JP4937166B2 - Dispersion retention agent for hydraulic composition - Google Patents

Description

  The present invention relates to a dispersion retention agent for hydraulic compositions.

  In order to impart fluidity to hydraulic compositions such as concrete, admixtures such as naphthalene-based, melamine-based, aminosulfonic acid-based, and polycarboxylic acid-based materials (high performance water reducing agents) are used. For admixtures such as water reducing agents, various performances are required such as imparting fluidity to hydraulic compositions, fluidity retention (flow retention), prevention of cure delay, etc. Improvements are also proposed from this perspective.

In Patent Document 1, a concrete admixture comprising a copolymer having a specific ethylenically unsaturated monomer unit and an ethylenically unsaturated carboxylic acid ester unit as a structural unit can be used in combination with a high-performance water reducing agent. It is disclosed. Patent Document 2 discloses a cement comprising a terpolymer of an ethylene monomer having a polyoxyalkylene group, an unsaturated organic acid monomer, and a monomer that can be hydrolyzed in an alkaline aqueous solution. It is disclosed that the admixture is excellent in slump retention and fluidity. Patent Document 3 includes a copolymer of a polyalkylene glycol mono (meth) acrylate ester monomer, a mono (meth) acrylate ester monomer, and a carboxylic acid monomer having an unsaturated bond. It is disclosed that a cement dispersing aid is excellent in workability, fluidity and strength development.
JP-A-10-81549 JP-A-2005-330129 JP 2003-286057 A

  Patent Documents 1 to 3 disclose a technique for maintaining the fluidity and viscosity of a hydraulic composition, but the fluid retention performance is desired to be further improved with respect to recent changes in material circumstances. Yes.

  An object of the present invention is to provide a dispersion retention agent for a hydraulic composition that exhibits excellent fluidity retention.

In the present invention, the monomer 1 represented by the general formula (1), the monomer 2 represented by the general formula (2), and the monomer 3 represented by the general formula (3) are polymerized. A dispersion holding agent for a hydraulic composition comprising a copolymer having a weight average molecular weight of 30,000 to 60,000,
At least a part of the monomer 2 has a relationship of [log P value of alcohol compound R ⁵ —OH corresponding to R ⁵ in general formula (2) / molecular weight Mw of monomer (2)] <− 0.003. The filling,
The present invention relates to a dispersion holding agent for a hydraulic composition, wherein monomer 1 is 25 to 78% by weight and monomer 3 is 0 to 18% by weight among the constituent monomers of the copolymer.

Wherein, R ¹ to R ³ each represent a hydrogen atom or a methyl group, AO represents an oxyalkylene group having 2 to 4 carbon atoms, n is an average addition mole number of AO, the number of 20 to 30 R ⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, q represents an integer of 0 to 2, and p represents 0 or 1. ]

[Wherein R ⁵ is a hydrocarbon group which may contain a hetero atom having 1 to 4 carbon atoms. ]

Wherein, R ⁶ to R ⁸ are each a hydrogen atom, a methyl group or ^{_{(CH 2) s COOM 2,}} (CH 2) s COOM 2 is COOM ¹ or another (CH _{²⁾ s} COOM ₂ and anhydrous In this case, M ¹ and M ² of those groups are not present. s represents the number of 0-2. M ¹ and M ² each represent a hydrogen atom, an alkali metal, an alkaline earth metal (1/2 atom), an ammonium group, an alkyl ammonium group, a substituted alkyl ammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group. ]

  ADVANTAGE OF THE INVENTION According to this invention, the dispersion | distribution holding | maintenance agent for hydraulic compositions which exhibits the outstanding fluid retainability with respect to a hydraulic composition is provided.

  Patent Documents 1 and 2 aim to achieve both initial fluidity and fluidity retention. Patent Document 2 examines a difference in holding performance due to a difference in polymerization method. Patent Document 2 has a general disclosure that the weight average molecular weight of the polymer is 5,000 to 100,000, but the specific disclosure in the examples is only 19000 to 28000.

  Further, Patent Document 3 aims at workability, fluidity and strength development, and describes that when the weight average molecular weight exceeds 30000, the effect of improving the gap passage property of concrete is not exhibited because it exhibits an aggregating action. .

  In the present invention, by using a copolymer having a specific range of molecular weight obtained by copolymerizing specific monomers 1 to 3 at a specific ratio, a dispersion retention agent that exhibits fluidity retention that cannot be achieved by the conventional technology. Is obtained.

<Monomer 1>
The monomer 1 is an unsaturated polyalkylene glycol monomer such as a polyalkylene glycol monoester monomer and a polyalkylene glycol alkyl ether monomer, and in the monomer 1, the general formula (1) AO in it represents an oxyalkylene group having 2 to 4 carbon atoms and includes at least one selected from the group consisting of an oxyethylene group, an oxypropylene group, and an oxybutylene group, and among them, an oxyethylene group is preferable. n is the average added mole number of AO and represents a number of 20 to 30, preferably 20 to 28, more preferably 21 to 26, and still more preferably 22 from the viewpoint of versatility of initial dispersibility and fluidity retention. -25, even more preferably 22-24. R ⁴ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of fluidity retention.

  As monomer 1, methoxypolyethylene glycol, methoxypolyethylenepolypropylene glycol, ethoxypolyethyleneglycol, ethoxypolyethylenepolypropyleneglycol, propoxypolyethyleneglycol, propoxypolyethylenepolypropyleneglycol, etc., one-end alkyl-capped polyalkyleneglycol and acrylic acid or methacrylic acid Esterified products, addition products of ethylene oxide or propylene oxide to acrylic acid or methacrylic acid, etherification products of the above-mentioned one-end alkyl-blocked polyalkylene glycol and (meth) alkenyl alcohol, and alkylene having 2 to 4 carbon atoms to alkenyl alcohol An oxide adduct or the like can be used. Specifically, ω-methoxypolyethylene glycol monomethacrylate, ω-methoxypolyethyleneglycol monoacrylate, polyoxyethylene monoallyl ether, ω-methoxypolyethyleneglycol monoallyl ether, poly (3-methyl-3-buten-1-ol) Examples include oxyethylene monoallyl ether. From the viewpoint of fluidity retention, esterified products of one-end alkyl-blocked polyalkylene glycol and acrylic acid or methacrylic acid are preferred, preferably ω-methoxypolyethylene glycol monomethacrylate, ω-methoxypolyethyleneglycol monoacrylate, ω- Methoxy polyethylene glycol monomethacrylate is more preferred.

<Monomer 2>
The monomer 2 is an acrylate monomer and can be regarded as an ester of an alcohol compound represented by acrylic acid and R ⁵ —OH in terms of structure. R ⁵ has 1 to 4 carbon atoms, Preferably it is a hydrocarbon group which may contain 2 to 3 heteroatoms. A hetero atom is an oxygen atom, a nitrogen atom or the like.

In the present invention, as at least a part of the monomer 2, a specific monomer among the monomers represented by the general formula (2) is used. That is, as at least part of the monomer 2, the general formula (2) R ⁵ in a logP value of R ⁵ -OH corresponding to R ⁵ in the general formula (2), the molecular weight of the monomer 2 A compound in which Mw is [log P value of R ⁵ —OH / molecular weight Mw of monomer (2)] <− 0.003 (hereinafter referred to as monomer 2-1) is used. Further, in addition to the monomer 2-1, that is, the monomer 2 having a [R ⁵ —OH logP value / monomer (2) molecular weight Mw] ≧ −0.003 is obtained. -2. Examples of R ⁵ —OH satisfying the relationship of monomer 2-1 include ethylene glycol (log P value: −1.369), glycerin (log P value: −1.538), and the like. That is, examples of R ⁵ include a hydroxyethyl group and a glycerol group. A monomer having these groups as R ⁵ is preferably used as at least a part of the monomer 2. The ratio of the monomer 2-1 is preferably 30% by mole or more, more preferably 50% by mole or more in the monomer 2 from the viewpoints of versatility with respect to the type of hydraulic powder, and also flow retention and viscosity. 70 mol% or more is more preferable, 90 mol% or more is more preferable, and substantially 100 mol% is still more preferable.

As monomer 2-1, methyl acrylate (log P value of R ⁵ —OH (hereinafter also simply referred to as log P): −0.764, molecular weight Mw of monomer (2) (hereinafter also simply referred to as Mw) : 86.1, log P / Mw: -0.0089), 2-hydroxyethyl acrylate (log P: -1.369, Mw: 116.1, log P / Mw: -0.0118), 2-hydroxypropyl acrylate ( log P: -1.062, Mw: 130.2, log P / Mw: -0.0081), 3-hydroxypropyl acrylate (log P: -1.037, Mw: 130.2, log P / Mw: -0.0080) ), Methoxyethyl acrylate (log P: -0.6064, Mw: 130.2, log P / Mw: -0.0047), n-butyl acrylate logP: -1.164, Mw: 144.2, logP / Mw: -0.0081), and the like.

  As the monomer 2-1, 2-hydroxyethyl acrylate is preferable from the viewpoint of maintaining fluidity. Examples of the monomer 2-2 include ethyl acrylate (log P: -0.235, Mw: 100.1, log P / Mw: -0.0023). Two or more types of monomers may be used for each of the monomer 2-1 and the monomer 2-2.

[Monomer 3]
Monomer 3 are the compounds of formula (3), R ⁶ ~R ⁸ are each a hydrogen atom, a methyl group or ^{_{(CH 2) s COOM 2,}} (CH 2) s COOM 2 is COOM ¹ or other (CH ₂ ) _s COOM ² and an anhydride may be formed. In that case, M ¹ and M ² of those groups do not exist. s represents the number of 0-2. R ⁶ is preferably a hydrogen atom, and R ⁷ is preferably a methyl group. R ⁸ is preferably a hydrogen atom or (CH ₂ ) _s COOM ² .

M ¹ and M ² are each a hydrogen atom, an alkali metal, an alkaline earth metal (1/2 atom), an ammonium group, an alkyl ammonium group, a substituted alkyl ammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group. M ¹ and M ² are each preferably a hydrogen atom or an alkali metal.

  Specifically, monocarboxylic acid monomers such as (meth) acrylic acid and crotonic acid, dicarboxylic acid monomers such as maleic acid, itaconic acid and fumaric acid, or anhydrides or salts thereof (for example, alkalis) Metal salt, alkaline earth metal salt, ammonium salt, mono-, di-, trialkyl (carbon number 2 to 8) ammonium salt optionally substituted with hydroxyl group) or ester, preferably (meth) acrylic acid, Maleic acid, maleic anhydride, more preferably (meth) acrylic acid or an alkali metal salt thereof. In addition, (meth) acrylic acid means acrylic acid and / or methacrylic acid (hereinafter the same).

  In the copolymer serving as the dispersion holding agent of the present invention, the fluidity of the hydraulic composition can be maintained over time from the initial addition to the hydraulic composition by introducing the monomer 2-1. This is because the monomer 2-1 has an acrylic acid ester structure before addition to the hydraulic composition, so that hydrolysis of the ester bond proceeds with time after the addition, and the carboxylic acid type or carboxylate salt. It is assumed that the copolymer gradually adsorbs on the surface of the hydraulic powder and maintains the dispersion of the hydraulic powder to offset the increase in viscosity due to hydration of the hydraulic powder. The Even if it has a similar structure, an effect like that of the monomer 2-1 cannot be obtained with an ester of methacrylic acid or an alkylene oxide adduct thereof, which is harder to hydrolyze than acrylic acid. Further, the effect as in the case of the monomer 2-1 cannot be obtained even with the monomer 2-2. As this reason, it is estimated that the hydrolyzability of the monomer 2-2 is inferior to the monomer 2-1.

  Moreover, in the copolymer used as the dispersion holding agent of the present invention, by introducing the monomer 3, a predetermined amount of adsorption can be initially shown and initial fluidity can be shown. However, since the content of the monomer 3 affects the flow retention, in the present invention, 20% by weight is used as the upper limit in the constituent monomer of the copolymer. Furthermore, the content is preferably less than the content (% by weight) of monomer 2.

In addition, as for the monomer 2-1, the molecular weight of the monomer 2-1 and the log P of the compound represented by R ⁵ —OH composed of the substituent R ⁵ and the hydroxyl group OH of the monomer 2-1 ( It was found that there is a correlation between the water / octanol distribution coefficient (hereinafter logP refers to logP of the compound unless otherwise specified) and the speed of expression of the dispersibility of the hydraulic powder. That is, the hydrolyzability varies depending on the ester substituent of acrylic acid, and hydrolyzation has steps of nucleophilicity of water molecule to ester and elimination of alcohol. It was thought that ease contributed. The hydrolysis rate decreases as the molecular weight of the monomer increases (the steric hindrance increases), and the hydrolysis rate increases as the hydrophilicity (log P) value of the hydrolysis group of the alcohol compound constituting the ester decreases. Therefore, logP was normalized by the molecular weight Mw of the acrylate ester, and used as an index of the efficiency of the introduced group (carboxyl group production rate). Therefore, the smaller the value of logP / molecular weight Mw, the greater the hydrolyzability of monomer 2-1. In the present invention, this value is −0.003 or less, preferably −0.009 or less, more preferably −0.010 or less, and further preferably −0.011 or less. logP can be obtained as a ClogP value using the software of CS Chem Draw Ultra (Ver. 8.0) (distributed Cambridge Software). For example, the software is executed on a personal computer running Windows (registered trademark) XP. it can.

  Conventionally, if the AO average addition mole number of the polycarboxylic acid polymer is not large to some extent, there is no contribution of fluidity due to steric repulsion, and the increase in adsorbing groups due to hydrolysis is considered to have a small fluidity retention effect over time. (Patent Document 2, paragraph 0010). Moreover, when the AO average added mole number is large, the viscosity tends to increase with time. However, as a result of detailed examination of the copolymer structure, fluidity and retention performance, the present inventor adsorbed over time in a highly alkaline environment when kneaded with a steric repulsion unit (AO average addition unit), cement, and the like. Dispersion retention agent with excellent fluidity retention by adjusting the balance between the specific unit that generates the group and the initial adsorption unit (carboxylic acid unit) and optimizing the molecular weight within the range of the specific alkylene oxide average addition unit Was completed.

<Copolymer>
In the copolymer of the present invention, monomer 1 is 25 to 78% by weight and monomer 3 is 0 to 18% by weight in the constituent monomers of the copolymer. This ratio may be the ratio at the time of charging the monomer (hereinafter, the other ratios for the monomer are the same).

  Among the constituent monomers of the copolymer according to the present invention, the monomer 1 is preferably 28 to 78% by weight, and more preferably 40 to 70% by weight.

  In the copolymer of the present invention, two or more monomers 1 having different n can be used in combination. In that case, the value of n of the monomer 1 is the average value (depending on the molar fraction) of the monomers 1 having different n (the same applies hereinafter).

  In the constituent monomer of the copolymer according to the present invention, the monomer 2 is preferably 10 to 70% by weight, more preferably 15 to 60% by weight, and further preferably 25 to 40% by weight.

  Among the constituent monomers of the copolymer according to the present invention, the monomer 3 is preferably 0 to 15% by weight, more preferably 5 to 15% by weight, and more preferably 6 to 15% by weight.

  The total of monomer 1, monomer 2 and monomer 3 in all the constituent monomers of the copolymer is 90% by weight or more, further 95% by weight or more, and further 98% by weight from the viewpoint of fluidity retention. % Or more is preferable.

  Further, the total of monomer 2 and monomer 3 in all the constituent monomers of the copolymer is preferably 22 to 72% by weight in all the constituent monomers from the viewpoint of fluidity retention, Preferably it is 30 to 65% by weight.

  Further, from the viewpoint of fluidity retention, the weight of monomer 2 in the total weight of monomer 1, monomer 2 and monomer 3 is greater than the weight of monomer 3, that is, It is preferable that the weight ratio (X) of the monomer 2 is larger than the weight ratio (Y) of the monomer 3 [(X)> (Y)] among the constituent monomers of the coalescence. Specifically, these weight ratios are (X) / (Y) ≧ 1.0, further (X) / (Y) ≧ 1.2, and further (X) / (Y) ≧ 1.5. It is preferable.

  The weight ratio of monomer 1, monomer 2 and monomer 3 (monomer 1 / monomer 2 / monomer 3) is preferably 25 to 78/10 to 70 from the viewpoint of fluidity retention. / 0-18, more preferably 28-78 / 15-60 / 0-15, still more preferably 35-75 / 20-50 / 0-15, still more preferably 40-70 / 25-40 / 5-15 It is. In any case, as described above, it is preferable that (X)> (Y). In addition, in terms of monomer 1 / monomer 2 / monomer 3, for example, 25 to 78/10 to 70/0 to 18, monomer 1 is 25 to 78, and monomer 2 is 10 to 10. 70, meaning that monomer 3 is 0-18.

  Moreover, when manufacturing the copolymer which concerns on this invention, you may copolymerize the monomer 4 copolymerizable with the monomers 1-3. The monomer 4 is 5% by weight or less, preferably 2.5% by weight or less, more preferably 1.% by weight or less in the total constituent monomers of the copolymer, from the viewpoint of suppressing the initial fluidity and flow retention performance. 0% by weight or less.

  As the monomer 4, methacrylic acid phosphoric acid di-[(2-hydroxyethyl) methacrylic acid] ester, phosphoric acid di-[(2-hydroxyethyl) acrylic acid] ester, phosphoric acid mono (2-hydroxy) And phosphoric acid esters such as ethyl) methacrylic acid ester, phosphoric acid mono (2-hydroxyethyl) acrylic acid ester, polyalkylene glycol mono (meth) acrylate acid phosphoric acid ester, and any of these. One or more alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts, and anhydrous compounds such as maleic anhydride may be used.

  As other monomers 4, methacrylic acid esters such as methyl methacrylate and 2-hydroxyethyl methacrylate, allyl sulfonic acid, methallyl sulfonic acid, any of these alkali metal salts, alkaline earth metal salts, ammonium salts, or amines Salt, (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2- (meth) acrylamide-2-metasulfonic acid, 2- (meth) acrylamide-2-ethanesulfonic acid , 2- (meth) acrylamide-2-propanesulfonic acid, styrene, styrenesulfonic acid and other strong acid acid groups or monomers having a neutralizing group thereof. These monomers may be copolymerized for adjusting the molecular weight of the copolymer, for example. The acid groups of these strong acids exist as stable salts in the hydraulic composition and do not function as adsorbing groups to hydraulic powders such as cement.

  The copolymer in the present invention can be produced by a known method. Examples thereof include solution polymerization methods described in JP-A-62-1119147 and JP-A-62-78137. That is, it is produced by polymerizing the monomer 1, the monomer 2 and the monomer 3 in combination in the above ratio in an appropriate solvent. That is, among all the monomers used in the copolymer polymerization, the ratio of the monomer 1 is set to 25 to 85% by weight, and preferably the ratio of the monomer 1 and the ratio of the monomer 2 Polymerization is performed with the total ratio of the monomers 3 being 90% by weight or more.

  Examples of the solvent used in the solution polymerization method include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, benzene, toluene, xylene, cyclohexane, n-hexane, ethyl acetate, acetone, and methyl ethyl ketone. In consideration of handling and reaction equipment, water and methyl alcohol, ethyl alcohol, and isopropyl alcohol are preferable.

  As an aqueous polymerization initiator, persulfuric acid ammonium salt or alkali metal salt or hydrogen peroxide, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2-methylpropionamide) Water-soluble azo compounds such as dihydrate are used. For solution polymerization using a non-aqueous solvent, peroxides such as benzoyl peroxide and lauroyl peroxide, aliphatic azo compounds such as azobisisobutyronitrile, and the like are used.

  Examples of chain transfer agents include thiol chain transfer agents and halogenated hydrocarbon chain transfer agents, and thiol chain transfer agents are preferred.

As the thiol chain transfer agent, those having a —SH group are preferable, and in particular, the general formula HS—R—Eg (wherein R represents a hydrocarbon-derived group having 1 to 4 carbon atoms, and E is − OH, —COOM, —COOR ′ or —SO ₃ M group, M represents a hydrogen atom, monovalent metal, divalent metal, ammonium group or organic amine group, and R ′ represents an alkyl having 1 to 10 carbon atoms. In which g represents an integer of 1 to 2, for example, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, Examples include octyl thioglycolate, octyl 3-mercaptopropionate, and the like from the viewpoint of chain transfer effect in a copolymerization reaction including monomers 1 to 3. Mercaptoethanol are preferable, more preferably mercaptopropionic acid. These 1 type (s) or 2 or more types can be used.

  Examples of the halogenated hydrocarbon chain transfer agent include carbon tetrachloride and carbon tetrabromide.

  Examples of other chain transfer agents include α-methylstyrene dimer, terpinolene, α-terpinene, γ-terpinene, dipentene, 2-aminopropan-1-ol and the like. A chain transfer agent can use 1 type (s) or 2 or more types.

  An example of the manufacturing method of the copolymer which concerns on this invention is shown. A predetermined amount of water is charged into a reaction vessel, the atmosphere is replaced with an inert gas such as nitrogen, and the temperature is raised. Prepare monomer 1, monomer 2, monomer 3, chain transfer agent mixed and dissolved in water, and polymerization initiator dissolved in water, and take 0.5 to 5 hours. Drip into the reaction vessel. At that time, each monomer, chain transfer agent and polymerization initiator may be dropped separately, or a mixed solution of monomers can be charged in a reaction vessel in advance and only the polymerization initiator can be dropped. is there. That is, the chain transfer agent, the polymerization initiator, and other additives may be added as an additive solution separately from the monomer solution, or may be added to the monomer solution after being added. From the viewpoint of stability, it is preferable to supply the reaction system as an additive solution separately from the monomer solution. Further, aging is preferably performed for a predetermined time. The polymerization initiator may be added dropwise at the same time as the monomer, or may be added in portions, but it is preferable to add in portions in terms of reducing unreacted monomers. For example, in the total amount of the polymerization initiator to be finally used, 1/2 to 2/3 polymerization initiator is added simultaneously with the monomer, and the remainder is aged for 1 to 2 hours after the completion of the monomer dropping, It is preferable to add. If necessary, the copolymer according to the present invention is obtained by further neutralizing with an alkali agent (such as sodium hydroxide) after completion of aging.

  In addition, the copolymer according to the present invention is obtained by introducing a liquid A containing monomer 1, a liquid B containing monomer 2 and a liquid C containing monomer 3 into the reaction system. It can also be used for a copolymerization reaction, and the liquid A, the liquid B, and the liquid C can be separately or partially introduced into the reaction system. Moreover, it is preferable to introduce 90% by weight or more of each of the total amount of liquid A, liquid B, and liquid C introduced into the reaction system in parallel. Specific examples of the method for introducing the liquid A, the liquid B, and the liquid C into the reaction system include dropping and spraying, and the dropping is preferable from the viewpoint of the viscosity of the liquid A, the liquid B, and the liquid C. The liquid A is preferably a solvent containing water from the viewpoint of the freezing point, and the liquid B is preferably a solvent not containing water from the viewpoint of hydrolysis. When the liquid A, the liquid B, and the liquid C are each separately added, or the two kinds of mixed liquids and the remaining one kind of liquid are dropped from another nozzle, the distance between the nozzles (inlet ports) of the liquids is arbitrary. Can be set. Moreover, although dripping can be carried out in air or in liquid, air dripping is preferred from the viewpoint of introducing all of the liquid. The nozzle diameter is preferably smaller from the viewpoint of increasing the surface area of the droplet and the solubility. By introducing 90% by weight or more of each of the total amount of liquid A, liquid B, and liquid C introduced into the reaction system into the reaction system in parallel, a copolymer in which each monomer is randomly introduced is obtained. . In other words, 90% by weight or more of the total amount of the liquid A, the liquid B, and the liquid C means that the amount of the liquid A, the liquid B, and the liquid C introduced into the reaction system alone is the liquid A that is introduced into the reaction system. The total amount of liquid B and liquid C is 10% by weight or less.

  Further, in the production of the copolymer according to the present invention, from the viewpoint of versatility with respect to materials, temperature and blending, the monomer 1 and the monomer 2 or the monomer 1 and the monomer 3 are copolymerized during the polymerization. It is preferable to perform polymerization by changing the polymerization molar ratio at least once.

  The weight average molecular weight (gel permeation chromatography method / polyethylene glycol conversion) of the copolymer in the present invention is in the range of 30000 to 60000, preferably 350,000 to 55000, and more preferably 40000 to 50000.

The weight average molecular weight Mw of the copolymer of the present invention is measured by gel permeation chromatography (GPC) method under the following conditions.
[GPC conditions]
Column: G4000PWXL + G2500PWXL (Tosoh)
Eluent: 0.2M phosphate buffer / CH ₃ CN = 9/1
Flow rate: 1.0mL / min
Column temperature: 40 ° C
Detection: RI
Sample size: 0.2mg / mL
Reference material: Polyethylene glycol equivalent

  The dispersion holding agent for hydraulic compositions of the present invention can be used as an aqueous solution containing the copolymer.

<Admixture for hydraulic composition>
The dispersion-holding agent for hydraulic compositions of the present invention is another copolymer, for example, a polymer A having at least one selected from a carboxylic acid group, a phosphoric acid group, a sulfonic acid group and a neutralizing group thereof ( Hereinafter, it can be used as an admixture for a hydraulic composition in combination with the polymer A). That is, to obtain an admixture for a hydraulic composition (hereinafter sometimes referred to as an admixture for a hydraulic composition of the present invention) containing the dispersion holding agent for a hydraulic composition of the present invention and the polymer A. Can do. In general, the polymer A is a polymer known as an admixture (dispersant or the like) for a hydraulic composition. The admixture for hydraulic composition of the present invention can be used as an aqueous solution containing the dispersion retention agent of the present invention and the polymer A.

  Examples of the polymer A having a carboxylic acid group or a neutralizing group thereof include a polymer having a (poly) oxyalkylene group and a carboxylic acid group, and specifically, JP-A-7-223852. A polyalkylene glycol monoester monomer and an acrylic acid polymer into which 110 to 300 moles of an oxyalkylene group having 2 to 3 carbon atoms shown in FIG. 1 is introduced, and polymers A and B of JP-T-2004-519406. A polymer containing an amide-based macromonomer described in Japanese Patent Application Laid-Open No. 2004-210587 and Japanese Patent Application Laid-Open No. 2004-210589, Japanese Patent Application Laid-Open No. 2003-128738, and Japanese Patent Application Laid-Open No. 2006-2006. Examples thereof include polymers containing polyethyleneimine described in Japanese Patent No. 525219.

  Examples of commercially available polymers A having a carboxylic acid group or a neutralizing group thereof include (1) BASF Pozzolith Co., Ltd. Leo Build SP8LS / 8LSR, SP8LS, SP8LSR, SP8N, SP8S, SP8R, SP8SE / 8RE, SP8SE, SP8RE , SP8SB series (S type, M type, L type, LL type), SP8HE, SP8HR, SP8SV / 8RV, SP8RV, SP8HU, SP9N, SP9R, SP9HS, Leo build 8000 series, (2) Nihon Sika Co., Ltd. SeaCament 1100NT , Sea Kament 1100NTR, Sea Kament 2300, (3) Floric's Floric SF500S (500SB), Floric SF500H, Floric SF500R (500RB), (4) Tulip HP-8, HP -11, HP-8R, HP-11R, SSP-104, NV-G1, NV-G5, (5) Nippon Catalyst's Aqualock FC600S, Aqualock FC900, (6) Maria Lim, Nippon Oil & Fats Co., Ltd. AKM, Mariarim EKM, etc. are mentioned, but not limited to this.

  The polymer A having a phosphate group or a neutralizing group thereof is a polymer having a polyoxyalkylene group and a phosphate group. For example, the polymer of Unexamined-Japanese-Patent No. 2006-052381 is mentioned. Specifically, a polyalkylene glycol monoester monomer introduced with an average of 3 to 200 moles of an oxyalkylene group having 2 to 3 carbon atoms, di-[(2-hydroxyethyl) methacrylic acid] ester phosphate, And a copolymer with mono (2-hydroxyethyl) methacrylate ester.

  Among the polymers A, those having a sulfonic acid group or a neutralizing group thereof include naphthalene polymers (for example, Mighty 150: manufactured by Kao Corporation), melamine polymers (for example, Mighty 150V-2: Kao Corporation) ) And aminosulfonic acid polymers (for example, PARIC FP: manufactured by Fujisawa Chemical Co., Ltd.).

  In the admixture for hydraulic composition of the present invention, the content (in terms of solid content) of the dispersion retention agent of the present invention is preferably 1 to 99% by weight, more preferably 2 to 80% by weight, and even more preferably 5 to 70% by weight. The content of polymer A (in terms of solid content) is preferably 1 to 99% by weight, more preferably 20 to 98% by weight, and even more preferably 30 to 95% by weight. Two or more dispersion holding agents can be used, but the total content is preferably in the above range. Two or more types of polymers A can be used, but the total content is preferably in the above range. The weight ratio (dispersion retention agent / polymer A (in terms of solid content)) of the dispersion retention agent and polymer A in the admixture for hydraulic composition is 5/95 to 95 / from the viewpoint of fluidity and fluid retention. 5, 10/90 to 90/10 are preferred, 15/85 to 85/15 are more preferred, and 20/80 to 80/20 are more preferred.

  In addition to the polymer A, the admixture for a hydraulic composition of the present invention includes, for example, a high-performance water reducing agent, AE agent, AE water reducing agent, fluidizing agent, retarder, early strengthening agent, accelerator, foaming agent. , Foaming agents, antifoaming agents, thickeners, waterproofing agents, antifoaming agents, silica sand, blast furnace slag, fly ash, silica fume and other known additives (materials) can be used in combination.

<Hydraulic composition>
A hydraulic composition can be obtained by using the dispersion holding agent for a hydraulic composition of the present invention and the polymer A, and preferably using the admixture for a hydraulic composition of the present invention. That is, a hydraulic composition containing the dispersion holding agent for a hydraulic composition of the present invention, the polymer A, a hydraulic powder, and water (hereinafter also referred to as a hydraulic composition of the present invention). There is). In obtaining the hydraulic composition of the present invention, the dispersion-holding agent of the present invention and the polymer A may be mixed in advance or used separately.

  The hydraulic powder used in the hydraulic composition of the present invention is a powder having physical properties that are cured by a hydration reaction, and examples thereof include cement and gypsum. Preferred are ordinary Portland cement, Belite cement, moderate heat cement, early strong cement, super early strong cement, sulfuric acid resistant cement, etc., and blast furnace slag, fly ash, silica fume, stone powder (calcium carbonate powder), etc. May be added. In addition, the hydraulic composition finally obtained by adding sand, sand and gravel as aggregates to these powders is generally called mortar, concrete, etc., respectively. The hydraulic composition of the present invention is used in the field of ready-mixed concrete, concrete vibration products, self-leveling, refractory, plaster, gypsum slurry, lightweight or heavy concrete, AE, repair, pre-packed, tray It is useful in any field of various concrete such as for grouting, for ground improvement, for cold weather.

  The hydraulic composition of the present invention has a water / hydraulic powder ratio [weight percentage (% by weight) of water and hydraulic powder in the slurry, usually abbreviated as W / P. , W / C may be abbreviated. ] May be 60% by weight or less, further 58 to 15% by weight, further 57 to 18% by weight, further 56 to 20% by weight, particularly 55 to 23% by weight.

  In the hydraulic composition, the admixture for hydraulic composition of the present invention is 0.02 to 10 parts by weight, further 0.02 to 5 parts by weight, and further 0.05 to 5 parts by weight with respect to 100 parts by weight of the hydraulic powder. It is preferably added at a ratio of 2 parts by weight (in terms of solid content). Further, the dispersion retention agent is in a ratio (in terms of solid content) of 0.002 to 5 parts by weight, further 0.01 to 4 parts by weight, and further 0.02 to 2 parts by weight with respect to 100 parts by weight of the hydraulic powder. It is preferable to be added. The polymer A is preferably added in a ratio (converted to solid content) of 0.01 to 8 parts by weight and further 0.02 to 4 parts by weight with respect to 100 parts by weight of the hydraulic powder.

<Production example>
Production Example 1
126.1 g of water was charged into a glass reaction vessel (four-necked flask) equipped with a stirrer, purged with nitrogen while stirring, and heated to 80 ° C. in a nitrogen atmosphere. ω-methoxypolyethyleneglycol monomethacrylate (average added mole number of ethylene oxide 23, moisture 35.3%, purity 93.6%) 165.6 g, hydroxyethyl acrylate (indicated in the table as HEA) 43.3 g, methacrylic acid A monomer solution obtained by mixing and dissolving 16.0 g (denoted as MAA in the table) and 1.72 g of 3-mercaptopropionic acid (Sigma Aldrich Japan Co., Ltd., reagent), an ammonium persulfate aqueous solution (I) [ammonium persulfate ( Wako Pure Chemical Industries, Ltd. (Reagents) 2.66 g dissolved in 45 g of water] was started at the same time and dropped over 1.5 hours respectively, followed by ammonium persulfate aqueous solution (II) [ A solution obtained by dissolving 0.44 g of ammonium sulfate in 15 g of water] was added dropwise over 0.5 hours. Thereafter, aging was performed at 80 ° C. for 1 hour. After completion of aging, the mixture was neutralized with a 20% aqueous sodium hydroxide solution to obtain a copolymer (dispersion retention agent). Hydroxyethyl acrylate is a compound having a molecular weight of 116.1 in which the compound represented by the general formula (2), R ⁵ is a hydroxyethyl group, and the logP value of the compound represented by R ⁵ —OH is −1.369. is there. Therefore, hydroxyethyl acrylate has [log P value / molecular weight Mw of monomer (2)] of −1.369 / 116.1 = −0.0118.

  Incidentally, ω-methoxypolyethylene glycol monomethacrylate was synthesized by esterification reaction according to the method described in Japanese Patent No. 3879917, and methacrylic acid remaining as an unreacted product was distilled off to less than 1% by weight. Using.

  Specifically, methacrylic acid and polyalkylene glycol monoalkyl ether are esterified using p-toluenesulfonic acid as an acid catalyst and hydroquinone as a polymerization inhibitor, and then acidified using sodium hydroxide as an alkali agent. The catalyst was deactivated, and unreacted methacrylic acid was distilled off by a vacuum distillation method.

Production Examples 2-6 and Comparative Examples 1-5
A copolymer (dispersion retention agent) was produced in the same manner as in Production Example 1 using the monomers and ratios shown in Table 1. The resulting copolymer was used in the following examples.

The symbols in the table have the following meanings.
ME-PEG: ω-methoxypolyethylene glycol monomethacrylate, the value in parentheses is the average number of moles of ethylene oxide added.
HEA: 2-hydroxyethyl acrylate (ethylene glycol log P: -1.369, log P / Mw: -1.369 / 116.1 = -0.0118, Wako Pure Chemical Industries, Reagent)

Example 1 (Paste test)
<Paste formulation>

W: Tap water C: Ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd.)

  Into a 500 ml container, in accordance with Formulation 1, water containing cement and a dispersion retention agent of Table 1 (0.08 parts by weight with respect to 100 parts by weight of cement) is added, and kneaded for 2 minutes with a hand mixer (low speed of about 63 rpm). A paste was obtained.

<Evaluation of fluid retention performance>
The obtained paste was filled into a cylindrical cone (φ50 mm × 51 mm), and the spread (the longest diameter length and the average value in the vertical direction) when pulled up vertically was measured as a paste flow. The measurement was performed immediately after the end of kneading (after 0 minutes), 30 minutes after the end of kneading, 60 minutes after the end of kneading, 90 minutes after the end of kneading, and 120 minutes after the end of kneading. As an indicator of fluidity retention, the area of the graphic shown in FIG. 1 was determined for each dispersion retention agent. The area of this figure is obtained by (fluidity−100 mm) × time (unit: mm · min). The flow value immediately after completion of kneading was defined as initial fluidity. The initial fluidity when no dispersion retention agent was added was 100 mm.

  In this evaluation, if the fluidity retention is 6000 mm · min or more, preferably 7000 mm · min or more, it can be judged that the dispersion retention agent for hydraulic composition is good.

The following results are obtained from the results in Table 3.
When the ratio of the monomer 3 having a carboxylic acid group is 20% by weight in the constituent monomers of the copolymer, the fluidity retention deteriorates (Comparative Production Example 1 and Production Examples 1 to 4). In addition, the fluidity retention deteriorates whether the average added mole number of ethylene oxide of monomer 1 is small or large (Comparative Production Examples 2, 3 and Production Example 3). Moreover, when the weight average molecular weight of the copolymer is small, the fluidity retention deteriorates (Comparative Production Example 5 and Production Examples 3, 5, and 6).

<Evaluation of fluid retention>
About some manufacture examples and comparative manufacture examples of Table 3, it investigated about the flow retention after 30 minutes. The fluid retention was calculated according to the following formula. The results are shown in Table 4. Especially in the ready-mixed food field, the retention rate after 30 minutes is important. In this evaluation, when the concrete is used, the fluidity retention is preferably 110% or more, and more preferably 120% or more, considering that the fluidity greatly decreases.
Fluid retention = [(paste flow after 120 minutes) / (paste flow after 30 minutes)] × 100

  From the results of Table 4, Comparative Product 4 and Comparative Product 7 having a weight average molecular weight of 92,000 had a retention performance at 103% and 104%, respectively, in the paste flow evaluation, but were made concrete. Considering the case, the retention performance is still insufficient.

In an Example, the graph which shows the figure used as the object of area measurement for evaluating fluidity retention

Claims (4)

Weight average obtained by polymerizing monomer 1 represented by general formula (1), monomer 2 represented by general formula (2), and monomer 3 represented by general formula (3) A dispersion holding agent for a hydraulic composition comprising a copolymer having a molecular weight of 30,000 to 60,000,
At least a part of the monomer 2 has a relationship of [log P value of alcohol compound R ⁵ —OH corresponding to R ⁵ in general formula (2) / molecular weight Mw of monomer (2)] <− 0.003. The filling,
A dispersion retention agent for a hydraulic composition, wherein monomer 1 is 25 to 78% by weight and monomer 3 is 0 to 18% by weight in the constituent monomers of the copolymer.

Wherein, R ¹ to R ³ each represent a hydrogen atom or a methyl group, AO represents an oxyalkylene group having 2 to 4 carbon atoms, n is an average addition mole number of AO, the number of 20 to 30 R ⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, q represents an integer of 0 to 2, and p represents 0 or 1. ]

[Wherein R ⁵ is a hydrocarbon group which may contain a hetero atom having 1 to 4 carbon atoms. ]

Wherein, R ⁶ to R ⁸ are each a hydrogen atom, a methyl group or ^{_{(CH 2) s COOM 2,}} (CH 2) s COOM 2 is COOM ¹ or another (CH _{²⁾ s} COOM ₂ and anhydrous In this case, M ¹ and M ² of those groups are not present. s represents the number of 0-2. M ¹ and M ² each represent a hydrogen atom, an alkali metal, an alkaline earth metal (1/2 atom), an ammonium group, an alkyl ammonium group, a substituted alkyl ammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group. ] The dispersion retention agent for hydraulic compositions according to claim 1, wherein at least a part of the monomer 2 is a monomer in which R ^{5 in the} general formula (2) is a hydroxyethyl group or a glycerol group. [The log P value of the alcohol compound R ⁵ —OH corresponding to R ⁵ in the general formula (2) / the molecular weight Mw of the monomer (2)] <− 0.003 The dispersion retention agent for hydraulic compositions according to claim 1 or 2, which is 30 mol% or more in the monomer 2.   The weight ratio of monomer 1, monomer 2 and monomer 3 (monomer 1 / monomer 2 / monomer 3) is 25 to 78/10 to 70/0 to 18, and The dispersion retention agent for hydraulic compositions in any one of Claims 1-3 whose weight ratio (monomer 2 / monomer 3) of the monomer 2 and the monomer 3 is more than one.

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