Coating, preparation method and application thereof, and coated product

Abstract

The invention discloses a coating as well as a preparation method and application thereof and a coated product. According to the coating provided by the invention, the epoxy resin is cured by utilizing the polysilazane compound, so that the corrosion resistance and the high-temperature resistance of the coating can be remarkably improved: the main chain of the polysilazane compound contains an N-H bond, so that the curing reaction of the epoxy resin can be promoted, and the crosslinking density of the epoxy resin is improved; a side group contains at least one of a benzene ring and a naphthalene ring, the overall temperature resistance of an epoxy resin cured product is improved through a skeleton conjugation effect, and the side group contains a C1-C10 long straight-chain alkane group which can also provide better processability for polysilazane. The epoxy resin is obtained by reasonably proportioning bisphenol A epoxy resin, novolac epoxy resin and hyperbranched epoxy resin, and the crosslinking degree of the resin can be increased, so that the thermal stability of the resin is improved. A coating layer formed by the coating has the characteristics of high density, high heat resistance, high moisture resistance and high adhesion, and can meet the requirements of extreme environments such as high humidity and heat, salt spray corrosion and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a coating, a preparation method and application thereof, and a coated product. Background Art

[0002] Epoxy resin is an important thermosetting resin with good comprehensive properties, including excellent mechanical properties, electrical insulation properties, chemical resistance and adhesion, which also makes it widely used in coatings, adhesives, electronic device packaging, aerospace, microelectronic materials and other fields. The coating with epoxy resin as the main film-forming substance is called epoxy resin coating. Epoxy resin coating is one of the most widely used protective coatings. The coating formed by it not only has a shielding effect on corrosive media, but also can passivate the protected metal and play an electrochemical role.

[0003] In the related art, epoxy resin coatings cured with ordinary curing agents have problems such as poor moisture-thermal stability, poor dielectric properties, and low high-temperature residual mass fraction due to the presence of water-absorbent hydroxyl groups in their cross-linked network structure, which limits their application in extremely harsh environments such as high humidity and heat, salt spray corrosion, etc.

[0004] Therefore, it is an urgent problem to provide a coating material that can be used in extremely harsh environments such as high humidity, heat, and salt spray corrosion, and has good corrosion resistance and high temperature resistance. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a coating and a preparation method and application thereof, and a coated product, which aims to solve the problem that epoxy resin coatings cured by common curing agents are difficult to meet the application requirements in extremely harsh environments such as high humidity and heat, salt spray corrosion, etc.

[0006] The embodiment of the first aspect of the present invention provides a coating, wherein the raw material components of the coating include, by weight: 70 to 240 parts of an epoxy resin composition and 1 to 100 parts of a polysilazane compound;

[0007] The epoxy resin composition comprises 20 to 100 parts of bisphenol A epoxy resin, 10 to 40 parts of novolac epoxy resin, and 40 to 100 parts of hyperbranched epoxy resin;

[0008] The main chain of the polysilazane compound contains NH covalent bonds, and the side chain contains C 1 ~C 10 At least one of a straight-chain alkyl group, a phenyl group and a naphthyl group.

[0009] The coating according to the embodiment of the first aspect of the present invention has at least the following beneficial effects: the coating provided by the present invention can significantly improve the corrosion resistance, salt spray resistance and high temperature resistance of the coating by curing the epoxy resin with a polysilazane compound: on the one hand, the main chain of the polysilazane compound contains an NH bond, and the secondary amine and the epoxy group can undergo a ring-opening reaction to promote the curing of the epoxy resin. At the same time, the silicon secondary amine will be hydrolyzed to produce silicon primary amine, which will continue to promote the curing reaction of the epoxy resin and increase the crosslinking density of the epoxy resin; on the other hand, the polysilazane compound molecules can react with the metal cations (such as Fe) of the metal substrate through the N atom. 3+ ) forms a coordination effect, increases the surface interaction between the epoxy resin and the metal interface, and improves the adhesion of the epoxy resin to the metal substrate; finally, the side groups of the polysilazane contain at least one of a benzene ring and a naphthalene ring, which can improve the overall temperature resistance of the epoxy resin cured product through the skeleton conjugation effect, and ultimately improve the overall performance of the epoxy resin coating at high temperatures, and the C1-C10 long straight-chain alkane groups contained in the side groups can also provide polysilazane with better processing performance. In addition, in the coating component of the present invention, the epoxy resin is obtained by a reasonable ratio of bisphenol A epoxy resin, phenolic epoxy resin, and hyperbranched epoxy resin, which can increase the crosslinking degree of the resin and thus improve the thermal stability of the resin. Finally, the present invention proposes a silicone-modified epoxy resin coating with excellent high temperature resistance, good adhesion and protection to metal substrates. The coating utilizes polysilazane compounds to cure the epoxy resin, which can significantly improve the corrosion resistance and high temperature resistance of the coating. The coating formed by the above coating has the characteristics of high density, high heat and moisture resistance, and strong adhesion, and can meet the application requirements of extremely harsh environments such as high humidity and heat, and salt spray corrosion.

[0010] In some embodiments of the present invention, the raw material components of the coating include, by weight: 105 to 170 parts of epoxy resin composition and 15 to 30 parts of polysilazane compound.

[0011] In some embodiments of the present invention, the epoxy resin composition comprises, by weight, 50 to 85 parts of bisphenol A epoxy resin, 15 to 35 parts of novolac epoxy resin and 40 to 50 parts of hyperbranched epoxy resin.

[0012] In some embodiments of the present invention, the structural formula of the polysilazane compound is:

[0013]

[0014] Among them, R 1 Independently selected from C 1 ~C 10 A straight chain alkyl group;

[0015] R 2At least one independently selected from phenyl and naphthyl;

[0016] The value range of n is 700 to 1500.

[0017] In some embodiments of the present invention, the bisphenol A epoxy resin is selected from at least one of E51 epoxy resin, E44 epoxy resin, E20 epoxy resin and E12 epoxy resin.

[0018] In some embodiments of the present invention, the novolac epoxy resin is selected from at least one of F51 epoxy resin and NPCN-704 epoxy resin.

[0019] In some embodiments of the present invention, the hyperbranched epoxy resin is selected from at least one of AFG-90 epoxy resin, AFG-90H epoxy resin, AG-80 epoxy resin, AG-70 epoxy resin, AG-601 epoxy resin and AG-602 epoxy resin.

[0020] In some embodiments of the present invention, the raw material components of the coating further include: 0.1 to 100 parts of filler, by weight.

[0021] In some embodiments of the present invention, the filler is selected from at least one of carbon black, graphite, carbon nanotubes, activated carbon, alumina, silica, mica, boron nitride, calcium silicate, benzoin, titanium dioxide, MXene, glass microspheres, quartz sand, iron powder, iron salt, cobalt chloride, nickel chloride, iron oxide, ferrous oxide, cobalt oxide, nickel oxide, sodium tripolyphosphate, mica iron oxide, aluminum phosphate, glass flakes, zinc phosphate and calcium phosphate.

[0022] The embodiment of the second aspect of the present invention provides a method for preparing the coating as described above, comprising the steps of: mixing the raw materials according to weight components, heating and curing, and grinding and screening to obtain epoxy resin sintered powder.

[0023] The preparation method according to the embodiment of the second aspect of the present invention has at least the following beneficial effects: the preparation method of the coating provided by the present invention has a simple process, mild reaction conditions, easy operation, high production efficiency, and is suitable for large-scale production applications.

[0024] In some embodiments of the present invention, the heating and curing process is: heating to 100-280° C. and curing for 15-60 minutes.

[0025] In some embodiments of the present invention, the heating curing process is gradient temperature rise curing, which includes two stages: heating to 100-230° C. for curing for 15-30 min, and then heating to 230-280° C. for curing for 15-30 min.

[0026] An embodiment of the third aspect of the present invention provides the use of the coating as described above or the coating prepared by the preparation method as described above in coating of a metal substrate.

[0027] According to the application of the third aspect of the embodiment of the present invention, there are at least the following beneficial effects: the present invention applies the obtained coating to the coating of the metal substrate, and the formed coating has the characteristics of high density, high heat and moisture resistance, and strong adhesion, and can be used in extremely harsh environments such as high humidity and heat, salt spray corrosion, etc.

[0028] In some embodiments of the present invention, the metal substrate includes a single metal or a metal alloy.

[0029] An embodiment of the fourth aspect of the present invention provides an anti-corrosion coating, wherein the coating as described above or the coating prepared by the preparation method as described above is uniformly coated on the surface of a metal substrate, and the anti-corrosion coating is obtained after curing.

[0030] The anti-corrosion coating according to the fourth aspect of the embodiment of the present invention has at least the following beneficial effects: the present invention applies the above-mentioned coating to a metal substrate, and the formed coating has the characteristics of high density, high heat and moisture resistance, and strong adhesion, and can be used in extremely harsh environments such as high humidity and heat, salt spray corrosion, etc.

[0031] An embodiment of the fifth aspect of the present invention provides a coated product, comprising a metal substrate and the coating as described above or the coating prepared by the preparation method as described above, coated on the metal substrate.

[0032] In some embodiments of the present invention, the metal substrate includes a single metal or a metal alloy.

[0033] An embodiment of the sixth aspect of the present invention provides the use of the above-mentioned coating or the above-mentioned anti-corrosion coating in the fields of home appliance manufacturing, aerospace, and automobile manufacturing.

[0034] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0036] Figure 1 is a DSC spectrum of the epoxy resin prepolymer before curing in Example 1 of the present invention;

[0037] Figure 2This is the DSC spectrum of the epoxy resin coating cured by polysilazane in Example 1 of the present invention;

[0038] Figure 3 FTIR spectrum of the epoxy resin prepolymer before curing in Example 1 of the present invention;

[0039] Figure 4 This is the FTIR spectrum of the epoxy resin coating cured by polysilazane in Example 1 of the present invention;

[0040] Figure 5 is a TGA curve of the epoxy resin coating cured by polysilazane in Example 1 of the present invention in air atmosphere;

[0041] Figure 6 This is the TGA curve of the epoxy resin coating cured by polysilazane in Example 1 of the present invention under argon atmosphere. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0043] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0044] In the description of the present invention, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. Unless otherwise specified, each reaction or operation step may be performed in sequence or not. Preferably, the reaction method of the present invention is performed in sequence.

[0045] If no specific techniques or conditions are specified in the following examples, the techniques or conditions described in the literature in the art or the product instructions are used. All reagents or instruments without manufacturer specified are conventional products that can be purchased commercially.

[0046] The first aspect of the present invention provides a coating, wherein the raw material components of the coating include, by weight: 70 to 240 parts of an epoxy resin composition and 1 to 100 parts of a polysilazane compound; wherein the epoxy resin composition includes 20 to 100 parts of a bisphenol A epoxy resin, 10 to 40 parts of a novolac epoxy resin, and 40 to 100 parts of a hyperbranched epoxy resin; the main chain of the polysilazane compound contains an NH covalent bond, and the side chain contains a C 1 ~C 10 At least one of a straight-chain alkyl group, a phenyl group and a naphthyl group.

[0047] The coating provided by the present invention utilizes a polysilazane compound to cure an epoxy resin, thereby significantly improving the corrosion resistance, salt spray resistance, and high temperature resistance of the coating: on the one hand, the main chain of the polysilazane compound contains an NH bond, and the secondary amine and the epoxy group can undergo a ring-opening reaction to promote the curing of the epoxy resin. At the same time, the silicon secondary amine will be hydrolyzed to produce silicon primary amine, which will continue to promote the curing reaction of the epoxy resin and increase the crosslinking density of the epoxy resin; on the other hand, the polysilazane compound molecules can react with the metal cations (such as Fe 3+ ) forms a coordination effect, increases the surface interaction between the epoxy resin and the metal interface, and improves the adhesion of the epoxy resin to the metal substrate; finally, the side groups of the polysilazane contain at least one of a benzene ring and a naphthalene ring, which can improve the overall temperature resistance of the epoxy resin cured product through the skeleton conjugation effect, and ultimately improve the overall performance of the epoxy resin coating at high temperatures, and the C1-C10 long straight-chain alkane groups contained in the side groups can also provide polysilazane with better processing performance. In addition, in the coating component of the present invention, the epoxy resin is obtained by a reasonable ratio of bisphenol A epoxy resin, phenolic epoxy resin, and hyperbranched epoxy resin, which can increase the crosslinking degree of the resin and thus improve the thermal stability of the resin. Finally, the present invention proposes a silicone-modified epoxy resin coating with excellent high temperature resistance, good adhesion and protection to metal substrates. The coating utilizes polysilazane compounds to cure the epoxy resin, which can significantly improve the corrosion resistance and high temperature resistance of the coating. The coating formed by the above coating has the characteristics of high density, high heat and moisture resistance, and strong adhesion, and can meet the application requirements of extremely harsh environments such as high humidity and heat, and salt spray corrosion.

[0048] In some embodiments of the present invention, the raw material components of the coating include, by weight: 105-170 parts of epoxy resin composition and 15-30 parts of polysilazane compound. The present invention uses high temperature resistant polysilazane compound to cure epoxy resin, and the obtained organosilicon modified epoxy resin coating has excellent high temperature resistance, good adhesion and protection to metal substrates.

[0049] In some embodiments of the present invention, the epoxy resin composition includes 50-85 parts of bisphenol A epoxy resin, 15-35 parts of novolac epoxy resin and 40-50 parts of hyperbranched epoxy resin by weight. In the coating component of the present invention, the epoxy resin is obtained by reasonable proportioning of bisphenol A epoxy resin, novolac epoxy resin and hyperbranched epoxy resin, which can increase the crosslinking degree of the resin and thus improve the thermal stability of the resin.

[0050] In some embodiments of the present invention, the structural formula of the polysilazane compound is:

[0051]

[0052] Among them, R 1 Independently selected from C 1 ~C 10 A straight chain alkyl group;

[0053] R 2 At least one independently selected from phenyl and naphthyl;

[0054] The value range of n is 700 to 1500.

[0055] The high temperature resistant polysilazane compound of the present invention has an NH bond in the main chain, and the secondary amine and the epoxy group can undergo a ring-opening reaction to promote the curing of the epoxy resin. At the same time, the secondary amine of silicon can be hydrolyzed to produce primary amine of silicon, which further promotes the curing reaction of the epoxy resin and increases the crosslinking density of the epoxy resin. On the other hand, the polysilazane compound molecules can react with the metal cations (such as Fe 3+ ) forms a coordination effect, increases the surface interaction between the epoxy resin and the metal interface, and improves the adhesion of the epoxy resin to the metal substrate; finally, the side groups of the polysilazane contain at least one of a benzene ring and a naphthalene ring, which can improve the overall temperature resistance of the epoxy resin cured product through the skeleton conjugation effect, and ultimately improve the overall performance of the epoxy resin coating at high temperatures, and the C1-C10 long straight-chain alkane group contained in the side group can also provide better processing performance for the polysilazane.

[0056] In other embodiments of the present invention, the side chain of the polysilazane compound may also be a side chain containing an unsaturated bond, a fatty chain or other functional groups, but is not limited thereto.

[0057] In some specific embodiments of the present invention, the polysilazane compound is selected from at least one of XSC-N1501, XSC-N2501 and XSC-N0701 polysilazanes produced by Zhejiang Xinshichen New Materials Co., Ltd.

[0058] In some embodiments of the present invention, the bisphenol A epoxy resin is selected from at least one of E51 epoxy resin, E44 epoxy resin, E20 epoxy resin and E12 epoxy resin, but is not limited thereto, and may also be selected from common types in the art.

[0059] In some embodiments of the present invention, the phenolic epoxy resin is selected from at least one of F51 epoxy resin and NPCN-704 epoxy resin, but is not limited thereto, and may also be selected from common types in the art.

[0060] In some embodiments of the present invention, the hyperbranched epoxy resin is selected from at least one of AFG-90 epoxy resin, AFG-90H epoxy resin, AG-80 epoxy resin, AG-70 epoxy resin, AG-601 epoxy resin and AG-602 epoxy resin, but is not limited thereto and can also be selected from common models in the art.

[0061] In some embodiments of the present invention, the raw material components of the coating further include: 0.1 to 100 parts by weight, preferably 0.1 to 10 parts by weight of filler.

[0062] In some embodiments of the present invention, the filler is selected from at least one of carbon black, graphite, carbon nanotubes, activated carbon, aluminum oxide, silicon dioxide, mica, boron nitride, calcium silicate, benzoin, titanium dioxide, MXene, glass microspheres, quartz sand, iron powder, iron salt, cobalt chloride, nickel chloride, ferric oxide, ferrous oxide, cobalt oxide, nickel oxide, sodium tripolyphosphate, mica iron oxide, aluminum phosphate, glass flakes, zinc phosphate and calcium phosphate, preferably benzoin (benzoyl alcohol ketone). The addition of fillers can be used to regulate the bonding force of the resin adhesive, and / or high temperature resistance, and / or give the material other known excellent properties, and / or control costs. For example, benzoin in the filler can be used as a defoaming agent, silicon dioxide or aluminum oxide can be used as a reinforcing agent and a cost-reducing agent, and sodium tripolyphosphate, mica iron oxide, aluminum phosphate, glass flakes, zinc phosphate or calcium phosphate can be used as a rust remover. In the present invention, the raw material components of the coating may also include other additives, such as defoamers, leveling agents, thixotropic agents, coupling agents, anti-settling agents, dispersants, etc., and the above-mentioned defoamers, leveling agents, thixotropic agents, coupling agents, anti-settling agents, dispersants, etc. can be reasonably selected from any common types in the art according to actual conditions, and no limitation is made here.

[0063] The second aspect of the present invention provides a method for preparing the above-mentioned coating, comprising the steps of: mixing the raw materials according to weight components, heating and curing, and grinding and screening to obtain epoxy resin sintered powder.

[0064] The coating preparation method provided by the invention has simple processing technology, mild reaction conditions, easy operation, high production efficiency and is suitable for large-scale production application.

[0065] In some embodiments of the present invention, the heating and curing process is: heating to 100-280° C. and curing for 15-60 minutes.

[0066] In some embodiments of the present invention, the heating curing process is gradient temperature curing, which includes two stages: heating to 100-230° C. for curing for 15-30 min, and then heating to 230-280° C. for curing for 15-30 min.

[0067] In some preferred embodiments of the present invention, the heating curing process is gradient temperature rise curing, which includes two stages: heating to 100-230° C. for curing for 15 min, and then heating to 230-280° C. for curing for 15 min.

[0068] In some embodiments of the present invention, after the epoxy resin sintered powder is obtained, it can be directly used as a coating powder for electrostatic spraying of a substrate; it can also be prepared into a slurry and then used to coat the substrate.

[0069] The third aspect of the present invention provides the use of the above-mentioned coating or the coating prepared by the above-mentioned preparation method in coating of metal substrates.

[0070] The present invention applies the coating obtained as above to metal substrate coating, and the formed coating has the characteristics of high density, high heat and moisture resistance, and strong adhesion, and can be used in extremely harsh environments such as high humidity and heat, salt spray corrosion, etc.

[0071] In some embodiments of the present invention, the metal substrate includes a single metal or a metal alloy, such as tinplate, titanium alloy, stainless steel, and the like.

[0072] A fourth aspect of the present invention provides an anti-corrosion coating, wherein the above-mentioned coating or the coating prepared by the above-mentioned preparation method is uniformly coated on the surface of a metal substrate, and the anti-corrosion coating is obtained after curing.

[0073] The anticorrosion coating provided by the present invention is obtained by coating the aforementioned coating, and therefore also has the technical effects of the coating described above. The present invention applies the aforementioned coating to a metal substrate, and the formed coating has the characteristics of high density, high heat and moisture resistance, and strong adhesion, and can be used in extremely harsh environments such as high humidity and heat, salt spray corrosion, etc.

[0074] In some embodiments of the present invention, the coating powder can be electrostatically sprayed onto the surface of the metal substrate; the coating can also be prepared into a slurry, and then evenly coated on the surface of the metal substrate by scraping, spin coating or spraying, and then cured to obtain the anti-corrosion coating. The coating method can be a conventional method in the art, which is not limited here. The curing method can be a conventional method in the art, such as heating curing, which is not limited here.

[0075] In some embodiments of the present invention, the thickness of the anti-corrosion coating is 100-500 μm, preferably 200-500 μm, and more preferably about 250 μm.

[0076] A fifth aspect of the present invention provides a coated product, comprising a metal substrate and the above-mentioned coating or the coating prepared by the above-mentioned preparation method coated on the metal substrate.

[0077] In some embodiments of the present invention, the metal substrate includes a single metal or a metal alloy, such as tinplate, titanium alloy, stainless steel, and the like.

[0078] A sixth aspect of the present invention provides the use of the above-mentioned paint or the above-mentioned anti-corrosion coating in the fields of home appliance manufacturing, aerospace, and automobile manufacturing.

[0079] In some embodiments of the present invention, household appliances include refrigeration appliances (such as household refrigerators, cold drink machines, etc.), air conditioners (such as room air conditioners, electric fans, ventilation fans, hot and cold air blowers, air dehumidifiers, cold air blowers, humidifiers, etc.), cleaning appliances (such as washing machines, dryers, electric irons, vacuum cleaners, floor waxers, sweeping robots, etc.), kitchen appliances (such as electric stoves, microwave ovens, induction cookers, electric ovens, rice cookers, dishwashers, food processors, etc.), electric heating appliances (such as space heaters), audio and video appliances (such as micro projectors, televisions, radios, tape recorders, video recorders, cameras, combination stereos, etc.).

[0080] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0081] Example 1

[0082] In parts by weight, 62 parts of E51 epoxy resin, 28 parts of F51 epoxy resin, 45 parts of AFG-90 epoxy resin, 18 parts of XSC-N1501 polysilazane and 1 part of benzoin are mixed, and then cured at 100-230°C for 15 minutes and at 230-280°C for 15 minutes under an inert atmosphere, and then ground and sieved to obtain a coating powder; after pouring the coating powder into an electrostatic spray fluidized barrel, spraying it with tinplate as a metal substrate, and then heat curing it in an air environment at 230°C for 15 minutes to form a final coating.

[0083] The thickness of the coating is 250 μm.

[0084] Example 2

[0085] The difference from Example 1 is that the coating formula is different. In this example, by weight, 54 parts of E20 epoxy resin, 16 parts of NPCN-704 epoxy resin, 40 parts of AG-601 epoxy resin, 15 parts of XSC-N2501 polysilazane, and 0.1 parts of benzoin are used. Other parts are the same as in Example 1.

[0086] Example 3

[0087] The difference from Example 1 is that the coating formula is different. In this example, by weight, 85 parts of E44 epoxy resin, 32 parts of F51 epoxy resin, 48 parts of AG-80 epoxy resin, 30 parts of XSC-N0701 polysilazane, and 10 parts of benzoin are used. The rest is the same as Example 1.

[0088] Comparative Example 1

[0089] The difference from Example 1 is that the coating formula is different. In this example, by weight, 28 parts of F51 novolac epoxy resin, 45 parts of AFG-90 hyperbranched epoxy resin, 18 parts of XSC-N1501 polysilazane, and 1 part of benzoin are contained, and bisphenol A epoxy resin is not contained. Other parts are the same as Example 1.

[0090] Comparative Example 2

[0091] The difference from Example 1 is that the coating formula is different. In this example, by weight, 62 parts of E51 bisphenol A epoxy resin, 45 parts of AFG-90 hyperbranched epoxy resin, 18 parts of XSC-N1501 polysilazane, and 1 part of benzoin are contained, and no phenolic epoxy resin is contained. Other parts are the same as Example 1.

[0092] Comparative Example 3

[0093] The difference from Example 1 is that the coating formula is different. In this example, by weight, 62 parts of E51 bisphenol A epoxy resin, 28 parts of F51 novolac epoxy resin, 18 parts of XSC-N1501 polysilazane, and 1 part of benzoin are used, and no hyperbranched epoxy resin is contained. Other parts are the same as in Example 1.

[0094] Comparative Example 4

[0095] The difference from Example 1 is that the coating formula is different. In this embodiment, by weight, 62 parts of E51 bisphenol A epoxy resin, 28 parts of F51 novolac epoxy resin, 45 parts of AFG-90 hyperbranched epoxy resin, 18 parts of boron trifluoride-ethylamine complex, and 1 part of benzoin are contained, and no polysilazane compound is contained. Other parts are the same as Example 1.

[0096] Comparative Example 5

[0097] The difference from Example 1 is that the curing method of the coating is different. In this example, the temperature is gradually increased from 80 to 100° C. for 30 minutes. The other aspects are the same as Example 1.

[0098] Comparative Example 6

[0099] The difference from Example 1 is that the curing method of the coating is different. In this example, the temperature is gradually increased from 300 to 350° C. for 30 minutes. The other aspects are the same as in Example 1.

[0100] Comparative Example 7

[0101] The difference from Example 1 is that tinplate is used as the test sample and the surface is not covered with a protective coating.

[0102] Comparative Example 8

[0103] The difference from Example 1 is that tinplate is used as the test sample, the surface of which is sprayed with XSC-N0701 polysilazane resin, and then cured at 400° C. for 1 hour. The thickness of the cured coating is 250 μm.

[0104] Test Case

[0105] The polysilazane-cured epoxy resin coating in Example 1 was subjected to a DSC test, starting at 0°C and heating to 300°C at a rate of 10K / min. In Example 1, the DSC spectra of the polysilazane-cured epoxy resin coating before and after curing are as follows: Figure 1-2 As shown. In the figure, the heat release is above the ordinate, and it is found that it melts above 50°C, the solidification peak is at 230°C, the glass transition temperature is above 200°C, and the initial decomposition temperature is above 366°C.

[0106] In Example 1, the FTIR spectra of the polysilazane-cured epoxy resin coating before and after curing are as follows: Figure 3-4 As shown. Figure 3-4 It can be seen that the transformation of Si-N-Si bonds into Si-NC bonds and the enhancement of the infrared peaks of Si-OC bonds prove that polysilazane can effectively cure epoxy resin.

[0107] The TGA curves of the coating in Example 1 after curing in air atmosphere and argon atmosphere are as follows: Figure 5-6 As shown by Figure 5 It can be seen that the cured resin shows good thermal stability in an air environment below 300°C, with an initial decomposition temperature of 366°C and a residual content of 13%. Figure 6 It can be seen that the initial decomposition temperature of the cured epoxy resin in an argon environment is increased to 386°C, and it exhibits excellent heat resistance when the temperature is less than 350°C, with a residual amount of 38%.

[0108] The pull-out strength of the coatings in Examples 1-2 of the present invention based on the tinplate substrate was tested, and the testing standard was ISO4624: 2023. The pull-out strength of the coating in Example 1 based on the tinplate substrate was 0.713Mpa, and the pull-out strength of the coating in Example 2 based on the tinplate substrate was 0.570Mpa, which proved that the coating formed by the coating had the characteristics of high density and strong adhesion.

[0109] The corrosion resistance of the coating was evaluated by a scratch test on Examples 1-3 and Comparative Examples 1-8 of the present invention. The method is as follows: the prepared coating samples were respectively taken, scratched on the surface, and the scratches on the sample surface were of the same size. Then, the coating samples were placed in a salt spray test box. After 7 days of salt spray test, the surface of the samples was tested. The test standard is GB / T10125-2021. The results are shown in Table 1:

[0110] Table 1

[0111]

[0112]

[0113] The corrosion resistance of the anti-corrosion coating was evaluated through a scratch test, and it was found that there was no obvious change in the surface coating of Examples 1-3 before and after the experiment, and there was no corrosion except for the corrosion of the exposed external substrate; Comparative Examples 1-3 all had a tendency for surface corrosion to spread to the coating area, indicating that the epoxy resin requires a reasonable ratio of bisphenol A epoxy resin, phenolic epoxy resin, and hyperbranched epoxy resin; Comparative Example 4 had a tendency for surface corrosion to spread to the coating area but was milder than Comparative Examples 1-3, indicating that ordinary curing agents could not achieve the corresponding effect; Comparative Examples 5-6 had serious surface coating shedding, indicating that the gradient heating method of the present invention requires precise temperature control to ensure that the coating is completely cured and not over-cured; Comparative Example 7 had serious corrosion at the scratch point and the corrosion tended to extend outward, and Comparative Example 8 had serious coating shedding at the scratch point, and serious corrosion at the scratch point and the corrosion tended to extend outward.

[0114] The high temperature resistance and long-term corrosion resistance of Examples 1-3 and Comparative Examples 1-8 were accelerated by taking the coating samples, soaking them in 170°C hot water at 0.65MPa in a high temperature autoclave for 2 days, observing the surface of the samples and detecting their electrochemical impedance (test standard GB / T 39482-2020). The results are shown in Table 2:

[0115] Table 2

[0116]

[0117]

[0118] For the coatings prepared in the examples and comparative examples, the initial electrochemical impedance was 10 ^ 12Ω, after being immersed in 170℃ hot water 0.652MPa in a high temperature autoclave for 2 days, the surface coating of Examples 1-3 had no obvious change, and the electrochemical impedance only dropped to 10 ^ 11Ω, the surface coatings of comparative examples 1-6 all have some bubbles, and the electrochemical impedance drops to a minimum of 10 ^ 6Ω, the surface corrosion of comparative example 7 is serious, and the surface coating of comparative example 8 falls off and has no anti-corrosion effect.

[0119] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the above-mentioned implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the present application. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. A coating, characterized in that: The raw material components of the coating include, by weight: 70 to 240 parts of epoxy resin composition and 1 to 100 parts of polysilazane compound; The epoxy resin composition comprises 20 to 100 parts of bisphenol A epoxy resin, 10 to 40 parts of novolac epoxy resin, and 40 to 100 parts of hyperbranched epoxy resin; The main chain of the polysilazane compound contains NH covalent bonds, and the side chain contains C1~C 10 At least one of a straight-chain alkyl group, a phenyl group and a naphthyl group.

2. The coating according to claim 1, characterized in that The raw material components of the coating include, by weight: 105 to 170 parts of epoxy resin composition and 15 to 30 parts of polysilazane compound.

3. The coating according to claim 2, characterized in that In parts by weight, the epoxy resin composition comprises 50 to 85 parts of bisphenol A epoxy resin, 15 to 35 parts of novolac epoxy resin, and 40 to 50 parts of hyperbranched epoxy resin.

4. The coating according to claim 1 or 2, characterized in that: The structural formula of the polysilazane compound is: Wherein, R1 is independently selected from C1~C 10 A straight chain alkyl group; R2 is independently selected from at least one of phenyl and naphthyl; The value range of n is 700 to 1500.

5. The coating according to claim 1, 2 or 3, characterized in that: The bisphenol A epoxy resin is selected from at least one of E51 epoxy resin, E44 epoxy resin, E20 epoxy resin and E12 epoxy resin.

6. The coating according to claim 1, 2 or 3, characterized in that: The phenolic epoxy resin is selected from at least one of F51 epoxy resin and NPCN-704 epoxy resin.

7. The coating according to claim 1, 2 or 3, characterized in that: The hyperbranched epoxy resin is selected from at least one of AFG-90 epoxy resin, AFG-90H epoxy resin, AG-80 epoxy resin, AG-70 epoxy resin, AG-601 epoxy resin and AG-602 epoxy resin.

8. The coating according to claim 1, 2 or 3, characterized in that: The raw material components of the coating further include: 0.1 to 100 parts of filler by weight.

9. The coating according to claim 8, characterized in that The filler is selected from at least one of carbon black, graphite, carbon nanotubes, activated carbon, alumina, silica, mica, boron nitride, calcium silicate, benzoin, titanium dioxide, MXene, glass microspheres, quartz sand, iron powder, iron salt, cobalt chloride, nickel chloride, ferric oxide, ferrous oxide, cobalt oxide, nickel oxide, sodium tripolyphosphate, mica iron oxide, aluminum phosphate, glass flakes, zinc phosphate and calcium phosphate.

10. A method for preparing a coating according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: mixing raw materials according to weight components, heating and solidifying them, and grinding and screening them to obtain epoxy resin sintered powder.

11. The preparation method according to claim 10, characterized in that: The heating and curing process is: heating to 100-280° C. and curing for 15-60 minutes.

12. The preparation method according to claim 11, characterized in that: The heating and curing process is a gradient temperature rise curing process, which includes two stages: heating to 100-230° C. and curing for 15-30 min, and then heating to 230-280° C. and curing for 15-30 min.

13. Use of the coating according to any one of claims 1 to 9 or the coating prepared by the preparation method according to any one of claims 10 to 12 in coating a metal substrate.

14. An anti-corrosion coating, characterized in that: The coating according to any one of claims 1 to 9 or the coating prepared by the preparation method according to any one of claims 10 to 12 is uniformly coated on the surface of the metal substrate, and the anti-corrosion coating is obtained after curing.

15. A coated product, characterized in that The invention comprises a metal substrate and a coating as claimed in any one of claims 1 to 9 or a coating prepared by the preparation method as claimed in any one of claims 10 to 12, which is coated on the metal substrate.

16. The coated product according to claim 15, characterized in that The metal substrate includes a single metal or a metal alloy.

17. Use of the coating according to any one of claims 1 to 9 or the anti-corrosion coating according to claim 14 in the fields of home appliance manufacturing, aerospace, and automobile manufacturing.

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