Organic-inorganic hybrid early-strength polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention discloses an organic-inorganic hybrid early-strength polycarboxylate superplasticizer and a preparation method thereof, and the organic-inorganic hybrid early-strength polycarboxylate superplasticizer comprises the following components: a modified polyether monomer, methyl allyl polyoxyethylene ether, deionized water, a hydrogen peroxide solution, acrylic acid, a reducing agent, a chain transfer agent, a sodium hydroxide solution, modified graphene oxide, modified cellulose and modified fly ash, the invention relates to the technical field of polycarboxylate superplasticizers. Methyl allyl polyoxyethylene ether is modified through benzoic anhydride, so that the adsorption capacity of methyl allyl polyoxyethylene ether on the surfaces of cement particles is enhanced, and compared with unmodified methyl allyl polyoxyethylene ether, modified molecules can be more effectively combined with active sites on the surfaces of the cement particles through new functional groups of the modified molecules, so that the adsorption capacity of the modified molecules on the surfaces of the cement particles is improved. Therefore, a more stable adsorption layer is formed, the polycarboxylic acid water reducer can play a better dispersion role, and cement particles can be kept in a better dispersion state.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polycarboxylic acid water reducing agent, in particular to an organic-inorganic hybrid early-strength polycarboxylic acid water reducing agent and a preparation method thereof. BACKGROUND

[0002] As the third generation of water reducing agent products, polycarboxylic acid water reducing agent has strong designability of molecular structure, great potential for high performance, and can be prepared into multifunctional products by selecting different functional monomers for copolymerization.

[0003] Referring to a kind of early-strength polycarboxylic acid water reducing agent (publication number: CN103373831BA), the early-strength polycarboxylic acid water reducing agent is prepared from monomer a, monomer b, monomer c, initiator, chain transfer agent, pH regulator and early-strength catalytic component, and the steps are as follows: first, 5% to 14% of monomer a, 80% to 92% of modified low-foam polyether monomer b with a molecular weight of M=2000-5000, 2% to 7% of monomer c, and simultaneously uniformly drop the initiator and chain transfer agent into the aqueous solution at 65°C to 75°C to undergo copolymerization reaction to obtain a copolymerization product, the total amount of a+b+c is 100% by weight; then, the pH regulator is added to the copolymer for neutralization reaction to adjust the pH value of the copolymer to 7.2-7.5; finally, the organic or inorganic early-strength catalytic component is added to the copolymer. However, the compressive strength and slump of the polycarboxylic acid water reducing agent prepared by the above technical solution need to be further improved; therefore, the present application proposes an organic-inorganic hybrid early-strength polycarboxylic acid water reducing agent and a preparation method thereof to solve the above-mentioned problems. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides an organic-inorganic hybrid early-strength polycarboxylic acid water reducing agent and a preparation method thereof, which solves the problems mentioned in the background. TECHNICAL SOLUTION

[0005] To achieve the above-mentioned purposes, the present application is implemented by the following technical solution: an organic-inorganic hybrid early-strength polycarboxylic acid water reducing agent, comprising the following components: modified polyether monomer, methyl allyl polyoxyethylene ether, deionized water, hydrogen peroxide solution, acrylic acid, reducing agent, chain transfer agent, sodium hydroxide solution, modified graphene oxide, modified cellulose, and modified fly ash.

[0006] A preparation method of an organic-inorganic hybrid early-strength polycarboxylic acid water reducing agent, comprising the following preparation steps: Step one: pour 0.2-0.5g of modified polyether monomer and 0.75-1.8g of methyl allyl polyoxyethylene ether into 25-35g of deionized water, and add 0.05-0.08g of modified graphene oxide, and stir for 25-40min; Step 2: Add 0.4-0.8g of modified cellulose and 0.1-0.2g of hydrogen peroxide solution with a mass fraction of 26.5% in sequence. Heat to 25-35℃ and, while stirring, slowly add a mixed solution of 3-5.5g acrylic acid, 0.02-0.04g ascorbic acid and 0.25-0.45g mercaptopropionic acid, and continue stirring. Step 3: Add a 32% sodium hydroxide solution to adjust the pH of the mixed solution to neutral. Step 4: Add 15-25g of modified fly ash and stir evenly to obtain the organic-inorganic hybrid early-strength polycarboxylate superplasticizer. In step one, the modified polyether monomer is prepared as follows: (1) Add 6-10g of benzoic anhydride to 20-25g of methyl allyl polyoxyethylene ether, heat to 60-65℃, and react for 1.5-2h; (2) After washing the reaction product 3-5 times, extract it with ethyl acetate to obtain the modified polyether monomer.

[0007] Preferably, in step two, the dropping time of the mixed solution of acrylic acid, ascorbic acid and mercaptopropionic acid is controlled within 3 hours.

[0008] Preferably, in step (2), the reaction product is first washed 1-2 times with a saturated sodium chloride solution, and then washed 2-3 times with a sodium carbonate solution.

[0009] Preferably, the modified graphene oxide is prepared by: adding a modifier to 44-50g of graphene oxide dispersion with a concentration of 1mg / mL, stirring and mixing to obtain the modified graphene oxide. The modifier comprises the following components by weight: 1.5-2.5g of polyvinylpyrrolidone, 0.45-0.75g of benzotriazole, and 45-50g of deionized protein.

[0010] Preferably, the modified fly ash is prepared by grinding 2.5-4g of fly ash, then adding 8-15g of hydrochloric acid solution with a concentration of 2mol / L, stirring at 100-150r / min for 15-30min at a temperature of 40-50℃, letting it stand for 1.5-2h, washing it 2-3 times with deionized water, filtering it, and drying it in a drying oven at 60℃ for 10-12h to obtain the modified fly ash.

[0011] Preferably, the modified cellulose is prepared by: hydrolyzing cellulose, adding 1-3.5g of maleic acid ester to 7-10g of cellulose hydrolysis product, heating to 70-80℃, stirring and reacting for 1.5-2h, and then cooling to room temperature to obtain modified cellulose.

[0012] Preferably, the specific steps for hydrolyzing cellulose are as follows: ① Pour 6-10 mL of deionized water into 6-10 g of concentrated phosphoric acid, mix, then add 1.8-2.5 g of cellulose, heat to 135-160℃, and stir to hydrolyze; ②After filtration, add 2-3.5g of saturated barium hydroxide solution and let stand for 20-24 hours; ③Filter by vacuum filtration, or remove the water from the solution by rotary evaporation.

[0013] Preferably, in step ①, the stirring speed during hydrolysis is 350-450 r / min, and the hydrolysis time is 2.5-3 h. Beneficial effects

[0014] This invention provides an organic-inorganic hybrid early-strength polycarboxylate superplasticizer and its preparation method. Compared with the prior art, it has the following advantages: (1) In this invention, methyl allyl polyoxyethylene ether is modified by benzoic anhydride to enhance its adsorption capacity on the surface of cement particles. Compared with unmodified methyl allyl polyoxyethylene ether, the modified molecules can more effectively combine with the active sites on the surface of cement particles through their new functional groups, thereby forming a more stable adsorption layer, which helps polycarboxylate superplasticizer to better exert its dispersing effect and allows cement particles to maintain a better dispersion state. Due to the enhanced adsorption performance, a more effective steric hindrance effect can be generated, which prevents the agglomeration of cement particles and improves the fluidity, slump and compressive strength of the paste.

[0015] (2) This invention modifies graphene oxide by incorporating benzotriazole and polyvinylpyrrolidone into the graphene oxide dispersion, thereby preventing the agglomeration between graphene oxide sheets, improving the stability and dispersibility of graphene oxide, filling the gaps between cement particles, and improving the compressive strength and slump of concrete; the addition of modified graphene oxide allows polycarboxylate superplasticizer to better exert its steric hindrance and electrostatic repulsion, thereby increasing the fluidity of the paste, making the concrete easier to operate during construction, and better filling the mold, etc.

[0016] (3) By modifying cellulose, the present invention enhances its adsorption capacity on the surface of cement particles, enabling it to adhere better to the surface of cement particles, generating a better steric hindrance effect, preventing the aggregation between cement particles, and improving the fluidity and slump of the paste. Furthermore, the chemical structure of the modified cellulose hydrolysis product is more compatible with polycarboxylate superplasticizer, enabling it to work better in the mixed system, reducing adverse phenomena such as stratification and precipitation caused by incompatibility, and ensuring the stability of the polycarboxylate superplasticizer system.

[0017] (4) The present invention modifies fly ash to increase its specific surface area and enhance its activity, thereby improving the adsorption capacity of polycarboxylate superplasticizer on the surface of cement particles, improving the fluidity and slump of the paste, and enabling cement particles to come into more contact with water to undergo hydration reaction and generate more hydration products. These hydration products interweave and fill the pores of cement stone, improving the density of concrete and thus enhancing the early and later strength of concrete. Attached Figure Description

[0018] Figure 1 SEM images of fly ash before and after modification provided by this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0020] A method for preparing an organic-inorganic hybrid early-strength polycarboxylate superplasticizer includes the following preparation steps: Step 1: Preparation of modified polyether monomer: Add 6g of benzoic anhydride to 20g of methyl allyl polyoxyethylene ether, heat to 60℃, and react for 1.5h; wash the reaction product once with saturated sodium chloride solution, then wash the reaction product twice with sodium carbonate solution, and then extract with ethyl acetate to obtain the modified polyether monomer. 0.2g of modified polyether monomer and 0.75g of methyl allyl polyoxyethylene ether were poured into 25g of deionized water, and 0.05g of modified graphene oxide was added. The mixture was stirred and reacted for 25min. The modified graphene oxide is prepared by adding 1.5g of polyvinylpyrrolidone, 0.45g of benzotriazole and 45g of deionized iron to a 44g graphene oxide dispersion with a concentration of 1mg / mL. After stirring and mixing, the modified graphene oxide is obtained. Step 2: Add 0.4g of modified cellulose and 0.1g of hydrogen peroxide solution with a mass fraction of 26.5% in sequence. Heat to 25°C and, while stirring, slowly add a mixed solution of 3g acrylic acid, 0.02g ascorbic acid and 0.25g mercaptopropionic acid. The addition should be completed within 3 hours, and stirring should continue. The modified cellulose is prepared as follows: 6 mL of deionized water is poured into 6 g of concentrated phosphoric acid, mixed, and 1.8 g of cellulose is added. The mixture is heated to 135 °C and stirred at 350 r / min for 2.5 h for hydrolysis. After filtration, 2 g of saturated barium hydroxide solution is added and allowed to stand for 20 h. The mixture is then filtered and the solution is evaporated by rotary evaporation to remove the water, thus obtaining the cellulose hydrolysis product. 7 g of the cellulose hydrolysis product is taken, and 1 g of maleic acid ester is added to it. The mixture is heated to 70 °C, stirred for 1.5 h, and then cooled to room temperature to obtain the modified cellulose. Step 3: Add a 32% sodium hydroxide solution to adjust the pH of the mixed solution to neutral. Step 4: Add 15g of modified fly ash and stir evenly to obtain the organic-inorganic hybrid early-strength polycarboxylate superplasticizer. The modified fly ash is prepared by grinding 2.5g of fly ash, then adding 8g of hydrochloric acid solution with a concentration of 2mol / L, stirring at 100r / min for 15min at 40℃, letting stand for 1.5h, washing twice with deionized water, filtering, and drying in a drying oven at 60℃ for 10h to obtain modified fly ash. Example

[0021] A method for preparing an organic-inorganic hybrid early-strength polycarboxylate superplasticizer includes the following preparation steps: Step 1: Preparation of modified polyether monomer: Add 6-10g of benzoic anhydride to 22g of methyl allyl polyoxyethylene ether, heat to 62℃, and react for 1.8h; wash the reaction product twice with saturated sodium chloride solution, then wash the reaction product twice with sodium carbonate solution, and then extract with ethyl acetate to obtain the modified polyether monomer. 0.3g of modified polyether monomer and 1.2g of methyl allyl polyoxyethylene ether were poured into 30g of deionized water, and 0.06g of modified graphene oxide was added. The mixture was stirred and reacted for 30min. The modified graphene oxide is prepared by adding 2g of polyvinylpyrrolidone, 0.6g of benzotriazole and 47g of deionized protein to a 47g graphene oxide dispersion with a concentration of 1mg / mL. After stirring and mixing, the modified graphene oxide is obtained. Step 2: Add 0.6g of modified cellulose and 0.2g of hydrogen peroxide solution with a mass fraction of 26.5% in sequence. Heat to 30℃ and, while stirring, slowly add a mixed solution of 4.5g acrylic acid, 0.03g ascorbic acid and 0.35g mercaptopropionic acid. The addition should be completed within 3 hours, and stirring should continue. The modified cellulose is prepared as follows: 9 mL of deionized water is poured into 8 g of concentrated phosphoric acid, mixed, and 2 g of cellulose is added. The mixture is heated to 150°C and hydrolyzed by stirring at 400 r / min for 2.6 h. After filtration, 3 g of saturated barium hydroxide solution is added and allowed to stand for 22 h. The mixture is then filtered and the solution is evaporated by rotary evaporation to remove the water, thus obtaining the cellulose hydrolysate. 8 g of the cellulose hydrolysate is taken and 2.5 g of maleic acid ester is added to it. The mixture is heated to 75°C and stirred for 1.8 h. After cooling to room temperature, the modified cellulose is obtained. Step 3: Add a 32% sodium hydroxide solution to adjust the pH of the mixed solution to neutral. Step 4: Add 20g of modified fly ash and stir evenly to obtain the organic-inorganic hybrid early-strength polycarboxylate superplasticizer. The modified fly ash is prepared as follows: 3g of fly ash is ground, and then 12g of hydrochloric acid solution with a concentration of 2mol / L is added. The mixture is stirred at 130r / min for 20min at 45℃, then allowed to stand for 1.7h. After washing with deionized water three times, the mixture is filtered and dried in a drying oven at 60℃ for 11h to obtain the modified fly ash. Example

[0022] A method for preparing an organic-inorganic hybrid early-strength polycarboxylate superplasticizer includes the following preparation steps: Step 1: Preparation of modified polyether monomer: Add 10g of benzoic anhydride to 25g of methyl allyl polyoxyethylene ether, heat to 65℃, and react for 2h; wash the reaction product twice with saturated sodium chloride solution, then wash the reaction product three times with sodium carbonate solution, and then extract with ethyl acetate to obtain the modified polyether monomer. 0.5g of modified polyether monomer and 1.8g of methyl allyl polyoxyethylene ether were poured into 35g of deionized water, and 0.08g of modified graphene oxide was added. The mixture was stirred and reacted for 40min. The modified graphene oxide is prepared by adding 2.5g of polyvinylpyrrolidone, 0.75g of benzotriazole and 50g of deionized iron to a 50g graphene oxide dispersion with a concentration of 1mg / mL, stirring and mixing to obtain the modified graphene oxide. Step 2: Add 0.8g of modified cellulose and 0.2g of hydrogen peroxide solution with a mass fraction of 26.5% in sequence. Heat to 35℃ and, while stirring, slowly add a mixed solution of 5.5g acrylic acid, 0.04g ascorbic acid and 0.45g mercaptopropionic acid. The addition should be completed within 3 hours, and stirring should continue. The modified cellulose is prepared as follows: 10 mL of deionized water is poured into 10 g of concentrated phosphoric acid, mixed, and 2.5 g of cellulose is added. The mixture is heated to 160 °C and stirred at 450 r / min for 3 h for hydrolysis. After filtration, 3.5 g of saturated barium hydroxide solution is added and allowed to stand for 24 h. The mixture is then filtered and the solution is evaporated by rotary evaporation to remove the water, thus obtaining the cellulose hydrolysis product. 10 g of the cellulose hydrolysis product is taken and 3.5 g of maleic acid ester is added to it. The mixture is heated to 80 °C, stirred for 2 h, and then cooled to room temperature to obtain the modified cellulose. Step 3: Add a 32% sodium hydroxide solution to adjust the pH of the mixed solution to neutral. Step 4: Add 25g of modified fly ash and stir evenly to obtain the organic-inorganic hybrid early-strength polycarboxylate superplasticizer. The modified fly ash is prepared by grinding 4g of fly ash, then adding 15g of hydrochloric acid solution with a concentration of 2mol / L, stirring at 150r / min for 30min at 50℃, letting stand for 2h, washing three times with deionized water, filtering, and drying in a drying oven at 60℃ for 12h to obtain modified fly ash.

[0023] Comparative Example 1 Compared with Example 1, the difference is that the modified polyether monomer in Example 1 is replaced with methyl allyl polyoxyethylene ether; the rest remains the same.

[0024] Comparative Example 2 Compared with Example 1, the difference is that the modified graphene oxide in Example 1 is not added; everything else remains the same.

[0025] Comparative Example 3 Compared with Example 1, the difference is that the modified cellulose in Example 1 is not added; everything else remains the same.

[0026] Comparative Example 4 Compared with Example 1, the difference is that the modified fly ash in Example 1 is not added; everything else remains the same.

[0027] The fluidity of the paste was tested according to GB / T 8077-2000; the results are shown in Table 1.

[0028] Table 1

[0029] Concrete preparation: 360 kg / m³ of standard cement 3 792 kg / m³ of sand 3 Xiao Shi 290Kg / m 3 (5-10mm), large stone 678Kg / m 3(10-20mm), water-to-glue ratio is 0.4.

[0030] Compressive strength test: The slump and strength of concrete were tested according to GB / T 50107-2010; the results are shown in Table 2.

[0031] Table 2

[0032] As shown in Tables 1 and 2, compared with Comparative Examples 1-4, Examples 1-3 showed significant improvements in the fluidity, slump, and compressive strength of the concrete paste.

[0033] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0034] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An organic-inorganic hybrid early-strength polycarboxylate water reducer, characterized by, It comprises the following components: modified polyether monomer, methyl allyl polyoxyethylene ether, deionized water, hydrogen peroxide solution, acrylic acid, reducing agent, chain transfer agent, sodium hydroxide solution, modified graphene oxide, modified cellulose, modified fly ash.

2. The method for preparing the organic-inorganic hybrid early-strength polycarboxylate superplasticizer according to claim 1, characterized in that, It comprises the following preparation steps: Step one, pour 0.2-0.5g of modified polyether monomer and 0.75-1.8g of methyl allyl polyoxyethylene ether into 25-35g of deionized water, and add 0.05-0.08g of modified graphene oxide, stir for 25-40min; Step two, add 0.4-0.8g of modified cellulose, 0.1-0.2g of hydrogen peroxide solution with a mass fraction of 26.5%, and slowly add 3-5.5g of mixed solution of acrylic acid, ascorbic acid and mercaptopropionic acid under stirring condition, continue to stir; Step three, add sodium hydroxide solution with a mass fraction of 32%, and adjust the pH value of the mixed solution to neutral; Step four, add 15-25g of modified fly ash, stir evenly, and obtain the organic-inorganic hybrid early strength polycarboxylic acid water reducer; In the step one, the preparation method of the modified polyether monomer is: (1) add 6-10g of benzoic anhydride to 20-25g of methyl allyl polyoxyethylene ether, heat to 60-65℃, and react for 1.5-2h; (2) after washing the reaction product for 3-5 times, extract with ethyl acetate, and obtain the modified polyether monomer.

3. The preparation method of the organic-inorganic hybrid early-strength polycarboxylate superplasticizer according to claim 2, characterized in that: In the step two, the dropping time of the mixed solution of acrylic acid, ascorbic acid and mercaptopropionic acid is controlled within 3h.

4. The preparation method of the organic-inorganic hybrid early-strength polycarboxylate superplasticizer according to claim 2, characterized in that: In the (2), first wash the reaction product with saturated sodium chloride solution for 1-2 times, and then wash the reaction product with sodium carbonate solution for 2-3 times.

5. The preparation method of the organic-inorganic hybrid early-strength polycarboxylate superplasticizer according to claim 2, characterized in that: The preparation method of the modified graphene oxide is: pour the modifier into 44-50g of graphene oxide dispersion solution with a concentration of 1mg / mL, stir uniformly, and obtain the modified graphene oxide; The modifier comprises the following components by weight: polyvinylpyrrolidone 1.5-2.5g, benzotriazole 0.45-0.75g, and deionized water 45-50g.

6. The preparation method of the organic-inorganic hybrid early-strength polycarboxylate superplasticizer according to claim 2, characterized in that: The preparation method of the modified fly ash is: grind 2.5-4g of fly ash, then add 8-15g of hydrochloric acid solution with a concentration of 2mol / L, stir at a speed of 100-150r / min for 15-30min under the condition of 40-50℃, stand for 1.5-2h, wash with deionized water for 2-3 times, then filter, dry in a drying oven at 60℃ for 10-12h, and obtain the modified fly ash.

7. The preparation method of the organic-inorganic hybrid early-strength polycarboxylate superplasticizer according to claim 2, characterized in that: The preparation method of the modified cellulose is: hydrolyze the cellulose, pour 1-3.5g of maleate into 7-10g of cellulose hydrolysate, heat to 70-80℃, stir for 1.5-2h, and then cool to room temperature to obtain the modified cellulose.

8. The preparation method of the organic-inorganic hybrid early-strength polycarboxylate superplasticizer according to claim 7, characterized in that: The specific steps for hydrolyzing the cellulose are: ①Pour 6-10 mL of deionized water into 6-10 g of concentrated phosphoric acid, mix, then add 1.8-2.5 g of cellulose, heat to 135-160 ℃, and hydrolyze with stirring; ②After filtration, add 2-3.5 g of saturated barium hydroxide solution, and stand for 20-24 h; ③After suction filtration, the solution is rotary evaporated to remove the water therein.

9. The preparation method of the organic-inorganic hybrid early-strength polycarboxylate superplasticizer according to claim 8, characterized in that: In the step ①, the stirring speed during the hydrolysis is 350-450 r / min, and the hydrolysis time is 2.5-3 h.

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