Preparation process of anti-cracking polycarboxylate water reducer

Abstract

The present invention relates to the technical field of concrete admixtures, and discloses a preparation process for a crack-resistant polycarboxylate water-reducing agent. The present invention comprises the following steps: adding solution A, modified boric acid, methyl methacrylate, and water to 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 to initiate a polymerization reaction, and then dripping solution B thereto; after the dripping is completed, reacting, cooling the product to room temperature, and then adjusting the pH value to neutral with an alkaline solution to obtain the crack-resistant polycarboxylate water-reducing agent. The graphene in the modified boric acid has good corrosion resistance and durability, and adding the graphene to concrete can improve the crack resistance and mechanical properties of the concrete; the boron compound therein can accelerate the hydration reaction of cement, thereby improving the early strength of the concrete, and at the same time can improve the microstructure of the concrete, making it more dense and uniform, and improving its crack resistance.

Description

Technical Field

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

[0002] As concrete develops towards higher performance and multifunctionality, the role of water reducers is becoming increasingly important, and the performance requirements for these agents are also becoming increasingly stringent. While current water reducers meet concrete's high strength requirements, they offer poor crack resistance. For example, patent CN112300337B discloses a modified polycarboxylate water reducer and its preparation method, demonstrating excellent sustained-release, anti-blight, and reinforcement properties. However, this modified polycarboxylate water reducer exhibits no improvement in crack resistance. Summary of the Invention

[0003] (1) Technical problems solved

[0004] 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.

[0005] (2) Technical solution

[0006] 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:

[0007] (1) Dissolve isopentenol polyoxyethylene ether in deionized water and stir evenly to obtain solution A;

[0008] (2) Dissolve acrylic acid in deionized water and stir evenly to obtain solution B;

[0009] (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;

[0010] (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 the 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 dropwise add 40-60 parts by weight of solution B; 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.

[0011] Preferably, the weight content of isopentanol polyoxyethylene ether in (1) is 190-220.

[0012] Preferably, the weight content of acrylic acid in (2) is 50-70.

[0013] Preferably, the weight content of the sodium persulfate initiator in (3) is 2-4.

[0014] Preferably, the preparation method of the modified boric acid in (4) is:

[0015] S1. Add 4,4'-biphenyldiboronic acid to toluene solvent, stir and disperse, then add N-methyl-2-hydroxyethylamine, react at 110-135°C for 12-15 hours. After the reaction is completed, distill under reduced pressure, filter and dry to obtain intermediate 1;

[0016] S2. Add intermediate 1 and 2-chloroethyl vinyl ether to N,N-dimethylformamide solvent, stir and disperse, react at 60-80°C for 12-16 hours, then continue to add sodium 3-chloro-2-hydroxypropanesulfonate, react at 70-95°C for 6-10 hours, and then distill under reduced pressure and filter to obtain olefinated boronic acid;

[0017] S3. 4-8 parts by weight of graphene oxide is ultrasonically dispersed into 60-100 parts by weight of thionyl chloride, uniformly dispersed, reacted at 75-80 ° C, filtered after the reaction, washed, and dried to obtain graphene chloride;

[0018] S4. Add olefinated boronic acid and graphene chloride to N,N-dimethylformamide solvent, stir evenly, continue to add triethylamine catalyst, stir and react at 50-80°C for 4-7 hours, and then distill under reduced pressure and wash to obtain modified boronic acid.

[0019] Preferably, the mass ratio of 4,4'-biphenyldiboronic acid to N-methyl-2-hydroxyethylamine in S1 is 1:2.2-2.8.

[0020] Preferably, the mass ratio of the intermediate 1, 2-chloroethyl vinyl ether, and sodium 3-chloro-2-hydroxypropanesulfonate in S2 is 0.8-1.3:1:1.1-1.2.

[0021] 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.

[0022] (3) Beneficial technical effects

[0023] 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 to initiate a polymerization reaction, and then dropwise adding solution B; after the dropwise addition 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 polycarboxylate water-reducing agent.

[0024] The graphene in the modified boric acid has good corrosion resistance and durability. Adding it to concrete can improve the concrete's crack resistance and mechanical properties; 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 its crack resistance. DETAILED DESCRIPTION

[0025] Example 1

[0026] (1) Dissolve 190 parts by weight of prenol polyoxyethylene ether in deionized water and stir evenly to obtain solution A;

[0027] (2) Dissolve 50 parts by weight of acrylic acid in deionized water and stir evenly to obtain solution B;

[0028] (3) Dissolve 1 part by weight of vitamin C reducing agent, 2 parts by weight of mercaptopropionic acid chain transfer agent, and 2 parts by weight of sodium persulfate initiator in deionized water, stir evenly, and obtain solutions C, D, and E, respectively;

[0029] (4) 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 were added to the reactor, and 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 were added under stirring to initiate a polymerization reaction, and then 40 parts by weight of solution B was added dropwise thereto; after the addition was completed, the reaction was carried out at 40°C for 2 hours, the product was cooled to room temperature, and then the pH value was adjusted to neutral with alkaline solution to obtain an anti-cracking polycarboxylic acid water reducer.

[0030] The preparation method of the modified boric acid in (4) is:

[0031] S1. 4,4'-biphenyl diboronic acid was added to a toluene solvent and stirred to disperse the mixture. N-methyl-2-hydroxyethylamine was then added thereto in a mass ratio of 4,4'-biphenyl diboronic acid to N-methyl-2-hydroxyethylamine of 1:2.2. The mixture was reacted at 110°C for 12 hours. After the reaction was completed, the mixture was evaporated under reduced pressure, filtered, and dried to obtain Intermediate 1.

[0032] 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, and react at 70-95°C for 6 hours. After completion, distill under reduced pressure and filter to obtain olefinated boronic acid;

[0033] S3. 4 parts by weight of graphene oxide were ultrasonically dispersed into 60 parts by weight of thionyl chloride, and after uniform dispersion, the mixture was reacted at 75 ° C. After the reaction, the mixture was filtered, washed, and dried to obtain graphene chloride;

[0034] 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 boronic acid.

[0035] Example 2

[0036] (1) Dissolve 220 parts by weight of isopentanol polyoxyethylene ether in deionized water and stir evenly to obtain solution A;

[0037] (2) Dissolve 70 parts by weight of acrylic acid in deionized water and stir evenly to obtain solution B;

[0038] (3) 3 parts by weight of vitamin C reducing agent, 3 parts by weight of mercaptopropionic acid chain transfer agent, and 4 parts by weight of sodium persulfate initiator were dissolved in deionized water, and stirred to obtain solutions C, D, and E, respectively;

[0039] (4) 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 were added to the reactor, and 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 were added under stirring to initiate a polymerization reaction, and then 60 parts by weight of solution B was added dropwise thereto; after the addition was completed, the reaction was carried out at 60°C for 6 hours, the product was cooled to room temperature, and then the pH value was adjusted to neutral with alkaline solution to obtain an anti-cracking polycarboxylic acid water reducer.

[0040] The preparation method of the modified boric acid in (4) is:

[0041] S1. 4,4'-biphenyl diboronic acid was added to a toluene solvent and stirred to disperse the mixture. N-methyl-2-hydroxyethylamine was then added thereto. The mass ratio of 4,4'-biphenyl diboronic acid to N-methyl-2-hydroxyethylamine was 1:2.8. The mixture was reacted at 135°C for 15 hours. After the reaction was completed, the mixture was evaporated under reduced pressure, filtered, and dried to obtain Intermediate 1.

[0042] 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, and react at 95°C for 10 hours. After completion, distill under reduced pressure and filter to obtain olefinated boronic acid;

[0043] S3. 8 parts by weight of graphene oxide were ultrasonically dispersed into 100 parts by weight of thionyl chloride, and after uniform dispersion, the mixture was reacted at 80 ° C. After the reaction, the mixture was filtered, washed, and dried to obtain graphene chloride;

[0044] 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 7 hours, and then distill under reduced pressure and wash to obtain modified boronic acid.

[0045] Example 3

[0046] (1) Dissolve 200 parts by weight of prenol polyoxyethylene ether in deionized water and stir evenly to obtain solution A;

[0047] (2) Dissolve 60 parts by weight of acrylic acid in deionized water and stir evenly to obtain solution B;

[0048] (3) 2 parts by weight of vitamin C reducing agent, 2 parts by weight of mercaptopropionic acid chain transfer agent, and 3 parts by weight of sodium persulfate initiator were dissolved in deionized water, and stirred to obtain solutions C, D, and E, respectively;

[0049] (4) 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 were added to the reactor, and 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 were added under stirring to initiate a polymerization reaction, and then 50 parts by weight of solution B was added dropwise thereto; after the addition was completed, the reaction was carried out at 50°C for 4 hours, the product was cooled to room temperature, and then the pH value was adjusted to neutral with alkaline solution to obtain an anti-cracking polycarboxylic acid water reducer.

[0050] The preparation method of the modified boric acid in (4) is:

[0051] S1. 4,4'-biphenyl diboronic acid was added to a toluene solvent, stirred and dispersed, and then N-methyl-2-hydroxyethylamine was added thereto, wherein the mass ratio of 4,4'-biphenyl diboronic acid to N-methyl-2-hydroxyethylamine was 1:2.6. The reaction was carried out at 125°C for 14 hours. After the reaction was completed, the reaction was evaporated under reduced pressure, filtered, and dried to obtain Intermediate 1;

[0052] S2. Add intermediate 1 and 2-chloroethyl vinyl ether to N,N-dimethylformamide solvent, stir and disperse, react at 70°C for 14 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 1.2:1:1.1, and react at 85°C for 8 hours. After completion, distill under reduced pressure and filter to obtain olefinated boronic acid;

[0053] S3. 6 parts by weight of graphene oxide were ultrasonically dispersed into 90 parts by weight of thionyl chloride, and after uniform dispersion, the mixture was reacted at 78 ° C. After the reaction, the mixture was filtered, washed, and dried to obtain graphene chloride;

[0054] 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 6 hours, and then distill under reduced pressure and wash to obtain modified boronic acid.

[0055] Comparative Example 1

[0056] This comparative example is different from Example 3 in that no modified boric acid is added.

[0057] Concrete slab crack resistance test: Referring to GB / T 50082-2009, "Test Method for Long-term Properties and Durability of Ordinary Concrete," the water reducer solid content was 0.5%. The cement was PO 42.5, river sand with a fineness modulus within the medium sand range, and the gravel was a continuously graded 1030.5 mm. The admixtures used were a high-efficiency water reducer FDNC (produced by Shandong Wanshan Chemical Co., Ltd.) with a solid content of 40 wt.% and the polycarboxylate water reducer prepared in Example 13, respectively. The test was conducted 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 / m). The test results of the first crack time, maximum crack width, crack area, and 28-day strength are shown in Table 1.

[0058]

[0059] It can be seen from Table 1 that the anti-cracking polycarboxylate water-reducing agent of the present invention has good anti-cracking effect and mechanical properties.

[0060] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A preparation process for a crack-resistant polycarboxylate water-reducing agent, characterized in that: The following steps are involved: (1) dissolving isopentanol polyoxyethylene ether in deionized water and stirring uniformly to obtain solution A; (2) dissolving acrylic acid in deionized water and stirring uniformly to obtain solution B; (3) dissolving 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 stirring uniformly to obtain solutions C, D, and E, respectively; (4) adding 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 adding 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 adding 40-60 parts by weight of solution B dropwise thereto; after the dropwise addition is completed, reacting at 40-60° C. for 2-6 hours, cooling the product to room temperature, and then adjusting the pH value to neutral with alkali solution to obtain an anti-cracking polycarboxylate water reducer; The preparation method of the modified boric acid in (4) is: S1. Add 4,4'-biphenyldiboronic acid to toluene solvent, stir and disperse, then add N-methyl-2-hydroxyethylamine, react at 110-135°C for 12-15 hours. After the reaction is complete, 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 12-16 hours, then continue to add sodium 3-chloro-2-hydroxypropanesulfonate, react at 70-95°C for 6-10 hours, and then distill under reduced pressure and filter to obtain olefinated boronic acid; S3. 4-8 parts by weight of graphene oxide is ultrasonically dispersed into 60-100 parts by weight of thionyl chloride, uniformly dispersed, reacted at 75-80 ° C, filtered after the reaction, washed, and dried to obtain graphene chloride; S4. Add olefinated boronic acid and graphene chloride to N,N-dimethylformamide solvent, stir evenly, continue to add triethylamine catalyst, stir and react at 50-80°C for 4-7 hours, and then distill under reduced pressure and wash to obtain modified boronic acid.

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

8.

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

2.

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

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