阅读说明：本技术 一种缓释型功能单体以及高保坍型聚羧酸减水剂的制备方法及工艺 (Preparation method and process of slow-release functional monomer and high slump loss resistant polycarboxylic acid water reducer ) 是由 敖凡 陈杰 邓妮 方世昌 田应兵 于 2020-12-03 设计创作，主要内容包括：本发明公开了一种缓释型功能单体以及高保坍型聚羧酸减水剂的制备方法,包括下列原料和工具：80-100份D-酒石酸、40-200份甲基丙烯醇、阻聚剂、溶剂、催化剂、乙酸乙酯、250ml三颈瓶、反应釜、引发剂、还原剂和链转移剂,工艺成熟,由于其具有疏水亲水基团,使得其显示出引气可控的效果,而且合成的功能单体中含有多个酯基,在拥有分散效果的基础上能够增长减水剂的保坍时间,缓慢释放,使得所合成聚羧酸减水剂拥有更好的综合性能,将聚醚大单体、缓释型功能单体、不饱和酸酐在引发剂、链转移剂作用下进行自由基聚合,将单体接枝到聚醚大单体中,具有较强的亲水性,对于保坍有提升作用,具有良好的分散性、坍落度保持性能以及很好的和易性。(The invention discloses a preparation method of a slow-release functional monomer and a high slump loss resistant polycarboxylic acid water reducer, which comprises the following raw materials and tools: 80-100 parts of D-tartaric acid, 40-200 parts of methyl allyl alcohol, a polymerization inhibitor, a solvent, a catalyst, ethyl acetate, a 250ml three-necked bottle, a reaction kettle, an initiator, a reducing agent and a chain transfer agent, the process is mature, because the functional monomer has hydrophobic and hydrophilic groups, the functional monomer shows the effect of controllable air entraining, and the synthesized functional monomer contains a plurality of ester groups, the slump retaining time of the water reducing agent can be prolonged on the basis of having a dispersing effect, the water reducing agent is slowly released, so that the synthesized polycarboxylic acid water reducing agent has better comprehensive performance, the polyether macromonomer, the slow release type functional monomer and the unsaturated anhydride are subjected to free radical polymerization under the action of an initiator and a chain transfer agent, the monomer is grafted to the polyether macromonomer, and the polycarboxylic acid water reducing agent has stronger hydrophilicity, has the function of improving slump retention, and has good dispersibility, slump retention performance and workability.)

1. A preparation method of a slow-release functional monomer and a high slump loss resistant polycarboxylic acid water reducer is characterized by comprising the following steps: comprises the following raw materials and tools: 80-100 parts of D-tartaric acid, 40-200 parts of methyl allyl alcohol, a polymerization inhibitor, a solvent, a catalyst, ethyl acetate, a 250ml three-necked bottle, a reaction kettle, an initiator, a reducing agent and a chain transfer agent.

2. The method for preparing the monomer containing the slow-release function according to claim 1, wherein the method comprises the following steps: the method comprises the following steps:

s1, adding a certain amount of D-tartaric acid, methyl allyl alcohol, a polymerization inhibitor and a solvent into a three-necked bottle, and heating in a constant-temperature water bath;

s2, stirring in a three-necked flask until the mixture is completely dissolved, adding a catalyst, controlling the reaction temperature between 60 and 120 ℃, and reacting for 4 to 8 hours;

and S3, extracting by using ethyl acetate, and distilling under reduced pressure to obtain the target product of the methyl allyl alcohol-tartaric acid ester.

3. The method for preparing the monomer containing the slow-release function according to claim 2, wherein the method comprises the following steps: the solvent is one or the combination of more than two of methyl allyl alcohol, DMF, ethyl acetate and methanol.

4. The method for preparing the monomer containing the slow-release function according to claim 2, wherein the method comprises the following steps: the selected catalyst is one or the combination of more than two of p-toluenesulfonic acid, sulfuric acid, boric acid and hydrochloric acid.

5. The method for preparing the monomer containing the slow-release function according to claim 2, wherein the method comprises the following steps: the polymerization inhibitor is one or the combination of more than two of hydroquinone, p-hydroxyanisole and BHT.

6. The preparation method of the slow-release type high slump retaining polycarboxylic acid water reducing agent according to claim 1, characterized by comprising the following steps: the method comprises the following steps:

s1, dissolving the polyether macromonomer in a certain amount of water according to a certain proportion, placing the mixture in a reaction kettle, heating the mixture to 30-70 ℃, and adding a certain proportion of initiator after the polyether macromonomer is fully dissolved;

s2, preparing a dropwise adding liquid A by using an unsaturated carboxylic acid small monomer and the functional monomer in the step one and water according to a certain proportion for later use, and preparing a dropwise adding liquid B by using a reducing agent and a chain transfer agent according to a certain proportion for later use;

s3, simultaneously dripping the solution A and the solution B into the kettle bottom solution in the S1, finishing dripping within 120-180 min, preserving heat for reacting for 1-2h after finishing dripping, and finishing the reaction to obtain the slow-release type high slump loss resistant polycarboxylic acid water reducing agent;

wherein, the oxidant solution is one or two of ammonium persulfate, potassium persulfate and hydrogen peroxide; the concentration of the kettle bottom is between 40 and 58 percent; the concentration of the solution A is controlled to be 70-85 percent, and the concentration of the solution B is controlled to be 20-60 percent.

7. The preparation method of the slow-release type high slump retaining polycarboxylic acid water reducing agent according to claim 6, characterized by comprising the following steps: the polyether macromonomer is TPEG, HPEG or SPEG having a molecular weight of 2400.

8. The preparation method of the slow-release type high slump retaining polycarboxylic acid water reducing agent according to claim 6, characterized by comprising the following steps: the unsaturated carboxylic acid small monomer is one or the combination of more than two of maleic anhydride, acrylic acid, methacrylic acid, itaconic acid or fumaric acid.

9. The preparation method of the slow-release type high slump retaining polycarboxylic acid water reducing agent according to claim 6, characterized by comprising the following steps: the chain transfer agent is one or the combination of more than two of sodium hypophosphite, thioglycolic acid, mercaptopropionic acid, mercaptopropanol, mercaptoethanol, 2-mercaptoethanesulfonic acid, isopropanol and sodium methallyl sulfonate.

10. The preparation method of the slow-release type high slump retaining polycarboxylic acid water reducing agent according to claim 6, characterized by comprising the following steps: the reducing agent solution is one or more of sodium formaldehyde sulfoxylate, E51 or vitamin C.

Technical Field

The invention relates to the field of concrete admixtures, in particular to a preparation method and a preparation process of a slow-release functional monomer and a high slump loss resistant polycarboxylic acid water reducer.

Background

The polycarboxylate superplasticizer has the advantages of high water reducing rate, long slump retaining time, strong molecular adjustability, easy functionalization and the like, can effectively improve the strength and durability of concrete, and becomes an indispensable component of modern concrete.

In recent years, the development of concrete admixtures towards the directions of environmental protection, high water reduction, high slump loss resistance and better adaptability to concrete timbers is promoted by the proposal of high-strength self-compacting environment-friendly concrete, but for some areas, when the mud content is large, the dispersing capacity of a polycarboxylic acid water reducing agent is seriously reduced, the slump loss resistance effect is poor, the later strength is low and the like, and the quality and the progress of engineering are influenced, so that the invention discloses a monomer with a slow release function, which can improve the initial dispersibility and increase the slump loss resistance, greatly helps to improve the water reduction performance of polycarboxylic acid, and plays a certain role in promoting the development of the building industry, and therefore, the invention provides a preparation method and a process of the slow release functional monomer and the polycarboxylic acid water reducing agent with high slump loss resistance.

Disclosure of Invention

The invention aims to solve the defects in the prior art, and provides a preparation method and a preparation process of a slow-release functional monomer and a high slump-retaining polycarboxylic acid water reducing agent. The preparation method of the functional monomer adopts methyl allyl alcohol, D-tartaric acid, a catalyst, a polymerization inhibitor and a water-carrying agent to carry out esterification reaction to obtain a product. The invention also provides a preparation method of the polycarboxylic acid water reducing agent, which comprises the steps of carrying out free radical polymerization on the polyether macromonomer, the slow-release functional monomer and the unsaturated anhydride under the action of an initiator and a chain transfer agent, grafting the functional monomer into the polyether macromonomer, wherein the functional monomer has stronger hydrophilicity due to the polyhydroxy and ester group, and the ester group hydrolysis has a promoting effect on slump loss resistance.

In order to achieve the purpose, the invention provides the following technical scheme: a preparation method of a slow-release functional monomer and a high slump loss resistant polycarboxylic acid water reducer comprises the following raw materials and tools: 80-100 parts of D-tartaric acid, 40-200 parts of methyl allyl alcohol, a polymerization inhibitor, a solvent, a catalyst, ethyl acetate, a 250ml three-necked bottle, a reaction kettle, an initiator, a reducing agent and a chain transfer agent.

Preferably, the method comprises the following steps:

s1, adding a certain amount of D-tartaric acid, methyl allyl alcohol, a polymerization inhibitor and a solvent into a three-necked bottle, and heating in a constant-temperature water bath;

s2, stirring in a three-necked flask until the mixture is completely dissolved, adding a catalyst, controlling the reaction temperature between 60 and 120 ℃, and reacting for 4 to 8 hours;

and S3, extracting by using ethyl acetate, and distilling under reduced pressure to obtain the target product of the methyl allyl alcohol-tartaric acid ester.

Preferably, the selected solvent is one or a combination of more than two of methyl allyl alcohol, DMF, ethyl acetate and methanol.

Preferably, the selected catalyst is one or the combination of more than two of p-toluenesulfonic acid, sulfuric acid, boric acid and hydrochloric acid.

Preferably, the selected polymerization inhibitor is one or the combination of more than two of hydroquinone, p-hydroxyanisole and BHT.

Preferably, the preparation method of the slow-release type high slump loss resistant polycarboxylic acid water reducing agent comprises the following steps:

s1, dissolving the polyether macromonomer in a certain amount of water according to a certain proportion, placing the mixture in a reaction kettle, heating the mixture to 30-70 ℃, and adding a certain proportion of initiator after the polyether macromonomer is fully dissolved;

s2, preparing a dropwise adding liquid A by using an unsaturated carboxylic acid small monomer and the functional monomer in the step one and water according to a certain proportion for later use, and preparing a dropwise adding liquid B by using a reducing agent and a chain transfer agent according to a certain proportion for later use;

s3, simultaneously dripping the solution A and the solution B into the kettle bottom solution in the S1, finishing dripping within 180 min of 120-fold sand, preserving heat for reacting for 1-2h after finishing dripping, and finishing the reaction to obtain the slow-release type high slump loss resistant polycarboxylic acid water reducing agent.

Preferably, the polyether macromonomer is TPEG, HPEG or SPEG having a molecular weight of 2400.

Preferably, the unsaturated carboxylic small monomer is one or a combination of more than two of maleic anhydride, acrylic acid, methacrylic acid, itaconic acid and fumaric acid.

Preferably, the chain transfer agent is one or a combination of more than two of sodium hypophosphite, thioglycolic acid, mercaptopropionic acid, mercaptopropanol, mercaptoethanol, 2-mercaptoethanesulfonic acid, isopropanol and sodium methallyl sulfonate.

Preferably, the reducing agent solution is one or a combination of more than two of sodium formaldehyde sulfoxylate, E51 or vitamin C.

Preferably, the oxidant solution is one or two of ammonium persulfate, potassium persulfate and hydrogen peroxide.

Preferably, the concentration of the bottom of the kettle is between 40% and 58%.

Preferably, the concentration of the solution A is controlled to be 70-85%, and the concentration of the solution B is controlled to be between 20-60%.

The invention has the technical effects and advantages that:

1. the synthesized polyhydroxy polyester functional monomer, namely methyl allyl alcohol-tartaric acid ester, has the advantages that one end of hydroxyl and methyl contained in methyl allyl alcohol synthesized by the functional monomer is hydrophobic, and the other end is hydrophilic, so that the surface tension of the polycarboxylate superplasticizer can be greatly reduced, and the polycarboxylate superplasticizer has the effect of controllable air entraining by controlling the proportion of the functional monomer and unsaturated carboxylic acid. The polycarboxylate superplasticizer prepared by polymerizing the monomer, the polyether monomer and the unsaturated carboxylic acid monomer has good initial dispersibility and slump retaining function.

2. The invention can control the dropping process of the functional monomer to ensure that the functional monomer has different slow release effects. When the functional monomer is placed at the bottom of the kettle, the early-stage adsorption performance is better, and the slump retaining is stably and continuously carried out; the functional monomer is placed in the solution A, and when the functional monomer is slowly dripped at a constant speed, the influence on the initial dispersibility is small, and the later slump retention performance is excellent; the mixture ratio of the whole kettle bottom and the dropping liquid can be adjusted, so that the kettle has different dispersion performances and slump retaining effects.

3. The synthesis process of the functional monomer is simple and convenient to operate, the conditions are mild, the optimal synthesis conditions are that the methyl allyl alcohol in the reaction raw materials replaces the organic solvent in the traditional esterification reaction, the purity of the esterification product is improved, the reaction time is short, the product is easy to refine, and the large-scale production is facilitated.

4. The slow-release polycarboxylate superplasticizer prepared by using the monomer has better workability than a common water reducer and has a certain viscosity reduction effect.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. 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.

Example 1

(1) Preparation of slow-release functional monomer

Adding 100 parts of D-tartaric acid and 200 parts of methyl allyl alcohol (100 parts of which are used as a reaction solvent) into a 250mL three-necked bottle provided with a condenser, a thermometer and a stirrer, heating the mixture in a constant-temperature water bath at 80 ℃, stirring the mixture until the mixture is completely dissolved, adding 0.5% of p-toluenesulfonic acid which is used as a catalyst, controlling the reaction temperature to be between 80 and 90 ℃, reacting the mixture for 7 hours, carrying out reduced pressure distillation after the reaction is finished, adding 80 parts of water to dissolve the hydroquinone and the p-toluenesulfonic acid in water, extracting the mixture for three times by using ethyl acetate, and carrying out reduced pressure distillation again to remove the ethyl acetate, thus obtaining the methyl allyl alcohol-tartaric acid ester.

(2) Preparation of slow-release high slump retaining type polycarboxylate superplasticizer

1. 80 parts of TPEG polyether macromonomer with molecular weight of 2400 is dissolved in 100 parts of tap water and put into a reaction kettle, then a slow release type functional monomer with the mass of 3% of the macromonomer is added into the reaction kettle, the temperature is raised to 70 ℃, and after the macromonomer is fully dissolved, hydrogen peroxide with the mass of 1.5% of the macromonomer and the concentration of 20% -30% is added.

2. Respectively taking acrylic acid accounting for 8 percent of the mass of the macromonomer and a slow-release functional monomer accounting for 5 percent of the mass of the macromonomer to be dissolved in water to prepare a solution with the concentration of 30 percent as a dropwise adding solution A for standby. And taking sodium bisulfite accounting for about 0.7 percent of the total mass of the macromonomer as a reducing agent and 0.6 percent of mercaptopropionic acid which is dissolved in water to prepare a solution with the concentration of 30 percent as dropwise adding solution B for later use.

3. And (3) after the temperature reaches, uniformly dripping the prepared dripping liquid A and the prepared dripping liquid B into the reaction kettle in the step (1), wherein the dripping time is 2 hours, preserving the temperature for 1 hour after the reaction is finished, dripping alkali liquor to adjust the pH value to be neutral after the heat preservation is finished, supplementing water to 40% of solid content, and obtaining a solution, namely the slow-release high slump-retaining polycarboxylic acid water reducer.

Example 2

(1) Preparation of slow-release functional monomer

Adding 90 parts of D-tartaric acid, 70 parts of methyl allyl alcohol and 0.5% of p-hydroxyanisole serving as a polymerization inhibitor into a 250mL three-necked bottle provided with a condenser, a thermometer and a stirrer, heating in a 100 ℃ constant-temperature water bath, stirring until the p-hydroxyanisole is completely dissolved, adding 0.3% of sulfuric acid serving as a catalyst, controlling the reaction temperature to be 60-70 ℃, reacting for 8 hours, carrying out reduced pressure distillation after the reaction is finished, removing the catalyst and the polymerization inhibitor, extracting with ethyl acetate for three times to remove the solvent sulfuric acid, and carrying out reduced pressure distillation again to remove the ethyl acetate, thus obtaining the methyl allyl alcohol-tartaric acid ester.

(2) Preparation of slow-release high slump retaining type polycarboxylate superplasticizer

1. 80 parts of TPEG polyether macromonomer with molecular weight of 1200 is dissolved in 100 parts of tap water and put into a reaction kettle, the temperature is raised to 40 ℃, and ammonium persulfate accounting for 1.2 percent of the mass of the macromonomer is added after the TPEG polyether macromonomer is fully dissolved.

2. Respectively taking maleic anhydride accounting for 6 percent of the mass of the macromonomer and 6 percent of the slow-release functional monomer to be dissolved in water to prepare a solution with the concentration of 30 percent as a dropwise adding solution A for standby. Then ascorbic acid accounting for about 0.5 percent of the total mass of the macromonomer is taken as a reducing agent and 0.58 percent thioglycolic acid is dissolved in water to prepare a solution with the concentration of 25 percent as dropwise adding liquid B for standby.

3. And (3) after the temperature reaches, uniformly dropping the prepared dropping liquid A and the prepared dropping liquid B into the bottom of the reaction kettle in the step (1), wherein the total dropping time is 2 hours, preserving the temperature for 2 hours after the reaction is finished, dropping alkali liquor to adjust the pH value to be neutral after the heat preservation is finished, and supplementing water to 40% of solid content to obtain a solution, namely the slow-release high slump-retaining polycarboxylic acid water reducer.

Example 3

(1) Preparation of slow-release functional monomer

Adding 80 parts of D-tartaric acid, 40 parts of methyl allyl alcohol and 0.3% of BHT serving as a polymerization inhibitor into a 250mL three-necked bottle provided with a condenser, a thermometer and a stirrer, heating in a constant-temperature water bath at 100 ℃, stirring until the materials are completely dissolved, adding 0.3% of boric acid serving as a catalyst, controlling the reaction temperature to be between 100 ℃ and 115 ℃, reacting for 6 hours, carrying out reduced pressure distillation after the reaction is finished, removing the catalyst and the polymerization inhibitor, extracting for three times by using ethyl acetate to remove a solvent sulfuric acid, and carrying out reduced pressure distillation again to remove ethyl acetate, thus obtaining the methyl allyl alcohol-tartaric acid ester.

(2) Preparation of slow-release high slump retaining type polycarboxylate superplasticizer

1. 80 parts of SPEG polyether macromonomer with the molecular weight of 2400 is dissolved in 100 parts of tap water and put into a reaction kettle, the temperature is raised to 20 ℃, after the SPEG polyether macromonomer is fully dissolved, hydrogen peroxide with the mass of the macromonomer being 1.8 percent and the concentration being between 20 and 30 percent and sodium methallyl sulfonate accounting for about 0.8 percent of the mass of the macromonomer are added.

2. Respectively dissolving acrylic acid accounting for 4 percent of the mass of the macromonomer, maleic anhydride accounting for 2 percent of the mass of the macromonomer and the slow-release functional monomer accounting for 8 percent of the mass of the macromonomer in water to prepare a solution with the concentration of 30 percent as a dropwise adding solution A for later use. And dissolving a reducing agent E51 accounting for about 0.5 percent of the total mass of the macromonomer in water to prepare a solution with the concentration of 25 percent as dropwise-adding liquid B for later use.

3. And (3) after the temperature reaches, dropping the prepared dropping liquid A and the prepared dropping liquid B into the reaction kettle in the step (1) at a constant speed, wherein the dropping time is 3 hours for the liquid A, 3.5 hours for the liquid B, keeping the temperature for 1 hour after the reaction is finished, dropping alkali liquor to adjust the pH value to be neutral after the heat preservation is finished, and supplementing water to 40% of solid content to obtain the solution, namely the slow-release high slump-retaining polycarboxylic acid water reducer.

In summary, the following steps: comparing the concrete performance test of the sample synthesized in the embodiment 1-3 with the concrete performance test of a commercially available common polycarboxylic acid water reducing agent by adopting 42.5 cement of conch; class II fly ash; sand: the machine-made sand has the fineness modulus of 2.60; crushing stone: the grain diameter is 5-30 mm, and the test mixture ratio of C60 concrete is as follows: carrying out fruit cultivation under the conditions of 260Kg/m cement, 90Kg/m coal ash, 928Kg/m sand, 100Kg/m mineral powder, 877Kg/m crushed stone and 162Kg/m water during fruit cultivation under the conditions of uniformly testing concrete admixture and loss of concrete under the same conditions:

1. commercial water reducing agent: the water reducing agent content is 0.2%, the slump/slump (in cm) is 220/660 in the initial state, 200/500 in the 1H state, 160/450 in the 2H state and 140/400 in the 3H state, the concrete has more bubbles and poor cohesiveness.

2. Example 1: the water reducing agent content was 0.18%, the slump/slump (in cm) was 220/580 in the initial state, 220/560 in the 1H state, 200/520 in the 2H state, 180/495 in the 3H state, and the concrete was good with few bubbles.

3. Example 2: the mixing amount of the water reducing agent is 18 percent, the slump/expansion degree (unit cm) is 220/595 in the initial state, 220/575 in the 1H state, 200/540 in the 2H state and 195/500 in the 3H state, and the workability of the concrete is good.

4. Example 3: the mixing amount of the water reducing agent is 0.18 percent, the slump/expansion degree (unit cm) is 220/570 in the initial state, 220/560 in the 1H state, 200/535 in the 2H state and 175/465 in the 3H state, the viscosity of the concrete is small, and the flow speed is high.

5. According to the test results, the slow-release high slump loss resistant polycarboxylate water reducing agents prepared in the embodiments 1, 2 and 3 have more excellent performance, the water reducing rate and the slump retention are much better than those of the commercial water reducing agents, and the water reducing agents in the embodiments have better workability, fewer air bubbles and shorter flowing time in terms of concrete state.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.