Polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention relates to the technical field of concrete admixtures, in particular to a polycarboxylate superplasticizer and a preparation method thereof. Through molecular structure design, glycidyl ether compounds and unsaturated acid are subjected to ring-opening addition, and unsaturated functional monomers with unsaturated functional groups such as carbon-carbon double bonds, carboxyl and ester groups are obtained; condensing the unsaturated functional monomer with ethylene oxide and epoxypropane to obtain a glycidyl ether macromonomer; and carrying out copolymerization on the glycidyl ether macromonomer and free radicals such as polyether and unsaturated acid to obtain the required polycarboxylate superplasticizer. Under the synergistic effect of various groups, the polycarboxylate superplasticizer disclosed by the invention has the characteristics of high water-reducing rate and good adaptability, and the workability of concrete can be remarkably improved.

Description

Technical Field

[0001] The present application relates to the technical field of concrete admixtures, and in particular to a polycarboxylate water reducer and a preparation method thereof. Background Art

[0002] Concrete is the most widely used construction material in the world. Most high-rise buildings, roads, bridges, tunnels and railways are made of concrete. Concrete has become an indispensable infrastructure material for human life.

[0003] Since the 21st century, driven by both market demand and construction demand, high-performance concrete technology has developed rapidly. As the largest and most widely used admixture in concrete, water reducers have also developed rapidly. The application of water reducers can improve the working performance of fresh concrete. It can not only greatly reduce the amount of water used for cement during construction, but also make concrete have higher flowability and stronger mechanical properties. At the same time, the research and application of water reducers have also promoted the further development of concrete production methods, construction methods and high-performance concrete.

[0004] Although polycarboxylate water reducers are widely used in the concrete industry due to their many excellent properties, as natural materials are currently prohibited from being mined, most concrete raw materials are replaced by artificial sand and gravel, and the quality of raw materials is uneven, resulting in the increasingly prominent adaptability of polycarboxylate water reducers. Therefore, research on a high water-reducing and high workability mother liquor that can be used to cope with the current artificial sand and gravel materials is of great significance to the sustainable development of the social economy. Summary of the invention

[0005] In order to solve the problems of the prior art mentioned in the above background technology, the present application provides a polycarboxylate water reducer, and its technical solution is as follows: The polycarboxylic acid water-reducing agent provided in the present application is prepared by copolymerization of unsaturated polyoxyethylene ether, glycidyl ether macromonomer and a first unsaturated acid under the action of an initiator and a chain transfer agent; wherein the glycidyl ether macromonomer is prepared by condensation reaction of an unsaturated glycidyl ether compound and an alkylene oxide under the action of an alkali catalyst; and the unsaturated glycidyl ether compound is prepared by ring-opening addition reaction of a second unsaturated acid and a glycidyl ether compound under the action of a catalyst.

[0006] In some embodiments, the molar ratio of the second unsaturated acid to the glycidyl ether compound is (1-3):1; the alkylene oxide includes ethylene oxide and propylene oxide; wherein the weight ratio of the unsaturated glycidyl ether compound, ethylene oxide and propylene oxide is (100-300):(600-1200):(200-500); the mass ratio of the unsaturated polyoxyethylene ether, glycidyl ether macromonomer to the first unsaturated acid is (240-400):(10-50):(20-50).

[0007] In some embodiments, the glycidyl ether macromonomer preparation process is: The second unsaturated acid and the catalyst are uniformly mixed, and the reaction system is heated to 80-100° C.; the glycidyl ether compound is added at a reaction temperature of 80-100° C., and the glycidyl ether compound is added for 30-60 minutes; and the reaction system is kept at 105-110° C. for (50-70) minutes to obtain an unsaturated glycidyl ether compound; The unsaturated glycidyl ether compound and the alkali catalyst are placed in a reactor and mixed; in an oxygen-free environment filled with nitrogen or inert gas, ethylene oxide and propylene oxide are introduced into the reactor, and then the reaction system is heated to 80-110° C. and pressurized to 0.2-0.35 MPa for condensation reaction. After reacting for 2-6 hours, the reaction system is cooled to 70-80° C. and neutralized by adding a neutralizing liquid to obtain the glycidyl ether macromonomer; wherein the mass ratio of the unsaturated glycidyl ether compound, the alkali catalyst, ethylene oxide and propylene oxide is (100-300): (0.2-1.0): (600-1200): (200-500).

[0008] In some embodiments, the glycidyl ether compound is added dropwise.

[0009] In some embodiments, the glycidyl ether compound is one or more combinations of glycidyl ether, bisphenol A diglycidyl ether, and polyethylene glycol diglycidyl ether; the second unsaturated acid is one or two combinations of acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and fumaric acid; and the catalyst is one or more combinations of N,N-dimethylbenzylamine and triethylamine.

[0010] In some embodiments, the initiator includes an oxidant and a reductant; the copolymerization process is: Add unsaturated polyoxyethylene ether, oxidant and water into a reactor, mix, and stir to dissolve to form a mixed solution; At room temperature, the first mixed solution and the second mixed solution are added dropwise to the mixed solution respectively, and the addition is completed within (0.5-1.5) h, and then the mixture is kept at (25-35) °C for 0.5-1.0 h; Finally, sodium hydroxide is added for neutralization to obtain the polycarboxylate water-reducing agent; The components of the first mixed solution include a first unsaturated acid and water; the components of the second mixed solution include a chain transfer agent, a reducing agent and water; The glycidyl ether macromonomer is added to a reactor together with an unsaturated polyoxyethylene ether, an oxidant, and water to form a mixed solution to participate in a copolymerization reaction, or the glycidyl ether macromonomer is mixed with a first unsaturated acid and water to form the first mixed solution to participate in a copolymerization reaction; the mass ratio of the unsaturated polyoxyethylene ether, the glycidyl ether macromonomer, the first unsaturated acid, the oxidant, the chain transfer agent, and the reducing agent is (240-400): (10-50): (20-50): (1-5): (0.5-2): (0.3-0.8).

[0011] In some embodiments, the copolymerization process is: By weight, 240 to 400 parts of unsaturated polyoxyethylene ether, 1 to 5 parts of oxidant, 10 to 50 parts of glycidyl ether macromonomer and 240 to 400 parts of water are added into a reactor, mixed, and stirred to dissolve to form a mixed solution; At a reaction system temperature of (20-30)°C, the first mixed solution and the second mixed solution are added dropwise to the mixed solution respectively, and the addition is completed within (0.5-1.5) h; and then the mixture is kept at (25-35)°C for 0.5-1.0 hour; Finally, 5 to 20 parts of sodium hydroxide with a mass concentration of (30 to 32)% is added for neutralization to obtain the polycarboxylate water reducer; The components of the first mixed solution include 20 to 50 parts of a first unsaturated acid and 10 to 20 parts of water; the components of the second mixed solution include 0.5 to 2 parts of a chain transfer agent, 0.3 to 0.8 parts of a reducing agent and 30 to 60 parts of water; 10 to 50 parts of the glycidyl ether macromonomer are added to a reactor together with an unsaturated polyoxyethylene ether, an oxidant, and water to form a mixed solution to participate in a copolymerization reaction, or 10 to 50 parts of the glycidyl ether macromonomer are mixed with a first unsaturated acid and water to form the first mixed solution to participate in a copolymerization reaction.

[0012] In some embodiments, the unsaturated polyoxyethylene ether is one or a combination of methyl allyl polyoxyethylene ether with a molecular weight of 2400 and ethylene glycol monovinyl polyoxyethylene ether with a molecular weight of 3000; the first unsaturated acid is one or a combination of two of acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and fumaric acid.

[0013] In some embodiments, the oxidant is one or more combinations of hydrogen peroxide, ammonium persulfate, and potassium persulfate; the chain transfer agent is one or two combinations of thioglycolic acid, 2-mercaptoethanol, 3-mercaptopropionic acid, and sodium hypophosphite; the reducing agent is one or two combinations of sodium sulfite, L-ascorbic acid, and sodium formaldehyde bisulfate.

[0014] The present application also provides a method for preparing the polycarboxylate water-reducing agent as described above, which comprises the following preparation steps: By weight, 240 to 400 parts of unsaturated polyoxyethylene ether, 1 to 5 parts of oxidant, 10 to 50 parts of glycidyl ether macromonomer and 240 to 400 parts of water are added into a reactor, mixed, and stirred to dissolve to form a mixed solution; At a reaction system temperature of (20-30)°C, the first mixed solution and the second mixed solution are added dropwise to the mixed solution respectively, and the addition is completed within 0.5-1.5 hours; and then the mixture is kept at (25-35)°C for 0.5-1.0 hours; Finally, 5 to 20 parts of sodium hydroxide with a mass concentration of (30 to 32)% is added for neutralization to obtain the polycarboxylate water reducer; The components of the first mixed solution include 20 to 50 parts of a first unsaturated acid and 10 to 20 parts of water; the components of the second mixed solution include 0.5 to 2 parts of a chain transfer agent, 0.3 to 0.8 parts of a reducing agent and 30 to 60 parts of water; 10 to 50 parts of the glycidyl ether macromonomer are added to a reactor together with an unsaturated polyoxyethylene ether, an oxidant, and water to form a mixed solution to participate in a copolymerization reaction, or 10 to 50 parts of the glycidyl ether macromonomer are mixed with a first unsaturated acid and water to form the first mixed solution to participate in a copolymerization reaction.

[0015] Compared with the prior art, the polycarboxylate water-reducing agent provided in this application has the following beneficial effects: The polycarboxylate water-reducing agent provided in the present application has the characteristics of high water-reducing rate and good adaptability, and can significantly improve the workability of concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the ring-opening addition reaction mechanism. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0018] The present application provides an operation example of the preparation process of polycarboxylate water reducer as follows: The preparation process includes the following steps: (1) Preparation of unsaturated functional monomers: The second unsaturated acid is added to a four-necked flask, a catalyst is added and stirred evenly, and the mixture is heated to 80-100°C, and a glycidyl ether compound is added dropwise over 30-60 minutes. After the addition is completed, the reaction system is kept at 105-110°C for (50-70) minutes to obtain an unsaturated glycidyl ether compound.

[0019] The molar ratio of the second unsaturated acid to the glycidyl ether compound is (1-3):1. The glycidyl ether compound used is one or more combinations of glycidyl ether, bisphenol A diglycidyl ether, and polyethylene glycol diglycidyl ether; the second unsaturated acid used is one or two combinations of acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and fumaric acid; the catalyst used is one or more combinations of N,N-dimethylbenzylamine and triethylamine; The specific ring-opening addition reaction mechanism is shown in Figure 1 When the glycidyl ether compound used is glycidyl ether, the structure of the corresponding R group is:

[0020] When the glycidyl ether compound used is bisphenol A diglycidyl ether, the structure of the corresponding R group is:

[0021] When the glycidyl ether compound used is polyethylene glycol diglycidyl ether, the structure of the corresponding R group is:

[0022] It should be noted that: Figure 1 Only the ring-opening addition reaction of a certain epoxy group in the glycidyl ether compound and the unsaturated acid fumaric acid is shown in the reaction formula. This reaction formula is only used as a mechanism illustration and does not limit the ring-opening addition reaction of the present application. In the actual reaction process of the present application, it is not limited to only a certain epoxy group in the glycidyl ether compound undergoing the ring-opening addition reaction. The epoxy group in the R group can also undergo the ring-opening addition reaction simultaneously. Similarly, the fumaric acid in the reaction formula is only used as an example and is not limited to the use of fumaric acid.

[0023] (2) Preparation of glycidyl ether macromonomers: 100 to 300 parts by mass of an unsaturated glycidyl ether compound and 0.2 to 1.0 parts of a base catalyst are placed in a reactor; Nitrogen or inert gas is flushed into the reaction system, and then 600-1200 parts of ethylene oxide and 200-500 parts of propylene oxide are introduced in an oxygen-free environment. The reaction system is heated to 80-110°C and pressurized to 0.2-0.35MPa for condensation reaction. After reacting for 2-6 hours, the temperature is lowered to 70-80°C, and a neutralizing liquid is added for neutralization to obtain a glycidyl ether macromonomer.

[0024] (3) Preparation of polycarboxylate water reducer By weight, 240 to 400 parts of unsaturated polyoxyethylene ether, 1 to 5 parts of oxidant and 240 to 400 parts of deionized water are added into a reactor and mixed and stirred to dissolve; At a reaction system temperature of 20-30° C., the first mixed solution and the second mixed solution are added dropwise respectively, and the addition is completed within 0.5-1.5 hours. The mixture is kept at (25-35)° C. for 0.5-1.0 hours, and 5-20 parts of sodium hydroxide with a mass concentration of (30-32)% are added for neutralization to obtain the polycarboxylate water reducer.

[0025] The first mixed solution comprises 20 to 50 parts of a first unsaturated acid and 10 to 20 parts of water; the second mixed solution comprises 0.5 to 2 parts of a chain transfer agent, 0.3 to 0.8 parts of a reducing agent and 30 to 60 parts of water; Among them, 10 to 50 parts of the glycidyl ether macromonomer are added to the reactor together with unsaturated polyoxyethylene ether, oxidant and water to form a mixed solution to participate in the copolymerization reaction, or 10 to 50 parts of the glycidyl ether macromonomer are mixed with the first unsaturated acid and water to form the first mixed solution to participate in the copolymerization reaction.

[0026] Raw material selection: The unsaturated polyoxyethylene ether used is one or a combination of methyl allyl polyoxyethylene ether with a molecular weight of 2400 and ethylene glycol monovinyl polyoxyethylene ether with a molecular weight of 3000; the first unsaturated acid used is one or a combination of acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and fumaric acid; the oxidant used is one or a combination of hydrogen peroxide, ammonium persulfate, and potassium persulfate; the chain transfer agent used is one or a combination of thioglycolic acid, 2-mercaptoethanol and 3-mercaptopropionic acid, and sodium hypophosphite; the reducing agent used is one or a combination of sodium sulfite, L-ascorbic acid, and sodium formaldehyde hyposulfite.

[0027] The present invention also provides the following embodiments and comparative examples: Example 1 (1) Preparation of unsaturated functional monomers: 50 parts of fumaric acid are added to a four-necked flask, 1 part of N,N-dimethylbenzylamine is used as a catalyst, stirred evenly, heated to 90°C, 80 parts of glycidyl ether are added dropwise for 40 minutes, and after the addition is completed, the mixture is kept at 105°C for 60 minutes to obtain an unsaturated glycidyl ether compound, i.e., an unsaturated glycidyl ether functional monomer.

[0028] (2) Preparation of macromonomer 140 parts of unsaturated glycidyl ether compounds and 0.5 parts of potassium hydroxide are placed in a reactor, flushed with nitrogen, and then 820 parts of ethylene oxide and 210 parts of propylene oxide are introduced in an oxygen-free environment. The reaction is heated to 80°C and pressurized to 0.30 MPa for condensation reaction. After reacting for 5 hours, the temperature is lowered to 70°C, and sodium hydroxide is added for neutralization to obtain a glycidyl ether macromonomer.

[0029] (3) Preparation of polycarboxylate water reducer: 320 parts of methyl allyl polyoxyethylene ether with a molecular weight of 2400, 1.2 parts of an oxidant (hydrogen peroxide is selected as the oxidant), 20 parts of a glycidyl ether macromonomer, and 260 parts of deionized water are added to a reactor and mixed. After stirring and dissolving, the first mixed solution and the second mixed solution are respectively added dropwise at room temperature (20-30° C.), and the addition is completed within 1.5 hours. The mixture is kept at (25-35)° C. for 1.0 hour, 10 parts of sodium hydroxide with a mass concentration of 32% is added for neutralization, and water is added to a solid content of 40% to obtain the polycarboxylate water reducer.

[0030] Among them, 42 parts of acrylic acid and 10 parts of deionized water are mixed to form the first mixed solution; 1.6 parts of thioglycolic acid, 0.8 parts of L-ascorbic acid and 60 parts of deionized water are mixed to form the second mixed solution.

[0031] Example 2 The preparation of the unsaturated functional monomer in step (1) of this embodiment and the glycidyl ether macromonomer in step (2) are the same as step (1) and step (2) in embodiment 1.

[0032] (3) Preparation of polycarboxylate water reducer: 300 parts of methyl allyl polyoxyethylene ether with a molecular weight of 2400, 1.2 parts of an oxidant, 40 parts of a glycidyl ether macromonomer, and 260 parts of deionized water are added to a reactor and mixed. After stirring and dissolving, the first mixed solution and the second mixed solution are respectively added dropwise at room temperature (20-30° C.), and the addition is completed within 1.5 hours. The mixture is kept at (25-35)° C. for 1.0 hour, 10 parts of sodium hydroxide with a mass concentration of 32% is added for neutralization, and water is added to a solid content of 40% to obtain the polycarboxylic acid water reducer.

[0033] Among them, 42 parts of acrylic acid and 10 parts of deionized water are mixed to form the first mixed solution; 1.6 parts of thioglycolic acid, 0.8 parts of L-ascorbic acid and 60 parts of deionized water are mixed to form the second mixed solution.

[0034] Example 3 The preparation of the unsaturated functional monomer in step (1) of this embodiment and the glycidyl ether macromonomer in step (2) are the same as step (1) and step (2) in embodiment 1.

[0035] (3) Preparation of polycarboxylate water reducer: 320 parts of methyl allyl polyoxyethylene ether with a molecular weight of 2400, 1.2 parts of an oxidant, and 260 parts of deionized water are added to a reactor and mixed. After stirring and dissolving, the first mixed solution and the second mixed solution are respectively added dropwise at room temperature (20-30° C.), and the addition is completed within 1.5 hours. The mixture is kept at (25-35)° C. for 1.0 hour, 10 parts of sodium hydroxide with a mass concentration of 32% is added for neutralization, and water is added to a solid content of 40% to obtain the polycarboxylic acid water reducer.

[0036] Among them, 42 parts of acrylic acid, 20 parts of glycidyl ether macromonomer and 10 parts of deionized water are mixed to form the first mixed solution; 1.6 parts of thioglycolic acid, 0.8 parts of L-ascorbic acid and 60 parts of deionized water are mixed to form the second mixed solution.

[0037] Comparative Example 1 (Compared with Example 1, the only difference is that the glycidyl ether macromonomer is not involved in the polymerization) The only difference between this comparative example and Example 1 is that the glycidyl ether macromonomer is not involved in the polymerization, and the other steps and conditions are the same as those of Example 1. The specific preparation process is: 320 parts of methyl allyl polyoxyethylene ether with a molecular weight of 2400, 1.2 parts of an oxidant, and 260 parts of deionized water are added to a reactor and mixed. After stirring and dissolving, the first mixed solution and the second mixed solution are respectively added dropwise at room temperature (20-30° C.), and the addition is completed within 1.5 hours. The mixture is kept at (25-35)° C. for 1.0 hour, 10 parts of sodium hydroxide with a mass concentration of 32% is added for neutralization, and water is added to a solid content of 40% to obtain the polycarboxylic acid water reducer.

[0038] Among them, 42 parts of acrylic acid and 10 parts of deionized water are mixed to form the first mixed solution; 1.6 parts of thioglycolic acid, 0.8 parts of L-ascorbic acid and 60 parts of deionized water are mixed to form the second mixed solution.

[0039] Comparative Example 2 (Compared with Example 1, glycidyl ether without the first and second steps was used to replace the glycidyl ether macromonomer) The only difference between this comparative example and Example 1 is that the glycidyl ether without ring-opening addition reaction is used to replace the glycidyl ether macromonomer, that is, the glycidyl ether is not subjected to the first and second steps and is directly added as the reaction raw material of the third step, and the other steps and conditions are the same as those of Example 1. The specific preparation process is: 320 parts of methyl allyl polyoxyethylene ether with a molecular weight of 2400, 1.2 parts of an oxidant, 20 parts of glycidyl ether, and 260 parts of deionized water are added to a reactor and mixed. After stirring and dissolving, the first mixed solution and the second mixed solution are respectively added dropwise at room temperature (20-30° C.), and the addition is completed within 1.5 hours. The mixture is kept at (25-35)° C. for 1.0 hour, 10 parts of sodium hydroxide with a mass concentration of 32% is added for neutralization, and water is added to a solid content of 40% to obtain the polycarboxylic acid water reducer.

[0040] Among them, 42 parts of acrylic acid and 10 parts of deionized water are mixed to form the first mixed solution; 1.6 parts of thioglycolic acid, 0.8 parts of L-ascorbic acid and 60 parts of deionized water are mixed to form the second mixed solution.

[0041] Comparative Example 3 (Compared with Example 1, the unsaturated glycidyl ether compound prepared in the first step is used to replace the glycidyl ether macromonomer) The only difference between this comparative example and Example 1 is that the unsaturated glycidyl ether compound that has not undergone condensation reaction is used to replace the glycidyl ether macromonomer, that is, the unsaturated glycidyl ether compound prepared in the first step is not subjected to the condensation reaction with propylene oxide and ethylene oxide in the second step, but is directly added as the reaction raw material in the third step, and the other steps and conditions are the same as those in Example 1. The specific preparation process is: 320 parts of methyl allyl polyoxyethylene ether with a molecular weight of 2400, 1.2 parts of an oxidant, 20 parts of an unsaturated glycidyl ether compound, and 260 parts of deionized water are added to a reactor and mixed. After stirring and dissolving, the first mixed solution and the second mixed solution are respectively added dropwise at room temperature (20-30° C.), and the addition is completed within 1.5 hours. The mixture is kept at (25-35)° C. for 1.0 hour, 10 parts of sodium hydroxide with a mass concentration of 32% is added for neutralization, and water is added to a solid content of 40% to obtain the polycarboxylic acid water reducer.

[0042] Among them, 42 parts of acrylic acid and 10 parts of deionized water are mixed to form the first mixed solution; 1.6 parts of thioglycolic acid, 0.8 parts of L-ascorbic acid and 60 parts of deionized water are mixed to form the second mixed solution.

[0043] Comparative Example 4 (Compared with Example 1, the amounts of ethylene oxide and propylene oxide added in the second step are different) The only difference between this comparative example and Example 1 is that the amounts of ethylene oxide and propylene oxide added in the second step are different, and the other steps and conditions are the same as those in Example 1. The specific preparation process of the second step is: 140 parts of unsaturated glycidyl ether compounds and 0.5 parts of potassium hydroxide are placed in a reactor, flushed with nitrogen, and then 580 parts of ethylene oxide and 520 parts of propylene oxide are introduced in an oxygen-free environment. The reaction is heated to 80°C and pressurized to 0.30 MPa for condensation reaction. After reacting for 5 hours, the temperature is lowered to 70°C, and sodium hydroxide is added for neutralization to obtain a glycidyl ether macromonomer.

[0044] The water reducing agents prepared in the above examples and comparative examples were subjected to the following performance tests: The polycarboxylate water-reducing agent synthesized in the embodiment and the comparative example product were subjected to comparative tests. Southern P.O42.5R cement was used, with the addition amount being 2.0% of the mortar mass (0.20% as solid), and different performance indicators were tested according to the mortar water reduction rate test method in GB 8076-2008 "Concrete Admixtures" and GBT 50081-2002 "Test Method for Mechanical Properties of Ordinary Concrete".

[0045] The test results and concrete mix ratio are shown in Tables 1-3 below.

[0046] Table 1 Water reduction rate of mortar with different polycarboxylate water reducers

[0047] Table 2 C30 concrete mix ratio (kg / m 3 )

[0048] Table 3 Concrete performance test results of different polycarboxylate water reducers

[0049] Analysis of the above comparative examples and embodiment data shows that: (1) Compared with Comparative Example 1, the polycarboxylic acid water-reducing agents of Examples 1-3 of the present application have a higher water reduction rate and a significantly smaller concrete loss over time when the dosage is the same, which indicates that the polycarboxylic acid water-reducing agents prepared in the present application have better water reduction and slump retention effects than conventional water-reducing agents.

[0050] (2) Comparison of the test results of Example 1 and Comparative Example 2 shows that, compared with the water-reducing agent to which the glycidyl ether compound is directly added, the polycarboxylic acid water-reducing agent prepared in the present application has better water-reducing and collapse-preserving effects.

[0051] (3) Comparison of the test results of Example 1 and Comparative Example 3 shows that, compared with the water reducer formed by directly adding unsaturated glycidyl ether compounds to participate in copolymerization, the polycarboxylic acid water reducer prepared in the present application has better water reduction performance, and its slump retention performance is slightly worse than that of the water reducer prepared in Comparative Example 3. The reasons may be: The structure produced by the glycidyl ether macromonomer used in the polycarboxylate water-reducing agent prepared in the present application tends to extend the length of the polyether side chain, provide better steric hindrance and thus have a higher water reduction rate. The role played by the participation of the glycidyl ether compound in the copolymerization in Comparative Example 3 is to provide a slow-release functional structure with an ester group, thereby achieving a better collapse-preserving effect. The design concept of Comparative Example 3 tends to improve the collapse-preserving effect, which is different from the design purpose and effect of the present application.

[0052] (4) Comparison of the test results of Example 1 and Comparative Example 4 shows that the polycarboxylic acid water-reducing agent prepared in this application has better water-reducing and slump-retaining performance than the product prepared when the weight ratio of unsaturated glycidyl ether compounds, ethylene oxide, and propylene oxide is not within the limited range of the application. The reasons may be: The amount of ethylene oxide is reduced, while the less active propylene oxide is increased, which makes the reaction more difficult, the side reactions more frequent, and the reaction more difficult to initiate. This causes the molecular weight distribution of the macromonomer to become wider and the chain length to become shorter, thus affecting the steric hindrance of the structure introduced into the water reducer.

[0053] In summary, the present application scheme has at least the following design concepts and beneficial effects: (1) The present application adopts molecular structure design, adopts ring-opening addition reaction of glycidyl ether compounds with unsaturated acids to obtain unsaturated functional monomers having unsaturated functional groups such as carbon-carbon double bonds, carboxyl groups, and ester groups; the unsaturated functional monomers are condensed with ethylene oxide and propylene oxide to obtain glycidyl ether macromonomers; and the glycidyl ether macromonomers are copolymerized with free radicals such as polyethers and unsaturated acids to obtain the desired polycarboxylic acid water reducer.

[0054] Due to the introduction of macromonomers with glycidyl ether compound structures in the polycarboxylate water-reducing agent, the length of the polyether side chain in the water-reducing agent molecule is increased, the structural rigidity of the polycarboxylate water-reducing agent is changed, and the steric hindrance effect of the water-reducing agent molecule is increased, so that the carboxyl groups wrapped by cement hydrates but not playing a dispersing role can be exposed, and the adsorption amount of the water-reducing agent molecule is increased. In addition, the side chains of the water-reducing agent molecules contain a large number of hydroxyl groups, carboxyl groups, ester groups and other groups, which can significantly improve the water-reducing performance and slump-retaining performance of concrete, reduce the loss of water-reducing groups, and make the water-reducing agent have better adaptability. In summary, under the synergistic effect of various groups, the polycarboxylate water-reducing agent of the present application has the characteristics of high water reduction rate and good adaptability, and can significantly improve the workability of concrete.

[0055] In addition, it is well known to those skilled in the art that if the side chain length, steric hindrance and other characteristics of the water reducer are different (i.e., the structural characteristics of the water reducer are different), the effects they bring are also different. The design concept of this application is not only to introduce the glycidyl ether structure into the molecular structure of the water reducer. This application needs to control the parameters such as the ratio design of ethylene oxide and propylene oxide to the unsaturated glycidyl ether compound in the condensation reaction, so that the structure and chain length of the introduced glycidyl ether compound macromonomer are controlled within the required range of this application. The desired effect can be achieved by introducing the glycidyl ether compound macromonomer with this specific structure (specific chain length and steric hindrance). For example: It can be seen from Comparative Example 4 that although the chain length is adjusted by condensing ethylene oxide and propylene oxide with unsaturated glycidyl ether compounds, their dosage is not within the scope specified in the present application, resulting in the chain length and steric hindrance effect being inconsistent with the present application, resulting in the water reducer failing to achieve the desired effect of the present application.

[0056] (2) The process of preparing the water reducing agent in this application is simple and easy, the conditions are easy to control, and it has good industrial prospects.

[0057] It should be noted that: In this article, “~” is used to indicate a numerical range, and the range indicated by this expression includes two endpoint values.

[0058] In addition to the actual selections embodied in the above specific embodiments, the above formulation ranges may be used in the specific implementation of the present application, including but not limited to the above embodiment schemes.

[0059] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments of the present application, but are not intended to limit the present application. Those skilled in the art may make adaptive adjustments within the scope of the present application.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A polycarboxylate water reducer, characterized in that: It is formed by copolymerization of unsaturated polyoxyethylene ether, glycidyl ether macromonomer and first unsaturated acid under the action of initiator and chain transfer agent; The glycidyl ether macromonomer is prepared by condensation reaction of unsaturated glycidyl ether compounds and alkylene oxides in the presence of a base catalyst; The unsaturated glycidyl ether compound is prepared by a ring-opening addition reaction between a second unsaturated acid and a glycidyl ether compound under the action of a catalyst.

2. The polycarboxylate water-reducing agent according to claim 1, characterized in that: The molar ratio of the second unsaturated acid to the glycidyl ether compound is (1-3):1; The alkylene oxide includes ethylene oxide and propylene oxide; wherein the weight ratio of the unsaturated glycidyl ether compound, ethylene oxide and propylene oxide is (100-300): (600-1200): (200-500); The mass ratio of the unsaturated polyoxyethylene ether, glycidyl ether macromonomer and the first unsaturated acid is (240-400): (10-50): (20-50).

3. The polycarboxylate water reducer according to claim 1, characterized in that: The glycidyl ether macromonomer preparation process is as follows: The second unsaturated acid and the catalyst are uniformly mixed, and the reaction system is heated to 80-100° C.; the glycidyl ether compound is added at a reaction temperature of 80-100° C., and the glycidyl ether compound is added for 30-60 minutes; and the reaction system is kept at 105-110° C. for (50-70) minutes to obtain an unsaturated glycidyl ether compound; The unsaturated glycidyl ether compound and the base catalyst are placed in a reactor and mixed; in an oxygen-free environment filled with nitrogen or inert gas, ethylene oxide and propylene oxide are introduced into the reactor, and then the reaction system is heated to 80-110° C. and pressurized to 0.2-0.35 MPa for condensation reaction. After reacting for 2-6 hours, the reaction system is cooled to 70-80° C. and neutralized by adding a neutralizing liquid to obtain the glycidyl ether macromonomer; Among them, the mass ratio of unsaturated glycidyl ether compound, base catalyst, ethylene oxide and propylene oxide is (100-300): (0.2-1.0): (600-1200): (200-500).

4. The polycarboxylate water-reducing agent according to claim 3, characterized in that: The glycidyl ether compound is added dropwise.

5. The polycarboxylate water-reducing agent according to claim 3, characterized in that: The glycidyl ether compound is one or more of glycidyl ether, bisphenol A diglycidyl ether, and polyethylene glycol diglycidyl ether; The second unsaturated acid is one or a combination of two of acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and fumaric acid; The catalyst is one or more combinations of N,N-dimethylbenzylamine and triethylamine.

6. The polycarboxylate water-reducing agent according to claim 1, characterized in that: The initiator includes an oxidizing agent and a reducing agent; The copolymerization process is: Add unsaturated polyoxyethylene ether, oxidant and water into a reactor, mix, and stir to dissolve to form a mixed solution; At room temperature, the first mixed solution and the second mixed solution are added dropwise to the mixed solution respectively, and the addition is completed within (0.5-1.5) h, and then the mixture is kept at (25-35) °C for 0.5-1.0 h; Finally, sodium hydroxide is added for neutralization to obtain the polycarboxylate water-reducing agent; The components of the first mixed solution include a first unsaturated acid and water; the components of the second mixed solution include a chain transfer agent, a reducing agent and water; The glycidyl ether macromonomer is added to a reactor together with an unsaturated polyoxyethylene ether, an oxidant, and water to form a mixed solution to participate in a copolymerization reaction, or the glycidyl ether macromonomer is mixed with a first unsaturated acid and water to form the first mixed solution to participate in a copolymerization reaction; The mass ratio of the unsaturated polyoxyethylene ether, the glycidyl ether macromonomer, the first unsaturated acid, the oxidant, the chain transfer agent, and the reducing agent is (240-400): (10-50): (20-50): (1-5): (0.5-2): (0.3-0.8).

7. The polycarboxylate water-reducing agent according to claim 1, characterized in that: The copolymerization process is: By weight, 240 to 400 parts of unsaturated polyoxyethylene ether, 1 to 5 parts of oxidant, 10 to 50 parts of glycidyl ether macromonomer and 240 to 400 parts of water are added into a reactor, mixed, and stirred to dissolve to form a mixed solution; At a reaction system temperature of (20-30)°C, the first mixed solution and the second mixed solution are added dropwise to the mixed solution respectively, and the addition is completed within (0.5-1.5) h; and then the mixture is kept at (25-35)°C for 0.5-1.0 hour; Finally, 5 to 20 parts of sodium hydroxide with a mass concentration of (30 to 32)% is added for neutralization to obtain the polycarboxylate water reducer; The components of the first mixed solution include 20 to 50 parts of a first unsaturated acid and 10 to 20 parts of water; the components of the second mixed solution include 0.5 to 2 parts of a chain transfer agent, 0.3 to 0.8 parts of a reducing agent and 30 to 60 parts of water; 10 to 50 parts of the glycidyl ether macromonomer are added to a reactor together with an unsaturated polyoxyethylene ether, an oxidant, and water to form a mixed solution to participate in a copolymerization reaction, or 10 to 50 parts of the glycidyl ether macromonomer are mixed with a first unsaturated acid and water to form the first mixed solution to participate in a copolymerization reaction.

8. The polycarboxylate water-reducing agent according to claim 1, characterized in that: The unsaturated polyoxyethylene ether is one or a combination of methyl allyl polyoxyethylene ether with a molecular weight of 2400 and ethylene glycol monovinyl polyoxyethylene ether with a molecular weight of 3000; The first unsaturated acid is one or a combination of two of acrylic acid, methacrylic acid, maleic anhydride, itaconic acid and fumaric acid.

9. The polycarboxylate water-reducing agent according to claim 7, characterized in that: The oxidant is one or more combinations of hydrogen peroxide, ammonium persulfate, and potassium persulfate; The chain transfer agent is one or a combination of two of mercaptoacetic acid, 2-mercaptoethanol, 3-mercaptopropionic acid, and sodium hypophosphite; The reducing agent is one or a combination of two of sodium sulfite, L-ascorbic acid, and sodium formaldehyde bisulfate.

10. A method for preparing the polycarboxylate water-reducing agent according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: By weight, 240 to 400 parts of unsaturated polyoxyethylene ether, 1 to 5 parts of oxidant, 10 to 50 parts of glycidyl ether macromonomer and 240 to 400 parts of water are added into a reactor, mixed, and stirred to dissolve to form a mixed solution; At a reaction system temperature of (20-30)°C, the first mixed solution and the second mixed solution are added dropwise to the mixed solution respectively, and the addition is completed within 0.5-1.5 hours; Then keep warm at (25-35)°C for 0.5-1.0 hour; Finally, 5 to 20 parts of sodium hydroxide with a mass concentration of (30 to 32)% is added for neutralization to obtain the polycarboxylate water reducer; The components of the first mixed solution include 20 to 50 parts of a first unsaturated acid and 10 to 20 parts of water; the components of the second mixed solution include 0.5 to 2 parts of a chain transfer agent, 0.3 to 0.8 parts of a reducing agent and 30 to 60 parts of water; 10 to 50 parts of the glycidyl ether macromonomer are added to a reactor together with an unsaturated polyoxyethylene ether, an oxidant, and water to form a mixed solution to participate in a copolymerization reaction, or 10 to 50 parts of the glycidyl ether macromonomer are mixed with a first unsaturated acid and water to form the first mixed solution to participate in a copolymerization reaction.

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