Acid and alkali resistant and salt spray resistant coating and preparation method thereof

Abstract

The invention discloses an acid and alkali resistant and salt spray resistant coating and a preparation method thereof, and relates to the field of coatings. When the acid and alkali resistant and salt fog resistant coating is prepared, 4-imidazole formaldehyde reacts with 3-aminopropyldimethoxymethylsilane and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and then reacts with hexamethyldisiloxane, octamethylcyclotetrasiloxane and 2, 4, 6, 8-tetramethylcyclotetrasiloxane to prepare modified polysiloxane; the preparation method comprises the following steps: reacting graphene oxide with 3-aminoethyl thiophene, 3-hexylthiophene and 3-allyl thiophene to prepare modified graphene; the preparation method comprises the following steps: uniformly mixing modified graphene, 1, 3-divinyl-1, 1, 3, 3-tetramethyldisiloxane platinum, a defoaming agent and modified polysiloxane to obtain a component A, taking waterborne epoxy emulsion as a component B, and uniformly mixing the component A and the component B to obtain the acid-alkali-resistant salt-fog-resistant coating. The prepared acid-alkali-resistant salt-fog-resistant coating has good acid-alkali-resistant, salt-fog-resistant, flame-retardant and hydrophobic properties.

Description

Technical Field

[0001] The present invention relates to the field of coatings, and specifically to an acid and alkali resistant and salt spray resistant coating and a preparation method thereof. Background Art

[0002] With the development of modern economy, metal materials are widely used in daily life and national defense construction. In recent years, various aspects of processing of metal materials have improved their own properties, but metal materials are extremely prone to corrosion. In the application of metal materials in various fields, they are damaged by the corrosion media existing in the atmosphere, soil and seawater environments, which changes the nature of the metal itself. This phenomenon is usually called metal corrosion. The corrosion and damage of metal materials lead to the loss of functions, the failure of structures, and even environmental pollution, which not only affects the sustainable development of natural resources, but also brings many potential safety hazards to our daily life. This phenomenon is more likely to occur in places with harsher environments, such as offshore platforms, marine transportation, infrastructure construction, etc.

[0003] Nowadays, people use a variety of technologies including electrochemical protection, surface coating technology, manufacturing new alloys, etc. to prevent the occurrence of metal corrosion. Among them, coating an anti-corrosion coating on the metal surface is one of the most effective and commonly used methods. The coating provides good anti-corrosion effect on the metal by isolating the contact between the corrosion medium and the metal matrix. The acid and alkali resistant and salt spray resistant coating prepared by the present invention has good acid and alkali resistance, salt spray resistance, and also has good flame retardant and hydrophobic properties, and has broad market prospects. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of an acid and alkali resistant and salt spray resistant coating to solve the problems existing in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions: An acid and alkali resistant and salt spray resistant coating, wherein the acid and alkali resistant and salt spray resistant coating is prepared by reacting 4-imidazolecarboxaldehyde with 3-aminopropyldimethoxymethylsilane and then reacting with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to obtain a modified silane; reacting hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane with the modified silane to obtain a modified polysiloxane; reacting graphene oxide with 3-aminoethylthiophene and then reacting with 3-hexylthiophene and 3-allylthiophene to obtain a modified graphene; mixing the modified graphene, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, defoaming agent, and modified polysiloxane to obtain component A, using waterborne epoxy emulsion as component B, and mixing component A and component B.

[0006] A preparation method of an acid and alkali resistant and salt spray resistant coating includes the following preparation steps: (1) Mix hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, modified silane, and trifluoromethanesulfonic acid in a mass ratio of 1:(8 - 12):(6 - 8):(2 - 4):(0.05 - 0.07). Under a nitrogen atmosphere, stir at 20 - 30 °C and 200 - 400 r / min for 20 - 24 h. Add anhydrous sodium bicarbonate in an amount 2 - 2.4 times the mass of trifluoromethanesulfonic acid and stir for 1 - 2 h. Then add anhydrous sodium sulfate in an amount 3 - 4 times the mass of trifluoromethanesulfonic acid and continue to stir for 1 - 2 h. Filter, and vacuum-dry the liquid for 5 - 7 h to obtain modified polysiloxane. (2) Mix pre-modified graphene, 3-hexylthiophene, 3-allylthiophene, and anhydrous chloroform in a mass ratio of 1:(0.2 - 0.4):(0.1 - 0.2):(400 - 600). Ultrasonic for 10 - 20 min. Under a nitrogen atmosphere, stir at 400 - 600 r / min for 10 - 20 min. Add anhydrous ferric chloride in an amount 2 - 4 times the mass of pre-modified graphene and stir for 5 - 15 min. Cool in an ice bath and stir for 3 - 5 h. Continue to stir at room temperature for 2 - 3 days. Filter, wash the filter residue with anhydrous ethanol 3 - 5 times, and vacuum-dry for 5 - 7 h to obtain modified graphene. (3) Weigh 1 - 2 parts of modified graphene, 0.002 - 0.004 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, 0.025 - 0.035 parts of defoamer, 75 - 85 parts of modified polysiloxane, and 90 - 110 parts of deionized water and mix them evenly to obtain Component A; the waterborne epoxy emulsion is Component B; Mix Component A and Component B in a mass ratio of 1:0.8 to obtain the acid and alkali resistant and salt spray resistant coating.

[0007] As an optimization, the preparation method of the modified silane in step (1) is: Mix 4-imidazolecarboxaldehyde, 3-aminopropyldimethoxymethylsilane, and anhydrous ethanol in a mass ratio of 1:(1.6 - 1.8):(10 - 20). Stir at 400 - 600 r / min at 50 - 60 °C for 10 - 14 h, and dry at 75 - 85 °C for 4 - 6 h to obtain pre-modified silane; Mix the pre-modified silane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:(0.7 - 0.9). Stir at 400 - 600 r / min at 95 - 105 °C for 10 - 14 h to obtain it.

[0008] As an optimization, the preparation method of the pre-modified graphene in step (2) is: Mix 3-aminoethylthiophene, graphene oxide, anhydrous ethanol, and deionized water in a mass ratio of 1:(0.8 - 1.2):(45 - 55):(180 - 220). Ultrasonic for 10 - 20 min. Stir at 400 - 600 r / min at 85 - 95 °C for 18 - 22 h. Perform suction filtration, wash the filter cake with anhydrous ethanol 3 - 5 times, and vacuum-dry at 55 - 65 °C for 4 - 6 h to obtain it.

[0009] As an optimization, the preparation method of the aqueous epoxy emulsion described in step (3) is as follows: Mix diallylbisphenol A diglycidyl ether and polyethylene glycol at a mass ratio of 1:(5 - 15), heat at 90 - 100 °C for 25 - 35 min, raise the temperature to 175 - 185 °C, add potassium persulfate which is 0.0003 - 0.0005 times the mass of diallylbisphenol A diglycidyl ether, stir at 400 - 600 r / min for 3 - 5 h to obtain an emulsifier; Mix diallylbisphenol A diglycidyl ether, the emulsifier, and OP - 10 at a mass ratio of 1:(0.06 - 0.08):(0.02 - 0.04), stir at 4000 - 5000 r / min at 55 - 65 °C for 5 - 15 min, drop in deionized water at a rate of 150 ml / min, and stop when the solid content is 50% - 60% to obtain it.

[0010] As an optimization, the defoamer described in step (3) is AKN - 3386 type defoamer.

[0011] As an optimization, the graphene oxide is graphene oxide with a purity of 96%.

[0012] As an optimization, the polyethylene glycol described in step (4) is polyethylene glycol with an average molecular weight of 4000.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: When preparing the acid - alkali and salt - fog resistant coating of the present invention, 4 - imidazolecarboxaldehyde reacts with 3 - aminopropyldimethoxymethylsilane and then reacts with 9,10 - dihydro - 9 - oxa - 10 - phosphaphenanthrene - 10 - oxide to obtain a modified silane; Hexamethyldisiloxane, octamethylcyclotetrasiloxane, and 2,4,6,8 - tetramethylcyclotetrasiloxane react with the modified silane to obtain a modified polysiloxane; Graphene oxide reacts with 3 - aminoethylthiophene and then reacts with 3 - hexylthiophene and 3 - allylthiophene to obtain a modified graphene; The modified graphene, 1,3 - divinyl - 1,1,3,3 - tetramethyldisiloxane platinum, defoamer, and modified polysiloxane are mixed to obtain component A, and the aqueous epoxy emulsion is used as component B, and component A and component B are mixed to obtain it.

[0014] First, 4-imidazolecarboxaldehyde is reacted with 3-aminopropyldimethoxymethylsilane and then with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to obtain a modified silane; hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane are reacted with the modified silane to obtain a modified polysiloxane. The introduction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide makes the modified polysiloxane contain a large number of flame-retardant monomers, which has a good effect of promoting char formation during combustion. The char layer forms a dense structure on the surface of the material, inhibiting the escape of combustible gases and effectively improving the flame-retardant performance of the coating; in addition, imidazole can form a nitrogen-phosphorus-silicon synergistic flame retardancy with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the organosilicon long chain, further improving the flame-retardant performance of the coating. The modified polysiloxane introduces a large number of polysiloxane long chains containing methyl groups into the coating, which has a low surface energy and effectively improves the hydrophobic performance of the coating; the aldehyde group on 4-imidazolecarboxaldehyde reacts with the amino group on 3-aminopropyldimethoxymethylsilane, making a latent curing structure formed on the modified polysiloxane. After heat curing, a more compact cross-linked network is formed, effectively improving the acid and alkali resistance and salt spray resistance of the coating. Moreover, the abundant silicon-hydrogen structure and imidazole on the modified polysiloxane can react with double bonds and epoxy resin respectively to form a complex cross-linked network, increasing the cross-linking density, thereby further improving the acid and alkali resistance and salt spray resistance of the acid and alkali resistant and salt spray resistant coating.

[0015] Second, graphene oxide is reacted with 3-aminoethylthiophene and then with 3-hexylthiophene and 3-allylthiophene to obtain a modified graphene. The 3-allylthiophene on the modified graphene introduces double bonds, which can react with the silicon-hydrogen structure on the polysiloxane to form a complex cross-linked network, improving the acid and alkali resistance of the coating; graphene has a flaky structure, which can play a good physical barrier effect and extend the diffusion path of salt spray, thereby effectively improving the salt spray resistance of the coating. Specific embodiments

[0016] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0017] The graphene oxide in each of the examples and comparative examples is graphene oxide with a purity of 96%; the polyethylene glycol is polyethylene glycol with an average molecular weight of 4000; the defoamer is an AKN-3386 type defoamer.

[0018] Example 1, a preparation method of an acid and alkali resistant and salt spray resistant coating, includes the following preparation steps: (1) Mix 4-imidazolecarboxaldehyde, 3-aminopropyldimethoxymethylsilane, and absolute ethanol in a mass ratio of 1:1.6:10, stir at 400 r / min for 10 h at 50 °C, and dry at 75 °C for 4 h to obtain pre-modified silane; mix the pre-modified silane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:0.7, stir at 400 r / min for 10 h at 95 °C to obtain modified silane; mix hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, modified silane, and trifluoromethanesulfonic acid in a mass ratio of 1:8:6:2:0.05, stir at 20 °C and 200 r / min for 20 h under a nitrogen atmosphere, add anhydrous sodium bicarbonate twice the mass of trifluoromethanesulfonic acid, stir for 1 h, then add anhydrous sodium sulfate three times the mass of trifluoromethanesulfonic acid, continue to stir for 1 h, filter, and vacuum dry the liquid for 5 h to obtain modified polysiloxane; (2) Mix 3-aminoethylthiophene, graphene oxide, absolute ethanol, and deionized water in a mass ratio of 1:0.8:45:180, ultrasonicate for 10 min, stir at 400 r / min for 18 h at 85 °C, filter by suction, wash the filter cake with absolute ethanol three times, and vacuum dry at 55 °C for 4 h to obtain pre-modified graphene; mix the pre-modified graphene, 3-hexylthiophene, 3-allylthiophene, and anhydrous chloroform in a mass ratio of 1:0.2:0.1:400, ultrasonicate for 10 min, stir at 400 r / min for 10 min under a nitrogen atmosphere, add anhydrous ferric chloride twice the mass of pre-modified graphene, stir for 5 min, cool in an ice bath, stir for 3 h, continue to stir at room temperature for 2 days, filter, wash the filter residue with absolute ethanol three times, and vacuum dry for 5 h to obtain modified graphene; (3) Mix diallylbisphenol A diglycidyl ether and polyethylene glycol in a mass ratio of 1:5, heat at 90 °C for 25 min, raise the temperature to 175 °C and add potassium persulfate 0.0003 times the mass of diallylbisphenol A diglycidyl ether, stir at 400 r / min for 3 h to obtain an emulsifier; mix diallylbisphenol A diglycidyl ether, emulsifier, and OP-10 in a mass ratio of 1:0.06:0.02, stir at 4000 r / min for 5 min at 55 °C, and drop in deionized water at a rate of 150 ml / min, stop when the solid content reaches 50% to obtain an aqueous epoxy emulsion; (4) Weigh 1 part of modified graphene, 0.002 part of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, 0.025 part of defoamer, 75 parts of modified polysiloxane, and 90 parts of deionized water and mix them evenly to obtain Component A; the aqueous epoxy emulsion is Component B; mix Component A and Component B in a mass ratio of 1:0.8 to obtain an acid and alkali resistant and salt spray resistant coating.

[0019] Example 2, a method for preparing an acid and alkali resistant and salt spray resistant coating, includes the following preparation steps: (1) Mix 4-imidazolecarboxaldehyde, 3-aminopropyldimethoxymethylsilane, and absolute ethanol in a mass ratio of 1:1.7:15, stir at 500 r / min for 12 h at 55 °C, and dry at 80 °C for 5 h to obtain pre-modified silane; mix the pre-modified silane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:0.8, stir at 50 r / min for 12 h at 100 °C to obtain modified silane; mix hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, modified silane, and trifluoromethanesulfonic acid in a mass ratio of 1:10:7:3:0.06, stir at 300 r / min for 22 h at 25 °C under a nitrogen atmosphere, add anhydrous sodium bicarbonate 2.2 times the mass of trifluoromethanesulfonic acid, stir for 1.5 h, then add anhydrous sodium sulfate 3.5 times the mass of trifluoromethanesulfonic acid, continue to stir for 1.5 h, filter, and vacuum-dry the liquid for 6 h to obtain modified polysiloxane; (2) Mix 3-aminoethylthiophene, graphene oxide, absolute ethanol, and deionized water in a mass ratio of 1:1:50:200, ultrasonicate for 15 min, stir at 500 r / min for 20 h at 90 °C, filter by suction, wash the filter cake 4 times with absolute ethanol, and vacuum-dry at 60 °C for 5 h to obtain pre-modified graphene; mix the pre-modified graphene, 3-hexylthiophene, 3-allylthiophene, and anhydrous chloroform in a mass ratio of 1:0.3:0.15:500, ultrasonicate for 15 min, stir at 500 r / min for 15 min under a nitrogen atmosphere, add anhydrous ferric chloride 3 times the mass of pre-modified graphene, stir for 10 min, cool in an ice bath, stir for 4 h, continue to stir at room temperature for 2.5 days, filter, wash the filter residue 4 times with absolute ethanol, and vacuum-dry for 6 h to obtain modified graphene; (3) Mix diallylbisphenol A diglycidyl ether and polyethylene glycol in a mass ratio of 1:10, heat at 95 °C for 30 min, raise the temperature to 180 °C and add potassium persulfate 0.0004 times the mass of diallylbisphenol A diglycidyl ether, stir at 500 r / min for 4 h to obtain an emulsifier; mix diallylbisphenol A diglycidyl ether, the emulsifier, and OP-10 in a mass ratio of 1:0.07:0.03, stir at 4500 r / min for 10 min at 60 °C, and drop in deionized water at a rate of 150 ml / min, stop when the solid content reaches 55% to obtain an aqueous epoxy emulsion; (4) Weigh 1.5 parts of modified graphene, 0.003 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, 0.03 parts of defoamer, 80 parts of modified polysiloxane, and 100 parts of deionized water and mix them evenly to obtain Component A; the aqueous epoxy emulsion is Component B; mix Component A and Component B in a mass ratio of 1:0.8 to obtain an acid-alkali and salt spray resistant coating.

[0020] Example 3, a preparation method of an acid and alkali resistant and salt spray resistant coating, comprising the following preparation steps: (1) Mix 4-imidazole formaldehyde, 3-aminopropyldimethoxymethylsilane, and absolute ethanol in a mass ratio of 1: 1.8: 20, stir at 600 r / min at 60 °C for 14 h, and dry at 85 °C for 6 h to obtain pre-modified silane; Mix the pre-modified silane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:0.9, stir at 600 r / min at 105 °C for 14 h to obtain modified silane; Mix hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, modified silane, and trifluoromethanesulfonic acid in a mass ratio of 1:12:8:4:0.07, stir at 30 °C and 400 r / min for 24 h under a nitrogen atmosphere, add anhydrous sodium bicarbonate 2.4 times the mass of trifluoromethanesulfonic acid, stir for 2 h, then add anhydrous sodium sulfate 4 times the mass of trifluoromethanesulfonic acid, continue to stir for 2 h, filter, and vacuum dry the liquid for 7 h to obtain modified polysiloxane; (2) Mix 3-aminoethylthiophene, graphene oxide, absolute ethanol, and deionized water in a mass ratio of 1:1.2:55:220, ultrasonicate for 20 min, stir at 600 r / min at 95 °C for 22 h, filter by suction, wash the filter cake with absolute ethanol 5 times, and vacuum dry at 65 °C for 6 h to obtain pre-modified graphene; Mix the pre-modified graphene, 3-hexylthiophene, 3-allylthiophene, and anhydrous chloroform in a mass ratio of 1:0.4:0.2:600, ultrasonicate for 20 min, stir at 600 r / min under a nitrogen atmosphere for 20 min, add anhydrous ferric chloride 4 times the mass of the pre-modified graphene, stir for 15 min, cool in an ice bath, stir for 5 h, continue to stir at room temperature for 3 days, filter, wash the filter residue with absolute ethanol 5 times, and vacuum dry for 7 h to obtain modified graphene; (3) Mix diallylbisphenol A diglycidyl ether and polyethylene glycol in a mass ratio of 1:15, heat at 100 °C for 35 min, raise the temperature to 185 °C and add potassium persulfate 0.0005 times the mass of diallylbisphenol A diglycidyl ether, stir at 600 r / min for 5 h to obtain an emulsifier; Mix diallylbisphenol A diglycidyl ether, the emulsifier, and OP-10 in a mass ratio of 1:0.08:0.04, stir at 5000 r / min at 65 °C for 15 min, and drop in deionized water at a rate of 150 ml / min, stop when the solid content reaches 60% to obtain an aqueous epoxy emulsion; (4)Weigh 2 parts of modified graphene, 0.004 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, 0.035 parts of defoamer, 85 parts of modified polysiloxane, and 110 parts of deionized water and mix them evenly to obtain Component A; The aqueous epoxy emulsion is Component B; Mix Component A and Component B in a mass ratio of 1:0.8 to obtain the acid and alkali resistant and salt spray resistant coating.

[0021] Comparative Example 1, a preparation method of an acid and alkali resistant and salt spray resistant coating, comprising the following preparation steps: (1) Mix 4-imidazolecarboxaldehyde, 3-aminopropyldimethoxymethylsilane, and absolute ethanol in a mass ratio of 1:1.7:15, stir at 500 r / min for 12 h at 55 °C, and dry at 80 °C for 5 h to obtain pre-modified silane; mix hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, pre-modified silane, and trifluoromethanesulfonic acid in a mass ratio of 1:10:7:3:0.06, stir at 300 r / min for 22 h at 25 °C under a nitrogen atmosphere, add anhydrous sodium bicarbonate 2.2 times the mass of trifluoromethanesulfonic acid, stir for 1.5 h, then add anhydrous sodium sulfate 3.5 times the mass of trifluoromethanesulfonic acid, continue to stir for 1.5 h, filter, and vacuum dry the liquid for 6 h to obtain modified polysiloxane; (2) Mix 3-aminoethylthiophene, graphene oxide, absolute ethanol, and deionized water in a mass ratio of 1:1:50:200, ultrasonicate for 15 min, stir at 500 r / min for 20 h at 90 °C, filter by suction, wash the filter cake 4 times with absolute ethanol, and vacuum dry at 60 °C for 5 h to obtain pre-modified graphene; mix pre-modified graphene, 3-hexylthiophene, 3-allylthiophene, and anhydrous chloroform in a mass ratio of 1:0.3:0.15:500, ultrasonicate for 15 min, stir at 500 r / min for 15 min under a nitrogen atmosphere, add anhydrous ferric chloride 3 times the mass of pre-modified graphene, stir for 10 min, cool in an ice bath, stir for 4 h, continue to stir at room temperature for 2.5 days, filter, wash the filter residue 4 times with absolute ethanol, and vacuum dry for 6 h to obtain modified graphene; (3) Mix diallylbisphenol A diglycidyl ether and polyethylene glycol in a mass ratio of 1:10, heat at 95 °C for 30 min, raise the temperature to 180 °C, add potassium persulfate 0.0004 times the mass of diallylbisphenol A diglycidyl ether, and stir at 500 r / min for 4 h to obtain an emulsifier; mix diallylbisphenol A diglycidyl ether, emulsifier, and OP-10 in a mass ratio of 1:0.07:0.03, stir at 4500 r / min for 10 min at 60 °C, and drop in deionized water at a rate of 150 ml / min, stop when the solid content reaches 55% to obtain an aqueous epoxy emulsion; (4) Weigh 1.5 parts of modified graphene, 0.003 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, 0.03 parts of defoamer, 80 parts of modified polysiloxane, and 100 parts of deionized water and mix them evenly to obtain Component A; the aqueous epoxy emulsion is Component B; mix Component A and Component B in a mass ratio of 1:0.8 to obtain an acid and alkali resistant and salt spray resistant coating.

[0022] Comparative Example 2, a preparation method of an acid-alkali and salt spray resistant coating, comprising the following preparation steps: (1) Mix hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, and trifluoromethanesulfonic acid in a mass ratio of 1:10:7:0.06. Under a nitrogen atmosphere, stir at 25 °C and 300 r / min for 22 h. Add anhydrous sodium bicarbonate 2.2 times the mass of trifluoromethanesulfonic acid, stir for 1.5 h, then add anhydrous sodium sulfate 3.5 times the mass of trifluoromethanesulfonic acid, continue to stir for 1.5 h, filter, and vacuum dry the liquid for 6 h to obtain modified polysiloxane; (2) Mix 3-aminoethylthiophene, graphene oxide, anhydrous ethanol, and deionized water in a mass ratio of 1:1:50:200, ultrasonicate for 15 min, stir at 90 °C and 500 r / min for 20 h, perform suction filtration, wash the filter cake with anhydrous ethanol 4 times, and vacuum dry at 60 °C for 5 h to obtain pre-modified graphene; Mix pre-modified graphene, 3-hexylthiophene, 3-allylthiophene, and anhydrous chloroform in a mass ratio of 1:0.3:0.15:500, ultrasonicate for 15 min, under a nitrogen atmosphere, stir at 500 r / min for 15 min, add anhydrous ferric chloride 3 times the mass of pre-modified graphene, stir for 10 min, perform ice bath, stir for 4 h, continue to stir at room temperature for 2.5 days, filter, wash the filter residue with anhydrous ethanol 4 times, and vacuum dry for 6 h to obtain modified graphene; (3) Mix diallylbisphenol A diglycidyl ether and polyethylene glycol in a mass ratio of 1:10, heat at 95 °C for 30 min, raise the temperature to 180 °C, add potassium persulfate 0.0004 times the mass of diallylbisphenol A diglycidyl ether, and stir at 500 r / min for 4 h to obtain an emulsifier; Mix diallylbisphenol A diglycidyl ether, emulsifier, and OP-10 in a mass ratio of 1:0.07:0.03, stir at 60 °C and 4500 r / min for 10 min, and drop in deionized water at a rate of 150 ml / min, stop when the solid content reaches 55% to obtain an aqueous epoxy emulsion; (4) Weigh 1.5 parts of modified graphene, 0.003 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, 0.03 parts of defoamer, 80 parts of modified polysiloxane, and 100 parts of deionized water and mix them evenly to obtain Component A; The aqueous epoxy emulsion is Component B; Mix Component A and Component B in a mass ratio of 1:0.8 to obtain the acid-alkali and salt spray resistant coating.

[0023] Comparative Example 3, a preparation method of an acid-alkali and salt spray resistant coating, comprising the following preparation steps: (1) Mix 3 - aminoethylthiophene, graphene oxide, absolute ethanol, and deionized water in a mass ratio of 1:1:50:200, ultrasonic for 15 min, stir at 500 r / min at 90 °C for 20 h, perform suction filtration, wash the filter cake with absolute ethanol 4 times, and dry it in vacuum at 60 °C for 5 h to obtain pre - modified graphene; Mix pre - modified graphene, 3 - hexylthiophene, 3 - allylthiophene, and absolute chloroform in a mass ratio of 1:0.3:0.15:500, ultrasonic for 15 min, stir at 500 r / min under a nitrogen atmosphere for 15 min, add anhydrous ferric chloride 3 times the mass of pre - modified graphene, stir for 10 min, cool in an ice bath, stir for 4 h, continue to stir at room temperature for 2.5 days, filter, wash the filter residue with absolute ethanol 4 times, and dry it in vacuum for 6 h to obtain modified graphene; (2) Mix diallylbisphenol A diglycidyl ether and polyethylene glycol in a mass ratio of 1:10, heat at 95 °C for 30 min, raise the temperature to 180 °C, add potassium persulfate 0.0004 times the mass of diallylbisphenol A diglycidyl ether, and stir at 500 r / min for 4 h to obtain an emulsifier; Mix diallylbisphenol A diglycidyl ether, emulsifier, and OP - 10 in a mass ratio of 1:0.07:0.03, stir at 4500 r / min at 60 °C for 10 min, and drip deionized water at a rate of 150 ml / min, stop when the solid content reaches 55% to obtain a water - borne epoxy emulsion; (3) Weigh 1.5 parts of modified graphene, 0.003 parts of 1,3 - divinyl - 1,1,3,3 - tetramethyldisiloxane platinum, 0.03 parts of defoamer, 5 parts of ethylenediamine, and 100 parts of deionized water and mix them evenly to obtain component A; The water - borne epoxy emulsion is component B; Mix component A and component B in a mass ratio of 1:0.8 to obtain an acid - alkali and salt - fog resistant coating.

[0024] Comparative Example 4, A preparation method of an acid - alkali and salt - fog resistant coating, comprising the following preparation steps: (1) Mix 4-imidazolecarboxaldehyde, 3-aminopropyldimethoxymethylsilane, and absolute ethanol in a mass ratio of 1:1.7:15, stir at 500 r / min for 12 h at 55 °C, and dry at 80 °C for 5 h to obtain pre-modified silane; mix the pre-modified silane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:0.8, stir at 50 r / min for 12 h at 100 °C to obtain modified silane; mix hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, pre-modified silane, and trifluoromethanesulfonic acid in a mass ratio of 1:10:7:3:0.06, stir at 300 r / min for 22 h at 25 °C under a nitrogen atmosphere, add anhydrous sodium bicarbonate 2.2 times the mass of trifluoromethanesulfonic acid, stir for 1.5 h, then add anhydrous sodium sulfate 3.5 times the mass of trifluoromethanesulfonic acid, continue to stir for 1.5 h, filter, and vacuum dry the liquid for 6 h to obtain modified polysiloxane; (2) Mix diallylbisphenol A diglycidyl ether and polyethylene glycol in a mass ratio of 1:10, heat at 95 °C for 30 min, raise the temperature to 180 °C, add potassium persulfate 0.0004 times the mass of diallylbisphenol A diglycidyl ether, and stir at 500 r / min for 4 h to obtain an emulsifier; mix diallylbisphenol A diglycidyl ether, the emulsifier, and OP-10 in a mass ratio of 1:0.07:0.03, stir at 4500 r / min for 10 min at 60 °C, and drop in deionized water at a rate of 150 ml / min, stop when the solid content reaches 55% to obtain an aqueous epoxy emulsion; (3) Weigh 1.5 parts of graphene, 0.003 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, 0.03 parts of defoamer, 80 parts of modified polysiloxane, and 100 parts of deionized water and mix them evenly to obtain Component A; the aqueous epoxy emulsion is Component B; mix Component A and Component B in a mass ratio of 1:0.8 to obtain an acid and alkali resistant and salt spray resistant coating.

[0025] Comparative Example 5, a method for preparing an acid and alkali resistant and salt spray resistant coating, includes the following preparation steps: (1) Mix 4-imidazolecarboxaldehyde, 3-aminopropyldimethoxymethylsilane, and absolute ethanol in a mass ratio of 1:1.7:15, stir at 500 r / min for 12 h at 55 °C, and dry at 80 °C for 5 h to obtain pre-modified silane; mix the pre-modified silane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:0.8, stir at 50 r / min for 12 h at 100 °C to obtain modified silane; mix hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, pre-modified silane, and trifluoromethanesulfonic acid in a mass ratio of 1:10:7:3:0.06, stir at 300 r / min for 22 h at 25 °C under a nitrogen atmosphere, add anhydrous sodium bicarbonate 2.2 times the mass of trifluoromethanesulfonic acid, stir for 1.5 h, then add anhydrous sodium sulfate 3.5 times the mass of trifluoromethanesulfonic acid, continue to stir for 1.5 h, filter, and vacuum-dry the liquid for 6 h to obtain modified polysiloxane; (2) Mix diallylbisphenol A diglycidyl ether and polyethylene glycol in a mass ratio of 1:10, heat at 95 °C for 30 min, raise the temperature to 180 °C, add potassium persulfate 0.0004 times the mass of diallylbisphenol A diglycidyl ether, and stir at 500 r / min for 4 h to obtain an emulsifier; mix diallylbisphenol A diglycidyl ether, emulsifier, and OP-10 in a mass ratio of 1:0.07:0.03, stir at 4500 r / min for 10 min at 60 °C, and drip deionized water at a rate of 150 ml / min, stop when the solid content reaches 55% to obtain a waterborne epoxy emulsion; (3) Weigh 0.003 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, 0.03 parts of defoamer, 80 parts of modified polysiloxane, and 100 parts of deionized water and mix them to obtain Component A; the waterborne epoxy emulsion is Component B; mix Component A and Component B in a mass ratio of 1:0.8 to obtain an acid-alkali and salt spray resistant coating.

[0026] Test Example 1: Acid-alkali resistance test: Fix the test panel on a horizontal platform, grind the steel plate with sandpaper of 150 to 1000 grit, and degrease it ultrasonically in acetone. Then evenly coat the prepared coating on Q235 carbon steel (100 mm × 70 mm × 0.8 mm) and dry at 70 °C for 48 hours. Prepare 5 wt% hydrochloric acid and 5 wt% sodium hydroxide aqueous solutions respectively, immerse the test samples in the prepared acid-base solutions, and each group of test specimens includes 3 Q235 steel plates. Observe the coating peeling situation. The results are shown in Table 1.

[0027] Salt spray resistance performance test: Fix the test panel on a horizontal platform, grind the steel plate with sandpaper of 150 to 1000 grit, and degrease it ultrasonically in acetone. Then evenly coat the prepared coating on Q235 carbon steel (100 mm × 70 mm × 0.8 mm) and dry it at room temperature for 24 hours. Coat the coatings prepared in each example and comparative example on the 0235 steel plate according to the formula, dry at 70 °C for 48 hours, make scratch damage along the diagonal with a knife, and seal the edge of the test steel plate with transparent tape to prevent the corrosive medium from infiltrating from the edge and affecting the experimental results. Subsequently, put the prepared test samples into a YWX-150 type salt spray test chamber for testing, and observe the corrosion situation at the scratch of the samples. The results are shown in Table 1.

[0028] Table 1: ; From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 1, it can be found that the acid and alkali resistant and salt spray resistant coating prepared by the present invention has good acid and alkali resistance and salt spray resistance performance.

[0029] By comparison, the peeling situation of Examples 1 to 3 is better than that of Comparative Example 2, indicating that the aldehyde group on 4-imidazolecarboxaldehyde reacts with the amino group on 3-aminopropyldimethoxymethylsilane, forming a latent curing structure on the modified polysiloxane. After heat curing, a more compact crosslinked network is formed, effectively improving the acid and alkali resistance of the coating; the peeling situation of Examples 1 to 3 is better than that of Comparative Example 3, indicating that the rich silicon hydride structure and imidazole on the modified polysiloxane can react with double bonds and epoxy resins respectively to form a complex crosslinked network, increasing the crosslinking density, thereby improving the acid and alkali resistance of the acid and alkali resistant and salt spray resistant coating; the peeling situation of Examples 1 to 3 is better than that of Comparative Examples 4 and 5, indicating that the 3-allylthiophene introduced on the modified graphene introduces double bonds, which can react with the silicon hydride structure on the polysiloxane to form a complex crosslinked network, improving the acid and alkali resistance of the coating.

[0030] By comparison, the rusting situation of Examples 1 to 3 is better than that of Comparative Example 2, indicating that the aldehyde group on 4-imidazolecarboxaldehyde reacts with the amino group on 3-aminopropyldimethoxymethylsilane, forming a latent curing structure on the modified polysiloxane. After heat curing, a more compact crosslinked network is formed, effectively improving the salt spray resistance of the coating; the rusting situation of Examples 1 to 3 is better than that of Comparative Example 3, indicating that the rich silicon hydride structure and imidazole on the modified polysiloxane can react with double bonds and epoxy resins respectively to form a complex crosslinked network, increasing the crosslinking density, thereby improving the salt spray resistance of the acid and alkali resistant and salt spray resistant coating; the rusting situation of Examples 1 to 3 is better than that of Comparative Example 5, indicating that graphene is in a flaky structure, which can play a good physical barrier effect, extending the diffusion path of salt spray, thereby effectively improving the salt spray resistance of the coating.

[0031] Test Example 2: Flame retardancy test: Samples of the fast-drying waterborne epoxy coatings prepared in each of the examples and test examples were prepared in accordance with GB / T 2406 and the limiting oxygen index was tested. The results are shown in Table 2.

[0032] Table 2: ; From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 2, it can be found that the acid and alkali resistant and salt spray resistant coatings prepared by the present invention have good flame retardancy.

[0033] By comparison, the limiting oxygen index of Examples 1 to 3 is significantly greater than that of Comparative Example 1, indicating that the modified silane is prepared by reacting 4-imidazolecarboxaldehyde with 3-aminopropyldimethoxymethylsilane and then reacting with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; reacting hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane with the modified silane to obtain a modified polysiloxane. The introduction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide makes the modified polysiloxane contain a large number of flame retardant monomers, which has a good effect of promoting char formation during combustion. The carbon layer forms a dense structure on the surface of the material, inhibiting the escape of combustible gases and effectively improving the flame retardancy of the coating; the limiting oxygen index of Examples 1 to 3 is significantly greater than that of Comparative Examples 2 and 3, indicating that imidazole can form a nitrogen-phosphorus-silicon synergistic flame retardancy with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the organic silicon long chain, improving the flame retardancy of the coating.

[0034] Test Example 3: Hydrophobic property test: The coatings prepared in each of the examples and comparative examples were cut into specimens of 100 mm × 100 mm, and the static contact angle of water was tested with an SL200A type contact angle meter. The results are shown in Table 3.

[0035] Table 3: ; From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 3, it can be found that the acid and alkali resistant and salt spray resistant coatings prepared by the present invention have good hydrophobic properties.

[0036] By comparison, the contact angles of Examples 1 to 3 are significantly greater than that of Comparative Example 3, indicating that the modified silane is prepared by reacting 4-imidazolecarboxaldehyde with 3-aminopropyldimethoxymethylsilane and then reacting with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; reacting hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane with the modified silane to obtain the modified polysiloxane, introducing a large number of polysiloxane long chains containing methyl groups into the coating, which has a low surface energy and effectively improves the hydrophobic performance of the coating.

[0037] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and does not limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. An acid- and alkali-resistant and salt spray-resistant coating, characterized in that The acid- and alkali-resistant and salt-fog-resistant coating is prepared by mixing modified graphene, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, an antifoaming agent, and modified polysiloxane to obtain Component A, using a waterborne epoxy emulsion as Component B, and mixing Component A and Component B; The modified graphene is prepared by reacting graphene oxide with 3-aminoethylthiophene and then reacting with 3-hexylthiophene and 3-allylthiophene; The modified polysiloxane is prepared by reacting 4-imidazole formaldehyde with 3-aminopropyldimethoxymethylsilane, then reacting with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and finally reacting with hexamethyldisiloxane, octamethylcyclotetrasiloxane, and 2,4,6,8-tetramethylcyclotetrasiloxane; 2. A preparation method of an acid and alkali resistant and salt spray resistant coating, characterized in that, It includes the following preparation steps: (1) Mix hexamethyldisiloxane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, modified silane, and trifluoromethanesulfonic acid in a mass ratio of 1:(8 - 12):(6 - 8):(2 - 4):(0.05 - 0.07). Under a nitrogen atmosphere, stir at 20 - 30°C and 200 - 400 r / min for 20 - 24 h. Add anhydrous sodium bicarbonate that is 2 - 2.4 times the mass of trifluoromethanesulfonic acid, stir for 1 - 2 h, then add anhydrous sodium sulfate that is 3 - 4 times the mass of trifluoromethanesulfonic acid, continue to stir for 1 - 2 h, filter, and vacuum-dry the liquid for 5 - 7 h to obtain modified polysiloxane; (2) Mix pre-modified graphene, 3-hexylthiophene, 3-allylthiophene, and anhydrous chloroform in a mass ratio of 1:(0.2 - 0.4):(0.1 - 0.2):(400 - 600). Ultrasonic for 10 - 20 min. Under a nitrogen atmosphere, stir at 400 - 600 r / min for 10 - 20 min. Add anhydrous ferric chloride that is 2 - 4 times the mass of pre-modified graphene, stir for 5 - 15 min, cool in an ice bath, stir for 3 - 5 h, continue to stir at room temperature for 2 - 3 days, filter, wash the filter residue with anhydrous ethanol 3 - 5 times, and vacuum-dry for 5 - 7 h to obtain modified graphene; (3) Weigh 1 - 2 parts of modified graphene, 0.002 - 0.004 parts of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, 0.025 - 0.035 parts of an antifoaming agent, 75 - 85 parts of modified polysiloxane, and 90 - 110 parts of deionized water and mix them to obtain Component A; the waterborne epoxy emulsion is Component B; mix Component A and Component B in a mass ratio of 1:0.8 to obtain the acid- and alkali-resistant and salt-fog-resistant coating.

3. The preparation method of an acid and alkali resistant and salt spray resistant coating according to claim 2, wherein, The preparation method of the modified silane in step (1) is: Mix 4-imidazole formaldehyde, 3-aminopropyldimethoxymethylsilane, and anhydrous ethanol in a mass ratio of 1:(1.6 - 1.8):(10 - 20). Stir at 400 - 600 r / min at 50 - 60°C for 10 - 14 h, and dry at 75 - 85°C for 4 - 6 h to obtain pre-modified silane; Mix the pre-modified silane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a mass ratio of 1:(0.7 - 0.9). Stir at 400 - 600 r / min at 95 - 105°C for 10 - 14 h to obtain it.

4. The preparation method of an acid and alkali resistant and salt spray resistant coating according to claim 2, characterized in that, The preparation method of the pre-modified graphene described in step (2) is as follows: Mix 3-aminoethylthiophene, graphene oxide, absolute ethanol, and deionized water according to a mass ratio of 1:(0.8 - 1.2):(45 - 55):(180 - 220), ultrasonicate for 10 - 20 min, stir at 400 - 600 r / min at 85 - 95 °C for 18 - 22 h, perform suction filtration, wash the filter cake with absolute ethanol 3 - 5 times, and dry it in vacuum at 55 - 65 °C for 4 - 6 h to obtain it.

5. The preparation method of an acid- and alkali-resistant and salt spray-resistant coating according to claim 2, wherein, The preparation method of the waterborne epoxy emulsion described in step (3) is as follows: Mix diallyl bisphenol A diglycidyl ether and polyethylene glycol according to a mass ratio of 1:(5 - 15), heat at 90 - 100 °C for 25 - 35 min, raise the temperature to 175 - 185 °C and add potassium persulfate in an amount of 0.0003 - 0.0005 times the mass of diallyl bisphenol A diglycidyl ether, stir at 400 - 600 r / min for 3 - 5 h to obtain an emulsifier; Mix diallyl bisphenol A diglycidyl ether, the emulsifier, and OP-10 according to a mass ratio of 1:(0.06 - 0.08):(0.02 - 0.04), stir at 4000 - 5000 r / min at 55 - 65 °C for 5 - 15 min, and drop deionized water at a rate of 150 ml / min, stop when the solid content reaches 50% - 60% to obtain it.

6. The preparation method of an acid and alkali resistant and salt spray resistant coating according to claim 2, wherein, The defoamer described in step (3) is AKN-3386 type defoamer.