CN112126021B

CN112126021B - Mud-resistant polycarboxylic acid water reducer and preparation method thereof

Info

Publication number: CN112126021B
Application number: CN202010854758.7A
Authority: CN
Inventors: 王博; 孙金桥; 屈建; 霍亮; 廖娟
Original assignee: China State Construction Engineering Corp Ltd CSCEC; China State Construction Engineering Industry Technology Research Institute
Current assignee: China State Construction Engineering Corp Ltd CSCEC; China State Construction Engineering Industry Technology Research Institute
Priority date: 2020-08-21
Filing date: 2020-08-21
Publication date: 2022-06-21
Anticipated expiration: 2040-08-21
Also published as: CN112126021A

Abstract

The invention discloses an anti-mud polycarboxylic acid water reducer and a preparation method thereof, belonging to the technical field of polycarboxylic acid water reducers for concrete, and the anti-mud polycarboxylic acid water reducer is prepared from the following raw materials: the multi-arm polymer comprises a multi-arm polymer precursor, methacrylic polyglycol ether, an unsaturated acid monomer, acryloyloxyethyl trimethyl ammonium chloride, a chain transfer agent and an initiator. The mud-resistant polycarboxylate-type water reducing agent disclosed by the invention has a multi-arm molecular structure containing quaternary ammonium salt functional groups, can reduce the surface adsorption effect of clay on water reducing agent molecules, and can also inhibit the expansion of the clay to reduce the distance between clay intercalation layers, so that the adsorption capacity of the clay on a polycarboxylate water reducing agent is reduced, and finally the mud-resistant effect is achieved. The water reducer has the advantages of long slump retaining time and strong mud resistance, can avoid adverse effects caused by mud-containing aggregates in concrete, is simple and reasonable in preparation method, high in efficiency and low in cost, and is suitable for industrial production. The product has stable performance, and is a green and environment-friendly water-soluble polymer.

Description

Mud-resistant polycarboxylic acid water reducer and preparation method thereof

Technical Field

The invention relates to the technical field of polycarboxylic acid water reducing agents for concrete, in particular to an anti-mud polycarboxylic acid water reducing agent and a preparation method thereof.

Background

The polycarboxylate superplasticizer (PCE) has a series of advantages of good designability of molecular structure, high water reducing rate of concrete, good slump retaining performance over time, environmental friendliness, excellent durability and the like, and gradually replaces other types of water reducers to be developed into a new generation of water reducers with wide application.

However, with the rapid development of the building industry in China, a large amount of high-quality concrete raw materials are consumed, and more concrete projects are forced to use sand stones with poor quality and high mud content. But the polycarboxylate superplasticizer has stronger sensitivity to the mud content in the sandstone, and is mainly characterized in that the mixing amount of the PCE superplasticizer is increased, so that the water reducing rate and slump retaining performance of concrete are reduced sharply, the strength is reduced and the like. Under the condition of high aggregate mud content, the problems of poor concrete fluidity, high loss and the like cannot be effectively solved by simply improving the mixing amount of the PCE, which is an important reason for always restricting the further popularization and application of the PCE in the premixed concrete industry.

Although this phenomenon can be alleviated by increasing the amount of the concrete admixture, it causes problems such as prolonged setting time of concrete, reduced compressive strength ratio, and excessive cost. With the continuous development of market demand and the continuous deepening of research and development, PCE urgently needs to develop from early water reducing type and slump retaining type to different functional applications such as slow release type, early strength type, anti-mud type, high workability type and viscosity reducing type.

Disclosure of Invention

The invention aims to provide a mud-resistant polycarboxylic acid water reducer which has strong adaptability, good mud resistance, good concrete workability, good slump retaining performance and stable quality and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme: the mud-resistant polycarboxylic acid water reducer is prepared by reacting a multi-arm polymer precursor with methacrylic polyglycol ether, an unsaturated acid monomer, acryloyloxyethyl trimethyl ammonium chloride and a chain transfer agent under the action of an initiator, wherein the multi-arm polymer precursor comprises 6-8 parts of the multi-arm polymer precursor, 23-30 parts of the methacrylic polyglycol ether, 20-25 parts of the unsaturated acid monomer, 10-15 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.5-1.2 parts of the chain transfer agent and 0.5-1.5 parts of the initiator.

Preferably, the multi-arm polymer precursor is obtained by reacting polyvinyl alcohol and acryloyl chloride, wherein the mass ratio of the polyvinyl alcohol to the acryloyl chloride is 1: 2.

preferably, the polymerization degree of the polyvinyl alcohol is 100, and the alcoholysis degree is 78-88%.

Preferably, the molecular weight of the methacrylic polyethylene glycol ether is 2000-2400.

Preferably, the unsaturated acid is any one of acrylic acid, methacrylic acid and maleic acid.

Preferably, the initiator is any one of dibenzoyl peroxide, tert-butyl peroxydicarbonate-2-ethylhexyl and tert-butyl peroxybenzoate.

Preferably, the chain transfer agent is any one of 2, 4-diphenyl-4-methyl-1-pentene, isooctyl 3-mercaptopropionate and dodecyl mercaptan.

Preferably, the anti-mud polycarboxylic acid water reducing agent is of a multi-arm molecular structure with quaternary ammonium functional groups.

In addition, the invention also provides a preparation method of the anti-mud polycarboxylic acid water reducing agent, which comprises the following steps:

dissolving a multi-arm polymer precursor in part of dimethyl sulfoxide to form a base solution;

dissolving methacrylic polyglycol ether, unsaturated acid monomers, acryloyloxyethyl trimethyl ammonium chloride and a chain transfer agent in part of dimethyl sulfoxide to form a material A;

dissolving an initiator in part of dimethyl sulfoxide to form a material B;

heating the base material to 62-68 ℃, dropwise adding A, B material at a constant speed, and keeping the temperature for 3.0h under the condition of 62-68 ℃ after dropwise adding;

and step five, after the heat preservation is finished, cooling the solution to room temperature, dialyzing to remove impurities, and then removing the solvent to obtain the anti-mud polycarboxylic acid water reducer.

Preferably, the method for preparing the multi-arm polymer precursor comprises the following steps:

s1, dissolving polyvinyl alcohol in dimethyl sulfoxide at 50 ℃ to form a polyvinyl alcohol solution with the concentration of 2-5%;

s2, dropwise adding concentrated sulfuric acid and acryloyl chloride into the polyvinyl alcohol solution, wherein the mass ratio of the polyvinyl alcohol to the acryloyl chloride is 1: 2;

and S3, performing reflux reaction at 50 ℃ for 3 hours, stopping the reaction, pouring the solution into a beaker filled with water, separating out a precipitate, performing suction filtration and washing, and drying in a vacuum drying oven to obtain the multi-arm polymer precursor.

Compared with the prior art, the invention has the characteristics and beneficial effects that:

(1) the raw materials of the mud-resistant polycarboxylic acid water reducer comprise a multi-arm polymer precursor, methacrylic polyglycol ether, an unsaturated acid monomer, acryloyloxyethyl trimethyl ammonium chloride, a chain transfer agent and an initiator, and the organic solvent system is adopted. The multi-arm polymer precursor, the methacrylic polyglycol ether, the unsaturated acid monomer, the acryloyloxyethyl trimethyl ammonium chloride and other vinyl monomers contain double bonds, the initiator initiates free radical polymerization of the multi-arm polymer precursor, the methacrylic polyglycol ether, the unsaturated acid monomer, the acryloyloxyethyl trimethyl ammonium chloride and other vinyl monomers, and the molecular weight is adjusted through the chain transfer agent.

(2) The mud-resistant polycarboxylate-type water reducing agent disclosed by the invention has a multi-arm molecular structure containing quaternary ammonium salt functional groups, can reduce the surface adsorption effect of clay on water reducing agent molecules, and can also inhibit the expansion of the clay to reduce the distance between clay intercalation layers, so that the adsorption capacity of the clay on a polycarboxylate water reducing agent is reduced, and finally the mud-resistant effect is achieved. The methacrylic polyglycol ether can make the water reducing agent molecule have stronger cement particle dispersibility maintaining ability. Therefore, the adaptability of the mud-resistant polycarboxylic acid water reducer to high mud content sand is improved.

(3) The mud-resistant polycarboxylic acid water reducer has the advantages of long slump retaining time and strong mud resistance, and can avoid adverse effects caused by mud-containing aggregates in concrete. The reaction condition of the water reducing agent is easy to control, the efficiency is high, the cost is low, and the method is suitable for industrial production. The product has stable performance, and is a green and environment-friendly water-soluble polymer.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The primary objects and other advantages of the invention may be realized and attained by the instrumentalities particularly pointed out in the specification.

Detailed Description

In order to make the technical means, innovative features, objectives and functions realized by the present invention easy to understand, the present invention is further described below.

The embodiments described herein are specific embodiments of the present invention, and are intended to be illustrative and exemplary of the concepts of the present invention and should not be construed as limiting the scope of the embodiments of the present invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification of the present application, and these technical solutions include technical solutions which make any obvious replacement or modification for the embodiments described herein.

The invention provides a mud-resistant polycarboxylic acid water reducer which is a multi-arm molecular structure with quaternary ammonium functional groups. The mud-resistant polycarboxylate-type water reducing agent is prepared by reacting a multi-arm polymer precursor with methacrylic polyethylene glycol ether (TPEG), an unsaturated acid monomer, acryloyloxyethyl trimethyl ammonium chloride and a chain transfer agent under the action of an initiator, wherein 6-8 parts of the multi-arm polymer precursor, 23-30 parts of methacrylic polyethylene glycol ether, 20-25 parts of the unsaturated acid monomer, 10-15 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.5-1.2 parts of the chain transfer agent and 0.5-1.5 parts of the initiator are used.

The molecular weight of the methacrylic polyglycol ether is 2000-2400. The unsaturated acid is any one of acrylic acid, methacrylic acid and maleic acid. The initiator is any one of dibenzoyl peroxide, tert-butyl peroxydicarbonate-2-ethylhexyl carbonate and tert-butyl peroxybenzoate. The chain transfer agent is any one of 2, 4-diphenyl-4-methyl-1-pentene, 3-isooctyl mercaptopropionate and dodecyl mercaptan.

The multi-arm polymer precursor is obtained by reacting polyvinyl alcohol and acryloyl chloride, wherein the mass ratio of the polyvinyl alcohol (PVA) to the acryloyl chloride is 1: 2. the polymerization degree of the polyvinyl alcohol is 100, and the alcoholysis degree of the polyvinyl alcohol is 78-88%.

The preparation method of the mud-resistant polycarboxylic acid water reducer comprises the following steps:

dissolving an initiator in part of dimethyl sulfoxide to form a material B;

The preparation method of the multi-arm polymer precursor comprises the following steps:

Example 1

Dissolving polyvinyl alcohol in dimethyl sulfoxide at 50 ℃ to form a PVA solution with the concentration of 2%, adding acryloyl chloride which is 2 times of the mass of the polyvinyl alcohol and a proper amount of concentrated sulfuric acid into the PVA solution, carrying out reflux reaction at 50 ℃ for 3 hours, and stopping the reaction. Pouring the solution into a beaker filled with water, separating out precipitate, carrying out suction filtration, washing, and putting into a vacuum drying oven for drying to obtain the multi-arm polymer precursor. 6.5 parts of multi-arm polymer precursor is dissolved in part of dimethyl sulfoxide to form a base solution, 28 parts of methacrylic polyglycol ether, 22 parts of acrylic acid, 13 parts of acryloyloxyethyl trimethyl ammonium chloride and 1.2 parts of 2, 4-diphenyl-4-methyl-1-pentene are dissolved in part of dimethyl sulfoxide to form a material A, 0.9 part of dibenzoyl peroxide is dissolved in part of dimethyl sulfoxide to form a material B, the base material is heated to 65 +/-3 degrees, A, B materials are dropwise added at a constant speed, and the temperature is kept for 3.0 hours under the condition of 65 +/-3 degrees after the dropwise addition is completed. And after the heat preservation is finished, cooling the solution to room temperature, dialyzing to remove impurities, and then removing the solvent to obtain the anti-mud polycarboxylic acid water reducer.

Example 2

Dissolving polyvinyl alcohol in dimethyl sulfoxide at 50 ℃ to form a PVA solution with the concentration of 3%, adding acryloyl chloride which is 2 times of the mass of the polyvinyl alcohol and a proper amount of concentrated sulfuric acid into the PVA solution, carrying out reflux reaction at 50 ℃ for 3 hours, and stopping the reaction. Pouring the solution into a beaker filled with water, separating out precipitate, carrying out suction filtration, washing, and putting into a vacuum drying oven for drying to obtain the multi-arm polymer precursor. Dissolving 8 parts of multi-arm polymer precursor in part of dimethyl sulfoxide to form a base solution, dissolving 30 parts of methacrylic polyethylene glycol ether, 20 parts of methacrylic acid, 10 parts of acryloyloxyethyl trimethyl ammonium chloride and 0.8 part of isooctyl 3-mercaptopropionate in part of dimethyl sulfoxide to form a material A, dissolving 1.5 parts of dibenzoyl peroxide in part of dimethyl sulfoxide to form a material B, heating the base material to 65 +/-3 degrees, starting to dropwise add A, B materials at a constant speed, and preserving heat for 3.0 hours under the condition of 65 +/-3 degrees after dropwise addition is completed. And after the heat preservation is finished, cooling the solution to room temperature, dialyzing to remove impurities, and then removing the solvent to obtain the anti-mud polycarboxylic acid water reducer.

Example 3

Dissolving polyvinyl alcohol in dimethyl sulfoxide at 50 ℃ to form a PVA solution with the concentration of 4%, adding acryloyl chloride which is 2 times of the mass of the polyvinyl alcohol and a proper amount of concentrated sulfuric acid into the PVA solution, carrying out reflux reaction at 50 ℃ for 3 hours, and stopping the reaction. Pouring the solution into a beaker filled with water, separating out precipitate, carrying out suction filtration, washing, and putting into a vacuum drying oven for drying to obtain the multi-arm polymer precursor. Dissolving 7 parts of multi-arm polymer precursor in part of dimethyl sulfoxide to form a base solution, dissolving 24 parts of methacrylic polyethylene glycol ether, 25 parts of maleic acid, 12 parts of acryloyloxyethyl trimethyl ammonium chloride and 0.5 part of 2, 4-diphenyl-4-methyl-1-pentene in part of dimethyl sulfoxide to form a material A, dissolving 0.5 part of tert-butyl peroxycarbonate-2-ethylhexyl ester in part of dimethyl sulfoxide to form a material B, heating the base material to 65 +/-3 ℃, starting dropwise adding A, B materials at a constant speed, and after dropwise adding is completed, keeping the temperature for 3.0 hours under the condition of 65 +/-3 ℃. And after the heat preservation is finished, cooling the solution to room temperature, dialyzing to remove impurities, and then removing the solvent to obtain the anti-mud polycarboxylic acid water reducer.

Example 4

Dissolving polyvinyl alcohol in dimethyl sulfoxide at 50 ℃ to form a PVA solution with the concentration of 5%, adding acryloyl chloride which is 2 times of the mass of the polyvinyl alcohol and a proper amount of concentrated sulfuric acid into the PVA solution, performing reflux reaction at 50 ℃ for 3 hours, and stopping the reaction. Pouring the solution into a beaker filled with water, separating out precipitate, carrying out suction filtration, washing, and putting into a vacuum drying oven for drying to obtain the multi-arm polymer precursor. Dissolving 7.5 parts of multi-arm polymer precursor in part of dimethyl sulfoxide to form a base solution, dissolving 26 parts of methacrylic polyglycol ether, 24 parts of acrylic acid, 14 parts of acryloyloxyethyl trimethyl ammonium chloride and 1 part of isooctyl 3-mercaptopropionate in part of dimethyl sulfoxide to form a material A, dissolving 1.2 parts of tert-butyl peroxybenzoate in part of dimethyl sulfoxide to form a material B, heating the base material to 65 +/-3 degrees, starting dropwise adding A, B materials at a constant speed, and preserving heat for 3.0 hours under the condition of 65 +/-3 degrees after dropwise adding. And after the heat preservation is finished, cooling the solution to room temperature, dialyzing to remove impurities, and then removing the solvent to obtain the anti-mud polycarboxylic acid water reducer.

Example 5

Dissolving polyvinyl alcohol in dimethyl sulfoxide at 50 ℃ to form a PVA solution with the concentration of 4%, adding acryloyl chloride which is 2 times of the mass of the polyvinyl alcohol and a proper amount of concentrated sulfuric acid into the PVA solution, performing reflux reaction at 50 ℃ for 3 hours, and stopping the reaction. Pouring the solution into a beaker filled with water, separating out precipitate, carrying out suction filtration, washing, and putting into a vacuum drying oven for drying to obtain the multi-arm polymer precursor. Dissolving 6 parts of multi-arm polymer precursor in part of dimethyl sulfoxide to form a base solution, dissolving 23 parts of methacrylic polyethylene glycol ether, 23 parts of acrylic acid, 15 parts of acryloyloxyethyl trimethyl ammonium chloride and 0.9 part of dodecyl mercaptan in part of dimethyl sulfoxide to form a material A, dissolving 0.7 part of dibenzoyl peroxide in part of dimethyl sulfoxide to form a material B, heating the base material to 65 +/-3 ℃, starting dropwise adding A, B materials at a constant speed, and keeping the temperature for 3.0 hours under the condition of 65 +/-3 ℃ after dropwise adding is completed. And after the heat preservation is finished, cooling the solution to room temperature, dialyzing to remove impurities, and then removing the solvent to obtain the anti-mud polycarboxylic acid water reducer.

Comparative example 1

In this comparative example, the multi-arm polymer precursor component was omitted from the raw material weighing step as compared to example 1, except that the process steps were otherwise identical.

Comparative example 2

In this comparative example, as compared with example 1, in the raw material weighing step, the methacrylic polyglycol ether component was omitted, except that the other process steps were the same.

Comparative example 3

In this comparative example, in comparison with example 1, in the raw material weighing step, the acryloyloxyethyltrimethylammonium chloride component was omitted, except that the other steps of the method were the same.

The samples obtained in examples 1 to 5 and comparative examples 1 to 3 were subjected to a net slurry fluidity test using standard cement, W/C of 0.29, a water reducing agent anchoring amount of 0.25% of the amount of cement, and a clay content in place of a portion of the cement, in accordance with GB8077-2000, and the test results are shown in table 1.

TABLE 1 detection results of polycarboxylic acid-based water reducing agents of examples and comparative examples

As can be seen from Table 1, the mud-resistant polycarboxylic acid water reducing agent prepared by the method shows better cement paste fluidity under the condition of no clay, and has good adaptability to cement. Example 1 shows a great advantage in net slurry fluidity with clay addition compared to comparative examples 2 and 3. The adaptability of the anti-mud polycarboxylic acid water reducer to high mud content sandstone is improved under the combined action of the multi-arm molecular structure of the anti-mud polycarboxylic acid water reducer and the components of the methacrylic polyglycol ether and the acryloyloxyethyl trimethyl ammonium chloride.

Concrete slump and strength of samples obtained in preparation examples were tested according to GB8076-2008 "concrete admixture" on the mud-resistant polycarboxylic acid water reducing agents obtained in examples 1-5 and comparative examples 1-3. The concrete mixing proportion is as follows: cement 360kg/m³772kg/m of sand³1068kg/m of stone³The mixing amount of the water reducing agent is 0.25 percent and the mixing amount of the clay is 4 percent. The sand is river sand, and is washed, soaked and aired to be clean, and the fineness modulus is 2.9; the cement is reference cement; the stones (prepared according to the gradation) are washed by water, dried in the sun and dried. The results obtained are shown in Table 2.

TABLE 2 comparison of concrete Performance test results of polycarboxylic acid water reducers of examples and comparative examples

As can be seen from Table 2, the initial slump loss of the concrete of examples 1 to 5 and the slump loss of 1h were superior to those of comparative examples 1 to 3, and the strength of the concrete of examples 1 to 5 was superior to that of comparative examples 1 to 3. Concrete obtained by using the mud-resistant polycarboxylic acid water reducer prepared by the method has obvious advantages in slump property and concrete strength.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that may be made by those skilled in the art within the technical scope of the present invention will be covered by the scope of the present invention.

Claims

1. The mud-resistant polycarboxylic water reducer is characterized in that: the mud-resistant polycarboxylic acid water reducer is prepared by reacting a multi-arm polymer precursor with methacrylic polyglycol ether, an unsaturated acid monomer, acryloyloxyethyl trimethyl ammonium chloride and a chain transfer agent under the action of an initiator, wherein 6-8 parts of the multi-arm polymer precursor, 23-30 parts of the methacrylic polyglycol ether, 20-25 parts of the unsaturated acid monomer, 10-15 parts of acryloyloxyethyl trimethyl ammonium chloride, 0.5-1.2 parts of the chain transfer agent and 0.5-1.5 parts of the initiator are reacted; the multi-arm polymer precursor is obtained by reacting polyvinyl alcohol and acryloyl chloride, wherein the mass ratio of the polyvinyl alcohol to the acryloyl chloride is 1: 2; the polymerization degree of the polyvinyl alcohol is 100, and the alcoholysis degree of the polyvinyl alcohol is 78-88%.

2. The anti-mud polycarboxylic acid water reducer according to claim 1, characterized in that: the molecular weight of the methacrylic polyglycol ether is 2000-2400.

3. The anti-mud polycarboxylic acid water reducer according to claim 1, characterized in that: the unsaturated acid is any one of acrylic acid, methacrylic acid and maleic acid.

4. The anti-mud polycarboxylic acid water reducer according to claim 1, characterized in that: the initiator is any one of dibenzoyl peroxide, tert-butyl peroxydicarbonate-2-ethylhexyl carbonate and tert-butyl peroxybenzoate.

5. The anti-mud polycarboxylic acid water reducer according to claim 1, characterized in that: the chain transfer agent is any one of 2, 4-diphenyl-4-methyl-1-pentene, 3-isooctyl mercaptopropionate and dodecyl mercaptan.

6. The anti-mud polycarboxylic acid water reducer according to claim 1, characterized in that: the mud-resistant polycarboxylic acid water reducer has a multi-arm molecular structure with quaternary ammonium functional groups.

7. The preparation method of the mud-resistant polycarboxylic acid water reducer as defined in any one of claims 1 to 6, characterized by comprising the steps of:

dissolving an initiator in part of dimethyl sulfoxide to form a material B;

8. The preparation method of the mud-resistant polycarboxylic acid water reducer according to claim 7, characterized in that the preparation method of the multi-arm polymer precursor comprises the following steps: