WO1999062838A1

WO1999062838A1 - Cement admixture, cement compositions and cement structures

Info

Publication number: WO1999062838A1
Application number: PCT/JP1999/002435
Authority: WO
Inventors: Kyouichi Tanaka; Yasuhiko Fujita; Tutomu Saitou; Takeru Sakamoto
Original assignee: Fpk Co., Ltd.
Priority date: 1998-06-04
Filing date: 1999-05-11
Publication date: 1999-12-09

Abstract

A cement admixture which comprises, in terms of solid matter, 50 to 80 parts by weight of a lignosulfonate salt [I] and 20 to 50 parts by weight of a copolymer prepared from the monomer components: (a) 40 to 83 parts by weight of an α,β-unsaturated carboxylic acid and/or a salt thereof, (b) 10 to 30 parts by weight of a (meth)acrylate ester (except hydroxyalkyl (meth)acrylates) and (c) 7 to 50 parts by weight of a hydroxyalkyl (meth)acrylate [provided the sum total of the components (a), (b) and (c) is 100 parts by weight] and which is superior to the ones of the prior art in slump improving effect and slump loss inhibiting performance; and cement compositions and cement structures made by using the same.

Description

SPECIFICATIONS-Cement admixtures and compositions,

TECHNICAL FIELD The present invention relates to an admixture for a cement composition such as cement, mortar, and concrete, and to a cement composition comprising the same. A cement admixture that can enhance the flowability and flow retention (generally referred to as slanproth control) during the construction of cement, as well as increase the strength of the cement cured product. The present invention relates to a cement composition modified by the addition of the admixture, and further to a cement structure comprising a cured product having an increased strength. BACKGROUND ART Reforming admixtures are blended in cement for various purposes. In recent years, cement compositions with even higher performance have been developed to be able to cope sufficiently with the increase in the height of buildings and the durability life, etc., and also to cope with changes in aggregate conditions. There is a need for a reforming admixture.

This type of admixture ensures excellent water reduction in order to provide a stable air entrainment to the cement composition and increase the strength and durability life of the cured product. It is important to improve the fluidity and slan process suppression in order to enhance the stability during construction It is said to be performance, and the demands of consumers for those performances have become more severe recently. -The cement admixtures currently in practical use include lignin sulfonate, naphtholensulfonate / formalin condensate, and melamin sulfonate. Known are salt-formalin condensate, aminosulfonate, polycarbonate, etc., each of which has advantages and disadvantages and is satisfactory. No.

Under these circumstances, there has recently been an increasing expectation for polycarboxylic acid-based admixtures, which have high water-reducing properties and slanpros-suppressing properties. Attention has been paid to acryl-based or vinyl-based (co) polymers having a base or ether bond.

For example, JP-A-62-212252 discloses that a monomer having a sulfonic acid group and a monomer having a carboxylic acid group are used as hydrophilic structural units, and further a hydrophobic structural unit is used. It is described that when a specific amount of a hydrophobic monomer is used, the time-dependent change in dispersibility is suppressed, and the slanproth-inhibiting property of the cement composition is improved.

In Japanese Patent Application Laid-Open No. 5-213354, the use of an alkylenoxyside-added monomer and a carboxylic acid-based monomer is used to improve the flowability and the slanpros inhibitory property. A cement admixture is disclosed, which states that this cement admixture is useful not only for improving the workability of the cement composition, but also for improving the durability of the cement cement cured product. It has been done.

Further, Japanese Unexamined Patent Publication (Kokai) No. 59-162161 discloses hydroxyl groups such as monoesters of unsaturated monocarboxylic acid and glycol. A copolymer comprising a monomer having a carboxyl group and a monomer having a carboxyl group or a salt thereof does not delay the curing of cement and can be added in a small amount. It has been clarified that the fluidity during cement composition application can be increased.

Japanese Unexamined Patent Publication (Kokai) No. 63-166253 discloses a (meth) a of unsaturated carboxylic acid and / or its salt and an alkyl alcohol having 1 to 4 carbon atoms. A cement dispersant containing a copolymer with a acrylate or, if necessary, a copolymer obtained by copolymerizing another copolymerizable monomer as an essential component is used. It has been disclosed that this dispersant also enhances the flowability and slam loss control of the cement composition.

Furthermore, Japanese Patent Application Laid-Open No. 7-2670705 discloses that

(A) a copolymer of a polyalkylene-glycol- (mono) acrylic acid ester compound and a (meth) acrylic acid compound or a salt thereof;

(B) A copolymer of a polyalkylene glycol mono (meth) aryl ester compound and maleic anhydride, or a salt or hydrolyzate thereof , and

(C) Polyalkyleneglycol -—Lumono (meta) arylester compound and polyalkyleneglycol compound with maleic ester Coalescence or its salt

A cement dispersant containing a specific ratio of and is disclosed, and this dispersant is effective for improving the water reduction of the cement composition, suppressing slanpros and reducing the viscosity. It has been clarified that this is the case.

However, it has been confirmed by the present inventors that these known cement admixtures have poor fluidity and slanpros inhibitory properties. However, it is not always satisfactory, and in order to meet the recent demands of consumers, further higher performance is required.

The present invention has been made in view of the above-mentioned problems, and its object is to provide an excellent fluidity improving effect and slanting effect which are superior to the conventional cement admixture as described above. Provided is a cement admixture having a process-suppressing property, and further provides a high-performance cement composition containing the admixture, and further uses the composition. The purpose of the present invention is to provide a high-performance cement structure. DISCLOSURE OF THE INVENTION The cement admixture of the present invention has a solid content equivalent of:

Lignin sulfonate [I]: 50-80 parts by weight,

(a) H, unsaturated carboxylic acid and / or salts thereof: 40 to 83 parts by weight,

(b) (meta) acrylic acid ester (excluding hydroxyalkyl ester): 10 to 30 parts by weight, and

(c) (Meth) hydroxyalkyl ester of acrylic acid: 7 to 50 parts by weight

[However, the sum of (a), (b) and (c) is 100 parts by weight]

There is a gist in that the copolymer [II] containing 50 to 20 parts by weight of is a monomer component.

Particularly preferred as the (meth) hydroxyalkyl ester of (meth) acrylic acid constituting the copolymer of the present invention is an alkyl moiety having 2 to 4 carbon atoms. Hydroxyalkyl esters and (b) particularly preferred as the (meth) acrylic acid ester are those having 1 to 4 carbon atoms in the form of allyl alcohol. E: It is an acrylate ester.

The cement composition containing the above-mentioned cement admixture has a remarkably improved fluidity and slanproth-inhibiting property, and has a remarkable improvement in the present invention. The present invention is also applicable to a cement structure, which is a cured product thereof. BEST MODE FOR CARRYING OUT THE INVENTION Under the above-mentioned problems, the present inventors have earnestly aimed at further improving the fluidity and the slanth process inhibiting property of a cement composition. As a result of repeated research, it was found that the use of a cement admixture containing a lignin sulfonate and a copolymer of a specific composition can achieve the above-mentioned tasks brilliantly. Thus, the present invention has been completed.

Here, lignin sulfonate is commonly found in natural pulp raw materials.

It is a natural macromolecule (molecular weight is said to be distributed from hundreds to millions) contained in about 50 to 60%, and its type depends on the treatment method. Nin and high performance lignin.

Lignin sulfonate, which is classified as general lignin, is obtained by desugaring the digested effluent from sulphite pulp production, and has an average molecular weight (Mw). ) Is said to be 10,000 or less (usually about 6,000 to 8,000). Lignin sulfonate, which is classified as a high-performance lignin, can be used for the above-mentioned digestion eluate or its desaccharified solution by converting it into a high-molecular fraction and a low-molecular fraction. It is a high-molecular fraction portion of fractionated fractions and has an average molecular weight (M w) of 10,000 or more (usually about 10,000 to 20,000). In fact, these lignin sulfonates are desugared. They are roughly classified into Mg'Na salt, Na salt, and Ca salt according to the difference in the treatment method.

In the present invention, the metal salt can be effectively used irrespective of the type of the metal salt, general lignin, and high-performance lignin. Especially preferred are high performance lignins.

Next, as described above, the copolymer used in combination with the ligninsulfonate may be, as described above, a polyunsaturated carboxylic acid and / or a salt thereof (a) and (meta) acrylic acid. It is a copolymer containing an acid ester (b) and a hydroxyalkyl ester of (meth) acrylic acid (c) as an essential monomer component.

Examples of the unsaturated carboxylic acid component (a) include (mono) unsaturated monocarboxylic acids such as acrylic acid and crotonic acid; itaconic acid and fumaric acid. And unsaturated dicarboxylic acids such as maleic acid and citraconic acid, and their semi-esters, and the salts thereof include alkali metal salts and alkaline earth metals. Examples include metal salts, ammonium salts, and organic amine salts.

These can be used alone or, if necessary, in combination of two or more. The use ratio is the ratio occupying in 100 parts by weight of all monomers constituting the copolymer and should be in the range of 40 to 83 parts by weight in terms of β, β-unsaturated carboxylic acid. It is. If the amount is less than 40 parts by weight, a sufficient slanpros inhibitory effect cannot be obtained, and if it exceeds 83 parts by weight, the air entrainment of the cement composition becomes poor. The preferred lower limit of the 5-unsaturated carboxylic acid and / or its salt (a) is 60% in order to achieve both the slumping property and the effect of suppressing slanpros and air entrainment. Parts by weight, a more preferred upper limit is 75 parts by weight. Next, the (meth) acrylic acid ester (b) is preferably an ester of an alkanol having 1 to 4 carbon atoms, specifically,-(meth) acrylic acid Methyl, (meth) ethyl acrylate, (meth) acrylic acid n_butyl, (meth) acrylic acid i-butyl, (meta) t-butyl acrylate These can be used alone, or two or more of them can be used in combination as needed. The compounding amount of the (meth) acrylic acid ester (b) is in the range of 1 ° to 30 parts by weight based on 100 parts by weight of all monomer components constituting the copolymer. If the amount is less than 10 parts by weight, the ability to inhibit flowability and slanpros becomes poor, and if the amount exceeds 30 parts by weight, the hydrophilicity of the admixture decreases, and the admixture with cement becomes poor. It lacks gender. A more preferred lower limit of the amount of the (meth) acrylic acid ester (b) is 10 parts by weight, and a more preferred upper limit is 25 parts by weight.

The (alkyl) hydroxyalkyl ester (c) of (meth) acrylic acid is preferably an alkyl ester having 2 to 4 carbon atoms, for example, 2-hydroxy. Kishetil (meta) acrylate, 2—hydroxypropyl (meta) acrylate, 3—hydroxypropyl (meta) acrylate, 2—hid Roxybutyl (meta) acrylate, 3—Hydroxybutyl (meta) acrylate, 4-Hydroxybutyl (meta) acrylate, 3—Cross mouth 1-2—Hydroxypropyl (meta) acrylate. These can be used alone, or two or more can be used in combination.

What is the blending amount in terms of the proportion occupied in 100 parts by weight of all monomer components constituting the copolymer? It is in the range of 50 to 50 parts by weight. If the amount is less than 7 parts by weight, wettability with cement becomes poor and dispersibility is poor. On the other hand, if the amount exceeds 50 parts by weight, the slam prosthesis suppressing effect is not only deteriorated, but also the air entrainment becomes too high, which is not preferable. The lower limit of the more preferred amount of the hydroxyalkyl ester (c) of (meth) acrylic acid is 7 parts by weight, and the more preferable upper limit is 30 parts by weight.

The method for producing a copolymer using these monomers is not particularly limited, but the most common method is a radial polymerization method, and among them, a solution polymerization method is preferable. As a reaction solvent, it is preferable to use water from the viewpoint of safety and harmlessness.

Examples of the radical polymerization initiator include peroxides such as benzoyl peroxide and t-butyl benzoyl benzoyl, and azo compounds represented by azobisisobutyronitrile. Further, it can be appropriately selected and used depending on the type of the monomer, such as ammonium persulfate, potassium persulfate, and persulfate such as sodium persulfate. The polymerization reaction is carried out at normal pressure or under pressure, usually in the range of 50 to 150 ° C, preferably at 50 to 100 ° C under normal pressure.

The obtained copolymer alone exhibits excellent fluidity and slanpros-suppressing properties as a cement admixture, but it has been confirmed by the present inventors. It was also found that when the copolymer is used in combination with an appropriate amount of lignin sulfonate, the modifying effect as a cement admixture is further enhanced. In order to effectively exert such a combined effect, the copolymer and lignin sulfonate are preferably in a weight ratio of 50 to 20: 50 to 80, more preferably 50 to 80. It must be used together at a ratio of 35 to 20:65 to 8 °, and even if the ratio is too large or too small, the excellent modification effect intended by the present invention can be obtained. I can't do it. By the way, if the blending ratio of the above copolymer is too large (the blending ratio of lignin sulfonate is insufficient), the slanpros-suppressive effect becomes less persistent, As will be apparent from the examples described later, an excellent slanpros inhibitory effect is exhibited until about 30 minutes elapse from the kneading, but after about 60 minutes elapses. The effect of suppressing slanpros decreases.

On the other hand, if the blending ratio of the lignin sulfonate is too large (the blending ratio of the above copolymer is insufficient), the sustaining effect of the suppression of the slump is similarly reduced, and the general rig is not used. In garlic, slanproth inhibitory properties decrease about 30 minutes after kneading, and even when high-performance lignin is used together, it takes about 60 minutes or more. The effect of suppressing slanpros decreases.

As described above, the present invention is characterized in that the copolymer having a specified monomer composition and ligninsulfonate are blended at a specific ratio. According to further studies, the cement dispersant disclosed in JP-A-7-267705 was used in place of the above-mentioned copolymer. Even when oxyorganic acid salts such as gluconate are used in place of ligninsulfonate, it can be a very good cement admixture. Since they were confirmed, they will be explained below.

First, oxyorganic acid salts such as gluconate, which can be used in place of lignin sulfonate, can themselves effectively act as a cement reducer. Although it is known, the use of the oxyorganic acid salt in combination with the above-mentioned copolymer in place of lignin sulfonate is also excellent as a cement admixture. Performance is demonstrated. When the oxyorganic acid, particularly gluconate, is used in combination with the copolymer, a preferable blending ratio is in a weight ratio, preferably 20 to 75 parts by weight of the copolymer. Gluconate: 80 to 25 parts by weight, more preferably 50 to 25 parts by weight, and it can be used in place of the copolymer. The cement dispersant disclosed in Kaihei 7-2670705 discloses a polyalkylene glycol mono (meth) acryl as a component (I). Copolymer of acid ester compound and (meth) acrylic acid compound and / or salt thereof, (II) Polyalkylene glycol mono (meta) As a copolymer of an aryl ether compound and anhydrous maleic acid and its salt or hydrolyzate (C), polyalkyl Preferable is a copolymer of a glycol alcohol (meta) alcohol compound and a maleic acid ester of a polyalkylene glycol compound. (Α), (Β), (C) The components were blended at a ratio of 5 to 40: 30 to 70: 5 to 40 (% by weight). The combination of a dispersant and lignin sulfonate in a weight ratio of 50 to 20: 50 to 80 also provides a fluid with excellent fluidity and slanpros inhibitory properties. A ment admixture can be obtained.

The preferred component (ii) is a polyalkylene glycol mono (meth) acrylic acid ester compound represented by the following general formula [1]: ] Or a salt thereof with a (meth) acrylic acid-based compound or a salt thereof.

R ¹

CH ₂ = CC-0- 0) _n -R ³ …… [1] 0

(Wherein, R ¹ represents hydrogen or a methyl group, and R ² represents carbon Represents an alkylene group of the formulas 2 to 4, R ³ represents hydrogen or an alkyl group of 1 to 5 carbon atoms, and n represents an integer of 1 to L 0.

,Four

CH 2 C-1 COOX [2]

(Wherein, R ⁴ represents hydrogen or a methyl group, and X represents hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group)

The alkylene group represented by R ² in the above general formula [1] is an ethylene group, a propylene group, a butylene group, or the like, and is preferably an ethylene group, a propylene group, or the like. A pyrene group is particularly preferred, and an ethylene group is particularly preferred. The number n of added moles of R ²⁰ may be any integer as long as it is in the range of 1 to 100, preferably 1 to 50, and more preferably 1 to 30. R ³ is hydrogen or an alkyl group having 1 to 5 carbon atoms, and examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Preferred as the alkyl group are hydrogen, a methyl group, and an ethyl group, and particularly preferred are a hydrogen and a methyl group.

The copolymerization ratio of the component represented by the general formula [1] and the component represented by the general formula [2] constituting the component (A) is as follows: the component represented by the general formula [1]: 10 to 95 wt. % Of the component represented by the general formula [2]: 90 to 5% by weight, and more preferably the former: 50 to 90% by weight to the latter 50 to 10% by weight. % By weight, and more preferably the former: 60 to 90% by weight, and the latter 40 to 10% by weight (the total of both is 100% by weight).

The preferred molecular weight of the component (A) is 2,000 in weight average molecular weight. ~ 100,000, more preferably 5,000-70,000, and even more preferably 10,000-50,000. -Next, the component (B) is a copolymer of a polyalkylene glycol mono (meth) aryl ether compound represented by the following general formula [3] and a water-free maleic acid. Coalesce and its salts or hydrolysates,

R ⁵

CH ₂ = C-CH ₂ 0- (R ⁶ 0) _m -R ⁷ …… [3] 0

(Wherein, R ⁵ represents hydrogen or a methyl group, R ⁶ represents an alkylene group having 2 to 4 carbon atoms, and R ⁷ represents a hydrogen or methyl group having 1 to 5 carbon atoms. Represents an alkyl group, and m represents an integer of 1 to 100)

The alkylene group represented by R ⁶ in the above general formula [3] is an ethylene group, a propylene group, a butylene group, and the like, but preferred are an ethylene group and a propylene group. A pyrene group is particularly preferred, among which an ethylene group is preferred. The number m of added moles of R ⁶⁰ may be any integer as long as it is in the range of 1 to 100, preferably in the range of 2 to 50, and more preferably in the range of 5 to 50. R ⁷ is hydrogen or an alkyl group having 1 to 5 carbon atoms, and examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Preferred as the alkyl group are hydrogen, a methyl group, and an ethyl group, and particularly preferred is a methyl group.

The copolymerization ratio of the component represented by the general formula [3] to maleic anhydride is 30 to 99% by weight of the former to 70 to 1% by weight of the latter, more preferably 50 to 100% by weight of the former. ~ 98 wt% vs. the latter 50 ~ 2 wt%, more preferably the former 80 ~ 98 wt% vs. the latter 20 ~ 2 wt% (However, the total of both is 100% by weight). The preferred molecular weight of the component (B) is from 2,000 to 100,000, more preferably from 3,000 to 60,000, and even more preferably from 5,000 to 40,000 in terms of weight average molecular weight. .

The component (C) is composed of a poly (ethylene glycol) copolymer (meta) aryliether ether compound represented by the same general formula as the above general formula [3], and the following general formula [4] A copolymer of a polyalkylene glycol compound represented by the following formula with maleic acid ester or a salt thereof.

R ⁸ 0-(R ⁹ 0) P-H …… [4]

(In the formula, R ⁸ represents hydrogen or an alkyl group having 1 to 5 carbon atoms, R ⁹ represents an alkylene group having 2 to 4 carbon atoms, and p is an integer of 1 to 100. Express)

In the poly (ethylene glycol) (meta) aryl sole ether compound represented by the general formula [3] and used for producing the component (C), the substituent R ⁶ The alkylene group shown is, for example, an ethylene group, a propylene group, or a butylene group, and the preferred one is an ethylene group, a propylene group, and among them. Particularly preferred is an ethylene group. 1 ⁶ 0 additional molar number 111 may be a that of how integer in the range of 1 to 100. However, preferred and rather 2-5 0, rather then favored further the area by der of 5-5 0 . R ⁷ is hydrogen or an alkyl group having 1 to 5 carbon atoms, and examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Hydrogen, a methyl group, and an ethyl group are particularly preferable, and a methyl group is particularly preferable.

The substituent R ⁸ in the polyalkylene glycol-based compound represented by the general formula [4] is hydrogen or an alkyl having 1 to 5 carbon atoms. The alkyl group includes a methyl group, an ethyl group, a propyl group, and the like, and is preferably hydrogen, a methyl group, and an ethyl group, and particularly preferably. What is new is hydrogen and a methyl group. The alkylene group represented by R ⁹ is an ethylene group, a propylene group, a butylene group, or the like, preferably an ethylene group, a propylene group, or the like. Particularly preferred is an ethylene group. Addition molar number p of R ⁹ 〇 may be in a how that integer in the range of 1 to 100. However, preferred and rather 1-5 0, rather further favored Ru der range of 1-3 0.

The copolymerization ratio of the component represented by the general formula [3] and the component represented by the general formula [4] constituting the component (C) is as follows: the component represented by the general formula [3]: 1 to 99% by weight In contrast, the component represented by the general formula [4] may be in the range of 99 to 1% by weight, more preferably the former is 3 to 97% by weight and the latter is 97 to 3% by weight. More preferably, the former is in the range of 40 to 95% by weight, and the latter is in the range of 60 to 5% by weight (the total of both is 100% by weight).

The preferred molecular weight of the component (C) is from 2,000 to 100,000, more preferably from 5,000 to 70,000, and even more preferably from 10,000 to 50,000 in weight average molecular weight.

Examples of the salts of the above polymers include ammonium salts, alkali metal salts (such as sodium salts and potassium salts), and alkaline earth metal salts (calcium salts and magnesium salts). Gnesium salt, etc.).

When these components (A) to (C) are used as a cement admixture, these components may be blended into the cement composition in a preferred blending ratio, or may be prepared by adding three components in advance. Is prepared as a mixture, and this can be mixed with a cement composition in an appropriate amount. The preferred mixing ratio of these three components depends on the distribution of the cement composition used. Since it depends on conditions such as the admixture material and the temperature at the time of use, it cannot be specified uniformly, but is preferably the solid content ratio of each component, and the component (A): 5 to 40% by weight, more preferably 3 to 30% by weight, component (B): 30 to 70% by weight, more preferably 40 to 65% by weight, component (C): It is in the range of 5 to 40% by weight, more preferably 5 to 30% by weight (the sum of the three components is 100% by weight). Further, the mixing ratio of the component (A) and the component (B) is preferably in the range of 2: 8 to 4: 6 in terms of solid content weight ratio.

The above-mentioned component (A) is extremely excellent in dispersibility in cement, and has a function of increasing the initial fluidity of the cement composition, but has a poor slanprose inhibitory property. In addition, it tends to markedly increase the viscosity of the cement composition and imparts thixotropy, so that it can be used alone as a cement admixture. Lack of aptitude. Further, the dispersibility of the component (B) in the cement is not as excellent as that of the component (A), and it takes time to increase the initial fluidity. Therefore, if the initial amount of fluidity is increased by increasing the amount of addition, the fluidity further increases over time thereafter, and problems such as separation of the cement composition may occur. In particular, since this phenomenon appears remarkably in a cement composition having a small water / cement ratio, the component (B) alone can be used as a cement admixture again. Lack of aptitude.

Further, the component (C) has a lower cement dispersibility than the component (B), and the addition amount is increased especially for a cement composition having a small water / cement ratio. Even at the beginning, the required fluidity cannot be obtained in the early stage, and (B) the fluidity increases over time as in the case of the component, causing problems such as separation of the cement composition. .

It is presumed that the reason why these components have different effects on the cement composition is due to the molecular structure of each component. That is the first The effect of increasing the initial fluidity is different in the case of a polymer having a (meth) acrylic acid functional group such as the component (A), as in the case of the components (B) and (C). This is probably because the adsorption rate to cement particles is higher than that of a polymer having a maleic acid functional group. Conversely, those having a high adsorption rate have poor fluidity retention ability thereafter, and the components (B) and (C) have fluidity retention ability over time.

It is presumed that the reason why the viscosity of the cement composition is given by the blending of the admixture is that the admixture adsorbs to the cement particles to form a steric bond. Details are not clear.

The lower viscosity of the cement composition when using the components (B) and (C) than when using the component (A) is due to the polyoxyalkyl in the molecules of the components (B) and (C). Since the len group has a very high affinity, the water molecules have an affinity for the admixture adsorbed between the cement particles, and as a result, the distance between the cement particles is widened. It is also expected that the dynamic friction of cement particles is reduced.

In any case, the viscosity of the cement composition to which an appropriate amount of each of the components (A), (B), and (C) is added is generally sufficient when the water / cement ratio is large. However, when the ratio is small, the spacing between cement particles is small due to the large amount of unit cement, and the effect on viscosity is remarkably exhibited for the above-mentioned reason. Seem . For this reason, the mixture can be more effective when applied to cement compositions with a low water / cement ratio. Wear .

When a mixture comprising the above components (A), (B) and (C) is used in combination with lignin sulfonate instead of the above-mentioned copolymer [II], the present invention provides It is possible to obtain a cement admixture with both improved flowability and improved slanproth control. As described above, the present invention is characterized in that the above-described copolymer and lignin sulfonate are used in combination, and the above-mentioned ( Alternatively, a mixture of components (A), (B) and (C) may be used, or by using an oxyorganic acid such as gluconate instead of ligninsulfonate. It is possible to obtain a cement admixture having a high reforming effect.

In the present invention, a part of ligninsulfonate is used by replacing it with an oxyorganic acid salt such as gluconate, or is used in addition to ligninsulfonate. It is also effective to additionally add a oxyorganic acid salt. Similarly, a part of the copolymer [II] may be replaced with a mixture of the above components (A), (B) and (C), or the copolymer [II] may be used. It is also effective to additionally add a mixture of the above-mentioned components (A), (B) and (C) in addition to the amount of the cement admixture according to the present invention based on the cement. Is preferably in the range of 0.1 to 1.0, more preferably in the range of 0.2 to 0.6% by weight of the total solid content relative to the cement weight. If the amount is less than 0.1% by weight, the modifying effect as a cement admixture is not sufficiently exhibited, and if the amount exceeds 1.0% by weight, the aggregate may cause separation or poor curing. It may be.

The cement admixture of the present invention may be added to the cement paste, mortar concrete, etc. simultaneously with water injection, or may be kneaded immediately after water injection. It may be added until immediately after, or may be added to the cement composition once kneaded. In addition, each component may be added in a mixed state or may be added individually to uniformly disperse and mix when kneading the cement composition.

Further, the cement admixture of the present invention may be used in combination with other known modifying additives. For example, AE agents, foaming agents, antifoaming agents, curing retarders, fast-strength agents, curing accelerators, thickeners, water retention agents, waterproofing agents, antibacterial agents, drying shrinkage reducing agents-coloring agents, preservatives, etc. It is also possible to use them together. Furthermore, it can be used in combination with, for example, blast furnace slag, silica fume, fly ash, and expansive agent.

The cement admixture of the present invention thus obtained has a superior water reducing (dispersing) effect, a fluidity improving effect, and a slanpros inhibitory effect as compared with the conventional cement admixture. Is provided. In addition, the cement composition containing this cement admixture has a low viscosity and excellent separation stability, and is suitable for workability including pumping property. Is also excellent. Further, the cement structure obtained by curing the composition has excellent strength and durability, which are also included in the technical scope of the present invention. EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, and has the purport of the preceding and the following. It is also possible to carry out the present invention with appropriate modifications within a range that can be adapted to the above, all of which are included in the technical scope of the present invention. Reference example

In a stainless steel reaction vessel equipped with a thermometer, stirrer, dropping funnel, nitrogen gas inlet tube and reflux condenser, water is used as a polymerization reaction solvent, and a radical polymerization initiator is used. And β-stain-unsaturated carboxylic acid and / or its salts and various Copolymerization was carried out using (meth) acrylic acid ester and (medium) hydroxyalkyl ester of acrylic acid in the ratios shown in Table 1. In Table 1, MAA represents methyl acrylate, MMA represents methyl methacrylate, and HEMA represents 2-hydroxyhexyl methacrylate. Table 1 also shows the nonvolatile content concentration and the viscosity of each of the obtained copolymers.

table 1

Example

The copolymer of No. 6 (as a sodium salt) shown in Table 1 above was used, and the following six kinds of lignin sulfonates were used. The two were blended in the ratio shown in Table 2 to obtain a cement admixture. Using each cement admixture, concretes were prepared according to the formulation shown in Table 3, and the change over time in fluidity was measured. The kneading method, the kneading procedure and the method for measuring the change over time were as follows. Table 2 summarizes the results. [Lignin sulfonate used]

A: Mg, Na salt type of general lignin (trade name “San extract FDL” manufactured by Nippon Paper Industries)

B: General lignin Na salt type (Bolegard product name)

"Boresnosu")

C: General lignin Ca salt type (NMB product name “P

N 6 4 5)

D: High performance lignin Mg, Na salt type (“UL — PAR” manufactured by Kojin Pulp)

E: High-performance lignin Na salt type (Nippon Paper Industries brand name "No, 'One Lex")

[Materials used]

Cement: Asano * Chichibu Onoda · Sumitomo Osaka ordinary Portland Cement (specific gravity: 3.16)

Fine aggregate: Kisarazu mountain sand (specific gravity 2.36, water absorption 1.57, coarse grain ratio

2.77)

Coarse aggregate: Ome crushed stone Gmax20mm (specific gravity 2.67, water absorption 0.51, coarse particle ratio 6.73, actual rate 58.1%)

A E agent: Product name “Norrick A E” manufactured by FPC

100 "

Defoaming agent: Toho Chemical Co., Ltd. product name "Pronal 753" [Test method]

Kneading: Use of 100 liter forced pan mixer, kneading amount

40 liters

Kneading procedure: (coarse aggregate + 1/2 fine aggregate + cement + 1/2 fine bone) Is kneaded for 10 seconds, and a predetermined amount of cement admixture and water are added thereto, and the mixture is kneaded for 90 seconds to obtain a concrete. Adjust the air volume to about 4 to 5% immediately after kneading with the AE agent and antifoaming agent.

Temporal change: A spiral mixer simulating an agitated mixer is used. Mixer rotation speed lrpm, sample volume 40 liters. The fluidity is measured 30 minutes and 60 minutes after the kneading. The amount of air after 60 minutes from the kneading is in the range of about 11 to 11% with respect to immediately after the kneading.

Table 2

Note) The effect was evaluated based on whether the fluidity decreased within 5.8 cm, which is the decrease in fluidity 60 minutes after the copolymer alone was added (Experiment No. 1).

Table 3 Concrete mix (mix)

Note) In the above formula, plain concrete (from nothing to unit water) is reduced by 16% (3 lkg / m ³ per unit water).

Effects of the Invention The present invention is constituted as described above, and comprises a copolymer having a characteristic monomer composition in which the components (a), (b) and (c) are copolymerizable monomer components, and a resin. By using gninsulfonate in a specific ratio, a superior flowability improving effect (cement dispersibility) and a slumping performance over conventional cement admixtures are achieved. The present invention can provide a cement admixture having a cement-suppressing property (cement dispersion retention property), and can use the cement admixture in cement, mortar, and concrete. By using these cement compositions as admixtures for cement compositions such as these, the flowability and flow retention of these cement compositions at the time of construction can be enhanced and the workability is excellent. A ment composition can be obtained. Also, since the cement admixture has a small adverse effect on the cement hydraulic property, it gives a cement structure having excellent compressive strength and durability.

Claims

The scope of the claims

1. In terms of solid content,

Lignin sulfonate [I]: 50 to 80 parts by weight;

(a) a,? —unsaturated carboxylic acid and / or salts thereof: 40 to 83 parts by weight,

(c) Hydroxyalkyl esters of (meth) acrylic acid:

7 to 50 parts by weight

[However, the sum of (a), (b) and (c) is 100 parts by weight]

A copolymer containing as a monomer component [Π]: 20 to 50 parts by weight.

2. The cement admixture according to claim 1, wherein the? -Unsaturated carboxylic acid defined in (a) is an unsaturated monocarboxylic acid.

3. The cement admixture according to claim 2, wherein said unsaturated monocarboxylic acid is mecryacrylic acid.

4. The (meth) acrylic acid ester defined in the above (b) is a (meth) acrylic acid ester of a C1-C4 alkanol. 4. The cement admixture according to any one of items 3 to 7.

5. The cement admixture according to claim 4, wherein the (meth) ester acrylate is methyl methacrylate.

6. In the hydroxyalkyl ester of (meth) acrylic acid defined in (c) above, the alkyl moiety has 2 to 4 carbon atoms. The cement admixture according to any one of claims 1 to 5.

7. The cement admixture according to claim 6, wherein the hydroxyalkyl ester of the (meta) acrylic acid is 2-hydroxyhexyl methacrylate. Agent.

8. Copolymer [11]

(a) ，, _ unsaturated carboxylic acid and / or its salts: 60 to 75 parts by weight,

(b) (meta) acrylic acid ester (excluding hydroxyalkyl ester): 10 to 25 parts by weight, and

(c) (Meth) hydroxyalkyl ester of acrylic acid:

7 to 30 parts by weight

[However, the total of (a), (b) and (c) is 100 parts by weight]

The cement admixture according to any one of claims 1 to 7, wherein the cement admixture is a monomer component.

9. A cement composition comprising the cement admixture according to any one of claims 1 to 8.

10. A cement structure comprising a cured product of the cement composition according to claim 9.