 0.3 mol, methacrylic acid is 0.7 mol (molar ratio = 3/7),
A mixture of 42 mol of water, 0.01 mol of 20% ammonium persulfate aqueous solution and 5 g of 2-mercaptoethanol
Each of them is simultaneously dropped into the reaction system over 2 hours. Next, 0.03 mol of 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C) for 1 hour. After aging 95 ℃
The temperature is raised to 25 ° C., 25 g of 35% hydrogen peroxide is added dropwise over 1 hour, and the mixture is aged at the same temperature (95 ° C.) for 2 hours. After aging, 48
Add 0.21 mol% sodium hydroxide to neutralize, molecular weight 57,0
A copolymer of 00 was obtained.

Comparative Production Example 8 (Symbol AB-8) A reaction vessel equipped with a stirrer was charged with 10 mol of water, and the atmosphere was replaced with nitrogen while stirring, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. A-8
Is 0.3 mol, methacrylic acid is 0.7 mol (molar ratio = 3/7),
A mixture of 10 mol of water, 0.01 mol of 20% ammonium persulfate aqueous solution and 6 g of 2-mercaptoethanol
Each of them is simultaneously dropped into the reaction system over 2 hours. Next, 0.03 mol of 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C) for 1 hour. After aging 95 ℃
The temperature is raised to 18%, and 18 g of 35% hydrogen peroxide is added dropwise over 1 hour, followed by aging at the same temperature (95 ° C) for 2 hours. After aging, 48
Add 0.21 mol% sodium hydroxide to neutralize, molecular weight 35,0
A copolymer of 00 was obtained.

Comparative Production Example 9 (symbol AB-9 as an admixture) 12 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 75 ° C. in a nitrogen atmosphere. A-9
0.05 mol, methacrylic acid 0.95 mol (molar ratio = 5/95)
, Dissolved in 10 mol of water, 0.01 mol of 20% ammonium persulfate aqueous solution and 5 g of 2-mercaptoethanol
Each of the three is simultaneously added dropwise to the reaction system over 2 hours. Next, 0.03 mol of 20% ammonium persulfate aqueous solution is added dropwise over 30 minutes, and the mixture is aged at the same temperature (75 ° C) for 1 hour. After aging, the temperature is raised to 95 ° C., 15 g of 35% hydrogen peroxide is added dropwise over 1 hour, and aging is performed at the same temperature (95 ° C.) for 2 hours. After the aging was completed, 0.21 mol of 48% sodium hydroxide was added to neutralize and obtain a copolymer having a molecular weight of 65,000.

The contents and symbols of known cement admixtures used in the examples are shown below. Symbol for admixture NS: Naphthalene admixture (Mighty 150
; Kao Corporation) Admixture symbol MS: Melamine admixture (Mighty 150V-
2; manufactured by Kao Corporation. Admixture symbol AA: (meth) acrylic acid / (meth) acrylic acid ester copolymer salt (Mighty 2000WHZ; manufactured by Kao Corporation).

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

[0040]

[Table 1]

The concrete was prepared by mixing the materials and admixtures with a concrete mixture shown in Table 1 using a tilting mixer at 25 r.
It was adjusted by kneading for 3 minutes at pm. Liquidity (slump value)
Table 2 shows the results of measuring the curing time. The slump value was measured according to JIS-A1101 method, and the hardening time of concrete was measured according to ASTM-C-403 method.

[0042]

[Table 2]

<Evaluation Results> As is clear from Table 2, the concrete admixture of the present invention has better fluidity and faster curing time than the comparative product.

[0044]

When the concrete admixture according to the present invention is added to the cement composition, there is no delay in the demolding time of the formwork from the finishing process, so that the construction schedule can be easily managed.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area C08F 222/02 290/06 MRS C04B 103: 32

Claims (6)

[Claims] 1. A monomer (a) represented by the following general formula (A):
A concrete admixture containing as an essential component a copolymer obtained by polymerizing a monomer and one or more monomers (b) selected from compounds represented by the following general formulas (B) and (C) . Embedded image (In the formula, R ₁ and R ₂ : hydrogen, a methyl group m ₁ : an integer of 0 to 2 AO: an oxyalkylene group having 2 to 3 carbon atoms n: an integer of 50 to 100 X: hydrogen or a carbon number of 1 to 3 Represents an alkyl group.) (Wherein, R ₃ to R _5: hydrogen, _{methyl, (CH 2) m 2 COOM} 2 R 6: hydrogen, methyl M _1, M _2, Y: alkali metal, alkaline earth metal, ammonium or alkyl ammonium m ₂ : represents an integer of 0 to 2) 2. A monomer (a) constituting the copolymer, a monomer
The reaction unit of (b) is monomer (a) / monomer (b) = 1/99 to 80/20
(Mole ratio) The concrete admixture according to claim 1. 3. The average molecular weight of the copolymer is 1,0 in terms of weight average molecular weight (gel permeation chromatography method / standard substance sodium polystyrene sulfonate / water system).
The concrete admixture according to claim 1 or 2, which has an amount of 00 to 500,000. 4. The concrete admixture according to claim 1, further comprising a publicly known cement admixture. 5. A known cement admixture used in combination is naphthalene sulfonate formaldehyde condensate, melamine sulfonate formaldehyde condensate, lignin sulfonate, phenol / sulfanylate formaldehyde condensate, and (meth) acrylic acid. The concrete admixture according to claim 4, which is one or more selected from (meth) acrylic acid ester copolymer salts. 6. The concrete admixture according to any one of claims 1 to 5, wherein in the general formula (A), n is an integer of 60 to 90.