Self-assembly method and application of ester polycarboxylate water reducer and gamma-cyclodextrin

Abstract

The invention relates to the technical field of concrete admixtures, and discloses a self-assembly method of an ester polycarboxylate water reducer and gamma-cyclodextrin and an application thereof. Firstly, acrylic acid and methacrylic acid are used to generate a polyacrylic acid prepolymer under a redox system; at a water temperature of 60 DEG C, the polyacrylic acid prepolymer is added to a saturated solution of gamma-cyclodextrin, reacted for 1 hour, and then cooled to room temperature; then, an inclusion compound formed by self-assembly of gamma-cyclodextrin and the polyacrylic acid prepolymer is subjected to esterification reaction with polyethylene glycol monomethyl ether at a temperature of 105-120 DEG C for 4-6 hours; finally, an appropriate amount of water and a sodium carbonate solution are added to neutralize the mixture to obtain a self-assembly product of gamma-cyclodextrin and the ester polycarboxylate water reducer. The ester polycarboxylate water reducer has good workability when applied to water-washed sand, is insensitive to dosage, has excellent slump-retaining performance without compounding a slump-retaining agent within a reasonable dosage range, greatly saves the cost of polycarboxylate mother liquor, and has a significant viscosity-reducing effect when applied to high-strength concrete.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, and in particular to a self-assembly method of an ester polycarboxylate water reducer and gamma-cyclodextrin and an application thereof. Background Art

[0002] In recent years, ether polycarboxylate water reducers have been welcomed by manufacturers and users due to their convenient raw material supply, simple production process and stable products. However, the application of machine-made sand is constantly consumed, and many projects use washed sand to replace machine-made sand. The application of ether polycarboxylate water reducers in concrete is becoming more and more difficult. It is sensitive to the dosage in washed sand. Because the relatively fine components in washed sand are washed away, the concrete produced using it is prone to problems such as segregation and bleeding. The concrete has poor workability and poor slump retention. Compared with ether polycarboxylate water reducers, ester polycarboxylate water reducers have low dosage sensitivity and good concrete workability. Therefore, the use of ester polycarboxylate water reducers in coastal areas is better than that of ether polycarboxylate water reducers. In addition, when ether polycarboxylate water reducers are used in high-strength and high-grade concrete, there are technical difficulties such as slow reaction, high concrete viscosity, and difficulty in pumping high-rise buildings. The use of ester polycarboxylate water reducers can reduce the viscosity of concrete to achieve pumping.

[0003] Patent No. CN201911165236.X discloses a method for preparing an ester polycarboxylate water reducer. This method mainly focuses on the air entrainment and foam stabilization effect, and the collapse protection performance has not been improved. Patent No. CN 105778023 A discloses a method for preparing a sulfonated cyclodextrin polycarboxylate water reducer. The cyclodextrin sulfonation product is esterified with maleic anhydride and then grafted to the side chain of the polycarboxylate water reducer. This method uses a sulfonation reaction, which has high energy consumption and is not conducive to production. Patent No. CN201710038165.1 discloses a method for preparing a modified cyclodextrin self-assembly type ether polycarboxylate water reducer, which focuses on introducing lipophilic small monomers to improve the adaptability of polycarboxylate water reducer in concrete.

[0004] The above disclosed technologies all modify the polycarboxylate water-reducing agent with different focuses, and the reaction cost is increased by means of modifying cyclodextrin, which is not conducive to large-scale production. Summary of the invention

[0005] The present invention aims to provide a self-assembly method of an ester polycarboxylate water reducer and gamma-cyclodextrin and its application, so as to solve the problems of poor neutralization property of washed sand, insufficient slump retention performance and reduced concrete viscosity in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical scheme: a self-assembled inclusion compound of an ester polycarboxylate water reducer and γ-cyclodextrin, the general structural formula of which is shown in formula (I):

[0007] In formula (I), X, Y, and Z are the degrees of polymerization and are all positive integers, X=40-100, Y=20-50, Z=17-30, and n=13, 23, or 44.

[0008] On the other hand, the present technical solution provides a self-assembly method of an ester polycarboxylate water reducer and γ-cyclodextrin, comprising the following steps:

[0009] Step 1: dissolving acrylic acid in water to prepare a mixed solution A of acrylic acid, methacrylic acid and water; mixing a reducing agent, a chain transfer agent and water to prepare a mixed solution B; and heat-retaining an oxidant, the A solution and the B solution to obtain a viscous polymer liquid polyacrylic acid;

[0010] Step 2: Under elevated temperature conditions, dissolving γ-cyclodextrin in water to obtain a saturated aqueous solution of γ-cyclodextrin, adding polyacrylic acid and stirring to react to obtain a γ-cyclodextrin / polyacrylic acid inclusion complex;

[0011] Step 3: Add the pre-dissolved polyethylene glycol monomethyl ether and the catalyst p-toluenesulfonic acid to the γ-cyclodextrin / polyacrylic acid inclusion complex prepared in step 2, and stir to react to obtain a self-assembled inclusion complex of the ester polycarboxylic acid water reducer and γ-cyclodextrin.

[0012] Preferably, as an improvement, in step 1, the molar ratio of acrylic acid to methacrylic acid is 3-2:1.

[0013] In the present technical solution, the addition ratio of acrylic acid to methacrylic acid has a great influence on the water reduction rate of the water reducer. Too little addition of acrylic acid will lead to a low water reduction rate of the self-assembled inclusion complex of the ester polycarboxylic acid water reducer and γ-cyclodextrin. Too much addition of acrylic acid will lead to a high water reduction rate and the collapse retention performance of the ester polycarboxylic acid water reducer will deteriorate.

[0014] Preferably, as an improvement, in step 1, the oxidant is one or a combination of hydrogen peroxide and persulfate, and the amount of the oxidant added is 2-4% of the total mass of acrylic acid and methacrylic acid.

[0015] In the technical solution, the oxidant and the reductant form a redox system, which allows the free radical polymerization to react at room temperature.

[0016] Preferably, as an improvement, in step one, the reducing agent is at least one of Vc, bleaching powder, E51, and sodium bisulfite, and the amount of the reducing agent added is 15-20% of the mass of the oxidant.

[0017] Preferably, as an improvement, in step one, the chain transfer agent is at least one of thioglycolic acid, mercaptopropionic acid, mercaptoethanol, sodium hypophosphite, and sodium methyl methacrylate sulfonate, and the added amount of the chain transfer agent is 0.8-1.2% of the total mass of acrylic acid and methacrylic acid.

[0018] In the technical solution, the chain transfer agent can adjust the molecular weight and molecular weight distribution of the ester polycarboxylate water reducer, and the molecular weight and molecular weight distribution affect the performance of the self-assembled inclusion complex of the ester polycarboxylate water reducer and γ-cyclodextrin.

[0019] Preferably, as an improvement, in step 2, the molar ratio of polyacrylic acid to γ-cyclodextrin is 1 to 2:1; the heating temperature is 60° C., and the stirring reaction time is 1 h.

[0020] Preferably, as an improvement, in step three, the acid-ether ratio of acrylic acid and methacrylic acid to polyethylene glycol monomethyl ether is 3.5-5:1; and the added amount of the catalyst p-toluenesulfonic acid accounts for 1-2% of the total mass of polyacrylic acid and polyethylene glycol monomethyl ether.

[0021] Preferably, as an improvement, in step three, the polyethylene glycol monomethyl ether is one or a combination of two or more having a degree of polymerization of 13, 23, or 44.

[0022] In the technical solution, the polymerization degree of polyethylene glycol monomethyl ether can affect the side chain distribution of the self-assembled inclusion complex of ester polycarboxylate water reducer and γ-cyclodextrin, and the side chain distribution affects the water reduction rate and collapse retention performance of the self-assembled inclusion complex of ester polycarboxylate water reducer and γ-cyclodextrin.

[0023] Preferably, as an improvement, a self-assembled inclusion complex of an ester polycarboxylate water-reducing agent and γ-cyclodextrin is used in the preparation of a concrete slump-reducing agent.

[0024] The principles and advantages of this solution are:

[0025] 1. In the self-assembly of an ester polycarboxylate water-reducing agent and γ-cyclodextrin provided by the technical solution, γ-cyclodextrin presents a hollow truncated cone cavity structure in space, which can embed guest molecules. The present invention includes part of the carboxyl groups on the molecular chain of the polycarboxylate water-reducing agent by γ-cyclodextrin, and when the γ-cyclodextrin is high pH in the concrete, it slowly falls off the carboxyl groups of the guest molecular chain, so that the carboxyl groups are slowly released, thereby achieving a sustained release effect, and further enhancing the slump retention performance of the polycarboxylate water-reducing agent in concrete.

[0026] 2. The technical solution forms polyacrylic acid by first polymerizing and then forming an inclusion complex with γ-cyclodextrin. Since γ-cyclodextrin exists in the side chain, the esterification reaction with polyethylene glycol monomethyl ether is meta-esterification, so that the molecular weight distribution has a regular sequence, showing excellent water reduction rate and slump retention performance.

[0027] 3. This technical solution uses a method of uniformly dropping polyethylene glycol monomethyl ether, which results in a mild reaction and a high esterification rate, thereby improving the water reduction rate and slump retention performance.

[0028] 4. The γ-cyclodextrin used in this technical solution does not need to be modified, and the self-assembly product is easy to prepare, giving the polycarboxylic acid water reducer excellent slump-retaining performance; there is no need to compound the slump-retaining agent in engineering applications, thereby achieving the purpose of saving mother liquor costs. DETAILED DESCRIPTION

[0029] The following is further described in detail through specific implementations, but the implementation of the present invention is not limited thereto. Unless otherwise specified, the technical means used in the following implementations are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; the materials, reagents, etc. used can all be obtained from commercial channels.

[0030] Program Overview:

[0031] A self-assembled inclusion compound of an ester polycarboxylate water-reducing agent and γ-cyclodextrin, the general structural formula of which is shown in formula (I):

[0032] In formula (I), X, Y, and Z are the degrees of polymerization and are all positive integers, X=40-100, Y=20-50, Z=17-30, and n=13, 23, or 44.

[0033] A method for self-assembly of an ester polycarboxylate water-reducing agent and γ-cyclodextrin comprises the following steps:

[0034] Step 1, preparation of polyacrylic acid prepolymer: add a certain amount of acrylic acid and water to the bottom of a 500 mL four-necked flask equipped with a stirrer, stir evenly at 25±2°C, prepare a mixed solution A of acrylic acid, methacrylic acid and water, prepare a mixed solution B of a reducing agent, a chain transfer agent and water, add an oxidant to the bottom of the kettle before adding A and B solutions, add A solution for 2 hours, and B solution for 2.5 hours, keep warm and react for 1 hour to obtain a viscous polymer liquid polyacrylic acid.

[0035] The oxidant is one of hydrogen peroxide and persulfate or a combination of the two.

[0036] The reducing agent is at least one of Vc, bleaching powder, E51 and sodium bisulfite.

[0037] The chain transfer agent is at least one of thioglycolic acid, mercaptopropionic acid, mercaptoethanol, sodium hypophosphite, and sodium methacrylic acid.

[0038] Step 2, preparation of γ-cyclodextrin / polyacrylic acid inclusion complex: dissolve a certain amount of γ-cyclodextrin in water and stir at 60°C to obtain a saturated aqueous solution of γ-cyclodextrin. Add the polyacrylic acid prepared in step 1 to the saturated solution of γ-cyclodextrin, stir for 1 hour, and then cool to room temperature to obtain a γ-cyclodextrin / polyacrylic acid inclusion complex.

[0039] Step 3, preparation of self-assembled inclusion complex of ester polycarboxylate water reducer and γ-cyclodextrin: add pre-dissolved polyethylene glycol monomethyl ether and catalyst p-toluenesulfonic acid to the γ-cyclodextrin / polyacrylic acid inclusion complex prepared in step 2; wherein polyethylene glycol monomethyl ether is added dropwise at a uniform speed for 1 hour, nitrogen is passed to remove water generated by the reaction, stirred at a temperature of 105-120 ° C for 4-6 hours, cooled to room temperature after the reaction, and added with appropriate amounts of water and sodium carbonate solution for neutralization to obtain a self-assembled inclusion complex of ester polycarboxylate water reducer and γ-cyclodextrin with a solid content of 50%.

[0040] Wherein, the polyethylene glycol monomethyl ether is one or a combination of two or more having a degree of polymerization of 13, 23, or 44.

[0041] The added amount of the catalyst p-toluenesulfonic acid accounts for 1% to 1.5% of the total mass of polyacrylic acid and polyethylene glycol monomethyl ether.

[0042] Example 1

[0043] A method for self-assembly of an ester polycarboxylate water-reducing agent and γ-cyclodextrin comprises the following steps:

[0044] Step 1, preparation of polyacrylic acid prepolymer: Add 4g of acrylic acid, 2g of methacrylic acid and 30g of water to the bottom of a 500 mL four-necked flask equipped with a stirrer and stir evenly at 25±2°C. 32g of acrylic acid, 18g of methacrylic acid and 7g of water are prepared into liquid A, 0.16g of Vc, 0.44g of thioglycolic acid and 20g of water are prepared into liquid B, 1.08g of hydrogen peroxide is added before adding liquid A and liquid B, after stirring for 10min, liquid A and liquid B are added dropwise, wherein liquid A is added dropwise for 2h, liquid B is added dropwise for 2.5h, and after keeping warm for 1h, a viscous polymer liquid polyacrylic acid prepolymer with a concentration of 50% is obtained.

[0045] Step 2: At 60°C, add 12.97 g of γ-cyclodextrin into a 500 mL flask and add water to prepare a saturated aqueous solution of γ-cyclodextrin. Then weigh 114 g of the polyacrylic acid prepolymer prepared in step 1 and add it to the saturated solution of γ-cyclodextrin. After stirring for 1 hour, cool to room temperature to prepare a γ-cyclodextrin / polyacrylic acid inclusion complex.

[0046] Step 3, (3) weigh 127 g of the γ-cyclodextrin / polyacrylic acid inclusion complex prepared in step 2 in a 500 mL flask, add 120 g of polyethylene glycol monomethyl ether with a degree of polymerization of 23 and 2.25 g of catalyst p-toluenesulfonic acid dissolved in advance, wherein the polyethylene glycol monomethyl ether is added dropwise at a uniform rate for 1 hour, and the water generated by the reaction is removed by nitrogen flow. The mixture is stirred at a temperature of 105° C. and allowed to react for 4 hours. After the reaction is completed, the mixture is cooled to room temperature, and water and sodium carbonate solution are added to neutralize the mixture to obtain a self-assembled inclusion complex of an ester polycarboxylic acid water reducer and γ-cyclodextrin with a solid content of 50%.

[0047] Example 2

[0048] A method for self-assembly of an ester polycarboxylate water-reducing agent and γ-cyclodextrin comprises the following steps:

[0049] Step 1, preparation of polyacrylic acid prepolymer: Add 4g of acrylic acid, 2g of methacrylic acid and 30g of water to the bottom of a 500 mL four-necked flask equipped with a stirrer and stir evenly at 25±2°C. 36g of acrylic acid, 18g of methacrylic acid and 13g of water are prepared into liquid A, 0.16g of Vc, 0.44g of thioglycolic acid and 20g of water are prepared into liquid B, 1.2g of hydrogen peroxide is added before adding liquid A and liquid B, after stirring for 10min, liquid A and liquid B are added dropwise, wherein liquid A is added dropwise for 2h, liquid B is added dropwise for 2.5h, and after keeping warm for 1h, a viscous polymer liquid polyacrylic acid prepolymer with a concentration of 50% is obtained.

[0050] Step 2: At 60°C, add 12.97 g of γ-cyclodextrin into a 500 mL flask and add water to prepare a saturated aqueous solution of γ-cyclodextrin. Then weigh 122 g of the polyacrylic acid prepolymer prepared in step 1 and add it to the saturated solution of γ-cyclodextrin. After stirring for 1 hour, cool to room temperature to prepare a γ-cyclodextrin / polyacrylic acid inclusion complex.

[0051] Step 3: weigh 135 g of the γ-cyclodextrin / polyacrylic acid inclusion complex prepared in step 2 in a 500 mL flask, add 120 g of polyethylene glycol monomethyl ether with a degree of polymerization of 23 and 2.25 g of catalyst p-toluenesulfonic acid dissolved in advance, wherein the polyethylene glycol monomethyl ether is added dropwise at a uniform rate for 1 hour, and the water generated by the reaction is removed by nitrogen gas. Stir and react for 4 hours at a temperature of 105 ° C. After the reaction, cool to room temperature, add water and sodium carbonate solution to neutralize to obtain an ester polycarboxylic acid water reducer and γ-cyclodextrin self-assembled inclusion complex with a solid content of 50%.

[0052] Example 3

[0053] A method for self-assembly of an ester polycarboxylate water-reducing agent and γ-cyclodextrin comprises the following steps:

[0054] Step 1, preparation of polyacrylic acid prepolymer: Add 4g of acrylic acid, 2g of methacrylic acid and 30g of water to the bottom of a 500 mL four-necked flask equipped with a stirrer and stir evenly at 25±2°C. 33g of acrylic acid, 21g of methacrylic acid and 7g of water are prepared into liquid A, 0.16g of Vc, 0.44g of thioglycolic acid and 20g of water are prepared into liquid B, 1.2g of hydrogen peroxide is added before adding liquid A and liquid B, after stirring for 10min, liquid A and liquid B are added dropwise, wherein liquid A is added dropwise for 2h, liquid B is added dropwise for 2.5h, and after keeping warm for 1h, a viscous polymer liquid polyacrylic acid prepolymer with a concentration of 50% is obtained.

[0055] Step 2: At 60°C, add 12.97 g of γ-cyclodextrin into a 500 mL flask and add water to prepare a saturated aqueous solution of γ-cyclodextrin. Then weigh 122 g of the polyacrylic acid prepolymer prepared in step 1 and add it to the saturated solution of γ-cyclodextrin. After stirring for 1 hour, cool to room temperature to prepare a γ-cyclodextrin / polyacrylic acid inclusion complex.

[0056] Step 3: weigh 127 g of the γ-cyclodextrin / polyacrylic acid inclusion complex prepared in step 2 in a 500 mL flask, add 120 g of polyethylene glycol monomethyl ether with a degree of polymerization of 23 and 2.25 g of catalyst p-toluenesulfonic acid dissolved in advance, wherein the polyethylene glycol monomethyl ether is added dropwise at a uniform rate for 1 hour, and the water generated by the reaction is removed by nitrogen gas. Stir and react for 4 hours at a temperature of 105 ° C. After the reaction, cool to room temperature, add water and sodium carbonate solution to neutralize to obtain an ester polycarboxylic acid water reducer and γ-cyclodextrin self-assembled inclusion complex with a solid content of 50%.

[0057] Example 4

[0058] A method for self-assembly of an ester polycarboxylate water-reducing agent and γ-cyclodextrin comprises the following steps:

[0059] Step 1, preparation of polyacrylic acid prepolymer: Add 4g of acrylic acid, 2g of methacrylic acid and 30g of water to the bottom of a 500 mL four-necked flask equipped with a stirrer and stir evenly at 25±2°C. 33g of acrylic acid, 21g of methacrylic acid and 7g of water are prepared into liquid A, 0.16g of Vc, 0.44g of thioglycolic acid and 20g of water are prepared into liquid B, 1.2g of hydrogen peroxide is added before adding liquid A and liquid B, after stirring for 10min, liquid A and liquid B are added dropwise, wherein liquid A is added dropwise for 2h, liquid B is added dropwise for 2.5h, and after keeping warm for 1h, a viscous polymer liquid polyacrylic acid prepolymer with a concentration of 50% is obtained.

[0060] Step 2: At 60°C, add 12.97 g of γ-cyclodextrin into a 500 mL flask and add water to prepare a saturated aqueous solution of γ-cyclodextrin. Then weigh 122 g of the polyacrylic acid prepolymer prepared in step 1 and add it to the saturated solution of γ-cyclodextrin. After stirring for 1 hour, cool to room temperature to prepare a γ-cyclodextrin / polyacrylic acid inclusion complex.

[0061] Step 3: weigh 127 g of the γ-cyclodextrin / polyacrylic acid inclusion complex prepared in step 2 in a 500 mL flask, add 120 g of polyethylene glycol monomethyl ether with a degree of polymerization of 23 dissolved in advance and 2.25 g of catalyst p-toluenesulfonic acid, wherein the polyethylene glycol monomethyl ether is added dropwise at a uniform rate for 1 hour, and the water generated by the reaction is removed by passing nitrogen. Stir and react for 5 hours at a temperature of 115 ° C. After the reaction, cool to room temperature, add water and sodium carbonate solution to neutralize to obtain an ester polycarboxylic acid water reducer and γ-cyclodextrin self-assembled inclusion complex with a solid content of 50%.

[0062] Example 5

[0063] A method for self-assembly of an ester polycarboxylate water-reducing agent and γ-cyclodextrin comprises the following steps:

[0064] Step 1, preparation of polyacrylic acid prepolymer: Add 4g of acrylic acid, 2g of methacrylic acid and 30g of water to the bottom of a 500 mL four-necked flask equipped with a stirrer and stir evenly at 25±2°C. 33g of acrylic acid, 21g of methacrylic acid and 7g of water are prepared into liquid A, 0.16g of Vc, 0.44g of thioglycolic acid and 20g of water are prepared into liquid B, 1.2g of hydrogen peroxide is added before adding liquid A and liquid B, after stirring for 10min, liquid A and liquid B are added dropwise, wherein liquid A is added dropwise for 2h, liquid B is added dropwise for 2.5h, and after keeping warm for 1h, a viscous polymer liquid polyacrylic acid prepolymer with a concentration of 50% is obtained.

[0065] Step 2: At 60°C, add 12.97 g of γ-cyclodextrin into a 500 mL flask and add water to prepare a saturated aqueous solution of γ-cyclodextrin. Then weigh 122 g of the polyacrylic acid prepolymer prepared in step 1 and add it to the saturated solution of γ-cyclodextrin. After stirring for 1 hour, cool to room temperature to prepare a γ-cyclodextrin / polyacrylic acid inclusion complex.

[0066] Step 3: weigh 127 g of the γ-cyclodextrin / polyacrylic acid inclusion complex prepared in step 2 in a 500 mL flask, add 100 g of polyethylene glycol monomethyl ether with a degree of polymerization of 23 and 25 g of polyethylene glycol monomethyl ether with a degree of polymerization of 13 dissolved in advance, and 2.5 g of catalyst p-toluenesulfonic acid, wherein the polyethylene glycol monomethyl ether is added dropwise at a uniform rate for 1 hour, and the water generated by the reaction is removed by passing nitrogen. Stir and react at a temperature of 115 ° C for 5 hours. After the reaction is completed, cool to room temperature, add water and sodium carbonate solution to neutralize to obtain an ester polycarboxylic acid water reducer and γ-cyclodextrin self-assembled inclusion complex with a solid content of 50%.

[0067] Example 6

[0068] A method for self-assembly of an ester polycarboxylate water-reducing agent and γ-cyclodextrin comprises the following steps:

[0069] Step 1, preparation of polyacrylic acid prepolymer: Add 4g of acrylic acid, 2g of methacrylic acid and 30g of water to the bottom of a 500 mL four-necked flask equipped with a stirrer and stir evenly at 25±2°C. 33g of acrylic acid, 21g of methacrylic acid and 7g of water are prepared into liquid A, 0.16g of Vc, 0.44g of thioglycolic acid and 20g of water are prepared into liquid B, 1.2g of hydrogen peroxide is added before adding liquid A and liquid B, after stirring for 10min, liquid A and liquid B are added dropwise, wherein liquid A is added dropwise for 2h, liquid B is added dropwise for 2.5h, and after keeping warm for 1h, a viscous polymer liquid polyacrylic acid prepolymer with a concentration of 50% is obtained.

[0070] Step 2: At 60°C, add 12.97 g of γ-cyclodextrin into a 500 mL flask and add water to prepare a saturated aqueous solution of γ-cyclodextrin. Then weigh 122 g of the polyacrylic acid prepolymer prepared in step 1 and add it to the saturated solution of γ-cyclodextrin. After stirring for 1 hour, cool to room temperature to prepare a γ-cyclodextrin / polyacrylic acid inclusion complex.

[0071] Step 3: weigh 127 g of the γ-cyclodextrin / polyacrylic acid inclusion complex prepared in step 2 in a 500 mL flask, add 100 g of polyethylene glycol monomethyl ether with a degree of polymerization of 23 and 50 g of polyethylene glycol monomethyl ether with a degree of polymerization of 44, and 2.6 g of catalyst p-toluenesulfonic acid, wherein the polyethylene glycol monomethyl ether is added dropwise at a uniform rate for 1 hour, and the water generated by the reaction is removed by nitrogen gas. Stir and react for 5 hours at a temperature of 115 ° C. After the reaction, cool to room temperature, add water and sodium carbonate solution to neutralize, and obtain a self-assembled inclusion complex of an ester polycarboxylic acid water reducer and γ-cyclodextrin with a solid content of 50%.

[0072] Experimental Example 1 Performance Test

[0073] The ester polycarboxylate water-reducing agent synthesized in Examples 1 to 6 was used to test the concrete performance with the γ-cyclodextrin self-assembly mother liquor and the standard vertebral ether polycarboxylate water-reducing agent. According to GB / 8076-2008 "Concrete Admixtures", the concrete mix ratio is: 360 kg of cement, 906 kg of washed sand, 990 kg of gravel, and 144 kg of water. The water reduction rate, slump, time loss and water bleeding rate ratio in the concrete were tested; at the same time, the viscosity reduction effect was tested. Each group was repeated three times, and the results are shown in Table 1 below.

[0074] Table 1

[0075]

[0076] As shown in Table 1, the water reduction rate, slump and time loss of the self-assembled mother solution of the ester polycarboxylate water-reducing agent and γ-cyclodextrin of the present invention are better than those of the standard vertebral ether polycarboxylate water-reducing agent; the water bleeding rate is reduced by 27% compared with the standard vertebral ether polycarboxylate water-reducing agent, T500 The emptying time is 4 seconds shorter than that of the standard cone-type ether polycarboxylate water reducer, which has a significant viscosity reduction effect. It has excellent workability when used in water-washed sand.

[0077] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A self-assembly method of an ester polycarboxylate water-reducing agent and γ-cyclodextrin, characterized in that: The steps include: Step 1: dissolving acrylic acid in water to prepare a mixed solution A of acrylic acid, methacrylic acid and water; mixing a reducing agent, a chain transfer agent and water to prepare a mixed solution B; and heat-retaining an oxidant, the A solution and the B solution to obtain a viscous polymer liquid polyacrylic acid; Step 2: Under elevated temperature conditions, dissolving γ-cyclodextrin in water to obtain a saturated aqueous solution of γ-cyclodextrin, adding polyacrylic acid and stirring to react to obtain a γ-cyclodextrin / polyacrylic acid inclusion complex; Step 3: Add the pre-dissolved polyethylene glycol monomethyl ether and the catalyst p-toluenesulfonic acid to the γ-cyclodextrin / polyacrylic acid inclusion complex prepared in step 2, and stir to react to obtain a self-assembled inclusion complex of the ester polycarboxylic acid water reducer and γ-cyclodextrin.

2. An inclusion compound obtained by the self-assembly method of an ester polycarboxylate water-reducing agent and γ-cyclodextrin according to claim 1.

3. The self-assembly method of an ester polycarboxylate water-reducing agent and γ-cyclodextrin according to claim 1, characterized in that: In step 1, the molar ratio of acrylic acid to methacrylic acid is 3 to 2:

1.

4. The self-assembly method of an ester polycarboxylate water-reducing agent and γ-cyclodextrin according to claim 3, characterized in that: In step 1, the oxidant is one or a combination of hydrogen peroxide and persulfate, and the added amount of the oxidant is 2-4% of the total mass of acrylic acid and methacrylic acid.

5. The self-assembly method of an ester polycarboxylate water-reducing agent and γ-cyclodextrin according to claim 4, characterized in that: In step 1, the reducing agent is at least one of Vc, bleaching powder, and sodium bisulfite, and the amount of the reducing agent added is 15-20% of the mass of the oxidant.

6. The self-assembly method of an ester polycarboxylate water-reducing agent and γ-cyclodextrin according to claim 5, characterized in that: In step 1, the chain transfer agent is at least one of thioglycolic acid, mercaptopropionic acid, mercaptoethanol, sodium hypophosphite, and sodium methacrylic acid, and the added amount of the chain transfer agent is 0.8-1.2% of the total mass of acrylic acid and methacrylic acid.

7. The self-assembly method of an ester polycarboxylate water-reducing agent and γ-cyclodextrin according to claim 6, characterized in that: In step 2, the molar ratio of polyacrylic acid to γ-cyclodextrin is 1-2:1; the heating temperature is 60° C., and the stirring reaction time is 1 hour.

8. The self-assembly method of an ester polycarboxylate water-reducing agent and γ-cyclodextrin according to claim 7, characterized in that: In step 3, the acid-ether ratio of acrylic acid and methacrylic acid to polyethylene glycol monomethyl ether is 3.5-5:1; and the added amount of the catalyst p-toluenesulfonic acid accounts for 1-2% of the total mass of polyacrylic acid and polyethylene glycol monomethyl ether.

9. The self-assembly method of an ester polycarboxylate water-reducing agent and γ-cyclodextrin according to claim 8, characterized in that: In step 3, the polyethylene glycol monomethyl ether has a degree of polymerization of 13, 23, 44, or a combination of two or more thereof.

10. Use of the self-assembled inclusion compound of an ester polycarboxylate water-reducing agent and γ-cyclodextrin according to claim 2 in the preparation of a concrete slump-reducing agent.

Images