Super-retarding ester polycarboxylic acid water reducer and preparation method thereof

Abstract

The invention relates to the technical field of concrete admixtures, in particular to a super-retarding ester polycarboxylic acid water reducer and a preparation method thereof. The super-retarding ester polycarboxylic acid water reducing agent is formed by polymerizing a comonomer under the action of an initiator, a chain transfer agent and an emulsifier, the comonomer comprises an ester macromonomer, polyoxyalkyl ether containing an ester group and a rigid benzene ring structure, an ester micromonomer and unsaturated acid. The super-retarding ester polycarboxylic acid water reducer can effectively improve the initial dispersing performance and slump retaining performance of concrete, improve the strength of the concrete and reduce the sensitivity of the concrete, and has a good long-acting slump retaining effect. And the super-retarding type ester polycarboxylic acid water reducer can be prepared through reaction at normal temperature, the reaction condition is mild, and energy is effectively saved.

Description

Technical Field

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

[0002] As the demand for high-performance concrete in the construction industry continues to increase, traditional water reducers can no longer meet the requirements of modern engineering. Polycarboxylate water reducers have become the preferred high-performance concrete admixture in today's construction industry due to their high water reduction and high slump retention performance. However, some water reducers in the prior art cannot maintain good slump retention performance while providing good water reduction effects. Therefore, it is particularly important to develop a polycarboxylate water reducer with long slump retention that can slowly release carboxyl groups and maintain good concrete construction performance.

[0003] During the synthesis of polycarboxylic acid water-reducing agent, the reactivity of polyether macromonomer determines the reaction temperature of polycarboxylic acid water-reducing agent. 4-carbon and 5-carbon type water-reducing agents (synthesized using 4-carbon or 5-carbon terminal olefin initiators) are the current mainstream polycarboxylic acid water-reducing agents, accounting for a high proportion, but their reaction temperature is as high as 60°C, requiring heating equipment. 2+2 and 2+4 type water-reducing agents are also recognized by the current market due to their short reaction time, excellent water reduction rate and collapse retention performance, but their macromonomer reactivity is high and requires low-temperature equipment. Both have high production costs and do not meet the requirements of energy conservation and environmental protection. It is of great significance to develop a polycarboxylic acid water-reducing agent that can be synthesized at room temperature.

[0004] For example, the Chinese invention patent application with publication number CN 118580021 A discloses a method for synthesizing an isopentanol polyoxyethylene ether water reducer, which requires high temperature preparation and consumes a lot of energy. The Chinese invention patent application with publication number CN118620143A discloses a long-acting collapse-preserving polycarboxylic acid high-performance water reducer and its preparation method, which introduces a comb-type structure but does not present a step-hydrolysis ester group, and its collapse-preserving performance is less stable. Summary of the invention

[0005] In order to solve the shortcomings of the existing polycarboxylate water reducer mentioned in the above background technology, the present application provides a super slow-setting ester polycarboxylate water reducer, and its technical solution is as follows: The super slow-setting ester polycarboxylate water-reducing agent provided in the present application is prepared by polymerization of comonomers under the action of an initiator, a chain transfer agent, and an emulsifier; the comonomers include ester macromonomers, polyoxyalkyl ethers containing ester groups and rigid benzene ring structures, ester micromonomers, and unsaturated acids; wherein the structural formula of the polyoxyalkyl ethers containing ester groups and rigid benzene ring structures is as follows: , Wherein, R1 is an alkylene group having 1 or 2 carbon atoms; N1 is an epoxyalkyl group containing an ester group and a rigid benzene ring structure; The structural formula of the ester small monomer is as follows: , wherein R2 is an alkylene group having 1 to 5 carbon atoms.

[0006] In some embodiments, the structure of N1 is as follows: ,or ; Among them, n is 4 to 18.

[0007] In some embodiments, the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure is prepared by ring-opening polymerization of an unsaturated alcohol and an epoxy ester compound under the action of a catalyst; wherein the unsaturated alcohol is diethylene glycol monoallyl ether or diethylene glycol monovinyl ether; the epoxy ester compound is 2,3-epoxypropyl benzoate or 3,3-diphenyl-2,3-epoxypropionic acid methyl ester; the molar ratio of the unsaturated alcohol to the epoxy ester compound is 1:(6-18); the ring-opening polymerization reaction temperature is 100°C-180°C, the reaction time is 4-6h, and the reaction pressure is 0.3Mpa-0.5Mpa.

[0008] The structural formula of 2,3-epoxypropyl benzoate is:

[0009] The structure of methyl 3,3-diphenyl-2,3-epoxypropionate is: .

[0010] In some embodiments, the catalyst is one or more combinations of potassium hydroxide, sodium ethoxide, sodium hydride, potassium hydride, and potassium hydroxide.

[0011] In some embodiments, the mass ratio of the ester small monomer, the ester macromonomer, the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure, and the unsaturated acid is (1.8-6):100:(10-16):(4-13); the polymerization reaction temperature is 25°C-35°C, and the reaction time is 0.5h-1.5h.

[0012] In some embodiments, the ester macromonomer is one or more combinations of polyethylene glycol dimethacrylate with a molecular weight of 1500-5000, polyethylene glycol monomethyl ether acrylate with a molecular weight of 1500-5000, polyethylene glycol acrylate with a molecular weight of 1500-5000, polyethylene glycol monomethoxy ether monoacrylate with a molecular weight of 1500-5000, and polyethylene glycol monomethoxy ether monomethacrylate with a molecular weight of 1500-5000.

[0013] In some embodiments, the unsaturated acid is one or more of acrylic acid, methacrylic acid, and maleic acid.

[0014] In some embodiments, the initiator includes an oxidant and a reductant; the oxidant is one or more combinations of potassium persulfate, hydrogen peroxide, and 2,5-dimethyl-2,5-bis(hydroperoxide)hexane; the reductant is one or more combinations of sodium hypophosphite, sodium sulfite, ferrous sulfate, and potassium thiosulfate; the chain transfer agent is one or more combinations of thioglycolic acid, 2-hydroxypropyl mercaptan, 2-mercaptosuccinic acid, and sodium hypophosphite; the emulsifier is one or more combinations of sorbitan polyoxyethylene ether tetraoleate and stearic acid polyoxyethylene ester.

[0015] In some embodiments, the amount of the oxidant is 1% to 2.5% of the total mass of the ester macromonomer, the amount of the reducing agent is 0.8% to 2.8% of the total mass of the ester macromonomer, the amount of the chain transfer agent is 0.5% to 2% of the total mass of the ester macromonomer; and the amount of the emulsifier is 1% to 4% of the total mass of the ester macromonomer.

[0016] The present application also provides a method for preparing the super-slow-setting ester polycarboxylate water-reducing agent as described above, which comprises the following preparation steps: mixing the ester small monomer, the ester large monomer and the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure, adding an initiator solution, a chain transfer agent solution, an emulsifier solution and an unsaturated acid at 25°C to 35°C to carry out a polymerization reaction, and the addition time is 0.5h to 1.5h; then keeping the temperature for a certain period of time, adjusting the pH, and obtaining the super-slow-setting ester polycarboxylate water-reducing agent.

[0017] Compared with the prior art, this application has the following beneficial effects: The present application provides a super-slow-setting ester polycarboxylate water reducer, which provides a more three-dimensional adsorption effect due to the introduction of a slow-release group on its side chain. The ester side chain slowly releases the adsorption group, provides a long-term slump-retaining effect, and can improve the later strength of concrete. The super-slow-setting ester polycarboxylate water reducer can effectively improve the initial dispersion performance and slump-retaining performance of concrete, improve the strength of concrete, and reduce the sensitivity of concrete, and has a good long-term slump-retaining effect. In addition, the super-slow-setting ester polycarboxylate water reducer can be prepared by reaction at room temperature, the reaction conditions are mild, and energy is effectively saved. DETAILED DESCRIPTION

[0018] 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.

[0019] The present application also provides the following embodiments and comparative examples: Example 1 (1) Preparation of polyoxyalkyl ethers containing ester groups and rigid benzene ring structures: In a 3L stainless steel high-pressure reactor, add 29.2 parts of diethylene glycol monoallyl ether and 1.7 parts of sodium ethoxide by weight and stir evenly; evacuate the reactor and replace it with N2 4 times. Heat the reactor to 90°C, and continuously add 213.8 parts of 2,3-epoxypropyl benzoate to the reactor. Control the reaction temperature to 110°C and the reaction pressure to 0.5Mpa. The reaction time is 5.5h. After the product is cooled, add a neutralizer and collect the product; (2) Copolymerization reaction: first, by weight, add 4 parts of diethyl 2-(4-pentene)malonate, 12 parts of polyoxyalkylene polyether containing an ester group and a rigid benzene ring structure, 100 parts of polyethylene glycol acrylate, 2.8 parts of sodium hypophosphite solution, 1 part of sorbitan polyoxyethylene ether tetraoleate and 68.2 parts of water into a first reaction container and stir evenly; 1 part of hydrogen peroxide and 20 parts of water are mixed evenly in the first dropping device; 2 parts of thioglycolic acid and 20 parts of water are mixed evenly in the second dropping device; 8 parts of acrylic acid and 20 parts of water are mixed evenly in the third dropping device; At room temperature of 25°C to 35°C, the materials in the first dropping device, the second dropping device and the third dropping device are sequentially added dropwise to the first reaction container, and the materials in the third dropping device, the second dropping device and the first dropping device are added dropwise within 60 minutes, and the reaction is carried out at a constant temperature for 1 hour; Among them, the molecular weight of polyethylene glycol acrylate (where the repeating chain segment is 56) is 2536, and its structural formula is: H2C=CHCO(OCH2CH2) 56 OH.

[0020] (3) Add 10 parts by weight of 32% sodium hydroxide to obtain a super slow-setting ester polycarboxylic acid water reducer with a concentration of 50%.

[0021] Example 2 (1) Preparation of polyoxyalkyl ethers containing ester groups and rigid benzene ring structures: In a 3L stainless steel high-pressure reactor, add 100.2 parts of diethylene glycol monovinyl ether and 1.4 parts of sodium hydride by weight and stir evenly; evacuate the reactor and replace it with N2 four times. Heat the reactor to 140°C, and continuously add 1748.6 parts of 3, 3-diphenyl-2,3-epoxypropionic acid methyl ester to the reactor, control the reaction temperature to 160°C, and the reaction pressure to 0.3Mpa. The reaction time is 4h. After the product is cooled, add a neutralizer and collect the product; (2) Copolymerization reaction: first, by weight, add 6 parts of diethyl 2-(4-propylene)malonate, 14 parts of polyoxyalkylene polyether containing an ester group and a rigid benzene ring structure, 100 parts of polyethylene glycol monomethoxy ether monoacrylate, 1.5 parts of sodium sulfite, 4 parts of polyoxyethylene stearate and 68.8 parts of water into a first reaction container and stir evenly; 2.4 parts of potassium persulfate and 20 parts of water are mixed evenly in the first dropping device; 0.5 parts of 2-hydroxypropanethiol and 20 parts of water are mixed evenly in the second dropping device; 4 parts of methacrylic acid and 20 parts of water are mixed evenly in the third dropping device; At room temperature of 25°C to 35°C, the materials in the first dropping device, the second dropping device and the third dropping device are sequentially added dropwise to the first reaction container. The materials in the third dropping device, the second dropping device and the first dropping device are added dropwise within 75 minutes, and the reaction is carried out at a constant temperature for 1 hour. Wherein, the molecular weight of polyethylene glycol monomethoxy ether monoacrylate is 3000.

[0022] (3) Add 10 parts by weight of 32% sodium hydroxide to obtain the super slow-setting ester polycarboxylic acid water reducer with a concentration of 40%.

[0023] Example 3 (1) Preparation of polyoxyalkyl ethers containing ester groups and rigid benzene ring structures: In a 3L stainless steel high-pressure reactor, add 50.6 parts of diethylene glycol monovinyl ether and 0.9 parts of potassium hydride by weight and stir evenly; evacuate the reactor and replace it with N2 4 times. Heat the reactor to 110°C, and continuously add 1226.4 parts of 2,3-epoxypropyl benzoate to the reactor. Control the reaction temperature to 130°C and the reaction pressure to 0.4Mpa. The reaction time is 4.5h. After the product is cooled, add a neutralizer and collect the product; (2) Copolymerization reaction: first, by weight, add 2 parts of diethyl 2-(4-pentene)malonate, 10 parts of polyoxyalkylene polyether containing an ester group and a rigid benzene ring structure, 100 parts of polyethylene glycol monomethyl ether acrylate, 3 parts of sorbitan polyoxyethylene ether tetraoleate and 66.5 parts of water into a first reaction container and stir evenly; 1.2 parts of 2,5-dimethyl-2,5-bis(hydroperoxide)hexane and 20 parts of water are mixed evenly in the first dropping device; 0.9 parts of potassium thiosulfate, 1 part of sodium hypophosphite and 20 parts of water are mixed evenly in the second dropping device; 12 parts of acrylic acid and 20 parts of water are mixed evenly in the third dropping device; At room temperature of 25°C to 35°C, the materials in the first dropping device, the second dropping device and the third dropping device are sequentially added dropwise to the first reaction container, and the materials in the third dropping device, the second dropping device and the first dropping device are added dropwise within 90 minutes, and the reaction is carried out at a constant temperature for 1 hour; Wherein, the molecular weight of polyethylene glycol monomethyl ether acrylate is 4000.

[0024] (3) Add 10 parts by weight of 32% sodium hydroxide to obtain the super slow-setting ester polycarboxylic acid water reducer with a concentration of 40%.

[0025] Comparative Example 1 (4-Hydroxybutyl Vinyl Ether Substituted for Diethylene Glycol Monoallyl Ether) The only difference from Example 1 is that in the preparation process of the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure in step (1), 4-hydroxybutyl vinyl ether is used in an equal molar amount to replace diethylene glycol monoallyl ether, and the other steps and conditions are the same as those in Example 1.

[0026] Comparative Example 2 (using ethylene glycol monovinyl ether to replace diethylene glycol monoallyl ether in equal moles) The only difference from Example 1 is that in the preparation process of the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure in step (1), ethylene glycol monovinyl ether is used in an equal molar amount to replace diethylene glycol monoallyl ether, and the other steps and conditions are the same as those in Example 1.

[0027] Comparative Example 3 (Polyether macromonomers of equal quality replacing ester macromonomers) The only difference from Example 1 is that in the copolymerization reaction of step (2), a polyether macromonomer TPEG polyether of equal mass is used to replace polyethylene glycol acrylate, and the other steps and conditions are consistent with those of Example 1.

[0028] The molecular weight of the polyether macromonomer TPEG polyether is 2507 (55 repeating segments), and its structural formula is: CH2=CH(CH3)CH2CH2O(CH2CH2O) n H, where n=55.

[0029] Comparative Example 4 (Polyoxyalkyl ether without ester group and rigid benzene ring structure participating in copolymerization reaction) The only difference from Example 1 is that in the copolymerization reaction of step (2), no polyoxyalkyl ether containing an ester group and a rigid benzene ring structure is added to participate in the copolymerization reaction, and the other steps and conditions are consistent with Example 1.

[0030] Comparative Example 5 Commercially available Point-S polycarboxylate water-reducing agent mother liquor and white sugar were selected and mixed in amounts of 0.2% and 0.03% of the cementitious material respectively for concrete verification.

[0031] Comparative Example 6 (No Ester Small Monomer Participates in Copolymerization) The only difference from Example 1 is that no ester small monomer is added in the copolymerization reaction of step (2). The other steps and conditions are the same as those of Example 1.

[0032] Comparative Example 7 (Hydroxyethyl acrylate replaces ester small monomer 2-(4-pentene) diethyl malonate) The only difference from Example 1 is that in the copolymerization reaction of step (2), hydroxyethyl acrylate is used in place of diethyl 2-(4-pentene)malonate. The other steps and conditions are the same as those of Example 1.

[0033] Comparative Example 8 (Methyl 2,3-epoxypropionate substituted for 2,3-epoxypropyl benzoate) The only difference from Example 1 is that in step (1), 2,3-epoxypropionic acid methyl ester is used to replace 2,3-epoxypropyl benzoate in an equal molar amount. The other steps and conditions are the same as those in Example 1.

[0034] Comparative Example 9 (Methyl 6-heptenoate equimolarly replaces diethyl 2-(4-pentene)malonate) The only difference from Example 1 is that in the copolymerization reaction of step (2), methyl 6-heptenoate is used in place of diethyl 2-(4-pentene)malonate. The other steps and conditions are the same as those of Example 1.

[0035] Performance tests of the products of the embodiments and comparative examples: The polycarboxylate water-reducing agent synthesized in the embodiment and the comparative example were compared with the machine-made sand concrete: Conch PO42.5R cement was used, the water-reducing agent dosage of embodiments 1 to 3 was 0.2% (solid content) of the cementitious material, the water-reducing agent dosage of comparative examples 1 to 4 and comparative example 6 was 0.2% (solid content) of the cementitious material, and the dosage of the admixture in comparative example 5 referred to the specific compound formula.

[0036] According to GB 8076-2008 "Concrete Admixtures", the slump and expansion are measured. The concrete standard mix ratio is: cement 285 kg / m 3 、Fly ash 63 kg / m 3 、Mineral powder 60kg / m 3 , machine-made sand 825 kg / m 3 、Stone 1013 kg / m 3, wherein no admixture is added to the benchmark, and Examples 1 to 3 and Comparative Examples 1 to 9 are tested using the benchmark mix ratio, and the concrete test results are shown in Table 1: Table 1

[0037] From the results in Table 1, we can see that: According to the experimental results, it can be found that the product of the present application performs excellently in improving the initial dispersibility and collapse resistance of concrete, while also enhancing the strength of concrete and reducing its sensitivity. In particular, in reducing the loss of slump and expansion of concrete after 4 hours, the effects of Examples 1 to 3 are particularly significant, indicating that the product of the present application has a significant and long-lasting collapse resistance effect.

[0038] It can be seen from Example 1 and Comparative Examples 1-2 that compared with the comparative example of using 4-hydroxybutyl vinyl ether and ethylene glycol monovinyl ether as initiators to prepare polyether macromonomers, the specific structural unsaturated alcohols used in the present application have greatly improved the initial water-reducing performance of concrete.

[0039] By comparing Example 1 with Comparative Examples 1-2, it can be found that compared with the use of 4-hydroxybutyl vinyl ether and ethylene glycol monovinyl ether, the specific structural unsaturated alcohol used in the present application as an initiator can significantly improve the initial water-reducing performance of concrete when preparing polyether macromonomers.

[0040] Comparing Example 1 with Comparative Example 3, compared with the polycarboxylic acid water reducer prepared by copolymerization using 5-carbon polyether, the water reducer prepared by copolymerization using specific ester macromonomers in the present application has greatly improved the 4-hour collapse retention performance.

[0041] By comparing Example 1 with Comparative Example 4, it can be found that if the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure is not used for polymerization, the collapse resistance of the concrete will be reduced, and the strength of the concrete will also be slightly reduced.

[0042] It can be seen from Example 1 and Comparative Example 5 that, compared with the existing method of compounding a water-reducing agent with a retarder, the ester macromonomer, the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure, and the concrete water-reducing agent prepared by introducing an ester monomer provided in the present application not only have better water-reducing performance, but also significantly improve the slump retention performance, and can enhance the early strength of concrete.

[0043] When comparing Example 1 with Comparative Examples 6 and 7, it is obvious that the ester monomer with a specific structure selected in the present application shows a more superior collapse protection performance and the ability to enhance the strength of concrete when no ester monomer is added or other types of ester monomers are used. Specifically, after 2 hours, the ester monomer of the present application can still maintain good workability, while the workability of the other two monomers is poor.

[0044] By comparing and analyzing Example 1 with Comparative Example 8, we found that after hydrolysis, the adsorption groups of the water reducer in Comparative Example 8 were easily shielded by the surrounding long side chain groups, which resulted in a decrease in its adsorption capacity. In the 2-hour and 4-hour slump tests, the results of Comparative Example 8 were lower than those of Example 1.

[0045] By comparing Example 1 with Comparative Example 9, we observed that the slump retention performance of the water reducer of Comparative Example 9 decreased at 2 hours and 4 hours. This may be because the number of adsorption groups formed after hydrolysis is small, and compared with Example 1, its slump retention effect is not obvious.

[0046] The super slow-setting ester polycarboxylate water-reducing agent and its preparation method provided in the present application at least include the following design concepts, action mechanisms and beneficial effects: 1. This application uses unsaturated alcohol diethylene glycol monovinyl ether (carbon structure is 2+2+2) and diethylene glycol monoallyl ether (carbon structure is 3+2+2) to polymerize with 2,3-epoxypropyl benzoate and 3,3-diphenyl-2,3-epoxypropionic acid methyl ester to prepare polyether products. The structure of the polyether product containing ester group and epoxyalkyl group of rigid benzene ring structure is as follows: , Wherein, R1 is an alkylene group having 1 or 2 carbon atoms; the structure of N1 is ,or ; Wherein, n is 4 to 18.

[0047] It can be seen from the above structure that the polyether product introduces multi-segment ester groups, thereby introducing multi-segment ester groups into the water reducer. Therefore, a large number of carboxyl groups can be introduced after hydrolysis, which are adsorbed on the surface of cement particles to delay the dissolution of cement particles. In addition, the chain segments and free calcium ions in the pore solution form complex compounds to delay the formation of a supersaturated solution in the solution. At the same time, ester groups with different hydrolysis rates are introduced, and calcium hydroxide precipitation and ettringite precipitation can also be adsorbed in the pore solution.

[0048] At the same time, the benzene ring on the ester group (in the N1 group) increases the rigidity of the chain segment, and after the ester group is hydrolyzed, the benzene ring or the double benzene ring remains on the side chain structure, increasing the steric hindrance effect of the chain segment, making it less likely for the hydration product to aggregate, further prolonging the hydration time and improving the retarding effect. At the same time, it can also reduce the hydrolysis rate of the ester group, which is conducive to establishing different hydrolysis rates of the ester group in the overall polycarboxylate water reducer. If the structure of the polyether monomer (especially the ester group) does not have a corresponding benzene ring, for example, the structure of N1 adopts the structure without a benzene ring as shown below:

[0049] This will result in the carboxyl group of the adsorption group after hydrolysis having no rigid chain segment support and will be "buried" in other side chains. Due to the shielding effect of other long flexible side chains, its adsorption capacity will be further reduced.

[0050] 2. From the structure of the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure, it can be seen that among the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure participating in the polymerization of the water reducer, the unsaturated alcohol preferably uses a 2+2+2, 3+2+2 carbon structure terminal olefin initiator (diethylene glycol monoallyl ether or diethylene glycol monovinyl ether). Compared with the initiator with low reactivity for synthesizing 2+2 or 2+4 type water reducers, this application does not need to react under low temperature conditions, but can react at room temperature, which plays a role in energy conservation and environmental protection, and caters to the effect of dual carbon emission reduction. Compared with 4-carbon and 5-carbon polycarboxylic acid water reducers, this application does not need to be heated for reaction, which also saves energy.

[0051] Although 1-allyloxypropan-1-ol (carbon structure is 3+3) or 4-(allyloxy)-1-butanol (carbon structure is 3+4) is used as the unsaturated alcohol, that is, terminal olefin initiators with a 3+3 carbon structure or a 3+4 carbon structure can be polymerized at room temperature to obtain polyoxyalkyl ethers containing ester groups and rigid benzene ring structures.

[0052] However, different structures of terminal olefin initiators affect the structure of the final polyoxyalkyl ether. From the structure of the above-mentioned polyoxyalkyl ether containing ester group and rigid benzene ring structure, it can be seen that: compared with the use of 1-allyloxyprop-1-ol (carbon structure is 3+3) or 4-(allyloxy)-1-butanol (carbon structure is 3+4) as terminal olefin initiator, the present application uses diethylene glycol monoallyl ether or diethylene glycol monovinyl ether, that is, 3+2+2 or 2+2+2 structured unsaturated alcohol as terminal olefin initiator, which brings more folding angles to the side chain structure of polycarboxylate water-reducing agent in the pore solution, improves the chain segment flexibility of polycarboxylate water-reducing agent, makes it easier to adsorb active sites of cement particles and hydration products, and further improves the subsequent slump retention performance. At the same time, diethylene glycol monoallyl ether or diethylene glycol monovinyl ether has high activity, which shortens the reaction time of the copolymerization reaction and increases the solid content of the final polycarboxylic acid water-reducing agent product, so that industrial production improves production efficiency and saves energy, thereby saving energy and improving synthesis efficiency for subsequent industrial applications.

[0053] 3. This application introduces diester groups on the main chain of polycarboxylic acid water-reducing agent by introducing diester-based ester small monomers (the specific ester-based small monomers involved in the polymerization are an olefin-coordinated diester-based structure). After hydration to an alkaline environment, more carboxyl groups can be released, which is beneficial to the adsorption of polycarboxylic acid chain segments and improves the slow setting and slump-preserving effects. At the same time, under the alkaline conditions of cement, effective adsorption prevents excessive consumption of free water content in the pore solution of the polycarboxylic acid water-reducing agent, further improves the steric hindrance effect of the polyether fragment and the rigid benzene ring structure, and plays a role in continuously maintaining the slump. When the ester group is hydrolyzed, the carboxylate radical is released, which adsorbs calcium ions and the surface of cement particles or hydration products, further reduces the calcium ion concentration of the solution, covers the nucleation sites of the hydration products, prolongs the nucleation time of the hydration products, inhibits the growth of Ca(OH)2 and AFt crystal nuclei, slows down the hydration rate, and prolongs the cement hydration induction period, thereby improving the dispersion retention and having an excellent slump-preserving effect. At the same time, the products released after hydrolysis still carry a large number of carboxyl groups, which can be freely dispersed in the negatively charged areas of cement particles or complexed with calcium ions, further filling the nucleation sites of hydration products and further hindering the generation of hydration products.

[0054] In addition, the structure of ester monomers affects the molecular structure of water reducers. If the proportion of olefin and ester groups in ester monomers is different, the structure of polycarboxylic acid water reducers will be different, thus affecting the effect of water reducers. Although some ester monomers involved in polymerization also have ester groups, and even have diester structures. However, their structures are one olefin combined with one ester group or dienes combined with diester groups. For example, the structure of ester monomers is as follows: ; Compared with the existing ester monomers (one olefin with one ester group or two olefins with two ester groups) in which the ratio of olefin to ester group is 1 in the structure of the above-mentioned ester monomers, the present application adopts a specific ester monomer (one olefin with two ester groups, the structure is shown below). The monoolefin with two ester groups will not cause the polycarboxylic acid water reducer to produce a cross-linking reaction. Its two ester group structures produce more carboxyl groups when hydrolyzed, which are easier to adsorb on the surface of cement particles and hydration products, thereby improving the collapse-preserving effect.

[0055] .

[0056] 4. The present application can effectively improve the long-term collapse-preserving effect of polycarboxylic acid water-reducing agent by introducing ester macromonomers. If the existing polyether macromonomer TPEG polyether is used as a substitute, the effect is not good.

[0057] 5. The process of this application is simple to operate, the reaction conditions are mild, it is easy to scale up production, the production process is safe and pollution-free, and it is an environmentally friendly product.

[0058] Finally, it should be noted that: 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.

[0059] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A super slow-setting ester polycarboxylate water reducer, characterized in that: The copolymer is formed by polymerization of comonomers under the action of an initiator, a chain transfer agent and an emulsifier; the comonomers include ester macromonomers, polyoxyalkyl ethers containing ester groups and rigid benzene ring structures, ester micromonomers and unsaturated acids; The structural formula of the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure is as follows: ， Wherein, R1 is an alkylene group having 1 or 2 carbon atoms; N1 is an epoxyalkyl group containing an ester group and a rigid benzene ring structure; The structural formula of the ester small monomer is as follows: , wherein R2 is an alkylene group having 1 to 5 carbon atoms.

2. The super slow-setting ester polycarboxylate water reducer according to claim 1, characterized in that: The structure of N1 is as follows: ,or ; Among them, n is 4 to 18.

3. The super slow-setting ester polycarboxylate water reducer according to claim 1, characterized in that: The polyoxyalkyl ether containing an ester group and a rigid benzene ring structure is prepared by a ring-opening polymerization reaction of an unsaturated alcohol and an epoxy acid ester compound under the action of a catalyst; Wherein, the unsaturated alcohol is diethylene glycol monoallyl ether or diethylene glycol monovinyl ether; the epoxy ester compound is 2,3-epoxypropyl benzoate or 3,3-diphenyl-2,3-epoxypropionic acid methyl ester; The molar ratio of the unsaturated alcohol to the epoxy ester compound is 1:(6-18); the ring-opening polymerization reaction temperature is 100° C.-180° C., the reaction time is 4-6 hours, and the reaction pressure is 0.3Mpa-0.5Mpa.

4. The super slow-setting ester polycarboxylate water-reducing agent according to claim 3, characterized in that: The catalyst is one or more combinations of potassium hydroxide, sodium ethoxide, sodium hydride, potassium hydride and potassium hydroxide.

5. The super slow-setting ester polycarboxylate water reducer according to claim 1, characterized in that: The mass ratio of the ester small monomer, the ester macromonomer, the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure, and the unsaturated acid is (1.8-6):100:(10-16):(4-13); The polymerization reaction temperature is 25° C. to 35° C., and the reaction time is 0.5 h to 1.5 h.

6. The super slow-setting ester polycarboxylate water reducer according to claim 1, characterized in that: The ester macromonomer is one or more combinations of polyethylene glycol dimethacrylate with a molecular weight of 1500-5000, polyethylene glycol monomethyl ether acrylate with a molecular weight of 1500-5000, polyethylene glycol acrylate with a molecular weight of 1500-5000, polyethylene glycol monomethoxy ether monoacrylate with a molecular weight of 1500-5000, and polyethylene glycol monomethoxy ether monomethacrylate with a molecular weight of 1500-5000.

7. The super slow-setting ester polycarboxylate water reducer according to claim 1, characterized in that: The unsaturated acid is one or more combinations of acrylic acid, methacrylic acid and maleic acid.

8. The super slow-setting ester polycarboxylate water reducer according to claim 1, characterized in that: The initiator includes an oxidizing agent and a reducing agent; The oxidant is one or more combinations of potassium persulfate, hydrogen peroxide, and 2,5-dimethyl-2,5-bis(hydroperoxide)hexane; the reducing agent is one or more combinations of sodium hypophosphite, sodium sulfite, ferrous sulfate, and potassium thiosulfate; the chain transfer agent is one or more combinations of thioglycolic acid, 2-hydroxypropyl mercaptan, 2-mercaptosuccinic acid, and sodium hypophosphite; the emulsifier is one or more combinations of sorbitan polyoxyethylene ether tetraoleate and stearic acid polyoxyethylene ester.

9. The super slow-setting ester polycarboxylate water reducer according to claim 8, characterized in that: in, The amount of the oxidant is 1% to 2.5% of the total mass of the ester macromonomer, the amount of the reducing agent is 0.8% to 2.8% of the total mass of the ester macromonomer, the amount of the chain transfer agent is 0.5% to 2% of the total mass of the ester macromonomer; and the amount of the emulsifier is 1% to 4% of the total mass of the ester macromonomer.

10. A method for preparing the super slow-setting ester polycarboxylate water-reducing agent according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: The ester small monomer, the ester large monomer and the polyoxyalkyl ether containing an ester group and a rigid benzene ring structure are mixed, and an initiator solution, a chain transfer agent solution, an emulsifier solution and an unsaturated acid are added at 25° C. to 35° C. to carry out a polymerization reaction for 0.5 h to 1.5 h; then the mixture is kept warm for a certain period of time and the pH is adjusted to obtain the super slow-setting ester polycarboxylic acid water reducer.

Images