JP5019734B2 - Cement admixture and method for producing the same - Google Patents

Description

  The present invention relates to a cement admixture and a method for producing the same.

  Since the early deterioration of concrete structures has become a social issue, it has been strongly demanded to reduce the unit water volume in concrete and improve its workability and durability. There has been a lot of technological innovation for influential cement admixtures.

In particular, cement admixtures having oxyalkylene groups have many proposals because they exhibit higher water reduction performance than conventional naphthalene-based cement admixtures.
For example, Patent Document 1 discloses a cement admixture containing a copolymer composed of a specific unsaturated polyalkylene glycol ester monomer and a (meth) acrylic acid monomer. In this document, as a cement dispersant having excellent slump retention performance, a polycarboxylic acid polymer having a weight average molecular weight within a predetermined range and a value obtained by subtracting a peak top molecular weight from a weight average molecular weight within a predetermined range ( A cement dispersant based on A) or a salt thereof is disclosed. Also disclosed is the use of water-soluble polymerization initiators such as ammonia or alkali metal persulfates, hydrogen peroxide, azoamidine compounds such as azobis-2-methylpropionamidine hydrochloride, and the like. It is disclosed that a promoter can be used in combination. On the other hand, there is no description about a polymerization initiator system containing persulfuric acid or a salt thereof and an organic reducing compound, and there is no description about the relationship between the polymerization initiator system and the performance of the resulting polymer.

  Patent Document 2 proposes a cement dispersant mainly composed of a copolymer derived from a polyoxyalkylene alkenyl ether monomer and an unsaturated monocarboxylic acid monomer, and improves water reduction performance. Has been done. Patent Document 2 discloses that the polymerization is preferably initiated by a redox polymerization initiator that uses a peroxide and a reducing agent in combination, and the peroxide contains a persulfate. On the other hand, the literature particularly includes a combination of hydrogen peroxide and L-ascorbic acid, a combination of hydrogen peroxide and erythorbic acid, a combination of hydrogen peroxide and molle salt, and a combination of sodium persulfate and sodium bisulfite. A particularly preferred combination is disclosed as a combination of hydrogen peroxide and L-ascorbic acid. Thus, the superiority of the polymerization initiator system containing persulfuric acid or a salt thereof and an organic reducing compound is negative, and there is no description about the relationship between the polymerization initiator system and the performance of the resulting polymer.

  In the above-described known polycarboxylic acid-based dispersants having an oxyalkylene group, the dispersion retention is insufficient, and there is a case where the decrease in the fluidity of the cement composition over time may not be sufficiently suppressed. is there.

JP-A-9-86990 JP 2001-220417 A

  An object of the present invention is to provide a cement admixture that can achieve better dispersion retention than conventional ones among cement admixtures that require a polymer having a polyoxyalkylene chain, and a method for producing the same.

  Conventionally, it is well known that a polycarboxylic acid-based dispersant having an oxyalkylene group in the side chain is excellent in water reduction performance. Such a polycarboxylic acid-based dispersant is generally obtained by copolymerizing a monomer having an oxyalkylene chain and a carboxylic acid-based monomer. In order to achieve excellent dispersion retention with such a polymer, it is necessary to reduce the content of the carboxylic acid monomer as much as possible. The yield of the polymer is deteriorated, and as a result, dispersibility and dispersion retention tend to be deteriorated.

  The present inventors paid attention to the polymerization initiator system in order to obtain a polymer with good yield, and found that the use of a specific initiator system is excellent in the yield of the polymer. As a result, the present inventors have found that a cement dispersant using the polymer is excellent in dispersion retention of the cement composition. As a result, the present inventors have found that an ascorbic acid-based compound that has not been attracting attention in the past improves the dispersion retention of the cement composition under specific conditions, and has completed the present invention.

  The present invention is a cement admixture described below, a production method thereof, and a cement composition using the admixture.

<I> As a structural unit derived from a polyoxyalkylene group, the following (general formula 1)

(In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or a methyl group; AO is the same or different and represents one or more oxyalkylene groups having 2 or more carbon atoms; In the case of more than seeds, they may be bonded in a block shape or in a random shape, n represents an average added mole number of an oxyalkylene group and represents a number of 1 to 300, and x is an integer of 0 to 2. Y represents 0 or 1, and R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms), and a polymer (P) containing the structural unit (I) represented as an essential structural unit, A cement admixture comprising ascorbic acid compounds (AsA-D) and sulfate ions (SO ₄ ²⁻ ) as essential components.

<Ii> The cement admixture according to <i>, wherein the ratio of the ascorbic acid-based compound (AsA-D) to the polymer (P) is 0.001 to 5% by mass, and sulfate ion (SO ₄ ^2- ) Is preferably 0.01 to 10% by mass.

  <Iii> The polymer (P) is the following (general formula 2)

(In the formula, R ⁴ , R ⁵ and R ⁶ are the same or different, and a hydrogen atom, a methyl group or — (CH ₂ ) zCOOM ² group (— (CH ₂ ) zCOOM ² is —COOM ¹ or other — (CH ₂ ) may form an anhydride with zCOOM ² ), n represents an integer of 0 to 2, and M ¹ and M ² are the same or different and represent a hydrogen atom, an alkali metal atom, an alkaline earth It is preferable that the structural unit (II) containing a carboxyl group represented by a similar metal atom, an ammonium group or an organic amine group) is contained as an essential structural unit.

  <Iv> In the cement admixture according to any one of <i> to <iii>, the structural unit (I) derived from a polyoxyalkylene group is represented by the following (general formula 3):

(In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or a methyl group; AO is the same or different and represents one or more oxyalkylene groups having 2 or more carbon atoms; In the case of more than seeds, they may be bonded in a block shape or in a random shape, n represents an average added mole number of an oxyalkylene group and represents a number of 1 to 300, and x is an integer of 0 to 2. And y represents 0 or 1, and R ³ preferably represents a hydrogen atom or a polyoxyalkylene monomer (IM) represented by a hydrocarbon group having 1 to 20 carbon atoms. .

  <V> In the cement admixture according to <i> to <iv>, the structural unit (II) containing a carboxyl group is represented by the following (general formula 4):

(In the formula, R ⁴ , R ⁵ and R ⁶ are the same or different, and a hydrogen atom, a methyl group or — (CH ₂ ) zCOOM ² group (— (CH ₂ ) zCOOM ² is —COOM ¹ or other — (CH ₂ ) may form an anhydride with zCOOM ² ), n represents an integer of 0 to 2, and M ¹ and M ² are the same or different and represent a hydrogen atom, an alkali metal atom, an alkaline earth It is preferably a structural unit derived from a carboxyl group-containing unsaturated monomer (II-M) represented by a metal atom, an ammonium group or an organic amine group.

  <Vi> If the ascorbic acid compound (AsA-D) and persulfuric acid or a salt thereof (C) are added during the polymerization of the polymer (P), the cement admixture according to any one of <i> to <v> The agent can be suitably produced.

  <Vii> A cement composition comprising the cement admixture according to any one of <i> to <v>.

  The present invention relates to a method for producing a polymer using a polymerization initiator system that contributes to fluidity retention when used as a cement admixture and can improve the yield when producing the polymer to be used, and uses the polymer. And a cement composition using the admixture. The cement composition using the cement admixture of the present invention can maintain fluidity for a long time and contributes to improvement in workability.

  The polymer (P) essentially comprising a structural unit derived from a polyoxyalkylene group is derived from a polyoxyalkylene monomer having an average addition mole number of oxyalkylene groups of 1 to 300 represented by the general formula 1 above. The structural unit is not particularly limited as long as the structural unit (I) is contained as an essential structural unit, but a structure in which the polyoxyalkylene group is grafted to the polymer main chain is preferable.

  The type of the oxyalkylene group in (General Formula 1) is not particularly limited, but the number of carbon atoms of AO is preferably within the range of 2-18, more preferably within the range of 2-8, and particularly preferably within the range of 2-4. preferable. Moreover, from the viewpoint of the dispersion performance of the inorganic powder using water as a medium, it is necessary to increase the hydrophilicity of the oxyalkylene group, and it is preferable that the oxyalkylene group contains a oxyethylene group having 2 carbon atoms as an essential component. . At this time, the ratio of oxyethylene groups to all oxyalkylene groups is preferably 50 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and further preferably 100 mol%.

  Further, the average addition mole number of the oxyalkylene group in (General Formula 1) is not particularly limited, but the average addition mole number is preferably 1 to 300, and preferably 2 moles or more from the viewpoint of improving the dispersibility of the inorganic powder. Preferably it is 4 mol or more, More preferably, it is 10 mol or more, More preferably, it is 20 mol or more. From the viewpoint of production of the oxyalkylene chain, the upper limit of the oxyalkylene group is preferably 300 mol, more preferably 200 mol or less, still more preferably 150 mol or less.

  Any two or more types of alkylene oxide adducts can be used, such as random addition, block addition, and alternate addition.

  It is essential that the polymer (P) has a structural unit (I) derived from a polyoxyalkylene group, and a polymer (P) having a structural unit (II) containing a carboxyl group is more preferable. When the content of the structural unit (I) is too low, the dispersion retention is deteriorated, and when the content of the structural unit (II) is too small, the dispersion performance is hardly exhibited. ) / Structural unit (II) = 1 to 90/99 to 10 (mol%), preferably in the range of structural unit (I) / structural unit (II) = 5 to 60/95 to 40 (mol%). More preferably, the range of structural unit (I) / structural unit (II) = 10-50 / 90-50 (mol%) is particularly preferable (however, the total of structural unit (I) and structural unit (II) is 100 mol%) Is).

The polymer (P) may further contain a structural unit (III) derived from a monomer (III-M) described later. The ratio of each structural unit when the polymer (P) includes the structural unit (III) is not particularly limited as long as the structural unit (I) is essential. However, if the content of the structural unit (I) is too low, the dispersion retention deteriorates. If the content of the structural unit (II) is too small, the dispersion performance deteriorates. ) / (Constituent unit (II) + constituent unit (III)) = 1-80 / 99-20 (mol%) is preferred, and constituent unit (I) / (constituent unit (II) + constituent unit (IV) ) = 5-60 / 95-40 (mol%) is more preferable, and structural unit (I) / structural unit (I) / (structural unit (II) + structural unit (III)) = 10-50 / 90 The range of ˜50 (mol%) is particularly preferable (however, the total of the structural unit (I), the structural unit (II) and the structural unit (III) is 100 mol%).
<Monomer for obtaining a polymer (P) containing a structural unit derived from a polyoxyalkylene group>
Examples of the monomer that gives the structural unit (I) include the following (general formula 3).

(In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or a methyl group; AO is the same or different and represents one or more oxyalkylene groups having 2 or more carbon atoms; In the case of more than seeds, they may be bonded in a block shape or in a random shape, n represents an average added mole number of an oxyalkylene group and represents a number of 1 to 300, and x is an integer of 0 to 2. Y represents 0 or 1, and R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms). M ”).

  As unsaturated monomer component (IM), methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 1-hexanol, octanol, 2-ethyl-1 -C1-C20 saturated aliphatic alcohols such as hexanol, nonyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, allyl alcohol, methallyl alcohol, crotyl alcohol, oleyl alcohol, etc. C3-C20 alicyclic alcohols such as saturated aliphatic alcohols, cyclohexanol, phenol, phenylmethanol (benzyl alcohol), methylphenol (cresol), p-ethylphenol, dimethylphenol (xylenol), nonylfe Alkoxy polyalkylene glycols obtained by adding an alkylene oxide having 2 to 18 carbon atoms to any of aromatic alcohols having 6 to 20 carbon atoms such as diol, dodecylphenol, phenylphenol and naphthol, Examples include esterified products of polyalkylene glycols obtained by polymerizing 18 alkylene oxides with (meth) acrylic acid and crotonic acid, and one or more of these can be used. Among these, (meth) acrylic acid alkoxypolyalkylene glycol esters are preferred. Further, vinyl alcohol, (meth) allyl alcohol, 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-3-buten-2-ol, 2-methyl- The compound which added 1-300 mol of alkylene oxides to unsaturated alcohols, such as 2-buten-1-ol and 2-methyl-3-buten-1-ol, can be mentioned, These 1 type or 2 types or more are used. be able to. Among these monomers, compounds using (meth) allyl alcohol and 3-methyl-3-buten-1-ol are particularly preferable. In addition, said unsaturated ester and unsaturated ether are arbitrary 1 type chosen from C2-C18 alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, as alkylene oxide, Alternatively, two or more alkylene oxides may be added. When two or more types are added, any of random addition, block addition, and alternate addition may be used.

In (General Formula 3), R ³ may be a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. Specifically, the hydrocarbon group having 1 to 20 carbon atoms is specifically an alkyl having 1 to 20 carbon atoms. A benzene ring such as a group (aliphatic alkyl group or alicyclic alkyl group), a phenyl group having 6 to 20 carbon atoms, an alkylphenyl group, a phenylalkyl group, a phenyl group substituted with an (alkyl) phenyl group, or a naphthyl group. As the number of carbons in the case where R ³ is a hydrocarbon group, the number of carbons in the case of R ³ is 1-18. 1 to 12 is more preferable, 1 to 4 is particularly preferable, and R ² is most preferably a methyl group or a hydrogen atom.

  Examples of the monomer that gives the structural unit (II) include the following (general formula 4):

(In the formula, R ⁴ , R ⁵ and R ⁶ are the same or different, and a hydrogen atom, a methyl group or — (CH ₂ ) zCOOM ² group (— (CH ₂ ) zCOOM ² is —COOM ¹ or other — (CH ₂ ) may form an anhydride with zCOOM ² ), n represents an integer of 0 to 2, and M ¹ and M ² are the same or different and represent a hydrogen atom, an alkali metal atom, an alkaline earth A metal atom, an ammonium group or an organic amine group).

  Specific examples thereof include acrylic acid, methacrylic acid, crotonic acid and their metal salts, ammonium salts and amine salts as unsaturated monocarboxylic acid monomers, and as unsaturated dicarboxylic acid monomers. , Maleic acid, itaconic acid, citraconic acid, fumaric acid, or metal salts thereof, ammonium salts, amine salts, and the like, and examples of anhydrides thereof include maleic anhydride, itaconic anhydride, citraconic anhydride, and the like. . Of these, acrylic acid, methacrylic acid, maleic acid, maleic anhydride and salts thereof are preferred from the viewpoint of polymerizability. Two or more of these monomers may be used in combination.

  It is also preferable to use an unsaturated monomer (III-M) that is different from the monomers (IM) and (II-M) and is copolymerizable with (IM) and (II-M). . Examples of such monomers (III-M) include half of unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid and alcohols having 1 to 30 carbon atoms. Esters, diesters; half amides and diamides of unsaturated dicarboxylic acids and amines having 1 to 30 carbon atoms; alkyls obtained by adding 1 to 500 moles of alkylene oxides having 2 to 18 carbon atoms to the alcohols and amines Half-esters and diesters of (poly) oxyalkylene and the unsaturated dicarboxylic acids; the unsaturated dicarboxylic acids and a glycol having 2 to 18 carbon atoms or a polyoxyalkylene having 2 to 500 addition moles of these glycols. Half ester, diester; methyl (meth) acrylate, ethyl (meth) a Esters of unsaturated monocarboxylic acids such as relate, propyl (meth) acrylate, glycidyl (meth) acrylate, methyl crotonate, ethyl crotonate, propyl crotonate, and alcohols having 1 to 30 carbon atoms; Esters of alkoxy (poly) oxyalkylene obtained by adding 1 to 500 moles of alkylene oxide having 2 to 18 carbon atoms to 30 alcohols and unsaturated monocarboxylic acids such as (meth) acrylic acid; (poly) ethylene glycol Addition of 1 to 500 moles of alkylene oxide having 2 to 18 carbon atoms to unsaturated monocarboxylic acids such as (meth) acrylic acid, such as monomethacrylate, (poly) propylene glycol monomethacrylate, (poly) butylene glycol monomethacrylate Things: Maleamic acid and charcoal Half amides of glycols having 2 to 18 atoms or polyoxyalkylenes having 2 to 500 addition moles of these glycols; triethylene glycol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, polypropylene glycol (Poly) oxyalkylene di (meth) acrylates such as di (meth) acrylate and (poly) ethylene glycol (poly) propylene glycol di (meth) acrylate; hexanediol di (meth) acrylate, trimethylolpropane tri (meth) Bifunctional (meth) acrylates such as acrylate and trimethylolpropane di (meth) acrylate; (Poly) oxyalkylene dimaleates such as triethylene glycol dimaleate and polyethylene glycol dimaleate; Nyl sulfonate, (meth) allyl sulfonate, 2- (meth) acryloxyethyl sulfonate, 3- (meth) acryloxypropyl sulfonate, 3- (meth) acryloxy-2-hydroxypropyl sulfonate, 3- (meth) acryloxy-2 -Hydroxypropylsulfophenyl ether, 3- (meth) acryloxy-2-hydroxypropyloxysulfobenzoate, 4- (meth) acryloxybutylsulfonate, (meth) acrylamidomethylsulfonic acid, (meth) acrylamidoethylsulfonic acid, 2- Unsaturated sulfonic acids such as methylpropanesulfonic acid (meth) acrylamide and styrenesulfonic acid, and their monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts; like methyl (meth) acrylamide Amides of unsaturated monocarboxylic acids and amines having 1 to 30 carbon atoms; vinyl aromatics such as styrene, α-methylstyrene, vinyltoluene, p-methylstyrene; 1,4-butanediol mono (meth) Alkanediol mono (meth) acrylates such as acrylate, 1,5-pentanediol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate; butadiene, isoprene, 2-methyl-1,3-butadiene, Dienes such as 2-chloro-1,3-butadiene; unsaturated amides such as (meth) acrylamide, (meth) acrylalkylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide; Unsaturated cyanides such as (meth) acrylonitrile, α-chloroacrylonitrile; Unsaturated esters such as vinyl acid vinyl and vinyl propionate; aminoethyl (meth) acrylate, methylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, (meta ) Unsaturated amines such as dibutylaminoethyl acrylate and vinyl pyridine; divinyl aromatics such as divinylbenzene; cyanurates such as triallyl cyanurate; allyls such as (meth) allyl alcohol and glycidyl (meth) allyl ether ; Unsaturated amino compounds such as dimethylaminoethyl (meth) acrylate; methoxypolyethylene glycol monovinyl ether, polyethylene glycol monovinyl ether, methoxypolyethylene glycol mono (meth) allyl ether, polyethylene glycol Vinyl ethers or allyl ethers such as mono (meth) allyl ether; polydimethylsiloxanepropylaminomaleamic acid, polydimethylsiloxaneaminopropylaminomaleamic acid, polydimethylsiloxane-bis- (propylaminomaleamic acid), polydimethyl Siloxane-bis- (dipropyleneaminomaleamic acid), polydimethylsiloxane- (1-propyl-3-acrylate), polydimethylsiloxane- (1-propyl-3-methacrylate), polydimethylsiloxane-bis- (1- Propyl derivatives such as propyl-3-acrylate) and polydimethylsiloxane-bis- (1-propyl-3-methacrylate), and the like, and one or more of these can be used.

  The ascorbic acid compound (AsA-D) according to claims 1 to 2 represents ascorbic acid and its derivatives. Specific examples include L-xylo-AsA (L-ascorbic acid) which is an isomer of ascorbic acid, D-xylo-AsA, L-arabo-AsA and D-arabo which are isomers of L-ascorbic acid. -AsA (erythorbic acid); alkali metal (Na, K etc.) salt, alkaline earth metal (Ca, Mg etc.) salt, ammonium group or organic amine group salt of L-ascorbic acid and its isomers; ascorbyl stearate; L-ascorbic acid and its isomer esters such as ascorbyl palmitate; L-ascorbic acid and its isomer phosphate esters such as L-ascorbic acid phosphate and L-ascorbic acid phosphate magnesium and the like Salt; L-ascorbine such as monodehydroascorbic acid and dehydroascorbic acid And oxides of isomers; and the like. Any of these compounds may be used, but since the cement admixture is often provided in the form of an aqueous solution, it is more preferable if the reducing organic compound (AsA-D) is also water-soluble.

  The ascorbic acid compound (AsA-D) exhibits fluidity retention when used as a cement admixture. A necessary amount may be added to the cement admixture, but as shown in Examples and Comparative Examples described later, it is more effective to add the polymer (P) during polymerization. In that case, (AsA-D) can generate radicals by redox reaction with persulfuric acid or a salt thereof (C), and therefore can be used as a constituent element of the initiator system. In addition, when an initiator system comprising an ascorbic acid compound (AsA-D) and persulfuric acid or a salt thereof (C) is used, the yield of the polymer (P) is improved compared to a known initiator system. It was issued.

  The mechanism by which the ascorbic acid compound (AsA-D) exhibits fluidity retention in the cement composition is not yet clear, but if added in a large amount to the cement composition, the early strength of the cured cement composition may decrease. It was. Ascorbic acid compounds are similar in structure to gluconic acid, and compounds such as gluconic acid and glucose are known to delay the hardening of the cement composition. Therefore, the ascorbic acid compound (AsA-D) may have some influence on the initial hydration of the cement composition, and may improve the fluidity retention of the cement composition. It is more effective to use an ascorbic acid compound (AsA-D) and sulfate ion in combination to improve the fluidity retention of the cement composition, but the cause of this is still unclear.

  If the amount of the ascorbic acid compound (AsA-D) in the cement admixture is too large as described above, the early strength of the cured cement composition may be reduced, and if it is too small, the flow of the cement composition may be reduced. Since retainability does not improve, 0.001-5 mass% is preferable with respect to a polymer (P), 0.01-3 mass% is more preferable, 0.05-1 mass% is further more preferable.

The sulfate ion (SO ₄ ²⁻ ) according to claim 1 may be used by adding a necessary amount to the cement admixture using sulfuric acid or the like, but the ascorbic acid compound (AsA) during the polymerization of the polymer (P). It is efficient to add it as persulfuric acid or a salt thereof together with -D) and reduce it to generate sulfate ions.

The persulfuric acid according to claim 6 represents peroxosulfuric acid (H ₂ SO ₅ ) and peroxodisulfuric acid (H ₂ S ₂ O ₈ ). Examples of persulfuric acid or a salt thereof (C) include alkali metal (Na, K, etc.) salt, alkaline earth metal (Ca, Mg, etc.) salt, ammonium group or organic amine group salt of persulfuric acid. More than seeds may be used. Peroxodisulfuric acid is preferable to peroxosulfuric acid from the viewpoint of stability of the compound, and a salt is preferable to acid in order not to corrode the reaction apparatus. Therefore, a salt of peroxodisulfuric acid is a more preferable compound.

It is known that if the amount of sulfate ion (SO ₄ ²⁻ ) in the cement admixture is too large, it will affect the hardening of the cement composition, and if it is too small, the fluidity retention of the cement composition will be improved. Therefore, 0.01-10 mass% is preferable with respect to a polymer (P), 0.05-5 mass% is more preferable, 0.1-2 mass% is further more preferable. In cement admixture, sulfate ions may precipitate as a salt such as sodium sulfate. Although these are not sulfate ions, they are compounds derived from sulfate ions, and can be easily redissolved by stirring or the like. Therefore, they are calculated by incorporating them into the amount of sulfate ions (SO ₄ ²⁻ ) in the cement admixture.

  The ratio ((AsA-D) / C) of the ascorbic acid compound (AsA-D) and persulfuric acid or a salt thereof (C) used during the polymerization of the polymer (P) shown in claim 6 is a polymer. This is important because it affects the yield of (P) and the performance of the cement admixture using it. By using the ascorbic acid compound (AsA-D) and persulfuric acid or a salt thereof (C) in combination, the polymerization rate of the monomer (IM) is improved, and as a result, the polymer (P) can be obtained in a short time. Good yield. In addition, as shown in Examples and Comparative Examples described later, when the monomer (IM) and the monomer (II-M) are copolymerized, the initiator system described in the present application is compared with a known initiator system. Then, in the initiator system described in the present application, both the monomer (IM) and the monomer (II-M) had a high polymerization rate, and a copolymer having a uniform composition was obtained in a high yield in a short time. . On the other hand, in the known initiator system, the difference in polymerization rate between the monomer (IM) and the monomer (II-M) is large, the composition of the obtained copolymer becomes non-uniform, the polymerization rate When the fast monomer was exhausted, the polymerization sometimes ended and the yield deteriorated. As a result, cement admixtures using polymers obtained with the initiator systems described herein are more fluidly retained in cement compositions than cement admixtures with polymers obtained with known initiator systems. It became excellent.

  ((AsA-D) / C) has an optimum ratio depending on the types of monomers (IM), (II-M) and (III-M) used in the synthesis of the polymer (P), but the molar ratio ((AsA-D) / C) = 1 / 0.25 to 1/20 is preferable, 1/2 to 1/10 is more preferable, and 1/1 to 1/5 is still more preferable.

In order to obtain the polymer (P) of the present invention, the monomer component may be polymerized, and a polymerization initiator system containing an ascorbic acid compound (AsA-D) and persulfuric acid or a salt thereof (C) is used. It is more preferable to use and polymerize. The copolymerization can be performed by a known method such as solution polymerization or bulk polymerization. Copolymerization can be carried out by any of batch, semi-batch, tube-type continuous, stirred tank type, and combinations thereof.
Solvents used for copolymerization include water; alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane and n-hexane; ethyl acetate and the like Ester compounds; ketone compounds such as acetone and methyl ethyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane, etc., but from the solubility of the raw material monomers and the resulting polymer, water and lower alcohols having 1 to 4 carbon atoms It is preferable to use at least one selected from the group consisting of, and among these, it is more preferable to use water as a solvent because the solvent removal step can be omitted.

  In the method for producing the polymer (P) of the present invention, a chain transfer agent may be used as necessary during the polymerization. When a chain transfer agent is used in the polymerization, the molecular weight of the resulting polymer (P) can be easily adjusted.

  The chain transfer agent may be any compound that can adjust the molecular weight. Specifically, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, thioglycolic acid Thiol chain transfer agents such as octyl, octyl 3-mercaptopropionate, 2-mercaptoethanesulfonic acid, n-dodecyl mercaptan, octyl mercaptan, butylthioglycolate; halogens such as carbon tetrachloride, methylene chloride, bromoform, bromotrichloroethane Secondary alcohols such as isopropanol; phosphorous acid, hypophosphorous acid, and salts thereof (sodium hypophosphite, potassium hypophosphite, etc.), sulfurous acid, hydrogen sulfite, dithionic acid, meta heavy Sulfurous acid and its salts (sodium sulfite , Potassium sulfite, sodium hydrogen sulfite, potassium hydrogen sulfite, sodium dithionite, potassium dithionite, sodium metabisulfite, potassium metabisulfite, etc.) lower oxides and salts thereof, etc. .

  Furthermore, in order to adjust the molecular weight of the polymer (P), it is also effective to use a monomer having a high chain transfer property as the monomer (III-M). Specifically, αβ-unsaturated dicarboxylic acid compounds such as maleic acid, fumaric acid, citraconic acid, and derivatives thereof, and salts thereof (more specifically, examples of derivatives include, for example, those having 1 to 30 carbon atoms. Half esters with alcohols; half amides with amines having 1 to 30 carbon atoms; half amides or half esters with amino alcohols having 1 to 30 carbon atoms; alkylene oxides having 2 to 18 carbon atoms on the alcohols; Half-esters with compound (x) added in an average of 1 to 300 mol; Half-amides with a compound obtained by amination of the hydroxyl group at one end of compound (x); Half-esters with polyalkylene glycols having an average addition mole number of 2 to 300; glycols having 2 to 18 carbon atoms Examples of the salts include monovalent metal salts, divalent metal salts, ammonium salts, and the like. Organic amine salts); allyl compounds such as allyl alcohol and allyl sulfonic acid (salt), and their alkylene oxide adducts having an average addition mole number of 2 to 300 and 2 to 18 carbon atoms; methallyl alcohol, methallyl sulfonic acid And methallyl compounds such as (salts), and alkylene oxide adducts having an average addition mole number of 2 to 300 and 2 to 18 carbon atoms.

  Of the chain transfer agents exemplified above, two or more types of chain transfer agents can be used in combination. It is preferable that the chain transfer agent is always present in the reaction system during the polymerization. In particular, when using a thiol chain transfer agent or a lower oxide and a salt thereof as the chain transfer agent, without adding the chain transfer agent all at once, continuously by dropping or the like, It is effective to add over a long time.

  When supplying the chain transfer agent into the reaction system, it is preferable to supply it in a line different from the oxidizing raw material, and in particular, when a thiol chain transfer agent or a lower oxide and a salt thereof are used as the chain transfer agent. For this, it is effective to supply the raw material through a line different from the oxidizing raw material.

  For example, when a thiol chain transfer agent is supplied in the same line as persulfuric acid or a salt thereof (C), both react and lose activity before persulfuric acid or a salt thereof (C) acts as a reaction initiator. Will end up.

  There is no particular limitation on the polymerization temperature, but if the temperature is too low, the solubility of the monomer may decrease, and the monomer or reaction product may be decomposed at a high temperature. 200 degreeC is preferable, 20-150 degreeC is more preferable, and 40-100 degreeC is the most preferable.

  The polymerization pressure may be arbitrary because it has little influence on the radical polymerization reaction, but is appropriately selected according to the boiling point of the solvent or monomer, and is preferably 0.01 to 10 atm.

  The polymerization time is suitably in the range of 0.5 to 12 hours, preferably 0.5 to 10 hours, more preferably 1 to 8 hours. If the polymerization time is too short or too long from this range, it is not preferable because the polymerization rate is lowered and the productivity is lowered.

  When the polymerization is carried out at a pH of 5 or more, the polymerization rate is lowered, and at the same time, the copolymerizability is deteriorated and the dispersibility is lowered when used as a cement admixture. On the other hand, if the pH is too low during the polymerization, the raw material monomer and the produced polymer may be decomposed. Therefore, the pH of the system during polymerization is preferably 1-5. The pH can be adjusted, for example, using an alkaline substance such as inorganic salts such as hydroxides and carbonates of monovalent metals and divalent metals; ammonia; organic amines;

  The polymer (P) thus obtained is used as it is as the main component of the cement dispersant, but if necessary, the polymer (P) may be further neutralized with an alkaline substance. . Preferred examples of such an alkaline substance include inorganic salts such as hydroxides and carbonates of monovalent metals and divalent metals; ammonia; organic amines and the like.

  The weight average molecular weight of the polymer (P) is suitably in the range of 1,000 to 500,000 in terms of polyethylene glycol by gel permeation chromatography (hereinafter referred to as “GPC”). The range of 000 is preferable, and the range of 10,000 to 200,000 is more preferable. By selecting the range of the weight average molecular weight, a cement dispersant exhibiting higher dispersion performance can be obtained. However, since the GPC method is a relative molecular weight measurement method, the value shown above is a value measured under specific GPC conditions shown later.

  The polymer (P) of the present invention can be used as a dispersant in various hydraulic materials, that is, hydraulic materials other than cement such as cement and gypsum. And as a specific example of a hydraulic composition containing a hydraulic material, water and a polymer (P), and further containing fine aggregate (sand, etc.) and coarse aggregate (crushed stone, etc.) as necessary, Cement paste, mortar, concrete, plaster, etc. are mentioned. Among the hydraulic compositions described above, a cement composition that uses cement as the hydraulic material is the most common, but the cement to be used is not particularly limited. For example, Portland cement (ordinary, early strength, very early strength, moderate heat, sulfate resistance and low alkali type of each), various mixed cements (blast furnace cement, silica cement, fly ash cement), white Portland cement, alumina cement, Super fast cement (1 clinker fast cement, 2 clinker fast cement, magnesium phosphate cement), grout cement, oil well cement, low heat cement (low heat blast furnace cement, fly ash mixed low heat blast furnace cement, belite High-concentration cement), ultra-high-strength cement, cement-based solidified material, eco-cement (city waste incineration ash, sewage sludge incineration ash as a raw material), blast furnace slag, fly ash , Cinder ash, clinker ash Husk ash, silica fume, silica powder, may be added fine powders or gypsum limestone powder. In addition to gravel, crushed stone, granulated slag, recycled aggregate, etc., as aggregate, siliceous, clay, zircon, high alumina, silicon carbide, graphite, chromium, chromic, magnesia, etc. The refractory aggregate can be used.

In the cement composition containing the polymer (P) of the present invention, the unit water amount per 1 m ³ , the cement use amount and the water / cement ratio are not particularly limited, and the unit water amount is 100 to 185 kg / m ³ . Amount 250 to 800 kg / m ³ , water / cement ratio = 10 to 70% by weight, preferably unit water amount 120 to 175 kg / m ³ , used cement amount 270 to 800 kg / m ³ , water / cement ratio = 20 to 65% It is recommended and can be used widely from poor blends to rich blends, and is effective for both high-strength concrete with a large amount of unit cement and poor blend concrete with a unit cement amount of 300 kg / m ³ or less.

  In the cement composition containing the polymer (P) of the present invention, the blending ratio of the polymer (P) is not particularly limited, but when used for mortar or concrete using hydraulic cement, the cement weight 0.01 to 2.0%, preferably 0.02 to 1.0%, more preferably 0.05 to 0.5%. By this addition, various preferable effects such as reduction in unit water amount, increase in strength, and improvement in durability are brought about. If the blending ratio is less than 0.01%, the performance is insufficient. Conversely, even if a large amount exceeding 2.0% is used, the effect is practically peaked and disadvantageous in terms of economy. The polymer (P) of the present invention is effective for concrete for concrete secondary products, concrete for centrifugal molding, concrete for vibration compaction, steam-cured concrete, sprayed concrete, and the like. It is also effective for mortar and concrete that require high fluidity, such as self-filling concrete and self-leveling material.

  The polymer (P) of the present invention can be used as a main component of a cement dispersant as it is in the form of an aqueous solution, but is neutralized with a divalent metal hydroxide such as calcium or magnesium to obtain a polyvalent metal salt. After drying, it may be dried, or supported on an inorganic powder such as silica-based fine powder and dried to be pulverized for use. Further, it may be used in combination with a known cement dispersant. Known cement dispersants that can be used in combination are not particularly limited, and various sulfonic acid dispersants having a sulfonic acid group in the molecule, and various polycarboxylic acid types having a polyoxyalkylene chain and a carboxyl group in the molecule. A dispersing agent is mentioned. Examples of the sulfonic acid dispersant include lignin sulfonate; polyol derivative; naphthalene sulfonic acid formalin condensate; melamine sulfonic acid formalin condensate; polystyrene sulfonate; aminoaryl sulfonic acid-phenol-formaldehyde condensate and the like. Examples thereof include sulfonic acid type (see JP-A-1-113419). Examples of the polycarboxylic acid-based dispersant include a copolymer of a polyoxyalkylene mono (meth) acrylic acid ester compound and a (meth) acrylic acid compound and / or a salt thereof as the component (a) ( b) A copolymer of polyoxyalkylene mono (meth) allyl ether compound and maleic anhydride and / or a hydrolyzate and / or salt thereof as component (c), and a polyoxyalkylene mono (meth) allyl as component (c) A dispersant for cement comprising a copolymer of an ether compound and a maleic ester of a polyoxyalkylene compound and / or a salt thereof (see JP-A-7-267705); a poly (meth) acrylic acid as component A Copolymer of oxyalkylene ester and (meth) acrylic acid (salt), specific polyethylene glycol as B component Concrete admixture comprising a specific surfactant as a C component (see Japanese Patent Publication No. 2508113); polyethylene (propylene) glycol ester of (meth) acrylic acid or polyethylene (propylene) glycol mono (meth) Copolymer comprising allyl ether, (meth) allylsulfonic acid (salt), and (meth) acrylic acid (salt) (see JP-A-62-216950); polyethylene (propylene) glycol ester of (meth) acrylic acid , (Meth) allylsulfonic acid (salt), (meth) acrylic acid (salt) copolymer (see JP-A-1-226757); (meth) acrylic acid polyethylene (propylene) glycol ester, (meta ) Allyl sulfonic acid (salt) or p- (meth) a Copolymer comprising ruoxybenzenesulfonic acid (salt) and (meth) acrylic acid (salt) (see Japanese Patent Publication No. 5-36377); copolymer of polyethylene glycol mono (meth) allyl ether and maleic acid (salt) Polymer (see JP-A-4-149056); polyethylene glycol ester of (meth) acrylic acid, (meth) allylsulfonic acid (salt), (meth) acrylic acid (salt), alkanediol mono (meth) acrylate, Polyoxyalkylene mono (meth) acrylate, a copolymer comprising an αβ-unsaturated monomer having an amide group in the molecule (see JP-A-5-170501); polyethylene glycol mono (meth) allyl ether, polyethylene glycol Mono (meth) acrylate, (meth) acrylic acid alkyl ester, (meth) acrylate Copolymers consisting of phosphoric acid (salt), (meth) allylsulfonic acid (salt) or p- (meth) allyloxybenzenesulfonic acid (salt) (see JP-A-6-191918); alkoxy polyoxyalkylene mono Copolymers of allyl ether and maleic anhydride or hydrolysates thereof or salts thereof (see JP-A-5-43288); polyethylene glycol monoallyl ether, maleic acid and monomers capable of copolymerizing with these monomers A copolymer comprising a monomer or a salt thereof or an ester thereof (see Japanese Patent Publication No. 58-38380); a polyoxyalkylene mono (meth) acrylic acid ester monomer, a (meth) acrylic acid monomer and the like Copolymers composed of monomers copolymerizable with other monomers (see Japanese Patent Publication No. 59-18338); having sulfonic acid groups (Meth) acrylic acid ester and, if necessary, a copolymer comprising a monomer copolymerizable therewith or a salt thereof (see JP-A-62-1119147); alkoxypolyoxyalkylene monoallyl ether and anhydrous Esterification reaction product of a copolymer with maleic acid and a polyoxyalkylene derivative having an alkenyl group at the terminal (see JP-A-6-271347); Copolymerization of alkoxypolyoxyalkylene monoallyl ether and maleic anhydride Esterification reaction product of a polymer and a polyoxyalkylene derivative having a hydroxyl group at the terminal (see JP-A-6-298555); a polyoxyalkylene monoester monomer, a (meth) acrylic acid monomer, One or more selected from saturated dicarboxylic acid monomers and (meth) allylsulfonic acid monomers Copolymers of monomers (see JP-A-7-223852); and the like. The known cement dispersants can be used in combination.

  In addition, when using the said well-known cement dispersant together, the compounding weight ratio of the polymer (P) of this invention and a well-known cement dispersant is the kind of a well-known cement dispersant to be used, a mixing | blending, test conditions, etc. Although it is not uniquely determined due to the difference, it is preferably in the range of 5:95 to 95: 5, more preferably 10:90 to 90:10.

Furthermore, the cement dispersant comprising the polymer (P) of the present invention can be used in combination with other known cement additives (materials) exemplified in the following (1) to (20).
(1) Water-soluble polymer substances: polyacrylic acid (sodium), polymethacrylic acid (sodium), polymaleic acid (sodium), unsaturated carboxylic acid polymer such as sodium salt of acrylic acid / maleic acid copolymer; polyethylene Polyoxyethylene or polyoxypropylene polymers such as glycol and polypropylene glycol or copolymers thereof; nonionic such as methylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, carboxyethylcellulose, hydroxypropylcellulose, etc. Cellulose ethers; alkylation of polysaccharides such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, or hydroxya Ionicity in which hydrogen atoms of some or all hydroxyl groups of the killed derivative contain a hydrophobic substituent having a hydrocarbon chain having 8 to 40 carbon atoms as a partial structure and a sulfonic acid group or a salt thereof as a partial structure Polysaccharide derivatives substituted with hydrophilic substituents; yeast glucan, xanthan gum, β-1.3 glucans (which may be either linear or branched, for example, curdlan, baramilon, bakiman, scre Polysaccharides produced by microbial fermentation such as loglucan, laminaran, etc .; polyacrylamide; polyvinyl alcohol; starch; starch phosphate ester; sodium alginate; gelatin; Compounds and the like.
(2) Polymer emulsion: Copolymers of various vinyl monomers such as alkyl (meth) acrylate.
(3) retarder: oxycarboxylic such as gluconic acid, glucoheptonic acid, arabonic acid, malic acid or citric acid, and inorganic salts or organic salts thereof such as sodium, potassium, calcium, magnesium, ammonium, triethanolamine, etc. Acid; monosaccharides such as glucose, fructose, galactose, saccharose, xylose, abitose, repose, isomerized sugar, oligosaccharides such as disaccharides and trisaccharides, oligosaccharides such as dextrin, polysaccharides such as dextran, etc. Sugars such as molasses; sugar alcohols such as sorbitol; magnesium silicofluoride; phosphoric acid and its salts or borate esters; aminocarboxylic acids and salts thereof; alkali-soluble proteins; humic acid; tannic acid; Polyhydric alcohols such as glycerin; aminotri (methylenephos Phosphonic acid and derivatives thereof such as phonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and alkali metal salts and alkaline earth metal salts thereof etc.
(4) Early strengthening agents / accelerators: 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; formate such as formic acid and calcium formate; alkanolamine; alumina cement; calcium aluminate silicate.
(5) Mineral oil-based antifoaming agent: cocoon oil, liquid paraffin, etc.
(6) Fat and oil-based antifoaming agents: animal and vegetable oils, sesame oil, castor oil, alkylene oxide adducts thereof and the like.
(7) Fatty acid-based antifoaming agent: oleic acid, stearic acid, and these alkylene oxide adducts.
(8) Fatty acid ester antifoaming agent: glycerin monoricinoleate, alkenyl succinic acid derivative, sorbitol monolaurate, sorbitol trioleate, natural wax and the like.
(9) Oxyalkylene antifoaming agents: polyoxyalkylenes such as (poly) oxyethylene (poly) oxypropylene adducts; diethylene glycol heptyl ether, polyoxyethylene oleyl ether, polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene (Poly) oxyalkyl ethers such as 2-ethylhexyl ether and oxyethyleneoxypropylene adducts to higher alcohols having 12 to 14 carbon atoms; (poly) oxy such as polyoxypropylene phenyl ether and polyoxyethylene nonylphenyl ether Alkylene (alkyl) aryl ethers; 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2,5-dimethyl-3-hexyne-2,5-diol, 3-methyl-1 − Acetylene ethers obtained by addition polymerization of alkylene oxide to acetylenic alcohol such as tin-3-ol; (poly) oxyalkylene fatty acid esters such as diethylene glycol oleate, diethylene glycol laurate, ethylene glycol distearate; polyoxyethylene (Poly) oxyalkylene sorbitan fatty acid esters such as sorbitan monolaurate and polyoxyethylene sorbitan trioleate; (poly) oxyalkylene alkyl such as sodium polyoxypropylene methyl ether sulfate and sodium polyoxyethylene dodecylphenol ether sulfate ( Aryl) ether sulfate salts; (poly) oxyethylene stearyl phosphates, etc. Sialic sharp emission alkyl phosphate esters; polyoxyethylene such as polyoxyethylene lauryl amine (poly) oxyalkylene alkyl amines; polyoxyalkylene amide.
(10) Alcohol-based antifoaming agent: octyl alcohol, hexadecyl alcohol, acetylene alcohol, glycols and the like.
(11) Amide antifoaming agent: acrylate polyamine and the like.
(12) Phosphate ester antifoaming agent: tributyl phosphate, sodium octyl phosphate, etc.
(13) Metal soap type antifoaming agent: aluminum stearate, calcium oleate, etc.
(14) Silicone antifoaming agent: dimethyl silicone oil, silicone paste, silicone emulsion, organically modified polysiloxane (polyorganosiloxane such as dimethylpolysiloxane), fluorosilicone oil and the like.
(15) AE agent: resin soap, saturated or unsaturated fatty acid, sodium hydroxystearate, lauryl sulfate, ABS (alkyl benzene sulfonic acid), LAS (linear alkyl benzene sulfonic acid), alkane sulfonate, polyoxyethylene alkyl (phenyl) ether , Polyoxyethylene alkyl (phenyl) ether sulfate or a salt thereof, polyoxyethylene alkyl (phenyl) ether phosphate or a salt thereof, protein material, alkenyl sulfosuccinic acid, α-olefin sulfonate, and the like.
(16) Other surfactants: aliphatic monohydric alcohols having 6 to 30 carbon atoms in the molecule such as octadecyl alcohol and stearyl alcohol, and those having 6 to 30 carbon atoms in the molecule such as abiethyl alcohol Intramolecular such as alicyclic monohydric alcohol, dodecyl mercaptan, etc. Intramolecular such as monovalent mercaptan having 6-30 carbon atoms in the molecule, such as nonylphenol, alkylphenol having 6-30 carbon atoms in the molecule, dodecylamine, etc. 10 mol or more of an alkylene oxide such as ethylene oxide or propylene oxide was added to a carboxylic acid having 6 to 30 carbon atoms in the molecule such as an amine having 6 to 30 carbon atoms, lauric acid or stearic acid. Polyalkylene oxide derivatives having an alkyl or alkoxy group as a substituent Alkyldiphenyl ether sulfonates in which two phenyl groups having a sulfone group are ether-bonded; various anionic surfactants; various cationic surfactants such as alkylamine acetate and alkyltrimethylammonium chloride; various nonionics Surfactant; various amphoteric surfactants.
(17) Waterproofing agent: fatty acid (salt), fatty acid ester, oil and fat, silicon, paraffin, asphalt, wax and the like.
(18) Rust preventive: nitrite, phosphate, zinc oxide and the like.
(19) Crack reducing agent: polyoxyalkyl ether and the like.
(20) Expansion material: Ettlingite, coal, etc.
Other known cement additives (materials) include, for example, cement wetting agents, thickeners, separation reducing agents, flocculants, drying shrinkage reducing agents, strength enhancers, self-leveling agents, rust inhibitors, colorants, An antifungal agent etc. can be mentioned. The known cement additives (materials) can be used in combination.

Particularly preferable embodiments include the following <1> to <7>.
<1> A combination in which two components, i) a cement dispersant comprising the copolymer (P) of the present invention, and ii) an oxyalkylene antifoaming agent are essential. In addition, as a compounding weight ratio of the oxyalkylene type | system | group antifoamer of ii), the range of 0.01 to 10 weight% is preferable with respect to the cement dispersant of i).
<2> i) Cement dispersant comprising the copolymer (P) of the present invention, ii) Polyalkylene glycol having a polyoxyalkylene chain in which an alkylene oxide having 2 to 18 carbon atoms is added in an average addition mole number of 2 to 300 Mono (meth) acrylic acid ester monomer, copolymer comprising (meth) acrylic acid monomer and a monomer copolymerizable with these monomers (Japanese Patent Publication No. 59-18338, (See JP-A-7-223852, JP-A-9-2441056, etc.), iii) A combination comprising essentially three components of an oxyalkylene antifoaming agent. The blending weight ratio of the cement dispersant i) and the copolymer ii) is preferably in the range of 5:95 to 95: 5, and more preferably in the range of 10:90 to 90:10. In addition, the blending weight ratio of the oxyalkylene antifoaming agent of iii) is preferably in the range of 0.01 to 10% by weight with respect to the total amount of the cement dispersant of i) and the copolymer of ii).
<3> i) A combination comprising essentially two components: a cement dispersant comprising the copolymer (P) of the present invention, and ii) a sulfonic acid-based dispersant having a sulfonic acid group in the molecule. Examples of the sulfonic acid-based dispersant include amino sulfonic acid-based compounds such as lignin sulfonate, naphthalene sulfonic acid formalin condensate, melamine sulfonic acid formalin condensate, polystyrene sulfonate, and aminoaryl sulfonic acid-phenol-formaldehyde condensate. A dispersant or the like can be used. The blending weight ratio between the cement dispersant i) and the sulfonic acid dispersant ii) is preferably in the range of 5:95 to 95: 5, and more preferably in the range of 10:90 to 90:10.
<4> i) A cement dispersant comprising the copolymer (P) of the present invention, and ii) a combination essentially comprising two components of lignin sulfonate. The blending weight ratio of the cement dispersant i) and the lignin sulfonate salt ii) is preferably in the range of 5:95 to 95: 5, and more preferably in the range of 10:90 to 90:10.
<5> i) A combination consisting essentially of two components: a cement dispersant comprising the copolymer (P) of the present invention, and ii) a material separation reducing agent. Examples of the material separation reducing agent include various thickeners such as nonionic cellulose ethers, a hydrophobic substituent composed of a hydrocarbon chain having 4 to 30 carbon atoms as a partial structure, and an alkylene oxide having 2 to 18 carbon atoms. A compound having a polyoxyalkylene chain added in an average addition mole number of 2 to 300 can be used. The blending weight ratio of the cement dispersant i) and the material separation reducing agent ii) is preferably in the range of 10:90 to 99.99: 0.01, and 50:50 to 99.9: 0. A range of 1 is more preferred. A cement composition comprising this combination is suitable as high fluidity concrete, self-filling concrete, and self-leveling material.
<6> i) A combination comprising two components, i.e., a cement dispersant comprising the copolymer (P) of the present invention, and ii) a retarder. As the retarder, oxycarboxylic acids such as gluconic acid (salt) and citric acid (salt), sugars such as glucose, sugar alcohols such as sorbitol, phosphonic acids such as aminotri (methylenephosphonic acid), etc. can be used. It is. In addition, as a compounding weight ratio of the cement dispersing agent of i) and the retarder of ii), the range of 50: 50-99.9: 0.1 is preferable, and the range of 70: 30-99: 1 is more preferable. .
<7> i) A combination of two components, i.e., a cement dispersant comprising the copolymer (P) of the present invention, and ii) an accelerator. As the accelerator, soluble calcium salts such as calcium chloride, calcium nitrite and calcium nitrate, chlorides such as iron chloride and magnesium chloride, formates such as thiosulfate, formic acid and calcium formate can be used. is there. The blending weight ratio of the cement dispersant i) and the accelerator ii) is preferably in the range of 10:90 to 99.9: 0.1, more preferably in the range of 20:80 to 99: 1. .

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto. In the examples, unless otherwise specified, “%” represents “% by weight” and “part” represents “part by weight”.
<Measurement conditions of molecular weight and molecular weight distribution of polymer>
Equipment: Waters Alliance (2695)
Analysis software: Empower professional + GPC option column manufactured by Waters: TSKgel guard column (inner diameter 6.0 × 40 mm) + G4000SWXL + G3000SWXL + G2000SWXL (each inner diameter 7.8 × 300 mm)
Detector: differential refractometer (RI) detector (Waters 2414), multi-wavelength visible ultraviolet (PDA) detector (Waters 2996)
Eluent: Acetonitrile / sodium acetate (50 mM) ion exchange aqueous solution = 40/60 (volume%) mixed with acetic acid to adjust to pH 6.0 Flow rate: 1.0 ml / min Column / detector temperature: 40 ℃
Measurement time: 45 minutes Sample solution injection amount: 100 μl (eluent solution with sample concentration of 0.5 wt%)
GPC standard sample: polyethylene glycol manufactured by Tosoh Corporation Mp = 272500, 219300, 107000, 50000, 24000, 11840, 6450, 4250, 1470 Calibration curve: cubic equation using Mp value of polyethylene glycol Analysis method: In the obtained RI chromatogram, the horizontally stable portions in the baseline immediately before and after elution of the polymer were connected with a straight line, and the polymer was detected and analyzed. However, when the monomer peak or monomer-derived impurity peak overlaps with the polymer peak and is measured, the peak is separated by vertical division at the most concave or inflection point of the overlap between the peak and the polymer peak, and the molecular weight / The molecular weight distribution was measured. In addition, when a plurality of types of monomer peaks were detected, the polymer and monomer peaks were divided so that the monomer peak with the largest molecular weight was excluded. When oligomers higher than dimer were detected, they were included in the polymer part. The ratio of (polymer peak area) / (polymer peak area + monomer peak area) was defined as “polymer component”, which was used as a measure of the polymer yield.
<Example 1-1>
The reaction apparatus was a thermometer, a stirrer equipped with a blade having a height of 2.5 cm and a width of 11 cm, a dropping apparatus, a nitrogen introduction tube, and a reflux cooling apparatus having a diameter of 16 cm and a 3 L glass reaction apparatus. The conditions were a reaction temperature of 58 ° C., a stirring speed of 200 rpm, and an amount of nitrogen introduced into the system of 100 mL / min. 517.826 g of ethylene oxide adduct of 3-methyl-3-buten-1-ol (average number of moles of ethylene oxide 50), 0.935 g of acrylic acid and 267.241 g of water were charged into the reactor and heated to 58 ° C. did. Subsequently, a mixed aqueous solution of 31.238 g of acrylic acid and 82.759 g of water was added for 3 hours, an aqueous solution prepared by adding water to 3.07 g of ammonium persulfate to a total of 50 g, 3.5 hours, and 0.889 g of L-ascorbic acid and 3 -An aqueous solution prepared by adding water to 2.142 g of mercaptopropionic acid to a total of 50 g was dropped into the reactor at a uniform rate over 3.5 hours. However, the time from the start of heating to the start of dropping was adjusted to be within 2 hours. After completion of all the additions, the polymerization reaction was completed by maintaining the temperature at 58 ° C. for 1 hour, followed by cooling to obtain the cement admixture of Example 1-1. The physical properties of the obtained polymer are shown in Table 1.
<Examples 1-2 to 1-3>
In the same manner as in Example 1-1, only the amount of 3-mercaptopropionic acid was changed, and cement admixtures of Examples 1-2 to 1-3 were obtained. The physical properties of the obtained polymer are shown in Table 1.
<Comparative Example 1-1>
The reaction apparatus was a thermometer, a stirrer equipped with a blade having a height of 2.5 cm and a width of 11 cm, a dropping apparatus, a nitrogen introduction tube, and a reflux cooling apparatus having a diameter of 16 cm and a 3 L glass reaction apparatus. The conditions were a reaction temperature of 58 ° C., a stirring speed of 200 rpm, and an amount of nitrogen introduced into the system of 100 mL / min. 517.826 g of ethylene oxide adduct of 3-methyl-3-buten-1-ol (average number of moles of ethylene oxide 50), 0.935 g of acrylic acid and 267.241 g of water were charged into the reactor and heated to 58 ° C. did. Subsequently, a mixed aqueous solution of 31.238 g of acrylic acid and 82.759 g of water was added for 3 hours, an aqueous solution prepared by adding water to 3.07 g of ammonium persulfate to a total of 50 g, 3.5 hours, and 2.142 g of 3-mercaptopropion in water. Was added dropwise to the reaction apparatus at a uniform rate over a period of 3.5 hours. However, the time from the start of heating to the start of dropping was adjusted to be within 2 hours. After completion of all the additions, the polymerization reaction was completed by maintaining the temperature at 58 ° C. for 1 hour, followed by cooling to obtain a cement admixture of Comparative Example 1-1. The physical properties of the obtained polymer are shown in Table 1.
<Comparative Examples 1-2 to 1-3>
In the same manner as in Comparative Example 1-1, only the amount of 3-mercaptopropionic acid was changed, and cement admixtures of Comparative Examples 1-2 to 1-3 were obtained. The physical properties of the obtained polymer are shown in Table 1.
<Comparative Example 2-1>
The reaction apparatus was a thermometer, a stirrer equipped with a blade having a height of 2.5 cm and a width of 11 cm, a dropping apparatus, a nitrogen introduction tube, and a reflux cooling apparatus having a diameter of 16 cm and a 3 L glass reaction apparatus. The conditions were a reaction temperature of 58 ° C., a stirring speed of 200 rpm, and an amount of nitrogen introduced into the system of 100 mL / min. 517.826 g of ethylene oxide adduct of 3-methyl-3-buten-1-ol (average number of moles of ethylene oxide 50), 0.935 g of acrylic acid and 267.241 g of water were charged into the reactor and heated to 58 ° C. did. Subsequently, an aqueous solution adjusted to a total of 22.879 g by adding water to 1.525 g of 30% aqueous hydrogen peroxide was added to the reactor and heated to 58 ° C. Subsequently, a mixed aqueous solution of 31.238 g of acrylic acid and 59.880 g of water was added for 3 hours to 0.592 g of L-ascorbic acid and 1.785 g of 3-mercaptopropionic acid to adjust the total aqueous solution to 3.5 g. Over time, each was dropped into the reactor at a uniform rate. However, the time from the start of heating to the start of dropping was within 2 hours. After completion of all the additions, the polymerization reaction was completed by maintaining the temperature at 58 ° C. for another hour, followed by cooling to obtain a cement admixture of Comparative Example 2-1. The physical properties of the obtained polymer are shown in Table 1.
<Comparative Examples 2-2 to 2-3>
In the same manner as in Comparative Example 2-1, only the amount of 3-mercaptopropionic acid was changed to obtain cement admixtures of Comparative Examples 2-2 to 2-3. The physical properties of the obtained polymer are shown in Table 1.
<Comparative Example 3-1>
The cement admixture of Comparative Example 3-1 was obtained in the same manner as Comparative Example 1-1. However, the amount of 3-mercaptopropionic acid was changed, the polymerization temperature was set to 70 ° C., the dropping time of the acrylic acid aqueous solution was 5 hours, the dropping time of the persulfuric acid aqueous solution was 5.5 hours, and the 3-mercaptopropionic acid aqueous solution The dropping time was changed to 5.5 hours. The physical properties of the obtained polymer are shown in Table 1.
<Example 2-1>
In a half amount of the aqueous polymer solution produced in Comparative Example 3-1, 0.444 g of L-ascorbic acid was dissolved to obtain the cement admixture of Example 2-1.
<Polymerization result>
From the polymerization results shown in Table 1, Examples 1-1 to 1-3 are polymer components as compared with Comparative Examples 1-1 to 1-3 and Comparative Examples 2-1 to 2-3 with comparable Mw. It was revealed that the polymer yield was good. Moreover, when Example 1-2 and Comparative Example 3-1 are compared, the polymer content is almost the same or Example 1-2 is slightly better, and the polymerization times are 4.5 h and 7 h, respectively. It was clear that it was excellent in productivity.

<Measurement of solid content>
The polymer used for the performance test was measured for non-volatile content by the following procedure, and the concentration was calculated using the non-volatile content as a cement admixture.

About 0.5 g of a cement admixture aqueous solution was weighed into an aluminum cup, and about 1 g of ion-exchanged water was added to spread it uniformly. This was dried at 130 ° C. for 1 hour in a nitrogen atmosphere, and the nonvolatile content was measured from the weight difference before and after drying.
<Concrete test>
Each material was weighed by a concrete raw material, blending, and kneading method shown below so that the kneading amount was 30 L, and the material was kneaded using a pan mixer. Using the cement admixture obtained in Examples 1-1 to 1-3, Example 2-1, Comparative Examples 1-1 to 1-3, Comparative Examples 2-1 to 2-3, and Comparative Example 3-1. The amount of admixture added to obtain a predetermined slump flow value and the slump value, slump flow value, and air amount immediately after kneading, 15 minutes after kneading, and 30 minutes after kneading were evaluated. The blending amount of the cement admixture with respect to the cement mass was calculated by the non-volatile content of the admixture and is shown in Table 2 in terms of mass%. Further, if necessary, a necessary amount of a solid 1 wt% aqueous solution of MA303 (manufactured by Pozoris), which is an AE agent, was blended, and the air amount was adjusted to 4 plus or minus 0.5%.
<Raw materials>
As the cement, ordinary Portland cement (specific gravity: 3.16) manufactured by Ube Mitsubishi Cement Co., Ltd. and Sumitomo Osaka Cement Co., Ltd. was used by mixing them uniformly. Ome crushed stone was used as coarse aggregate, and Ogasayama mountain sand and Kimitsu mountain sand were mixed at a fine ratio of 8/2. Tap water was used as the kneading water.
<Concrete mix>
Unit cement amount: 320.0 Kg / m ³
Unit water amount: 170.0 Kg / m ³ (including admixtures such as polymer and AE agent)
Unit fine aggregate amount: 846.0 Kg / m ³
Unit coarse aggregate amount: 942.0 Kg / m ³
Water cement ratio (W / C): 53.1%
Fine aggregate rate (s / a): 48.0%
<Kneading ingredients>
Cement, fine aggregate, and coarse aggregate were charged into a mixer and kneaded for 10 seconds. The kneading was stopped and a predetermined amount of water and an admixture were charged into the mixer and immediately kneaded for 120 seconds. The kneaded fresh concrete was discharged and an evaluation test was conducted. In the evaluation test, the kneading start time after adding water and admixture was set to zero minutes.
<Evaluation of fresh concrete>
About the obtained fresh concrete, the measurement of the slump value, the slump flow value, and the air quantity was implemented with the following method.
Slump value: JIS A 1101-1998
Slump flow value: JIS A 1150-2001
Air volume: JIS A 1128-1998
The evaluation results are shown in Table 2.
<Concrete evaluation results>
As shown in Table 1, the polymers obtained in Example 1-2, Comparative Example 1-2, and Comparative Example 2-2 have almost the same Mw as about 30,000, and these are used as cement admixtures. The performance was compared. From the concrete test results shown in Table 2, it was found that the concrete immediately after kneading had almost the same slump value and slump flow value with the same amount of admixture added, and the same fluidity was obtained. On the other hand, when comparing the slump loss value / flow loss value (the difference between the slump value / flow value at the measurement time and the slump value / flow value immediately after kneading) indicating the fluidity over time, Example 1-2 It was revealed that the slump loss value and the flow loss value were smaller than those of Comparative Example 1-2 and Comparative Example 2-2, and the performance of maintaining the fluidity of the concrete for a long time was high.

  Examples 1-2 and 2-1 (those obtained by adding L-ascorbic acid to Comparative Example 3-1) and Comparative Example 3-1 have the same polymer content. From the concrete test results shown in Table 2, it was found that the concrete immediately after kneading had almost the same slump value and slump flow value with the same amount of admixture added, and the same fluidity was obtained. On the other hand, the slump loss value and the flow loss value were the results of Example 1-2 <Example 2-1 <Comparative Example 3-1. Since Example 2-1 <Comparative Example 3-1, L-ascorbic acid contributes to improvement of fluidity retention. Moreover, since Example 1-2 <Example 2-1, Example 1-2 in which L-ascorbic acid was added during the production of the copolymer (P) was found to be more excellent in fluid retention. .

Claims (10)

A cement admixture comprising polymer (P), ascorbic acid compound (AsA-D) and sulfate ion (SO ₄ ²⁻ ) as essential components,
The polymer (P) has the following (general formula 1) as a structural unit derived from a polyoxyalkylene group :

(In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or a methyl group; AO is the same or different and represents one or more oxyalkylene groups having 2 or more carbon atoms; In the case of more than seeds, they may be bonded in a block shape or in a random shape, n represents an average added mole number of an oxyalkylene group and represents a number of 1 to 300, and x is an integer of 0 to 2. Y represents 0 or 1, and R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms) .
The ratio of the ascorbic acid compound (AsA-D) to the polymer (P) is 0.001 to 5% by mass, and the sulfate ion (SO ₄ ²⁻ ) is 0.01 to 10% by mass. Cement admixture. And wherein the polymer ascorbic acid compounds for (P) (AsA-D) ratio of 0.01 5% by weight, and Sulfate ion _(SO ^{4 2-)} is 0.05 to 10 wt% The cement admixture according to claim 1. The cement admixture according to claim 1 or 2, wherein y in the (general formula 1) is 0. The polymer (P) is the following (general formula 2) :

(In the formula, R ⁴ , R ⁵ and R ⁶ are the same or different, and a hydrogen atom, a methyl group or — (CH ₂ ) zCOOM ² group (— (CH ₂ ) zCOOM ² represents —COOM ¹ or other — (CH ₂ ) zCOOM ² may form an anhydride), n represents an integer of 0 to 2, M ¹ and M ² are the same or different, and represent a hydrogen atom, an alkali metal atom, an alkaline earth The cement according to any one of claims 1 to 3 , comprising a carboxyl group-containing structural unit (II) represented by a metal atom, an ammonium group or an organic amine group) as an essential structural unit. Admixture. The polyoxyalkylene group derived from the structural unit (I) is the following (formula 3):

(In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or a methyl group; AO is the same or different and represents one or more oxyalkylene groups having 2 or more carbon atoms; In the case of more than seeds, they may be bonded in a block shape or in a random shape, n represents an average added mole number of an oxyalkylene group and represents a number of 1 to 300, and x is an integer of 0 to 2. And y represents 0 or 1, and R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms), and is derived from a polyoxyalkylene monomer (IM) represented by The cement admixture according to any one of claims 1 to 4 . 6. The cement admixture according to claim 5, wherein y in (general formula 3) is 0. The polyoxyalkylene monomer (IM) represented by the general formula (3) is a compound obtained by adding 1 to 300 moles of an alkylene oxide to an unsaturated alcohol. Cement admixture. The carboxyl group-containing structural unit (II) is the following (general formula 4) :

(In the formula, R ⁴ , R ⁵ and R ⁶ are the same or different, and a hydrogen atom, a methyl group or — (CH ₂ ) zCOOM ² group (— (CH ₂ ) zCOOM ² represents —COOM ¹ or other — (CH ₂ ) zCOOM ² may form an anhydride), n represents an integer of 0 to 2, M ¹ and M ² are the same or different, and represent a hydrogen atom, an alkali metal atom, an alkaline earth metalloid atom, to any one of claims 4 to 7, characterized in that a structural unit derived from an unsaturated monomer containing a carboxyl group represented by an ammonium group or an organic amine group) (II-M) The cement admixture described. The cement according to any one of claims 1 to 8 , which is produced by adding an ascorbic acid compound (AsA-D) and persulfuric acid or a salt thereof (C) during the polymerization of the polymer (P). A method for producing an admixture. A cement composition comprising the cement admixture according to any one of claims 1 to 8 .