JP3179022B2 - Cement dispersant, method for producing the same, and cement composition using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement dispersant, a method for producing the same, and a cement composition using the same. More specifically, by improving the dispersibility of the cement particles to increase the fluidity of the cement composition, preventing the resulting fluidity from decreasing over time, and entraining an appropriate amount of air into the cement composition The present invention relates to a cement dispersant which gives good workability and forms concrete having high strength, a method for producing the same, and a cement composition using the same.

[0002]

2. Description of the Related Art Since the early deterioration of concrete structures became a social problem in 1981, there has been a strong demand for reducing the amount of water in concrete to improve its workability and durability. There are active innovations in cement dispersants that greatly affect the quality and performance of cement.

[0003] However, in the cement composition, due to the hydration reaction between the cement and water, the consistency decreases with the lapse of time after compounding, and the workability decreases.
This phenomenon is generally called slump loss in concrete, and the slump loss increases as the cement composition has a lower unit water amount, that is, a cement composition having a high water reduction rate required recently. Such slump loss is a factor that causes obstacles in ready-mixed concrete such as a limitation in transportation time, a change in quality due to a standby time at a casting site, poor workability, and a decrease in durability due to a cold joint or the like. Also, in the production of concrete secondary products, etc., after temporarily suspending the pumping of the cement composition, when the pumping is resumed, the pumping pressure suddenly increases,
It may cause accidents such as blockage of the pump, or may cause problems such as unfilling if the molding such as compaction is delayed for some reason after the cement composition is injected into the mold. . Therefore, slump loss is an important problem that must be solved in a ready-mixed concrete plant, a plant for manufacturing secondary concrete products, and the like in order to control the quality of the cement composition and improve workability.

[0004] Therefore, so-called high-performance AE water reducing agents which have high water-reducing properties, small slump loss and can be added to a concrete composition at a ready-mixed concrete factory have been vigorously developed by admixture manufacturers, and at present, High performance AE water reducing agents such as naphthalene, aminosulfonic acid and polycarboxylic acid are commercially available. As polycarboxylic acid-based high-performance AE water reducing agents, for example, Japanese Patent Publication No. 18338/1984 discloses polyalkylene glycol mono (meth) acrylate monomers, (meth) acrylic monomers and monomers thereof. A copolymer produced by introducing a monomer copolymerizable with a specific ratio is disclosed in JP-A-5-23.
No. 8795 discloses a copolymer obtained by polymerizing a polyalkylene glycol diester monomer having an unsaturated bond and a monomer having a dissociating group, and JP-A-8-12396 discloses a copolymer having an unsaturated bond. A copolymer with another specific monomer having an alkylene glycol-based monomer as an essential component is disclosed. Although these polycarboxylic acid-based high-performance AE water reducing agents have a high water reducing performance and a slump holding function, they are still not sufficiently satisfied, and further improvement in performance is required. On the other hand, various methods for improving the ability of the cement composition to prevent slump loss have been proposed, for example, Japanese Patent Application Laid-Open No. 54-139929.
Japanese Patent Application Laid-Open No. 60-16851 discloses a method of granulating a naphthalenesulfonic acid formalin condensate and gradually dissolving it in a cement composition to prevent slump loss. The method of preventing the slump loss by gradually hydrolyzing and dissolving the copolymer granules in the cement composition has been proposed, but any of the particulate admixtures is dispersed in the solution. Therefore, there are problems in localization of the admixture, storage stability, and the like. JP-A-63-162562 proposes a method in which a cement dispersant is contained in an organic hydrogel such as polyacrylic acid and the dispersant is gradually released in the cement composition. Because it contains an insoluble gel,
There was a problem in stability such as separation and sedimentation.

[0005] Further, when the water / cement ratio (weight ratio) is extremely suppressed to 15 to 40% for the purpose of high strength, poly is said to have the highest water reducing performance among these high performance AE water reducing agents. Even with a carboxylic acid-based high-performance AE water reducing agent, there is a problem that it is difficult to give sufficient fluidity to the cement composition and slump loss is large, so that sufficient workability cannot be obtained. .

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cement dispersant which solves the above problems and has excellent slump holding performance, a method for producing the same, and a cement composition using the same. It is in.

Another object of the present invention is to provide a cement dispersant which gives excellent fluidity over a long period of time even for a cement composition having a water / cement ratio (weight ratio) of 15 to 40%, and a cement dispersant. An object of the present invention is to provide a cement composition containing the same.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the above-mentioned objects were found to have a weight average molecular weight within a predetermined range and a weight within a predetermined range. The present inventors have found that this can be achieved by a cement dispersant containing a polycarboxylic acid-based polymer (A) or a salt thereof having a value obtained by subtracting the peak top molecular weight from the average molecular weight, and completed the present invention based on this finding.

That is, the above objects are achieved by any one of the following (1) to (9).

(1) (Alkoxy) polyalkylene
Recohol mono (meth) acrylate monomer
(A) 5 to 98% by weight, (meth) acrylic acid monomer
(B) 95-2% by weight and copolymerization with these monomers
0 to 50% by weight of other possible monomers (c) (provided that
(The total of (a), (b) and (c) is 100% by weight)
A cement dispersant containing a polycarboxylic acid-based polymer (A) or a salt thereof obtained by copolymerization as a main component, wherein the weight average molecular weight of the polymer (A) is determined by gel permeation chromatography (hereinafter, referred to as “gel permeation chromatography”). GPC ”) in terms of polyethylene glycol by 10,000 to 500,0.
A cement dispersant, wherein the value is in the range of 00 and the value obtained by subtracting the peak top molecular weight from the weight average molecular weight is 0 to 8,000. The “peak top molecular weight” used in the present invention indicates a molecular weight corresponding to the highest position in a curve plotted for a test polymer in a GPC chart. (2) The following general formula (1):

[0011]

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(Wherein R ¹ is hydrogen or methyl
R ² O represents an oxyalkylene having 2 to 4 carbon atoms
Represents a mixture of one or more of the groups
In this case, even if they are added in blocks,
R ³ may be hydrogen or an alkyl having 1 to 5 carbons.
And m is an average addition mole of the oxyalkylene group.
It is a value indicating a number and represents an integer of 1 to 100. )
(Alkoxy) polyalkylene glycol mono (me
(T) Acrylic ester monomer (a) 5 to 98 weight
%, The following general formula (2):

[0013]

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(Wherein, R ⁴ is hydrogen or methyl)
M ¹ represents hydrogen, a monovalent metal, a divalent metal,
Represents a monium group or an organic amine group. )
(Meth) acrylic acid monomer (b) 95 to 2% by weight,
And another monomer (c) 0 copolymerizable with these monomers.
~ 50% by weight (however, the sum of (a), (b) and (c)
The total amount is 100% by weight).
Cement containing acid-based polymer (A) or a salt thereof as a main component
A dispersant, wherein the weight average molecular weight of the polymer (A) is
Polyester by gel permeation chromatography
10,000-500,000 in terms of Tylene glycol
Within the range, and from the weight average molecular weight to the peak top
Note that the value obtained by subtracting the molecular weight is from 0 to 8,000.
Cement dispersant.

(3) (Alkoxy) polyalkylene
Recohol mono (meth) acrylate monomer
(A) is (methoxy) polyethylene glycol mono (meth)
(T) acrylate, (meth) acrylic acid monomer
(1) or wherein (b) is (meth) acrylic acid
The cement dispersant according to (2). (4) The adsorption rate of the polymer (A) to cement particles is
When added at 0.2% by weight to cement, at room temperature
(1) characterized by being less than 60% in 5 minutes
The cement dispersant according to any one of (1) to (3). (5) The adsorption rate of the polymer (A) to cement particles is
When added at 0.2% by weight to cement, at room temperature
(1) characterized in that it is 60% or more in 5 minutes.
The cement dispersant according to any one of (1) to (3).

(6) (Alkoxy) polyalkylene
Recohol mono (meth) acrylate monomer
(A) 5 to 98% by weight, (meth) acrylic acid monomer
(B) 95-2% by weight and copolymerization with these monomers
0 to 50% by weight of other possible monomers (c) (provided that
(The sum of (a), (b) and (c) is 100% by weight)
The amount of the monomer mixture (I) consisting of
Within the range of 10 to 28% by weight based on the
At a temperature below the cloud point of the monomer mixture (I),
When the neutralization ratio of the monomer mixture (I) is in the range of 0 to 20 mol%
A reaction vessel containing the monomer mixture (I) under water under certain conditions
Solution polymerization reaction by dropping on
Of producing a cement dispersant. (7) (Alkoxy) polyalkylene glycol mono
(Meth) acrylic acid ester monomer (a) 5 to 98 layers
%, (Meth) acrylic acid monomer (b) 95 to 2% by weight
%, And other monomers copolymerizable with these monomers
(C) 0 to 50% by weight (provided that (a), (b) and
(A total of 100% by weight of (c))
(I) the neutralization ratio is in the range of 0 to 20 mol%, and
The monomer mixture (I) is mixed with a chain transfer agent before the polymerization reaction.
Under the following conditions, the monomer mixture (I) and the chain transfer agent
The solution polymerization reaction is carried out by dropping into a reaction vessel containing water.
A method for producing a cement dispersant. (8) The following general formula (1):

[0017]

Embedded image

(Wherein R ¹ is hydrogen or methyl
R ² O represents an oxyalkylene having 2 to 4 carbon atoms
Represents a mixture of one or more of the groups
In this case, even if they are added in blocks,
R ³ may be hydrogen or an alkyl having 1 to 5 carbons.
And m is an average addition mole of the oxyalkylene group.
It is a value indicating a number and represents an integer of 1 to 100. )
(Alkoxy) polyalkylene glycol mono (me
(T) Acrylic ester monomer (a) 5 to 98 weight
%, The following general formula (2):

[0019]

Embedded image

(Wherein, R ⁴ is hydrogen or methyl
M ¹ represents hydrogen, a monovalent metal, a divalent metal,
Represents a monium group or an organic amine group. )
(Meth) acrylic acid monomer (b) 95 to 2% by weight,
And another monomer (c) 0 copolymerizable with these monomers.
~ 50% by weight (however, the sum of (a), (b) and (c)
Use of monomer mixture (I) consisting of 100% by weight)
The amount ranges from 10 to 28% by weight relative to the total amount of the raw materials used.
And the polymerization was carried out at a temperature below the cloud point of the monomer mixture (I).
The neutralization rate of the monomer mixture (I) is 0 to
The monomer mixture under conditions which are within the range of 20 mol%
The solution weight is dropped by dropping (I) into a reaction vessel containing water.
Manufacture of cement dispersant characterized by performing a combined reaction
Method.

[0021] (9) under following general formula (1):

[0022]

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(Wherein R ¹ represents hydrogen or a methyl group; R ² O represents one or a mixture of two or more oxyalkylene groups having 2 to 4 carbon atoms; R ³ represents hydrogen or an alkyl group having 1 to 5 carbon atoms, m is a value indicating the average addition mole number of the oxyalkylene group, and 1 to 3 (Representing an integer of 100)) (alkoxy) polyalkylene glycol mono (meth) acrylate monomer (a) in an amount of 5 to 98% by weight, represented by the following general formula (2):

[0024]

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(Wherein, R ⁴ represents hydrogen or a methyl group, and M ¹ represents hydrogen, a monovalent metal, a divalent metal, an ammonium group or an organic amine group). 95 to 2% by weight of a system monomer (b) and another monomer (c) 0 copolymerizable with these monomers
Neutralization of the monomer mixture (I) consisting of 〜50 % by weight (the total of (a), (b) and (c) is 100% by weight)
Rate is in the range of 0 to 20 mol%, and
Under the condition that the product (I) is mixed with a chain transfer agent before the polymerization reaction.
Reaction of the monomer mixture (I) and the chain transfer agent with water
Performing the solution polymerization reaction by dropping
A method for producing a characteristic cement dispersant.

( 10 ) A cement composition containing at least cement, water and a cement dispersant, wherein the cement composition contains the cement dispersant according to the above (1) or (2).

[0027]

Hereinafter, the present invention will be described in detail.

The polycarboxylic acid polymer (A) used as a main component of the cement dispersant of the present invention is obtained by polymerizing a monomer mixture (I) containing an unsaturated carboxylic acid monomer as an essential component. Is a generic term for the polymer obtained by the above method, and particularly, the monomer mixture (I) is represented by the following general formula (1):

[0029]

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(Wherein R ¹ represents hydrogen or a methyl group; R ² O represents one or a mixture of two or more oxyalkylene groups having 2 to 4 carbon atoms; R ³ represents hydrogen or an alkyl group having 1 to 5 carbon atoms, m is a value indicating the average addition mole number of the oxyalkylene group, and 1 to 3 (Representing an integer of 100)) (alkoxy) polyalkylene glycol mono (meth) acrylate monomer (a) in an amount of 5 to 98% by weight, represented by the following general formula (2):

[0031]

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(Wherein, R ⁴ represents hydrogen or a methyl group, and M ¹ represents hydrogen, a monovalent metal, a divalent metal, an ammonium group or an organic amine group). 95 to 2% by weight of a system monomer (b) and another monomer (c) 0 copolymerizable with these monomers
-50% by weight (however, the total of (a), (b) and (c) is 100% by weight).

Examples of the monomer (a) include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and polybutylene glycol mono ( (Meth) 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, methoxypolypropylene glycol mono (meth) acrylate, methoxypolybutylene glycol mono ( Meth) acrylates,
Methoxy polyethylene glycol polypropylene glycol mono (meth) acrylate, methoxy polyethylene glycol polybutylene glycol mono (meth) acrylate, methoxy polypropylene glycol polybutylene glycol mono (meth) acrylate, methoxy polyethylene 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, ethoxy polyethylene glycol polybutylene glycol mono (meth) acrylate Ethoxy polypropylene glycol polybutylene glycol mono (meth) acrylate, and can be exemplified ethoxy polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) acrylate, can be used alone or in combination of two or more thereof.

Although not limited by the following description, the cement dispersant of the present invention exhibits a strong cement dispersing effect due to the hydrophilicity and steric repulsion of the polyalkylene glycol chain of the monomer (a) after being adsorbed on the cement. It is considered to be something to do. From this viewpoint, it is preferable to introduce a large number of highly hydrophilic oxyethylene groups into the polyalkylene glycol chain, and it is particularly preferable to use methoxypolyethylene glycol mono (meth) acrylate for the monomer (a). The average number of moles of the oxyethylene group is preferably 1 to 100, and among them, the average number of moles of the oxyethylene group is most preferably 5 to 100 mol in order to obtain high hydrophilicity and steric repulsion. preferable.

Examples of the monomer (b) include acrylic acid, methacrylic acid and their monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts. Two or more types can be used.

Examples of the monomer (c) include those having 1 carbon atom
Esters of up to 20 aliphatic alcohols with (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid and their monovalent, divalent, ammonium and organic amine salts An unsaturated dicarboxylic acid such as maleic acid, fumaric acid, citraconic acid and an aliphatic alcohol having 1 to 20 carbon atoms or 2 carbon atoms;
Monoesters or diesters of (1) to 4 (4) glycols or (2) to 100 (mol) of added glycols with (alkoxy) polyalkylene glycols; unsaturated amides such as (meth) acrylamide and (meth) acrylalkylamide; vinyl acetate; Vinyl esters such as vinyl propionate; aromatic vinyls such as styrene;
Unsaturated sulfonic acids such as (meth) allylsulfonic acid, sulfoethyl (meth) acrylate, 2-methylpropanesulfonic acid (meth) acrylamide and styrenesulfonic acid, and their monovalent metal salts, divalent metal salts, ammonium salts and organic compounds Amine salts and the like,
One or more of these can be used.

The ratio of using the monomer (a), the monomer (b) and the monomer (c) is such that the monomer (a) is 5 to 98% by weight, preferably 25 to 96% by weight, Preferably 40
-94% by weight, and the monomer (b) is 95-2% by weight;
It is preferably 75 to 4% by weight, more preferably 60 to 6% by weight, and the monomer (c) is 0 to 50% by weight, preferably 0 to 30% by weight, more preferably 0 to 10% by weight. .

The weight average molecular weight of the polycarboxylic acid polymer (A) is 10,000 to 500,000, preferably 10,000 in terms of polyethylene glycol by GPC.
It is in the range of 0-100,000. Further, the value obtained by subtracting the peak top molecular weight from the weight average molecular weight of the polymer (A) needs to be 0 to 8,000,
Preferably it is 0 to 7,000.

If the weight-average molecular weight is less than 10,000 or more than 500,000, the resulting cement dispersant has a reduced water-reducing ability, which is not preferable. The value obtained by subtracting the peak top molecular weight from the weight-average molecular weight is 8,8. If it exceeds 000, the resulting cement dispersant has poor slump retention performance, which is not preferable.

The cement dispersant of the present invention has a specific weight average molecular weight as described above, and a polycarboxylic acid polymer (A) having a specific value obtained by subtracting the peak top molecular weight from the weight average molecular weight. ) Is a cement dispersing agent having as a main component.

In general, it is known that the cement dispersing performance of the polymer used in the cement dispersant has a correlation with the molecular weight, and that the weight average molecular weight (Mw) has an optimum range. However, if the molecular weight distribution of the obtained polymer is described in detail, even if Mw is the same, various molecular weight distributions can be taken such that the peak top molecular weight (Mp) is located on the low molecular weight side or high molecular weight side of Mw. And, for example, even if Mw is the same, Mp greatly deviates and is on the low molecular weight side, that is, Mw−Mp> 8,000.
Such a polymer contains a large amount of a high-molecular-weight polymer having a low cement dispersing performance, so that a large amount of a cement dispersing agent is required to obtain the same flow value, or the slump holding performance is reduced. In other words, when the polymer has a molecular weight distribution of Mw-Mp <0, the amount of low molecular weight polymer increases, and the amount of air is undesirably increased. Such a polymer is prepared by polymerizing the monomer mixture (I) in an aqueous solution at a high temperature exceeding the cloud point, or dropping a chain transfer agent separately from the monomer mixture (I) into a reaction vessel containing water. It can be formed by polymerization. For example, when the monomer mixture (I) is polymerized at a high temperature exceeding the cloud point, the monomer mixture (I) separates into a water-insoluble suspension and a water-soluble water-soluble substance. This is probably because the suspension becomes a high molecular weight substance due to its high concentration, and the chain transfer agent is dropped into the reaction vessel containing water separately from the monomer mixture (I). When polymerized, it takes a little time for the chain transfer agent to dissolve uniformly in water, so that the monomer mixture (I) in contact with the highly concentrated chain transfer agent droplets remains in a low molecular weight form. It is thought that it will be.

When the polycarboxylic acid polymer (A) satisfies the following requirement (i) or (ii), it is more preferable because various properties as a cement dispersant are most excellent.

(I) The adsorption rate of the polycarboxylic acid-based polymer (A) to the cement particles is such that when the polymer (A) is added at 0.2% by weight to the cement, it is obtained at room temperature for 5 minutes. If less than 60%, preferably less than 50%.

(Ii) The adsorption rate of the polycarboxylic acid-based polymer (A) to the cement particles is such that when 0.2% by weight of the polymer (A) is added to the cement, it can be obtained at room temperature for 5 minutes. When it is 60% or more.

Here, the adsorption rate of the polycarboxylic acid polymer (A) to the cement particles is calculated by measuring the following method.

First, the polymer (A) is added to the cement used in the beaker so that the solid content is 0.2% by weight, and a predetermined amount of water is further added. After adding a predetermined amount of cement to the same beaker and stirring for a predetermined time, filtration is performed to collect a filtrate. The concentration of the polymer (A) remaining in the obtained filtrate is measured with a differential refractometer. Then, the adsorption rate is calculated by the following equation.

[0047]

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Therefore, if the polymer (A) is completely adsorbed on the cement particles and is not detected from the filtrate, the adsorption rate will be 100%.

When the polymer (A) satisfies the requirement of (i), the cement dispersant of the present invention can maintain the fluidity of the resulting cement composition for a long period of time, while maintaining the weight When the combination (A) satisfies the requirement of (ii), the cement dispersant of the present invention can secure sufficient fluidity even in a cement composition having an extremely low water / cement ratio.

When the polymer (A) satisfies the requirement of (ii), the cement dispersant of the present invention contains water /
Even in the normally used range of cement ratio of 60% by weight, in a performance evaluation test using mortar, a very small amount of addition can provide favorable mortar properties of a mortar flow value of 100 mm or more and an entrained air amount of 10% or less.

The present inventors have found that the adsorption of the polycarboxylic acid-based cement dispersant to the cement particles is carried out more rapidly as the molecular weight increases, and after the high molecular weight material is adsorbed to the cement particles, the lowering of the polycarboxylic acid-based cement dispersant is successively performed with time. It was discovered that molecular weights were adsorbed. In addition, we have found that such adsorption
It has been found that the cement particles start immediately after coming into contact with the aqueous solution of the polycarboxylic acid-based cement dispersant, and reach saturation adsorption in about one hour or more.

At this time, the saturation adsorption rate is about 80%, though it depends on the kind of the polycarboxylic acid cement dispersant.

The requirement (i) is to minimize the initial adsorption of the polycarboxylic acid-based cement dispersant to the cement particles and to achieve subsequent adsorption over time, and to improve the cement dispersing performance with time. Improve or sustain. Conversely, the requirement (ii) is to end the adsorption of the polycarboxylic acid-based cement dispersant to the cement particles in an extremely short time, thereby improving the initial cement dispersion performance.

The method for producing the polycarboxylic acid polymer (A) is not particularly limited as long as the above-mentioned molecular weight distribution can be obtained. For example, known methods such as solution polymerization and bulk polymerization using a polymerization initiator can be used. A polymerization method can be employed.

The solution polymerization method can be carried out batchwise or continuously. In this case, the solvent used is water; alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; benzene, toluene, xylene and cyclohexane. And an aromatic or aliphatic hydrocarbon such as n-hexane; an ester compound such as ethyl acetate; a ketone compound such as acetone and methyl ethyl ketone; and the like. From the viewpoint of properties, it is preferable to use at least one selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms, and it is more preferable to use water as the solvent.

In the case of performing aqueous solution polymerization, a water-soluble polymerization initiator such as ammonia or an alkali metal persulfate: hydrogen peroxide; an azoamidine compound such as azobis-2-methylpropionamidine hydrochloride is used as the polymerization initiator. In this case, an accelerator such as sodium bisulfite can be used in combination.

When a lower alcohol, an aromatic or aliphatic hydrocarbon, an ester compound or a ketone compound is used as a polymerization solvent, a peroxide such as benzoyl peroxide or lauroyl peroxide; a hydroperoxide such as cumene hydroperoxide. Peroxides; azo compounds such as azobisisobutyronitrile and the like are used as polymerization initiators. At this time, an accelerator such as an amine compound may be used in combination.

Further, when a water-lower alcohol mixed solvent is used, it can be appropriately selected from the above-mentioned various polymerization initiators or a combination of the polymerization initiator and the accelerator.

The bulk polymerization is carried out using a polymerization initiator such as a peroxide such as benzoyl peroxide or lauroyl peroxide; a hydroperoxide such as cumene hydroperoxide; an azo compound such as azobisisobutyronitrile at 50 to 200 ° C. Within the temperature range of

The carboxyl group in the polycarboxylic acid polymer (A) may be a free salt or a salt having a desired neutralization ratio. Examples of such alkaline substances include inorganic salts such as hydroxides, chlorides and carbonates of monovalent and divalent metals; ammonia; organic amines and the like.

Then, for example, (a) a method of polymerizing a monomer mixture (I) containing an unsaturated carboxylic acid monomer as an essential component and, if necessary, neutralizing this to a desired neutralization ratio. And (b) a method of polymerizing a monomer mixture (I) containing an unsaturated carboxylic acid monomer neutralized to a desired neutralization ratio as an essential component, and further increasing the neutralization ratio if necessary. Etc. can be appropriately adopted.

[0062] Particularly preferred production methods for the cement dispersant of the present invention include the following and other production methods.

The amount of the monomer mixture (I) containing an unsaturated carboxylic acid monomer as an essential component is in the range of 10 to 28% by weight based on the total amount of the raw materials used, and the polymerization temperature is simple. Below the cloud point of the monomer mixture (I), preferably from 20 to 5
The monomer mixture (I) is dropped into a water-containing reaction vessel under the conditions of 2 ° C. and the neutralization rate of the monomer mixture (I) is in the range of 0 to 20 mol%. A solution polymerization reaction.

A monomer mixture (I) containing an unsaturated carboxylic acid monomer as an essential component is mixed with a chain transfer agent, and the neutralization ratio of the monomer mixture (I) is from 0 to 20 mol%. A method in which a solution polymerization reaction is carried out by dropping a mixture obtained under conditions within the range into a reaction vessel containing water.

The method of (1) is a method in which water is charged into a reaction vessel, and a solution polymerization reaction is performed while dropping an aqueous solution of the monomer mixture (I) and an aqueous solution of a polymerization catalyst into the reaction vessel. Here, the amount of the monomer mixture used is preferably in the range of 10 to 28% based on the total amount of the raw materials used, and 2
Using more than 8% causes excessive air entrainment,
If it is less than 10%, the net content per unit production is too low, and there is also a problem in economy, which is not preferable. In order to obtain a specific molecular weight distribution according to the present invention, the monomer mixture (I)
Below the cloud point, preferably in the range of 20 to 52 ° C
It is essential to carry out a solution polymerization reaction. Further, the neutralization ratio of the monomer mixture (I) is in the range of 0 to 20%,
If the neutralization ratio exceeds 20%, the water reducing performance is undesirably reduced. Under the above conditions, the temperature of the water in the reaction vessel is raised to a predetermined temperature, and the aqueous solution of the monomer mixture (I) and the aqueous solution of the polymerization catalyst are simultaneously dropped to start the solution polymerization reaction. Each drop is, for example, dropping an aqueous solution of the monomer mixture (I) at a constant rate over 4 hours into water.
The polymerization catalyst aqueous solution is dropped over 5 hours. If the dropping time is too short or too long, the water-reducing performance and productivity are undesirably reduced. In order to complete the solution polymerization of the monomer mixture, the dropping time of the aqueous solution of the polymerization catalyst is set longer than the dropping time of the aqueous solution of the monomer mixture (I), preferably 30 minutes or more, more preferably 1 hour. Take longer. After completion of the dropping of the polymerization catalyst aqueous solution, the predetermined temperature is maintained for at least 30 minutes, preferably for 1 hour or more, to terminate the solution polymerization reaction. Thus, the solution polymerization reaction is completed, and after the temperature is lowered, if necessary, neutralization and concentration adjustment are performed.

In the method of (1), water is charged into a reaction vessel, and an aqueous solution (II) is prepared by uniformly mixing an aqueous solution of the monomer mixture (I) and a chain transfer agent in advance.
And the polymerization catalyst aqueous solution are dropped into the reaction vessel, respectively.
This is a method of performing a solution polymerization reaction. Here, in order to obtain the specific molecular weight distribution of the present invention, the chain transfer agent must be uniformly mixed with the aqueous solution of the monomer mixture (I) before the polymerization reaction. The mixing may be performed in a tank containing the aqueous solution of the monomer mixture (I), or may be performed by a static mixer or the like in a feed line from the tank to the reaction vessel. The mixing temperature is set at 50 ° C. or lower so that polymerization by the chain transfer agent does not occur. Further, the neutralization ratio of the monomer mixture (I) is in the range of 0 to 20%, and a neutralization ratio exceeding 20% is not preferable because the water reducing performance is reduced. Under the above conditions, the temperature of the water in the reaction vessel is raised to a predetermined temperature, and the solution polymerization reaction is started by simultaneously dropping the aqueous solution (II) and the polymerization catalyst aqueous solution, respectively. Each drop is carried out, for example, uniformly over 4 hours of the aqueous solution (II) and over 5 hours of the aqueous polymerization catalyst solution. Further, in order to complete the solution polymerization of the monomer mixture, the dropping time of the polymerization catalyst aqueous solution is set longer than that of the aqueous solution (II),
It is preferably longer than 30 minutes, more preferably longer than 1 hour. After completion of the dropwise addition of the polymerization catalyst aqueous solution, the predetermined temperature is maintained for at least 30 minutes, preferably for 1 hour or more, to terminate the solution polymerization reaction. Thus, the solution polymerization reaction is completed, and after the temperature is lowered, if necessary, neutralization and concentration adjustment are performed.

The chain transfer agent used in the present invention includes:
Although not particularly limited as long as it is a thiol-based compound, for example, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionate, And 2
-Known thiol compounds such as mercaptoethanesulfonic acid. One or two of these chain transfer agents are used.
More than one species can be used.

The polymer (A) can be used as a cement dispersant in the form of an aqueous solution alone or in the form of a mixture. Further, the polymer (A) may be used in combination with other known cement admixtures. Examples of such known cement admixtures include a conventional cement dispersant, an air entrainer, a cement wetting agent, Swelling agents, waterproofing agents, retarders, quick-setting agents, water-soluble polymer substances, thickeners, flocculants, drying shrinkage reducing agents, strength enhancers, curing accelerators, defoamers and the like can be mentioned.

The cement dispersant of the present invention can be used for hydraulic cements such as portland cement, alumina cement, belite-rich cement and various mixed cements, and hydraulic materials other than cements such as gypsum.

When the cement dispersant of the present invention is used, for example, in mortar or concrete using hydraulic cement, it is used in an amount of about 0.01 to 1.0%, preferably about 0.02 to 0.5% of the cement weight. May be added.
This addition has various favorable effects such as improvement of slump holding performance, reduction of unit water amount, increase of concrete strength, and improvement of durability of mortar or concrete. Addition amount of cement dispersant is 0.01
If the amount is less than 1.0%, the performance is insufficient. Conversely, if the amount exceeds 1.0%, the effect is substantially flattened, which is disadvantageous in terms of economy.

Next, a cement composition using the above-mentioned cement dispersant according to the present invention comprises at least cement,
It contains water and the above-mentioned cement dispersant. The above-mentioned cement dispersant is used in an amount of 0.01 to 1.0 part by weight, preferably 0.0
It is preferable to contain 2 to 0.5 parts by weight. In the cement composition prepared by mixing the cement dispersant of the present invention so as to satisfy the above range, for example, in addition to significantly improving the slump retention time, reducing the unit water volume, increasing the strength of concrete, and mortar or Various favorable effects such as improvement in durability of concrete are brought about. The cement that can be added to the cement composition is not particularly limited, and examples thereof include hydraulic cements such as Portland cement, alumina cement, belite-rich cement, and various mixed cements. Also, fine aggregates and coarse aggregates that can be blended with the cement composition are not particularly limited, and may be appropriately selected from many types of fine aggregates and coarse aggregates currently used. Can be. The amount of fine aggregate and coarse aggregate in the cement composition is not particularly limited, and can be appropriately determined by those skilled in the art according to the materials used and the like.

[0072]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples. In the examples,% is% by weight unless otherwise specified.
And parts represent parts by weight.

Production of the cement dispersant (1) of the present invention
REFERENCE EXAMPLE 1 For a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, 1698 parts of water was charged, the inside of the reaction vessel was replaced with nitrogen under stirring, and the mixture was stirred under nitrogen atmosphere. Heated to 80 ° C. Next, 1,668 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 25), methacrylic acid 33
2 parts and 500 parts of water were mixed, and 16.7 parts of mercaptopropionic acid were further uniformly mixed as a chain transfer agent to prepare an aqueous monomer mixture solution. This monomer mixture aqueous solution and 10% ammonium persulfate aqueous solution 1
84 parts were added dropwise over 4 hours, and 10 minutes after the addition was completed.
A 46% aqueous solution of ammonium persulfate was added dropwise over 1 hour. Then the temperature was maintained at 80 ° C. Subsequently 1 hour, solvent
The liquid polymerization reaction was completed. Then, the mixture is neutralized with a 30% aqueous solution of sodium hydroxide to obtain a weight average molecular weight (converted into polyethylene glycol by GPC; the same applies hereinafter).
A cement dispersant (1) of the present invention comprising an aqueous polymer solution having a peak top molecular weight of 18,200 and 3,800 was obtained.

Production of the cement dispersant (2) of the present invention
Reference Example 2 1520 parts of water was charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, and the inside of the reaction vessel was purged with nitrogen under stirring, and under a nitrogen atmosphere. Heated to 50 ° C. Next, 790 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of added ethylene oxide: 10), 189 parts of methacrylic acid
Part, aqueous solution of a monomer mixture consisting of 26 parts of sodium methacrylate and 1500 parts of water, 400 parts of a 10% aqueous ammonium persulfate solution, 5% aqueous sodium bisulfite solution 4
00 parts each for 4 hours, and 10 minutes after the completion of the addition.
100 parts of a 5% aqueous ammonium persulfate solution and 100 parts of a 5% aqueous sodium bisulfite solution were added dropwise over 1 hour. Thereafter, the temperature was maintained at 50 ° C. for 1 hour, and the solution polymerization reaction was completed. The mixture was neutralized with a 30% aqueous sodium hydroxide solution to obtain a cement dispersant (2) of the present invention comprising a polymer aqueous solution having a weight average molecular weight of 33,300 and a peak top molecular weight of 31,800.

Production of the cement dispersant (3) of the present invention
Reference Example 3 For a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, 1700 parts of water was charged, the inside of the reaction vessel was replaced with nitrogen under stirring, and the mixture was placed under a nitrogen atmosphere. Heated to 80 ° C. Next, 1580 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 25), methacrylic acid 42
0 parts and 500 parts of water were mixed, and further 14.5 parts of mercaptopropionic acid as a chain transfer agent were uniformly mixed to prepare an aqueous monomer mixture solution. This monomer mixture aqueous solution and 10% ammonium persulfate aqueous solution 18
4 parts were added dropwise for 4 hours, and after completion of the addition, 46 parts of a 10% ammonium persulfate aqueous solution was further added dropwise for 1 hour. Subsequently, the temperature was maintained at 80 ° C. for 1 hour to complete the solution polymerization reaction. The mixture was neutralized with a 30% aqueous sodium hydroxide solution to obtain a cement dispersant (3) of the present invention comprising a polymer aqueous solution having a weight average molecular weight of 28,600 and a peak top molecular weight of 22,500.

The cement dispersant (4) of the present invention is produced.
Reference Example 4 For a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, 1698 parts of water was charged, the inside of the reaction vessel was replaced with nitrogen under stirring, and the mixture was placed under a nitrogen atmosphere. Heated to 80 ° C. Next, 1796 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 25), methacrylic acid 20
4 parts and 500 parts of water were mixed, and 16.7 parts of mercaptopropionic acid were further uniformly mixed as a chain transfer agent to prepare an aqueous monomer mixture solution. This monomer mixture aqueous solution and 10% ammonium persulfate aqueous solution 18
4 parts were added dropwise over 4 hours, and 10%
46 parts of an aqueous ammonium persulfate solution was added dropwise over 1 hour.
Subsequently, the temperature was maintained at 80 ° C. for 1 hour to complete the solution polymerization reaction. The mixture was neutralized with a 30% aqueous sodium hydroxide solution to obtain a cement dispersant (4) of the present invention comprising a polymer aqueous solution having a weight average molecular weight of 20,500 and a peak top molecular weight of 15,300.

Production of the cement dispersant (5) of the present invention
Reference Example 5 For a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, 1703 parts of water was charged, the inside of the reaction vessel was replaced with nitrogen under stirring, and the reaction was carried out under a nitrogen atmosphere. Heated to 80 ° C. Next, 1858 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 25), methacrylic acid 14
2 parts and 500 parts of water were mixed, and 12.1 parts of mercaptopropionic acid were further uniformly mixed as a chain transfer agent to prepare an aqueous monomer mixture solution. This monomer mixture aqueous solution and 10% ammonium persulfate aqueous solution 18
4 parts were added dropwise over 4 hours, and 10%
46 parts of an aqueous ammonium persulfate solution was added dropwise over 1 hour.
Subsequently, the temperature was maintained at 80 ° C. for 1 hour to complete the solution polymerization reaction. The mixture was neutralized with a 30% aqueous sodium hydroxide solution to obtain a cement dispersant (5) of the present invention comprising a polymer aqueous solution having a weight average molecular weight of 32,800 and a peak top molecular weight of 26,400.

Tables 1 and 2 show the contents of the cement dispersants (1) to (5) of the present invention obtained in the above Reference Examples 1 to 5.

[0079]

[Table 1]

[0080]

[Table 2]

For producing the comparative cement dispersant (1)
Comparative Reference Example 1 189 parts of methacrylic acid and 26 parts of sodium methacrylate of Reference Example 2 were changed to 147 parts of methacrylic acid and 79 parts of sodium methacrylate, and the amount of water charged to the reaction vessel was 156 parts.
The same operation as in Reference Example 2 was performed except that the amount was changed to 4 parts, and the weight average molecular weight was 5,100 and the peak top molecular weight was 4,40.
Thus, a comparative cement dispersant (1) consisting of a polymer aqueous solution was obtained.

For producing the comparative cement dispersant (2)
Comparative Reference Example 2 189 parts of methacrylic acid and 26 parts of sodium methacrylate of Reference Example 2 were changed to 263 parts of sodium methacrylate,
The same operation as in Reference Example 2 was carried out except that the amount of water charged to the reaction vessel was changed to 1712 parts, and the weight average molecular weight was 9,00
0, a comparative cement dispersant (2) comprising a polymer aqueous solution having a peak top molecular weight of 5,700 was obtained.

For preparing the comparative cement dispersant (3)
Comparative Reference Example 3 886 parts of water was charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser.
The atmosphere in the reaction vessel is replaced with nitrogen under stirring, and the atmosphere is
Heated to ° C. Next, 711 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 10) 711 parts, methacrylic acid 170 parts,
An aqueous solution of a monomer mixture consisting of 24 parts of sodium methacrylate and 226 parts of water was dropped in 400 parts of an aqueous 10% ammonium persulfate solution and 400 parts of an aqueous solution of 5% sodium bisulfite over 4 hours. 100 parts of an aqueous solution and 100 parts of a 5% aqueous sodium bisulfite solution were added dropwise over 1 hour. Thereafter, the temperature was maintained at 50 ° C. for 1 hour, and the solution polymerization reaction was completed. The mixture was neutralized with a 30% aqueous sodium hydroxide solution to obtain a comparative cement dispersant (3) comprising a polymer aqueous solution having a weight average molecular weight of 31,100 and a peak top molecular weight of 34,300.

For preparing the comparative cement dispersant (4)
Comparative Reference Example 4 380 parts of water was charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube, and a reflux condenser.
The atmosphere in the reaction vessel is replaced with nitrogen under stirring, and the atmosphere is
Heated to ° C. Next, 1185 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 10), 283 of methacrylic acid
, 40 parts of sodium methacrylate and 377 parts of water, 300 parts of a 20% aqueous ammonium persulfate solution, 10 parts of a 10% aqueous sodium bisulfite solution 3
00 parts each for 4 hours, and 2 hours after the completion of the addition.
75 parts of a 0% aqueous ammonium persulfate solution and 75 parts of a 10% aqueous sodium bisulfite solution were added dropwise over 1 hour. Thereafter, the temperature was maintained at 50 ° C. for 1 hour, and the solution polymerization reaction was completed. The obtained polymer was an unsuitable gel as a cement dispersant, and the molecular weight could not be measured by GPC.

For producing the comparative cement dispersant (5)
Comparative Reference Example 5 In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introduction tube and a reflux condenser, 632 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 10) of 632 parts, 151 parts of methacrylic acid, 21 parts of sodium methacrylate and water 24
A monomer mixture aqueous solution consisting of 66 parts was charged, the inside of the reaction vessel was replaced with nitrogen under stirring, and heated to 50 ° C. under a nitrogen atmosphere. Next, a 10% ammonium persulfate aqueous solution 300
And 300 parts of a 5% aqueous sodium bisulfite solution were added dropwise over 4 hours. After the addition was completed, 75 parts of a 10% aqueous ammonium persulfate solution and 75 parts of a 5% aqueous sodium bisulfite solution were added dropwise over 1 hour. Thereafter, the temperature was maintained at 50 ° C. for 1 hour, and the solution polymerization reaction was completed. The obtained polymer was an unsuitable gel as a cement dispersant, and the molecular weight could not be measured by GPC.

For producing the comparative cement dispersant (6)
Comparative Reference Example 6 In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, 1,422 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 25) was added; An aqueous monomer mixture solution consisting of 378 parts of methacrylic acid, 27 parts of mercaptopropionic acid as a chain transfer agent and 1968 parts of water was charged, the inside of the reaction vessel was replaced with nitrogen under stirring, and heated to 80 ° C. in a nitrogen atmosphere. Next, 165 parts of a 10% ammonium persulfate aqueous solution was added dropwise over 4 hours, and after completion of the addition, 40 parts of a 10% ammonium persulfate aqueous solution was further added dropwise over 1 hour. Subsequently, the temperature was maintained at 80 ° C. for 1 hour to complete the solution polymerization reaction. Then, the mixture is neutralized with a 30% aqueous sodium hydroxide solution to obtain a weight average molecular weight of 20,000.
A comparative cement dispersant (6) consisting of a polymer aqueous solution having a peak top molecular weight of 9,100 was obtained.

For producing the comparative cement dispersant (7)
Comparative Reference Example 7 In a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, 2425 parts of water was charged, the inside of the reaction vessel was replaced with nitrogen under stirring, and the mixture was stirred under a nitrogen atmosphere. Heated to 95 ° C. Next, 790 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of added ethylene oxide: 10), 189 parts of methacrylic acid
, A monomer mixture aqueous solution consisting of 26 parts of sodium methacrylate and 1,500 parts of water, and 75 parts of an aqueous 10% ammonium persulfate solution were added dropwise over 4 hours. After the addition, 20 parts of an aqueous 10% ammonium persulfate solution were added over 1 hour. It was dropped. Thereafter, the temperature was maintained at 95 ° C. continuously for 1 hour to complete the solution polymerization reaction. Then, the mixture is neutralized with a 30% aqueous sodium hydroxide solution to obtain a weight average molecular weight of 35.0.
00, a comparative cement dispersant (7) comprising a polymer aqueous solution having a peak top molecular weight of 18,300 was obtained.

To produce the comparative cement dispersant (8)
Comparative Reference Example 8 1551 parts of water was charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, and the inside of the reaction vessel was replaced with nitrogen under stirring, and then, under a nitrogen atmosphere. Heated to 80 ° C. Next, 1668 parts of methoxypolyethylene glycol monomethacrylate (average number of moles of ethylene oxide added: 25), methacrylic acid 32
0 parts, 15 parts of sodium methacrylate and 500 parts of water, a monomer mixture aqueous solution, 184 parts of a 10% ammonium persulfate aqueous solution, 10% mercaptopropionic acid 167
Parts for 4 hours each, and 10% after completion of the addition.
46 parts of an aqueous ammonium persulfate solution was added dropwise over 1 hour.
Subsequently, the temperature was maintained at 80 ° C. for 1 hour to complete the solution polymerization reaction. The mixture was neutralized with a 30% aqueous sodium hydroxide solution to obtain a comparative cement dispersant (8) comprising a polymer aqueous solution having a weight average molecular weight of 21,000 and a peak top molecular weight of 12,700.

Tables 3 and 4 show the contents of the comparative cement dispersants (1) to (8) obtained in Comparative Examples 1 to 8 described above.

[0090]

[Table 3]

[0091]

[Table 4]

Example 1 and Comparative Example 1 Concrete test 1 Ordinary Portland cement (manufactured by Chichibu Onoda Cement Co., Ltd.) as cement, and land sand and Kisarazuyama sand (specific gravity 2.62, FM 2.71) as fine aggregate as fine aggregates , Hard sandstone crushed stone from Ome as a coarse aggregate (specific gravity 2.64, MS20
mm).

The cement dispersants (2) of the present invention shown in Tables 1 and 2 and the comparative cement dispersants (7) shown in Tables 3 and 4 were used for comparison.

Concrete mixing conditions were as follows: unit cement amount 320 kg / m ³ , unit water amount 166 kg / m ³ , water /
Cement ratio 51.9%, water reduction rate 18%, fine aggregate rate 4
9%, and the amount (parts by weight) of the cement dispersant added to 100 parts by weight of the cement solid content was as shown in Table 5 below. The amount of air was adjusted to 4 ± 1% using a commercially available air entrainer as needed.

Under the above conditions, 50 liters of concrete was produced using a forced kneading mixer, and the change with time of the slump was measured. In addition, the measurement of the slump and the air amount were all performed in Japanese Industrial Standards (JIS A 1101, 1128,
6204). Table 5 shows the results.

[0096]

[Table 5]

Table 5 shows that the slump retention time of concrete using the cement dispersant of the present invention is improved as compared with the case of using the comparative cement dispersant.
That is, like the cement dispersant (2) of the present invention, it is preferable for the slump retention performance to perform the solution polymerization reaction at a polymerization temperature equal to or lower than the cloud point of the monomer mixture (I).

Example 2 and Comparative Example 2 Concrete Test 2 Ordinary Portland cement (manufactured by Chichibu Onoda Cement Co., Ltd.) as cement, land sand from Oigawa water system (specific gravity 2.62, FM 2.71) as coarse aggregate, coarse aggregate As a hard sandstone crushed stone from Ome (specific gravity 2.64, MS 20 mm).

The cement dispersants (1) of the present invention shown in Tables 1 and 2 and the comparative cement dispersants (8) shown in Tables 3 and 4 were used for comparison.

Concrete mixing conditions were as follows: unit cement amount 660 kg / m ³ , unit water amount 165 kg / m ³ , water /
The cement ratio is 25% and the fine aggregate ratio is 40%.
The amount (parts by weight) of the cement dispersant added to 100 parts by weight of the cement solid content was as shown in Table 6 below. The air amount was adjusted to 1 to 2% using a commercially available defoamer.

Under the above conditions, the mortar was first kneaded for 90 seconds with a forced kneading mixer, and then coarse aggregate was added and kneaded for 90 seconds to produce 50 liters of concrete. Then, the time until the mortar was fluidized and the change with time of the slump flow value of the obtained concrete were measured. The measurement of the slump flow value and the amount of air were all performed according to Japanese Industrial Standards (JIS A 1101, 1
128, 6204). Table 6 shows the results.

[0102]

[Table 6]

From Table 6, it can be seen that the slump holding time and the water reducing performance of the concrete using the cement dispersant of the present invention are improved as compared with the case using the comparative cement dispersant. That is, like the cement dispersant (1) of the present invention, the solution polymerization reaction in which the monomer mixture (I) and the chain transfer agent are previously mixed and then dropped into the reaction vessel prevents slump loss and reduces the amount of addition. It is preferable for reduction.

Further, from Tables 5 and 6, the slump holding performance and the water reducing performance depend on the polymerization method for producing the cement dispersant, and this is caused by the difference in the molecular weight distribution of the polymer as described above. For example, the molecular weight distributions of the cement dispersant (2) of the present invention and the comparative cement dispersant (7) are shown in FIG.
Shown in

Examples 3 to 5 and Comparative Examples 3 to 7 Mortar test Cement dispersants (1) to (1) of the present invention shown in Tables 1 and 2
(3) and for comparison, in order to observe the basic performance of the comparative cement dispersants (1) to (3), (6) and (8) shown in Tables 3 and 4, The flow value and air volume were measured. Mortar is 400 parts of ordinary Portland cement manufactured by Chichibu Onoda Cement Co., Ltd.
800 parts of standard sand from Toyoura and 240 parts of water containing the cement dispersant of the present invention or the comparative cement dispersant were kneaded with a mortar mixer. Then, the obtained mortar was placed on a horizontal table and had an inner diameter of 55 mm × a height of 5 mm.
A 5-mm hollow cylinder was packed to the extent of fraying, the cylinder was gently lifted vertically, and then the major axis and minor axis of the mortar spread on the table were measured. The average value was taken as the flow value. Also,
The air amount was calculated from the volume and weight of the obtained mortar and the specific gravity of the material used. Table 7 shows the results.

[0106]

[Table 7]

From Examples 3 to 5 and Comparative Examples 3 and 4, it can be seen that the lower the neutralization ratio of the monomer mixture (I), the higher the flow value, which is preferable.

In Example 4, Comparative Example 5 and Comparative Reference Example 4, the polymerization temperature was 50 ° C., the cloud point of the monomer mixture (I) or lower, and the neutralization rate of the monomer mixture (I) was 10%. Examination of the optimum polymerization concentration in this case shows that gelation occurs at a polymerization concentration of 50% and air entrainment is high at a polymerization concentration of 30%, which is inappropriate for each case.

In Example 5 and Comparative Example 6, and in Example 4 and Comparative Reference Example 5, the influence of the difference in the polymerization mode was examined. First, it is understood that a chain transfer agent is indispensable for suppressing the gelation of the polymer in the batch method in which the monomer mixture is charged into the reaction vessel all at once. And it can be seen that even with the polymer obtained in this way, a higher flow value can be obtained by the dropping method in which the monomer mixture is dropped into the reaction vessel.

Comparing Example 3 with Comparative Example 7, a higher flow value can be obtained by previously mixing the chain transfer agent with the monomer mixture (I) and conducting a solution polymerization reaction. This is of course consistent with the results in Table 6.

Examples 6 to 10 and Comparative Example 8 Measurement of Adsorption Rate to Cement Cement dispersants (1) to (1) of the present invention shown in Tables 1 and 2
(5) And for comparison, the adsorption rate of naphthalenesulfonic acid formalin condensate (NSF) to cement was measured. The measuring method is shown below.

(1) Into a beaker, the cement dispersant (1) of the present invention obtained in Reference Example 1 was added so as to be 0.2% in terms of solid content of cement, and the water / cement ratio ( (Weight ratio) is 10%. (2) A predetermined amount of cement (high flow cement manufactured by Chichibu Onoda Cement Co., Ltd.) is added to a beaker, stirred for 5 minutes, filtered, and the filtrate is collected. (3) The operations of (1) and (2) are repeated with a stirring time of 60 minutes. (4) The concentration of the cement dispersant remaining in the obtained filtrate is measured with a differential refractometer. (5) The same operation is repeated for the cement dispersants (2) to (5) of the present invention obtained in Reference Examples 3 to 7. (6) The adsorption rate of the cement dispersant is defined as follows.

[0113]

Embedded image

If all of the added cement dispersant is adsorbed on the cement, the adsorption rate becomes 100%.
Table 8 shows the results of the adsorption rates.

[0115]

[Table 8]

Table 8 shows that the cement dispersant (1) of the present invention was obtained.
In (3), no increase in the adsorption rate was observed after 60 minutes, indicating that saturated adsorption was reached. On the other hand, the adsorption rates of the cement dispersants (4) and (5) of the present invention were increased even after 120 minutes, and it was found that saturated adsorption was not reached.

Examples 11 to 14 and Comparative Example 9 Concrete Test 3 The cement dispersants used were the cement dispersants (1), (2), (4) and (5) of the present invention and naphthalene sulfone for comparison. Except for using the acid formalin condensate (NSF), the time-dependent change of the slump was measured in the same manner as in the concrete test 1 described above. Table 9 shows the results.

[0118]

[Table 9]

Table 9 shows that the cement dispersant of the present invention has better water reducing performance and slump retention performance than NSF. Also, comparing the cement dispersants of the present invention with the results in Table 6, the adsorption rate after 5 minutes to the cement was low, and the difference between the adsorption rate after 60 minutes and the adsorption rate after 5 minutes was low. The larger the slump, the higher the slump holding performance.
It can be seen that the slump after 30 minutes increases as shown in FIG.

Examples 15 to 17 and Comparative Example 10 Concrete test 4 High flow cement (made by Chichibu Onoda Cement Co., Ltd.) as cement, land sand of Oigawa water system (specific gravity 2.62, FM 2.71) as coarse aggregate, coarse bone Hard sandstone crushed stone from Ome (specific gravity 2.64, MS 20 mm) was used as a material.

As the cement dispersant, the cement dispersants (1), (2) and (4) of the present invention shown in Tables 1 and 2 and, for comparison, a naphthalenesulfonic acid formalin condensate (NSF) were used. .

[0122] blending conditions of concrete, the unit amount of cement 553kg / m ^3, unit water 160 kg / m ^3, water /
The cement ratio is 29% and the fine aggregate ratio is 51%.
The amount (parts by weight) of the cement dispersant added to 100 parts by weight of the cement solid content was as shown in Table 10 below.
The air amount was adjusted to 1 to 2% using a commercially available defoamer.

Under the above conditions, the mortar was first kneaded with a forced kneading mixer for 90 seconds, and then coarse aggregate was added and kneaded for 90 seconds to produce 50 liters of concrete. Then, the time until the mortar was fluidized and the change with time of the slump flow value of the obtained concrete were measured. The measurement of the slump flow value and the amount of air were all performed according to Japanese Industrial Standards (JIS A 1101, 1
128, 6204). Table 10 shows the results.
Shown in

[0124]

[Table 10]

Table 10 shows that the water dispersibility of the cement dispersant of the present invention is better than that of NSF. Further, comparing the results of Table 8 with those of the cement dispersants of the present invention, those having a high adsorption rate to cement after 5 minutes of more than 60% have a shorter time required for the mortar to fluidize, It can be seen that good water reducing performance is exhibited. Also,
Comparing Examples 15 and 16, since the cement dispersant of Example 15 has a shorter mortar kneading time despite a lower adsorption rate to cement after 5 minutes, the longer the polyethylene glycol chain, It can be seen that the water reducing performance is improved. On the other hand, Example 17 has the lowest adsorption rate to cement after 5 minutes of 46%, indicating that the slump holding performance is the highest.

Examples 18 to 20 and Comparative Example 11 Concrete Test 5 Ordinary Portland cement (manufactured by Chichibu Onoda Cement Co., Ltd.) as cement, land sand from Oigawa water system (specific gravity 2.62, FM 2.71) as fine aggregate, coarse Ome hard sandstone crushed stone (specific gravity 2.64, MS 20 mm) was used as an aggregate.

The cement dispersants used in the present invention are shown in Tables 1 and 2, and the cement dispersants (1) to (3) of the present invention and, for comparison, naphthalenesulfonic acid formalin condensate (NSF)
Was used.

The concrete mixing conditions were as follows: unit cement amount 550 kg / m ³ , unit water amount 165 kg / m ³ , water /
The cement ratio is 30% and the fine aggregate ratio is 40%.
The amount (parts by weight) of the cement dispersant added to 100 parts by weight of the cement solid content was as shown in Table 11 below.
The air amount was adjusted to 1 to 2% using a commercially available defoamer.

Under the above conditions, the mortar was first kneaded for 40 seconds by a forced kneading mixer, and then coarse aggregate was added and kneaded for 90 seconds to produce 35 liters of concrete. Then, the time until the mortar was fluidized, the slump flow value of the obtained concrete, and the compressive strength for 28 days were measured. The slump flow value,
All measurements of air volume are based on Japanese Industrial Standards (JIS A1).
101, 1128, 6204). Table 11 shows the results.

[0130]

[Table 11]

Table 11 shows that the water reducing performance of the cement dispersant of the present invention is superior to that of NSF. In addition, comparing the cement dispersants of the present invention with the results in Table 8, if the adsorption rate after 5 minutes to cement is 60% or more, there is no correlation with the time required for the mortar to fluidize, but rather It can be seen that the longer the polyethylene glycol chain, the shorter the mortar kneading time and the amount of addition can be reduced.

[0132]

As described above, the cement dispersant of the present invention is a cement dispersant containing a polycarboxylic acid polymer (A) or a salt thereof as a main component, and the weight of the polymer (A) is high. The average molecular weight is in the range of 10,000 to 500,000 in terms of polyethylene glycol by GPC,
In addition, a value obtained by subtracting the peak top molecular weight from the weight average molecular weight is 0 to 8,000.

The cement dispersant according to the present invention is excellent in water reducing performance and eliminates slump loss which is a problem of the conventional high performance AE water reducing agent. Therefore, according to the cement dispersant, a cement composition such as concrete can be kneaded under a high water reduction rate, and since slump loss is extremely small, obstacles in quality control and construction of the obtained concrete can be improved. In particular, the cement dispersant according to claim 4 of the present invention has remarkably improved slump retention performance, and the cement dispersant according to claim 5 of the present invention has sufficient sludge retention even at a cement composition having an extremely low water / cement ratio. It ensures liquidity.

The method for producing a cement dispersant of the present invention is a method capable of more effectively imparting slump holding performance and water reducing performance to the obtained cement dispersant, and is economically excellent. is there.

Further, in the cement composition of the present invention, the slump holding time and the water reducing performance can be far improved as compared with the conventional one.

[Brief description of the drawings]

FIG. 1 is a view showing the molecular weight distributions of a cement dispersant (2) of the present invention and a comparative cement dispersant (7).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08F 220/18 C08F 220/18 290/06 290/06 // C04B 103: 40 (72) Inventor Takeshi Ken Hirata Kawasaki, Kawasaki City, Kanagawa Prefecture 14-1 Chidoricho, Chidori-cho, Japan Nippon Shokubai Co., Ltd. (72) Inventor Tohru Uno 14-1 Chidoricho, Kawasaki-ku, Kawasaki, Kawasaki, Kanagawa Pref. 14-1 Machi, Inc. Nippon Shokubai Co., Ltd. (72) Inventor Hideyuki Tahara 14-1, Chidori-cho, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Nippon Shokubai Co., Ltd. (56) References JP-A-7-10943 (JP, A) JP-A-6-25358 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 24/26 C04B 28/02 C08F 220/18 C08F 290/06

Claims (10)

(57) [Claims] 1. An (alkoxy) polyalkylene glycol
Lumono (meth) acrylate monomer (a) 5
98% by weight, (meth) acrylic acid monomer (b) 95-
2% by weight and other units copolymerizable with these monomers.
(C) 0 to 50% by weight (provided that (a), (b) and
And (c) is a cement dispersant containing a polycarboxylic acid-based polymer (A) or a salt thereof as a main component, which is obtained by copolymerizing 100% by weight). The weight average molecular weight of A) is 10,000 to 5 in terms of polyethylene glycol by gel permeation chromatography.
A cement dispersant, wherein the value is within the range of 00000 and the value obtained by subtracting the peak top molecular weight from the weight average molecular weight is 0 to 8,000. 2. A lower following general formula (1): ## STR1 ## (Wherein R ¹ represents hydrogen or a methyl group,
R ² O represents one or a mixture of two or more oxyalkylene groups having 2 to 4 carbon atoms. In the case of two or more, R ² O may be added in block form or in random form. ³ represents hydrogen or an alkyl group having 1 to 5 carbon atoms, m represents a value indicating the average number of added moles of the oxyalkylene group, and represents an integer of 1 to 100. 5 to 98% by weight of an (alkoxy) polyalkylene glycol mono (meth) acrylate monomer (a) represented by the following general formula (2): (Wherein, R ⁴ represents hydrogen or a methyl group, and M ¹ represents hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group). 95 to 2% by weight of a compound (b) and 0 to 50% by weight of another monomer (c) copolymerizable with these monomers (however, the total of (a), (b) and (c)) Is 100
% By weight) and a polycarboxylic acid polymer obtained by copolymerizing
A cement dispersant containing (A) or a salt thereof as a main component.
The weight average molecular weight of the polymer (A) is
Polyethylene glycol by aeration chromatography
Within the range of 10,000 to 500,000 in terms of call
And the peak top molecular weight is different from the weight average molecular weight.
A cement dispersant characterized in that the subtracted value is from 0 to 8,000 . 3. The (alkoxy) polyalkylene glycol mono (meth) acrylate monomer (a) is (methoxy) polyethylene glycol mono (meth) acrylate, and the (meth) acrylic acid monomer is (B)
There (meth) cement dispersant according to claim 1 or 2 wherein the acrylic acid. 4. The polymer (A) having an adsorption rate to cement particles of 0.2% by weight based on cement,
The cement dispersant according to any one of claims 1 to 3, wherein the content is less than 60% for 5 minutes at room temperature. 5. An adsorption rate of the polymer (A) to cement particles when 0.2% by weight of cement is added to cement.
The cement dispersant according to any one of claims 1 to 3, wherein the content is 60% or more in 5 minutes at room temperature. 6. An (alkoxy) polyalkylene glycol
Lumono (meth) acrylate monomer (a) 5
98% by weight, (meth) acrylic acid monomer (b) 95-
2% by weight and other units copolymerizable with these monomers.
(C) 0 to 50% by weight (provided that (a), (b) and
And a total of 100% by weight of (c))
The amount of (I) used is 10 to 2 with respect to the total amount of the raw materials used.
In the range of 8% by weight, and the polymerization is carried out with the monomer mixture (I).
Carried out at a temperature below the cloud point and further of the monomer mixture (I)
Under the condition that the neutralization ratio is in the range of 0 to 20 mol%,
The body mixture (I) is dropped into a reaction vessel containing water.
Cement dispersion characterized by performing a solution polymerization reaction
Method of manufacturing the agent. 7. An (alkoxy) polyalkylene glycol
Lumono (meth) acrylate monomer (a) 5
98% by weight, (meth) acrylic acid monomer (b) 95-
2% by weight and other units copolymerizable with these monomers.
(C) 0 to 50% by weight (provided that (a), (b) and
And a total of 100% by weight of (c))
(I) the neutralization ratio is in the range of 0 to 20 mol%, and
The monomer mixture (I) is mixed with a chain transfer agent before the polymerization reaction.
Under the following conditions, the monomer mixture (I) and the chain transfer agent
The solution polymerization reaction is carried out by dropping into a reaction vessel containing water.
A method for producing a cement dispersant. 8. following general formula (1): ## STR3 ## (Wherein R ¹ represents hydrogen or a methyl group,
R ² O is one of oxyalkylene groups having 2 to 4 carbon atoms or
Represents a mixture of two or more types, and a block
May be added in a random shape
R ³ represents hydrogen or an alkyl group having 1 to 5 carbon atoms
And m is a value indicating the average number of added moles of the oxyalkylene group.
And represents an integer of 1 to 100. ) (Al
Coxy) polyalkylene glycol mono (meth) acryl
Lulic ester monomer (a) 5 to 98% by weight, the following general
Equation (2): ## STR00004 ## (Wherein, R ⁴ represents hydrogen or a methyl group.
And M ¹ is a hydrogen, monovalent metal, divalent metal, ammonium group
Or represents an organic amine group. ) (Meta)
95 to 2% by weight of crylic acid monomer (b), and these
0 to 50 weight of another monomer (c) copolymerizable with the monomer of
% (The sum of (a), (b) and (c) is 100
% By weight of the monomer mixture (I) comprising the monomer mixture (I) is within the range of 10 to 28% by weight based on the total amount of the raw materials used, and the polymerization is carried out at a temperature below the cloud point of the monomer mixture (I). solution polymerization by performed, further dropping the monomer mixture neutralization rate under conditions in the range of 0 to 20 mol% of the monomer mixture (I) and (I) to a reaction vessel containing water at A method for producing a cement dispersant, comprising performing a reaction. 9. following general formula (1): embedded image (Wherein R ¹ represents hydrogen or a methyl group,
R ² O is one of oxyalkylene groups having 2 to 4 carbon atoms or
Represents a mixture of two or more types, and a block
May be added in a random shape
R ³ represents hydrogen or an alkyl group having 1 to 5 carbon atoms
And m is a value indicating the average number of added moles of the oxyalkylene group.
And represents an integer of 1 to 100. ) (Al
Coxy) polyalkylene glycol mono (meth) acryl
Lulic ester monomer (a) 5 to 98% by weight, the following general
Equation (2): ## STR00006 ## (Wherein, R ⁴ represents hydrogen or a methyl group.
And M ¹ is a hydrogen, monovalent metal, divalent metal, ammonium group
Or represents an organic amine group. ) (Meta)
95 to 2% by weight of crylic acid monomer (b), and these
0 to 50 weight of another monomer (c) copolymerizable with the monomer of
% (The sum of (a), (b) and (c) is 100
% By weight) of the monomer mixture (I)
A reaction containing the monomer mixture (I) and the chain transfer agent under water under the condition that the monomer mixture (I) is mixed with a chain transfer agent before the polymerization reaction. A method for producing a cement dispersant, comprising performing a solution polymerization reaction by dropping the solution into a container. 10. A cement composition comprising at least cement, water and a cement dispersant, wherein the cement composition comprises:
Or a cement composition containing the cement dispersant according to 2 above.