JP2006176380A - Copolymer for dispersing hydraulic powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copolymer for dispersing hydraulic powder capable of securing sufficient dispersibility and also excellent dispersion holdability to the hydraulic powder and capable of giving sufficient fluidity and excellent flow holdability to a hydraulic composition. <P>SOLUTION: In the copolymer for dispersing the hydraulic powder having a constituent unit (I) originated from a specific polyalkylene glycol ester-based monomer, a constituent unit (II) originated from a specific acrylic ester-based monomer and a constituent unit (III) originated from a specific acrylic acid-based monomer, a weight ratio Z and AV value of the constituent unit (II) are respectively within a specific range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a copolymer that can be suitably used as a dispersant for hydraulic powder typified by cement, a hydraulic powder dispersant and a hydraulic composition using the copolymer. More specifically, a hydraulic powder-dispersing copolymer capable of imparting sufficient fluidity and excellent fluidity retention to hydraulic compositions such as cement paste, mortar and concrete, and hydraulic properties using the same The present invention relates to a powder dispersant and a hydraulic composition.

  A polycarboxylic acid having a typical example of a copolymer of a polyalkylene glycol ester monomer (hereinafter also referred to as PAG ester monomer) and a methacrylic acid monomer (hereinafter also referred to as PAG ester copolymer). Compared to naphthalene-based and melamine-based polymers, acid-based polymers have a strong dispersion power for hydraulic powders typified by cement, and are dispersion agents for hydraulic compositions containing hydraulic powders typified by concrete. It is very popular as a main ingredient.

  In Patent Document 1, a copolymer of a specific PAG ester-based monomer and a methacrylic acid-based monomer having different copolymerization weight ratios of carboxylic acid-based monomers is mixed. Thus, a concrete admixture that can ensure dispersibility and dispersion retention at a high level is disclosed.

  Patent Document 2 discloses a concrete admixture containing a specific PAG ester monomer, a terpolymer of methyl acrylate and methacrylic acid and excellent in fluidity retention.

JP 2001-294462 A (Claim 1, Table 3) JP 10-81549 A (Claim 6, Table 2)

  The present invention provides a hydraulic powder that is sufficiently dispersible with respect to the hydraulic powder, has excellent dispersion retention, and can provide sufficient fluidity and excellent fluid retention to the hydraulic composition. It is an object of the present invention to provide a copolymer for dispersion, a hydraulic powder dispersant and a hydraulic composition using the same.

The present invention includes a structural unit (I) derived from a monomer represented by the following general formula (1), a structural unit (II) derived from a monomer represented by the following general formula (2), and the following: A hydraulic powder dispersion copolymer having a structural unit (III) derived from a monomer represented by the general formula (3), the weight of the structural unit (II) defined by the following formula (4a) The AV value defined by the ratio Z and the following formula (4b) is such that when R ₆ in the structural unit (III) is a hydrogen atom, Z is 2 to 35 and the AV value is 25 to 44, and the structural unit (III And R _{6 in} () is a methyl group or (CH ₂ ) _{m 2} COOM ₂ , it relates to a hydraulic powder dispersion copolymer having a Z of 5 to 35 and an AV value of 25 to 44.

[Where,
R ₁ and R ₂ may be the same or different and are each a hydrogen atom or —CH ₃
X: a hydrogen atom or an alkyl group having 1 to 3 carbon atoms AO: an alkylene oxide group having 2 to 3 carbon atoms n: an average number of moles added, and a number of 80 to 300. ]

[Where,
R ₃ represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or a hydroxyalkyl group having 2 to 6 carbon atoms. ]

[Where,
R _{4 to} R ₆ : hydrogen atom, methyl group or (CH ₂ ) _{m 2} COOM ₂ , where M ₂ is the same as M ₁ m2: 0 or 1
M _{1 represents} hydrogen, alkali metal, alkaline earth metal, ammonium group, alkylammonium group or substituted alkylammonium group. ]

Z = [[[Z (II)] / [Z (ALL)]] × 100 (4a)
[In Formula (4a),
Z (II): Weight of the structural unit (II) in the copolymer Z (ALL): Weight of the structural units (I), (II) and (III) in the copolymer. ]

AV value ≡ [W _(III) ] / [M _(III) ] × 1000 × 56.1 (4b)
[In Formula (4b),
W _(III) : Weight ratio of the structural unit (III) in the total of the structural units (I), (II) and (III) in the copolymer [(III) / [(I) + (II) + ( III)], and the structural unit (III) is the weight in terms of acid. ]
M _(III) : The molecular weight in terms of acid type of the structural unit (III). ]

  The present invention also relates to a dispersant for a hydraulic powder containing the above-mentioned copolymer for dispersing a hydraulic powder of the present invention, and a hydraulic composition containing the dispersant for a hydraulic powder of the present invention. .

Further, the present invention provides a monomer represented by the general formula (1) [hereinafter referred to as monomer (1)], a monomer represented by the general formula (2) [hereinafter monomer (Referred to as (2)) and the monomer represented by the general formula (3) (hereinafter referred to as monomer (3)) is the weight of the monomer (2) defined by the following formula (4a ′) AV ′ value defined by the ratio Z ′ and the following formula (4b ′) is such that when R ₆ in the monomer (3) is a hydrogen atom, Z ′ is 2 to 35 and AV ′ value is 25 to 44. And when R ₆ in the monomer (3) is a methyl group or (CH ₂ ) _m2 COOM ₂ , copolymerization is carried out under the conditions that Z ′ is 5 to 35 and AV ′ value is 25 to 44. The present invention also relates to a method for producing a hydraulic powder dispersion copolymer of the present invention.

Z ′ = [[Z ′ (II)] / [Z ′ (ALL)]] × 100 (4′a)
[In the formula (4′a),
Z ′ (II): Weight of monomer (2) Z ′ (ALL): Weight of monomers (1), (2), (3). ]

AV ′ value ≡ [W ′ _(III) ] / [M ′ _(III) ] × 1000 × 56.1 (4′b)
[In the formula (4′b),
W ′ _(III) : weight ratio of monomer (3) in the sum of monomers (1), (2), (3) [(3) / [(1) + (2) + (3) The monomer (3) is an acid equivalent weight. ]
M ′ _(III) : molecular weight in terms of acid type of monomer (3). ]

  According to the present invention, a hydraulic powder that ensures sufficient dispersibility with respect to the hydraulic powder, has excellent dispersion retention, and can provide sufficient fluidity and excellent fluid retention to the hydraulic composition. Dispersion copolymers, hydraulic powder dispersants and hydraulic compositions using the same are provided.

  Conventional PAG ester-based copolymers are difficult to achieve both the dispersion and dispersion retention of hydraulic powders alone. Like the concrete admixture disclosed in Reference 1, a copolymer having a strong dispersibility but insufficient dispersion retention and a copolymer having insufficient dispersion but insufficient dispersion retention are mixed together. Mixing various types of copolymers with different polymerization compositions, mixing components specialized for fluidity retention, such as the concrete admixture disclosed in Patent Document 2, and further adding amount of copolymer Attempts have been made to adjust both performances, for example by increasing.

  Therefore, the present inventors consider that if the copolymer responsible for dispersion retention can sufficiently secure the dispersion force, a more balanced hydraulic powder dispersant can be formed, and a PAG ester copolymer can be formed. As a result of a detailed review of the relationship between the coalescence composition and the dispersion performance of the hydraulic powder, by limiting the conventional PAG ester copolymer to a specific structure, excellent dispersibility and sufficient dispersibility are achieved. The present inventors have found that this can be done and have completed the present invention.

《Copolymer for dispersion of hydraulic powder》
The copolymer of the present invention has the structural unit (I), the structural unit (II) and the structural unit (III) as essential structural units. For example, in the composition of only the structural unit (I) and the structural unit (III) as in the copolymer disclosed in Patent Document 1, the dispersibility and the dispersion retention tend to conflict with each other. Increasing the composition ratio improves the dispersibility while lowering the dispersion retention, and there is a limit to the compatibility of both performances.

  In the copolymer of the present invention, the constitutional unit (II) is essential in addition to the constitutional unit (I) and the constitutional unit (III), thereby trying to balance dispersibility and dispersion retention. It has been found that the copolymer of the present invention can achieve both sufficient dispersibility and excellent dispersion retention when the structural unit (II) is added and the structure is extremely limited.

  That is, in the copolymer of the present invention, if the composition ratio of the structural unit (III) is increased, a certain degree of dispersibility can be secured, while the dispersion of the structural unit (I) The average added mole number n of the alkylene oxide (hereinafter also referred to as AO) is required to be 80 or more, preferably 90 or more, more preferably 100 or more, and further preferably 110 or more. From the viewpoint of reactivity during synthesis, n is 300 or less, preferably 200 or less, and more preferably 150 or less. From a comprehensive viewpoint, n is preferably 80 to 300, more preferably 80 to 200, still more preferably 80 to 150, still more preferably 90 to 150, still more preferably 100 to 150, and particularly preferably 110 to 150.

  In the copolymer of the present invention, the increase in the composition ratio of the structural unit (III) contributes to the improvement of dispersibility, but the AV value defined by the formula (4b) as an index of the composition ratio of the structural unit (III). When (or AV ′ value defined by the equation (4′b)) is adopted, a large AV value means a strong dispersibility.

  The inventors of the present invention have sufficient dispersibility by selecting the following structure in the range where the AV value is 25 to 44, preferably 27 to 42, more preferably 28 to 41, and further preferably 29 to 40. And found to ensure excellent dispersion retention.

That is, in the present invention, the AV value is in the above range, and the weight ratio Z of the structural unit (II) is 2 to 35, preferably 3 to 33, when R ₆ in the structural unit (III) is a hydrogen atom. , More preferably 3 to 30, more preferably 3 to 27, and when R ₆ is a methyl group or (CH ₂ ) _m2 COOM ₂ , 5 to 35, preferably 6 to 33, more preferably 6 to 30, When it is preferably 6 to 27, sufficient dispersibility and excellent dispersion retention can be ensured.

  This is because the structural unit (II) is hydrolyzed in a hydraulic composition having a high pH and changes to the structure of the structural unit (III) over time, contributing to dispersibility (dispersion retention is improved). The above effect can be achieved by substituting the structural unit (I) with the structural unit (II) to the extent that the dispersibility of the entire copolymer is good.

  From this point of view, in the copolymer of the present invention, the weight ratio of the structural unit (I) to the structural unit (II) is the structural unit (I) / structural unit (II) in terms of the acid type of the structural unit (II). = 99/1 to 60/40 is preferable, more preferably 95/5 to 65/35, still more preferably 94/6 to 68/32, and particularly preferably 93/7 to 71/29.

Below, the more preferable aspect of the copolymer of this invention is demonstrated.
<Structural unit (I)>
As the monomer (1) represented by the general formula (1) from which the structural unit (I) is derived, from the viewpoint of ensuring sufficient dispersibility, methoxypolyethylene glycol, methoxypolyethylenepolypropylene glycol, ethoxypolyethyleneglycol, Use esterified products of one-end alkyl-blocked polyalkylene glycols such as ethoxypolyethylenepolypropylene glycol, propoxypolyethylene glycol, propoxypolyethylenepolypropyleneglycol and acrylic acid or methacrylic acid, or addition of ethylene oxide or propylene oxide to acrylic acid or methacrylic acid Preferred are esterified products of methoxypolyethylene glycol and esterified products of methoxypolyethylenepolypropylene glycol, more preferably methoxyethylene glycol. It is a ester of polyethylene glycol.

  The oxyalkylene group (AO) may be any of random addition, block addition, alternating addition, etc. for both adducts of ethylene oxide and propylene oxide, but ethylene oxide is preferred from the viewpoint of ensuring sufficient dispersibility.

<Structural unit (II)>
Examples of the monomer (2) represented by the general formula (2) from which the structural unit (II) is derived include a linear or branched alkyl acrylate ester having 1 to 18 carbon atoms, and a straight chain having 2 to 18 carbon atoms. A chain or branched alkenyl acrylate ester or a hydroxyalkyl acrylate ester having 2 to 6 carbon atoms can be used. Here, as R < ₃ > in General formula (2), a C1-C4 thing is especially preferable at the point with the good solubility to the water of the polymer obtained, About linear and branched forms Although not particularly limited, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl acrylate, and ethyl acrylate are preferable from the viewpoint of solubility in water and hydrolyzability, and hydroxyethyl acrylate, hydroxypropyl acrylate, and methyl acrylate are more preferable. Preferably, hydroxyethyl acrylate and methyl acrylate are more preferable.

<Structural unit (III)>
As the monomer (3) represented by the general formula (3) from which the structural unit (III) is derived, as a monocarboxylic acid monomer, acrylic acid, methacrylic acid, crotonic acid, or an alkali metal salt thereof , Ammonium salts, amine salts and substituted amine salts can be used. As the unsaturated dicarboxylic acid monomer, maleic acid, itaconic acid, citraconic acid, fumaric acid, or alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts, substituted amine salts thereof can be used. From the viewpoint of copolymerization, (meth) acrylic acid, maleic acid and itaconic acid are preferable, (meth) acrylic acid and maleic acid are more preferable, (meth) acrylic acid is further preferable, and acrylic acid is still more preferable. (Meth) acrylic acid means acrylic acid and / or methacrylic acid.

<Optional component>
In addition, the copolymer in the present invention may be produced using other copolymerizable monomers within the range not impairing the effects of the present invention. Examples of such monomers include acrylonitrile, methallyl sulfonic acid, acrylamide, methacrylamide, styrene, styrene sulfonic acid, vinyl acetate, vinyl chloride and the like. The composition ratio of the optional components in the copolymer is as follows: From the viewpoint of the adsorptivity of the copolymer to the cement, the copolymer preferably contains 0 to 50% by weight, more preferably 0 to 30% by weight, still more preferably 0 to 10% by weight, and most preferably. It is not.

<Quantitative method for structural units>
The composition of the copolymer of the present invention can be designed according to the charged value of the monomer from which each structural unit is derived, and the composition of the copolymer obtained by polymerization can be determined as follows.

[AO average added mole number n]
A copolymer dissolved in water and 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 and the integrated value of the peak of the alkylene oxide group, the total number of H of the alkylene oxide group is obtained, and the value obtained by dividing by the number of hydrogen atoms contained in one alkylene oxide group is Let n. 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 temperature is 25.0 ° C.

[Composition ratio of structural unit (III)]
A copolymer dissolved in water and dried at room temperature in a nitrogen atmosphere is dissolved in heavy water, and ¹ H-NMR is measured (conditions are the same as the above AO average addition mole number n). From the integral value s of the peak of the alkoxy group and the integral value S of the peak of the alkyl group of the main chain, [(S−s) / S] × 100 is calculated, and the constitutional unit (I) and constitution of the entire copolymer The ratio of the unit (II) is obtained, and the ratio (composition ratio) of the structural unit (III) is calculated from the value.

<Average weight molecular weight>
The weight average molecular weight (gel permeation chromatography method / polyethylene glycol equivalent) of the copolymer in the present invention is preferably in the range of 8,000 to 1,000,000, more preferably 10,000 to 300,000. When the molecular weight is too large, the fluidity imparting property is lowered, and when the molecular weight is too small, the fluidity retaining property tends to be lowered.

<Manufacturing method>
The copolymer in the present invention can be produced by a known method. Examples thereof include solution polymerization methods described in JP-A Nos. 62-119147 and 62-78137. That is, it is produced by polymerizing the above monomers (1), (2) and (3) in a suitable solvent in the above ratio.

  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.

  Water-based polymerization initiators include ammonium persulfate or alkali metal salts 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.

  Moreover, accelerators, such as sodium hydrogen sulfite and an amine compound, can also be used in combination with a polymerization initiator. Furthermore, for the purpose of adjusting the molecular weight, chain transfer agents such as 3-mercaptopropionic acid, 2-mercaptoethanol, mercaptoacetic acid, 1-mercaptoglycerin, mercaptosuccinic acid, alkyl mercaptan, and preferably low odor from the viewpoint of production environment 3-mercaptopropionic acid can also be used in combination.

In the production of the copolymer of the present invention, the weight ratio Z ′ of the monomer (2) defined by the following formula (4a ′) and the following formula so that the weight ratio Z and the AV value are substantially satisfied. The AV ′ value defined by (4b ′) is such that when R ₆ in the monomer (3) is a hydrogen atom, Z ′ is 2 to 35 and AV ′ value is 25 to 44, and the monomer ( 3) When R _{6 in the} formula is a methyl group or (CH ₂ ) _{m 2} COOM ₂ , monomers (1) to (3) are combined under the conditions that Z ′ is 5 to 35 and AV ′ value is 25 to 44. Polymerize.

Z ′ = [[Z ′ (II)] / [Z ′ (ALL)]] × 100 (4′a)
[In the formula (4′a),
Z ′ (II): Weight of monomer (2) Z ′ (ALL): Weight of monomers (1), (2), (3). ]

AV ′ value ≡ [W ′ _(III) ] / [M ′ _(III) ] × 1000 × 56.1 (4′b)
[In the formula (4′b),
W ′ _(III) : weight ratio of monomer (3) in the sum of monomers (1), (2), (3) [(3) / [(1) + (2) + (3) The monomer (3) is an acid equivalent weight. ]

According to the present invention, the monomer (1), the monomer (2), and the monomer (3) are converted into a weight ratio Z ′ of the monomer (2) defined by the formula (4a ′). And the AV ′ value defined by the formula (4b ′) is as follows: when R ₆ in the monomer (3) is a hydrogen atom, Z ′ is 2 to 35 and AV ′ value is 25 to 44. Hydraulic powder obtained by copolymerization under the conditions that Z ′ is 5 to 35 and AV ′ value is 25 to 44 when R _{6 in} monomer (3) is a methyl group or (CH ₂ ) _m2 COOM ₂ A body-dispersing copolymer is provided.

<< Dispersant for hydraulic powder >>
When the copolymer of the present invention is used as a main component of a dispersant for hydraulic powder, the dispersibility is equal to or higher than that achieved by combining different types of copolymers with a conventional dispersant in a single composition. Dispersion retention is expressed. In addition, in the case of a mixed system in which the copolymer of the present invention and another copolymer are used in combination, the total amount of addition can be reduced. In any case, a conventional high-performance water reducing agent can be contained within a range not impairing the effects of the present invention. An example of a high-performance water reducing agent is naphthalene (for example, Mighty 150: manufactured by Kao Corporation), melamine (for example, Mighty 150V-2: manufactured by Kao Corporation), aminosulfonic acid (for example, PARIC FP: Fujisawa) Chemical Co., Ltd.), polycarboxylic acid type (for example, Mighty 3000: manufactured by Kao Corporation) and the like.

  Among these known high-performance water reducing agents, in particular, polyalkylene glycol monoester monomers introduced with 1 to 100 moles of oxyalkylene groups having 2 to 3 carbon atoms, as disclosed in JP-A-58-74552, and Those containing a copolymer of an acrylic acid polymer are those in which 110 to 300 moles of an oxyalkylene group having 2 to 3 carbon atoms shown in JP-A-7-223852 is introduced in that the viscosity is lowered. Those containing a copolymer of an alkylene glycol monoester monomer and an acrylic acid polymer further enhance the dispersibility, so that an oxy of 2 to 3 carbon atoms disclosed in JP-A-10-81549 is disclosed. A binary or ternary copolymer having a unit derived from an ethylenically unsaturated monomer having 25 to 300 moles of an alkylene group as a structural unit enhances dispersion retention. In a preferred point.

  In the conventional PAG ester-based polycarboxylic acid, a copolymer with strong dispersion power has extremely low dispersion retention, and a copolymer with strong dispersion retention has extremely low dispersion power. When used as a component, it is necessary to add a large amount of a dispersion-holding component even if the amount of the dispersion component is small. However, when the copolymer of the present invention having an excellent dispersing power is used, it is possible to maintain dispersion for a long time with a low addition amount, and it is possible to reduce the addition amount of the initial dispersant. That is, the copolymer of the present invention can be suitably used as a component of a dispersing agent for hydraulic powders excellent in dispersion performance and dispersion retention performance. The content of the copolymer of the present invention in the dispersant for hydraulic powder is 30 to 100% by weight when the copolymer of the present invention satisfies 2 ≦ Z <8 and 35 <AV value ≦ 44, and further 40 ~ 100% by weight, in particular 50 ~ 100% by weight, the copolymer of the present invention is 8 ≦ Z ≦ 35 and 35 ≦ AV value ≦ 44 or 2 ≦ Z <8 and 25 ≦ AV value <35 In some cases, 1 to 80% by weight, more preferably 3 to 70% by weight, and particularly preferably 5 to 70% by weight.

<< Hydraulic composition >>
When the copolymer of the present invention is used as an additive for hydraulic powder, particularly as a main component of a dispersant, the amount added to the hydraulic composition is the same as that of the present invention relative to hydraulic powder such as cement. The polymer solid content is preferably 0.01 to 1.0% by weight, more preferably 0.02 to 0.5% by weight.

  The hydraulic powder used in the hydraulic composition that is the target of the dispersant for the hydraulic composition of the present invention is a powder having physical properties that are cured by a hydration reaction, such as cement and gypsum. Can be mentioned. Preferred are ordinary portland cement, high belite cement, medium heat cement, early strong cement, very 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 copolymer of this invention is added to hydraulic compositions, such as these cement paste, mortar, and concrete, The content is not limited.

  The hydraulic composition has a water powder ratio [weight percentage (% by weight) of water and hydraulic powder in the slurry, usually abbreviated as W / P. Abbreviated. It is preferably 25 to 60% by weight. Furthermore, 25 to 55% by weight, particularly 25 to 50% by weight is preferable. Moreover, the hydraulic powder used may be individual or mixed.

  The copolymer of the present invention can be used in combination with a known additive (particularly, an additive when the copolymer of the present invention is a powder). For example, AE agent, AE water reducing agent, fluidizing agent, retarding agent, early strengthening agent, accelerator, foaming agent, foaming agent, antifoaming agent, thickener, waterproofing agent, antifoaming agent, quartz sand, blast furnace slag, fly Examples include ash and silica fume.

<Manufacture of copolymer>
Into a reaction vessel equipped with a stirrer, 6.2 mol of water was charged, purged with nitrogen while stirring, and heated to 75 ° C. in a nitrogen atmosphere. A mixture of 0.03 mol of the monomer constituting the structural unit (I), 0.04 mol of the monomer constituting the structural unit (II) and 0.13 mol of the monomer constituting the structural unit (III), and 20% ammonium persulfate Three parts, 0.01 mol of aqueous solution (as ammonium persulfate) and 0.008 mol of 20% 3-mercaptopropionic acid aqueous solution (as 3-mercaptopropionic acid), were added dropwise simultaneously over 1 hour and 30 minutes, and the same temperature ( Aged at 75 ° C. After aging, 0.004 mol of 20% aqueous ammonium persulfate solution (as ammonium persulfate) was added dropwise, and after aging at the same temperature (75 ° C.) for 2 hours, 0.05 mol of 20% aqueous sodium hydroxide solution (as sodium hydroxide) was added dropwise. A copolymer having a weight average molecular weight of 80,800 was obtained. In the same manner as this method, other copolymers in Table 1 were obtained.

  Details of the copolymers of Examples and Comparative Examples are shown in Table 1. In Table 1, the monomer that is the structural unit (I) is methoxypolyethylene glycol / methacrylic acid ester, and the average added mole number n is as shown in Table 1. Moreover, all the monomers used as the structural unit (II) are hydroxyethyl acrylate. Further, among the monomers serving as the structural unit (III), MAA is methacrylic acid, and AA is acrylic acid.

<Evaluation>
These materials and the copolymer shown in Table 1 were kneaded with a mortar mixer at 63 rpm x 1 minute and 126 rpm x 2 minutes using a cement blend of 800 g of ordinary Portland cement and 280 g of ion exchange water (W / C = 35 wt%). A slurry was prepared. At that time, the addition amount (solid content) of the copolymer was adjusted so that the initial slump value was 200 mm ± 10 mm. The fluidity (slump value) of the cement slurry immediately after the preparation and after 60 minutes was measured by the JIS-A1101 method to determine the fluidity retention. The results are shown in Table 1.

  The addition ratio in Table 1 is the solid content weight% of the copolymer with respect to the cement.

  As shown in Table 1, the copolymer of the present invention is excellent in dispersibility and can maintain the fluidity immediately after the preparation of the cement slurry for a long time.

  That is, in the conventional copolymer, a copolymer having a strong dispersibility (a small amount of addition necessary for achieving a certain fluidity (immediately after)) has a weak dispersion retention (fluidity retention) (comparison). Examples 1 to 6), while the copolymer with strong dispersion retention has low dispersion (Comparative Examples 7 and 8), the copolymer of the present invention is a copolymer with strong dispersion retention. Also, dispersibility is ensured (Examples 1, 2, 3, and 5), and a single composition can ensure dispersibility and stable dispersion retention (Examples 4 and 6).

  Also, with conventional copolymers, dispersibility and stable dispersion retention cannot be ensured unless a highly dispersible copolymer and a copolymer with strong dispersion retention are combined, and this is added to ensure dispersibility. Whereas the amount needs to be increased (Comparative Example 9), the copolymer of the present invention can be combined with a conventional highly dispersible copolymer to increase dispersibility and maintain stable dispersion without increasing the amount added. (Examples 7 and 8).

  Furthermore, if the copolymer of the present invention is added as a dispersant to a hydraulic composition, high fluidity can be maintained for a long time, so that it is more difficult to maintain fluidity at high temperatures in summer or when the water cement ratio is small. Even when concrete is delayed due to various concrete production, placing conditions and troubles, the quality control of the concrete becomes easy.

Claims (4)

The structural unit (I) derived from the monomer represented by the following general formula (1), the structural unit (II) derived from the monomer represented by the following general formula (2), and the following general formula (3 A copolymer for dispersing a hydraulic powder having a structural unit (III) derived from a monomer represented by formula (4), wherein the weight ratio Z of the structural unit (II) defined by the following formula (4a) is The AV value defined by the formula (4b) is such that when R ₆ in the structural unit (III) is a hydrogen atom, Z is 2 to 35 and the AV value is 25 to 44, and R in the structural unit (III) _A hydraulic powder dispersion copolymer in which Z is 5 to 35 and AV value is 25 to 44 when ₆ is a methyl group or (CH ₂ ) _m2 COOM ₂ .

[Where,
R ₁ and R ₂ may be the same or different and are each a hydrogen atom or —CH ₃
X: a hydrogen atom or an alkyl group having 1 to 3 carbon atoms AO: an alkylene oxide group having 2 to 3 carbon atoms n: an average number of moles added, and a number of 80 to 300. ]

[Where,
R ₃ represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or a hydroxyalkyl group having 2 to 6 carbon atoms. ]

[Where,
R _{4 to} R ₆ : hydrogen atom, methyl group or (CH ₂ ) _{m 2} COOM ₂ , where M ₂ is the same as M ₁ m2: 0 or 1
M _{1 represents} hydrogen, alkali metal, alkaline earth metal, ammonium group, alkylammonium group or substituted alkylammonium group. ]

Z = [[[Z (II)] / [Z (ALL)]] × 100 (4a)
[In Formula (4a),
Z (II): Weight of the structural unit (II) in the copolymer Z (ALL): Weight of the structural units (I), (II) and (III) in the copolymer. ]

AV value ≡ [W _(III) ] / [M _(III) ] × 1000 × 56.1 (4b)
[In Formula (4b),
W _(III) : Weight ratio of the structural unit (III) in the total of the structural units (I), (II) and (III) in the copolymer [(III) / [(I) + (II) + ( III)], and the structural unit (III) is the weight in terms of acid. ]
M _(III) : The molecular weight in terms of acid type of the structural unit (III). ]   The dispersing agent for hydraulic powders containing the copolymer for hydraulic powder dispersions of Claim 1.   A hydraulic composition containing the dispersant for hydraulic powder according to claim 2. A monomer represented by the general formula (1) [hereinafter referred to as a monomer (1)], a monomer represented by the general formula (2) [hereinafter referred to as a monomer (2)], and The monomer represented by the general formula (3) [hereinafter referred to as the monomer (3)] is represented by the weight ratio Z ′ of the monomer (2) defined by the following formula (4a ′) and the following formula: The AV ′ value defined by (4b ′) is such that when R ₆ in the monomer (3) is a hydrogen atom, Z ′ is 2 to 35 and AV ′ value is 25 to 44, and the monomer ( 3) having a step of copolymerization under the conditions that Z ′ is 5 to 35 and AV ′ value is 25 to 44 when R _{6 in FIG.} 3 is a methyl group or (CH ₂ ) _{m 2} COOM _2. A method for producing a hydraulic powder-dispersing copolymer according to any one of the above.

Z ′ = [Z ′ (II)] / [Z ′ (ALL)] × 100 (4′a)
[In the formula (4′a),
Z ′ (II): Weight of monomer (2) Z ′ (ALL): Weight of monomers (1), (2), (3). ]

AV ′ value ≡ [W ′ _(III) ] / [M ′ _(III) ] × 1000 × 56.1 (4′b)
[In the formula (4′b),
W ′ _(III) : weight ratio of monomer (3) in the sum of monomers (1), (2), (3) [(3) / [(1) + (2) + (3) The monomer (3) is an acid equivalent weight. ]
M ′ _(III) : molecular weight in terms of acid type of monomer (3). ]