A high-temperature resistant metal coating and its preparation process

Abstract

The present invention relates to the technical field of metal coatings, and specifically relates to a high-temperature resistant metal coating and its preparation process. In the present invention, first, acrylic acid and 1,1,3,3-tetramethyldisiloxane are used as raw materials to prepare intermediate A, and diethanolamine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and paraformaldehyde are reacted to obtain intermediate B; intermediate A and intermediate B are reacted at a molar ratio of 1:2 to obtain a silicon-containing flame-retardant diol; then polytetrahydrofuran ether diol 2000 and the silicon-containing flame-retardant diol are mixed and reacted with isophorone diisocyanate and chain-extended to obtain a modified polyurethane emulsion; the modified polyurethane emulsion, deionized water, wetting agent, defoaming agent, dispersant, titanium dioxide, barium sulfate powder, zinc phosphate, leveling agent, and thickening agent are mixed and stirred to obtain a high-temperature resistant metal coating.

Description

Technical Field

[0001] The present invention relates to the technical field of metal coatings, and specifically relates to a high-temperature resistant metal coating and a preparation process thereof. Background Art

[0002] Metal materials are a type of materials with properties such as luster, ductility, easy electrical conductivity, and heat transfer. They are widely used in fields such as construction, manufacturing, transportation, aerospace, and electronic communication. Metal materials are prone to external corrosion during use, resulting in reduced mechanical properties and shortened service life. Therefore, it is necessary to coat their surfaces with coatings to tightly separate the metal surface from the external medium and protect the metal from external corrosion.

[0003] Metal coatings, also known as metal paints, can not only protect the metal substrate from oxidation and rust, but also perform surface processing and color treatment to make the metal material more beautiful. However, most coatings are organic polymer materials, which are not high-temperature resistant and are flammable. Therefore, it is very necessary to modify them. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-temperature resistant metal coating and a preparation process thereof to solve the problems raised in the above background art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions: A high-temperature resistant metal coating and a preparation process thereof, including the following steps:

[0006] Step 1:

[0007] Dehydrate polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol at 110 - 120 °C respectively; mix the dehydrated polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol to obtain a mixed diol; mix the mixed diol, dimethylolpropionic acid, and isophorone diisocyanate, and use dibutyltin dilaurate as a catalyst to react at 70 - 80 °C in a nitrogen environment for 2 - 3 h. Cool down to 50 - 60 °C and add 1,4-butanediol, then heat up to 60 - 70 °C and continue to react for 1 - 2 h; subsequently, add 20 - 30 parts of acetone to reduce the viscosity, add triethylamine to neutralize to a neutralization degree of 100%, add deionized water to emulsify for 5 - 10 min, then add ethylenediamine for chain extension reaction for 30 min, and evaporate acetone to obtain a modified polyurethane emulsion with a solid content of 30 - 40%;

[0008] Step 2:

[0009] Mix and stir the modified polyurethane emulsion, deionized water, wetting agent, defoaming agent, dispersant, titanium dioxide, barium sulfate powder, zinc phosphate, leveling agent, and thickening agent to obtain a high-temperature resistant metal coating.

[0010] Further, in Step 1, the preparation method of the silicon-containing flame retardant diol is:

[0011] S1: Disperse acrylic acid and inhibitor in deionized water, heat to 60 - 70 °C, under argon protection, using isopropanol solution of chloroplatinic acid as catalyst, add 1,1,3,3 - tetramethyldisiloxane, keep the temperature for reaction for 8 - 10 h, distill off the solvent under reduced pressure to obtain intermediate A;

[0012] S2: Take diethanolamine and 9,10 - dihydro - 9 - oxa - 10 - phosphaphenanthrene - 10 - oxide and disperse them in deionized water, stir and heat the oil bath to 70 - 85 °C, then add paraformaldehyde in 2 - 3 portions at intervals of 3 - 5 min; after adding paraformaldehyde completely, keep the temperature for reflux reaction for 60 - 75 min, remove impurities by vacuum rotary evaporation, obtain the crude product, wash it with absolute ethanol, and then vacuum treat it at 120 - 130 °C for 2 - 3 h to obtain intermediate B;

[0013] S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4 - dimethylaminopyridine under nitrogen protection, stir for 5 - 10 min, then add intermediate B to the reaction system, react at 40 - 50 °C for 48 h, then distill off the solvent under reduced pressure by rotary evaporation, and wash and dry the product with boiling water.

[0014] Further, in S1, the molar ratio of acrylic acid to 1,1,3,3 - tetramethyldisiloxane is 2:1.

[0015] Further, in S2, the molar ratio of diethanolamine, 9,10 - dihydro - 9 - oxa - 10 - phosphaphenanthrene - 10 - oxide is 1:1:1.5.

[0016] Further, in S3, the molar ratio of intermediate A to intermediate B is 1:2.

[0017] Further, in step 1, in the mixed diol, the mass ratio of polytetrahydrofuran ether diol 2000 to silicon - containing flame - retardant diol is (3 - 4):1.

[0018] Further, in step 1, when preparing the modified polyurethane emulsion, the dosage of each component, by weight, is 100 parts of mixed diol, 9 - 12 parts of dimethylolpropionic acid, 120 - 138 parts of isophorone diisocyanate, 7 - 11 parts of 1,4 - butanediol, 20 - 30 parts of acetone, 3 - 5 parts of ethylenediamine.

[0019] Further, in step 1, the solid content of the modified polyurethane emulsion is 30 - 40%.

[0020] Furthermore, in step 2, the content of each component in the high temperature resistant metal coating is, by weight, 45 to 55 parts of modified polyurethane emulsion, 15 to 18 parts of deionized water, 0.3 to 0.5 parts of wetting agent, 0.1 to 0.3 parts of defoaming agent, 0.2 to 0.5 parts of dispersant, 8 to 10 parts of titanium dioxide, 4 to 5 parts of barium sulfate powder, 2 to 3 parts of zinc phosphate, 0.1 to 0.3 parts of leveling agent, and 0.1 to 0.3 parts of thickener.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention provides a preparation process for a high-temperature resistant metal coating, wherein polytetramethylene ether glycol 2000 is mixed with a silicon-containing flame-retardant diol to obtain a mixed diol, and then the mixed diol is reacted with isophorone diisocyanate and chain extended to obtain a modified polyurethane emulsion; the modified polyurethane emulsion, deionized water, a wetting agent, a defoaming agent, a dispersant, titanium dioxide, barium sulfate powder, zinc phosphate, a leveling agent, and a thickener are mixed and stirred to obtain a high-temperature resistant metal coating.

[0022] Among them, the preparation method of silicon-containing flame-retardant diol is: prepare intermediate A with acrylic acid and 1,1,3,3-tetramethyldisiloxane as raw materials, react with diethanolamine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and polyformaldehyde to obtain intermediate B; react intermediate A and intermediate B at a molar ratio of 1:2. Silicon-containing flame-retardant diol not only improves the flame retardant properties of polyurethane, but also introduces Si-O-Si segments to improve the high temperature resistance and water resistance of polyurethane. When preparing silicon-containing flame-retardant diol, since intermediate A contains two carboxyl groups and intermediate B contains two hydroxyl groups, intermediate A and intermediate B are reacted at a molar ratio of 1:2 to obtain silicon-containing flame-retardant diol. In addition, it should be noted that excessive use of silicon-containing flame-retardant diols will lead to reduced performance stability of the prepared polyurethane emulsion. Therefore, when the mass ratio of polytetramethylene ether diol 2000 and silicon-containing flame-retardant diol is controlled at (3~4):1, the prepared metal coating has the best performance. DETAILED DESCRIPTION

[0023] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0024] Materials and sources used in the present invention: the inhibitor is inhibitor 701; the wetting agent model is ZY-2045, the defoaming agent model is ZY-1024, the dispersant model is ZY-9200, the leveling agent model is ZY-1737, and the thickener model is ZY-608W, all from Shanghai Ziyi Chemical Co., Ltd.; titanium dioxide comes from Anhui Anada Titanium Co., Ltd., model ATR-311; barium sulfate powder comes from Yichang Zhongtai New Materials Co., Ltd., model PB-88.

[0025] Example 1: A high-temperature resistant metal coating and its preparation process, including the following steps:

[0026] Step 1:

[0027] S1: Disperse acrylic acid and inhibitor in deionized water, heat to 60 °C, under argon protection, use isopropanol solution of chloroplatinic acid as catalyst, add 1,1,3,3-tetramethyldisiloxane, keep the temperature for reaction for 8 h, remove the solvent by reduced pressure distillation to obtain intermediate A, where the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1;

[0028] S2: Take diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and disperse them in deionized water. After stirring and heating the oil bath to 70 °C, add paraformaldehyde in two portions with an interval of 3 min each time; after the addition of paraformaldehyde is complete, keep the temperature for reflux reaction for 60 min, remove impurities by vacuum rotary evaporation, wash with anhydrous ethanol, and then vacuum treat at 120 °C for 2 h to obtain intermediate B; where the molar ratio of diethanolamine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.5;

[0029] S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 5 min, then add intermediate B to the reaction system, react at 40 °C for 48 h, remove the solvent by reduced pressure rotary evaporation, wash the product with boiling water, and dry to obtain a silicon-containing flame retardant diol; where the molar ratio of intermediate A to intermediate B is 1:2;

[0030] Step 2:

[0031] Dehydrate polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol at 110 °C respectively; mix the dehydrated polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol according to a mass ratio of 4:1 to obtain a mixed diol; mix 100 g of the mixed diol, 10 g of dimethylolpropionic acid, and 138 g of isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 70 °C under a nitrogen environment for 2 h, cool to 50 °C, add 9 g of 1,4-butanediol, heat to 60 °C and continue to react for 1 h; then add 20 g of acetone to reduce the viscosity, add triethylamine to neutralize to a neutralization degree of 100%, add deionized water to emulsify for 5 min, add 4 g of ethylenediamine for chain extension reaction for 30 min, and remove acetone to obtain a modified polyurethane emulsion with a solid content of 40%;

[0032] Step 3:

[0033] Mix 50 g of modified polyurethane emulsion, 15 g of deionized water, 0.5 g of wetting agent, 0.3 g of defoamer, 0.5 g of dispersant, 10 g of titanium dioxide, 4 g of barium sulfate powder, 3 g of zinc phosphate, 0.2 g of leveling agent, and 0.3 g of thickener by stirring to obtain a high-temperature resistant metal coating.

[0034] Example 2: A high-temperature resistant metal coating and its preparation process, comprising the following steps:

[0035] Step 1:

[0036] S1: Disperse acrylic acid and inhibitor in deionized water, heat to 65 °C, under argon protection, using an isopropanol solution of chloroplatinic acid as a catalyst, add 1,1,3,3-tetramethyldisiloxane, keep the temperature for reaction for 9 h, and remove the solvent by reduced pressure evaporation to obtain intermediate A, where the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1;

[0037] S2: Take diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and disperse them in deionized water. After stirring and heating the oil bath to 80 °C, add paraformaldehyde in 3 portions at intervals of 4 min; after the paraformaldehyde is added, keep the temperature for reflux reaction for 70 min, remove impurities by vacuum rotary evaporation, obtain the crude product, wash it with absolute ethanol, and then perform vacuum treatment at 125 °C for 2.5 h to obtain intermediate B; where the molar ratio of diethanolamine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.5;

[0038] S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 8 min, then add intermediate B to the reaction system, react at 45 °C for 48 h, remove the solvent by reduced pressure rotary evaporation, wash the product with boiling water, and dry to obtain a silicon-containing flame retardant diol; where the molar ratio of intermediate A to intermediate B is 1:2;

[0039] Step 2:

[0040] Poly (tetrahydrofuran) ether glycol 2000 and a silicon-containing flame retardant diol were dehydrated at 115 °C respectively; the dehydrated poly (tetrahydrofuran) ether glycol 2000 and the silicon-containing flame retardant diol were mixed according to a mass ratio of 3.5:1 to obtain a mixed diol; 100 g of the mixed diol, 10 g of dimethylolpropionic acid, and 138 g of isophorone diisocyanate were mixed, and dibutyltin dilaurate was used as a catalyst to react at 75 °C in a nitrogen environment for 2.5 h. The temperature was lowered to 55 °C, 9 g of 1,4-butanediol was added, and the temperature was raised to 65 °C and the reaction continued for 1.5 h; then 20 g of acetone was added to reduce the viscosity, triethylamine was added to neutralize to a neutralization degree of 100%, deionized water was added for emulsification for 8 min, and then 4 g of ethylenediamine was added for chain extension reaction for 30 min. Acetone was distilled off to obtain a modified polyurethane emulsion with a solid content of 40%.

[0041] Step 3:

[0042] 50 g of the modified polyurethane emulsion, 15 g of deionized water, 0.5 g of wetting agent, 0.3 g of defoaming agent, 0.5 g of dispersant, 10 g of titanium dioxide, 4 g of barium sulfate powder, 3 g of zinc phosphate, 0.2 g of leveling agent, and 0.3 g of thickener were mixed and stirred to obtain a high-temperature resistant metal coating.

[0043] Example 3: A high-temperature resistant metal coating and its preparation process, including the following steps:

[0044] Step 1:

[0045] S1: Acrylic acid and a polymerization inhibitor were dispersed in deionized water, heated to 70 °C, and under argon protection, using an isopropanol solution of chloroplatinic acid as a catalyst, 1,1,3,3-tetramethyldisiloxane was added, and the reaction was carried out under insulation for 10 h. The solvent was removed by reduced pressure distillation to obtain intermediate A, where the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane was 2:1.

[0046] S2: Diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were dispersed in deionized water, and the temperature was raised to 85 °C by stirring in an oil bath. Paraformaldehyde was added in 3 portions at intervals of 5 min; after the addition of paraformaldehyde was completed, the reaction was carried out under reflux with insulation for 75 min, and impurities were removed by vacuum rotary evaporation. The crude product was washed with absolute ethanol and then vacuum treated at 130 °C for 3 h to obtain intermediate B; among them, the molar ratio of diethanolamine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:1:1.5.

[0047] S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 10 min, then add intermediate B to the reaction system, react at 50 °C for 48 h, remove the solvent by rotary evaporation under reduced pressure, wash the product with boiling water, and dry to obtain the silicon-containing flame-retardant diol; wherein, the molar ratio of intermediate A to intermediate B is 1:2;

[0048] Step 2:

[0049] Dehydrate polytetrahydrofuran ether diol 2000 and the silicon-containing flame-retardant diol at 120 °C respectively; mix the dehydrated polytetrahydrofuran ether diol 2000 and the silicon-containing flame-retardant diol in a mass ratio of 3:1 to obtain a mixed diol; mix 100 g of the mixed diol, 10 g of dimethylolpropionic acid, and 138 g of isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 80 °C under a nitrogen atmosphere for 3 h, cool down to 60 °C, add 9 g of 1,4-butanediol, and continue to react at 70 °C for 2 h; then add 20 g of acetone to reduce the viscosity, add triethylamine to neutralize to a neutralization degree of 100%, add deionized water to emulsify for 10 min, add 4 g of ethylenediamine for chain extension reaction for 30 min, and evaporate acetone to obtain a modified polyurethane emulsion with a solid content of 40%;

[0050] Step 3:

[0051] Mix 50 g of the modified polyurethane emulsion, 15 g of deionized water, 0.5 g of wetting agent, 0.3 g of defoaming agent, 0.5 g of dispersant, 10 g of titanium dioxide, 4 g of barium sulfate powder, 3 g of zinc phosphate, 0.2 g of leveling agent, and 0.3 g of thickener by stirring to obtain a high-temperature resistant metal coating.

[0052] Comparative Example 1: Do not add the silicon-containing flame-retardant diol, and the other parameters are the same as in Example 1.

[0053] Step 1:

[0054] Dehydrate polytetrahydrofuran ether diol 2000 at 110 °C respectively; mix 100 g of polytetrahydrofuran ether diol 2000, 10 g of dimethylolpropionic acid, and 138 g of isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 70 °C under a nitrogen atmosphere for 2 h, cool down to 50 °C, add 9 g of 1,4-butanediol, and continue to react at 60 °C for 1 h; then add 20 g of acetone to reduce the viscosity, add triethylamine to neutralize to a neutralization degree of 100%, add deionized water to emulsify for 5 min, add 4 g of ethylenediamine for chain extension reaction for 30 min, and evaporate acetone to obtain a modified polyurethane emulsion with a solid content of 40%;

[0055] Step 2:

[0056] Mix 50 g of modified polyurethane emulsion, 15 g of deionized water, 0.5 g of wetting agent, 0.3 g of defoamer, 0.5 g of dispersant, 10 g of titanium dioxide, 4 g of barium sulfate powder, 3 g of zinc phosphate, 0.2 g of leveling agent, and 0.3 g of thickener by stirring to obtain a high-temperature resistant metal coating.

[0057] Comparative Example 2: React intermediate A and intermediate B in a molar ratio of 1:1, and the remaining parameters are the same as in Example 2.

[0058] Step 1:

[0059] S1: Disperse acrylic acid and inhibitor in deionized water, heat to 65 °C, under argon protection, use an isopropanol solution of chloroplatinic acid as a catalyst, add 1,1,3,3-tetramethyldisiloxane, keep the temperature for reaction for 9 h, and remove the solvent by reduced pressure distillation to obtain intermediate A, where the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1;

[0060] S2: Take diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and disperse them in deionized water. After stirring and heating the oil bath to 80 °C, add paraformaldehyde in 3 portions at intervals of 4 min each; after the paraformaldehyde is added, keep the temperature for reflux reaction for 70 min, remove impurities by vacuum rotary evaporation, obtain a crude product, wash it with absolute ethanol, and then vacuum treat it at 125 °C for 2.5 h to obtain intermediate B; among them, the molar ratio of diethanolamine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.5;

[0061] S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 8 min, then add intermediate B to the reaction system, react at 45 °C for 48 h, remove the solvent by reduced pressure rotary evaporation, wash the product with boiling water, and dry to obtain a silicon-containing flame retardant; among them, the molar ratio of intermediate A to intermediate B is 1:1;

[0062] Step 2:

[0063] Poly(tetramethylene ether) glycol 2000 and a silicon-containing flame retardant were dehydrated separately at 115 °C; the dehydrated poly(tetramethylene ether) glycol 2000 and the silicon-containing flame retardant diol were mixed at a mass ratio of 3.5:1 to obtain a mixed polyol; 100 g of the mixed polyol, 10 g of dimethylolpropionic acid, and 138 g of isophorone diisocyanate were mixed, and dibutyltin dilaurate was used as a catalyst to react at 75 °C in a nitrogen environment for 2.5 h. The temperature was lowered to 55 °C, 9 g of 1,4-butanediol was added, and the temperature was raised to 65 °C and the reaction continued for 1.5 h; then 20 g of acetone was added to reduce the viscosity, triethylamine was added to neutralize to 100% neutralization degree, deionized water was added for emulsification for 8 min, and then 4 g of ethylenediamine was added for chain extension reaction for 30 min. Acetone was distilled off to obtain a modified polyurethane emulsion with a solid content of 40%.

[0064] Step 3:

[0065] 50 g of the modified polyurethane emulsion, 15 g of deionized water, 0.5 g of wetting agent, 0.3 g of defoaming agent, 0.5 g of dispersant, 10 g of titanium dioxide, 4 g of barium sulfate powder, 3 g of zinc phosphate, 0.2 g of leveling agent, and 0.3 g of thickener were mixed and stirred to obtain a high-temperature resistant metal coating.

[0066] Comparative Example 3: Increase the content of the silicon-containing flame retardant diol in the mixed diol, and the other parameters are the same as those in Example 1.

[0067] Step 1:

[0068] S1: Acrylic acid and an inhibitor were dispersed in deionized water, heated to 70 °C, and under argon protection, using an isopropanol solution of chloroplatinic acid as a catalyst, 1,1,3,3-tetramethyldisiloxane was added, and the reaction was carried out under insulation for 10 h. The solvent was removed by distillation under reduced pressure to obtain intermediate A, where the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane was 2:1;

[0069] S2: Diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were dispersed in deionized water. After stirring and heating the oil bath to 85 °C, paraformaldehyde was added in 3 portions at intervals of 5 min; after the addition of paraformaldehyde was complete, the reaction was carried out under reflux with insulation for 75 min, and impurities were removed by vacuum rotary evaporation. The crude product was washed with absolute ethanol and then vacuum-treated at 130 °C for 3 h to obtain intermediate B; among them, the molar ratio of diethanolamine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was 1:1:1.5;

[0070] S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 10 min, then add intermediate B to the reaction system, react at 50 °C for 48 h, rotary evaporate the solvent under reduced pressure, wash the product with boiling water, and dry to obtain a silicon-containing flame-retardant diol; wherein, the molar ratio of intermediate A to intermediate B is 1:2;

[0071] Step 2:

[0072] Dehydrate polytetrahydrofuran ether diol 2000 and the silicon-containing flame-retardant diol at 120 °C respectively; mix the dehydrated polytetrahydrofuran ether diol 2000 and the silicon-containing flame-retardant diol according to a mass ratio of 2:1 to obtain a mixed diol; mix 100 g of the mixed diol, 10 g of dimethylolpropionic acid, and 138 g of isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 80 °C under a nitrogen atmosphere for 3 h, cool down to 60 °C, add 9 g of 1,4-butanediol, and continue to react at 70 °C for 2 h; then add 20 g of acetone to reduce the viscosity, add triethylamine to neutralize to 100% neutralization degree, add deionized water to emulsify for 10 min, add 4 g of ethylenediamine for chain extension reaction for 30 min, and distill off acetone to obtain a modified polyurethane emulsion with a solid content of 40%;

[0073] Step 3:

[0074] Mix 50 g of the modified polyurethane emulsion, 15 g of deionized water, 0.5 g of wetting agent, 0.3 g of defoaming agent, 0.5 g of dispersant, 10 g of titanium dioxide, 4 g of barium sulfate powder, 3 g of zinc phosphate, 0.2 g of leveling agent, and 0.3 g of thickener by stirring to obtain a high-temperature resistant metal coating.

[0075] Experiment: Test the performance of the high-temperature resistant metal coatings prepared in Examples 1-3 and Comparative Examples 1-3.

[0076] Water resistance: Coat the high-temperature resistant metal coating on the surface of a stainless steel plate, cure to form a coating with a thickness of 100 μm, immerse the steel plate in clear water (25 °C) for 7 days, and observe the surface morphology of the coating.

[0077] Adhesion performance: Coat the high-temperature resistant metal coating on the surface of a stainless steel plate, cure to form a coating with a thickness of 100 μm, and refer to GB / T 9286–2021 to test the adhesion performance by the cross-cut method.

[0078] Flame retardancy: Coat the high-temperature resistant metal coating on the surface of a polytetrafluoroethylene plate, cure and then peel off, and test the limiting oxygen index.

[0079] Thermal decomposition performance: In an air atmosphere, use a thermogravimetric analyzer to test, with a heating rate of 10 °C / min and a temperature range of 30-600 °C, test the temperature at which the thermal weight loss is 20%, denoted as Td20% 。

[0080] The experimental results are shown in Table 1.

[0081] Table 1. Test results of various properties of the high-temperature resistant metal coating

[0082]

[0083] Conclusion: Any of the data in Examples 1-3 and Comparative Examples 1-3 shows that the metal coating prepared by the present invention has good performance. The data of Example 1 and Comparative Example 1 show that after adding the silicon-containing flame retardant diol, the water resistance, flame retardancy and heat resistance of the coating are improved; the data of Example 2 and Comparative Example 2 show that when intermediate A and intermediate B react in a molar ratio of 1:1, the reaction product of the two is an irregular polymer, thus affecting the performance of the coating; the data of Example 3 and Comparative Example 3 show that after increasing the dosage of the silicon-containing flame retardant diol, the stability of the coating is reduced, resulting in poor film-forming performance of the coating.

[0084] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation process of a high-temperature resistant metal coating, characterized in that: It includes the following steps: Step 1: Dehydrate polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol at 110-120°C respectively; Mix the dehydrated polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol to obtain a mixed diol; mix the mixed diol, dimethylolpropionic acid, and isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 70-80°C under a nitrogen atmosphere for 2-3 h, cool down to 50-60°C, add 1,4-butanediol, and heat up to 60-70°C to continue the reaction for 1-2 h; then add 20-30 parts by weight of acetone to reduce the viscosity, add triethylamine to neutralize to 100% neutralization degree, add deionized water to emulsify for 5-10 min, add ethylenediamine for chain extension reaction for 30 min, and evaporate acetone to obtain a modified polyurethane emulsion with a solid content of 30-40%; Step 2: Mix and stir the modified polyurethane emulsion, deionized water, wetting agent, defoaming agent, dispersant, titanium dioxide, barium sulfate powder, zinc phosphate, leveling agent, and thickening agent to obtain a high-temperature resistant metal coating; The preparation method of the silicon-containing flame retardant diol is as follows: S1: Disperse acrylic acid and inhibitor in deionized water, heat to 60-70°C, under argon protection, use an isopropanol solution of chloroplatinic acid as a catalyst, add 1,1,3,3-tetramethyldisiloxane, keep the temperature for reaction for 8-10 h, and evaporate the solvent under reduced pressure to obtain intermediate A; S2: Take diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and disperse them in deionized water, stir and heat the oil bath to 70-85°C, then add paraformaldehyde in 2-3 portions at intervals of 3-5 min each; after adding paraformaldehyde completely, keep the temperature for reflux reaction for 60-75 min, remove impurities by vacuum rotary evaporation, obtain a crude product, wash it with absolute ethanol, and vacuum treat it at 120-130°C for 2-3 h to obtain intermediate B; there are two hydroxyl groups in intermediate B; S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 5-10 min, then add intermediate B to the reaction system, react at 40-50°C for 48 h, evaporate the solvent under reduced pressure by rotary evaporation, and wash and dry the product with boiling water; In S1, the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1; in S3, the molar ratio of intermediate A to intermediate B is 1:2; In Step 1, in the mixed diol, the mass ratio of polytetrahydrofuran ether diol 2000 to silicon-containing flame retardant diol is (3-4):

1.

2. The preparation process of a high-temperature resistant metal coating according to claim 1, characterized in that: In Step 1, when preparing the modified polyurethane emulsion, the dosage of each component, by weight, is 100 parts of mixed diol, 9-12 parts of dimethylolpropionic acid, 120-138 parts of isophorone diisocyanate, 7-11 parts of 1,4-butanediol, 20-30 parts of acetone, and 3-5 parts of ethylenediamine.

3. The preparation process of a high-temperature resistant metal coating according to claim 1, characterized in that: In step 2, the content of each component in the high temperature resistant metal coating is, by weight, 45 to 55 parts of modified polyurethane emulsion, 15 to 18 parts of deionized water, 0.3 to 0.5 parts of wetting agent, 0.1 to 0.3 parts of defoaming agent, 0.2 to 0.5 parts of dispersant, 8 to 10 parts of titanium dioxide, 4 to 5 parts of barium sulfate powder, 2 to 3 parts of zinc phosphate, 0.1 to 0.3 parts of leveling agent, and 0.1 to 0.3 parts of thickener.

4. The high temperature resistant metallic coating prepared by the preparation process according to any one of claims 1 to 3.

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