JPH07172888A - Mixing agent for cement - Google Patents

Abstract

PURPOSE:To obtain a mixing agent for hydraulic cement having excellent properties as a dispersing agent, a water reducing agent, a fluidizing agent or the like by incorporating polyaspartic acid and its derivative as effective components. CONSTITUTION:The mixing agent for cement contains polyaspartic acid and its derivative as the effective components. The molecular weight of polyaspartic acid and its derivative is preferably 1000-100000 by weigh average molecular weight. The sufficient water reducing effect is not exhibited when molecular weight is <=3000 and the reverse effect is generated owing to the increase in viscosity when the molecular weight is >=100000. The molecular weight of 3000-50000 is particularly preferable. The quantity of polyaspartic acid and its derivative to be added is usually 0.01-2.0wt.%, preferably 0.05-1.0wt.%. Both alpha-isomer and beta-isomer of polyaspartic acid and its derivative and also the mixture of both isomers are used.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel admixture for hydraulic cement. More specifically, the present invention relates to a novel hydraulic cement admixture having excellent properties as a dispersant, a water reducing agent, a fluidizing agent, and the like.

[0002]

2. Description of the Related Art Generally, an admixture is generally used to improve dispersibility, fluidity, etc. when producing concrete, mortar, paste, etc. using cement. The performance and effect of the admixture for concrete are not necessarily single, but have some secondary effects. In addition, the performance required for concrete is diversified, and the classification of admixtures is diverse. JIS A
In 6204 (chemical admixture for concrete), the following are specified among these various admixtures.

1) AE agent: The purpose is to improve the workability and frost damage resistance by generating a large number of independent fine bubbles in concrete. 2) Water-reducing agent: The purpose is to improve the workability by dispersing the cement particles in the concrete, and to reduce the amount of unit water and the amount of cement required to obtain a predetermined consistency and strength. 3) AE water reducing agent: Combines the effects of both the AE agent and the water reducing agent. Furthermore, AE agents and water reducing agents are classified into standard type, delayed type, and accelerated type depending on the difference in setting time.

Conventionally, as typical examples of such an admixture, a naphthalene sulfonic acid formaldehyde condensate and a melamine sulfonic acid formalin condensate admixture have been known.
In addition, olefin-α, β-
There is also known a method of using an unsaturated dicarboxylic acid copolymer system (hereinafter sometimes simply referred to as polycarboxylic acid system) admixture (Japanese Patent Publication No. 56-12268, etc.). Also, lignin sulfonate, which is a natural polymer, is used.

[0005]

However, the coarse particle dispersion system is thermodynamically unstable, and agglomeration and sedimentation of cement particles occur and slump loss occurs. It is hard to say that the above-mentioned conventional techniques sufficiently satisfy the required performances for dispersion fluidity and slump retention in recent years, and improvements thereof are strongly desired.

[0006]

The inventors of the present invention have made extensive studies to overcome the above-mentioned drawbacks. As a result, when polyaspartic acid and its derivatives were used as an admixture, polycarboxylic acids known in the prior art were used. The inventors have found that a cement composition having excellent dispersion fluidity and workability of cement and excellent slump retention property can be obtained as compared with the case of using a system admixture, and completed the present invention. That is, the present invention relates to a cement admixture containing polyaspartic acid and its derivative as an active ingredient.

The weight average molecular weight of polyaspartic acid and its derivatives used in the present invention is Mw = 1,00.
0 to 100,000 is preferable. If the molecular weight is less than this, sufficient water reducing effect is not exhibited. On the other hand, if the molecular weight is higher than this, the viscosity is increased, which is the opposite effect. Particularly preferably, Mw = 3,
It is 000 to 50,000. The amount of polyaspartic acid and its derivative to be added is not particularly limited, but is usually 0.
01-2.0 wt%, preferably 0.05-1.
It is 0 wt%. Polyaspartic acid and its derivatives have α and β isomers, and either of them can be used. Also, a mixture of both may be used. The polyaspartic acid and its derivative may be a D- or L-form homopolymer or a D- or L-form copolymer. The polyaspartic acid and its derivative may be not only a homopolymer of aspartic acid, but also a copolymer of aspartic acid and other amino acids such as glutamic acid.

Examples of the polyaspartic acid derivative are as follows. Polyaspartic acid salt, those in which all or part of the side chain carboxyl groups of polyaspartic acid are amide-bonded with substituted amines, and all or part of the side chain carboxyl groups of polyaspartic acid are substituted alcohols and esters For example, they are combined. Examples of the salt of polyaspartic acid include sodium polyaspartate, alkali metal salts of polyaspartic acid such as potassium polyaspartate, ammonium salts of polyaspartic acid, polyaspartic acid triethylamine salt, polyaspartic acid triethanolamine salt and other polyaspartic acid salts. Examples include salts of organic bases.

Substituted amines that form an amide bond with the side chain carboxyl group of polyaspartic acid include butylamine, dodecylamine, 2-aminoethanol, 3-amino-1propanol, 1-amino-2-propanol,
Aliphatic primary amines such as 2-methoxyethylamine, 3-ethoxypropylamine and 2,2-dimethoxyethylamine, diethyl secondary amines such as diethylamine, diisopropylamine, dibutylamine, diethanolamine and N-methylethanolamine, and ethylenediamine. , 1,
2-propanediamine, 1,3-propanediamine,
1,4-diaminobutane, hexamethylenediamine,
Aliphatic diamines such as N, N-dimethyl-1,3-propanediamine, triamines such as diethylenetriamine, norbornenediamine, isophoronediamine, alicyclic amines represented by piperazine, glycine, alanine, aspartic acid, lysine, tyrosine, etc. -Representatives such as α-amino acids and esters thereof, taurine, β-alanine, γ-aminobutyric acid, 6-aminocaproic acid and other derivatives of amino acids and esters thereof, peptides represented by glycyl-glycine, aniline And aromatic diamines represented by.

Examples of the substituted alcohols which form an ester bond with all or part of the carboxyl group of the side chain of polyaspartic acid include aliphatic alcohols represented by methanol and ethanol, amino alcohols such as aminoethanol and diaminoethanol, and the like. To be

The method for producing polyaspartic acid and its salt is not particularly limited, but generally it can be produced by hydrolyzing polysuccinimide obtained by dehydration condensation of aspartic acid in the presence of phosphoric acid. The method for producing a compound in which the carboxyl group of the side chain of polyaspartic acid is amide-bonded with a substituted amine is not particularly limited, but generally, polysuccinimide, which is a precursor of polyaspartic acid, is directly opened by a substituted amine. Can be manufactured. The method for producing a compound in which the side chain carboxyl group of polyaspartic acid is ester-bonded with a substituted alcohol is not particularly limited, but is produced by heating polyaspartic acid and a substituted alcohol in the presence of a mineral acid such as hydrochloric acid or sulfuric acid. it can.

The polyaspartic acid and its derivatives may be used alone or in combination with other admixtures such as melamine sulfonic acid formalin condensate admixtures. The timing of addition to the cement mixture can be appropriately selected depending on the purpose of use. For example, a method of premixing with cement, a method of simultaneously adding the cement mixture such as concrete at the time of kneading, a method of adding water or another admixture after stirring is started, an appropriate method after kneading the mixture in advance. Examples include a method of adding after a certain interval, and the like.

The type of cement to which the admixture of the present invention can be applied is not particularly limited, and examples thereof include ordinary Portland cement, early strength Portland cement, alumina cement, fly ash cement, blast furnace cement, silica cement and various mixed cements.

[0014]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples. Example 1 100 g of Portland cement, 26 g of water, and 1 g of sodium polyaspartate having a weight average molecular weight (hereinafter Mw) of 310,000 were hand kneaded in a polycup, placed on a flow table, and tapped 15 times to measure the flow value. .

Example 2 3 g of polysuccinimide having Mw = 68,000 was dissolved in 15 ml of DMF, 4.5 ml of ethanolamine was added dropwise, and the reaction was carried out at room temperature for 4 hours. The reaction solution was neutralized with acetic acid, desalted by dialysis, and lyophilized to obtain the target poly [(2-hydroxyethyl) aspartamide].
1 g of this poly [(2-hydroxyethyl) aspartamide] having a weight-average molecular weight of 42,000, 100 g of Portland cement, and 26 g of water were hand kneaded in a polycup, then placed on a flow table and tapped 15 times to measure the flow value. .

Example 3 5 g of polysuccinimide having a weight average molecular weight of 68,000
Was dissolved in 25 g of DMF, 4.6 g of glycine methyl ester was added, 1 equivalent of triethylamine was added, and the reaction was carried out for 26 hours at room temperature. The reaction solution was discharged into ethanol, and the obtained precipitate was filtered and dried to obtain a compound in which the side chain carboxyl group of polyaspartic acid was amide-bonded with glycine methyl ester. The weight average molecular weight was 32,000. 1 g of the compound, 100 Portland cement
g and 26 g of water were kneaded in a poly cup, and then placed on a flow table and tapped 15 times to measure the flow value.

Example 4 Polysuccinimide having a weight average molecular weight of 108,000 was added to water 2
7 g, and to this suspension was added 3.9 g of taurine in 30 g of water.
A solution obtained by dissolving g and neutralizing the sulfonic acid group with an aqueous NaOH solution was slowly added dropwise while adjusting the pH to 9 to 9.5. It dissolved completely after 2 hours. The solution was discharged into 400 ml of ethanol, and the obtained precipitate was filtered and dried to obtain a compound in which the side chain carboxyl group of polyaspartic acid was bound to taurine with an amide bond. The weight average molecular weight was 46,000. 1 g of the compound, 100 Portland cement
g and 26 g of water were kneaded in a poly cup, and then placed on a flow table and tapped 15 times to measure the flow value.

Example 5 Polyaspartic acid having a weight average molecular weight of 310,000 was suspended in ethanol, and the polyaspartic acid was suspended in the presence of 98% sulfuric acid in a molar ratio of 1.8.
The reaction was carried out at 70 ° C for 20 hours. The reaction solution was neutralized with an aqueous NaOH solution, desalted by dialysis, and then freeze-dried to obtain the target polyaspartic acid ethyl ester. 1 g of this polyaspartic acid ethyl ester having a weight average molecular weight of 28,000, 100 g of Portland cement, 26 water
After g was hand kneaded with a poly cup, it was placed on a flow table and tapped 15 times to measure the flow value.

Comparative Example 1 100 g of Portland cement and 26 g of water were hand kneaded in a polycup, placed on a flow table and tapped 15 times to measure the flow value. Comparative Example 2 1 g of a melamine sulfonic acid formalin condensate cement admixture, 100 g of Portland cement, and 26 g of water were hand-kneaded in a polycup, placed on a flow table, and tapped 15 times to measure the flow value. Examples 1-5,
The results of Comparative Examples 1 and 2 are shown in Table-1 (Table 1).

[0020]

[Table 1]

[0021]

EFFECTS OF THE INVENTION By using a hydraulic cement admixture containing polyaspartic acid and its derivative as an active ingredient, a cement composition having excellent water-reducing property, dispersion fluidity and slump retention property can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Yamaguchi 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (3)

[Claims] 1. An admixture for hydraulic cement, which comprises polyaspartic acid and its derivative as an active ingredient. 2. The polyaspartic acid and its derivative have a weight average molecular weight of 1,000 to 100,000.
The admixture for cement according to claim 1, which is 3. The admixture for cement according to claim 2, wherein the polyaspartic acid and its derivative have a weight average molecular weight of 3,000 to 50,000.