Strong-alkali-resistant water-based industrial paint and preparation method thereof

Abstract

The invention discloses a strong-alkali-resistant water-based industrial paint and a preparation method thereof, and relates to the technical field of paints. When the strong-alkali-resistant water-based industrial paint is prepared, polysiloxane and allyl glycidyl ether react to prepare epoxidized polysiloxane; the preparation method comprises the following steps: reacting a graphene nanosheet with glycidyl furfuryl ether and a phosphorus-containing furan monomer to prepare a pre-modified graphene nanosheet; the pre-modified graphene nanosheet and 2, 4-dihydroxy benzophenone are subjected to a reaction, and a modified graphene nanosheet is prepared; the preparation method comprises the following steps: reacting bisphenol AF with epoxy chloropropane to prepare a fluorine-containing epoxy monomer; the preparation method comprises the following steps: emulsifying epoxy resin, a fluorine-containing epoxy monomer and epoxidized polysiloxane to prepare an epoxy resin emulsion; and uniformly mixing the epoxy resin emulsion, the modified graphene nanosheets and a curing agent to prepare the strong-alkali-resistant water-based industrial paint. The strong-alkali-resistant water-based industrial paint prepared by the invention has excellent strong alkali resistance, flame retardance and aging resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a strong alkali-resistant waterborne industrial paint and a preparation method thereof. BACKGROUND

[0002] Alkali-resistant paint is an industrial paint mainly used for the corrosion-resistant coating pretreatment of substrates such as walls, metals, and wood, which can resist the erosion of alkaline substances on the coating film and improve 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 ponds. The common components of alkali-resistant paint on the market are mainly epoxy resin, modified siloxane, and polyvinylidene fluoride, which provide basic chemical corrosion resistance. Some products add graphene and fluorine-containing elastomers to improve temperature resistance and mechanical strength. Waterborne epoxy resin paint dominates the alkali-resistant paint market due to its environmental protection (using water as the dispersion medium, the VOC content is much lower than the national standard), wide construction adaptability (can be applied to humid substrates such as basements and parking lots, has strong adhesion, and is compatible with various substrates such as steel, aluminum, galvanized steel, and cement). With the development of industry, ordinary waterborne epoxy resin paint cannot meet the more stringent strong alkali resistance requirements, and waterborne epoxy resin paint also has the problems of flammability and aging. Therefore, it is necessary to invent a strong alkali-resistant waterborne industrial paint with excellent comprehensive performance to meet market demand. SUMMARY

[0003] The present application relates to the field of coating technology, in particular to a strong alkali-resistant waterborne industrial paint and a preparation method thereof.

[0004] To solve the above technical problems, the present application provides the following technical solutions: A strong alkali-resistant waterborne industrial paint, which 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, and emulsifying epoxy resin, fluorine-containing epoxy monomer, and epoxidized polysiloxane to obtain an epoxy resin emulsion, and then uniformly mixing the epoxy resin emulsion, modified graphene nanosheets, and curing agent. The polysiloxane is prepared by hydrolysis and condensation of azobenzyldimethoxysilane and methyl dimethoxysilane, and end-capping with trimethylchlorosilane. The azobenzyldimethoxysilane is prepared by reacting 1-chloroethyl methyl dimethoxysilane and p-aminoazobenzene. The pre-modified graphene nanosheets are prepared by reacting graphene nanosheets with glycidyl furfuryl ether and phosphorus-containing furan monomer. The phosphorus-containing furan monomer is prepared by reacting 2-furfurylamine and tolyl phosphine chloride. The fluorine-containing epoxy monomer is prepared by reacting bisphenol AF and epichlorohydrin.

[0005] A preparation method of a strong-alkali-resistant waterborne industrial paint, comprising the following preparation steps: (1) uniformly mix polysiloxane, allyl glycidyl ether, chloroplatinic acid and toluene in a mass ratio of 1: (0.6-0.8): (0.02-0.03): (8-10), and then perform stirring reaction at 70-80 DEG C and 200-300 r / min for 3-4 h, remove toluene by rotary evaporation under reduced pressure, wash with anhydrous ethanol for 4 times, and dry at 50-60 DEG C under vacuum for 10-12 h to prepare epoxidized polysiloxane; (2) uniformly mix graphene nanosheets and N-methylpyrrolidone in a mass ratio of 1: (400-500), and then perform ultrasonic dispersion at 0-2 DEG C and 300 W for 1-2 h, add phosphorus-containing furan monomer with a mass 40-50 times that of the graphene nanosheets, add glycidyl furfuryl ether with a mass 30-40 times that of the graphene nanosheets, place in a high-pressure reaction kettle, and then perform stirring reaction at 100-106 DEG C and 300-400 r / min for 2-3 h, centrifugal, wash with acetone for 5 times, and dry at 50-60 DEG C under vacuum for 12-14 h to prepare pre-modified graphene nanosheets; uniformly mix the pre-modified graphene nanosheets, 2, 4-dihydroxybenzophenone, tetrabutylammonium bromide and toluene in a mass ratio of 1: (7-8): (0.2-0.3): (30-40), and then perform stirring reaction at 70-80 DEG C and 300-400 r / min for 4-5 h under nitrogen protection, centrifugal, wash with anhydrous ethanol for 4 times, and dry at 50-60 DEG C under vacuum for 8-10 h to prepare modified graphene nanosheets; (3) mix bisphenol AF and epichlorohydrin in a molar ratio of 1: (8-10), add tetraethylammonium chloride with a mass 0.03-0.05 times that of the bisphenol AF, perform stirring at 70 DEG C and 300-400 r / min for 55-65 min, cool to 60 DEG C, uniformly drop the 30% sodium hydroxide aqueous solution with a mass 4-5 times that of the bisphenol AF within 10 min, perform stirring reaction at 68-72 DEG C for 100-120 min, remove the unreacted epichlorohydrin by rotary evaporation under reduced pressure, cool to 60 DEG C, add benzene with a mass 7-8 times that of the bisphenol AF, add the 30% sodium hydroxide aqueous solution with a mass 2-3 times that of the bisphenol AF, continue stirring reaction for 2-3 h, cool to room temperature, wash with hot water with a temperature of 70-80 DEG C for 3 times, and dry at 60-70 DEG C under vacuum for 10-12 h to prepare the fluorine-containing epoxy monomer; (4) by mass fraction, take epoxy resin 24~26 parts, fluorine-containing epoxy monomer 18~20 parts, epoxidized polysiloxane 7~8 parts, modified graphene nanosheet 1.8~2 parts, curing agent 9~10 parts, 3~4 parts Span-60, 4~5 parts polysorbate-20; the epoxy resin, fluorine-containing epoxy monomer, epoxidized polysiloxane, Span-60, polysorbate-20 is mixed uniformly, under the condition of 64~66℃, 600~700r / min stirring, distilled water is added from constant pressure separatory funnel, the drop rate of distilled water is 6~8ml / min, and the conductivity of the reaction system is monitored by conductivity meter, when the conductivity of the reaction system jumps, stop the reaction, cool to room temperature, and discharge, to prepare epoxy resin emulsion; the epoxy resin emulsion, modified graphene nanosheet, curing agent is mixed uniformly, the viscosity is adjusted to 70~80KU with distilled water, stirred at 1600~2000r / min for 30~40min, to prepare strong alkali resistant water-based industrial paint.

[0006] As optimization, the preparation method of the polysiloxane in step (1) is as follows: azobenzene dimethoxysilane, methyl dimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, toluene are mixed uniformly in a mass ratio of: 1: (1.4~1.6): (0.7~0.8): (0.01~0.02): (13~14), stirred at 78~82℃, 300~400r / min for 4~5h, 0.1~0.2 times the mass of methyl dimethoxysilane of trimethylchlorosilane is added, heated to 96~100℃, continue to stir for 2~3h, washed with deionized water for 3 times, dried at 70~80℃ under vacuum for 8~10h, to prepare polysiloxane; the reaction mechanism is as follows: .

[0007] As optimization, the preparation method of the azobenzene dimethoxysilane is as follows: 1-chloroethyl methyl dimethoxysilane, p-aminoazobenzene are added to 1-chloroethyl methyl dimethoxysilane 8~10 times of anhydrous ethanol, 0.04~0.05 times the mass of 1-chloroethyl methyl dimethoxysilane of triethylamine is added, stirred at 60~70℃, 300~400r / min for 3~4h, dried at 60~70℃ under vacuum for 10~12h, to prepare azobenzene dimethoxysilane; the reaction mechanism is as follows: .

[0008] As optimization, the preparation method of the phosphorus-containing furan monomer in step (2) is as follows: 2-furfurylamine and tolyl phosphine chloride are added into anhydrous ethanol in a molar ratio of 1:1, the mass of 2-furfurylamine is 9-11 times, the mass of triethylamine is 0.05-0.06 times that of 2-furfurylamine, stirring is carried out at 60-70 DEG C and 300-400 r / min for 2-3 h, and drying is carried out at 50-60 DEG C under vacuum for 12-14 h to obtain the phosphorus-containing furan monomer; the reaction mechanism is as follows: .

[0009] As optimization, the diameter of the graphene nanosheet in step (2) is 5-10 mu m, and the thickness is 4-20 nm, which is purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.

[0010] As optimization, the reaction mechanism of the fluorine-containing epoxy monomer in step (3) is as follows: .

[0011] As optimization, the type of the epoxy resin in step (4) is E44.

[0012] As optimization, the curing agent in step (4) is a water-based epoxy curing agent, and the type is CYDHD-280.

[0013] Compared with the prior art, the present application has the following beneficial effects: In the preparation of the strong-alkali-resistant water-based industrial paint, firstly, azobenzene dimethoxysilane is prepared by reacting 1-chloroethyl methyl dimethoxysilane and p-aminoazobenzene; polysiloxane is prepared by hydrolytic condensation of azobenzene dimethoxysilane and methyl dimethoxysilane and end-capping with trimethylchlorosilane; azobenzene structure and Si-H bond are introduced into the side chain of the polysiloxane; the Si-H bond reacts with the carbon-carbon double bond on the allyl glycidyl ether to introduce 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 performance of the strong-alkali-resistant water-based industrial paint, and the azobenzene structure on the side chain can change from cis to trans under the action of ultraviolet light, thereby converting the ultraviolet light energy into chemical energy, and improving the anti-aging performance of the strong-alkali-resistant water-based industrial paint, and the principle is as follows: .

[0014] Secondly, 2-furfurylamine and tolyl phosphine chloride are reacted to obtain a phosphorus-containing furan monomer; the graphene nanosheet is reacted with glycidyl furfuryl ether and the phosphorus-containing furan monomer to obtain a pre-modified graphene nanosheet; the furan groups on the glycidyl furfuryl ether and the phosphorus-containing furan monomer are subjected to Diels-Alder reaction with the surface of the graphene nanosheet to introduce phosphorus elements and epoxy groups onto the surface of the graphene nanosheet; the introduction of the phosphorus elements can further improve the flame retardation of the strong-alkali-resistant waterborne industrial paint; the epoxy groups are reacted with 2,4-dihydroxybenzophenone to obtain a modified graphene nanosheet, and a 2-hydroxybenzophenone structure is introduced onto the modified graphene nanosheet; the 2-hydroxybenzophenone structure forms intramolecular hydrogen bonds through the ortho-hydroxyl group and the carbonyl oxygen atom to form a chelate ring structure; when ultraviolet light is irradiated, the hydrogen bonds are broken due to the energy absorption of the molecule, the chelate ring is opened, and the energy absorbed by the ultraviolet light is converted into heat energy through molecular thermal vibration and released, further improving the anti-aging performance of the strong-alkali-resistant waterborne industrial paint; in addition, the two-dimensional sheet structure of the graphene nanosheet can form a physical barrier in the industrial paint, making the diffusion process of the corrosion medium more tortuous and slow, effectively blocking the penetration of the corrosion medium, forming a dense protective layer, and improving the strong-alkali resistance of the strong-alkali-resistant waterborne industrial paint.

[0015] Finally, bisphenol AF and epichlorohydrin are reacted to obtain a fluorine-containing epoxy monomer; the fluorine-containing epoxy monomer participates in the curing of the industrial paint to introduce fluorine atoms into the paint film; the fluorine atom has strong electronegativity and low surface energy, improves the hydrophobic and oleophobic properties of the strong-alkali-resistant waterborne industrial paint, is inert to the corrosion medium, and further improves the strong-alkali resistance of the material. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0017] In the following examples and comparative examples, the type of the epoxy resin used is E44; the type of the curing agent used is CYDHD-280; the diameter of the graphene nanosheet used is 5-10 μm, and the thickness is 4-20 nm, which is purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.; the HLB of Span-60 used is 4.7; and the HLB of polysorbate-20 used is 16.7.

[0018] Example 1: A preparation method of a strong-alkali-resistant waterborne industrial paint, the preparation method of the strong-alkali-resistant waterborne industrial paint comprising the following preparation steps: (1) 1-chloroethyl methyl dimethoxysilane, p-aminoazobenzene were added to 1-chloroethyl methyl dimethoxysilane 8 times of anhydrous ethanol in mass ratio of 1:1, 1-chloroethyl methyl dimethoxysilane 0.04 times of triethylamine was added, 60℃, 300r / min stirring reaction for 4h, under vacuum condition, 60℃ drying for 12h, azobenzene dimethoxysilane was prepared; azobenzene dimethoxysilane, methyl dimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, toluene were mixed uniformly in mass ratio of 1:1.4:0.7:0.01:13, 78℃, 300r / min stirring reaction for 5h, methyl dimethoxysilane 0.1 times of trimethylchlorosilane was added, the temperature was raised to 96℃, continue to stir for 3h, washed with deionized water for 3 times, under vacuum condition, 70℃ drying for 10h, polysiloxane was prepared; polysiloxane, allyl glycidyl ether, chloroplatinic acid, toluene were mixed uniformly in mass ratio of 1:0.6:0.02:8, 70℃, 200r / min stirring reaction for 4h, toluene was removed by rotary evaporation under reduced pressure, washed with anhydrous ethanol for 4 times, under vacuum condition, 50℃ drying for 12h, epoxidized polysiloxane was prepared; (2) 2-furan methylamine, tolyl phosphine chloride were added to 2-furan methylamine 9 times of anhydrous ethanol in mass ratio of 1:1, 2-furan methylamine 0.05 times of triethylamine was added, 60℃, 300r / min stirring reaction for 3h, under vacuum condition, 50℃ drying for 14h, phosphorus-containing furan monomer was prepared; graphene nanosheet, N-methyl pyrrolidone were mixed uniformly in mass ratio of 1:400, 0℃, 300W ultrasonic dispersion for 1h, graphene nanosheet 40 times of phosphorus-containing furan monomer was added, graphene nanosheet 30 times of glycidyl furfuryl ether was added, placed in a high-pressure reaction kettle, 100℃, 300r / min stirring reaction for 3h, centrifuged, washed with acetone for 5 times, under vacuum condition, 50℃ drying for 14h, pre-modified graphene nanosheet was prepared; pre-modified graphene nanosheet, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide, toluene were mixed uniformly in mass ratio of 1:7:0.2:30, 70℃, 300r / min stirring reaction for 5h under nitrogen protection, centrifuged, washed with anhydrous ethanol for 4 times, under vacuum condition, 50℃ drying for 10h, modified graphene nanosheet was prepared; (3) Mix bisphenol AF and epichlorohydrin in a molar ratio of 1:8, add tetraethylammonium chloride (0.03 times the mass of bisphenol AF), stir at 70°C, 300 r / min for 55 min, cool to 60°C, uniformly add 30% sodium hydroxide aqueous solution (4 times the mass of bisphenol AF) dropwise over 10 min, stir at 68°C for 100 min, remove unreacted epichlorohydrin by vacuum evaporation, cool to 60°C, add benzene (7 times the mass of bisphenol AF), add 30% sodium hydroxide aqueous solution (2 times the mass of bisphenol AF), continue stirring and reacting for 2 h, cool to room temperature, wash with hot water at 70°C for 3 times, and dry at 60°C for 12 h under vacuum conditions to obtain a fluorine-containing epoxy monomer; (4) According to the mass ratio, 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 were weighed; the epoxy resin, fluorinated epoxy monomer, epoxidized polysiloxane, Span-60, and polysorbate-20 were mixed evenly, and distilled water was added dropwise from a constant pressure separatory funnel at 64°C and 600 r / min under stirring conditions. The dropping rate of distilled water was 6 ml / min, and the conductivity of the reaction system was monitored by a conductivity meter. When the conductivity of the reaction system jumped, the reaction was stopped, and the material was discharged after cooling to room temperature 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 70KU with distilled water. The paint was stirred at 1600 r / min for 40 minutes to obtain a strong alkali resistant water-based industrial paint.

[0019] Example 2: A method for preparing a strong alkali-resistant water-based industrial paint, the method comprising the following steps: (1) 1-chloroethyl methyl dimethoxysilane, p-aminoazobenzene were added to 1-chloroethyl methyl dimethoxysilane 9 times of anhydrous ethanol in mass ratio of 1:1, 1-chloroethyl methyl dimethoxysilane 0.045 times of triethylamine in mass ratio was added, 65℃, 350r / min stirring reaction 3.5h, under vacuum condition, 65℃ drying 11h, azobenzene dimethoxysilane was prepared; azobenzene dimethoxysilane, methyl dimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, toluene were mixed uniformly in mass ratio of 1:1.5:0.75:0.015:13.5, 80℃, 350r / min stirring reaction 4.5h, methyl dimethoxysilane 0.15 times of trimethylchlorosilane in mass ratio was added, heated to 98℃, continue to stir for 2.5h, washed with deionized water 3 times, under vacuum condition, 75℃ drying 9h, polysiloxane was prepared; polysiloxane, allyl glycidyl ether, chloroplatinic acid, toluene were mixed uniformly in mass ratio of 1:0.7:0.025:9, 75℃, 250r / min stirring reaction 3.5h, toluene was removed by rotary evaporation under reduced pressure, washed with anhydrous ethanol 4 times, under vacuum condition, 55℃ drying 11h, epoxidized polysiloxane was prepared; (2) 2-furan methylamine, tolyl phosphine chloride were added to 2-furan methylamine 10 times of anhydrous ethanol in mass ratio of 1:1, 2-furan methylamine 0.055 times of triethylamine in mass ratio was added, 65℃, 350r / min stirring reaction 2.5h, under vacuum condition, 55℃ drying 13h, phosphorus-containing furan monomer was prepared; graphene nanosheet, N-methyl pyrrolidone were mixed uniformly in mass ratio of 1:450, 1℃, 300W ultrasonic dispersion 1.5h, phosphorus-containing furan monomer 45 times of graphene nanosheet in mass ratio was added, glycidyl furfuryl ether 35 times of graphene nanosheet in mass ratio was added, placed in a high-pressure reaction kettle, 103℃, 350r / min stirring reaction 2.5h, centrifugation, washed with acetone 5 times, under vacuum condition, 55℃ drying 13h, pre-modified graphene nanosheet was prepared; pre-modified graphene nanosheet, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide, toluene were mixed uniformly in mass ratio of 1:7.5:0.25:35, 75℃, 350r / min stirring reaction 4.5h under nitrogen protection, centrifugation, washed with anhydrous ethanol 4 times, under vacuum condition, 55℃ drying 9h, modified graphene nanosheet was prepared; (3) Bisphenol AF, epoxy chloropropane were mixed according to the molar ratio of 1:9, tetraethylammonium chloride was added in an amount of 0.04 times the mass of bisphenol AF, and stirred at 70°C and 350 r / min for 60 min. The temperature was reduced to 60°C, and sodium hydroxide aqueous solution with a mass fraction of 30% was added at a uniform speed within 10 min, in an amount of 4.5 times the mass of bisphenol AF. The reaction was stirred at 70°C for 110 min, and unreacted epoxy chloropropane was removed by rotary evaporation under reduced pressure. The temperature was reduced to 60°C, and benzene was added in an amount of 7.5 times the mass of bisphenol AF. Sodium hydroxide aqueous solution with a mass fraction of 30% was added in an amount of 2.5 times the mass of bisphenol AF, and the reaction was continued to stir for 2.5 h. The temperature was cooled to room temperature, and hot water with a temperature of 75°C was used for washing 3 times. The product was dried at 65°C under vacuum for 11 h to obtain a fluorine-containing epoxy monomer; (4) According to the mass fraction, 25 parts of epoxy resin, 19 parts of fluorine-containing epoxy monomer, 7.5 parts of epoxidized polysiloxane, 1.9 parts of modified graphene nanosheet, 9.5 parts of curing agent, 3.5 parts of Span-60, and 4.5 parts of polysorbate-20 were weighed. The epoxy resin, fluorine-containing epoxy monomer, epoxidized polysiloxane, Span-60, and polysorbate-20 were mixed uniformly, and distilled water was added from a constant-pressure separatory funnel under the condition of stirring at 65°C and 650 r / min. The addition rate of distilled water was 7 ml / min, and the conductivity of the reaction system was monitored by a conductivity meter. When the conductivity of the reaction system jumped, the reaction was stopped. After cooling to room temperature, the product was discharged to obtain an epoxy resin emulsion. The epoxy resin emulsion, modified graphene nanosheet, and curing agent were mixed uniformly, and the viscosity was adjusted to 75 KU with distilled water. The product was stirred at 1800 r / min for 35 min to obtain a strong alkali-resistant water-based industrial paint.

[0020] Example 3: A preparation method of a strong alkali-resistant water-based industrial paint, the preparation method of the strong alkali-resistant water-based industrial paint comprising the following preparation steps: (1) 1-chloroethyl methyl dimethoxysilane, p-amino azobenzene were added to 1-chloroethyl methyl dimethoxysilane 10 times of anhydrous ethanol in mass ratio of 1:1, 1-chloroethyl methyl dimethoxysilane 0.05 times of triethylamine in mass ratio was added, 70℃, 400r / min stirring reaction 3h, 70℃, 10h drying under vacuum condition, azobenzene dimethoxysilane was prepared; azobenzene dimethoxysilane, methyl dimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, toluene were mixed uniformly in mass ratio of 1:1.6:0.8:0.02:14, 82℃, 400r / min stirring reaction 4h, methyl dimethoxysilane 0.2 times of trimethylchlorosilane in mass ratio was added, heated to 100℃, continue to stir for 2h, washed with deionized water 3 times, 80℃, 8h drying under vacuum condition, polysiloxane was prepared; polysiloxane, allyl glycidyl ether, chloroplatinic acid, toluene were mixed uniformly in mass ratio of 1:0.8:0.03:10, 80℃, 300r / min stirring reaction 3h, toluene was removed by rotary evaporation under reduced pressure, washed with anhydrous ethanol 4 times, 60℃, 10h drying under vacuum condition, epoxidized polysiloxane was prepared; (2) 2-furan methylamine, tolyl phosphine chloride were added to 2-furan methylamine 11 times of anhydrous ethanol in mass ratio of 1:1, 2-furan methylamine 0.06 times of triethylamine in mass ratio was added, 70℃, 400r / min stirring reaction 2h, 60℃, 12h drying under vacuum condition, phosphorus-containing furan monomer was prepared; graphene nanosheet, N-methyl pyrrolidone were mixed uniformly in mass ratio of 1:500, 2℃, 300W ultrasonic dispersion 2h, graphene nanosheet 50 times of phosphorus-containing furan monomer in mass ratio was added, graphene nanosheet 40 times of glycidyl furfuryl ether in mass ratio was added, placed in a high-pressure reaction kettle, 106℃, 400r / min stirring reaction 2h, centrifuged, washed with acetone 5 times, 60℃, 12h drying under vacuum condition, pre-modified graphene nanosheet was prepared; pre-modified graphene nanosheet, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide, toluene were mixed uniformly in mass ratio of 1:8:0.3:40, 80℃, 400r / min stirring reaction 4h under nitrogen protection, centrifuged, washed with anhydrous ethanol 4 times, 60℃, 8h drying under vacuum condition, modified graphene nanosheet was prepared; (3) mixed bisphenol AF and epichlorohydrin according to a molar ratio of 1:10, added tetraethylammonium chloride with a mass of 0.05 times the mass of bisphenol AF, stirred at 70°C and 400 r / min for 65 min, cooled to 60°C, added sodium hydroxide aqueous solution with a mass fraction of 30% at a speed of 5 times the mass of bisphenol AF within 10 min, stirred at 72°C for 100 min, removed unreacted epichlorohydrin by rotary evaporation under reduced pressure, cooled to 60°C, added benzene with a mass of 8 times the mass of bisphenol AF, added sodium hydroxide aqueous solution with a mass fraction of 30% with a mass of 3 times the mass of bisphenol AF, continued to stir for 3 h, cooled to room temperature, washed with hot water at 80°C for 3 times, dried at 70°C under vacuum for 10 h, and prepared a fluorine-containing epoxy monomer; (4) mixed epoxy resin 26 parts, fluorine-containing epoxy monomer 20 parts, epoxidized polysiloxane 8 parts, modified graphene nanosheet 2 parts, curing agent 10 parts, 4 parts Span-60, and 5 parts polysorbate-20 according to mass fractions, mixed the epoxy resin, fluorine-containing epoxy monomer, epoxidized polysiloxane, Span-60, and polysorbate-20 uniformly, added distilled water from a constant-pressure separatory funnel under stirring at 66°C and 700 r / min, the addition rate of the distilled water was 8 ml / min, and the conductivity of the reaction system was monitored by using a conductivity meter, the reaction was stopped when the conductivity of the reaction system jumped, the material was discharged after cooling to room temperature, and an epoxy resin emulsion was prepared; mixed the epoxy resin emulsion, modified graphene nanosheet, and curing agent uniformly, adjusted the viscosity to 80 KU by using distilled water, stirred at 2000 r / min for 30 min, and prepared a strong-alkali-resistant waterborne industrial paint.

[0021] Comparative Example 1 The preparation method of the strong-alkali-resistant waterborne industrial paint of Comparative Example 1 is different from that of Example 2 in that step (1) is modified as follows: mixed dimethyldimethoxysilane, methyl dimethoxysilane, deionized water, anhydrous tetramethylammonium hydroxide, and toluene according to a mass ratio of 1:1.5:0.75:0.015:13.5, stirred at 80°C and 350 r / min for 4.5 h, added trimethylchlorosilane with a mass of 0.15 times the mass of methyl dimethoxysilane, increased the temperature to 98°C, and continued to stir for 2.5 h, washed with deionized water for 3 times, dried at 75°C under vacuum for 9 h, and prepared polysiloxane; mixed the polysiloxane, allyl glycidyl ether, chloroplatinic acid, and toluene according to a mass ratio of 1:0.7:0.025:9, stirred at 75°C and 250 r / min for 3.5 h, removed toluene by rotary evaporation under reduced pressure, washed with anhydrous ethanol for 4 times, dried at 55°C under vacuum for 11 h, and prepared epoxidized polysiloxane. The remaining steps are the same as those of Example 2.

[0022] Comparative Example 2 The preparation method of the strong alkali-resistant waterborne industrial paint of Comparative Example 2 is different from that of Example 2 in that step (1) is not performed, and step (4) is modified as follows: 32.5 parts of epoxy resin, 19 parts of fluorine-containing epoxy monomer, 1.9 parts of modified graphene nanosheet, 9.5 parts of curing agent, 3.5 parts of Span-60, and 4.5 parts of polysorbate-20 are weighed by mass fraction; the epoxy resin, fluorine-containing epoxy monomer, Span-60, and polysorbate-20 are uniformly mixed, and distilled water is added dropwise from a constant-pressure separatory funnel under the condition of 65°C and 650 r / min stirring, the dropwise rate of the distilled water is 7 ml / min, and the conductivity of the reaction system is monitored by using a conductivity meter; when the conductivity of the reaction system jumps, the reaction is stopped, and the material is discharged after cooling to room temperature, to obtain an epoxy resin emulsion; the epoxy resin emulsion, modified graphene nanosheet, and curing agent are uniformly mixed, the viscosity is adjusted to 75 KU by using distilled water, and stirring is performed at 1800 r / min for 35 min, to obtain the strong alkali-resistant waterborne industrial paint. The remaining steps are the same as those of Example 2.

[0023] Comparative Example 3: The preparation method of the strong alkali-resistant waterborne industrial paint of Comparative Example 3 is different from that of Example 2 only in step (2), and step (2) is modified as follows: the graphene nanosheet and N-methyl pyrrolidone are uniformly mixed in a mass ratio of 1:450, ultrasonic dispersion is performed at 1°C and 300 W for 1.5 h, glycidyl furfuryl ether with a mass of 35 times that of the graphene nanosheet is added, the mixture is placed in a high-pressure reaction kettle, and reaction is performed at 103°C and 350 r / min stirring for 2.5 h; centrifugation is performed, washing is performed with acetone for 5 times, and drying is performed under vacuum at 55°C for 13 h, to obtain pre-modified graphene nanosheet; the pre-modified graphene nanosheet, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide, and toluene are uniformly mixed in a mass ratio of 1:7.5:0.25:35, reaction is performed under nitrogen protection at 75°C and 350 r / min stirring for 4.5 h, centrifugation is performed, washing is performed with anhydrous ethanol for 4 times, and drying is performed under vacuum at 55°C for 9 h, to obtain modified graphene nanosheet. The remaining steps are the same as those of Example 2.

[0024] Comparative Example 4: The preparation method of the strong alkali resistant waterborne industrial paint of Comparative Example 4 is different from that of Example 2 only in step (2), which is modified as follows: 2-furfurylamine and tolyl phosphine chloride are added to 10 times the mass of 2-furfurylamine of anhydrous ethanol at a molar ratio of 1:1, 0.055 times the mass of 2-furfurylamine of triethylamine is added, and the mixture is stirred at 65°C and 350 r / min for 2.5 h, dried at 55°C under vacuum for 13 h, and the phosphorus-containing furan monomer is prepared; graphene nanosheets and N-methylpyrrolidone are uniformly mixed at a mass ratio of 1:450, ultrasonically dispersed at 1°C and 300 W for 1.5 h, 45 times the mass of graphene nanosheets of the phosphorus-containing furan monomer is added, 35 times the mass of graphene nanosheets of glycidyl furfuryl ether is added, and the mixture is placed in a high-pressure reaction kettle, stirred at 103°C and 350 r / min for 2.5 h, centrifuged, washed with acetone 5 times, and dried at 55°C under vacuum for 13 h to obtain the modified graphene nanosheets. The remaining steps are the same as those of Example 2.

[0025] Comparative Example 5 The preparation method of the strong alkali resistant waterborne industrial paint of Comparative Example 5 is different from that of Example 2 only in that step (2) is not performed, and step (4) is modified as follows: 25 parts of epoxy resin, 19 parts of fluorine-containing 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 are uniformly mixed, and the mixture is stirred at 65°C and 650 r / min, and distilled water is added from a constant-pressure separatory funnel at a rate of 7 ml / min, and the conductivity of the reaction system is monitored with a conductivity meter, and the reaction is stopped when the conductivity of the reaction system jumps, and the mixture is cooled to room temperature and discharged to obtain an epoxy resin emulsion; the epoxy resin emulsion and the curing agent are uniformly mixed, the viscosity is adjusted to 75 KU with distilled water, and the mixture is stirred at 1800 r / min for 35 min to obtain the strong alkali resistant waterborne industrial paint. The remaining steps are the same as those of Example 2.

[0026] Comparative Example 6 The preparation method of the strong-alkali-resistant waterborne industrial paint of Comparative Example 6 is only different from that of Example 2 in that step (3) is not performed, and step (4) is modified as follows: 44 parts by mass of the epoxy resin, 7.5 parts by mass of the epoxidized polysiloxane, 1.9 parts by mass of the modified graphene nanosheet, 9.5 parts by mass of the curing agent, 3.5 parts by mass of Span-60, and 4.5 parts by mass of polysorbate-20 are weighed; the epoxy resin, the epoxidized polysiloxane, Span-60, and polysorbate-20 are uniformly mixed, and distilled water is added dropwise from a constant-pressure separatory funnel under the condition of stirring at 65°C and 650 r / min, the dropwise adding rate of the distilled water is 7 ml / min, and the conductivity of the reaction system is monitored by using a conductivity meter; when the conductivity of the reaction system jumps, the reaction is stopped, and the epoxy resin emulsion is obtained after cooling to room temperature; the epoxy resin emulsion, the modified graphene nanosheet, and the curing agent are uniformly mixed, the viscosity is adjusted to 75 KU by using distilled water, and the mixture is stirred at 1800 r / min for 35 min, to obtain the strong-alkali-resistant waterborne industrial paint. The remaining steps are the same as those of Example 2.

[0027] Test Example 1 Test of strong-alkali resistance Test method: The strong-alkali-resistant waterborne industrial paints prepared in the examples and comparative examples are coated on tinplate with a size of 50x100x0.5 mm, dried at 100°C for 3 h, cooled to 80°C and dried for 5 h, and then placed at room temperature for 12 h, to obtain test pieces; the test pieces (2 / 3 of the total area) are immersed in a 50% by mass sodium hydroxide aqueous solution, and placed at room temperature for 24 h; the test pieces are washed with deionized water, then dried with filter paper, and immediately observed for phenomena such as blistering, cracking, softening, powdering, and peeling, to determine the corrosion resistance of the paint film; level 1: no change in the surface of the paint film, and level 2: phenomena such as blistering, cracking, softening, powdering, and peeling occur on the surface of the paint film. The results are shown in Table 1.

[0028] Table 1 ; As can be seen from the experimental data of Examples 1-3 and Comparative Examples 1-6 in Table 1, the strong-alkali-resistant waterborne industrial paint prepared in the present application has good strong-alkali resistance.

[0029] By comparison, the strong-alkali resistance of Examples 1-3 is better than that of Comparative Example 5, which indicates that the two-dimensional sheet structure of the graphene nanosheet can form a physical barrier in the industrial paint, making the diffusion process of the corrosion medium more tortuous and slow, effectively blocking the penetration of the corrosion medium, forming a dense protective layer, and improving the strong-alkali resistance of the strong-alkali-resistant waterborne industrial paint.

[0030] By comparison, the strong alkali resistance performance of examples 1-3 is better than that of comparative example 6, which indicates that the fluorine-containing epoxy monomer is prepared by reacting bisphenol AF and epichlorohydrin; the fluorine-containing epoxy monomer participates in the curing of the industrial paint, introduces fluorine atoms into the paint film, the fluorine atoms have strong electronegativity and low surface energy, improve the hydrophobic and oleophobic properties of the strong alkali-resistant water-based industrial paint, are inert to corrosive media, and further improve the strong alkali resistance of the material.

[0031] Test example 2 Test of anti-aging performance Test method: pour the examples and comparative examples into a polytetrafluoroethylene mold, dry at 100℃ for 3h, cool to 80℃ and dry for 5h, stand at room temperature for 12h, cut the cured sample into a standard sample according to GB / T1040.1, test the tensile strength P of the standard sample with a tensile testing machine, irradiate the standard sample with a xenon arc lamp for 7 days, the irradiation intensity is 0.51W / m 2 (340nm), obtain an aged sample; test the tensile strength Q of the aged sample with a tensile testing machine, calculate the performance decline rate before and after aging of the standard sample; performance decline rate=(P-Q) / P×100%. The results are shown in Table 2.

[0032] Table 2 ; From the experimental data comparison of examples 1-3 and comparative examples 1-6 in Table 2, it can be found that the strong alkali-resistant water-based industrial paint prepared by the present application has good anti-aging performance.

[0033] By comparison, the performance decline rate of examples 1-3 is less than that of comparative examples 1-2, which indicates that azobenzene-based dimethoxysilane is prepared by reacting 1-chloroethyl methyl dimethoxysilane and p-aminoazobenzene; polysiloxane is prepared by hydrolysis and condensation of azobenzene-based dimethoxysilane and methyl dimethoxysilane and end-capping with trimethylchlorosilane; the azobenzene structure is introduced into the side chain of the polysiloxane; the azobenzene structure on the side chain will undergo cis-trans isomerization under the action of ultraviolet light, converting the ultraviolet light energy into chemical energy, thereby improving the anti-aging performance of the strong alkali-resistant water-based industrial paint.

[0034] By comparison, the performance degradation rate of examples 1-3 is less than that of comparative examples 4-5, which indicates that the pre-modified graphene nanosheet is prepared by reacting graphene nanosheet with glycidyl furfuryl ether and phosphorus-containing furan monomer; the furan groups on glycidyl furfuryl ether and phosphorus-containing furan monomer perform Diels-Alder reaction with the surface of graphene nanosheet to introduce epoxy groups on the surface of graphene nanosheet; the epoxy groups react with 2,4-dihydroxybenzophenone to prepare modified graphene nanosheet, which introduces 2-hydroxybenzophenone structure on the modified graphene nanosheet; the 2-hydroxybenzophenone structure forms intramolecular hydrogen bond through ortho-hydroxyl and carbonyl oxygen atom to form chelate ring structure; when irradiated by ultraviolet light, the hydrogen bond is broken due to the energy absorption of the molecule, the chelate ring is opened, and the energy absorbed by ultraviolet light is converted into heat energy through molecular thermal vibration and released, which further improves the anti-aging performance of the strong alkali-resistant water-based industrial paint.

[0035] Test Example 3 Test of Flame Retardant Performance Test Method: Pour the examples and comparative examples into a polytetrafluoroethylene mold, dry at 100℃ for 3h, cool to 80℃ and dry for 5h, stand at room temperature for 12h, cut the cured sample into standard sample bars according to GB / T2406.2, and test the limiting oxygen index of the standard sample bars. The results are shown in Table 3.

[0036] Table 3 ; From the experimental data comparison of examples 1-3 and comparative examples 1-6 in Table 3, it can be found that the strong alkali-resistant water-based industrial paint prepared by the present application has good flame retardant performance.

[0037] By comparison, the limiting oxygen index of examples 1-3 is greater than that of comparative example 2, which indicates that the polysiloxane is prepared by hydrolysis and condensation of azobenzene dimethoxysilane and methyl dimethoxysilane and end-capping with trimethylchlorosilane; the siloxane structure can improve the flame retardant performance of the strong alkali-resistant water-based industrial paint.

[0038] By comparison, the limiting oxygen index of examples 1-3 is greater than that of comparative examples 3 and 5, which indicates that the phosphorus-containing furan monomer is prepared by reacting 2-furfurylamine and tolyl phosphine chloride; the pre-modified graphene nanosheet is prepared by reacting graphene nanosheet with glycidyl furfuryl ether and phosphorus-containing furan monomer; the furan groups on glycidyl furfuryl ether and phosphorus-containing furan monomer perform Diels-Alder reaction with the surface of graphene nanosheet to introduce phosphorus element on the surface of graphene nanosheet, and the introduction of phosphorus element can further improve the flame retardant performance of the strong alkali-resistant water-based industrial paint.

[0039] The above detailed description of the specific embodiments of the present application has been given to understand the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A strong alkali resistant water-based industrial paint, characterized in that: The strong 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 the epoxy resin emulsion, modified graphene nanosheets, and a curing agent. The polysiloxane is prepared by hydrolyzing and condensing azophenyldimethoxysilane and methyldimethoxysilane and capping with trimethylchlorosilane; The azophenyldimethoxysilane is prepared by reacting 1-chloroethylmethyldimethoxysilane and p-aminoazobenzene; The pre-modified graphene nanosheets are prepared by reacting graphene nanosheets with glycidyl furfuryl ether and phosphorus-containing furan monomers; The phosphorus-containing furan monomer is prepared by reacting 2-furylmethylamine and tolylphosphine chloride; The fluorine-containing epoxy monomer is prepared by reacting bisphenol AF and epichlorohydrin.

2. A method for preparing a strong alkali resistant water-based industrial paint, characterized in that: The preparation method of the strong alkali resistant water-based industrial paint comprises the following preparation steps: (1) Polysiloxane, allyl glycidyl ether, chloroplatinic acid and toluene were mixed evenly, reacted at 70-80°C for 3-4 hours, and the toluene was removed by vacuum rotary evaporation, washed and vacuum dried to obtain epoxidized polysiloxane; (2) Pre-modified graphene nanosheets, 2,4-dihydroxybenzophenone, tetrabutylammonium bromide, and toluene were mixed uniformly, reacted at 70-80°C for 4-5 hours under nitrogen protection, centrifuged, washed, and dried to obtain modified graphene nanosheets; (3) Mix bisphenol AF and epichlorohydrin, add tetraethylammonium chloride, stir at 70°C for 55-65 minutes, cool to 60°C, add sodium hydroxide aqueous solution dropwise, stir and react at 68-72°C for 100-120 minutes, remove unreacted epichlorohydrin by vacuum rotary evaporation, cool to 60°C, add benzene and sodium hydroxide aqueous solution, continue stirring and reacting for 2-3 hours, cool to room temperature, wash with hot water, and vacuum dry to obtain a fluorine-containing epoxy monomer; (4) Epoxy resin, fluorinated epoxy monomer, epoxidized polysiloxane, Span-60 and polysorbate-20 were mixed evenly, and distilled water was added dropwise from a constant pressure separatory funnel at 64-66°C and 600-700 r / min, and the conductivity of the reaction system was monitored with a conductivity meter. When the conductivity of the reaction system jumped, the reaction was stopped, and the material was discharged after cooling to room temperature to obtain epoxy resin emulsion; 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 paint was stirred at 1600-2000 r / min for 30-40 minutes to obtain a 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 uniformly mixed, stirred and reacted at 78-82° C. for 4-5 hours, trimethylchlorosilane is added, the temperature is raised to 96-100° C., the reaction is continued for 2-3 hours, washed, and dried to obtain polysiloxane.

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 comprises the following steps: adding 1-chloroethylmethyldimethoxysilane and p-aminoazobenzene to anhydrous ethanol, adding triethylamine, reacting at 60-70° C. for 3-4 hours, and vacuum drying to obtain the 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 uniformly mixed, ultrasonically dispersed for 1-2 hours, phosphorus-containing furan monomer and glycidyl furfuryl ether are added, placed in a high-pressure reactor, reacted at 100-106° C. for 2-3 hours, centrifuged, washed, and vacuum-dried to obtain pre-modified graphene nanosheets.

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 comprises the following steps: adding 2-furylmethylamine and tolylphosphonium chloride into anhydrous ethanol, adding triethylamine, reacting at 60-70° C. for 2-3 hours, and vacuum drying 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 to 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 mass fraction of the sodium hydroxide aqueous solution in step (3) is 30%.

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

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