A multifunctional polycarboxylate superplasticizer and its preparation method

Abstract

This invention discloses a multifunctional polycarboxylate superplasticizer and its preparation method. First, a polyester prepolymer containing multifunctional groups such as benzene rings, sulfonic acid groups, ester groups, hydroxyl groups, fluorine groups, and unsaturated double bonds is obtained through a condensation reaction of a diol and a diacid. Second, the polyester prepolymer is subjected to a free radical polymerization reaction with a polyether macromonomer and unsaturated carboxylic acid under the action of an oxidizing agent, a reducing agent, and a chain transfer agent to obtain the polycarboxylate superplasticizer. The multifunctional polycarboxylate superplasticizer prepared by this invention through condensation and free radical polymerization exhibits diverse functional groups, good weather resistance, and outstanding high-temperature resistance, demonstrating excellent fluidity, slump retention, and adaptability in concrete.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete additive, in particular to a multifunctional polycarboxylate superplasticizer and a preparation method thereof. BACKGROUND

[0002] Concrete is one of the most important raw materials in the building materials industry. With the development of the concrete industry, high-performance, high-strength, and environmentally friendly concrete is highly favored. Polycarboxylate superplasticizer is one of the indispensable raw materials for concrete, and its role in concrete cannot be ignored.

[0003] At present, polycarboxylate superplasticizer has become the largest amount of admixture used in the concrete industry. It is favored by the concrete industry because of its high water-reducing rate at low dosage. The introduction of carboxyl (-COOH), hydroxyl (-OH), sulfonic acid group (-SO3H), fluorine (-F) and other groups can effectively improve the fluidity of concrete, reduce water consumption, improve the compressive strength of concrete, improve the setting time of concrete, and reduce the viscosity of concrete.

[0004] However, due to the influence of complex and variable concrete construction process and large material fluctuation, ordinary polycarboxylate superplasticizer cannot meet the needs of modern concrete construction, and often needs to introduce functional monomers for modification or use compounded slump retaining superplasticizer, retarder, water-retaining thickening agent, early strength agent and other materials to meet the needs of on-site construction. SUMMARY

[0005] Therefore, it is necessary to provide a multifunctional polycarboxylate superplasticizer and a preparation method thereof to improve the fluidity and slump retention of concrete.

[0006] The multifunctional polycarboxylate superplasticizer of the present application, by weight, the preparation raw materials of the multifunctional polycarboxylate superplasticizer include:

[0007]

[0008]

[0009] Preferably, the preparation raw materials of the polyester prepolymer include:

[0010]

[0011] Preferably, the weight average molecular weight of the polycarboxylate superplasticizer is 20000-60000.

[0012] The present application also provides a preparation method of a multifunctional polycarboxylate superplasticizer, comprising the following steps:

[0013] The second reaction container is added with 5-20 parts of polyester prepolymer, 150-250 parts of polyether macromonomer and 150-450 parts of water by weight, and then solution A, solution B and solution C are added dropwise into the second reaction container respectively, the temperature is controlled at 20-50°C, and reaction is carried out for 0.5-3 hours to obtain the polycarboxylic acid water reducer;

[0014] The solution A comprises 0.5-5 parts of oxidizing agent and 10-50 parts of water.

[0015] The solution B comprises 0.2-2 parts of reducing agent, 0.5-5 parts of chain transfer agent and 10-50 parts of water.

[0016] The solution C comprises 10-30 parts of unsaturated carboxylic acid and 10-50 parts of water.

[0017] Preferably, the preparation method of the polyester prepolymer comprises the following steps:

[0018] The first reaction container is added with 50-150 parts of dihydric alcohol, 25-100 parts of diacid and 0.5-5 parts of condensing agent by weight, nitrogen is introduced to control the reaction temperature at 130-180°C, reaction is carried out for 3-6 hours, 5-15 parts of unsaturated capping agent is added, constant temperature reaction is carried out for 0.5-2 hours, and then excess small molecules are removed by distillation under reduced pressure to obtain the polyester prepolymer.

[0019] Preferably, the dihydric alcohol is at least one of C 2～10 2-10 diols, polyethylene glycol with a molecular weight of 200-1000.

[0020] Preferably, the diacid is at least two of C 2～10 2-10 disulfonic acids, C 2～10 2-10 dicarboxylic acids, sodium m-dibenzoate-5-sulfonic acid, 4-bromophthalic acid, 5-sulfonic acid-based phthalic acid monolithium salt, 4-hydroxyphthalic acid, 5-hydroxyphthalic acid, 5-fluorophthalic acid.

[0021] Preferably, the unsaturated capping agent is at least one of acrylic acid, methacrylic acid, tetramethyldivinyl disiloxane, vinyl dichlorosilane, acetyl chloride, acryloyl chloride.

[0022] Preferably, the condensing agent is at least one of hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, pyrophosphoric acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, stannous octoate, n-titanium butylate and titanium isopropylate.

[0023] Preferably, the polyether macromonomer is at least one of isobutylene polyoxyethylene ether, isoamylenic polyoxyethylene ether, end-vinyl polyoxyethylene ether, and the weight average molecular weight thereof is 2400-6000.

[0024] Preferably, the unsaturated acid is at least one selected from acrylic acid, methacrylic acid, fumaric acid, hydroxyethyl acrylate, and hydroxypropyl acrylate.

[0025] The beneficial effects of the polycarboxylate superplasticizer for concrete of the present invention:

[0026] Compared with the prior art, in the polycarboxylate superplasticizer of the present invention, water is used as the medium, and under the action of oxidant, reducing agent and chain transfer agent, polyester prepolymer, polyether macromonomer and unsaturated carboxylic acid undergo free radical copolymerization reaction to obtain polycarboxylate superplasticizer.

[0027] Polyester prepolymers contain functional groups such as hydroxyl (-OH), sulfonic acid (-SO3H), fluorine (-F), ester (-COO-), and carbon-carbon double bonds (-C=C-). Among these, the hydroxyl (-OH) groups in polyester prepolymers have good dispersibility and wetting properties; the sulfonic acid (-SO3H) groups have good dispersibility and early strength properties; the fluorine (-F) groups have extremely high electronegativity and good dispersibility; and the ester (-COO-) groups slowly release carboxyl (-COOH) and hydroxyl (-OH) groups under the alkaline conditions of concrete. Since the sulfonic acid (-SO3H) groups have better adsorption capacity than the carboxyl groups, the sulfonic acid groups are adsorbed by cement, sand, and other concrete admixtures before the carboxyl groups, thereby reducing the amount of carboxyl groups adsorbed by cement, sand, and other concrete admixtures. This not only ensures the water-reducing performance of polycarboxylate superplasticizers but also improves the fluidity and slump retention of concrete containing polycarboxylate superplasticizers. Therefore, even under conditions such as poor aggregate gradation and extreme construction environments, concrete mixed with the polycarboxylate superplasticizer of this invention can still have good fluidity, slump retention and adaptability. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the experimental materials and reagents used in the following examples are commercially available. All quantitative experiments in the following examples were performed in triplicate, and the data are the average of the three replicates or the average ± standard deviation.

[0030] Furthermore, the term "and / or" in the text includes three solutions. Taking A and / or B as an example, it includes technical solution A, technical solution B, and technical solution that simultaneously satisfies both A and B. In addition, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0031] This invention provides a multifunctional polycarboxylate superplasticizer, comprising the following components in parts by weight:

[0032]

[0033] Compared with existing technologies, in the polycarboxylate superplasticizer of this invention, water is used as the medium, and under the action of oxidizing agents, reducing agents, and chain transfer agents, polyester prepolymer, polyether macromonomer, and unsaturated carboxylic acid undergo a free radical copolymerization reaction to obtain the polycarboxylate superplasticizer. The polyester prepolymer contains functional groups such as hydroxyl (-OH), sulfonic acid (-SO3H), fluorine (-F), ester (-COO-), and carbon-carbon double bonds (-C=C-). Among these, the hydroxyl (-OH) groups in the polyester prepolymer have good dispersibility and wetting properties; the sulfonic acid (-SO3H) groups have good dispersibility and early strength effect; the fluorine-containing groups (-F) have extremely high electronegativity and good dispersibility; and the ester (-COO-) groups slowly release carboxyl (-COOH) and hydroxyl (-OH) groups under the alkaline conditions of concrete, which can better improve the fluidity and slump retention of concrete.

[0034] Because sulfonic acid groups (-SO3H) have a better adsorption capacity than carboxyl groups, sulfonic acid groups are adsorbed by cement, sand, and other concrete admixtures before carboxyl groups. This reduces the amount of carboxyl groups adsorbed by cement, sand, and other concrete admixtures, ensuring not only the water-reducing performance of the polycarboxylate superplasticizer but also improving the fluidity and slump retention of the concrete incorporating the polycarboxylate superplasticizer. Therefore, even under conditions such as poor aggregate gradation in the concrete and extreme construction environments, concrete incorporating the polycarboxylate superplasticizer of this invention can still exhibit good fluidity, slump retention, and adaptability.

[0035] In some embodiments, the polycarboxylate superplasticizer has a weight-average molecular weight of 20,000 to 60,000, so that the polycarboxylate superplasticizer of the present invention has excellent water-reducing performance and improves the fluidity, slump retention and adaptability of concrete mixed with the polycarboxylate superplasticizer of the present invention.

[0036] This invention also provides a method for preparing a multifunctional polycarboxylate superplasticizer, comprising the following steps:

[0037] (1) By weight, 50-150 parts of diol, 25-100 parts of diacid, and 0.5-5 parts of condensing agent are placed in the first reaction vessel. Nitrogen gas is introduced to control the reaction temperature at 130-180℃. The reaction is carried out for 3-6 hours. Then, 5-15 parts of unsaturated end-capping agent are added and the reaction is carried out at a constant temperature for 0.5-2 hours. After removing excess small molecules by vacuum distillation, polyester prepolymer is obtained.

[0038] (2) By weight, 5-20 parts of polyester prepolymer, 150-250 parts of polyether macromonomer, and 150-450 parts of water are added to the second reaction vessel. Then, solutions A, B, and C are added dropwise to the second reaction vessel respectively. The temperature is controlled at 20-50°C, and the reaction is carried out for 0.5-3 hours to obtain polycarboxylate superplasticizer.

[0039] The solution A comprises 0.5 to 5 parts of oxidant and 10 to 50 parts of water;

[0040] Solution B comprises 0.2 to 2 parts reducing agent, 0.5 to 5 parts chain transfer agent, and 10 to 50 parts water;

[0041] The solution C comprises 10-30 parts of unsaturated carboxylic acid and 10-50 parts of water.

[0042] In the preparation method of this invention, water is used as the medium, and under the action of oxidant, reducing agent, and chain transfer agent, polyester prepolymer, polyether macromonomer, and unsaturated carboxylic acid undergo a free radical copolymerization reaction to obtain polycarboxylic acid water-reducing agent. This results in the prepared polycarboxylic acid water-reducing agent having groups such as hydroxyl (-OH), sulfonic acid (-SO3H), fluorine (-F), and ester (-COO-). During the concrete admixture process, the polyhydroxyl (-OH) group has good dispersibility and wetting effect; the sulfonic acid (-SO3H) group has good dispersibility and early strength effect; the fluorine (-F) group has extremely strong electronegativity and good dispersibility; and the ester (-COO-) group slowly releases carboxyl (-COOH) and hydroxyl (-OH) groups under the alkaline action of concrete, which can better improve the fluidity and slump retention of concrete. Because sulfonic acid groups (-SO3H) have a better adsorption capacity than carboxyl groups, sulfonic acid groups are adsorbed by cement, sand, and other concrete admixtures before carboxyl groups. This reduces the amount of carboxyl groups adsorbed by cement, sand, and other concrete admixtures, ensuring not only the water-reducing performance of the polycarboxylate superplasticizer but also improving the fluidity, slump retention, and adaptability of concrete incorporating the polycarboxylate superplasticizer. Therefore, even under conditions of poor aggregate gradation and extreme construction environments, concrete incorporating the polycarboxylate superplasticizer of this invention can still exhibit good fluidity, slump retention, and adaptability.

[0043] The present invention discloses a method for preparing a polycarboxylic acid superplasticizer with multiple functional groups. The preparation process is simple, green, environmentally friendly and pollution-free.

[0044] In the preparation method of this invention, the reaction temperature is 20–50°C, which is the reaction temperature for the free radical copolymerization reaction. The reaction time is 0.5–3 hours to ensure that the free radical copolymerization reaction is complete, thereby increasing the yield of the polycarboxylate superplasticizer.

[0045] In some embodiments, in the preparation method of polycarboxylate superplasticizer for concrete, solutions A, B, and C are added dropwise to a second reaction vessel over a period of 0.5–3 hours. The addition of solutions A, B, and C to the second reaction vessel allows for continuous free radical copolymerization reactions between the second unsaturated acid and the polyether macromonomer and polyester prepolymer in the second reaction vessel under the action of an oxidizing agent, a reducing agent, and a chain transfer agent, thereby promoting the formation of the polycarboxylate superplasticizer. The 1–3 hour addition time ensures sufficient free radical copolymerization, thus improving the yield of the polycarboxylate superplasticizer with excellent water-reducing and flow properties.

[0046] In some of these embodiments, the method for preparing the polyester prepolymer includes the following steps:

[0047] By weight, 50-150 parts of diol, 25-100 parts of diacid, and 0.5-5 parts of condensing agent are placed in the first reaction vessel. Nitrogen gas is introduced to control the reaction temperature at 130-180℃, and the reaction is carried out for 3-6 hours. Then, 5-15 parts of unsaturated end-capping agent are added, and the reaction is carried out at a constant temperature for 0.5-2 hours. After removing excess small molecules by vacuum distillation, polyester prepolymer is obtained.

[0048] In the polyester prepolymer preparation method of the present invention, a diol and a diacid undergo an esterification reaction under the action of a condensing agent to obtain the polyester prepolymer. The temperature is 130–180°C to allow the diol and diacid to react, and excess small molecules are removed by vacuum distillation to obtain the polyester prepolymer. The reaction time is 3–6 hours to ensure sufficient polycondensation reaction, thereby increasing the yield of the prepared polyester prepolymer.

[0049] The method for preparing the polyester prepolymer of the present invention is simple, green, environmentally friendly and pollution-free.

[0050] In some embodiments, in the preparation method of the polyester prepolymer, 50-150 parts by weight of diol, 25-100 parts by weight of diacid and 0.5-5 parts by weight of condensing agent are placed in a first reaction vessel, nitrogen gas is introduced to control the reaction temperature at 130-180°C, and the reaction is carried out for 3-6 hours. Then, 5-15 parts by weight of unsaturated end-capping agent are added, and the reaction is carried out at a constant temperature for 0.5-2 hours. Excess small molecules are removed by vacuum distillation to facilitate the polycondensation reaction.

[0051] In some of these embodiments, the diol is C 2～10The polyester prepolymer is obtained by polycondensation reaction of excess diol and diol, with at least one of the following: diol and polyethylene glycol with a molecular weight of 200 to 1000.

[0052] In some of these embodiments, the diol is C 2～10 It is one of the glycols, or polyethylene glycol with a molecular weight of 200 to 1000. Such substances are beneficial for the synthesis of linear prepolymers.

[0053] In some embodiments of the diol, the dicarboxylic acid is C. 2～10 One of the disulfonic acids provides a sulfonic acid group (-SO3H), which is beneficial for polycondensation reaction with diols to produce sulfonate esters, which can effectively improve the dispersibility and slump retention of concrete.

[0054] In some of these embodiments, the dicarboxylic acid is C. 2～10 It is one of the dicarboxylic acids. The dicarboxylic acid provides a carboxyl group (-COOH), which is conducive to the condensation reaction with diol to form ester bonds (-COO-), which can effectively improve the dispersibility and slump retention of concrete.

[0055] In some of the embodiments, the dicarboxylic acid is one of sodium isophthalic acid-5-sulfonate, 5-nitroisophthalic acid, 4-bromoisophthalic acid, or 5-sulfonic isophthalic acid monolithium salt, which provides a benzene ring and a sulfonic acid group (-SO3H), which is beneficial for polycondensation reaction with diols, plays a stabilizing role in the reaction, and can effectively improve the dispersibility and slump retention of concrete.

[0056] In some of the embodiments, the dicarboxylic acid is one of 4-hydroxyisophthalic acid, 5-hydroxyisophthalic acid, and 5-fluoroisophthalic acid, which provides a hydroxyl group (-OH) and a fluorine-containing group (-F). The hydroxyl group (-OH) has a wetting effect, and the fluorine group (-F) has strong electronegativity and good dispersibility.

[0057] In some of these embodiments, the unsaturated end-capping agent is one of acrylic acid, methacrylic acid, tetramethyldivinyldisiloxane, vinyldichlorosilane, acetyl chloride, and acryloyl chloride, which provides an unsaturated double bond (-C=C-).

[0058] In some embodiments, the condensing agent is at least one selected from hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, pyrophosphate, p-toluenesulfonic acid, trifluoromethanesulfonic acid, stannous octoate, butyl titanate, and isopropyl titanate. The condensing agent provides electron donors to improve the conversion efficiency of the condensation reaction between the diol and the diacid, thereby promoting the formation of the polyester prepolymer.

[0059] In some embodiments, the polyether macromonomer is at least one selected from allyl polyoxyethylene ether, isobutyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, and 4-hydroxybutyl vinyl ether. Under the action of an oxidizing agent, a reducing agent, and a chain transfer agent, a polycarboxylate superplasticizer with excellent water-reducing properties, excellent flow properties, and good slump retention is obtained through free radical copolymerization of the carbon-carbon double bonds of the polyether macromonomer with the polyester prepolymer and unsaturated carboxylic acid.

[0060] In some of these embodiments, the unsaturated carboxylic acid is at least one of acrylic acid, methacrylic acid, fumaric acid, hydroxyethyl acrylate, and hydroxypropyl acrylate, to promote the free radical copolymerization reaction of polyester prepolymer and polyether macromonomer to obtain a polycarboxylic acid water-reducing agent with excellent water-reducing properties, excellent flow properties, and good slump retention properties.

[0061] In some embodiments, the oxidant is at least one of hydrogen peroxide, sodium peroxide, tert-butyl hydrogen peroxide, and persulfate. The oxidant lowers the activation energy of the reaction by undergoing a redox reaction with the reducing agent, thereby initiating a free radical copolymerization reaction of polyester prepolymer, polyether macromonomer, and unsaturated carboxylic acid, thus obtaining a polycarboxylic acid water-reducing agent with excellent water-reducing properties, excellent flow properties, and good slump retention.

[0062] In some of the embodiments, the reducing agent is at least one of ascorbic acid, sodium formaldehyde sulfoxylate, sodium phosphite and ferrous sulfate. By combining the reducing agent with the oxidizing agent, the reaction efficiency of the free radical copolymerization reaction of polyester prepolymer, polyether macromonomer and unsaturated carboxylic acid is improved, thereby obtaining a polycarboxylic acid water-reducing agent with excellent water-reducing properties, excellent flow properties and good slump retention.

[0063] In some embodiments, the chain transfer agent is at least one of mercapto alcohols and mercapto acids with carbon chain lengths of C2 to C6, which causes chain transfer in the free radical copolymerization reaction of polyester prepolymer, polyether macromonomer and first unsaturated acid, so as to adjust the relative molecular mass of polycarboxylate superplasticizer obtained by free radical copolymerization reaction, thereby obtaining a polycarboxylate superplasticizer with excellent water reduction performance, excellent flow performance and good slump retention performance.

[0064] In some of these embodiments, the water may be, but is not limited to, deionized water.

[0065] The technical solution of the present invention will be further described below with reference to preferred embodiments.

[0066] Example 1:

[0067] Preparation of polyester prepolymer:

[0068] By weight, 50 parts of ethylene glycol, 20 parts of oxalic acid, 5 parts of sodium dibenzoate-5-sulfonate, and 0.5 parts of hydrochloric acid were placed in the first reaction vessel. Nitrogen gas was introduced to control the reaction temperature at 130°C, and the reaction was carried out for 3 hours. Then, 5 parts of acrylic acid were added, and the reaction was carried out at a constant temperature for 0.5 hours. After removing excess small molecules by vacuum distillation, polyester prepolymer was obtained.

[0069] Preparation of a multifunctional polycarboxylic acid superplasticizer:

[0070] By weight, 5 parts of polyester prepolymer, 150 parts of allyl polyoxyethylene ether and 130 parts of water were added to the second reaction vessel. Then, solutions A, B and C were added dropwise to the second reaction vessel over a period of 1 hour, and the temperature was controlled at 20°C. The mixture was then kept at a constant temperature for 0.5 hours to obtain a colorless and transparent or light yellow transparent liquid with a solid content of 50%, which is the polycarboxylate superplasticizer. The weight-average molecular weight of the obtained polycarboxylate superplasticizer is 34,000 to 38,000.

[0071] Solution A consists of 0.5 parts hydrogen peroxide and 10 parts water;

[0072] Solution B comprises 0.1 parts sodium phosphite and 10 parts water;

[0073] Solution C comprises 0.5 parts mercaptoacetic acid, 5 parts acrylic acid, and 10 parts water.

[0074] Example 2

[0075] Preparation of a polyester prepolymer:

[0076] By weight, 80 parts of hexanediol, 20 parts of 1,3-propanedisulfonic acid, 20 parts of adipic acid, 5 parts of 5-sulfonic isophthalic acid monolithium salt, and 1.5 parts of sulfuric acid were placed in the first reaction vessel. Nitrogen gas was introduced to control the reaction temperature at 140°C, and the reaction was carried out for 4 hours. Then, 7 parts of methacrylic acid were added, and the reaction was carried out at a constant temperature for 1 hour. After removing excess small molecules by vacuum distillation, the polyester prepolymer was obtained.

[0077] Preparation of a multifunctional polycarboxylic acid superplasticizer:

[0078] By weight, 10 parts of polyester prepolymer, 180 parts of isopentenyl polyoxyethylene ether and 140 parts of water were added to the second reaction vessel. Then, solutions A, B and C were added dropwise to the second reaction vessel over a period of 2 hours, and the temperature was controlled at 30°C. The mixture was then kept at a constant temperature for 1 hour to obtain a colorless and transparent or light yellow transparent liquid with a solid content of 50%, which is the polycarboxylate superplasticizer. The weight-average molecular weight of the obtained polycarboxylate superplasticizer is 38,000 to 42,000.

[0079] Solution A comprises 0.95 parts ammonium persulfate and 20 parts water;

[0080] Solution B consists of 0.2 parts ascorbic acid and 20 parts water;

[0081] Solution C comprises 0.55 parts mercaptoethanol, 8 parts acrylic acid and hydroxypropyl acrylate (the mass ratio of acrylic acid to hydroxypropyl acrylate is 3:1), and 20 parts water.

[0082] Example 3

[0083] Preparation of a polyester prepolymer:

[0084] By weight, 110 parts of (1,4-butanediol: polyethylene glycol with a molecular weight of 200 = 1:1), 50 parts of sebacic acid, 20 parts of 4-hydroxyisophthalic acid, and 3 parts of sulfuric acid were placed in the first reaction vessel. Nitrogen gas was introduced to control the reaction temperature at 150°C, and the reaction was carried out for 5 hours. Then, 9 parts of tetramethyldivinyldisiloxane were added, and the reaction was carried out at a constant temperature for 1.5 hours. After removing excess small molecules by vacuum distillation, the polyester prepolymer was obtained.

[0085] Preparation of a multifunctional polycarboxylic acid superplasticizer:

[0086] By weight, 15 parts of polyester prepolymer, 200 parts of 4-hydroxybutyl vinyl ether and 125 parts of water were added to the second reaction vessel. Then, solutions A, B and C were added dropwise to the second reaction vessel over a period of 3 hours, and the temperature was controlled at 40°C. The mixture was then kept at a constant temperature for 1.5 hours to obtain a colorless transparent or light yellow transparent liquid with a solid content of 50%, which is the polycarboxylate superplasticizer. The weight-average molecular weight of the obtained polycarboxylate superplasticizer was 42,000 to 46,000.

[0087] Solution A comprises 1.1 parts ammonium persulfate and 30 parts water;

[0088] Solution B comprises 0.4 parts sodium methyl methacrylate and 30 parts water;

[0089] Solution C comprises 1.2 parts mercaptopropionic acid, 11 parts methacrylic acid and hydroxyethyl acrylate (the mass ratio of methacrylic acid to hydroxyethyl acrylate is 3:2), and 30 parts water.

[0090] Example 4

[0091] Preparation of a polyester prepolymer:

[0092] By weight, 130 parts of 1,5-pentanediol, 50 parts of (adipic acid: 1,2-ethanesulfonic acid), 20 parts of 5-hydroxyisophthalic acid, and 4 parts of trifluoromethanesulfonic acid were placed in the first reaction vessel. Nitrogen gas was introduced to control the reaction temperature at 160°C, and the reaction was carried out for 5 hours. Then, 11 parts of acryloyl chloride were added, and the reaction was carried out at a constant temperature for 2 hours. After removing excess small molecules by vacuum distillation, polyester prepolymer was obtained.

[0093] Preparation of a multifunctional polycarboxylic acid superplasticizer:

[0094] By weight, 18 parts of polyester prepolymer, 240 parts of isobutyl polyoxyethylene ether and 151 parts of water were added to the first reaction vessel. Then, solutions A, B and C were added dropwise to the first reaction vessel over a period of 3 hours, and the temperature was controlled at 45°C. The mixture was then kept at a constant temperature for 2 hours to obtain a colorless and transparent or light yellow transparent liquid with a solid content of 50%, which is the polycarboxylate superplasticizer. The weight-average molecular weight of the obtained polycarboxylate superplasticizer was 46,000 to 50,000.

[0095] Solution A consists of 1.5 parts hydrogen peroxide and 40 parts water;

[0096] Solution B consists of 0.6 parts ferrous sulfate and 40 parts water;

[0097] Solution C comprises 1 part mercaptopropanol, 14 parts methacrylic acid and fumaric acid (the mass ratio of methacrylic acid to fumaric acid is 5:2) and 40 parts water.

[0098] Example 5

[0099] Preparation of a polyester prepolymer:

[0100] By weight, 150 parts of (ethylene glycol: polyethylene glycol with a molecular weight of 400 = 9:1), 60 parts of succinic acid, 15 parts of 1,3-propanedisulfonic acid, 5 parts of 5-fluoroisophthalic acid, and 5 parts of p-toluenesulfonic acid were placed in the first reaction vessel. Nitrogen gas was introduced to control the reaction temperature at 170°C, and the reaction was carried out for 5 hours. Then, 15 parts of vinyl dichlorosilane were added, and the reaction was carried out at a constant temperature for 2 hours. After removing excess small molecules by vacuum distillation, the polyester prepolymer was obtained.

[0101] Preparation of a multifunctional polycarboxylic acid superplasticizer:

[0102] By weight, 20 parts of polyester prepolymer, 250 parts of allyl polyoxyethylene ether and 133 parts of water were added to the first reaction vessel. Then, solutions A, B and C were added dropwise to the first reaction vessel over a period of 3 hours, and the temperature was controlled at 50°C. The mixture was then kept at a constant temperature for 2 hours to obtain a colorless transparent or light yellow transparent liquid with a solid content of 50%, which is the polycarboxylate superplasticizer. The weight-average molecular weight of the obtained polycarboxylate superplasticizer was 54,000 to 56,000.

[0103] Solution A consists of 5 parts hydrogen peroxide and 50 parts water;

[0104] Solution B consists of 1 part sodium formaldehyde sulfoxylate and 50 parts water;

[0105] Solution C comprises 5 parts mercaptoacetic acid, 15 parts fumaric acid and hydroxyethyl acrylate (mass ratio of fumaric acid to hydroxyethyl acrylate is 2:5) and 50 parts water.

[0106] Comparative Example 1

[0107] The other steps are the same as in Example 1, except that ethylene glycol is not added when preparing the polyester prepolymer.

[0108] Comparative Example 2

[0109] The other steps are the same as in Example 1, except that oxalic acid is not added when preparing the polyester prepolymer.

[0110] Comparative Example 3

[0111] The other steps are the same as in Example 1, except that sodium dibenzoate-5-sulfonate is not added when preparing the polyester prepolymer.

[0112] Performance Experiment:

[0113] The experimental materials are as follows:

[0114] Cement: Conch Cement P.O42.5; Manufactured sand: Produced locally in Guizhou; Crushed stone: Produced locally in Guizhou; Comparative example: JSJ-01 water-reducing agent sold by a company in Guizhou, 18% solid content.

[0115] The detailed information on manufactured sand is shown in Table 1 below:

[0116] Table 1. Detailed Information on Manufactured Sand

[0117]

[0118] The details of the crushed stone are shown in Table 2 below.

[0119] Table 2. Detailed Information on Crushed Stone

[0120]

[0121] Using JSJ-01, a commercially available water-reducing agent from a Guizhou company, as Comparative Example 4, Comparative Examples 1-4 and Examples 1-5 were uniformly formulated to achieve an 18% solid content for concrete verification. Concrete performance tests were conducted according to GB 8076-2008 "Concrete Admixtures." Samples from Comparative Examples 1-4 and Examples 1-5 were subjected to concrete tests, and the flowability and compressive strength of concrete containing the comparative examples and Examples 1-5 were compared.

[0122] The proportions are shown in Table 3.

[0123] Table 3 Experimental concrete mix proportions (kg / m³) 3

[0124]

[0125] Concrete testing and evaluation were conducted according to the national standard GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" and the tests were performed according to GB8076-2008 "Concrete Admixtures". The measured data are shown in Table 4.

[0126] Table 4 Concrete Experiments

[0127]

[0128] As shown in Table 4, in the comparative example, the initial slump of the concrete was 200 mm, the spread was 535 mm, the slump after 2 hours was 180 mm, and the spread after 2 hours was 470 mm. In Examples 1 to 5, compared with the comparative example, the initial slump and initial spread of Examples 1 to 5 were better than those of the comparative example, and the slump and spread after 2 hours of Examples 1 to 5 were also better than those of the comparative example. This indicates that the concrete containing Examples 1 to 5 has good fluidity and good slump retention.

[0129] In summary, the polyester in the polycarboxylate superplasticizer of this invention exhibits structural diversity. Different structural polycarboxylate superplasticizers are obtained through free radical copolymerization reactions of polyester oligomers with polyether macromonomers and unsaturated carboxylic acids under the action of oxidants, reducing agents, and chain transfer agents. This allows them to adapt to the adverse effects of complex and variable concrete construction processes and large material fluctuations. Polyester oligomers improve the slump retention and flowability of concrete. Furthermore, polycarboxylate superplasticizers obtained through free radical copolymerization reactions of polyester oligomers with different molecular structures with polyether macromonomers and unsaturated carboxylic acids under the action of oxidants, reducing agents, and chain transfer agents can more effectively improve the compatibility and reactivity between various substances in concrete. The polycarboxylate superplasticizer of this invention demonstrates excellent performance and superior flowability, slump retention, and adaptability in concrete.

[0130] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A polynuclear polycarboxylic acid water reducing agent, characterized by, The raw materials for preparing the multi-functional polycarboxylic acid water reducing agent include, in parts by weight: The raw materials for preparing the polyester prepolymer include: The polyether macro-monomer is at least one of allyl polyoxyethylene ether, isobutyl polyoxyethylene ether, isoamyl polyoxyethylene ether, and 4-hydroxybutyl vinyl ether; The unsaturated carboxylic acid is at least one of acrylic acid, methacrylic acid, fumaric acid, hydroxyethyl acrylate, and hydroxypropyl acrylate; The polyester prepolymer has the following structural formula: wherein a, b, and c are the polymerization degrees, b > a + c, a is an integer of 3-5, b is an integer of 10-20, and c is an integer of 3-5; R is H or CH3; M1 is C=O, Si(OH)2, or Si(CH3)2; M2 is S=O or C; M3 is located at the 4th and / or 5th position of the benzene ring and is SO3Na, SO3Li, Br, F, and / or OH.

2. The polycarboxylic acid superplasticizer according to claim 1, wherein The polycarboxylic acid water reducing agent has a weight average molecular weight of 20,000-60,000.

3. The polycarboxylic acid superplasticizer according to claim 1, wherein Diols are C 2～10 At least one of glycols and polyethylene glycols with a molecular weight of 200 to 1000.

4. The polycarboxylic acid superplasticizer according to claim 1, wherein The dicarboxylic acid is C. 2～10 disulfonic acid, C 2～10 At least two of the following: dicarboxylic acid, sodium m-benzoic acid-5-sulfonate, 4-bromoisophthalic acid, lithium monosulfonic acid of 5-sulfonic acid, 4-hydroxyisophthalic acid, 5-hydroxyisophthalic acid, and 5-fluoroisophthalic acid.

5. The polycarboxylic acid superplasticizer according to claim 1, wherein The unsaturated end-capping agent is at least one of acrylic acid, methacrylic acid, tetramethyldivinyl disiloxane, vinyl dichlorosilane, and acryloyl chloride.

6. The polycarboxylic acid superplasticizer according to claim 1, wherein The condensing agent is at least one of hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, pyrophosphoric acid, p-toluene sulfonic acid, trifluoromethanesulfonic acid, stannous octoate, n-butyll titanate, and isopropyl titanate.

7. A method for producing a polifunctional polymeric carboxylic acid water reducer as claimed in any one of claims 1 to 6, characterized by, The method for preparing the polycarboxylic acid water reducing agent includes the following steps: The dihydric alcohol, dihydric acid, and condensing agent are put into a first reaction container, nitrogen is introduced to control the reaction temperature to be 130-180°C, and the reaction is carried out for 3-6 hours, the unsaturated end-capping agent is added, the constant temperature reaction is carried out for 0.5-2 hours, and the polyester prepolymer is obtained after removing the excess small molecules by reduced pressure distillation; The polyester prepolymer, polyether macro-monomer, and water are put into a second reaction container, solution A, solution B, and solution C are added dropwise into the second reaction container respectively, the temperature is controlled to be 20-50°C, and the reaction is carried out for 0.5-3 hours to obtain the polycarboxylic acid water reducing agent; The solution A includes an oxidizing agent and water; The solution B includes a reducing agent, a chain transfer agent, and water; The solution C includes an unsaturated carboxylic acid and water.

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