JP2019123648A - Cement additive, and cement composition - Google Patents

Abstract

To provide a cement additive that has a depression effect for viscosity increase in a cement composition, and excellent in initial fluidity and time-varying fluidity.SOLUTION: A cement additive of the present invention including a polycarboxylic acid-based copolymer contains a structural unit (I) derived from an unsaturated polyalkylene glycol-based monomer, a structural unit (II) derived from an unsaturated dicarboxylic acid-based monomer, and a structural unit (III) derived from a carboxylic acid hydroxyalkyl ester-based monomer, in which the structural unit (I) is 40 to 87 mass%, the structural unit (II) is 5 to 30 mass%, and the structural unit (III) is 8 to 30 mass%, with respect to 100 mass% of the total sum of structural unit (I), structural unit (II), and structural unit (III).SELECTED DRAWING: None

Description

  The present invention relates to cement additives and cement compositions.

  For cement compositions such as cement paste, mortar and concrete, the purpose is to improve properties such as flowability immediately after kneading of the cement composition, flow retention during aging after kneading, strength development after hardening of the cement composition, etc. As various additives are included. In recent years, the development of concrete and the like having higher strength and higher durability has been promoted, and the reduction of the unit water content and the reduction of the water-cement ratio have become issues. Moreover, the viscosity such as the plastic viscosity and the yield value of the cement composition increases with the reduction of water, which causes a problem that the construction workability is lowered. Therefore, as an additive for reducing the viscosity of a cement composition, an additive for cement containing a polycarboxylic acid-based copolymer has conventionally been proposed (Patent Document 1).

JP, 2017-88470, A

  In recent years, cement compositions in particular are required to maintain desired fluidity and viscosity over time after kneading, in addition to viscosity reduction immediately after kneading, but conventional cement additives In order to obtain sufficient effects, it is necessary to increase the amount added, which causes problems such as a significant increase in cost.

  The present invention has been made focusing on the above circumstances, and the object of the present invention is not only to reduce the viscosity immediately after kneading of the cement composition, but also to improve the fluidity and viscosity of the cement composition over time after kneading. Providing an additive.

（式（Ｉ）中、
Ｒ²は、水素原子又は炭素数１〜１８のアルキル基を表し、
Ｒ³、Ｒ⁴、及びＲ⁵は、同一又は異なって、水素原子、又は、メチル基を表し、
Ｒ⁶は炭素数０〜５のアルキレン基を表し、
Ｒ¹Ｏは、同一又は異なって、炭素数２〜１８のオキシアルキレン基を表し、
ｍは、Ｒ¹Ｏで表されるオキシアルキレン基の平均付加モル数であって、５〜３００を表す。）

（式（ＩＩ）中、
Ｒ⁷、Ｒ⁸、及びＲ⁹は、同一又は異なって、水素原子、炭素数１〜８のアルキル基、または−（ＣＨ_２）ｚＣＯＯＭ²を表し（但し、Ｒ⁷〜Ｒ⁹のいずれか１つが−（ＣＨ_２）ｚＣＯＯＭ²である）、
ｚは０〜２の整数であり、
Ｍ¹、Ｍ²は、同一又は異なって、水素原子、一価金属、二価金属、アンモニウム基、又は有機アミン基を表す。 The present invention, which has solved the above problems, is an additive for cement containing a polycarboxylic acid copolymer, and the polycarboxylic acid copolymer comprises the following structural unit (I), a structural unit (II) And a structural unit (III) derived from a carboxylic acid hydroxyalkyl ester-based monomer, based on 100% by mass in total of the structural unit (I), the structural unit (II), and the structural unit (III) The structural unit (I) is 40 to 87% by mass, the structural unit (II) is 5 to 30% by mass, and the structural unit (III) is 8 to 30% by mass. Have.

(In the formula (I),
R ² represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms,
R ³ , R ⁴ and R ⁵ are the same or different and each represents a hydrogen atom or a methyl group,
R ⁶ represents an alkylene group having 0 to 5 carbon atoms,
R ¹ O is the same or different and represents an oxyalkylene group having 2 to 18 carbon atoms,
m is an average added mole number of the oxyalkylene group represented by R ¹ O, and represents 5 to 300. )

(In the formula (II),
R ⁷ , R ⁸ and R ⁹ are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or-(CH ₂ ) zCOOM ² (however, any one of R ^{7 to} R ⁹ ) One is-(CH ₂ ) zCOOM ² ),
z is an integer of 0 to 2,
M ¹ and M ² are the same or different and each represents a hydrogen atom, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group.

Cement additive of the present invention, (1) In the formula (II), it is either one of R ^8, and R ^9, it is COOM ^2, (2) In the above formula (I), the R ⁶ The carbon number of the alkylene group is 1 or 2, (3) in the formula (I), m is 5 to 100, (4) carboxylic acid hydroxyalkyl ester from which the structural unit (III) is derived In any of the preferred embodiments, the system monomer is (meth) acrylic acid hydroxyalkyl ester.

  The present invention also includes a cement composition containing cement, water, and the above-described cement additive of the present invention. Furthermore, it is also preferable to include a cement dispersant, and in a preferred embodiment, the dispersant is at least one selected from the group consisting of a sulfonic acid based dispersant, a polycarboxylic acid based dispersant, and a phosphoric acid based dispersant. is there.

  The cement additive of the present invention has excellent properties of viscosity reduction of the cement composition and fluidity of the cement composition. In particular, the additive for cement of the present invention has an excellent property of suppressing the increase in viscosity immediately after kneading of the cement composition and with time after kneading, and also has excellent flowability with time after kneading of the cement composition. Hereinafter, the viscosity immediately after the kneading may be referred to as “initial viscosity”, the viscosity over time as “temporal viscosity”, simply combining the two, simply “viscosity” or combining the effects of the two and referred to as “viscosity increase suppression”. Also, the flowability immediately after kneading may be referred to as "initial flowability", the flowability over time may be referred to as "flowability over time", and the two may be simply referred to as "flowability". According to the present invention, a cement composition containing the above-mentioned additive for cement can be provided.

FIG. 1 is a schematic cross-sectional view of a J14 funnel according to JSCE Standard JSCE-F 541 for measuring the funnel down time. FIG. 2 is a graph showing the relationship between the funnel flow-down time and mortar flow value immediately after mortar kneading in Example 1 and Comparative Example 1. FIG. 3 is a graph showing the relationship between the funnel flow-down time and the mortar flow value 30 minutes after the mortars of Example 1 and Comparative Example 1 were kneaded. FIG. 4 is a graph showing the relationship between the funnel flow-down time and the mortar flow value 60 minutes after the mortars of Example 1 and Comparative Example 1 were kneaded.

  In the present specification, "(meth) acrylic" means "acrylic and / or methacrylic". Moreover, "acid (salt)" means "acid and / or a salt thereof". Moreover, "mass" and "weight" may be read as "weight" and "mass", respectively.

(Polycarboxylic acid copolymer)
The cement additive of the present invention comprises a specific polycarboxylic acid copolymer. While containing the said specific polycarboxylic acid type copolymer, while exhibiting the effect excellent in the viscosity increase suppression of a cement composition, it has the characteristic excellent also in time-lapse fluidity.

  If the additive for cement of the present invention contains the polycarboxylic acid-based copolymer of the present invention satisfying the following constitution, the above-described effect is obtained. The cement additive of the present invention may contain one or more of the polycarboxylic acid copolymer of the present invention.

  The polycarboxylic acid-based copolymer of the present invention comprises a structural unit (I), a structural unit (II), and a structural unit (III) derived from a carboxylic acid hydroxyalkyl ester-based monomer. The “structural unit derived from a monomer” is a structural unit formed by polymerizing a monomer, and specifically, the polymerizable carbon-carbon double bond of the monomer has become a single bond It is a structure.

(Structural unit (I))

  In the polycarboxylic acid-based copolymer of the present invention, only one type of structural unit (I) represented by the following formula may be contained, or two or more types may be contained.

In formula (I), R ³ , R ⁴ and R ⁵ are the same or different and each represents a hydrogen atom or a methyl group.

R ⁶ represents an alkylene group having 0 to 5 carbon atoms, preferably 0 to 3 carbon atoms, more preferably 1 or 2 carbon atoms. As a C1-C5 alkylene group, any of a linear or branched alkylene group may be sufficient. R ⁶ is exemplified by methylene, ethanediyl, propanediyl, methylpropanediyl, ethylpropanediyl, butanediyl, methylbutanediyl, pentanediyl, more preferably methylene, ethanediyl, propanediyl, butanediyl, pentanediyl, still more preferably methylene Ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,4-diyl.

Wherein (I), R ¹ O may be the same or different and each represents an oxyalkylene group having 2 to 18 carbon atoms. The carbon number of the oxyalkylene group is preferably 2 to 8, more preferably 2 to 4.

Examples of R ¹ O include an oxyethylene group, an oxypropylene group, an oxybutylene group and an oxystyrene group, preferably an oxyethylene group, an oxypropylene group and an oxybutylene group, more preferably an oxyethylene group and an oxypropylene group It is. When two or more different R ¹ O structures are present, the addition form of R ¹ O may be any form such as random addition, block addition, alternating addition, and the like. In addition, in order to secure the balance of hydrophilicity and hydrophobicity, it is preferable to include an oxyethylene group as an essential component in the oxyalkylene group. Specifically, the oxyethylene group is preferably 80 mol% or more, more preferably 90 mol% or more, and still more preferably 100 mol% with respect to 100 mol% of all the oxyalkylene groups.

In formula (I), R ² represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. The carbon number of the alkyl group is preferably 1 to 10, more preferably 1 to 8. The alkyl group may be a substituted alkyl group or an unsubstituted alkyl group. As a C1-C18 alkyl group, any of a linear, branched or cyclic alkyl group may be sufficient. The alkyl group having 1 to 18 carbon atoms is preferably methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group or isobutyl group, and more preferably methyl group, ethyl group or n- group. Propyl and n-butyl.

In formula (I), m is the average added mole number of the oxyalkylene group represented by R ¹ O, and is 5 to 300. m is preferably 5 to 100, more preferably 6 to 90, still more preferably 8 to 85, and particularly preferably 10 to 80. When m is in the above range, it is effective for suppressing the increase in viscosity of the cement composition, and it is possible to exhibit an excellent effect of fluidity, in particular, fluidity with time. In the formula (I), the “average number of moles added” of the oxyalkylene group represented by m means an oxyalkylene added in 1 unit of the structural unit represented by the formula (I) in 1 mole of the copolymer. The average value of the number of moles of the group is meant.

(Structural unit (II))
The polycarboxylic acid-based copolymer of the present invention may contain only one type of structural unit (II) represented by the following formula, or may contain two or more types. The structural unit (II) is effective in suppressing the viscosity increase of the cement composition by being combined with the structural unit (I) and the following structural unit (III), and further contributes to the improvement of the flowability.

In formula (II), R ⁷ , R ⁸ and R ⁹ are the same or different and each is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or-(CH ₂ ) zCOOM ² (wherein R ⁷ to Any one of R ⁹ is — (CH ₂ ) zCOOM ² ), preferably one of R ⁸ and R ⁹ is COOM ² .

  In formula (II), z is an integer of 0-2. z is preferably 0 or 1, more preferably 0.

In formula (II), M ¹ and M ² are the same or different and each represents a hydrogen atom, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group. Also, -COOM ¹ may form an anhydride with other-(CH ₂ ) zCOOM ² .

  As the monovalent metal and the divalent metal, any appropriate metal atom can be adopted. Preferred examples of the monovalent metal include alkali metals such as lithium, sodium and potassium; and preferred examples of the divalent metal include alkaline earth metals such as calcium and magnesium.

The ammonium group is a functional group represented by “—NH ₄ ⁺ ”. Further, as the organic amine group, any appropriate organic amine group may be adopted as long as it is a protonated organic amine. Examples of the organic amine group include alkanolamine groups such as ethanolamine group, diethanolamine group and triethanolamine group; alkylamines such as monoethylamine, diethylamine and triethylamine group; and polyamines such as ethylenediamine and triethylenediamine.

(Structural unit (III))
Structural unit (III) is a structural unit derived from a carboxylic acid hydroxyalkyl ester monomer. The polycarboxylic acid-based copolymer of the present invention may contain only one type of structural unit (III) or may contain two or more types. The structural unit (III) contributes to the above effects of the present invention by combining the structural unit (I) and the structural unit (II) in a predetermined ratio.

  The structural unit (III) is preferably a structural unit derived from (meth) acrylic acid hydroxyalkyl ester, more preferably the carbon number of the alkyl moiety is preferably 1 to 8, more preferably 2 to 4 (meta ) A structural unit derived from acrylic acid hydroxyalkyl ester. Specifically, structural units derived from (meth) acrylic acid hydroxyethyl ester, structural units derived from (meth) acrylic acid hydroxypropyl ester, or structural units derived from (meth) acrylic acid hydroxybutyl ester are preferable.

  The content ratios of the structural unit (I), the structural unit (II) and the structural unit (III) contained in the polycarboxylic acid copolymer of the present invention are the structural unit (I), the structural unit (II), and the structural unit The structural unit (I) is 40 to 87% by mass, the structural unit (II) is 5 to 30% by mass, and the structural unit (III) is 8 to 30% by mass with respect to 100% by mass in total of the unit (III) . Preferably, the structural unit (I) is 45 to 86% by mass, the structural unit (II) is 5 to 25% by mass, and the structural unit (III) is 9 to 30% by mass. More preferably, it is 50-85 mass% of structural unit (I), 5-20 mass% of structural unit (II), and 10-30 mass% of structural unit (III). When each content ratio of the structural unit (I), the structural unit (II), and the structural unit (III) is within the above range, it is effective for suppressing the viscosity increase of the cement composition and is also excellent in fluidity Play. In addition, each content rate of structural-unit (I)-(III) calculates | requires the reaction rate of the monomer as described in an Example by high performance liquid chromatography, and calculates it based on it.

  The total content ratio of the structural units (I) to (III) contained in the polycarboxylic acid-based copolymer is preferably 50 to 100% by mass, more preferably 100% by mass of the polycarboxylic acid-based copolymer. It is 70 to 100% by mass, more preferably 80 to 100% by mass, particularly preferably 90 to 100% by mass, and most preferably 95 to 100% by mass. If the total content ratio of the above-mentioned structural units (I) to (III) of the present invention is within the above range, it is possible to effectively suppress the viscosity increase of the cement composition and the flowability. In the case where the total of the structural units (I) to (III) is less than 100% by mass, the remaining structural unit (IV) described later and / or various known additives can be contained.

(Structural unit (IV))
The polycarboxylic acid-based copolymer of the present invention may contain, in addition to the structural units (I) to (III), structural units (IV) derived from another monomer (d). Structural unit (IV) may be contained alone or in combination of two or more.

The other monomer (d) is a monomer other than the monomer from which the structural units (I) to (III) are derived. The structural unit (IV) derived from the other monomer (d) is preferably a structural unit derived from the following monomer.
Monocarboxylic acid-based monomers such as (meth) acrylic acid and crotonic acid or salts thereof; various (alkoxy) (poly) s such as polyethylene glycol mono (meth) acrylate and methoxy (poly) ethylene glycol mono (meth) acrylate Alkylene glycol mono (meth) acrylates; (poly) ethylene glycol di (meth) acrylates, (poly) propylene glycol di (meth) acrylates and the like (poly) alkylene glycol di (meth) acrylates; hexanediol di (meth) Multifunctional (meth) acrylates such as acrylate and trimethylolpropane tri (meth) acrylate; (poly) alkylene glycol dimaleates such as polyethylene glycol dimaleate; vinyl sulfonate, (meth) allyl sulfonate, 2 Unsaturated sulfonic acids (salts) such as methyl propane sulfonic acid (meth) acrylamide and styrene sulfonic acid; (meth) acrylic (alkyl) amide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide and the like Unsaturated amides of 1); amides of unsaturated monocarboxylic acids such as methyl (meth) acrylamide and the like and amines having 1 to 30 carbon atoms; vinyl aromatics such as styrene, α-methylstyrene and vinyl toluene; Alkanediol mono (meth) acrylates such as 4-butanediol mono (meth) acrylate; dienes such as butadiene and isoprene; unsaturated cyanides such as (meth) acrylonitrile; unsaturated esters such as vinyl acetate; ) Aminoethyl acrylate, dimethylaminoethyl (meth) acrylate, Unsaturated amines such as vinylpyridine; divinyl aromatics such as divinyl benzene; allyls such as (meth) allyl alcohol and glycidyl (meth) allyl ether;

  The content ratio of the structural unit (IV) contained in the polycarboxylic acid-based copolymer of the present invention is preferably 0 to 100% by mass, more preferably 100% by mass in total of the structural units (I) to (III). Preferably it is 0-5 mass%. If the structural unit (IV) is a predetermined amount, the polycarboxylic acid copolymer of the present invention can exhibit the above effects. The content ratio of the structural unit (IV) can also be specified in the same manner as the structural units (I) to (III).

  The weight average molecular weight (Mw) of the polycarboxylic acid-based copolymer of the present invention is 5,000 to 100 as a weight average molecular weight (Mw) in terms of polyethylene glycol by gel permeation chromatography (GPC) described in the examples. , 000. The weight average molecular weight (Mw) is preferably 6,000 to 80,000, more preferably 7,000 to 50,000, still more preferably 8,000 to 30,000, and particularly preferably 9,000 to 25,000. is there. When the weight average molecular weight (Mw) of the polycarboxylic acid copolymer is in the above range, it is effective for suppressing the increase in viscosity of the cement composition, and exhibits excellent effects of fluidity.

(Production method of polycarboxylic acid copolymer)
Although the method for producing the polycarboxylic acid copolymer of the present invention is not particularly limited, it is preferable to use unsaturated polyalkylene glycol monomer (a), dicarboxylic acid monomer (b) and carboxylic acid hydroxyalkyl ester compound. The polymerization of the monomer component containing the monomer (c) may be carried out in the presence of a polymerization initiator. Other monomers (d) may be contained as required.

The structural unit (I) is formed derived from the unsaturated polyalkylene glycol monomer (a) shown in the following formula (1).

In said Formula (1), R < ³ >, R < ⁴ > and R < ⁵ > are the same or different, and represent a hydrogen atom or a methyl group. R ⁶ represents an alkylene group having 0 to 5 carbon atoms. R < ¹ > O is the same or different and represents a C2-C18 oxyalkylene group. R ² represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. m is an average added mole number of the oxyalkylene group represented by R ¹ O, and is 5 to 300. The carbon number of the preferred oxyalkylene group represented by R ¹ O, and the preferred example thereof; the carbon number of the preferred alkyl group represented by R ² , and the preferred example thereof; the preferred alkylene represented by R ⁶ Since the carbon number of the group is the same as the preferable range of m, the description is omitted.

  As the unsaturated polyalkylene glycol monomer (a), any unsaturated polyalkylene glycol ether monomer satisfying the structural unit (I) can be adopted. Specific examples of the unsaturated polyalkylene glycol ether monomer (a) represented by the formula (1) include hydroxyethyl vinyl ether, allyl alcohol, methallyl alcohol, 3-buten-1-ol, 3- Methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-2-buten-1-ol, 3-buten-2-ol, 3-methyl-3-butene- A C2-C18 alkylene oxide was added to a C2-C10 unsaturated alcohol such as 2-ol, 2-methyl-3-buten-1-ol or 2-methyl-3-buten-2-ol Examples thereof include unsaturated alcohol alkylene oxide adducts and the like. It is preferably a compound obtained by adding 5 to 300 moles of ethylene oxide or propylene oxide to any of allyl alcohol, methallyl alcohol and 3-methyl-3-buten-1-ol, and more preferably methallyl alcohol or 3- It is a compound in which 5 to 300 mol of ethylene oxide is added to at least one selected from methyl-3-buten-1-ol.

  The synthesis of the unsaturated polyalkylene glycol monomer (a) is not particularly limited, and may be performed by various known methods. For example, it can be synthesized by adding an alkylene oxide to an unsaturated alcohol such as allyl alcohol, methallyl alcohol, 3-methyl-3-buten-1-ol (isopreneol), hydroxyethyl vinyl ether, hydroxybutyl vinyl ether and the like.

The structural unit (II) is formed from a dicarboxylic acid monomer (b) represented by the following formula (2).

In formula (2), R ⁷ , R ⁸ and R ⁹ are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or-(CH ₂ ) zCOOM ² (provided that R ⁷ to Any one of R ⁹ is-(CH ₂ ) zCOOM ² ). Preferably, either one of R ⁸ and R ⁹ is COOM ² . z represents an integer of 0 to 2; M ¹ and M ² are the same or different and each represents a hydrogen atom, a monovalent metal, a divalent metal, an ammonium group, an organic ammonium group, or an organic amine group. Since the preferred examples of suitable ranges, M ^1, M ² and z is the same as the structural unit (II), the description thereof is omitted.

  As the dicarboxylic acid monomer (b) represented by the formula (2), unsaturated dicarboxylic acid monomers such as maleic acid, itaconic acid and fumaric acid or salts thereof; maleic acid, itaconic acid and fumaric acid Anhydrides of unsaturated dicarboxylic acid monomers such as acids or their salts; and the like. Examples of the salt as used herein include alkali metal salts, alkaline earth metal salts, ammonium salts, organic ammonium salts, organic amine salts and the like. Examples of the alkali metal salt include lithium salt, sodium salt, potassium salt and the like. Examples of alkaline earth metal salts include calcium salts and magnesium salts. Examples of the organic ammonium salt include methyl ammonium salt, ethyl ammonium salt, dimethyl ammonium salt, diethyl ammonium salt, trimethyl ammonium salt, triethyl ammonium salt and the like. Examples of the organic amine salt include alkanolamine salts such as ethanolamine salt, diethanolamine salt, triethanolamine salt and the like. Among these, maleic acid and fumaric acid are preferable, and by using the structural unit (II) derived therefrom, the effect of suppressing the increase in viscosity of the cement composition and improving the fluidity are exhibited more excellently.

  The structural unit (III) is formed by deriving from the carboxylic acid hydroxyalkyl ester monomer (c). Although any carboxylic acid hydroxyalkyl ester monomer may be employed, it is preferably (meth) acrylic acid hydroxyalkyl ester, and more preferably the alkyl moiety has 1 to 8 carbon atoms, more preferably 2 to 2 carbon atoms. (Meth) acrylic acid hydroxyalkyl ester of 4. Specifically, (meth) acrylic acid hydroxyethyl ester, (meth) acrylic acid hydroxypropyl ester, or (meth) acrylic acid hydroxybutyl ester is preferable.

  Unsaturated polyalkylene glycol monomers (a), dicarboxylic acid monomers (b), and hydroxyalkyl carboxylates which can be used for the preparation of the polycarboxylic acid copolymer contained in the cement additive of the present invention The amount of each of the ester-based monomers (c) used may be appropriately adjusted so that the proportion of each structural unit in all the structural units constituting the polycarboxylic acid-based copolymer falls within the above range.

  If necessary, other monomers (d) may be used, and structural units (IV) are formed from the other monomers (d). Specific examples of the other monomer (d) correspond to the above-mentioned monomers.

  The polymerization of the monomer components may be carried out in any suitable manner. For example, solution polymerization and bulk polymerization can be mentioned. As a system of solution polymerization, a batch system and a continuous system are mentioned, for example. Examples of solvents that can be used in solution polymerization include water; alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane and n-hexane; and esters such as ethyl acetate Compounds; ketone compounds such as acetone and methyl ethyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane; and the like.

  When the monomer component is polymerized, a water-soluble polymerization initiator, for example, a persulfate such as ammonium persulfate, sodium persulfate, potassium persulfate, etc. as a polymerization initiator; hydrogen peroxide; 2,2'- Azoamidine compounds such as azobis-2-methylpropionamidine hydrochloride, cyclic azoamidine compounds such as 2,2'-azobis-2- (2-imidazolin-2-yl) propane hydrochloride, 2-carbamoylazoisobutyronitrile etc. Water-soluble azo initiators such as azonitrile compounds of These polymerization initiators include alkali metal sulfites such as sodium bisulfite, metabisulfite, sodium hypophosphite, Fe (II) salts such as moly salt, sodium hydroxymethanesulfinate dihydrate, hydroxylamine hydrochloride Promoters such as salts, thioureas, L-ascorbic acid (salts) and erythorbic acid (salts) can also be used in combination. Among the polymerization initiators, persulfates and hydrogen peroxide are preferable. Among the promoters, Fe (II) salts such as Mohr's salt and L-ascorbic acid (salts) are preferable. Each of these polymerization initiators and promoters may be only one type, or two or more types.

  When performing solution polymerization using a lower alcohol, an aromatic hydrocarbon, an aliphatic hydrocarbon, an ester compound, or a ketone compound as a solvent, or when performing bulk polymerization, benzoyl peroxide, lauroyl peroxyl as a polymerization initiator Oxides, peroxides such as sodium peroxide; hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide; azo compounds such as azobisisobutyronitrile; and the like can be used. When using such a polymerization initiator, promoters, such as an amine compound, can also be used together. Furthermore, when a water-lower alcohol mixed solvent is used, it can be appropriately selected and used from the above-mentioned various polymerization initiators or a combination of a polymerization initiator and an accelerator.

  The reaction temperature at the time of the polymerization of the monomer component is appropriately determined depending on the polymerization method, the solvent, the polymerization initiator, and the chain transfer agent to be used. Such reaction temperature is preferably 0 ° C. or more, more preferably 30 ° C. or more, still more preferably 50 ° C. or more, preferably 150 ° C. or less, more preferably 120 ° C. or less, still more preferably 100 ° C. or less is there.

  Any appropriate method may be adopted as a method of introducing the monomer component into the reaction vessel.

  In the polymerization of the monomer components, preferably, a chain transfer agent may be used. Use of a chain transfer agent facilitates molecular weight control of the resulting copolymer. The chain transfer agent may be only one type, or two or more types.

  Any appropriate chain transfer agent may be employed as the chain transfer agent. As such a chain transfer agent, for example, a thiol-based chain transfer agent such as mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, 2-mercaptoethanesulfonic acid; Secondary alcohols such as isopropanol; phosphorous acid, hypophosphorous acid, and salts thereof (sodium hypophosphite, potassium hypophosphite, etc.), sulfite, hydrogen sulfite, dithionite, metabisulfite, And lower oxides and salts thereof (sodium sulfite, potassium sulfite, sodium bisulfite, potassium bisulfite, sodium dithionite, potassium dithionite, sodium metabisulfite, potassium metabisulfite etc.); Can be mentioned.

  Although the manufactured cement additive can be used as it is as the cement additive of the present invention, the pH of the reaction solution after the manufacture of the cement additive is adjusted to 5 or more from the viewpoint of handling. Is preferable. However, in order to improve the polymerization rate, it is preferable to carry out polymerization at a pH of less than 5 and to adjust the pH to 5 or more after polymerization. The adjustment of pH can be performed using, for example, an alkaline substance such as an inorganic salt such as a monovalent metal or divalent metal hydroxide or carbonate; ammonia; an organic amine;

  The prepared cement additive can also be subjected to concentration adjustment to the solution obtained by the preparation, if necessary.

  The manufactured cement additive may be used as it is in the form of a solution, or may be used after being powdered.

(Cement composition)
The cement composition of the present invention is cement paste, mortar, concrete or the like, and contains the additive for cement of the present invention.

  The cement composition of the present invention comprises cement, water, and the cement additive of the present invention. Preferably, it comprises cement, water, aggregate, and the cement additive of the present invention.

  As cements, Portland cement (usually, early strength, super early strength, moderate heat, low heat, sulfate and low alkali-type), various mixed cements (blast furnace cement, silica cement, fly ash cement), white portland cement Alumina cement, super rapid hardening cement (1 clinker rapid curing cement, 2 clinker rapid curing cement, magnesium phosphate cement), cement for grout, oil well cement, low heat generation cement (low heat generation blast furnace cement, fly ash mixed low heat generation blast furnace Cement, cement with high belite content, ultra-high strength cement, cement-based solidifying material, eco cement (cement manufactured from one or more of municipal waste incineration ash and sewage sludge incineration ash) is preferable, and blast furnace Slag, fly ash, cinder ash, clean Over ash, husk ash, silica fume, silica powder, a fine powder and gypsum limestone powder may be added. The cement contained in the cement composition of the present invention may be one kind or two or more kinds.

  As the aggregate, in addition to sand, gravel, crushed stone, regenerated aggregate, water-slag, etc., silica, clay, zircon, high alumina, silicon carbide, graphitic, chromium, black, magnesia, etc. The fireproof aggregate of is also exemplified. The aggregate may be appropriately selected according to the application, and for example, the mortar contains fine aggregate such as sand, cement, water, and the additive for cement of the present invention. For example, concrete includes coarse aggregate such as gravel, fine aggregate, cement, water, and the additive for cement of the present invention.

  The cement additive of the present invention in the cement composition may have any suitable content, depending on the purpose. For example, the polycarboxylic acid copolymer of the present invention is preferably 0.001 parts by mass to 10 parts by mass, more preferably 0.005 parts by mass to 5 parts by mass, more preferably 100 parts by mass of cement, in solid content. Is 0.01 to 3 parts by mass, particularly preferably 0.01 to 2 parts by mass, and most preferably 0.01 to 1 parts by mass. If the content of the polycarboxylic acid copolymer of the present invention in the cement composition is within the above range with respect to cement, the unit water content can be reduced, the strength can be increased, the durability can be improved, and the effects unique to the present invention It is possible to express in a compatible manner with suppression of viscosity increase, fluidity).

The amount of unit water, the amount of cement used, and the water / cement ratio per 1 m ³ of the cement composition of the present invention containing the cement additive of the present invention can be set appropriately. Preferably, the unit water amount is 100 to 185 kg / m ³ , the cement amount used is 250 to 800 kg / m ³ , the water / cement ratio (mass ratio) = 0.1 to 0.7, and more preferably the unit water amount is 120 to 175 kg / m ³ The amount of cement used is 270 to 800 kg / m ³ , and the water / cement ratio (mass ratio) is 0.15 to 0.65. The cement composition of the present invention can be used widely from poor to rich blends, and is effective for both high-strength concrete with a large amount of cement and poorly formulated concrete with a unit cement amount of 300 kg / m ³ or less.

  The cement composition of the present invention may contain any other appropriate components in addition to the cement additive of the present invention as long as the effects of the present invention are not impaired.

  As other components, for example, cement additives such as cement dispersant, AE agent, antifoaming agent, setting retarder, curing accelerator, curing retarder, waterproofing agent, rust inhibitor, crack reducing agent, expansive agent, etc. These may be added alone or in combination of two or more. In the present invention, it is preferable to add a cement dispersant.

  The cement dispersant adsorbs on the surface of the cement particles immediately after addition of the cement dispersant or after aging, and it has the function of dispersing the cement particles by its repulsion and enhancing the fluidity of the cement composition, in particular It is not limited. The cement dispersant is preferably at least one selected from the group consisting of a sulfonic acid-based dispersant having a sulfonic acid group in the molecule, a polycarboxylic acid-based dispersant, and a phosphoric acid-based dispersant. By using a cement dispersant in combination with the cement composition of the present invention, it is effective for suppressing the increase in viscosity of the cement composition, and an effect with excellent fluidity can be exhibited.

  Examples of sulfonic acid-based dispersants include polyalkylaryl sulfonate-based sulfonic acid-based dispersants such as naphthalenesulfonic acid-formaldehyde condensates, methylnaphthalenesulfonic acid-formaldehyde condensates, anthracenesulfonic acid-formaldehyde condensates; melamine sulfonic acid-formaldehyde condensates Such as melamine formalin resin sulfonate-based sulfonic acid based dispersant; aminoaryl sulfonic acid-phenol-formaldehyde condensate etc. aromatic amino sulfonate-based sulfonic acid based dispersant; lignin sulfonate, modified lignin Lignin sulfonate-based sulfonic acid-based dispersants such as sulfonates; polystyrene sulfonate-based sulfonic acid-based dispersants; and the like.

  Various known polycarboxylic acid-based copolymers can be used as the polycarboxylic acid-based dispersant (however, except for the polycarboxylic acid-based copolymer contained in the additive for cement of the present invention, the same applies hereinafter), preferably Is preferably a polycarboxylic acid-based dispersant which is a homopolymer or copolymer of a monocarboxylic acid-based monomer, and more preferably a polycarboxylic acid-based copolymer having a polyalkylene glycol chain. For example, a dispersant containing a constituent unit derived from an unsaturated (poly) alkylene glycol ether monomer; a dispersant containing a constituent unit derived from an unsaturated monocarboxylic acid monomer; a unit amount of unsaturated monocarboxylic acid ester Dispersant containing structural unit derived from body; dispersing agent containing structural unit derived from (poly) alkylene glycol mono (meth) acrylic acid ester type monomer; dispersion containing structural unit derived from unsaturated dicarboxylic acid type monomer Agents; dispersants containing a structural unit derived from a hydrophobic unsaturated monocarboxylic acid ester type monomer, and the like.

  As a phosphoric acid type dispersing agent, a dispersing agent having a phosphoric acid group in the molecule: a copolymer of a polyalkylene glycol mono (meth) acrylic acid ester type monomer and a phosphoric acid ester type monomer, an aromatic poly Examples thereof include formalin condensates of alkylene glycol ether monomers and aromatic phosphate ester monomers.

  When a dispersant is used, the ratio of the polycarboxylic acid copolymer of the present invention to the cement dispersant may be set depending on the type of cement dispersant used, the mixing conditions, the test conditions, etc., but the viscosity of the cement composition Considering the increase suppressing effect and the initial flowability and the improvement effect on time-lapse flowability, the ratio of the polycarboxylic acid copolymer of the present invention to the cement dispersant (polycarboxylic acid copolymer / dispersant of the present invention) Is preferably 1/99 to 99/1, more preferably 10/90 to 90/10, still more preferably 20/80 to 80/20, particularly preferably 30/70 to 70/30, most preferably 40 / 60 to 60/40.

  The cement composition of the present invention may be effective for ready mixed concrete, concrete for secondary concrete products, concrete for centrifugal molding, concrete for vibration compaction, steam cured concrete, shot concrete and the like. The cement composition of the present invention is a medium flow concrete (a concrete having a slump value of 22 to 25 cm), a high flow concrete (a concrete having a slump value of 25 cm or more and a slump flow value of 50 to 70 cm), a self-filling concrete, a self It may be effective for mortars and concretes that require high fluidity such as leveling agents.

  The cement composition of the present invention may be prepared by blending the components in any suitable manner. For example, the method etc. which knead | mix a component in a mixer are mentioned.

  EXAMPLES Hereinafter, the present invention will be more specifically described by way of examples. However, the present invention is of course not limited by the following examples, and appropriate modifications may be made as long as the present invention can be applied to the purpose. Of course, implementation is also possible, and all of them are included in the technical scope of the present invention. In addition, unless otherwise indicated, when there is a part, it means mass part, and when there is%, it means mass%.

(Measurement conditions of weight average molecular weight (Mw))
The weight average molecular weight (Mw) was measured using GPC (gel permeation chromatography) under the following conditions.
Device: Alliance (2695) (manufactured by Waters)
Analysis software: Empower 2 Professional + GPC option (made by Waters)
Used columns: TSKguardcolumns SWXL (inner diameter: 6.0 mm × 40 mm) + TSK gel G4000 SW XL (inner diameter: 7.8 mm × 300 mm) + G3000 SW XL (inner diameter: 7.8 mm × 300 mm) + G 2000 SW XL (inner diameter: 7.8 mm × 300 mm) (all manufactured by Tosoh Corporation) )
Detector: Differential Refractometer (RI) Detector (Waters, Waters 2414)
Eluent: A solution prepared by dissolving 115.6 g of sodium acetate trihydrate in a mixed solvent of 10999 g of ion-exchanged water and 6001 g of acetonitrile, and adjusting the pH to 6.0 with acetic acid.
Flow rate: 1 mL / min Column temperature: 40 ° C
Measurement time: 45 minutes Sample solution injection volume: 100 μL (eluent solution with a sample concentration of 0.5% by mass)
GPC standard sample: polyethylene glycol manufactured by Tosoh Corp. Mp = 255000, 200,000, 107000, 72750, 44900, 31400, 21300, 11840, 6450, 4020, 1470
Calibration curve: A cubic equation was prepared using the above Mp value of polyethylene glycol.

(High-performance liquid chromatography (LC))
The residual amount confirmation of each monomer used as a reaction raw material was measured on condition of the following.
Device: Waters Alliance 2695 (manufactured by Waters)
Analysis software: Empower Professional (made by Waters)
Column: Atlantis dC18 5 μm (inner diameter 4.6 mm × length 250 mm) × 2 (manufactured by Waters)
Detector: Differential refractometer (RI) detector (Waters 2414), multi-wavelength visible ultraviolet (PDA) detector (Waters 2996)
Solvent: 100 mM aqueous solution of sodium acetate and acetonitrile mixed in a ratio of 6: 4 Flow rate of solution: 1 mL / min Column temperature: 40 ° C.
Measurement time: 30 minutes Sample solution injection volume: 100 μL (sample concentration is 1% by mass)

[Synthesis of Copolymer (A-1)]
Ion exchange water: 109.3 parts is charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen introducing pipe and a reflux condenser, and the inside of the reaction vessel is purged with nitrogen under stirring to 58 ° C. The temperature rose. Next, 159.6 parts of unsaturated polyalkylene glycol ether (IPN-50) obtained by adding 50 mol of ethylene oxide in average to 3-methyl-3-buten-1-ol is dissolved in 104.8 parts of ion exchanged water. An aqueous solution prepared by diluting an aqueous solution with 12.3 parts of maleic acid and 23.4 parts of 2-hydroxyethyl acrylate (HEA) with 45 parts of deionized water is added dropwise over 5 hours to the reaction vessel. At the same time, an aqueous solution prepared by dissolving 1.7 parts of ammonium persulfate in 19.8 parts of ion-exchanged water, and 21.8 parts of ion-exchanged water: 0.5 parts of L-ascorbic acid and 3-mercaptopropionic acid: An aqueous solution in which 1.7 parts were dissolved was dropped over 5 hours. Thereafter, the temperature was maintained at 58 ° C. continuously for 1 hour to complete the polymerization reaction. Thereafter, the reaction solution is neutralized to pH 6 with an aqueous sodium hydroxide solution at a temperature not higher than the polymerization reaction temperature to obtain an aqueous solution of the copolymer (A-1) of the present invention having a weight average molecular weight (Mw) of 12,500. The The reaction rate of each raw material monomer was determined by liquid chromatography (LC) to determine the remaining amount, and the reaction rate of IPN-50 was 91.1%, and the reaction rate of maleic acid was 62.1. The reaction rate of HEA was 99.0%. The obtained copolymer (A-1) is a mixture having the structural unit (I), the structural unit (II), and the structural unit (III) shown in Table 1. Moreover, the ratio of each structural unit of copolymer (A-1) calculated | required from the reaction rate of each raw material monomer was described in Table 1.

[Synthesis of Copolymer (B-1)]
100 parts of ion exchanged water is charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping device, a nitrogen introducing pipe and a reflux condenser, the inside of the reaction vessel is purged with nitrogen under stirring, and the temperature is raised to 58 ° C. did. Next, 162.8 parts of unsaturated polyalkylene glycol ether (IPN-50) obtained by adding 50 mol of ethylene oxide in average to 3-methyl-3-buten-1-ol was dissolved in 107.1 parts of ion exchanged water. An aqueous solution prepared by diluting an aqueous solution, 13.3 parts of acrylic acid and 23.9 parts of 2-hydroxyethyl acrylate (HEA) with 45 parts of ion exchange water is added dropwise over 5 hours to the reaction vessel, At the same time, an aqueous solution prepared by dissolving 2.1 parts of ammonium persulfate in 24.2 parts of ion-exchanged water, 0.6 parts of L-ascorbic acid in 18.8 parts of ion-exchanged water, and 3-mercaptopropionic acid: An aqueous solution in which 2.1 parts were dissolved was dropped over 5 hours. Thereafter, the temperature was maintained at 58 ° C. continuously for 1 hour to complete the polymerization reaction. Thereafter, the reaction solution was neutralized to pH 6 with an aqueous solution of sodium hydroxide at a temperature not higher than the polymerization reaction temperature to obtain an aqueous solution of a comparative copolymer (B-1) having a weight average molecular weight (Mw) of 11,900. The reaction rate of each raw material monomer was determined by measuring the remaining amount by liquid chromatography (LC). The reaction rate of IPN-50 was 83.0%, and the reaction rate of acrylic acid was 93. The reaction rate of HEA was 95.3%. The obtained copolymer (B-1) is a mixture having the structural unit (I), the structural unit (II), and the structural unit (V) shown in Table 1. Further, the proportion of each structural unit of the copolymer (B-1) determined from the reaction rate of each raw material monomer is described in Table 1.

[Synthesis of copolymer (C)] (cement dispersant)
An average of 50 moles of ethylene oxide was added to 377 parts of ion-exchanged water and 3-methyl-3-buten-1-ol in a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introducing pipe and a reflux condenser After charging 400 parts of unsaturated polyalkylene glycol ether (IPN-50) and raising the temperature to 65 ° C, an aqueous hydrogen peroxide solution containing 0.67 parts of hydrogen peroxide and 12.73 parts of ion exchanged water is added thereto did. Next, 58.4 parts of acrylic acid is dropped into the reaction vessel over 3 hours, and at the same time, 0.87 parts of L-ascorbic acid and 1.57 parts of 3-mercaptopropionic acid in 16.49 parts of ion-exchanged water Was dissolved dropwise over 3.5 hours. Thereafter, the temperature was maintained at 65 ° C. continuously for 1 hour to complete the polymerization reaction. At the end of the polymerization reaction, the concentration of the polymerization component (the concentration by mass relative to all the raw materials of all the monomer components) was 60%. Thereafter, the reaction solution was neutralized to pH 7 with an aqueous solution of sodium hydroxide at a temperature not higher than the polymerization reaction temperature to obtain an aqueous solution of a copolymer (C) having a weight average molecular weight of 30,400. The reaction rate of each raw material monomer was determined by liquid chromatography (LC) to determine the remaining amount, and the reaction rate of IPN-50 was 94.1%, and the reaction rate of acrylic acid was 98.1%. It was 2%.

Example 1
The copolymer (A-1) and the copolymer (C) were mixed in a ratio of 6: 4 to obtain a copolymer (1) to be a sample.

Comparative Example 1
The copolymer (B-1) and the copolymer (C) were mixed at a ratio of 6: 4 to obtain a copolymer (2) to be a sample.

Mortar test
The mortar test was performed under the environment of a temperature of 20 ° C. ± 1 ° C. and a relative humidity of 60% ± 15%. The mortar was mix | blended so that it might be set to C / S / W = 900/1260/270 (g) using the material shown below.
C: Cement (Normal portland cement, made by Pacific Cement Co., Ltd.)
S: Fine aggregate (Oi River land sand)
W: Ion-exchanged aqueous solution of sample (copolymer) and antifoaming agent For W, 0.005% by mass of antifoaming agent based on a predetermined amount of sample and cement mass (Micro air 404, manufactured by BASF Pozzolith) The solution was sufficiently homogeneously dissolved in ion exchange water. Moreover, the addition amount of each sample was shown by the mass% of the solid content of each sample with respect to the cement mass.

(Preparation of mortar)
Preparation of mortar was performed as follows. The above C (cement) and the above S (fine aggregate) were put into a kneading container using a high power mixer (manufactured by Maruto Seisakusho, model number: CB-34), and kneaded at a low speed for 10 seconds. Furthermore, while kneading at a low speed, W (ion exchange aqueous solution of sample and antifoaming agent) was charged over 15 seconds. The mixer was stopped 40 seconds after commencing kneading, and the mortar adhered to the wall of the container was scraped off for 20 seconds. Thereafter, the mixture was further kneaded at a high speed for 180 seconds to prepare a mortar.

(Mortar flow value measurement method)
Slump cone (JIS-A-1171), upper end inner diameter 50 mm, lower end inner diameter 100 mm, placed on a flow measurement plate (steel flat plate, 60 cm × 60 cm) installed horizontally, and the mortar obtained as described above A half-packed in height of 150 mm), pushed with a push rod 15 times, further packed mortar to the end of the slump cone, pushed with a push rod 15 times, and smoothed the surface of the slump cone. After that, 11 minutes after the mixer is first started, pull up the slump cone vertically, and expand the diameter of the spread mortar (the diameter of the longest part (long diameter) and the diameter of the part that makes 90 degrees to the long diameter) The location was measured, and the average value was taken as the mortar flow value (initial flow value). The mortar flow value indicates that the larger the numerical value, the better the dispersion performance. Similarly, mortar flow values were measured after 30 minutes and 60 minutes from the start of the mixer start.

(Measurement method of funnel down time)
The funnel down time of the obtained mortar was measured using a J14 funnel as shown in FIG. 1 according to JSCE Standard JSCE-F541. Similarly, the funnel down time of the mortar was measured 30 minutes and 60 minutes after the start of the mixer start. The copolymer (1) and the copolymer (2) were added in the amounts of No. 1 and Table 2 in Table 2. It changed as shown to (i)-(iii), and measured the flow value and the flow-down time.

(Evaluation of water reduction performance, retention performance, and viscosity)
The characteristics of each sample were evaluated from the mortar flow value and the funnel down time.

(Water reduction performance)
Ratio ([wt% / C]) in cement (C) based on the addition amount (wt%) of sample (copolymer) required for the flow value (initial flow value) immediately after kneading to be 250 mm Calculated. The same test was conducted three times, and the values calculated from the approximate expression are shown in Table 2. In addition, it indicates that the water reduction performance is higher as the required addition amount is smaller.

(Retention performance)
Using a mortar with a flow value (initial flow value) of 250 mm immediately after the above kneading, and measuring the flow value (flow value after 60 minutes) after 60 minutes after kneading of the mortar, the flow retention rate (after 60 minutes) The flow value / initial flow value) was calculated and is shown in Table 2.

(viscosity)
The mortar adjusted so that the flow value (initial flow value) immediately after kneading becomes 220 mm, the funnel flow down time of the initial flow value (initial flow down time), and the flow value after 60 minutes after kneading (60 minutes) The funnel down time (60 minutes down time) when the after flow value became 220 mm was measured. The same test was conducted three times, and the values calculated from the approximate expression are shown in Table 2. In addition, it evaluated that viscosity was low, so that the flow-down time was short.

  From Tables 1 and 2 and FIGS. 2 to 4, Example 1 using the copolymer (A-1) satisfying the requirements of the present invention is any of the initial viscosity, the viscosity over time, and the fluidity over time of the cement composition. It was also excellent.

  On the other hand, in Comparative Example 1 in which a copolymer (B-1) containing a structural unit (V) derived from acrylic acid which is an unsaturated monocarboxylic acid monomer in place of the structural unit (II), the viscosity increase The suppression effect was low. Moreover, Example 1 was able to exhibit the outstanding initial stage fluidity | liquidity, a time-lapse | temporal fluidity | liquidity, and viscosity increase suppression by the addition amount smaller than the comparative example 1.

  From these results, the cement additive containing the polycarboxylic acid copolymer configured to satisfy the requirements of the present invention suppresses viscosity increase immediately after kneading of the cement composition and with time after kneading. It can be seen that the liquid also has excellent characteristics.

(Example 2, Comparative Example 2, Comparative Example 3)
[Synthesis of Copolymer (A-2)]
It is carried out in the same manner as the above-mentioned copolymer (A-1) except that the ratio of unsaturated polyalkylene glycol ether (IPN-50), maleic acid and 2-hydroxyethyl acrylate (HEA) is changed, and the weight average molecular weight ( Mw) An aqueous solution of 11,900 copolymer (A-2) was obtained. The reaction rate of each raw material monomer was determined by measuring the remaining amount by liquid chromatography (LC), and the proportion of each structural unit of the copolymer (A-2) was described in Table 3.

[Synthesis of Copolymer (B-2)]
While changing the ratio of unsaturated polyalkylene glycol ether (IPN-50), changing the ratio of maleic acid to acrylic acid and changing the ratio, and not adding 2-hydroxyethyl acrylate (HEA), It carried out similarly to copolymer (A-1), and obtained the aqueous solution of the copolymer (B-2) of weight average molecular weight (Mw) 33,000. About the reaction rate of each raw material monomer, each residual amount was measured and calculated | required by liquid chromatography (LC), and the ratio of each structural unit of a copolymer (B-2) was described in Table 3.

[Synthesis of Copolymer (B-3)]
Same as copolymer (B-1), except that the ratio of unsaturated polyalkylene glycol ether (IPN-50), acrylic acid, and 2-hydroxyethyl acrylate (HEA) is changed, and the weight average molecular weight (Mw (Mw) ) An aqueous solution of 28,800 copolymer (B-3) was obtained. The reaction rate of each raw material monomer was determined by measuring the remaining amount by liquid chromatography (LC), and the proportion of each structural unit of the copolymer (B-3) was described in Table 3.

Example 2
The copolymer (A-2) and the copolymer (C) were mixed at a ratio of 6: 4 to obtain a copolymer (2) to be a sample.

Comparative Example 2
The copolymer (B-2) and the copolymer (C) were mixed at a ratio of 6: 4 to obtain a copolymer (4) as a sample.

Comparative Example 3
The copolymer (B-3) and the copolymer (C) were mixed in a ratio of 6: 4 to obtain a copolymer (5) as a sample.

  The same mortar test was conducted on the copolymers (3) to (5) to evaluate the water reduction performance, the holding performance, and the viscosity. The results are shown in Table 4.

  From Tables 3 and 4, Example 2 using the polycarboxylic acid-based copolymer satisfying the requirements of the present invention was excellent in any of the initial viscosity, the temporal viscosity, and the temporal fluidity of the cement composition. In addition, Example 2 in which the ratio of the structural unit (II) and the structural unit (III) was higher than that of Example 1 was more excellent in the viscosity increase suppressing effect.

  On the other hand, Comparative Example 2 not containing the structural unit (II) and the structural unit (III) was inferior in both initial viscosity and viscosity over time.

  Further, Comparative Example 3 containing no structural unit (II) was also poor in both initial viscosity and viscosity over time as in Comparative Example 2.

Claims (8)

A cement additive comprising a polycarboxylic acid copolymer, wherein
The polycarboxylic acid copolymer is
Structural unit (I) below
And the structural unit (III) derived from a carboxylic acid hydroxyalkyl ester monomer,
The structural unit (I) is 40 to 87 mass% with respect to a total of 100 mass% of the structural unit (I), the structural unit (II), and the structural unit (III), and the structural unit (II) The additive for cement which is 5-30 mass% and whose said structural unit (III) is 8-30 mass%.

(In the formula (I),
R ² represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms,
R ³ , R ⁴ and R ⁵ are the same or different and each represents a hydrogen atom or a methyl group,
R ⁶ represents an alkylene group having 0 to 5 carbon atoms,
R ¹ O is the same or different and represents an oxyalkylene group having 2 to 18 carbon atoms,
m is an average added mole number of the oxyalkylene group represented by R ¹ O, and represents 5 to 300. )

(In the formula (II),
R ⁷ , R ⁸ and R ⁹ are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or-(CH ₂ ) zCOOM ² (however, any one of R ^{7 to} R ⁹ ) One is-(CH ₂ ) zCOOM ² ),
z is an integer of 0 to 2,
M ¹ and M ² are the same or different and each represents a hydrogen atom, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group. The cement additive according to claim 1, wherein one of R ⁸ and R ^{9 in} the formula (II) is COOM ² . The cement additive according to claim 1, wherein in the formula (I), the carbon number of the alkylene group of R ⁶ is 1 or 2.   The cement additive according to any one of claims 1 to 3, wherein m is 5 to 100 in the formula (I).   The additive for cement according to any one of claims 1 to 4, wherein the carboxylic acid hydroxyalkyl ester-based monomer from which the structure (III) is derived is (meth) acrylic acid hydroxyalkyl ester.   A cement composition comprising cement, water, and the cement additive according to any one of claims 1 to 5.   The cement composition according to claim 6, further comprising a cement dispersant.   The cement composition according to claim 7, wherein the dispersing agent is at least one selected from the group consisting of a sulfonic acid based dispersing agent, a polycarboxylic acid based dispersing agent, and a phosphoric acid based dispersing agent.

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