Anti-mud polycarboxylate water reducing agent and preparation method and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KZJ NEW MATERIALS GROUP CO LTD
- Filing Date
- 2024-10-17
- Publication Date
- 2026-06-23
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Figure SMS_2 
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of concrete admixtures, in particular to an anti-mud polycarboxylate superplasticizer and a preparation method and application thereof. BACKGROUND
[0002] In the field of concrete, water reducing agent is beneficial to reduce the water consumption of concrete, improve the working performance, improve the mechanical properties and improve the durability. In the development process of building materials, the admixtures with water reducing effect mainly include: lignin sulfonate, naphthalene sulfonate formaldehyde condensate, melamine formaldehyde condensate, acetone sulfonate formaldehyde condensate, amino sulfonate formaldehyde condensate, and the third generation of polycarboxylate superplasticizer (PCE).
[0003] Among them, polycarboxylate superplasticizer is a general term for a series of polymers with specific molecular structure and performance, which is a comb-shaped copolymer with a linear main chain connected to multiple side chains, which is generally formed by free radical reaction polymerization of monomers containing unsaturated double bonds and their derivatives. The main chain is connected to hydrophilic functional groups such as carboxyl, hydroxyl, sulfonic acid group, amino group, and grafts different polyoxyethylene (polyoxypropylene) with different polymerization degrees as side chains. Compared with other types of admixtures, polycarboxylate superplasticizer has the outstanding advantages of low dosage, good slump retention performance, low concrete shrinkage, high durability, strong adjustability on molecular structure, great potential for high performance, environmental protection in production process, etc. Therefore, its excellent performance has made it an indispensable element in pumping construction and is widely used in various engineering projects.
[0004] However, polycarboxylate superplasticizer faces a challenge: its polyoxyethylene (PEO) side chain is easily combined with aluminum silicate layers in clay, resulting in a decrease in effectiveness in clay-containing environments due to the strong adsorption of clay, which is manifested in high dosage requirements and poor aggregate adaptability.
[0005] To address the above problems, researchers in the industry have actively sought solutions.
[0006] CN105367720B discloses a water-reducing and slump-retaining polycarboxylate superplasticizer and a preparation method thereof, which introduces hydroxyethyl methacrylate and 2-methyl acryloyloxy ethyl phosphate to achieve water-reducing and slump-retaining effect. This scheme has good cement adaptability, but is difficult to apply to high-mud-content ground materials.
[0007] And CN109694213A patent further proposes an anti-mud polycarboxylate superplasticizer with a unique hollow cylindrical side chain structure, which effectively resists clay adsorption by using steric hindrance effect, significantly reducing the sensitivity of PCE to clay, but the slump retention performance is improved slightly. It is difficult to meet the needs of long-time transportation and pumping of concrete.
[0008] For example, authorized patent CN112759725B discloses a method for producing a novel anti-mud and slump-preserving nano-polycarboxylate superplasticizer. This method uses a sulfonate polymerizable emulsifier, a polyether polyol anti-mud crosslinking agent, and monomers for emulsion polymerization to obtain a novel anti-mud and slump-preserving nano-polycarboxylate superplasticizer with a crosslinked structure. It can achieve an anti-mud effect to a certain extent, but the emulsion polymerization method has high requirements for the production equipment and process control of the superplasticizer, making its application difficult.
[0009] The anti-mud polycarboxylate superplasticizer prepared by this invention has excellent anti-mud properties, good water reduction and slump retention effects, and lower requirements for water-reducing agent production equipment and process control, which is conducive to meeting the needs of actual industrial applications. Summary of the Invention
[0010] Therefore, it is necessary to provide an anti-mud polycarboxylate superplasticizer, its preparation method, and its application. This method can introduce an unsaturated cyclic pyrophosphate anti-mud functional monomer and synergize with some common unsaturated carboxylic acid esters. Using room temperature free radical solution copolymerization technology, without heating, an anti-mud polycarboxylate superplasticizer with excellent anti-mud performance, good dispersion and slump retention effect, and meeting the needs of actual industrial applications can be prepared.
[0011] To achieve the above objectives, the present invention provides a technical solution:
[0012] A mud-resistant polycarboxylate superplasticizer, wherein the raw materials for preparing the mud-resistant polycarboxylate superplasticizer, by weight, include:
[0013] 200-210 parts of unsaturated polyether macromonomer;
[0014] 10-20 parts of anti-mud functional monomer;
[0015] 8-16.5 parts of unsaturated carboxylic acids and / or unsaturated carboxylic acid esters;
[0016] Initiator 0.5-2.5 parts;
[0017] 0.1-0.5 parts reducing agent;
[0018] Chain transfer agent 0.6-1.6 parts; and
[0019] Neutralizing agent;
[0020] The structural formula of the anti-mud functional monomer is as follows:
[0021] ;
[0022] In the formula, R1 is -CH2- or -CH2-CH2-.
[0023] In some embodiments of the present invention, the raw materials for preparing the anti-mud functional monomer, by weight, include:
[0024] 100-120 parts of hydroxyl monoacrylate;
[0025] 52-60 parts of pyrophosphate;
[0026] 2-3 parts catalyst; and
[0027] Polymerization inhibitor 0.06~0.1 parts.
[0028] In some embodiments of the present invention, the hydroxy acrylate monoester includes at least one of hydroxyethyl acrylate and hydroxypropyl acrylate.
[0029] In some embodiments of the present invention, the catalyst comprises at least one of triethylenediamine and triethylamine.
[0030] In some embodiments of the present invention, the preparation steps of the anti-mud functional monomer are as follows:
[0031] The hydroxyl monoester of acrylate, the catalyst, and the organic solvent were stirred at 45℃-55℃ until completely dissolved to obtain the first mixture.
[0032] Add 1 to 1.5 times the amount of hydroxyl acrylate to the first mixture, and stir for 1.5 to 2.5 hours. Adjust the pH to 8-9 to obtain the second mixture. Specifically, the formaldehyde solution acts as a catalyst to undergo a substitution reaction with the hydroxyl acrylate.
[0033] Sodium chloride was added to the second mixture until the aqueous phase was saturated, and hydrochloric acid was added to adjust the pH to neutral. The mixture was then separated, and the organic phase was collected. Specifically, sodium chloride was used as the extract and hydrochloric acid was used as the pH adjuster.
[0034] Anhydrous sodium sulfate is added to the organic phase and stirred. The mixture is then filtered, and the solvent is removed from the filtrate. The filtrate is then subjected to vacuum distillation to obtain an intermediate. Specifically, the anhydrous sodium sulfate is used for drying.
[0035] Add a polymerization inhibitor to the intermediate, and add pyrophosphate dropwise while stirring at 65℃~80℃. After the addition is completed, keep warm to obtain the anti-mud functional monomer.
[0036] In some embodiments of the present invention, the time for adding pyrophosphate is 1h to 3h, and the time for keeping warm is 1h to 2h.
[0037] In some embodiments of the present invention, the polymerization inhibitor includes two or three of hydroquinone, p-benzoquinone, p-hydroxyanisole, and 2-tert-butylhydroquinone.
[0038] In some embodiments of the present invention, the organic solvent includes at least one of acetonitrile and tetrahydrofuran.
[0039] In some embodiments of the present invention, the unsaturated macromonomer includes at least one selected from methoxy polyethylene glycol methacrylate, methoxy polyethylene glycol acrylate, allyl polyethylene glycol, 3-methyl-3-butene-1-polyethylene glycol, 2-methylallyl polyethylene glycol, ethylene glycol monovinyl polyethylene glycol ether, and 4-hydroxybutylvinyl polyoxyethylene ether, with a molecular weight of 1500-3000.
[0040] Another aspect of the present invention provides a method for preparing an anti-mud-type polycarboxylate superplasticizer, comprising the steps of:
[0041] The polyether macromonomer, chain transfer agent and water are stirred and mixed to obtain the base aqueous solution;
[0042] The anti-mud functional monomer, unsaturated carboxylic acid and / or unsaturated carboxylic acid ester are mixed evenly with water to prepare solution A;
[0043] Mix the reducing agent and water thoroughly to prepare solution B.
[0044] Add an oxidant to the aqueous solution of the base material, stir evenly, and then add solution A and solution B dropwise over a period of 1 to 3 hours.
[0045] After the addition is complete, keep the mixture at 15-35℃ for 1-2 hours, then add a neutralizing agent to adjust the pH of the mixed solution to 5.5-7.0, thus obtaining the anti-mud polycarboxylate superplasticizer.
[0046] In some embodiments of the present invention, the unsaturated carboxylic acid and / or unsaturated carboxylic acid ester is at least one selected from acrylic acid, methacrylic acid, maleic anhydride, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.
[0047] The initiator is at least one of a 27.5% hydrogen peroxide solution, ammonium persulfate, or sodium persulfate.
[0048] In some embodiments of the present invention, the reducing agent is at least one of ascorbic acid, Bruggolite FF6, and Bruggolite E01.
[0049] In some embodiments of the present invention, the chain transfer agent is at least one of sodium hypophosphite, mercaptoacetic acid, and mercaptopropionic acid.
[0050] The beneficial effects of this invention are:
[0051] 1. The anti-mud polycarboxylate superplasticizer synthesized in this invention is produced by free radical solution copolymerization, incorporating unsaturated cyclic pyrophosphate esters as the main anti-mud functional monomers into the unsaturated polyether side chains. The pyrophosphate groups can form a pyrophosphate layer with clay minerals, inhibiting clay hydration and swelling, reducing excessive adsorption of the superplasticizer on the clay. Simultaneously, due to their higher electronegativity than carboxylate groups, the pyrophosphate groups exhibit stronger adsorption to the surface of cement particles, making the polycarboxylate superplasticizer more effective in dispersion and improving overall performance.
[0052] 2. The anti-mud polycarboxylate superplasticizer synthesized in this invention contains cyclic pyrophosphate structures in its side chains, which increases the physical size of the polycarboxylate superplasticizer side chains, resisting their insertion into the clay interlayer and enhancing their anti-mud properties. Furthermore, in the alkaline environment of cement hydration, the ester groups and pyrophosphate groups in the superplasticizer molecules hydrolyze to release carboxylate and phosphate ions, improving the slump retention and anti-mud properties of the polycarboxylate superplasticizer.
[0053] 3. The anti-mud polycarboxylate superplasticizer synthesized in this invention has excellent compatibility with polycarboxylate molecules, supports independent use or mixed application with conventional superplasticizers, and has significant market potential.
[0054] 4. The anti-mud polycarboxylate superplasticizer synthesized in this invention is prepared by free radical copolymerization at room temperature. The process is simple and mild, requires no complicated temperature control steps, has low energy consumption, and has high production and practical value. Detailed Implementation
[0055] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.
[0056] In the embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.
[0057] Example 1
[0058] This embodiment prepares a mud-resistant water-reducing agent, the specific process of which is as follows:
[0059] S1. Preparation of anti-mud functional monomers:
[0060] By weight, 102 parts of hydroxyl monoester of acrylate, 2.2 parts of triethylamine, and 100 mL of tetrahydrofuran were stirred at 55°C until completely dissolved to obtain the first mixture.
[0061] Add 146 parts of a 36% formaldehyde aqueous solution to the first mixture, stir for 2 hours, and adjust the pH to 8-9 to obtain the second mixture;
[0062] Add sodium chloride to the second mixture until the aqueous phase is saturated, add hydrochloric acid to adjust the pH to neutral, separate the liquids and keep the organic phase;
[0063] Anhydrous sodium sulfate was added to the organic phase and stirred. The mixture was filtered, and the solvent was removed from the filtrate. The filtrate was then subjected to vacuum distillation to obtain the intermediate.
[0064] Add 0.08 parts of hydroquinone to the intermediate, and add 56 parts of pyrophosphate dropwise at 70°C while stirring for 2 hours. After the addition is complete, keep warm for 1.5 hours to obtain the anti-mud functional monomer.
[0065] S2. Preparation of anti-mud polycarboxylate superplasticizer:
[0066] Aqueous solution A was prepared by mixing 18.4 parts by weight of anti-mud functional monomer, 14.6 parts by weight of acrylic acid and 28.2 parts by weight.
[0067] Prepare aqueous solution B by mixing 0.34 parts ascorbic acid and 32.8 parts water evenly;
[0068] Add 204 parts of polyether macromonomer, 1.2 parts of sodium hypophosphite and 152 parts of water to a three-necked flask, maintain 15-35℃, and stir to prepare a base material aqueous solution;
[0069] S3. Add 2.0 parts of 27.5% hydrogen peroxide to a three-necked flask and stir until well mixed;
[0070] S4. Add the above aqueous solutions A and B dropwise to a three-necked flask simultaneously for 2 hours. After the addition is complete, keep the flask warm for another 2 hours. Then add a 32% sodium hydroxide solution to the three-necked flask to adjust the pH of the mixed solution to 5.5-7.0 (within this near-neutral acid-base range, the product performance is almost the same), thus obtaining the anti-mud polycarboxylate superplasticizer.
[0071] Example 2
[0072] This embodiment prepares an anti-mud-type water-reducing agent. The specific process differs from that in Example 1 as follows:
[0073] In step S2, aqueous solution A consists of 16.6 parts anti-mud functional monomer, 10.6 parts acrylic acid, 4.6 parts hydroxyethyl acrylate, and 29.4 parts water;
[0074] Aqueous solution B: 0.29 parts ascorbic acid and 39.6 parts water;
[0075] Base material aqueous solution: 1.6 parts sodium hypophosphite and 155 parts water;
[0076] In step S3, 2.2 parts of hydrogen peroxide with a mass concentration of 27.5% were added to the three-necked flask;
[0077] The present invention also provides the following comparative examples:
[0078] Comparative Example 1
[0079] Point-T, a commercially available anti-mud polycarboxylate superplasticizer.
[0080] Comparative Example 2
[0081] This comparative example prepared a water-reducing agent, which differs from Example 1 in that:
[0082] Step S1 is excluded, and the anti-mud functional monomer in step S2 is replaced with acrylic acid.
[0083] Comparative Example 3
[0084] This comparative example prepared a water-reducing agent, which differs from Example 1 in that:
[0085] Step S1 is not included, and no anti-mud functional monomer is added in step S2.
[0086] Comparative Example 4
[0087] This comparative example prepared a water-reducing agent, which differs from Example 1 in that:
[0088] In step S2, the amount of anti-mud functional monomer used is 26 parts.
[0089] Comparative Example 5
[0090] This comparative example prepared a water-reducing agent, which differs from Example 1 in that:
[0091] In step S1, pyrophosphate is replaced with phosphoric acid.
[0092] Comparative Example 6
[0093] This comparative example prepared a water-reducing agent, which differs from Example 1 in that:
[0094] The anti-mud functional monomer was replaced in equal amounts with the capped amide pyrophosphate monomer prepared in Example 1 of patent CN118388530A.
[0095] To further illustrate the performance of the anti-mud polycarboxylate superplasticizer provided by this invention, the above-mentioned examples and comparative examples were tested for cement concrete workability according to GB 8076-2008 "Concrete Admixtures" standard, wherein the water-cement ratio was 0.44; the concrete mix proportions were as shown in Table 1, and the concrete performance test results are shown in Table 2, using the same compounding conditions.
[0096] Table 1 Concrete Mix Proportion Table
[0097]
[0098] The unit in the table is kg / m³. 3
[0099] Table 2 Results of concrete workability test
[0100]
[0101] The results in Table 2 show that:
[0102] Under the same dosage of polycarboxylate superplasticizer described in the embodiments, the dispersion and retention performance in high mud content manufactured sand concrete are superior to those of comparative examples 1 to 6. At the same time, the workability is better, and the anti-mud and slump retention performance is excellent.
[0103] In Comparative Example 2, replacing the anti-mud functional monomer with acrylic acid resulted in poor anti-mud performance. The dispersion effect was significantly weakened in manufactured sand concrete with high mud content, leading to poor workability of the concrete.
[0104] In Comparative Example 3, without the addition of anti-mud functional monomers, the anti-mud performance was poor. The dispersion effect was significantly weakened in high-mud-content manufactured sand concrete, slump loss was significantly accelerated, and the workability of the concrete was poor.
[0105] In Comparative Example 4, the higher dosage of anti-mud functional monomer resulted in better anti-mud performance, but significantly weakened slump retention. In high-mud-content manufactured sand concrete, slump loss was rapid, and concrete workability was poor.
[0106] In Comparative Example 5, replacing pyrophosphate with phosphoric acid weakened the anti-mud properties. In high-mud-content manufactured sand concrete, the dispersion effect was reduced, slump loss was faster, and the workability of the concrete was poor.
[0107] In Comparative Example 6, replacing the anti-mud functional monomer with the end-capped amide pyrophosphate monomer prepared in Example 1 of CN118388530A resulted in increased slump loss and weakened slump retention after 2 hours. This is because the anti-mud functional monomer is a composite of ester and pyrophosphate groups. The high-mud-content manufactured sand concrete has an appropriate hydrolysis rate, maintaining good concrete fluidity. However, the amide groups in the end-capped amide pyrophosphate monomer have weak hydrolysis capabilities and a slow hydrolysis rate, making it difficult to keep up with the rate of concrete slump loss over time, thus resulting in greater slump loss.
[0108] It should be noted that the specific parameters or reagents in the above embodiments are specific or preferred embodiments under the concept of the present invention, and not limitations thereof; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.
Claims
1. A mud-resistant polycarboxylate superplasticizer, characterized in that, The raw materials for preparing the anti-mud polycarboxylate superplasticizer, by weight, include: 200-210 parts of unsaturated polyether macromonomer; 10-20 parts of anti-mud functional monomer; 8-16.5 parts of unsaturated carboxylic acids and / or unsaturated carboxylic acid esters; Oxidizing agent 0.5-2.5 parts; 0.1-0.5 parts reducing agent; Chain transfer agent 0.6-1.6 parts; and Neutralizing agent; The structural formula of the anti-mud functional monomer is as follows: ； In the formula, R1 is -CH2- or -CH2-CH2-; The raw materials for preparing the anti-mud functional monomer, by weight, include: 100-120 parts of hydroxyl monoacrylate; 52-60 parts of pyrophosphate; 2-3 parts catalyst, and Polymerization inhibitor 0.06~0.1 parts; The preparation steps of the anti-mud functional monomer are as follows: The hydroxyl monoester of acrylate, the catalyst, and the organic solvent were stirred at 45℃-55℃ until completely dissolved to obtain the first mixture. Add formaldehyde aqueous solution to the first mixture, stir for 1.5-2.5 hours, and adjust the pH to 8-9 to obtain the second mixture; Add sodium chloride and hydrochloric acid to the second mixture, separate the liquids, and keep the organic phase. Anhydrous sodium sulfate was added to the organic phase and stirred. The mixture was filtered, and the solvent was removed from the filtrate. The filtrate was then subjected to vacuum distillation to obtain the intermediate. Add a polymerization inhibitor to the intermediate, and add pyrophosphate dropwise while stirring at 65℃~80℃. After the addition is completed, keep warm to obtain the anti-mud functional monomer.
2. The anti-mud polycarboxylate superplasticizer according to claim 1, characterized in that, The hydroxy acrylate monoester includes at least one of hydroxyethyl acrylate and hydroxypropyl acrylate.
3. The anti-mud polycarboxylate superplasticizer according to claim 1, characterized in that, The catalyst includes at least one of triethylenediamine and triethylamine.
4. The anti-mud polycarboxylate superplasticizer according to claim 1, characterized in that, The pyrophosphate is added dropwise over 1 to 3 hours, and the temperature is maintained for 1 to 2 hours.
5. The anti-mud polycarboxylate superplasticizer according to claim 1, characterized in that, The polymerization inhibitor includes one of hydroquinone, p-benzoquinone, p-hydroxyanisole, and 2-tert-butylhydroquinone.
6. The anti-mud polycarboxylate superplasticizer according to claim 1, characterized in that, The organic solvent includes at least one of acetonitrile and tetrahydrofuran.
7. A method for preparing an anti-mud-type polycarboxylate superplasticizer as described in any one of claims 1 to 6, characterized in that, Including the following steps: Unsaturated polyether macromonomers, chain transfer agents, and water are stirred and mixed to obtain a base aqueous solution; The anti-mud functional monomer, unsaturated carboxylic acid and / or unsaturated carboxylic acid ester are mixed evenly with water to prepare solution A; Mix the reducing agent and water thoroughly to prepare solution B. Add an oxidant to the aqueous solution of the base material, stir evenly, and then add solution A and solution B dropwise over a period of 1 to 3 hours. After the addition is complete, keep the mixture at 15-35℃ for 1-2 hours, then add a neutralizing agent to adjust the pH of the mixed solution to 5.5-7.0, thus obtaining the anti-mud polycarboxylate superplasticizer.
8. The application of the anti-mud polycarboxylate superplasticizer as described in any one of claims 1 to 6 in the preparation of precast concrete components.