Mud-resistant polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention relates to a mud-resistant polycarboxylate superplasticizer and a preparation method thereof, the mud-resistant polycarboxylate superplasticizer is prepared from the following raw materials: a polyether macromonomer, a hydrophobic macromonomer, an unsaturated acid monomer, a sulfonated compound, an oxidizing agent, a reducing agent, a chain transfer agent and water; wherein the preparation raw materials of the macromonomer with the hydrophobic function comprise an unsaturated compound and unsaturated phosphate. The prepared mud-resistant polycarboxylic acid water reducer has the advantages of being low in mixing amount, high in water reducing rate, good in workability and the like, is high in adaptability to high-mud-content aggregate (3%-10%), can remarkably improve the working performance of a cement-based material, and is suitable for various construction scenes.

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 thereof. BACKGROUND

[0002] As the most widely used and applied building material in the world, concrete is increasingly developing towards high performance and functionality. In recent years, the wide application of new concrete technologies such as pumping concrete, self-compacting concrete, high-strength high-performance concrete and the like has put forward higher requirements for the fluidity, strength, durability and construction adaptability of concrete. It has been proved in practice that admixtures are the key technical means to improve the performance of concrete, achieve energy saving and rapid construction, among which superplasticizers are the most widely used and fastest developing admixture varieties.

[0003] However, with the gradual replacement of natural sand by machine-made sand as the mainstream fine aggregate, the mud content (mainly stone powder) of concrete aggregate is generally as high as 3% to 10%. Clay minerals (such as montmorillonite and illite) can adsorb a large amount of traditional polycarboxylate superplasticizers (PCE) through intercalation, resulting in a significant increase in the water demand of concrete (an increase of more than 25%) and a rapid loss of fluidity (an expansion degree loss of more than 60%) and seriously affecting the construction efficiency and engineering quality.

[0004] At present, the anti-mud means adopted in the prior art has obvious limitations: inorganic salt anti-mud agents (such as sodium tripolyphosphate) easily introduce excessive air bubbles (air content > 5%) and cause the late strength of concrete to decrease (28d strength loss > 10%); small-molecule organic amines (such as triethanolamine) have poor compatibility with PCE and are prone to stratification; the traditional PCE modification method only adjusts the side chain density or introduces simple polar groups, and in high-mud systems, the superplasticizer is still adsorbed by clay in large amounts, making it difficult to balance the anti-mud function and the activation of cementitious materials. In addition, although polyoxyethylene stearyl ether (Brij series) has hydrophobic stearyl groups and hydrophilic polyoxyethylene chains, it can theoretically inhibit the water absorption and swelling of clay and complex Ca 2+ , but the prior art has not yet designed and introduced it into the main chain structure of PCE molecules in cooperation with hydrophobic functional macromonomer.

[0005] Therefore, it has become a technical problem to be solved in the field to develop a multifunctional anti-mud polycarboxylate superplasticizer that can effectively inhibit clay adsorption and improve the dispersibility and activity of cement and mineral admixtures. SUMMARY

[0006] Therefore, it is necessary to provide an anti-mud polycarboxylate superplasticizer and a preparation method thereof, which effectively overcome the poor adaptability and single function of the prior art in high-mud concrete systems.

[0007] To achieve the above object, the present application provides a technical solution:

[0008] The preparation raw material of the anti-mud polycarboxylate water reducer comprises a polyether macromonomer, a hydrophobic functional macromonomer, an unsaturated acid monomer, a sulfonated compound, an oxidizing agent, a reducing agent, a chain transfer agent, and water.

[0009] The preparation raw material of the hydrophobic functional macromonomer comprises an unsaturated compound and an unsaturated phosphate.

[0010] Preferably, the unsaturated compound comprises one of p-hydroxybenzoic acid, p-hydroxyphenylacetic acid, and p-hydroxyphenylpropionic acid, and the unsaturated phosphate comprises at least one of 1-aminoethyl diethyl phosphonate and (2-aminoethyl) diethyl phosphonate.

[0011] More specifically, the general formula of the unsaturated compound is HO-C6H4-(CH2) n -COOH, n = 0, 1 or 2.

[0012] The general formula of the unsaturated phosphate is (CH3CH2O)2P=(O)-CHR-NH2, wherein R = H or CH3.

[0013] Preferably, the structure formula of the hydrophobic functional macromonomer is as follows:

[0014]

[0015] In which, R1 is CH3.

[0016] Preferably, the preparation steps of the hydrophobic functional macromonomer comprise:

[0017] In the presence of a catalyst and a polymerization inhibitor, the unsaturated compound and the unsaturated phosphate are mixed, and the reaction is carried out at 60-120°C for 4-8h to obtain the hydrophobic functional macromonomer.

[0018] Preferably, the molar ratio of the unsaturated compound, the unsaturated phosphate, the catalyst, and the polymerization inhibitor is 1-1.2):1:(0.005-0.006):0.0009.

[0019] More specifically, the catalyst is any one of p-toluenesulfonic acid, concentrated sulfuric acid, heteropoly acid, stannous oxide, and dibutyl tin oxide.

[0020] The polymerization inhibitor is any one of p-hydroxyanisole, hydroquinone, p-tert-butyl hydroquinone, and phenothiazine.

[0021] Preferably, the structure formula of the sulfonated compound is R2O(CH2CH2O) nOSO3H, wherein R2 = C16-C18 alkyl chain, n = 30-60.

[0022] Preferably, the preparation method of the sulfonated compound comprises the steps of:

[0023] At 0-5℃, the chlorosulfonic acid is added dropwise into the polyoxyethylene stearyl ether, and after the addition is completed, the temperature is raised to 40-50℃, and the reaction is carried out for 3-5 hours.

[0024] Preferably, the molar ratio of the polyoxyethylene stearyl ether and the chlorosulfonic acid is (3-5):(2-4).

[0025] Preferably, the raw materials for preparing the anti-mud polycarboxylate superplasticizer include, in parts by weight:

[0026]

[0027] Preferably, the raw materials for preparing the anti-mud polycarboxylate superplasticizer further include 0.01-0.02 parts of ferrous sulfate.

[0028] More specifically, the polyether macromonomer is ethylene glycol monovinyl polyethylene glycol, 4-hydroxybutyl vinyl polyoxyethylene ether, isopentenyl polyethylene glycol ether, or methyl allyl alcohol polyoxyethylene ether, with a molecular weight of 3000-5000.

[0029] The reducing agent is one or a combination of ascorbic acid, formaldehyde sodium hyposulfite, sodium sulfite, sodium bisulfite, sodium hypophosphite, wherein sodium hypophosphite can also act as a chain transfer agent; the oxidizing agent is one or a combination of hydrogen peroxide, sodium peroxide, potassium peroxide, magnesium peroxide, sodium persulfate, ammonium persulfate, sodium dichromate, potassium dichromate, potassium permanganate; the chain transfer agent is one or a combination of thioglycolic acid, sodium hypophosphite, trisodium phosphate, mercaptopropionic acid, mercaptoethanol, mercaptoacetic acid; the unsaturated carboxylic acid monomer is one or a combination of acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, itaconic acid;

[0030] Another aspect of the present application provides a preparation method of an anti-mud polycarboxylate superplasticizer, which comprises the steps of:

[0031] The polyether macromonomer, the hydrophobic functional macromonomer, the oxidizing agent, and water are mixed to obtain a mother liquor;

[0032] The A liquid and the B liquid are added dropwise into the mother liquor, the dropwise addition is carried out for 60-130 minutes, and after the dropwise addition is completed, the mixture is kept at temperature for 1-2 hours to obtain the anti-mud polycarboxylate superplasticizer.

[0033] The A liquid is a mixed solution of the unsaturated acid and the sulfonated compound.

[0034] B solution is a mixed solution of reducing agent and chain transfer agent.

[0035] Advantages of the present application:

[0036] 1. Raw materials are easy to obtain and the process is environmentally friendly: The raw materials used in the present application are conventional chemical products, widely available and low cost; the preparation process is simple, the reaction conditions are mild, and it meets the requirements of green and environmental protection.

[0037] 2. Multiple effects of sulfonated compounds: By introducing sulfonated compounds, their hydrophobic structure can effectively hinder the water absorption and swelling of clay; the polyoxyethylene chain can complex Ca 2+ in the liquid phase, reducing the ionic strength of the system; the sulfonic group (-SO3 - ) not only enhances the water solubility of the molecule, but also forms hydrogen bonds with cement hydration products (such as C3A), promoting the activation of cementitious materials, thereby significantly improving the fluidity of concrete.

[0038] 3. Synergistic effect of molecular structure design:

[0039] Optimization of side chain structure: The sulfonic group in the side chain of the anti-mud polycarboxylate superplasticizer is connected to the main chain through an oxygen atom, reducing the space resistance of side chain swing, improving the activity freedom and entanglement wrapping ability of polyether chain segment, and enhancing the adsorption capacity of the molecule on the particle surface.

[0040] Rigid benzene ring: provides strong steric hindrance effect, enhances the rigidity of the molecular chain, reduces the ineffective intercalation and entanglement in the clay layer; its hydrophobic property helps to regulate the adsorption behavior of the molecule at the liquid-solid interface.

[0041] Phosphate group: has high affinity for Ca 2+ on the surface of cement particles and Al 3+ on the surface of clay, realizes selective anchoring adsorption, effectively competes for adsorption sites with clay, reduces ineffective adsorption, and improves dispersibility.

[0042] Amide group: enhances adsorption stability through hydrogen bonding, delays the initial adsorption rate of carboxyl groups on the surface of cement particles, gradually hydrolyzes in alkaline environment to release carboxyl groups, realizes sustained dispersion performance, and ensures good fluidity and stability of concrete over time.

[0043] 4. Excellent comprehensive application performance: The anti-mud polycarboxylate superplasticizer prepared by the present application has the advantages of low dosage, high water-reducing rate, and good workability, etc., and has strong adaptability to high-mud-content aggregate (3%~10%), which can significantly improve the workability of cement-based materials, and is suitable for various construction scenes. DETAILED DESCRIPTION

[0044] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in conjunction with specific examples.

[0045] In the examples, the test methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0046] I. Preparation of hydrophobic functional macromonomer A

[0047] 1. Hydrophobic functional macromonomer A1:

[0048] In a four-necked flask, 0.12 mol of p-hydroxybenzoic acid, 0.1 mol of diethyl 1-aminoethyl phosphonate, 0.0058 mol of p-toluenesulfonic acid, 0.0009 mol of hydroquinone, and 50 mL of toluene were added. The mixture was heated to 100°C and reacted for 6 h. After the reaction, the mixture was cooled, washed with 5% NaOH solution, and then washed with water until neutral. The mixture was dried over anhydrous sodium sulfate, and toluene was removed under reduced pressure to obtain the hydrophobic functional macromonomer A1.

[0049] 2. Hydrophobic functional macromonomer A2:

[0050] In a four-necked flask, 0.11 mol of p-hydroxybenzoic acid, 0.1 mol of diethyl 1-aminoethyl phosphonate, 0.0058 mol of p-toluenesulfonic acid, 0.0009 mol of hydroquinone, and 50 mL of toluene were added. The mixture was heated to 100°C and reacted for 6 h. After the reaction, the mixture was cooled, washed with 5% NaOH solution, and then washed with water until neutral. The mixture was dried over anhydrous sodium sulfate, and toluene was removed under reduced pressure to obtain the hydrophobic functional macromonomer A1.

[0051] II. Preparation of sulfonated compound B

[0052] 0.1 mol of polyoxyethylene stearyl ether was dissolved in 50 mL of dichloromethane, and 0.08 mL of chlorosulfonic acid was slowly added dropwise under ice bath (0-5°C). After the addition was completed, the temperature was raised to 40-50°C, and the reaction was carried out for 3-5 hours. After the reaction was completed, the pH was neutralized to 7, and the product was purified by dialysis to obtain the sulfonated compound B.

[0053] III. Preparation of polycarboxylic acid water reducer

[0054] S1: 180 parts of polyether macromonomer, 4 parts of hydrophobic functional macromonomer, and 300 parts of water were placed in a four-necked flask, and after stirring and dissolving, 0.01 parts of ferrous sulfate and 1.5 parts of oxidizing agent were added.

[0055] S2: 27 parts of unsaturated acid and 3 parts of sulfonated compound were configured as A liquid, the dropwise addition time was 50-120 min, 0.3 parts of reducing agent and 0.9 parts of chain transfer agent were configured as B liquid, the dropwise addition time was 60-130 min; A and B liquids were added to the above-mentioned S1, and after the reaction was completed, the mixture was kept at temperature for 1-2 h, and then neutralized with liquid alkali to obtain the product.

[0056] The proportions of Examples 1-4 and Comparative Examples 1-3 are shown in Table 1.

[0057] Table 1 Proportions of Examples 1-4 and Comparative Examples 1-3

[0058]

[0059]

[0060] Comparative Example 4

[0061] Commercially available anti-mud polycarboxylate superplasticizer (KZJ point-800AM).

[0062] The polycarboxylate superplasticizer samples synthesized in Examples 1-4 and Comparative Examples 1-4 and commercially available polycarboxylate superplasticizers were tested according to GB 8076-2008 "Concrete Admixtures" and GB 8077-2023 "Concrete Admixtures Homogeneity Test Method" to detect the initial slump and spread of concrete and the slump and spread over time of the polycarboxylate superplasticizer samples synthesized in Examples 1-4 and Comparative Examples 1-4 and commercially available polycarboxylate superplasticizers.

[0063] The concrete mix proportions were:

[0064] Cement (Runfeng P·O 42.5), machine-made sand 860 kg / m 3 , stone (5-20 mm) 1000 kg / m 3 , water 175 kg / m 3 ;

[0065] When the dosage of montmorillonite was 0, cement 360 kg / m 3 ;

[0066] When the dosage of montmorillonite was 10%, the actual 10% cement dosage was 36 kg / m 3 , cement 324 kg / m 3 ;

[0067] The results obtained are shown in Table 2.

[0068] Table 2 Concrete performance test results

[0069]

[0070]

[0071] From the results of Table 2, it can be seen that the experimental results of Examples 1-4 and Comparative Examples 1-4 show that the polycarboxylic water reducing agent prepared in the present application has little difference in initial spread and performance in the concrete experiment without adding montmorillonite, but the performance of the examples is better than that of the comparative examples. When 10% of montmorillonite is added, it can be found that the polycarboxylic water reducing agent synthesized in the examples and the comparative examples has little effect on the initial spread and the spread over time, while Comparative Example 4 shows a larger loss, indicating that the polycarboxylic water reducing agent synthesized in the present application has better clay resistance and better dispersion performance. Moreover, there is a larger difference in strength, and the strength of the examples is better than that of the comparative examples.

[0072] Comparative Example 1 does not add a hydrophobic monomer, and Comparative Example 2 does not add a sulfonated compound, and it can be found that the initial spread / time spread and strength are all worse than Example 1. Comparative Example 3 does not add a hydrophobic monomer and a sulfonated compound, and its performance is worse than that of Comparative Examples 1 and 2.

[0073] The polycarboxylic water reducing agent prepared in the present application has clay resistance, can improve the workability of concrete, has no adverse effects, is widely applicable, is fast to prepare, and has high efficiency.

[0074] It should be noted that the specific parameters or some reagents in the above examples are specific examples or preferred examples under the concept of the present application, but are not limited thereto; those skilled in the art can make adaptive adjustments within the scope of the concept and protection of the present application.

Claims

1. A mud-resistant polycarboxylate superplasticizer, characterized in that, The raw materials for preparing the anti-mud polycarboxylate superplasticizer include polyether macromonomers, hydrophobic macromonomers, unsaturated acid monomers, sulfonated compounds, oxidants, reducing agents, chain transfer agents, and water. The raw materials for preparing the hydrophobic functional macromonomer include unsaturated compounds and unsaturated phosphate esters.

2. The anti-mud polycarboxylate superplasticizer according to claim 1, characterized in that, The unsaturated compound includes one of p-hydroxybenzoic acid, p-hydroxyphenylacetic acid, and p-hydroxyphenylpropionic acid, and the unsaturated phosphate ester includes at least one of 1-aminoethylphosphonate diethyl ester and (2-aminoethyl)phosphonate diethyl ester.

3. The anti-mud polycarboxylate superplasticizer according to claim 2, characterized in that, The structural formula of the hydrophobic macromonomer is as follows: Wherein, R1 is CH3.

4. The anti-mud polycarboxylate superplasticizer according to claim 1, characterized in that, The preparation steps of the hydrophobic functional macromonomer include: In the presence of a catalyst and a polymerization inhibitor, an unsaturated compound is mixed with an unsaturated phosphate ester and reacted at 60℃-120℃ for 4-8 hours to obtain a hydrophobic functional macromonomer.

5. The anti-mud polycarboxylate superplasticizer according to claim 4, characterized in that, The molar ratio of the unsaturated compound, unsaturated phosphate ester, catalyst, and polymerization inhibitor is (1-1.2):1:(0.005-0.006):0.0009.

6. The anti-mud polycarboxylate superplasticizer according to claim 1, characterized in that, The structural formula of the sulfonated compound is: R2O(CH2CH2O) n OSO3H, where R2 = C16-C18 alkyl chain, n = 30-60.

7. The anti-mud polycarboxylate superplasticizer according to claim 6, characterized in that, The method for preparing the sulfonated compound includes the following steps: Chlorosulfonic acid was added dropwise to polyoxyethylene stearyl ether at 0℃-5℃. After the addition was complete, the temperature was raised to 40℃-50℃ and the reaction was carried out for 3-5 hours. After the reaction was completed, the sulfonated compound was obtained.

8. The anti-mud polycarboxylate superplasticizer according to claim 1, characterized in that, The raw materials for preparing the anti-mud polycarboxylate superplasticizer, by weight, include:

9. The anti-mud polycarboxylate superplasticizer according to claim 8, characterized in that, The raw materials for preparing the anti-mud polycarboxylate superplasticizer also include 0.01-0.02 parts by weight of ferrous sulfate.

10. A method for preparing the anti-mud-type polycarboxylate superplasticizer according to any one of claims 1 to 9, characterized in that, The method includes the following steps: A mother liquor is obtained by mixing polyether macromonomers, hydrophobic macromonomers, oxidants, and water. Add solution A and solution B dropwise to the mother liquor over a period of 60-130 minutes. After the addition is complete, keep the solution warm for 1-2 hours to obtain the anti-mud polycarboxylate superplasticizer. Solution A is a mixed solution of unsaturated acid and sulfonated compound; Solution B is a mixed solution of a reducing agent and a chain transfer agent.

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