Emulsion type polycarboxylate superplasticizer and preparation method thereof
By using free radical copolymerization of modified polyether monomers and self-reactive emulsifying monomers, an emulsion-type polycarboxylate superplasticizer without emulsifiers was prepared, solving the problems of high cost and poor stability of emulsion-type superplasticizers during polymerization, and achieving low viscosity, high dispersibility and environmental friendliness of concrete.
Patent Information
- Application Number
- CN202510861638.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-25
- Publication Date
- 2025-10-28
AI Technical Summary
Existing emulsion-type water-reducing agents require the addition of emulsifiers during the polymerization process, resulting in high costs, increased carbon emissions, and unstable emulsions that cannot maintain good concrete fluidity and dispersibility during long-term storage, easily leading to problems such as bleeding, segregation, and bottoming.
Modified polyether monomers and self-reactive emulsifying monomers are subjected to free radical copolymerization under the action of initiators and chain transfer agents to form an emulsion-type polycarboxylate superplasticizer that does not require emulsifiers. The self-emulsifying ability and high reactivity of the self-reactive emulsifying monomers are utilized to improve the air entrainment capacity of concrete, reduce viscosity and increase dispersibility.
This invention enables the preparation of emulsion-type polycarboxylate superplasticizers without emulsifiers, reducing concrete viscosity, increasing concrete dispersibility, ensuring good discharge condition, avoiding problems such as bleeding, segregation, and bottoming out, while also reducing costs and carbon emissions.
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Abstract
Description
Technical Field
[0001] This application relates to the field of concrete admixtures technology, and in particular to an emulsion-type polycarboxylate superplasticizer and its preparation method. Background Technology
[0002] As the required strength grade of concrete increases, the amount of cement used in concrete increases while the amount of water used relatively decreases, leading to problems such as poor concrete fluidity, less paste, and increased concrete viscosity. In the industry, admixtures are typically added to modify the fluidity of concrete. Therefore, during the concrete production process, the required strength grade of the resulting concrete, the amount of water used, and the amount of admixtures all affect the viscosity of the concrete. In addition, poor quality aggregates, large differences in mix proportions, low water-cement ratios, poor aggregate gradation, and environmental factors can also affect the viscosity of concrete, resulting in significant inconvenience for on-site construction.
[0003] In the industry, admixtures are often added to adjust the viscosity of concrete and change its fluidity to facilitate on-site construction. However, when high admixture dosages are required to improve the fluidity of concrete and make it suitable for construction operations, excessive admixture dosages can also cause problems such as bleeding, segregation, and bottoming, leading to defects in the concrete's output state, such as exposed aggregate and poor encapsulation.
[0004] Therefore, the development of a water-reducing admixture that can significantly reduce concrete viscosity and increase concrete dispersibility to meet construction requirements, while also ensuring good concrete output (no exposed aggregate and good encapsulation) is precisely what this field is dedicated to researching and exploring.
[0005] For the preparation of water-reducing agent admixtures, especially in the preparation of emulsion-type water-reducing agents, emulsion polymerization is one of the four conventional methods for synthesizing emulsion-type water-reducing agent polymer materials. Conventional emulsion polymerization usually consists of polymeric monomers, initiators, emulsifiers, chain transfer agents, thickeners, and water. The most important substance for the formation of an emulsion in emulsion polymerization is the emulsifier. Emulsifiers can be divided into anionic emulsifiers and cationic emulsifiers. Adjusting the water-oil balance value of the emulsifier can result in a bluish emulsion with a suitable micelle particle size, that is, a nano-sized latex.
[0006] In the polymerization process of existing emulsion-type water-reducing agents, emulsifiers are often added. Emulsifiers, similar to surfactants, are used to adjust the hydrophilic-lipophilic balance of the polymerization system, acting as a reaction carrier between "oil-based" and "water-based" substances. However, the emulsion-type water-reducing agents formed by existing emulsifiers are merely high-speed shear emulsifications of polycarboxylate superplasticizers and emulsifiers, and cannot form stable emulsions under long-term storage conditions. Furthermore, from the perspective of the cost of polymerization raw materials, adding emulsifiers incurs additional costs. Moreover, from an environmental perspective, introducing emulsifiers will ultimately increase carbon emissions to some extent.
[0007] Therefore, exploring routes for preparing emulsion-type water-reducing agents without adding emulsifiers is crucial. A non-emulsifier route could significantly reduce concrete viscosity and increase its dispersibility, improving the flowability of the concrete mixture to meet construction requirements. Simultaneously, it could reduce the hydrophilic sensitivity of the water-reducing agent, ensuring good concrete output without bleeding, segregation, or bottoming issues. This approach not only meets application needs but also reduces costs and promotes environmental friendliness, making it a valuable and promising market prospect. However, preparing emulsion-type water-reducing agents directly from conventional monomers, initiators, chain transfer agents, and water without adding emulsifiers would result in incomplete or non-reactive polymerization due to the presence of oily substances in the monomers. Summary of the Invention
[0008] To address the problems of existing polycarboxylate superplasticizers mentioned in the background section, this application provides an emulsion-type polycarboxylate superplasticizer, the technical solution of which is as follows: This application provides an emulsion-type polycarboxylate superplasticizer, which is polymerized by free radical copolymerization of modified polyether monomers and self-reactive emulsifying monomers under the action of an initiator and a chain transfer agent; The modified polyether monomer comprises 100-250 parts by weight, the self-reactive emulsifying monomer combination comprises 30-75 parts, the initiator comprises 0.6-5.5 parts, and the chain transfer agent comprises 0.5-3 parts. The self-reactive emulsifying monomer combination consists of monomers of type A, type B, and type C, or monomers of type A, type B, and type D, or monomers of type A, type C, and type D; wherein, the monomer of type A is acrylic acid; the monomer of type B is one or more of vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl valerate; the monomer of type C is one or more of sodium ethylene sulfonate and sodium propylene sulfonate; and the monomer of type D is one or more of acrylamide, styrene, and butadiene.
[0009] In some embodiments, when the self-reactive emulsifying monomer combination consists of type A monomers, type B monomers, and type C monomers, the mass ratio of type A monomers, type B monomers, and type C monomers is (2-4):(4-8):1; when the self-reactive emulsifying monomer combination consists of type A monomers, type C monomers, and type D monomers, the mass ratio of type A monomers, type C monomers, and type D monomers is (2-5):(5-7):1; when the self-reactive emulsifying monomer combination consists of type A monomers, type B monomers, and type D monomers, the mass ratio of type A monomers, type B monomers, and type D monomers is (2-3):(6-7):1.
[0010] In some embodiments, the modified polyether monomer includes a first type of modified polyether and a second type of modified polyether; the first type of modified polyether is one or two of polyethylene glycol acrylate and polyethylene glycol maleate; the second type of modified polyether is one or more of vinyl polyoxyethylene ether, allyl polyoxyethylene ether, isobutylene polyoxyethylene ether, and isopentenene polyoxyethylene ether.
[0011] In some embodiments, the modified polyether monomer is composed of a first type of modified polyether and a second type of modified polyether; the mass ratio of the first type of modified polyether to the second type of modified polyether is 1:(3-6).
[0012] In some embodiments, the temperature of the free radical copolymerization reaction is 10–50°C.
[0013] In some embodiments, the free radical copolymerization process is as follows: preparing raw materials including modified polyether monomers, a combination of self-reactive emulsifying monomers, an initiator, a chain transfer agent, water, and a metal salt; placing the modified polyether monomers, the combination of self-reactive emulsifying monomers, the initiator, the chain transfer agent, and water in a reactor, controlling the temperature at 10–50°C to carry out a free radical copolymerization reaction; after the reaction is completed, adding the metal salt until dissolved to obtain the emulsion-type polycarboxylate superplasticizer.
[0014] In some embodiments, the initiator includes an oxidant and a reducing agent; by weight, the raw materials for the free radical copolymerization reaction include 100-250 parts of the modified polyether monomer, 30-75 parts of the self-reactive emulsifying monomer combination, 0.5-5 parts of the oxidant, 0.1-0.5 parts of the reducing agent, 0.5-3 parts of the chain transfer agent, 1-5 parts of the metal salt, and water; the temperature of the free radical copolymerization reaction is 30-50°C.
[0015] In some embodiments, the solid content of the emulsion-type polycarboxylate superplasticizer is 40% to 60%; the viscosity of the emulsion-type polycarboxylate superplasticizer is 500 to 2000 cP.
[0016] This application also provides a method for preparing the emulsion-type polycarboxylate superplasticizer as described above, which includes the following steps: Raw material preparation: By weight, the raw materials include 100-250 parts of modified polyether monomer, 30-75 parts of self-reactive emulsifying monomer combination, 0.5-5 parts of oxidant, 0.1-0.5 parts of reducing agent, 0.5-3 parts of chain transfer agent, 1-5 parts of metal salt, and water; Modified polyether monomers, a combination of self-reactive emulsifying monomers, an initiator, a chain transfer agent, and water are placed in a reactor, and a free radical copolymerization reaction is carried out at a controlled temperature of 10–50°C. After the reaction is completed, a metal salt is added until dissolved to obtain the emulsion-type polycarboxylate superplasticizer.
[0017] In some embodiments, the following steps are included: By weight, 100-250 parts of modified polyether monomer, 0.5-5 parts of oxidant, and 15-150 parts of water are placed in a reactor, the temperature is adjusted to 10-30℃, and the mixture is stirred for 0.2-0.5 hours to obtain the first mixture. Mix 30-75 parts of self-reactive emulsifying monomers with 5-50 parts of water to obtain a second mixture; Mix 0.1–0.5 parts of reducing agent, 0.5–3 parts of chain transfer agent, and 5–50 parts of water to obtain a third mixture; The second and third mixtures are simultaneously added dropwise to the first mixture over 1–3 hours. After the addition is complete, a constant-temperature reaction is carried out at 30–50°C for 1–2 hours. Then, 1–5 parts of metal salt and 5–35 parts of water are added, and stirring is continued for 0.2–0.5 hours to obtain the emulsion-type polycarboxylate superplasticizer.
[0018] Based on the above, compared with the prior art, the emulsion-type polycarboxylate superplasticizer provided in this application has the following beneficial effects: The emulsion-type polycarboxylate superplasticizer provided in this application does not require the addition of an emulsifier. It only requires the introduction of a self-reactive emulsifying monomer into the reaction system. By utilizing the self-emulsifying ability and high reactivity of the self-reactive emulsifying monomer, the air-entraining ability of the polycarboxylate superplasticizer in concrete can be improved, the concrete viscosity can be reduced, and the concrete dispersion can be increased, so as to facilitate on-site construction operations. At the same time, it can ensure that the concrete has a good discharge condition, without bleeding, segregation, or bottoming problems, and the concrete has no exposed aggregate and good encapsulation.
[0019] Other features and beneficial effects of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other beneficial effects of this application may be realized and obtained by means of the structures particularly pointed out in the description and claims. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. The technical features designed in the different implementations of this application described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0021] In the description of this application, it should be noted that all terms used in this application (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains, and should not be construed as limiting this application; it should be further understood that the terms used in this application should be understood to have the same meaning as those in the context of this specification and the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this application.
[0022] The preferred example of the preparation method of the emulsion-type polycarboxylate superplasticizer provided in this application is as follows, including the following steps: S100. By weight, 100-250 parts of modified polyether monomer, 0.5-5 parts of oxidant, and 15-150 parts of water are placed in a reactor, the temperature is adjusted to 10-30℃, and the mixture is stirred for 0.2-0.5 hours to obtain the first mixture. S200. Mix 30-75 parts of self-reactive emulsifying monomers with 5-50 parts of water to obtain a second mixture; S300. Mix 0.1 to 0.5 parts of reducing agent, 0.5 to 3 parts of chain transfer agent and 5 to 50 parts of water to obtain a third mixture; S400. The second mixture and the third mixture are simultaneously added dropwise to the first mixture for 1 to 3 hours. After the addition is completed, a constant temperature reaction is carried out at 30 to 50°C. After the constant temperature reaction is carried out for 1 to 2 hours, 1 to 5 parts of metal salt are added, and 5 to 35 parts of water are added. Stirring is continued for 0.2 to 0.5 hours to obtain the emulsion-type polycarboxylate superplasticizer.
[0023] The self-reactive emulsifying monomer combination comprises monomers of type A, type B, and type C, or monomers of type A, type B, and type D, or monomers of type A, type C, and type D; the type A monomer is acrylic acid; the type B monomer is one or more of vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl valerate; the type C monomer is one or more of sodium ethylene sulfonate and sodium propylene sulfonate; and the type D monomer is one or more of acrylamide, styrene, and butadiene.
[0024] When the self-reactive emulsifying monomer combination consists of type A monomers, type B monomers, and type C monomers, the mass ratio of type A monomers, type B monomers, and type C monomers is (2-4):(4-8):1; when the self-reactive emulsifying monomer combination consists of type A monomers, type C monomers, and type D monomers, the mass ratio of type A monomers, type C monomers, and type D monomers is (2-5):(5-7):1; when the self-reactive emulsifying monomer combination consists of type A monomers, type B monomers, and type D monomers, the mass ratio of type A monomers, type B monomers, and type D monomers is (2-3):(6-7):1.
[0025] The modified polyether monomer comprises a first type of modified polyether and a second type of modified polyether; the first type of modified polyether is one or two of polyethylene glycol acrylate and polyethylene glycol maleate; the second type of modified polyether is one or more of vinyl polyoxyethylene ether, allyl polyoxyethylene ether, isobutylene polyoxyethylene ether, and isopentenene polyoxyethylene ether. The mass ratio of the first type of modified polyether to the second type of modified polyether is 1:(3-6).
[0026] Specifically, the raw materials for preparing emulsion-type polycarboxylate superplasticizers include modified polyether monomers, a combination of self-reactive emulsifying monomers, initiators, chain transfer agents, metal salts, and water. A copolymerization reaction is carried out by combining specific modified polyethers with specific self-reactive emulsifying monomer combinations (acrylic acid has high reactivity, while vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, sodium ethylene sulfonate, sodium propylene sulfonate, styrene, butadiene, and acrylamide have strong self-emulsifying abilities). During the reaction, the initiator first decomposes to generate initiator free radicals, which are then transferred to the modified polyether monomers and the combination of self-reactive emulsifying monomers. The monomers then undergo a copolymerization reaction in a water-based solvent environment to obtain the emulsion-type polycarboxylate superplasticizer. This introduces specific self-reactive emulsifying monomers into the macromolecules of the prepared emulsion-type polycarboxylate superplasticizer. Utilizing the self-emulsifying ability and high reactivity of the self-reactive emulsifying monomer combination, the air-entraining capacity of the polycarboxylate superplasticizer in concrete is improved, thereby reducing the viscosity of the concrete.
[0027] This application describes a polycarboxylate superplasticizer obtained by free radical polymerization of modified polyether macromonomers, self-reactive emulsifying monomers, and other substances under the action of oxidants, reducing agents, and chain transfer agents. No emulsifier needs to be added; only the self-reactive emulsifying monomer is introduced into the reaction system. Utilizing the self-emulsifying ability and high reactivity of the self-reactive emulsifying monomer, the air-entraining capacity of the polycarboxylate superplasticizer in concrete is improved, reducing concrete viscosity and increasing concrete dispersibility. This facilitates on-site construction while ensuring good concrete discharge condition, preventing bleeding, segregation, and bottoming issues, and resulting in no exposed aggregate and good encapsulation.
[0028] To verify the effectiveness of this application, the following embodiments and comparative examples are also provided: Example 1 S100. By weight, 100 parts (polyethylene glycol acrylate: vinyl polyoxyethylene ether mass ratio = 1:3), 1 part hydrogen peroxide and 130 parts water are placed in a reactor, the temperature is adjusted to 10°C, and the mixture is stirred for 0.2 h to obtain the first mixture.
[0029] S200. Mix 30 parts (acrylic acid: sodium ethylene sulfonate: vinyl acetate mass ratio = 2:1:6) and 15 parts water to obtain a second mixture.
[0030] S300. Mix 0.2 parts ferrous sulfate, 0.5 parts mercaptoethanol and 25 parts water to obtain a third mixture.
[0031] S400. The second and third mixtures are simultaneously added dropwise to the first mixture over 1.5 hours. After the addition is complete, a constant temperature reaction is carried out at 30°C. After 1 hour of constant temperature reaction, 2 parts of sodium hydroxide and 25 parts of water are added. Stirring is continued for 0.2 hours to obtain an emulsion-type polycarboxylate superplasticizer solution with a solid content of 40%.
[0032] Example 2 S100. By weight, 150 parts (polyethylene glycol maleate: allyl polyoxyethylene ether mass ratio = 1:4), 1.5 parts tert-butyl hydrogen peroxide and 150 parts water are placed in a reactor, the temperature is adjusted to 15°C, and the mixture is stirred for 0.3 h to obtain the first mixture.
[0033] S200. Mix 40 parts (acrylic acid:butadiene:vinyl propionate mass ratio = 3:1:5) and 15 parts water to obtain a second mixture.
[0034] S300. Mix 0.3 parts of sodium formaldehyde sulfoxylate, 0.8 parts of mercaptoacetic acid and 25 parts of water to obtain a third mixture.
[0035] S400. The second and third mixtures are simultaneously added dropwise to the first mixture over 2 hours. After the addition is complete, a constant temperature reaction is carried out at 35°C. After 1 hour of constant temperature reaction, 2.5 parts of sodium bicarbonate are added, followed by 40 parts of water. The mixture is stirred for another 0.5 hours to obtain an emulsion-type polycarboxylate superplasticizer solution with a solid content of 45%.
[0036] Example 3 S100. By weight, 200 parts (polyethylene glycol acrylate: isopentenyl polyoxyethylene ether mass ratio = 1:5), 2 parts sodium persulfate and 170 parts water are placed in a reaction vessel, the temperature is adjusted to 20°C, and the mixture is stirred for 0.4 h to obtain the first mixture.
[0037] S200. Mix 50 parts (acrylic acid:styrene:sodium vinyl sulfonate mass ratio = 2:1:7) and 15 parts water to obtain a second mixture.
[0038] S300. Mix 0.4 parts ascorbic acid, 1 part mercaptopropionic acid and 25 parts water to obtain the third mixture.
[0039] S400. The second and third mixtures are simultaneously added dropwise to the first mixture over 2.5 hours. After the addition is complete, a constant temperature reaction is carried out at 40°C. After 1.5 hours of constant temperature reaction, 3 parts of sodium sulfite are added, followed by 45 parts of water. The mixture is stirred for another 0.3 hours to obtain an emulsion-type polycarboxylate superplasticizer solution with a solid content of 50%.
[0040] Example 4 S100. By weight, 250 parts (polyethylene glycol maleate: isobutylene polyoxyethylene ether mass ratio = 1:6), 5 parts potassium peroxide and 160 parts water are placed in a reactor, the temperature is adjusted to 25°C, and the mixture is stirred for 0.4 h to obtain the first mixture.
[0041] S200. Mix 75 parts (acrylic acid:acrylamide:vinyl valerate mass ratio = 3:1:6) and 15 parts water to obtain a second mixture.
[0042] S300. Mix 0.5 parts sodium ascorbate, 3 parts mercaptopropionic acid and 25 parts water to obtain the third mixture.
[0043] S400. The second and third mixtures are simultaneously added dropwise to the first mixture over 3 hours. After the addition is complete, a constant temperature reaction is carried out at 45°C. After 2 hours of constant temperature reaction, 5 parts of sodium hydroxide are added, and stirring is continued for 0.5 hours. Then, 20 parts of water are added, and stirring is continued for 0.4 hours to obtain an emulsion-type polycarboxylate superplasticizer solution with a solid content of 60%.
[0044] Comparative Example 1 (the only difference from Example 1 is that the self-reactive emulsifying monomer is a single monomer) S100. By weight, 100 parts (polyethylene glycol acrylate: vinyl polyoxyethylene ether mass ratio = 1:3), 1 part hydrogen peroxide and 130 parts water are placed in a reactor, the temperature is adjusted to 10°C, and the mixture is stirred for 0.2 h to obtain the first mixture.
[0045] S200. Mix 30 parts acrylic acid and 15 parts water to obtain a second mixture.
[0046] S300. Mix 0.2 parts ferrous sulfate, 0.5 parts mercaptoethanol and 25 parts water to obtain a third mixture.
[0047] S400. The second and third mixtures are simultaneously added dropwise to the first mixture over 1.5 hours. After the addition is complete, a constant temperature reaction is carried out at 30°C. After 1 hour of constant temperature reaction, 2 parts of sodium hydroxide and 25 parts of water are added. Stirring is continued for 0.2 hours to obtain a colorless and transparent polycarboxylate superplasticizer solution with a solid content of 40%.
[0048] Comparative Example 2 (the only difference from Example 1 is that the self-reactive emulsifying monomer is a combination of two monomers) S100. By weight, 100 parts (polyethylene glycol acrylate: vinyl polyoxyethylene ether mass ratio = 1:3), 1 part hydrogen peroxide and 130 parts water are placed in a reactor, the temperature is adjusted to 10°C, and the mixture is stirred for 0.2 h to obtain the first mixture.
[0049] S200. Mix 30 parts (acrylic acid: vinyl acetate mass ratio = 2:7) and 15 parts water to obtain a second mixture.
[0050] S300. Mix 0.2 parts ferrous sulfate, 0.5 parts mercaptoethanol and 25 parts water to obtain a third mixture.
[0051] S400. The second and third mixtures are simultaneously added dropwise to the first mixture over 1.5 hours. After the addition is complete, a constant temperature reaction is carried out at 30°C. After 1 hour of constant temperature reaction, 2 parts of sodium hydroxide and 25 parts of water are added. Stirring is continued for 0.2 hours to obtain a colorless and transparent polycarboxylate superplasticizer solution with a solid content of 40%.
[0052] Comparative Example 3 (the only difference from Example 1 is that the proportion of monomers in the self-reactive emulsifying monomer exceeds the specified range). S100. By weight, 100 parts (polyethylene glycol acrylate: vinyl polyoxyethylene ether mass ratio = 1:3), 1 part hydrogen peroxide and 130 parts water are placed in a reactor, the temperature is adjusted to 10°C, and the mixture is stirred for 0.2 h to obtain the first mixture.
[0053] S200. Mix 30 parts (acrylic acid: sodium ethylene sulfonate: vinyl acetate mass ratio = 8:1:1) and 15 parts water to obtain a second mixture.
[0054] S300. Mix 0.2 parts ferrous sulfate, 0.5 parts mercaptoethanol and 25 parts water to obtain a third mixture.
[0055] S400. The second and third mixtures are simultaneously added dropwise to the first mixture over 1.5 hours. After the addition is complete, a constant temperature reaction is carried out at 30°C. After 1 hour of constant temperature reaction, 2 parts of sodium hydroxide and 25 parts of water are added. Stirring is continued for 0.2 hours to obtain a colorless and transparent polycarboxylate superplasticizer solution with a solid content of 40%.
[0056] Comparative Example 4 (the only difference from Example 1 is that the polymerization temperature is not within the specified range) S100. By weight, 100 parts (polyethylene glycol acrylate: vinyl polyoxyethylene ether mass ratio = 1:3), 1 part hydrogen peroxide and 130 parts water are placed in a reactor, the temperature is adjusted to 0℃, and the mixture is stirred for 0.2 h to obtain the first mixture.
[0057] S200. Mix 30 parts (acrylic acid: sodium ethylene sulfonate: vinyl acetate mass ratio = 2:1:6) and 15 parts water to obtain a second mixture.
[0058] S300. Mix 0.2 parts ferrous sulfate, 0.5 parts mercaptoethanol and 25 parts water to obtain a third mixture.
[0059] S400. The second and third mixtures are simultaneously added dropwise to the first mixture over 1.5 hours. After the addition is complete, a constant temperature reaction is carried out at 60°C. After 1 hour of constant temperature reaction, 2 parts of sodium hydroxide and 25 parts of water are added. Stirring is continued for 0.2 hours to obtain a relatively viscous emulsion-type polycarboxylate superplasticizer solution with a solid content of 40%.
[0060] Comparative Example 5 (the only difference from Example 1 is that the modified polyether is a single monomer) S100. By weight, 100 parts of vinyl polyoxyethylene ether, 1 part of hydrogen peroxide and 130 parts of water are placed in a reactor, the temperature is adjusted to 10°C and stirred for 0.2 hours to obtain the first mixture.
[0061] S200. Mix 30 parts (acrylic acid: sodium ethylene sulfonate: vinyl acetate mass ratio = 2:1:6) and 15 parts water to obtain a second mixture.
[0062] S300. Mix 0.2 parts ferrous sulfate, 0.5 parts mercaptoethanol and 25 parts water to obtain a third mixture.
[0063] S400. The second and third mixtures are simultaneously added dropwise to the first mixture over 1.5 hours. After the addition is complete, a constant temperature reaction is carried out at 30°C. After 1 hour of constant temperature reaction, 2 parts of sodium hydroxide and 25 parts of water are added. Stirring is continued for 0.2 hours to obtain an emulsion-type polycarboxylate superplasticizer solution with a solid content of 40%.
[0064] Performance tests were performed on the products of the examples and comparative examples: The experimental materials are as follows: Cement: Conch Cement PO 42.5; Manufactured sand: produced locally in Guizhou, with a fineness modulus of 2.6–3.2; Secondary aggregate: locally produced in Guizhou, with aggregate size ranging from 5 to 35 mm; Commercially available polycarboxylate slump retainer: produced locally in Guizhou, 40% solids content.
[0065] The emulsion-type polycarboxylate superplasticizer prepared in the examples and the superplasticizer prepared in the comparative examples were compounded with commercially available polycarboxylate slump retainer at a ratio of 8:2 (folded to solid), and diluted to a 15% solution. A concrete comparison experiment was conducted under the same mixing ratio conditions.
[0066] Performance tests were conducted on C30 concrete according to GB 8076-2008 "Concrete Admixtures," comparing its viscosity (characterized by the slump time of the concrete slump cone) and air content. The mix proportions are shown in Table 1. Table 1 Experimental mix proportions of C50 concrete (unit: kg / m³) 3
[0067] According to the national standard GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", the viscosity of concrete was evaluated by testing, and the test results in Table 1 were obtained according to GB / T 50081-2016 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The concrete performance test results are shown in Tables 2-3.
[0068] Table 2 Concrete Performance Tests
[0069] Table 3 Concrete Performance Tests
[0070] The "outflow state" refers to the state where concrete flows out of the mixer after 2 minutes of mixing and remains stationary.
[0071] Analysis of performance test results of the products of the examples and comparative examples The raw materials for the preparation of the polycarboxylate superplasticizers in Comparative Examples 1, 2, 3, 4, and 5 were all modified based on Example 1. Specifically, Comparative Example 1 did not add vinyl acetate and sodium ethylene sulfonate compared to Example 1, and the acid used in the reaction was a single combination; Comparative Example 2 did not add the two raw materials, sodium ethylene sulfonate, compared to Example 1, and the acid used in the reaction was a combination of two; Comparative Example 3 used three combinations of acids compared to Example 1, and the reaction ratios were different; Comparative Example 4 used three combinations of acids compared to Example 1, and the reaction temperature was not within the range specified in this application; Comparative Example 5 used a single polyether compared to Example 1.
[0072] The test results show that, compared with Example 1, Comparative Example 1 has a larger initial expansion and a smaller 2-hour expansion. The initial and 2-hour tumbling times of Comparative Example 1 are 1.8 s and 2.6 s respectively. The initial and 2-hour gas content of Example 1 are 2.0% and 0.5% respectively. This indicates that the viscosity (tumbling time) of Comparative Example 1, which does not contain polyethylene glycol acrylate, vinyl acetate, styrene, and is a combination of acids, is higher and the gas content is lower.
[0073] The test results show that, compared with Example 1, Comparative Example 2 has a larger initial expansion and a smaller 2-hour expansion. The initial and 2-hour tumbling times of Comparative Example 2 are 1.6 s and 2.2 s respectively, and the initial and 2-hour gas contents of Comparative Example 2 are 1.6% and 0.4% respectively. This indicates that the viscosity (tumbling time) of Comparative Example 2, which has two combinations of reactive acids, has increased and the gas content has decreased.
[0074] The test results show that, compared with Example 1, Comparative Example 3 has a larger initial expansion and a smaller 2-hour expansion. The initial and 2-hour tumbling times of Comparative Example 3 are 1.2 s and 1.8 s respectively, and the initial and 2-hour gas content of Comparative Example 3 are 1.8% and 0.8% respectively. This indicates that the viscosity (tumbling time) of Comparative Example 3 with different reaction ratios has increased and the gas content has decreased.
[0075] The test results show that, compared with Example 1, Comparative Example 4 has a larger initial expansion and a smaller 2-hour expansion. The initial and 2-hour tumbling times of Comparative Example 4 are 1.3s and 1.5s respectively, and the initial and 2-hour gas contents of Comparative Example 4 are 1.5% and 0.6% respectively. This indicates that the viscosity (tumbling time) of Comparative Example 4, which is outside the range specified in this application, has increased and the gas content has decreased.
[0076] The test results show that, compared with Example 1, Comparative Example 5 has a larger initial expansion and a smaller 2-hour expansion. The initial and 2-hour tumbling times of Comparative Example 5 are 2.0 s and 2.7 s respectively. The initial and 2-hour gas content of Comparative Example 5 are 1.6% and 0.4% respectively. This indicates that the viscosity (tumbling time) of Comparative Example 5, which uses a single type of polyether, is increased and the gas content is reduced.
[0077] The bleeding rate test results show that, compared with Example 1, the bleeding rate of Comparative Example 1 is 3.6, while the bleeding rate of Example 1 is only 0.24. The bleeding rate is relatively low, indicating that its concrete sensitivity is low and it will not cause bleeding due to excessive addition of polycarboxylate superplasticizer.
[0078] The bleeding rate test results show that, compared with Example 1, the bleeding rate of Comparative Example 2 is 3.8, while the bleeding rate of Example 1 is only 0.24. The bleeding rate is relatively low, indicating that its concrete sensitivity is low and it will not cause bleeding due to excessive addition of polycarboxylate superplasticizer.
[0079] The bleeding rate test results show that, compared with Example 1, the bleeding rate of Comparative Example 3 is 4.4, while the bleeding rate of Example 1 is only 0.24. The bleeding rate is relatively low, indicating that its concrete sensitivity is low and it will not cause bleeding due to excessive addition of polycarboxylate superplasticizer.
[0080] The bleeding rate test results show that, compared with Example 1, the bleeding rate of Comparative Example 4 is 4.1, while the bleeding rate of Example 1 is only 0.24. The bleeding rate is relatively low, indicating that its concrete sensitivity is low and it will not cause bleeding due to excessive addition of polycarboxylate superplasticizer.
[0081] The bleeding rate test results show that, compared with Example 1, Comparative Example 5 has a bleeding rate of 4.2, while Example 1 has a bleeding rate of only 0.24. The bleeding rate is relatively low, indicating that it has low concrete sensitivity and will not cause bleeding due to excessive addition of polycarboxylate superplasticizer.
[0082] It should be noted that: The emulsion-type polycarboxylate superplasticizer of this application can be used alone or in combination with other additives.
[0083] In this article, “~” is used to represent the range of values, and the range of values represented by this expression includes two endpoint values.
[0084] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments under the concept of this application, and are not intended to limit them; those skilled in the art can make adaptive adjustments within the concept and protection scope of this application.
[0085] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. An emulsion-type polycarboxylate superplasticizer, characterized in that: It is polymerized by free radical copolymerization of modified polyether monomers and self-reactive emulsifying monomers under the action of initiators and chain transfer agents; The modified polyether monomer comprises 100-250 parts by weight, the self-reactive emulsifying monomer combination comprises 30-75 parts, the initiator comprises 0.6-5.5 parts, and the chain transfer agent comprises 0.5-3 parts. The self-reactive emulsifying monomer combination consists of type A monomers, type B monomers, and type C monomers, or type A monomers, type B monomers, and type D monomers, or type A monomers, type C monomers, and type D monomers; Wherein, the type A monomer is acrylic acid; the type B monomer is one or more of vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl valerate; the type C monomer is one or more of sodium ethylene sulfonate and sodium propylene sulfonate; and the type D monomer is one or more of acrylamide, styrene, and butadiene.
2. The emulsion-type polycarboxylate superplasticizer according to claim 1, characterized in that: When the self-reactive emulsifying monomer combination is composed of type A monomers, type B monomers and type C monomers, the mass ratio of type A monomers, type B monomers and type C monomers is (2~4):(4~8):1; When the self-reactive emulsifying monomer combination is composed of type A monomers, type C monomers and type D monomers, the mass ratio of type A monomers, type C monomers and type D monomers is (2~5):(5~7):1; When the self-reactive emulsifying monomer combination is composed of type A monomers, type B monomers and type D monomers, the mass ratio of type A monomers, type B monomers and type D monomers is (2~3):(6~7):
1.
3. The emulsion-type polycarboxylate superplasticizer according to claim 1, characterized in that, The modified polyether monomers include Class I modified polyethers and Class II modified polyethers; The first type of modified polyether is one or two of polyethylene glycol acrylate and polyethylene glycol maleate; The second type of modified polyether is one or more of vinyl polyoxyethylene ether, allyl polyoxyethylene ether, isobutylene polyoxyethylene ether, and isopentenene polyoxyethylene ether.
4. The emulsion-type polycarboxylate superplasticizer according to claim 1, characterized in that: The modified polyether monomer is composed of a first type of modified polyether and a second type of modified polyether; The mass ratio of the first type of modified polyether to the second type of modified polyether is 1:(3-6).
5. The emulsion-type polycarboxylate superplasticizer according to claim 1, characterized in that: The temperature of the free radical copolymerization reaction is 10–50 °C.
6. The emulsion-type polycarboxylate superplasticizer according to claim 1, characterized in that, The free radical copolymerization process is as follows: Prepare the raw materials: modified polyether monomers, self-reactive emulsifying monomer combination, initiator, chain transfer agent, water, and metal salt; The modified polyether monomer, the self-reactive emulsifying monomer combination, the initiator, the chain transfer agent, and water are placed in a reactor, and a free radical copolymerization reaction is carried out at a controlled temperature of 10–50°C. After the reaction is completed, a metal salt is added until dissolved to obtain the emulsion-type polycarboxylate superplasticizer.
7. The emulsion-type polycarboxylate superplasticizer according to claim 6, characterized in that, The initiator includes an oxidant and a reducing agent; by weight, the raw materials for the free radical copolymerization reaction include 100-250 parts of the modified polyether monomer, 30-75 parts of the self-reactive emulsifying monomer combination, 0.5-5 parts of the oxidant, 0.1-0.5 parts of the reducing agent, 0.5-3 parts of the chain transfer agent, 1-5 parts of the metal salt, and water; The free radical copolymerization reaction is carried out at a temperature of 30–50 °C.
8. The emulsion-type polycarboxylate superplasticizer according to claim 1, characterized in that, The solid content of the emulsion-type polycarboxylate superplasticizer is 40% to 60%. The viscosity of the emulsion-type polycarboxylate superplasticizer is 500–2000 cP.
9. A method for preparing an emulsion-type polycarboxylate superplasticizer as described in any one of claims 1-8, characterized in that, Includes the following steps: Raw material preparation: By weight, the raw materials include 100-250 parts of modified polyether monomer, 30-75 parts of self-reactive emulsifying monomer combination, 0.5-5 parts of oxidant, 0.1-0.5 parts of reducing agent, 0.5-3 parts of chain transfer agent, 1-5 parts of metal salt, and water; Modified polyether monomers, a combination of self-reactive emulsifying monomers, an initiator, a chain transfer agent, and water are placed in a reactor, and a free radical copolymerization reaction is carried out at a controlled temperature of 10–50°C. After the reaction is completed, a metal salt is added until dissolved to obtain the emulsion-type polycarboxylate superplasticizer.
10. The preparation method of the emulsion-type polycarboxylate superplasticizer according to claim 9, characterized in that, Includes the following steps: By weight, 100-250 parts of modified polyether monomer, 0.5-5 parts of oxidant, and 15-150 parts of water are placed in a reactor, the temperature is adjusted to 10-30℃, and the mixture is stirred for 0.2-0.5 hours to obtain the first mixture. Mix 30-75 parts of self-reactive emulsifying monomers with 5-50 parts of water to obtain a second mixture; Mix 0.1–0.5 parts of reducing agent, 0.5–3 parts of chain transfer agent, and 5–50 parts of water to obtain a third mixture; The second and third mixtures are simultaneously added dropwise to the first mixture over 1–3 hours. After the addition is complete, a constant-temperature reaction is carried out at 30–50°C for 1–2 hours. Then, 1–5 parts of metal salt and 5–35 parts of water are added, and stirring is continued for 0.2–0.5 hours to obtain the emulsion-type polycarboxylate superplasticizer.