Dispersants for clay-containing hydraulic composition

Abstract

To provide dispersants exhibiting good performance even for a clay-containing hydraulic composition.SOLUTION: A dispersant for a clay-containing hydraulic composition contains a copolymer A of (a) methacrylic acid, (b) a vinyl monomer having a cationic group, and (c) one or more monomers 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 a molar average from 5 to 150 inclusive; and R4c represents a hydrogen atom or a C1-18 alkyl group.]SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a dispersant for a clay-containing 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 an additive for hydraulic compositions containing a cationic polymer (A) containing a quaternary nitrogen atom to which is bonded a polyoxyalkylene group containing an alkyl group having 1 to 22 carbon atoms or an oxyalkylene group having 1 to 8 carbon atoms.

[0004] Patent Document 2 discloses an additive for hydraulic compositions containing a cationic polymer (A) that satisfies the following: (i) the polymer has a structure derived from a vinyl monomer (a) having a cationic group and a vinyl monomer (b) having no cationic group, (ii) the molar ratio of the monomer (a) to the monomer (b) is (a) / (b)=1 / 99 to 95 / 5, and (iii) the monomer (a) contains a vinyl monomer having a quaternary nitrogen cationic group.

[0005] Patent Document 3 discloses a copolymer having (a) 16 to 95 mol % of cationic structural units (A) and (b) 5 to 55 mol % of macromonomer structural units (B) as an additive for hydraulic compositions. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-45010 A [Patent Document 2] Special Publication No. 2014-503455 [Patent Document 3] JP 2014-205606 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, it has been found that such dispersants are significantly adsorbed or absorbed by the clay contained in low-quality aggregates. In addition, monomers having quaternary ammonium groups generally have poor polymerizability, and do not provide high dispersant yields or sharp molecular weight distributions, so it is difficult to say that the performance is fully exerted. [Means for solving the problem]

[0008] 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. 4crepresents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. It has been found that the above problems can be solved by using a dispersant for a clay-containing hydraulic composition containing the copolymer A. Effect of the Invention

[0009] According to the present invention, it is possible to provide a dispersant for hydraulic compositions which exhibits high dispersibility even in low-quality aggregates containing clay. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The dispersant for a clay-containing hydraulic composition 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. The copolymer A contains the following as a constituent monomer:

[0011] The content of copolymer A in the clay-containing hydraulic composition dispersant 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.

[0012] When the content of copolymer A in the clay-containing hydraulic composition dispersant is less than 100% by weight, it may contain other components such as a setting accelerator and a foaming agent.

[0013] Next, each of the constituent monomers of copolymer A will be described. <(a) Methacrylic acid> The copolymer A contained in the clay-containing hydraulic composition dispersant of the present invention contains methacrylic acid as an essential component as a constituent monomer.

[0014] <(b) Vinyl monomer having a cationic group> The constituent monomer of the copolymer A contained in the clay-containing hydraulic composition dispersant of the present invention contains a vinyl monomer having a cationic group as an essential component. 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.

[0015] R in general formula (2) 1b As the alkyl group, a methyl group is preferred because of its good performance as a dispersant.

[0016] Examples of Y in the general formula (2) include an oxygen atom and an -NH- group. An oxygen atom is preferred because of its excellent performance as a dispersant.

[0017] In formula (2), m is preferably an integer of 1 or more and 6 or less, and more preferably 2, in that good performance as a dispersant is achieved.

[0018] R in general formula (2) 2b , R 3b and R 4b Examples of the 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.

[0019] 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.

[0020] <(c) Monomer c> The constituent monomer of the copolymer A contained in the clay-containing hydraulic composition dispersant of the present invention is one or more monomers c 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 4cR 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.

[0021] 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.

[0022] 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.

[0023] In the general formula (1), p represents 0 or 1. 1 is preferred in that it provides good performance as a dispersant.

[0024] 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.

[0025] The nc value 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.

[0026] In the general formula (1), R 1c , R 2c and R 3c R is a good dispersant. 1c and R 3c is a hydrogen atom, R 2c is preferably a methyl group.

[0027] 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.

[0028] The copolymer A contained in the clay-containing hydraulic composition dispersant 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.

[0029] 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, in terms of good dispersant performance.

[0030] 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 50 mol % or less, more preferably 45 mol % or less, in terms of good dispersant performance.

[0031] The content of component (b) as a constituent monomer contained in copolymer A is preferably 5 mol % or more, more preferably 10 mol % or more, and preferably 75 mol % or less, more preferably 70 mol % or less, in terms of good dispersant performance.

[0032] 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 90 mol % or less, more preferably 85 mol % or less, in terms of good dispersant performance.

[0033] The weight average molecular weight (Mw) of copolymer A is preferably 20,000 or more, more preferably 30,000 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 dispersant of the present invention has good dispersibility and is therefore effective even for low-quality aggregates that contain clay. EXAMPLES

[0038] <Examples and Comparative Examples> The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following descriptions.

[0039] <Composition ingredients> Copolymer A of the example and copolymer A' of the comparative example were prepared using the following components (a) to (c). [Component (a)] Methacrylic acid was used, and acrylic acid was also used for comparison.

[0040] [(b) component] MOEDES: Ethyl [2-(methacryloyl)ethyl] dimethylammonium ethyl sulfate DMAEM-Q: 2-(acryloyl)ethyltrimethylammonium chloride

[0041] [(c) component] The ester of polyethylene glycol monomethyl ether and methacrylic acid shown in general formula (7) was used. [ka] The molar average value n is as follows: MEPEG(9):n=9 MEPEG(23):n=23 MPEG(120):n=120 In addition, vinyloxybutyl polyethylene glycol (130) of the following formula (8) was used as a comparative compound. [ka]

[0042] [Chain transfer agent] β-mercaptopropionic acid was added in an amount of 1.5 to 9.0 mol % based on the total amount of components (a), (b), and (c).

[0043] <Production of Dispersant for Clay-Containing Hydraulic Composition by Copolymerization Reaction> The procedure will be described below using the production of A-6 in Table 1 as an example. 132.0 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) 4.06g of methacrylic acid, (b) 23.95g of 90% aqueous solution of ethyl [2-(methacryloyl)ethyl] dimethyl ammonium ethyl sulfate (MOEDES), (C) 303.5g of MEPEG (120) (water content 40.65%) and 0.22g of Dequest 2066 (25% aqueous solution) as a chelating agent were mixed and dissolved, (ii) an aqueous solution of 0.734g of β-mercaptopropionic acid dissolved in 18g of water as a chain transfer agent, and (iii) an aqueous solution of 1.13g of ammonium persulfate dissolved in 18g of water were each added dropwise over 1.5 hours. Next, an aqueous solution of 0.45g 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 73,000 and a molecular weight distribution Mw / Mn of 1.57 was obtained. The pH of the reaction system during copolymerization was 2.1. Other copolymers were also produced in the same manner as above, except that the types and amounts of monomers used were changed.

[0044] 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 (130) of formula (8).

[0045] [Table 1]

[0046] <Evaluation method 1 of dispersibility> The copolymer was mixed with water in an amount that would give a 1.0% addition amount relative to 100 parts by mass of Kasaoka clay, and the mixing water was adjusted to a total of 175 g. 175 g of this mixing water was added to 250 g of Kasaoka clay, and the mixture was mixed with a hand mixer for 60 seconds to obtain a clay slurry. The obtained clay slurry was filled into a cone with an upper inner diameter of 50 mm, a lower inner diameter of 50 mm, and a height of 50 mm, and the flow (mm) after extraction was measured. The results are shown in Table 2.

[0047] [Table 2]

[0048] When copolymers A-1 to A-8 produced in Examples 1 to 8 were used as dispersants, they were filled into a cone having an upper inner diameter of 50 mm, a lower inner diameter of 50 mm, and a height of 50 mm, and the flow after drawing was measured, and showed good fluidity of 119 mm or more (Examples 1 to 8).

[0049] On the other hand, when A'-1 to A'-3, which were not copolymerized with methacrylic acid, were used as dispersants, the fluidity was low, ranging from 89 to 112 mm (Comparative Examples 1 to 4). Furthermore, when A'-4, in which acrylic acid was copolymerized instead of methacrylic acid, was used, the fluidity was also low (Comparative Example 4). Furthermore, A'-5, in which more than 50 mol% of methacrylic acid was used, also had low fluidity (Comparative Example 5).

[0050] <Evaluation method 2 of dispersibility> The copolymer was mixed with water in an amount of 0.3% relative to 100 parts by mass of clay-containing gypsum, and the mixing water was adjusted to a total of 150 g. 150 g of this mixing water was added to 247 g of Yoshino Gypsum Sakura Brand A-class calcined gypsum and 15 g of bentonite (total 262 g), and the mixture was mixed with a hand mixer for 10 seconds to obtain a clay slurry. The obtained clay slurry was filled into a cone with an upper inner diameter of 50 mm, a lower inner diameter of 50 mm, and a height of 50 mm, and the flow (mm) after extraction was measured. The results are shown in Table 3.

[0051] [Table 3]

[0052] When copolymers A-1 to A-8 produced in Examples 1 to 8 were used as dispersants, they were filled into a cone having an upper inner diameter of 50 mm, a lower inner diameter of 50 mm, and a height of 50 mm, and the flow after drawing was measured, and showed good fluidity of 103 mm or more (Examples 1 to 8).

[0053] On the other hand, when A'-1 to A'-3, which were not copolymerized with methacrylic acid, were used as dispersants, the fluidity was low at 90 to 99 mm (Comparative Examples 1 to 4). In addition, when A'-4, which was copolymerized with acrylic acid instead of methacrylic acid, was used, the fluidity was also low (Comparative Example 4).

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 clay-containing hydraulic compositions containing copolymer A of the formula (I) above.

2. 2. The dispersant for clay-containing hydraulic compositions according to claim 1, wherein copolymer A contains (a) methacrylic acid as a constituent monomer in an amount of 1 mol % to 50 mol %.

3. 2. The dispersant for clay-containing 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 clay-containing 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 clay-containing 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 clay-containing hydraulic composition dispersant according to any one of claims 3 to 5, wherein is a methyl sulfate ion or an ethyl sulfate ion.

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

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

10. 2. The clay-containing hydraulic composition dispersant according to claim 1, wherein the weight average molecular weight (Mw) of copolymer A is 30,000 or more and 80,000 or less, and the ratio of Mw to number average molecular weight (Mn), Mw / Mn, is 1.0 or more and 2.0 or less.

11. 2. The clay-containing hydraulic composition dispersant 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. 2. The clay-containing hydraulic composition dispersant according to claim 1, comprising a copolymer A obtained by copolymerization at a pH of 3 or less.

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