JP2005225715A - Shrinkage reducing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shrinkage reducing agent capable of giving excellent shrinkage reducing effect to a hydraulic composition such as concrete and coping with both of the control of air volume and freezing and thawing resistance. <P>SOLUTION: The shrinkage reducing agent for the hydraulic composition contains a polymer obtained by using a specific molar ratio of a specific vinyl monomer in which the average additional molar number of alkylene oxide or the like is in a specific range in total of the monomer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a shrinkage reducing agent for hydraulic compositions such as cement, mortar, and gypsum.

  As an additive used for the purpose of preventing dry shrinkage cracking of a cured product of a hydraulic composition, an organic dry shrinkage reducing agent capable of greatly reducing dry shrinkage is known. Since it is important to adjust the amount of air in hydraulic compositions, the amount of air is usually adjusted by the type and amount of AE agent (sometimes called air entraining agent, bubble entraining agent, etc.). ing. When a shrinkage reducing agent is used in a system using an AE agent, a larger amount of air may be entrained than necessary, and a large amount of an antifoaming agent is added to solve this. However, even if the target air amount is achieved by such a technique, entrainment of fine bubbles required for freeze-thaw resistance is prevented. In addition, when a large amount of AE agent is used in combination with a strong shrinkage reducing agent, freeze-thaw resistance is similarly reduced. Therefore, conventionally, the use of a shrinkage reducing agent tends to reduce the freeze-thaw resistance of the hydraulic composition.

As conventional shrinkage reducing agents, those of Patent Documents 1 and 2 are known. Patent Document 1 discloses a method of suppressing air entrainment by using a specific shrinkage reducing agent and a specific antifoaming agent, but the combined use of the antifoaming agent is indispensable, and freeze-thaw resistance The improvement effect was not always sufficient. Patent Document 2 discloses that a polymer obtained by chemically grafting a compound having a drying shrinkage reducing effect is used as a dry shrinkage reducing cement dispersant, but there is a problem in terms of air entrainment, Again, sufficient freeze-thaw resistance cannot be obtained.
JP 2001-294466 A Japanese Patent Laid-Open No. 2001-10853

  The subject of this invention is providing the shrinkage reducing agent which can provide the shrinkage | contraction reduction effect outstanding with respect to hydraulic compositions, such as concrete, and also can make adjustment | control of air quantity and freeze-thaw resistance compatible.

  The present invention is a polymer obtained by using at least one vinyl monomer (a) represented by the following general formula (a1), wherein the proportion of the vinyl monomer (a) is a single amount. More than 50 mol% and not more than 100 mol% in the total amount of the body [however, the average value of the average added mole number of the oxyalkylene group having 2 to 4 carbon atoms and / or the oxystyrene group of the vinyl monomer (a) is 2 or more When the ratio is less than 60, the proportion of the vinyl monomer (a) is more than 50 mol% and not more than 98 mol% in the total amount of the monomers] relates to a shrinkage reducing agent for a hydraulic composition containing a polymer .

[Where,
R ¹¹ , R ¹² : hydrogen atom or methyl group R ¹³ : hydrogen atom or —COO (A ¹¹ O) _n11 X ¹¹ or

m11: 0 to a number of 2 to p11: 0 or a number of 1

A ^11: alkylene group having 2 to 4 carbon atoms and / or phenyl ethylene group n11: an average number of moles added, the number of 2 to 300 (when n11 there are plural number to be 2 to 300 in total Is)
s11, t11: average added mole number, and s11 + t11 is a number from 2 to 300 (however, when there are a plurality of s11, t11, it is a number from 2 to 300 in total)
X ¹¹ represents an alkyl group having 1 to 18 carbon atoms. ]

  Moreover, this invention relates to the additive for hydraulic compositions containing the shrinkage reducing agent of the said invention and the dispersing agent for hydraulic compositions.

  Moreover, this invention relates to the additive for hydraulic compositions containing the shrinkage reducing agent and antifoamer of the said invention.

  The present invention also relates to a hydraulic composition containing the shrinkage reducing agent of the present invention and a hydraulic powder.

  According to the present invention, an excellent shrinkage reduction effect can be imparted to hydraulic compositions such as concrete and mortar, and there is no excessive air entrainment, and both the adjustment of air amount and freeze-thaw resistance can be achieved. A reducing agent is provided.

  When the present inventors include a polymer obtained by using the specific vinyl monomer (a) at a specific ratio in the monomer, there is no excessive air entrainment and excellent freeze-thaw resistance. And found that the shrinkage reduction effect is extremely large.

  Furthermore, in order to obtain such an effect, the polymer includes at least one vinyl monomer (a) and at least one vinyl monomer (b) having an anionic group. It has been found that a copolymer obtained using is preferred.

  That is, the polymer obtained using one or more of the vinyl monomers (a) according to the present invention may be either a homopolymer (homopolymer) or a copolymer (copolymer). Hereinafter, such homopolymers and copolymers are collectively referred to as (co) polymers (A). The vinyl monomer (a), the vinyl monomer (b), and the (co) polymer (A) will be described.

<Vinyl monomer (a)>
Examples of the vinyl monomer (a) represented by the general formula (a1) include methoxypolyethylene glycol, methoxypolypropylene glycol, methoxypolybutylene glycol, methoxypolystyrene glycol, and ethoxypolyethylenepolypropylene glycol. (Meth) acrylic acid, (half) esterified product of maleic acid, etherified product of 3-methyl-3-butenyl alcohol, (meth) allyl alcohol, (meth) acrylic acid, maleic acid, 3- Examples include methyl-3-butenyl alcohol, ethylene oxide (hereinafter referred to as EO) and propylene oxide (hereinafter referred to as PO) adducts to (meth) allyl alcohol.

  The monomer (a) represented by the general formula (a1) includes unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid.

Or an amidated product obtained by adding EO or PO after amidating the unsaturated carboxylic acid with ammonia.

In general formula (a1), R ¹³ is preferably a hydrogen atom, p11 is preferably 1, and m11 is preferably 0. Y ¹¹ is _{^{-O (A 11 O) n11 -X}} 11 are preferred. A ¹¹ is preferably an ethylene group. The monomer (a) is more preferably an esterified product of alkoxy, particularly methoxypolyethylene glycol and (meth) acrylic acid. n11 or s11 + t11 is 2 to 300, more preferably 8 to 300, 20 to 200, 45 to 160, and particularly preferably 60 to 140. In addition, you may mix and use 2 or more types of vinyl-type monomers (a) from which n11 or s11 + t11 differs. The (co) polymer (A) contained in the shrinkage reducing agent of the present invention has an average addition mole number of oxyalkylene groups having 2 to 4 carbon atoms and / or oxystyrene groups of the vinyl monomer (a). mean value (hereinafter, n _AV and hereinafter) is 2 to 300, further 8～300,20～200,45～160, particularly 60 to 140 are preferred. This n _AV corresponds to n11 or s11 + t11 of the general formula (a1) when the vinyl monomer (a) is one kind, but when two or more kinds are used, the n11 or s11 + t11 of each monomer is used. Average value. That is, in the present invention, when one kind of vinyl monomer (a) is used, n11 or s11 + t11 in the general formula (a1) is 2 to 300, and when two or more kinds are used, the general formula ( a1) n11 or s11 + t11 in the and using those 2 to 300 (co) polymer (a) total n _AV needs to select a monomer (a) so as to 2-300. X ¹¹ is preferably an alkyl group having 1 to 8 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms.

<Vinyl monomer (b)>
The vinyl monomer (b) has an anionic group which is an adsorbing group for cement, and the adsorbing group for cement is a group having chelating ability and can have a negative charge. Is. Examples of such an anionic group include a carboxyl group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group. As the vinyl monomer (b), a compound represented by the following general formula (b1) is preferable.

[Where,
R ¹⁴ to R ^16: a hydrogen atom, a methyl group or (CH ₂₎ a _m12 COOM ^12, to form a (CH _{2) m12} COOM ¹² is COOM ¹¹ or other (CH _{2) m12} COOM ¹² and anhydrides In that case, M ¹¹ and M ¹² of those groups are not present.
M ¹¹ and M ^{12 are each a} hydrogen atom or a monovalent metal m12: 0 to 2; ]

  The vinyl monomer (b) represented by the general formula (b1) is (meth) acrylic acid (where (meth) acrylic acid means acrylic acid or methacrylic acid), monocarboxylic acids such as crotonic acid Monomers, dicarboxylic acid monomers such as maleic acid, itaconic acid and fumaric acid, or their anhydrides or monovalent metal salts (for example, alkali metal salts such as sodium salt and potassium salt) or polyvalent metal salts (For example, alkaline earth metal salts such as calcium salt and magnesium salt) are preferable, (meth) acrylic acid, maleic acid, maleic anhydride, more preferably (meth) acrylic acid or sodium salt or potassium salt thereof. Alkali metal salts such as

  As the vinyl-based monomer (b) other than the compound represented by the general formula (b1), (meth) allylsulfonic acid [where (meth) allylsulfonic acid means methallylic acid sulfonic acid or allylsulfonic acid , Styrene sulfonic acid, sulfoethyl methacrylate, acrylamide-t-butyl sulfonic acid, phosphoethyl methacrylate and the like, and salts thereof (monovalent metal salts are preferred), and a single monomer having an anionic group. The body is mentioned. (Meth) allylsulfonic acid and phosphoethyl methacrylate are preferred.

<(Co) polymer (A)>
When the vinyl monomer (a) and the vinyl monomer (b) are used as the constituent monomer of the (co) polymer (A) used in the shrinkage reducing agent of the present invention, a known method is used. Can be manufactured. A plurality of vinyl monomers (a) and vinyl monomers (b) can be used. Examples of the production method include solution polymerization methods exemplified in JP-A-62-78137, US Pat. No. 4,870,120, US Pat. No. 5,137,945 and the like. That is, it can be produced by polymerizing the vinyl monomer (a) and the vinyl monomer (b) in a suitable solvent in the above ratio. For example, in water or a lower alcohol having 1 to 4 carbon atoms, in the presence of a polymerization initiator such as ammonium persulfate or hydrogen peroxide, sodium hydrogen sulfite or mercaptoethanol is added if necessary, and 50 to 100 ° C. in a nitrogen atmosphere. For 0.5 to 10 hours.

  Further, as proposed in JP-A No. 2001-180998, a copolymer mixture produced by changing the monomer molar ratio at least once during the reaction is also the (co) polymer (A) of the present invention. Can be preferably used.

  Moreover, as long as the ratio of the monomer (a) in this invention is satisfy | filled, you may use together monomers other than a vinyl-type monomer (a) and a vinyl-type monomer (b). Examples of the other monomer include acrylonitrile, (meth) acrylamide, styrene, alkyl (meth) acrylate (having 1 to 12 carbon atoms which may have a hydroxyl group) ester, and the like.

That is, the (co) polymer (A) of the present invention is
(A1) a homopolymer comprising one kind of vinyl monomer (a) (A2) a copolymer using a plurality of vinyl monomers (a),
(A3) a copolymer of at least one vinyl monomer (a) and at least one vinyl monomer (b);
(A4) a copolymer of at least one vinyl monomer (a) and at least one monomer other than the vinyl monomer (b), and (A5) a vinyl monomer ( One or more selected from a copolymer of one or more of a), one or more of vinyl-based monomer (b), and one or more of monomers other than vinyl-based monomer (b) N _AV , the proportion of the vinyl monomer (a) in the total amount (100% by weight) of the monomer (hereinafter referred to as “M _a” ) within a specific range. There is something. The (co) polymer (A) preferably includes a copolymer using the vinyl monomer (b), and further includes those selected from the above (A3) from the viewpoint of the effect of reducing drying shrinkage. Is preferred. In that case, the ratio of the vinyl monomer (b) in the total amount of the monomer (hereinafter referred to as M _b ) is less than 50 mol%.

  The weight ratio of the copolymer (A3) in the (co) polymer (A) is 60% by weight or more, further 80% by weight or more, further 95% by weight or more, and particularly 100% by weight. preferable.

  The polymerization reaction may be performed without a solvent or in the presence of a solvent. Solvents include water, lower alcohols such as methanol, ethanol, isopropanol and butanol; aromatic hydrocarbons such as benzene, toluene and xylene; alicyclic hydrocarbons such as cyclohexane; aliphatic hydrocarbons such as n-hexane; acetic acid Examples thereof include esters such as ethyl; ketones such as acetone and methyl ethyl ketone. Among these, water and lower alcohols are preferable from the viewpoint of easy handling and solubility of the monomer and polymer.

  In the polymerization reaction, a polymerization initiator can be added. Examples of the polymerization initiator include organic peroxides, inorganic peroxides, nitrile compounds, azo compounds, diazo compounds, sulfinic acid compounds, and the like. The addition amount of the polymerization initiator is preferably 0.05 to 50 mol% with respect to the total of all monomers.

  In the polymerization reaction, a chain transfer agent can be added. Examples of the chain transfer agent include lower alkyl mercaptan, lower mercapto fatty acid, thioglycerin, thiomalic acid, 2-mercaptoethanol and the like. The reaction temperature of the polymerization reaction is preferably 0 to 120 ° C.

  The obtained polymer or copolymer can be deodorized as necessary. In particular, when a thiol such as mercaptoethanol is used as a chain transfer agent, an unpleasant odor tends to remain in the polymer, and therefore, it is desirable to perform a deodorization treatment.

  Weight average molecular weight of (co) polymer (A) used in the shrinkage reducing agent of the present invention [gel permeation chromatography method, converted to polyethylene glycol, column: G4000PWXL + G2500PWXL (manufactured by Tosoh Corporation), eluent: 0.2M Phosphate buffer / acetonitrile = 7/3 (volume ratio)] is preferably 6,000 to 1,000,000, more preferably 10,000 to 200,000, and particularly preferably 55,000 to 150,000 from the viewpoints of dispersibility and surface hardness.

  The (co) polymer (A) obtained by the above production method can be used even in the acid form, but from the viewpoint of suppressing hydrolysis of the ester due to acidity, it is converted into a salt form by neutralization with an alkali. It is preferable. Examples of the alkali include hydroxides of alkali metals or alkaline earth metals, ammonia, mono, di, trialkyl (2 to 8 carbon atoms) amine, mono, di, trialkanol (2 to 8 carbon atoms) amine, and the like. Can be mentioned. When a (meth) acrylic acid polymer is used, it is preferable to partially or completely neutralize.

  Of the (co) polymer (A), the copolymer is entirely unneutralized, or part or all of it is a metal salt, preferably a monovalent metal salt or a polyvalent metal salt. The salt may be derived from a monomer or may be formed by neutralization after the polymerization reaction. As the monovalent metal salt, an alkali metal salt is preferable, and a sodium salt is more preferable. As the polyvalent metal salt, an alkaline earth metal salt is preferable, and a calcium salt is more preferable. Further, the degree of neutralization is preferably 40 to 100%, more preferably 50 to 90%, and particularly preferably 50 to 80%.

In shrinkage reducing agent of the present invention, the proportion of the vinyl monomer in a total amount of n _AV or monomer (a), further the ratio of the vinyl monomer (b) different (co) polymer (A ) Can be used multiple times. Further, an acid type copolymer that is not a metal salt can be used in combination as appropriate.

<Shrinkage reducing agent>
N _AV of use in shrinkage reducing agent of the present invention (co) polymer (A) is 2 to 300, further 8～300,20～200,45～160, particularly 60 to 140 are preferred. From the viewpoint of shrinkage reduction effect, n _AV is preferably 220 or less, more preferably 200 or less, still more preferably 180 or less, and particularly preferably 150 or less. A (co) polymer having the structure of the (co) polymer (A) of the present invention and having n _AV not in the range of 2 to 300 can be used in combination. the average value of n _AV in is preferably in the range of 2 to 300.

In use in the shrinkage reducing agent of the present invention (co) polymer (A), from when n _AV (co) polymer (A) is less than 2 or 60, M _a is the point of shrinkage reducing effect, More than 50 mol% and less than 98 mol%, preferably more than 60 mol and 95 mol% or less, more preferably 65 mol% or more and 90 mol% or less, and further preferably 70 mol% or more and 85 mol% or less [Pattern 1]. On the other hand, when n _{AV of} the (co) polymer (A) is 60 or more and 300 or less, M _a can be selected from the range of more than 50 mol% and 100 mol% or less, preferably more than 55 mol and less than 95 mol%, more preferably Is from 60 mol% to 90 mol%, more preferably from 65 mol% to 85 mol% [Pattern 2]. In any case, _Mb is less than 50 mol%, further 45 mol% or less, further less than 45 mol%, further 40 mol% or less, further less than 40 mol%, further 35 mol%, and further 30 mol. %, More than 0 mol%, further 5 mol% or more, further 10 mol% or more, and further 15 mol% or more. In the pattern 1, _Mb is preferably more than 0 mol%, and more preferably 2 mol% or more and less than 50 mol%.

In the present invention, the (co) polymer (A) has a molar ratio M _a (mol%) in the total monomer amount of the vinyl monomer (a) and the average value n _AV is −4 M _a. It is preferable that + 280 ≦ n _AV . This range is preferable because excessive dispersibility of the hydraulic composition is not exhibited. Further, from the viewpoint of easy handling of the shrinkage reducing effect as shrinkage reducing agent solution, it is preferable that n _AV ≦ -4M _a +540. Furthermore, from the viewpoint of the shrinkage reduction effect, −4 M _a + 300 ≦ n _AV or n _AV ≦ −4 M _a +420 is preferable. From a comprehensive viewpoint, −4 M _a + 280 ≦ n _AV ≦ −4 M _a +540 is preferable, and −4 M _a + 300 ≦ n _AV ≦ −4 M _a +420 is more preferable. Further, in the relationship between such n _AV and M _a, it is further preferred that n _AV and M _a is in the preferred range of the.

Here, n _AV , M _a and M _b can be calculated from the charging ratio of the monomer (a) and the monomer (b), but by measuring ¹ H-NMR of the shrinkage reducing agent. Can be sought. In the present invention, n _AV , M _a and M _b obtained by measuring ¹ H-NMR are employed as the value of the (co) polymer (A). In the molecular design, when two or more monomers having different n11 are used as the monomer (a), the average value n _AV is Σ [added mole number j × added mole number j A value calculated by mol% of the monomer (a)] / Σ [mol% of the monomer (a) having the added mole number j] can be used as a guide.

  The (co) polymer (A) used in the present invention has an average addition mole number of alkylene oxide and a copolymerization molar ratio of monomers in a specific range as described above, and these are excessive dispersions. It is extremely useful because it does not exhibit properties, has an excellent shrinkage reduction effect, has no excessive air entrainment, and has excellent freeze-thaw resistance.

  The shrinkage reducing agent of the present invention is preferably used in a ratio of 0.01 to 5% by weight, more preferably 0.02 to 3% by weight in solid content with respect to hydraulic compounds such as cement and gypsum.

  By using the shrinkage reducing agent of the present invention in combination with a dispersant having dispersibility with respect to the hydraulic composition, an additive excellent in shrinkage reduction effect and dispersion effect can be obtained. Examples of the dispersant include a polycarboxylic acid copolymer, a naphthalene sulfonic acid formalin condensate, and a melamine sulfonic acid formalin condensate. Preferred are polycarboxylic acid copolymers and naphthalene sulfonic acid formalin condensates, and more preferred are polycarboxylic acid copolymers.

  The weight ratio of the shrinkage reducing agent to the dispersing agent is preferably shrinkage reducing agent / dispersant = 99/1 to 1/99, more preferably 90/10 to 20/80, and particularly preferably 80/20 to 40/60.

  Although it does not compensate for the basic performance of the shrinkage reducing agent of the present invention, it is desirable to add an antifoaming agent from the viewpoint of ease of air amount control. Alcohols, silicones such as dimethyl silicone oil, fluorosilicone oils, mineral oils such as blends of mineral oil and surfactant, phosphate esters such as tributyl phosphate, oleic acid, sorbitan oleic acid monoester, sorbitan olein Examples include acid monoesters, polyethylene glycol fatty acid esters, fatty acids such as polyethylene / polypropylene glycol fatty acid esters or esters thereof, and nonionics such as polypropylene glycol and polyethylene / polypropylene glycol alkyl ethers. Preferred are fatty acids or esters thereof, and more preferred are polyethylene / polypropylene glycol fatty acid esters. The addition amount of the antifoaming agent is preferably 0.0001 to 3% by weight, more preferably 0.005 to 1% by weight, and particularly preferably 0.001 to 0.5% by weight with respect to the hydraulic powder. The shrinkage reducing agent of the present invention is sufficient in reducing shrinkage, adjusting the air amount, and resistance to freezing and thawing even if the amount of antifoaming agent added is small (for example, 0 to 0.003% by weight with respect to hydraulic powder). Effects can be obtained.

  The shrinkage reducing agent of the present invention can take either a solid or liquid form. In the case of a liquid, the (co) polymer (A) is 5 to 70% by weight in terms of solid content, and further 10 to 40% by weight. A liquid composition containing% and water is preferred. In any case, the weight ratio of the (co) polymer (A) of the present invention is 60% by weight or more, further 80% by weight or more, and further 90% by weight in the total solid content of the shrinkage reducing agent of the present invention. % Or more, more preferably 95% by weight or more, and particularly preferably 100% by weight. Such a liquid composition can be obtained as it is from the production process of the (co) polymer (A), and if necessary, the liquid composition contains components such as a dispersant and an antifoaming agent. Can do.

  The shrinkage reducing agent of the present invention is used in a solid content of hydraulic powder such as cement and gypsum, particularly the solid content of the (co) polymer (A), in a ratio of 0.05 to 10% by weight. Preferably, 0.1 to 8% by weight is more preferable, 0.2 to 5% by weight is further preferable, and 0.3 to 2% by weight is particularly preferable.

  An example of the hydraulic composition containing the shrinkage reducing agent of the present invention is 0.05 to 10 parts by weight of the shrinkage reducing agent of the present invention with respect to 100 parts by weight of the hydraulic powder and the hydraulic powder. [As solid content of (co) polymer (A)], 0.05 to 2.0 parts by weight of dispersant for hydraulic composition, 0.001 to 0.5 parts by weight of antifoaming agent, 0. The hydraulic composition containing 0001-0.001 weight part is mentioned.

Production Example 1
Into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introduction tube and a reflux condenser, 410.6 parts by weight of water was charged, and nitrogen substitution was performed. Subsequently, the temperature was raised to 80 ° C. in a nitrogen atmosphere, and then mixed with 897.7 parts by weight of a 60% -methoxypolyethylene glycol monomethacrylate (monomer (a), n11 = 120) aqueous solution and 7.0 parts by weight of methacrylic acid. 3 liquids, 22.7 parts by weight of 5% -2-mercaptoethanol aqueous solution and 24.9 parts by weight of 5% -ammonium persulfate aqueous solution, were dripped simultaneously, and the dripping was completed over 90 minutes for all three liquids. . Next, after aging at the same temperature for 1 hour, 8.3 parts by weight of 5% -ammonium persulfate aqueous solution was dropped over 30 minutes, and after dropping, the mixture was aged at the same temperature for 2 hours. Further, 4.8 parts by weight of 48% -aqueous sodium hydroxide solution was added for neutralization, 2.9 parts by weight of 35% -hydrogen peroxide solution was added, the temperature was raised to 90 ° C., and the same temperature was maintained for 1 hour. After being held, it was cooled to obtain an aqueous solution containing the copolymer of Example 2 in Table 1 below [Na salt (degree of neutralization 70%)]. Moreover, the aqueous solution containing the copolymer except having shown to the following manufacture examples 2-4 was manufactured according to said manufacture example 1.

Production Example 2
(2-1)
It carried out according to the manufacturing method of Unexamined-Japanese-Patent No. 2001-180998. A glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introducing tube and a reflux condenser was charged with 926.0 parts by weight of water, and the temperature was raised to 80 ° C. in a nitrogen atmosphere. Subsequently, 895.0 parts by weight of an aqueous solution of 60% -methoxypolyethylene glycol monomethacrylate (monomer (a) -1, n = 120), 84% -methoxypolyethyleneglycol monomethacrylate (monomer (a) -2, n = 9) 5.4 parts by weight of aqueous solution, 4.7 parts by weight of methacrylic acid, 0.3 part by weight of 75% aqueous phosphoric acid, 0.4 part by weight of 2-mercaptoethanol and 15% -ammonium persulfate aqueous solution 5 parts by weight in 45 minutes, and then 60% -methoxypolyethylene glycol monomethacrylate (monomer (a) -1, n = 120) aqueous solution 1225.0 parts by weight, 84% -methoxypolyethylene glycol monomethacrylate ( Monomer (a) -2, n = 9) 5.4 parts by weight aqueous solution, 4.7 parts by weight methacrylic acid, 75% aqueous phosphoric acid solution 0 It was added dropwise at an aqueous solution of ammonium persulfate 3.0 parts by weight for 45 minutes - 4 parts by weight, 2-mercaptoethanol 0.5 parts by weight mixed solution and 15%. After completion of the dropwise addition, the mixture was aged at 78 ° C. for 60 minutes, and then 3.0 parts by weight of 15% -ammonium persulfate aqueous solution was added dropwise over 5 minutes. The mixture was further aged for 120 minutes at 79 ° C, neutralized by adding 6.4 parts by weight of a 48% -sodium hydroxide aqueous solution, then added with 2.5 parts by weight of 35% -hydrogen peroxide and heated to 90 ° C. After maintaining at the same temperature for 1 hour, the mixture was cooled to obtain an aqueous solution containing the copolymer of Example 20 in Table 1 [Na salt (degree of neutralization 70%)].

(2-2)
Further, an aqueous solution containing the copolymer of Example 21 was produced according to the production method of Example 20. A reaction vessel was charged with 808.5 parts by weight of water and heated to 80 ° C. in a nitrogen atmosphere. Next, 680.0 parts by weight of an aqueous solution of 60% -methoxypolyethylene glycol monomethacrylate (monomer (a) -1, n = 90), 60% -methoxypolyethyleneglycol monomethacrylate (monomer (a) -2, n = 25) A mixed solution of 28.7 parts by weight of aqueous solution, 1.24 parts by weight of methacrylic acid, 0.25 part by weight of 75% aqueous phosphoric acid solution, 0.34 part by weight of 2-mercaptoethanol, and 15% -ammonium persulfate aqueous solution. 0 part by weight was added dropwise over 45 minutes, and then 878.0 parts by weight of 60% -methoxypolyethyleneglycol monomethacrylate (monomer (a) -1, n = 90) aqueous solution, 60% -methoxypolyethyleneglycol monomethacrylate ( Monomer (a) -2, n = 25) 28.7 parts by weight of aqueous solution, 1.24 parts by weight of methacrylic acid, 75% It was added dropwise at an aqueous solution of ammonium persulfate 2.4 parts by weight for 45 minutes - 0.31 parts by weight of an aqueous acid solution, 2-mercaptoethanol 0.42 parts by weight mixed solution and 15%. After completion of the dropwise addition, the mixture was aged at 78 ° C. for 60 minutes, and then 3.0 parts by weight of 15% -ammonium persulfate aqueous solution was added dropwise over 5 minutes. The mixture was further aged for 120 minutes at 79 ° C, neutralized by adding 1.7 parts by weight of a 48% -sodium hydroxide aqueous solution, then added with 2.0 parts by weight of 35% -hydrogen peroxide solution and heated to 90 ° C. After maintaining at the same temperature for 1 hour, the mixture was cooled to obtain an aqueous solution containing the copolymer of Example 21 in Table 1 [Na salt (degree of neutralization 70%)].

Production Example 3
According to the method for producing a water-soluble vinyl copolymer disclosed in JP-A-7-309656, an aqueous solution containing the copolymers of Example 26 and 27 in Table 2 below [Na salt (neutralization degree 70%)] was prepared. Manufactured.

Production Example 4
According to the production method described in paragraph 0042 of JP-A-9-309756, an aqueous solution containing the copolymer [Na salt (degree of neutralization 70%)] of Example 24 in Table 1 below was produced.

In this way, aqueous solutions containing the respective (co) polymers were obtained and used as shrinkage reducing agents. The symbols in the table are as follows.
-MEPEG: methoxy polyethylene glycol monomethacrylate-METPEG: methoxy polyethylene glycol monoallyl ether-MAA: methacrylic acid-AA: acrylic acid-MSA: methallyl sulfonic acid-MAc: methyl acrylate-MA: maleic anhydride-MPE: phosphoethyl Methacrylate Tables 1 and 2 show the molar ratio and average number of moles of alkylene oxide added depending on the amount of copolymer charged. Tables 3 and 4 show the results of actual measurement, shrinkage reduction test and freeze-thaw resistance test. . The physical property measurement method and performance evaluation method are as follows.

(I) n _{AV of} (co) polymer (A)
A shrinkage reducing agent dried under reduced pressure in a nitrogen atmosphere is dissolved in heavy water at a concentration of 3 to 4%, and ¹ H-NMR is measured. From the integrated value of the peak of the alkoxy group (in this case, methoxy group) and the integrated value of the peak of the oxyalkylene group and / or oxystyrene group (in this case, oxyethylene group), the total number of H of the oxyethylene group is determined, The value divided by the number of hydrogen atoms contained in one oxyethylene group is defined as n _AV (actual value) of the shrinkage reducing agent. In addition, the measurement of ¹ H-NMR uses “UNITY-INOVA500” (500 MHz) manufactured by Varian, the number of data points is 64000, the measurement range is 10000.0 Hz, the pulse width (45 ° pulse) is 60 μsec, the pulse delay time is 30 sec, and the measurement is performed. The measurement was performed at a temperature of 25.0.

(II) M _a and M _{b of} (co) polymer (A)
A shrinkage reducing agent dried at room temperature in a nitrogen atmosphere is dissolved in heavy water, and ¹ H-NMR is measured (conditions are the same as above). From the integrated value s of the peak of the alkoxy group (in this case, methoxy group) and the integrated value S of the peak of the hydrogen atom or alkyl group (in this case, methyl group) of the main chain, [(S−s) / S] × 100 is calculated to determine the ratio M _b (measured value) of the (co) polymer (a) the total vinyl monomer ratio M _a (measured value) (a) and vinyl monomer (b) .

(1) Drying shrinkage test (1-1) Mortar blended cement: 800 g (1: 1 mixture of ordinary Portland cement manufactured by Taiheiyo Cement Co., Ltd. and ordinary Portland cement manufactured by Sumitomo Osaka Cement Co., Ltd., specific gravity 3.16)
Tap water: 320 g (including shrinkage reducing agent, dispersing agent and antifoaming agent if necessary)
Sand: 1750g (silica sand)

(1-2) Preparation of kneading water To tap water in the above mortar formulation, shrinkage reducing agent (used as an aqueous solution), if necessary, dispersing agent [methoxypolyethylene glycol monomethacrylate (EO average addition mole number 85) 20 mol Copolymer having an average addition mole number of 56,000 obtained by copolymerization of 80% by mole of methacrylic acid] and fatty acid ester antifoaming agent Foam Rex 797 (manufactured by Nikka Chemical Co., Ltd.) with respect to cement. 001 wt% was added and stirred until uniform.

(1-3) Evaluation item (1-3-1) Mortar fluidity To the mortar having the above composition, the kneading water prepared above is added (dispersant solid content 0.05 to 0.20% by weight based on cement). The mortar was prepared using a mortar mixer defined in JIS R 5201 so that the mortar fluidity was 220 to 270 mm. The mortar flow (unit: mm) was measured using a mini slump cone obtained by reducing the slump cone defined in JIS A 1101 to a scale of 1/2 and used as an index of mortar flowability.

(1-3-2) Drying shrinkage reduction performance Using the mortar obtained in (1-3-1), a mortar specimen was prepared by the method shown in JIS R 5201. The mortar specimens were removed from the molds after 24 hours and subjected to water curing for 7 days. Thereafter, as shown in JIS A 1129, the base length was taken and stored in a constant temperature and humidity chamber. After 4 weeks, the length of the basal length was measured. The measurement was performed by the contact gauge method shown in JIS A 1129. The length change rate was obtained from each measured value, and the shrinkage reduction performance was evaluated.

(2) Freezing and thawing resistance test (2-1) Concrete blended cement: 12.39 kg (1: 1 mixture of ordinary Portland cement manufactured by Taiheiyo Cement Co., Ltd. and ordinary Portland cement manufactured by Sumitomo Osaka Cement Co., Ltd., specific gravity 3.16)
Tap water: 4.95 kg (including additives, antifoaming agent and bubble entraining agent if necessary)
Sand: 23.79 kg (land sand from Kimitsu, Chiba Prefecture, surface dry specific gravity 2.63)
Gravel: 28.8kg (Mt. Torigata limestone, surface dry specific gravity 2.72)

(2-2) Preparation of kneading water To tap water in the above concrete blend, shrinkage reducing agent (used as an aqueous solution), if necessary dispersing agent [methoxypolyethylene glycol monomethacrylate (EO average added mole number 85) 20 mol Copolymer having an average addition mole number of 56,000 copolymerized with 80% by mole of methacrylic acid] and 0.001% by weight of fatty acid ester antifoaming agent Foam Rex 797 (manufactured by Nikka Chemical Co., Ltd.) with respect to cement. The bubble entraining agent Mighty AE-03 (manufactured by Kao Corporation) was added and stirred until uniform.

(2-3) Preparation of concrete Gravel, about half amount of sand, cement, and remaining sand were put into a tilting drum mixer (manufactured by Dragonfly Industry Co., Ltd.) in this order. Empty kneading (25 rpm) was performed for 10 seconds. Next, the above kneading water was quickly added and kneaded for 180 seconds (25 rpm).

(2-4) Evaluation item (2-4-1) Slump flow measurement About the concrete obtained above, the slump flow was measured based on JISA1101. At that time, the addition amount of the dispersant was appropriately adjusted in the range of 0.05 to 0.20% by weight of the solid content with respect to the cement so that the slump flow was 350 to 450 mm. In addition, the thing which does not use a dispersing agent employ | adopted the slump flow value as it is when kneading and adding predetermined amount of water.

(2-4-2) Air amount measurement The air amount of the concrete obtained above was measured based on JIS-A1118. At that time, the amount of the bubble entraining agent added was adjusted so as to be 4.5 to 6.0% by volume.

(2-4-3) Freeze-thaw resistance The freeze-thaw resistance of the concrete obtained above was measured based on JIS-A1148. If the relative dynamic elastic modulus at 300 cycles is 75% or more, ◎, if it is 60% or more and less than 75%, ○, if the relative dynamic elastic modulus in 300 cycles is less than 60% or less than 300 cycles, the relative dynamic elastic modulus is 60%. When it became less than, it was set as x. When the amount of air is the same, the one having better freeze-thaw resistance means that fine bubbles required for freeze-thaw resistance are appropriately mixed.

* In Example 28, no antifoaming agent was added.
** In Example 29, no dispersant was added.
*** All neutralized products have a neutralization degree of 70%.

(Note) The addition ratios in Tables 3 and 4 are weight percentages of the shrinkage reducing agent (effective amount of copolymer) with respect to the cement in the hydraulic composition.

  Comparative Example 1 has appropriate mortar fluidity, but did not show the shrinkage reducing effect. In Comparative Examples 2 and 3, since the addition rate was the same level as that of the shrinkage reducing agent, the dispersibility was excessively exhibited and the mortar was in a separated state. Comparative Examples 4 and 5 did not show the shrinkage reducing effect. Comparative Example 6 showed an effect of reducing shrinkage, but its freeze-thaw resistance was small. On the other hand, the shrinkage reducing agents of the examples exhibited an excellent shrinkage reducing effect, did not cause excessive air entrainment to concrete, and exhibited freeze-thaw resistance. These effects of the present invention were also obtained in combination with a small amount of antifoaming agent.

Claims (8)

A polymer obtained by using at least one vinyl monomer (a) represented by the following general formula (a1), wherein the proportion of the vinyl monomer (a) is in the total amount of the monomers More than 50 mol% and less than 100 mol% [However, when the average added mole number of the oxyalkylene group having 2 to 4 carbon atoms and / or the oxystyrene group of the vinyl monomer (a) is 2 or more and less than 60 The proportion of vinyl monomer (a) is more than 50 mol% and not more than 98 mol% in the total amount of monomers]. A shrinkage reducing agent for hydraulic compositions containing a polymer.

[Where,
R ¹¹ , R ¹² : hydrogen atom or methyl group R ¹³ : hydrogen atom or —COO (A ¹¹ O) _n11 X ¹¹ or

m11: 0 to a number of 2 to p11: 0 or a number of 1

A ^11: alkylene group having 2 to 4 carbon atoms and / or phenyl ethylene group n11: an average number of moles added, the number of 2 to 300 (when n11 there are plural number to be 2 to 300 in total Is)
s11, t11: average added mole number, and s11 + t11 is a number from 2 to 300 (however, when there are a plurality of s11, t11, it is a number from 2 to 300 in total)
X ¹¹ represents an alkyl group having 1 to 18 carbon atoms. ] The polymer includes a copolymer obtained by using one or more of the vinyl monomers (a) and one or more of the vinyl monomers (b) having an anionic group. 1 shrinkage reducing agent. The shrinkage reducing agent according to claim 2, wherein the anionic group of the vinyl monomer (b) is at least one selected from a carboxyl group, a sulfonic acid group, a phosphoric acid group, and a phosphonic acid group. The water according to claim 2 or 3, wherein the polymer is a copolymer obtained by using one or more of the vinyl monomers (a) and one or more of the vinyl monomers (b). Shrinkage reducing agent for hard composition. The shrinkage reducing agent according to any one of claims 2 to 4, wherein the vinyl monomer (b) is a compound represented by the following general formula (b1).

[Where,
R ^{14 to} R ^{16 are a} hydrogen atom, a methyl group, or (CH ₂ ) _m12 COOM ¹² , and (CH ₂ ) _m12 COOM ¹² forms an anhydride with COOM ¹¹ or other (CH ₂ ) _m12 COOM ¹² In that case, M ¹¹ and M ¹² of those groups are not present.
M ¹¹ and M ^{12 are each a} hydrogen atom, a monovalent metal or a polyvalent metal m12: 0 to 2; ] The additive for hydraulic compositions containing the shrinkage reducing agent in any one of Claims 1-5, and the dispersing agent for hydraulic compositions. The additive for hydraulic compositions containing the shrinkage reducing agent and antifoamer in any one of Claims 1-5. A hydraulic composition comprising the shrinkage reducing agent according to claim 1 and hydraulic powder.