JP2001294463A - Powdery cement dispersant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powdery cement dispersant which can be mixed into a premix product beforehand and which is excellent in fluidity and fluidity retention properties. SOLUTION: This powdery dispersant contains an inorganic powder and a powder consisting of a multivalent metal salt of a copolymer, wherein the copolymer has a weight average molecular weight of 5,000-100,000 and is formed by copolymerizing: (A) 3-25 mol% a monomer represented by the general formula (1) CH2=C(R1)COO(R2O)nR3 (wherein: R1 is a hydrogen atom or methyl group; R2O is a 2-4C oxyalkylene group; n is an integer of 5-40; and R3 is a hydrogen atom or 1-5C alkyl group); (B) 55-75 mol% methacrylic acid or its salt; (C) 5-35 mol% a monomer represented by the general formula (2) CH2=C(R4)COOR5 [wherein: R4 is a hydrogen atom or methyl group; and R5 is a 1-5C alkyl group optionally subtituted by a hydroxyl group, or (R6O)mH (wherein: R6O is a 2-3C oxyalkylene group; and m is an integer of 1-3)]; and (D) 0-10 mol% of another monomer (s).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a powder cement dispersant for hydraulic compositions such as cement, mortar, concrete and the like, and more particularly, to a convenient and premixable premix product. The present invention relates to a powder cement dispersant having high fluidity and excellent fluidity and fluidity retention.

[0002]

2. Description of the Related Art In recent years, with the increasing interest in building structures, hydraulic and hydraulic compositions such as concrete and plaster mortar have high strength and high durability. There is a demand for higher performance. In this case, it is generally considered that a composition using a hydraulic material such as concrete or mortar is preferable because the lower the water cement ratio (W / C ratio), the higher the strength of the cured product.

[0003] However, water cement ratio (W / C ratio)
If the water-cement ratio is low, various cement dispersants are used to ensure good fluidity and workability even when the water-cement ratio (W / C ratio) is low.

[0004] Recently, as a cement dispersant having excellent fluidity even at a low water cement ratio (W / C ratio), a dispersion mainly composed of a polycarboxylic acid type polymer compound having an alkylene oxide chain is used. Agents have been proposed and are receiving attention.

However, since the polycarboxylic acid-based cement dispersant having an alkylene oxide chain is generally produced as an aqueous solution, it cannot be blended in advance with a premix product such as dry concrete or plastering material. It is. In addition, even if water is removed from its chemical structure and physicochemical properties, it becomes waxy or syrupy, and it is difficult to powder as it is like a naphthalene-based dispersant or a melamine-based dispersant. There is a problem.

For this reason, various methods for pulverizing a polycarboxylic acid-based dispersant have been proposed. For example, there has been proposed a powdery cement dispersant obtained by using a polycarboxylic acid copolymer and an inorganic powder in combination and spray-drying the same (Japanese Patent No. 266,761). Further, a method has been proposed in which the solubility of a polyvalent metal salt of a polyalkylene glycol alkenyl ether-maleic anhydride copolymer in water is reduced, and a powdered dispersant can be easily obtained (JP-A-9-309756). No.). Further, a powder cement dispersant using a water-soluble vinyl copolymer and an inorganic salt in combination has been proposed (JP-A-11-31044).
No. 4).

However, these powdered dispersants take a long time to dissolve the dispersant, or do not dissolve, resulting in lumps, failing to obtain desired performance, and as a premix product, a powder such as cement. When blended into body material,
There were problems such as classification.

[0008] The present invention has been made in view of the above problems, and is a powder cement having high convenience, excellent fluidity and excellent fluidity retention, which can be preliminarily blended into a premix product. It is intended to provide a dispersant.

[0009]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventor has found that a specific weight average molecular weight range obtained by copolymerizing the following specific monomers is obtained. The polyvalent metal salt of the copolymer can be easily formed into a powder without affecting the solubility, and by blending a specific inorganic powder with the powder, the dissolution time is shortened and the powder becomes lumpy. It was found that a powder polycarboxylic acid-based cement dispersant that was easy to mix with a premix product and had excellent cement dispersing power was obtained.

That is, (A) 3 to 25 mol% of a monomer represented by the following general formula (1): CH ₂ ＣC (R ¹ ) COO (R ² O) _n R ³ (1) In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² O is C 2
To 4 oxyalkylene group, n represents 5 to 40 integer, R ³
Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. )
(B) 55-75 mol% of methacrylic acid or a salt thereof,
(C) 5-35 mol% of a monomer represented by the following general formula (2): CH ₂ ＣC (R ⁴ ) COOR ⁵ (2) wherein R ⁴ is a hydrogen atom or a methyl group; ⁵ has 1 to 1 carbon atoms
An alkyl group which may be substituted with a hydroxyl group of (5) or (R
⁶ O) _m H (where R ⁶ O represents an oxyalkylene group having 2 or 3 carbon atoms, and m represents an integer of 1 to 3). And (D) a powder comprising a polyvalent metal salt of a copolymer having a weight average molecular weight in the range of 5,000 to 100,000 obtained by copolymerizing 0 to 10 mol% of another monomer, and an inorganic powder. The powder cement dispersant containing is excellent in powder stability and its fluidity, and excellent in miscibility with hydraulic substances such as cement,
Cement that can be mass-produced industrially without lumps,
The present inventors have found that it is the most suitable as a powder cement dispersant for hydraulic compositions such as mortar and concrete, and have accomplished the present invention.

Hereinafter, the present invention will be described in more detail. The powder cement dispersant of the present invention comprises (A) a monomer represented by the general formula (1), (B) methacrylic acid or a salt thereof, and (C) a monomer represented by the general formula (2). Monomer and
If necessary, (D) a powder comprising a polyvalent metal salt of a copolymer obtained by copolymerizing another monomer and an inorganic powder.

The monomer of the component (A) is represented by the following general formula (1). CH ₂ ＣC (R ¹ ) COO (R ² O) _n R ³ (1) Here, in the formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² O has 2 to 4 carbon atoms. oxyalkylene group, _{e.g., -CH 2 CH 2 O -,} - CH 2 CH 2 CH 2 O -, - C
_{H 2 CH (CH 3) O} -, - CH 2 CH (CH 2 CH 3) O
—, —CH ₂ CH ₂ CH ₂ CH ₂ O— and the like. n represents the number of moles of the oxyalkylene group added, and is an integer of 5 to 40, preferably 7 to 35, more preferably 9 to 3
0. If the number of moles added (n) is too small, the dispersing power becomes insufficient. On the other hand, if it is too large, it becomes a high melting point solid,
Handling becomes difficult.

R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group or a butyl group.

As the monomer of the component (A), polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polybutylene glycol mono (meth) having alkylene oxide addition mole number of 5 to 40 moles Acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, methoxypolybutylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, ethoxypolybutylene glycol (meth) Acrylate, propoxy polyethylene glycol (meth) acrylate, and the like.
More than one species can be used in combination

The amount of the component (A) monomer is 3 to 2
5 mol%, preferably 4 to 20 mol%, more preferably 5 to 17 mol%. If the amount of the component (A) monomer is too small, sufficient dispersing power cannot be obtained. on the other hand,
If it is too large, powdering becomes difficult.

The monomer of the component (B) is a monomer selected from methacrylic acid and salts thereof. For example, a monovalent metal salt such as methacrylic acid or sodium methacrylate, a divalent metal salt such as calcium methacrylate, an ammonium salt of methacrylic acid, an organic amine salt of methacrylic acid, and the like, and one of these alone or Two or more can be used in combination.

The amount of the monomer (B) is 55 to 55.
75 mol%. If the amount of the monomer (B) is too small, the amount of the dispersant adsorbed on the cement particles becomes too small, and the dispersing power becomes insufficient. On the other hand, if it is too large, the adsorbed amount of the dispersant to the cement particles becomes excessive, and the fluidity retention becomes insufficient.

The molar ratio (A) / (B) of the monomer of component (A) to the monomer of component (B) is preferably 0.05 to 0.4, more preferably 0 to 0.4. 0.05 to 0.3.

The monomer of component (C) is represented by the following general formula (2). CH ₂ ＣC (R ⁴ ) COOR ⁵ (2) Here, in the formula (2), R ⁴ is a hydrogen atom or a methyl group, and R ⁵ may be substituted with a hydroxyl group having 1 to ⁵ carbon atoms. A good alkyl group or (R ⁶ O) _m H. Carbon number 1
Examples of the alkyl group which may be substituted by the hydroxyl group of No. 5 include a methyl group, an ethyl group, a hydroxyethyl group, a propyl group, a hydroxypropyl group, a butyl group and the like.

Further, (R ⁶ O) _m H in R ⁶ O is 2 carbon atoms
Or shows a 3 oxyalkylene group, for example -CH ₂ C
_{H 2 O -, - CH 2} CH 2 CH 2 O -, - CH (CH 3) C
H ₂ O— and the like are exemplified, and m represents the number of moles of the added oxyalkylene group, and is an integer of 1 to 3.

The monomer of component (C) not only enables powdering of the copolymer polymer, but also imparts hydrophobic adsorbability to cement particles and also has a function of improving fluidity retention. It is. Examples of such a monomer of the component (C) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylate.
2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, and the like. Can be used alone or in combination of two or more.

The amount of the monomer (C) is 5 to 3
5 mol%. If the amount of the component (C) monomer is too small, powdering becomes difficult and the fluidity retention becomes insufficient. On the other hand, if the amount is too large, the amount of the monomer of the component (A) or the monomer of the component (B) is too small, and favorable performance cannot be obtained.

The other monomer of the above component (D) includes 2
-Methylpropanesulfonic acid (meth) acrylamide,
Styrenesulfonic acids and their monovalent metal salts such as sodium, divalent metal salts such as calcium, ammonium salts, organic amine salts, and the like. These may be used alone or in combination of two or more. it can.

The amount of the component (D) monomer is from 0 to 1
0 mol%, preferably 0 to 8 mol%.

The polycarboxylic acid-based copolymer constituting the powder cement dispersant of the present invention comprises the monomers of the above components (A) to (C) and, if necessary, the monomer of the component (D). It is obtained by copolymerization. The method for producing the copolymer is not particularly limited, and a known polymerization method such as solution polymerization or bulk polymerization using a polymerization initiator can be employed.

Examples of the solvent used in the polymerization include water, lower alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, aromatic and aliphatic hydrocarbons such as benzene, toluene, xylene and cyclohexane, and ketone compounds such as acetone and methyl ethyl ketone. And the like. Of these, water is preferred.

As the polymerization initiator in the case of performing aqueous solution polymerization, a metal salt or ammonium salt of persulfuric acid, hydrogen peroxide,
A water-soluble polymerization initiator such as azobis-2-methylpropionamidine hydrochloride can be used. Further, an accelerator such as sodium hydrogen sulfite and a chain transfer agent such as mercaptoethanol, mercaptoacetic acid and mercaptopropionic acid can be used in combination.

The thus obtained copolymer of the present invention has a weight average molecular weight of 5,000 to 100,000, particularly 2
It is preferably from 0000 to 80000. If the molecular weight is too small, sufficient dispersing power cannot be obtained. On the other hand, if it is too large, an agglomeration action is exhibited and the dispersing power is reduced.

As the polyvalent metal used for the salt of the copolymer,
Calcium, magnesium, aluminum and the like are preferred, but calcium is particularly preferred in terms of ease of production and price. Monovalent metal salts such as sodium and potassium are very sticky even when dried, tend to lump, and cannot be handled as powder.

The method for producing the polyvalent metal salt of the copolymer is not particularly limited, but a method in which methacrylic acid to be used for the polymerization is previously converted into a polyvalent metal salt and then copolymerized, or methacrylic acid or a part thereof is Na There are a method of reacting a copolymer solution using a salt with a polyvalent metal salt or hydroxide, and a method of ion-exchanging a copolymer salt solution with a polyvalent metal. In this case, in the polyvalent metal salt of the copolymer, at least 50% of the methacrylic acid is preferably a polyvalent metal salt, and particularly preferably 50 to 85%.

The method of pulverization is not particularly limited, but a method of evaporating a solution of the copolymer polyvalent metal salt to dryness and then pulverizing the same, a method of spray-drying the solution of the copolymer polyvalent metal salt, a method of spray drying, A solution of the polymer polyvalent metal salt can be produced by a method in which a powder is precipitated by dropping a solution of the polyvalent metal salt into a poor solvent for the copolymer, followed by filtration and drying. Of these, spray drying is preferred.

The average particle size of the powder of the polyvalent metal salt of the copolymer thus obtained is preferably 1.0 to 5000 μm.

Next, examples of the inorganic powder of the present invention include powders of inorganic salts such as calcium carbonate and calcium silicate;
Clay mineral powders such as kaolinite, bentonite and smectite, fine powders such as silicon dioxide, blast furnace slag, fly ash and silica fume can be used. By blending these inorganic powders, the flowability of the powder of the copolymer polyvalent metal salt can be improved.

The mixing ratio of the above-mentioned inorganic powder and the powder of the copolymer polyvalent metal salt is expressed by the weight ratio of the powder of the copolymer polyvalent metal salt to the powder.
Inorganic powder = 50 to 99.9 / 0.1 to 50, particularly preferably 75 to 99.9 / 0.1 to 25.
If the amount of the inorganic powder is less than the above range, the powder flowability of the copolymer polyvalent metal salt may be deteriorated. On the other hand, if the amount is too large, the active ingredient of the dispersing agent is diluted, and the amount of the added component is required to be large, which may be economically disadvantageous.

In the present invention, when the powder of the copolymer polyvalent metal salt and the inorganic powder are blended, the blending method is not particularly limited, and the blending can be carried out using a usual stirring device. Specifically, an inorganic powder may be added to the powder of the copolymer polyvalent metal salt, or a powder of the copolymer polyvalent metal salt may be added to the inorganic powder. Further, when the powder of the copolymer polyvalent metal salt is produced by the spray drying method, the inorganic powder is gradually added to the spray-dried copolymer polyvalent metal salt powder in the drying tower. It is also possible to use a method of introducing.

The amount of the powder cement dispersant of the present invention to be added to the cement is preferably 0.01 to 5.
0% by weight, and particularly preferably 0.02 to 2.0% by weight.

The powder cement dispersant of the present invention can be used in combination with a known cement admixture (material). Such cement admixtures include, for example, AE agent, AE
Water reducing agent, high performance water reducing agent, high performance AE water reducing agent, superplasticizer,
Setting retarder, early strength agent, defoamer, thickener, waterproofing agent (material),
Expanding agent (material), shrinkage reducing agent (material), silica sand, blast furnace slag,
Fly ash, silica fume, calcium carbonate and the like.

Examples of the air conditioners such as the AE agent and the defoaming agent include resin acids, α-olefin sulfonates,
Examples thereof include an alkylbenzene sulfonate, an alkyl sulfate, a nonionic antifoaming agent, a silicone antifoaming agent, and an acetylene antifoaming agent.

Examples of the cement dispersants such as the AE water reducing agent, the high performance water reducing agent, the superplasticizer, and the high performance AE water reducing agent include, for example, those containing lignin sulfonate or a derivative thereof as a main component, formalin naphthalene sulfonate. Condensates, melamine sulfonic acid formalin condensates, polystyrene sulfonic acid salts, maleic anhydride copolymers, acrylic acid copolymers, and the like can be given.

Examples of curing regulators (materials) such as the above-mentioned setting retarders and setting accelerators include sodium aluminate,
Sodium carbonate, sodium silicate, calcium aluminates, chlorine compounds such as calcium chloride, nitrates, nitrites, thiosulfates, thiocyanates, and other water-soluble compounds such as cellulose derivatives, polyvinyl alcohol, dextrin, and sodium polyacrylate Examples include a polymer, a hydroxyl group such as citric acid and 2-ketoglutaric acid, an organic acid having a carboxyl group, sugars such as glucose, sorbitol, saccharin, and sucrose, and oxycarboxylic acids such as sodium gluconate.

Further, the powder cement dispersant of the present invention can be added to cement, cement paste, dry mortar, mortar, dry concrete, concrete, etc. having hydraulic cement.

The powder cement dispersant of the present invention includes a high-performance AE water reducing agent, a high-performance water reducing agent, a superplasticizer, a slump recovery agent, a dispersant for pre-mixed mortar, SL (Self Lef).
leveling agent, repair agent, water stopping agent, dispersant for dry concrete, dispersant for soil cement, and the like.

[0043]

According to the polycarboxylic acid-based powder cement dispersant of the present invention, it can be easily used for premix products, and the convenience is improved. Further, it has excellent fluidity and fluidity retention with a small amount of addition as compared with conventional powder cement dispersants. That is, by mixing and integrating the polyvalent metal salt of the copolymer having the specific monomer molar ratio of the present invention and the inorganic powder at a specific ratio, the fluidity of the powder is maintained in a good state. Thus, it is possible to stably produce a powder cement dispersant having no lumps and good original performance as a cement dispersant.

[0044]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Examples and Comparative Examples Copolymers having the monomer compositions shown in Table 1 were produced by ordinary aqueous polymerization. Next, the obtained aqueous copolymer solution is p-pulped with calcium hydroxide.
The copolymer was neutralized to H6 to 8 to prepare a calcium salt sodium salt mixture aqueous solution of the copolymer. B-1 is an aqueous solution of a sodium salt of a copolymer obtained by neutralizing the copolymer using sodium hydroxide instead of calcium hydroxide.

[0046]

[Table 1] Weight average molecular weight (Mw): GPC measurement (in terms of polyethylene glycol) a: methoxypolyethylene glycol methacrylate (n = 23) b: mixture of 25 mol% of Na methacrylate and 75 mol% of methacrylic acid c: methyl methacrylate d: 2 -Acrylamide 2-methylpropanesulfonic acid Na salt

Next, the obtained A-1 to A-3, B-1 to
The aqueous solution of the copolymer metal salt of B-4 was spray-dried and powdered. In this case, ASIZAWA-
“TYD / SD-6. Made by NIRO ATOMIZER”
3N / R ”, and the exhaust air temperature from the drying tower is 90 to 9
While maintaining the temperature at 5 ° C., an aqueous solution of a metal salt of a polycarboxylic acid copolymer adjusted to a concentration of 27% by weight and a liquid temperature of 50 ° C. was spray-dried at a rate of 12 to 14 kg / h, and powdered. . The average particle size of the obtained powder was 40 to 60 μm.

Inorganic powders were added to the resulting polycarboxylic acid-based copolymer metal salt powder in the proportions shown in Table 2 to prepare Examples 1 to 3.
4, a powder cement dispersant of Comparative Example 5 was produced. In addition,
Comparative Examples 1 to 4 are powder cement dispersants containing no inorganic powder.

The obtained powder cement dispersant was evaluated for spray drying property, powder fluidity, stability over time and dispersibility by the following methods. Table 2 shows the results. Spray Drying At the time of spray drying, the degree of adhesion of the powder in the drying tower was visually evaluated according to the following criteria. Good: Almost no adhesion Poor: Large adhesion powder After blending the inorganic powder, the fluidity of the powder was visually evaluated according to the following criteria. Good: Smooth poor: Partial lumps stable over time The powder cement dispersant was allowed to stand at room temperature for 14 days and then visually evaluated according to the following criteria. Good: Maintains smoothness Poor: Some lump dispersibility (according to JIS R 5201) 900 g of cement, 1350 g of standard sand, 315 g of water, 0.9 g of powder cement dispersant are stirred and mixed for 3 minutes, and then mortar flow (mm) Was measured. When the mortar flow is 200 mm or more, the dispersibility is good.

[0050]

[Table 2] *: Compounding amount of inorganic powder with respect to 100 parts by weight of powder of copolymer metal salt Inorganic powder A: silica gel (manufactured by Kanto Chemical), average particle size 5 to 5
10 μm inorganic powder B: calcium carbonate (manufactured by Fimatec), average particle diameter 1-2 μm inorganic powder C: Toksil NP (manufactured by Tokuyama Corporation),
Average particle size 5 to 15 μm

From the results shown in Table 2, Comparative Examples 1 to 4 do not contain an inorganic powder and have poor spray-drying properties. In Comparative Example 5, since the amount of the monomer (C) was too large, the dispersibility was poor. Among them, Comparative Example 2 is B-1
Because of the use of Na salt, the sticking to the inside of the drying tower was severe due to stickiness, the productivity was extremely poor, and it could not be handled as powder. In contrast, Examples 1 to 4
Can be easily pulverized without the powder adhering to the drying tower, and it has been confirmed that blending of inorganic powder improves powder flowability and handling properties. did it.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 220/06 C08F 220/06 290/06 290/06 C08K 3/00 C08K 3/00 C08L 33/02 C08L 33/02 55/00 55/00 // (C08F 220/06 (C08F 220/06 220: 28) 220: 28) (C08F 220/06 (C08F 220/06 220: 12 220: 12 220: 28) 220 : 28) C04B 103: 32 C04B 103: 32 (72) Inventor Etsuo Tobori 1-37 Honjo, Sumida-ku, Tokyo F-term in Lion Corporation (reference) 4D077 AB20 AC05 BA02 BA07 DB06Y DB07Y DD16Y DD17Y DD18Y DD19Y DD59Y DE02Y DE10Y 4J002 BG071 BN181 DE236 DJ006 DJ016 FD016 FD200 GL00 4J027 AC02 AC03 AC04 AC06 BA04 BA06 BA07 BA08 BA14 CA18 CA20 4J100 AJ02P AK03P AK08P AK13P AL03R AL08Q AM05BA05 BA05BA06Q

Claims (1)

[Claims] (A) 3 to 25 mol% of a monomer represented by the following general formula (1): CH ₂ ＣC (R ¹ ) COO (R ² O) _n R ³ (1) In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² O is C 2
To 4 oxyalkylene group, n represents 5 to 40 integer, R ³
Represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. )
(B) 55-75 mol% of methacrylic acid or a salt thereof,
(C) 5-35 mol% of a monomer represented by the following general formula (2): CH ₂ ＣC (R ⁴ ) COOR ⁵ (2) wherein R ⁴ is a hydrogen atom or a methyl group; ⁵ has 1 to 1 carbon atoms
An alkyl group which may be substituted with a hydroxyl group of (5) or (R
⁶ O) _m H (where R ⁶ O represents an oxyalkylene group having 2 or 3 carbon atoms, and m represents an integer of 1 to 3). And (D) a powder comprising a polyvalent metal salt of a copolymer having a weight average molecular weight in the range of 5,000 to 100,000 obtained by copolymerizing 0 to 10 mol% of another monomer, and an inorganic powder. A powder cement dispersant comprising: