JP2002362952A - Production process of cement dispersant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a high-performance cement dispersant having a narrow molecular weight distribution in a short time with simple operation without requiring any special device. SOLUTION: This production process of the (meth)acrylic acid-based cement dispersant comprises charging all reactant materials which include a monomer mixture containing a polyalkyleneglycol mono(meth)acrylate-based monomer and (meth)acrylic acid, a polymerization initiator and water, into a reaction vessel so that the solid concentration in the resulting mixture of all the reactant materials is 50-90 wt.%, and subjecting the charged reactant material mixture to reaction at a 42-70 deg.C polymerization temperature, preferably, while raising the temperature stepwise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a (meth) acrylic acid-based cement dispersant having high concentration and high performance with high productivity.

[0002]

2. Description of the Related Art As a conventional method for producing a (meth) acrylic acid-based cement dispersant (a polymer synthesized from (meth) acrylic acid and polyalkylene glycol mono (meth) acrylate), Method using an organic solvent as a solvent (JP-B-59-18338)
However, recovery of the organic solvent is required, and there is a problem in productivity and safety. Further, a method of dropping a monomer mixture or a mixture of a monomer mixture and a chain transfer agent into a reaction vessel containing water (JP-A-9-86990); and a mixture of a monomer mixture and a chain transfer agent In a reaction vessel containing water, a method of dropping a chain transfer agent before and after dropping a mixture solution (Japanese Patent Laid-Open No. 2000-159555) is disclosed. In order to increase the concentration, the compound is synthesized in a state of being diluted with water to a solid concentration of 10 to 50%, so that there is a problem that the production efficiency is low.

In order to industrially and inexpensively produce a polycarboxylic acid cement dispersant, it is important to produce it at a high concentration. As a high-concentration polymerization method, a method has been disclosed in which a monomer mixture and a chain transfer agent are charged into a tank reactor, and a polymerization initiator is dropped at a solid content concentration of 50% or more (Japanese Patent Laid-Open No. 2000-16849). However, in this production method, there was a problem that the molecular weight distribution of the obtained polymer was broad and the water reducing performance was reduced.

Further, a method has been proposed in which a monomer mixture is charged in a reactor in advance, and the remaining monomer mixture is charged into the reactor after the start of polymerization (JP-A-2001-2734).
In this production method, a monomer mixing tank, a quantitative supply device, and the like are required, so that the cost of the device is increased, and since the reaction is performed at a polymerization temperature of 80 ° C., a polymer having a low dispersing power is generated, and a cement dispersing agent is produced. However, there is a problem that the performance of the device is reduced.

[0005]

Under such circumstances, the present inventors have conducted intensive studies and found that unexpectedly, when a polymerization initiator is added to a monomer mixture in advance and the reaction is carried out, the molecular weight distribution is reduced. Has been found to be sharp (narrow) and a high-performance cement dispersant can be obtained, and the present invention has been completed.

That is, according to the present invention, a polyalkylene glycol mono (meth) acrylate monomer and a monomer mixture containing (meth) acrylic acid, a polymerization initiator and water are mixed at a solid concentration of 50 to 90% by weight. % At a time in a reaction vessel and reacted at a polymerization temperature of 42 to 70 ° C. to provide a method for producing a (meth) acrylic acid-based cement dispersant. The present invention also provides a polyalkylene glycol mono (meth) acrylate ester-based monomer and a monomer mixture containing (meth) acrylic acid, a polymerization initiator, and water at a solid concentration of 50 to 90% by weight. So that the polymerization temperature is 42-70
It is intended to provide a method for producing a (meth) acrylic acid-based cement dispersant, wherein the reaction is carried out by increasing the temperature stepwise.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The monomer mixture used in the present invention comprises a polyalkylene glycol mono (meth) acrylate monomer (hereinafter referred to as monomer A) and a (meth) acrylic acid (hereinafter referred to as monomer A). A monomer B) may be used as an essential component, and may further contain another monomer copolymerizable therewith (hereinafter, referred to as a monomer C).

Examples of the polyalkylene glycol mono (meth) acrylate monomer (monomer A) include, for example, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and polybutylene glycol mono (meth) acrylate. A) acrylate, polyethylene glycol polypropylene glycol mono (meth) acrylate, polyethylene glycol polybutylene glycol mono (meth) acrylate, polypropylene glycol polybutylene glycol mono (meth) acrylate, polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) acrylate, methoxypolyethylene Glycol mono (meth) acrylate, methoxy polypropylene glycol mono (meth) acryle Methoxypolybutylene glycol mono (meth) acrylate, methoxypolyethylene glycol polypropylene glycol mono (meth) acrylate, methoxypolyethylene glycol polybutylene glycol mono (meth) acrylate, methoxypolypropylene glycol polybutylene glycol mono (meth) acrylate, methoxypolyethylene glycol Polypropylene glycol polybutylene glycol mono (meth) acrylate, ethoxy polyethylene glycol mono (meth) acrylate, ethoxy polypropylene glycol mono (meth) acrylate, ethoxy polybutylene glycol mono (meth) acrylate, ethoxy polyethylene glycol polypropylene glycol mono (meth) acrylate, Ethoxypolyer Lenglycol polybutylene glycol mono (meth) acrylate, ethoxy polypropylene glycol polybutylene glycol mono (meth) acrylate, ethoxy polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) acrylate, 1-propoxy polyethylene glycol mono (meth) acrylate, 2- Propoxy polyethylene glycol mono (meth) acrylate, 1-butoxy polyethylene glycol mono (meth)
Acrylate, 2-butoxy polyethylene glycol mono (meth) acrylate, 2-methyl-1-propoxy polyethylene glycol mono (meth) acrylate, 2-methyl
2-propoxy polyethylene glycol mono (meth) acrylate, cyclohexoxy polyethylene glycol mono (meth) acrylate, 1-octoxy polyethylene glycol mono (meth) acrylate, 2-ethyl-1-hexanoxy polyethylene glycol mono (meth) acrylate , Nonylalkoxy polyethylene glycol mono (meth) acrylate, lauryl alkoxy polyethylene glycol mono (meth) acrylate, cetyl alkoxy polyethylene glycol mono (meth) acrylate, stearyl alkoxy polyethylene glycol mono (meth) acrylate, phenoxy polyethylene glycol mono (meth) acrylate, Phenylmethoxy polyethylene glycol mono (meth) acrylate, methylphenoxy polyethylene glycol Recohol mono (meth) acrylate, p-ethylphenoxy polyethylene glycol mono (meth) acrylate, dimethylphenoxy polyethylene glycol mono (meth) acrylate, pt-butylphenoxy polyethylene glycol mono (meth) acrylate, nonylphenoxy polyethylene glycol mono (meth) acrylate , Dodecylphenoxy polyethylene glycol mono (meth) acrylate, phenylphenoxy polyethylene glycol mono (meth) acrylate, naphthoxy polyethylene glycol mono (meth) acrylate, and the like. These may be used alone or in combination of two or more. Can be used together.

[0009] The cement additive obtained by the production method of the present invention is considered to exhibit strong cement dispersibility due to the hydrophilicity and steric repulsion of the polyalkylene glycol chain derived from the monomer A after being adsorbed on the cement. Can be From this viewpoint, it is preferable to introduce a large amount of highly hydrophilic oxyethylene groups into the polyalkylene glycol chain, and use methoxypolyethylene glycol mono (meth) acrylate, particularly methoxypolyethylene glycol monomethacrylate as the monomer A. Is preferred. On the other hand, if the polyalkylene glycol chain is too long, it takes a long time to dissolve. Therefore, the average number of moles of the added oxyalkylene group is 5 to 70, preferably 10 to 40, and particularly preferably 23 to 25.

As the (meth) acrylic acid (monomer B), either acrylic acid or methacrylic acid may be used, and either one may be used alone or a combination of both may be used, but methacrylic acid is preferred. When the monomer B is neutralized with an alkali, the reaction rate decreases, and unreacted monomers and low-molecular polymers having low dispersibility tend to increase. Therefore, the neutralization ratio is preferably 0%. Therefore,
The reaction is preferably performed without adding a neutralizing agent such as an alkali metal hydroxide to the reaction system.

The other monomer (monomer C) copolymerizable with the monomers A and B includes, for example, an ester of an aliphatic alcohol having 1 to 20 carbon atoms and (meth) acrylic acid;
Maleic acid, fumaric acid, unsaturated dicarboxylic acids such as citraconic acid, monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts thereof; maleic acid, fumaric acid, unsaturated dicarboxylic acids such as citraconic acid; C1-20 aliphatic alcohols, C2-4 glycols or monoesters or diesters of these glycols with (alkoxy) polyalkylene glycols having an addition mole number of 2 to 300; (meth) acrylamide, (meth) Unsaturated amides such as acrylalkylamide; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyls such as styrene; (meth) allylsulfonic acid, sulfoethyl (meth) acrylate, 2-methylpropanesulfonic acid ( Unsaturated sulfonic acids such as (meth) acrylamide and styrene sulfonic acid; Examples thereof include metal salts, divalent metal salts, ammonium salts, and organic amine salts, and any of these may be used alone or in combination of two or more.

The ratio of the monomer A, the monomer B and the monomer C in the monomer mixture is 5 to 98% by weight based on the total weight of the monomers, and 25 to 96% by weight. % By weight, especially 40 to 94% by weight, monomer B is 95 to 2% by weight, more preferably 75 to 4% by weight, particularly preferably 60 to 6% by weight, monomer C is 0 to 50% by weight, Further, it is preferably 0 to 30% by weight, particularly preferably 0 to 10% by weight. The monomer mixture may be used as it is,
It may be used as an aqueous solution.

In the present invention, it is preferable to use a chain transfer agent, and when this is used, it is charged into a reactor together with the monomer mixture before the start of the reaction. Examples of the chain transfer agent include mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate,
Examples thereof include thiol compounds such as octyl mercaptopropionate and 2-mercaptoethanesulfonic acid, and any of these can be used alone or in combination of two or more. The chain transfer agent is 1% of the total weight of the monomer mixture.
It is used in an amount of up to 5% by weight, preferably in an amount of 0.5 to 10% by weight. The chain transfer agent may be used as it is, or may be used as an aqueous solution.

The polymerization initiator used in the production method of the present invention includes, for example, ammonia or an alkali metal persulfate; hydrogen peroxide; 2,2′-azobis (2-amidinopropane) dihydrochloride and the like. And water-soluble polymerization initiators such as azoamidine compounds.
More than one species can be used in combination. Also, sodium hydrogen sulfite, Mohr salt, together with the polymerization initiator,
An accelerator such as ascorbic acid may be used in combination. The polymerization initiator is used in an amount of 0.5 to 10% by weight, preferably 1 to 5% by weight based on the total weight of the monomer mixture. The polymerization initiator may be liquid or powder. These may be used as they are, or may be diluted beforehand to prepare and use a polymerization initiator-containing aqueous solution. If the powdered polymerization initiator is used as it is, it may take time to uniformly dissolve it in the reaction system. Therefore, it is preferable to prepare and use a polymerization initiator-containing aqueous solution.

When the solid concentration in the production method of the present invention, that is, the solid content excluding water in the reaction solution, is low, the reaction time is prolonged, unreacted monomer is apt to remain, and Since the productivity at the time and the efficiency of dry powdering decrease, it is necessary to be 50 to 90% by weight, preferably 60 to 90% by weight, particularly preferably 60 to 85% by weight. The reaction system of the present invention contains substantially no solvent other than water, that is, no organic solvent.

[0016] The polymerization temperature is usually 42 to 70 ° C, preferably 45 to 65 ° C. If the polymerization temperature is lower than 42 ° C., no polymerization reaction occurs. On the other hand, when the temperature exceeds 70 ° C., polymers having various molecular weights are easily produced, and the production ratio of the polymer having a low dispersing power is increased, so that the performance as a cement dispersant is reduced.

In a preferred embodiment of the present invention, the reaction is carried out by increasing the polymerization temperature stepwise. That is, after charging the reaction raw materials into the reaction vessel at one time, the reaction is carried out at a temperature of 42 to 52 ° C, preferably 45 to 50 ° C for at least 20 minutes, preferably 30 to 60 minutes, and then at 55 to 70 ° C. Temperature, preferably 60-65 ° C
And react for 30 minutes or more. For example, when a tank reactor is used, the temperature can be controlled by adjusting the jacket temperature to control the heat of reaction.

After completion of the addition of the polymerization initiator, the temperature is preferably maintained or raised to mature the reaction and reduce the reaction activity. If the reaction activity remains, it causes the stability with time of the obtained cement dispersant to decrease.

The reaction solution obtained as described above can be used as it is as a liquid cement dispersant,
The reaction solution can be dried as a raw material and used as a powder dispersant.

The cement dispersant thus obtained may be used in combination with other known cement admixtures. Known cement admixtures include, for example, other cement dispersants (lignin sulfonates and derivatives thereof,
Oxycarboxylate, polyol derivative, polyoxyethylene alkylaryl ether derivative, formalin condensate of alkyl allyl sulfonate, formalin condensate of melamine sulfonic acid, polycarboxylic acid polymer compound, etc.), air entraining agent, cement wet Agent, swelling agent, waterproofing agent,
Retarders, quick-setting agents, water-soluble polymer substances, thickeners, flocculants,
Examples include a drying shrinkage reducing agent, a strength enhancer, a curing accelerator, an antifoaming agent, and the like, and any of these can be used alone or in combination of two or more.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 In a 300 ml three-necked flask, 82.2 g of methoxypolyethylene glycol methacrylate (n = 23), methacrylic acid
18.0 g, sodium methallyl sulfonate 7.7 g and water 19.6 g
And the raw materials were dissolved with stirring.
Thereafter, 9.7 g of a 20% by weight aqueous solution of ammonium persulfate was added to the above raw materials at once. Transfer the reaction mixture to an oil bath
C. and the polymerization reaction was carried out for 2 hours. Examples 2 to 6 Using the reaction materials shown in Table 1, polymerization was performed in the same manner as in Example 1. Comparative Example 1 The reaction materials shown in Table 1 other than a 20% by weight aqueous solution of ammonium persulfate were charged into a 300 ml three-necked flask and dissolved with stirring. Thereafter, the oil bath was heated to 60 ° C., and polymerization was carried out while dropping a 20% by weight aqueous solution of ammonium persulfate over 4 hours. Comparative Examples 2 to 6 Using the reaction materials shown in Table 1, polymerization was carried out in the same manner as in Comparative Example 1.

[0023]

[Table 1]

Table 2 shows Examples 1 to 6 and Comparative Examples 1 to 6.
, Polymerization temperature, polymerization temperature, weight average molecular weight (Mw) of the obtained polymer, degree of dispersion (Mw / M
n) and the mortar flow value measured by the following method.

[0025]

[Table 2]

(Method of measuring mortar flow) As a dispersant, the reaction solution obtained by the above method was diluted with water, and the solid content concentration was adjusted to 30% by weight. Compounded cement: 500 g, Ogasa sand: 500 g, water: 150 g, defoamer: CC-118 (manufactured by NOF Corporation) 5 g (1% by weight of cement), dispersant: 2.5 g (0.15% by weight of cement; solid content) Mixing method ) Cement, Ogasa sand, and an aqueous solution of an admixture and an antifoaming agent were added to a mixing bowl, and mixed for 90 seconds using a Hobart mixer to prepare a mortar. Method of measuring flow value A mortar flow cone is placed on a shingle glass plate having a thickness of 5 mm, and after filling the prepared mortar, the flow cone is pulled up. After the spread stopped, the diameters in two perpendicular directions were measured, and the average value was taken as the flow value.

Example 7 In a 500 ml three-necked flask, 224.7 g of methoxypolyethylene glycol methacrylate (n = 23), 49.2 g of methacrylic acid, 21.0 g of sodium methallylsulfonate and 53.6 g of water were placed.
g of raw material was charged and the raw material was dissolved with stirring. Then, 26.5 g of 20% by weight ammonium persulfate aqueous solution
Was added to the above raw materials at once, and the oil bath was heated to 50 ° C., and the polymerization reaction was carried out for 30 minutes. Thereafter, the temperature of the oil bath was raised to 60 ° C., and the polymerization reaction was performed for 1 hour.

Examples 8 to 10 Using the reaction materials shown in Table 3, polymerization was carried out in the same manner as in Example 7.

[0029]

[Table 3]

Table 4 shows the polymerization concentration (solid content concentration), the temperature difference between the oil bath and the reaction solution (maximum value), the weight average molecular weight (Mw), and the dispersity (Mw) of the obtained polymer in Examples 7 to 10. / Mn) and the mortar flow value measured by the above method.

[0031]

[Table 4]

Example 11 and Comparative Example 7: Production of Powder Dispersant The reaction solution obtained in Example 1 and Comparative Example 6 (solid content: 400 g)
10% by weight aqueous sodium hydroxide solution)
After adjusting the pH to alkaline, sodium peroxide and triethanolamine were each added at 1% by weight based on the solid content to neutralize the peroxide. This was put in a kneader-type kneader-stirrer with a processing volume of 1 L, and the temperature was 90 ° C. and the pressure was reduced to 30 Torr.
Concentration and drying were performed while kneading. The obtained powder is pulverized with a pulverizer (MCG180 manufactured by Matsubara Co., Ltd.) to obtain a particle size of 50 to 500.
It was adjusted to μm. In the production of each of the above powder dispersants,
Table 5 shows the time required for drying and the loss on drying.

[0033]

[Table 5]

[0034]

According to the production method of the present invention, a high-performance cement having a narrow molecular weight distribution can be obtained by a simple operation without requiring a special device such as a monomer mixing tank and a polymerization initiator dropping device. The dispersant can be manufactured in a short time.

Continuing from the front page (72) Inventor Hiroshi Nakanishi 2-4-2 Daisaku, Sakura City, Chiba Prefecture Pacific Cement Co., Ltd. Central Research Laboratory F term (reference) 4J011 AA06 BB09 HA02 HB02 HB06 4J027 AC03 BA06 CB10 CC02 CD00

Claims (5)

[Claims] 1. Polyalkylene glycol mono (meth)
A reaction mixture including a monomer mixture containing an acrylate monomer and (meth) acrylic acid, a polymerization initiator and water is charged into a reaction vessel so as to have a solid content concentration of 50 to 90% by weight. A method of producing a (meth) acrylic acid-based cement dispersant, wherein the reaction is carried out at a polymerization temperature of 42 to 70 ° C. 2. The method according to claim 1, wherein the monomer mixture contains methoxypolyethylene glycol methacrylate and methacrylic acid. 3. Polyalkylene glycol mono (meth)
A reaction mixture including a monomer mixture containing an acrylate monomer and (meth) acrylic acid, a polymerization initiator and water is charged into a reaction vessel so as to have a solid content concentration of 50 to 90% by weight. A method for producing a (meth) acrylic acid-based cement dispersant, wherein a polymerization temperature of 42 to 70 ° C. is stepwise raised to cause a reaction. 4. The method according to claim 3, wherein the reaction is carried out at a polymerization temperature of 42 to 52 ° C. for at least 20 minutes, and then the polymerization temperature is raised to 55 to 70 ° C. 5. The production method according to claim 3, wherein the monomer mixture contains methoxypolyethylene glycol methacrylate and methacrylic acid.