Polycarboxylate superplasticizer with high water-reducing rate and preparation method thereof

Abstract

The invention discloses a polycarboxylic acid water reducer with high water-reducing rate. The polycarboxylic acid water reducer comprises a polyether macromonomer agent, sodium hypophosphite, an oxidizing agent, a reducing agent, unsaturated acid and a small monomer dispersing agent, the small monomer dispersing agent is selected from at least one of isosorbide acrylate and isosorbide di (methyl) acrylate. According to the polycarboxylic acid water reducer prepared by the preparation method disclosed by the invention, the small monomer dispersing agent with relatively strong mechanical property and high dispersity is introduced, so that the dispersing capacity can be maintained, the water reducing rate is high, the tolerance to soil in cement sand is high, pores of concrete can be filled, and the concrete can be promoted to generate relatively high strength more quickly, so that the cement structure of the concrete is more compact; and the concrete slump retaining agent has a remarkable effect on concrete slump retaining.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and in particular to a polycarboxylate water-reducing agent with a high water-reducing rate and a preparation method thereof. Background Art

[0002] The development of water reducers has gone through three stages: from lignin-based water reducers to water-soluble resin-based water reducers to the currently most widely used polycarboxylate water reducers. Third-generation polycarboxylate water reducers offer excellent properties, including high water reduction rates, excellent applicability, and environmental friendliness. They have been widely used in projects such as high-speed railways, cross-sea bridges, and high-rise buildings, attracting widespread attention and rapidly becoming a mainstream product in the concrete water reducer market. With the gradual penetration of water reducers in the mortar industry, demand for powdered products is increasing. Currently, powdered products are being widely used in dry-mix mortars such as cement self-leveling grouts, grouting agents, and grouting agents. They fully utilize their water-reducing and strengthening properties in cement-based binders, improving the performance of mortar products.

[0003] In recent years, recycled aggregates have been increasingly used in concrete. Recycled aggregates contain high levels of mud, and their clay minerals can absorb polycarboxylate superplasticizers, impairing their dispersibility and water-reducing properties. Currently, common solutions include increasing the amount of superplasticizer or washing the recycled aggregates, but these methods increase costs and reduce water-reducing performance.

[0004] Therefore, it is necessary to provide some polycarboxylate water-reducing agents with more beneficial functions, especially higher water-reducing rates, to meet the needs of the existing mortar industry. Summary of the Invention

[0005] In order to address the deficiencies of the prior art, the present application provides a polycarboxylate water-reducing agent with a high water-reducing rate and a preparation method thereof, so as to improve the tolerance of the polycarboxylate water-reducing agent to sand in cement, improve the water-reducing rate performance, improve the compressive strength, and have a significant effect on the collapse resistance of concrete.

[0006] In one aspect, the present invention provides a polycarboxylate water-reducing agent with a high water-reduction rate, comprising a polyether macromonomer, sodium hypophosphite, an oxidizing agent, a reducing agent, an unsaturated acid, and a small monomer dispersant.

[0007] Furthermore, the polyether macromonomer includes at least one of methyl allyl alcohol polyoxyethylene ether, isopentanol polyoxyethylene ether, vinyl glycol polyoxyethylene ether, vinyl butanediol polyoxyethylene ether, and diethylene glycol monovinyl ether.

[0008] Furthermore, the oxidant is selected from at least one of hydrogen peroxide, ammonium persulfate, and potassium persulfate.

[0009] Furthermore, the reducing agent is selected from at least one of vitamin C, ferrous sulfate, sodium thiosulfate, ferrous oxide, and ferrosoferric oxide.

[0010] The present invention adopts an oxidant / reducing agent system as an initiator to initiate the polymerization reaction to generate free radicals, which can not only increase the polymerization efficiency but also increase the decomposition efficiency of the oxidant, so that the polymerization temperature of the reaction is low and the polymerization rate is fast.

[0011] Furthermore, the unsaturated acid is selected from at least one of acrylic acid, methacrylic acid, maleic anhydride and itaconic acid.

[0012] Furthermore, the small monomer dispersant is selected from at least one of isosorbide acrylate and isosorbide di(meth)acrylate. The polycarboxylate water-reducing agent of the present invention incorporates a small monomer dispersant into a polyether macromonomer, resulting in high filling efficiency and excellent dispersion of the polyether small monomer. The small monomer dispersant can improve the mechanical and dispersibility of the polycarboxylate water-reducing agent, and its inherent low shrinkage stress enables effective bonding of the various components in the cement. As a binary adhesive, the small monomer dispersant can be incorporated into cement to absorb static electricity, reduce cracks, and enhance crack resistance. The resulting polycarboxylate water-reducing agent exhibits a significant steric hindrance effect, increasing dispersibility and water reduction rate, and improving soil tolerance.

[0013] Furthermore, the polycarboxylate water-reducing agent comprises, by weight, 80-90 parts of a polyether macromonomer, 0.5-1.5 parts of sodium hypophosphite, 0.1-1 parts of an oxidizing agent, 0.1-1 parts of a reducing agent, 5-15 parts of an unsaturated acid, and 1-7 parts of a small monomer dispersant.

[0014] In another aspect, the present invention provides a method for preparing a polycarboxylate water-reducing agent with a high water-reducing rate, comprising the following steps:

[0015] S1: feeding measured water, polyether macromonomer and hypophosphorous acid into a reactor for mixing;

[0016] S2: After the components in the reactor are completely dissolved, add the oxidant;

[0017] S3: Control the temperature in the reactor and add the reducing agent solution dropwise;

[0018] S4: Add the mixed solution of unsaturated acid and small monomer dispersant dropwise at the same time as S3, keep warm after adding, take samples and discharge the materials after they are qualified.

[0019] Furthermore, in S1, the mass fraction of the polyether macromonomer is 40-50%, preferably 40%, 42%, 44%, 45.88%, 46%, 48% or 50%.

[0020] Furthermore, in S1, the mass fraction of the hypophosphorous acid is 0.1-1%, preferably 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 0.9% or 1%.

[0021] Furthermore, the mass concentration of the oxidant is 25-30%, preferably 25%, 26%, 27%, 27.5%, 28%, or 30%.

[0022] Furthermore, in S3, the reaction temperature is 10-25°C, preferably 10°C, 15°C, 20°C and 25°C.

[0023] Furthermore, the mass fraction of vitamin C in the reducing agent solution is 0.1-1%, preferably 0.1%, 0.2%, 0.4%, 0.46%, 0.5%, 0.6%, 0.8% or 1%.

[0024] Furthermore, the mass fraction of ferrous sulfate in the reducing agent solution is 0.1-1%, preferably 0.1%, 0.2%, 0.224%, 0.4%, 0.5%, 0.6%, 0.8% or 1%.

[0025] Furthermore, the reducing agent solution is prepared by dissolving vitamin C and ferrous sulfate in water and stirring evenly.

[0026] Furthermore, in S3, the dripping rate is controlled, and the dripping time is 45 to 60 minutes, preferably 45 minutes, 50 minutes, 55 minutes, or 60 minutes. The specific dripping rate can be calculated based on the volume and time.

[0027] Furthermore, the mass fraction of the unsaturated acid in the mixed solution is 20-30%, preferably 20%, 22%, 24%, 25%, 26%, 26.4%, 27%, 28%, or 30%.

[0028] Furthermore, the mass fraction of the small monomer dispersant in the mixed solution is 10-20%, preferably 10%, 11%, 11.89%, 12%, 15%, 16%, 17%, 18%, 19%, or 20%.

[0029] Furthermore, the mixed solution is prepared by dissolving the unsaturated acid and the small monomer dispersant in water and mixing them uniformly.

[0030] Furthermore, in S4, the dripping rate is controlled, and the dripping time is 45 to 55 minutes, preferably 45 minutes, 50 minutes, or 55 minutes. The specific dripping rate can be calculated based on the volume and time.

[0031] Furthermore, in S4, the temperature is controlled at 40-50° C. and kept warm for 0.5-2 h, preferably at 45° C. and kept warm for 1 h.

[0032] The reaction of the present invention is a continuous feeding reaction with fast reaction speed, high reaction rate and high production efficiency, and can complete the reaction in one pot with multi-step feeding.

[0033] Beneficial effects

[0034] The polycarboxylate water-reducing agent of the present invention comprises raw materials comprising a polyether macromonomer, an unsaturated acid, and a small monomer dispersant, which can be polymerized to produce a macromolecular copolymer containing alkenyl, hydroxyl, carboxyl, ester, and cyclic groups. Compared to conventional polycarboxylate water-reducing agents, the small monomer dispersant exhibits stronger mechanical properties and high dispersibility, maintains dispersibility, has a high water-reduction rate, is tolerant of soil in cement sand, fills pores in concrete, and accelerates the development of higher strength in the concrete, resulting in a denser cement structure and improved compressive strength. This significantly reduces the collapse of the concrete.

[0035] The groups in the polycarboxylate water-reducing agent prepared by the present invention can anchor the surface of cement particles, so that the surface of the cement particles has a negative charge, forming an electrostatic repulsion effect, effectively dispersing the cement particles, releasing part of the encapsulated water, and the water participates in the flow, effectively increasing the fluidity of the concrete and reducing the amount of water used. The hydroxyl groups of the small monomer dispersant adsorb onto the surface of cement particles through hydrogen bonds, forming a hydration film on the cement surface, achieving a water-reducing effect, enhancing fluidity retention, and prolonging the retarding effect during cement hydration. The ether and ester bond segments can reduce the surface tension of the aqueous solution. The carboxyl groups, as hydrophilic and strongly polar groups, provide adsorption sites and electrostatic repulsion, allowing them to adsorb in a targeted manner on the surface of cement particles, forming electrostatic repulsion between cement particles, disrupting the flocculated structure between cement particles, dispersing the particles, releasing free water, and improving mixability. In the alkaline environment of cement, the ester groups release carboxylic acid groups, which carry a negative charge and are more easily electrostatically attracted to calcium ions in the cement. This enhances the adsorption capacity of the water reducer to cement particles, reduces the adsorption of clay on the water reducer, increases its adaptability to sand and gravel aggregates, and improves the slump retention effect. The ring structure of sorbitol increases the rigidity of cement, thereby increasing its mechanical strength. It also reduces the adsorption of soil on the water reducer and improves the water reducer's tolerance to soil in cement sand.

[0036] The long-chain structure of the polyether macromonomer in the polycarboxylate water-reducer prepared by the present invention can be stretched to produce significant steric hindrance. The large dispersant structure of the small monomer also creates significant steric hindrance. When polymerized with an unsaturated acid, the resulting water-reducer exhibits even greater steric hindrance. The polycarboxylate water-reducer with high steric hindrance can disrupt the flocculated structure between cement particles, effectively hindering their aggregation and dispersing them, improving the mixing properties of concrete, releasing water, and increasing concrete fluidity. Furthermore, the high steric hindrance of the water-reducer can slow the hydration reaction and prolong the setting time of the cement.

[0037] The preparation method of the present invention is simple and efficient, and the preparation is completed in one pot by gradually adding reactants. The reaction time can be controlled within 2 hours, and the reaction efficiency is high.

[0038] Terminology

[0039] Certain embodiments of the present invention are now described in detail, examples of which are illustrated by the accompanying structural formulas and chemical formulae. The present invention is intended to encompass all substitutions, modifications, and equivalent technical solutions, which are all included within the scope of the invention as defined in the claims. Those skilled in the art will recognize that many methods and materials similar or equivalent to those described herein can be used to practice the present invention. The present invention is in no way limited to the methods and materials described herein. In the event that one or more of the combined documents, patents, and similar materials differ from or contradict the present application (including but not limited to defined terms, term applications, described technologies, etc.), the present application shall prevail.

[0040] It will be further appreciated that certain features of the invention, which, for clarity, are described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which, for brevity, are described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0041] Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. All patents and publications related to the present invention are incorporated herein by reference in their entirety.

[0042] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0043] In the following disclosure, all numerical values disclosed herein are approximate, regardless of whether the word "about" or "approximately" is used. The numerical value of each number may vary by 1%, 2%, 5%, 7%, 8%, 10%, 15%, or 20%. Whenever a number having a value of N is disclosed, any number having a value of N+ / -1%, N+ / -2%, N+ / -3%, N+ / -5%, N+ / -7%, N+ / -8%, N+ / -10%, N+ / -15%, or N+ / -20% is expressly disclosed, where "+ / -" means plus or minus. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the following examples. The specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention in any way. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion about the concepts of the present disclosure. Such structures and technologies are also described in many publications.

[0045] The reagents used in the present invention can be purchased from the market or prepared by the method described in the present invention.

[0046] Example 1

[0047] A method for preparing a polycarboxylate water-reducing agent with a high water-reducing rate comprises the following steps:

[0048] S1: 818 kg of water, 700 kg of diethylene glycol monovinyl ether, and 7.7 kg of hypophosphorous acid were added to a reaction kettle and stirred to mix;

[0049] S2: After the S1 component is completely dissolved, add 4.3 kg of 27.5% hydrogen peroxide;

[0050] S3: Control the temperature in the reactor to about 25°C, and add mixed solution A: 1.15kg vitamin C + 0.56kg ferrous sulfate + 250kg water (prepared in advance and stirred evenly) dropwise, and add at a constant speed over 55 minutes;

[0051] S4: Simultaneously with step S3, mixed solution B (60 kg acrylic acid, 27 kg isosorbide acrylate, and 140 kg water) was added dropwise over a constant speed over 50 minutes.

[0052] S5: Control the temperature below 45 degrees and keep it warm for 1 hour; after the sample is tested and qualified, discharge the material.

[0053] Preparation process of reducing agent solution: dissolve vitamin C and ferrous sulfate in water and stir evenly.

[0054] The mixed solution preparation process is as follows: acrylic acid and isosorbide acrylate are dissolved in water and mixed evenly.

[0055] Example 2

[0056] A method for preparing a polycarboxylate water-reducing agent with a high water-reducing rate comprises the following steps:

[0057] S1: 4080 kg of water, 3500 kg of diethylene glycol monovinyl ether and 38.4 kg of hypophosphorous acid were respectively added into a reaction kettle and stirred to mix;

[0058] S2: After the S1 component is completely dissolved, add 21.3 kg of 27.5% hydrogen peroxide;

[0059] S3: Control the temperature in the reactor to about 15°C, and add mixed solution A: 5.75kg vitamin C + 2.8kg ferrous sulfate + 750kg water (prepared in advance and stirred evenly) dropwise, and add at a constant speed over 55 minutes;

[0060] S4: Simultaneously with step S3, a mixture of 297 kg acrylic acid, 135 kg isosorbide di(meth)acrylate, and 200 kg water was added dropwise over a constant speed over 50 minutes.

[0061] S5: Control the temperature below 45 degrees and keep warm for 1 hour; add 1000kg of water, stir evenly, take samples and test them, then discharge the materials.

[0062] Preparation process of reducing agent solution: dissolve vitamin C and ferrous sulfate in water and stir evenly.

[0063] The mixed solution preparation process is as follows: acrylic acid and isosorbide di(meth)acrylate are dissolved in water and mixed evenly.

[0064] Example 3

[0065] A method for preparing a polycarboxylate water-reducing agent with a high water-reducing rate comprises the following steps:

[0066] S1: 380 kg of water, 351.7 kg of diethylene glycol monovinyl ether, and 3.85 kg of hypophosphorous acid were added to a reaction kettle and stirred to mix;

[0067] S2: After the S1 component is completely dissolved, add 2.2 kg of 27.5% hydrogen peroxide;

[0068] S3: Control the temperature in the reactor to about 25°C, and add mixed solution A: 0.55kg vitamin C + 0.26kg ferrous sulfate + 150kg water (prepared in advance and stirred evenly) dropwise, and add at a constant speed over 55 minutes;

[0069] S4: Simultaneously with step S3, add mixed solution B: a mixed solution of 25 kg acrylic acid + 6 kg isosorbide acrylate + 6.5 kg isosorbide di(meth)acrylate + 80 kg water, at a constant rate over 50 minutes;

[0070] S5: Control the temperature below 45 degrees and keep it warm for 1 hour; after the sample is tested and qualified, discharge the material.

[0071] Preparation process of reducing agent solution: dissolve vitamin C and ferrous sulfate in water and stir evenly.

[0072] The mixed solution preparation process is as follows: acrylic acid, isosorbide acrylate and isosorbide di(meth)acrylate are dissolved in water and mixed evenly.

[0073] Example 4

[0074] Referring to the components of Example 3, various parameters were adjusted to prepare a polycarboxylate water-reducing agent with a high water-reducing rate, as shown in Table 1 below:

[0075]

[0076] Comparative Example 1

[0077] The corresponding water reducing agent was prepared with reference to Example 4 of patent CN109593167A.

[0078] Effect Example 1

[0079] (1) According to the standard GB8077-2023 "Test method for homogeneity of concrete admixtures" chapter "15 Cement paste fluidity", the effects of the embodiments and comparative examples of the present invention on the fluidity of cement paste were measured. The number of tests for each measurement was set at three times, and the average value of the three test results was used to represent the measurement result. The test was carried out under standard test conditions, with a temperature of 20°C ± 2°C and a relative humidity of not less than 50%. The cement and water reducer were placed in the test environment 24 hours in advance to achieve temperature equilibrium. 300g of cement, 105g of water, and a water reducer dosage of 1.2% were used to examine the fluidity of the cement paste for 30s respectively. The experimental results are shown in Table 2. The control example is a cement paste without the addition of a water reducer.

[0080] Table 2 Cement paste data

[0081] sample water reducer 30s fluidity Control sample - 152mm Comparative sample Comparative Example 1 229mm Sample 1 Example 1 240mm Sample 2 Example 2 238mm Sample 3 Example 3 270mm Sample 5 Example 5 268mm Sample 6 Example 6 267mm Sample 7 Example 7 269mm

[0082] As can be seen from Examples 1-3 in Table 2, different small monomer dispersants have different effects. When acrylic acid and isosorbide di(meth)acrylate are added simultaneously as small monomer dispersants, the fluidity of the resulting cement paste is improved. It can be seen that compared with a single small monomer dispersant, the effect brought by two different small monomer dispersants is better.

[0083] It can be seen from Examples 5-7 that, while ensuring that the ratio of the two small monomer dispersants remains unchanged, the ratio of other components is changed, and the resulting water reducer has little effect on the fluidity of the cement paste.

[0084] As can be seen from the data in Table 2, the fluidity of the cement paste with the addition of a water reducer is significantly improved compared to the fluidity of the reference cement paste, indicating that the water reducer has a good effect on improving the fluidity of the cement paste. Compared with the comparative example samples, the samples prepared in each embodiment of the present invention have better fluidity.

[0085] (2) According to the standard GB8077-2023 "Test method for homogeneity of concrete admixtures" chapter "16 Mortar water reduction rate", the effects of the embodiments and comparative examples of the present invention on the cement water reduction rate were measured. The number of tests for each measurement was set at three times, and the average value of the three test results was used to represent the measurement result. The test was carried out under standard test conditions, with a temperature of 20°C ± 2°C and a relative humidity of not less than 50%. The cement and water reducer were placed in the test environment 24 hours in advance to achieve temperature equilibrium. 300g of cement and 1.2% of water reducer were used, and the water consumption when the fluidity of the cement paste was 180mm was examined in 30s. The experimental results are shown in Table 3. The control example is a cement paste without the addition of a water reducer.

[0086] Table 3 Cement paste data

[0087] sample water reducer Water consumption Control sample - 125g Comparative sample Comparative Example 1 85.3g Sample 1 Example 1 72.8g Sample 2 Example 2 72.7g Sample 3 Example 3 68.6g Sample 5 Example 5 69.3g Sample 6 Example 6 68.8g Sample 7 Example 7 69.2g

[0088] As can be seen from Examples 1-3 in Table 3, different small monomer dispersants provide different effects. When acrylic acid and isosorbide di(meth)acrylate are added simultaneously as small monomer dispersants, the water consumption is relatively reduced to ensure a uniform fluidity of 180 mm for the resulting cement paste. Furthermore, using two different small monomer dispersants provides superior results compared to using a single small monomer dispersant.

[0089] It can be seen from Examples 5-7 that, while ensuring that the ratio of the two small monomer dispersants remains unchanged, the ratio of other components is changed, and the resulting water reducer has little effect on the water consumption of cement.

[0090] As can be seen from the data in Table 3, the water consumption of cement with the addition of water reducer is significantly increased compared to the water consumption of the base cement, indicating that the water reducer has a good effect on improving the water consumption of cement. Compared with the comparative example samples, the samples prepared in each embodiment of the present invention have better water reducing properties.

[0091] As can be seen from Tables 2 and 3, the addition of the water-reducing agent of the present invention effectively disperses cement particles and reduces friction between them. The better the fluidity of the cement paste, the easier it is to evenly distribute the cement paste during mixing and pouring, and the better the workability. By adding a water-reducing agent, the fluidity of the cement paste is improved, effectively reducing water consumption while maintaining the same fluidity, helping to improve the strength and durability of concrete, while also avoiding shrinkage and cracking caused by excessive water reduction and extending the hydration time of the cement.

[0092] Effect Example 2

[0093] According to the standards GB / T 50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", GB / T 50081-2002 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" and GB8076-2008 "Concrete Admixtures", the effects of the embodiments and comparative examples of the present invention on the properties of concrete were measured. The number of tests for each measurement was set at two, and the average of the two test results was used to express the measurement result. Standard cement was used, and the concrete mix ratio was 360 kg / m 3 , sand 790kg / m 3 、Stone 1140kg / m 3 , the amount of water reducing agent added is 0.55%, and the experimental results are shown in Table 4. The control example is concrete without adding water reducing agent.

[0094] Table 4 Performance comparison test table

[0095]

[0096] The data in Table 4 demonstrate that, even with the same water content, the concrete prepared in the Examples of the present invention exhibit different properties. Examples 4-5 and 8-9 demonstrate that increasing the amount of isosorbide acrylate increases the compressive strength of the resulting water reducer. However, when isosorbide acrylate alone is used, its compressive strength does not exhibit a significant advantage over the combination of two different small monomer dispersants, demonstrating a synergistic effect between the two.

[0097] As can be seen from the data in Table 4, the performance of the concrete prepared by the embodiment of the present invention is better when the amount of water is reduced. In terms of performance, compared with the comparative concrete, after the water reducer prepared by the present invention is added to the concrete, the slump effect of the concrete sample is better, which can ensure the uniform distribution of the concrete, reduce the difficulty of construction, and avoid voids and looseness, reduce the vibration time, and improve production efficiency; compared with the comparative concrete, the expansion of concrete 1 and concrete 2 is improved, and there is no bleeding or segregation, which can ensure the quality of the concrete and subsequent construction efficiency. Compared with the comparative concrete, the compressive strength of the concrete sample added to the embodiment of the present invention is significantly improved, indicating that the addition of the water reducer of the present invention has a certain degree of mechanical strengthening effect on the concrete. It can be seen that the water reducer prepared by the present invention can effectively improve the initial dispersibility and slump retention performance of concrete, and can improve the strength of concrete when the amount of water is reduced, and has good long-term slump retention effect and anti-mud effect.

[0098] The methods of the present invention have been described through preferred embodiments. It is apparent that those skilled in the art will be able to modify or appropriately alter and combine the methods and applications described herein within the scope, spirit, and spirit of the present invention to implement and apply the technology of the present invention. Those skilled in the art may refer to the disclosure herein and appropriately modify the process parameters to achieve the desired effect. It is particularly important to note that all similar substitutions and modifications apparent to those skilled in the art are considered encompassed by the present invention.

Claims

1. A polycarboxylate water-reducing agent with a high water-reducing rate, characterized in that: Including polyether macromonomer, sodium hypophosphite, oxidant, reducing agent, unsaturated acid and small monomer dispersant; The small monomer dispersant is selected from at least one of isosorbide acrylate and isosorbide di(meth)acrylate.

2. The polycarboxylate water-reducing agent according to claim 1, characterized in that: The polyether macromonomer comprises at least one of methyl allyl alcohol polyoxyethylene ether, isopentanol polyoxyethylene ether, vinyl glycol polyoxyethylene ether, vinyl butanediol polyoxyethylene ether, and diethylene glycol monovinyl ether; The oxidant is selected from at least one of hydrogen peroxide, ammonium persulfate, and potassium persulfate; The reducing agent is selected from at least one of vitamin C, ferrous sulfate, sodium thiosulfate, ferrous oxide, and ferrosoferric oxide; The unsaturated acid is selected from at least one of acrylic acid, methacrylic acid, maleic anhydride and itaconic acid.

3. The polycarboxylate water-reducing agent according to claim 1, characterized in that: The polycarboxylate water-reducing agent comprises, by weight, 80-90 parts of a polyether macromonomer, 0.5-1.5 parts of sodium hypophosphite, 0.1-1 part of an oxidant, 0.1-1 part of a reducing agent, 5-15 parts of an unsaturated acid, and 1-7 parts of a small monomer dispersant.

4. The polycarboxylate water-reducing agent according to claim 1, characterized in that: The small monomer dispersant is isosorbide acrylate and isosorbide di(meth)acrylate.

5. A method for preparing the polycarboxylate water-reducing agent with high water-reducing rate according to any one of claims 1 to 4, characterized in that: The steps include: S1: feeding measured water, polyether macromonomer and hypophosphorous acid into a reactor for mixing; S2: After the components in the reactor are completely dissolved, add the oxidant; S3: Control the temperature in the reactor and add the reducing agent solution dropwise; S4: Add the mixed solution of unsaturated acid and small monomer dispersant dropwise at the same time as S3, keep warm after adding, take samples and discharge the materials after they are qualified.

6. The preparation method according to claim 5, characterized in that In S1, the mass fraction of the polyether macromonomer is 40-50%; The mass fraction of the hypophosphorous acid is 0.1-1%.

7. The preparation method according to claim 5, characterized in that The mass concentration of the oxidant is 25-30%.

8. The preparation method according to claim 5, characterized in that In S3, the reaction temperature is 10-25°C; The mass fraction of vitamin C in the reducing agent solution is 0.1-1%; The mass fraction of ferrous sulfate in the reducing agent solution is 0.1-1%; The reducing agent solution preparation process is as follows: dissolve vitamin C and ferrous sulfate in water and stir evenly; In S3, the dropping rate is controlled and the dropping time is 45 to 60 minutes.

9. The preparation method according to claim 5, characterized in that The mass fraction of the unsaturated acid in the mixed solution is 20-30%; In S4, the dropping rate is controlled and the dropping time is 45 to 55 minutes; the temperature is controlled at 40 to 50° C. and kept warm for 0.5 to 2 hours.

10. The preparation method according to claim 5, characterized in that The mixed solution is prepared by dissolving the unsaturated acid and the small monomer dispersant in water and mixing them uniformly; The mass fraction of the small monomer dispersant in the mixed solution is 10-20%.

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