METHOD FOR PRODUCING POWDER DISPERSANT COMPOSITION FOR HYDRAULIC COMPOSITIONS

Abstract

The present invention is a method for producing a powder dispersant composition for hydraulic compositions including, drying a mixture containing a copolymer having constituent unit (1) represented by the following formula (1) and constituent unit (2) represented by the following formula (2) and water to produce a powder containing the copolymer, wherein: when the copolymer is a copolymer whose n in constituent unit (2) is less than 40, the mixture is dried by a thin film drying method or a spray drying method with a pH of 11 or more and 14 or less; when the copolymer is a copolymer whose n in constituent unit (2) is 40 or more and less than 80, the mixture is dried by a thin film drying method or a spray drying method with a pH of 9 or more and 14 or less; and when the copolymer is a copolymer whose n in constituent unit (2) is 80 or more, the mixture is dried by a thin film drying method or a spray drying method with a pH of 7 or more and 14 or less,

##STR00001## wherein R.sup.1 and R.sup.3 are the same or different and individually represent a hydrogen atom or a methyl group; R.sup.2 and R.sup.4 are the same or different and individually represent a hydrogen atom or an alkyl group with 1 or more and 3 or less carbons; M represents a hydrogen atom, an alkali metal, an alkaline-earth metal, ammonium or an organic ammonium; p represents a number of 0 or more and 2 or less; q represents a number of 0 or 1; and n represents an average number of added moles and a number of 5 or more and 150 or less.

Claims

1. (canceled)

2: A method for producing a powder dispersant composition for hydraulic compositions comprising, drying a mixture containing a copolymer having a constituent unit (1) represented by formula (1) and a constituent unit (2) represented by formula (2) and water to produce a powder containing the copolymer, wherein: when the copolymer is a copolymer whose n in the constituent unit (2) is less than 40, the mixture is dried with a pH of 11 or more and 14 or less; when the copolymer is a copolymer whose n in the constituent unit (2) is 40 or more and less than 80, the mixture is dried with a pH of 9 or more and 14 or less; when the copolymer is a copolymer whose n in the constituent unit (2) is 80 or more and less than 100, the mixture is dried with a pH of more than 9 and 14 or less; and when the copolymer is a copolymer whose n in the constituent unit (2) is 100 or more, the mixture is dried with a pH of 7 or more and 14 or less, ##STR00003## wherein R.sup.1 and R.sup.3 are the same or different and individually represent a hydrogen atom or a methyl group; R.sup.2 and R.sup.4 are the same or different and individually represent a hydrogen atom or an alkyl group with 1 or more and 3 or less carbons; M represents a hydrogen atom, an alkali metal, an alkaline-earth metal, ammonium or an organic ammonium; p represents a number of 0 or more and 2 or less; q represents a number of 0 or 1; and n represents an average number of added moles and a number of 5 or more and 150 or less.

3: The method for producing a powder dispersant composition for hydraulic compositions according to claim 2, wherein the mixture is dried by heat drying.

4: The method for producing a powder dispersant composition for hydraulic compositions according to claim 2, wherein the mixture is dried by a thin film drying method or a spray drying method.

5. (canceled)

6: The method for producing a powder dispersant composition for hydraulic compositions according to claim 2, wherein a proportion of the total of the constituent unit (1) and the constituent unit (2) in all constituent units of the copolymer is 80 mol % or more.

7: The method for producing a powder dispersant composition for hydraulic compositions according to claim 2, wherein a molar ratio of the constituent unit (1) and the constituent unit (2) in the copolymer, constituent unit (1)/constituent unit (2), is 1 or more and 10 or less.

8: The method for producing a powder dispersant composition for hydraulic compositions according to claim 2, wherein a pH of the mixture of the copolymer is adjusted with a hydroxide of an alkali metal or an alkaline-earth metal.

9: The method for producing a powder dispersant composition for hydraulic compositions according to claim 2, wherein the copolymer has a weight average molecular weight of 20,000 or more and 70,000 or less.

10: The method for producing a powder dispersant composition for hydraulic compositions according to claim 2, wherein q in the formula (2) is 1.

11: The method for producing a powder dispersant composition for hydraulic compositions according to claim 2, wherein a powder dispersant composition for hydraulic compositions having a median diameter (D50) of 1 μm or more and 90 μm or less and a proportion of particles with a particle size of 1 μm or more and 250 μm or less of 90 mass % or more and 100 mass % or less is produced.

12: A powder dispersant composition for hydraulic compositions produced by the method according to claim 2, wherein the powder dispersant composition for hydraulic compositions has a median diameter (D50) of 1 μm or more and 90 μm or less and a proportion of particles with a particle size of 1 μm or more and 250 μm or less of 90 mass % or more and 100 mass % or less.

13: A powdered hydraulic composition formulated with a hydraulic powder and the powder dispersant composition for hydraulic compositions according to claim 12.

Description

EXAMPLES

Example 1 and Comparative Example 1

(1) Preparation of Aqueous Solution for Dispersant

[0093] An aqueous solution containing each of the following copolymers and water was prepared. This aqueous solution had a solids concentration of the copolymer of 40 mass % and a pH (25° C.) of 3. A 48% sodium hydroxide aqueous solution (manufactured by Kanto Chemical Co., Inc.) was added thereto to adjust the pH to values as shown in Table 1, thereby preparing various aqueous solutions for dispersant. The pH of the above aqueous solution and aqueous solutions for dispersant was measured by an electrode-type pH meter (manufactured by Horiba, Ltd.) at 25° C. Hereinafter, pH measurement was carried out according to the same method for the other examples and comparative examples. The types of copolymers used or the like are also listed together in Table 1.

<Copolymer>

[0094] Copolymer A: methacrylic acid/methoxypolyethylene glycol (25) monomethacrylate=75 moles/25 moles (the numeral shown in parentheses is n which is an average number of added moles in the formula (2), the same applies hereinafter), weight average molecular weight=50,000, pH 3 (active solids content: 40 mass %, measurement was carried out by the electrode-type pH meter at 25° C., the same applies hereinafter) [0095] Copolymer B: acrylic acid/methacrylic acid/methoxypolyethylene glycol (45) monomethacrylate=35 moles/35 moles/30 moles, weight average molecular weight=40,000, pH 3 [0096] Copolymer C: acrylic acid/polyethylene glycol (55) methallyl ether=80 moles/20 moles, weight average molecular weight=35,000, pH 3 [0097] Copolymer D: methacrylic acid/methoxypolyethylene glycol (120) monomethacrylate=90 moles/10 moles, weight average molecular weight=39,000, pH 3

Example 1 and Comparative Example 1

(1) Production of Powder Dispersant Composition for Hydraulic Compositions by Spray Drying Method

[0098] Some aqueous solutions for dispersant prepared as described above were spray-dried by actual powderization equipment to evaluate the ease of drying. The powderization equipment used was provided with a disk atomizer, an air blower and a dryer, and the dryer inlet and outlet temperatures were 150° C. and 80° C., respectively, the ambient temperature was 20° C. and the number of revolutions of the disk atomizer was 18,000 rpm. Each obtained product was thereafter put through a 1-mm mesh sieve for removing coarse particles and foreign substances, and those passing therethrough were used for testing as a powder dispersant composition for hydraulic compositions.

(2) Production of Powder Dispersant Composition for Hydraulic Compositions by Drum Drying Method

[0099] Some aqueous solutions for dispersant prepared as described above were formed into sheets by actual drum drying equipment. The powderization equipment used was provided with a drying drum and a scraper, and the drying drum area was 6.2 m.sup.2, the number of revolutions of the drying drum was 3.1 rpm, the drying drum temperature was 130° C. and the ambient temperature was 30° C. Subsequently, each obtained sheet was cooled by actual drum cooling equipment and ground by a feather mill. The cooling equipment was installed near the powderization equipment such that sample sheets peeled off by the scraper from the above drum drying equipment were continuously conveyed to the cooling equipment. The cooling equipment used was provided with a cooling drum, and the cooling drum area was 5.8 m.sup.2, the number of revolutions of the cooling drum was 1.5 rpm, the cooling drum temperature was 22° C. and the ambient temperature was 30° C. The dried product after grinding was put through a 700-μm mesh sieve to remove coarse particles or foreign substances, and thereafter used for testing as a powder dispersant composition for hydraulic compositions.

(3) Production of Powder Dispersant Composition for Hydraulic Compositions by Disk Drying Method

[0100] Some aqueous solution for dispersant prepared as described above was formed into a sheet by pilot disk drying equipment. The powderization equipment used was provided with a drying disk and a scraper, and the drying disk area was 0.4 m.sup.2, the number of revolutions of the drying drum was 1.5 rpm, the drying drum temperature was 140° C. and the ambient temperature was 30° C. Subsequently, the obtained dried product was cooled by actual cooling equipment and ground by a feather mill. The cooling/grinding equipment used had the function of sending cold air at 10° C., and the dried product was ground while cooled until the surface temperature thereof reached about 20° C. The dried product after grinding was put through a 700-μm mesh sieve to remove coarse particles or foreign substances, and thereafter used for testing as a powder dispersant composition for hydraulic compositions.

[0101] Note that, in all of the methods, a difference in sieve meshes did not affect the final particle size. For each powder dispersant composition for hydraulic compositions, particle size distribution measurement was carried out by the method mentioned earlier, and the median diameter (D50; μm) and the proportion of particles with a particle size of 1 μm or more and 250 μm or less (mass %) were measured and calculated. The results are shown in Table 1.

(4) Calculation of Yield of Powder Dispersant Composition for Hydraulic Compositions

[0102] The yield of each powder dispersant composition for hydraulic compositions obtained by the above operation (1), (2) or (3) was calculated on the basis of the following calculation formula. The results are shown as “yield” in Table 1.

Yield of powder dispersant composition for hydraulic compositions (%)=[X×100]/[Y×Z]

[0103] X: mass of powder dispersant composition for hydraulic compositions (g)

[0104] Y: mass of aqueous solution for dispersant used for production (g)

[0105] Z: solids content of aqueous solution for dispersant used for production (mass %)

[0106] The solids content of the aqueous solution for dispersant was calculated by the following formula on the basis of a change in mass when 2 g of the aqueous solution for dispersant sampled in an aluminum cup was dried and solidified at 105° C. for 2 hours.

Solids content of aqueous solution for dispersant (%)=[mass of aqueous solution for dispersant after drying and solidification (g)×100]/mass of aqueous solution for dispersant before drying and solidification (g)

TABLE-US-00001 TABLE 1 Powder dispersant composition for hydraulic compositions Aqueous solution for dispersant Proportion of particles Copolymer Median with particle size n in Drying Yield diameter of 1 gm or more and Type formula (2) pH method (%) (D50; μm) 250 gm or less (mass %) Comparative 1-1 Copolymer A 25 3 Drum drying  0* — — example method 1-2 10 Drum drying  0* — — method Example 1-1 13 Drum drying 97.1 98.5 88.0 method 1-2 11 Spray drying 97.9 71.5 94.9 method 1-3 13 Spray drying 99.2 60.9 98.2 method Comparative 1-3 Copolymer B 45 3 Drum drying  0* — — example method 1-4 8 Drum drying  0* — — method Example 1-4 10 Drum drying 95.5 120.1  87.4 method 1-5 9 Spray drying 98.8 60.1 97.1 method 1-6 11 Spray drying 99.2 45.5 99.0 method Comparative 1-5 Copolymer C 55 5 Drum drying  0* — — example method Example 1-7 10 Spray drying 96.8 78.3 96.9 method Comparative 1-6 Copolymer D 120 3 Drum drying  0* — — example method Example 1-8 7 Drum drying 96.2 135.1  93.3 method Comparative 1-7 6 Spray drying 64.8 65.2 87.6 example method Example 1-9 8 Spray drying 98.8 60.9 97.4 method 1-10 11 Spray drying 99.4 54.7 96.1 method 1-11 13 Spray drying 99.1 49.2 98.0 method 1-12 8 Disk drying 97.1 141.1  76.6 method *Composition is in gel form or rubber form, and powdered dried product cannot be obtained.

[0107] As shown in Table 1, the powder dispersant compositions for hydraulic compositions of examples 1-1 to 1-12 exhibited superior yields as compared with those of comparative examples 1-1 to 1-7. This is considered to be because pH enhancement improved the ease of drying of the aqueous solutions for dispersant and effectively promoted the drying processes, thereby improving the efficiency of spray drying or grinding.

[0108] Considering that the drum drying method has the same drying performance as the spray drying method for materials with the same moisture content, and that the ancillary cooling equipment is also used in the drum drying method, materials which cannot be powderized by the drum drying method naturally cannot be powderized by the spray drying method.