Large-steric-hindrance low-dosage mud-resistant polycarboxylic acid water reducer and preparation method thereof

Abstract

The invention discloses a large-site impedance mud type polycarboxylic acid water reducer, which is a segmented copolymer formed by an unsaturated polyoxyethylene ether monomer, a tristyrylphenol polyoxyethylene ether phosphate monomer and an unsaturated carboxylic acid monomer. On the basis of a traditional polycarboxylate superplasticizer structure, tristyrylphenol polyoxyethylene ether phosphate, a polycarboxylate superplasticizer with a molecular structure containing a polyoxyethylene ether long chain, a large steric hindrance group with a plurality of benzene ring structures and a phosphate group with a mud-resistant function are further introduced; the water reducing agent can reduce the adsorption of soil to the water reducing agent under the condition of low mixing amount, ensures a better water reducing effect, and is suitable for popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete admixtures, and particularly relates to a large steric hindrance, low-dosage, mud-resistant polycarboxylate water-reducing agent and a preparation method thereof. Background Art

[0002] Polycarboxylate water reducer is a concrete admixture that can reduce the amount of mixing water while maintaining the slump of concrete. Most of them are anionic surfactants. When polycarboxylate water reducer is added to concrete mixture, it has a dispersing effect on cement particles, which can improve its workability, reduce unit water consumption, increase concrete strength, improve the fluidity of concrete mixture; or reduce unit cement consumption and save cement.

[0003] With the development of the concrete industry and increasingly stringent environmental protection requirements, the source of high-quality sand and gravel is limited, and sand and gravel with high mud content has been used to a certain extent. Since the specific surface area of ​​soil is smaller than that of cement, it is easier to adsorb polycarboxylic acid water reducers, resulting in problems such as the weakening of the water-reducing effect of polycarboxylic acid water reducers. It is usually necessary to further increase the amount of water reducer and water, which will increase the preparation cost and reduce the strength of concrete. In response to the above problems, some studies have introduced polycarboxylic acid water reducers with amide groups and other groups with anti-mud effects to improve the high mud content of sand and gravel, but this will affect the water-reducing effect of the water reducer to a certain extent. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a large steric hindrance, low dosage, anti-mud polycarboxylic acid water reducer in view of the deficiencies in the prior art, which can reduce the adsorption of soil on the water reducer under low dosage conditions and ensure a high water reduction rate.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A large impedance mud type polycarboxylic acid water reducing agent is a block copolymer formed by unsaturated polyoxyethylene ether monomer, tristyrylphenol polyoxyethylene ether phosphate monomer and unsaturated carboxylic acid monomer.

[0007] In the above scheme, the unsaturated polyoxyethylene ether monomer is one or more of methyl allyl alcohol polyoxyethylene ether, isopentanol polyoxyethylene ether, isobutylene alcohol polyoxyethylene ether, ethylene glycol monovinyl polyethylene glycol ether, etc.; its molecular weight is 2400-3000; preferably isopentanol polyoxyethylene ether.

[0008] In the above scheme, the structural formula of the tristyrylphenol polyoxyethylene ether phosphate monomer is shown in Formula I;

[0009]

[0010] Wherein, n is 13-29, and Me is derived from Na or K.

[0011] Furthermore, the preparation method of tristyrylphenol polyoxyethylene ether phosphate comprises the following steps: heating tristyrylphenol polyoxyethylene ether under a protective atmosphere (50-55° C.), then adding phosphorus oxide thereto under stirring conditions, and continuing to heat the mixture for esterification reaction; adding water for hydrolysis, and then adding polyethylene glycol solution for neutralization and grafting, and adjusting the pH value of the alkali metal-based alkali solution to 6-7 to obtain the tristyrylphenol polyoxyethylene ether phosphate.

[0012] In the above scheme, in the preparation method of tristyrylphenol polyoxyethylene ether phosphate, the amount of each raw material is: 9-11 parts of tristyrylphenol polyoxyethylene ether, 1-3 parts of phosphorus pentoxide, 9-11 parts of water, and 7-9 parts of polyethylene glycol solution.

[0013] Furthermore, the concentration of the polyethylene glycol solution is 20-30%.

[0014] Furthermore, the molecular weight of the tristyrylphenol polyoxyethylene ether is 340-500.

[0015] In the above scheme, the temperature used for the esterification reaction is 110-120° C. and the time is 2.5-3 h.

[0016] In the above scheme, the hydrolysis time is 1-2h

[0017] In the above scheme, the neutralization grafting time is 1-2h.

[0018] In the above scheme, the alkali metal-based lye is a NaOH aqueous solution or a KOH aqueous solution.

[0019] In the above scheme, the unsaturated carboxylic acid is one or more of acrylic acid, methacrylic acid, maleic anhydride, etc.; preferably acrylic acid.

[0020] Furthermore, the mass ratio of the unsaturated polyoxyethylene ether monomer, the tristyrylphenol polyoxyethylene ether phosphate monomer and the unsaturated carboxylic acid monomer is 320-350:5-10:22-27.

[0021] The preparation method of the above-mentioned large steric hindrance, low dosage and anti-mud type polycarboxylate water reducer comprises the following steps:

[0022] 1) adding unsaturated polyoxyethylene ether monomer and suspending agent into a reaction kettle, and heating and stirring to completely dissolve the polyether macromonomer in the suspending agent;

[0023] 2) adding the oxidant and tristyrylphenol polyoxyethylene ether phosphate into the reaction kettle and stirring evenly;

[0024] 3) Mix unsaturated carboxylic acid with water and stir to obtain liquid A; mix reducing agent and chain transfer agent with water and stir to obtain liquid B;

[0025] 5) At room temperature, liquid A and liquid B are uniformly added to the reaction kettle, and after the addition is completed, the mixture is stirred for reaction. After the reaction is completed, the mixture is heat-insulated for aging, and an alkali solution is added to adjust the pH value, thereby obtaining the large-impedance mud-type polycarboxylate water-reducing agent.

[0026] In the above scheme, the suspending agent is a tricyclazole suspending agent.

[0027] In the above scheme, in the preparation process of the large steric hindrance, low dosage anti-mud polycarboxylate water-reducing agent, the raw materials used include, by mass: 320-350 parts of unsaturated polyoxyethylene ether, 290-310 parts of suspending agent, 0.1-0.2 parts of chain transfer agent, 3-4 parts of oxidant, 0.3-0.5 parts of reducing agent, 22-27 parts of unsaturated carboxylic acid, and 5-10 parts of tristyrylphenol polyoxyethylene ether phosphate.

[0028] In the above scheme, the temperature used for dissolving the polyether macromonomer is 40-45° C., and the stirring time is 15-20 min.

[0029] In the above scheme, the oxidant is at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.; preferably hydrogen peroxide.

[0030] Furthermore, the concentration of the hydrogen peroxide is 27.5%.

[0031] In the above scheme, the stirring and mixing time of the oxidant is controlled within 5-10 minutes.

[0032] In the above scheme, the reducing agent is one or more of ascorbic acid, sodium bisulfite, ferrous sulfate, etc.; ascorbic acid is preferred.

[0033] In the above scheme, the chain transfer agent is one or more of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, etc.; mercaptopropionic acid is preferred.

[0034] In the above scheme, the dropwise addition time of liquid A is controlled at 2-2.5 h, preferably 2 h.

[0035] In the above scheme, the B solution addition time is controlled at 2.5-3h, preferably 3h.

[0036] In the above scheme, the insulation time after the dropwise addition is controlled to be 1-1.5h; preferably 2.5h.

[0037] In the above scheme, the alkaline solution is at least one of sodium hydroxide or potassium hydroxide, with a mass concentration of 30-35% and a pH value controlled at 6-7.

[0038] In the above scheme, the pH value of the large impedance mud type polycarboxylate water reducer is 6-7, and the solid content is 40-50%.

[0039] Furthermore, during the application of the large impedance mud type polycarboxylate water-reducing agent, its solid content relative to cement is as low as 0.13%.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1) The present invention firstly esterifies tristyrylphenol polyoxyethylene ether with phosphorus pentoxide to obtain tristyrylphenol polyoxyethylene ether phosphate, and then polymerizes with a macromonomer and an unsaturated carboxylic acid to prepare a polycarboxylic acid water reducer; the polymerization process adopts a suspension polymerization process, which can effectively ensure the polymerization effect of the tristyrylphenol polyoxyethylene ether phosphate monomer, and the relative molecular weight and distribution of the obtained polymerization product are relatively stable, and the impurity content is low, which is conducive to ensuring the application effect of the obtained polycarboxylic acid water reducer.

[0042] 2) The present invention introduces tristyrylphenol polyoxyethylene ether phosphate as the main functional monomer, which has high polymerization activity in the suspending agent, and the obtained polymer product can exert good electrostatic repulsion and steric hindrance; in addition, during the preparation process of tristyrylphenol polyoxyethylene ether phosphate, the anchoring groups of the phosphate salt can be increased by neutralization and grafting, thereby improving its adhesion on the surface of cement particles, thereby enhancing the dispersion stability.

[0043] 3) The polycarboxylate water-reducing agent synthesized by the present invention has a molecular structure containing a long chain of polyoxyethylene ether and a large steric hindrance group of multiple benzene ring structures, which increases the steric hindrance effect, improves the dispersibility of the water-reducing agent, and can effectively reduce the amount of the water-reducing agent used; and the phosphate group introduced at the same time has a special anti-mud effect, making it difficult for the water-reducing agent molecules to be inserted into the soil interlayer, which can effectively reduce the amount of soil adsorbed on the polycarboxylate water-reducing agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a typical molecular structure of the chemically synthesized polycarboxylate water reducer of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] In the following embodiment, the preparation method of tristyrylphenol polyoxyethylene ether phosphate comprises the following steps: adding 10 parts (weight parts, the same below) of tristyrylphenol polyoxyethylene ether (molecular weight 340-500) into a three-necked flask equipped with a stirrer, then introducing nitrogen for 5 minutes, raising the temperature to 50°C, adding 2 parts of phosphorus pentoxide powder under stirring conditions, continuing to raise the temperature to 80°C, and esterification reaction for 4 hours; after the esterification is completed, adding 10 parts of water for hydrolysis, hydrolysis for 2 hours, after the end, adding 8 parts of 30% polyethylene glycol solution for neutralization and grafting, reacting for 0.5 hours, and cooling to room temperature after the reaction is completed.

[0047] Example 1

[0048] A large steric hindrance, low dosage, anti-mud type polycarboxylate water reducer, the preparation method of which comprises the following steps:

[0049] 1) 320 parts (by weight, the same below) of isopentanol polyoxyethylene ether (molecular weight 2400) and 300 parts of tricyclazole suspension were put into a reaction kettle, the stirrer was started, and the mixture was heated to 40° C. and stirred until completely dissolved;

[0050] 2) After the monomers are dissolved in step 1), 3.2 parts of hydrogen peroxide and 5 parts of tristyrylphenol polyoxyethylene ether phosphate are added into the reaction kettle under stirring;

[0051] 3) After stirring for 10 minutes in step 2), 25 parts of acrylic acid were mixed with 30 parts of water to prepare solution A; 0.45 parts of ascorbic acid, 1.8 parts of mercaptopropionic acid and 90 parts of water were mixed to prepare solution B; after the preparation was completed, solution A and solution B were added dropwise at the same time, solution A was added dropwise over 2 hours, and solution B was added dropwise over 2.5 hours;

[0052] 4) After the reaction in step 3) is completed, the mixture is kept warm for 1 hour, and then 9 parts of a 32% sodium hydroxide solution are added for neutralization, and the pH value is adjusted to 6-7 to obtain the large-impedance mud-type polycarboxylate water reducer.

[0053] Example 2

[0054] A large steric hindrance, low dosage, anti-mud type polycarboxylate water reducer, the preparation method of which comprises the following steps:

[0055] 1) 330 parts of methyl allyl alcohol polyoxyethylene ether (molecular weight 2400) and 300 parts of tricyclazole suspension concentrate were put into a reaction kettle, the stirrer was started, and the mixture was heated to 40° C. and stirred until completely dissolved;

[0056] 2) After the monomers are dissolved in step 1), 3.5 parts of ammonium persulfate and 6 parts of tristyrylphenol polyoxyethylene ether phosphate are added into the reaction kettle under stirring;

[0057] 3) After stirring for 10 minutes in step 2), 25 parts of acrylic acid were mixed with 30 parts of water to prepare solution A; 0.48 parts of sodium bisulfite, 1.8 parts of mercaptopropionic acid and 90 parts of water were mixed to prepare solution B; after the preparation was completed, solution A and solution B were added dropwise at the same time, solution A was added dropwise over 2 hours, and solution B was added dropwise over 2.5 hours;

[0058] 4) After the reaction in step 3) is completed, the mixture is aged for 1 hour, and then 9 parts of a 32% sodium hydroxide solution are added for neutralization, and the pH value is adjusted to 6-7 to obtain the large-impedance mud-type polycarboxylate water-reducing agent.

[0059] Example 3

[0060] A large steric hindrance, low dosage, anti-mud type polycarboxylate water reducer, the preparation method of which comprises the following steps:

[0061] 1) 345 parts of pentenol polyoxyethylene ether (molecular weight 3000) and 300 parts of tricyclazole suspension were put into a reaction kettle, the stirrer was started, and the mixture was heated to 40° C. and stirred until completely dissolved;

[0062] 2) After the monomers are dissolved in step 1), 3.9 parts of potassium persulfate and 8 parts of tristyrylphenol polyoxyethylene ether phosphate are added into the reaction kettle under stirring;

[0063] 3) After stirring in step 2) for 10 minutes, 22 parts of maleic anhydride and 30 parts of water were mixed to prepare solution A; 0.45 parts of ascorbic acid, 1.8 parts of mercaptopropionic acid and 90 parts of water were mixed to prepare solution B; after the preparation was completed, solution A and solution B were added dropwise at the same time, solution A was added dropwise over 2 hours, and solution B was added dropwise over 2.5 hours

[0064] 4) After the reaction in step 3) is completed, the mixture is kept warm for 1 hour, and then 9.9 parts of a 32% potassium hydroxide solution is added for neutralization, and the pH value is adjusted to 6-7 to obtain the large-impedance mud-type polycarboxylate water-reducing agent.

[0065] Example 4

[0066] A large steric hindrance, low dosage, anti-mud type polycarboxylate water reducer, the preparation method of which comprises the following steps:

[0067] 1) 330 parts of pentenol polyoxyethylene ether (molecular weight 2500) and 310 parts of tricyclazole suspension were put into a reaction kettle, the stirrer was started, and the mixture was heated to 40° C. and stirred until completely dissolved;

[0068] 2) After the monomers are dissolved in step 1), 3.2 parts of hydrogen peroxide and 10 parts of tristyrylphenol polyoxyethylene ether phosphate are added into a reaction kettle under stirring;

[0069] 3) After stirring for 10 minutes in step 2), 26 parts of acrylic acid and 30 parts of water were mixed to prepare solution A; 0.45 parts of ascorbic acid, 2.2 parts of thioglycolic acid and 90 parts of water were mixed to prepare solution B; after the preparation was completed, solution A and solution B were added dropwise at the same time, solution A was added dropwise over 2 hours, and solution B was added dropwise over 2.5 hours;

[0070] 4) After the reaction in step 3) is completed, the mixture is kept warm for 1 hour, and then 9.5 parts of a 32% sodium hydroxide solution is added for neutralization, and the pH value is adjusted to 6-7 to obtain the large-impedance mud-type polycarboxylate water-reducing agent.

[0071] Comparative Example 1

[0072] A method for preparing a polycarboxylate water-reducing agent comprises the following steps:

[0073] 1) 320 parts of isopentanol polyoxyethylene ether (molecular weight 2400) and 300 parts of water were put into a reaction kettle, the stirrer was started, and the mixture was heated to 40° C. and stirred until completely dissolved;

[0074] 2) After the monomers are dissolved in step 1), 3.2 parts of hydrogen peroxide and 5 parts of tristyrylphenol polyoxyethylene ether phosphate are added into the reaction kettle under stirring;

[0075] 3) After stirring for 10 minutes in step 2), 25 parts of acrylic acid were mixed with 30 parts of water to prepare solution A; 0.45 parts of ascorbic acid, 1.8 parts of mercaptopropionic acid and 90 parts of water were mixed to prepare solution B; after the preparation was completed, solution A and solution B were added dropwise at the same time, solution A was added dropwise over 2 hours, and solution B was added dropwise over 2.5 hours;

[0076] 4) After the reaction in step 3) is completed, the mixture is aged for 1 hour, and then 9 parts of a 32% sodium hydroxide solution are added for neutralization, and the pH value is adjusted to 6-7 to obtain the large-impedance mud-type polycarboxylate water-reducing agent.

[0077] Comparative Example 2

[0078] A polycarboxylate water-reducing agent, the preparation method of which comprises the following steps:

[0079] 1) 320 parts of isopentanol polyoxyethylene ether (molecular weight 2400) and 300 parts of water were put into a reaction kettle, the stirrer was started, and the mixture was heated to 40° C. and stirred until completely dissolved;

[0080] 2) After the monomer is dissolved in step 1), add 3.2 parts of hydrogen peroxide into the reactor under stirring.

[0081] 3) After stirring in step 2) for 10 minutes, 25 parts of acrylic acid were mixed with 30 parts of water to prepare solution A; 0.45 parts of ascorbic acid, 1.8 parts of mercaptopropionic acid and 90 parts of water were mixed to prepare solution B; after the preparation was completed, solution A and solution B were added dropwise at the same time, solution A was added dropwise over 2 hours, and solution B was added dropwise over 2.5 hours

[0082] 4) After the reaction in step 3) is completed, the mixture is aged for 1 hour, and then 9 parts of a 32% sodium hydroxide solution are added for neutralization, and the pH value is adjusted to 6-7 to obtain the large-impedance mud-type polycarboxylate water-reducing agent.

[0083] Comparative Example 3

[0084] A polycarboxylate water reducer, the preparation method of which is substantially the same as that of Example 1, except that: in step 2), the same mass of 2-hydroxyethyl methacrylate phosphate is used instead of tristyrylphenol polyoxyethylene ether phosphate

[0085] Comparative Example 4

[0086] A polycarboxylate water reducer, the preparation method of which is substantially the same as that of Example 1, except that in step 2), styrene of the same mass is used instead of tristyrylphenol polyoxyethylene ether phosphate

[0087] Comparative Example 5

[0088] A polycarboxylate water reducer, the preparation method of which is substantially the same as that of Example 1, except that styrene and 2-hydroxyethyl methacrylate phosphate (mass ratio 1:1) are added simultaneously in step 2), and the replacement mass is the same as that of tristyrylphenol polyoxyethylene ether phosphate.

[0089] Performance testing

[0090] The polycarboxylate water-reducing agents in Examples 1 to 4 and Comparative Examples 1 to 4 were tested according to GB / T8077-2012 "Test Method for Homogeneity of Concrete Admixtures". A certain mass of soil was added to cement, and the polycarboxylate water-reducing agent was added to mix the cement paste. The fluidity of the cement paste was tested.

[0091] Experimental materials: standard cement PO42.5, fixed water-binder ratio of 0.29, conventional montmorillonite soil, the dosage is 0-6% of cement mass, and the solid dosage of polycarboxylate water reducer is 0.13%. The test results are shown in Table 1

[0092] Table 1 Test results of embodiments and comparative examples

[0093]

[0094] Combining Examples 1-4 and Table 1, it can be seen that under different mud contents, the initial fluidity and 1h fluidity retention of the cement paste of Examples 1-4 first increase and then remain unchanged. The reason is that when the degree of polymerization of the synthetic main chain has not reached saturation, with the increase in the amount of tristyrylphenol polyoxyethylene ether phosphate, the dispersing effect and anti-mud effect of the water reducer are improved; when the added amount reaches the saturation point of the main chain polymerization degree, the excess amount will not participate in the reaction.

[0095] Combining Examples 1-4 with Comparative Example 1 and Table 1, it can be seen that without adding a suspending agent during synthesis, tristyrylphenol polyoxyethylene ether phosphate is difficult to participate in polymerization in aqueous solution, resulting in a low conversion rate of the synthesized water reducer and failure to play the role of anti-mud and reducing the dosage.

[0096] Combining Examples 1-4 with Comparative Example 2 and Table 1, it can be seen that with the increase of mud content, the fluidity of the five water reducers decreases, but the dispersion effect and fluidity retention effect of Examples 1-4 are better than that of the water reducer synthesized by the conventional method, namely Comparative Example 2, indicating that the introduced tristyrylphenol polyoxyethylene ether phosphate plays a role in reducing mud resistance and reducing the dosage.

[0097] Combining Examples 1-4 with Comparative Example 3 and Table 1, it can be seen that the initial fluidity and 1h fluidity of the cement paste in Comparative Example 3 do not decrease much with the increase of mud content. However, at the same dosage of water reducer, the initial fluidity of the cement paste in Examples 1-4 is greater and the 1h fluidity retention is better. The reason is that although the anti-mud group phosphate is introduced in Comparative Example 3, it cannot play a role in reducing the dosage.

[0098] Combining Examples 1-4 with Comparative Example 4 and Table 1, it can be seen that when the mud content is 0, the initial fluidity and 1h fluidity of the cement paste of Comparative Example 4 are not much different from those of Examples 1-4. However, as the mud content increases, the dispersion effect and fluidity retention effect of Comparative Example 4 decrease significantly.

[0099] Combining Examples 1-4 with Comparative Examples 3-5 and Table 1, it can be seen that although Comparative Example 5 simultaneously introduces two functional monomers containing phosphate esters and benzene rings, the dispersion effect and fluidity retention effect are worse than those of Examples 1-4 and Comparative Examples 3-5.

[0100] In summary, the preparation method of the large steric hindrance, low dosage and mud-resistant polycarboxylic acid water-reducing agent of the embodiment of the present application can be used in concrete with high mud content to reduce the dosage of the water-reducing agent and reduce the adsorption of mud on the water-reducing agent.

[0101] The above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above descriptions. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. A large impedance mud type polycarboxylate water reducer, characterized in that: It is a block copolymer formed by unsaturated polyoxyethylene ether monomers, tristyrylphenol polyoxyethylene ether phosphate monomers and unsaturated carboxylic acid monomers.

2. The large impedance mud type polycarboxylate water reducer according to claim 1, characterized in that: The unsaturated polyoxyethylene ether monomer is one or more of methyl allyl alcohol polyoxyethylene ether, isopentanol polyoxyethylene ether, isobutylene alcohol polyoxyethylene ether, and ethylene glycol monovinyl polyethylene glycol ether; and the molecular weight thereof is 2400-3000.

3. The large impedance mud type polycarboxylate water reducer according to claim 1, characterized in that: The structural formula of the tristyrylphenol polyoxyethylene ether phosphate monomer is shown in Formula I; In the formula, n is 13-29, and Me is selected from Na or K.

4. The large impedance mud type polycarboxylate water reducer according to claim 1, characterized in that: The preparation method of tristyrylphenol polyoxyethylene ether phosphate comprises the following steps: heating tristyrylphenol polyoxyethylene ether under a protective atmosphere, then adding phosphorus oxide thereto under stirring conditions, and continuing to heat the mixture for esterification reaction; adding water for hydrolysis, and then adding polyethylene glycol solution for neutralization and grafting, and adjusting the pH value of the alkali metal-based alkali solution to 6-7 to obtain the tristyrylphenol polyoxyethylene ether phosphate.

5. The large impedance mud type polycarboxylate water reducer according to claim 4, characterized in that: In the preparation method of tristyrylphenol polyoxyethylene ether phosphate, the amounts of the raw materials are: 9-11 parts of tristyrylphenol polyoxyethylene ether, 1-3 parts of phosphorus pentoxide, 9-11 parts of water, and 87-9 parts of polyethylene glycol solution.

6. The large impedance mud type polycarboxylate water reducer according to claim 4, characterized in that: The temperature used for the esterification reaction is 110-120° C. and the time is 2.5-3 hours.

7. The large impedance mud type polycarboxylate water reducer according to claim 1, characterized in that: The unsaturated carboxylic acid is one or more of acrylic acid, methacrylic acid and maleic anhydride.

8. The large impedance mud type polycarboxylate water reducer according to claim 1, characterized in that: The mass ratio of the unsaturated polyoxyethylene ether monomer, the tristyrylphenol polyoxyethylene ether phosphate monomer and the unsaturated carboxylic acid monomer is 320-350:5-10:22-27.

9. The method for preparing the large steric hindrance, low dosage, anti-mud polycarboxylate water reducer according to any one of claims 1 to 8, characterized in that: The steps include: 1) adding unsaturated polyoxyethylene ether monomer and suspending agent into a reaction kettle, and heating and stirring to completely dissolve the polyether macromonomer in the suspending agent; 2) adding the oxidant and tristyrylphenol polyoxyethylene ether phosphate into the reaction kettle and stirring evenly; 3) Mix unsaturated carboxylic acid with water and stir to obtain liquid A; mix reducing agent and chain transfer agent with water and stir to obtain liquid B; 5) At room temperature, liquid A and liquid B are uniformly added to the reaction kettle, and after the addition is completed, the mixture is stirred for reaction. After the reaction is completed, the mixture is heat-insulated for aging, and an alkali solution is added to adjust the pH value, thereby obtaining the large-impedance mud-type polycarboxylate water-reducing agent.

10. The preparation method according to claim 9, characterized in that: The raw materials used include, by weight: 320-350 parts of unsaturated polyoxyethylene ether, 290-310 parts of suspending agent, 0.1-0.2 parts of chain transfer agent, 3-4 parts of oxidant, 0.3-0.5 parts of reducing agent, 22-27 parts of unsaturated carboxylic acid and 5-10 parts of tristyrylphenol polyoxyethylene ether phosphate.

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