Double-layer coating and preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of coatings, and provides a double-layer coating and a preparation method therefor and a use thereof. The double-layer coating comprises a base layer coating and a top layer coating; the base layer coating comprises a ceramic precursor and a resin, the ceramic precursor is composed of a polysilane compound and a metal precursor, the polysilane compound is selected from one or more of polycarbosilane, polyborosilazane, and polysilicon boron carbon nitrogen, and the metal precursor is selected from one or more of a zirconium precursor, an aluminum precursor, and a titanium precursor. The base layer coating of the present invention uses a copolymerization product obtained by reaction of a ceramic precursor with a resin as a main resin, and the ceramic precursor is composed of a specific polysilane compound and a metal precursor, so that low-adhesion performance on a material surface is achieved, thus effectively preventing scale formation, improving the anti-corrosion performance, and reducing the energy consumption.

Description

Double-layer coating and its preparation method and application

[0001] Cross-references

[0002] This application claims priority to Chinese patent application No. 202311682247.1, filed on December 8, 2023, entitled “Double-layer coating, preparation method and application thereof,” and all disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates to the technical field of coatings, and in particular to a double-layer coating and a preparation method and application thereof. Background Art

[0004] Coatings are liquid or solid materials that, under certain conditions, form a thin film on surfaces, providing protection, decoration, or other special functions (such as insulation, rust prevention, mildew resistance, and heat resistance). Coatings can be categorized by application, including architectural coatings, automotive coatings, appliance coatings, and wood coatings. With the development of the home appliance industry, the performance and functional requirements for appliance coatings are increasing.

[0005] Enamel and stainless steel are the most widely used coating materials for water heaters. Enamel is widely used in water heater production due to its high hardness, excellent scratch resistance, and high-temperature resistance. Stainless steel is also widely used due to its excellent corrosion resistance.

[0006] However, enamel has the following disadvantages: ① high sintering temperature (most of which is greater than 800℃) and high energy consumption; ② there is a risk of heavy metal hazards; ③ low yield rate, prone to defects such as porcelain explosion and enameling; ④ requires roughening pre-treatment such as sandblasting; ⑤ difficult to clean the surface, and scale problems are prone to occur during heater operation.

[0007] However, stainless steel has poor temperature resistance and begins to oxidize at around 250°C, which reduces its corrosion resistance. In addition, the surface is difficult to clean, and scale is easily formed during the operation of the heater.

[0008] Summary of the Invention

[0009] The present invention aims to address at least one of the technical problems existing in the related art. To this end, the present invention proposes a double-layer coating, its preparation method, and its application. The double-layer coating formed by the double-layer coating exhibits excellent low viscosity, high adhesion, and corrosion resistance. It aims to address technical issues such as scaling, corrosion, and high energy consumption associated with the long-term use of enamel or stainless steel in water heaters in the home appliance industry.

[0010] In the first aspect, the present invention provides a double-layer coating, including a primer and a topcoat, wherein the primer includes a ceramic precursor and a resin, and the ceramic precursor is composed of a polysilane compound and a metal precursor, wherein the polysilane compound is selected from one or more of polycarbosilane, polyborosilazane, and polysilicon boron carbon nitrogen, and the metal precursor is selected from one or more of a zirconium precursor, an aluminum precursor, and a titanium precursor.

[0011] In some embodiments, the mass ratio of the polysilane compound to the metal precursor is 3:1-1:6.

[0012] In some embodiments, the resin is a polysiloxane resin and / or an epoxy resin.

[0013] In some embodiments, the resin is a mixture of polysiloxane resin and epoxy resin in a mass ratio of 20:0-8:15.

[0014] In some embodiments, the mass ratio of the ceramic precursor to the resin is 99:1-10:90.

[0015] In some embodiments, the primer further comprises one or more of a filler, a solvent, and an additive.

[0016] In some embodiments, the filler is selected from one or more of silicon carbide, talc, glass flakes, basalt flakes, muscovite, zinc phosphate, aluminum phosphate, low-melting glass powder, white carbon black, and inorganic pigments, and the mass of the filler accounts for 0.1-50% of the mass of the primer;

[0017] In some embodiments, the solvent is selected from one or more of an alkane solvent, an ether solvent, a ketone solvent, a benzene derivative solvent, and an ester solvent.

[0018] In some embodiments, the mass of the solvent accounts for 0.1-50% of the mass of the primer.

[0019] In some embodiments, the auxiliary agent is selected from one or more of a dispersant, an anticorrosive agent, and a wetting and leveling agent.

[0020] In some embodiments, the mass of the auxiliary agent accounts for 0.1-5% of the mass of the primer.

[0021] In some embodiments, the surface coating is composed of the following components by mass: 10% to 50% silica sol, 1-25% epoxy-modified siloxane, 0 to 20% polysilane compound, 0.1 to 5% anti-graffiti agent, and 10 to 70% solvent.

[0022] In some embodiments, the solvent is butyl acetate.

[0023] In a second aspect, the present invention provides a method for preparing the above-mentioned double-layer coating, which includes two parts: preparing the base coating and preparing the surface coating.

[0024] The preparation method of the primer comprises:

[0025] Mixing a polysilane compound and a metal precursor to obtain a ceramic precursor, namely component A;

[0026] Mix and grind the raw materials other than the ceramic precursor to obtain component B with a fineness of ≤15μm;

[0027] Finally, component A and component B are mixed to obtain the primer.

[0028] The preparation method of the surface coating comprises:

[0029] The surface coating is obtained by mixing silica sol, epoxy-modified siloxane, polysilane compound, anti-graffiti additive and solvent.

[0030] In some embodiments, the mixing is performed by stirring at a stirring rate of 100 to 2000 r / min.

[0031] In a third aspect, the present invention provides a double-layer coating formed by the above-mentioned double-layer coating.

[0032] In a fourth aspect, the present invention provides a product having a coating, which comprises a substrate and a coating attached to at least a portion of the surface of the substrate, wherein the coating is a double-layer coating formed by the above-mentioned double-layer coating.

[0033] According to the article with coating provided by the present invention, the substrate is a metal substrate, a glass substrate, a ceramic substrate, an enamel substrate, a polymer substrate or a composite substrate of two or more of the above substrates.

[0034] According to the present invention, the article with a coating is a household appliance.

[0035] In some embodiments, the article is a water heater.

[0036] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0037] The present invention provides a double-layer coating, a preparation method and an application thereof, wherein the base coating uses a copolymer obtained by the reaction of a ceramic precursor and a resin as the main resin, and the ceramic precursor is composed of a specific polysilane compound and a metal precursor, thereby achieving low adhesion performance on the material surface, thereby effectively preventing scale formation, while also improving corrosion resistance and reducing energy consumption.

[0038] Furthermore, the surface coating of the present invention also has excellent low surface energy, which can further prevent scale formation and is particularly suitable for electrical appliances that heat water, such as water heaters.

[0039] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 shows the scale state of a heater coated with the coating of Example 1 of the present invention;

[0041] Figure 2 shows the scale status of the blank control. DETAILED DESCRIPTION

[0042] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0043] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean 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 embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0044] In the first aspect, the present invention provides a double-layer coating, including a primer and a topcoat, wherein the primer includes a ceramic precursor and a resin, and the ceramic precursor is composed of a polysilane compound and a metal precursor, wherein the polysilane compound is selected from one or more of polycarbosilane, polyborosilazane, and polysilicon boron carbon nitrogen, and the metal precursor is selected from one or more of a zirconium precursor, an aluminum precursor, and a titanium precursor.

[0045] The present invention uses a copolymer obtained by reacting a ceramic precursor with excellent reactivity and a resin as the main resin of the primer, wherein the ceramic precursor is composed of a specific polysilane compound and a metal precursor. By chemically grafting low surface energy groups and constructing micro-nano structures, the material surface has low adhesion performance, thereby effectively preventing scale formation. At the same time, the present invention uses a copolymer obtained by reacting a ceramic precursor and a resin as the main resin of the primer, and the film formed has excellent density, which improves the anti-corrosion performance; in addition, the coating system has excellent adhesion performance, so there is no need for roughening such as sandblasting, and only the oil stains on the surface of the workpiece need to be removed to achieve excellent adhesion between the coating and the blank substrate. Compared with enamel materials, the primer of the present invention does not need to use heavy metals such as cobalt and nickel to achieve excellent adhesion between the coating and the substrate. In addition, since the present invention uses an organic polymer material as the main resin, it can achieve excellent adhesion performance under low temperature conditions (below 300°C), and compared with the sintering temperature of enamel greater than 850°C, the energy consumption is significantly reduced. In summary, the coating of the present invention is significantly superior to the currently used enamel and stainless steel coating materials, and is particularly suitable for the surface treatment of water heaters.

[0046] In the present invention, the zirconium precursor refers to an organic polymer with a main chain of Zr-O and a side chain containing a reactive group, which can be converted into an inorganic substance under conditions such as heating.

[0047] The aluminum precursor refers to a type of organic polymer with an Al-O main chain and reactive groups in the side chain, which can be converted into an inorganic substance under heating or other conditions.

[0048] The titanium precursor refers to a type of organic polymer with a main chain of Ti-O and a side chain containing reactive groups, which can be converted into an inorganic substance under conditions such as heating.

[0049] In some embodiments of the present invention, the mass ratio of the polysilane compound to the metal precursor is 3:1-1:6.

[0050] The resin of the present invention is a common coating resin that can stably react with ceramic precursors. In some embodiments of the present invention, the resin is polysiloxane and / or epoxy resin.

[0051] In some embodiments, the resin is a mixture of polysiloxane resin and epoxy resin in a mass ratio of 20:0-8:15.

[0052] In some embodiments of the present invention, the mass ratio of the ceramic precursor to the resin is 99:1-10:90.

[0053] In some embodiments of the present invention, the primer further comprises one or more of a filler, a solvent and an additive.

[0054] The addition of fillers can not only impart a certain color to the coating, but also make the coating denser and more corrosion-resistant. In some embodiments of the present invention, the filler is selected from one or more of silicon carbide, talc, glass flakes, basalt flakes, muscovite, zinc phosphate, aluminum phosphate, low-melting glass powder, white carbon black, and inorganic pigments, and the weight of the filler accounts for 0.1-50% of the weight of the primer. In some embodiments, the weight of the filler accounts for 30-50% of the weight of the primer.

[0055] In some embodiments of the present invention, the solvent is selected from one or more of an alkane solvent, an ether solvent, a ketone solvent, a benzene derivative solvent, and an ester solvent, and the weight of the solvent accounts for 0.1-50% of the weight of the primer. In some embodiments, the weight of the solvent accounts for 20-40% of the weight of the primer.

[0056] The alkane solvent is selected from one or more of n-hexane, n-octane, n-decane, chloroform, dichloromethane, ethylene dichloride, and mineral oil.

[0057] The ether solvent is selected from at least one of ethyl ether, petroleum ether, and dibutyl ether.

[0058] The ketone solvent is selected from at least one of acetone, methyl ethyl ketone, cyclohexanone, and isophorone.

[0059] The benzene derivative solvent is selected from at least one of toluene, m-xylene, p-xylene, o-xylene, and chlorobenzene.

[0060] The ester solvent is selected from ethyl acetate and propyl propionate. In some embodiments, the ester solvent is ethyl acetate.

[0061] In some embodiments of the present invention, the auxiliary agent is selected from one or more auxiliary agents such as dispersants, anti-corrosion agents, wetting and leveling agents, anti-graffiti agents, etc. that can enhance the performance of the coating composition, and the mass of the auxiliary agent accounts for 0.1-5% of the mass of the primer.

[0062] In some embodiments of the present invention, the surface coating is composed of the following components by mass: 10% to 50% silica sol, 1-25% epoxy-modified siloxane, 0 to 20% polysilane compound, 0.1 to 5% anti-graffiti agent, and 10 to 70% solvent.

[0063] In the surface coating, the solvent is butyl acetate, which can dissolve and mix the components well.

[0064] In a second aspect, the present invention provides a method for preparing the above-mentioned double-layer coating, which includes two parts: preparing the base coating and preparing the surface coating.

[0065] The preparation method of the primer comprises:

[0066] Mixing a polysilane compound and a metal precursor to obtain a ceramic precursor, namely component A;

[0067] Mix and grind the raw materials other than the ceramic precursor to obtain component B with a fineness of ≤15μm;

[0068] Finally, component A and component B are mixed to obtain the primer.

[0069] The preparation method of the surface coating comprises:

[0070] The surface coating is obtained by mixing silica sol, epoxy-modified siloxane, polysilane compound, anti-graffiti additive and solvent.

[0071] In the process of preparing the primer and the topcoat, mixing can be performed by conventional means in the art, such as stirring. In some embodiments, the stirring speed is 100 to 2000 r / min.

[0072] When grinding component B, commonly used equipment in the field, such as a sand mill, a basket grinder, a high-speed disperser, etc., can be used to grind the mixed material to a fineness of ≤15μm.

[0073] In some embodiments of the present invention, when mixing to obtain component B, the resin is first dispersed in the solvent, and then the remaining materials are added and mixed evenly.

[0074] It is understandable that the order of component addition, stirring speed, stirring time, grinding method, etc. mentioned in the preparation method are only typical values ​​of the experimental process. By adjusting the order and processing parameters to other values, coatings with similar performance can be obtained. Most of the differences are just in production efficiency.

[0075] In a third aspect, the present invention provides a double-layer coating formed by the above-mentioned double-layer coating.

[0076] Specifically, in the coating formation process, the primer is first applied to the substrate surface by common construction methods such as spraying, brushing, and roller coating. After drying, a primer coating is formed. Then, the topcoat is applied to the dried primer coating to finally form a double-layer coating.

[0077] In some embodiments of the present invention, for better long-term effectiveness and scale inhibition, the thickness of the base coating is 15-25 μm and the thickness of the top coating is 4-7 μm.

[0078] In a fourth aspect, the present invention provides an article having a coating, wherein the article comprises a substrate and a coating attached to at least a portion of the surface of the substrate, wherein the coating is formed from the above-mentioned coating composition.

[0079] In some embodiments of the present invention, the substrate is a metal substrate, a glass substrate, a ceramic substrate, an enamel substrate, a polymer substrate, or a composite substrate of two or more of the above substrates.

[0080] In some embodiments of the present invention, the article is a household appliance. In some embodiments, the article is a water heater.

[0081] There are many household appliances, such as microwave ovens, ovens, range hoods, stoves, vacuum cleaners, dishwashers, air conditioners, refrigerators, washing machines, water heaters, etc. All of them require coatings, but the coating of the present invention is more suitable for water heaters because the double-layer coating specifically solves problems such as scaling and corrosion, and is also resistant to a certain high temperature (around 100°C). This is different from the coatings previously developed by the applicant that are more suitable for household appliances such as microwave ovens and ovens, which have higher temperature resistance requirements (around 400°C).

[0082] Specific embodiments will be described below.

[0083] In the following examples, if no specific techniques or conditions are specified, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. All reagents or instruments used, if the manufacturer is not specified, are conventional products that can be purchased through regular channels.

[0084] In the following examples, the zirconium precursor used is an organic polymer having a Zr-O backbone and side chains containing hydrogen, vinyl, and methyl groups. The aluminum precursor used is an organic polymer having an Al-O backbone and side chains containing hydrogen, vinyl, and methyl groups. The titanium precursor used is an organic polymer having a Ti-O backbone and side chains containing hydrogen, vinyl, and methyl groups.

[0085] Example 1

[0086] This embodiment provides a double-layer coating, including a base coating and a top coating.

[0087] The base coating comprises, by mass percentage, 4% polycarbosilane, 11% zirconium precursor, 20% polysiloxane resin, 5% talc, 15% glass flakes, 2% white carbon black, 3% low-melting glass powder, 13% copper chrome black, 10.4% diethylene glycol butyl ether, 16% propylene glycol methyl ether acetate, 0.5% dispersant, and 0.1% wetting and leveling agent. The preparation method is as follows:

[0088] (1) Preparation of component A:

[0089] Weigh 4% polycarbosilane and 11% zirconium precursor and mix them evenly.

[0090] (2) Preparation of component B:

[0091] Stir 20% polysiloxane resin with 10.4% diethylene glycol butyl ether and 16% propylene glycol methyl ether acetate at 500 r / min until uniformly dissolved, then add 0.5% dispersant, 0.1% wetting and leveling agent, 5% talcum powder, 15% glass flakes, 2% white carbon black, 3% low-melting glass powder and 13% copper chrome black one by one, and pre-stir at 1000 r / min until the materials are evenly mixed.

[0092] The premix was ground using a sand mill at 2000 r / min to a fineness of ≤15 μm.

[0093] (3) Preparation of base coating:

[0094] Mix the above components A and B, and stir at 600 r / min until uniform to prepare the base coating.

[0095] The surface coating is composed of the following components by mass percentage: 10% silica sol, 25% epoxy-modified siloxane, 20% polysilazane, 3% anti-graffiti additive, and 42% butyl acetate. The preparation method is as follows:

[0096] Add 10% silica sol, 25% epoxy modified siloxane, 20% polysilazane, 3% anti-graffiti additive and 42% butyl acetate into a mixing tank one by one, stir at 1000 r / min until uniform to prepare the surface coating.

[0097] Example 2

[0098] This embodiment provides a double-layer coating, including a base coating and a top coating.

[0099] The primer is composed of the following components by mass percentage: 2% polysilicon boron carbon nitrogen, 11.4% aluminum precursor, 8% polysiloxane resin, 15% epoxy resin, 3% silicon carbide, 10% glass flakes, 5% mica, 3% zinc phosphate, 3% low-melting glass powder, 17% copper chrome black, 5% petroleum ether, 5% butyl acetate, 12% propylene glycol methyl ether acetate, 0.5% dispersant, and 0.1% wetting and leveling agent. The preparation method is as follows:

[0100] (1) Preparation of component A:

[0101] Weigh 2% polysilicon boron carbon nitride and 11.4% aluminum precursor and mix them evenly.

[0102] (2) Preparation of component B:

[0103] Stir 8% polysiloxane resin, 15% epoxy resin, 5% petroleum ether, 5% butyl acetate, and 12% propylene glycol methyl ether acetate at 500 r / min until uniformly dissolved, then add 0.5% dispersant, 0.1% wetting and leveling agent, 3% silicon carbide, 10% glass flakes, 5% mica, 3% zinc phosphate, 3% low-melting glass powder, and 17% copper chrome black one by one, and pre-stir at 900 r / min until the materials are evenly mixed.

[0104] The premix was ground using a sand mill at 2000 r / min to a fineness of ≤15 μm.

[0105] (3) Preparation of base coating:

[0106] Mix the above components A and B, and stir at 400 r / min until uniform to prepare the base coating.

[0107] The surface coating comprises, by mass percentage, 50% silica sol, 1% epoxy-modified siloxane, 13% polysilazane, 2% anti-graffiti additive, and 34% butyl acetate. The preparation method is as follows:

[0108] Add 50% silica sol, 1% epoxy modified siloxane, 13% polysilazane, 2% anti-graffiti additive and 34% butyl acetate into a mixing tank one by one, stir at 100 r / min until uniform to prepare the surface coating.

[0109] Example 3

[0110] This embodiment provides a double-layer coating, including a base coating and a top coating.

[0111] The primer comprises, by mass percentage, 4% polyborosilazane, 12% titanium precursor, 12% polysiloxane resin, 17% epoxy resin, 3% silicon carbide, 3% talc, 7% basalt flakes, 4% zinc phosphate, 4% aluminum phosphate, 5% low-melting glass powder, 10% copper chrome black, 6% paraxylene, 12.4% propylene glycol methyl ether acetate, 0.5% dispersant, and 0.1% wetting and leveling agent. The preparation method is as follows:

[0112] (1) Preparation of component A:

[0113] Weigh 4% polyborosilazane and 12% titanium precursor and mix them evenly.

[0114] (2) Preparation of component B:

[0115] Stir 12% polysiloxane resin, 17% epoxy resin, 6% p-xylene and 12.4% propylene glycol methyl ether acetate at 700 r / min until uniformly dissolved, then add 0.5% dispersant, 0.1% wetting and leveling agent, 3% silicon carbide, 3% talc, 7% basalt flakes, 4% zinc phosphate, 4% aluminum phosphate, 5% low-melting glass powder and 10% copper chrome black one by one, and pre-stir at 1000 r / min until the materials are evenly mixed.

[0116] The premix was ground using a sand mill at 2000 r / min to a fineness of ≤15 μm.

[0117] (3) Preparation of base coating:

[0118] Mix the above components A and B, and stir at 600 r / min until uniform to prepare the base coating.

[0119] The surface coating comprises, by mass percentage, 30% silica sol, 15% epoxy-modified siloxane, 12% polysilazane, 5% anti-graffiti additive, and 38% butyl acetate. The preparation method is as follows:

[0120] Add 30% silica sol, 15% epoxy modified siloxane, 12% polysilazane, 5% anti-graffiti additive and 38% butyl acetate into a mixing tank one by one, stir at 700 r / min until uniform to prepare the surface coating.

[0121] Example 4

[0122] This embodiment provides a double-layer coating, including a base coating and a top coating.

[0123] The primer comprises, by mass percentage, 15% polyborosilazane, 5% zirconium precursor, 10% polysiloxane resin, 10% epoxy resin, 10% silicon carbide, 4% basalt flakes, 4% zinc phosphate, 5% low-melting glass powder, 10% copper chrome black, 10% paraxylene, 16.4% propylene glycol methyl ether acetate, 0.5% dispersant, and 0.1% wetting and leveling agent. The preparation method is as follows:

[0124] (1) Preparation of component A:

[0125] Weigh 15% polyborosilazane and 5% zirconium precursor and mix them evenly.

[0126] (2) Preparation of component B:

[0127] Stir 10% polysiloxane resin, 10% epoxy resin, 10% p-xylene and 16.4% propylene glycol methyl ether acetate at 800 r / min until uniformly dissolved, then add 0.5% dispersant, 0.1% wetting and leveling agent, 10% silicon carbide, 4% basalt flakes, 4% zinc phosphate, 5% low-melting glass powder and 10% copper chrome black one by one, and pre-stir at 1000 r / min until the materials are evenly mixed.

[0128] The premix was ground using a sand mill at 2000 r / min to a fineness of ≤15 μm.

[0129] (3) Preparation of base coating:

[0130] Mix the above components A and B, and stir at 700 r / min until uniform to prepare the base coating.

[0131] The surface coating is composed of the following components by mass percentage: 20% silica sol, 20% epoxy-modified siloxane, 20% polysilazane, 0.5% anti-graffiti additive, and 39.5% butyl acetate. The preparation method is as follows:

[0132] Add 20% silica sol, 20% epoxy modified siloxane, 20% polysilazane, 0.5% anti-graffiti additive and 39.5% butyl acetate into a mixing tank one by one, stir at 600 r / min until uniform to prepare the surface coating.

[0133] Example 5

[0134] This embodiment provides a double-layer coating, including a base coating and a top coating.

[0135] The primer is composed of the following components by mass: 2% polycarbosilane, 16% titanium precursor, 10% polysiloxane resin, 10% epoxy resin, 10% silicon carbide, 4% basalt flakes, 4% zinc phosphate, 5% low-melting glass powder, 10% copper chrome black, 10% paraxylene, 18.4% propylene glycol methyl ether acetate, 0.5% dispersant, and 0.1% wetting and leveling agent. The preparation method is as follows:

[0136] (1) Preparation of component A:

[0137] Weigh 2% polycarbosilane and 16% titanium precursor and mix them evenly.

[0138] (2) Preparation of component B:

[0139] Stir 10% polysiloxane resin, 10% epoxy resin, 10% p-xylene and 18.4% propylene glycol methyl ether acetate at 800 r / min until uniformly dissolved, then add 0.5% dispersant, 0.1% wetting and leveling agent, 10% silicon carbide, 4% basalt flakes, 4% zinc phosphate, 5% low-melting glass powder and 10% copper chrome black one by one, and pre-stir at 1000 r / min until the materials are evenly mixed.

[0140] The premix was ground using a sand mill at 2000 r / min to a fineness of ≤15 μm.

[0141] (3) Preparation of base coating:

[0142] Mix the above components A and B, and stir at 700 r / min until uniform to prepare the base coating.

[0143] The surface coating is composed of the following components by mass percentage: 20% silica sol, 20% epoxy-modified siloxane, 20% polysilazane, 0.5% anti-graffiti additive, and 39.5% butyl acetate. The preparation method is as follows:

[0144] Add 20% silica sol, 20% epoxy modified siloxane, 20% polysilazane, 0.5% anti-graffiti additive and 39.5% butyl acetate into a mixing tank one by one, stir at 600 r / min until uniform to prepare the surface coating.

[0145] Example 6

[0146] This embodiment provides a double-layer coating, including a base coating and a top coating.

[0147] The primer comprises, by mass percentage, 4% polyborosilazane, 12% titanium precursor, 12% polysiloxane resin, 17% epoxy resin, 3% silicon carbide, 3% talc, 7% basalt flakes, 4% zinc phosphate, 4% aluminum phosphate, 5% low-melting glass powder, 10% copper chrome black, 6% paraxylene, 12.4% propylene glycol methyl ether acetate, 0.5% dispersant, and 0.1% wetting and leveling agent. The preparation method is as follows:

[0148] (1) Preparation of component A:

[0149] Weigh 4% polyborosilazane and 12% titanium precursor and mix them evenly.

[0150] (2) Preparation of component B:

[0151] Stir 12% polysiloxane resin, 17% epoxy resin, 6% p-xylene and 12.4% propylene glycol methyl ether acetate at 700 r / min until uniformly dissolved, then add 0.5% dispersant, 0.1% wetting and leveling agent, 3% silicon carbide, 3% talc, 7% basalt flakes, 4% zinc phosphate, 4% aluminum phosphate, 5% low-melting glass powder and 10% copper chrome black one by one, and pre-stir at 1000 r / min until the materials are evenly mixed.

[0152] The premix was ground using a sand mill at 2000 r / min to a fineness of ≤15 μm.

[0153] (3) Preparation of base coating:

[0154] Mix the above components A and B, and stir at 600 r / min until uniform to prepare the base coating.

[0155] The surface coating comprises, by mass percentage, 30% silica sol, 15% polyester-modified siloxane, 12% polyborosilazane, 5% anti-graffiti additive, and 38% butyl acetate. The preparation method is as follows:

[0156] Add 30% silica sol, 15% polyester modified siloxane, 12% polyborosilazane, 5% anti-graffiti additive and 38% butyl acetate into a mixing tank one by one, stir at 700 r / min until uniform to prepare the surface coating.

[0157] Comparative Example 1

[0158] This comparative example provides a double-layer coating, including a primer and a topcoat.

[0159] The primer is 100% polyborosilazane.

[0160] The surface coating is composed of 25% silica sol, 25% epoxy modified siloxane, 1% anti-graffiti additive, and 49% butyl acetate by mass percentage. The preparation method is as follows:

[0161] Add 25% silica sol, 25% epoxy modified siloxane, 1% anti-graffiti additive and 49% butyl acetate into a mixing tank one by one, stir at 1200 r / min until uniform to prepare the surface coating.

[0162] Comparative Example 2

[0163] This comparative example provides a double-layer coating, including a primer and a topcoat.

[0164] The primer is 100% polysilazane.

[0165] The surface coating is composed of 45% silica sol, 17% epoxy-modified siloxane, 16% polysilazane, 2% anti-graffiti additive, and 20% butyl acetate by mass percentage. The preparation method is as follows:

[0166] Add 45% silica sol, 17% epoxy modified siloxane, 16% polysilazane, 2% anti-graffiti additive and 20% butyl acetate into a mixing tank one by one, stir at 1500r / min until uniform to prepare the surface coating.

[0167] Comparative Example 3

[0168] This comparative example provides a coating, including a primer and a topcoat.

[0169] The primer is composed of the following components by mass percentage: 10% polysilazane, 30% epoxy resin, 10% silicon carbide, 15% basalt flakes, 2% white carbon black, 13% copper chrome black, 19.5% p-xylene, and 0.5% dispersant. The preparation method is as follows:

[0170] (1) Preparation of component A:

[0171] Weigh 10% polysilazane ceramic precursor.

[0172] (2) Preparation of component B:

[0173] Stir 30% epoxy resin and 19.5% p-xylene at 500 r / min until uniformly dissolved, then add 0.5% dispersant, 10% silicon carbide, 15% basalt flakes, 2% white carbon black, and 13% copper chrome black one by one, and pre-stir at 800 r / min until the materials are evenly mixed.

[0174] The premix was ground using a sand mill at 2000 r / min to a fineness of ≤15 μm.

[0175] (3) Preparation of base coating:

[0176] Mix the above components A and B, and stir at 300 r / min until uniform to prepare the base coating.

[0177] The surface coating is composed of the following components by mass percentage: 35% silica sol, 10% epoxy-modified siloxane, 10% polysilazane, 4% anti-graffiti additive, and 41% butyl acetate. The preparation method is as follows:

[0178] Add 35% silica sol, 10% epoxy modified siloxane, 10% polysilazane, 4% anti-graffiti additive and 41% butyl acetate into a mixing tank one by one, stir at 500 r / min until uniform to prepare the surface coating.

[0179] Comparative Example 4

[0180] This comparative example provides a double-layer coating, including a primer and a topcoat.

[0181] The preparation method of the primer is as follows:

[0182] Providing preparation raw materials, the preparation raw materials comprising polysilazane and polysiloxane, wherein R1 of the polysilazane is an aryl group, R2 is a hydrogen group, and R3 is an alkylamino group, and the polysilazane accounts for 40% by mass of the preparation raw materials; R4 of the polysiloxane is a cycloalkane, R5 is an alkylsiloxy group, and the polysiloxane accounts for 30% by mass of the preparation raw materials;

[0183] placing polysilazane and polysiloxane in a reactor, mixing the polysilazane and polysiloxane at a speed of 800 rpm, and copolymerizing the polysiloxane with the polysilazane to generate a polysiloxane-polysilazane copolymer;

[0184] Dibutyl ether is provided, wherein the mass percentage of the dibutyl ether in the preparation raw material is 30%, and the dibutyl ether and the polysiloxane-polysilazane copolymer are mixed at a speed of 1000 revolutions per minute to obtain a primer.

[0185] The preparation of the top coating is the same as in Example 1.

[0186] Performance Testing

[0187] The coatings obtained in each example and comparative example were subjected to a 100-grid test according to GB / T 9286 to measure the adhesion between the coating and the substrate (heater substrate, stainless steel).

[0188] The coatings obtained in each embodiment and comparative example are respectively applied to the surface of the heater. For the comparability of the test results, the heater material (stainless steel) and shape are the same, and the coating thickness is consistent. The working environment of the heating pipe in the electric water heater is simulated, and spiked water quality is used (by adding chemical reagents such as calcium chloride, magnesium chloride, sodium bicarbonate, etc. to the water, adjusting the water hardness value to 400-500 mg / L and the chloride ion concentration to 200-300 mg / L, so that the water quality is easy to form scale and has a certain corrosiveness to metals). A fixed power-on time (20 minutes) and a fixed power-off time (5 minutes) are used as a heating cycle, and finally the heating temperature is set within a certain range (75±5°C). The heater is heated for 150-250 cycles, and the time point when the scale increases the most during the period is used as the comparison time point of the scale inhibition rate. At the same time, the corrosion resistance of each group of heaters is compared in this test environment. The corrosion resistance end point is judged by the corrosion penetration of the heater and the short circuit tripping (there is a protection mechanism during the test). The results are shown in Table 1.

[0189] Table 1

[0190] The blank control is a heater surface without any coating. Scale inhibition rate = (weight of scale deposited on the blank heater surface - weight of scale deposited on the coated heater surface) / weight of scale deposited on the blank heater surface * 100%. It should be noted that the spiked water corrosion resistance test in this invention is an accelerated test. Therefore, the spiked water corrosion resistance times in Table 1 do not represent the actual corrosion time of the product. These values ​​are used only to compare the advantages and disadvantages of the various coating groups.

[0191] FIG1 shows the scale state of a heater coated with the coating of Example 1 of the present invention, and FIG2 shows the scale state of a blank control.

[0192] The above results show that the double-layer coating obtained in the embodiment of the present invention can be firmly bonded to the heater substrate and has good anti-scaling and corrosion resistance.

[0193] Finally, it should be noted that the above embodiments are intended to illustrate the present invention only and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and are intended to be encompassed by the claims of the present invention. Industrial Applicability

[0194] The present invention provides a double-layer coating, a preparation method thereof, and an application thereof. The double-layer coating includes a primer and a topcoat. The primer includes a ceramic precursor and a resin. The ceramic precursor is composed of a polysilane compound and a metal precursor. The polysilane compound is selected from one or more of polycarbosilane, polyborosilazane, and polysilicon boron carbon nitrogen. The metal precursor is selected from one or more of a zirconium precursor, an aluminum precursor, and a titanium precursor. The primer of the present invention uses a copolymer obtained by reacting the ceramic precursor and the resin as the main resin, and the ceramic precursor is composed of a specific polysilane compound and a metal precursor. This achieves low adhesion on the material surface, thereby effectively preventing scale formation. It can also improve corrosion resistance and reduce energy consumption, and has good economic value and application prospects.

Claims

1. A double-layer coating, characterized in that: The invention comprises a primer and a surface coating, wherein the primer comprises a ceramic precursor and a resin, wherein the ceramic precursor is composed of a polysilane compound and a metal precursor, wherein the polysilane compound is selected from one or more of polycarbosilane, polyborosilazane and polysilicon boron carbon nitrogen, and the metal precursor is selected from one or more of a zirconium precursor, an aluminum precursor and a titanium precursor.

2. The double-layer coating according to claim 1, characterized in that: The mass ratio of the polysilane compound to the metal precursor is 3:1-1:

6.

3. The double-layer coating according to claim 1 or 2, characterized in that: The resin is polysiloxane resin and / or epoxy resin.

4. The double-layer coating according to claim 3, characterized in that: The resin is a mixture of polysiloxane resin and epoxy resin in a mass ratio of 20:0-8:

15.

5. The double-layer coating according to claim 3, characterized in that: The mass ratio of the ceramic precursor to the resin is 99:1-10:

90.

6. The double-layer coating according to any one of claims 1 to 5, characterized in that: The primer further comprises one or more of a filler, a solvent and an auxiliary agent.

7. The double-layer coating according to claim 6, characterized in that: The filler is selected from one or more of silicon carbide, talc, glass flakes, basalt flakes, muscovite, zinc phosphate, aluminum phosphate, low-melting glass powder, white carbon black, and inorganic pigments, and the mass of the filler accounts for 0.1-50% of the mass of the primer; The solvent is selected from one or more of alkane solvents, ether solvents, ketone solvents, benzene derivative solvents, and ester solvents, and the mass of the solvent accounts for 0.1-50% of the mass of the primer; The auxiliary agent is selected from one or more of a dispersant and a wetting and leveling agent, and the mass of the auxiliary agent accounts for 0.1-5% of the mass of the base coating.

8. The double-layer coating according to any one of claims 1 to 7, characterized in that: The surface coating is composed of 10% to 50% silica sol, 1-25% epoxy modified siloxane, 0-20% polysilane compound, 0.1-5% anti-graffiti additive and 10-70% solvent according to mass percentage.

9. The double-layer coating according to claim 8, characterized in that: The solvent is butyl acetate.

10. The method for preparing the double-layer coating according to any one of claims 1 to 9, characterized in that: The preparation method of the primer comprises: The polysilane compound and the metal precursor are mixed to obtain a ceramic precursor, i.e., component A; Mix and grind the raw materials other than the ceramic precursor to obtain component B with a fineness of ≤15 μm; Finally, the component A is mixed with the component B to obtain the primer; and / or, The preparation method of the surface coating comprises: The surface coating is obtained by mixing silica sol, epoxy-modified siloxane, polysilane compound, anti-graffiti additive and solvent.

11. The preparation method according to claim 10, characterized in that: The mixing is carried out by stirring, and the stirring rate is 100-2000 r / min.

12. A double-layer coating, characterized in that: It is formed by the double-layer coating material according to any one of claims 1 to 9.

13. A coated article comprising a substrate and a coating attached to at least a portion of the surface of the substrate, characterized in that: The coating is a double-layer coating as claimed in claim 12.

14. The product according to claim 13, characterized in that The substrate is a metal substrate, a glass substrate, a ceramic substrate, an enamel substrate, a polymer substrate or a composite substrate of two or more of the above substrates.

15. The product according to claim 13 or 14, characterized in that The product is a household appliance.

16. The article according to claim 15, characterized in that The product is a water heater.

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