Preparation process of anti-cracking polycarboxylic acid water reducing agent

Abstract

The invention relates to the technical field of concrete admixtures, and discloses a preparation process of an anti-crack polycarboxylate superplasticizer, which comprises the following steps: adding a solution A, modified boric acid, methyl methacrylate and water into a reactor, adding a sodium persulfate initiator solution E, a vitamin C reducing agent solution C and a thiohydracrylic acid chain transfer agent solution D under a stirring condition, and uniformly stirring, thereby obtaining the anti-crack polycarboxylate superplasticizer. Initiating a polymerization reaction, and then dropwise adding the solution B; after dropwise adding is completed, a reaction is conducted, a product is cooled to the room temperature, then the pH value is adjusted to be neutral with alkali liquor, and the anti-crack type polycarboxylate superplasticizer is obtained. Graphene in the modified boric acid has good corrosion resistance and durability, and the crack resistance and mechanical property of concrete can be improved by adding the graphene into the concrete; wherein the boron compound can accelerate the hydration reaction of cement, so that the early strength of the concrete is improved, meanwhile, the microstructure of the concrete can be improved, the concrete is more compact and uniform, and the crack resistance of the concrete is improved.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, in particular to a preparation process of an anti-cracking polycarboxylate water-reducing agent. Background Art

[0002] As concrete develops towards high performance and multifunctionality, the role of water reducers is becoming more and more important, and the performance requirements for water reducers are becoming higher and higher. Although the current water reducers meet the high strength requirements of concrete, the anti-cracking effect is poor. For example, patent CN112300337B discloses a modified polycarboxylic acid water reducer and its preparation method, which can obtain a modified polycarboxylic acid water reducer with excellent slow-release and collapse-preserving effects, anti-bleeding effects and strengthening effects, but the anti-cracking effect is not improved. Summary of the invention

[0003] 1. Technical issues to be resolved In view of the deficiencies of the prior art, the present invention provides a preparation process of a crack-resistant polycarboxylate water-reducing agent, which improves the crack resistance and mechanical properties of concrete.

[0004] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a preparation process of a crack-resistant polycarboxylate water-reducing agent, comprising the following steps: (1) Dissolve isopentanol polyoxyethylene ether in deionized water and stir evenly to obtain solution A; (2) dissolving acrylic acid in deionized water and stirring evenly to obtain solution B; (3) Dissolve 1-3 parts by weight of a vitamin C reducing agent, 2-3 parts by weight of a mercaptopropionic acid chain transfer agent, and a sodium persulfate initiator in deionized water, respectively, and stir evenly to obtain solutions C, D, and E, respectively; (4) Add 150-160 parts by weight of solution A, 10-15 parts by weight of modified boric acid, 30-50 parts by weight of methyl methacrylate, and 90-150 parts by weight of water to a reactor, and add 1-2 parts by weight of sodium persulfate initiator solution E, 1.2-1.5 parts by weight of vitamin C reducing agent solution C, and 1.4-2 parts by weight of mercaptopropionic acid chain transfer agent solution D under stirring conditions to initiate a polymerization reaction, and then drop 40-60 parts by weight of solution B thereto; after the dropwise addition is completed, react at 40-60° C. for 2-6 hours, cool the product to room temperature, and then adjust the pH value to neutral with alkali solution to obtain an anti-cracking polycarboxylic acid water reducer.

[0005] Preferably, the weight content of isopentanol polyoxyethylene ether in (1) is 190-220.

[0006] Preferably, the weight content of acrylic acid in (2) is 50-70.

[0007] Preferably, the weight component of the sodium persulfate initiator in (3) is 2-4.

[0008] Preferably, the preparation method of the modified boric acid in (4) is: S1. Add 4,4'-biphenyl diboronic acid to toluene solvent, stir and disperse, then add N-methyl-2-hydroxyethylamine, react at 110135°C for 12-15h, and after the reaction, distill under reduced pressure, filter and dry to obtain intermediate 1; S2. Add intermediate 1 and 2-chloroethyl vinyl ether to N,N-dimethylformamide solvent, stir and disperse, react at 60-80°C for 12-16h, then continue to add sodium 3-chloro-2-hydroxypropanesulfonate, react at 70-95°C for 6-10h, and then distill under reduced pressure and filter to obtain olefinated boronic acid; S3. ultrasonically dispersing 4-8 parts by weight of graphene oxide into 60-100 parts by weight of thionyl chloride, uniformly dispersing, reacting at 75-80° C., filtering after the reaction, washing, and drying to obtain chlorinated graphene; S4. Add olefinated boronic acid and chlorinated graphene to N,N-dimethylformamide solvent, stir evenly, continue to add triethylamine catalyst, stir and react at 50-80°C for 4-7h, and then distill under reduced pressure and wash to obtain modified boronic acid.

[0009] Preferably, the mass ratio of 4,4'-biphenyldiboric acid to N-methyl-2-hydroxyethylamine in S1 is 1:2.2-2.8.

[0010] Preferably, the mass ratio of the intermediate 1, 2-chloroethyl vinyl ether, and sodium 3-chloro-2-hydroxypropane sulfonate in S2 is 0.8-1.3:1:1.1-1.2.

[0011] Preferably, the mass ratio of olefinated boronic acid, graphene chloride and triethylamine catalyst in S4 is 1:1.2-1.4:0.01-0.03.

[0012] 3. Beneficial technical effects The invention comprises the following steps: adding solution A, modified boric acid, methyl methacrylate and water into a reactor, and adding a sodium persulfate initiator solution E, a vitamin C reducing agent solution C and a mercaptopropionic acid chain transfer agent solution D under stirring conditions to initiate a polymerization reaction, and then dripping solution B therein; after the dripping is completed, reacting, cooling the product to room temperature, and then adjusting the pH value to neutral with an alkali solution to obtain an anti-cracking polycarboxylic acid water reducer.

[0013] The graphene in the modified boric acid has good corrosion resistance and durability. Adding it to concrete can improve the crack resistance and mechanical properties of concrete; the boron compound in it can accelerate the hydration reaction of cement, thereby increasing the early strength of concrete, and at the same time improve the microstructure of concrete, making it denser and more uniform, and improving its crack resistance; the sodium sulfonate group in it can help reduce the water consumption of concrete while maintaining its workability and strength, which helps to improve the density and durability of concrete, and indirectly improves crack resistance. DETAILED DESCRIPTION

[0014] Example 1 (1) dissolving 190 parts by weight of isopentanol polyoxyethylene ether in deionized water and stirring the mixture to obtain solution A; (2) dissolving 50 parts by weight of acrylic acid in deionized water and stirring the mixture to obtain a solution B; (3) dissolving 1 part by weight of a vitamin C reducing agent, 2 parts by weight of a mercaptopropionic acid chain transfer agent, and 2 parts by weight of a sodium persulfate initiator in deionized water, respectively, and stirring evenly to obtain solutions C, D, and E, respectively; (4) Add 150 parts by weight of solution A, 10 parts by weight of modified boric acid, 30 parts by weight of methyl methacrylate, and 90 parts by weight of water into a reactor, and add 1 part by weight of sodium persulfate initiator solution E, 1.2 parts by weight of vitamin C reducing agent solution C, and 1.4 parts by weight of mercaptopropionic acid chain transfer agent solution D under stirring conditions to initiate a polymerization reaction, and then drop 40 parts by weight of solution B thereto; after the dropwise addition is completed, react at 40° C. for 2 hours, cool the product to room temperature, and then adjust the pH value to neutral with an alkali solution to obtain an anti-cracking polycarboxylic acid water reducer.

[0015] The preparation method of the modified boric acid in (4) is: S1. Add 4,4'-biphenyl diboronic acid to toluene solvent, stir and disperse, then add N-methyl-2-hydroxyethylamine, wherein the mass ratio of 4,4'-biphenyl diboronic acid to N-methyl-2-hydroxyethylamine is 1:2.2, react at 110°C for 12h, and after the reaction is completed, distill under reduced pressure, filter and dry to obtain intermediate 1; S2. Add intermediate 1 and 2-chloroethyl vinyl ether to N,N-dimethylformamide solvent, stir and disperse, react at 60° C. for 12 hours, then continue to add sodium 3-chloro-2-hydroxypropanesulfonate, wherein the mass ratio of intermediate 1, 2-chloroethyl vinyl ether and sodium 3-chloro-2-hydroxypropanesulfonate is 0.8:1:1.1, react at 70-95° C. for 6 hours, and then distill under reduced pressure after completion, filter, and obtain olefinated boronic acid; S3. 4 parts by weight of graphene oxide are ultrasonically dispersed in 60 parts by weight of thionyl chloride, and after being uniformly dispersed, reacted at 75° C., filtered after the reaction, washed, and dried to obtain chlorinated graphene; S4. Add olefinated boronic acid and graphene chloride to N,N-dimethylformamide solvent, stir evenly, and continue to add triethylamine catalyst, wherein the mass ratio of olefinated boronic acid, graphene chloride and triethylamine catalyst is 1:1.2:0.01, stir and react at 50°C for 4h, and then distill under reduced pressure and wash to obtain modified boric acid.

[0016] Example 2 (1) dissolving 220 parts by weight of isopentanol polyoxyethylene ether in deionized water and stirring the mixture to obtain solution A; (2) dissolving 70 parts by weight of acrylic acid in deionized water and stirring the mixture to obtain a solution B; (3) 3 parts by weight of a vitamin C reducing agent, 3 parts by weight of a mercaptopropionic acid chain transfer agent, and 4 parts by weight of a sodium persulfate initiator were dissolved in deionized water, and stirred evenly to obtain solutions C, D, and E, respectively; (4) Add 160 parts by weight of solution A, 15 parts by weight of modified boric acid, 50 parts by weight of methyl methacrylate, and 150 parts by weight of water into a reactor, and add 2 parts by weight of sodium persulfate initiator solution E, 1.5 parts by weight of vitamin C reducing agent solution C, and 2 parts by weight of mercaptopropionic acid chain transfer agent solution D under stirring conditions to initiate a polymerization reaction, and then drop 60 parts by weight of solution B thereto; after the dropwise addition is completed, react at 60° C. for 6 hours, cool the product to room temperature, and then adjust the pH value to neutral with an alkali solution to obtain an anti-cracking polycarboxylic acid water reducer.

[0017] The preparation method of the modified boric acid in (4) is: S1. Add 4,4'-biphenyl diboronic acid to toluene solvent, stir and disperse, then add N-methyl-2-hydroxyethylamine, wherein the mass ratio of 4,4'-biphenyl diboronic acid to N-methyl-2-hydroxyethylamine is 1:2.8, react at 135°C for 15h, and after the reaction is completed, distill under reduced pressure, filter and dry to obtain intermediate 1; S2. Add intermediate 1 and 2-chloroethyl vinyl ether to N,N-dimethylformamide solvent, stir and disperse, react at 80°C for 16 hours, then continue to add sodium 3-chloro-2-hydroxypropanesulfonate, wherein the mass ratio of intermediate 1, 2-chloroethyl vinyl ether and sodium 3-chloro-2-hydroxypropanesulfonate is 1.3:1:1.2, react at 95°C for 10 hours, and then distill under reduced pressure and filter to obtain olefinated boronic acid; S3. 8 parts by weight of graphene oxide are ultrasonically dispersed in 100 parts by weight of thionyl chloride, and after being uniformly dispersed, the mixture is reacted at 80° C. After the reaction, the mixture is filtered, washed, and dried to obtain graphene chloride; S4. Add olefinated boronic acid and graphene chloride to N,N-dimethylformamide solvent, stir evenly, and continue to add triethylamine catalyst, wherein the mass ratio of olefinated boronic acid, graphene chloride and triethylamine catalyst is 1:1.4:0.03, stir and react at 80°C for 7h, and then distill under reduced pressure and wash to obtain modified boric acid.

[0018] Example 3 (1) dissolving 200 parts by weight of isopentanol polyoxyethylene ether in deionized water and stirring the mixture to obtain solution A; (2) dissolving 60 parts by weight of acrylic acid in deionized water and stirring the mixture to obtain a solution B; (3) dissolving 2 parts by weight of a vitamin C reducing agent, 2 parts by weight of a mercaptopropionic acid chain transfer agent, and 3 parts by weight of a sodium persulfate initiator in deionized water, respectively, and stirring evenly to obtain solutions C, D, and E, respectively; (4) Add 155 parts by weight of solution A, 12 parts by weight of modified boric acid, 40 parts by weight of methyl methacrylate, and 120 parts by weight of water to a reactor, and add 1 part by weight of sodium persulfate initiator solution E, 1.4 parts by weight of vitamin C reducing agent solution C, and 1.6 parts by weight of mercaptopropionic acid chain transfer agent solution D under stirring conditions to initiate a polymerization reaction, and then drop 50 parts by weight of solution B thereto; after the dropwise addition is completed, react at 50° C. for 4 hours, cool the product to room temperature, and then adjust the pH value to neutral with an alkali solution to obtain an anti-cracking polycarboxylic acid water reducer.

[0019] The preparation method of the modified boric acid in (4) is: S1. Add 4,4'-biphenyl diboronic acid to toluene solvent, stir and disperse, then add N-methyl-2-hydroxyethylamine, wherein the mass ratio of 4,4'-biphenyl diboronic acid to N-methyl-2-hydroxyethylamine is 1:2.6, react at 125°C for 14h, and after the reaction is completed, distill under reduced pressure, filter and dry to obtain intermediate 1; S2. Add intermediate 1 and 2-chloroethyl vinyl ether to N,N-dimethylformamide solvent, stir and disperse, react at 70°C for 14h, then continue to add sodium 3-chloro-2-hydroxypropanesulfonate, wherein the mass ratio of intermediate 1, 2-chloroethyl vinyl ether and sodium 3-chloro-2-hydroxypropanesulfonate is 1.2:1:1.1, react at 85°C for 8h, and after completion, distill under reduced pressure and filter to obtain olefinated boronic acid; S3. ultrasonically dispersing 6 parts by weight of graphene oxide into 90 parts by weight of thionyl chloride, and after being uniformly dispersed, reacting at 78° C., filtering after the reaction, washing, and drying to obtain chlorinated graphene; S4. Add olefinated boronic acid and graphene chloride to N,N-dimethylformamide solvent, stir evenly, and continue to add triethylamine catalyst, wherein the mass ratio of olefinated boronic acid, graphene chloride and triethylamine catalyst is 1:1.3:0.02, stir and react at 60°C for 6h, and then distill under reduced pressure and wash to obtain modified boric acid.

[0020] Comparative Example 1 This comparative example is compared with Example 3, except that no modified boric acid is added.

[0021] Concrete slab crack resistance test: Referring to GB / T 50082-2009, "Test method for long-term performance and durability of ordinary concrete", the solid content of water reducer is 0.5%, wherein the cement is PO 42.5, the fineness modulus is river sand within the range of medium sand, the gravel is 1030.5mm continuous grading, and the admixtures are respectively 40wt.% high-efficiency water reducer FDNC (high-efficiency water reducer produced by Shandong Wanshan Chemical Co., Ltd.) and the polycarboxylate water reducer prepared in Example 13. The test is carried out according to the following mass ratio: cement: fly ash: mineral powder: river sand: gravel: water: admixture = 250: 50: 80: 780: 1000: 200: 8 (unit: kg / m3). The test results of the first crack time, maximum crack width, crack area and 28d strength are shown in Table 1.

[0022]

[0023] It can be seen from Table 1 that the anti-cracking polycarboxylic acid water-reducing agent of the present invention has good anti-cracking effect and mechanical properties.

[0024] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A preparation process of a crack-resistant polycarboxylate water-reducing agent, characterized in that: The following steps are involved: (1) Dissolve isopentanol polyoxyethylene ether in deionized water and stir evenly to obtain solution A; (2) dissolving acrylic acid in deionized water and stirring evenly to obtain solution B; (3) Dissolve 1-3 parts by weight of a vitamin C reducing agent, 2-3 parts by weight of a mercaptopropionic acid chain transfer agent, and a sodium persulfate initiator in deionized water, respectively, and stir evenly to obtain solutions C, D, and E, respectively; (4) Add 150-160 parts by weight of solution A, 10-15 parts by weight of modified boric acid, 30-50 parts by weight of methyl methacrylate, and 90-150 parts by weight of water to a reactor, and add 1-2 parts by weight of sodium persulfate initiator solution E, 1.2-1.5 parts by weight of vitamin C reducing agent solution C, and 1.4-2 parts by weight of mercaptopropionic acid chain transfer agent solution D under stirring conditions to initiate a polymerization reaction, and then drop 40-60 parts by weight of solution B thereto; after the dropwise addition is completed, react at 40-60° C. for 2-6 hours, cool the product to room temperature, and then adjust the pH value to neutral with alkali solution to obtain an anti-cracking polycarboxylic acid water reducer.

2. The preparation process of the anti-cracking polycarboxylate water-reducing agent according to claim 1, characterized in that: The weight content of isopentanol polyoxyethylene ether in (1) is 190-220.

3. The preparation process of the anti-cracking polycarboxylate water-reducing agent according to claim 1, characterized in that: The weight content of acrylic acid in (2) is 50-70.

4. The preparation process of the anti-cracking polycarboxylate water-reducing agent according to claim 1, characterized in that: The weight component of the sodium persulfate initiator in (3) is 2-4.

5. The preparation process of the anti-cracking polycarboxylate water-reducing agent according to claim 1, characterized in that: The preparation method of the modified boric acid in (4) is: S1. Add 4,4'-biphenyl diboronic acid to toluene solvent, stir and disperse, then add N-methyl-2-hydroxyethylamine, react at 110135°C for 12-15h, and after the reaction, distill under reduced pressure, filter and dry to obtain intermediate 1; S2. Add intermediate 1 and 2-chloroethyl vinyl ether to N,N-dimethylformamide solvent, stir and disperse, react at 60-80°C for 12-16h, then continue to add sodium 3-chloro-2-hydroxypropanesulfonate, react at 70-95°C for 6-10h, and then distill under reduced pressure and filter to obtain olefinated boronic acid; S3. ultrasonically dispersing 4-8 parts by weight of graphene oxide into 60-100 parts by weight of thionyl chloride, uniformly dispersing, reacting at 75-80° C., filtering after the reaction, washing, and drying to obtain chlorinated graphene; S4. Add olefinated boronic acid and chlorinated graphene to N,N-dimethylformamide solvent, stir evenly, continue to add triethylamine catalyst, stir and react at 50-80°C for 4-7h, and then distill under reduced pressure and wash to obtain modified boronic acid.

6. The preparation process of the anti-cracking polycarboxylate water-reducing agent according to claim 5, characterized in that: The mass ratio of 4,4'-biphenyldiboronic acid to N-methyl-2-hydroxyethylamine in S1 is 1:2.2-2.

8.

7. The preparation process of the anti-cracking polycarboxylate water-reducing agent according to claim 5, characterized in that: The mass ratio of the intermediate 1, 2-chloroethyl vinyl ether and sodium 3-chloro-2-hydroxypropane sulfonate in S2 is 0.8-1.3:1:1.1-1.

2.

8. The preparation process of the anti-cracking polycarboxylate water-reducing agent according to claim 5, characterized in that: The mass ratio of olefinated boric acid, graphene chloride and triethylamine catalyst in S4 is 1:1.2-1.4:0.01-0.03.

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