JPH11139855A - Cement additive and production of hydrophilic graft polymer used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new cement additive which exhibits high cement dispersing property in a small added amt. and a method to produce a hydrophilic graft polymer used for the cement additive. SOLUTION: A cement additive contains a hydrophilic graft polymer having wt. average mol.wt. of >=6,000 as an essential component. The graft polymer is obtd. by graft-polymerizing an ethylenic unsatd. monomer essentially including an unsatd. carboxylic acid monomer essentially including an α,β-unsatd. dicarboxylic acid and/or its anhydride to a polyether compd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement additive and a method for producing a hydrophilic graft polymer used therein.

[0002]

2. Description of the Related Art Cement compositions such as cement water paste (cement water slurry), mortar, concrete, etc.
It is an indispensable material for many construction and civil engineering structures.
Generally, in order to obtain good workability of the cement composition, it is sufficient to increase the amount of water (W / C) with respect to the cement to increase the fluidity of the cement composition. The strength of the cured product of the composition is reduced. Therefore, it is proposed to add various water reducing agents (cement dispersants) to the cement composition, which can secure good workability even if the W / C is reduced and can arbitrarily obtain a desired high strength. It has been. As such a water reducing agent, for example, a naphthalene-based water reducing agent is widely known. However, this water reducing agent has a problem that the ultimate water reduction rate is low.

[0003] On the other hand, the air contained in the cement composition is called entrained air. If the amount is large, the strength of the cement composition after curing is reduced. Conversely, if the amount of entrained air is small, resistance to freezing and thawing is reduced. descend. Therefore, there is an optimal amount of entrained air, and a water reducing agent that excessively entrains air is not preferable. For these reasons, a water reducing agent having both high water reducing performance (cement dispersing performance) and appropriate air entrainment (AE property) is required. The water reducing agent is preferably as inexpensive as possible and easily available.

[0004] JP-A-55-71710 and JP-A-5-71710
JP-A-9-62614, JP-A-7-53645,
JP-A-8-208769, JP-A-8-20877
No. 0 discloses a hydrophilic graft polymer obtained by graft-polymerizing an unsaturated carboxylic acid monomer such as (meth) acrylic acid to a polyether compound, and is disclosed in JP-A-7-53645. JP-A-8-208767 and JP-A-8-208770 describe that this polymer can be used as a dispersant for a water slurry of cement.

However, Japanese Patent Application Laid-Open No. 55-71710 discloses
JP-A-59-62614, JP-A-7-53645
JP, JP-A-8-208767, JP-A-8-2876
The above-mentioned hydrophilic graft polymer disclosed in JP 08770-A or the like has a problem that when it is actually added to a water slurry of cement, the cement dispersing performance cannot be sufficiently obtained. Further, the above publication does not disclose at all whether the hydrophilic graft polymer can be used as a cement additive in cement compositions other than a cement water slurry, for example, mortar and concrete.

On the other hand, European Patent Publication No. 0271435 (A
No. 2) discloses a hydrophilic graft polymer having a number average molecular weight of 50,000 or less obtained by graft-polymerizing an unsaturated carboxylic acid monomer onto a polyether compound having a number average molecular weight of 200 to 30,000, There is disclosed an example in which a cement composition such as mortar or concrete is used as a fluidizing agent (water reducing agent). According to the above-mentioned European publication, the hydrophilic graft polymer functions as a fluidizing agent with a small amount of addition (page 13, line 13).

[0007]

However, the hydrophilic graft polymer disclosed in the above-mentioned European publication is suitable for the purpose of providing a cement additive at a low price, but it is not practical to obtain sufficient fluidity. Must be used a lot, and another economic effect is not enough. Therefore, a first object of the present invention is to solve the above-mentioned problems and provide a novel cement additive having a high cement dispersibility (water-reduction) with a small amount of addition.
An object of the present invention is to provide a method for producing a hydrophilic graft polymer used in the method.

A second object of the present invention is to solve the above-mentioned problems and to provide a novel cement having a high cement dispersibility (water-reducing property) with a small amount of addition and an appropriate air entrainment (AE property). An object of the present invention is to provide an additive and a method for producing a hydrophilic graft polymer used for the additive.

[0009]

Means for Solving the Problems The present inventors have conducted various studies on how to reduce the amount of the hydrophilic graft polymer required to obtain sufficient cement dispersibility. As a result, they thought that the molecular weight of the hydrophilic graft polymer should be increased. However,
Even if an acrylic acid alone is used as an unsaturated carboxylic acid monomer as in the examples disclosed in the above-mentioned European Patent Publication, and an attempt is made to produce a hydrophilic graft polymer having a high molecular weight, the viscosity is not increased. This is because, when an unsaturated carboxylic acid monomer having a very high polymerization rate such as acrylic acid is used, the unsaturated carboxylic acid monomer is grafted to a different bonding point of the polyether main chain. The graft chain elongation reaction, in which the unsaturated carboxylic acid monomer is successively polymerized on the same graft chain (side chain) once formed and the graft chain becomes longer, proceeds preferentially. It is presumed that only a small number of hydrophilic graft polymers having a long graft chain are formed. Therefore, when an α, β-unsaturated dicarboxylic acid such as maleic acid having a lower polymerization rate than acrylic acid is added as an unsaturated carboxylic acid-based monomer, the graft chain elongation reaction is suppressed, and the unsaturated carboxylic acid The reaction in which the system monomer was grafted to different bonding points of the polyether main chain occurred preferentially, and a hydrophilic graft polymer having a large number of graft chains and a short graft chain was formed.
As a result, a product having a high molecular weight without thickening was successfully produced.

Further, (1) Among the above-mentioned hydrophilic graft polymers obtained using α, β-unsaturated dicarboxylic acids, the use of a hydrophilic graft polymer having a weight average molecular weight of at least the following specified value is small. (2) In the hydrophilic graft polymer of (1) above, a polyether compound having a weight average molecular weight of at least the following specified value is used as an unsaturated carboxylic acid. When a hydrophilic graft polymer obtained by graft-polymerizing a polyether compound with a polyether compound in the following specific range is used, not only a small amount of addition but also a high cement dispersibility but also an appropriate AE The present invention was completed by confirming through experiments that the properties were also obtained.

That is, the first cement additive of the present invention is an ethylenically unsaturated additive containing, as an essential component, an unsaturated carboxylic acid monomer essentially comprising an α, β-unsaturated dicarboxylic acid and / or an anhydride thereof. A hydrophilic graft polymer having a weight average molecular weight of 6,000 or more obtained by graft-polymerizing a saturated monomer to a polyether compound is contained as an essential component. The second cement additive of the present invention comprises an ethylenically unsaturated monomer containing an unsaturated carboxylic acid monomer having α, β-unsaturated dicarboxylic acid and / or an anhydride thereof as an essential component. , To a polyether compound having a weight average molecular weight of 6,000 or more,
The unsaturated carboxylic acid-based monomer in the ethylenically unsaturated monomer is used in an amount of 0.1 to 4 with respect to the polyether compound.
A hydrophilic graft polymer having a weight average molecular weight of 6,000 or more obtained by graft polymerization at a usage amount of 5% by weight is contained as an essential component.

The first method for producing a hydrophilic graft polymer for a cement additive according to the present invention comprises the steps of: preparing an unsaturated carboxylic acid monomer essentially comprising an α, β-unsaturated dicarboxylic acid and / or an anhydride thereof; A step of obtaining a hydrophilic graft polymer having a weight average molecular weight of 6,000 or more by graft-polymerizing an ethylenically unsaturated monomer contained as an essential component to a polyether compound.

The second method for producing a hydrophilic graft polymer for a cement additive according to the present invention comprises the steps of preparing an unsaturated carboxylic acid monomer essentially comprising an α, β-unsaturated dicarboxylic acid and / or an anhydride thereof. The ethylenically unsaturated monomer containing as an essential component is converted to a polyether compound having a weight average molecular weight of 6,000 or more, and the unsaturated carboxylic acid-based monomer in the ethylenically unsaturated monomer is converted to the polyether compound. 0.1 for
A step of obtaining a hydrophilic graft polymer having a weight-average molecular weight of 6,000 or more by graft polymerization at a usage amount of up to 45% by weight.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the following, first, a polyether compound and an ethylenically unsaturated monomer will be described, and then a hydrophilic graft polymer and a method for producing the same will be described.
The cement additive and the configuration of the entire cement composition using the same will be described. [Polyether compound] The polyether compound is used as a raw material for obtaining a hydrophilic graft polymer used as an essential component of the cement additive of the present invention.

The polyether compound is a repeating unit represented by the following general formula (1) as a structural unit for improving the graft ratio of the obtained hydrophilic graft polymer, improving the cement dispersing performance, improving the hydrophilicity, and the like. Units (ie, ethylene oxide units and / or propylene oxide units) are preferably 4 units, based on the total polyether compound.
It has 0 mol% or more, more preferably 60 mol% or more, and still more preferably 80 mol% or more.

—RCH—CH ₂ —O— (1) (where R is at least one member selected from the group consisting of a hydrogen atom and a methyl group, and may be present in one molecule.) The compound is not particularly limited. For example, an alkylene oxide (preferably ethylene oxide and / or propylene oxide, and other alkylene oxides copolymerizable therewith if necessary) can be prepared by using water, amines, It can be obtained by performing polymerization by a known method using at least one selected from the group consisting of alcohols and phenols as a starting point. The alcohols for obtaining the polyether compound are not particularly limited, but include, for example, primary alcohols having 1 to 22 carbon atoms such as methanol, ethanol, n-propanol, and n-butanol; iso-propyl alcohol, a secondary alcohol having 3 to 18 carbon atoms such as an alcohol obtained by oxidizing n-paraffin; ter
tertiary alcohols such as t-butanol; diols such as ethylene glycol, diethylene glycol, propanediol, butanediol, and propylene glycol; triols such as glycerin and trimethylolpropane; and polyols such as sorbitol.
Only one species or two or more species can be used. The phenols for obtaining the polyether compound are not particularly limited, but include, for example, phenol, cresol, bisphenol A, salicylic acid, trimethylolphenol,
Resol, novolak and the like can be mentioned, and these can be used alone or in combination of two or more. The amines for obtaining the polyether compound are not particularly limited, but include, for example, aniline, naphthylamine, ethylenediamine and the like, and one or more of these can be used.

Other alkylene oxides copolymerizable with ethylene oxide and propylene oxide are not particularly limited, but include, for example, butylene oxide, styrene oxide, tetrahydrofuran and the like. Is done. However, since these other copolymerizable alkylene oxides have extremely low hydrophilicity, the amount is preferably less than 60 mol%, more preferably less than 40 mol%, and still more preferably less than 20 mol%, based on the whole polyether compound. . When the proportion of the other alkylene oxide structural unit exceeds 60 mol%, the viscosity becomes high and it becomes difficult to handle, and the hydrophilicity is reduced and the cement dispersibility may be reduced.

In order for the hydrophilic graft polymer used in the present invention to exhibit higher cement dispersing performance, the higher the hydrophilicity of the raw material polyether compound, the better. In order to further increase the hydrophilicity of the polyether compound, it is most preferable that the repeating unit of the polyether compound consists of only ethylene oxide. further,
Examples of polyether compounds also include derivatives derived from the polyether obtained as described above.
Such a derivative is not particularly limited, and examples thereof include a terminal group converter obtained by converting a terminal functional group of a polyether, and a polyether and a group such as a carboxyl group, an isocyanate group, an amino group, and a halogen group. And a cross-linked product obtained by reacting with a cross-linking agent having two or more in one molecule. Although the terminal group converter is not particularly limited, for example, hydroxyl groups at all or some of the terminals of the polyether may be replaced with (1) a C2 to C2 hydroxyl group.
22 fatty acids, succinic acid, succinic anhydride, maleic acid,
Examples thereof include those esterified with a dicarboxylic acid (anhydride) such as maleic anhydride and adipic acid, and those (2) alkoxylated by a dehydrohalogenation reaction using an alkyl halide (that is, alkoxypolyalkylene glycol). Can be

The weight average molecular weight of the polyether compound is
Although not particularly limited, the resulting hydrophilic graft polymer expresses a high cement dispersing performance by steric repulsion of the polyether portion, and, in order to exhibit an appropriate AE property, preferably 6,000 or more, More preferably 1
It is 0000 or more, more preferably 20,000 or more. [Ethylenically unsaturated monomer] The ethylenically unsaturated monomer to be graft-polymerized to the polyether compound is used to improve the dispersibility of the cement by improving the adsorptivity of the resulting hydrophilic graft polymer to cement. Therefore, an unsaturated carboxylic acid monomer is contained as an essential component.

The unsaturated carboxylic acid monomer must contain an α, β-unsaturated dicarboxylic acid and / or an anhydride thereof in order to prevent the viscosity from increasing by graft polymerization to the polyether compound at an appropriate rate. I do. The α, β-unsaturated dicarboxylic acid is not particularly limited, but includes, for example, maleic acid, fumaric acid, mesaconic acid, citraconic acid, and the like, and one or more of these may be used. The anhydride of the α, β-unsaturated dicarboxylic acid is not particularly limited, but includes, for example, maleic anhydride, citraconic anhydride, and the like, and one or more of these may be used. Among the α, β-unsaturated dicarboxylic acids and / or their anhydrides, at least one selected from the group consisting of maleic acid, fumaric acid and maleic anhydride is preferred because it is easily available.

As unsaturated carboxylic acid monomers, α,
A β-unsaturated dicarboxylic acid and / or an anhydride thereof is always used, but if necessary, another unsaturated carboxylic acid monomer is used in combination with an α, β-unsaturated dicarboxylic acid and / or an anhydride thereof. You may. Other unsaturated carboxylic acid monomers that can be used in combination are not particularly limited,
For example, (meth) acrylic acid, crotonic acid, (anhydrous)
Itaconic acid and the like can be mentioned, and these can be used alone or in combination.

The proportion of the α, β-unsaturated dicarboxylic acid and / or its anhydride relative to the total amount of the unsaturated carboxylic acid monomer used is not particularly limited, but the proportion of the polyether compound at an appropriate rate. In order to prevent thickening by graft polymerization, preferably 0.1 to 99.9% by weight, more preferably 1 to 99% by weight, further preferably 10 to 90% by weight, and still more preferably 20 to 80% by weight. % By weight.

In order to further improve the dispersibility of cement, etc., the unsaturated carboxylic acid monomer may be replaced with (meth) acrylic acid,
It is preferable that at least one selected from the group consisting of maleic acid, fumaric acid and maleic anhydride is contained as an essential component, and the unsaturated carboxylic acid monomer is maleic acid,
More preferably, at least one selected from the group consisting of fumaric acid and maleic anhydride and (meth) acrylic acid are contained as essential components, and the unsaturated carboxylic acid-based monomer is preferably a maleic acid or a maleic anhydride. More preferably, at least one of them and acrylic acid are contained as essential components.

As the ethylenically unsaturated monomer to be graft-polymerized to the polyether compound, an unsaturated carboxylic acid monomer is always used, but if necessary, the unsaturated carboxylic acid monomer may be used together with the unsaturated carboxylic acid monomer. Other polymerizable ethylenically unsaturated monomers can also be used. The other ethylenically unsaturated monomer copolymerizable with the unsaturated carboxylic acid monomer is not particularly limited as long as it is an ethylenically unsaturated monomer other than the unsaturated carboxylic acid monomer. Are, for example, ethylenically unsaturated carboxylic acid esters (eg, alkyl esters of maleic acid such as monomethyl maleate, dimethyl maleate, monoethyl maleate, diethyl maleate, etc .; monomethyl fumarate, dimethyl fumarate, monoethyl fumarate) And alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and stearyl (meth) acrylate; hydroxyethyl (meth) acrylate , Hydroxypropyl (meth) acrylate Unsaturated carboxylic acid esters having a hydroxyl group such as hydroxyalkyl (meth) acrylate; (methoxy) polyethylene glycol (meth) acrylate,
Polyalkylene glycol (meth) acrylates such as phenoxy polyethylene glycol (meth) acrylate, naphthoxy polyethylene glycol (meth) acrylate, monophenoxy polyethylene glycol maleate and carbazole polyethylene glycol (meth) acrylate; and aromatic vinyl such as styrene Amide group-containing vinyl monomers such as (meth) acrylamide and (meth) acrylalkylamide; vinyls such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate and vinyl cinnamate Esters; alkenes such as ethylene and propylene; dienes such as butadiene and isoprene; vinyl monomers containing a trialkyloxysilyl group such as vinyltrimethoxysilane and vinyltriethoxysilane; (Methacryloyloxypropyl) silicon-containing vinyl monomers such as trimethoxysilane; maleimides such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, and cyclohexylmaleimide Derivatives; vinyl monomers containing nitrile groups such as (meth) acrylonitrile; vinyl monomers containing aldehyde groups such as (meth) acrolein; dialkylaminoethyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate Group-containing vinyl monomers such as phenols; unsaturated ethers such as (methoxy) polyethylene glycol (meth) allyl ether and (methoxy) polyethylene glycol isopropenyl ether Le; 2
-Acrylamide-2-methylpropanesulfonic acid,
(Meth) allyl sulfonic acid, 2-sulfoethyl (meth)
Vinyl monomers containing a sulfonic acid group such as acrylate, vinylsulfonic acid, hydroxyallyloxypropanesulfonic acid, 2-hydroxy-3-butenesulfonic acid, and styrenesulfonic acid; vinyl chloride, vinylidene chloride, allyl chloride, allyl alcohol And the like, and other functional group-containing vinyl monomers, and the like, and these may be used alone or in combination of two or more. It is preferable that the ethylenically unsaturated monomer other than the unsaturated carboxylic acid-based monomer is at least one selected from alkyl (meth) acrylates for improving the slump holding performance.

The proportion of the unsaturated carboxylic acid monomer in the ethylenically unsaturated monomer is not particularly limited. However, in order to improve the cement dispersibility, the total amount of the ethylenically unsaturated monomer is reduced. On the other hand, it is preferably at least 60% by weight, more preferably at least 80% by weight, most preferably 100% by weight. Unsaturated carboxylic acid monomers and other ethylenically unsaturated monomers can be used as they are, but when they have an acid group, an acid ester group or an amine group, part or all of them are alkaline. It can be used after being converted into a salt by a substance or an acidic substance. (Hydrophilic graft polymer) The hydrophilic graft polymer used as an essential component of the cement additive of the present invention is a component that enhances cement dispersibility, and is obtained by graft-polymerizing an ethylenically unsaturated monomer to a polyether compound. It is a polymer obtained by. The hydrophilic graft polymer is composed of a polyether portion derived from a polyether compound, and a graft chain portion in which an ethylenically unsaturated monomer is graft-polymerized on the polyether portion.

The weight-average molecular weight of the hydrophilic graft polymer is preferably large in order to obtain high cement dispersing performance with a small amount of addition. Specifically, usually 6,000
Or more, preferably 7,000 or more, more preferably 1
It is at least 000, more preferably at least 15,000. (Method for producing hydrophilic graft polymer) The method for producing the hydrophilic graft polymer used in the present invention is not particularly limited as long as it is a method for graft-polymerizing an ethylenically unsaturated monomer to a polyether compound. However, from the viewpoint of increasing the graft ratio and improving the cement dispersing ability, for example, a method in which an ethylenically unsaturated monomer is graft-polymerized to a polyether compound in the presence of a polymerization initiator is preferable. The polymerization initiator is not particularly limited, and a known radical initiator can be used. In particular, an organic peroxide is preferable in terms of reactivity and the like.

The organic peroxide is not particularly restricted but includes, for example, methyl ethyl ketone peroxide,
Ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide, acetylacetone peroxide; tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene Hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,
Hydroperoxides such as 1,3,3-tetramethylbutyl hydroperoxide and 2- (4-methylcyclohexyl) -propane hydroperoxide; di-tert-butyl peroxide, tert-butylcumyl peroxide, dicumyl Peroxide, α,
α′-bis (tert-butylperoxy) p-diisopropylbenzene, α, α′-bis (tert-butylperoxy) p-isopropylhexyne, 2,5-dimethyl-2,5-di (tert-butyl) Dialkyl peroxides such as peroxy) hexane and 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3; tert-butylperoxyacetate, te
rt-butylperoxylaurate, tert-butylperoxybenzoate, di-tert-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxyisopropyl carbonate Tert-butyl peroxyisobutyrate, tert-butyl peroxybivalate, tert-butyl peroxy neodecanoate, cumyl peroxy neodecanoate, ter
t-butylperoxy-2-ethylexanoate, t
tert-butylperoxy-3,5,5-trimethylcyclohexanoate, tert-butylperoxybenzoate, tert-butylperoxymaleic acid, cumylperoxyoctoate, tert-hexylperoxybivalate, tert-hexylper Peroxyesters such as oxyneohexanoate and cumylperoxyneohexanoate; n-butyl-4,4-bis (tert-butylperoxy) valeate, 2,2-
Bis (tert-butylperoxy) butane, 1,1-
Bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, 2,2-bis (te
peroxy ketals such as rt-butylperoxy) octane; acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,3,5
-Trimethylcyclohexanoyl peroxide, succinic acid peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide,
diacyl peroxides such as m-toluyl peroxide; di-isopropyl peroxy dicarbonate, di-2-ethylhexyl peroxy dicarbonate, di-
n-propylperoxydicarbonate, bis- (4-
tert-butylcyclohexyl) peroxydicarbonate, dimyristyl peroxydicarbonate, di-
Peroxydicarbonates such as methoxyisopropylperoxydicarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, di-allylperoxydicarbonate; acetylcyclohexylsulfonyl peroxide, tert-butylperoxyallyl Other organic peroxides such as carbonate can be used, and one or more of these are used.

The organic peroxide may be used together with a decomposition catalyst for the organic peroxide or a reducing compound. The amount of the polymerization initiator is not particularly limited, but is preferably 0.1 to 15% by weight, more preferably 0.5 to 10% by weight, based on the ethylenically unsaturated monomer. If the amount is less or more than this, the graft ratio to the polyether compound is reduced. The polymerization initiator may be added to the polyether compound in advance, but may be added to the ethylenically unsaturated monomer or added to the reaction system simultaneously with the ethylenically unsaturated monomer. You can also.

The polymerization method is not particularly limited, and for example, a known polymerization method such as solution polymerization or bulk polymerization using a polymerization initiator can be employed. The solvent used when performing the solution polymerization is not particularly limited, but a solvent that does not adversely affect the polymerization efficiency is preferable. Such a solvent is not particularly limited, for example, water; n-
Hydrocarbons such as butane, propane, benzene, cyclohexane and naphthalene; halogenated hydrocarbons such as methyl chloride, chloroform, carbon tetrachloride and trichloroethane;
Propanol, butanol, isopropyl alcohol,
Alcohols such as isobutyl alcohol and isoamyl alcohol; ethers such as ethyl ether, isopropyl ether and butyl ether; ketones such as methyl ethyl ketone, ethyl butyl ketone and methyl isobutyl ketone; methyl acetate, ethyl acetate, ethyl benzoate and ethyl lactate; Ester type; acid type such as formic acid, acetic acid and propionic acid; polyhydric alcohol such as (poly) ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, tetraethylene glycol and propylene glycol monobutyl ether, and derivatives thereof. And one or more of these can be used.

The polymerization method can be carried out batchwise or continuously. The temperature of the graft polymerization is preferably 80 ° C or higher, more preferably 100 ° C or higher and 160 ° C or lower. When the temperature is lower than 80 ° C., the graft polymerization does not easily proceed, and the grafting efficiency of the ethylenically unsaturated monomer to the polyether compound may decrease. On the other hand, 160 ° C
At a higher temperature, thermal decomposition of the raw material polyether compound and the obtained hydrophilic graft polymer may occur.

At the time of graft polymerization, it is preferable to initially or partially charge the polyether compound. Further, as an ethylenically unsaturated monomer, at least one monomer selected from the group consisting of maleic acid, fumaric acid and maleic anhydride, and (meth) acrylic acid are used in combination to form a polyether compound. In the case of graft polymerization, at least half of maleic acid, fumaric acid, and maleic anhydride are mixed in advance with a polyether compound, and these are heated to a pour point (temperature) or higher of the polyether compound.
It is preferable that the remaining ethylenically unsaturated monomer and the polymerization initiator are separately added to the obtained mixture to carry out graft polymerization. According to this method, the rate of introduction of maleic acid, fumaric acid, and maleic anhydride into the hydrophilic graft polymer can be significantly improved.

The amount of the ethylenically unsaturated monomer used for graft-polymerizing the ethylenically unsaturated monomer to the polyether compound is not particularly limited, but is included in the ethylenically unsaturated monomer. The unsaturated carboxylic acid monomer is preferably used in an amount of 0.1 to 4 based on the polyether compound.
The amount is 5% by weight, more preferably 1 to 40% by weight, still more preferably 2 to 35% by weight. The above amount is 0.1
When the amount is less than 10% by weight, the obtained hydrophilic graft polymer tends to be hardly adsorbed to the cement, so that the cement dispersing ability tends to be reduced, or an appropriate AE property tends to be not obtained.
If the content exceeds 45% by weight, the resulting hydrophilic graft polymer tends to have low cement dispersing ability, fail to obtain an appropriate AE property, and have a tendency that the viscosity of the reaction mixture becomes high, making it difficult to handle.

The hydrophilic graft polymer obtained by the above-mentioned production method may be used as a cement additive as it is, or a solution dissolved in a solvent such as water or alcohol may be used as a cement additive. . When the hydrophilic graft polymer has an acid group such as a carboxyl group or a sulfonic acid group or an ester group thereof, a substance obtained by adding a base to convert the acid group or the ester group into a salt is used as a cement additive. You may. The base is not particularly limited, but includes, for example, sodium hydroxide, potassium hydroxide,
Alkali metals such as calcium hydroxide and lithium hydroxide,
Hydroxides of alkaline earth metals; alkali metals such as sodium carbonate, calcium carbonate and lithium carbonate, carbonates of alkaline earth metals; ammonia, monoethanolamine,
Examples thereof include amines such as diethanolamine and triethanolamine, and one or more of these are used. Further, water is preferable as the solvent.

The method for producing the hydrophilic graft polymer is not limited to the above method.
Known methods described in JP-A-53-645, JP-A-8-208767, JP-A-8-208770 and the like may be used. [Cement additive] The cement additive of the present invention contains the hydrophilic graft polymer as an essential component, and further contains the above-mentioned solvent and other components described below as necessary. The concentration of the hydrophilic graft polymer in the cement additive is not particularly limited.

The cement additive of the present invention may optionally contain
Known additives may be further included. Such additives are not particularly limited, but include, for example, water reducing agents, AE water reducing agents, superplasticizers, high performance water reducing agents, high performance AEs.
Water reducer, thickener, defoamer, shrinkage reducer, swelling agent, rust inhibitor, strength enhancer, fungicide, cement dispersant, AE (air entraining) agent, cement wetting agent, water soluble polymer , A waterproofing agent, a curing retarder, a curing accelerator, a quick-setting agent, a flocculant and the like. These may use only one kind,
Two or more types may be used as a mixture. The mixing ratio is not particularly limited.

The cement additive of the present invention is widely used, for example, in conventionally known concrete methods. Such a construction method is not particularly limited, for example,
High-strength concrete method, ultra-high-strength concrete method,
High fluidity concrete method, flowing concrete method and the like can be mentioned. The use form of the cement additive of the present invention is not particularly limited. For example, it may be used as it is in a solid or powder form, or may be mixed with water and used in the form of an aqueous solution or an aqueous dispersion. be able to.

Among the cement additives of the present invention, the addition amount required to obtain a mortar flow value of 110 mm and an air entrainment amount of 11 ± 2 vol% by the following evaluation method is calculated based on the solid content of the hydrophilic graft polymer with respect to the cement. Those having a content of 0.5% by weight or less are preferred in terms of economy. (Evaluation method): After 400 parts by weight of ordinary Portland cement and 800 parts by weight of standard sand from Toyoura were kneaded with a Hobart mortar mixer (model number N-50, manufactured by Tesco Corporation) for 30 seconds, the cement additive was added. The mortar is obtained by adding 240 parts by weight of water and kneading for 3 minutes.

The obtained mortar is filled into a hollow cylinder placed on a horizontal table and having an inner diameter and a height of 55 mm until it is worn out. This cylinder is gently lifted vertically, and then the mortar spread on the table is removed. The minor axis is measured, and the average value is defined as the mortar flow value. When evaluating the cement composition having a small entrained air amount, the entrained air amount of the mortar is adjusted to about 11% using an AE (air entraining) agent. The amount of air is calculated from the volume and weight of the obtained mortar and the specific gravity of the material used. [Cement composition] As the cement composition to which the cement additive of the present invention is blended, a conventionally known cement composition can be used and is not particularly limited. For example, a cement water paste containing cement and water (a cement water slurry) is used. ); Mortar containing cement, water, and sand; concrete containing cement, water, sand, and stone;

As the cement to be added to the cement composition, conventionally known cements can be used and are not particularly limited. For example, portland cements such as ordinary portland cement and early-strength portland cement, silica cement, fly ash cement , Blast furnace cement, alumina cement, belite-rich cement, various mixed cements and the like. Among them, Portland cement is preferable because it is often used. In addition, only one type of cement may be used, or two or more types may be used in appropriate combination.

The mixing ratio of the cement additive in the cement composition is not particularly limited. For example, the content of the hydrophilic graft polymer, which is an essential component of the cement additive, based on the solid content of cement is preferably 0.0001 to 0.0001.
It is 10% by weight, more preferably 0.001 to 5% by weight, further preferably 0.005 to 3% by weight, and most preferably 0.01 to 1% by weight. If the compounding ratio of the cement additive is less than 0.0001% by weight, the effect of improving the cement dispersibility may be small, and if it exceeds 10% by weight,
The setting delay of the cement composition may easily occur.

The mixing ratio of water in the cement composition is as follows:
Although not particularly limited, for example, for cement,
Preferably 10 to 80% by weight, more preferably 15 to 7% by weight.
It is 5% by weight, more preferably 20-70% by weight, most preferably 25-65% by weight. Water mixing ratio is 10
When the amount is less than the weight percentage, various components may be insufficiently mixed and molding may not be performed, or strength may be reduced. On the other hand, if it exceeds 80% by weight, the strength of the cured product of the cement composition may decrease.

When the cement composition is used as mortar or concrete, the sand used in the cement composition can be any sand used in conventional cement compositions, and is not particularly limited. Natural fine aggregate such as river sand, sea sand, mountain sand, etc.
Artificial fine aggregates obtained by crushing these rocks and slabs; lightweight fine aggregates; The amount of the sand may be the same as that of the conventional cement composition, and is not particularly limited.

When the cement composition is used as concrete, stones to be mixed with the cement composition can be those used in conventional cement compositions, and are not particularly limited. Natural coarse aggregate such as river sand, sea sand, mountain sand, etc .; artificial coarse aggregate obtained by pulverizing these rocks and slabs; lightweight coarse aggregate; The compounding amount of the stone may be the same as that of the conventional cement composition, and is not particularly limited. For example, the fine aggregate ratio is preferably 20 to 60%, and more preferably 30 to 50%. If the fine aggregate ratio is less than 20%, the concrete becomes loose, and in the case of concrete having a large slump, the coarse aggregate and the mortar component may be easily separated. On the other hand, if it exceeds 60%, a large amount of unit cement and a large amount of water are required, and concrete with poor fluidity may be obtained.

Other materials may be added to the cement composition as required. As other materials, those similar to the conventional cement composition can be used, and are not particularly limited. For example, silica fume, blast furnace slab, silica powder, steel fiber, fiber material such as glass fiber, and the like can be used. No. The compounding amount of these materials is
There is no particular limitation, and it may be the same as a conventional cement composition.

The method for producing the cement composition containing the cement additive of the present invention is not particularly limited, but may be the same as that of the conventional cement composition, for example, cement and water, and if necessary, other compounds. A method of blending and mixing together the cement additive of the present invention, its aqueous dispersion or aqueous solution when mixing the materials; mixing cement and water with other blended materials as necessary, and obtaining the mixture. Adding and mixing the cement additive of the present invention, an aqueous dispersion or an aqueous solution thereof to the mixture obtained; mixing the cement and other compounding materials in advance as necessary, and adding the cement additive of the present invention to the obtained mixture. A method of adding and mixing an aqueous dispersion or aqueous solution thereof with water; cement, a cement additive of the present invention, an aqueous dispersion or aqueous solution thereof, and other compounding materials as required. The previously mixed, and a method of mixing water is added to the mixture obtained.

When the cement additive of the present invention contains additives other than the hydrophilic graft polymer, the hydrophilic graft polymer and other additives can be added separately. When the cement additive of the present invention containing the hydrophilic graft polymer as an essential component is added to a cement composition,
In the molecular structure of the hydrophilic graft polymer contained in the cement additive, the graft chain portion derived from the ethylenically unsaturated monomer graft-polymerized to the polyether compound is adsorbed on the cement, and the polyether derived from the polyether compound Due to steric repulsion (electrostatic repulsion) and hydrophilicity of the part,
The dispersibility of the cement is improved. Therefore, high fluidity is given to the cement composition without causing a large hardening delay due to the addition of the cement additive, and the working life thereof is prolonged, so that workability of the construction using the cement composition is remarkable. Be improved. Therefore, the cement additive of the present invention can be used, for example, as a fluidizer for concrete such as ready-mixed concrete. In particular, the production of ready-mixed concrete with a high water reduction ratio as a high-performance AE water reducing agent added simultaneously with a plant can be easily realized.

The cement additive of the present invention can also be used as a high-performance water reducing agent for the production of secondary concrete products, and can reduce water and increase strength.

[0048]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the present invention is not limited to the following Examples. In addition,
In the following examples, the weight average molecular weight was measured by GPC (gel permeation chromatography) using an LC Module 1p manufactured by Nippon Waters Co., Ltd. as a measurement model.
A calibration curve was prepared with standard polyethylene oxide using rus and measured as a converted value.

First, a cement additive was prepared by the following method. <Example 1> A glass reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser was charged with a weight average molecular weight of 13,00.
0 parts by weight of polyethylene glycol, 6.2 parts by weight of succinic anhydride, and 7.3 parts by weight of maleic acid were charged and melt-mixed by heating to 120 ° C. under a nitrogen stream.
Next, while maintaining the temperature at 128 ± 3 ° C.,
0.6 parts by weight, t-butyl peroxybenzoate
8 parts by weight separately and continuously dropped over 30 minutes,
Thereafter, stirring was continued for 1 hour. After cooling, 200 parts by weight of water was added, and an aqueous solution of sodium hydroxide (a 30% by weight solution) was further added so as to have a pH of 8, thereby obtaining a sodium salt aqueous solution of the hydrophilic graft polymer 1. This is called cement additive (1).

The weight average molecular weight (Mw) of the obtained hydrophilic graft polymer 1 was 17,400. <Example 2> 100 parts by weight of polyethylene glycol having a weight average molecular weight of 20,000, 2 parts by weight of succinic anhydride, and maleic anhydride in a reactor similar to that of Example 1.
Five parts by weight were charged and heated to 120 ° C. under a nitrogen stream to melt and mix. Next, while maintaining the temperature at 128 ± 3 ° C., 6 parts by weight of acrylic acid and 1 part by weight of t-butylperoxybenzoate were separately dropped continuously over 15 minutes, and thereafter, stirring was continued for 45 minutes. After cooling, water 480
By weight, an aqueous solution of sodium hydroxide (30% by weight solution) was further added in such an amount as to give a pH of 8, whereby an aqueous solution of a sodium salt of the hydrophilic graft polymer 2 was obtained. This is called cement additive (2).

The weight average molecular weight (Mw) of the obtained hydrophilic graft polymer 2 was 32,500. Example 3 In the same reactor as in Example 1, methoxypolyethylene glycol 100 having a weight average molecular weight of 5,000 was added.
Parts by weight and 23.8 parts by weight of maleic anhydride were charged and melt-mixed by heating to 120 ° C. under a nitrogen stream.
Next, while maintaining the temperature at 128 ± 3 ° C.,
6.2 parts by weight and 5 parts by weight of t-butyl peroxybenzoate were separately dropped continuously over 15 minutes, and then stirring was continued for 45 minutes. After cooling, 600 parts by weight of water were added, and an aqueous sodium hydroxide solution (30% by weight solution) was further added.
Was added in such an amount as to give a pH of 8, whereby a sodium salt aqueous solution of the hydrophilic graft polymer 3 was obtained. This is called cement additive (3).

The weight average molecular weight (Mw) of the obtained hydrophilic graft polymer 3 was 57,100. Example 4 In the same reactor as in Example 1, 100 parts by weight of polyethylene glycol having a weight average molecular weight of 13,000, 3.1 parts by weight of succinic anhydride and 2 parts of maleic anhydride were added.
3.8 parts by weight were charged and heated to 120 ° C. under a nitrogen stream to be melt-mixed. Next, while maintaining the temperature at 128 ± 3 ° C., 26.2 parts by weight of acrylic acid and 5 parts by weight of t-butylperoxybenzoate were separately dropped continuously over 15 minutes, and thereafter, stirring was continued for 45 minutes. After cooling, 600 parts by weight of water was added, and an aqueous solution of sodium hydroxide (30% by weight solution) was further added to adjust the pH to 8, thereby obtaining an aqueous sodium salt solution of the hydrophilic graft polymer 4. This is called cement additive (4).

The weight average molecular weight (Mw) of the obtained hydrophilic graft polymer 4 was 50,900. <Example 5> 252.1 parts by weight of polyethylene glycol having a weight average molecular weight of 1,100 and 20.9 parts by weight of maleic acid were charged into the same reactor as in Example 1, and heated to 120 ° C under a nitrogen stream. And melt mixed. Next, while maintaining the temperature at 128 ± 3 ° C., 59 parts by weight of acrylic acid,
3.8 parts by weight of di-t-butyl peroxide are separately added to 15 parts by weight.
The mixture was added dropwise continuously over a period of minutes, and then stirring was continued for 45 minutes. After cooling, 1300 parts by weight of water was added, and an aqueous solution of sodium hydroxide (30% by weight solution) was further added in such an amount as to have a pH of 8, whereby an aqueous solution of a sodium salt of the hydrophilic graft polymer 5 was obtained. This is called cement additive (5).

The weight average molecular weight (Mw) of the obtained hydrophilic graft polymer 5 was 6,700. Comparative Example 1 100 parts by weight of methoxypolyethylene glycol having a weight average molecular weight of 250 and 43.8 parts by weight of maleic anhydride were charged into the same reactor as in Example 1, and heated to 120 ° C. under a nitrogen stream to melt. Mixed. next,
While keeping the temperature at 128 ± 3 ° C.,
Parts by weight and 4.6 parts by weight of t-butyl peroxybenzoate were continuously dropped separately over 15 minutes, and then stirring was continued for 45 minutes. After cooling, 770 parts by weight of water was added, and an aqueous sodium hydroxide solution (30% by weight solution) was further added.
Was added in such an amount as to give a pH of 8, whereby a sodium salt aqueous solution of the comparative hydrophilic graft polymer 1 was obtained. This is referred to as comparative cement additive (1).

The weight average molecular weight (Mw) of the obtained comparative hydrophilic graft polymer 1 was 3,960. Table 1 shows the preparation conditions and preparation results of the hydrophilic graft polymer. Comparative Example 2 A commercially available polyethylene glycol having a weight average molecular weight of 20,000 (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used as a comparative cement additive (2). <Comparative Example 3> A commercially available sodium polyacrylate having a weight average molecular weight of 5,000 (DL-40S manufactured by Nippon Shokubai Co., Ltd.) was used as a comparative cement additive (3). <Comparative Example 4> Commercially available Kao Corporation water reducer Mighty 15
0 (naphthalene-based water reducing agent) was used as a comparative cement additive (4). Comparative Example 5 The same reactor as in Example 1 was charged with 70 parts by weight of polyethylene glycol having a weight average molecular weight of 7,500, and heated and melted and mixed at 120 ° C. under a nitrogen stream. Next, while maintaining the temperature at 150 ± 3 ° C., 30 parts by weight of acrylic acid and 0.6 part by weight of di-t-butyl peroxide were separately dropped continuously over 60 minutes.

The reactant started to increase its viscosity rapidly about 55 minutes after the start of the dropping of acrylic acid and the initiator, and rolled up along the stirring blade. For this reason, continuation of stirring became impossible, and the intended aging for one hour could not be completed (thus, the reaction product had an intense monomer odor). The cement additive obtained as described above was subjected to a mortar flow test described below to evaluate the cement dispersibility. (Mortar flow test): 400 parts by weight of ordinary Portland cement manufactured by Chichibu Onoda Cement Co., Ltd. and 800 parts by weight of standard sand produced by Toyoura are emptied with a Hobart type mortar mixer (model number N-50, manufactured by Tesco Corporation) for 30 seconds. After kneading,
A predetermined amount of the cement additive shown in Table 2 was weighed and diluted with water, and 240 parts by weight were added (for the reason described later, a predetermined amount of an AE (air entraining) agent (mount (Trade name of “Vinsol” of Souka Co., Ltd.) was also added.)
The mortar was obtained by kneading for minutes.

The obtained mortar was filled into a hollow cylinder placed on a horizontal table and having both an inner diameter and a height of 55 mm until it was worn out. This cylinder was gently lifted vertically, and then the mortar spread on the table was removed. The minor axis was measured, and the average value was taken as the mortar flow value. The larger this value is, the better the cement dispersibility (water reduction) is. It should be noted that the flow value becomes apparently large when the entrained air amount is large, so that it is necessary to measure the flow value with the entrained air amount being constant. Therefore, when evaluating the cement composition having a small amount of entrained air, the entrained air amount of the mortar was adjusted to about 11% using an AE (air entraining) agent (trade name “VINSOL” of Yamamune Chemical Co., Ltd.). . The amount of air was calculated from the volume and weight of the obtained mortar and the specific gravity of the material used.

The results are shown in Table 2 and FIG.

[0059]

[Table 1]

[0060]

[Table 2]

The following can be seen from Tables 1 and 2 and FIG. A polyether compound having a weight average molecular weight of 6,000 or more is graft-polymerized with an unsaturated carboxylic acid monomer in an amount of 1 to 45% by weight based on the polyether compound, and has a weight average molecular weight of 6,000 or more. The cement additives (1) and (2) of Examples 1 and 2 containing a hydrophilic graft polymer having a molecular weight were compared with any of the comparative cement additives (1) to (4) of Comparative Examples 1 to 4. However, high cement dispersibility is obtained with a small amount of addition, and air entrainment (AE property) is small. It is easy to adjust the entrained air amount of the cement composition such as mortar to the set value in the direction of increasing by using the AE agent, but it is difficult to adjust to the set value in the direction of decreasing by the use of the defoaming agent. For this reason, a water reducing agent having a small AE property is prepared in advance by using a certain amount or an excessive amount of an antifoaming agent, and the amount of A is determined according to the aggregate and the composition in various parts of the country.
It is common practice to adjust the entrained air volume with the E agent. An agent having a small AE property can be said to be an easy-to-use agent because it is not necessary to previously reduce the AE property with an antifoaming agent.

The cement additives (3) to (5) of Examples 3 to 5 have a weight average molecular weight of 6 of the polyether compound as a raw material of the hydrophilic graft polymer contained therein.
The amount of the unsaturated carboxylic acid monomer, which is less than 1,000, or more than 45% by weight based on the polyether compound, which is another raw material of the hydrophilic graft polymer, Has a weight average molecular weight of 6,000 or more, so that even with any of the comparative cement additives (1) to (4) of Comparative Examples 1 to 4, high cement dispersibility is obtained with a small amount of addition. In addition, the ultimate water reduction rate is large.

On the other hand, in the comparative cement additive (1) of Comparative Example 1, the weight average molecular weight of the polyether compound as a raw material of the hydrophilic graft polymer contained therein was less than 6,000, and Since the amount of the unsaturated carboxylic acid monomer used exceeds 45% by weight and the weight average molecular weight of the hydrophilic graft polymer is less than 6,000,
Even when the amount of addition was increased, the flow value reached a plateau (the attained water reduction rate was small). Forcibly increasing the amount of addition causes material separation (non-uniformity (localization) of water, cement, and aggregate).

Comparative Example 2 Made of Polyethylene Glycol
The comparative cement additive (3) of Comparative Example 3 comprising sodium polyacrylate and the comparative cement additive (3)
In all cases, the cement dispersibility is low despite the large amount of addition. The comparative cement additive (4) of Comparative Example 4, which is composed of the commercially available water reducing agent Mighty 150, has a small AE (air entraining) property but a small water reduction rate.

In Comparative Example 5, since acrylic acid having a very high polymerization rate was used alone as the unsaturated carboxylic acid monomer, the viscosity increased, and a hydrophilic graft polymer could be produced successfully. Did not.

[0066]

The first cement additive of the present invention contains the above-mentioned specific hydrophilic graft polymer having high cement dispersibility as an essential component, so that it does not cause a large delay in hardening and has a high cement composition. Since the fluidity can be imparted and the pot life can be prolonged, the workability of the construction using the cement composition can be remarkably improved.

The second cement additive of the present invention contains, as an essential component, the above-mentioned specific hydrophilic graft polymer having not only a high cement dispersibility but also an appropriate air entrainment (AE property). In addition to having the above-mentioned effects due to the properties, the cement composition after curing has the strength and the resistance to freezing and thawing can be maintained by the moderate AE property.

The first and second cement additives of the present invention can exhibit the above-mentioned excellent performance with a small amount of addition, and are therefore highly economical. Further, the hydrophilic graft polymer used in these cement additives has an unsaturated carboxylic acid-based monomer, which is an essential component of the ethylenically unsaturated monomer as a raw material, containing α, β-unsaturated dicarboxylic acid and When acrylic acid is used alone as an unsaturated carboxylic acid-based monomer because the rate of graft polymerization of the α, β-unsaturated dicarboxylic acid and / or its anhydride is moderately low. It can be obtained easily and inexpensively without causing thickening as described above.

According to the first and second methods for producing hydrophilic graft polymers for cement additives of the present invention, the first and second hydrophilic graft polymers of the present invention exhibiting the above-mentioned excellent performance, respectively.
The hydrophilic graft polymer used for the cement additive can be easily and inexpensively obtained without increasing the viscosity.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the addition amount and the mortar flow value of the cement additives of Examples 1 to 5 and Comparative Examples 1 to 4 of the present invention. In this graph, the numerical values shown beside each plot indicate the air volume (v
ol%), and those in parentheses indicate the amount of AE agent added (wt.
%).

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08G 65/48 C08G 65/48 (C08F 283/01 220: 04) (C08F 283/01 222: 02) (C08F 283/06 220: 04) (C08F 283/06 222: 02) C04B 103: 40 (72) Inventor Eriko Maeda 5-8 Nishiburi-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd. (72) Inventor Takeshi Kenneda, Nishi-Moritacho, Suita-shi, Osaka No.5-8 Nippon Shokubai Co., Ltd.

Claims (9)

[Claims] 1. An ethylenically unsaturated monomer containing, as an essential component, an unsaturated carboxylic acid monomer essentially comprising an α, β-unsaturated dicarboxylic acid and / or an anhydride thereof is graft-polymerized to a polyether compound. A cement additive comprising a hydrophilic graft polymer having a weight average molecular weight of 6,000 or more as an essential component. 2. The hydrophilic graft polymer is obtained by adding the ethylenically unsaturated monomer to the polyether compound having a weight average molecular weight of 6,000 or more and the unsaturated carboxylic acid in the ethylenically unsaturated monomer. The cement additive according to claim 1, wherein the system monomer is a hydrophilic graft polymer obtained by graft polymerization in an amount of 0.1 to 45% by weight based on the polyether compound. 3. The unsaturated carboxylic acid-based monomer contains at least one selected from the group consisting of maleic acid, fumaric acid and maleic anhydride as an essential component.
Or the cement additive according to 2. 4. The unsaturated carboxylic acid monomer contains at least one selected from the group consisting of maleic acid, fumaric acid and maleic anhydride, and (meth) acrylic acid as essential components. Item 4. A cement additive according to item 3. 5. A mortar flow value of 110 according to the following evaluation method.
The amount of addition necessary for obtaining an air entrainment amount of 11 ± 2 vol% in mm and not more than 0.5% by weight in terms of solid content based on cement of the hydrophilic graft polymer.
The cement additive according to any one of the above. (Evaluation method): After 400 parts by weight of ordinary Portland cement and 800 parts by weight of standard sand from Toyoura were kneaded with a Hobart type mortar mixer (model number N-50, manufactured by Tesco Corporation) for 30 seconds, the cement additive was added. The mortar is obtained by adding 240 parts by weight of water and kneading for 3 minutes. The obtained mortar was filled into a hollow cylinder having an inner diameter and a height of 55 mm both placed on a horizontal table until the surface of the mortar, and the cylinder was gently lifted vertically, and then the length and width of the mortar spread on the table were reduced. The mortar flow value is measured and the average value is taken as the mortar flow value. When evaluating the cement composition having a small entrained air amount, the entrained air amount of the mortar is adjusted to about 11% using an AE (air entraining) agent. The amount of air is calculated from the volume and weight of the obtained mortar and the specific gravity of the material used. 6. An ethylenically unsaturated monomer containing, as an essential component, an unsaturated carboxylic acid monomer essentially comprising an α, β-unsaturated dicarboxylic acid and / or an anhydride thereof, is graft-polymerized to a polyether compound. To obtain a hydrophilic graft polymer having a weight average molecular weight of 6,000 or more by performing
A method for producing a hydrophilic graft polymer for a cement additive. 7. The polyether compound has a weight-average molecular weight of 6,000 or more, and the amount of the ethylenically unsaturated monomer used depends on the amount of the unsaturated carboxylic acid-based compound in the ethylenically unsaturated monomer. The method for producing a hydrophilic graft polymer for a cement additive according to claim 6, wherein a ratio of the monomer is 0.1 to 45% by weight based on the polyether compound. 8. The unsaturated carboxylic acid monomer contains at least one selected from the group consisting of maleic acid, fumaric acid and maleic anhydride as an essential component.
Or the method for producing a hydrophilic graft polymer for a cement additive according to item 7. 9. The unsaturated carboxylic acid monomer contains at least one selected from the group consisting of maleic acid, fumaric acid and maleic anhydride, and (meth) acrylic acid as essential components. Item 10. The method for producing a hydrophilic graft polymer for a cement additive according to Item 8.