JP2003286058A - Cement dispersing agent and cement composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement dispersing agent having excellent water initially reducing property, strength expressing property and aging stability. <P>SOLUTION: This cement dispersing agent contains as an effective component a copolymer and/or its salt which is obtained by reacting 40-80 wt.% polyalkylene glycol mono(meth)acrylate-based monomer (a), 5-30 wt.% mono(meth)acrylate-based monomer (b), 10-40 wt.% carboxylic acid-based monomer (c) having an unsaturated bond and 0-30 wt.% monomer copolymerizable with these monomers. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cement dispersant used as a concrete admixture and a cement composition containing the same.

[0002]

2. Description of the Related Art In recent years, due to the increase in size of concrete structures, it has been required to increase the strength of concrete. Therefore, in order to reduce the amount of unit water and realize higher strength, a high-performance AE water reducing agent having both high water reducing property and excellent stability over time has been developed. The high-performance AE water reducing agent is classified into polycarboxylic acid type polymer, naphthalene sulfonic acid formaldehyde condensate, melamine sulfonic acid formaldehyde condensate, lignin sulfonic acid, and amino sulfonic acids as the main components. Among these, a polycarboxylic acid type high performance AE water reducing agent containing a water-soluble carboxylic acid type polymer having an oxyalkylene group in a graft chain as a main component (for example, JP-B-59-18338 and JP-A-8-11970).
No. 1, JP-A-9-286645 and the like) show higher water reduction. On the other hand, from the deterioration of the quality of aggregate used in concrete mixes and the problems of traffic conditions in urban areas,
The importance of maintaining the fluidity of concrete for a certain period of time is emphasized. This performance is called stability over time, but this point is still insufficient with conventional high-performance AE water reducing agents, and there has been a strong demand for a dispersant having excellent stability over time.

[0003]

Therefore, an object of the present invention is to provide a cement dispersant which exhibits higher initial water reduction, higher strength development, and higher stability over time than conventional cement dispersants. Is to provide.

[0004]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have achieved the above object by using a cement dispersant which is a copolymer composed of a specific monomer and / or a neutralization salt thereof. I found a solution.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polyalkylene glycol (meth) acrylic acid ester monomer (a) used in the present invention is represented by the general formula (1).

[0006]

Embedded image General formula (1)

R ₁ : hydrogen atom or methyl group R ₂ O: oxyethylene group, or oxypropylene group m: integer of 5 to 50 R ₃ : hydrogen or alkyl group having 1 to 3 carbon atoms, specifically polyethylene glycol Polyethylene glycol mono (meth) acrylic acid esters such as (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate; polypropylene glycol (meth)
Polypropylene glycol mono (meth) acrylic acid esters such as acrylate, methoxy polypropylene glycol (meth) acrylate, ethoxy polypropylene glycol (meth) acrylate; and those in which these polyalkylene glycol moieties are used in combination with ethylene glycol and propylene glycol It is possible,
These may be added in blocks or randomly. Furthermore, these are 1 type or 2 types.
More than one species can be used together.

The mono (meth) acrylic acid ester monomer (b) used in the present invention is represented by the general formula (2).

[0009]

Embedded image General formula (2)

R _{4 is a} hydrogen atom or a methyl group R _{5 is} an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group in which a part of the alkyl group is substituted with a hydroxyl group, a part of the alkyl group is a methoxy group, ethoxy An alkoxyalkyl group substituted with an alkoxy group such as a group, or a benzyl group or a cyclohexyl group which may be partially substituted with a hydroxyl group or an alkoxy group (methoxy group, ethoxy group, etc.), specifically, (meth) acrylic acid Methyl, ethyl (meth) acrylate, propyl (meth) acrylate, (meth)
I-butyl acrylate, n-butyl (meth) acrylate,
Lower alcohol esters such as t-butyl (meth) acrylate, lower diols such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate, and (meth ) Esters with acrylic acid, (meth) acrylic acid 2-methoxyethyl, (meth) acrylic acid ester of lower diol monoalkyl ether such as 2-ethoxyethyl acrylate,
Examples thereof include esters of (meth) acrylic acid such as cyclohexyl (meth) acrylate and benzyl (meth) acrylate with an alicyclic or aromatic ring alcohol, and these can be used alone or in combination of two or more.

The carboxylic acid type monomer (c) having an unsaturated bond used in the present invention is represented by the general formula (3).

[0012]

Embedded image General formula (3)

R6, R7, R8: hydrogen or a methyl group or (CH ₂ ) _m COOM (m is an integer of 0 to 2) M: hydrogen atom, monovalent metal atom, divalent metal atom, ammonium group or organic amine Specifically, acrylic acid, methacrylic acid, maleic acid,
Examples thereof include fumaric acid, itaconic acid, citraconic acid and the like, or salts thereof such as alkali metal salts, alkaline earth metal salts, ammonium salts and organic amine salts. These may be used alone or in combination of two or more. Of these, acrylic acid, methacrylic acid, maleic acid, and / or salts thereof are particularly preferable.

The monomer (d) copolymerizable therewith used in the present invention is copolymerizable with the above-mentioned monomers (a), (b) and (c). It is a monomer. Examples of the monomer (d) include monoesters or diesters of a dicarboxylic acid such as maleic acid fumaric acid and an alcohol, unsaturated amides such as (meth) acrylamide, vinyl esters such as vinyl acetate and vinyl propionate. , Vinyl sulfonic acid, sulfoethyl (meth) acrylate, 2-methylpropane sulfonic acid (meth) acrylamide, unsaturated sulfonic acids such as styrene sulfonic acid and their metal salts, ammonium salts, organic amine salts, aromatics such as styrene Aromatic allyls such as vinyls and allylphenol may be mentioned, and these may be used alone or in combination of two or more.

In particular, when 0.1 to 10% by weight of (meth) allyl bisphenol is used as the monomer (d), the compressive strength development of the hardened concrete is enhanced. In the present invention, the (meth) allyl bisphenols are represented by the following general formula (4), (5) or (6).

[0016]

Embedded image General formula (4)

[0017]

Embedded image General formula (5)

[0018]

Embedded image General formula (6)

For example, 4,4'-dihydroxydiphenylpropane, 4,4'-dihydroxydiphenylmethane, 4,4'-
3-position allyl substitution product of dihydroxydiphenyl sulfone,
Alternatively, 3 and 3′-position allyl substitution products and the like can be mentioned.

In the present invention, the monomer (a) is 40 to 80% by weight, the monomer (b) is 5 to 30% by weight, the monomer (c) is 10 to 40% by weight, and the monomer (d) is ) 0-30% by weight (however, (a) +
It is necessary to react at a ratio of (b) + (c) + (d) = 100% by weight). If the ratio is out of the above range, the water-reducing property may be poor, the strength developing property may be deteriorated, or the temporal stability may be further deteriorated.

The monomers (a), (b), (c) of the present invention,
The copolymer composed of (d) can be produced by a known method. The copolymerization can be carried out by a method such as polymerization in a solvent or bulk polymerization.

As the solvent, water, lower alcohols such as methanol, ethanol, isopropanol and butanol; aromatic hydrocarbons such as benzene, toluene and xylene; alicyclic hydrocarbons such as cyclohexane; esters such as ethyl acetate; acetone. Examples thereof include ketones such as methyl ethyl ketone, and water and lower alcohols are preferable from the viewpoint of solubility of monomers and polymers.

In the copolymerization, each of the monomers and the polymerization initiator may be continuously dropped into the reaction vessel, or the mixture of the monomers and the polymerization initiator may be continuously dropped into the reaction vessel. Alternatively, a solvent may be charged to the reaction vessel, and the mixture of the monomer and the solvent and the polymerization initiator solution may be continuously added dropwise to the reaction vessel, or a part or all of the monomer may be charged to the reaction vessel to start the polymerization. The agent may be continuously dropped.

As the polymerization initiator used for the copolymerization, persulfates such as ammonium persulfate, sodium persulfate and potassium persulfate in a water solvent; or water-soluble organic peroxides such as t-butyl hydroperoxide are used. be able to. At this time, an accelerator such as sodium bisulfite and Mohr's salt may be used in combination. When an organic solvent is used, peroxides such as benzoyl peroxide and lauryl peroxide; hydroperoxides such as cumene hydroperoxide; aromatic azo compounds such as azobisisobutyronitrile can be used. At this time, an accelerator such as an amine can be used together. The polymerization temperature varies depending on the solvent, but is usually within the range of 50 to 120 ° C.

In the copolymerization reaction, the molecular weight can be adjusted by using a chain transfer agent, if necessary. The chain transfer agent used is, for example, a lower alkyl mercaptan,
Lower mercapto fatty acids, thioglycerin, thiomalic acid, 2-mercaptoethanol and the like can be mentioned.

The weight average molecular weight of the polymer is from 10,000 to 300.
00 or less is preferable. When it is less than 10,000, the initial water-reducing property is not exhibited. Further, when it exceeds 30,000, excellent stability with time is not exhibited. More preferably, it is 10000 or more and 25000 or less. The weight average molecular weight in the present invention is determined by gel permeation chromatography (GPC, standard substance polyethylene glycol, column: Shodex OHpak SB-
806 HQ + SB-804 HQ + SB-802.5 HQ, eluent: 0.05M NaN
O ₃ aqueous solution / acetonitrile = 8/2 (volume ratio)).

When copolymerizing in a water solvent, pH at the time of polymerization
Usually becomes strongly acidic under the influence of a monomer having an unsaturated bond, but it may be adjusted to an appropriate pH. However, the pH is preferably 8 or less in order to suppress the hydrolysis of the ester-based monomer. The alkali used for pH adjustment is not particularly limited, but usually NaOH, Ca (OH) ₂ or the like is common. Further, the pH adjustment may be performed on the monomer before the polymerization or on the copolymer solution after the polymerization.
Further, these may be polymerized by adding a part of alkali before the polymerization, and then the pH of the copolymer may be further adjusted.

The cement dispersant of the present invention is a known cement dispersant (for example, polycarboxylic acid type cement dispersant,
Naphthalene sulfonic acid type dispersant, melamine sulfonic acid type dispersant, lignin sulfonic acid type dispersant, amino sulfonic acid type dispersant, etc.) and thickeners, AE agents, defoaming agents, effect accelerators, etc. It is possible. When used in combination, the cement dispersant of the present invention accounts for 50% by weight of the whole (solid content mixing ratio)
It is preferable to mix the above. In particular, the combined use with a lignin sulfonic acid-based dispersant has the effect of improving stability over time.

The addition rate of the cement dispersant of the present invention to cement is usually 0.1 to 1.5% in terms of solid content addition rate.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following examples. In the examples, unless otherwise specified,% means% by weight,
Moreover, a part shows a weight part.

[Production Example 1] 507 parts by weight of water was charged into a reaction vessel equipped with a stirrer, a reflux device and a dropping device, and 1
The temperature was raised to 00 ° C. Then, 114 parts by weight of methoxypolyoxyethylene methacrylate (average added mole number 9),
Mixed solution (1) of 13 parts by weight of ethyl methacrylate, 30 parts by weight of acrylic acid, 4 parts by weight of diallyl substitution product of 4,4′-dihydroxydiphenylsulfone and 69 parts by weight of water.
Then, a mixed solution (2) of 3.5 parts by weight of ammonium persulfate and 60 parts by weight of water was continuously added dropwise to the reaction container kept at 100 ° C. for 2 hours. Further, the temperature was kept at 100 ° C. and the reaction was carried out for 1 hour to obtain an aqueous suspension of the copolymer. This solution was adjusted to pH 7 with a 30% NaOH aqueous solution.
The result of measuring the weight average molecular weight of the copolymer is 23,000.
Met.

[Production Example 2] 505 parts by weight of water was charged into a reaction vessel equipped with a stirrer, a reflux device, and a dropping device, and
The temperature was raised to 0 ° C. Then, 99 parts by weight of methoxypolyoxyethylene methacrylate (average addition mole number: 9), 2-
26 parts by weight of hydroxyethyl acrylate, 34 parts by weight of methacrylic acid, 8 parts by weight of 30% NaOH aqueous solution, 4,4'-
Mixed solution (1) of 3 parts by weight of diallyl substitution product of dihydroxydiphenyl sulfone and 69 parts by weight of water, and mixed solution of 3.8 parts by weight of ammonium persulfate and 60 parts by weight of water (2)
Was continuously added dropwise to the reaction vessel kept at 90 ° C. for 3 hours. Further, the temperature was maintained at 90 ° C. and the reaction was carried out for 1 hour to obtain an aqueous suspension of the copolymer. 30% of this liquid
The pH was adjusted to 7 with aqueous NaOH. The weight average molecular weight of the copolymer was measured and found to be 22000.

[Production Examples 3 to 10] Under the conditions shown in Table 1, a copolymer was produced in the same manner as in Example 1.

[0034]

[Table 1]

A1: methoxypolyoxyethylene methacrylate (average number of moles added: 9) a2: methoxypolyoxyethylene methacrylate (average number of moles added: 23) b1: ethyl methacrylate b2: 2-hydroxyethyl acrylate b3: 2-hydroxypropyl methacrylate b4: 2-methoxyethyl methacrylate b5: methyl methacrylate c1: acrylic acid c2: methacrylic acid c3: maleic anhydride d1: 4,4′-dihydroxydiphenylsulfone diallyl substitution product d2: 4,4′-dihydroxydiphenylmethane Diallyl Substituted d3: 4,4'-Dihydroxydiphenylpropane Diallyl Substituted d4: Acrylamide e1: Ammonium Persulfate e2: Sodium Persulfate ^{* 1} : The units of each item in the table are the same as in Production Example 1. ^{* 2} : In Production Example 2, 30% Na was added to the mixed solution (1).
Add 8 parts by weight of OH aqueous solution. ^{* 3} : The figures in parentheses indicate the amount of raw materials used.

[Production Example of Known Cement Dispersant (Polycarboxylic Acid Type, hereinafter Abbreviated as PC Agent)] Polymerization was carried out as follows according to Reference Example 3 of JP-B-59-18338. 560.7 parts of water was charged into a reaction vessel equipped with a thermometer, a dropping funnel, a nitrogen gas introduction tube, and a stirrer, and the atmosphere was replaced with nitrogen while stirring and heated to 95 ° C. Next, a monomer mixture solution consisting of 75 parts of methoxypolyoxyethylene methacrylate (NK Ester M-230G, Shin Nakamura Chemical Co., Ltd., average ethylene oxide addition mole number 23), 25 parts of acrylic acid and 300 parts of water, and a 5% excess Each of them with 34.5 parts of ammonium sulfate aqueous solution was added in 120 minutes, and after the addition was completed, 6.8 parts of 5% ammonium persulfate aqueous solution was added in 20 minutes. After this addition was completed, the temperature was kept at 95 ° C. for 120 minutes to complete the polymerization. Then, the solution was neutralized with a NaOH solution to obtain an aqueous solution of the copolymer. The weight average molecular weight of the copolymer was measured and found to be 32000.

[Concrete test] A fine aggregate, coarse aggregate, cement, water and a cement dispersant shown in Table 3 were charged in a 50-liter twin-screw forced kneading type concrete mixer according to the mixing ratio of Table 2, and 90 Concrete (30 liters) was prepared by kneading for 2 seconds. Also, the air volume is AE
The agent (AE-4, manufactured by Nippon Paper Industries Co., Ltd.) and the defoaming agent (Trimin DF325, manufactured by Miyoshi Yushi Co., Ltd.) were added to adjust the concentration to 4.0 to 5.0%. The slump of the obtained concrete (immediately after kneading, after 30 minutes and after 60 minutes) and the compressive strength after 28 days were measured, and the results are shown in Table 3. Air volume, slump, and compression strength are JIS A 1128 and JIS A, respectively.
1101, JIS A 1108.

[0038]

[Table 2]

C cement: Three kinds of ordinary Portland cement (manufactured by Mitsubishi Ube Cement Co., Ltd., Taiheiyo Cement Co., Ltd., Sumitomo Osaka Cement Co., Ltd.) Specific gravity 3.16 W Water: Tap water S Fine aggregate: Kimitsu Sanriku Sand / Kodama land sand = 6/4 Specific gravity 2.60 FW (coarse grain ratio) 2.66 G Coarse aggregate: Ome crushed stone Specific gravity 2.65 Actual rate 60.8%

[0040]

[Table 3]

[0041]

As described above, since the cement dispersant of the present invention can obtain a predetermined fluidity with a small addition rate, it is clear that the initial water-reducing property is high. Moreover, the cement dispersant of the present invention has high fluidity and excellent stability over time. Furthermore, the cement dispersant of the present invention has high strength development. Therefore, according to the present invention, it is possible to provide a cement dispersant that is excellent in initial water-reducing property, has high strength development property, and is excellent in stability over time as compared with conventional cement dispersants.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08F 290/06 C08F 290/06 // C04B 103: 32 C04B 103: 32 103: 40 103: 40 111: 20 111: 20 (72) Inventor Takaaki Ueda 2-8-1 Iida-cho, Iwakuni-shi, Yamaguchi F-Term (Reference), Chemicals Research Laboratory, Nippon Paper Industries Co., Ltd. (reference) 4G012 PB27 PB31 PB32 PC02 PC03 PC12 4J027 AC02 AC06 BA06 BA07 CD00

Claims (3)

[Claims] 1. A polyalkylene glycol mono (meth) acrylic acid ester monomer (a) represented by the general formula (1) (40 to 80% by weight) and a mono (meth) acrylic acid represented by the general formula (2). Ester monomer (b) 5 to 30% by weight,
10 to 40% by weight of an unsaturated bond-containing carboxylic acid monomer represented by the general formula (3), and 0 to 30% by weight of a monomer (d) copolymerizable therewith (however, (( a) + (b) +
(C) + (d) = 100% by weight), and / or a copolymer salt obtained by further neutralizing the copolymer with an alkaline substance. Cement dispersant. [Formula 1] General formula (1) R ₁ : a hydrogen atom or a methyl group R ₂ O: an oxyethylene group, or an oxypropylene group m: an integer of 5 to 50 R ₃ : hydrogen or an alkyl group having 1 to 3 carbon atoms embedded image General formula (2) R _{4 is a} hydrogen atom or a methyl group R _{5 is} an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group in which a part of the alkyl group is substituted with a hydroxyl group, a part of the alkyl group is a methoxy group, an ethoxy group, or the like. Alkoxyalkyl group substituted with an alkoxy group, or a benzyl group or cyclohexyl group which may be partially substituted with a hydroxyl group or an alkoxy group (methoxy group, ethoxy group, etc.) ## STR3 ## R6, R7, R8: hydrogen or a methyl group or (C
H ₂ ) _m COOM (m is an integer of 0 to 2) M: hydrogen atom, monovalent metal atom, divalent metal atom, ammonium group or organic amine group 2. The cement dispersant according to claim 1, wherein the monomer (d) is 0.1 to 10% by weight of (meth) allyl bisphenols. 3. The cement dispersant according to claim 1 or 2,
A cement composition containing cement and water.