Composite functional polycarboxylate superplasticizer with high synthesis conversion rate and preparation method thereof

Abstract

The invention relates to the technical field of building materials, in particular to a composite functional polycarboxylate superplasticizer with high synthesis conversion rate and a preparation method thereof. The molecular structure of the polycarboxylate superplasticizer is optimally designed from an initiation mechanism and raw materials to prepare the polycarboxylate superplasticizer with a novel molecular structure, so that the polycarboxylate superplasticizer has the characteristics of high monomer conversion rate and functional compounding; therefore, the product energy efficiency is improved, and the common problems of poor adaptability to concrete materials, sensitivity to the mixing amount and the like of the conventional polycarboxylate superplasticizer product at present are solved. Unsaturated functional active monomers containing structures such as carboxyl, carboxylate group, hydroxyl, double benzene rings, phosphate group, amide group, disilane and sulfonic acid group are introduced in molecular synthesis of the polycarboxylate superplasticizer, so that the synergistic effect of the monomers is fully exerted, and the multifunctional composite effect of the polycarboxylate superplasticizer is realized.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a composite functional polycarboxylate water-reducing agent with high synthesis conversion rate and a preparation method thereof. Background Art

[0002] Polycarboxylate water reducers are widely used in construction engineering fields represented by commercial concrete because of their high water reduction rate, strong slump retention ability, simple process, safe and environmentally friendly production process, etc. At present, the mainstream polycarboxylate water reducer products in the market are usually polymer solutions prepared by free radical copolymerization of terminal olefinic alkane macromonomers with terminal double bonds and unsaturated functional small monomers through an oxidation-reduction initiation system in aqueous solution. As an aqueous solution homogeneous polymerization system, the raw materials and polymerization products synthesized by polycarboxylate water reducers generally have good water solubility, which is conducive to heat conduction and full mixing, thereby avoiding local overheating of the reaction to produce gel and ensuring the homogeneity and quality stability of polycarboxylate water reducer products.

[0003] However, in order to reduce the adverse effects of excessive system viscosity on equipment operation, production efficiency and product quality, the theoretical solid content of the water-reducing mother liquor product designed in the conventional polycarboxylic acid water-reducing agent preparation process is generally ≤50%, which greatly limits the production efficiency of the synthesis equipment. Therefore, under the condition of limited solid content of the water-reducing mother liquor product, improving the conversion rate of the reaction monomer to prepare a polycarboxylic acid water-reducing agent with a high synthesis conversion rate, and then increasing the content of active ingredients in the polycarboxylic acid water-reducing agent product, has become one of the important research and development paths for various admixture manufacturers to achieve cost reduction and efficiency improvement and improve product cost performance.

[0004] In addition, as fluctuations in the quality of concrete raw materials become increasingly normal, conventional polycarboxylic acid water-reducing agent products are often more prone to common problems such as poor adaptability to concrete materials and sensitivity to dosage due to their single functionality, making it increasingly difficult to meet the demands for concrete working performance during actual construction. Summary of the invention

[0005] In order to solve the problems of low conversion rate and single function of polycarboxylate water-reducing agent mentioned in the above background, the present invention provides a composite functional polycarboxylate water-reducing agent with high synthesis conversion rate and a preparation method thereof.

[0006] The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate provided by the present invention comprises, by weight, 210-230 parts of a polyether macromonomer, 20-50 parts of an unsaturated functional monomer mixture, 1.0-2.2 parts of an oxidant, 0.1-0.6 parts of a reducing agent, 0.01-0.5 parts of a polymerization catalyst, 0.5-1.2 parts of a chain transfer agent, 1.5-2.0 parts of a pH regulator and 240-270 parts of deionized water; The polyether macromonomer structural formula is: ; Wherein, R represents a hydroxyl group and n is 20-120.

[0007] On the basis of the above technical solution, further, the unsaturated functional monomer mixture includes, by weight, 10-25 parts of acrylic acid, 2-5 parts of monomethyl maleate, 4-15 parts of methyl methacrylate, 8-14 parts of hydroxypropyl acrylate, 1-3 parts of isomerized dibasic ester, 1-2 parts of disilane-modified dibasic maleamide and 0.5-1.5 parts of 2-acrylamido-2-methylpropanesulfonic acid; The isomerized dibasic ester structural formula is: ; wherein R1 represents one of H, -CH3 and -CH3CH2-; R2 represents one of -CH2CH2-, -CH(CH3)-, -CH2CH2CH2- and -CH(CH3)CH2-; The structural formula of the bisilane-modified dibasic maleamide is: ; Among them, R3 is one of H, -CH3, and -CH3CH2-; R4 is one of H, -CH3, and -CH3CH2-.

[0008] Specifically, the acrylic acid is a carboxyl-containing unsaturated monomer structure, and its function is to exert an adsorption effect on cement particles through the carboxyl group.

[0009] Specifically, the monomethyl maleate, methyl methacrylate, hydroxypropyl acrylate and isomerized dibasic ester are structures of unsaturated monomers containing carboxylic acid ester groups, which can release carboxyl groups through slow hydrolysis of ester groups in an alkaline environment and continuously adsorb cement particles.

[0010] Specifically, the monomethyl maleate also contains a carboxyl group, which functions to cooperate with the acrylic acid monomer to exert an adsorption effect on cement particles.

[0011] Specifically, the hydroxypropyl acrylate also contains a hydroxyl group, which functions to reduce the surface tension of cement particles and exert a penetrating and wetting effect on the cement particles.

[0012] Specifically, the isomerized dibasic ester contains a phosphate group and two benzene ring structures, wherein the phosphate group generated by hydrolysis of the phosphate group can effectively reduce the SO4 2- The competitive attachment of ions inhibits the intercalation adsorption of polycarboxylic acid molecules on soil; the benzene ring can act as a rigid group to effectively inhibit the conformational curling of polycarboxylic acid molecules, which is beneficial to increase the adsorption area on the surface of cement particles.

[0013] Preferably, the isomerized dibasic ester is a combination of 2-hydroxyethyl methacrylate diphenyl phosphate and 3-hydroxypropyl methacrylate diphenyl phosphate.

[0014] More preferably, the mass ratio of 2-hydroxyethyl methacrylate diphenyl phosphate to 3-hydroxypropyl methacrylate diphenyl phosphate is 3:1.

[0015] Specifically, the disilane-modified dimaleamide and 2-acrylamide-2-methylpropanesulfonic acid are structures containing amide unsaturated monomers, which introduce polycarboxylic acid molecules with both anions and cations and can be adsorbed on mineral surfaces with different charged properties, thereby reducing the sensitivity of the polycarboxylic acid water reducer to concrete raw materials.

[0016] More specifically, the bisilane-modified dimaleamide contains two silane groups at the same time. The silanol generated by the hydrolysis of the alkoxy groups in the silane can form Si-O-Si chemical bonds with the hydroxyl groups on the surface of the cement particles, which is intended to promote the action mode of the polycarboxylic acid molecules on the surface of the calcium silicate hydrate from Ca 2+ The complexation is transformed into a more stable Si-O-Si chemical bond, thereby enhancing the adsorption of the water reducer on cement hydrates and improving the fluidity of the cement paste.

[0017] More specifically, the 2-acrylamido-2-methylpropanesulfonic acid also contains a sulfonic acid group, which serves to improve the adaptability of the polycarboxylic acid molecule to different cements and mineral admixtures.

[0018] On the basis of the above technical solution, further, the polyether macromonomer is a combination of ethylene glycol monovinyl polyethylene glycol ether and 4-hydroxybutyl vinyl polyoxyethylene ether.

[0019] On the basis of the above technical solution, further, the mass ratio of ethylene glycol monovinyl polyethylene glycol ether to 4-hydroxybutyl vinyl polyoxyethylene ether is 5-8:3-5.

[0020] Preferably, the mass ratio of ethylene glycol monovinyl polyethylene glycol ether to 4-hydroxybutyl vinyl polyoxyethylene ether is 7:3.

[0021] More preferably, the Mn of the ethylene glycol monovinyl polyethylene glycol ether is 3000Da, and the double bond retention rate is greater than 95.0%; the Mn of the 4-hydroxybutyl vinyl polyoxyethylene ether is 2000Da, and the double bond retention rate is greater than 95.0%.

[0022] Specifically, the double bond retention rate determines the amount of polyether monomers containing unsaturated double bonds that can participate in the free radical copolymerization reaction, thereby affecting the performance of the synthesized collapse-retaining polycarboxylic acid water-reducing agent.

[0023] On the basis of the above technical solution, further, the bisilane-modified dimaleic amide is prepared by removing one molecule of HCl through a polycondensation reaction between one molecule of monomer A and two molecules of γ-aminopropyltriethoxysilane; The structural formula of the monomer A is: ; Among them, R3 is one of H, -CH3, and -CH3CH2-; R4 is one of H, -CH3, and -CH3CH2-.

[0024] Preferably, the disilane-modified dimaleamide is a condensation product of one molecule of maleic acid chloride and two molecules of γ-aminopropyltriethoxysilane.

[0025] On the basis of the above technical solution, further, the oxidant is a hydrogen peroxide solution with a mass fraction of 25%-35%.

[0026] Preferably, the mass fraction of the hydrogen peroxide solution is 31.5%.

[0027] On the basis of the above technical solution, further, the reducing agent is a combination of sodium bisulfite and sodium formaldehyde sulfoxylate, wherein the mass ratio of sodium bisulfite to sodium formaldehyde sulfoxylate is 1:5-10.

[0028] On the basis of the above technical solution, further, the polymerization agent is one of FeSO4·7H2O, NiSO4·6H2O and ZnSO4, and the transition metal ions (Fe 2+ 、Ni 2+ 、Zn 2+ ) can catalyze the free radical copolymerization reaction of the oxidation-reduction initiation system to achieve the purpose of improving the monomer conversion rate.

[0029] Specifically, transition metal ions (Fe 2+ 、Ni 2+ 、Zn 2+ ) can coordinate with the carboxyl group (-COO-) contained in acrylic acid, so that the conjugated electron cloud of the carbon-carbon double bond in the monomer shifts to the carbonyl carbon, the original conjugation effect energy increases, the double bond activity is enhanced, the polymerization reaction barrier is reduced, and the monomer conversion rate is improved; The reaction formula is: ; Where M represents the transition metal ion Fe 2+ 、Ni 2+ 、Zn 2+ One of them.

[0030] More preferably, the polymerization catalyst is FeSO4·7H2O, the Fe 2+It can accelerate the initiation rate of the polymerization reaction, thereby achieving the purpose of optimizing the molecular structure of the polycarboxylic acid, which is manifested in that the synthesized polycarboxylic acid water reducer has a lower molecular weight and a more uniform molecular weight distribution.

[0031] More preferably, the purity of the FeSO4·7H2O is ≥99.7%.

[0032] Specifically, Fe 2+ The principle of accelerating the polymerization initiation rate is: when H2O2 is used as the oxidant of the free copolymerization oxidation-reduction initiation system, Fe 2+ Will react with H2O2, where Fe 2+ Transformed into strong oxidizing Fe 3+ , H2O2 decomposes into highly reactive hydroxyl radicals, which are continuously consumed in the reaction; Fe 3+ Reaction with reducing agent to regenerate Fe 2+ It interacts with H2O2 again to form a Fenton-like cycle until H2O2 is completely decomposed; The reaction formula is as follows: .

[0033] On the basis of the above technical solution, further, the chain transfer agent is mercaptopropionic acid; the pH adjuster is solid flake caustic soda with a mass fraction of ≥98%.

[0034] On the basis of the above technical solution, further, the solid content of the composite functional polycarboxylate water-reducing agent with high synthesis conversion rate is 50%-52%.

[0035] The present invention also provides a method for preparing any of the above-mentioned composite functional polycarboxylate water-reducing agents with high synthesis conversion rate, comprising the following steps: S1. Add polyether macromonomer, polymerization reaction catalyst and deionized water into a synthesis reactor, stir and dissolve them thoroughly to prepare a mixed solution A, wherein the mass ratio of the total amount of polyether macromonomer and polymerization reaction catalyst to deionized water is 1:1-1.5; S2, dissolving an unsaturated functional monomer mixture of acrylic acid, monomethyl maleate, methyl methacrylate, hydroxypropyl acrylate, isomerized dibasic ester, disilane-modified dimaleamide and 2-acrylamide-2-methylpropanesulfonic acid in deionized water and stirring well to prepare a mixed solution B, wherein the mass ratio of the unsaturated functional monomer mixture to deionized water is 1:0.3-0.4; S3, dissolving the reducing agent and the chain transfer agent in deionized water and stirring them thoroughly to prepare a mixed solution C, wherein the mass ratio of the total amount of the reducing agent and the chain transfer agent to the deionized water is 1:30-36; S4, adding mixed solution A and oxidant into the reaction vessel, and then using an automatic dropping device to uniformly and slowly add the prepared mixed solution B and mixed solution C, the dropping time is 1.0-1.5h, and the reaction temperature is constant at 25±5°C; S5. After the addition is completed, keep warm for 1 hour, add water and use caustic soda to adjust the pH value to 5.5-6.0.

[0036] Compared with the prior art, the present invention provides a composite functional polycarboxylate water-reducing agent with a high synthesis conversion rate and a preparation method thereof, which optimizes the molecular structure of the polycarboxylate water-reducing agent from the perspective of the initiation mechanism and raw materials to prepare a polycarboxylate water-reducing agent with a new molecular structure, so that it has the characteristics of high monomer conversion rate and composite functions, thereby improving the energy efficiency of the product and solving the common problems of current conventional polycarboxylate water-reducing agent products, such as poor adaptability to concrete materials and sensitivity to dosage.

[0037] In the preferred embodiment, unsaturated functional active monomers containing structures such as carboxyl, carboxylate, hydroxyl, biphenyl ring, phosphate, amide, disilane, sulfonic acid and the like are introduced into the molecular synthesis of the polycarboxylate water-reducing agent to give full play to the synergistic effect of the monomers and realize the multi-functional composite effect of the polycarboxylate water-reducing agent.

[0038] In a preferred embodiment, the transition metal ion Fe generated by the hydrolysis of the polymerization catalyst 2+ 、Ni 2+ and Zn 2+ , which can catalyze the free radical copolymerization reaction under the oxidation-reduction initiation system, coordinate with the carboxyl group (-COO-) contained in the unsaturated functional small monomer, so that the conjugated electron cloud of the carbon-carbon double bond in the monomer shifts to the carbonyl carbon, the original conjugation effect energy increases, the double bond activity is enhanced, and the polymerization reaction barrier is reduced, thereby achieving the purpose of improving the monomer conversion rate. In a more preferred embodiment, FeSO4·7H2O is used as a polymerization catalyst, which can be introduced into the free copolymerization oxidation-reduction initiation system with H2O2 as an oxidant. 2+ The purpose of accelerating the polymerization initiation rate and optimizing the molecular structure of polycarboxylic acid is to form a Fenton-like cycle.

[0039] In the preferred embodiment, the isomerized dibasic ester contains a carboxylate group, a phosphate group and two benzene ring structures at the same time. The carboxylate group provides protection through the carboxyl group; the phosphate group generated by the hydrolysis of the phosphate group can effectively reduce the SO4 2- The competitive attachment of ions inhibits the intercalation adsorption of polycarboxylic acid molecules on soil; the benzene ring can act as a rigid group to effectively inhibit the conformational curling of polycarboxylic acid molecules, which is beneficial to increase the adsorption area on the surface of cement particles.

[0040] In the preferred embodiment, the bisilane-modified dimaleic acid amide contains two amide groups and two silane groups at the same time. The introduction of the amide groups makes the polycarboxylic acid molecules have both anions and cations, and can be adsorbed on the surfaces of minerals with different electrical properties, thereby reducing the sensitivity of the polycarboxylic acid water reducer to concrete raw materials; the silanol generated by the hydrolysis of the alkoxy groups in the silane groups can form Si-O-Si chemical bonds with the hydroxyl groups on the surface of cement particles, and the introduction of the silanol groups can promote the action mode of the polycarboxylic acid molecules on the surface of calcium silicate hydrate from Ca to Si. 2+ The complexation is transformed into a more stable Si-O-Si chemical bond, thereby enhancing the adsorption of the water reducer on cement hydrates and improving the fluidity of the cement paste. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The present invention also provides a preparation example of a composite functional polycarboxylate water-reducing agent having a high synthesis conversion rate as shown below: Example 1 The raw materials include, by weight: 210 parts of polyether macromonomer, 42 parts of unsaturated functional monomer, 2.0 parts of oxidant, 0.3 parts of reducing agent, 0.02 parts of polymerization catalyst, 1.0 parts of chain transfer agent, 1.6 parts of flake caustic soda and 250 parts of deionized water.

[0043] The polyether macromonomers were all purchased from Sichuan Aoke Chemical Co., Ltd., and the double bond retention rate was ≥95%.

[0044] The unsaturated functional monomer mixture comprises, by weight: 20 parts of acrylic acid, 2 parts of monomethyl maleate, 4 parts of methyl methacrylate, 12 parts of hydroxypropyl acrylate, 1.5 parts of isomerized dibasic ester, 2 parts of disilane-modified dimaleamide and 0.5 parts of 2-acrylamido-2-methylpropanesulfonic acid.

[0045] The oxidant is a hydrogen peroxide solution with a mass fraction of 31.5%.

[0046] The reducing agent is a combination of sodium bisulfite and sodium formaldehyde sulfoxylate, wherein the mass ratio of sodium bisulfite to sodium formaldehyde sulfoxylate is 1:5.

[0047] The polymerization reaction catalyst is FeSO4·7H2O, and the purity is ≥99.7%.

[0048] The chain transfer agent is mercaptopropionic acid.

[0049] The pH regulator is solid caustic soda flakes with a mass fraction of ≥98%.

[0050] Example 1 The preparation process is as follows: S1. Add ethylene glycol monovinyl polyoxyethylene ether, polymerization reaction catalyst and deionized water into a synthesis reactor, stir and dissolve them thoroughly to prepare a mixed solution A, wherein the mass ratio of the total amount of ethylene glycol monovinyl polyoxyethylene ether and polymerization reaction catalyst to deionized water is 1:1.2; S2, dissolving the unsaturated functional monomer mixture in deionized water and stirring thoroughly to prepare a mixed solution B, wherein the mass ratio of the unsaturated functional monomer mixture to deionized water is 1:0.5; S3, dissolving the reducing agent and the chain transfer agent in deionized water and stirring them thoroughly to prepare a mixed solution C, wherein the mass ratio of the total amount of the reducing agent and the chain transfer agent to the deionized water is 1:33; S4, adding mixed solution A and oxidant into the reaction vessel, and then using an automatic dropping device to uniformly and slowly add the prepared mixed solution B and mixed solution C, the dropping time is 1.25h, and the reaction temperature is constant at 25°C; S5. After the addition is completed, keep warm for 1 hour, add water and use caustic soda to adjust the pH value to 5.5-6.0.

[0051] Example 2 The raw materials include, by weight: 220 parts of polyether macromonomer, 40 parts of unsaturated functional monomer, 1.8 parts of oxidant, 0.32 parts of reducing agent, 0.25 parts of polymerization catalyst, 0.8 parts of chain transfer agent, 1.6 parts of caustic soda flakes and 260 parts of deionized water.

[0052] The composition of the unsaturated functional monomer mixture is the same as that of Example 1.

[0053] The oxidant is a hydrogen peroxide solution with a mass fraction of 31.5%.

[0054] The reducing agent is a combination of sodium bisulfite and sodium formaldehyde sulfoxylate, wherein the mass ratio of sodium bisulfite to sodium formaldehyde sulfoxylate is 1:8.

[0055] The polymerization reaction catalyst is NiSO4·6H2O, and the purity is ≥99.7%.

[0056] The chain transfer agent is mercaptopropionic acid.

[0057] The pH regulator is solid caustic soda flakes with a mass fraction of ≥98%.

[0058] Example 2 The preparation process is as follows: S1. Add ethylene glycol monovinyl polyoxyethylene ether, polymerization reaction catalyst and deionized water into a synthesis reactor, stir and dissolve them thoroughly to prepare a mixed solution A, wherein the mass ratio of the total amount of ethylene glycol monovinyl polyoxyethylene ether and polymerization reaction catalyst to deionized water is 1:1.35; S2, dissolving the unsaturated functional monomer mixture in deionized water and stirring thoroughly to prepare a mixed solution B, wherein the mass ratio of the unsaturated functional monomer mixture to deionized water is 1:0.35; S3, dissolving the reducing agent and the chain transfer agent in deionized water and stirring them thoroughly to prepare a mixed solution C, wherein the mass ratio of the total amount of the reducing agent and the chain transfer agent to the deionized water is 1:33; S4, adding mixed solution A and oxidant into the reaction vessel, and then using an automatic dropping device to uniformly and slowly add the prepared mixed solution B and mixed solution C, the dropping time is 1.25h, and the reaction temperature is constant at 25°C; S5. After the addition is completed, keep warm for 1 hour, add water and use caustic soda to adjust the pH value to 5.5-6.0.

[0059] Example 3 The raw materials include, by weight: 230 parts of polyether macromonomer, 40 parts of unsaturated functional monomer mixture, 1.5 parts of oxidant, 0.36 parts of reducing agent, 0.40 parts of polymerization catalyst, 0.7 parts of chain transfer agent, 1.6 parts of caustic soda flakes and 270 parts of deionized water.

[0060] The composition of the unsaturated functional monomer mixture is the same as that of Example 1.

[0061] The oxidant is a hydrogen peroxide solution with a mass fraction of 31.5%.

[0062] The reducing agent is a combination of sodium bisulfite and sodium formaldehyde sulfoxylate, wherein the mass ratio of sodium bisulfite to sodium formaldehyde sulfoxylate is 1:10.

[0063] The polymerization reaction catalyst is ZnSO4 with a purity of ≥99.7%.

[0064] The chain transfer agent is mercaptopropionic acid.

[0065] The pH regulator is solid caustic soda flakes with a mass fraction of ≥98%.

[0066] Example 3 The preparation process is as follows: S1. Add ethylene glycol monovinyl polyoxyethylene ether, polymerization reaction catalyst and deionized water into a synthesis reactor, stir and dissolve them thoroughly to prepare a mixed solution A, wherein the mass ratio of the total amount of ethylene glycol monovinyl polyoxyethylene ether and polymerization reaction catalyst to deionized water is 1:1.5; S2, dissolving the unsaturated functional monomer mixture in deionized water and stirring thoroughly to prepare a mixed solution B, wherein the mass ratio of the unsaturated functional monomer mixture to deionized water is 1:0.35; S3, dissolving the reducing agent and the chain transfer agent in deionized water and stirring them thoroughly to prepare a mixed solution C, wherein the mass ratio of the total amount of the reducing agent and the chain transfer agent to the deionized water is 1:33; S4, adding mixed solution A and oxidant into the reaction vessel, and then using an automatic dropping device to uniformly and slowly add the prepared mixed solution B and mixed solution C, the dropping time is 1.25h, and the reaction temperature is constant at 25°C; S5. After the addition is completed, keep warm for 1 hour, add water and use caustic soda to adjust the pH value to 5.5-6.0.

[0067] Example 4 The difference between Example 4 and Example 1 is that the copolymerization reaction temperature in the preparation method S4 is kept constant at 20° C., and the remaining operations and steps are the same as those in Example 1.

[0068] Example 5 The difference between Example 5 and Example 1 is that the copolymerization reaction temperature in the preparation method S4 is kept constant at 30° C., and the other operations and steps are the same as those in Example 1.

[0069] Example 6 The difference between Example 6 and Example 1 is that the reaction dropwise addition time in preparation method S4 is 1.0 h, and the other operations and steps are the same as those in Example 1.

[0070] Example 7 The difference between Example 6 and Example 1 is that the reaction dropwise addition time in preparation method S4 is 1.5 h, and the other operations and steps are the same as those in Example 1.

[0071] Comparative Example 1 Comparative Example 1 is a conventional commercially available comprehensive polycarboxylate water-reducing agent, which is prepared by copolymerization of a polyether macromonomer and acrylic acid, and has an actual solid content of 51%. The raw materials, by weight, include: 220 parts of ethylene glycol monovinyl polyoxyethylene ether, 20 parts of acrylic acid, 1.6 parts of an oxidant, 0.5 parts of a reducing agent, 0.05 parts of a polymerization catalyst, 1.2 parts of a chain transfer agent, 1.4 parts of caustic soda flakes, and 240 parts of deionized water.

[0072] The ethylene glycol monovinyl polyoxyethylene ether was purchased from Sichuan Aoke Chemical Co., Ltd., with Mn=3000Da and a double bond retention rate of 97.13%.

[0073] The oxidant is a hydrogen peroxide solution with a mass fraction of 31.5%.

[0074] The reducing agent is a combination of L-ascorbic acid and sodium formaldehyde sulfoxylate, wherein the mass ratio of L-ascorbic acid to sodium formaldehyde sulfoxylate is 1:4.

[0075] The polymerization reaction catalyst is FeSO4·7H2O, and the purity is ≥99.7%.

[0076] The chain transfer agent is thioglycolic acid.

[0077] The pH regulator is solid caustic soda flakes with a mass fraction of ≥98%.

[0078] Comparative Example 1 The preparation process of conventional polycarboxylate water-reducing agent comprises the following steps: S1. Add ethylene glycol monovinyl polyoxyethylene ether, polymerization reaction catalyst and deionized water into a synthesis reactor, stir and dissolve them thoroughly to prepare a mixed solution A, wherein the mass ratio of the total amount of ethylene glycol monovinyl polyoxyethylene ether and polymerization reaction catalyst to deionized water is 1:1.8; S2, dissolving the unsaturated functional monomer mixture in deionized water and stirring thoroughly to prepare a mixed solution B, wherein the mass ratio of the unsaturated functional monomer mixture to deionized water is 1:0.3; S3, dissolving the reducing agent and the chain transfer agent in deionized water and stirring them thoroughly to prepare a mixed solution C, wherein the mass ratio of the total amount of the reducing agent and the chain transfer agent to the deionized water is 1:35; S4, adding mixed solution A and oxidant into the reaction vessel, and then using an automatic dropping device to uniformly and slowly add the prepared mixed solution B and mixed solution C, the dropping time is 1.25h, and the reaction temperature is constant at 35°C; S5. After the addition is completed, keep warm for 1 hour, add water and use caustic soda to adjust the pH value to 5.5.

[0079] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that FeSO4·7H2O is not added to the raw materials, and the remaining operations and steps are the same as those of Example 1.

[0080] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that NiSO4·6H2O is not added to the raw materials, and the remaining operations and steps are the same as those of Example 2.

[0081] Comparative Example 4 The difference between Comparative Example 4 and Example 3 is that ZnSO4 is not added to the raw materials, and the remaining operations and steps are the same as those of Example 3.

[0082] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that no isomerized dibasic ester is added to the raw materials, and the remaining operations and steps are the same as those of Example 1.

[0083] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that no disilane-modified dimaleamide is added to the raw materials, and the remaining operations and steps are the same as those of Example 1.

[0084] Comparative Example 7 The difference between Comparative Example 7 and Example 1 is that 2-acrylamido-2-methylpropanesulfonic acid is not added to the raw materials, and the remaining operations and steps are the same as those of Example 1.

[0085] Experimental test method: The polycarboxylate water-reducing agents prepared in Examples 1-7 and Comparative Examples 1-7 were subjected to monomer conversion rate and polydispersity analysis tests by gel chromatography, and the test results are shown in Table 1. At the same time, the C30 trial concrete performance comparison test was carried out with reference to GB / T 50080-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures" and GB 8076-2008 "Concrete Admixtures", and the concrete mix ratio is shown in Table 2 (the dosage of each component is kg / m 3 ), its working performance is shown in Table 3.

[0086] The raw materials of concrete used in the test are: Cement (C): Jidong P·O42.5 ordinary Portland cement; Fly ash (FA): activity index 79%; Sand 1 (S1): machine-made sand, fineness modulus Mx=2.8, powder content 10.1%, MB value 1.7; Sand 2 (S2): machine-made sand, fineness modulus Mx=2.6, powder content 7.5%, MB value 1.1; Small stone (G1): particle size 5-10 mm; Dashi (G2): particle size 10-25 mm; Mixing water (W): tap water, in accordance with the mixing water requirements specified in JGJ63-2006 "Concrete Water Standard"; Concrete admixture (Ad): solid content 14.8% (compounded by the polycarboxylate water reducer prepared in Examples 1-7 and Comparative Examples 1-7 and the concrete workability regulator and retarder produced by Chongqing Jianyan Kezhijie Building Materials Co., Ltd. in a mass ratio of 11:2:3).

[0087] Table 1 Monomer conversion and polydispersity coefficient sample Monomer conversion rate / % Polydispersity coefficient Example 1 96.4 1.627928 Example 2 92.95 1.72789 Example 3 93.72 1.769388 Example 4 94.89 1.686306 Example 5 92.11 1.679083 Example 6 91.85 1.753434 Example 7 94.94 1.687359 Comparative Example 1 87.58 2.35894 Comparative Example 2 85.71 1.857911 Comparative Example 3 84.69 1.881647 Comparative Example 4 85.83 2.53247 Comparative Example 5 83.75 2.057567 Comparative Example 6 86.35 2.294796 Comparative Example 7 89.44 1.672016 Table 2 Concrete mix ratio (kg / m 3 ) Concrete mix ratio C S1 S2 G1 G2 FA Ad W Mixing ratio 1 330 380 570 230 720 / 5.7 158 Mix ratio 2 330 665 285 230 720 / 6.0 161 Mix ratio 3 270 380 570 230 720 60 6.0 160 Table 3 Concrete working performance

[0088] As can be seen from Table 1, compared with Comparative Examples 1-7, the monomer conversion rate of Examples 1-7 is significantly improved, and the molecular weight distribution is more uniform (the polydispersity coefficient is closer to 1); further comparison between Examples 1-3 and Comparative Examples 2-4 shows that the use of the present invention to provide transition metal ions (Fe 2+ 、Ni 2+ 、Zn 2+ The polymerization catalyst can significantly increase the monomer conversion rate and improve the uniformity of the molecular weight distribution of polycarboxylic acid.

[0089] It can be seen from Table 3 that compared with Comparative Examples 1-7, Examples 1-7 have better water reduction and collapse retention performance.

[0090] Combined with Table 1, the concrete working performance of Examples 1-3 in Table 3 is compared and analyzed. It is found that compared with Examples 2 and 3 using NiSO4·6H2O and ZnSO4 as polymerization reaction catalysts, Example 1 using FeSO4·7H2O as polymerization reaction catalyst has higher monomer conversion rate, lower polydispersity coefficient, better water reduction and slump retention performance, which may be due to the Fe 2+ This is related to the ability to accelerate the polymerization reaction initiation rate, and also indicates that the product process involved in the present invention has strong flexibility.

[0091] By comparing and analyzing the concrete working performance of Example 1, Example 4-5, and Example 6-7 in Table 3 in combination with Table 1, it can be found that different reaction temperatures (20-30°C) and different reaction dropwise addition times (1.0-1.5h) can all be used to stably synthesize a composite functional polycarboxylate water-reducing agent with a high synthesis conversion rate.

[0092] By comparing and analyzing the concrete working performance of Examples 1-7 and Comparative Examples 1-7 in Table 3 in combination with Table 2, it can be found that when the concrete mix ratio is adjusted (i.e., the sand ratio and cementitious material composition in the concrete are changed) to conduct concrete tests, compared with the comparative examples, the working performance of the embodiments is stable when the raw materials of the concrete fluctuate significantly, and the adaptability to the raw materials of the concrete is good, which is mainly manifested in that the mixing amount, water consumption, sand powder content and cementitious material changes are not sensitive.

[0093] In summary, the derivative product of the present invention can be prepared at room temperature and the process is relatively stable. It can effectively solve the common problems of conventional polycarboxylate water-reducing agent products such as poor adaptability to concrete materials and sensitivity to dosage, and has potential promotion value.

[0094] Although the terms such as polycarboxylate water-reducing agent, oxidant and reducing agent are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 invention.

Claims

1. A composite functional polycarboxylate water reducer with high synthesis conversion rate, characterized in that: In parts by weight, it comprises 210-230 parts of polyether macromonomer, 20-50 parts of unsaturated functional monomer mixture, 1.0-2.2 parts of oxidant, 0.1-0.6 parts of reducing agent, 0.01-0.5 parts of polymerization catalyst, 0.5-1.2 parts of chain transfer agent, 1.5-2.0 parts of pH regulator and 240-270 parts of deionized water; The polyether macromonomer structural formula is: ; Wherein, R represents a hydroxyl group and n is 20-120.

2. The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate according to claim 1, characterized in that: In parts by weight, the unsaturated functional monomer mixture includes 10-25 parts of acrylic acid, 2-5 parts of monomethyl maleate, 4-15 parts of methyl methacrylate, 8-14 parts of hydroxypropyl acrylate, 1-3 parts of isomerized dibasic ester, 1-2 parts of disilane-modified dibasic maleamide and 0.5-1.5 parts of 2-acrylamido-2-methylpropanesulfonic acid; The isomerized dibasic ester structural formula is: ; wherein R1 represents one of H, -CH3 and -CH3CH2-; R2 represents one of -CH2CH2-, -CH(CH3)-, -CH2CH2CH2- and -CH(CH3)CH2-; The structural formula of the bisilane-modified dibasic maleamide is: ; Among them, R3 is one of H, -CH3, and -CH3CH2-; R4 is one of H, -CH3, and -CH3CH2-.

3. The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate according to claim 1, characterized in that: The polyether macromonomer is a combination of ethylene glycol monovinyl polyethylene glycol ether and 4-hydroxybutyl vinyl polyoxyethylene ether.

4. The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate according to claim 3, characterized in that: The mass ratio of the ethylene glycol monovinyl polyethylene glycol ether to the 4-hydroxybutyl vinyl polyoxyethylene ether is 5-8:3-5.

5. The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate according to claim 2, characterized in that: The bisilane-modified dimaleic acid amide is prepared by removing one molecule of HCl through a polycondensation reaction between one molecule of monomer A and two molecules of γ-aminopropyltriethoxysilane; The structural formula of the monomer A is: ; Among them, R3 is one of H, -CH3, and -CH3CH2-; R4 is one of H, -CH3, and -CH3CH2-.

6. The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate according to claim 1, characterized in that: The reducing agent is a combination of sodium bisulfite and sodium formaldehyde sulfoxylate, wherein the mass ratio of sodium bisulfite to sodium formaldehyde sulfoxylate is 1:5-10.

7. The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate according to claim 1, characterized in that: The polymerization reaction catalyst is one of FeSO4·7H2O, NiSO4·6H2O and ZnSO4.

8. The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate according to claim 1, characterized in that: The oxidant is a hydrogen peroxide solution with a mass fraction of 25%-35%; the chain transfer agent is mercaptopropionic acid; and the pH regulator is a solid flake caustic soda with a mass fraction of ≥98%.

9. The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate according to claim 1, characterized in that: The composite functional polycarboxylate water-reducing agent with high synthesis conversion rate has a solid content of 50%-52%.

10. A method for preparing a composite functional polycarboxylate water-reducing agent with a high synthetic conversion rate according to any one of claims 1 to 10, characterized in that: The following steps are involved: S1. Add polyether macromonomer, polymerization reaction catalyst and deionized water into a synthesis reactor, stir and dissolve them thoroughly to prepare a mixed solution A, wherein the mass ratio of the total amount of polyether macromonomer and polymerization reaction catalyst to deionized water is 1:1-1.5; S2, dissolving an unsaturated functional monomer mixture of acrylic acid, monomethyl maleate, methyl methacrylate, hydroxypropyl acrylate, isomerized dibasic ester, disilane-modified dimaleamide and 2-acrylamide-2-methylpropanesulfonic acid in deionized water and stirring well to prepare a mixed solution B, wherein the mass ratio of the unsaturated functional monomer mixture to deionized water is 1:0.3-0.4; S3, dissolving the reducing agent and the chain transfer agent in deionized water and stirring them thoroughly to prepare a mixed solution C, wherein the mass ratio of the total amount of the reducing agent and the chain transfer agent to the deionized water is 1:30-36; S4, adding mixed solution A and oxidant into the reaction vessel, and then using an automatic dropping device to uniformly and slowly add the prepared mixed solution B and mixed solution C, the dropping time is 1.0-1.5h, and the reaction temperature is constant at 25±5°C; S5. After the addition is completed, keep warm for 1 hour, add water and use caustic soda to adjust the pH value to 5.5-6.0.

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