Preparation method of polycarboxylic acid mother liquor and polycarboxylic acid mother liquor

Abstract

The invention provides a preparation method of polycarboxylic acid mother liquor and the polycarboxylic acid mother liquor, and particularly relates to the technical field of concrete admixtures. The preparation method comprises the following steps: mixing deionized water, a polyether macromonomer, part of acrylic acid and sodium hypophosphite to prepare a base material; wherein the polyether macromonomer is VE600, the molecular formula of the polyether macromonomer is CH2 = CH-O-[CH2-CH2-O] n + 2-[CH2-CH (CH3)-O] mH, in the formula, m is 1-5, and n is 120-125; the preparation method comprises the following steps: mixing deionized water, part of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid to prepare a first solution; mixing deionized water, a reducing agent, a pH regulator and a sulfydryl chain transfer agent to prepare a second solution; adding a ferrous sulfate solution, an oxidizing agent and a photoinitiator into the base material, starting ultraviolet irradiation, then adding the first solution and the second solution into the base material, and performing heat preservation and aging to obtain the polycarboxylic acid mother liquor. The polycarboxylic acid mother liquor prepared by the method is free of bleeding, relatively good in workability and outstanding in long-term slump retaining performance, and is particularly suitable for concrete with slightly high sand content.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete admixtures, and particularly relates to a preparation method of a polycarboxylate mother liquor and the polycarboxylate mother liquor. Background Art

[0002] The polycarboxylate mother liquor is a high-performance concrete admixture, mainly used to improve the workability and mechanical properties of concrete. At present, the polycarboxylate mother liquors on the market mainly include water-reducing mother liquors and sustained-release mother liquors, with single functions. In practical applications, it is usually necessary to compound two mother liquors to solve the workability problems such as the initial fluidity of concrete, slump loss, etc. However, such compounding schemes have a relatively high dosage of the mother liquor, and have poor adaptability to concrete systems with a relatively high mud content, and it is difficult to solve the workability problems of concrete with a high mud content. Therefore, developing a comprehensive mother liquor is an urgent need in the market, which can more efficiently solve the workability problems of concrete, especially under the condition of a high mud content.

[0003] In the prior art, polycarboxylate mother liquors are mostly prepared by free radical polymerization of methyl allyl polyoxyethylene ether (HPEG2400) monomer and acrylic acid. Among them, the hydrogen peroxide - ascorbic acid (VC) redox system is a commonly used technical means to initiate such reactions. However, the initiation activity of this system is relatively low. Under the process conditions of a relatively low acid-ether ratio (i.e., a relatively small molar ratio of acrylic acid to the macromonomer), the conversion efficiency of the macromonomer is relatively low. The residue of the unreacted monomer not only reduces the utilization rate of raw materials, but also affects the molecular structure regularity of the product, thereby weakening its dispersion performance and compatibility with the concrete system. Summary of the Invention

[0004] In view of the above problems existing in the prior art, the present invention provides a preparation method of a polycarboxylate mother liquor and the polycarboxylate mother liquor to improve the single function of the polycarboxylate mother liquor prepared by the prior art and the inability to solve the workability problems of concrete with a high mud content.

[0005] To achieve the above object and other related objects, the first aspect of the present invention provides a preparation method of a polycarboxylate mother liquor, and the preparation method at least includes the following steps:

[0006] Prepare the base material: Mix deionized water, polyether macromonomer, part of acrylic acid and sodium hypophosphite to prepare the base material, wherein the polyether macromonomer is VE600, and the molecular formula is CH 2 =CH-O-[CH 2 -CH 2 -O] n+2 -[CH 2 -CH(CH 3 )-O] m H, where m is 1 to 5 and n is 120 to 125;

[0007] Prepare the first solution: Mix deionized water, partial acrylic acid, and 2-acrylamido-2-methylpropanesulfonic acid to obtain the first solution;

[0008] Prepare the second solution: Mix deionized water, a reducing agent, a pH regulator, and a mercapto chain transfer agent to obtain the second solution;

[0009] Mixing reaction: Add ferrous sulfate solution, an oxidizing agent, and a photoinitiator to the base material. After turning on the ultraviolet light irradiation, then add the first solution and the second solution to the base material. After heat preservation and aging, a polycarboxylic acid mother liquor is obtained.

[0010] In an embodiment of the present invention, in the raw materials for preparing the polycarboxylic acid mother liquor, the molar ratio of the polyether macromonomer, the acrylic acid, and the 2-acrylamido-2-methylpropanesulfonic acid is 1:(3.0 - 5.0):(0.05 - 0.10).

[0011] In an embodiment of the present invention, in the mixing reaction step, the temperature before adding the first solution and the second solution to the base material is controlled at 10°C - 15°C, and the temperature during the reaction is controlled at 10°C - 28°C.

[0012] In an embodiment of the present invention, in the mixing reaction step, the first solution and the second solution are added to the base material in a uniform dropping manner, and the dropping time of the second solution is controlled to be 60 - 90 min, and the dropping time of the first solution is controlled to be 50 - 60 min.

[0013] In an embodiment of the present invention, the heat preservation and aging time is 30 - 60 min, and the ultraviolet light irradiation runs through the whole reaction; the solid content of the polycarboxylic acid mother liquor is 40 - 45%.

[0014] In an embodiment of the present invention, in the step of preparing the base material, the mass of the sodium hypophosphite accounts for 0.2% - 1.0% of the mass of the polyether macromonomer; in the mixing reaction step, the concentration of the ferrous sulfate aqueous solution is 0.1%, and the dosage of the ferrous sulfate aqueous solution accounts for 0.5% - 1.5% of the mass of the polyether macromonomer; the dosage of the oxidizing agent accounts for 0.5% - 1.0% of the mass of the polyether macromonomer; the dosage of the photoinitiator accounts for 0.2% - 0.6% of the mass of the polyether macromonomer.

[0015] In an embodiment of the present invention, in the step of preparing the second solution, the dosage of the mercapto chain transfer agent accounts for 0.1% - 0.7% of the total mass of the polyether macromonomer, acrylic acid, and 2-acrylamido-2-methylpropanesulfonic acid; the dosage of the reducing agent accounts for 0.1% - 0.4% of the total mass of the polyether macromonomer, acrylic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

[0016] In an embodiment of the present invention, in the step of preparing the base material, the addition amount of acrylic acid accounts for 10% - 30% of the total mass of acrylic acid in the raw materials.

[0017] In an embodiment of the present invention, the reducing agent is selected from one or both of Rongalite and E51; the mercapto group-containing chain transfer agent is selected from one or both of mercaptopropionic acid and mercaptoethanol; the oxidizing agent is selected from one or both of aqueous hydrogen peroxide solution and sodium persulfate; the photoinitiator is selected from Irgacure 651; the pH regulator is selected from aqueous sodium hydroxide solution.

[0018] The present invention also provides a polycarboxylic acid mother liquor, which is prepared by the above-mentioned preparation method.

[0019] The present invention uses the unsaturated monomer VE600 as the polyether macromonomer, and makes it carry out a polymerization reaction with acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid under a dual initiation system of photoinitiation and redox initiation to obtain the polycarboxylic acid mother liquor. The mother liquor prepared with the unsaturated monomer VE600 has better effects than the mother liquor prepared with the commonly used HPEG2400 in terms of the bleeding state of concrete and the slump loss over time of concrete (especially on aggregates with a relatively high mud content). In addition, the present invention adopts a dual initiation system of photoinitiation and redox initiation to ensure better free radical polymerization effect, improve the conversion rate of the macromonomer VE600 under low acid-ether ratio conditions, and at the same time meet normal temperature polymerization and ensure the feasibility of low temperature production. AMPS is introduced into the side chain to improve the workability and fluidity of concrete in the alkaline environment of concrete.

[0020] The polycarboxylic acid mother liquor prepared by the preparation method of the present invention has the advantages of no bleeding in the initial stage, good workability, and outstanding slump retention performance over time, especially for concrete with a slightly higher mud content in aggregates. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other embodiments can be obtained based on these drawings without creative efforts.

[0022] Figure 1 It is a flowchart of an embodiment of the preparation method of the polycarboxylic acid mother liquor of the present invention. Detailed Embodiments

[0023] The following describes the implementation modes of the present invention through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are for the purpose of describing specific specific implementation modes, rather than limiting the protection scope of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention.

[0025] In this article, when it comes to a numerical range, unless otherwise specified, the distribution of the optional numerical values within this numerical range is considered continuous, and includes the two numerical endpoints of this numerical range (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. When providing multiple numerical ranges to describe features or characteristics, these numerical ranges can be combined.

[0026] In this article, when it comes to "multiple", "a variety of", "multiple times", etc., unless otherwise specifically defined, it means greater than 2 or equal to 2 in quantity. For example, "one or more" means one or greater than or equal to two.

[0027] In this article, "further", "even further", "especially", etc. are used for descriptive purposes, indicating differences in content, but should not be construed as limiting the protection scope of the present invention.

[0028] The present invention provides a preparation method of a polycarboxylic acid mother liquor and a polycarboxylic acid mother liquor prepared by using this preparation method. Using unsaturated monomer VE600 as a polyether macromonomer, under a dual initiation system of photoinitiation and redox initiation, it undergoes a polymerization reaction with acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid to obtain a polycarboxylic acid mother liquor. The dual initiation system makes the free radical polymerization effect better, improves the conversion rate of macromonomer VE600 under the condition of a low acid-ether ratio, and at the same time satisfies room temperature polymerization and ensures the feasibility of low-temperature production. The prepared polycarboxylic acid mother liquor can maintain the slump and spread of concrete, reduce bleeding and slump loss, and has good workability.

[0029] Please refer to Figure 1 , the preparation method of the polycarboxylic acid mother liquor of the present invention includes at least the following steps:

[0030] S1. Mix deionized water, polyether macromonomer, partial acrylic acid and sodium hypophosphite to prepare a base material;

[0031] S2. Mix deionized water, partial acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid to prepare a first solution;

[0032] S3. Mix deionized water, reducing agent, pH regulator, mercapto chain transfer agent to prepare a second solution;

[0033] S4. Add ferrous sulfate solution, oxidizing agent and photoinitiator to the base material. After turning on ultraviolet light irradiation, add the first solution and the second solution to the base material. After heat preservation and aging, prepare a polycarboxylic acid mother liquor.

[0034] The polyether macromonomer in step S1 of the present invention uses the unsaturated monomer VE600 produced by Jiangsu Sierbang Petrochemical Co., Ltd., which is a product obtained by reacting vinyl diglycol ether as an initiator with propylene oxide and ethylene oxide in a certain molar ratio, and the molecular weight is about 5500.

[0035] The molecular formula of polyether macromonomer VE600 is CH 2 =CH-O-[CH 2 -CH 2 -O] n+2 -[CH 2 -CH(CH 3 )-O] m H, where m is 1 to 5. Exemplarily, m can be 1, 3 or 5, etc., and n is 120 to 125. Exemplarily, n can be 120, 122, 124 or 125, etc. This molecular structure contains vinyl (CH 2 =CH-), polyoxyethylene (-CH 2 -CH 2 -O-) and polyoxypropylene (-CH 2 -CH(CH 3 )-O-) segments. Among them, vinyl is the active group in the polymerization reaction, which can undergo free radical copolymerization reactions with monomers such as acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) to form the polycarboxylic acid main chain. The polyoxyethylene segment has hydrophilicity and flexibility, can provide steric hindrance effect, prevent particle agglomeration, and significantly improve the fluidity and water reduction rate of concrete. The polyoxypropylene segment has certain hydrophobicity, can reduce the ineffective adsorption of the polymer on the surface of clay particles, and improve its applicability in concrete with a high mud content. The introduction of the polyoxypropylene segment can adjust the adsorption performance of the polymer and make it more adaptable to different cement systems.

[0036] The long side-chain structure of the polyether macromonomer can delay the cement hydration reaction, reduce the slump loss of concrete, and extend the construction time. The synergistic effect of the polyoxyethylene and polyoxypropylene segments in polyether VE600 can optimize the adsorption-desorption equilibrium of the polymer and further improve the slump retention performance. By adjusting the lengths and ratios of the polyoxyethylene (n) and polyoxypropylene (m) segments, the molecular structure of the polycarboxylate superplasticizer can be precisely regulated, thereby optimizing its performance. For example, increasing the length of the polyoxyethylene segment can improve hydrophilicity and dispersibility, while increasing the length of the polyoxypropylene segment can enhance hydrophobicity and anti-clay properties.

[0037] In the polymerization reaction of polyether VE600, acrylic acid (AA), and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) of the present invention, the molar ratio of polyether VE600, acrylic acid, and AMPS is 1:(3.0 - 5.0):(0.05 - 0.10). Exemplarily, the molar ratio of polyether VE600, acrylic acid, and AMPS can be 1:3.0:0.05, 1:4.0:0.08, or 1:5.0:0.10, etc. Therefore, before performing step S1, the reactants polyether VE600, acrylic acid, and AMPS need to be weighed according to the set molar ratio. When weighing, first convert the molar amount into mass, and the conversion relationship is n = m / M, where n represents the amount of substance, with the unit of mol, M represents the molar mass of the substance, with the unit of g / mol, and m represents the mass of the substance, with the unit of g. The molar mass of polyether VE600 varies according to the values of m and n in its molecular formula. For example, when m = 3 and n = 123 in the molecular formula, the molar mass of VE600 is 5725.82 g / mol; when m = 5 and n = 120, the molar mass of VE600 is 5709.84 g / mol; when m = 1 and n = 125, the molar mass of VE600 is 5697.76 g / mol, etc.; the molar mass of acrylic acid is 72 g / mol, and the molar mass of AMPS is 207 g / mol.

[0038] The process of preparing the base material in step S1 is the dissolution of polyether VE600 to form a solution containing polyether VE600. Deionized water is used as the solvent in the base material to dissolve polyether VE600, a part of acrylic acid, and sodium hypophosphite. In this step, the amount of deionized water used is not limited, as long as it can ensure the full dissolution of polyether VE600, a part of acrylic acid, and sodium hypophosphite. Adding a part of acrylic acid during the dissolution of polyether VE600 can accelerate the dissolution rate of polyether VE600 and improve the application effect of the product, while adding sodium hypophosphite can reduce the initial self-polymerization rate of acrylic acid.

[0039] Exemplarily, the specific process of step S1 is as follows: First, add a certain amount of deionized water to the reaction kettle and start stirring. Then, put the weighed polyether VE600, a part of acrylic acid, and sodium hypophosphite into the reaction kettle and mix and stir until the solids are completely dissolved to form a base material. In this step, the addition amount of acrylic acid accounts for 10% - 30% of the total mass of the weighed acrylic acid. For example, it can be 10%, 20%, or 30%, etc. The addition amount of sodium hypophosphite accounts for 0.2% - 1.0% of the mass of polyether VE600. For example, it can be 0.2%, 0.5%, 0.8%, or 1.0%, etc.

[0040] Step S2 is to dissolve the remaining part of acrylic acid and the weighed AMPS to form a first solution. In this step, deionized water is used as a solvent to dissolve acrylic acid and AMPS, and the addition amount of deionized water needs to be sufficient to fully dissolve acrylic acid and AMPS. An example of the specific process of step S2 is as follows: First, add deionized water to a reaction vessel, and add the remaining part of acrylic acid and the weighed AMPS and mix and stir fully until the solids are completely dissolved.

[0041] Step S3 is to prepare a second solution. In this step, deionized water is used as a solvent to dissolve the reducing agent, pH regulator, and mercapto chain transfer agent, and the addition amount of deionized water needs to be sufficient to fully dissolve the reducing agent, pH regulator, and mercapto chain transfer agent. The mercapto chain transfer agent can adjust the molecular weight of the polymer, and the pH regulator can adjust the pH value of the second solution to keep the second solution alkaline, thereby ensuring the stability of the reducing agent. An example of the specific process of step S3 is as follows: First, add deionized water to another reaction vessel, and then add the reducing agent, pH regulator, and mercapto chain transfer agent and mix and stir fully until the solids are completely dissolved to form a second solution.

[0042] In some embodiments, the reducing agent is selected from one or two of Rongalite and E51. Further, the reducing agent can be Rongalite, or E51, or a composition in which Rongalite and E51 are mixed in any proportion, but not limited thereto. The dosage of the reducing agent in step S2 accounts for 0.1% - 0.4% of the total mass of the monomers (polyether VE600, acrylic acid, and AMPS). Exemplarily, the dosage of the reducing agent accounts for 0.1%, 0.2%, 0.3%, or 0.4% of the total mass of the monomers, etc.

[0043] In some embodiments, the mercapto chain transfer agent is selected from one or two of mercaptopropionic acid and mercaptoethanol. Further, the mercapto chain transfer agent can be mercaptopropionic acid, or mercaptoethanol, or a composition in which mercaptopropionic acid and mercaptoethanol are mixed in any proportion, but not limited thereto. The dosage of the mercapto chain transfer agent in step S2 accounts for 0.1% - 0.7% of the total mass of the monomers (polyether VE600, acrylic acid, and AMPS). For example, it can be 0.1%, 0.3%, 0.5%, or 0.7, etc.

[0044] In some embodiments, the pH regulator is selected from basic compounds. Further, the pH regulator is selected from sodium hydroxide. More specifically, the pH regulator is a sodium hydroxide solution with a mass concentration of 30%, and the dosage of the 30% sodium hydroxide solution is the same as that of the mercapto chain transfer agent.

[0045] It should be noted that the order of steps S2 and S3 is not sequential. S2 can be executed first, or S3 can be executed first, or they can be carried out simultaneously.

[0046] In step S4, the base material, the first solution, and the second solution are mixed to cause a polymerization reaction. The specific process is as follows:

[0047] First, add a ferrous sulfate solution, an oxidizing agent, and a photoinitiator to the base material, and then turn on the ultraviolet light irradiation and stir for 5 minutes. In this step, the ferrous sulfate solution is a ferrous sulfate solution with a mass concentration of 0.1%, and the addition amount accounts for 0.5% - 1.5% of the mass of the polyether macromonomer (VE600), such as 0.5%, 1.0%, or 1.5%, etc.; the oxidizing agent is selected from one or two of an aqueous hydrogen peroxide solution (mass concentration of 0.1%) and sodium persulfate. For example, the oxidizing agent is an aqueous hydrogen peroxide solution, or sodium persulfate, or a composition in which an aqueous hydrogen sulfide solution and sodium persulfate are mixed in any ratio. Further, the addition amount of the oxidizing agent accounts for 0.5% - 1.0% of the mass of the polyether macromonomer VE600. For example, it is 0.5%, 0.8%, or 1.0%, etc. The photoinitiator is selected from Irgacure 651. Further, the addition amount of the photoinitiator accounts for 0.2% - 0.6% of the mass of the polyether macromonomer VE600, such as 0.2%, 0.4%, or 0.6%, etc. The wavelength of the ultraviolet light can be any wavelength within 300 - 420 nm, such as 300 nm, 350 nm, 400 nm, or 420 nm, etc.

[0048] Next, add the first solution and the second solution to the base material, and keep it warm and aged to obtain the polycarboxylic acid mother liquor. At the same time, the ultraviolet light remains on, that is, the ultraviolet light irradiation runs through the whole reaction to ensure the photoinitiation and redox dual initiation system of the polymerization reaction. Further, the first solution and the second solution are added in a uniform dropping manner, and the dropping time of the second solution is longer than that of the first solution to ensure that the unreacted acrylic acid and the like continue to react after the first solution is dropped. Furthermore, the dropping time of the second solution is controlled to be 60-90 minutes, and the dropping time of the first solution is controlled to be 50-60 minutes. Exemplarily, the dropping time of the second solution is controlled at 60 minutes, and the dropping time of the first solution is controlled at 50 minutes; or, the dropping time of the second solution is controlled at 75 minutes, and the dropping time of the first solution is controlled at 55 minutes; or, the dropping time of the second solution is controlled at 90 minutes, and the dropping time of the first solution is controlled at 60 minutes, and so on.

[0049] Further, in step S4, the temperature of the reaction system before dropping the first solution and the second solution is controlled within the range of 10-15 °C. Exemplarily, the temperature can be 10 °C, 12 °C or 15 °C, etc. During the dropping process, the reaction temperature is controlled at 10-28 °C. Exemplarily, the reaction temperature can be 10 °C, 15 °C, 20 °C, 25 °C or 28 °C, etc. After the dropping is completed, continue to keep it warm and aged for 30-60 minutes, such as 30 minutes, 40 minutes, 50 minutes or 60 minutes, etc.

[0050] After the heat preservation and aging are completed, the polycarboxylic acid mother liquor can be obtained. It should be noted that: the addition amount of deionized water during the reaction process needs to meet the solid content of the finally obtained polycarboxylic acid mother liquor to be 40%-45%. Exemplarily, 40%, 42% or 45%, etc. In practical applications, after the heat preservation and aging are completed, the polycarboxylic acid mother liquor can be diluted to the required solid content by adding water. Further, the solidification amount of the polycarboxylic acid mother liquor after dilution by adding water is usually 40%.

[0051] After the preparation of the present invention is completed, a comprehensive polycarboxylic acid mother liquor can be obtained, and its active ingredient is a polymer obtained by the polymerization reaction of polyether VE600, polypropylene and AMPS. The molecular weight of this polymer is 20,000-50,000.

[0052] Specifically, the molecular formula of the polymer is -[CH 2 -CH(COOH)] x --[CH 2 -CH(R 1 )] y --[CH 2 -CH(R 2 )] z-, where x, y, and z in the formula are the polymerization numbers of acrylic acid, VE600, and AMPS in the polymer molecule, respectively. The specific values can be determined according to the polymerization numbers of each raw material in the actual reaction process and are not limited herein; R in the formula 1 is O-[CH 2 -CH 2 -O] n+2 -[CH 2 -CH(CH 3 )-O] m -H, m is 1 to 5, and n is 120 to 125; R 2 is -CO-NH-C(CH 3 ) 2

[0053] -CH 2 -SO 3 H.

[0054] In the present invention, the unsaturated monomer VE600 produced by Jiangsu Sierbang Petrochemical Co., Ltd. is used as the polyether macromonomer, and it undergoes a polymerization reaction with acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid under a dual initiation system of photoinitiation and redox initiation to prepare a polycarboxylic acid mother liquor. The polyoxyethylene chain segment in the molecular structure of VE600 can provide a steric hindrance effect to prevent particle agglomeration, significantly improving the fluidity and water reduction rate of concrete. The polyoxypropylene chain segment can reduce the ineffective adsorption of the polymer on the surface of clay particles, improving its applicability in concrete with a high mud content (mud content greater than 5%). The synergistic effect of the polyoxyethylene and polyoxypropylene chain segments in VE600 can optimize the adsorption-desorption equilibrium of the polymer, further improving the slump retention performance. In addition, the dual initiation system of photoinitiation and redox initiation makes the free radical polymerization effect better, increasing the conversion rate of the macromonomer VE600 under low acid-ether ratio conditions, while meeting room temperature polymerization and ensuring the feasibility of low-temperature production.

[0055] The technical solution of the present invention will be described in detail below through several specific examples and comparative examples. Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the examples can be commercially purchased.

[0056] Example 1

[0057] This example provides a method for preparing a polycarboxylic acid mother liquor. The molecular formula of the polyether VE600 used in this method is as follows:

[0058] CH 2 =CH-O-[CH 2 -CH 2 -O] n+2 -[CH 2-CH(CH 3 )-O] m H, where m is 3 and n is 123.

[0059] The preparation process is as follows:

[0060] (1) Prepare the base material: Add 330 parts (parts by weight, the same below) of deionized water to a reaction kettle equipped with a thermometer, a stirrer, a double dropping pipe, and a reflux condenser. Start stirring, add 330 parts of polyether macromonomer VE600, add 5.18 parts of acrylic acid and 1.98 parts of sodium hypophosphite. Wait until the solid macromonomer is completely dissolved to obtain the base material.

[0061] (2) Prepare the first solution: Thoroughly mix 16 parts of deionized water, 12.10 parts of acrylic acid, and 0.62 parts of AMPS until the solids are completely dissolved to obtain the first solution;

[0062] (3) Prepare the second solution: Thoroughly mix 100 parts of deionized water, 2.44 parts of 30% aqueous sodium hydroxide solution, 2.44 parts of mercaptopropionic acid, and 0.87 parts of imported E51 until the solids are completely dissolved to obtain the second solution;

[0063] (4) Mixing reaction: After the solids in the kettle are completely dissolved, control the temperature in the kettle at 10 °C. Add 3.30 parts of aqueous ferrous sulfate solution (concentration 0.1%), 2.48 parts of aqueous hydrogen peroxide solution (content 30%), and 0.66 parts of Yanjia Gu 651 in sequence, and turn on the ultraviolet light irradiation at 300 - 420 nm. After stirring for 5 minutes, start to uniformly dropwise add the first solution and the second solution. Among them, the second solution is added dropwise for 90 minutes, and the first solution is added dropwise for 60 minutes. After dropping, keep warm and age for 60 minutes, and the solid content is 43.4%. Add 68.0 parts of deionized water and mix evenly. The sample number is VZH - 63, and the solid content is 40%. Temperature requirements during the reaction: Control the temperature at 10 - 15 °C when starting to add drops. If the temperature exceeds 25 °C during the dropping process, turn on the cooling water to cool down to ensure that the temperature is controlled below 28 °C.

[0064] Example 2

[0065] This example provides a method for preparing a polycarboxylic acid mother liquor. The molecular formula of the polyether VE600 used in this method is as follows:

[0066] CH 2 =CH - O - [CH 2 -CH 2 -O] n+2 -[CH 2 -CH(CH 3 )-O] m H, where m is 5 and n is 120.

[0067] The preparation process is as follows:

[0068] (1) Preparation of the base material: Add 330 parts of deionized water to a reaction kettle equipped with a thermometer, a stirrer, a double dropping pipe, and a reflux condenser. Start stirring, add 330 parts of polyether macromonomer VE600, add 3.46 parts of acrylic acid and 1.98 parts of sodium hypophosphite. Wait until the solid macromonomer is completely dissolved to obtain the base material.

[0069] (2) Preparation of the first solution: Thoroughly mix 16 parts of deionized water, 13.82 parts of acrylic acid, and 0.93 part of AMPS until the solids are completely dissolved to obtain the first solution.

[0070] (3) Preparation of the second solution: Thoroughly mix 100 parts of deionized water, 1.39 parts of 30% aqueous sodium hydroxide solution, 1.39 parts of mercaptoethanol, and 1.39 parts of imported E51 until the solids are completely dissolved to obtain the second solution.

[0071] (4) Mixing reaction: After the solids in the kettle are completely dissolved, control the temperature in the kettle at 15 °C. Sequentially add 4.95 parts of ferrous sulfate aqueous solution (concentration 0.1%), 1.28 parts of hydrogen peroxide aqueous solution (content 30%), 1.2 parts of sodium persulfate, 1.32 parts of Yanjia Gu 651, and turn on ultraviolet light irradiation at 300 - 420 nm. After stirring for 5 minutes, start to uniformly dropwise add the first solution and the second solution. Among them, the second solution is added dropwise for 60 minutes, and the first solution is added dropwise for 50 minutes. After dropping, keep warm and age for 45 minutes. The solid content is 43.5%. Add 70 parts of deionized water and mix evenly. The sample number is VZH - 66, and the solid content is 40%. Temperature requirements during the reaction: When starting to add dropwise, control the temperature at 10 - 15 °C. If the temperature exceeds 25 °C during the dropping process, turn on the cooling water to cool down to ensure that the temperature is controlled below 28 °C.

[0072] Example 3

[0073] This example provides a method for preparing a polycarboxylic acid mother liquor. The molecular formula of the polyether VE600 used in this method is as follows:

[0074] CH 2 =CH - O - [CH 2 - CH 2 - O] n+2 -[CH 2 - CH(CH 3 ) - O] m H, where m is 3 and n is 123.

[0075] The preparation process is as follows:

[0076] (1) Prepare the base material: Add 330 parts of deionized water to a reaction kettle equipped with a thermometer, a stirrer, a double dropping pipe, and a reflux condenser. Start stirring, add 330 parts of polyether macromonomer VE600, add 5.4 parts of acrylic acid and 0.66 part of sodium hypophosphite. After the solid macromonomer is completely dissolved, the base material is prepared.

[0077] (2) Prepare the first solution: Thoroughly mix 16 parts of deionized water, 16.20 parts of acrylic acid, and 0.93 part of AMPS until the solid is completely dissolved to prepare the first solution.

[0078] (3) Prepare the second solution: Thoroughly mix 100 parts of deionized water, 1.41 parts of 30% aqueous sodium hydroxide solution, 1.00 part of mercaptopropionic acid, 0.41 part of mercaptoethanol, and 0.35 part of Rongalite until the solid is completely dissolved to prepare the second solution.

[0079] (4) Mixing reaction: After the solids in the kettle are completely dissolved, control the temperature in the kettle at 12.5 °C. Add 1.65 parts of ferrous sulfate aqueous solution (concentration 0.1%), 1.65 parts of hydrogen peroxide aqueous solution (content 30%), and 1.32 parts of Yanjia Gu 651 in sequence, and turn on the ultraviolet light irradiation at 300 - 420 nm. After stirring for 5 minutes, start to uniformly drip the first solution and the second solution. Among them, the second solution is dripped for 75 minutes, and the first solution is dripped for 55 minutes. After dripping, keep warm and age for 60 minutes, and the solid content is 43.9%. Then add 79 parts of deionized water and mix evenly. The sample number is VZH - 69, and the solid content is 40%. Temperature requirements during the reaction: Control the temperature at 10 - 15 °C when starting to drip. If the temperature exceeds 25 °C during the dripping process, turn on the cooling water to cool down to ensure that the temperature is controlled below 28 °C.

[0080] Example 4

[0081] This example provides a method for preparing a polycarboxylic acid mother liquor. The molecular formula of the polyether VE600 used in this method is as follows:

[0082] CH 2 =CH - O - [CH 2 - CH 2 - O] n+2 -[CH 2 - CH(CH 3 ) - O] m H, where m is 1 and n is 125.

[0083] The preparation process is as follows:

[0084] (1) Prepare the base material: Add 330 parts of deionized water to a reaction kettle equipped with a thermometer, a stirrer, a double dropping pipe, and a reflux condenser. Start stirring, add 330 parts of polyether macromonomer VE600, add 1.30 parts of acrylic acid and 3.30 parts of sodium hypophosphite. Wait until the solid macromonomer is completely dissolved to obtain the base material.

[0085] (2) Prepare the first solution: Thoroughly mix 16 parts of deionized water, 11.66 parts of acrylic acid, and 1.24 parts of AMPS until the solids are completely dissolved to obtain the first solution;

[0086] (3) Prepare the second solution: Thoroughly mix 100 parts of deionized water, 0.34 part of 30% aqueous sodium hydroxide solution, 0.34 part of mercaptoethanol, 0.50 part of imported E51, and 0.88 part of Rongalite until the solids are completely dissolved to obtain the second solution;

[0087] (4) Mixing reaction: After the solids in the kettle are completely dissolved, control the temperature in the kettle at 12.5 °C. Sequentially add 4.95 parts of ferrous sulfate aqueous solution (concentration 0.1%), 3.30 parts of oxidant sodium persulfate, and 1.98 parts of Yanjia Gu 651, and turn on the ultraviolet light irradiation at 300 - 420 nm. After stirring for 5 minutes, start to uniformly dropwise add the first solution and the second solution. Among them, the second solution is dropped for 75 minutes, and the first solution is dropped for 50 minutes. After dropping, keep warm and age for 45 minutes, and then add 65 parts of deionized water and mix well. The sample number is VZH - 73, and the solid content is 40%. Temperature requirements during the reaction: Control the temperature at 10 - 15 °C when starting to drop. If the temperature exceeds 25 °C during the dropping process, turn on the cooling water to cool down to ensure that the temperature is controlled below 28 °C.

[0088] Comparative Example 1

[0089] (1) Prepare the base material: Sequentially add 280 parts of deionized water and 312 parts of polyether HPEG2400 (produced by Jiangsu Sierbang) under stirring in the reaction kettle, and heat up to 40 °C;

[0090] (2) Prepare the first solution: Thoroughly mix 39.4 parts of acrylic acid and 50 parts of deionized water until the solids are completely dissolved to obtain the first solution;

[0091] (3) Prepare the second solution: Thoroughly mix 1.8 parts of mercaptoacetic acid, 90 parts of deionized water, and 0.80 part of L - ascorbic acid (VC) until the solids are completely dissolved to obtain the second solution;

[0092] (4) Mixing reaction: When the temperature of the base material reaches 40°C, add 2.5 parts of 35% hydrogen peroxide, stir for 5 minutes, and start to uniformly dropwise add the second solution. After 2 minutes, uniformly dropwise add the first solution. Among them, the dropping time of the first solution is 120 minutes, and the dropping time of the second solution is 150 minutes. Heat is released during the dropping process, and the reaction temperature is controlled at 40 - 50°C;

[0093] (5) Heat preservation and dilution: After dropping, the heat preservation time is 1 hour; then, slowly add 10 parts of liquid alkali to neutralize and supplement 90 parts of deionized water for dilution; after stirring for 10 minutes, discharge the material to obtain a mother liquor with a solid content of 40%, denoted as PC-1.

[0094] Comparative Example 2

[0095] (1) Preparation of the base material: While stirring in the reaction kettle, sequentially add 280 parts of deionized water and 312 parts of polyether HPEG2400 (produced by Jiangsu Sierbang), and heat up to 40°C;

[0096] (2) Preparation of the first solution: Fully mix 33.7 parts of acrylic acid and 44 parts of deionized water to completely dissolve the solid, and prepare the first solution;

[0097] (3) Preparation of the second solution: Fully mix 1.6 parts of mercaptoacetic acid, 90 parts of deionized water, and 0.75 part of L-ascorbic acid (VC) to completely dissolve the solid, and prepare the second solution;

[0098] (4) Mixing reaction: When the temperature of the base material reaches 40°C, add 2 parts of 35% hydrogen peroxide, stir for 5 minutes, and start to uniformly dropwise add the second solution. After 2 minutes, uniformly dropwise add the first solution. Among them, the dropping time of the first solution is 120 minutes, and the dropping time of the second solution is 150 minutes. Heat is released during the dropping process, and the reaction temperature is controlled at 40 - 50°C;

[0099] (5) Heat preservation and dilution: After dropping, the heat preservation time is 1 hour; then, slowly add 10 parts of liquid alkali to neutralize and supplement 90 parts of deionized water for dilution; after stirring for 10 minutes, discharge the material to obtain a mother liquor with a solid content of 40%, denoted as PC-2.

[0100] Perform application performance tests on the samples VZH-63, VZH-66, VZH-69, and VZH-73 prepared in Examples 1 - 4 and the samples PC-1 and PC-2 prepared in Comparative Examples 1 - 2 under the same conditions. The test results are shown in Tables 1 to 4, and the test methods are as follows:

[0101] Testing of the fluidity of neat cement paste: Referring to GB / T 8077-2023 "Test Methods for the Homogeneity of Concrete Admixtures", the fluidity of the prepared polycarboxylic acid mother liquor was tested for its dispersion performance. Equipment and spare parts, such as a neat cement paste mixer and a truncated cone mold, were in accordance with the requirements of GB / T 8077-2023. The water consumption was 87 g, and the cement was 300 g (using 42.5# cement from Zhonglian in Banqiao, Lianyungang), sampled from a cement tanker. The temperature of tap water was 20 ± 1°C, the indoor ambient temperature was 20 ± 1°C, and the humidity was 55%. In the second group, 3 g of bentonite was used to replace 3 g of cement, with other conditions remaining unchanged. The flow diameter at the initial stage and over time (1 h, 2 h, and 3 h) was measured.

[0102] Testing of concrete properties: Referring to GB / T 8076-2023 "Concrete Admixtures" and GB / T 50080-2016 "Standard Test Method for Properties of Ordinary Concrete Mixtures", the concrete properties of the prepared polycarboxylic acid mother liquor were tested. The concrete mix ratio (materials sourced from Sujin Mixing Station in Lianyungang) was as follows: 42.5# cement from Zhonglian in Banqiao, Lianyungang: manufactured sand: crushed stone 2 - 25 mm: tap water = 360:880:970:170. The temperature of tap water was 20 ± 1°C, the indoor ambient temperature was 20 ± 1°C, and the humidity was 62%. The mud content in the manufactured sand in the first and second groups was 2% and 8.5% respectively. The fluidity at the initial stage and over time (1 h, 1.5 h, and 2 h) was measured.

[0103] Table 1: Comparison of the performance of the sample VZH-63 prepared in Example 1 with that of similar products prepared by conventional methods (at the same solid content after conversion)

[0104]

[0105] From the analysis of the neat cement paste data in Table 1, it can be concluded that compared with samples PC-1 (HPEG2400 type) and PC-2 (HPEG2400 type), the sample VZH-63 has a relatively smaller initial fluidity but a smaller loss over time, and the effect is more obvious when 3 g of bentonite is added. From the analysis of the concrete data in Table 1, it can be concluded that compared with samples PC-1 (HPEG2400 type) and PC-2 (HPEG 2400 type), the sample VZH-63 does not bleed water initially, has good workability, and has a slightly smaller loss over time, and the effect is more obvious when the mud content is 8.5%.

[0106] Table 2: Comparison of the performance of the sample VZH-66 prepared in Example 2 with that of similar products prepared by conventional methods (at the same solid content after conversion)

[0107]

[0108] From the analysis of the neat paste data in Table 2, it can be concluded that: Compared with samples PC-1 (HPEG2400 type) and PC-2 (HPEG 2400 type), sample VZH-66 has a relatively smaller initial fluidity but a smaller time-dependent loss value, and the effect is more obvious when 3 g of bentonite is added. From the analysis of the concrete data in Table 2, it can be concluded that sample VZH-63 has no initial bleeding, good workability, and a slightly smaller time-dependent loss compared with samples PC-1 (HPEG2400 type) and PC-2 (HPEG 2400 type), and the effect is more obvious when the mud content is 8.5%.

[0109] Table 3: Performance comparison of sample VZH-69 prepared in Example 3 with similar products prepared by conventional methods (at the same solid content)

[0110]

[0111]

[0112] From the analysis of the neat paste data in Table 3, it can be concluded that: Compared with samples PC-1 (HPEG2400 type) and PC-2 (HPEG2400 type), sample VZH-69 has a relatively smaller initial fluidity but a smaller time-dependent loss value, and the effect is more obvious when 3 g of bentonite is added. From the analysis of the concrete data in Table 3, it can be concluded that sample VZH-63 has no initial bleeding, good workability, and a slightly smaller time-dependent loss compared with samples PC-1 (HPEG2400 type) and PC-2 (HPEG 2400 type), and the effect is more obvious when the mud content is 8.5%.

[0113] Table 4: Performance comparison of sample VZH-73 prepared in Example 4 with similar products prepared by conventional methods (at the same solid content)

[0114]

[0115] From the analysis of the neat paste data in Table 4, it can be concluded that: Compared with samples PC-1 (HPEG2400 type) and PC-2 (HPEG 2400 type), sample VZH-63 has a relatively smaller initial fluidity but a smaller time-dependent loss value, and the effect is more obvious when 3 g of bentonite is added. From the analysis of the concrete data in Table 4, it can be concluded that sample VZH-63 has no initial bleeding, good workability, and a slightly smaller time-dependent loss compared with samples PC-1 (HPEG2400 type) and PC-2 (HPEG 2400 type), and the effect is more obvious when the mud content is 8.5%.

[0116] In summary, it can be concluded that in Examples 1 to 4, the unsaturated monomer VE600 was used as the polyether macromonomer, and it was polymerized with acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid under the dual initiation of photoinitiation and redox. The prepared polycarboxylic acid mother liquor can maintain the slump and spread of concrete, reduce bleeding and slump loss, and has good workability.

[0117] The preparation method of the polycarboxylic acid mother liquor provided by the present invention: The unsaturated monomer VE600 produced by Jiangsu Sierbang Petrochemical Co., Ltd. is used as the polyether macromonomer, and it is polymerized with acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid under a dual initiation system of photoinitiation and redox. The polyoxyethylene chain segment in the molecular structure of VE600 can provide a steric hindrance effect to prevent particle agglomeration and significantly improve the fluidity and water reduction rate of concrete. The polyoxypropylene chain segment can reduce the ineffective adsorption of the polymer on the surface of clay particles and improve its applicability in concrete with a high mud content. The synergistic effect of the polyoxyethylene and polyoxypropylene chain segments in VE600 can optimize the adsorption-desorption equilibrium of the polymer and further improve the slump retention performance. In addition, the dual initiation system of photoinitiation and redox makes the free radical polymerization effect better, improves the conversion rate of the macromonomer VE600 under the condition of a low acid-ether ratio, and at the same time meets the requirements of room temperature polymerization and ensures the feasibility of low-temperature production. Therefore, the present invention effectively overcomes some practical problems in the prior art and thus has high utilization value and practical significance.

[0118] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing a polycarboxylic acid mother solution, characterized in that: The following steps are involved: Preparation of primer: Deionized water, polyether macromonomer, part of acrylic acid and sodium hypophosphite are mixed to prepare primer, wherein the polyether macromonomer is VE600, and the molecular formula is CH2=CH-O-[CH2-CH2-O] n+2 -[CH2-CH(CH3)-O] m H, where m is 1 to 5 and n is 120 to 125; Preparing a first solution: mixing deionized water, a portion of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid to prepare a first solution; Preparing the second solution: mixing deionized water, a reducing agent, a pH regulator, and a thiol chain transfer agent to prepare a second solution; Mixing reaction: adding ferrous sulfate solution, oxidant and photoinitiator to the base material, turning on ultraviolet light irradiation, then adding the first solution and the second solution to the base material, and obtaining a polycarboxylic acid mother solution after heat preservation and aging.

2. The method for preparing a polycarboxylic acid mother solution according to claim 1, characterized in that: In the raw materials for preparing the polycarboxylic acid mother solution, the molar ratio of the polyether macromonomer, the acrylic acid, and the 2-acrylamide-2-methylpropanesulfonic acid is 1:(3.0-5.0):(0.05-0.10).

3. The method for preparing a polycarboxylic acid mother solution according to claim 1, characterized in that: In the mixing reaction step, the temperature before adding the first solution and the second solution to the base material is controlled at 10° C. to 15° C., and the temperature during the reaction is controlled at 10° C. to 28° C.

4. The method for preparing a polycarboxylic acid mother solution according to claim 1, characterized in that: In the mixing reaction step, the first solution and the second solution are added to the base material by uniform dripping, and the dripping time of the second solution is controlled to be 60 to 90 minutes, and the dripping time of the first solution is controlled to be 50 to 60 minutes.

5. The method for preparing a polycarboxylic acid mother solution according to claim 1, characterized in that: The heat preservation aging time is 30 to 60 minutes, and ultraviolet light irradiation runs through the entire reaction; the solid content of the polycarboxylic acid mother liquid is 40 to 45%.

6. The method for preparing a polycarboxylic acid mother solution according to claim 1, characterized in that: Include one or more of the following: In the step of preparing the base material, the mass of the sodium hypophosphite accounts for 0.2% to 1.0% of the mass of the polyether macromonomer; In the step of mixing reaction, the concentration of the ferrous sulfate aqueous solution is 0.1%, and the amount of the ferrous sulfate aqueous solution accounts for 0.5% to 1.5% of the mass of the polyether macromonomer; The amount of the oxidant is 0.5% to 1.0% of the mass of the polyether macromonomer; The amount of the photoinitiator used accounts for 0.2% to 0.6% of the mass of the polyether macromonomer.

7. The method for preparing a polycarboxylic acid mother solution according to claim 1, characterized in that: In the step of preparing the second solution, the amount of the thiol chain transfer agent is 0.1% to 0.7% of the total mass of the polyether macromonomer, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid; the amount of the reducing agent is 0.1% to 0.4% of the total mass of the polyether macromonomer, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid.

8. The method for preparing a polycarboxylic acid mother solution according to claim 1, characterized in that: In the step of preparing the base material, the amount of acrylic acid added accounts for 10% to 30% of the total mass of acrylic acid in the raw materials.

9. The method for preparing a polycarboxylic acid mother solution according to claim 1, characterized in that: Include one or more of the following: The reducing agent is selected from one or two of bleaching agent and E51; The mercapto chain transfer agent is selected from one or both of mercaptopropionic acid and mercaptoethanol; The oxidant is selected from one or both of aqueous hydrogen peroxide solution and sodium persulfate; The photoinitiator is selected from Yanjiagu 651; The pH regulator is selected from aqueous sodium hydroxide solution.

10. A polycarboxylic acid mother solution, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 9.

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