Strongly alkaline resistant waterborne industrial paint and preparation method thereof

Abstract

The application discloses a strong-alkali-resistant waterborne industrial paint and a preparation method thereof, and relates to the technical field of paints. In the preparation of the strong-alkali-resistant waterborne industrial paint, epoxy polyorganosiloxane is prepared by reacting polysiloxane and allyl glycidyl ether; pre-modified graphene nanosheets are prepared by reacting graphene nanosheets, glycidyl furfuryl ether and phosphorus-containing furan monomers; modified graphene nanosheets are prepared by reacting the pre-modified graphene nanosheets and 2,4-dihydroxybenzophenone; fluorine-containing epoxy monomers are prepared by reacting bisphenol AF and epichlorohydrin; epoxy resin emulsion is prepared by emulsifying epoxy resin, the fluorine-containing epoxy monomers and the epoxy polyorganosiloxane; and the strong-alkali-resistant waterborne industrial paint is prepared by uniformly mixing the epoxy resin emulsion, the modified graphene nanosheets and a curing agent. The strong-alkali-resistant waterborne industrial paint prepared by the application has excellent strong-alkali resistance, flame resistance and anti-aging performance.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a water-based industrial paint resistant to strong alkali and its preparation method. Background Technology

[0002] Alkali-resistant paint is an industrial coating primarily used for pretreatment before applying anti-corrosion coatings to substrates such as walls, metals, and wood. It resists the erosion of the coating by alkaline substances and improves the adhesion and durability of the coating in humid or alkaline environments. Its applications cover chemical pipelines, power equipment, metallurgical facilities, bridges, concrete surfaces, and sewage treatment plants. Currently, the main components of commonly available alkali-resistant paints are epoxy resin, modified siloxanes, and polyvinylidene fluoride, providing basic chemical corrosion resistance. Some products enhance temperature resistance and mechanical strength by adding graphene and fluorinated elastomers. Water-based epoxy resin paint dominates the alkali-resistant paint market due to its environmental friendliness (using water as the dispersion medium, with VOC content far below national standards) and wide applicability (can be applied to damp surfaces such as basements and parking lots, with strong adhesion and excellent compatibility with various substrates such as steel, aluminum, galvanized steel, and cement). With industrial development, ordinary water-based epoxy resin paints can no longer meet the increasingly stringent requirements for resistance to strong alkalis. Furthermore, water-based epoxy resin paints also suffer from flammability and aging issues. Therefore, it is necessary to invent a water-based industrial paint with superior overall performance and strong alkali resistance to meet market demands. Summary of the Invention

[0003] The purpose of this invention is to provide a water-based industrial paint resistant to strong alkali and its preparation method, so as to solve the problems existing in the prior art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] A water-based industrial paint resistant to strong alkalis is prepared by reacting polysiloxane and allyl glycidyl ether to obtain epoxidized polysiloxane; reacting pre-modified graphene nanosheets and 2,4-dihydroxybenzophenone to obtain modified graphene nanosheets; emulsifying epoxy resin, fluorinated epoxy monomer, and epoxidized polysiloxane to obtain epoxy resin emulsion; and uniformly mixing the epoxy resin emulsion, modified graphene nanosheets, and curing agent to obtain the final product.

[0006] The polysiloxane is prepared by hydrolyzing and condensing azophenyldimethoxysilane and methyldimethoxysilane and then capping with trimethylchlorosilane.

[0007] The azophenyldimethoxysilane is prepared by reacting 1-chloroethylmethyldimethoxysilane with p-aminoazobenzene.

[0008] The pre-modified graphene nanosheets are prepared by reacting graphene nanosheets with glycidyl furfural ether and phosphorus-containing furan monomers.

[0009] The phosphorus-containing furan monomer is prepared by reacting 2-furan methylamine and tolylphosphine chloride.

[0010] The fluorinated epoxy monomer is prepared by reacting bisphenol AF and epichlorohydrin.

[0011] A method for preparing a water-based industrial paint resistant to strong alkalis, the method comprising the following preparation steps:

[0012] (1) Polysiloxane, allyl glycidyl ether, chloroplatinic acid and toluene are mixed evenly in a mass ratio of 1:(0.6~0.8):(0.02~0.03):(8~10), and stirred at 70~80℃ and 200~300r / min for 3~4h. Toluene is removed by rotary evaporation under reduced pressure. The mixture is washed 4 times with anhydrous ethanol and dried at 50~60℃ for 10~12h under vacuum to obtain epoxidized polysiloxane.

[0013] (2) Graphene nanosheets and N-methylpyrrolidone were mixed evenly at a mass ratio of 1:(400~500), and ultrasonically dispersed at 0~2℃ and 300W for 1~2h. Phosphorus-containing furan monomers with a mass ratio of 40~50 times the mass of the graphene nanosheets were added, along with glycidyl furfuryl ether with a mass ratio of 30~40 times the mass of the graphene nanosheets. The mixture was placed in a high-pressure reactor and stirred at 100~106℃ and 300~400r / min for 2~3h. After centrifugation, the mixture was washed 5 times with acetone and then subjected to vacuum conditions. Pre-modified graphene nanosheets were prepared by drying at 0~60℃ for 12~14h; the pre-modified graphene nanosheets, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide and toluene were mixed evenly at a mass ratio of 1:(7~8):(0.2~0.3):(30~40), and stirred at 70~80℃ and 300~400r / min for 4~5h under nitrogen protection. After centrifugation, the nanosheets were washed 4 times with anhydrous ethanol and dried at 50~60℃ for 8~10h under vacuum to obtain modified graphene nanosheets.

[0014] (3) Mix bisphenol AF and epichlorohydrin at a molar ratio of 1:(8~10), add tetraethylammonium chloride at a mass of 0.03~0.05 times the mass of bisphenol AF, stir at 300~400r / min for 55~65min at 70℃, cool down to 60℃, add sodium hydroxide aqueous solution with a mass fraction of 30% at a uniform rate of 4~5 times the mass of bisphenol AF within 10min, stir and react at 68~72℃ for 100~120min, remove unreacted epichlorohydrin by rotary evaporation under reduced pressure, cool down to 60℃, add benzene at a mass of 7~8 times the mass of bisphenol AF, add sodium hydroxide aqueous solution with a mass fraction of 30% at a mass of 2~3 times the mass of bisphenol AF, continue stirring and react for 2~3h, cool to room temperature, wash 3 times with hot water at a temperature of 70~80℃, dry at 60~70℃ for 10~12h under vacuum to obtain fluorinated epoxy monomer;

[0015] (4) Weigh out 24-26 parts of epoxy resin, 18-20 parts of fluorinated epoxy monomer, 7-8 parts of epoxidized polysiloxane, 1.8-2 parts of modified graphene nanosheets, 9-10 parts of curing agent, 3-4 parts of Span-60, and 4-5 parts of polysorbate-20 by weight; mix the epoxy resin, fluorinated epoxy monomer, epoxidized polysiloxane, Span-60, and polysorbate-20 evenly, and stir at 64-66℃ and 600-700r / min. Distilled water was added dropwise using a separatory funnel at a rate of 6-8 ml / min. The conductivity of the reaction system was monitored using a conductivity meter. The reaction was stopped when the conductivity of the reaction system changed abruptly. After cooling to room temperature, the product was discharged to obtain an epoxy resin emulsion. The epoxy resin emulsion, modified graphene nanosheets, and curing agent were mixed evenly, and the viscosity was adjusted to 70-80 KU with distilled water. The mixture was stirred at 1600-2000 r / min for 30-40 min to obtain a water-based industrial paint resistant to strong alkalis.

[0016] As an optimization, the preparation method of the polysiloxane in step (1) is as follows: Azophenyldimethoxysilane, methyldimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, and toluene are mixed evenly in a mass ratio of 1:(1.4~1.6):(0.7~0.8):(0.01~0.02):(13~14). The mixture is stirred at 78~82℃ and 300~400r / min for 4~5h. Trimethylchlorosilane is added at a mass ratio of 0.1~0.2 times that of methyldimethoxysilane. The temperature is raised to 96~100℃ and the mixture is stirred for another 2~3h. The mixture is washed three times with deionized water and dried at 70~80℃ under vacuum for 8~10h to obtain the polysiloxane. The reaction mechanism is as follows:

[0017] .

[0018] As an optimization, the preparation method of the azophenyldimethoxysilane is as follows: 1-chloroethylmethyldimethoxysilane and p-aminoazophenyl are added to anhydrous ethanol at a molar ratio of 1:1, in an amount 8-10 times the mass of 1-chloroethylmethyldimethoxysilane. Triethylamine is then added in an amount 0.04-0.05 times the mass of 1-chloroethylmethyldimethoxysilane. The mixture is stirred at 60-70°C and 300-400 r / min for 3-4 h. The mixture is then dried under vacuum at 60-70°C for 10-12 h to obtain azophenyldimethoxysilane. The reaction mechanism is shown below:

[0019] .

[0020] As an optimization, the preparation method of the phosphorus-containing furan monomer in step (2) is as follows: 2-furan methylamine and toluenephosphine chloride are added to anhydrous ethanol at a molar ratio of 1:1, which is 9 to 11 times the mass of 2-furan methylamine. Triethylamine is added at a mass of 0.05 to 0.06 times the mass of 2-furan methylamine. The mixture is stirred at 300 to 400 r / min for 2 to 3 h at 60 to 70 °C. The mixture is then dried at 50 to 60 °C under vacuum for 12 to 14 h to obtain the phosphorus-containing furan monomer. The reaction mechanism is as follows:

[0021] .

[0022] As an optimization, the graphene nanosheets in step (2) have a diameter of 5~10μm and a thickness of 4~20nm, and were purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.

[0023] As an optimization, the reaction mechanism of the fluorinated epoxy monomer in step (3) is as follows:

[0024] .

[0025] As an optimization, the epoxy resin used in step (4) is of type E44.

[0026] As an optimization, the curing agent in step (4) is a water-based epoxy curing agent, model CYDHD-280.

[0027] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0028] In preparing a strong alkali-resistant water-based industrial paint, this invention first reacts 1-chloroethylmethyldimethoxysilane and p-aminoazobenzene to obtain azophenyldimethoxysilane; then hydrolyzes and condenses azophenyldimethoxysilane and methyldimethoxysilane, and capsulates them with trimethylchlorosilane to obtain polysiloxane; an azobenzene structure and Si-H bonds are introduced into the side chain of the polysiloxane; the Si-H bonds then undergo a hydrosilylation reaction with the carbon-carbon double bond on allyl glycidyl ether, introducing epoxy groups into the side chain of the polysiloxane molecule to obtain epoxidized polysiloxane; the epoxy groups on the epoxidized polysiloxane can participate in the curing process of the industrial paint, the siloxane structure on the main chain can improve the flame retardant properties of the strong alkali-resistant water-based industrial paint, and the azobenzene structure on the side chain undergoes a cis-trans isomerization change under ultraviolet light, converting ultraviolet light energy into chemical energy, thereby improving the anti-aging properties of the strong alkali-resistant water-based industrial paint. The working principle is as follows:

[0029] .

[0030] Secondly, phosphorus-containing furan monomers were prepared by reacting 2-furanmethylamine and toluenephosphine chloride; pre-modified graphene nanosheets were prepared by reacting graphene nanosheets with glycidyl furfuryl ether and phosphorus-containing furan monomers; the furan groups on glycidyl furfuryl ether and phosphorus-containing furan monomers were reacted with the surface of graphene nanosheets via Diels-Alder reaction to introduce phosphorus and epoxy groups onto the surface of graphene nanosheets; the introduction of phosphorus can further improve the flame retardant properties of strong alkaline water-based industrial paints; the epoxy groups were reacted with 2,4-dihydroxybenzophenone to prepare modified graphene nanosheets, and 2-hydroxybenzophenone was introduced onto the modified graphene nanosheets. The 2-hydroxybenzophenone structure forms an intramolecular hydrogen bond between the ortho-hydroxyl group and the carbonyl oxygen atom, constituting a chelate ring structure. When exposed to ultraviolet light, the molecule absorbs energy, causing the hydrogen bond to break and the chelate ring to open. The energy absorbed by the ultraviolet light is converted into heat energy through molecular thermal vibration and released, further enhancing the anti-aging performance of water-based industrial paints resistant to strong alkalis. In addition, the two-dimensional layered structure of graphene nanosheets can form a physical barrier in industrial paints, making the diffusion process of corrosive media more tortuous and slow, effectively blocking the penetration of corrosive media, forming a dense protective layer, and improving the resistance of water-based industrial paints to strong alkalis.

[0031] Finally, fluorinated epoxy monomers are prepared by reacting bisphenol AF and epichlorohydrin. The fluorinated epoxy monomers participate in the curing of industrial paints, introducing fluorine atoms into the paint film. Fluorine atoms have strong electronegativity and low surface energy, which improves the hydrophobic and oleophobic properties of water-based industrial paints resistant to strong alkalis. They are inert to corrosive media and further improve the material's resistance to strong alkalis. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] The epoxy resin used in the following examples and comparative examples is E44; the curing agent used is CYDHD-280; the graphene nanosheets used have a diameter of 5~10μm and a thickness of 4~20nm, and were purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.; the HLB of the Span-60 used is 4.7; and the HLB of the polysorbate-20 used is 16.7.

[0034] Example 1: A method for preparing a water-based industrial paint resistant to strong alkalis, the method comprising the following preparation steps:

[0035] (1) 1-Chloroethylmethyldimethoxysilane and p-aminoazobenzene were added to anhydrous ethanol at a molar ratio of 1:1, which was 8 times the mass of 1-chloroethylmethyldimethoxysilane. Triethylamine was added at a mass ratio of 0.04 times the mass of 1-chloroethylmethyldimethoxysilane. The mixture was stirred at 300 r / min for 4 h at 60 °C and dried at 60 °C for 12 h under vacuum to obtain azophenyldimethoxysilane. Azophenyldimethoxysilane, methyldimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, and toluene were mixed evenly at a mass ratio of 1:1.4:0.7:0.01:13. The reaction was stirred at 78℃ and 300 r / min for 5 h. Trimethylchlorosilane, with a mass ratio of 0.1 times that of methyldimethoxysilane, was added. The temperature was raised to 96℃, and the reaction was stirred for another 3 h. The mixture was washed three times with deionized water and dried at 70℃ for 10 h under vacuum to obtain polysiloxane. Polysiloxane, allyl glycidyl ether, chloroplatinic acid, and toluene were mixed evenly at a mass ratio of 1:0.6:0.02:8 and stirred at 70℃ and 200 r / min for 4 h. Toluene was removed by rotary evaporation under reduced pressure. The mixture was washed four times with anhydrous ethanol and dried at 50℃ for 12 h under vacuum to obtain epoxidized polysiloxane.

[0036] (2) 2-Furfural methylamine and toluenephosphine chloride were added to anhydrous ethanol at a molar ratio of 1:1, which was 9 times the mass of 2-furan methylamine. Triethylamine was added at a mass of 0.05 times the mass of 2-furan methylamine. The mixture was stirred at 60°C and 300 r / min for 3 h, and then dried at 50°C under vacuum for 14 h to obtain a phosphorus-containing furan monomer. Graphene nanosheets and N-methylpyrrolidone were mixed evenly at a mass ratio of 1:400 and ultrasonically dispersed at 0°C and 300 W for 1 h. Phosphorus-containing furan monomer with a mass of 40 times the mass of graphene nanosheets was added, and then 3 times the mass of graphene nanosheets was added. 0 times the amount of glycidyl furfural ether was placed in a high-pressure reactor and stirred at 100℃ and 300 r / min for 3 h. After centrifugation, the mixture was washed 5 times with acetone and dried at 50℃ under vacuum for 14 h to obtain pre-modified graphene nanosheets. The pre-modified graphene nanosheets, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide, and toluene were mixed evenly at a mass ratio of 1:7:0.2:30 and stirred at 70℃ and 300 r / min for 5 h under nitrogen protection. After centrifugation, the mixture was washed 4 times with anhydrous ethanol and dried at 50℃ under vacuum for 10 h to obtain modified graphene nanosheets.

[0037] (3) Bisphenol AF and epichlorohydrin were mixed at a molar ratio of 1:8. Tetraethylammonium chloride was added at a mass of 0.03 times that of bisphenol AF. The mixture was stirred at 300 r / min for 55 min at 70 °C. The mixture was then cooled to 60 °C. A 30% sodium hydroxide aqueous solution with a mass fraction of 4 times that of bisphenol AF was added dropwise over 10 min. The mixture was stirred at 68 °C for 100 min. Unreacted epichlorohydrin was removed by rotary evaporation under reduced pressure. The mixture was cooled to 60 °C. Benzene with a mass fraction of 7 times that of bisphenol AF was added. A 30% sodium hydroxide aqueous solution with a mass fraction of 2 times that of bisphenol AF was added. The mixture was stirred for 2 h. The mixture was cooled to room temperature and washed three times with hot water at 70 °C. The mixture was dried at 60 °C for 12 h under vacuum to obtain a fluorinated epoxy monomer.

[0038] (4) Weigh 24 parts of epoxy resin, 18 parts of fluorinated epoxy monomer, 7 parts of epoxidized polysiloxane, 1.8 parts of modified graphene nanosheets, 9 parts of curing agent, 3 parts of Span-60, and 4 parts of polysorbate-20 by mass. Mix the epoxy resin, fluorinated epoxy monomer, epoxidized polysiloxane, Span-60, and polysorbate-20 evenly. Under stirring conditions of 64℃ and 600r / min, add distilled water dropwise from a constant pressure separatory funnel at a drop rate of 6ml / min. Monitor the conductivity of the reaction system with a conductivity meter. Stop the reaction when the conductivity of the reaction system jumps. After cooling to room temperature, discharge the material to obtain an epoxy resin emulsion. Mix the epoxy resin emulsion, modified graphene nanosheets, and curing agent evenly. Adjust the viscosity to 70KU with distilled water. Stir at 1600r / min for 40min to obtain a water-based industrial paint resistant to strong alkali.

[0039] Example 2: A method for preparing a water-based industrial paint resistant to strong alkalis, the method comprising the following preparation steps:

[0040] (1) 1-Chloroethylmethyldimethoxysilane and p-aminoazobenzene were added to anhydrous ethanol at a molar ratio of 1:1, which was 9 times the mass of 1-chloroethylmethyldimethoxysilane. Triethylamine was added at a mass ratio of 0.045 times the mass of 1-chloroethylmethyldimethoxysilane. The mixture was stirred at 350 r / min for 3.5 h at 65 °C and dried at 65 °C for 11 h under vacuum to obtain azophenyldimethoxysilane. Azophenyldimethoxysilane, methyldimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, and toluene were mixed evenly at a mass ratio of 1:1.5:0.75:0.015:13.5. The reaction was stirred at 80℃ and 350 r / min for 4.5 h. Trimethylchlorosilane, with a mass ratio of 0.15 times that of methyldimethoxysilane, was added. The temperature was raised to 98℃, and the reaction was stirred for another 2.5 h. The mixture was washed three times with deionized water and dried at 75℃ for 9 h under vacuum to obtain polysiloxane. Polysiloxane, allyl glycidyl ether, chloroplatinic acid, and toluene were mixed evenly at a mass ratio of 1:0.7:0.025:9. The mixture was stirred at 75℃ and 250 r / min for 3.5 h. Toluene was removed by rotary evaporation under reduced pressure. The mixture was washed four times with anhydrous ethanol and dried at 55℃ for 11 h under vacuum to obtain epoxidized polysiloxane.

[0041] (2) 2-Furfural and toluenephosphine chloride were added to anhydrous ethanol at a molar ratio of 1:1, which was 10 times the mass of 2-furanmamide. Triethylamine was added at a mass of 0.055 times the mass of 2-furanmamide. The mixture was stirred at 350 r / min for 2.5 h at 65 °C and dried at 55 °C for 13 h under vacuum to obtain a phosphorus-containing furan monomer. Graphene nanosheets and N-methylpyrrolidone were mixed evenly at a mass ratio of 1:450 and ultrasonically dispersed at 300 W for 1.5 h at 1 °C. Phosphorus-containing furan monomer with a mass of 45 times the mass of graphene nanosheets was added, and then added at a mass of 3 times the mass of graphene nanosheets. Five times the amount of glycidyl furfural ether was placed in a high-pressure reactor and stirred at 103℃ and 350 r / min for 2.5 h. After centrifugation, the mixture was washed five times with acetone and dried at 55℃ under vacuum for 13 h to obtain pre-modified graphene nanosheets. The pre-modified graphene nanosheets, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide, and toluene were mixed evenly at a mass ratio of 1:7.5:0.25:35 and stirred at 75℃ and 350 r / min for 4.5 h under nitrogen protection. After centrifugation, the mixture was washed four times with anhydrous ethanol and dried at 55℃ under vacuum for 9 h to obtain modified graphene nanosheets.

[0042] (3) Bisphenol AF and epichlorohydrin were mixed at a molar ratio of 1:9. Tetraethylammonium chloride was added at a mass of 0.04 times that of AF. The mixture was stirred at 350 r / min for 60 min at 70 °C. The mixture was cooled to 60 °C. A 30% sodium hydroxide aqueous solution with a mass fraction of 4.5 times that of bisphenol AF was added dropwise over 10 min. The mixture was stirred at 70 °C for 110 min. Unreacted epichlorohydrin was removed by rotary evaporation under reduced pressure. The mixture was cooled to 60 °C. Benzene with a mass fraction of 7.5 times that of bisphenol AF was added. A 30% sodium hydroxide aqueous solution with a mass fraction of 2.5 times that of bisphenol AF was added. The mixture was stirred for 2.5 h. The mixture was cooled to room temperature. The mixture was washed three times with hot water at 75 °C. The mixture was dried at 65 °C for 11 h under vacuum to obtain a fluorinated epoxy monomer.

[0043] (4) Weigh out 25 parts epoxy resin, 19 parts fluorinated epoxy monomer, 7.5 parts epoxidized polysiloxane, 1.9 parts modified graphene nanosheets, 9.5 parts curing agent, 3.5 parts Span-60, and 4.5 parts polysorbate-20 by weight; mix the epoxy resin, fluorinated epoxy monomer, epoxidized polysiloxane, Span-60, and polysorbate-20 evenly, and stir at 65°C and 650 r / min under constant pressure. Distilled water was added dropwise using a separatory funnel at a rate of 7 ml / min. The conductivity of the reaction system was monitored using a conductivity meter. The reaction was stopped when the conductivity of the reaction system changed abruptly. After cooling to room temperature, the product was discharged to obtain an epoxy resin emulsion. The epoxy resin emulsion, modified graphene nanosheets, and curing agent were mixed evenly, and the viscosity was adjusted to 75 KU with distilled water. The mixture was stirred at 1800 r / min for 35 min to obtain a water-based industrial paint resistant to strong alkalis.

[0044] Example 3: A method for preparing a water-based industrial paint resistant to strong alkalis, the method comprising the following preparation steps:

[0045] (1) 1-Chloroethylmethyldimethoxysilane and p-aminoazobenzene were added to anhydrous ethanol at a molar ratio of 1:1, which was 10 times the mass of 1-chloroethylmethyldimethoxysilane. Triethylamine was added at a mass ratio of 0.05 times the mass of 1-chloroethylmethyldimethoxysilane. The mixture was stirred at 70°C and 400 r / min for 3 h. The mixture was then dried at 70°C under vacuum for 10 h to obtain azophenyldimethoxysilane. Azophenyldimethoxysilane, methyldimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, and toluene were mixed evenly at a mass ratio of 1:1.6:0.8:0.02:14. The reaction was stirred at 82℃ and 400 r / min for 4 h. Trimethylchlorosilane, with a mass of 0.2 times that of methyldimethoxysilane, was added. The temperature was raised to 100℃, and the reaction was stirred for another 2 h. The mixture was washed three times with deionized water and dried at 80℃ for 8 h under vacuum to obtain polysiloxane. Polysiloxane, allyl glycidyl ether, chloroplatinic acid, and toluene were mixed evenly at a mass ratio of 1:0.8:0.03:10 and stirred at 80℃ and 300 r / min for 3 h. Toluene was removed by rotary evaporation under reduced pressure. The mixture was washed four times with anhydrous ethanol and dried at 60℃ for 10 h under vacuum to obtain epoxidized polysiloxane.

[0046] (2) 2-Furfural methylamine and toluenephosphine chloride were added to anhydrous ethanol at a molar ratio of 1:1, which was 11 times the mass of 2-furan methylamine. Triethylamine was added at a mass of 0.06 times the mass of 2-furan methylamine. The mixture was stirred at 70°C and 400 r / min for 2 h, and then dried at 60°C under vacuum for 12 h to obtain a phosphorus-containing furan monomer. Graphene nanosheets and N-methylpyrrolidone were mixed evenly at a mass ratio of 1:500 and ultrasonically dispersed at 2°C and 300 W for 2 h. Phosphorus-containing furan monomer with a mass of 50 times the mass of graphene nanosheets was added. 40 times the amount of glycidyl furfural ether was placed in a high-pressure reactor and stirred at 106℃ and 400 r / min for 2 h. After centrifugation, the mixture was washed 5 times with acetone and dried at 60℃ for 12 h under vacuum to obtain pre-modified graphene nanosheets. The pre-modified graphene nanosheets, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide, and toluene were mixed evenly in a mass ratio of 1:8:0.3:40 and stirred at 80℃ and 400 r / min for 4 h under nitrogen protection. After centrifugation, the mixture was washed 4 times with anhydrous ethanol and dried at 60℃ for 8 h under vacuum to obtain modified graphene nanosheets.

[0047] (3) Bisphenol AF and epichlorohydrin were mixed at a molar ratio of 1:10. Tetraethylammonium chloride was added at a mass of 0.05 times that of bisphenol AF. The mixture was stirred at 70°C and 400 r / min for 65 min. The mixture was cooled to 60°C and a 30% sodium hydroxide aqueous solution with a mass fraction of 5 times that of bisphenol AF was added dropwise over 10 min. The mixture was stirred at 72°C for 100 min. Unreacted epichlorohydrin was removed by rotary evaporation under reduced pressure. The mixture was cooled to 60°C and benzene with a mass fraction of 8 times that of bisphenol AF was added. A 30% sodium hydroxide aqueous solution with a mass fraction of 3 times that of bisphenol AF was added. The mixture was stirred and reacted for 3 h. The mixture was cooled to room temperature and washed three times with hot water at 80°C. The mixture was dried at 70°C for 10 h under vacuum to obtain a fluorinated epoxy monomer.

[0048] (4) Weigh 26 parts of epoxy resin, 20 parts of fluorinated epoxy monomer, 8 parts of epoxidized polysiloxane, 2 parts of modified graphene nanosheets, 10 parts of curing agent, 4 parts of Span-60, and 5 parts of polysorbate-20 by mass. Mix the epoxy resin, fluorinated epoxy monomer, epoxidized polysiloxane, Span-60, and polysorbate-20 evenly. Under stirring conditions of 66℃ and 700r / min, add distilled water dropwise from a constant pressure separatory funnel at a drop rate of 8ml / min. Monitor the conductivity of the reaction system with a conductivity meter. Stop the reaction when the conductivity of the reaction system jumps. After cooling to room temperature, discharge the material to obtain an epoxy resin emulsion. Mix the epoxy resin emulsion, modified graphene nanosheets, and curing agent evenly. Adjust the viscosity to 80KU with distilled water and stir at 2000r / min for 30min to obtain a water-based industrial paint resistant to strong alkali.

[0049] Comparative Example 1:

[0050] The difference between the preparation method of the strong alkali resistant water-based industrial paint in Comparative Example 1 and Example 2 lies in the different step (1). Step (1) is modified as follows: Dimethyldimethoxysilane, methyldimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, and toluene are mixed evenly in a mass ratio of 1:1.5:0.75:0.015:13.5, and stirred at 80°C and 350 r / min for 4.5 h. Then, trimethyl chloride is added at a mass ratio of 0.15 times that of methyldimethoxysilane. Silane was heated to 98°C and stirred for 2.5 hours. The mixture was washed three times with deionized water and dried at 75°C for 9 hours under vacuum to obtain polysiloxane. Polysiloxane, allyl glycidyl ether, chloroplatinic acid, and toluene were mixed uniformly in a mass ratio of 1:0.7:0.025:9 and stirred at 75°C and 250 rpm for 3.5 hours. Toluene was removed by rotary evaporation under reduced pressure. The mixture was washed four times with anhydrous ethanol and dried at 55°C for 11 hours under vacuum to obtain epoxidized polysiloxane. The remaining steps were the same as in Example 2.

[0051] Comparative Example 2:

[0052] The preparation method of the strong alkali resistant water-based industrial paint in Comparative Example 2 differs from that in Example 2 in that step (1) is omitted, and step (4) is modified as follows: Weigh 32.5 parts of epoxy resin, 19 parts of fluorinated epoxy monomer, 1.9 parts of modified graphene nanosheets, 9.5 parts of curing agent, 3.5 parts of Span-60, and 4.5 parts of polysorbate-20 by mass; Mix the epoxy resin, fluorinated epoxy monomer, Span-60, and polysorbate-20 evenly, and heat at 65°C and 650 rpm. Under stirring conditions of 7 ml / min, distilled water was added dropwise from a constant-pressure separatory funnel. The drop rate of the distilled water was 7 ml / min, and the conductivity of the reaction system was monitored using a conductivity meter. The reaction was stopped when the conductivity of the reaction system changed abruptly. After cooling to room temperature, the product was discharged to obtain an epoxy resin emulsion. The epoxy resin emulsion, modified graphene nanosheets, and curing agent were mixed evenly, and the viscosity was adjusted to 75 KU with distilled water. The mixture was stirred at 1800 r / min for 35 min to obtain a water-based industrial paint resistant to strong alkalis. The remaining steps were the same as in Example 2.

[0053] Comparative Example 3:

[0054] The preparation method of the strong alkali resistant water-based industrial paint in Comparative Example 3 differs from that in Example 2 only in step (2). Step (2) is modified as follows: graphene nanosheets and N-methylpyrrolidone are mixed evenly at a mass ratio of 1:450, ultrasonically dispersed at 1°C and 300W for 1.5h, glycidyl furfuryl ether with a mass of 35 times that of the graphene nanosheets is added, and the mixture is placed in a high-pressure reactor and stirred at 103°C and 350r / min for 2.5h. After centrifugation, the mixture is... Pre-modified graphene nanosheets were prepared by washing five times with acetone and drying at 55°C for 13 hours under vacuum. The pre-modified graphene nanosheets, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide, and toluene were mixed uniformly at a mass ratio of 1:7.5:0.25:35. The mixture was stirred at 75°C and 350 rpm for 4.5 hours under nitrogen protection. After centrifugation, the nanosheets were washed four times with anhydrous ethanol and dried at 55°C for 9 hours under vacuum to obtain modified graphene nanosheets. The remaining steps were the same as in Example 2.

[0055] Comparative Example 4:

[0056] The preparation method of the strong alkali resistant water-based industrial paint in Comparative Example 4 differs from that in Example 2 only in step (2). Step (2) is modified as follows: 2-furan methylamine and toluenephosphine chloride are added to anhydrous ethanol at a molar ratio of 1:1, which is 10 times the mass of 2-furan methylamine. Triethylamine is added at a mass of 0.055 times the mass of 2-furan methylamine. The mixture is stirred at 65°C and 350 r / min for 2.5 h, and then dried at 55°C under vacuum for 13 h to obtain a phosphorus-containing furan monomer. Graphene nanosheets and N-methylpyrrolidone were mixed uniformly at a mass ratio of 1:450 and ultrasonically dispersed at 1°C and 300W for 1.5 h. Phosphorus-containing furan monomers with a mass ratio of 45 times that of the graphene nanosheets and glycidyl furfuryl ether with a mass ratio of 35 times that of the graphene nanosheets were added. The mixture was placed in a high-pressure reactor and stirred at 103°C and 350 r / min for 2.5 h. After centrifugation, the mixture was washed five times with acetone and dried at 55°C under vacuum for 13 h to obtain modified graphene nanosheets. The remaining steps were the same as in Example 2.

[0057] Comparative Example 5:

[0058] The preparation method of the strong alkali resistant water-based industrial paint in Comparative Example 5 differs from that in Example 2 only in that step (2) is omitted, and step (4) is modified as follows: Weigh 25 parts of epoxy resin, 19 parts of fluorinated epoxy monomer, 7.5 parts of epoxidized polysiloxane, 9.5 parts of curing agent, 3.5 parts of Span-60, and 4.5 parts of polysorbate-20 by mass; Mix the epoxy resin, fluorinated epoxy monomer, epoxidized polysiloxane, Span-60, and polysorbate-20 evenly, and heat at 6... At 5℃ and under stirring conditions of 650 r / min, distilled water was added dropwise from a constant pressure separatory funnel at a dropping rate of 7 ml / min. The conductivity of the reaction system was monitored using a conductivity meter. The reaction was stopped when the conductivity of the reaction system showed a jump. After cooling to room temperature, the product was discharged to obtain an epoxy resin emulsion. The epoxy resin emulsion and curing agent were mixed evenly, and the viscosity was adjusted to 75 KU with distilled water. The mixture was stirred at 1800 r / min for 35 min to obtain a water-based industrial paint resistant to strong alkalis. The remaining steps were the same as in Example 2.

[0059] Comparative Example 6

[0060] The preparation method of the strong alkali resistant water-based industrial paint in Comparative Example 6 differs from that in Example 2 only in that step (3) is omitted, and step (4) is modified as follows: Weigh 44 parts of epoxy resin, 7.5 parts of epoxidized polysiloxane, 1.9 parts of modified graphene nanosheets, 9.5 parts of curing agent, 3.5 parts of Span-60, and 4.5 parts of polysorbate-20 by mass; mix the epoxy resin, epoxidized polysiloxane, Span-60, and polysorbate-20 evenly, and heat at 65°C and 650°C. Under stirring conditions at 1800 rpm, distilled water was added dropwise from a constant-pressure separatory funnel at a dropping rate of 7 ml / min. The conductivity of the reaction system was monitored using a conductivity meter. The reaction was stopped when the conductivity of the reaction system showed a jump. After cooling to room temperature, the product was discharged to obtain an epoxy resin emulsion. The epoxy resin emulsion, modified graphene nanosheets, and curing agent were mixed evenly, and the viscosity was adjusted to 75 KU with distilled water. The mixture was stirred at 1800 rpm for 35 min to obtain a water-based industrial paint resistant to strong alkalis. The remaining steps were the same as in Example 2.

[0061] Test Example 1

[0062] Test of resistance to strong alkali

[0063] Test method: The strong alkali resistant water-based industrial paints prepared in the examples and comparative examples were coated on tinplate with dimensions of 50×100×0.5mm, dried at 100℃ for 3h, cooled to 80℃ and dried for 5h, and then left to stand at room temperature for 12h to obtain test pieces. Two-thirds of the test pieces were immersed in a 50% sodium hydroxide aqueous solution and left to stand at room temperature for 24h. After removal, the test pieces were rinsed with deionized water and then blotted dry with filter paper. The presence of blistering, cracking, softening, powdering, or peeling was immediately observed to determine the corrosion resistance of the paint film. Grade 1 – No change on the paint film surface; Grade 2 – Blistering, cracking, softening, powdering, or peeling occurs on the paint film surface. The results are shown in Table 1.

[0064] Table 1

[0065] ;

[0066] A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-6 in Table 1 reveals that the strong alkali resistant water-based industrial paint prepared by this invention has good strong alkali resistance.

[0067] By comparison, the strong alkali resistance of Examples 1-3 is better than that of Comparative Example 5, indicating that the two-dimensional sheet structure of graphene nanosheets can form a physical barrier in industrial paint, making the diffusion process of corrosive media more tortuous and slow, effectively blocking the penetration of corrosive media, forming a dense protective layer, and improving the strong alkali resistance of water-based industrial paint.

[0068] By comparison, the strong alkali resistance of Examples 1-3 is better than that of Comparative Example 6, indicating that the fluorinated epoxy monomer is prepared by reacting bisphenol AF and epichlorohydrin. The fluorinated epoxy monomer participates in the curing of industrial paint, introducing fluorine atoms into the paint film. Fluorine atoms have strong electronegativity and low surface energy, which improves the hydrophobic and oleophobic properties of the water-based industrial paint with strong alkali resistance, and makes it inert to corrosive media, further improving the material's strong alkali resistance.

[0069] Test Example 2

[0070] Anti-aging performance test

[0071] Test method: The samples from the examples and comparative examples were poured into polytetrafluoroethylene molds, dried at 100℃ for 3 hours, cooled to 80℃ and dried for 5 hours, and then allowed to stand at room temperature for 12 hours. The cured samples were then cut into standard strips according to GB / T1040.1. The tensile strength P of the standard strips was tested using a tensile testing machine. The standard strips were then irradiated with a xenon arc lamp for 7 days at an irradiation intensity of 0.51 W / m². 2 (340nm) to obtain aged samples; the tensile strength Q of the aged samples was tested using a tensile testing machine, and the performance degradation rate of the standard sample before and after aging was calculated; performance degradation rate = (PQ) / P×100%. The results are shown in Table 2.

[0072] Table 2

[0073] ;

[0074] A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-6 in Table 2 reveals that the water-based industrial paint resistant to strong alkali prepared by this invention has good anti-aging properties.

[0075] By comparison, the performance degradation rate of Examples 1-3 was less than that of Comparative Examples 1-2, indicating that azophenyldimethoxysilane was prepared by reacting 1-chloroethylmethyldimethoxysilane and p-aminoazobenzene; polysiloxane was prepared by hydrolyzing and condensing azophenyldimethoxysilane and methyldimethoxysilane and then capping with trimethylchlorosilane; an azobenzene structure was introduced into the side chain of the polysiloxane; the azobenzene structure on the side chain undergoes a cis-trans isomerization change under ultraviolet light, converting ultraviolet light energy into chemical energy, thereby improving the anti-aging performance of the strong alkali resistant water-based industrial paint.

[0076] By comparison, the performance degradation rate of Examples 1-3 was less than that of Comparative Examples 4-5, indicating that pre-modified graphene nanosheets were prepared by reacting graphene nanosheets with glycidyl furfuryl ether and phosphorus-containing furan monomers; the furan groups on the glycidyl furfuryl ether and phosphorus-containing furan monomers underwent a Diels-Alder reaction with the surface of the graphene nanosheets, introducing epoxy groups onto the surface of the graphene nanosheets; the epoxy groups reacted with 2,4-dihydroxybenzophenone to prepare modified graphene nanosheets, introducing a 2-hydroxybenzophenone structure onto the modified graphene nanosheets. The 2-hydroxybenzophenone structure forms an intramolecular hydrogen bond with the carbonyl oxygen atom through the ortho-hydroxyl group, forming a chelate ring structure. When irradiated with ultraviolet light, the molecule absorbs energy, causing the hydrogen bond to break and the chelate ring to open, converting the energy absorbed by ultraviolet light into heat energy through molecular thermal vibration, further improving the anti-aging performance of the strong alkali resistant water-based industrial paint.

[0077] Test Example 3

[0078] Flame retardant performance testing

[0079] Test method: The samples from the examples and comparative examples were poured into polytetrafluoroethylene molds, dried at 100℃ for 3 hours, cooled to 80℃ and dried for 5 hours, and then allowed to stand at room temperature for 12 hours. The cured samples were then cut into standard strips according to GB / T2406.2, and the limiting oxygen index of the standard strips was tested. The results are shown in Table 3.

[0080] Table 3

[0081] ;

[0082] A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-6 in Table 3 reveals that the water-based industrial paint resistant to strong alkali prepared by this invention has good flame retardant properties.

[0083] By comparison, the limiting oxygen index of Examples 1-3 is greater than that of Comparative Example 2, indicating that polysiloxane is prepared by hydrolyzing and condensing azophenyldimethoxysilane and methyldimethoxysilane and then end-capping with trimethylchlorosilane; the siloxane structure can improve the flame retardant properties of water-based industrial paints resistant to strong alkalis.

[0084] By comparison, the limiting oxygen index of Examples 1-3 is greater than that of Comparative Examples 3 and 5, indicating that phosphorus-containing furan monomers are prepared by reacting 2-furan methylamine and toluene phosphine chloride; pre-modified graphene nanosheets are prepared by reacting graphene nanosheets with glycidyl furfuryl ether and phosphorus-containing furan monomers; and phosphorus groups on glycidyl furfuryl ether and phosphorus-containing furan monomers undergo Diels-Alder reaction with the surface of graphene nanosheets to introduce phosphorus elements into the surface of graphene nanosheets. The introduction of phosphorus elements can further improve the flame retardant properties of strong alkaline water-based industrial paints.

[0085] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A water-based industrial paint resistant to strong alkalis, characterized in that, The alkali-resistant water-based industrial paint is prepared by reacting polysiloxane and allyl glycidyl ether to obtain epoxidized polysiloxane; reacting pre-modified graphene nanosheets and 2,4-dihydroxybenzophenone to obtain modified graphene nanosheets; emulsifying epoxy resin, fluorinated epoxy monomer, and epoxidized polysiloxane to obtain epoxy resin emulsion; and uniformly mixing epoxy resin emulsion, modified graphene nanosheets, and curing agent to obtain the final product. The polysiloxane is prepared by hydrolyzing and condensing azophenyldimethoxysilane and methyldimethoxysilane and then capping with trimethylchlorosilane. The azophenyldimethoxysilane is prepared by reacting 1-chloroethylmethyldimethoxysilane with p-aminoazobenzene. The pre-modified graphene nanosheets are prepared by reacting graphene nanosheets with glycidyl furfural ether and phosphorus-containing furan monomers. The phosphorus-containing furan monomer is prepared by reacting 2-furan methylamine and tolylphosphine chloride. The fluorinated epoxy monomer is prepared by reacting bisphenol AF and epichlorohydrin.

2. A method for preparing a water-based industrial paint resistant to strong alkalis, characterized in that, The preparation method of the strong alkali resistant water-based industrial paint includes the following preparation steps: (1) Polysiloxane, allyl glycidyl ether, chloroplatinic acid and toluene are mixed evenly and reacted at 70~80℃ for 3~4h. Toluene is removed by rotary evaporation under reduced pressure, washed and dried under vacuum to obtain epoxidized polysiloxane. (2) Mix pre-modified graphene nanosheets, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide and toluene evenly, react at 70~80℃ for 4~5h under nitrogen protection, centrifuge, wash and dry to obtain modified graphene nanosheets. (3) Mix bisphenol AF and epichlorohydrin, add tetraethylammonium chloride, stir at 70°C for 55-65 min, cool down to 60°C, add sodium hydroxide aqueous solution dropwise, stir at 68-72°C for 100-120 min, remove unreacted epichlorohydrin by rotary evaporation under reduced pressure, cool down to 60°C, add benzene and sodium hydroxide aqueous solution, continue stirring for 2-3 h, cool to room temperature, wash with hot water, and dry under vacuum to obtain fluorinated epoxy monomer; (4) Mix epoxy resin, fluorinated epoxy monomer, epoxidized polysiloxane, Span-60, and polysorbate-20 evenly. Under the stirring conditions of 64~66℃ and 600~700r / min, add distilled water dropwise from a constant pressure separatory funnel and monitor the conductivity of the reaction system with a conductivity meter. Stop the reaction when the conductivity of the reaction system jumps. After cooling to room temperature, discharge the material to obtain epoxy resin emulsion. Mix epoxy resin emulsion, modified graphene nanosheets, and curing agent evenly. Adjust the viscosity to 70~80KU with distilled water and stir at 1600~2000r / min for 30~40min to obtain strong alkali resistant water-based industrial paint.

3. The method for preparing a strong alkali-resistant water-based industrial paint according to claim 2, characterized in that, The preparation method of the polysiloxane in step (1) is as follows: Azophenyldimethoxysilane, methyldimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide and toluene are mixed evenly and stirred at 78~82℃ for 4~5h. Trimethylchlorosilane is added, the temperature is raised to 96~100℃, and the reaction is continued for 2~3h. After washing and drying, polysiloxane is obtained.

4. The method for preparing a strong alkali-resistant water-based industrial paint according to claim 3, characterized in that, The preparation method of the azophenyldimethoxysilane is as follows: 1-chloroethylmethyldimethoxysilane and p-aminoazobenzene are added to anhydrous ethanol, triethylamine is added, the reaction is carried out at 60~70℃ for 3~4h, and then dried under vacuum to obtain azophenyldimethoxysilane.

5. The method for preparing a strong alkali-resistant water-based industrial paint according to claim 2, characterized in that, The preparation method of the pre-modified graphene nanosheets in step (2) is as follows: graphene nanosheets and N-methylpyrrolidone are mixed evenly, ultrasonically dispersed for 1-2 hours, phosphorus-containing furan monomer and glycidyl furfur ether are added, and the mixture is placed in a high-pressure reactor and reacted at 100-106℃ for 2-3 hours. After centrifugation, washing, and vacuum drying, the pre-modified graphene nanosheets are obtained.

6. The method for preparing a strong alkali-resistant water-based industrial paint according to claim 5, characterized in that, The preparation method of the phosphorus-containing furan monomer is as follows: 2-furanmethylamine and toluenephosphine chloride are added to anhydrous ethanol, triethylamine is added, the reaction is carried out at 60~70℃ for 2~3h, and then vacuum dried to obtain the phosphorus-containing furan monomer.

7. The method for preparing a strong alkali-resistant water-based industrial paint according to claim 2, characterized in that, The molar ratio of bisphenol AF and epichlorohydrin in step (3) is 1:(8~10).

8. The method for preparing a strong alkali-resistant water-based industrial paint according to claim 2, characterized in that, The sodium hydroxide aqueous solution in step (3) has a mass fraction of 30%.

9. The method for preparing a strong alkali-resistant water-based industrial paint according to claim 2, characterized in that, The amounts of epoxy resin, fluorinated epoxy monomer, epoxidized polysiloxane, modified graphene nanosheets, curing agent, Span-60, and polysorbate-20 in step (4) are as follows: by mass parts, epoxy resin 24-26 parts, fluorinated epoxy monomer 18-20 parts, epoxidized polysiloxane 7-8 parts, modified graphene nanosheets 1.8-2 parts, curing agent 9-10 parts, Span-60 3-4 parts, and polysorbate-20 4-5 parts.

10. The method for preparing a strong alkali-resistant water-based industrial paint according to claim 2, characterized in that, The drip rate of the distilled water in step (4) is 6~8 ml / min.