High-temperature-resistant coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and discloses a high-temperature-resistant coating and a preparation method thereof.The preparation method comprises the steps that epoxy resin, filler, a dispersing agent and a defoaming agent are added into a solvent, a curing agent is added after stirring, and the high-temperature-resistant coating is obtained. The curing agent is composed of a polyamide curing agent and UPy diaminodiphenyl sulfone; the UPy structure forms a stable quadruple hydrogen bond action on an epoxy resin molecular chain bond, the crosslinking density of the epoxy resin is improved, and when the epoxy resin is stressed, the quadruple hydrogen bond can absorb energy to break, consume stress and transfer energy, so that a coating cured product is not damaged by the stress and has a very good toughening effect; the toughness of the paint film is improved. A heat-resistant diphenyl sulfone structure is introduced into an epoxy resin molecular chain, so that the high-temperature resistance of the coating is improved, and the coating has higher thermal decomposition temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a high-temperature-resistant coating and a preparation method thereof. BACKGROUND

[0002] Epoxy resin coatings are widely used in floor, pipeline, automobile, ship and other aspects. Although epoxy resin has good acid and alkali resistance, corrosion resistance and mechanical strength, its toughness is poor, the paint film is easy to crack, which will affect the protective effect of the coating, and the high-temperature resistance of epoxy resin is poor, which limits the practical application of epoxy resin coatings.

[0003] The curing agent of epoxy resin mainly includes amine curing agent, acid anhydride curing agent and the like, which has a great influence on the performance of epoxy resin and its coating. For example, polyamide curing agent can improve the toughness of epoxy resin, but it is difficult to improve its heat resistance and other properties; 4,4'-diamino diphenyl sulfone can improve the heat resistance of epoxy resin, but it cannot improve its toughness. The patent with publication number CN113185899B discloses a preparation method of an epoxy coating with room temperature self-repairing function, which uses a polyamide with a reversible tetrahydrogen bond group in a branched chain as a curing agent to improve the self-repairing, corrosion resistance and other properties of the epoxy resin coating. However, the patent does not solve the problem of poor high-temperature resistance and toughness of the epoxy resin coating. SUMMARY

[0004] (I) The technical problem solved by the present application is that the present application solves the problem of poor high-temperature resistance and toughness of the epoxy resin coating.

[0005] (II) Technical solution: A high-temperature-resistant coating, by weight, the high-temperature-resistant coating comprises 100 parts of epoxy resin, 18-30 parts of filler, 1-1.6 parts of dispersing agent, 0.7-1.2 parts of defoaming agent, 40-47 parts of curing agent; the curing agent is composed of 23-41 parts of polyamide curing agent and 6-15 parts of UPy diamino diphenyl sulfone.

[0006] The preparation method of the high-temperature-resistant coating comprises the following steps: adding a solvent and an epoxy resin into a container, stirring, then adding a filler, a dispersing agent and a defoaming agent, stirring, then adding a curing agent to obtain a high-temperature-resistant coating.

[0007] Preferably, the filler includes any one or combination of silicon powder, silicon carbide powder, aluminum oxide powder, corundum powder and zinc oxide.

[0008] Preferably, the solvent is any one or combination of n-butanol, ethyl acetate, toluene and xylene.

[0009] Preferably, the preparation method of the UPy diamino diphenyl sulfone comprises the following steps: Step (1) 2-amino-4-hydroxy-6-methyl pyrimidine and hexamethylene diisocyanate are reacted to obtain Upy-HDI; then Upy-HDI and 3,3'-dinitro-4,4'-dihydroxy diphenyl sulfone are added to a reaction solvent, and reacted at 40-90 DEG C for 2-5 h under a nitrogen atmosphere, distilled under reduced pressure, and the crude product is separated by silica gel column chromatography to obtain UPy dinitro diphenyl sulfone.

[0010] Step (2) ethanol, hydrazine hydrate solution, UPy dinitro diphenyl sulfone and palladium-carbon catalyst are added to 1,4-dioxane, and reacted at 60-70 DEG C for 24-30 h under a nitrogen atmosphere, the filtrate is distilled under reduced pressure after filtration, and the crude product is separated by silica gel column chromatography to obtain UPy diamino diphenyl sulfone.

[0011] Preferably, the amount of 3,3'-dinitro-4,4'-dihydroxy diphenyl sulfone in step (1) is 100 parts, and the amount of Upy-HDI is 172-190 parts by weight.

[0012] Preferably, the reaction solvent in step (1) is dichloromethane or toluene.

[0013] Preferably, the amount of UPy dinitro diphenyl sulfone in step (2) is 100 parts, and the amount of palladium-carbon catalyst is 1.6-2.2 parts by weight.

[0014] Preferably, the volume ratio of 1,4-dioxane, ethanol and hydrazine hydrate solution in step (2) is (100-150):100:(20-30).

[0015] (Three) beneficial technical effects: the UPy diamino diphenyl sulfone of the present application contains multiple amino groups, can replace part of the polyamide curing agent, and has a curing reaction with the epoxy resin coating, introduces the UPy structure and the diphenyl sulfone structure into the epoxy resin molecular chain, the UPy structure forms stable quadruple hydrogen bond action in the epoxy resin molecular chain bond, improves the crosslinking density of the epoxy resin, when the epoxy resin is stressed, the quadruple hydrogen bond can absorb energy and break at the same time, can consume stress and transmit energy, so that the coating curing product is not damaged by stress, has good toughening effect, and improves the toughness of the paint film.

[0016] The present application introduces the heat-resistant diphenyl sulfone structure into the epoxy resin molecular chain, which is beneficial to improve the high temperature resistance of the coating, and has a higher thermal decomposition temperature. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0018] The epoxy resin model below is E51; the polyamide curing agent model is polyamide 650. The CAS number of 3,3'-dinitro-4,4'-dihydroxy diphenyl sulfone is 7149-20-4; the CAS number of 3,3'-dinitro-[1,1'-biphenyl]-4,4'-diol is 66041-61-0.

[0019] Embodiment 1

[0020] Step (1), 50g Upy-HDI, 86g 3,3'-dinitro-4,4'-dihydroxy diphenyl sulfone are added to 1.2L dichloromethane, refluxed at 40℃ for 5h under a nitrogen atmosphere, distilled under reduced pressure, and the crude product is separated by silica gel column chromatography with dichloromethane and methanol mixed solution as the eluent to obtain UPy dinitro diphenyl sulfone. The preparation reaction formula is: .

[0021] Step (2), 0.8L ethanol, 180mL hydrazine hydrate solution (mass fraction 80%), 70g UPy dinitro diphenyl sulfone, 1.12g palladium-carbon catalyst are added to 1L 1,4-dioxane, refluxed at 70℃ for 24h under a nitrogen atmosphere, the nitro group is reduced to amino group, after filtration, the filtrate is distilled under reduced pressure, and the crude product is separated by silica gel column chromatography with dichloromethane and methanol mixed solution as the eluent to obtain UPy diamino diphenyl sulfone. The structural formula is: .

[0022] Step (3), 100mL ethyl acetate, 120mL dimethylbenzene, 1kg epoxy resin are added to a container, after stirring, 160g silicon powder, 80g zinc oxide, 14g dispersant, 12g defoaming agent are added, after stirring, 410g polyamide curing agent and 60g UPy diamino diphenyl sulfone are added as the curing agent to obtain a high-temperature-resistant coating.

[0023] Embodiment 2

[0024] Step (1), 50g Upy-HDI, 95g 3,3'-dinitro-4,4'-dihydroxy diphenyl sulfone are added to 1L toluene, refluxed at 90℃ for 2h under a nitrogen atmosphere, distilled under reduced pressure, and the crude product is separated by silica gel column chromatography with dichloromethane and methanol mixed solution as the eluent to obtain UPy dinitro diphenyl sulfone.

[0025] Step (2), 0.8 L of 1,4-dioxane was added with 0.8 L of ethanol, 160 mL of hydrazine hydrate solution (mass fraction 80%), 70 g of UPy dinitro diphenyl sulfone, 1.57 g of palladium-carbon catalyst, under nitrogen atmosphere, refluxed at 70°C for 24 h, after filtration, the filtrate was distilled under reduced pressure, the crude product was separated by silica gel column chromatography, the eluent was a mixture of dichloromethane and methanol solution, to obtain UPy diamino diphenyl sulfone.

[0026] Step (3), 80 mL of n-butanol, 130 mL of toluene, 1 kg of epoxy resin were added to the container, after stirring, 130 g of silicon carbide powder, 170 g of alumina powder, 10 g of dispersant, 9 g of defoaming agent were added, after stirring, 330 g of polyamide curing agent and 100 g of UPy diamino diphenyl sulfone were added as curing agent, to obtain a high temperature resistant coating.

[0027] Example 3

[0028] Step (1), 50 g of Upy-HDI, 93 g of 3,3'-dinitro-4,4'-dihydroxy diphenyl sulfone were added to 1 L of toluene, under nitrogen atmosphere, refluxed at 90°C for 3 h, distilled under reduced pressure, the crude product was separated by silica gel column chromatography, the eluent was a mixture of dichloromethane and methanol solution, to obtain UPy dinitro diphenyl sulfone.

[0029] Step (2), 0.8 L of 1,4-dioxane was added with 0.8 L of ethanol, 240 mL of hydrazine hydrate solution (mass fraction 80%), 70 g of UPy dinitro diphenyl sulfone, 1.34 g of palladium-carbon catalyst, under nitrogen atmosphere, refluxed at 60°C for 30 h, after filtration, the filtrate was distilled under reduced pressure, the crude product was separated by silica gel column chromatography, the eluent was a mixture of dichloromethane and methanol solution, to obtain UPy diamino diphenyl sulfone.

[0030] Step (3), 100 mL of ethyl acetate, 120 mL of xylene, 1 kg of epoxy resin were added to the container, after stirring, 140 g of silicon powder, 40 g of corundum powder, 16 g of dispersant, 7 g of defoaming agent were added, after stirring, 230 g of polyamide curing agent and 150 g of UPy diamino diphenyl sulfone were added as curing agent, to obtain a high temperature resistant coating.

[0031] Comparative Example 1: Step (1), 100 mL of ethyl acetate, 120 mL of xylene, 1 kg of epoxy resin were added to the container, after stirring, 160 g of silicon powder, 80 g of zinc oxide, 14 g of dispersant, 12 g of defoaming agent were added, after stirring, 410 g of polyamide curing agent was added, to obtain a coating.

[0032] Comparative Example 2: Step (1), UPy dinitro diphenyl sulfone was prepared by the method of Example 1.

[0033] Step (2), 100 mL of ethyl acetate, 120 mL of xylene, 1 kg of epoxy resin were added to a container, after stirring, 160 g of silica powder, 80 g of zinc oxide, 14 g of dispersant, 12 g of defoaming agent were added, after stirring, 410 g of polyamide curing agent and 60 g of UPy dinitro diphenyl sulfone as curing agent were added to obtain a coating.

[0034] Comparative Example 3: Step (1), 100 mL of ethyl acetate, 120 mL of xylene, 1 kg of epoxy resin were added to a container, after stirring, 160 g of silica powder, 80 g of zinc oxide, 14 g of dispersant, 12 g of defoaming agent were added, after stirring, 410 g of polyamide curing agent and 60 g of 4,4'-diamino diphenyl sulfone as curing agent were added to obtain a coating.

[0035] Comparative Example 4: Step (1), 50 g of Upy-HDI, 86 g of 3,3'-dinitro-[1,1'-biphenyl]-4,4'-diol were added to 1.2 L of dichloromethane, refluxed at 40°C for 5 h under nitrogen atmosphere, distilled under reduced pressure, and the crude product was separated by silica gel column chromatography with dichloromethane and methanol mixed solution as eluent to obtain UPy dinitro biphenyl. The structure is as follows: .

[0036] Step (2), 0.8 L of ethanol, 180 mL of hydrazine hydrate solution (mass fraction 80%), 70 g of UPy dinitro diphenyl sulfone, 1.12 g of palladium on carbon catalyst were added to 1 L of 1,4-dioxane, refluxed at 70°C for 24 h under nitrogen atmosphere, filtered, and the filtrate was distilled under reduced pressure. The crude product was separated by silica gel column chromatography with dichloromethane and methanol mixed solution as eluent to obtain UPy diamino biphenyl. The structure is as follows: .

[0037] Step (3), 100 mL of ethyl acetate, 120 mL of xylene, 1 kg of epoxy resin were added to a container, after stirring, 160 g of silica powder, 80 g of zinc oxide, 14 g of dispersant, 12 g of defoaming agent were added, after stirring, 410 g of polyamide curing agent and 60 g of UPy diamino biphenyl as curing agent were added to obtain a coating.

[0038] The coating was sprayed on the surface of the tinplate, and then cured at 80°C for 1 h, 110°C for 2 h, and room temperature for 24 h. The flexibility of the paint film was tested according to the standard GB / T 1731-2020.

[0039] Take 6 mg of paint film, test the thermal performance in the thermal gravimetric analyzer, with a temperature rising rate of 5℃ / min from 25℃ to 800℃, and the test atmosphere is nitrogen.

[0040] Test the tensile properties of the paint cured product according to standard GB / T 1040.1-2018.

[0041] Table 1 Performance of the paint Compared with Comparative Example 1, UPy diaminodiphenyl sulfone is added in the epoxy resin paint of Example 1 to Example 3, which contains multiple amino groups, can replace part of the polyamide curing agent, and has a curing reaction with the epoxy resin, thereby introducing multiple UPy structures ( ) and diphenyl sulfone structures into the epoxy resin molecular chain. Multiple UPy structures form more stable quadruple hydrogen bonding in the epoxy resin molecular chain bond, improve the crosslinking density of the epoxy resin, and can make the epoxy resin maintain good tensile strength. When the epoxy resin is stressed, the quadruple hydrogen bond can also absorb energy and break, which has the effect of consuming stress and transmitting energy, so that the paint cured product is not damaged by stress, thereby having good toughening effect. The flexibility of the paint film is 0.5-1mm, and the elongation at break of the cured product reaches 18.3-33.7%. And the introduction of heat-resistant diphenyl sulfone structure in the epoxy resin molecular chain is conducive to improving the high temperature resistance of the paint, and has a higher thermal decomposition temperature.

[0042] The UPy dinitrodiphenyl sulfone of Comparative Example 2 does not contain amino groups, cannot have a curing reaction with the epoxy resin, and cannot introduce UPy structures and diphenyl sulfone structures into the epoxy resin molecular chain. The toughening effect is not good, the toughness of the coating is poor, and the thermal decomposition temperature is significantly lower than that of Example 1.

[0043] Comparative Example 3 added 4,4'-diaminodiphenyl sulfone, and the elongation at break of the epoxy resin was significantly lower than that of Example 1, and the toughness was poor.

[0044] The UPy diaminodiphenyl of Comparative Example 4 does not contain heat-resistant diphenyl sulfone structure, resulting in a significantly lower initial thermal decomposition temperature of the epoxy resin coating than Example 1, and poor high temperature resistance.

Claims

1. A high temperature resistant coating, characterized in that: The high temperature resistant coating comprises, by weight, 100 parts of epoxy resin, 18-30 parts of filler, 1-1.6 parts of dispersant, 0.7-1.2 parts of defoamer, and 40-47 parts of curing agent; The curing agent is composed of 23-41 parts of polyamide curing agent and 6-15 parts of UPy diaminodiphenyl sulfone; The structural formula of the UPy diaminodiphenyl sulfone is: 。 2. The high temperature resistant coating according to claim 1, characterized in that: The filler includes any one or a combination of silicon micropowder, silicon carbide micropowder, aluminum oxide micropowder, corundum powder, and zinc oxide.

3. The high temperature resistant coating according to claim 1, characterized in that: The preparation method of the UPy diaminodiphenyl sulfone comprises the following steps: Step (1) reacting 2-amino-4-hydroxy-6-methylpyrimidine and hexamethylene diisocyanate to obtain Upy-HDI; then adding Upy-HDI and 3,3'-dinitro-4,4'-dihydroxydiphenyl sulfone to a reaction solvent, reacting at 40-90° C. for 2-5 hours in a nitrogen atmosphere, performing vacuum distillation, and separating the crude product by silica gel column chromatography to obtain UPy dinitrodiphenyl sulfone; Step (2) adding ethanol, hydrazine hydrate solution, UPy dinitrodiphenyl sulfone and palladium-carbon catalyst to 1,4-dioxane, reacting at 60-70° C. for 24-30 hours in a nitrogen atmosphere, filtering and distilling the filtrate under reduced pressure, and separating the crude product by silica gel column chromatography to obtain UPy diaminodiphenyl sulfone.

4. The high temperature resistant coating according to claim 3, characterized in that: In terms of weight, the amount of 3,3'-dinitro-4,4'-dihydroxydiphenyl sulfone used in step (1) is 100 parts, and the amount of Upy-HDI is 172-190 parts.

5. The high temperature resistant coating according to claim 3, characterized in that: The reaction solvent in step (1) is dichloromethane or toluene.

6. The high temperature resistant coating according to claim 3, characterized in that: In terms of weight, the amount of UPy dinitrodiphenyl sulfone used in step (2) is 100 parts, and the amount of palladium-carbon catalyst is 1.6-2.2 parts.

7. The high temperature resistant coating according to claim 3, characterized in that: In step (2), the volume ratio of 1,4-dioxane, ethanol, and hydrazine hydrate solution is (100-150):100:(20-30).

8. A method for preparing a high temperature resistant coating according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: adding a solvent and an epoxy resin into a container, adding a filler, a dispersant, and a defoamer after stirring, and adding a curing agent after stirring to obtain a high-temperature resistant coating.

9. The method for preparing a high temperature resistant coating according to claim 8, characterized in that: The solvent is any one or a combination of n-butanol, ethyl acetate, toluene and xylene.

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