JP6979855B2 - Cement Additives and Cement Compositions - Google Patents

Description

The present invention relates to an additive for inorganic particles containing a polycarboxylic acid-based copolymer. The present invention also relates to cement compositions containing such additives for inorganic particles. It also relates to a cement composition containing such a polycarboxylic acid-based copolymer.

Living polymerization is a polymerization capable of synthesizing a polymer whose structure is controlled, and has the following characteristics (see Non-Patent Document 1).
1. 1. When the polymerization reaction is started, the polymerization proceeds until the monomer has a certain concentration or less.
2. 2. The number average molecular weight increases in proportion to the polymerization rate.
3. 3. The number of polymer molecules (active species) is constant and is not related to the polymerization rate.
4. The molecular weight is stoichiometrically controlled.
5. A polymer having a molecular weight distribution narrower than that of a normal polymerization reaction can be obtained.
6. Subsequent addition of the monomer allows the polymerization reaction to proceed again, and a block copolymer can also be obtained.
7. The end of the polymer chain can be modified in quantitative yield.

As living radical polymerization, RAFT (reversible addition-fragmentation chain transfer) polymerization (see Patent Document 1), MADIX (macro-molecular design via interchange-of xantates) polymerization (see Patent Document 2), RP (Refer to Patent Document 2), NMP (nitroxide-mediated polymerization) (see Patent Document 3), and TERP (organotellurium-mediated living radical polymerization) (see Non-Patent Document 3) are known. Here, since MADIX polymerization has the same reversible chain transfer mechanism as RAFT polymerization, the term RAFT polymerization is used uniformly in the present specification.

ATRP is a catalytic reaction by a transition metal complex, and the polymerization proceeds while the transition metal takes two different oxidation states. It is common to use an alkyl halide as an initiator. Ti, Fe, Co, Ni, Cu, Mo, Ru, Rh, Pd, Re, Os and the like can be used for the core of the transition metal complex, but the method using Cu is the most common. Cu takes two types of oxidation states, ^{Cu 1+} and Cu ^2+. Examples of the transition metal complex having Cu as a nucleus include a Cu nucleus, tris [2- (dimethylamino) ethyl] amine ( _{abbreviated as Me 6} TERN), and tris (2-pyridylmethyl) amine (abbreviated as TPMA). A catalyst composed of a nitrogen-containing ligand such as copper) can be mentioned. Disadvantages of ATRP include the use of alkyl halides, which are unstable in the air, and the use of large amounts of catalysts containing heavy metals. In order to reduce the environmental load, the purification process for removing the catalyst and the treatment of heavy metal-containing waste are indispensable, which increases the production cost of the polymer.

NMP requires a combination of radical initiators, monomers, and nitroxide radicals that trap intermediate polymer radical species. The difficulty of NMP lies in the difficulty of synthesizing a general-purpose initiator capable of supplying both a reactive radical that initiates polymerization and a stable nitroxide radical from a single molecule, resulting in low versatility.

TERP is a polymerization method using an organic tellurium compound, and living polymerization proceeds by an equilibrium reaction between an active species and a dormant dormant species. Although the TERP method is a useful technique capable of highly controlling the polymerization reaction, the problem is the organotellurium compound remaining in the reaction system after the polymerization. Organotellurium compounds have a peculiar unpleasant odor and hue, and are highly toxic. It is difficult to completely remove this odor and coloring even through a general purification step such as reprecipitation. Some organotellurium compounds are volatile, and if the organotellurium compound remains in a low molecular weight form after the polymerization reaction, it causes discomfort due to odor to the handling operator.

In RAFT polymerization, in the presence of a suitable chain transfer agent (RAFT agent), reactions related to RAFT equilibrium are added to the general free radical polymerization of substituted monomers. The advantages of RAFT polymerization are that it can control the polymerization reaction of most of the monomers that can be polymerized by radical polymerization, and that unprotected functional groups in the monomers and solvents (eg, -OH, -NR ₂ , -COOH, -CONR). _2, -SO 3 _H) highly tolerant of, it is possible polymerization even water or protic solvents, it is a wide application range of reaction conditions, is inexpensive easy to use as compared to competing technologies Can be mentioned.

Examples of the RAFT agent include dithioesters (-(C = S) -S-, see Patent Document 1), dithiocarbamate (> N- (C = S) -S-, see Patent Document 4), and trithio. Thiocarbonyls of carbonates (-S- (C = S) -S-, see Patent Documents 5 and 6), xanthates (-O- (C = S) -S-, see Patent Documents 4 and 7) and the like. Examples thereof include compounds having a thio group (-(C = S) -S-), and the living property is exhibited by a reversible chain transfer reaction.

RAFT agents typically establish an equilibrium state consisting of a very small amount of growth radicals and a dormant species (a polymer having a thiocarbonylthio group at the end) that accounts for most of the growth radicals in the presence of a radical polymerization initiator. (See Non-Patent Document 4).

It has been reported that a polymer (hereinafter referred to as PCE) obtained by grafting a polyalkylene glycol on a polycarboxylic acid such as poly (meth) acrylic acid can be obtained by RAFT polymerization.

The results of RAFT polymerization of methoxypolyethylene glycol methacrylate and methacrylic acid at a monomer composition ratio of 100/0 to 0/100 (molar ratio) are disclosed (see Non-Patent Document 5). The molecular weight of the copolymer increases as the proportion of methoxypoly (n = 8.5) ethylene glycol methacrylate increases, for example, when used in a proportion of 70% to 100% by weight, sequentially from about 15,000 to about 18,000. The molecular weight of the copolymer is increased up to, and when methoxypoly (n = 22.7) ethylene glycol methacrylate is used in a ratio of 70% by weight to 100% by weight, the molecular weight is sequentially increased from about 17,000 to about 48,000.

RAFT polymerization using methoxypolyethylene glycol methacrylate (PEGMA) and methacrylic acid in a monomer composition ratio (PEGMA / sodium methacrylate) = 94/6 (weight ratio) is disclosed (see Non-Patent Document 6).

It is well known that PCE obtained by ordinary radical polymerization exhibits cement dispersion performance (see Patent Document 8), but it is said that the effect as a cement dispersant is improved by narrowing the molecular weight distribution thereof. There is a report.

For example, gel permeation chromatography (GPC) obtained by RAFT copolymerization of methoxypolyethylene glycol methacrylate having a molecular weight of 5000 and sodium acrylate at 81.5 / 18.5 (weight ratio) in terms of polyacrylic acid. It is disclosed that a copolymer having a measured weight average molecular weight (Mw) of 52300 and a Mw / Mn of 1.45 obtained by dividing Mw by a number average molecular weight (Mn) is effective as a cement dispersant (Patent). See Document 6).

As a method for obtaining a PCE having a narrow molecular weight distribution showing good performance as a cement dispersant, (1) a methoxypolyethylene glycol methacrylate / sodium methacrylate copolymer obtained by ordinary radical copolymerization or 3-methyl-3-butene. A method for fractionating a -1-ol ethylene oxide adduct / sodium acrylate copolymer into several types of copolymers by using GPC or the like, (2) methoxypolyethylene glycol methacrylate / methacryl by living radical polymerization. A method for obtaining a sodium acid copolymer is known. However, although RAFT polymerization is mentioned as one of the preferred examples of living radical polymerization, its detailed description and demonstration by examples have not been made. As the physical property values of the fractionated polymer, in the case of methoxypoly (n = 25) ethylene glycol methacrylate / sodium methacrylate copolymer (monomer composition ratio = 80/20 (weight ratio)), the polymer of Mw = 42800. Mw / Mn is the lowest at 1.25, and it is disclosed that Mw / Mn increases even with Mw higher or lower than this. In the case of the ethylene oxide adduct of 3-methyl-3-butene-1-ol / sodium acrylate copolymer, the polymer having Mw = 113100 has the lowest Mw / Mn of 1.20 and Mw of 60500, 34200, Mw / Mn tended to increase as it decreased to 24200, 22100, 18500, and 14200, and were 1.26, 1.35, 1.31, 1.35, 1.62, and 2.03, respectively (. See Patent Document 9).

Polymer obtained by RAFT polymerization using methoxypolyethylene glycol methacrylate (PEGMA, Mw = 1100) and methacrylic acid at a monomer composition ratio (PEGMA / sodium methacrylate) of 87.6 / 12.4 (weight ratio). The performance of the polymer obtained by dropping methoxypolyethylene glycol methacrylate and changing the composition distribution in the latter half of the polymerization reaction with the same monomer composition ratio is compared. Each polymer had a degree of polymerization of 100 and Mw = 51500 (see Non-Patent Document 7).

In addition, PCE having a narrow molecular weight distribution obtained without RAFT polymerization has been reported as a cement dispersant.

A copolymer obtained by reacting a polyalkylene glycol mono (meth) acrylic acid ester-based monomer, a carboxylic acid-based monomer having an unsaturated bond, and a monomer copolymerizable with these at a specific ratio. A cement dispersant having a (salt) of Mw of 5,000 or more and less than 10,000 and a Mw / Mn of 1.0 or more and 1.5 or less can obtain a predetermined fluidity with a small amount of addition, and has high strength development. It is disclosed that it is excellent in gap passage (see Patent Document 10). The polymer of Mw = 9800 and Mw / Mn = 1.42 obtained in Production Example 1 expresses a predetermined slump with the smallest addition amount. Further, in Comparative Production Example 4, the lowest polymer with Mw = 4800 and Mw / Mn = 1.30 is disclosed.

A PCE in which polyalkylene glycol is ester- or ether-grafted to a polycarboxylic acid in the main chain, and an additive for concrete having Mw of 1500 to 30,000 and Mw / Mn of 1.0 to 1.6 is disclosed ( See Patent Document 11). However, the polymer described in the examples is only a copolymer of methoxypoly (n = 9 or 23) ethylene glycol methacrylic acid ester and methacrylic acid. Among them, the Mw / Mn of the polymer described in Example 1 is the lowest, 1.33, and the slump flow at a constant slump is the largest, and a concrete in a good fresh state with a silky feeling and a fluffy feeling is produced. It is said that it can be done.

A continuous process for producing comb copolymers of (meth) acrylic acid-based monomers and (meth) acrylic acid ester-based polyether macromonomers has been disclosed as a water reducing agent for cement as compared to those produced by the batch process. Excellent performance (see Patent Document 12). Among them, the polymer of Comparative Example 4 had the lowest Mw / Mn, which was 1.30.

In general, in order to position an additive for inorganic particles containing a polycarboxylic acid-based copolymer as a highly functional cement additive, the inorganic necessary for achieving the desired fluidity in the case of a cement composition. It is important to be able to reduce the amount of particle additives used as much as possible. Further, in order to position the additive for inorganic particles containing a polycarboxylic acid-based copolymer as a high-performance additive for cement, the additive for inorganic particles is used as an additive for cement in order to improve workability and the like. It is important that the viscosity of the added cement composition can be reduced as much as possible. Furthermore, the entrainment air of the cement composition to which the additive for inorganic particles is added as an additive for cement can be sufficiently reduced, and the compressive strength of the cement composition to which the additive for inorganic particles is added as an additive for cement is improved. It is important to let them do it.

Special Table 2000-515181A Japanese Patent Publication No. 2002-512653 U.S. Patent No. 4581429 Japanese Patent Publication No. 2002-508409 Special Table 2003-522816 Japanese Patent Publication No. 2008-508384 Japanese Patent Publication No. 2002-512653 Japanese Unexamined Patent Publication No. 58-74552 WO2007 / 034965A1 Gazette Japanese Unexamined Patent Publication No. 2005-281022 Japanese Unexamined Patent Publication No. 2008-127221 Special Table 2003-505560 Gazette

Roderic P. Quirk and Bumjae Lee, Experimental Criteria for Living Polymerizations, Polymer International 27 (1992) 359-376. M. Kato, M.M. Kamigaito, M.M. Sawamoto, and T. et al. Higashimura, Macromolecules 28 (1995) 1721-1723. Shigeru Yamako, Yasuyuki Nakamura, Living Radical Polymerization 2. Polymerization mechanism and method 2, Japan Rubber Association Paper, 82 (2009) 363-369. A. Fabier, M.M. -T. Charreyre, Experimental Requirerements for an Effect Control of Free-Radical Polymerizations via the Reversible Addition-FragmentRasis2 C. R. Becer, S.M. Han, M.M. W. M. Fijten, H. et al. M. L. Thijs, R.M. Hoogenboom, and U.S. S. Schubert, Libraries of Methacrylic Acid Acid and Oligo (ethylene glycol) Methacryliclate Copolymers with LCST Behavior, Journal-of D. Rinaldi, T.I. Hamaide, C.I. Graillat, F.M. D'agosto, R.M. Spitz, S.A. Georges, M.D. Mosquet, P. et al. Maitrasse, RAFT Copolymerization of Methacrylic Acid and Poly (ethylene glycol) Methyl Ether Methacrylate in the Presence of a Hydrophobic Chain Transfer Agent in Organic Solution and in Water, Journal of Polymer Science: Part A: Polymer Chemistry 47 (2009) 3045-3055. S. Pourchet, S.M. Liautaud, D.M. Rinaldi, I. Pochard, Effect of the repartition of the PEG side chains on the adsorption and dispersion behaviors of PCP in presense 42

An object of the present invention is the use of an additive for inorganic particles that can be used as an additive for cement to be added to a cement composition, which is necessary for achieving the desired fluidity in the cement composition. To provide an additive for inorganic particles, which can reduce the amount, reduce the viscosity of the cement composition as much as possible, sufficiently reduce the entrained air of the cement composition, and improve the compressive strength of the cement composition. It is in. Another object of the present invention is to provide a cement composition containing such an additive for inorganic particles. Another object of the present invention is to provide a cement composition containing such a polycarboxylic acid-based copolymer.

（一般式（１）中、Ｒ^１およびＲ^２は、同一または異なって、水素原子またはメチル基を表し、Ｒ^３は、水素原子または炭素原子数１〜３０の炭化水素基を表し、ＡＯは、炭素原子数２〜１８のオキシアルキレン基を表し、ｎは、ＡＯで表されるオキシアルキレン基の平均付加モル数を表し、ｎは１〜５００の数であり、ｘは０〜２の整数である。）

（一般式（２）中、Ｒ^４〜Ｒ^６は、同一または異なって、水素原子、メチル基、または−（ＣＨ_２）_ｚＣＯＯＭ基を表し、−（ＣＨ_２）_ｚＣＯＯＭ基は−ＣＯＯＸ基または他の−（ＣＨ_２）_ｚＣＯＯＭ基と無水物を形成していても良く、ｚは０〜２の整数であり、Ｍは、水素原子、アルカリ金属、アルカリ土類金属、アンモニウム基、有機アンモニウム基、または有機アミン基を表し、Ｘは、水素原子、メチル基、エチル基、アルカリ金属、アルカリ土類金属、アンモニウム基、有機アンモニウム基、または有機アミン基を表す。） The additive for inorganic particles of the present invention is
Derived from the structural unit (I) derived from the unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) and the unsaturated carboxylic acid-based monomer (b) represented by the general formula (2). An additive for inorganic particles containing a polycarboxylic acid-based copolymer having the structural unit (II) of.
The polycarboxylic acid-based copolymer was obtained by living polymerization.
The weight average molecular weight Mw in terms of polyethylene glycol obtained by gel permeation chromatography of the polycarboxylic acid-based copolymer is 50,000 or less.
The dispersity Mw / Mn of the polycarboxylic acid-based copolymer is 1.00 to 1.25.

(In the general formula (1), R ¹ and R ² represent the same or different hydrogen atom or methyl group, R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and AO represents a hydrocarbon group. , Represents an oxyalkylene group having 2 to 18 carbon atoms, n represents the average number of moles of the oxyalkylene group represented by AO, n is a number of 1 to 500, and x is an integer of 0 to 2. Is.)

(In the general formula ^(2), R 4 ~R ⁶ are the same or different, a hydrogen atom, a methyl group, or _- represents a _(CH 2) z COOM groups, _{- (CH} 2) z COOM group -COOX group Alternatively, it may form an anhydride with another − (CH ₂ ) _z COM group, z is an integer of 0 to 2, and M is a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, or an organic substance. Represents an ammonium group or an organic amine group, where X represents a hydrogen atom, a methyl group, an ethyl group, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group.)

（一般式（１）中、Ｒ^１およびＲ^２は、同一または異なって、水素原子またはメチル基を表し、Ｒ^３は、水素原子または炭素原子数１〜３０の炭化水素基を表し、ＡＯは、炭素原子数２〜１８のオキシアルキレン基を表し、ｎは、ＡＯで表されるオキシアルキレン基の平均付加モル数を表し、ｎは１〜５００の数であり、ｘは０〜２の整数である。）

（一般式（２）中、Ｒ^４〜Ｒ^６は、同一または異なって、水素原子、メチル基、または−（ＣＨ_２）_ｚＣＯＯＭ基を表し、−（ＣＨ_２）_ｚＣＯＯＭ基は−ＣＯＯＸ基または他の−（ＣＨ_２）_ｚＣＯＯＭ基と無水物を形成していても良く、ｚは０〜２の整数であり、Ｍは、水素原子、アルカリ金属、アルカリ土類金属、アンモニウム基、有機アンモニウム基、または有機アミン基を表し、Ｘは、水素原子、メチル基、エチル基、アルカリ金属、アルカリ土類金属、アンモニウム基、有機アンモニウム基、または有機アミン基を表す。） Another additive for inorganic particles of the present invention is
Derived from the structural unit (I) derived from the unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) and the unsaturated carboxylic acid-based monomer (b) represented by the general formula (2). An additive for inorganic particles containing a polycarboxylic acid-based copolymer having the structural unit (II) of.
The additive for inorganic particles contains a defoaming agent and contains
The polycarboxylic acid-based copolymer was obtained by living polymerization.
The dispersity Mw / Mn of the polycarboxylic acid-based copolymer is 1.00 to 1.25.

(In the general formula (1), R ¹ and R ² represent the same or different hydrogen atom or methyl group, R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and AO represents a hydrocarbon group. , Represents an oxyalkylene group having 2 to 18 carbon atoms, n represents the average number of moles of the oxyalkylene group represented by AO, n is a number of 1 to 500, and x is an integer of 0 to 2. Is.)

(In the general formula ^(2), R 4 ~R ⁶ are the same or different, a hydrogen atom, a methyl group, or _- represents a _(CH 2) z COOM groups, _{- (CH} 2) z COOM group -COOX group Alternatively, it may form an anhydride with another − (CH ₂ ) _z COM group, z is an integer of 0 to 2, and M is a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, or an organic substance. Represents an ammonium group or an organic amine group, where X represents a hydrogen atom, a methyl group, an ethyl group, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group.)

In one embodiment, the total content of heavy metals and tellurium in the solid content of the polycarboxylic acid-based copolymer containing the polycarboxylic acid-based copolymer is 300 μg / g or less.

In one embodiment, the polycarboxylic acid-based copolymer has a structure at the polymer end derived from at least one selected from dithioester, trithiocarbonate, dithiocarbamate, and xantane.

In one embodiment, the living polymerization is RAFT polymerization.

In one embodiment, the RAFT agent used in the RAFT polymerization has at least one functional group selected from dithioesters, trithiocarbonates, dithiocarbamates and xanthan.

In one embodiment, the additive for inorganic particles of the present invention is an additive for cement.

The cement composition of the present invention contains the additive for inorganic particles of the present invention and cement.

（一般式（１）中、Ｒ^１およびＲ^２は、同一または異なって、水素原子またはメチル基を表し、Ｒ^３は、水素原子または炭素原子数１〜３０の炭化水素基を表し、ＡＯは、炭素原子数２〜１８のオキシアルキレン基を表し、ｎは、ＡＯで表されるオキシアルキレン基の平均付加モル数を表し、ｎは１〜５００の数であり、ｘは０〜２の整数である。）

（一般式（２）中、Ｒ^４〜Ｒ^６は、同一または異なって、水素原子、メチル基、または−（ＣＨ_２）_ｚＣＯＯＭ基を表し、−（ＣＨ_２）_ｚＣＯＯＭ基は−ＣＯＯＸ基または他の−（ＣＨ_２）_ｚＣＯＯＭ基と無水物を形成していても良く、ｚは０〜２の整数であり、Ｍは、水素原子、アルカリ金属、アルカリ土類金属、アンモニウム基、有機アンモニウム基、または有機アミン基を表し、Ｘは、水素原子、メチル基、エチル基、アルカリ金属、アルカリ土類金属、アンモニウム基、有機アンモニウム基、または有機アミン基を表す。） Another cement composition of the present invention is
A cement composition containing a polycarboxylic acid-based copolymer, an antifoaming agent, and cement.
The polycarboxylic acid-based copolymer has a structural unit (I) derived from an unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) and an unsaturated represented by the general formula (2). A polycarboxylic acid-based copolymer having a structural unit (II) derived from the carboxylic acid-based monomer (b).
The polycarboxylic acid-based copolymer was obtained by living polymerization.
The dispersity Mw / Mn of the polycarboxylic acid-based copolymer is 1.00 to 1.25.

(In the general formula (1), R ¹ and R ² represent the same or different hydrogen atom or methyl group, R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and AO represents a hydrocarbon group. , Represents an oxyalkylene group having 2 to 18 carbon atoms, n represents the average number of moles of the oxyalkylene group represented by AO, n is a number of 1 to 500, and x is an integer of 0 to 2. Is.)

(In the general formula ^(2), R 4 ~R ⁶ are the same or different, a hydrogen atom, a methyl group, or _- represents a _(CH 2) z COOM groups, _{- (CH} 2) z COOM group -COOX group Alternatively, it may form an anhydride with another − (CH ₂ ) _z COM group, z is an integer of 0 to 2, and M is a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, or an organic substance. Represents an ammonium group or an organic amine group, where X represents a hydrogen atom, a methyl group, an ethyl group, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group.)

According to the present invention, in an additive for inorganic particles that can be used as an additive for cement to be added to a cement composition, the use of the additive for inorganic particles necessary for achieving the desired fluidity in the cement composition. To provide an additive for inorganic particles, which can reduce the amount, reduce the viscosity of the cement composition as much as possible, sufficiently reduce the entrained air of the cement composition, and improve the compressive strength of the cement composition. Can be done. Further, it is possible to provide an additive for cement containing such an additive for inorganic particles. Further, it is possible to provide a cement composition containing such a cement additive.

It is explanatory drawing which shows how to draw a baseline in a GPC chart, and how to determine a polymer peak boundary. It is explanatory drawing which shows the method of drawing a baseline in a GPC chart, and another method of determining a polymer peak boundary.

In the present specification, the expression "(meth) acrylic" means "acrylic and / or methacrolein", and the expression "(meth) acrylate" means "acrylate and / or methacrylate". When the expression "(meth) allyl" is used, it means "allyl and / or methacrolein", and when the expression "(meth) acrolein" is used, "acrolein and / or methacrolein" is used. It means "rain". Further, when the expression "acid (salt)" is used in the present specification, it means "acid and / or a salt thereof".

Further, when the expression "mass" is used in the present specification, it may be read as "weight" which is generally used as a unit of weight in the present specification, and conversely, "weight" is used in the present specification. When there is an expression of, it may be read as "mass" which is commonly used as an SI system unit indicating weight.

A. Additives for Inorganic Particles The additives for inorganic particles of the present invention include polycarboxylic acid-based copolymers.

One embodiment of the additive for inorganic particles of the present invention (embodiment (i)) is an additive for inorganic particles containing a polycarboxylic acid-based copolymer. The polycarboxylic acid-based copolymer in this embodiment is obtained by living polymerization, has a polyethylene glycol-equivalent weight average molecular weight Mw obtained by gel permeation chromatography, and has a dispersity Mw /. Mn is 1.00 to 1.25. The polycarboxylic acid-based copolymer will be described in detail in Section A-1.

Another embodiment of the additive for inorganic particles of the present invention (Ii) is an additive for inorganic particles containing a polycarboxylic acid-based copolymer and inorganic particles. The polycarboxylic acid-based copolymer in this embodiment is obtained by living polymerization and has a dispersity of Mw / Mn of 1.00 to 1.25. The polycarboxylic acid-based copolymer will be described in detail in Section A-1.

In the case of the above embodiment (i), the content ratio of the polycarboxylic acid-based copolymer in the solid content of the additive for inorganic particles of the present invention is preferably 50% by mass to 100% by mass, more preferably 70. It is from% by mass to 100% by mass, more preferably 90% by mass to 100% by mass, particularly preferably 95% by mass to 100% by mass, and most preferably substantially 100% by mass. In the case of the above embodiment (i), if the content ratio of the polycarboxylic acid-based copolymer in the solid content of the additive for inorganic particles of the present invention is within the above range, the cement additive to be added to the cement composition. In the additive for inorganic particles that can be used as an additive, the amount of the additive for inorganic particles required to achieve the desired fluidity in the cement composition can be further reduced, and the viscosity of the cement composition can be reduced as much as possible. , It is possible to provide an additive for inorganic particles which can sufficiently reduce the entrained air of the cement composition and improve the compressive strength of the cement composition.

In the case of the above embodiment (ii), the content ratio of the polycarboxylic acid-based copolymer in the solid content of the additive for inorganic particles of the present invention is preferably 45% by mass to 99.98% by mass, more preferably. Is 70% by mass to 99.95% by mass, more preferably 85% by mass to 99.92% by mass, and particularly preferably 90% by mass to 99.9% by mass. In the case of the above embodiment (ii), if the content ratio of the polycarboxylic acid-based copolymer in the solid content of the additive for inorganic particles of the present invention is within the above range, the cement additive to be added to the cement composition. In the additive for inorganic particles that can be used as an additive, the amount of the additive for inorganic particles required to achieve the desired fluidity in the cement composition can be further reduced, and the viscosity of the cement composition can be reduced as much as possible. , It is possible to provide an additive for inorganic particles which can sufficiently reduce the entrained air of the cement composition and improve the compressive strength of the cement composition.

（一般式（１）中、Ｒ^１およびＲ^２は、同一または異なって、水素原子またはメチル基を表し、Ｒ^３は、水素原子または炭素原子数１〜３０の炭化水素基を表し、ＡＯは、炭素原子数２〜１８のオキシアルキレン基を表し、ｎは、ＡＯで表されるオキシアルキレン基の平均付加モル数を表し、ｎは１〜５００の数であり、ｘは０〜２の整数である。）

（一般式（２）中、Ｒ^４〜Ｒ^６は、同一または異なって、水素原子、メチル基、または−（ＣＨ_２）_ｚＣＯＯＭ基を表し、−（ＣＨ_２）_ｚＣＯＯＭ基は−ＣＯＯＸ基または他の−（ＣＨ_２）_ｚＣＯＯＭ基と無水物を形成していても良く、ｚは０〜２の整数であり、Ｍは、水素原子、アルカリ金属、アルカリ土類金属、アンモニウム基、有機アンモニウム基、または有機アミン基を表し、Ｘは、水素原子、メチル基、エチル基、アルカリ金属、アルカリ土類金属、アンモニウム基、有機アンモニウム基、または有機アミン基を表す。） A-1. Polycarboxylic acid-based copolymer The polycarboxylic acid-based copolymer has a structural unit (I) derived from an unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) and a general formula (2). It is a polycarboxylic acid-based copolymer having a structural unit (II) derived from the unsaturated carboxylic acid-based monomer (b) represented by.

(In the general formula (1), R ¹ and R ² represent the same or different hydrogen atom or methyl group, R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and AO represents a hydrocarbon group. , Represents an oxyalkylene group having 2 to 18 carbon atoms, n represents the average number of moles of the oxyalkylene group represented by AO, n is a number of 1 to 500, and x is an integer of 0 to 2. Is.)

(In the general formula ^(2), R 4 ~R ⁶ are the same or different, a hydrogen atom, a methyl group, or _- represents a _(CH 2) z COOM groups, _{- (CH} 2) z COOM group -COOX group Alternatively, it may form an anhydride with another − (CH ₂ ) _z COM group, z is an integer of 0 to 2, and M is a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, or an organic substance. Represents an ammonium group or an organic amine group, where X represents a hydrogen atom, a methyl group, an ethyl group, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group.)

According to the "ICH Q3D: Guidelines for Metal Purities in Pharmaceuticals (Draft)" reported at the Japan-US EU International Council for Harmonization of Pharmaceutical Regulations (ICH), As, Pb, and other metal impurities that require risk assessment are classified as Class 1. Cd, Hg, V, Mo, Se, Co for class 2A, Ag, Au, Tl, Pd, Pt, Ir, Os, Rh, Ru for class 2B, Sb, Ba, Li, Cr, Cu, Sn for class 3. , Ni is mentioned.

Heavy metals such as Mo, Co, Pd, Pt, Os, Rh, Ru, Cu, and Ni may be used in living polymerization, but these are listed in the above guidelines as heavy metals that require risk assessment. It will be required to reduce the amount used in the future.

In addition to heavy metals, tellurium, which is often used in living polymerization, often has high acute toxicity and reproductive toxicity of compounds, and ACGIH (American Conference of Governmental Industrial Hygienists) also defines an allowable concentration, and it is used in the same way as heavy metals. There is a need to reduce the amount.

The polycarboxylic acid-based copolymer contained in the additive for inorganic particles of the present invention preferably has a low content of heavy metals and tellurium. The term "polycarboxylic acid-based copolymer" as used herein refers to the whole including the polycarboxylic acid-based copolymer obtained by the polymerization reaction, the monomers and solvents remaining after the polymerization reaction, the catalyst, and other impurities. That is, the "polycarboxylic acid-based copolymer" refers to the entire composition after the reaction obtained by the polymerization reaction for obtaining the polycarboxylic acid-based copolymer.

The total content of heavy metals and tellurium in the solid content of the polycarboxylic acid-based copolymer is preferably 300 μg / g or less, more preferably 100 μg / g or less, still more preferably 10 μg / g or less. It is particularly preferably 1 μg / g or less, and most preferably 0.1 μg / g or less. The heavy metal and tellurium may or may not be incorporated in the polycarboxylic acid-based copolymer. The amount of the solid content of the polycarboxylic acid-based copolymer is substantially equal to the amount of the polycarboxylic acid-based copolymer.

When the total content of heavy metals and tellurium in the solid content of the polycarboxylic acid-based copolymer is within the above range, for example, it is preferable from the viewpoint of the above two criteria and the like. Further, if the total content of heavy metal and tellurium in the solid content of the polycarboxylic acid-based copolymer is within the above range, the additive for inorganic particles that can be used as an additive for cement to be added to the cement composition is said to be the same. The amount of the additive for inorganic particles required to achieve the desired fluidity in the cement composition can be further reduced, the viscosity of the cement composition can be reduced as much as possible, and the entrainment air of the cement composition can be sufficiently reduced. It is possible to provide an additive for inorganic particles which can improve the compressive strength of the cement composition. The heavy metals mentioned here refer to all the elements listed in each class in the above guidelines.

Here, the solid content represents a non-volatile component contained in the object with respect to the tangible state of the object. The solid content content can be measured by the following method.

<Measuring method of solid content ratio>
A sample of 0.3 g to 1.2 g for measuring the solid content was weighed in an aluminum dish having a known mass, diluted with about 1 g of water, and spread uniformly on the aluminum dish. Dry in a nitrogen atmosphere at 130 ° C. for 1 hour, allow to cool in a desiccator at room temperature for 15 to 30 minutes to return to room temperature, then weigh the dried mass, subtract the mass of the aluminum dish, and dry the sample. The mass of was calculated. The solid content was calculated by dividing the mass of the sample after drying by the mass of the sample before drying.

The additive for inorganic particles of the present invention also preferably has a low content of heavy metals and tellurium. Specifically, the total content of heavy metals and tellurium in the additive for inorganic particles of the present invention is preferably 300 μg / g or less, more preferably 100 μg, with respect to the solid content of the additive for inorganic particles. It is / g or less, more preferably 10 μg / g or less, particularly preferably 1 μg / g or less, and most preferably 0.1 μg / g or less. When the total content of heavy metals and tellurium in the additive for inorganic particles of the present invention is within the above range, it is preferable from the viewpoint of, for example, the above two criteria. Further, if the total content of heavy metal and tellurium in the additive for inorganic particles of the present invention is within the above range, the cement composition of the additive for inorganic particles that can be used as the additive for cement to be added to the cement composition. The amount of the additive for inorganic particles required to achieve the desired fluidity in the product can be further reduced, and the viscosity of the cement composition to which the additive for inorganic particles is added as an additive for cement can be increased as much as possible. It is possible to provide an additive for inorganic particles that can be reduced. The heavy metals mentioned here refer to all the elements listed in each class in the above guidelines.

The amount of heavy metal in the polycarboxylic acid-based copolymer or the polycarboxylic acid-based copolymer is generally measured by using ICP-MS, but the measuring method is not limited to this. When performing analysis by ICP-MS, the polymer sample is diluted with a solvent for measurement. It is essential that the solvent used is one in which the polymer is soluble and does not contain metal.

If the polycarboxylic acid-based copolymer contained in the additive for inorganic particles of the present invention is obtained by living polymerization, only a very small amount of heavy metals or tellul compounds known to be highly environmentally toxic is used. Or, it can be manufactured without using it at all, and it is possible to reduce the environmental load.

It should be noted that the polycarboxylic acid-based copolymer contained in the additive for inorganic particles of the present invention is assumed to be obtained by RAFT (Reversible Addition-Fragmentation Chain Transfer) polymerization as described later in the living polymerization. Since no catalyst containing heavy metals or tellurium is required, there is no risk of heavy metals being mixed into the system. That is, it can be said to be one of the most suitable polymerization methods for obtaining the polycarboxylic acid-based copolymer contained in the additive for inorganic particles of the present invention.

The polycarboxylic acid-based copolymer is a structural unit (I) derived from the unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) and an unsaturated carboxylic acid represented by the general formula (2). It contains a structural unit (II) derived from the acid-based monomer (b).

The structural unit (I) derived from the unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) is specifically represented by the following formula.

The structural unit (II) derived from the unsaturated carboxylic acid-based monomer (b) represented by the general formula (2) is specifically represented by the following formula.

In the general formula (1) and the general formula (I), R ¹ and R ² represent the same or different hydrogen atoms or methyl groups.

In the general formula (1) and general formula (I), ^{R 2} is preferably a methyl group. By R ² is a methyl group, the effect of the present invention may be more expressed. Specifically, for example, in an additive for inorganic particles that can be used as an additive for cement to be added to a cement composition, the additive for inorganic particles necessary for achieving the desired fluidity in the cement composition. Provided is an additive for inorganic particles which can further reduce the amount used, reduce the viscosity of the cement composition as much as possible, sufficiently reduce the entrained air of the cement composition, and improve the compressive strength of the cement composition. can do.

In the general formula (1) and the general formula (I), R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group having 1 to 30 carbon atoms (aliphatic alkyl group and an alicyclic alkyl group), an alkenyl group having 1 to 30 carbon atoms, and a carbon atom number. Examples thereof include 1 to 30 alkynyl groups and 6 to 30 carbon atom number aromatic groups. R ³ is preferably a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, more preferably a hydrogen atom or It is a hydrocarbon group having 1 to 10 carbon atoms, and particularly preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. When R ³ is the above, the effect of the present invention can be more exhibited. Specifically, for example, in an additive for inorganic particles that can be used as an additive for cement to be added to a cement composition, the additive for inorganic particles necessary for achieving the desired fluidity in the cement composition. Provided is an additive for inorganic particles which can further reduce the amount used, reduce the viscosity of the cement composition as much as possible, sufficiently reduce the entrained air of the cement composition, and improve the compressive strength of the cement composition. can do.

In the general formula (1) and the general formula (I), AO is an oxyalkylene group having 2 to 18 carbon atoms, preferably an oxyalkylene group having 2 to 8 carbon atoms, and more preferably an oxyalkylene group having 2 to 8 carbon atoms. 2-4 oxyalkylene groups. When the AO is any two or more types selected from an oxyethylene group, an oxypropylene group, an oxybutylene group, an oxystyrene group, etc., the addition form of the AO is random addition, block addition, alternate addition, etc. It may be in any form of. In order to secure a balance between hydrophilicity and hydrophobicity, it is preferable that the oxyethylene group contains an oxyethylene group as an essential component, and 50 mol% or more of the total oxyalkylene group is an oxyethylene group. It is preferable that 90 mol% or more of the total oxyalkylene group is an oxyethylene group. If the oxyalkylene group is as described above, the cement composition is required to achieve the desired fluidity in the additive for inorganic particles that can be used as the cement additive to be added to the cement composition. Inorganic particles can further reduce the amount of additives used for inorganic particles, reduce the viscosity of the cement composition as much as possible, sufficiently reduce the entrainment air of the cement composition, and improve the compressive strength of the cement composition. Additives for particles can be provided.

In the general formula (1) and the general formula (I), n represents the average number of moles of oxyalkylene group represented by AO, which is 1 to 500, preferably 2 to 200. The number is more preferably 5 to 140, still more preferably 10 to 100, particularly preferably 15 to 70, and most preferably 20 to 55. When n is within the above range, it is an additive for inorganic particles that can be used as an additive for cement to be added to the cement composition, and for the inorganic particles necessary for achieving the desired fluidity in the cement composition. Additives for inorganic particles that can further reduce the amount of additives used, reduce the viscosity of the cement composition as much as possible, sufficiently reduce the entrainment air of the cement composition, and improve the compressive strength of the cement composition. Agents can be provided.

In the general formula (1) and the general formula (I), x is an integer of 0 to 2.

As the unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1), for example, an alkylene oxide having 2 to 8 carbon atoms is added to saturated aliphatic alcohols having 1 to 20 carbon atoms. The alkoxypolyalkylene glycols thus obtained and an esterified product of (meth) acrylic acid or crotonic acid; obtained by polymerizing an alkylene oxide having 2 to 18 carbon atoms on saturated aliphatic alcohols having 1 to 20 carbon atoms. Esterates of polyalkylene glycols and (meth) acrylic acid or crotonic acid; unsaturated aliphatic alcohols having 3 to 20 carbon atoms such as (meth) allyl alcohols, crotyl alcohols, and oleyl alcohols have carbon numbers. An esterified product of (meth) acrylic acid or crotonic acid with polyalkylene glycols obtained by adding 2 to 8 alkylene oxides; 3 to 3 carbon atoms of (meth) allyl alcohol, crotyl alcohol, oleyl alcohol and the like. An esterified product of polyalkylene glycols obtained by polymerizing an alkylene oxide having 2 to 18 carbon atoms on 20 unsaturated aliphatic alcohols with (meth) acrylic acid or crotonic acid; 3 carbon atoms such as cyclohexanol. An esterified product of (meth) acrylic acid or crotonic acid with polyalkylene glycols obtained by adding an alkylene oxide having 2 to 8 carbon atoms to 20 to 20 alicyclic alcohols; carbon number of cyclohexanol and the like. Polyalkylene glycols obtained by polymerizing an alkylene oxide having 2 to 18 carbon atoms on 3 to 20 alicyclic alcohols and an esterified product of (meth) acrylic acid or crotonic acid; 6 to 20 carbon atoms. A esterified product of (meth) acrylic acid or crotonic acid with polyalkylene glycols obtained by adding an alkylene oxide having 2 to 8 carbon atoms to aromatic alcohols; aromatic alcohols having 6 to 20 carbon atoms. Examples thereof include polyalkylene glycols obtained by polymerizing an alkylene oxide having 2 to 18 carbon atoms and an esterified product of (meth) acrylic acid or crotonic acid.

The unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) is preferably an alkoxypolyalkylene glycol of (meth) acrylic acid in that the effects of the present invention can be further exhibited. Esther. If the unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) is such, it is an additive for inorganic particles that can be used as an additive for cement to be added to a cement composition. The amount of the additive for inorganic particles required to achieve the desired fluidity in the cement composition can be further reduced, the viscosity of the cement composition can be reduced as much as possible, and the entrained air of the cement composition is sufficient. It is possible to provide an additive for inorganic particles which can be reduced and can improve the compressive strength of the cement composition.

The unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) may be of only one type or of two or more types.

In the general formula (2) and the general formula (II), R ^{4 to} R ⁶ represent the same or different hydrogen atom, methyl group, or − (CH ₂ ) _z COM group. The − (CH ₂ ) _z COM group may form anhydrate with the −COOX group or another − (CH ₂ ) _{z COM group.} z is an integer of 0 to 2.

M represents a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group.

X represents a hydrogen atom, a methyl group, an ethyl group, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group.

Examples of the unsaturated carboxylic acid-based monomer (b) represented by the general formula (2) include monocarboxylic acid-based monomers such as (meth) acrylic acid and crotonic acid, or salts thereof; maleic acid, Dicarboxylic acid-based monomers such as itaconic acid and fumaric acid or salts thereof; anhydrides of dicarboxylic acid-based monomers such as maleic acid, itaconic acid and fumaric acid or salts thereof; and the like. Examples of the salt here include alkali metal salts, alkaline earth metal salts, ammonium salts, organic ammonium salts, and organic amine salts.

Examples of the alkali metal salt include lithium salt, sodium salt, potassium salt and the like. Examples of the alkaline earth metal salt include calcium salt and magnesium salt.

Examples of the organic ammonium salt include methylammonium salt, ethylammonium salt, dimethylammonium salt, diethylammonium salt, trimethylammonium salt, triethylammonium salt and the like.

Examples of the organic amine salt include ethanolamine salt, diethanolamine salt, triethanolamine salt, monoisopropanolamine salt, diisopropanolamine salt, triisopropanolamine salt, hydroxyethyldiisopropanolamine salt, dihydroxyethylisopropanolamine salt, and tetrakis (dihydroxyethylisopropanolamine salt). Examples thereof include alkanolamine salts such as 2-hydroxypropyl) ethylenediamine and pentax (2-hydroxypropyl) diethylenetriamine. Among these, a diisopropanolamine salt, a triisopropanolamine salt, a hydroxyethyldiisopropanolamine salt, a tetrakis (2-hydroxypropyl) ethylenediamine salt, and a pentax (2-hydroxypropyl) diethylenetriamine salt are preferable, and more preferably. Triisopropanolamine salt and hydroxyethyldiisopropanolamine salt.

The unsaturated carboxylic acid-based monomer (b) represented by the general formula (2) is preferably (meth) acrylic acid, maleic acid, or maleic anhydride in that the effects of the present invention can be further exhibited. It is more preferably acrylic acid or methacrylic acid. If the unsaturated carboxylic acid-based monomer (b) represented by the general formula (2) is such, it is the additive for inorganic particles that can be used as an additive for cement to be added to the cement composition. The amount of the additive for inorganic particles required to achieve the desired fluidity in the cement composition can be further reduced, the viscosity of the cement composition can be reduced as much as possible, and the entrainment air of the cement composition can be sufficiently reduced. It is possible to provide an additive for inorganic particles which can improve the compressive strength of the cement composition.

The unsaturated carboxylic acid-based monomer (b) represented by the general formula (2) may be of only one type or of two or more types.

The content of the structural unit (I) in the polycarboxylic acid-based copolymer is preferably 30% by mass to 99% by mass, more preferably 40% by mass to 95% by mass, and further preferably 50% by mass. % To 90% by mass, particularly preferably 60% by mass to 85% by mass, and most preferably 70% by mass to 80% by mass. When the content ratio of the structural unit (I) in the polycarboxylic acid-based copolymer is within the above range, the cement composition can be used as an additive for cement to be added to the cement composition. The amount of the additive for inorganic particles required to achieve the desired fluidity can be further reduced, the viscosity of the cement composition can be reduced as much as possible, the entrainment air of the cement composition can be sufficiently reduced, and the cement composition can be sufficiently reduced. It is possible to provide an additive for inorganic particles that can improve the compressive strength of an object.

The content ratio of the structural unit (II) in the polycarboxylic acid-based copolymer is preferably 1% by mass to 70% by mass, more preferably 5% by mass to 60% by mass, and further preferably 8% by mass. % To 50% by mass, more preferably 11% by mass to 40% by mass, particularly preferably 16% by mass to 30% by mass, and most preferably 18% by mass to 30% by mass. When the content ratio of the structural unit (II) in the polycarboxylic acid-based copolymer is within the above range, the cement composition can be used as an additive for cement to be added to the cement composition. The amount of the additive for inorganic particles required to achieve the desired fluidity can be further reduced, the viscosity of the cement composition can be reduced as much as possible, the entrainment air of the cement composition can be sufficiently reduced, and the cement composition can be sufficiently reduced. It is possible to provide an additive for inorganic particles that can improve the compressive strength of an object.

The total content of the structural unit (I) and the structural unit (II) in the polycarboxylic acid-based copolymer is preferably 50% by mass to 100% by mass, and more preferably 70% by mass to 100% by mass. %, More preferably 90% by mass to 100% by mass, particularly preferably 95% by mass to 100% by mass, and most preferably substantially 100% by mass. For inorganic particles that can be used as an additive for cement to be added to a cement composition if the total content ratio of the structural unit (I) and the structural unit (II) in the polycarboxylic acid-based copolymer is within the above range. In the additive, the amount of the additive for inorganic particles required to achieve the desired fluidity in the cement composition can be further reduced, the viscosity of the cement composition can be reduced as much as possible, and the cement composition can be entrained. It is possible to provide an additive for inorganic particles which can sufficiently reduce air and improve the compressive strength of the cement composition.

In addition to the structural unit (I) and the structural unit (II), the polycarboxylic acid-based copolymer may contain a structural unit (III) derived from another monomer (c).

The monomer (c) is a monomer copolymerizable with the monomer (a) and the monomer (b). The monomer (c) may be only one kind or two or more kinds.

Examples of the monomer (c) include hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; unsaturated monos such as methyl (meth) acrylate and glycidyl (meth) acrylate. Esters of carboxylic acids and alcohols with 1 to 30 carbon atoms; (anhydrous) Half esters of unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and alcohols with 1 to 30 carbon atoms; (anhydrous) ) Diesters of unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and alcohols having 1 to 30 carbon atoms; halfamides of the unsaturated dicarboxylic acids and amines having 1 to 30 carbon atoms; Diamides of unsaturated dicarboxylic acids and amines with 1 to 30 carbon atoms; alkyl (poly) alkylene glycols obtained by adding 1 to 500 mol of alkylene oxides with 2 to 18 carbon atoms to the alcohols and amines and the unsaturated compounds. Half esters with dicarboxylic acids; Diesters of alkyl (poly) alkylene glycols obtained by adding 1 to 500 mol of alkylene oxides having 2 to 18 carbon atoms to the alcohols and amines and unsaturated dicarboxylic acids; Half esters of dicarboxylic acids and glycols having 2 to 18 carbon atoms or polyalkylene glycols having 2 to 500 additional moles of these glycols; the unsaturated dicarboxylic acids and glycols having 2 to 18 carbon atoms or glycols thereof. Diesters with polyalkylene glycols with 2 to 500 additional moles; halfamides with maleamide acid and glycols with 2 to 18 carbon atoms or polyalkylene glycols with 2 to 500 added moles of these glycols; ) (Poly) alkylene glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate and (poly) propylene glycol di (meth) acrylate; hexanediol di (meth) acrylate, trimethyl propanthry (meth) acrylate and the like. Polyfunctional (meth) acrylates; (poly) alkylene glycol dimalate such as polyethylene glycol dimalate; non-vinyl sulfonate, (meth) allylsulfonate, 2-methylpropanesulfonic acid (meth) acrylamide, styrenesulfonic acid and the like Saturated sulfonic acids (salts); unsaturated monocarboxylic acids such as methyl (meth) acrylamide and 1 carbon atom Amides with ~ 30 amines; vinyl aromatics such as styrene, α-methylstyrene, vinyltoluene; alcandiol mono (meth) acrylates such as 1,4-butanediol mono (meth) acrylate; butadiene, isoprene Dienes such as; unsaturated amides such as (meth) acrylic (alkyl) amides, N-methylol (meth) acrylamides, N, N-dimethyl (meth) acrylamides; unsaturated cyanides such as (meth) acrylonitrile; acetic acid. Unsaturated esters such as vinyl; unsaturated amines such as (meth) aminoethyl acrylate, dimethylaminoethyl (meth) acrylate, vinylpyridine; divinyl aromatics such as divinylbenzene; isoprenyl alcohol, (meth) Allyls such as allyl alcohols and glycidyl (meth) allyl ethers; (alkoxy) polyalkylene glycol vinyl ethers such as (methoxy) polyethylene glycol monovinyl ethers; (meth) allyl ethers such as (methoxy) polyethylene glycol mono (meth) allyl ethers. Kind: Ester oxide adducts of isoprenyl alcohols, ethylene oxide adducts of (meth) allyl alcohols, ethylene oxide adducts of vinyl alcohols such as hydroxybutyl vinyl alcohols, and alkylene oxide adducts to unsaturated alcohols having 2 to 10 carbon atoms. ; And so on.

The content of the structural unit (III) in the polycarboxylic acid-based copolymer is preferably 0% by mass to 50% by mass, more preferably 0% by mass to 40% by mass, and further preferably 0% by mass. % To 30% by mass, particularly preferably 0% by mass to 20% by mass, and most preferably 0% by mass to 10% by mass. When the content ratio of the structural unit (III) in the polycarboxylic acid-based copolymer is within the above range, the cement composition can be used as an additive for cement to be added to the cement composition. The amount of the additive for inorganic particles required to achieve the desired fluidity can be further reduced, the viscosity of the cement composition can be reduced as much as possible, the entrainment air of the cement composition can be sufficiently reduced, and the cement composition can be sufficiently reduced. It is possible to provide an additive for inorganic particles that can improve the compressive strength of an object.

The content ratio of the structural unit (I), the content ratio of the structural unit (II), the total content ratio of the structural unit (I) and the structural unit (II) in the polycarboxylic acid-based copolymer, the polycarboxylic acid-based The content ratio of the structural unit (III) in the copolymer can be known, for example, by various structural analyzes (for example, NMR) of the polycarboxylic acid-based copolymer. Further, a structural unit derived from the various monomers calculated based on the amount of the various monomers used in producing the polycarboxylic acid-based copolymer without performing various structural analyzes as described above. The content ratio of the structural unit (I), the content ratio of the structural unit (II), and the total content ratio of the structural unit (I) and the structural unit (II) in the polycarboxylic acid-based copolymer. , The content ratio of the structural unit (III) in the polycarboxylic acid-based copolymer may be used. That is, for example, the unsaturated polyalkylene glycol-based monomer (a) and the unsaturated carboxylic acid-based monomer (b) in all the monomer components used in producing the polycarboxylic acid-based copolymer. The content ratio of the total mass of the above may be treated as the total content ratio of the structural unit (I) and the structural unit (II) in the polycarboxylic acid-based copolymer.

When determining the content ratio of the structural unit in the polycarboxylic acid-based copolymer, if the structural unit has a salt of a carboxyl group, the calculation is performed by converting all the acid portions of the carboxyl group into sodium salts.

The polyethylene glycol-equivalent weight average molecular weight Mw obtained by gel permeation chromatography of the polycarboxylic acid-based copolymer is preferably 50,000 or less, more preferably 2000 to 40,000, and further preferably 3,000 to 30,000. It is more preferably 4000 to 26000, particularly preferably 5000 to 18000, and most preferably 5500 to 12000. If the weight average molecular weight Mw in terms of polyethylene glycol obtained by gel permeation chromatography of a polycarboxylic acid-based copolymer is within the above range, it can be used as an additive for cement to be added to a cement composition. In the agent, the amount of the additive for inorganic particles required to achieve the desired fluidity in the cement composition can be further reduced, the viscosity of the cement composition can be reduced as much as possible, and the entrainment air of the cement composition can be reduced. It is possible to provide an additive for inorganic particles, which can sufficiently reduce the amount of the cement composition and improve the compressive strength of the cement composition.

However, as will be described later, when the polycarboxylic acid-based copolymer is used in combination with an antifoaming agent, the weight average in terms of polyethylene glycol obtained by gel permeation chromatography of the polycarboxylic acid-based copolymer. The molecular weight Mw is not limited to the above-mentioned preferable range, and for example, even if the weight average molecular weight exceeds 50,000, the effect of the present invention can be exhibited.

The polycarboxylic acid-based copolymer has a dispersity (Mw / Mn) of 1.00 to 1.25, preferably 1.00 to 1.23, and more preferably 1.00 to 1.20. It is more preferably 1.00 to 1.17, particularly preferably 1.00 to 1.14, and most preferably 1.00 to 1.11. If the dispersibility (Mw / Mn) is very low as described above, the desired fluidity of the cement composition in the additive for inorganic particles that can be used as the additive for cement to be added to the cement composition. The amount of the additive for inorganic particles required to achieve the above can be further reduced, the viscosity of the cement composition can be reduced as much as possible, the entrainment air of the cement composition can be sufficiently reduced, and the compressive strength of the cement composition can be sufficiently reduced. It is possible to provide an additive for inorganic particles which can improve the above.

One preferred embodiment of the polycarboxylic acid-based copolymer is that the weight average molecular weight Mw in terms of polyethylene glycol obtained by gel permeation chromatography of the polycarboxylic acid-based copolymer is 50,000 or less, and the polycarboxylic acid-based copolymer is used. The dispersity Mw / Mn of the polycarboxylic acid-based copolymer is 1.00 to 1.25. As described above, the weight average molecular weight Mw in terms of polyethylene glycol obtained by gel permeation chromatography of the polycarboxylic acid-based copolymer is low, and the molecular weight distribution of the polycarboxylic acid-based copolymer is very narrow. As a result, in the additive for inorganic particles that can be used as an additive for cement to be added to the cement composition, the amount of the additive for inorganic particles required to achieve the desired fluidity in the cement composition is further reduced. It is possible to provide an additive for inorganic particles which can reduce the viscosity of the cement composition as much as possible, sufficiently reduce the entrained air of the cement composition, and can improve the compressive strength of the cement composition.

The polycarboxylic acid-based copolymer is obtained by living polymerization, and is preferably obtained by RAFT (Reversible Addition-Fragmentation Chain Transfer) polymerization. If the polycarboxylic acid-based copolymer is obtained by RAFT polymerization, the weight average molecular weight Mw in terms of polyethylene glycol obtained by gel permeation chromatography of the polycarboxylic acid-based copolymer is preferable. It is possible to reduce the dispersity Mw / Mn calculated by the ratio of the average molecular weight Mn. Then, in the additive for inorganic particles that can be used as the additive for cement to be added to the cement composition, the amount of the additive for inorganic particles required to achieve the desired fluidity in the cement composition is further reduced. It is possible to provide an additive for inorganic particles capable of reducing the viscosity of the cement composition as much as possible, sufficiently reducing the entrained air of the cement composition, and improving the compressive strength of the cement composition.

If the polycarboxylic acid-based copolymer is obtained by living polymerization (preferably RAFT polymerization), the dispersity of the polycarboxylic acid-based copolymer can be lowered as described above.

The RAFT agent used in RAFT polymerization that can be used to obtain polycarboxylic acid-based copolymers includes a RAFT active site that serves as a cleavage point and several substituents that bind to this active site and change the activity of the RAFT agent. Consists of. The RAFT active site preferably has at least one functional group selected from dithioester, trithiocarbonate, dithiocarbamate and xanthan. That is, the polycarboxylic acid-based copolymer contained in the additive for inorganic particles of the present invention preferably has a structure derived from at least one selected from dithioester, trithiocarbonate, dithiocarbamate, and xantane at the polymer terminal. Have in. In an additive for inorganic particles that can be used as an additive for cement to be added to a cement composition by having such a structure at the end of the polymer, the inorganic necessary for achieving the desired fluidity in the cement composition. Inorganic particles that can further reduce the amount of particle additives used, reduce the viscosity of the cement composition as much as possible, sufficiently reduce the entrainment air of the cement composition, and improve the compressive strength of the cement composition. Additives can be provided. Having such a structure at the end of the polymer can be proved, for example, by the MALDI-TOF method. The MALDI-TOF method is an abbreviation for a matrix-assisted laser desorption / ionization method, and is one of known mass spectrometry methods.

As the RAFT active site, the RAFT agent containing a dithioester structure has a general formula (3), the RAFT agent containing a trithiocarbonate structure has a general formula (4), and the RAFT agent having a dithiocarbamate structure has a general formula (5), xanthan. The RAFT agent containing a structure is represented by the general formula (6).
_{Z 1} , Z ₂ , Z ₃ , Z ₄ , Z ₅ , Y ₁ , Y ₂ , Y ₃ , and Y _{4 in the} formulas (3) to (6) are substituents that change the activity of the RAFT agent.

As the substituents Z ₁ , Z ₂ , Z ₃ , Z ₄ , and Z ₅ , a hydrogen atom or a hydrocarbon group composed of an alkyl group, an aryl group, or the like is preferable. The carbon chain of these substituents may be a straight chain or a branched chain, and may have a cyclic structure or an unsaturated bond in the middle or at the end. Further, these substituents may contain complex atoms such as N, O, Si, P and S in the carbon chain, and N, O, Si, P, S and halogen atoms (N, O, Si, P, S and halogen atoms on the carbon chain ( It may have any substituent including F, Cl, Br, I) and the like. From the viewpoint of hydrophilicity, these substituents are hydroxyl group, amino group, carbonyl group, carboxyl group, amide group, cyano group, carbamoyl group, oxo acid group (sulfon group, phosphon group, phosphine group, etc.) and oxo acid. Those having a polar functional group such as an ester are more preferable, and those having 15 or less carbon atoms per polar functional group are further preferable. Specifically, methyl group, ethyl group, propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-dodecyl group, Isopropyl group, isobutyl group, tert-butyl group, neopentyl group, 2-ethylhexyl group, cyclopentyl group, cyclohexyl group, vinyl group, allyl group, isoprenyl group, phenyl group, benzyl group, and functional groups thereof. Examples thereof include a substituent formed by substituting one or more arbitrary hydrogen atoms in the above with the above-mentioned polar functional group or alkyl group, a substituent formed by inserting the above-mentioned complex atom between arbitrary atoms, and the like.

Z ₃ and Z ₄ may be covalently linked, in which case they have a cyclic structure containing the N atom of the RAFT active site. Specific examples thereof include 4-chloro-3,5-dimethylpyrazole groups.

As the substituents Y ₁ , Y ₂ , Y ₃ and Y ₄ , a hydrogen atom or a hydrocarbon group composed of an alkyl group or an aryl group is preferable. The carbon chain of these substituents may be a straight chain or a branched chain, and may have a cyclic structure or an unsaturated bond in the middle or at the end. Further, these substituents may contain complex atoms such as N, O, Si, P and S in the carbon chain, and N, O, Si, P, S and halogen atoms (N, O, Si, P, S and halogen atoms on the carbon chain ( It may have any substituent including F, Cl, Br, I) and the like. From the viewpoint of hydrophilicity, these substituents are hydroxyl group, amino group, carbonyl group, carboxyl group, amide group, cyano group, carbamoyl group, oxo acid group (sulfon group, phosphon group, phosphine group, etc.) and oxo acid. Those having a polar functional group such as an ester are more preferable, and those having 15 or less carbon atoms per polar functional group are further preferable. Further, it is preferable that these substituents have a secondary or tertiary carbon atom at the connection end with the RAFT active site S atom. Specifically, methyl group, ethyl group, propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-dodecyl group, Isopropyl group, isobutyl group, tert-butyl group, neopentyl group, 2-ethylhexyl group, cyclopentyl group, cyclohexyl group, vinyl group, allyl group, isoprenyl group, phenyl group, benzyl group, and functional groups thereof. Examples thereof include a substituent formed by substituting one or more arbitrary hydrogen atoms in the above with the above-mentioned polar functional group or alkyl group, a substituent formed by inserting the above-mentioned complex atom between arbitrary atoms, and the like.

In the general formula (4), Z ₂ and Y ₂ may be the same substituent, but those in which Z ₂ and Y ₂ have different substituents are preferable, and the substituent on the carbon atom bonded to the RAFT active site is preferable. Those having different types are more preferable, and those having a different number of bonds between the RAFT active site and the hydrogen atom of the carbon atom bonded to the RAFT active site are further preferable. If the structure is symmetrical or similar to the left and right, the activities of the S-Z ₂ bond and the SY ₂ bond of the RAFT active site are similar, and the polymerization reaction occurs on both sides of the RAFT active site, which is difficult to control. become. When Z ₂ and Y ₂ have different substituents, the polymerization proceeds only on one side of the RAFT active site, and it is easy to control the structure of the polymer.

Z ₁ , Z ₂ , Z ₃ , Z ₄ , Z ₅ , Y ₁ , Y ₂ , Y ₃ , Y ₄ may contain one or more other RAFT active sites.

As the RAFT agent that can be used to obtain a polycarboxylic acid-based copolymer, those having a dithiocarbonate structure or a trithiocarbonate structure at the RAFT active site are particularly preferable. When using a RAFT agent having a dithiocarbonate structure RAFT active site for polymerization, it is preferable to contain a highly polar functional group at least at one structure of its substituents Z ₁ and Y _1. When a RAFT agent having a trithiocarbonate structure in the RAFT active site is used for polymerization, it is preferable that at least one of the _{substituents Z 2} and Y _{2 contains a highly polar functional group.} Since the RAFT agent having such a substituent has a relatively high molecular polarity, it is easy to disperse uniformly in a polar solvent, particularly in water, and a polymer having a lower dispersity can be obtained. Specifically, 4-cyano-4- (thiobenzoylthio) pentanoic acid, 4-cyano-4-thiothiopropylsulfanylpentanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl) sulfanyl] pentanoic acid, 4-[(2-carboxyethyl sulfanylthiocarbonyl) sulfanyl] -4-cyanopentanoic acid, 2-{[(2-carboxyethyl) sulfanylthiocarbonyl] sulfanyl} propanoic acid and the like are preferable.

The polycarboxylic acid-based copolymer preferably has a structure derived from at least one selected from dithioester, trithiocarbonate, dithiocarbamate, and xantane at the polymer terminal. The polycarboxylic acid-based copolymer more preferably has a structure derived from at least one selected from trithiocarbonate and dithiocarbamate at the polymer terminal. In an additive for inorganic particles that can be used as an additive for cement to be added to a cement composition by having such a structure at the end of the polymer, the inorganic necessary for achieving the desired fluidity in the cement composition. Inorganic particles that can further reduce the amount of particle additives used, reduce the viscosity of the cement composition as much as possible, sufficiently reduce the entrainment air of the cement composition, and improve the compressive strength of the cement composition. Additives can be provided. Having such a structure at the end of the polymer can be proved, for example, by the MALDI-TOF method. The MALDI-TOF method is an abbreviation for a matrix-assisted laser desorption / ionization method, and is one of known mass spectrometry methods.

As the conditions for RAFT polymerization that can be adopted to obtain the polycarboxylic acid-based copolymer, any appropriate conditions can be adopted as long as the effects of the present invention are not impaired.

As the conditions for RAFT polymerization, for example, the following conditions are preferable.

(solvent)
The polymerization step (copolymerization step) for obtaining the polycarboxylic acid-based copolymer can be carried out by a usual method such as solution polymerization or bulk polymerization. Solution polymerization can be carried out either in batches or continuously. Any suitable solvent may be used in this case, for example, water; alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol; aromatic or aliphatic carbonized products such as benzene, toluene, xylene, cyclohexane, n-hexane. Examples thereof include hydrogen; ester compounds such as ethyl acetate; ketone compounds such as acetone and methyl ethyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane. Above all, from the viewpoint of the solubility of the raw material monomer and the obtained polymer, it is preferable to use at least one selected from the group consisting of water and a lower alcohol having 1 to 4 carbon atoms, and among them, water is a solvent removing step. Is more preferable in that the above can be omitted.

(Polymerization concentration)
The amount of all the monomer components used in the RAFT polymerization is preferably 15% by mass or more, more preferably 20% by mass to 90% by mass, still more preferably, with respect to all the raw materials including other raw materials. Is 25% by mass to 80% by mass, particularly preferably 30% by mass to 60% by mass, and most preferably 35% by mass to 55% by mass. If the amount of all monomer components used in RAFT polymerization is within the above range, the polymerization rate is improved, productivity is improved, and side reactions such as double molecule termination reaction are unlikely to occur.

(Amount of RAFT agent added)
In RAFT polymerization, the ratio of the number of moles of RAFT agent added to the number of moles of all monomers is preferably 1/1000 to 1/5, more preferably 1/500 to 1/10. It is more preferably 1/250 to 1/15, particularly preferably 1/100 to 1/20, and most preferably 1/50 to 1/25. When the ratio of the number of moles of the RAFT agent added to the number of moles of all the monomers is within the above range, it is desired for the cement composition in the additive for inorganic particles that can be used as the additive for cement to be added to the cement composition. The amount of the additive for inorganic particles required to achieve the fluidity of the cement composition can be further reduced, the viscosity of the cement composition can be reduced as much as possible, the entrainment air of the cement composition can be sufficiently reduced, and the cement composition can be sufficiently reduced. It is possible to provide an additive for inorganic particles capable of improving the compression strength of the cement.

(Type of polymerization initiator)
As the polymerization initiator for RAFT polymerization, any suitable polymerization initiator can be adopted. Examples of such a polymerization initiator include azo-based initiators and peroxides. Specific examples of the azo-based initiator include 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (trade name "VA-044" manufactured by Wako Junyaku Kogyo Co., Ltd.). , 2'-Azobisisobuty [2- (imidazolin-2-yl) propane] disulfate dihydrate (trade name "VA-046B" manufactured by Wako Junyaku Kogyo Co., Ltd.), 2, 2'-azobis [2- (2-imidazolin-2-yl) propane] (trade name "VA-061" manufactured by Wako Pure Chemical Industries, Ltd., etc.), 2,2'-azobis (2-methylpropionamidine) Dihydrochloride (trade name "V-50" manufactured by Wako Junyaku Kogyo Co., Ltd., etc.), 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] n hydrate (Japanese (Product name "VA-057", etc. manufactured by Kojunyaku Kogyo Co., Ltd.), 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide] (trade name manufactured by Wako Junyaku Kogyo Co., Ltd.) "VA-086" etc.), 4,4'-azobis (4-cyanovaleric acid) (trade name "V-501" manufactured by Wako Pure Chemical Industries Co., Ltd.), 2,2'-azobis (4-methoxy) -2,4-dimethylvaleronitrile) (trade name "V-70" manufactured by Wako Pure Chemical Industries, Ltd., etc.), 2,2'-azobis (2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, Ltd.) (Product name "V-65", etc.), 2,2'-azobis (isobutyronitrile) (AIBN), 2,2'-azobis (2-methylbutyronitrile) (manufactured by Wako Pure Chemical Industries, Ltd.) (Product name "V-59", etc.), 1,1'-azobis (cyclohexane-1-carbobisisobuty) (trade name "V-40", etc. manufactured by Wako Pure Chemical Industries Co., Ltd.), 2,2'-azobis [N- (2-propenyl) -2-methylpropionamide] (trade name "VF-096" manufactured by Wako Pure Chemical Industries, Ltd., etc.), 2,2'-azobis (N-butyl-2-methylpropionamide) ) (Product name "VAm-110" manufactured by Wako Junyaku Kogyo Co., Ltd.), 2,2'-azobis (isobutyric acid) dimethyl (trade name "V-601" manufactured by Wako Junyaku Kogyo Co., Ltd.), etc. Can be mentioned. Examples of peroxides include hydrogen peroxide, benzoyl peroxide, tertiary butyl hydroperoxide (trade name "Perbutyl H-69" manufactured by Nippon Oil & Fat Co., Ltd., etc.), 1,1,3,3-tetramethylbutylhydroperoxide. (Product name "Perocta H" manufactured by Nippon Oil & Fat Co., Ltd., etc.) and the like.

(Ratio of RAFT agent and polymerization initiator)
In RAFT polymerization, the polymerization reaction is started with a small amount of polymerization initiator. If the amount of the polymerization initiator is too small, the polymerization reaction will not proceed well because the initial radical concentration is low, and conversely, if the amount is too large, the initial radical concentration will increase and free radical polymerization will proceed at the same time, resulting in a copolymer with a narrow degree of dispersion. Cannot be obtained. For a polymerization initiator such as hydrogen peroxide, in which only one radical is generated from the cleavage of one molecule of the polymerization initiator, the ratio of the number of moles of the polymerization initiator to the number of moles of the RAFT agent is preferably 20 mol% to 80 mol. %, More preferably 30 mol% to 70 mol%, still more preferably 35 mol% to 65 mol%, particularly preferably 40 mol% to 60 mol%, and most preferably 45 mol% to. It is 55 mol%. When an azo-based initiator such as the trade name "V-50" manufactured by Wako Pure Chemical Industries, Ltd. is used, two radicals are generated from the cleavage of one molecule of the polymerization initiator, so that the number of moles of the RAFT agent is increased. The ratio of the number of moles of the polymerization initiator is preferably 10 mol% to 40 mol%, more preferably 15 mol% to 35 mol%, still more preferably 17 mol% to 32 mol%, and particularly. It is preferably 20 mol% to 30 mol%, and most preferably 22 mol% to 28 mol%.

(Polymerization temperature)
In RAFT polymerization, the polymerization temperature is appropriately determined by the polymerization method, solvent, polymerization initiator, chain transfer agent, etc. used, but the lower limit is preferably 0 ° C. or higher, more preferably 30 ° C. or higher, and further. The temperature is preferably 50 ° C. or higher, and the upper limit is preferably 150 ° C. or lower, more preferably 120 ° C. or lower, and further preferably 100 ° C. or lower.

(Monomer addition method)
As a method of charging each monomer into the reaction vessel, a method of initially charging the entire amount into the reaction vessel, a method of dividing or continuously charging the entire amount into the reaction vessel, and a method of initially charging a part into the reaction vessel and the rest. Can be divided or continuously charged into the reaction vessel. As a suitable charging method, specifically, a method of continuously charging the monomer (a) and all of the monomer (b) into the reaction vessel, and a method of continuously charging a part of the monomer (a) into the reaction vessel. A method in which the remainder of the monomer (a) and the entire monomer (b) are continuously charged into the reaction vessel at the initial stage, a part of the monomer (a) and one of the monomers (b). Examples thereof include a method in which the portions are initially charged into the reaction vessel, and the remainder of the monomer (a) and the remainder of the monomer (b) are alternately charged into the reaction vessel in several divided portions. Further, by continuously or stepwise changing the charging rate of each monomer into the reaction vessel during the reaction, the charging mass ratio of each monomer per unit time is continuously or stepwise changed to carry out polypoly. The polymer may be polymerized so that the ratio of the structural unit (I) and the structural unit (II) in the carboxylic acid-based copolymer changes continuously or stepwise in the same polymer chain. The polymerization initiator and the chain transfer agent may be charged into the reaction vessel from the beginning, may be dropped into the reaction vessel, or may be combined depending on the purpose.

(Dissolved oxygen concentration)
In RAFT polymerization, in order to obtain a polycarboxylic acid-based copolymer having a predetermined molecular weight with good reproducibility, it is necessary to allow the copolymerization reaction to proceed stably. The dissolved oxygen concentration at 25 ° C. is preferably 5 ppm or less. The dissolved oxygen concentration is more preferably 0.01 ppm to 4 ppm, further preferably 0.01 ppm to 2 ppm, and particularly preferably 0.01 ppm to 1 ppm. When nitrogen substitution or the like is performed after adding the monomer to the solvent, it is preferable that the dissolved oxygen concentration of the system including the monomer is within the above range. The dissolved oxygen concentration of the solvent may be adjusted in a polymerization reaction tank, or a solvent having a dissolved oxygen amount adjusted in advance may be used. Examples of the method for expelling oxygen in the solvent include the following methods (1) to (5).
(1) After pressure-filling the closed container containing the solvent with an inert gas such as nitrogen, the pressure inside the closed container is lowered to lower the partial pressure of oxygen in the solvent. The pressure in the closed container may be reduced under a nitrogen stream.
(2) The liquid phase portion is vigorously stirred for a long time while the gas phase portion in the container containing the solvent is replaced with an inert gas such as nitrogen.
(3) The solvent contained in the container is bubbled with an inert gas such as nitrogen for a long time.
(4) After boiling the solvent once, it is cooled under the atmosphere of an inert gas such as nitrogen.
(5) A static mixer is installed in the middle of the pipe, and an inert gas such as nitrogen is mixed in the pipe that transfers the solvent to the polymerization reaction tank.

(PH adjustment)
The obtained polycarboxylic acid-based copolymer can be used as it is as an essential component of the cement admixture of the present invention, but it is preferable to adjust the pH to 5 or more from the viewpoint of handleability. However, in order to improve the polymerization rate, it is preferable to carry out the copolymerization reaction at a pH of less than 5 and adjust the pH to 5 or more after the copolymerization. The pH is adjusted by adjusting the pH to one of alkaline substances such as monovalent metals such as sodium hydroxide, potassium hydroxide and calcium hydroxide, and inorganic salts such as hydroxides and carbonates of divalent metals; ammonia; organic amines; It can be performed using two or more types. Further, after the reaction is completed, the concentration can be adjusted if necessary.

When the polycarboxylic acid-based copolymer is obtained by RAFT polymerization, the structure of the polycarboxylic acid-based copolymer is derived from the RAFT agent used in the polymerization at the end of the main chain immediately after the polymerization. It has the characteristic that the structure (the RAFT active site and the substituent bonded to the S atom of the active site) always remains.

The concentration of the produced polycarboxylic acid-based copolymer can be adjusted as necessary with respect to the solution obtained by the production.

The produced polycarboxylic acid-based copolymer may be used as it is in the form of a solution, or may be powdered and used.

A-2. Defoaming agent As the defoaming agent, any suitable defoaming agent can be used. According to one embodiment of the present invention (the above-mentioned embodiment (ii)), a specific polycarboxylic acid-based copolymer as described above and a defoaming agent can be used in combination in a cement composition. It is possible to prevent entrainment of excess air, and it is possible to obtain a cement composition having excellent compressive strength and having a predetermined compressive strength regardless of the type of defoaming agent. In addition, it is possible to prevent an increase in viscosity and a decrease in fluidity due to excessive entrainment of air.

Examples of the defoaming agent include an oxyalkylene-based defoaming agent and a defoaming agent other than the oxyalkylene-based defoaming agent.

Examples of the oxyalkylene-based defoaming agent include polyoxyalkylenes such as (poly) oxyethylene (poly) oxypropylene adduct; polyoxyalkylene alkyl ethers such as diethylene glycol heptyl ether; polyoxyalkylene acetylene ethers; Poly) Oxyalkylene fatty acid esters; Polyoxyalkylene sorbitan fatty acid esters; Polyoxyalkylene alkyl (aryl) ether sulfate esters; Polyoxyalkylene alkyl phosphate esters; Polyoxypropylene polyoxyethylene laurylamine (propylene oxide 1- Poly such as 20 mol addition, ethylene oxide 1 to 20 mol addition, etc.), amine derived from fatty acid obtained from hardened beef fat to which alkylene oxide is added (propylene oxide 1 to 20 mol addition, ethylene oxide 1 to 20 mol addition, etc.) Examples thereof include oxyalkylene alkylamines; polyoxyalkylene amides and the like;

Examples of defoamers other than oxyalkylene-based defoamers include mineral oil-based, oil-based, fatty acid-based, fatty acid ester-based, alcohol-based, amide-based, phosphoric acid ester-based, metal soap-based, and silicone-based defoaming agents. Be done.

When a defoaming agent is used, the content ratio of the defoaming agent in the solid content of the additive for inorganic particles is preferably 0.02% by mass to 20% by mass, more preferably 0.05% by mass or more. It is 10% by mass, more preferably 0.08% by mass to 6% by mass, and particularly preferably 0.1% by mass to 4% by mass.

When a defoaming agent is used, the total content ratio of the polycarboxylic acid-based copolymer and the defoaming agent in the solid content of the additive for inorganic particles is preferably 50% by mass to 100% by mass. It is more preferably 75% by mass to 100% by mass, further preferably 90% by mass to 100% by mass, and particularly preferably 95% by mass to 100% by mass.

When a defoaming agent is used, the content ratio of the defoaming agent to the polycarboxylic acid-based copolymer in the additive for inorganic particles is the solid content, preferably 0.001% by mass to 120% by mass. It is more preferably 0.01% by mass to 60% by mass, further preferably 0.1% by mass to 10% by mass, and particularly preferably 0.5% by mass to 5% by mass.

A-3. Additional Ingredients Additives for inorganic particles may contain any suitable additional ingredients. As additional components, for example, a sulfonic acid-based dispersant having a sulfonic acid group in a molecule that can be used as a cement admixture, a phosphoric acid-based dispersant having a phosphoric acid group in the molecule, and the polycarboxylic acid-based agent according to A-1. Polycarboxylic acid dispersants other than copolymers, water-soluble polymer substances, polymer emulsions, curing retarders, fast-strengthening agents / accelerators, AE agents, crack reducing agents, surfactants, waterproofing materials, rust preventives , Cement wetting agent, thickener, separation reducing agent, flocculant, drying shrinkage reducing agent, strength enhancing agent, self-leveling agent, coloring agent, antifungal agent and the like.

Examples of the sulfonic acid-based dispersant include polyalkylaryl sulfonate-based sulfonic acid-based dispersants such as naphthalene sulfonic acid formaldehyde condensate, methylnaphthalene sulfonic acid formaldehyde condensate, and anthracene sulfonic acid formaldehyde condensate; melamine sulfonic acid. Melamine formalin resin sulfonate-based sulfonic acid-based dispersants such as formaldehyde condensates; aromatic aminosulfonate-based sulfonic acid-based dispersants such as aminoaryl sulfonic acid-phenol-formaldehyde condensates; lignin sulfonates, Examples thereof include a lignin sulfonate-based sulfonic acid-based dispersant such as a modified lignin sulfonate; a polystyrene sulfonate-based sulfonic acid-based dispersant; and the like.

As the phosphoric acid-based dispersant, a formalin condensate of an aromatic phosphoric acid compound such as 2-phenoxyethyl phosphate and an aromatic polyalkylene glycol compound such as phenoxypolyethylene glycol; a phosphoric acid ester of hydroxyethyl (meth) acrylate. Examples thereof include a copolymer of a hydroxyalkyl (meth) acrylate-based phosphoric acid compound such as (methoxy) polyethylene glycol (meth) acrylate and (alkoxy) polyalkylene glycol (meth) acrylate such as (methoxy) polyethylene glycol (meth) acrylate.

Examples of the water-soluble polymer substance include nonionic cellulose ethers such as methyl cellulose, ethyl cellulose and carboxymethyl cellulose; polysaccharides produced by microbial fermentation such as yeast glucan, xanthan gum and β-1.3 glucan; polyethylene glycol. Polyoxyalkylene glycols and the like; polyacrylamide and the like can be mentioned.

Examples of the polymer emulsion include copolymers of various vinyl monomers such as alkyl (meth) acrylate.

Examples of the curing retarder include oxycarboxylic acids such as gluconic acid, glucoheptonic acid, arabonic acid, malic acid and citric acid or salts thereof; sugars and sugar alcohols; polyhydric alcohols such as glycerin; aminotri (methylenephosphonic acid) and the like. Phosphoric acid and its derivatives thereof.

Examples of the fast-strengthening agent / accelerator include soluble calcium salts such as calcium chloride, calcium nitrite, calcium nitrate, calcium bromide and calcium iodide; chlorides such as iron chloride and magnesium chloride; sulfates; potassium hydroxide. ; Sodium hydroxide; carbonate; thiosulfate; formates such as formic acid and calcium formate;

Examples of the AE agent include resin soap, saturated or unsaturated fatty acids, sodium hydroxystearate, lauryl sulfate, ABS (alkylbenzene sulfonic acid), alkanesulfonate, polyoxyethylene alkyl (phenyl) ether, and polyoxyethylene alkyl (phenyl). Examples thereof include ether sulfate ester or a salt thereof, polyoxyethylene alkyl (phenyl) ether phosphate ester or a salt thereof, protein material, alkenyl sulfosuccinic acid, α-olefin sulfonate and the like.

Examples of the surfactant include various anionic surfactants; various cationic surfactants such as alkyltrimethylammonium chloride; various nonionic surfactants; various amphoteric surfactants and the like.

Examples of the waterproofing agent include fatty acids (salts), fatty acid esters, fats and oils, silicones, paraffins, asphalts, waxes and the like.

Examples of the rust preventive include nitrite, phosphate, zinc oxide and the like.

Examples of the crack reducing agent include polyoxyalkyl ethers and the like.

The content ratio of the additional component in the solid content of the additive for inorganic particles is preferably 0% by mass to 50% by mass, more preferably 0% by mass to 10% by mass, and further preferably 0% by mass to 1%. It is by mass, particularly preferably 0% by mass to 0.1% by mass.

The types, combinations, blending amounts, etc. of additional components in the additive for inorganic particles can be appropriately set according to the purpose.

B. Additives for Cement In one embodiment, the additive for inorganic particles can be an additive for cement.

C. Cement Composition One embodiment of the cement composition of the present invention comprises the additive for inorganic particles according to Item A, cement, and the like. The additive for inorganic particles according to Item A, which can be adopted here, is the additive for inorganic particles of the above-mentioned embodiment (i) or the additive for inorganic particles of the above-mentioned embodiment (ii).

Another embodiment of the cement composition of the present invention comprises the polycarboxylic acid-based copolymer described in Section A-1, the defoaming agent described in Section A-2, and cement. The specific form of the polycarboxylic acid-based copolymer according to Item A-1 that can be adopted here is a structure derived from the unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1). A polycarboxylic acid-based copolymer having a unit (I) and a structural unit (II) derived from an unsaturated carboxylic acid-based monomer (b) represented by the general formula (2), obtained by living polymerization. The degree of dispersion Mw / Mn is 1.00 to 1.25.

Practically, the cement composition further comprises water and aggregate. The cement composition may further contain the additional components described in Section A-3, if necessary.

The cement composition may contain each component according to items A-1 to A-3 as an additive for cement (item B).

The content of the additive for cement in the cement composition is preferably 0.001% by mass to 10% by mass, more preferably 0.005% by mass to 5% by mass, based on the solid content of the cement. It is more preferably 0.01% by mass to 3% by mass, particularly preferably 0.05% by mass to 2% by mass, and most preferably 0.1% by mass to 1% by mass. As described above, the cement additive according to the embodiment of the present invention can reduce the amount used to achieve the desired fluidity when made into a cement composition, and can reduce the viscosity of the cement composition as much as possible. The effect that the entrainment air of the cement composition can be sufficiently reduced and the compressive strength of the cement composition can be improved can be exhibited.

The content of the polycarboxylic acid-based copolymer in the cement composition is, in terms of solid content, preferably 0.02% by mass to 5% by mass, and more preferably 0.05% by mass to 1% by mass with respect to the cement. It is by mass, more preferably 0.1% by mass to 0.5% by mass, and particularly preferably 0.13% by mass to 0.2% by mass.

When the cement composition contains a defoaming agent, the content of the defoaming agent in the cement composition is a solid content, preferably 0.00001% by mass to 1% by mass, more preferably with respect to the cement. It is 0.00002% by mass to 0.1% by mass, more preferably 0.00005% by mass to 0.01% by mass, and particularly preferably 0.0001% by mass to 0.008% by mass.

As the aggregate, any suitable aggregate such as fine aggregate (sand or the like) or coarse aggregate (crushed stone or the like) can be adopted. Examples of such aggregates include gravel, crushed stone, granulated slag, and recycled aggregate. Further, examples of such aggregates include refractory aggregates such as silica stone, clay, zircon, high alumina, silicon carbide, graphite, chromium, chromog and magnesia.

As the cement contained in the cement composition, any suitable cement may be adopted. Examples of such cement include Portoland cement (ordinary, early-strength, ultra-fast-strength, moderate heat-resistant, sulfate-resistant and each low-alkali form), various mixed cements (blast furnace cement, silica cement, fly ash cement), and the like. White Portoland Cement, Alumina Cement, Ultra Fast Hard Cement (1 Clinker Fast Hard Cement, 2 Clinker Fast Hard Cement, Magnesium Phosphate Cement), Grout Cement, Oil Well Cement, Low Heat Cement (Low Heat Heat Type High Furnace Cement, Fly Ash Mixed Low) Heat-generating blast furnace cement, belite-rich cement), 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). Further, fine powder such as blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, silica powder, limestone powder, gypsum, and expansion material (for example, ettringite-based, coal-based) are added to the cement composition. You may. The cement contained in the cement composition may be only one kind or two or more kinds.

In the cement composition, any appropriate value can be set as the unit water amount per ^{1 m 3} of the cement composition, the amount of cement used, and the water / cement ratio. Such values, preferably, unit water is ^{100kg / m 3 ~185kg / m 3} , the amount of cement used is ^{250kg / m 3 ~800kg / m 3} , water / cement ratio (mass ratio) = is 0.1 to 0.7, more preferably, a unit water amount is ^{120kg / m 3 ~175kg / m 3} , the amount of cement used is ^{270kg / m 3 ~800kg / m 3} , water / cement ratio ( Mass ratio) = 0.12 to 0.65. As described above, the cement composition can be widely used from poor to rich concrete, and is effective for both ^{high-strength concrete having a large unit cement amount and poor concrete with a unit cement amount of 300 kg / m 3 or less.} ..

The cement composition may be effective for ready-mixed concrete, concrete for secondary concrete products, concrete for centrifugal molding, concrete for vibration compaction, steam curing concrete, sprayed concrete and the like. The cement composition of the present invention includes medium-fluidity concrete (concrete with a slump value of 22 to 25 cm), high-fluidity concrete (concrete with a slump value of 25 cm or more and a slump flow value of 50 to 70 cm), self-filling concrete, and self. It can also be effective for mortar and concrete that require high fluidity such as leveling materials.

The cement composition may be prepared by blending the constituent components by any suitable method. For example, a method of kneading the constituents in a mixer may be mentioned.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Unless otherwise specified, the term "parts" means parts by mass, and the term "%" means% by mass.

<Measurement conditions for weight average molecular weight Mw and dispersity Mw / Mn>
The weight average molecular weight and the degree of dispersion Mw / Mn were measured under the following measurement conditions.
Device: Waters Alliance (2695)
Analysis software: Waters, Emper Professional + GPC option column: Tosoh, TSKgel guard column (inner diameter 6.0 mm x 40 mm) + TSKgel G4000SWXL (inner diameter 7.8 mm x 300 mm) + G3000SWXL (inner diameter 7.8 mm x 300 mm) + G2000SWXL (inner diameter 7.8 mm x 300 mm) Inner diameter 7.8 mm x 300 mm)
Detectors: Differential Refractometer (RI) Detector (Waters 2414), Photodiode Array (PDA) Detector (Waters 2996)
Eluent: 115.6 g of sodium acetate trihydrate dissolved in a mixed solvent of 10999 g of water and 6001 g of acetonitrile, and the pH was adjusted to 6.0 with acetic acid.
GPC standard sample: Polyethylene glycol manufactured by GL Science (Peak Top Molecular Weight (Mp) 272500, 219300, 107000, 50000, 24000, 11840, 6450, 4250, 1470)
Calibration curve: Prepared by a cubic formula using the Mp value of the above polyethylene glycol.
Flow rate: 1.0 mL / min Column temperature: 40 ° C
Measurement temperature: 40 ° C
Measurement time: 45 minutes Sample solution injection amount: 100 μL (eluent solution with sample concentration of 0.5% by mass)
Standard sample injection volume: 100 μL (concentration 0.1% by mass eluent solution)
(Analysis method)
In the above measurement, for example, the RI chromatograms illustrated in FIGS. 1, 2 (A) and 2 (B) can be obtained. In the RI chromatogram of FIG. 1, the elution time is plotted on the horizontal axis and the RI signal intensity is plotted on the vertical axis. Further, in the RI chromatogram of FIG. 2A, the elution time is plotted on the horizontal axis and the RI signal intensity is plotted on the vertical axis. Further, in the RI chromatogram of FIG. 2B, the elution time is plotted on the horizontal axis, and the unit time change amount ΔRI of the RI signal intensity is plotted on the vertical axis. The scales on the horizontal axes of FIGS. 2 (A) and 2 (B) are aligned in the same manner. The unit time of ΔRI may be set to an arbitrary time of 1 second or less, and the difference between the elution time and the RI signal intensity before the elution time by the unit time is calculated and plotted.
In the obtained RI chromatogram, as shown in the examples of FIGS. 1 and 2 (A), a portion that is flat and stable at the baseline before polymer elution and a portion that is flat and stable at the baseline after polymer elution are obtained. The polymer was detected and analyzed by connecting the existing portions with a straight line (straight line L in the example of FIGS. 1 and 2 (A)).
Depending on the type of monomer to be polymerized and the method of polymerization, a monomer peak or a peak derived from a high molecular weight impurity may be detected in addition to the polymer peak which is the main component. The elution time of these peaks differs depending on the molecular weight of the monomer and the type of impurities contained, but if these peaks overlap with the polymer peaks, these peaks are separated / excluded by the method shown below, and the main component is The remaining portion including the polymer peak was used as the polymer portion, and the molecular weight and dispersity (Mw / Mn) of only the polymer portion were calculated.
When the monomer peak is measured so as to overlap the polymer peak (PT is the polymer peak and M is the monomer peak in the example of FIGS. 1 and 2 (A)), the polymer peak PT and the monomer peak M are the most recessed portions of the overlapping portion. At the elution time ta, both peaks were vertically divided to separate the polymer part and the monomer part. In the examples of FIGS. 1 and 2 (A), the shaded portion detected between the elution times ta and tb is the monomer portion. When oligomers of dimer or higher were detected between the peak top elution time tp and ta of the polymer peak, these were included in the polymer portion.
When a high molecular weight peak was detected at an elution time earlier than the peak top elution time tp of the polymer peak, it was divided by one of the following two methods according to the overlapping method and excluded from the polymer part.
As shown in FIG. 1, when a maximum point exists at the peak N of the high molecular weight, the two peaks are vertically divided by td, where td is the elution time at which the maximum point is reached and the elution time at which the recess is located between tp. The high molecular weight part was excluded from the polymer part. In the example of FIG. 1, the shaded portion detected between the elution time ct and td is the high molecular weight portion.
As shown in FIG. 2A, when the peak K of the high molecular weight does not have a maximum point and is the shoulder peak of the main component polymer peak PT, it is between the high molecular weight peak K and the main component polymer peak PT. The elution time of the inflection from the upward convex to the downward convex on the PT side of the polymer peak was defined as td, and the two peaks were vertically divided by td to exclude the high molecular weight portion from the polymer portion. In the example of FIG. 2A, the shaded portion detected during the elution time tc to td is the high molecular weight portion. The inflection point from upward convex to downward convex here is a point where the magnitude of ΔRI becomes a minimum value. The elution time td in FIG. 2 (A) appears as a minimum value in the graph in FIG. 2 (B) with ΔRI on the vertical axis.

<ICP-MS measurement>
ICP-MS was measured under the following measurement conditions.
Device: Agilent Technologies ICP mass spectrometer 7700 type Measurement conditions: RF power: 1500 W, nebulizer pump: 0.10 rps, carrier gas: 0.70 L / min

[Synthesis Example 1]
240 parts of ion-exchanged water, 115 parts of alcoholic methacrylic acid ester obtained by adding 25 mol of ethylene oxide to methanol, 35.7 parts of methacrylic acid in a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, and a recirculation cooler. 2.73 parts of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (trade name "V-50" manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, 4-cyano-as a chain transfer agent. 7.14 parts of 4- (thiobenzoylthio) pentanoic acid was charged, stirred at 300 rpm, and the inside of the reaction apparatus was replaced with nitrogen at 500 mL / min for 30 minutes, and then the temperature was raised to 70 ° C. Then, the temperature was maintained at 70 ° C. for 3 hours to complete the polymerization reaction, and an aqueous solution of the copolymer (1), which is an additive for inorganic particles, was obtained. The physical characteristics of the obtained copolymer (1) are shown in Table 1.

[Synthesis Examples 2-4]
The same as in Example 1 except that the amount of the chain transfer agent was changed as shown in Table 1 and the amount of the polymerization initiator was changed so as to be the same as the ratio of the amount of the polymerization initiator and the chain transfer agent in Example 1. This was carried out to obtain aqueous solutions of the copolymers (2) to (4), which are additives for inorganic particles. The physical characteristics of the obtained copolymers (2) to (4) are shown in Table 1.

[Synthesis Example 5]
240 parts of ion-exchanged water, 123 parts of methacrylic acid ester of alcohol obtained by adding 25 mol of ethylene oxide to methanol, 32.7 parts of methacrylic acid in a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, and a recirculation cooler. 0.727 parts of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (trade name "V-50" manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, 4-[((2-methylpropionamidine)) as a chain transfer agent 2-carboxyethyl sulfanylthiocarbonyl) sulfanyl] -4-cyanopentanoic acid was charged in 3.30 parts, stirred at 300 rpm, the inside of the reaction apparatus was replaced with nitrogen at 500 mL / min for 30 minutes, and then the temperature was raised to 70 ° C. Then, the temperature was maintained at 70 ° C. for 3 hours to complete the polymerization reaction, and an aqueous solution of the copolymer (5), which is an additive for inorganic particles, was obtained. The physical characteristics of the obtained copolymer (5) are shown in Table 1.

[Synthesis Example 6]
The same as in Example 5 except that the amount of the chain transfer agent was changed as shown in Table 1 and the amount of the polymerization initiator was changed so as to be the same as the ratio of the amount of the polymerization initiator and the chain transfer agent in Example 5. Then, an aqueous solution of the copolymer (6), which is an additive for inorganic particles, was obtained. The physical characteristics of the obtained copolymer (6) are shown in Table 1.

[Synthesis Example 7]
Examples show the mass ratio of the monomer (a) to the monomer (b) (monomer (a) / (b)) and the amount of the chain transfer agent as shown in Table 1, and the amount of the polymerization initiator. The same procedure as in Example 1 was carried out except that the ratio was changed so as to be the same as the ratio of the amounts of the polymerization initiator and the chain transfer agent of No. 1, to obtain an aqueous solution of the copolymer (7) as an additive for inorganic particles. The physical characteristics of the obtained copolymer (7) are shown in Table 1.

[Comparative synthesis example 1]
110 parts of ion-exchanged water was placed in a glass reaction vessel equipped with a thermometer, agitator, a dropping funnel, and a reflux cooler, and the temperature was raised to 80 ° C. while stirring at 300 rpm and replacing nitrogen in the reactor at 500 mL / min. After that, 118 parts of methacrylic acid ester and 36.5 parts of methacrylic acid obtained by adding 25 mol of ethylene oxide to methanol and 5.73 parts of 3-mercaptopropionic acid, which is a chain transfer agent, were dissolved in 100 parts of ion-exchanged water. An aqueous solution prepared by dissolving 1.86 parts of sodium persulfate as a polymerization initiator in 38.1 parts of ion-exchanged water was added dropwise over 5 hours. After completion of the dropping, the temperature was continuously maintained at 80 ° C. for 1 hour to complete the polymerization reaction, and an aqueous solution of the copolymer (C1) was obtained. The physical characteristics of the obtained copolymer (C1) are shown in Table 2.

[Comparative Synthesis Examples 2 and 3]
The same procedure as in Comparative Example 1 was carried out except that the amount of the chain transfer agent was changed as shown in Table 2, to obtain aqueous solutions of the copolymers (C2) to (C3). The physical characteristics of the obtained copolymers (C2) to (C3) are shown in Table 2.

[Comparative synthesis example 4]
Similar to Comparative Example 1 except that the mass ratio of the monomer (a) to the monomer (b) (monomer (a) / (b)) and the amount of the chain transfer agent were changed as shown in Table 2. Then, an aqueous solution of the copolymer (C4) was obtained. The physical characteristics of the obtained copolymer (C4) are shown in Table 2.

[Examples 1 to 5, Comparative Examples 1 to 4]
The evaluation test of the additive for inorganic particles was carried out by the method of the mortar test described below. The copolymers used, antifoaming agents, and evaluation results are shown in Table 3. In Examples 1 to 5 and Comparative Examples 1 to 4, the kneaded water contains ion-exchanged water, an aqueous solution of each copolymer, and a defoaming agent (MA404).

<Mortar test>
The composition of the materials and mortar used in the test was 900 g of Pacific ordinary Portland cement, 1350 g of ISO standard sand for strength test, and 270 g of kneaded water. A mortar was prepared by mechanically kneading with a hovert mixer for 4 minutes at a room temperature of 20 ° C. and a relative humidity of 55% by the following kneading method, and obtained in a metal flow cone having an upper inner diameter of 70 mm, a lower inner diameter of 100 mm and a height of 60 mm. I packed the mortar. Next, after 5.5 minutes after water injection, the flow cone was lifted vertically, and then the diameter of the mortar spread on the table was measured in two orthogonal directions, and this average was taken as the mortar flow value. The amount of air was measured by the following method.

<Kneading method>
A kneader (Hobert Japan Co., Ltd., Mixer N50) was used to knead the mortar of each batch. The operation of the kneader was performed as follows. Cement was added to the kneading pot, and water containing each polymer and antifoaming agent was added. The kneader was then immediately started at low speed and after 30 seconds, sand was added in the next 30 seconds. The kneader was speeded up and then kneaded for 30 seconds. After that, the kneader was stopped for 90 seconds. During the first 15 seconds of rest, the mortar adhering to the kneading pot was scraped off. After that, kneading was continued at high speed for 60 seconds.

<Air volume measurement method>
Approximately 150 mL of mortar was packed in a 500 mL glass graduated cylinder with a known mass, and after poking it 10 to 15 times with a cylindrical thrust rod with a length of 40 cm and a diameter of 5 mm, the graduated cylinder was lifted and beaten at the bottom 10 times to vibrate. .. This operation was repeated 3 times to make the total volume about 450 mL, and the volume and weight were measured. Based on the densities of cement and sand used, the theoretical volume was calculated from the measured mass assuming that there was no air. The difference between the measured mass and the theoretical volume was taken as the amount of air, and the ratio to the whole was shown by volume%.

[Example 6, Comparative Example 5]
The additive for inorganic particles of the present invention can obtain a high viscosity reducing effect and a fluidity improving effect by combining with a defoaming agent, but even when the defoaming agent is not added, the additive for inorganic particles of the present invention is conventionally used. It shows superiority to the additive for inorganic particles containing the copolymer obtained by the polymerization method of. Table 4 shows the evaluation results in the mortar test when no antifoaming agent was used in combination. In Example 6 and Comparative Example 5, since no defoaming agent was added, an increase in the amount of air was observed and a decrease in fluidity was observed. However, the additive for inorganic particles of the present invention was obtained by a conventional polymerization method. It showed superiority over additives for inorganic particles including copolymers. Note that Example 6 and Comparative Example 5 are examples in which the defoaming agent is not used in combination, and the kneading water is ion-exchanged water and an aqueous solution of each copolymer, and the kneading water does not contain the defoaming agent.

The additive for inorganic particles of the present invention is suitably used for cement compositions such as cement paste, mortar and concrete.

Claims (7)

Derived from the structural unit (I) derived from the unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) and the unsaturated carboxylic acid-based monomer (b) represented by the general formula (2). An additive for cement containing a polycarboxylic acid-based copolymer having the structural unit (II) of.
The polycarboxylic acid-based copolymer was obtained by RAFT polymerization.
The weight average molecular weight Mw in terms of polyethylene glycol obtained by gel permeation chromatography of the polycarboxylic acid-based copolymer is 50,000 or less.
Degree of dispersion Mw / Mn of the polycarboxylic acid-based copolymer Ri der 1.00 to 1.25,
The unsaturated polyalkylene glycol-based monomer (a) is an ester of alkoxypolyalkylene glycols of (meth) acrylic acid.
Additives for cement .

(In the general formula (1), R ¹ and R ² represent the same or different hydrogen atom or methyl group, R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and AO represents a hydrocarbon group. , Represents an oxyalkylene group having 2 to 18 carbon atoms, n represents the average number of moles of the oxyalkylene group represented by AO, n is a number of 1 to 500, and x is an integer of 0 to 2. Is.)

(In the general formula (2), R ^{4 to} R ⁶ represent the same or different hydrogen atom, methyl group, _{or-(CH 2} ) zCOOM group, and-(CH ₂ ) zCOOM group is -COOX group or other. -(CH ₂ ) zCOOM group may form an anhydride, z is an integer of 0 to 2, and M is a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, Alternatively, it represents an organic amine group, and X represents a hydrogen atom, a methyl group, an ethyl group, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group.) Derived from the structural unit (I) derived from the unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) and the unsaturated carboxylic acid-based monomer (b) represented by the general formula (2). An additive for cement containing a polycarboxylic acid-based copolymer having the structural unit (II) of.
The cement additive contains a defoaming agent and
The polycarboxylic acid-based copolymer was obtained by RAFT polymerization.
Degree of dispersion Mw / Mn of the polycarboxylic acid-based copolymer Ri der 1.00 to 1.25,
The unsaturated polyalkylene glycol-based monomer (a) is an ester of alkoxypolyalkylene glycols of (meth) acrylic acid.
Additives for cement .

(In the general formula (1), R ¹ and R ² represent the same or different hydrogen atom or methyl group, R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and AO represents a hydrocarbon group. , Represents an oxyalkylene group having 2 to 18 carbon atoms, n represents the average number of moles of the oxyalkylene group represented by AO, n is a number of 1 to 500, and x is an integer of 0 to 2. Is.)

(In the general formula (2), R ^{4 to} R ⁶ represent the same or different hydrogen atom, methyl group, _{or-(CH 2} ) zCOOM group, and-(CH ₂ ) zCOOM group is -COOX group or other. -(CH ₂ ) zCOOM group may form an anhydride, z is an integer of 0 to 2, and M is a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, Alternatively, it represents an organic amine group, and X represents a hydrogen atom, a methyl group, an ethyl group, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group.) The cement additive according to claim 1 or 2, wherein the total content of heavy metals and tellurium in the solid content of the polycarboxylic acid-based copolymer containing the polycarboxylic acid-based copolymer is 300 μg / g or less. The invention according to any one of claims 1 to 3, wherein the polycarboxylic acid-based copolymer has a structure derived from at least one selected from dithioester, trithiocarbonate, dithiocarbamate, and xantane at the polymer terminal. Additives for cement . The cement additive according to any one of claims 1 to 4, wherein the RAFT agent used in the RAFT polymerization has at least one functional group selected from dithioester, trithiocarbonate, dithiocarbamate, and xantane. A cement composition comprising the cement additive according to any one of claims 1 to 5 and cement. A cement composition containing a polycarboxylic acid-based copolymer, an antifoaming agent, and cement.
The polycarboxylic acid-based copolymer has a structural unit (I) derived from an unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) and an unsaturated represented by the general formula (2). A polycarboxylic acid-based copolymer having a structural unit (II) derived from the carboxylic acid-based monomer (b).
The polycarboxylic acid-based copolymer was obtained by RAFT polymerization.
The dispersity Mw / Mn of the polycarboxylic acid-based copolymer is 1.00 to 1.25, and the degree of dispersion is 1.00 to 1.25.
The unsaturated polyalkylene glycol-based monomer (a) is an ester of alkoxypolyalkylene glycols of (meth) acrylic acid.
Cement composition.

(In the general formula (1), R ¹ and R ² represent the same or different hydrogen atom or methyl group, R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and AO represents a hydrocarbon group. , Represents an oxyalkylene group having 2 to 18 carbon atoms, n represents the average number of moles of the oxyalkylene group represented by AO, n is a number of 1 to 500, and x is an integer of 0 to 2. Is.)

(In the general formula (2), R ^{4 to} R ⁶ represent the same or different hydrogen atom, methyl group, _{or-(CH 2} ) zCOOM group, and-(CH ₂ ) zCOOM group is -COOX group or other. -(CH ₂ ) zCOOM group may form an anhydride, z is an integer of 0 to 2, and M is a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, Alternatively, it represents an organic amine group, and X represents a hydrogen atom, a methyl group, an ethyl group, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group.)

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