阅读说明：本技术 一种具有高降粘性能的聚羧酸减水剂的制备方法 (Preparation method of polycarboxylate superplasticizer with high viscosity reduction performance ) 是由 汪苏平 汪源 魏凯 纪宪坤 张亚利 胡志豪 于 2020-06-23 设计创作，主要内容包括：本发明公开一种具有高降粘性能的聚羧酸减水剂的制备方法,先将三氟乙醇、含双键烯酸酰氯类化合物反应生成降粘功能单体Ⅰ,然后将马来酸酐、直链二元醇类化合物反应生产降粘功能单体Ⅱ,最后制备特殊的A液、B液、C液滴加到水相体系反应制得成品。与普通PCE相比,本专利提供的聚羧酸减水剂具有良好的降粘效果,流空时间、T500明显缩短；采用乳液聚合方法,反应聚合效率高,制得的产品分子量分布更加均匀,产品分子结构及性能更稳定；可有效解决高强混凝土在拌制过程中因低水胶比带来的粘度大、扒底等现象。(The invention discloses a preparation method of a polycarboxylic acid water reducing agent with high viscosity reducing performance, which comprises the steps of firstly reacting trifluoroethanol and double-bond olefine acid acyl chloride compounds to generate a viscosity reducing functional monomer I, then reacting maleic anhydride and straight-chain dihydric alcohol compounds to generate a viscosity reducing functional monomer II, and finally preparing special liquid A, liquid B and liquid C which are dripped into a water phase system to react to obtain a finished product. Compared with the common PCE, the polycarboxylate superplasticizer provided by the patent has a good viscosity reduction effect, and the emptying time and T500 are obviously shortened; by adopting the emulsion polymerization method, the reaction polymerization efficiency is high, the molecular weight distribution of the prepared product is more uniform, and the molecular structure and the performance of the product are more stable; the problems of high viscosity, bottom scraping and the like caused by low water-cement ratio in the mixing process of the high-strength concrete can be effectively solved.)

1. A preparation method of a polycarboxylate superplasticizer with high viscosity reduction performance is characterized by comprising the following steps:

s1, uniformly mixing 1 part of trifluoroethanol and 1-3 parts of double-bond olefine acid acyl chloride compounds, heating to 40-50 ℃, adding a catalyst, carrying out constant-temperature reflux reaction for 3-6h, cooling to room temperature after the reaction is finished, extracting for 3-5 times by using an organic solvent, and removing the organic solvent to obtain a viscosity reduction functional monomer I;

s2, heating 1 part of maleic anhydride to 120-150 ℃, adding 1-7 parts of linear chain dihydric alcohol compound to react for 3-5.5 hours at constant temperature, cooling to room temperature after the reaction is finished, adding water until the solid content is 60%, and uniformly stirring to obtain a viscosity reduction functional monomer II;

s3, adding polyether monomers and maleic anhydride into water, stirring and dissolving to form a water phase system, dissolving vitamin C and mercaptopropionic acid in water to serve as solution A, dissolving acrylic acid and a viscosity reduction functional monomer II in water to serve as solution B, and dispersing an emulsifier and a viscosity reduction functional monomer I in water to serve as solution C;

adding sodium persulfate into the water phase system, slowly dripping the solution A, the solution B and the solution C into the water phase system for 3.0h, 3.5h and 4.0h, and reacting for 4h at 40-60 ℃; and finally, adjusting the pH value to 6-7, and stirring for 15min to obtain the polycarboxylic acid water reducing agent with high viscosity reducing performance.

2. The method for preparing a polycarboxylic acid water reducing agent with high viscosity reduction performance according to claim 1, wherein in step S1, the molar ratio of the trifluoroethanol to the double bond-containing alkenoic acid chloride compound is 1: 1-1.5.

3. The method for preparing a polycarboxylic acid water reducer with high viscosity reduction performance according to claim 1 or 2, wherein in step S1, the double bond-containing alkenoic acid chloride compound is at least one of acryloyl chloride, pentenoyl chloride and undecylenic chloride.

4. The preparation method of the polycarboxylate superplasticizer with high viscosity reduction performance according to claim 1 or 2, wherein in step S1, the catalyst is at least one of 4-dimethylamino pyridine, p-toluenesulfonic acid, phosphotungstic acid and silicotungstic acid, and the dosage of the catalyst is 0.1-0.2% of the total weight of trifluoroethanol and double bond-containing olefine acid chloride compounds.

5. The method for preparing a polycarboxylic acid water reducing agent with high viscosity reduction performance according to claim 1, wherein in step S2, the molar ratio of maleic anhydride to the linear diol compound is 1: 1-5.

6. The method for preparing a polycarboxylic acid water reducing agent with high viscosity reduction performance according to claim 1, wherein in step S2, the linear dihydric alcohol compound is diethylene glycol or dipropylene glycol.

7. The preparation method of the polycarboxylic acid water reducer with high viscosity reduction performance according to claim 1, wherein in step S3, the weight ratio of the polyether monomer, the viscosity reduction functional monomer I and the viscosity reduction functional monomer II is 10:1-3: 2-4.

8. The preparation method of the polycarboxylic acid water reducer with high viscosity reduction performance according to claim 6, wherein in step S3, the weight ratio of the polyether monomer, the maleic anhydride, the vitamin C, the mercaptopropionic acid, the acrylic acid and the emulsifier is 100:5-15:0.2-0.8:1-3:10.5-13: 2-5.

9. The preparation method of the polycarboxylic acid water reducer with high viscosity reduction performance according to claim 6 or 7, wherein in step S3, the polyether monomer is prenyl polyoxyethylene ether.

10. The method for preparing a polycarboxylic acid water reducing agent with high viscosity reduction performance according to claim 6 or 7, wherein in step S3, the emulsifier is at least one of sodium dibutylnaphthalenesulfonate, sodium dodecylsulfate and sodium alkylaryl sulfonate.

Technical Field

The invention belongs to the field of concrete water reducing agents, and particularly relates to a preparation method of a polycarboxylic acid water reducing agent with high viscosity reduction performance.

Background

With the rapid development of the building industry, modern buildings increasingly tend to be high-rise, light-weight and large-span, and high-strength concrete is being widely applied to infrastructure due to the characteristics of high strength, good integrity, small self weight and the like. At present, the strength of high-strength concrete is improved mainly by methods of reducing the water cement ratio, increasing the using amount of cementing materials and the like, but the viscosity of the concrete is increased, the fluidity is reduced, the pumping performance of the concrete is reduced, the construction efficiency is influenced, and the popularization and the application of the high-strength concrete are limited to a great extent.

At present, the problem is generally solved by increasing the mixing amount of the water reducing agent, using high-quality ultrafine powder and optimizing the particle size distribution. However, the viscosity of the concrete is reduced by increasing the mixing amount of the water reducing agent, so that the cost is increased, the retarding effect is excessive, the formwork removal period is obviously prolonged, the problems of bleeding, bottom scraping and the like of newly mixed concrete can occur, and certain difficulty is caused to construction. The concrete viscosity is reduced by selecting high-quality ultrafine powder and optimizing the particle grading, and although many related researches exist in the prior art, the flowability of fresh concrete mainly depends on the strong adsorption and dispersion effects of the high-efficiency water reducing agent, the particle grading is optimized, so that the actual problem cannot be fundamentally solved, and the method has certain limitations. Therefore, the research and development of the viscosity reduction type polycarboxylate superplasticizer have great significance.

In recent years, more and more scholars are dedicated to developing viscosity-reducing polycarboxylic acid water reducing agents, and related results are reported. For example, in patent CN108192010A, an ether macromonomer, an ester group modified monomer, and an unsaturated acid monomer are used as raw materials to synthesize a viscosity-reducing polycarboxylic acid water reducer, which has a certain viscosity-reducing effect, but the synthesis process is complex, the price of the related raw materials is expensive, and ethanol is selected as a solvent, which is not suitable for large-scale industrial production. In the granted patent CN105601826A, an unsaturated carboxylic acid monomer, an unsaturated phosphonic acid monomer and an ultraviolet active monomer are synthesized into a macromolecule, and then synthesized with acrylamide and the monomer to prepare the viscosity-reducing polycarboxylate superplasticizer. Patent application CN104262550A provides a method for synthesizing a viscosity-reducing polycarboxylate superplasticizer, but the overall synthetic route is long, and the problems of low yield and low product purity are easy to occur.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the preparation method of the polycarboxylic acid water reducer with high viscosity reduction performance, and the viscosity reduction functional monomer is introduced into the molecular structure, so that the molecular HLB value is reduced, the viscosity adjustment of concrete is facilitated, and the viscosity reduction performance of the product is further improved. Specifically, the following technique is used.

A preparation method of a polycarboxylate superplasticizer with high viscosity reduction performance comprises the following steps:

s1, uniformly mixing 1 part of trifluoroethanol and 1-3 parts of double-bond olefine acid acyl chloride compounds, heating to 40-50 ℃, adding a catalyst (the general dosage is 0.2 percent of the total weight of the trifluoroethanol and the double-bond olefine acid acyl chloride compounds), carrying out constant-temperature reflux reaction for 3-6h, cooling to room temperature after the reaction is finished, extracting for 3-5 times by using an organic solvent (the common organic solvent is petroleum ether), and removing the organic solvent to obtain a viscosity reduction functional monomer I;

s2, heating 1 part of maleic anhydride to 120-150 ℃, adding 1-7 parts of linear chain dihydric alcohol compound to react for 3-5.5 hours at constant temperature, cooling to room temperature after the reaction is finished, adding water until the solid content is 60%, and uniformly stirring to obtain a viscosity reduction functional monomer II;

s3, adding polyether monomers and maleic anhydride into water, stirring and dissolving to form a water phase system, dissolving vitamin C and mercaptopropionic acid in water (the water dosage is only required to completely dissolve the vitamin C and the mercaptopropionic acid and is generally about 40g (40 mL)) to form a liquid A, dissolving acrylic acid and a viscosity reduction functional monomer II in water to form a liquid B, and dispersing an emulsifier and a viscosity reduction functional monomer I in water (the water dosage is only required to completely disperse the emulsifier and the viscosity reduction functional monomer I in the water and is generally about 40g (40 mL)) to form a liquid C;

adding sodium persulfate (the dosage of the sodium persulfate is generally 0.4-1% of the weight of the polyether monomer) into the aqueous phase system, slowly dropping the solution A, the solution B and the solution C into the aqueous phase system for 3.0h, 3.5h and 4.0h, and reacting for 4h at 40-60 ℃; and finally, adjusting the pH value to 6-7, and stirring for 15min to obtain the polycarboxylic acid water reducing agent with high viscosity reducing performance.

The high-strength concrete is characterized in that the water-cement ratio is low, the volume weight is high, free water in the interior is less, so that the viscosity is high and the volume weight is large, heavy aggregate sinks to the lower part, the slurry body is on the upper part, the bleeding phenomenon occurs, the concrete on the lower part has high quality and low water content, and the bottom pulling phenomenon occurs. Therefore, the viscosity reduction type water reducing agent is often used in high strength grade concrete. The polycarboxylate superplasticizer prepared by the method has the advantages that the monomer I with the viscosity reduction function is prepared by reacting the trifluoroethanol with the compound containing double bond olefine acid acyl chloride, so that the slump and the running-in time of the final superplasticizer can be improved, the T500 time is shortened, concrete bleeding and bottom scraping are prevented, and the 28d compressive strength is enhanced. The molecular structure of the monomer I containing the trifluoroethanol and the double-bond olefine acid acyl chloride compound is provided with a special hydrophobic structure, so that the free water in the concrete is increased, the viscosity of the concrete is improved, and the effect cannot be obtained by singly using the double-bond olefine acid acyl chloride compound as the viscosity reduction functional monomer I. In step S3, the emulsifier acts as a chain transfer agent in addition to emulsification, and adjusts the molecular weight during the reaction. The water reducing performance of the finished water reducing agent is improved.

Preferably, in step S1, the molar ratio of the trifluoroethanol to the double bond-containing olefinic acid chloride compound is 1: 1-1.5.

More preferably, in step S1, the double bond-containing alkenoic acid chloride compound is at least one of acryloyl chloride, pentenoyl chloride and undecylenic chloride.

More preferably, the catalyst is at least one of 4-dimethylamino pyridine, p-toluenesulfonic acid, phosphotungstic acid and silicotungstic acid, and the dosage of the catalyst is 0.1-0.2 percent of the total weight of the trifluoroethanol and the double-bond-containing olefine acid chloride compounds. The catalytic effects with the above catalysts are not very different.

Preferably, in step S2, the weight ratio of the maleic anhydride to the linear dihydric alcohol compound is 1: 1-5.

Preferably, in step S2, the linear diol compound is diethylene glycol or dipropylene glycol.

Preferably, in step S3, the molar ratio of the polyether monomer, the viscosity-reducing functional monomer i, and the viscosity-reducing functional monomer ii is 10:1-3: 2-4.

More preferably, in step S3, the weight ratio of the polyether monomer, maleic anhydride, vitamin C, mercaptopropionic acid, acrylic acid, and emulsifier is 100:5-15:0.2-0.8:1-3:100:10.5-13:100: 2-5.

Further preferably, in step S3, the polyether monomer is prenyl polyoxyethylene ether.

Further preferably, in step S3, the emulsifier is at least one of sodium dibutylnaphthalenesulfonate, sodium dodecylsulfate, and sodium alkylaryl sulfonate. The emulsifying action and the chain transfer agent action of the emulsifier are not very different.

Compared with the prior art, the invention has the advantages that:

1. compared with the common PCE, the viscosity reduction type water reducer prepared by the invention has good viscosity reduction effect, and the emptying time and T500 are obviously shortened;

2. by adopting the emulsion polymerization method, the reaction polymerization efficiency is high, the molecular weight distribution of the prepared product is more uniform, and the molecular structure and the performance of the product are more stable;

3. the problems of high viscosity, bottom scraping and the like caused by low water-cement ratio in the mixing process of the high-strength concrete can be effectively solved.

Detailed Description

The technical solutions of the present invention will be described clearly and completely below, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the preparation methods of the polycarboxylic acid water reducing agent provided in the following examples and comparative examples, unless otherwise specified, the catalyst used in step S1 is p-toluenesulfonic acid, and the used amount is 0.2% by weight of the total amount of the trifluoroethanol and the double bond-containing olefinic acid chloride compound, and the used organic solvent is petroleum ether; the double bond-containing olefine acid chloride compound is acryloyl chloride. In step S2, the linear diol used is diethylene glycol. In step S3, the polyether monomer is prenyl polyoxyethylene ether, the sodium persulfate is 1% of the weight of the polyether monomer, and the emulsifying machine is sodium dodecyl sulfate and the amount of the sodium dodecyl sulfate is 4% of the weight of the polyether monomer.