Dispersants for hydraulic composition

Abstract

To provide dispersants exhibiting good pulverizability for a hydraulic composition.SOLUTION: A dispersant for a hydraulic composition contains a copolymer A of (a) methacrylic acid, (b) a vinyl monomer having a cationic group, and (c) a monomer c selected from monomers represented by the general formula (1). [In the formula, R1c and R2c are identical or different and each represent a hydrogen atom or a methyl group; R3c represents a hydrogen atom or a -C(O)O(AO)nR4c group, where AO represents an oxyalkylene group or the like; q represents an integer from 0 to 2 inclusive; p represents 0 or 1; n represents from 5 to 150 inclusive; and R4c represents a hydrogen atom or a C1-18 alkyl group.] The summed molar content of (a) and (b) is 50 mol% or more if the molar average n of the (c) component is from 5 to 14 inclusive; 70 mol% or more if n is greater than 14 and less than or equal to 30; and 80 mol% or more if n is greater than 30 and less than or equal to 150.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a dispersant for a hydraulic composition. [Background technology]

[0002] In recent years, with the depletion of fine aggregates such as river sand, the proportion of aggregates used that were not actively used in the past is increasing. Hydraulic compositions using such aggregates tend to have high viscosity in the fresh state, low fluidity, and low workability even at normal water-cement ratios (W / C). In addition, the proportion of natural gypsum containing clay used in gypsum, which is the raw material for gypsum boards, is increasing. Hydraulic compositions using such natural gypsum tend to have low fluidity and low workability. To address the decrease in fluidity and workability, polycarboxylic acid-based water reducers have been used up to now, but there are limitations to how well this method can be used. For this reason, additives for hydraulic compositions containing polymers with cationic compounds containing quaternary nitrogen as constituent monomers have been developed.

[0003] Patent Document 1 discloses that a powdered cement dispersant is produced by drying and powdering a mixture containing a (meth)acrylate-based cement dispersant having a specific structural unit containing an alkyleneoxy group and water. However, it discloses that the average number of moles n added of AO is 20 or more, and that if it is less than 20, it becomes difficult to dry and powder the compound, resulting in a gummy compound.

[0004] Patent Document 2 discloses a powder dispersant which contains a copolymer obtained by polymerizing a specific vinyl monomer (a), such as an ethylenically unsaturated carboxylic acid derivative having a polyoxyalkylene group, with a specific vinyl monomer (b), such as (meth)acrylic acid, in which the average number of moles of added oxyalkylene groups or oxystyrene groups having 2 to 4 carbon atoms is 50 to 300, the ratio of monomer (a) to monomer (b) is (a) / [(a)+(b)]×100=10 to 50 (mol %), and at least a part of the copolymer is a monovalent metal salt. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2000-26145 A [Patent Document 2] JP 2002-167255 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, such dispersants have high viscosity and are difficult to powderize, and require techniques such as increasing the (meth)acrylic acid content of the copolymer to a certain level, increasing the number of ethylene oxide units added, or increasing the degree of neutralization of the (meth)acrylic acid. [Means for solving the problem]

[0007] The present inventors (a) methacrylic acid, (b) a vinyl monomer having a cationic group, (c) one or more monomers selected from the monomers represented by general formula (1): [ka] [In the formula, R 1c and R 2c R may be the same or different and represent a hydrogen atom or a methyl group. 3c is a hydrogen atom or -C(O)O(AO) n R 4c R represents an oxyalkylene group or a phenylethylene group having 2 to 4 carbon atoms. q represents an integer of 0 to 2. p represents 0 or 1. n represents a molar average value of 5 to 150. 4c represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. A dispersant for hydraulic compositions containing copolymer A of the formula: The total molar content of (a) and (b) as constituent monomers is such that the molar average value n of the (c) component is When the ratio is 5 or more and 14 or less, it is 50 mol % or more. When it is greater than 14 and less than or equal to 30, it is 70 mol % or more; When it is greater than 30 and less than or equal to 150, it is 80 mol % or more; It has been found that the above problems can be solved by using a dispersant for hydraulic compositions, which is Effect of the Invention

[0008] According to the present invention, a dispersant for a hydraulic composition that can be easily powderized can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The dispersant for hydraulic compositions of the present application is (a) methacrylic acid, (b) a vinyl monomer having a cationic group, (c) one or more monomers selected from the monomers represented by general formula (1): [ka] [In the formula, R 1c and R 2c R may be the same or different and represent a hydrogen atom or a methyl group. 3c is a hydrogen atom or -C(O)O(AO) n R 4c R represents an oxyalkylene group or a phenylethylene group having 2 to 4 carbon atoms. q represents an integer of 0 to 2. p represents 0 or 1. n represents a molar average value of 5 to 150. 4c represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. A dispersant for hydraulic compositions containing copolymer A of the formula: The total molar content of (a) and (b) as constituent monomers is such that the molar average value n of the (c) component is When the ratio is 5 or more and 14 or less, it is 50 mol % or more. When it is greater than 14 and less than or equal to 30, it is 70 mol % or more; When it is greater than 30 and less than or equal to 150, it is 80 mol % or more; It is.

[0010] The content of copolymer A in the dispersant for hydraulic compositions may be 80% by mass or more and 100% by mass or less, and is preferably 100% by mass in terms of good performance as a dispersant.

[0011] When the content of copolymer A in the hydraulic composition dispersant is less than 100% by weight, the dispersant may contain other components such as a setting accelerator and a foaming agent.

[0012] Next, each of the constituent monomers of copolymer A will be described. <(a) Methacrylic acid> The copolymer A contained in the dispersant for hydraulic composition of the present invention contains methacrylic acid as an essential component as a constituent monomer.

[0013] <(b) Vinyl monomer having a cationic group> The copolymer A contained in the dispersant for hydraulic compositions of the present invention contains, as an essential component, a vinyl monomer having a cationic group as a constituent monomer. The vinyl monomer having a cationic group is one or more monomers selected from the monomers represented by the general formula (2): [ka] [In the formula, R 1b R represents a hydrogen atom or a methyl group. 2b , R 3b and R 4b are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Y represents an oxygen atom or an -NH- group. m represents an integer of 1 to 6. X - indicates the counter anion. Ammonium salts represented by the following formula are preferred because they have good dispersing properties.

[0014] R in general formula (2) 1b As the alkyl group, a methyl group is preferred in that it can be easily powdered.

[0015] Examples of Y in the general formula (2) include an oxygen atom and an -NH- group, with the oxygen atom being preferred because it is easy to powder.

[0016] In formula (2), m is preferably from 1 to 6, and more preferably 2, in that good performance as a dispersant is obtained.

[0017] R in general formula (2) 2b , R 3b and R 4b Examples of R include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a hexyl group, a 2-ethylhexyl group, a cyclohexyl group, an octyl group, a cyclooctyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, and an octadecyl group. 2b , R 3b and R 4b It is preferable that two of the groups are methyl groups and one is an ethyl group.

[0018] X in general formula (2) - Examples of the ion include halide ions such as chloride ion, bromide ion, iodide ion, sulfate ion, nitrate ion, perchlorate ion, phosphate ion, methyl sulfate ion, ethyl sulfate ion, phenyl sulfate ion, tolyl sulfate ion, acetate ion, acetylacetonate ion, etc. In terms of easy availability, methyl sulfate ion or ethyl sulfate ion is preferred, and ethyl sulfate ion is more preferred.

[0019] <(c) Monomer I> The constituent monomer of the copolymer A contained in the hydraulic composition dispersant of the present invention is one or more monomers c selected from the monomers represented by the general formula (1): [ka] [In the formula, R 1c and R 2c R may be the same or different and represent a hydrogen atom or a methyl group. 3c is a hydrogen atom or -C(O)O(AO) n R4c R represents an oxyalkylene group or a phenylethylene group having 2 to 4 carbon atoms. q represents an integer of 0 to 2. p represents 0 or 1. n represents a molar average value of 5 to 150. 4c represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. Contains as an essential ingredient.

[0020] Examples of A in the general formula (1) include ethylene, propylene, butylene, methylethylene, 1-methylpropylene, 2-methylpropylene, and phenylethylene. These may also be mixed. The ethylene group is preferred because of its excellent performance as a dispersant.

[0021] In the general formula (1), q represents an integer of 0 or more and 2 or less. An integer of 0 is preferable in that the performance as a dispersant is good.

[0022] In the general formula (1), p represents 0 or 1. 1 is preferred in that it provides good performance as a dispersant.

[0023] In the general formula (1), n ​​indicates the molar average value of the monomer c when the monomer c is one type. When two or more monomers are used as the monomer c, n indicates the molar average value calculated by taking into account the molar content of each monomer.

[0024] The value of n is preferably 1 or more, more preferably 3 or more, and even more preferably 5 or more, in terms of good performance as a dispersant, and is preferably 150 or less, more preferably 140 or less, and even more preferably 130 or less.

[0025] In the general formula (1), R 1c , R 2c and R 3c R is a good dispersant. 1 and R 3 is a hydrogen atom, R 2c is preferably a methyl group.

[0026] In the general formula (1), R 4cSpecific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, hexyl, 2-ethylhexyl, cyclohexyl, octyl, cyclooctyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, etc. The methyl group is preferred because of its good performance as a dispersant.

[0027] Copolymer A contained in the dispersant for hydraulic compositions may be isolated after the polymerization reaction, but may not be isolated and may contain unreacted monomers (a) to (c). If the yield of copolymer A is greater than 95%, the molar ratio of the constituent monomers charged in the production of the copolymer can be considered to be the molar ratio of the constituent monomers in copolymer A.

[0028] In addition, when copolymer A is not isolated and contains unreacted monomers (a) to (c), the total content of the unreacted monomers is preferably 5% or less based on the total amount of each monomer charged, from the viewpoint of facilitating powderization.

[0029] The content of methacrylic acid as a constituent monomer contained in copolymer A is preferably 1 mol % or more, more preferably 1.5 mol % or more, and preferably 25 mol % or less, more preferably 20 mol % or less, in terms of ease of powderization.

[0030] The content of component (b) as a constituent monomer contained in copolymer A is preferably 40 mol % or more, more preferably 45 mol % or more, and preferably 75 mol % or less, more preferably 70 mol % or less, in terms of ease of powderization.

[0031] The content of component (c) as a constituent monomer contained in copolymer A is preferably 10 mol % or more, more preferably 15 mol % or more, and preferably 60 mol % or less, more preferably 50 mol % or less, in terms of ease of powderization.

[0032] In terms of ease of powderization, the total molar content of (a) and (b) as constituent monomers is preferably 50 mol % or more when the value of n in the (c) component of general formula (1) is 5 or more and 14 or less, 70 mol % or more when the value is more than 14 and 30 or less, and 80 mol % or more when the value is more than 30 and 150 or less.

[0033] The weight average molecular weight (Mw) of copolymer A is preferably 20,000 or more, more preferably 3,000 or more, in terms of good performance as a dispersant, and is preferably 100,000 or less, more preferably 80,000 or less. In addition, the ratio of Mw to the number average molecular weight (Mn), Mw / Mn, is preferably 1.0 or more and 2.0 or less in terms of good performance as a dispersant.

[0034] Copolymer A of the present invention can be produced under the conditions for copolymerization of general-purpose vinyl polymers. For example, water can be used as the solvent. The reaction temperature is in the range of 50°C to 100°C. The reaction time varies depending on the reaction temperature, but can be in the range of 0.5 hours to 10 hours.

[0035] The production of Copolymer A of the present invention is preferably carried out at a pH of 3 or less in terms of good yield.

[0036] The weight average molecular weight of copolymer A can be adjusted by adding a chain transfer agent, such as general-purpose thiols such as β-mercaptopropionic acid, 2-mercaptoethanol, 2-ethylhexyl-β-mercaptopropionic acid, methoxybutyl β-mercaptopropionate, and octadecyl 3-mercaptopropionate, or carbon tetrachloride.

[0037] The hydraulic composition dispersant of the present invention provides a high-performance hydraulic composition dispersant by drying and powdering an aqueous solution of a (meth)acrylate-based hydraulic composition dispersant having a specific structure, making it possible to use the dispersant in premix products, and furthermore, exhibiting superior performance with a smaller addition amount compared to conventional hydraulic composition dispersants. EXAMPLES

[0038] <Examples and Comparative Examples> Copolymer A of the example and copolymer A' of the comparative example were prepared using the following components (a) to (c).

[0039] <Composition ingredients> The compositions of the examples and comparative examples were prepared using the following ingredients. [Component (a)] Methacrylic acid was used, and acrylic acid was also used for comparison. [(b) component] MOEDES: Ethyl [2-(methacryloyl)ethyl] dimethylammonium ethyl sulfate DMAEM-Q: 2-(acryloyl)ethyltrimethylammonium chloride [(c) component] The ester of polyethylene glycol monomethyl ether and methacrylic acid shown in general formula (8) was used. [ka] The molar average value of n is as follows: MEPEG(9):n=9 MEPEG(23):n=23 MPEG(120):n=120 In addition, vinyloxybutyl polyethylene glycol (66) of the following formula (9) was used as a comparative compound. [ka]

[0040] [Chain transfer agent] β-mercaptopropionic acid was added in an amount of 2.0 to 7.0 mol % based on the total amount of components (a), (b), and (c).

[0041] <Production of dispersant for hydraulic composition by copolymerization reaction> The procedure will be described below using the production of A-4 in Table 1 as an example. 147.0 g of water was placed in a glass reaction vessel equipped with a stirrer, and the inside of the vessel was replaced with nitrogen while stirring, and the temperature was raised to 80° C. in a nitrogen atmosphere. (i) (a) 3.48g of methacrylic acid, (b) 49.9g of 90% aqueous solution of ethyl [2-(methacryloyl)ethyl] dimethyl ammonium ethyl sulfate (MOEDES), (C) 260.4g of MEPEG (120) (water content 40.65%) and 0.19g of Dequest 2066 (25% aqueous solution) as a chelating agent were mixed and dissolved, (ii) an aqueous solution of 1.26g of β-mercaptopropionic acid dissolved in 18g of water as a chain transfer agent, and (iii) an aqueous solution of 1.94g of ammonium persulfate dissolved in 18g of water were each added dropwise over 1.5 hours. Next, an aqueous solution of 0.77g of ammonium persulfate dissolved in 6g of water was added dropwise over 30 minutes, and then the mixture was aged at the same temperature (80°C) for 1 hour. A polymer with a weight average molecular weight Mw of 58,000 and a molecular weight distribution Mw / Mn of 1.42 was obtained. The pH of the reaction system during copolymerization was 2.2. Other copolymers were also produced in the same manner as above, except that the types and amounts of monomers used were changed.

[0042] The average molecular weight and yield of the dispersant obtained by the above-mentioned production method are shown in Table 1. In the table, n indicates the average number of ethylene oxide moieties added to MEPEG of component (c) and vinyloxybutyl polyethylene glycol (66) of formula (8).

[0043] [Table 1]

[0044] <Evaluation of dry powder properties> The reaction product containing the copolymer and water prepared above was placed in an aluminum cup, and the concentration and amount were adjusted so that the film thickness after drying would be about 1 mm. The reaction product was then placed in a flat container and dried in a thermostatic dryer at 105°C for 10 hours. A test piece of 40 mm x 15 mm was prepared from the dried thin film, and a bending force was applied from the other end by hand, with the test piece being pinched between fingers at a point about 1 cm from one end in the longitudinal direction. This test was carried out at an ambient temperature of 20°C, and the behavior was observed to confirm the sheet formability and powderization ease of the dried product from the reaction product, and was evaluated as dry powderability based on the following criteria. The results are shown in Table 1. ◯: Sheet formation is possible, and when the obtained sheet is bent at 20°, a crack having a length of 1 cm or more is generated. ×: Sheet formation is possible, but the resulting sheet is elastic, that is, no cracks longer than 1 cm are formed even when bent at 20°, or the dried product remains liquid, making sheet formation impossible. The results are shown in Table 2.

[0045] [Table 2]

[0046] When copolymers A-1 to A-4 were used, good easiness of powderization was demonstrated (Examples 1 to 4).

[0047] On the other hand, when A'-1 and A'-2 in which methacrylic acid was not copolymerized were used as dispersants, powderization was not easy (Comparative Examples 1 and 2). In addition, A'-3 (Comparative Example 3), where n=9 in the general formula (7) but the molar content of the (a) component plus the (b) component is less than 50 mol%, A'-4 (Comparative Example 4), where n=23 but the molar content of the (a) component plus the (b) component is less than 70 mol%, and A'-5 (Comparative Example 5), where n=120 but the molar content of the (a) component plus the (b) component is less than 80 mol%, did not show good powderization ease. Furthermore, A'-5, which used more than 50 mol% of methacrylic acid, also showed low powderization ease (Comparative Example 6).

Claims

1. (a) methacrylic acid, (b) a vinyl monomer having a cationic group; (c) one or more monomers selected from the monomers represented by general formula (1): 【Chemical 1】 [In the formula, R １ｃ and R ２ｃ are the same or different and represent a hydrogen atom or a methyl group. ３ｃ is a hydrogen atom or -C(O)O(AO) ｎ R ４ｃ AO represents an oxyalkylene group or a phenylethylene group having 2 to 4 carbon atoms. q represents an integer of 0 to 2. p represents 0 or 1. n represents a molar average value of 5 to 150. R ４ｃ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. A dispersant for hydraulic compositions containing copolymer A of the formula: The total molar content of (a) and (b) as constituent monomers is such that the molar average value n of the component (c) is When the ratio is 5 or more and 14 or less, it is 50 mol% or more. When it is greater than 14 and less than 30, it is 70 mol% or more; When it is greater than 30 and less than 150, it is 80 mol% or more; The dispersant for hydraulic compositions is

2. 2. The dispersant for hydraulic compositions according to claim 1, wherein the copolymer A contains (a) methacrylic acid as a constituent monomer in an amount of 1 mol % to 25 mol %.

3. 2. The dispersant for hydraulic compositions according to claim 1, wherein the vinyl monomer (b) having a cationic group is one or more monomers b selected from vinyl monomers of general formula (2). 【Chemistry 2】 [In the formula, R １ｂ represents a hydrogen atom or a methyl group. ２ｂ , R ３ｂ and R ４ｂ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Y represents an oxygen atom or an -NH- group. m represents an integer of 1 to 6. X － indicates a counter anion.

4. 2. The dispersant for hydraulic compositions according to claim 1, wherein the vinyl monomer (b) having a cationic group is one or more monomers b selected from vinyl monomers of general formula (3). 【Chemistry 3】 [In the formula, R ２ｂ , R ３ｂ and R ４ｂ each independently represents a hydrogen atom or a methyl group; Y represents an oxygen atom or an —NH— group; and m represents an integer of 1 or more and 6 or less. X － indicates a counter anion.

5. 2. The dispersant for hydraulic compositions according to claim 1, wherein the vinyl monomer (b) having a cationic group is one or more monomers b selected from vinyl monomers of general formula (4). 【Chemistry 4】 [In the formula, X － indicates a counter anion.

6. X － The dispersant for hydraulic compositions according to any one of claims 3 to 5, wherein is a methyl sulfate ion or an ethyl sulfate ion.

7. 2. The dispersant for hydraulic compositions according to claim 1, wherein the monomer c is one or more monomers selected from the monomers of general formula (5). 【Chemistry 5】 [In the formula R １ｃ and R ２ｃ are the same or different and represent a hydrogen atom or a methyl group. ３ｃ is a hydrogen atom or -C(O)O(AO) ｎ R ４ｃ AO represents an oxyalkylene group or a phenylethylene group having 2 to 4 carbon atoms. n represents a molar average value of 5 to 150. R ４ｃ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms.

8. 2. The dispersant for hydraulic compositions according to claim 1, wherein the monomer c is one or more monomers selected from the monomers of general formula (6). 【Chemistry 6】 [In the formula R ４ｃ represents a hydrogen atom or an alkyl group having from 1 to 18 carbon atoms; AO represents an oxyalkylene group or a phenylethylene group having from 2 to 4 carbon atoms; and n represents a molar average value of from 5 to 150.

9. 2. The dispersant for hydraulic compositions according to claim 1, wherein the monomer c is one or more monomers selected from the monomers of general formula (7). 【Chemistry 7】 [In the formula, n represents a molar average value of 5 to 150.]

10. 2. The dispersant for hydraulic compositions according to claim 1, wherein the copolymer A has a weight average molecular weight (Mw) of 30,000 or more and 80,000 or less, and a ratio of Mw to number average molecular weight (Mn), Mw / Mn, of 1.0 or more and 2.0 or less.

11. 2. The dispersant for hydraulic compositions according to claim 1, wherein the total content of unreacted monomers (a) to (c) in copolymer A is 5 mol % or less based on the total amount of each monomer charged.

12. The dispersant for hydraulic compositions according to claim 1 , comprising a copolymer A obtained by copolymerization at a pH of 3 or less.

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