Method for preparing a slow-release polycarboxylate water reducing agent with alcohol-water mixture as solvent and product thereof

Abstract

The application discloses a method for preparing a slow-release polycarboxylic water reducing agent by using alcohol-water mixed solution as a solvent and a product thereof. The slow-release polycarboxylic water reducing agent is prepared by using an ethanol aqueous solution as a solvent, glycol monovinyl polyoxyethylene ether, acrylic acid, an ester functional monomer, an initiator and a chain transfer agent. The ethanol aqueous solution is used as the solvent, which is beneficial to improving the solubility and conversion rate of the ester monomer, and the slow-release polycarboxylic water reducing agent obtained has stronger dispersibility and dispersion maintaining capacity for cement. The ester functional monomer is introduced into the polycarboxylic water reducing agent, the ester group is gradually hydrolyzed to generate carboxyl in an alkaline environment, the content of the carboxyl in a cement slurry is kept constant or the speed of the content reduction is slowed down, and thus the purpose of keeping the cement neat slurry fluidity for a long time is achieved. The water reducing agent prepared by the method has the advantages of good slow-release performance, high dispersibility, strong adaptability and effective inhibition of neat slurry fluidity loss.

Description

Technical Field

[0001] This invention relates to a method for preparing a slow-release polycarboxylate superplasticizer, and more particularly to a method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent, and the product thereof; belonging to the technical fields of polymer materials and concrete admixtures. Background Technology

[0002] Polycarboxylate superplasticizers effectively improve the fluidity and workability of concrete, and are widely used in large-scale infrastructure projects such as subways, bridges, nuclear power plants, and hydropower plants, becoming a mainstream product in the concrete superplasticizer industry. Due to significant differences in concrete raw materials, concrete slump often decreases too rapidly during high temperatures or long-distance transportation. In practical engineering applications, retarders such as sodium gluconate, sugar, and sodium hexametaphosphate are typically used, but the addition of these retarders cannot completely solve the problem of slump loss and may even lead to segregation, delayed bleeding, and spoilage of the concrete.

[0003] Polycarboxylate superplasticizers are the third generation of high-performance superplasticizers, and are currently one of the most promising and best-performing superplasticizers in the world. Compared with traditional naphthalene sulfonate formaldehyde condensates and melamine formaldehyde condensates, polycarboxylate superplasticizers have advantages such as low dosage, good slump retention, low concrete shrinkage, and strong adjustability in molecular structure.

[0004] Slow-release polycarboxylate superplasticizers control the dispersion process of superplasticizer molecules on cement particles through physical or chemical means, ensuring a continuous and slow dispersion over a certain period. Slow-release polycarboxylate superplasticizers can be prepared by introducing ester functional monomers. These monomers slowly hydrolyze in an alkaline environment to produce carboxyl groups, thus maintaining a constant or slowing rate of decrease in carboxyl group content in the cement paste, thereby achieving the goal of maintaining concrete slump for a longer period. However, most current slow-release polycarboxylate superplasticizers use water as a solvent, but ester monomers are not easily soluble in water. During synthesis, surfactants are often added to improve the dispersibility of ester monomers and enhance the compatibility between polymeric monomers. A search revealed no reported methods for preparing slow-release polycarboxylate superplasticizers using an alcohol-water mixture as a solvent to replace surfactants, thereby improving the dispersibility and dispersion retention of ester monomers and solving the problem of ester monomer insolubility. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent, and the product thereof.

[0006] The method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent according to the present invention comprises the following steps:

[0007] (1) Prepare an ethanol aqueous solution with a mass concentration of 20%-40% as a solvent, wherein the mass of the solvent is equal to the mass of all solutes in the prepared components; measure 2 / 3 of the total volume of the solvent solution to prepare mixture A, and measure 1 / 3 of the total volume of the solvent solution to prepare mixture B.

[0008] (2) Weigh out 160-180 parts of ethylene glycol monovinyl polyoxyethylene ether, 10-15 parts of acrylic acid, 1-3 parts of 30% hydrogen peroxide solution, 0.5-1.5 parts of chain transfer agent, and 6.6-9.1 parts of ester functional monomers according to the mass fraction, add them to the solvent used to prepare mixture A, and dissolve them by ultrasonication to obtain mixture A;

[0009] (3) Weigh out 1 part of ascorbic acid by mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0010] (4) Add mixture A to mixture B to obtain mixture C. Under constant temperature water bath conditions of 40±1℃, stir continuously for 5±1h. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.0-7.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0011] In the above method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent: the number-average molecular weight Mn of the ethylene glycol monovinyl polyoxyethylene ether is 3000 g / mol.

[0012] In the above method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent: the mass concentration of the ethanol-water solution in step (1) is preferably 30%.

[0013] In the above method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent: in step (2), preferably by weight, 171.4 parts of ethylene glycol monovinyl polyoxyethylene ether, 12.3 parts of acrylic acid, 1.5-2 parts of 30% hydrogen peroxide solution, 1 part of chain transfer agent, and 6.6 parts of hydroxyethyl acrylate, 8.1 parts of tert-butyl methacrylate, or 9.1 parts of dimethyl itaconic acid are added to the solvent used to prepare mixture A, and dissolved by ultrasonication to obtain mixture A.

[0014] In the above method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent: the chain transfer agent in step (2) is one or a mixture of two of mercaptoacetic acid and 3-mercaptopropionic acid in any mass ratio.

[0015] Wherein: the chain transfer agent in step (2) is preferably 3-mercaptopropionic acid.

[0016] In the above method for preparing slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent: in step (4), the pH of the solution is adjusted with 30% NaOH solution, preferably to a pH of 6.7-7.0.

[0017] The product obtained by the method of preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent as described in this invention.

[0018] This invention addresses the problem in existing slow-release polycarboxylate superplasticizers where it is difficult to introduce ester functional monomers into the superplasticizer without adding surfactants. It provides a method for preparing a polycarboxylate superplasticizer with high dispersibility, strong adaptability, effective inhibition of concrete slump loss, and slow-release effect in an ethanol-water solution. The beneficial effects of this invention are as follows:

[0019] (1) The present invention improves the preparation method of slow-release polycarboxylate superplasticizer by using ethanol aqueous solution as solvent to synthesize polycarboxylate superplasticizer, replacing the common preparation method using deionized water as solvent, thereby improving the conversion rate of ester functional monomers.

[0020] (2) The slow-release polycarboxylate superplasticizer prepared by the present invention has a good slow-release effect and improves the initial fluidity of cement paste, which can meet the requirements of use of commercial concrete that needs to be stored or transported for a long time. Attached Figure Description

[0021] Figure 1 Comparison of the dispersion effect of slow-release polycarboxylate superplasticizers prepared in different solvents on cement. Detailed Implementation

[0022] The present invention will now be described in detail with reference to specific accompanying drawings and embodiments. The examples described below are merely preferred embodiments of the present invention. It should be noted that the following description is only for explaining the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

[0023] Unless otherwise specified, all materials and reagents used in the following embodiments are commercially available.

[0024] Example 1

[0025] (1) Prepare an ethanol aqueous solution with a mass concentration of 30% as a solvent, wherein the mass of the solvent is equal to the mass of all solutes in the prepared components; in this embodiment, the mass of the ethanol aqueous solution is 27.29 g. Measure 2 / 3 of the total volume of the solvent solution to prepare mixture A, and measure 1 / 3 of the total volume of the solvent solution to prepare mixture B;

[0026] (2) Weigh out 24g of ethylene glycol monovinyl polyoxyethylene ether with a number average molecular weight Mn of 3000g / mol, 1.73g of acrylic acid, 0.32g of hydrogen peroxide solution with a mass fraction of 30%, 0.14g of chain transfer agent 3-mercaptopropionic acid, and 0.93g of hydroxyethyl acrylate, respectively, and add them to the solvent used to prepare mixture A. Dissolve by ultrasonication to obtain mixture A.

[0027] (3) Weigh 0.17g of ascorbic acid according to the mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0028] (4) Add mixture A to mixture B to obtain mixture C. Stir and react continuously for 5 hours under constant temperature water bath at 40℃. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.7-7.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0029] Example 2

[0030] (1) Prepare an ethanol aqueous solution with a mass concentration of 30% as a solvent, wherein the mass of the solvent is equal to the mass of all solutes in the prepared components; in this embodiment, the mass of the ethanol aqueous solution is 27.5g. Measure 2 / 3 of the total volume of the solvent solution to prepare mixture A, and measure 1 / 3 of the total volume of the solvent solution to prepare mixture B;

[0031] (2) Weigh out 24g of ethylene glycol monovinyl polyoxyethylene ether with a number average molecular weight Mn of 3000g / mol, 1.73g of acrylic acid, 0.32g of hydrogen peroxide solution with a mass fraction of 30%, 0.14g of chain transfer agent 3-mercaptopropionic acid, and 1.14g of tert-butyl methacrylate, respectively, and add them to the solvent used to prepare mixture A. Dissolve by ultrasonication to obtain mixture A.

[0032] (3) Weigh 0.17g of ascorbic acid according to the mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0033] (4) Add mixture A to mixture B to obtain mixture C. Stir and react continuously for 5 hours under constant temperature water bath at 40℃. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.7-7.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0034] Example 3

[0035] (1) Prepare an ethanol aqueous solution with a mass concentration of 30% as a solvent, wherein the mass of the solvent is equal to the mass of all solutes in the prepared components; in this example, the mass of the ethanol aqueous solution is 27.63g. Measure 2 / 3 of the total volume of the solvent solution to prepare mixture A, and measure 1 / 3 of the total volume of the solvent solution to prepare mixture B;

[0036] (2) Weigh out 24g of ethylene glycol monovinyl polyoxyethylene ether with a number average molecular weight Mn of 3000g / mol, 1.73g of acrylic acid, 0.32g of hydrogen peroxide solution with a mass fraction of 30%, 0.14g of chain transfer agent 3-mercaptopropionic acid, and 1.27g of dimethyl itaconic acid according to the mass. Add them to the solvent used to prepare mixture A, and dissolve them by ultrasonication to obtain mixture A.

[0037] (3) Weigh 0.17g of ascorbic acid according to the mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0038] (4) Add mixture A to mixture B to obtain mixture C. Stir and react continuously for 5 hours under constant temperature water bath at 40℃. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.7-7.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0039] Comparative Example 1

[0040] (1) Deionized water is used as the solvent, wherein the mass of water is equal to the mass of all solutes in the preparation components; in this embodiment, the mass of deionized water is 27.29 g. Two-thirds of the total volume of deionized water is used to prepare mixture A, and one-third of the total volume of deionized water is used to prepare mixture B;

[0041] (2) Weigh out 24g of ethylene glycol monovinyl polyoxyethylene ether with a number average molecular weight Mn of 3000g / mol, 1.73g of acrylic acid, 0.32g of hydrogen peroxide solution with a mass fraction of 30%, 0.14g of chain transfer agent 3-mercaptopropionic acid, and 0.93g of hydroxyethyl acrylate, respectively, and add them to the solvent used to prepare mixture A. Dissolve by ultrasonication to obtain mixture A.

[0042] (3) Weigh 0.17g of ascorbic acid according to the mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0043] (4) Add mixture A to mixture B to obtain mixture C. Stir and react continuously for 5 hours under constant temperature water bath at 40℃. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.7-7.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0044] Comparative Example 2

[0045] (1) Deionized water is used as the solvent, wherein the mass of water is equal to the mass of all solutes in the preparation components; in this embodiment, the mass of deionized water is 27.5g. Two-thirds of the total volume of deionized water is used to prepare mixture A, and one-third of the total volume of deionized water is used to prepare mixture B;

[0046] (2) Weigh out 24g of ethylene glycol monovinyl polyoxyethylene ether with a number average molecular weight Mn of 3000g / mol, 1.73g of acrylic acid, 0.32g of hydrogen peroxide solution with a mass fraction of 30%, 0.14g of chain transfer agent 3-mercaptopropionic acid, and 1.14g of tert-butyl methacrylate, respectively, and add them to the solvent used to prepare mixture A. Dissolve by ultrasonication to obtain mixture A.

[0047] (3) Weigh 0.17g of ascorbic acid according to the mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0048] (4) Add mixture A to mixture B to obtain mixture C. Stir and react continuously for 5 hours under constant temperature water bath at 40℃. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.7-7.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0049] Comparative Example 3

[0050] (1) Deionized water is used as the solvent, wherein the mass of water is equal to the mass of all solutes in the preparation components; in this embodiment, the mass of deionized water is 27.63 g. Two-thirds of the total volume of deionized water is used to prepare mixture A, and one-third of the total volume of deionized water is used to prepare mixture B;

[0051] (2) Weigh out 24g of ethylene glycol monovinyl polyoxyethylene ether with a number average molecular weight Mn of 3000g / mol, 1.73g of acrylic acid, 0.32g of hydrogen peroxide solution with a mass fraction of 30%, 0.14g of chain transfer agent 3-mercaptopropionic acid, and 1.27g of dimethyl itaconic acid according to the mass. Add them to the solvent used to prepare mixture A, and dissolve them by ultrasonication to obtain mixture A.

[0052] (3) Weigh 0.17g of ascorbic acid according to the mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0053] (4) Add mixture A to mixture B to obtain mixture C. Stir and react continuously for 5 hours under constant temperature water bath at 40℃. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.7-7.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0054] Test case

[0055] The slow-release polycarboxylate superplasticizers prepared in Examples 1-3 and Comparative Examples 1-3 were tested for dispersibility according to GB / T 8077-2000 "Test Method for Homogeneity of Concrete Admixtures": Shanshui Dongyue cement PO·42.5, cement dosage 300g, superplasticizer dosage (converted to solids) 0.25%, water dosage 87g. The results are shown in Table 1 and... Figure 1 As shown.

[0056] Table 1. Test results of cement paste fluidity (unit: mm)

[0057]

[0058]

[0059] Figure 1 A comparison of the dispersion effects of slow-release polycarboxylate superplasticizers prepared in different solvents on cement.

[0060] From Table 1 and Figure 1 The results show that when polycarboxylate superplasticizers are modified using hydroxyethyl acrylate, tert-butyl methacrylate, and dimethyl itaconic acid as functional groups, the solvent has a significant impact on the product properties.

[0061] Using ethanol-water solution as a solvent can effectively improve the solubility and conversion rate of ester monomers. Compared with using deionized water as a solvent alone, the slow-release polycarboxylate superplasticizer prepared with ethanol-water solution as a solvent has stronger dispersibility and dispersion retention ability in cement paste. Simultaneously, introducing ester functional monomers into the polycarboxylate superplasticizer allows the ester groups to gradually hydrolyze in an alkaline environment to generate carboxyl groups, thus maintaining a constant carboxyl content in the cement paste or slowing down its rate of decrease, thereby achieving long-term maintenance of the fluidity of the cement paste.

[0062] Extended Example 1: Method for preparing slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent (parts by mass, unit: grams)

[0063] (1) Prepare an ethanol aqueous solution with a mass concentration of 20% as a solvent, wherein the mass of the solvent is equal to the mass of all solutes in the prepared components; measure 2 / 3 of the total volume of the solvent solution to prepare mixture A, and measure 1 / 3 of the total volume of the solvent solution to prepare mixture B.

[0064] (2) Weigh out 160 parts of ethylene glycol monovinyl polyoxyethylene ether, 10 parts of acrylic acid, 1 part of 30% hydrogen peroxide solution, 0.5 parts of mercaptoacetic acid, and 6.6 parts of hydroxyethyl acrylate according to the mass fraction. Add them to the solvent used to prepare mixture A, and dissolve them by ultrasonication to obtain mixture A.

[0065] (3) Weigh out 1 part of ascorbic acid by mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0066] (4) Add mixture A to mixture B to obtain mixture C. Stir and react continuously for 4 hours under constant temperature water bath at 39℃. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0067] Extended Example 2: Method for preparing slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent (parts by mass, unit: grams)

[0068] (1) Prepare an ethanol aqueous solution with a mass concentration of 40% as a solvent, wherein the mass of the solvent is equal to the mass of all solutes in the prepared components; measure 2 / 3 of the total volume of the solvent solution to prepare mixture A, and measure 1 / 3 of the total volume of the solvent solution to prepare mixture B.

[0069] (2) Weigh out 180 parts of ethylene glycol monovinyl polyoxyethylene ether, 15 parts of acrylic acid, 3 parts of hydrogen peroxide solution with a mass fraction of 30%, 1.5 parts of 3-mercaptopropionic acid, and 9.1 parts of dimethyl itaconic acid according to the mass fraction. Add them to the solvent used to prepare mixture A, and dissolve them by ultrasonication to obtain mixture A.

[0070] (3) Weigh out 1 part of ascorbic acid by mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0071] (4) Add mixture A to mixture B to obtain mixture C. Stir and react continuously for 6 hours under constant temperature water bath at 41℃. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 7.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0072] Extended Example 3: Method for preparing slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent (parts by mass, unit: grams)

[0073] (1) Prepare an ethanol aqueous solution with a mass concentration of 30% as a solvent, wherein the mass of the solvent is equal to the mass of all solutes in the prepared components; measure 2 / 3 of the total volume of the solvent solution to prepare mixture A, and measure 1 / 3 of the total volume of the solvent solution to prepare mixture B.

[0074] (2) Weigh out 171.4 parts of ethylene glycol monovinyl polyoxyethylene ether with a number average molecular weight Mn of 3000 g / mol, 12.3 parts of acrylic acid, 2 parts of hydrogen peroxide solution with a mass fraction of 30%, 1 part of 3-mercaptopropionic acid, and 8.1 parts of tert-butyl methacrylate according to the mass fraction. Add them to the solvent used to prepare mixture A, and dissolve them by ultrasonication to obtain mixture A.

[0075] (3) Weigh out 1 part of ascorbic acid by mass and add it to the solvent used to prepare mixture B to obtain mixture B;

[0076] (4) Add mixture A to mixture B to obtain mixture C. Stir and react for 5 hours under constant temperature water bath at 40℃. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.8 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

[0077] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent, comprising the following steps: (1) Prepare an aqueous ethanol solution with a mass concentration of 20% - 40% as a solvent, wherein the mass of the solvent is equal to the mass of all solutes in the prepared components; measure 2 / 3 of the total volume of the solvent solution to prepare mixture A, and measure 1 / 3 of the total volume of the solvent solution to prepare mixture B. (2) Weigh out 160-180 parts by weight of ethylene glycol monovinyl polyoxyethylene ether, 10-15 parts by weight of acrylic acid, 1-3 parts by weight of 30% hydrogen peroxide solution, 0.5-1.5 parts by weight of chain transfer agent, and 6.6-9.1 parts by weight of ester functional monomers, and add them to the solvent used to prepare mixture A. Dissolve the mixture by ultrasonication to obtain mixture A; wherein, The ester functional monomers are hydroxyethyl acrylate, tert-butyl methacrylate, or dimethyl itaconic acid; (3) Weigh out 1 part of ascorbic acid by mass and add it to the solvent used to prepare mixture B to obtain mixture B; (4) Add mixture A to mixture B to obtain mixture C. Under constant temperature water bath conditions of 40±1℃, stir continuously for 5±1 h. After the reaction is completed, cool to room temperature and adjust the pH of the solution to 6.0-7.0 with 30% NaOH solution to obtain the slow-release polycarboxylate superplasticizer.

2. The method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent according to claim 1, characterized in that: The number-average molecular weight (Mn) of the ethylene glycol monovinyl polyoxyethylene ether is 3000 g / mol.

3. The method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent according to claim 1, characterized in that: The mass concentration of the ethanol aqueous solution in step (1) is 30%.

4. The method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent according to claim 1 or 2, characterized in that: In step (2), according to the mass fractions, 171.4 parts of ethylene glycol monovinyl polyoxyethylene ether, 12.3 parts of acrylic acid, 1.5-2 parts of 30% hydrogen peroxide solution, 1 part of chain transfer agent, and 6.6 parts of hydroxyethyl acrylate, 8.1 parts of tert-butyl methacrylate, or 9.1 parts of dimethyl itaconic acid are added to the solvent used to prepare mixture A and dissolved by ultrasonication to obtain mixture A.

5. The method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent according to claim 1 or 4, characterized in that: The chain transfer agent in step (2) is one or a mixture of two of mercaptoacetic acid and 3-mercaptopropionic acid in any mass ratio.

6. The method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent according to claim 5, characterized in that: The chain transfer agent in step (2) is 3-mercaptopropionic acid.

7. The method for preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent according to claim 1, characterized in that: In step (4), the pH of the solution is adjusted to 6.7-7.0 using a 30% NaOH solution.

8. The product obtained by the method of preparing a slow-release polycarboxylate superplasticizer using an alcohol-water mixture as a solvent as described in claim 1.

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