Mud-resistant polycarboxylic acid water-reducing mother solution and preparation method thereof

Abstract

The preparation method comprises the following steps: dissolving an unsaturated polyoxyethylene ether macromonomer and a functional monomer R1 in deionized water, and stirring the mixed solution at a water bath temperature, so that the macromonomer and the functional monomer R1 are fully dissolved and uniformly mixed; sequentially adding strong acid type cation exchange resin and part of unsaturated carboxylic acid polymerization small monomers, then adding an initiator, and stirring for a period of time; stirring is kept, a solution A prepared from a functional monomer R2, an unsaturated carboxylic acid polymerization small monomer and deionized water and a solution B prepared from a chain transfer agent, a reducing agent and deionized water are slowly added in sequence, then ion exchange resin is filtered and recycled, and a neutralization material is added to adjust the PH. The mud-resistant polycarboxylic acid water-reducing mother solution based on a strong acid type cation exchange resin catalysis technology and a functional monomer modification technology is synthesized, and the mud resistance of a polycarboxylic acid water reducing agent is improved, so that the construction performance, the mechanical property, the durability and the like of cement concrete are improved.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, and more specifically to an anti-mud type polycarboxylate water-reducing concentrate and a preparation method thereof. Background Art

[0002] As an important branch of civil engineering materials, concrete has a development history of more than 200 years. On the one hand, with the continuous development of the civil engineering field, high-strength, high-pumpability and high-durability concrete has become a development trend. On the other hand, cement concrete faces unprecedented challenges of low-carbon development. In the process of rapid development of the concrete industry, as the "sixth component" of mixing concrete, the research and development of concrete admixtures has gradually deepened.

[0003] Water reducer is an important admixture for concrete. It has a dispersing effect on cement particles in fresh concrete. It can improve the workability of concrete, reduce construction energy consumption, and improve construction efficiency without changing the composition of the various components of concrete. Or, under the premise of keeping the workability of the concrete premix unchanged, it can reduce the unit water consumption, reduce the water-cement ratio of concrete, and improve the strength and stability of concrete.

[0004] Water reducers have developed into three generations of products, namely the first generation (ordinary) water reducers represented by wood calcium, the second generation (high-efficiency) water reducers represented by naphthalene series, and the third generation (high-performance) water reducers represented by polycarboxylates. With the improvement of civil engineering requirements for materials, the first and second generation water reducers have gradually been unable to meet the requirements of actual concrete engineering, especially high-performance concrete. It has become an urgent need to seek upgraded products for concrete water reducers.

[0005] As the third generation of water reducers, polycarboxylate water reducers are favored for their high water reduction rate, strong molecular designability, multiple synthesis technologies, green environmental protection and many other advantages. However, current polycarboxylate water reducers still have problems such as weak adaptability to cement and poor mud resistance. Specifically, the mud content in sand and gravel aggregates will significantly reduce the water reduction and slump retention capabilities of polycarboxylate water reducers, affecting the quality of concrete.

[0006] Therefore, the development of anti-mud polycarboxylate water reducer has become an urgent need in my country's civil engineering and construction fields. Summary of the invention

[0007] The invention provides an anti-mud type polycarboxylate water-reducing concentrate and a preparation method thereof, which improves the anti-mud performance of the polycarboxylate water-reducing agent and has environmental protection and economic value.

[0008] According to one aspect of the present invention, there is provided an anti-mud polycarboxylic acid water-reducing concentrate, comprising the following raw materials, by mass percentage: 30-37% of unsaturated polyoxyethylene ether macromonomer, 1-4% of functional monomer R1, 0.8-4% of functional monomer R2, 0.1%-1.5% of initiator, 3.5-6% of unsaturated carboxylic acid polymerization small monomer, 0.1%-1.5% of chain transfer agent, 0.03-0.5% of reducing agent, 59-61% of deionized water, neutralizing material, and strong acid cation exchange resin.

[0009] Preferably, based on the above scheme, the unsaturated polyoxyethylene ether macromonomer is isopentanol polyoxyethylene ether.

[0010] Preferably, based on the above scheme, the functional monomer R1 is one or both of sodium methyl methacrylate sulfonate and 2-acrylamide-2-methylpropane sulfonic acid, and the functional monomer R2 is acrylamide.

[0011] Preferably, based on the above scheme, the initiator is one or both of hydrogen peroxide solution and ammonium persulfate.

[0012] Preferably, based on the above scheme, the unsaturated carboxylic acid polymerizable small monomer is acrylic acid, the chain transfer agent is 3-mercaptopropionic acid, and the reducing agent is ascorbic acid.

[0013] The present invention also provides a method for preparing an anti-mud type polycarboxylic acid water-reducing mother liquor, comprising the following steps:

[0014] Step S1, dissolving the unsaturated polyoxyethylene ether macromonomer and the functional monomer R1 in deionized water, stirring the mixed solution at a water bath temperature to fully dissolve and evenly mix the macromonomer and the functional monomer R1, and ensuring that the concentrations of the unsaturated polyoxyethylene ether macromonomer and the functional monomer R1 decrease in proportion during the reaction;

[0015] Step S2, first add a strong acid cation exchange resin, then add an unsaturated carboxylic acid polymerization monomer, react for 5 to 10 minutes, add an initiator, and react for 10 to 15 minutes;

[0016] Step S3, preparing a solution A by mixing the functional monomer R2, the unsaturated carboxylic acid polymerizable monomer and deionized water, so that the functional monomer R2 and the unsaturated carboxylic acid polymerizable monomer maintain a similar ratio during the reaction, adding the solution A to the solution formed by S2, and gradually reducing the dropping speed, so that the concentrations of the functional monomer R2 and the unsaturated carboxylic acid polymerizable monomer gradually decrease during the reaction;

[0017] Step S4, preparing a chain transfer agent, a reducing agent and deionized water into a B solution, and adding the B solution to the solution formed in S3, maintaining a uniform dropwise addition speed;

[0018] Step S5, thermal insulation and aging;

[0019] Step S6, filtering and recovering the strong acidic cation exchange resin, and adding a neutralizing material to adjust the pH.

[0020] Preferably, based on the above scheme, from step S1 to step S5, the temperature of the reaction system is controlled at 20-40° C., and the stirring speed of the stirrer is controlled at 300-1000 rpm.

[0021] Preferably, based on the above scheme, the dropping time in step S3 is 1 to 2 hours, the dropping time in step S4 is 1.5 to 2.5 hours, and the dropping time in step S4 is 20 to 40 minutes longer than that in step S3.

[0022] Preferably, based on the above scheme, the aging time in step S5 is 0.5 to 1 hour.

[0023] The anti-mud polycarboxylate water-reducing concentrate of the present invention has the following beneficial effects:

[0024] 1. The anti-mud polycarboxylic acid water-reducing concentrate and the preparation method thereof of the present invention are as follows: the unsaturated polyoxyethylene ether macromonomer and the functional monomer R1 are first dissolved and mixed evenly; during the synthesis process, the concentrations of the unsaturated polyoxyethylene ether macromonomer and the functional monomer R1 are reduced in proportion, so that the distribution of the functional monomer R1 in the molecular chain is consistent with that of the side chain, and the anti-mud effect of the functional group is effectively exerted.

[0025] 2. The anti-mud polycarboxylic acid water-reducing concentrate and preparation method thereof of the present invention use a strong acid cation exchange resin to promote hydrogen peroxide and (or) sodium persulfate initiator to generate stable free radicals, improve the stability and efficiency of free radical polymerization, shorten the reaction time, lower the reaction temperature, and reduce production costs.

[0026] 3. The anti-mud polycarboxylic acid water-reducing concentrate and preparation method thereof of the present invention, before adding the functional monomer R2, the unsaturated carboxylic acid polymerization small monomer and the solution prepared by deionized water for polymerization, firstly add the unsaturated carboxylic acid for "prepolymerization", which can effectively improve the efficiency of the subsequent reaction and enhance the dispersing effect of the polycarboxylic acid water-reducing agent.

[0027] 4. In the anti-mud type polycarboxylic acid water-reducing concentrate and the preparation method thereof of the present invention, the functional monomers R1 and R2 play a synergistic role, and the acrylamide and sulfonic acid group functional monomers cooperate with each other, showing a better dispersion effect and anti-mud effect.

[0028] 5. The anti-mud polycarboxylic acid water-reducing concentrate and preparation method thereof of the present invention prepare the functional monomer R2 and the unsaturated carboxylic acid polymerization small monomer into a solution and simultaneously introduce them into the reaction system. The presence of acrylamide can optimize the free radical polymerization process. Meanwhile, the functional monomer R2 and the unsaturated carboxylic acid polymerization small monomer maintain a similar ratio during the reaction process, so that the distribution of acrylamide molecules in the polycarboxylic acid molecules is the same as that of acrylic acid, thereby optimizing the molecular structure of the polycarboxylic acid, and the formed structure has a better dispersion effect.

[0029] 6. The anti-mud polycarboxylic acid water-reducing mother liquid and its preparation method of the present invention gradually reduce the dripping speed of liquid A, reduce the concentration of the functional monomer R2 unsaturated carboxylic acid polymerization small monomer in the reaction system during the reaction process, avoid forming a polycarboxylic acid molecular structure that is "sparse on the outside and dense on the inside", and improve the dispersion effect of the water reducer.

[0030] 7. The anti-mud polycarboxylic acid water-reducing concentrate and its preparation method of the present invention can synthesize a water-reducing concentrate with excellent anti-mud function under normal temperature conditions (20-40°C). Compared with high-temperature production technology, low-temperature production technology, and precise temperature control production technology, it greatly reduces the production difficulty and energy consumption, meets the requirements of green development, and has great economic and environmental value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] In the figure:

[0033] Figure 1 It is the molecular structural formula of the anti-mud type polycarboxylic acid water-reducing concentrate of the present invention. DETAILED DESCRIPTION

[0034] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0035] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections.

[0036] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0037] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation of the present invention will be described below with reference to the accompanying drawings.

[0039] The present invention discloses an anti-mud polycarboxylic acid water-reducing concentrate, which comprises the following raw materials by mass percentage: 30-37% of unsaturated polyoxyethylene ether macromonomer, 1-4% of functional monomer R1, 0.8-4% of functional monomer R2, 0.1%-1.5% of initiator, 3.5-6% of unsaturated carboxylic acid polymerization small monomer, 0.1%-1.5% of chain transfer agent, 0.03-0.5% of reducing agent, 59-61% of deionized water, neutralizing material, and strong acid cation exchange resin. For specific molecular structure formula, please refer to Figure 1 shown.

[0040] Among them, the unsaturated polyoxyethylene ether macromonomer is isopentanol polyoxyethylene ether, the functional monomer R1 is one or both of sodium methyl propylene sulfonate and 2-acrylamide-2-methylpropane sulfonic acid, the functional monomer R2 is acrylamide, the initiator is one or both of hydrogen peroxide solution and ammonium persulfate, the unsaturated carboxylic acid polymerization small monomer is acrylic acid, the chain transfer agent is 3-mercaptopropionic acid, and the reducing agent is ascorbic acid.

[0041] Among them, the molecular formula of the anti-mud polycarboxylic acid water-reducing concentrate is as follows Figure 1 As shown, when preparing the above-mentioned anti-mud type polycarboxylic acid water-reducing mother liquid, the specific preparation method is as follows:

[0042] Step S1, dissolving the unsaturated polyoxyethylene ether macromonomer and the functional monomer R1 in deionized water, stirring the mixed solution at a water bath temperature to fully dissolve and evenly mix the macromonomer and the functional monomer R1, and ensuring that the concentrations of the unsaturated polyoxyethylene ether macromonomer and the functional monomer R1 decrease in proportion during the reaction;

[0043] Step S2, first add a strong acid cation exchange resin, then add an unsaturated carboxylic acid polymerization monomer, react for 5 to 10 minutes, add an initiator, and react for 10 to 15 minutes;

[0044] Step S3, preparing a solution A by mixing the functional monomer R2, the unsaturated carboxylic acid polymerizable monomer and deionized water, so that the functional monomer R2 and the unsaturated carboxylic acid polymerizable monomer maintain a similar ratio during the reaction, adding the solution A to the solution formed by S2, and gradually reducing the dropping speed, so that the concentrations of the functional monomer R2 and the unsaturated carboxylic acid polymerizable monomer gradually decrease during the reaction;

[0045] Step S4, preparing a chain transfer agent, a reducing agent and deionized water into a B solution, and adding the B solution to the solution formed in S3, maintaining a uniform dropwise addition speed;

[0046] Step S5, thermal insulation and aging;

[0047] Step S6, filtering and recovering the strong acidic cation exchange resin, and adding a neutralizing material to adjust the pH.

[0048] Among them, from step S1 to step S5, the temperature of the reaction system is controlled at 20-40°C, the stirring speed of the stirrer is controlled at 300-1000rpm, the dropping time in step S3 is 1-2h, the dropping time in step S4 is 1.5-2.5h, and the dropping time in step S4 is 20-40min longer than that in step S3, and the aging time in step S5 is 0.5-1h.

[0049] Below, in order to illustrate the experimental effects of the present invention in detail, the technical effects of the present invention will be experimentally illustrated with specific embodiments, wherein the raw material ratios of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1. The raw material ratio table is as follows.

[0050] Table 1 Raw material ratio table

[0051]

[0052] Example 1

[0053] Example 1 The preparation method is as follows:

[0054] Step 1: dissolving isopentanol polyoxyethylene and 2-acrylamide-2-methylpropanesulfonic acid in 50% deionized water, stirring the mixed solution at a water bath temperature of 40° C. with a stirrer at a stirring speed of 400 rpm until the mixed solution is uniform;

[0055] Step 2: first add strong acid cation exchange resin, then add 0.7% acrylic acid, keep the reaction system temperature at 40°C, stir at 400 rpm, stir for 5 min, add ammonium persulfate, keep the reaction system temperature at 40°C, stir at 400 rpm, stir for 15 min;

[0056] Step 3: Prepare solution A: Mix 4.0% acrylic acid, acrylamide and 5.0% deionized water to form solution A, keep the reaction system temperature at 40°C, stir at 400 rpm, stir for 1.5 hours, and evenly add solution A;

[0057] Step 4: Prepare solution B: mix 3-mercaptopropionic acid, ascorbic acid and 5% deionized water to form solution B, keep the reaction system temperature at 40°C, stir at 400 rpm, stir for 2 hours, and evenly add solution B;

[0058] Step 5: Thermal aging: Keep the reaction system temperature at 40°C, the stirring speed of the stirrer at 400 rpm, and stir for 1 hour;

[0059] Step 6: Add sodium hydroxide solution to adjust the pH to 6-7 to obtain the anti-mud polycarboxylic acid water-reducing mother liquor.

[0060] Example 2

[0061] Embodiment 2 preparation method is as follows:

[0062] Step 1: dissolving isopentanol polyoxyethylene ether and sodium methacrylate sulfonate in 50% deionized water, stirring the mixed solution at a water bath temperature of 30° C. with a stirrer at a stirring speed of 600 rpm until the mixed solution is uniform;

[0063] Step 2: First add strong acid cation exchange resin, then add 1.0% acrylic acid, keep the reaction system temperature at 30°C, stir at 600rpm, stir for 7min, add hydrogen peroxide solution and ammonium persulfate, keep the reaction system temperature at 30°C, stir at 600rpm, stir for 12min;

[0064] Step 3: Prepare solution A: Mix 2.7% acrylic acid, acrylamide and 5.0% deionized water to form solution A, keep the reaction system temperature at 30°C, stir at 600 rpm, stir for 2 hours, and evenly add solution A;

[0065] Step 4: Prepare solution B: mix 3-mercaptopropionic acid, ascorbic acid and 5% deionized water to form solution B, keep the reaction system temperature at 30°C, stir at 600 rpm, stir for 2.5 hours, and evenly add solution B;

[0066] Step 5: Thermal aging: Keep the reaction system temperature at 30°C, stir at 600 rpm, and stir for 40 minutes;

[0067] Step 6: Add sodium hydroxide solution to adjust the pH to 6-7 to obtain the anti-mud polycarboxylic acid water-reducing mother liquor.

[0068] Example 3

[0069] Example 3 The preparation method is as follows:

[0070] Step 1: dissolving isopentanol polyoxyethylene ether, 2-acrylamide-2-methylpropane sulfonic acid and sodium methyl propene sulfonate in 50% deionized water, stirring the mixed solution at a stirring speed of 300 rpm with a stirrer at a water bath temperature of 25° C. until the mixed solution is uniform;

[0071] Step 2: First add strong acid cation exchange resin, then add 0.7% acrylic acid, keep the reaction system temperature at 25°C, stir at 600 rpm, stir for 5 min, add hydrogen peroxide solution, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 15 min;

[0072] Step 3: Prepare solution A: Mix 3.5% acrylic acid, acrylamide and 5.0% deionized water to form solution A, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 1.5 hours, and evenly add solution A;

[0073] Step 4: Prepare solution B: mix 3-mercaptopropionic acid, ascorbic acid and 5% deionized water to form solution B, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 2 hours, and evenly add solution B;

[0074] Step 5: Thermal aging: Keep the reaction system temperature at 25°C, stir at 300 rpm, and stir for 30 minutes;

[0075] Step 6: Add sodium hydroxide solution to adjust the pH to 6-7 to obtain the anti-mud polycarboxylic acid water-reducing mother liquor.

[0076] Comparative Example 1

[0077] Comparative Example 1 The preparation method is as follows:

[0078] Step 1: dissolving isopentanol polyoxyethylene ether in 50% deionized water, stirring the mixed solution at a water bath temperature of 25° C. with a stirrer at a stirring speed of 300 rpm until the mixed solution is uniform;

[0079] Step 2: Add 0.7% acrylic acid, keep the reaction system temperature at 25°C, stir at 600 rpm, stir for 5 min, add hydrogen peroxide solution, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 15 min;

[0080] Step 3: Prepare solution A: Mix 3.7% acrylic acid and 5.0% deionized water to form solution A, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 1.5 hours, and evenly add solution A;

[0081] Step 4: Prepare solution B: mix 3-mercaptopropionic acid, ascorbic acid and 5% deionized water to form solution B, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 2 hours, and evenly add solution B;

[0082] Step 5: Thermal aging: Keep the reaction system temperature at 25°C, stir at 300 rpm, and stir for 30 minutes;

[0083] Step 6: Add sodium hydroxide solution to adjust the pH to 6-7 to obtain the anti-mud polycarboxylic acid water-reducing mother liquor.

[0084] Comparative Example 2

[0085] Comparative Example 2 The preparation method is as follows:

[0086] Step 1: dissolving isopentanol polyoxyethylene ether, 2-acrylamide-2-methylpropane sulfonic acid and sodium methyl propene sulfonate in 50% deionized water, stirring the mixed solution at a stirring speed of 300 rpm with a stirrer at a water bath temperature of 25° C. until the mixed solution is uniform;

[0087] Step 2: Add hydrogen peroxide solution, keep the reaction system temperature at 25°C, stir at 300 rpm, and stir for 15 minutes;

[0088] Step 3: Prepare solution A: Mix 4.2% acrylic acid, acrylamide and 5.0% deionized water to form solution A, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 1.5 hours, and evenly add solution A;

[0089] Step 4: Prepare solution B: mix 3-mercaptopropionic acid, ascorbic acid and 5% deionized water to form solution B, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 2 hours, and evenly add solution B;

[0090] Step 5: Thermal aging: Keep the reaction system temperature at 25°C, stir at 300 rpm, and stir for 30 minutes;

[0091] Step 6: Add sodium hydroxide solution to adjust the pH to 6-7 to obtain the anti-mud polycarboxylic acid water-reducing mother liquor.

[0092] Comparative Example 3

[0093] The preparation method of Comparative Example 3 is as follows:

[0094] Step 1: dissolving methyl allyl polyoxyethylene ether, 2-acrylamide-2-methylpropane sulfonic acid and sodium methyl propene sulfonate in 50% deionized water, stirring the mixed solution at a stirring speed of 300 rpm with a stirrer at a water bath temperature of 25° C. until the mixed solution is uniform;

[0095] Step 2: Add 0.7% acrylic acid, keep the reaction system temperature at 25°C, stir at 600 rpm, stir for 5 min, add hydrogen peroxide solution, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 15 min;

[0096] Step 3: Prepare solution A: Mix 3.5% acrylic acid, acrylamide and 5.0% deionized water to form solution A, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 1.5 hours, and evenly add solution A;

[0097] Step 4: Prepare solution B: mix 3-mercaptopropionic acid, ascorbic acid and 5% deionized water to form solution B, keep the reaction system temperature at 25°C, stir at 300 rpm, stir for 2 hours, and evenly add solution B;

[0098] Step 5: Thermal aging: Keep the reaction system temperature at 25°C, stir at 300 rpm, and stir for 30 minutes;

[0099] Step 6: Add sodium hydroxide solution to adjust the pH to 6-7 to obtain the anti-mud polycarboxylic acid water-reducing mother liquor.

[0100] Implementation Effect

[0101] (1) Cement paste fluidity test

[0102] The polycarboxylate water-reducing concentrates of Examples 1 to 3 and Comparative Examples 1 to 3 were used in the cement paste fluidity test. The materials used were: 300 g of cement, 87 g of water, and polycarboxylate water-reducing concentrate. The test results are shown in Table 2:

[0103] Table 2 Test results of cement paste fluidity

[0104]

[0105] (2) Concrete application performance test

[0106] The water reducing concentrates prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were compounded with other admixtures to form a water reducing agent for concrete application performance testing. The concrete used was C30 underwater concrete, the mix ratio of which was shown in Table 3, in which the powder content of machine-made sand was about 14%.

[0107] Table 3 Concrete application performance test mix ratio

[0108] cement Fly ash Machine-made sand Large gravel Medium crushed stone Small gravel water Water reducing agent 312 78 789 314 524 209 164 39

[0109] The test results of concrete application performance are shown in Table 4:

[0110] Table 4 Concrete application performance test results

[0111]

[0112] The above test results show that the water-reducing mother liquor prepared in the embodiment has a better water-reducing effect than the comparative example. When applied to machine-made sand concrete with a higher powder content, the water-reducing mother liquor in the embodiment can adapt well and the concrete is in good condition; the water-reducing mother liquor in the comparative example has poor adaptability and the concrete is in poor condition. The anti-mud polycarboxylic acid water-reducing mother liquor prepared by the present invention can adapt well to concrete with a higher powder content.

[0113] The present invention provides an anti-mud type polycarboxylic acid water-reducing concentrate and a preparation method thereof, which has the following beneficial effects and technical points:

[0114] 1. The main reason for the poor mud resistance of polycarboxylic acid water-reducing agent is that the powder or mud in the aggregate contains components such as montmorillonite, which will adsorb the side chains of polycarboxylic acid molecules between layers, restrict the movement of polycarboxylic acid molecules, and reduce the number of free polycarboxylic acid molecules in the system, thereby reducing the dispersion effect of the water-reducing agent. The mud-resistant polycarboxylic acid water-reducing mother liquor of the present invention and the preparation method thereof are to first dissolve and mix the unsaturated polyoxyethylene ether macromonomer and the functional monomer R1 uniformly, and during the synthesis process, the concentrations of the unsaturated polyoxyethylene ether macromonomer and the functional monomer R1 decrease in proportion, so that the functional monomer R1 in the molecular chain is distributed consistently with the side chain, and the anti-mud effect of the functional group is effectively exerted.

[0115] 2. The anti-mud polycarboxylic acid water-reducing concentrate and preparation method thereof of the present invention use a strong acid cation exchange resin to promote hydrogen peroxide and (or) sodium persulfate initiator to generate stable free radicals, improve the stability and efficiency of free radical polymerization, shorten the reaction time, lower the reaction temperature, and reduce production costs.

[0116] 3. The anti-mud polycarboxylic acid water-reducing mother liquid and its preparation method of the present invention, before adding liquid A for polymerization, first add unsaturated carboxylic acid for "prepolymerization", which can effectively improve the efficiency of subsequent reactions and enhance the dispersing effect of the polycarboxylic acid water-reducing agent.

[0117] 4. In the anti-mud type polycarboxylic acid water-reducing concentrate and the preparation method thereof of the present invention, the functional monomers R1 and R2 play a synergistic role, and the acrylamide and sulfonic acid group functional monomers cooperate with each other, showing a better dispersion effect and anti-mud effect.

[0118] 5. The anti-mud polycarboxylic acid water-reducing concentrate and preparation method thereof of the present invention prepare the functional monomer R2 and the unsaturated carboxylic acid polymerization small monomer into a solution and simultaneously introduce them into the reaction system. The presence of acrylamide can optimize the free radical polymerization process. Meanwhile, the functional monomer R2 and the unsaturated carboxylic acid polymerization small monomer maintain a similar ratio during the reaction process, so that the distribution of acrylamide molecules in the polycarboxylic acid molecules is the same as that of acrylic acid, thereby optimizing the molecular structure of the polycarboxylic acid, and the formed structure has a better dispersion effect.

[0119] 6. The anti-mud polycarboxylic acid water-reducing mother liquid and its preparation method of the present invention gradually reduce the dripping speed of liquid A, reduce the concentration of the functional monomer R2 unsaturated carboxylic acid polymerization small monomer in the reaction system during the reaction process, avoid forming a polycarboxylic acid molecular structure that is "sparse on the outside and dense on the inside", and improve the dispersion effect of the water reducer.

[0120] 7. The anti-mud polycarboxylic acid water-reducing concentrate and its preparation method of the present invention can synthesize a water-reducing concentrate with excellent anti-mud function under normal temperature conditions (20-40°C). Compared with high-temperature production technology, low-temperature production technology, and precise temperature control production technology, it greatly reduces the production difficulty and energy consumption, meets the requirements of green development, and has great economic and environmental value.

[0121] Finally, the method of the present application is only a preferred implementation scheme and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An anti-mud type polycarboxylate water-reducing concentrate, characterized in that: The invention comprises the following raw materials in percentage by mass: 30-37% of unsaturated polyoxyethylene ether macromonomer, 1-4% of functional monomer R1, 0.8-4% of functional monomer R2, 0.1%-1.5% of initiator, 3.5-6% of unsaturated carboxylic acid polymerization small monomer, 0.1%-1.5% of chain transfer agent, 0.03-0.5% of reducing agent, 59-61% of deionized water, neutralizing material and strong acid cation exchange resin.

2. The anti-mud type polycarboxylate water-reducing concentrate according to claim 1, characterized in that: The unsaturated polyoxyethylene ether macromonomer is prenol polyoxyethylene ether.

3. The anti-mud type polycarboxylate water-reducing concentrate according to claim 1, characterized in that: The functional monomer R1 is one or both of sodium methyl propylene sulfonate and 2-acrylamide-2-methylpropane sulfonic acid, and the functional monomer R2 is acrylamide.

4. The anti-mud type polycarboxylate water-reducing concentrate according to claim 1, characterized in that: The initiator is one or both of hydrogen peroxide solution and ammonium persulfate.

5. The anti-mud type polycarboxylate water-reducing concentrate according to claim 1, characterized in that: The unsaturated carboxylic acid polymerization monomer is acrylic acid, the chain transfer agent is 3-mercaptopropionic acid, and the reducing agent is ascorbic acid.

6. A method for preparing an anti-mud polycarboxylic acid water-reducing concentrate, characterized in that: The steps include: Step S1, dissolving an unsaturated polyoxyethylene ether macromonomer and a functional monomer R1 in deionized water, and stirring the mixed solution at a water bath temperature to fully dissolve the macromonomer and the functional monomer R1 and mix them evenly; Step S2, first add a strong acid cation exchange resin, then add an unsaturated carboxylic acid polymerization monomer, react for 5 to 10 minutes, add an initiator, and react for 10 to 15 minutes; Step S3, preparing a solution A by mixing the functional monomer R2, the unsaturated carboxylic acid polymerizable monomer and deionized water, adding the solution A to the solution formed by S2, and gradually reducing the dropping speed; Step S4, preparing a chain transfer agent, a reducing agent and deionized water into a B solution, and adding the B solution to the solution formed in S3, maintaining a uniform dropwise addition speed; Step S5, thermal insulation and aging; Step S6, filtering and recovering the strong acidic cation exchange resin, and adding a neutralizing material to adjust the pH.

7. The method for preparing an anti-mud type polycarboxylate water-reducing concentrate according to claim 6, characterized in that: From step S1 to step S5, the temperature of the reaction system is controlled at 20-40° C., and the stirring speed of the stirrer is controlled at 300-1000 rpm.

8. The method for preparing an anti-mud type polycarboxylate water-reducing concentrate according to claim 6, characterized in that: The dropping time in step S3 is 1 to 2 hours, the dropping time in step S4 is 1.5 to 2.5 hours, and the dropping time in step S4 is 20 to 40 minutes longer than that in step S3.

9. The method for preparing an anti-mud type polycarboxylate water-reducing concentrate according to claim 6, characterized in that: The aging time in step S5 is 0.5 to 1 hour.

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