High-temperature-resistant metal coating and preparation process thereof

Abstract

The invention relates to the technical field of metal coatings, in particular to a high-temperature-resistant metal coating and a preparation process thereof. The preparation method comprises the following steps: firstly, preparing an intermediate A by taking acrylic acid and 1, 1, 3, 3-tetramethyldisiloxane as raw materials, and reacting diethanol amine, 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and paraformaldehyde to obtain an intermediate B; reacting the intermediate A and the intermediate B according to a molar ratio of 1: 2 to obtain silicon-containing flame-retardant dihydric alcohol; then mixing polytetrahydrofuran ether glycol 2000 and silicon-containing flame-retardant dihydric alcohol, then reacting with isophorone diisocyanate, and carrying out chain extension to obtain a modified polyurethane emulsion; the modified polyurethane emulsion, deionized water, a wetting agent, a defoaming agent, a dispersing agent, titanium dioxide, barium sulfate powder, zinc phosphate, a flatting agent and a thickening agent are mixed and stirred, and the high-temperature-resistant metal coating is obtained.

Description

Technical Field

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

[0002] Metal materials are a type of material that has properties such as luster, ductility, easy conductivity, and heat transfer. They are widely used in the fields of construction, manufacturing, transportation, aerospace, and electronic communications. Metal materials are easily corroded by the outside world during use, resulting in reduced mechanical properties and reduced service life. Therefore, it is necessary to coat the surface with paint to strictly separate the metal surface from the external medium and protect the metal from external corrosion.

[0003] Metallic coatings, also known as metallic paints, can not only protect the metal base from oxidation and rust, but also perform paint processing and color treatment to make the metal material more beautiful. However, most coatings are organic polymer materials, which are not resistant to high temperatures and are flammable, so 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 technology.

[0005] In order 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, comprising the following steps: Step 1: Dehydrating polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol at 110-120°C respectively; mixing the dehydrated polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol to obtain a mixed diol; mixing the mixed diol, dimethylol propionic acid and isophorone diisocyanate, reacting for 2-3 hours at 70-80°C and nitrogen environment with dibutyltin dilaurate as a catalyst, cooling to 50-60°C, adding 1,4-butanediol, heating to 60-70°C and continuing to react for 1-2 hours; subsequently adding 20-30 parts of acetone to reduce the viscosity, adding triethylamine to neutralize to a neutralization degree of 100%, adding deionized water for emulsification for 5-10 minutes, adding ethylenediamine to extend the chain for 30 minutes, and evaporating the acetone to obtain a modified polyurethane emulsion with a solid content of 30-40%; Step 2: 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.

[0006] Furthermore, in step 1, the preparation method of the silicon-containing flame retardant diol is: S1: Disperse acrylic acid and polymerization inhibitor in deionized water, heat to 60-70°C, add 1,1,3,3-tetramethyldisiloxane under argon protection with isopropanol solution of chloroplatinic acid as catalyst, keep warm for 8-10 hours, and evaporate the solvent under reduced pressure to obtain intermediate A; S2: Disperse diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in deionized water, stir in an oil bath and heat to 70-85°C, then add paraformaldehyde in 2-3 portions, each time with an interval of 3-5 minutes; after the addition of paraformaldehyde, keep the temperature under reflux for 60-75 minutes, remove impurities by vacuum rotary evaporation to obtain a crude product, wash with anhydrous ethanol, and vacuum treat at 120-130°C for 2-3 hours to obtain intermediate B; S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 5-10 minutes, add intermediate B to the reaction system, react at 40-50°C for 48 hours, remove the solvent by rotary evaporation under reduced pressure, wash the product with boiling water and dry it.

[0007] Furthermore, in S1, the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1.

[0008] Furthermore, in S2, the molar ratio of diethanolamine to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.5.

[0009] Furthermore, in S3, the molar ratio of intermediate A to intermediate B is 1:2.

[0010] Furthermore, in step 1, in the mixed diol, the mass ratio of polytetramethylene ether glycol 2000 and silicon-containing flame retardant diol is (3-4):1.

[0011] Furthermore, in step 1, when preparing the modified polyurethane emulsion, the amount of each component used, by weight, is 100 parts of mixed diols, 9 to 12 parts of dihydroxymethylpropionic acid, 120 to 138 parts of isophorone diisocyanate, 7 to 11 parts of 1,4-butanediol, 20 to 30 parts of acetone, and 3 to 5 parts of ethylenediamine.

[0012] Furthermore, in step 1, the solid content of the modified polyurethane emulsion is 30-40%.

[0013] 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.

[0014] 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.

[0015] 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

[0016] 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.

[0017] 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.

[0018] Embodiment 1: A high temperature resistant metal coating and a preparation process thereof, comprising the following steps: Step 1: S1: Disperse acrylic acid and a polymerization inhibitor in deionized water, heat to 60°C, use an isopropanol solution of chloroplatinic acid as a catalyst under argon protection, add 1,1,3,3-tetramethyldisiloxane, keep the temperature for 8 hours, and evaporate the solvent under reduced pressure to obtain an intermediate A, wherein the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1; S2: Disperse diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in deionized water, stir in an oil bath and heat to 70°C, then add paraformaldehyde twice, each time with an interval of 3 minutes; after the addition of paraformaldehyde, keep the temperature under reflux for 60 minutes, remove impurities by vacuum rotary evaporation to obtain a crude product, wash with anhydrous ethanol, and vacuum treat at 120°C for 2 hours to obtain intermediate B; wherein the molar ratio of diethanolamine to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.5; S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 5 minutes, add intermediate B to the reaction system, react at 40°C for 48 hours, remove the solvent by rotary evaporation under reduced pressure, wash the product with boiling water, and dry to obtain silicon-containing flame-retardant diol; wherein the molar ratio of intermediate A to intermediate B is 1:2; Step 2: 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 at a mass ratio of 4:1 to obtain a mixed diol; mix 100g of the mixed diol, 10g of dimethylol propionic acid, and 138g of isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 70°C and nitrogen environment for 2h, cool to 50°C, add 9g of 1,4-butanediol, and heat to 60°C to continue reacting for 1h; then add 20g of acetone to reduce the viscosity, add triethylamine to neutralize to 100% neutralization, add deionized water to emulsify for 5min, add 4g of ethylenediamine to extend the chain for 30min, and evaporate the acetone to obtain a modified polyurethane emulsion with a solid content of 40%; Step 3: 50 g of 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.

[0019] Embodiment 2: A high temperature resistant metal coating and a preparation process thereof, comprising the following steps: Step 1: S1: Disperse acrylic acid and a polymerization inhibitor in deionized water, heat to 65°C, use an isopropanol solution of chloroplatinic acid as a catalyst under argon protection, add 1,1,3,3-tetramethyldisiloxane, keep the temperature for 9 hours, and evaporate the solvent under reduced pressure to obtain an intermediate A, wherein the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1; S2: Disperse diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in deionized water, stir in an oil bath and heat to 80°C, then add paraformaldehyde in three portions, each with an interval of 4 minutes; after the addition of paraformaldehyde, keep the temperature under reflux for 70 minutes, remove impurities by vacuum rotary evaporation to obtain a crude product, wash with anhydrous ethanol, and vacuum treat at 125°C for 2.5 hours to obtain intermediate B; wherein the molar ratio of diethanolamine to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.5; S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 8 minutes, add intermediate B to the reaction system, react at 45°C for 48 hours, remove the solvent by rotary evaporation under reduced pressure, wash the product with boiling water, and dry to obtain silicon-containing flame-retardant diol; wherein the molar ratio of intermediate A to intermediate B is 1:2; Step 2: Dehydrate polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol at 115°C respectively; mix the dehydrated polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol at a mass ratio of 3.5:1 to obtain a mixed diol; mix 100g of the mixed diol, 10g of dimethylol propionic acid, and 138g of isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 75°C and nitrogen environment for 2.5h, cool to 55°C, add 9g of 1,4-butanediol, and heat to 65°C to continue reacting for 1.5h; then add 20g of acetone to reduce the viscosity, add triethylamine to neutralize to 100% neutralization, add deionized water to emulsify for 8min, add 4g of ethylenediamine to extend the chain for 30min, and evaporate the acetone to obtain a modified polyurethane emulsion with a solid content of 40%; Step 3: 50 g of 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.

[0020] Embodiment 3: A high temperature resistant metal coating and a preparation process thereof, comprising the following steps: Step 1: S1: Disperse acrylic acid and a polymerization inhibitor in deionized water, heat to 70°C, use an isopropanol solution of chloroplatinic acid as a catalyst under argon protection, add 1,1,3,3-tetramethyldisiloxane, keep the temperature for 10 hours, and evaporate the solvent under reduced pressure to obtain an intermediate A, wherein the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1; S2: Disperse diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in deionized water, stir in an oil bath and heat to 85°C, then add paraformaldehyde in three portions, each time with an interval of 5 minutes; after the addition of paraformaldehyde, keep the temperature under reflux for 75 minutes, remove impurities by vacuum rotary evaporation to obtain a crude product, wash with anhydrous ethanol, and vacuum treat at 130°C for 3 hours to obtain intermediate B; wherein the molar ratio of diethanolamine to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.5; S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 10 minutes, add intermediate B to the reaction system, react at 50°C for 48 hours, remove the solvent by rotary evaporation under reduced pressure, wash the product with boiling water, and dry to obtain silicon-containing flame-retardant diol; wherein the molar ratio of intermediate A to intermediate B is 1:2; Step 2: Dehydrate polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol at 120°C respectively; mix the dehydrated polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol in a mass ratio of 3:1 to obtain a mixed diol; mix 100g of the mixed diol, 10g of dimethylol propionic acid, and 138g of isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 80°C and nitrogen environment for 3h, cool to 60°C, add 9g of 1,4-butanediol, heat to 70°C and continue to react for 2h; then add 20g of acetone to reduce the viscosity, add triethylamine to neutralize to 100% neutralization, add deionized water for emulsification for 10min, add 4g of ethylenediamine to extend the chain for 30min, and evaporate the acetone to obtain a modified polyurethane emulsion with a solid content of 40%; Step 3: 50 g of 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.

[0021] Comparative Example 1: No silicon-containing flame retardant diol was added, and other parameters were the same as those in Example 1.

[0022] Step 1: Dehydrate polytetramethylene glycol 2000 at 110°C; mix 100g polytetramethylene glycol 2000, 10g dihydroxymethyl propionic acid and 138g isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 70°C and nitrogen environment for 2h, cool to 50°C, add 9g 1,4-butanediol, heat to 60°C and continue to react for 1h; then add 20g acetone to reduce viscosity, add triethylamine to neutralize to 100% neutralization, add deionized water to emulsify for 5min, add 4g ethylenediamine to extend the chain for 30min, and evaporate acetone to obtain a modified polyurethane emulsion with a solid content of 40%; Step 2: 50 g of 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.

[0023] Comparative Example 2: Intermediate A and intermediate B were reacted at a molar ratio of 1:1, and the other parameters were the same as those in Example 2.

[0024] Step 1: S1: Disperse acrylic acid and a polymerization inhibitor in deionized water, heat to 65°C, use an isopropanol solution of chloroplatinic acid as a catalyst under argon protection, add 1,1,3,3-tetramethyldisiloxane, keep the temperature for 9 hours, and evaporate the solvent under reduced pressure to obtain an intermediate A, wherein the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1; S2: Disperse diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in deionized water, stir in an oil bath and heat to 80°C, then add paraformaldehyde in three portions, each with an interval of 4 minutes; after the addition of paraformaldehyde, keep the temperature under reflux for 70 minutes, remove impurities by vacuum rotary evaporation to obtain a crude product, wash with anhydrous ethanol, and vacuum treat at 125°C for 2.5 hours to obtain intermediate B; wherein the molar ratio of diethanolamine to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.5; S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 8 minutes, add intermediate B to the reaction system, react at 45°C for 48 hours, remove the solvent by rotary evaporation under reduced pressure, wash the product with boiling water, and dry to obtain a silicon-containing flame retardant; wherein the molar ratio of intermediate A to intermediate B is 1:1; Step 2: Dehydrate polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant at 115°C respectively; mix the dehydrated polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol at a mass ratio of 3.5:1 to obtain a mixed polyol; mix 100g of the mixed polyol, 10g of dimethylol propionic acid, and 138g of isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 75°C and nitrogen environment for 2.5h, cool to 55°C, add 9g of 1,4-butanediol, and heat to 65°C to continue reacting for 1.5h; then add 20g of acetone to reduce the viscosity, add triethylamine to neutralize to 100% neutralization, add deionized water for emulsification for 8min, add 4g of ethylenediamine to extend the chain for 30min, and evaporate the acetone to obtain a modified polyurethane emulsion with a solid content of 40%; Step 3: 50 g of 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.

[0025] Comparative Example 3: The content of silicon-containing flame-retardant diol in the mixed diol was increased, and the other parameters were the same as those in Example 1.

[0026] Step 1: S1: Disperse acrylic acid and a polymerization inhibitor in deionized water, heat to 70°C, use an isopropanol solution of chloroplatinic acid as a catalyst under argon protection, add 1,1,3,3-tetramethyldisiloxane, keep the temperature for 10 hours, and evaporate the solvent under reduced pressure to obtain an intermediate A, wherein the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:1; S2: Disperse diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in deionized water, stir in an oil bath and heat to 85°C, then add paraformaldehyde in three portions, each time with an interval of 5 minutes; after the addition of paraformaldehyde, keep the temperature under reflux for 75 minutes, remove impurities by vacuum rotary evaporation to obtain a crude product, wash with anhydrous ethanol, and vacuum treat at 130°C for 3 hours to obtain intermediate B; wherein the molar ratio of diethanolamine to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.5; S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 10 minutes, add intermediate B to the reaction system, react at 50°C for 48 hours, remove the solvent by rotary evaporation under reduced pressure, wash the product with boiling water, and dry to obtain silicon-containing flame-retardant diol; wherein the molar ratio of intermediate A to intermediate B is 1:2; Step 2: Dehydrate polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol at 120°C respectively; mix the dehydrated polytetrahydrofuran ether diol 2000 and silicon-containing flame retardant diol in a mass ratio of 2:1 to obtain a mixed diol; mix 100g of the mixed diol, 10g of dimethylol propionic acid, and 138g of isophorone diisocyanate, use dibutyltin dilaurate as a catalyst, react at 80°C and nitrogen environment for 3h, cool to 60°C, add 9g of 1,4-butanediol, heat to 70°C and continue to react for 2h; then add 20g of acetone to reduce the viscosity, add triethylamine to neutralize to 100% neutralization, add deionized water for emulsification for 10min, add 4g of ethylenediamine to extend the chain for 30min, and evaporate the acetone to obtain a modified polyurethane emulsion with a solid content of 40%; Step 3: 50 g of 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.

[0027] Experiment: The performance of the high temperature resistant metallic coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested.

[0028] Water resistance: The high temperature resistant metal coating was applied on the surface of the stainless steel plate and cured to form a coating with a thickness of 100 μm. The steel plate was immersed in clean water (25°C) for 7 days and the surface morphology of the coating was observed.

[0029] Adhesion performance: The high temperature resistant metal coating is applied to the surface of the stainless steel plate and cured to form a coating with a thickness of 100 μm. With reference to GB / T 9286-2021, the adhesion performance is tested by the cross-cut method.

[0030] Flame retardant performance: Apply high temperature resistant metal coating on the surface of polytetrafluoroethylene plate, peel it off after curing, and test the limiting oxygen index.

[0031] Thermal decomposition performance: In air atmosphere, the test was performed using a thermogravimetric analyzer with a heating rate of 10°C / min and a temperature range of 30~600°C. The temperature at which the thermal weight loss was 20% was recorded as Td. 20% .

[0032] The experimental results are shown in Table 1.

[0033] Table 1. Test results of various properties of high temperature resistant metal coatings

[0034] Conclusion: The data of any one of Examples 1 to 3 and Comparative Examples 1 to 3 show 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 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 at a molar ratio of 1:1, the reaction product of the two is an irregular polymer, which affects the performance of the coating; the data of Example 3 and Comparative Example 3 show that after increasing the amount of silicon-containing flame retardant diol, the stability of the coating is reduced, and the film-forming performance of the derived coating is poor.

[0035] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation process of a high temperature resistant metal coating, characterized in that: The following steps are involved: Step 1: Dehydration of polytetramethylene glycol 2000 and silicon-containing flame retardant diol was performed at 110-120°C respectively; The dehydrated polytetrahydrofuran ether diol 2000 and the silicon-containing flame retardant diol are mixed to obtain a mixed diol; the mixed diol, dimethylol propionic acid and isophorone diisocyanate are mixed, dibutyltin dilaurate is used as a catalyst, and the mixture is reacted at 70-80°C and nitrogen environment for 2-3 hours, the temperature is lowered to 50-60°C, 1,4-butanediol is added, and the temperature is raised to 60-70°C to continue the reaction for 1-2 hours; then 20-30 parts of acetone are added to reduce the viscosity, triethylamine is added to neutralize to a neutralization degree of 100%, deionized water is added to emulsify for 5-10 minutes, ethylenediamine is added to extend the chain for 30 minutes, and the acetone is evaporated to obtain a modified polyurethane emulsion with a solid content of 30-40%; Step 2: 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.

2. The process for preparing a high temperature resistant metal coating according to claim 1, characterized in that: In step 1, the preparation method of silicon-containing flame retardant diol is: S1: Disperse acrylic acid and polymerization inhibitor in deionized water, heat to 60-70°C, add 1,1,3,3-tetramethyldisiloxane under argon protection with isopropanol solution of chloroplatinic acid as catalyst, keep warm for 8-10 hours, and evaporate the solvent under reduced pressure to obtain intermediate A; S2: Disperse diethanolamine and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in deionized water, stir in an oil bath and heat to 70-85°C, then add paraformaldehyde in 2-3 portions, each time with an interval of 3-5 minutes; after the addition of paraformaldehyde, keep the temperature under reflux for 60-75 minutes, remove impurities by vacuum rotary evaporation to obtain a crude product, wash with anhydrous ethanol, and vacuum treat at 120-130°C for 2-3 hours to obtain intermediate B; S3: Disperse intermediate A in tetrahydrofuran, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine under nitrogen protection, stir for 5-10 minutes, add intermediate B to the reaction system, react at 40-50°C for 48 hours, remove the solvent by rotary evaporation under reduced pressure, wash the product with boiling water and dry it.

3. The preparation process of a high temperature resistant metal coating according to claim 2, characterized in that: In S1, the molar ratio of acrylic acid to 1,1,3,3-tetramethyldisiloxane is 2:

1.

4. The process for preparing a high temperature resistant metal coating according to claim 2, characterized in that: In S2, the molar ratio of diethanolamine to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1:1.

5.

5. The process for preparing a high temperature resistant metal coating according to claim 2, characterized in that: In S3, the molar ratio of intermediate A to intermediate B is 1:

2.

6. The process for preparing a high temperature resistant metal coating according to claim 2, characterized in that: In step 1, in the mixed diol, the mass ratio of polytetramethylene ether diol 2000 and the silicon-containing flame retardant diol is (3-4):

1.

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

8. The process for preparing a high temperature resistant metal coating according to claim 2, characterized in that: In step 1, the solid content of the modified polyurethane emulsion is 30-40%.

9. The process for preparing 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.

10. The high temperature resistant metallic coating prepared by the preparation process according to any one of claims 1 to 9.

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