JP2000327386A - Cement dispersant and hydraulic composition including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dispersant capable of imparting excellent dispersibility and high fluidity in a small quantity consumed irrespective of a formulation ratio of a hydraulic substance to water, hardly causing setting retardation and capable of imparting highly strong hardened product by including a polymer obtained from a monoester or monoether each having a polyalkylene glycol chain and a comonomer having at least one unsaturated bond and phosphoric acid group as a principal ingredient. SOLUTION: This dispersant comprises a copolymer obtained from a monomer having at least one phosphoric acid group expressed by formula I [e.g. mono(2-hydroxyethyl)methacryl phosphate] and a comonomer having a polyoxyalkylene group expressed by formula II; wherein R1 to R3 are each H, a 1-3C alkyl, COOH or CH2COOH; X is CO or CH2; AO is a 2-4C oxyalkylene; Y is H, an alkali (or alkaline earth) metal, ammonium, an alkylammonium or a 1-3C alkyl; (j) is 0-2; (k) is 1 or 2; (m) is 0-5; (n) is 5-200 and; (i) is 3-(k) (ω-methoxy polyoxyethylene methacrylate) as a principal ingredient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersant for cement which prevents aggregation of a hydraulic substance such as cement when added with water and increases the viscosity of a paste, and a hydraulic composition to which the dispersant is added. More specifically, the present invention relates to a dispersant for cement which exhibits excellent flow characteristics, a high dispersing effect, and a fast setting property with a small amount of addition.

[0002]

2. Description of the Related Art Generally, cement paste, mortar,
In hydraulic compositions such as concrete, the smaller the amount of water relative to hydraulic substances such as cement, the better the strength development and durability after curing can be obtained, but the fluidity before curing decreases. easy. For this reason, even if the amount of water is small, an admixture such as a fluidizing agent or a water reducing agent is blended and used so that desired fluidity can be secured. The admixture used when the mixing ratio of water is small is generally a naphthalene-based water reducing agent such as a naphthalene sulfonic acid formalin cocondensate, a melamine water reducing agent such as a melamine sulfonic acid formalin cocondensate, or an aqueous solution such as a carboxylic acid monomer. It is known that a polycarboxylic acid-based water reducing agent composed of a water-soluble vinyl copolymer exhibits relatively high fluidity.

[0003] Of these, the naphthalene-based water reducing agent and the melamine-based water reducing agent require a considerably large amount of their own blending in order to enhance the fluidity. Further, the amount of the existing polycarboxylic acid-based water reducing agent can be suppressed to a low level, but the adsorbing ability to the hydraulic powder substance is relatively low, and the dispersing action is inferior. Therefore, as an improved product in which the dispersibility of a polycarboxylic acid-based water reducing agent is improved, a polymer in which the amount of an adsorbing group such as a carboxyl group or a sulfonic acid group in the polymer or the monomer structure to be copolymerized is changed is disclosed in, for example, 226557, JP-A-5-310458, JP-A-7-109156, JP-A-7-223852, JP-A-8-12396, JP-A-9
-278505, and JP-A-10-194809.

[0004]

However, since the above adsorbing group has a large effect of delaying the hydration reaction of a hydraulic substance, the use of a polycarboxylic acid-based water reducing agent containing such an adsorbing group is important. In addition, since the curing speed becomes slow, problems such as a long time required for demolding of a molded article from a mold, a long setting time and a large amount of bleeding water are likely to occur.

[0005]

Means for Solving the Problems The present inventors adsorb a copolymer exhibiting a high fluidity action to a hydraulic substance by using a phosphate group as an adsorption medium, and make use of a steric hindrance effect of a polyoxyalkylene group. Since the hydraulic substance can be strongly dispersed, such a specific polymer having a phosphate group and a polyoxyalkylene group has excellent fluidity with a small amount of addition to a composition containing at least a hydraulic substance and water. The present inventors have found that they can be expressed and have a small setting delay, and have completed the present invention.

That is, the present invention provides a cement dispersant represented by the following (a) to (d) and a hydraulic composition represented by the following (e) containing the same. (B) a monoester or monoether having a polyalkylene glycol chain;
A dispersant for cement containing a polymer of a monomer having an unsaturated bond and a phosphate group as a main component. (B) The cement dispersant according to the above (a), which mainly comprises a polymer having at least the structural units represented by the formulas (1) and (2) in the molecule.

[0007]

Embedded image

Wherein R ¹ , R ² and R ³ are the same or different and each represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, —COO
H represents —CH ₂ COOH, and X represents —C ＝ O or —C
Indicates H _2, AO represents an oxyalkylene group having 2 to 4 carbon atoms, Y is a hydrogen atom, an alkali metal, alkaline earth metal, ammonium, alkylammonium or 1 carbon atoms
And j represents an integer of 0 to 2;
Represents 1 or 2; m represents an integer of 0 to 5;
It represents an integer of 200, and i represents 3-k. ]

(C) Formula (3) and / or (4) in the molecule
The cement dispersant according to the above (a) or (b), which comprises a polymer having the structural unit represented by the formula as a main component.

[0010]

Embedded image

Wherein R ¹ , R ² and R ³ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, —COO
H or —CH ₂ COOH, and R ⁴ represents —CH ₂ —, —C ₂
H ₄ —, —C ₆ H ₄ — or —CH ₂ 0—C ₆ H ₄ —;
Represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, an alkyl ammonium or an alkyl group having 1 to 3 carbon atoms. ]

(D) The weight average molecular weight of the polymer is 3000
(I) characterized in that it is ~ 500,000.
The dispersant for cement according to any of (c). (E) The above (a)
A hydraulic composition comprising the cement dispersant according to any one of (1) to (4) in a solid content of 0.01 to 1.0 part by weight and 100 parts by weight of an inorganic hydraulic substance.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The dispersant for cement according to the present invention is mainly composed of a polymer obtained by copolymerizing a monomer having a phosphoric acid group and a monomer having a polyoxyalkylene group. It is. As the monomer having a phosphate group,
Any monomer having the structural unit of the formula (1) may be used,
For example, mono (2-hydroxyethyl) methacrylic acid phosphate, di- (2-hydroxyethyl) methacrylic acid phosphate, mono (2-hydroxymethyl) methacrylic acid phosphate, mono (2-hydroxypropyl) methacrylic acid phosphate, mono (2) phosphoric acid ester -Hydroxyethyl) acrylic ester, mono (2-hydroxyethyl) allyl ether phosphate and the like, and alkali metal salts, alkaline earth metal salts, ammonium salts and alkylammonium salts of these compounds. good. Here, k in the formula (1) is 1 or 2. When k is 2, a cross-linking reaction occurs at the time of copolymerization, and when the cross-linked structure becomes dominant, the initial flow developability tends to decrease. Therefore, it is preferable that the upper limit of the molar content ratio when k is 2 is 70%.

The monomer having a polyoxyalkylene group may be any monomer having the structural unit of the above formula (2). Examples thereof include ω-methoxypolyoxyethylene methacrylic ester and ω-methoxypolyalkylene. Oxyethylene acrylic ester, ω-methoxypolyoxyethylene allyl ether, ω-methoxypolyoxyethylene methacryl ester, ω-methoxypolyoxypropylene methacryl ester, ω-methoxypolyoxypropylene allyl ether and the like can be mentioned. here,
(2) In the formula, n is preferably from 5 to 200, and more preferably n is from 10 to 100. If n is less than 5, the dispersibility decreases, and if n exceeds 200, the viscosity of the hydraulic composition increases, which is not preferable. Further, the repeating unit n may include a different A.

In the copolymerization of the monomer, 0.1 to 4 mol of the monomer having the structural unit of the formula (1) is copolymerized with respect to 1 mol of the monomer having the structural unit of the formula (2). It is preferable to allow the reaction. When the reaction amount of the monomer having the structural unit of the formula (1) is less than 0.1 mole per 1 mole of the monomer having the structural unit of the formula (2), the adsorptive power becomes poor, which is preferable. If the reaction amount exceeds 4 mol, the adsorption capacity becomes excessive and the fluidity decreases with time, which is not preferable.

Further, the dispersant for cement of the present invention is mainly composed of a polymer having at least the structural units represented by the above formulas (1) and (2) in the molecule.

The dispersant for cement of the present invention has the structural units of the above formulas (1) and (2) and is expressed by the formulas (3) and / or (4). The main component may be a polymer having the structural unit to be formed.

Such a dispersant for cement comprises a monomer having a structural unit represented by the formula (3) and / or (4), and a structural unit represented by the formulas (1) and (2). It can also be obtained by copolymerizing with a monomer having the same.
(3) As the monomer having the structural unit represented by the formula,
For example, allyl sulfonic acid, methallyl sulfonic acid, any of these alkali metal salts, alkaline earth metal salts, ammonium salts, or amine salts can be used. (3)
The structural unit represented by the formula exhibits an action as a chain transfer agent, and is useful for adjusting the molecular weight of the copolymer. Also,
(4) As the monomer having the structural unit represented by the formula,
For example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and the like, and any one or more of these alkali metal salts, alkaline earth metal salts, ammonium salts, An amine salt, a methyl ester, an ethyl ester or an anhydride compound such as maleic anhydride may be used. Further, a monomer having both the structural units of the formulas (3) and (4) may be copolymerized with the monomer having the structural units of the formulas (1) and (2). In the copolymerization reaction from each monomer, the content of the monomer having the structural unit represented by the formula (3) with respect to all the reactive monomers should be 50% or less in terms of mole fraction. It is desirable to increase the initial fluidity, and the content of the monomer having the structural unit represented by the formula (4) with respect to all the reactive monomers should be 80% or less in terms of mole fraction to reduce the setting delay effect. It is desirable in doing.

Still further, the dispersant for cement of the present invention comprises:
The main component may be a copolymer comprising a monomer having at least the structural units of the above formulas (1) and (2) and another monomer having an unsaturated bond. Examples of such other monomers include (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2- (meth) acrylamide-2-methsulfonic acid, (Meth) acrylamide-2-ethanesulfonic acid, 2- (meth) acrylamide-2-propanesulfonic acid, styrene, styrenesulfonic acid, and the like.

The weight average molecular weight of the copolymer as the main component of the dispersant for cement of the present invention is preferably from 3,000 to 500,000. If the weight average molecular weight is less than 3,000, the contained phosphoric acid groups become insufficient, and the adsorptive power to hydraulic substances generally decreases, which is not preferable. On the other hand, if the weight average molecular weight exceeds 500,000, the viscosity after adding water is considerably increased, which is not preferable. In addition, the present dispersant may contain, for example, a known solvent or the like as a component other than the main component, in addition to any of the copolymers as the main component.

Further, any of the copolymers of the present invention can be synthesized by subjecting the above monomers to a known copolymerization reaction. The polymerization initiator used in the copolymerization reaction is not particularly limited as long as it decomposes below the copolymerization reaction to generate radicals. As an example, ammonium persulfate, persulfates such as potassium persulfate, hydrogen peroxide,
2,2-azobis (2-amidinopropane) dihydrochloride can be mentioned.

The dispersant for cement of the present invention can be used for various cements and other inorganic hydraulic materials which show curability by a hydration reaction. The compounding amount of the present dispersant is preferably 0.01 to 1.0 part by weight in terms of solid content concentration based on 100 parts by weight of the hydraulic substance. More preferably, it is 0.02 to 1.0 part by weight. If the amount of the dispersant is less than 0.01 part by weight, the dispersing effect is hardly exhibited, and if it exceeds 1.0 part by weight, setting delay may occur, which is not preferable. The addition amount of water required for the hydration reaction may be appropriately selected according to the hydraulic substance. For example, in the case of ordinary Portland cement, a relatively small amount of about 18 to 30 parts by weight relative to 100 parts by weight of the cement is used. Even with water, good fluidity can be obtained by introducing the dispersant. The hydraulic composition of the present invention containing such a cement dispersant and an inorganic hydraulic substance as constituents contains a mixture of other known cement-concrete admixtures and aggregates. Is also good.

[0023]

The present invention will be described below in detail with reference to examples. [Synthesis Example] ω-methoxypolyoxyethylene monomethacrylate (additional mole number of ethylene oxide: 23) 94
g, sodium methallylsulfonate 8.8 g, and water 1
80 g was placed in a glass reaction vessel and dissolved, and then 24 g of a mixture of 1 mol of di (2-hydroxyethyl) methacrylic acid phosphate and 2.7 mol of mono (2-hydroxyethyl) methacrylic acid phosphate was added. 30 more
7. The pH is adjusted to 8.
Adjusted to 5. After replacing the air in the reaction vessel with argon gas, 9.0 g of 20% by weight ammonium persulfate was gradually added with stirring, and the reaction was carried out at 60 ° C. for 4 hours to obtain a copolymer (No. 1). . The weight average molecular weight of this copolymer was 37,100 as determined by gel permeation chromatography (separation liquid: 50 mM NaNO ₃ , molecular weight standard: polyethylene glycol). Various copolymers (No. 2 to No. 8) were produced using the monomers shown in Table 1 as raw materials by the same synthesis method. In addition, No. measured by the same method as described above. 2-No. Table 1 also shows the weight average molecular weight of the copolymer No. 8.

[0024]

[Table 1]

[Preparation of Cement Composition] The above composition was synthesized into a composition comprising 100 parts by weight of ordinary Portland cement, 150 parts by weight of fine aggregate (crushed limestone sand having a coarseness ratio of 2.68) and 32.5 parts by weight of water. No. 1 to No. 8 as a dispersant (in terms of solid weight relative to 100 parts by weight of ordinary Portland cement) was added, and the mixture was kneaded for about 3 minutes to obtain a cement composition (the product of the present invention). 1 to 8) were produced. By the method according to JIS R5201, immediately after the completion of kneading of each cement composition,
In addition, the mortar 0 hit flow after 60 minutes of kneading, and the compressive strength of the test specimens (40 × 40 × 160 mm) after 1 day and 7 days of age were measured. Table 2 shows the results. In addition, as a comparative example, a commercially available lignin-based water reducing agent, a naphthalenesulfonic acid-based water reducing agent, and a melamine-based water reducing agent were all used in a mixture of ordinary Portland cement, fine aggregate and water having the same material and compounding ratio as described above. Table 2 shows polycarboxylic acid-based water reducing agents.
The same method as described above was applied to a cement composition (reference products 1 to 4) prepared by adding the amount described in (1) (in terms of solid content weight relative to 100 parts by weight of ordinary Portland cement).
Table 2 also shows the results of the mortar zero-strike flow and the compressive strength measured under the conditions.

[0026]

[Table 2]

[Preparation of gypsum composition] No. 1 was synthesized into a composition comprising 100 parts by weight of hemihydrate gypsum and 70 parts by weight of water. 1 to
No. 8 was used as a dispersing agent, and 0.1 in terms of solid content.
After adding 025 parts by weight and kneading for about 1 minute, gypsum compositions (Products 9 to 16 of the present invention) were prepared. The gypsum composition immediately after kneading was placed on an acrylic flat plate with a diameter of 50 mm and a height of 15 mm.
mm into a cylindrical tube, immediately pull up the cylindrical tube, measure the diameter (flow value) of the gypsum composition spread on a flat plate,
Further, the setting time was measured as the setting time by a method according to JIS R5201. The results are shown in Table 3. Further, as a comparative example, 100 parts by weight of hemihydrate gypsum and water 7
The amounts of the commercially available naphthalene sulfonic acid-based water reducing agent, melamine-based water reducing agent, and polycarboxylic acid-based water reducing agent are shown in Table 3 (in terms of the solid content weight per 100 parts by weight of gypsum hemihydrate) in the formulation consisting of 0 parts by weight. Table 3 shows the flow values and the setting times of the gypsum compositions (reference products 5 to 7) prepared by the addition and measured by the same method and conditions as described above.

[0028]

[Table 3]

[0029]

Industrial Applicability The dispersant for cement of the present invention can be used regardless of the mixing ratio of a hydraulic substance such as cement or gypsum to water.
With a relatively small amount of use, good dispersibility and high fluidity can be imparted, and there is little setting delay, and the use of the dispersant makes it possible to easily obtain a high-strength hydraulic composition cured product. it can.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) // C04B 103: 32

Claims (5)

[Claims] 1. A cement dispersant comprising a polymer of a monoester or monoether having a polyalkylene glycol chain and a monomer having an unsaturated bond and a phosphate group as a main component. 2. At least one of the formulas (1) and (2) in a molecule
The dispersant for cement according to claim 1, comprising a polymer having a structural unit represented by the formula as a main component. Embedded image [Wherein, R ¹ , R ² and R ³ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, -COOH or -CH
₂ COOH, X represents CO or CH ₂ , AO represents an oxyalkylene group having 2 to 4 carbon atoms, Y represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium,
An alkylammonium or an alkyl group having 1 to 3 carbon atoms, j represents an integer of 0 to 2, k represents 1 or 2,
m represents an integer of 0 to 5, n represents an integer of 5 to 200, and i represents 3-k. ] 3. The cement dispersant according to claim 1, wherein the dispersant for a cement mainly comprises a polymer having a structural unit represented by the formula (3) and / or (4) in the molecule. Embedded image [Wherein, R ¹ , R ² and R ³ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, -COOH or -CH
₂ COOH, and R ⁴ represents —CH ₂ —, —C ₂ H ₄ —, —C ₆
H ₄ — or —CH ₂ O—C ₆ H ₄ —, wherein Y is a hydrogen atom,
It represents an alkali metal, an alkaline earth metal, ammonium, alkyl ammonium or an alkyl group having 1 to 3 carbon atoms. ] 4. A polymer having a weight average molecular weight of 3000 to 5
The dispersant for cement according to any one of claims 1 to 3, wherein the dispersant is 00000. 5. The cement dispersant according to claim 1, which contains 0.01 to 1.0 part by weight of a solid component concentration and 100 parts by weight of an inorganic hydraulic substance. Hydraulic composition.