Slow-release polycarboxylate water reducer and its preparation method

Abstract

The present invention provides a sustained-release polycarboxylate water reducer and a preparation method thereof. The preparation method is as follows: Add a macromonomer to softened water under stirring and fully stir and dissolve to obtain a base material C; Under stirring, add a solution prepared from an unsaturated carboxylic acid small monomer to the base material C, stir and mix evenly. Under stirring conditions, add a liquid caustic solution, stir and mix evenly, then dropwise add a chain transfer agent, stir and mix evenly, then add an oxidant solution, stir and mix evenly, and finally add a catalyst solution and stir; Dropwise add solution A and solution B to the obtained base material simultaneously; After the dropping is completed, carry out aging and adjust the pH; Thus obtained. Compared with the prior art, the present invention utilizes the unique molecular structure of ethylene glycol mono vinyl polyethylene glycol ether, and at the same time controls the addition sequence and addition timing of raw materials, adds an alkali solution to the base material, and the entire reaction process is carried out at room temperature without low-temperature temperature control, greatly reducing energy consumption. The synthesized product has excellent ultra-long slump retention and sustained-release performance.

Description

Technical Field

[0001] The present invention relates to the technical field of building chemical materials, and particularly to a sustained-release polycarboxylate water reducer synthesized from EPEG monomers and a preparation method thereof. Background Art

[0002] Carboxylic acid water reducers are widely used in the preparation of high-strength and ultra-high-strength concrete due to their advantages such as low dosage, high water reduction, and high slump retention. Due to the special molecular structure of polycarboxylate water reducers, water reducers with desired properties can be prepared as needed. However, the slump of commercially available polycarboxylate water reducers in concrete is mostly affected by temperature changes, transportation distance, and cement type. Especially in hot summers or during long-distance transportation, the slump loss of concrete is too fast. During the construction process, measures such as increasing the dosage of water reducer or compounding with retarders are required to maintain the workability of concrete. Increasing the dosage of water reducer will cause segregation, bleeding and other phenomena in the early stage of concrete mixing, affecting the homogeneity of concrete and reducing the compressive and flexural strengths of concrete; while retarders are prone to deterioration under high-temperature conditions, which will also reduce the workability of concrete.

[0003] Currently, low-temperature temperature control processes are selected for the synthesis process of polycarboxylate water reducers synthesized from new six-carbon monomers in the market, which greatly increases the equipment investment cost and a large amount of power consumption. Moreover, with the increasing urban congestion, the transportation time of concrete mixer trucks is getting longer. Therefore, developing a new type of super-sustained-release polycarboxylate water reducer synthesized at normal temperature with six carbons that can effectively solve the long-distance transportation of concrete and ensure no slump loss of concrete within three hours is of great significance to the development of concrete admixtures and the concrete industry. Summary of the Invention

[0004] The purpose of the present invention is to provide a sustained-release polycarboxylate water reducer, which overcomes the defects of the prior art, has a wide adaptability and a long slump retention time.

[0005] Another purpose of the present invention is to provide a preparation method of a sustained-release polycarboxylate water reducer. The preparation method can prepare a sustained-release polycarboxylate water reducer at normal temperature using EPEG monomers, overcoming the problems of complex production processes, high investment, and poor economic benefits in the existing low-temperature synthesis technology of 6C monomers for polycarboxylate water reducers.

[0006] The specific technical solution of the present invention is as follows:

[0007] A sustained-release polycarboxylate water reducer, comprising solution A, solution B, and base material;

[0008] The A solution includes: unsaturated carboxylic acid monomers, ester monomers, a chain transfer agent, and softened water; by weight, the unsaturated carboxylic acid monomers are 2-8 parts by weight, the ester monomers are 10-40 parts by weight, the chain transfer agent is 0.6-1.8 parts by weight, and the softened water is 50-100 parts by weight.

[0009] The B solution includes softened water and a reducing agent; by weight, the softened water is 20-60 parts by weight, and the reducing agent is 0.5-4.0 parts by weight;

[0010] The base material includes a macromonomer, softened water, unsaturated carboxylic acid monomers, liquid caustic soda, a chain transfer agent, an oxidizing agent, and a catalyst; by weight, the macromonomer is 220-450 parts by weight, the softened water is 150-300 parts by weight, the unsaturated carboxylic acid monomers are 0.5-2 parts by weight, the liquid caustic soda is 0.2-1.0 parts by weight, the chain transfer agent is 0.2-0.6 parts by weight, the oxidizing agent is 2-8 parts by weight, and the catalyst is 1-5 parts by weight.

[0011] In the base material and the A solution, the unsaturated carboxylic acid monomers are one or a combination of maleic anhydride, acrylic acid, methacrylic acid, or itaconic acid.

[0012] In the A solution, the ester monomers are selected from one or more of vinyl acetate, allyl acetate, hydroxypropyl acrylate, hydroxyethyl acrylate, and diethylhexyl maleate.

[0013] In the base material and the A solution, the chain transfer agent is at least one of mercaptoethanol, mercaptoacetic acid, mercaptopropionic acid, and sodium hypophosphite.

[0014] In the B solution, the reducing agent is at least one of ascorbic acid, sodium formaldehyde sulfoxylate, and sodium bisulfite;

[0015] In the base material, the liquid caustic soda is an aqueous sodium hydroxide solution with a concentration of 35%;

[0016] In the base material, the macromonomer is ethylene glycol mono vinyl polyethylene glycol ether (EPEG); the number average molecular weight of the ethylene glycol mono vinyl polyethylene glycol ether is 2000-4000;

[0017] In the base material, the oxidizing agent is at least one of hydrogen peroxide solution, ammonium persulfate, or potassium persulfate; preferably a hydrogen peroxide solution with a mass fraction of 30%.

[0018] In the base material, the catalyst is an inorganic Fe 2+ salt solution, preferably an FeSO4 solution with a mass fraction of 0.25%-2.0%.

[0019] A preparation method of a sustained-release polycarboxylate water reducer provided by the present invention includes the following steps:

[0020] 1) By weight, into 50 - 100 parts by weight of softened water, add 2 - 8 parts of unsaturated carboxylic acid small monomers, 10 - 40 parts of ester small monomers, and 0.6 - 1.8 parts of chain transfer agent, and mix evenly to prepare solution A;

[0021] 2) By weight, into 20 - 60 parts by weight of softened water, add 0.5 - 4 parts of reducing agent, and mix thoroughly to prepare solution B;

[0022] 3) Add 220 - 450 parts of macromonomer to 150 - 300 parts by weight of softened water under stirring, and stir and dissolve thoroughly to obtain base material C;

[0023] 4) Under stirring, add 0.5 - 2.0 parts by weight of unsaturated carboxylic acid small monomers to the base material C obtained in step 3), stir and mix evenly. Under stirring conditions, add 0.2 - 1.0 parts by weight of liquid alkali solution, stir and mix evenly, then add 0.2 - 0.6 parts by weight of chain transfer agent, stir and mix evenly, then add 2 - 8 parts of oxidant solution, stir and mix evenly, and finally add 1 - 5 parts by weight of catalyst solution, and stir;

[0024] 5) While simultaneously dripping solution A prepared in step 1) and solution B prepared in step 2) into the base material obtained in step 4); after the dripping is completed, carry out aging and adjust the pH; thus obtained.

[0025] In the preparation method, for the stirring, the stirring rate range is: 250 r / rmin - 300 r / min;

[0026] The preparation process is carried out at normal temperature.

[0027] In step 4), add 0.5 - 2.0 parts by weight of unsaturated carboxylic acid small monomers, stir for 3 - 5 min, and then add 0.2 - 1.0 parts by weight of liquid alkali solution;

[0028] In step 4), the unsaturated carboxylic acid small monomers are added in the form of an aqueous solution, and the mass concentration of the aqueous solution is 90% - 99%.

[0029] Furthermore, in step 4), add 0.2 - 1.0 parts by weight of liquid alkali solution, stir for 3 - 5 min, and then add 0.2 - 0.6 parts by weight of chain transfer agent;

[0030] Furthermore, in step 4), after adding 0.2 - 0.6 parts by weight of chain transfer agent, stir for 3 - 5 min, and then add 2 - 8 parts of oxidant solution;

[0031] Furthermore, in step 4), after adding 2 - 8 parts of oxidant, stir for 3 - 5 min, and then add 1 - 5 parts by weight of catalyst solution;

[0032] Further, in step 4), after adding 1-5 parts by weight of the catalyst solution, stir for 3-5 min, and then proceed to step 5), while adding solution A and solution B dropwise.

[0033] In step 5), solution A is added dropwise within 30-45 min, and the dropping time of solution B is 5-15 min longer than that of solution A.

[0034] In step 5), after the addition of solution B is completed, cure for 10-20 min.

[0035] The reaction process in step 5) does not need to be carried out in a low-temperature system. Preferably, it is carried out at room temperature.

[0036] In step 5), the sodium hydroxide solution with a mass fraction of 35% is used to adjust the pH.

[0037] In step 5), the pH is adjusted to 6.0-6.5.

[0038] The beneficial technical effects of the present invention are as follows: The present invention utilizes the unique molecular structure of ethylene glycol mono vinyl polyethylene glycol ether. In solution A, small ester monomers are added. During the reaction process, an inorganic Fe catalyst salt is introduced, which can greatly shorten the reaction time and stimulate the activity of the monomers. The entire reaction process only takes 1.0-1.5 hours. At the same time, the addition sequence and timing of the raw materials are controlled. An alkali solution is added to the bottom material, and the entire reaction process is carried out at room temperature without low-temperature control, greatly reducing energy consumption. The synthesized product has excellent super-long slump retention and slow-release performance. When transported over a long distance, the slump of the concrete basically has no loss in 120 min, and it has good concrete construction performance, and the product has good material adaptability. The preparation method of the present invention belongs to an environmental protection process, and the reaction raw materials are pollution-free, and the reaction process is safe and environmentally friendly. 2+ In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the preparation method described in the embodiments of the present invention is only used to illustrate the present invention, rather than a limitation of the present invention. Any simple improvement of the preparation method of the present invention under the premise of the concept of the present invention belongs to the scope protected by the present invention. Specific embodiments

[0039] A preparation method of a slow-release polycarboxylate water reducer, comprising the following steps:

[0040] Example 1

[0041] A preparation method of a slow-release polycarboxylate water reducer, comprising the following steps:

[0042] 1) Prepare solution A: 5 g of acrylic acid, 40 g of hydroxyethyl acrylate, and 1.8 g of thiol propionic acid aqueous solution (solution mass concentration is 99%) are dissolved in 70 g of softened water, mixed evenly, and solution A is obtained for standby;

[0043] 2) Preparation of Solution B: 1.5 g of formaldehyde sodium bisulfite is dissolved in 35 g of softened water and mixed evenly to obtain Solution B for standby.

[0044] 3) Add 240 g of softened water to a four-necked flask, and add 360 g of ethylene glycol mono-vinyl polyethylene glycol ether macromonomer with a molecular weight of 2400 under stirring. After complete dissolution, obtain the base material C.

[0045] 4) Under the stirring state of 250 r / rmin, add 1.0 g of acrylic acid aqueous solution (solution mass concentration is 95%) to the base material C obtained in step 3). After stirring for 5 min, add 0.8 g of 35% sodium hydroxide solution, stir for 5 min, then add 0.6 g of mercaptopropionic acid aqueous solution (solution mass concentration is 99%), stir for 5 min, add 5 g of 30% hydrogen peroxide aqueous solution, stir for 5 min, and then add 3 g of 0.5% FeSO4 aqueous solution, and continue to stir for 5 min.

[0046] 5) Add Solution A and Solution B to the base material system obtained in step 4) simultaneously. Solution A is added dropwise within 40 min, and Solution B is added dropwise within 50 min (Solution B takes 10 min longer than Solution A for dropwise addition). The whole reaction process is carried out at room temperature. After dropwise addition, cure for 15 min, and then add 35% sodium hydroxide solution and adjust its pH to 6.0 to obtain the slow-release polycarboxylate water reducer solution.

[0047] Example 2

[0048] A preparation method of a slow-release polycarboxylate water reducer, comprising the following steps:

[0049] 1) Preparation of Solution A: 5 g of acrylic acid, 36 g of hydroxyethyl acrylate, and 1.5 g of mercaptopropionic acid aqueous solution (solution mass concentration is 99%) are dissolved in 65 g of softened water and mixed evenly to obtain Solution A for standby.

[0050] 2) Preparation of Solution B: 2.0 g of formaldehyde sodium bisulfite is dissolved in 40 g of softened water and mixed evenly to obtain Solution B for standby.

[0051] 3) Add 200 g of softened water to a four-necked flask, and add 280 g of ethylene glycol mono-vinyl polyethylene glycol ether macromonomer with a molecular weight of 2400 under stirring. After complete dissolution, obtain the base material C.

[0052] 4) Under the stirring state of 300 r / min, add 1.25 g of acrylic acid aqueous solution (solution mass concentration is 95%) to the base material C obtained in step 3), stir for 5 min, then add 0.6 g of 35% sodium hydroxide solution, stir for 5 min, add 0.5 g of mercaptopropionic acid aqueous solution (solution mass concentration is 99%), stir for 5 min, then add 6 g of 30% hydrogen peroxide aqueous solution, stir for 5 min, add 2 g of 1.0% FeSO4 aqueous solution, and continue to stir for 5 min;

[0053] 5) Dropwise add solution A and solution B to the base material system obtained in step 4) simultaneously. Solution A is dropped within 40 min, and solution B is dropped within 50 min (solution B takes 10 min longer than solution A to be dropped). The whole reaction process is carried out at room temperature. After dropping, cure for 15 min, then add 35% sodium hydroxide solution and adjust its pH to 6.0 to obtain a high-performance polycarboxylate water reducer solution.

[0054] Example 3

[0055] A preparation method of a sustained-release polycarboxylate water reducer, comprising the following steps:

[0056] 1) Prepare solution A: Dissolve 6 g of acrylic acid, 32 g of hydroxyethyl acrylate, and 1.2 g of mercaptopropionic acid aqueous solution (solution mass concentration is 99%) in 60 g of softened water, mix evenly, and set aside solution A for use;

[0057] 2) Prepare solution B: Dissolve 3.5 g of sodium formaldehyde bisulfite in 50 g of softened water, mix evenly, and set aside solution B for use;

[0058] 3) Add 250 g of softened water to a four-necked flask, add 380 g of ethylene glycol monovinyl polyethylene glycol ether macromonomer with a molecular weight of 2400 under stirring, and obtain base material C after complete dissolution;

[0059] 4) Under the stirring state of 300 r / min, add 1.5 g of acrylic acid aqueous solution (solution mass concentration is 95%) to the base material obtained in step 3), stir for 5 min, then add 0.4 g of 35% sodium hydroxide solution, stir for 5 min, add 0.4 g of mercaptopropionic acid aqueous solution (solution mass concentration is 99%), stir for 5 min, then add 3 g of 30% hydrogen peroxide aqueous solution, stir for 5 min, add 3 g of 0.25% FeSO4 aqueous solution, and continue to stir for 5 min;

[0060] 5) While simultaneously dripping Solution A and Solution B into the system obtained in Step 4), Solution A is dripped out within 40 minutes, and Solution B is dripped out within 50 minutes (Solution B takes 10 minutes longer than Solution A to be dripped). The entire reaction process is carried out at room temperature. After dripping, it is aged for 15 minutes, and then a sodium hydroxide solution with a mass fraction of 35% is added, and its pH is adjusted to 6.0 to obtain a high-performance polycarboxylate water reducer solution.

[0061] Example 4

[0062] A preparation method of a sustained-release polycarboxylate water reducer includes the following steps:

[0063] 1) Prepare Solution A: 4 g of acrylic acid, 30 g of hydroxyethyl acrylate, and 0.9 g of thiol propionic acid aqueous solution (solution mass concentration is 99%) are dissolved in 55 g of softened water, mixed evenly, and Solution A is reserved for use;

[0064] 2) Prepare Solution B: 2.5 g of sodium formaldehyde bisulfite is dissolved in 30 g of softened water, mixed evenly, and Solution B is reserved for use;

[0065] 3) Add 200 g of softened water to a four-necked flask, and add 350 g of ethylene glycol monovinyl polyethylene glycol ether macromonomer with a molecular weight of 2400 under stirring. After complete dissolution, the bottom material C is obtained;

[0066] 4) Under stirring at 300 r / min, add 1.0 g of acrylic acid aqueous solution (solution mass concentration is 95%) to the bottom material obtained in Step 3). After stirring for 5 minutes, add 0.2 g of sodium hydroxide solution with a concentration of 35%. After stirring for 5 minutes, add 0.3 g of thiol propionic acid aqueous solution (solution mass concentration is 99%). After stirring for 5 minutes, add 4 g of hydrogen peroxide solution with a mass fraction of 30%. After stirring for 5 minutes, add 2 g of FeSO4 aqueous solution with a mass fraction of 2.0%, and continue stirring for 5 minutes;

[0067] 5) While simultaneously dripping Solution A and Solution B into the system obtained in Step 4), Solution A is dripped out within 40 minutes, and Solution B is dripped out within 50 minutes (Solution B takes 10 minutes longer than Solution A to be dripped). The entire reaction process is carried out at room temperature. After dripping, it is aged for 15 minutes, and then a sodium hydroxide solution with a mass fraction of 35% is added, and its pH is adjusted to 6.0 to obtain a high-performance polycarboxylate water reducer solution.

[0068] Example 5

[0069] A preparation method of a sustained-release polycarboxylate water reducer includes the following steps:

[0070] 1) Preparation of Solution A: 4 g of acrylic acid, 28 g of hydroxyethyl acrylate, and 0.6 g of an aqueous solution of mercaptopropionic acid (solution mass concentration of 99%) are dissolved in 50 g of softened water, mixed evenly, and the obtained Solution A is reserved for use;

[0071] 2) Preparation of Solution B: 3.5 g of sodium formaldehyde sulfoxylate is dissolved in 40 g of softened water, mixed evenly, and the obtained Solution B is reserved for use;

[0072] 3) Add 220 g of softened water to a four-necked flask, and add 380 g of ethylene glycol monovinyl polyethylene glycol ether macromonomer with a molecular weight of 2400 under stirring. After complete dissolution, the base material is obtained;

[0073] 4) Under stirring, add 0.8 g of an aqueous acrylic acid solution (solution mass concentration of 95%) to the base material obtained in step 3). After stirring for 5 min, add 0.2 g of a 35% sodium hydroxide solution, stir for 5 min, then add 0.2 g of an aqueous solution of mercaptopropionic acid (solution mass concentration of 99%), stir for 5 min, then add 8 g of a 30% hydrogen peroxide aqueous solution, stir for 5 min, then add 1 g of a 1.0% FeSO4 aqueous solution, and continue stirring for 5 min;

[0074] 5) Add Solution A and Solution B to the system obtained in step 4) simultaneously. Solution A is added dropwise within 40 min, and Solution B is added dropwise within 50 min (Solution B has a 10-min longer dropping time than Solution A). The entire reaction process is carried out at room temperature. After dropping, it is aged for 15 min, and then a 35% sodium hydroxide solution is added and its pH is adjusted to 6.0 to obtain a high-performance polycarboxylate water-reducing agent solution.

[0075] Comparative Example 1

[0076] In this Comparative Example 1, the macromonomer ethylene glycol monovinyl polyethylene glycol ether in Example 1 is replaced with allyl alcohol polyoxyethylene ether, and other conditions remain unchanged;

[0077] Comparative Example 2

[0078] In this Comparative Example 2, the macromonomer ethylene glycol monovinyl polyethylene glycol ether in Example 1 is replaced with isopentenol polyoxyethylene ether, and other conditions remain unchanged.

[0079] Comparative Example 3

[0080] In this Comparative Example 3, the catalyst FeSO4 aqueous solution is not added during the reaction process in Example 1, and other conditions remain unchanged.

[0081] Comparative Example 4

[0082] In Comparative Example 4, the aqueous solution of catalyst FeSO4 was not added during the reaction in Example 1, where Solution A was added dropwise for 3 h and Solution B was added dropwise for 3.5 h, and other conditions remained unchanged.

[0083] Comparative Example 5

[0084] In Comparative Example 5, no liquid caustic solution was added to the reaction bottom material in Example 1, and other conditions remained unchanged.

[0085] Comparative Example 6

[0086] In Comparative Example 6, the method of Example 1 was followed, except that hydroxyethyl acrylate was not added to Solution A, and other conditions remained unchanged.

[0087] Comparative Example 7

[0088] In Comparative Example 7, the method of Example 1 was followed, except that the operation in step 4) of Example 1 was adjusted as follows, and other conditions remained unchanged. The operation of step 4) was changed to: add 5 g of 30% hydrogen peroxide aqueous solution dropwise to the bottom material C obtained in step 3), stir for 5 min, then add 3 g of 0.5% FeSO4 aqueous solution dropwise, stir for 5 min, then add 0.8 g of 35% sodium hydroxide solution dropwise, stir for 5 min, then add 1.0 g of acrylic acid aqueous solution (solution mass concentration is 95%), stir for 5 min, and then add 0.6 g of mercaptopropionic acid aqueous solution (solution mass concentration is 99%) dropwise, and continue to stir for 5 min.

[0089] Net paste and concrete comparative experiments were carried out on the above Examples 1 - 5 and Comparative Examples 1 - 7 respectively. Among them, the net paste experiment was carried out according to the standard of GB / T 8077 - 2012 "Test Methods for the Homogeneity of Concrete Admixtures"; the concrete experiment was carried out according to "Standard for Test Methods of Performance of Ordinary Concrete Mixtures". The specific test data are shown in Table 1 and Table 2 below.

[0090] Table 1 Test Results of Net Paste Experiments for Each Example and Comparative Example

[0091]

[0092] Table 2 Test Results of C30 Concrete Experiments for Each Example and Comparative Example

[0093]

[0094] From the above data, it can be obtained that: for the slow - release polycarboxylate superplasticizer embodiments provided by the present invention, as the slow - release monomer is gradually released, the net paste fluidity at 60 min begins to increase, and the net paste fluidity at 360 min hardly decreases, showing excellent slump retention. In the concrete test, it can also ensure that within 180 min, the slump spread remains unchanged and the workability is good.

[0095] The above is only an example to further illustrate the technical content of the invention, but they do not limit the present invention. Any technical extension or re-creation based on the present invention is protected by the present invention.

Claims

1. A sustained-release polycarboxylate water reducer, characterized in that, The slow-release polycarboxylate water reducer includes solution A, solution B and base material; Solution A includes: unsaturated carboxylic acid small monomers, ester small monomers, chain transfer agent and softened water; Solution B includes softened water and reducing agent; The base material includes macromonomer, softened water, unsaturated carboxylic acid small monomers, liquid caustic soda, chain transfer agent, oxidizing agent and catalyst; The preparation method of the slow-release polycarboxylate water reducer includes the following steps: 1) By weight, put 2-8 parts of unsaturated carboxylic acid small monomers, 10-40 parts of ester small monomers and 0.6-1.8 parts of chain transfer agent into 50-100 parts by weight of softened water, and mix evenly to prepare solution A; 2) By weight, put 0.5-4 parts of reducing agent into 20-60 parts by weight of softened water, and mix evenly to prepare solution B; 3) Add 220-450 parts of macromonomer to 150-300 parts by weight of softened water under stirring, and stir and dissolve fully to obtain base material C; 4) Under stirring, add 0.5-2.0 parts by weight of unsaturated carboxylic acid small monomers to the base material C obtained in step 3), stir and mix evenly, under stirring conditions, add 0.2-1.0 parts by weight of liquid caustic soda, stir and mix evenly, add 0.2-0.6 parts by weight of chain transfer agent, stir and mix evenly, then add 2-8 parts of oxidizing agent solution, stir and mix evenly, and finally add 1-5 parts by weight of catalyst solution, and stir; 5) Dropwise add solution A prepared in step 1) and solution B prepared in step 2) to the base material obtained in step 4) at the same time; after dropping, ripen and adjust the pH; thus obtained; In solution A, the ester small monomer is selected from hydroxypropyl acrylate or hydroxyethyl acrylate; in the base material, the large monomer is ethylene glycol mono vinyl polyethylene glycol ether; the number average molecular weight of the ethylene glycol mono vinyl polyethylene glycol ether is 2000-4000; the catalyst solution is an inorganic Fe 2+ salt solution; In step 5), solution A is dropped within 30-45 minutes, and the dropping time of solution B is 5-15 minutes longer than that of solution A; after solution B is dropped, it is ripened for 10-20 minutes.

2. The preparation method of the sustained-release polycarboxylate water reducer according to claim 1, characterized in that, The preparation method includes the following steps: 1) By weight, put 2-8 parts of unsaturated carboxylic acid small monomers, 10-40 parts of ester small monomers and 0.6-1.8 parts of chain transfer agent into 50-100 parts by weight of softened water, and mix evenly to prepare solution A; 2) By weight, put 0.5-4 parts of reducing agent into 20-60 parts by weight of softened water, and mix evenly to prepare solution B; 3) Add 220-450 parts of macromonomer to 150-300 parts by weight of softened water under stirring, and stir and dissolve fully to obtain base material C; 4) Under stirring, add 0.5-2.0 parts by weight of unsaturated carboxylic acid small monomers to the base material C obtained in step 3), stir and mix evenly, under stirring conditions, add 0.2-1.0 parts by weight of liquid caustic soda, stir and mix evenly, add 0.2-0.6 parts by weight of chain transfer agent, stir and mix evenly, then add 2-8 parts of oxidizing agent solution, stir and mix evenly, and finally add 1-5 parts by weight of catalyst solution, and stir; 5) Dropwise add solution A prepared in step 1) and solution B prepared in step 2) to the base material obtained in step 4) at the same time; after dropping, ripen and adjust the pH; thus obtained; In step 5), solution A is added dropwise within 30 - 45 minutes, and the addition time of solution B is 5 - 15 minutes longer than that of solution A; after the addition of solution B is completed, it is aged for 10 - 20 minutes.

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