JPH10194809A - Concrete admixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement admixture small in slump loss over a long period. SOLUTION: This concrete admixture contains a polycondensation product having a residue induced from a polycondensing monomer (A) having 1-300mol of a 2-3C oxyalkylene group and a residue induced from a polycondensing monomer (B) having carboxy monoester group as essential structural units. Further, a residue induced from a polycondensing monomer (C) having one or more kinds of groups selected from a group consisting of carboxyl group, sulfonic group, sulfuric group and phosphoric group can be contained as the essential structural unit. Preferably the polycondensing monomer (A) is an oxyalkylene group addition compound of phenol and the polycondensing monomer (B) is a 1-18C alkyl or alkenyl or a 2-6C hydroxy alkyl hydroxy benzoic ester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a concrete admixture. More specifically, the present invention relates to a concrete admixture which exhibits an effect of improving the fluidity of a hydraulic composition such as cement paste, mortar, and concrete, and in particular, the effect of maintaining fluidity.

[0002]

2. Description of the Related Art Among concrete admixtures, representatives having a large fluidity effect include naphthalenesulfonic acid formaldehyde condensate salt (naphthalene type), melaminesulfonic acid formaldehyde condensate salt (melamine type), and polycarboxylic acid. There is a so-called high-performance water reducing agent such as a salt (polycarboxylic acid type).

Although these admixtures have excellent functions, they also have problems. For example, although naphthalene-based and melamine-based materials are excellent in curing properties, they have a problem in fluidity retention (slump loss), and polycarboxylic acid-based materials have a problem that curing delay is large.

In recent years, the development of a polycarboxylic acid-based concrete admixture exhibiting excellent fluidity has made it possible to obtain good dispersibility with a small amount of addition, and the problem of delay in curing is being improved. For example, water-soluble vinyl copolymers such as copolymers of a polyalkylene glycol monoester monomer having an unsaturated bond and an acrylic acid and / or unsaturated dicarboxylic acid monomer are exemplified. (JP-B-59-18338, JP-B-2-78978, JP-B-2
-7898, JP-B-2-7901, JP-B2-1154
No. 2, JP-A-3-75252, JP-A-59-162163, etc.). However, at present, sufficient effects have not yet been obtained for the effect of maintaining fluidity.

In view of these circumstances, the present inventors have proposed in JP-A-7-223852 an improvement in slump loss by using an admixture of a copolymer containing a high chain length oxyalkylene group. JP-A-8-12401 discloses an improvement in slump loss by using an admixture of an aromatic copolymer containing an oxyalkylene group having a high chain length.

[0006]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. Hei 7-2238.
No. 52 and Japanese Patent Application Laid-Open No. H08-12401 disclose the technology described in
It enables slump holding to be performed well for a long time of up to 90 minutes or more. However, in order to cope with a delay in placing concrete due to traffic congestion or construction trouble, slump maintenance for about two hours is often required, and further improvement is required. Accordingly, an object of the present invention is to provide a concrete admixture which enables such a slump characteristic to be maintained for a longer time.

[0007]

Means for Solving the Problems The present inventors have intensively studied as a means for maintaining the dispersibility of cement particles against slump holding for a long time, from the viewpoint of successive replenishment of a dispersant. That is, the present inventors performed molecular design from the viewpoint of the adsorption rate of the dispersant in the strong ionic system in concrete,
A polycondensate containing an oxyalkylene group and a residue derived from a specific polycondensable monomer shows a very good slump retention effect and finds that retention for a much longer time than before is possible, The present invention has been completed.

That is, the present invention relates to a polycondensable monomer having a carboxymonoester group and a residue derived from a polycondensable monomer (A) having 1 to 300 mol of an oxyalkylene group having 2 to 3 carbon atoms. It is intended to provide a concrete admixture characterized by containing a polycondensate having a residue derived from a monomer (B) as an essential structural unit.

When the concrete admixture of the present invention is used for concrete, an extremely excellent effect for maintaining slump is exhibited. However, this is because the dispersant is sequentially incorporated into the cement hydrate and the fluidity is reduced. It is thought that it is to buffer doing. That is, it is considered that the oxyalkylene group and the specific monomer residue in the polycondensate of the present invention regulate the rate of adsorption to cement. In particular, by introducing a residue derived from the polycondensable monomer (B) having a carboxymonoester group, the carboxyl group of the adsorbing group is gradually increased due to ester decomposition by alkali, and a new dispersion is obtained. It is considered that the agent is supplied, thereby compensating for a decrease in the fluidity and maintaining the fluidity.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polycondensable monomer having 1 to 300 moles of an oxyalkylene group having 2 to 3 carbon atoms used in the present invention is an aromatic monomer, particularly an oxyalkylene group having 2 to 3 carbon atoms. Polyoxyalkylene alkyl phenols or polyoxyalkylene alkyl naphthols in which 1 to 300 mol of alkylene groups are introduced are used. For example,
It is an adduct of 1 to 300 moles of an oxyalkylene group to phenol, cresol, nonylphenol, naphthol, methylnaphthol, butylnaphthol, bisphenol and the like. From the viewpoint of cocondensability, a benzene ring derivative, that is, a polyoxyalkylene alkylphenol is preferable, and an oxyalkylene group adduct of phenol is particularly preferable.

An oxyalkylene group having 2 to 3 carbon atoms is
It means ethylene oxide or propylene oxide, which may be introduced in random or block form, and is not limited. In addition, the terminal of the oxyalkylene group may be any one of a hydroxyl group, an alkyl ether and an alkyl ester.

The number of moles of the added oxyalkylene group having 2 to 3 carbon atoms may be an average of 1 or more. Can be used even if
However, when the oxyalkylene group exceeds 300 mol on average, the dispersion retention tends to decrease.

The polycondensable monomer (B) having a carboxy monoester group used in the present invention is an aromatic monomer, particularly a benzene ring or naphthalene ring derivative, for example, a straight chain having 1 to 18 carbon atoms. Or a branched-chain alkyl isophthalate, hydroxynaphthoate, benzoate or hydroxybenzoate, having 1 carbon atom
-18 linear or branched alkenyl isophthalate, hydroxynaphthoate, benzoate, or hydroxybenzoate, or hydroxyalkyl isophthalate having 2 to 6 carbon atoms,
Hydroxynaphthoic acid esters, benzoic acid esters, or hydroxybenzoic acid esters are used.

However, considering the cocondensability, the following general formula

[0015]

Embedded image

A phenol derivative compound represented by the formula (wherein, R _{1 is} an alkyl or alkenyl group having 1 to 18 carbon atoms or a hydroxyalkyl group having 2 to 6 carbon atoms) is preferable. That, R ₁ in the general formula above having 1 to 18 carbon atoms, more preferably an alkyl group or an alkenyl group, or a hydroxyalkyl group having 2 to 6 carbon atoms having 1 to 6 carbon atoms, o- hydroxybenzoic Acid esters, m-hydroxybenzoic esters, or p-hydroxybenzoic esters are preferred.

The polycondensate of the present invention may further have, as an essential structural unit, a residue derived from a polycondensable monomer (C) having a carboxyl group or a sulfonic acid group.

Since the component (C) has an adsorptive group,
By introducing this, the adsorbability of the polycondensate to the cement can be increased, and it can contribute to the development of fluidity immediately after kneading.

Polycondensable monomer having a sulfonic acid group (C)
For example, aromatic monomers such as alkylnaphthalenesulfonic acid, alkylphenolsulfonic acid, anilinesulfonic acid, and alkylbenzenesulfonic acid can be used. Examples include naphthalene sulfonic acid, methyl naphthalene sulfonic acid, butyl naphthalene sulfonic acid, phenol sulfonic acid, cresol sulfonic acid, aniline sulfonic acid, benzene sulfonic acid, toluene sulfonic acid, melamine sulfonic acid, and the like. It is also possible to use these isomers and those obtained by condensing them. For example, lignin sulfonic acid or naphthalene sulfonic acid formaldehyde condensate can be used. However, from the viewpoint of cocondensability, a sulfonic acid compound composed of a phenol derivative, that is, an alkylphenolsulfonic acid is preferred, and phenolsulfonic acid is particularly preferred.

Polycondensable monomer having a carboxyl group
As (C), an aromatic monomer, in particular, a benzene ring or naphthalene ring derivative can be used. For example, isophthalic acid, hydroxynaphthoic acid, benzoic acid, hydroxybenzoic acid and the like, and isomers thereof can be mentioned.
However, considering co-condensability, o-hydroxybenzoic acid, m-hydroxybenzoic acid, or p-hydroxybenzoic acid is preferred.

The polycondensate contained in the concrete admixture of the present invention may contain a residue derived from another polycondensable monomer as long as the effects of the present invention are not impaired. . Examples of such monomers include phenol,
Alkyl phenols such as cresol are exemplified.

The polycondensate according to the present invention can be used as a concrete admixture while being acidic, but is preferably used as a neutralizing salt from the viewpoint of storage and use. Examples of the neutralizing salt include a monovalent metal salt, a divalent metal salt, an ammonium salt, an amine salt, and a substituted amine salt.

The reaction molar ratio of the polycondensable monomer (A) to the polycondensable monomer (B) is in the range of (A) / (B) = 1 to 99/99 to 1 for maintaining the dispersion. From the aspect, it is appropriate, and the range of 10 to 50/50 to 90 is particularly excellent in dispersion retention. In addition, polycondensable monomers
When (C) is reacted, the reaction molar ratio is (A) / (B)
The range of / (C) = 1 to 98/1 to 98/1 to 98 is suitable from the viewpoint of dispersion maintenance, and the range of 5 to 50/5 to 90/5 to 90 is particularly excellent in dispersion maintenance.

The standard method for producing the polycondensate of the present invention includes, for example, a polycondensable monomer (A) having a predetermined amount of an oxyalkylene group and a polycondensable monomer (B) having a carboxymonoester. ), Or a polycondensable monomer (C) having a carboxyl group, a sulfonic acid group, a sulfate group, and / or a phosphate group in a reaction vessel, and stirred at a temperature of 70 to 90 ° C under stirring. A predetermined amount of aqueous formaldehyde solution
There is a method in which the mixture is added dropwise over 4 hours, and after the addition, the mixture is stirred under reflux for 3 to 30 hours, cooled, and neutralized. However, this is only an example, and the present invention is not limited by this method.

In the polycondensation system, water is added and adjusted to control the condensation viscosity and the condensation time.
The reaction is carried out under acidic conditions. If the compound is already acidic due to a compound having a sulfonic acid group or an unreacted acid contained therein, the condensation is carried out in the acidic region as it is. If the reaction system does not make it acidic, sulfuric acid or the like is added in advance to adjust the pH to 2 or less, and then the reaction is performed.

Weight average molecular weight of polycondensate of the present invention (condensation degree is calculated from molecular weight by gel permeation chromatography / sodium polystyrene sulfonate conversion)
Is preferably 3,000 to 100,000, more preferably 5,000 to 50,000. If the average molecular weight is less than 3,000 or exceeds 100,000, the dispersion retention tends to be poor.

The amount of the concrete admixture of the present invention added to concrete is 0.02 to 1.0 in terms of solid content with respect to cement.
% By weight, more preferably 0.05 to 0.5% by weight.

The concrete admixture of the present invention can be used in combination with a high-performance water reducing agent. When used in combination with the high-performance water reducing agent, the fluctuation range of the flow value at the initial stage of the concrete and the flow value over time is reduced, and a stable slump value can be obtained.

Examples of the high-performance water reducing agent include naphthalene type (eg, Mighty 150 manufactured by Kao Corporation), melamine type (eg, Mighty 150V-2 manufactured by Kao Corporation), and aminosulfonic acid type (eg, Fujisawa Chemical Co., Ltd.) PALIC FP), polycarboxylic acid (for example, Mighty 2000WHZ manufactured by Kao Corporation) and the like. Among the known high-performance water reducing agents, a polyalkylene glycol monoester monomer having 110 to 300 moles of an oxyalkylene group having 2 to 3 carbon atoms, which is disclosed in JP-A-7-223852, and an acrylic acid-based polymer, The one containing the unified copolymer is excellent in the effect of maintaining the fluidity and is preferred.

The mixing ratio of the concrete admixture of the present invention and the high-performance water reducing agent is such that the weight ratio of the polycondensate of the present invention /
The range of the high-performance water reducing agent = 1 to 99/99 to 1 (total is 100% by weight) is preferable from the viewpoint of maintaining the fluidity, and 10 to 99/99.
The range of 90/90 to 10 is further excellent in maintaining the fluidity and is preferred.

Further, the concrete admixture of the present invention can be used in combination with other known additives (materials). Examples include AE agents, AE water reducing agents, superplasticizers, retarders, fast strengtheners, accelerators, foaming agents, foaming agents, defoamers, thickeners, waterproofing agents, foam inhibitors and silica sand, blast furnaces Slag, fly ash, silica fume and the like can be mentioned.

Further, the concrete admixture of the present invention is added to a cement paste, mortar, concrete or the like having a hydraulic cement composition, but the content thereof is not limited at all.

[0033]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In the following examples, “%” means “% by weight” unless otherwise specified. The molecular weight indicates a molecular weight based on a weight average molecular weight (gel permeation chromatography / sodium polystyrene sulfonate conversion).

Polycondensable monomer having 1 to 300 mol of oxyalkylene group having 2 to 3 carbon atoms used in the following examples
(A), a polycondensable monomer having a carboxy monoester group (B), a polycondensable having one or more groups selected from the group consisting of a carboxyl group, a sulfonic group, a sulfate group, and a phosphate group The contents of the monomer (C) are shown below. In addition, EO represents ethylene oxide, PO represents propylene oxide, and the numerical values represent the average number of moles added.

Polycondensable monomer (A) A-1; phenol EO 10 mol adduct A-2; phenol EO 75 mol adduct A-3; phenol EO 120 mol adduct A-4; phenol EO 250 mol / PO 20 mol block Adduct A-5; naphthol EO 2-mol adduct A-6 (comparative); phenol EO 370 mol adduct polycondensable monomer (B) B-1; methyl p-hydroxybenzoate B-2; o-hydroxybenzo Butyric acid B-3; methyl hydroxynaphthoate polycondensable monomer (C) C-1; p-hydroxybenzoic acid C-2; hydroxynaphthoic acid C-3; phenolsulfonic acid C-4; naphthalenesulfonic acid formaldehyde Condensate (Molecular weight 4500) The production example of the co-condensate is shown below.

Production Example 1 (D-1 of admixture) In a reaction vessel equipped with a stirrer, 0.3 mol of A-1, 0.7 mol of B-1, 0.5 mol of sulfuric acid, and 4 mol of water were charged, and a 37% aqueous formaldehyde solution was added. 0.9 mol was added dropwise at 80 ° C. over 3 hours. After completion of the dropwise addition, the mixture was heated to 105 ° C. and reacted for 10 hours, then cooled, adjusted to pH 6 with a 50% aqueous sodium hydroxide solution, and allowed to stand. After standing, the upper layer separated from the two layers was taken, and the solid content was adjusted to 30% by adding water to obtain a co-condensate having a molecular weight of 32,000.

Production Example 2 (Admixture symbol D-2) In a reaction vessel equipped with a stirrer, 0.1 mol of A-2, 0.7 mol of B-2, and C-
1 mol 0.2 mol, sulfuric acid 0.3 mol, water 4 mol, 37%
0.9 mol of an aqueous formaldehyde solution was added dropwise at 80 ° C. over 3 hours. After completion of the dropwise addition, the mixture was heated to 105 ° C. and reacted for 10 hours, then cooled, adjusted to pH 6 with a 50% aqueous sodium hydroxide solution, and allowed to stand. After standing, take the upper layer separated into two layers,
The solid content was adjusted to 30% by adding water to obtain a cocondensate having a molecular weight of 25,000.

Production Example 3 (Admixture D-3) In a reaction vessel equipped with a stirrer, 0.2 mol of A-3, 0.6 mol of B-1 and C-
2 mol 0.2 mol, sulfuric acid 0.3 mol, water 4 mol, 37%
0.9 mol of an aqueous formaldehyde solution was added dropwise at 80 ° C. over 3 hours. After completion of the dropwise addition, the mixture was heated to 105 ° C. and reacted for 10 hours, then cooled, adjusted to pH 6 with a 50% aqueous sodium hydroxide solution, and allowed to stand. After standing, take the upper layer separated into two layers,
The solid content was adjusted to 30% by adding water to obtain a co-condensate having a molecular weight of 37,000.

Production Example 4 (D-4 of admixture) In a reaction vessel equipped with a stirrer, 0.1 mol of A-4, 0.5 mol of B-3, and C-
3 mol 0.4 mol, sulfuric acid 0.3 mol, water 4 mol, 37%
0.9 mol of an aqueous formaldehyde solution was added dropwise at 80 ° C. over 3 hours. After completion of the dropwise addition, the mixture was heated to 105 ° C. and reacted for 10 hours, cooled, adjusted to pH 6 with a 50% aqueous sodium hydroxide solution, and allowed to stand. After standing, take the upper layer separated into two layers,
The solid content was adjusted to 30% by adding water to obtain a co-condensate having a molecular weight of 30,000.

Production Example 5 (Admixture symbol D-5) In a reaction vessel equipped with a stirrer, 0.1 mol of A-5, 0.8 mol of B-1 and 0.8 mol of C-
4 0.1 mol, water 4 mol, sulfuric acid 0.3 mol, 37%
0.9 mol of an aqueous formaldehyde solution was added dropwise at 80 ° C. over 3 hours. After completion of the dropwise addition, the mixture was heated to 105 ° C. and reacted for 10 hours, then cooled, adjusted to pH 6 with a 50% aqueous sodium hydroxide solution, and allowed to stand. After standing, take the upper layer separated into two layers,
The solid content was adjusted to 30% by adding water to obtain a cocondensate having a molecular weight of 29,000.

Production Example 6 (Admixture D-6) 0.2 mol of A-3, 0.7 mol of B-1 and C-
3 0.1 mol, sulfuric acid 0.3 mol, water 4 mol, 37%
0.9 mol of an aqueous formaldehyde solution was added dropwise at 80 ° C. over 3 hours. After completion of the dropwise addition, the mixture was heated to 105 ° C. and reacted for 10 hours, then cooled, adjusted to pH 6 with a 50% aqueous sodium hydroxide solution, and allowed to stand. After standing, take the upper layer separated into two layers,
The solid content was adjusted to 30% by adding water to obtain a cocondensate having a molecular weight of 18,000.

Production Example 7 (Admixture symbol D-7) (Comparative product) In a reaction vessel equipped with a stirrer, 0.1 mol of A-6, 0.5 mol of B-1 and C-
0.4 mol of 1, 7 mol of water, 0.3 mol of sulfuric acid, 37%
0.9 mol of an aqueous formaldehyde solution was added dropwise at 80 ° C. over 3 hours. After completion of the dropwise addition, the mixture was heated to 105 ° C. and reacted for 15 hours, cooled, adjusted to pH 6 with a 50% aqueous sodium hydroxide solution, and allowed to stand. After standing, take the upper layer separated into two layers,
The solid content was adjusted to 20% by adding water to obtain a cocondensate having a molecular weight of 23,000.

Production Example 8 (Admixture symbol D-8) (Comparative product) 0.1 mol of A-3, 0.6 mol of C-1 and 0.6 mol of C-1 in a reaction vessel equipped with a stirrer.
0.3 mol of 3, 7 mol of water, 0.3 mol of sulfuric acid, 37%
0.9 mol of an aqueous formaldehyde solution was added dropwise at 80 ° C. over 3 hours. After completion of the dropwise addition, the mixture was heated to 105 ° C. and reacted for 15 hours, cooled, adjusted to pH 6 with a 50% aqueous sodium hydroxide solution, and allowed to stand. After standing, take the upper layer separated into two layers,
The solid content was adjusted to 30% by adding water to obtain a co-condensate having a molecular weight of 19,000.

In addition to the polycondensate used as the comparative product, the contents and symbols of the comparative concrete admixture (high-performance water reducing agent) used in the examples are shown below. Symbol NS of admixture: Naphthalene admixture (Mighty 15
0; manufactured by Kao Corporation) Symbol of admixture MS: Melamine-based admixture (Mighty 150V-
2; Kao Corporation) Symbol of admixture PC: polycarboxylic acid admixture (Mighty
The evaluation method of the concrete admixture of the present invention and the comparative concrete admixture is shown below.

<Evaluation as a concrete admixture> The concrete mixing conditions are shown in Table 1 below.

[0046]

[Table 1]

For the concrete, according to the concrete composition shown in Table 1, the material and the admixture were mixed at 25 rpm × 3 with a tilting mixer.
It was prepared by kneading for minutes. After measuring the fluidity (slump value) by the JIS-A1101 method, the sample was further rotated at 4 rpm for a predetermined time, and the slump value (cm) up to 120 minutes was measured. The initial slump value was adjusted by adding amounts of the admixture of the present invention and the comparative admixture so that the initial slump value was 19.5 ± 1 cm. Table 2 shows the measurement results.

[0048]

[Table 2]

Note) * 1: Solid content conversion to cement * 2: Compound of present invention D-6 and comparative product D-8, compounding ratio = 50
/ 50 (%) * 3: Compound of the present invention D-1 and comparative product PC, compounding ratio = 40
/ 60 (%)

[0050]

As is clear from Table 2, the concrete admixture according to the present invention can maintain the slump value immediately after preparation for a long time. Therefore, if the concrete admixture of the present invention is added to the cement composition, the change in slump is small over a long period of time. Manufacturing and casting conditions,
Also, in the case where the concrete placement is delayed due to troubles such as traffic congestion, etc., the quality control of the concrete becomes easy.

Claims (12)

[Claims] 1. An oxyalkylene group having 2 to 3 carbon atoms.
Residues derived from the polycondensable monomer (A) having 300 moles and a polycondensable monomer having a carboxy monoester group
A concrete admixture comprising a polycondensate having a residue derived from (B) as an essential structural unit. 2. The polycondensate as an essential structural unit further comprising a residue derived from a polycondensable monomer (C) having at least one group selected from the group consisting of a carboxyl group and a sulfonic acid group. The concrete admixture of claim 1 having a group. 3. The polycondensate according to claim 1, wherein the polycondensate is the polycondensable monomer.
(A) and the polycondensable monomer (B) are (A) / (B) = 1 to 99/99
The concrete admixture according to claim 1, which is obtained by reacting at a molar ratio of -1. 4. The concrete admixture of claim 3, wherein said ratio is in the range of (A) / (B) = 10-50 / 50-90. 5. The polycondensate according to claim 1, wherein the polycondensate is the polycondensable monomer.
(A), the polycondensable monomer (B), and the polycondensable monomer
The concrete admixture according to claim 2, which is obtained by reacting (C) at a molar ratio of (A) / (B) / (C) = 1 to 98/1 to 98/1 to 98. 6. The concrete admixture of claim 5, wherein said ratio is in the range of 5-50 / 5-90 / 5-90. 7. The concrete admixture according to claim 1, wherein the polycondensable monomer (A) is a benzene ring or a naphthalene ring derivative. 8. The concrete admixture according to claim 7, wherein said polycondensable monomer (A) is an oxyalkylene group adduct of phenol. 9. The concrete admixture according to claim 1, wherein the polycondensable monomer (B) is a benzene ring or a naphthalene ring derivative. 10. The polycondensable monomer (B) represented by the general formula: (Wherein R _{1 is} an alkyl or alkenyl group having 1 to 18 carbon atoms or a hydroxyalkyl group having 2 to 6 carbon atoms), and the concrete is mixed with any one of claims 1 to 9. Agent. 11. The polycondensable monomer (C) is a naphthalene ring or benzene ring derivative having a carboxyl group or a sulfonic acid group, or a phenol derivative having a sulfonic acid group. Or 1 concrete admixture. 12. The polycondensate has a weight average molecular weight of 3,000.
12. The concrete admixture according to any one of claims 1 to 11, wherein the amount is from 0 to 100,000.