Patent Application
20080027177
The following examples illustrate the present invention more specifically. They are, however, by no means limitative of the scope of the invention. In the examples, “%” represents “% by mass”, unless otherwise specified.
A glass-made reaction tank (content: 1 liter) equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube and reflux condenser was charged with 377 g of water. The reaction vessel inside was purged with nitrogen under stirring, and heated to 70° C. in a nitrogen atmosphere. Then, to the reaction vessel, a mixed solution composed of 239 g of methoxypolyethylene glycol monomethacrylate (average molar number of addition of ethylene oxide 10), 64 g of methacrylic acid, 14 g of sodium methacrylate, 9 g of 3-mercaptopropionic acid and 92 g of deionized water was added dropwise over 5 hours. At the same time, an aqueous solution dissolving 5.1 g of a 30% hydrogen peroxide solution in 50 g of water and an aqueous solution dissolving 2.0 g of L-ascorbic acid in 50 g of water were added thereto dropwise over 6 hours. Further at the same time, dropping of 57 g of methyl methacrylate was started at a feed rate of 0.148 g/min. After the lapse of 235 minutes from starting the dropping, the feed rate of methyl methacrylate was changed to 0.344 g/min., and the dropping was completed in 5 hours.
After completion of the dropping, the reaction mixture was maintained at 70° C. for 1 hour. Moreover, the pH of this reaction mixture was adjusted to 7 with sodium hydroxide to obtain a polycarboxylic acid (P-1) of the present invention with a weight average molecular weight of 7700 as determined by gel permeation chromatography and expressed on the polyethylene glycol equivalent basis.
A glass-made reaction tank (content: 0.5 liter) equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube and reflux condenser was charged with 70 g of water. The reaction vessel inside was purged with nitrogen under stirring, and heated to 70° C. in a nitrogen atmosphere. Then, to the reaction vessel, a mixed solution composed of 121 g of methoxypolyethylene glycol monomethacrylate (average molar number of addition of ethylene oxide 6), 36 g of methacrylic acid, 4.3 g of 3-mercaptopropionic acid and 60 g of deionized water was added dropwise over 5 hours. At the same time, an aqueous solution dissolving 2.7 g of a 30% hydrogen peroxide solution in 30 g of water and an aqueous solution dissolving 1.0 g of L-ascorbic acid in 30 g of water were added dropwise over 6 hours. Further at the same time, 27.5 g of methyl methacrylate was added thereto dropwise in 5 hours. After completion of the dropping, the reaction mixture was maintained at 70° C. for 1 hour. Furthermore, the pH of this reaction mixture was adjusted to 7 with sodium hydroxide to obtain a polycarboxylic acid (P-2) of the present invention with a weight average molecular weight of 8900 as determined by gel permeation chromatography and expressed on the polyethylene glycol equivalent basis.
A glass-made reaction tank (content: 0.5 liter) equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube and reflux condenser was charged with 80 g of water. The reaction vessel inside was purged with nitrogen under stirring, and heated to 70° C. in a nitrogen atmosphere. Then, to the reaction vessel, a mixed solution composed of 109 g of methoxypolyethylene glycol monomethacrylate (average molar number of addition of ethylene oxide 25), 22 g of methacrylic acid, 18 g of methyl methacrylate, 1.7 g of 3-mercaptopropionic acid and 37 g of deionized water was added dropwise over 5 hours. At the same time, an aqueous solution dissolving 2.6 g of ammonium persulfate salt in 30 g of water was added dropwise over 6 hours. After completion of the dropping, the reaction mixture was maintained at 70° C. for 1 hour. Furthermore, the pH of this reaction mixture was adjusted to 7 with sodium hydroxide to obtain a polycarboxylic acid (P-3) of the present invention with a weight average molecular weight of 18000 as determined by gel permeation chromatography and expressed on the polyethylene glycol equivalent basis.
A glass-made reaction tank (content: 1 liter) equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube and reflux condenser was charged with 273 g of water. The reaction vessel inside was purged with nitrogen under stirring, and heated to 80° C. in a nitrogen atmosphere. Then, to the reaction vessel, a mixed solution composed of 375 g of methoxypolyethylene glycol monomethacrylate (average molar number of addition of ethylene oxide 25), 75 g of methacrylic acid, 3.3 g of 3-mercaptopropionic acid and 100 g of deionized water was added dropwise over 5 hours. At the same time, an aqueous solution dissolving 3 g of a 30% hydrogen peroxide solution in 50 g of water and an aqueous solution dissolving 1.2 g of L-ascorbic acid in 50 g of water were added dropwise over 6 hours. After completion of the dropping, the reaction mixture was maintained at 80° C. for 1 hour to obtain a comparative polycarboxylic acid (H-1) with a weight average molecular weight of 24000 as determined by gel permeation chromatography and expressed on the polyethylene glycol equivalent basis.
With the monomer compositions shown in Table 1 below, polycarboxylic acids (P-2) to (P-13) were obtained in the same manner as Example 1, and polycarboxylic acids (H-2) to (H-9) for comparison were obtained in the same manner as Comparative Example 1. The weight average molecular weights of the polycarboxylic acids (P-4) to (P-13) and (H-2) to (H-9) were measured by gel permeation chromatography in terms of polyethylene glycol are shown in Table 1.
With the monomer compositions shown in Table 2 below, polycarboxylic acids (S-1) to (S-6) were obtained in the same manner as Comparative Example 1. The weight average molecular weights of the polycarboxylic acids (S-1) to (S-6) were measured by gel permeation chromatography in terms of polyethylene glycol are shown in Table 2.
The descriptions in Table 1 and 2 are as follows.
By a concrete test, the polycarboxylic acids obtained in Examples 1 to 3 and Comparative Examples 1 to 9 were evaluated as concrete admixtures. The results are shown in Table 3. Moreover, these polycarboxylic acids were mixed in mass rarios shown in Table 4, and the resultants were evaluated as concrete admixtures. The results are shown in Table 4. The concrete test conditions are as follows.
The above materials were mixed with a pan mixer for 90 seconds.
The slump immediately after the mixing was measured by setting at 23.5 to 25 cm.
The amounts of addition (amounts of addition in terms of the solid matters) of the polycarboxylic acids obtained in Examples 1 to 3 and Comparative Examples 1 to 3 relative to 100% by mass of the solid matters of the cement were adjusted as shown in Table 3 and 4. The amount of addition shown in Examples a to h of Table 4 indicates the amount of addition (amount of addition in terms of solid matter) in the state that a polycarboxylic acid is mixed.
In Table 3 and 4, various properties were evaluated as follows.
The water-reducing ability was compared for an amount required for providing the predetermined slump value. Those requiring a small amount of addition were evaluated as good in water-reducing ability, and those requiring a large amount of addition were evaluated as poor in water-reducing ability. Specifically, it was evaluated as the following criteria.
The slump-retaining ability was compared for ratios after the lapse of 60 minutes relative to the initial slump value. Those with high ratios were evaluated as good in slump-retaining ability, and those with low ratios were evaluated as poor in slump-retaining ability. Specifically, it was evaluated as the following criteria.
The concrete condition was evaluated as follows. Those high in concrete viscosity when mixed with a scoop and with a large amount of adhesion of mortar to the scoop are poor in concrete condition. As the concrete viscosity becomes lower and the adhesion of mortar becomes smaller, the concrete condition becomes better. Specifically, it was evaluated as the following criteria.
As shown in Table 3, Comparative Example A using the polycarboxylic acid (H-1) is excellent in the water-reducing ability, but remarkably poor in the slump-retaining ability and concrete condition. Comparative Example C using the polycarboxylic acid (H-2) and Comparative Example D using the polycarboxylic acid (H-3) are good in the water-reducing ability, but poor in the slump-retaining ability and concrete condition. Comparative Example D using the polycarboxylic acid (H-4), Comparative Example F using the polycarboxylic acid (H-6), and Comparative Example I using the polycarboxylic acid (H-9) are good in the retaining ability, but remarkably poor in the water-reducing ability. Comparative Example E using the polycarboxylic acid (H-5), Comparative Example G using the polycarboxylic acid (H-7), and Comparative Example H using the polycarboxylic acid (H-8) are remarkably poor in the concrete condition.
Meanwhile, Examples A to M using the polycarboxylic acids (P-1) to (H-13) are good in all of the water-reducing ability, retaining ability and condition.
Furthermore, as shown in Table 4, Comparative Examples a to i using the polycarboxylic acids (H-1), (H-2), (H-3), (S-1), (S-2), (S-3), (S-4), (S-5) and (S-6) are excellent in the water-reducing ability, but poor in the slump-retaining ability and concrete condition.
Meanwhile, Examples a to h mixing the polycarboxylic acids (P-1) or (P-8) of the present invention are improved in the slump-retaining ability and concrete condition while maintaining the water-reducing ability.
The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2003-132287, filed May 9, 2003, entitled “POLYCARBOXYLIC ACID CONCRETE ADMIXTURE”. The content of this application is incorporated herein by reference in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-132287 | May 2003 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP04/06475 | 5/7/2004 | WO | 00 | 7/17/2006 |
