Metal or alloy surface treatment method and metal or alloy product

Abstract

The invention provides a metal or alloy surface treatment method and a metal or alloy product. The surface treatment method of the metal or the alloy comprises the following steps: forming an organic-inorganic hybrid layer on the surface of an anodic oxide layer on at least one surface of the metal or the alloy; the organic-inorganic hybrid layer is provided with a spatial network structure formed by silicon dioxide, a copolymer of organic oxysilane containing an epoxy group and a benzophenone compound containing a hydroxyl group, and nanocrystallized superfine carbon black. At least one surface of the metal or alloy product is provided with an anodic oxide layer and an organic-inorganic hybrid layer; the organic-inorganic hybrid layer is provided with a spatial network structure formed by silicon dioxide, a copolymer of organic oxysilane containing an epoxy group and a benzophenone compound containing a hydroxyl group, and nanocrystallized superfine carbon black. According to the technical scheme, the organic-inorganic hybrid high-brightness black layer is formed, so that the high-brightness black coating not only has an excellent appearance orange peel effect and excellent xenon lamp aging resistance, but also has extremely high hardness and extremely excellent car washing resistance.

Description

Surface treatment method of metal or alloy and metal or alloy product

[0001] Cross-reference information

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on September 15, 2023, with application number 202311191388.3 and invention name “A surface treatment method for metal or alloy and metal or alloy product”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The invention relates to a surface treatment method for metal or alloy and a metal or alloy product, belonging to the technical field of metal and alloy treatment. Background Art

[0004] Aluminum alloy trim strips, due to their unique metallic surface texture and low material density, are increasingly popular in automotive exterior trim, gaining popularity among vehicle owners, especially high-end customers. Due to their material properties, aluminum alloy trim strips cannot be used directly as automotive exterior trim and require surface treatment before use. This treatment allows for a more diverse and personalized appearance, while significantly improving surface hardness and corrosion resistance. Common surface treatments for aluminum alloy trim strips include anodizing, baking varnish, and powder coating.

[0005] Aluminum alloys used in automotive exterior parts are most commonly available in natural and high-gloss black finishes. Natural color is produced by anodizing, while high-gloss black is produced by baking or powder coating. The traditional baking process used in the industry is a three-spray, two-bake process. This involves spraying a primer on the aluminum alloy surface after cathodic electrophoresis, then baking it once. The basecoat and topcoat are then sprayed, and then baked once more. The entire process involves three sprayings and two bakes. This is not only complex and generates significant VOC emissions, but also consumes a lot of energy, which is not in line with green, low-carbon, and environmentally friendly development trends. Due to these drawbacks, high-gloss black powder coating has begun to gain traction. This requires only a single spraying and baking process, resulting in virtually no VOC emissions and significantly lower energy consumption. However, powder coating also has its drawbacks. Powder coating is not as hard as baking paint, and since it only has a single coat, lacking the outermost clearcoat protective layer used in baking, it is easily scratched during production and use, severely impacting the appearance. This makes it less acceptable for exterior parts, especially among high-end automotive OEMs.

[0006] At the same time, as an exterior trim product, the appearance quality of the product is as important as its performance. Regardless of whether it is a paint process or a powder spray process, customers have certain requirements for its appearance. The higher the level of the customer, the higher the requirements. However, the current high-gloss black aluminum alloy exterior trim products are difficult to meet the requirements of appearance and performance at the same time.

[0007] Summary of the Invention

[0008] In order to solve the above technical problems, the purpose of the present invention is to provide a surface treatment method for metals or alloys and metal or alloy products, which can meet the appearance requirements and car wash resistance requirements of exterior trim products by forming an organic-inorganic hybrid layer on the surface of the anodized layer, while reducing the manufacturing cost of the product and reducing the emission of VOCs.

[0009] To solve the above technical problems, the present invention first provides a surface treatment method for a metal or alloy, which is to form an organic-inorganic hybrid layer on the surface of an anodic oxide layer on at least one surface of the metal or alloy;

[0010] The organic-inorganic hybrid layer has a spatial network structure formed by silicon dioxide, a copolymer of epoxy-containing organooxysilane and hydroxyl-containing benzophenone compounds, and nano-sized ultrafine carbon black.

[0011] The present invention also provides a metal or alloy product, at least one surface of which has an anodic oxide layer and an organic-inorganic hybrid layer, wherein the organic-inorganic hybrid layer is formed on the surface of the anodic oxide layer;

[0012] The organic-inorganic hybrid layer has a spatial network structure formed by silicon dioxide, a copolymer of epoxy-containing organooxysilane and hydroxyl-containing benzophenone compounds, and nano-sized ultrafine carbon black.

[0013] According to a specific embodiment of the present invention, preferably, the nano-sized ultrafine carbon black is a nano-sized ultrafine carbon black with a particle size D90 of 10-250nm, and more preferably a nano-sized ultrafine carbon black with a particle size D90 of 50-150nm. In the above-mentioned organic-inorganic hybrid layer, the nano-sized ultrafine carbon black is uniformly dispersed in the spatial network structure and the copolymer, and is connected to other components by van der Waals forces. Large-particle carbon black reduces the blackness and has an adverse effect. The present invention controls the size of carbon black particles through the use of nano-technology and formula, which can reduce reflection and scattering, and can present sufficient blackness within the range of ultra-thin coatings.

[0014] According to a specific embodiment of the present invention, the nano-sized ultrafine carbon black is preferably modified nano-sized ultrafine carbon black, so that it can be permanently suspended in the coating system without precipitation. The above-mentioned modification refers to surface carboxylation modification: Grafting modification can increase the repulsive force between carbon black particles, preventing high-concentration carbon black from agglomerating in the base material and coarsening. At the same time, increasing the hydrogen content in the carbon black can reduce the viscosity of the system and increase the fluidity, which helps improve the system's dispersibility and storage stability and increase the blackness.

[0015] According to a specific embodiment of the present invention, preferably, the spatial network structure formed by the silicon dioxide in the organic-inorganic hybrid layer is formed by oligomers generated by dehydration condensation of two or more organooxysilanes.

[0016] According to a specific embodiment of the present invention, preferably, at least one organooxysilane contains an epoxy group. More preferably, the organooxysilane containing an epoxy group includes one or more of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-[(2,3)-epoxypropoxy]propylmethyldimethoxysilane, 3-(2,3-epoxypropoxy)propyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, etc.

[0017] According to a specific embodiment of the present invention, preferably, at least one organooxysilane does not contain an epoxy group. By using both "organooxysilane containing an epoxy group" and "organooxysilane not containing an epoxy group" for preparation, it is possible to ensure that the organic-inorganic hybrid layer has a sufficiently high hardness and is not prone to cracking. More preferably, the organooxysilane not containing an epoxy group includes a general formula R a SiX (4-a) In the compound shown, a is 0-3, R represents a non-hydrolyzable group selected from alkyl, alkenyl, alkynyl and aryl groups, and X represents a hydrolyzable group selected from alkoxy, aryloxy, acyloxy and alkylcarbonyl groups; preferably, the organooxysilane not containing an epoxy group includes: methyltrimethoxysilane, tetramethoxysilane, tetraacetylsilane, methylphenyldimethoxysilane, dimethoxydiacetoxysilane, diethyldiacetoxysilane, di-tert-butoxydiacetoxysilane, diethoxydiphenylsilane, trimethylphenoxysilane, or a combination of two or more thereof.

[0018] According to a specific embodiment of the present invention, preferably, the organooxysilane includes at least one or a combination of two or more of dialkoxysilanes, trialkoxysilanes and tetraalkoxysilanes.

[0019] According to a specific embodiment of the present invention, the copolymer of the epoxy-containing organooxysilane and the hydroxyl-containing benzophenone compound is preferably cross-linked within the spatial network structure via the hydroxyl groups. This means that the copolymer forms bonds with groups within the spatial network structure via the hydroxyl groups, thereby connecting the copolymer to the spatial network structure. The UV absorption capacity of the benzophenone compound can enhance the aging resistance of the organic-inorganic hybrid layer, allowing it to maintain a long-lasting high-gloss black finish without fading or loss of gloss.

[0020] According to a specific embodiment of the present invention, preferably, the hydroxyl-containing benzophenone compound includes one or a combination of two or more of 2,4-dihydroxybenzophenone, 2,2',3-trihydroxybenzophenone, 2,2',4-trihydroxybenzophenone, 2,2',5-trihydroxybenzophenone, 2,2',6-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,4-dihydroxy-2',4'-dimethoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, etc.

[0021] According to a specific embodiment of the present invention, preferably, the thickness of the organic-inorganic hybrid layer is 5 μm-25 μm, more preferably 8-20 μm.

[0022] According to a specific embodiment of the present invention, preferably, when preparing the organic-inorganic hybrid layer, the solvents used include a first co-solvent and a second co-solvent; the first co-solvent includes water; the second co-solvent includes a lower alcohol and / or a glycol ether; thereby, the coating of the present invention can emit much less VOCs during the construction process than traditional coatings.

[0023] According to a specific embodiment of the present invention, preferably, the lower alcohol includes one or a combination of two or more of methanol, ethanol, and isopropanol, and the glycol ether includes one or a combination of two or more of ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether.

[0024] According to a specific embodiment of the present invention, preferably, the organic-inorganic hybrid layer is prepared by coating, for example, by hydrolyzing an oligomer of at least one epoxy-containing organooxysilane (content of 16.3%-18.5%) and an epoxy-free organooxysilane (content of 3.6%-4.8%), adding a copolymer of an epoxy-containing organooxysilane (content of 5.3%-15.4%) and a hydroxyl-containing benzophenone compound (content of 1.3%-3.8%) and nano-sized ultrafine carbon black (content of 2.8%-12.5%), adding a first co-solvent (content of 10.0%-30.0%, preferably 18.2%-24.4%) and a second co-solvent (content of 20.0%-50.0%, preferably 30.3%-40.7%), mixing and stirring at 30-50° C. for a certain period of time, and then coating the mixture on the substrate by conventional coating methods such as spray coating, dip coating, and flow coating. Curing at 150-200°C for 10-90 minutes forms a high-gloss black organic-inorganic hybrid layer. In the above preparation process, the total content of the epoxy-containing organooxysilane (added twice), the epoxy-free organooxysilane, the hydroxyl-containing benzophenone compound, the nano-sized ultrafine carbon black, the first co-solvent, and the second co-solvent is 100%.

[0025] According to a specific embodiment of the present invention, preferably, the alloy is an aluminum alloy.

[0026] According to a specific embodiment of the present invention, preferably, the thickness of the anodized layer is 5 μm-20 μm, more preferably 8 μm-15 μm.

[0027] According to a specific embodiment of the present invention, the anodized layer can be obtained through a conventional process, and after obtaining the anodized layer, the anodized layer can be treated to a dark color through an electrolytic coloring or dyeing process. Preferably, a dyeing process is used, which can make the external high-gloss black coating darker on the one hand, and avoid the possible white exposure of the coating on the other hand.

[0028] According to a specific embodiment of the present invention, the metal or alloy product is preferably a high-gloss black aluminum alloy exterior trim. The high-gloss black aluminum alloy exterior trim comprises an aluminum alloy substrate, an anodized layer obtained on the aluminum alloy substrate using a conventional process (the anodized layer is electrolytically colored or dyed), and an organic-inorganic hybrid high-gloss black coating applied on the anodized layer.

[0029] A key indicator for evaluating the appearance quality of high-gloss black products is the orange peel value, which generally includes three dimensions: R value, SW value, and LW value. The larger the R value and the smaller the SW value and LW value, the better the appearance quality. Typically, the R value of paint and powder coating products is between 6.5-8, and the SW value and LW value are between 10-25. The high-gloss black aluminum alloy exterior accessories of the present invention have an orange peel R value greater than 9.5, and both the SW value and LW value are less than 5. More preferably, the orange peel R value is greater than 10, and both the SW value and LW value are less than 3.

[0030] The surface pencil hardness of the high-gloss black aluminum alloy exterior ornament of the present invention is greater than 4H, and more preferably greater than 5H.

[0031] The car wash resistance of the high-gloss black aluminum alloy exterior decoration of the present invention can meet the following requirements: using the car wash resistance test in the DIN EN ISO 20566 (2013) standard, the 60° gloss retention rate is greater than 85%, and more preferably 90%.

[0032] The aging resistance of the high-gloss black aluminum alloy exterior decoration accessory of the present invention can meet the following requirements: using the xenon lamp aging resistance test in the SAE J2527 standard, it can pass the 4000h test, and more preferably, it can pass the 6000h test.

[0033] According to a specific embodiment of the present invention, preferably, the high-gloss black aluminum alloy exterior trim is an exterior trim of an automobile.

[0034] The technical solution provided by the present invention forms an organic-inorganic hybrid high-gloss black layer on the surface of the anodized layer, which not only has an excellent orange peel effect in appearance and excellent resistance to xenon lamp aging, but also has extremely high hardness and excellent car wash resistance, which can meet the requirements of all automobile OEMs currently on the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a schematic diagram of a specific implementation example of the high-gloss black aluminum alloy exterior trim product provided by the present invention.

[0036] FIG2 is a comparison diagram of the appearance of the high-gloss black aluminum alloy exterior trim product according to Example 1 of the present invention and the high-gloss black exterior trim product according to a conventional baking varnish.

[0037] FIG3 is a comparison diagram of the appearance effects of the high-gloss black aluminum alloy exterior trim product according to Example 1 of the present invention and the high-gloss black exterior trim product according to a conventional baking finish.

[0038] Figure 4 is a diagram showing the appearance of the vehicle after the car wash resistance test.

[0039] FIG5 is a diagram showing the coating states of the exterior trim products of Comparative Examples 1 and 2. FIG.

[0040] FIG6 is a diagram showing the appearance of the exterior trim product having an organic-inorganic hybrid high-gloss black layer according to Example 2 after undergoing a car wash resistance test.

[0041] FIG7 is a diagram showing the appearance of the exterior trim product having an organic-inorganic hybrid high-gloss black layer according to Example 5 after undergoing a car wash resistance test. DETAILED DESCRIPTION

[0042] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0043] The structure of a specific embodiment of the high-gloss black aluminum alloy exterior product provided by the present invention is shown in Figure 1. The high-gloss black aluminum alloy exterior product comprises an aluminum substrate 101, with anodized layers 201 and 202 provided on both sides thereof, respectively. Organic-inorganic hybrid high-gloss black layers 301 and 302 are coated on the surfaces of the two anodized layers 201 and 202, respectively.

[0044] Example 1

[0045] In this embodiment, a high-gloss black aluminum alloy exterior trim product is prepared on the surface of an aluminum alloy substrate, wherein:

[0046] The organooxysilanes used that do not contain epoxy groups are tetramethoxysilane and methyltrimethoxysilane;

[0047] The epoxy-containing organooxysilane used is 3-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0048] The hydroxyl-containing benzophenone compound used is 2,4-dihydroxybenzophenone;

[0049] The first co-solvent is water;

[0050] The second co-solvent is a mixture of isopropyl alcohol, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether in a mass ratio of 20:20:60.

[0051] The specific preparation process is as follows: tetramethoxysilane, methyltrimethoxysilane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane (the amount of the three is 2.5%, 2% and 17% respectively, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer as 100%) are added to 20% of the first cosolvent, and the oligomers are hydrolyzed under a pH of 2-4. Then, 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 2,4-dihydroxybenzophenone (the amount of the two is 12.5%, 3.2% respectively) are added. The invention relates to a method for preparing a high-gloss black organic-inorganic hybrid layer comprising: preparing a copolymer (based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer being 100%), 35% of a second co-solvent, and 7.8% of nano-sized ultrafine carbon black having a particle size D90 of 50-150 nm, followed by mixing and stirring at 30-50° C. for a certain period of time to obtain a workable coating, applying the coating to a substrate by conventional coating methods such as spraying, dipping, or curtain coating, and curing the coating at 150-200° C. for 10-90 minutes to form a high-gloss black organic-inorganic hybrid layer; the organic-inorganic hybrid layer has a thickness of 15-18 μm.

[0052] Example 2

[0053] In this embodiment, a high-gloss black aluminum alloy exterior trim product is prepared on the surface of an aluminum alloy substrate, wherein:

[0054] The organooxysilanes used that do not contain epoxy groups are diethoxydiphenylsilane and dimethoxydiacetoxysilane;

[0055] The epoxy-containing organooxysilane used is 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane;

[0056] The hydroxyl-containing benzophenone compound used is 2,2',6-trihydroxybenzophenone;

[0057] The first co-solvent is water;

[0058] The second co-solvent is a mixture of ethanol: ethylene glycol monomethyl ether: propylene glycol monomethyl ether in a mass ratio of 25:25:50.

[0059] The specific preparation process is as follows: diethoxydiphenylsilane, dimethoxydiacetoxysilane and 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane (the amount of the three is 2.3%, 1.8% and 16.5% respectively, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer being 100%) are added to 23.8% of the first cosolvent, and the generated oligomers are hydrolyzed under a pH of 2-4. Then, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane and 2,2',6-trihydroxybenzophenone (the amount of the two is 2.3%, 1.8% and 16.5% respectively, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer being 100%) are added. The present invention relates to a method for preparing a high-gloss black organic-inorganic hybrid layer comprising the following steps: preparing a copolymer (the weight fractions of the raw materials of the high-gloss black organic-inorganic hybrid layer are 8.5% and 2.6%, respectively, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer being 100%), 36% of a second co-solvent and 8.5% of nano-sized ultrafine carbon black with a particle size D90 of 50-150 nm, followed by mixing and stirring at 30-50° C. for a certain period of time to obtain a workable coating, which is applied to a substrate by conventional coating methods such as spraying, dipping, and flow coating, and cured at 150-200° C. for 10-90 minutes to form a high-gloss black organic-inorganic hybrid layer; the thickness of the organic-inorganic hybrid layer is 15-18 μm.

[0060] Example 3

[0061] In this embodiment, a high-gloss black aluminum alloy exterior trim product is prepared on the surface of an aluminum alloy substrate, wherein:

[0062] The organooxysilane used that does not contain epoxy groups is methyltrimethoxysilane;

[0063] The epoxy-containing organooxysilane used is 3-[(2,3)-epoxypropyloxy]propylmethyldimethoxysilane;

[0064] The hydroxyl-containing benzophenone compound used is 2,4-dihydroxy-2',4'-dimethoxybenzophenone;

[0065] The first co-solvent is water;

[0066] The second co-solvent is a mixture of isopropyl alcohol: diethylene glycol monobutyl ether propylene glycol monomethyl ether: dipropylene glycol monomethyl ether in a mass ratio of 25:30:45.

[0067] The specific preparation process is as follows: 18.6% of the first co-solvent is added to methyltrimethoxysilane and 3-[(2,3)-epoxypropyloxy]propylmethyldimethoxysilane (the amount of the two is 3.7% and 16.8%, respectively, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer as 100%), and the oligomer is hydrolyzed under a pH of 2-4. Then, 3-[(2,3)-epoxypropyloxy]propylmethyldimethoxysilane and 2,4-dihydroxy-2',4'-dimethoxybenzophenone (the amount of the two is 6.8%, respectively) are added. , 1.8%, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer as 100%), 40.7% of the second co-solvent and 11.6% of nano-ultrafine carbon black with a particle size D90 of 50-150nm, followed by mixing and stirring at 30-50°C for a certain time to obtain a workable coating, which is applied to a substrate by conventional coating methods such as spraying, dipping, and flow coating, and cured at 150-200°C for 10-90min to form a high-gloss black organic-inorganic hybrid layer; the thickness of the organic-inorganic hybrid layer is 15-18μm.

[0068] Example 4

[0069] In this embodiment, a high-gloss black aluminum alloy exterior trim product is prepared on the surface of an aluminum alloy substrate, wherein:

[0070] The organooxysilanes used that do not contain epoxy groups are tetraacetylsilane and methylphenyldimethoxysilane;

[0071] The epoxy-containing organooxysilane used is 3-(2,3-epoxypropoxy)propyltriethoxysilane;

[0072] The hydroxyl-containing benzophenone compound used is 2,2',3-trihydroxybenzophenone;

[0073] The first co-solvent is water;

[0074] The second co-solvent is a mixture of isocarbinol: diethylene glycol monobutyl ether propylene glycol monomethyl ether: propylene glycol monomethyl ether in a mass ratio of 15:35:50.

[0075] The specific preparation process is as follows: tetraacetylsilane, methylphenyldimethoxysilane and 3-(2,3-epoxypropoxy)propyltriethoxysilane (the amount of the three is 2.3%, 1.3% and 17.4% respectively, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer as 100%) are added to 24.4% of the first cosolvent, and the oligomers are hydrolyzed under a pH of 2-4. Then, 3-(2,3-epoxypropoxy)propyltriethoxysilane and 2,2',3-trihydroxybenzophenone (the amount of the two is 14.5% respectively) are added. , 1.3%, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer as 100%), 30.5% of a second co-solvent and 8.3% of nano-ultrafine carbon black with a particle size D90 of 50-150nm, followed by mixing and stirring at 30-50°C for a certain time to obtain a workable coating, which is applied to a substrate by conventional coating methods such as spraying, dipping, and flow coating, and cured at 150-200°C for 10-90min to form a high-gloss black organic-inorganic hybrid layer; the thickness of the organic-inorganic hybrid layer is 15-18μm.

[0076] Example 5

[0077] In this embodiment, a high-gloss black aluminum alloy exterior trim product is prepared on the surface of an aluminum alloy substrate, wherein:

[0078] The organooxysilanes used that do not contain epoxy groups are di-tert-butoxydiacetoxysilane and trimethylphenoxysilane;

[0079] The epoxy-containing organooxysilane used is 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane;

[0080] The hydroxyl-containing benzophenone compound used is 2,2',4,4'-tetrahydroxybenzophenone;

[0081] The first co-solvent is water;

[0082] The second co-solvent is a mixture of isopropyl alcohol, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether in a mass ratio of 22:35:43.

[0083] The specific preparation process is as follows: di-tert-butoxydiacetoxysilane, trimethylphenoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (the amount of the three is 2.5%, 2.3% and 17.1% respectively, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer as 100%) are added to 23.6% of the first cosolvent, and the oligomers are hydrolyzed under a pH of 2-4. Then, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 2,2',4,4'-tetrahydroxybenzophenone (the amount of the two is 2.5%, 2.3% and 17.1% respectively, based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer as 100%) are added. The present invention relates to a method for preparing a high-gloss black organic-inorganic hybrid layer comprising: preparing a copolymer (often referred to as a copolymer) comprising 9.8% and 2.6% (based on the total weight fraction of the raw materials of the high-gloss black organic-inorganic hybrid layer being 100%), 38.5% of a second co-solvent, and 3.6% of nano-sized ultrafine carbon black having a particle size D90 of 50-150 nm, followed by mixing and stirring at 30-50° C. for a certain period of time to obtain a workable coating, which is then applied to a substrate by conventional coating methods such as spraying, dipping, or flow coating, and cured at 150-200° C. for 10-90 minutes to form a high-gloss black organic-inorganic hybrid layer; the thickness of the organic-inorganic hybrid layer is 15-18 μm.

[0084] The appearance of the exterior trim product with the organic-inorganic hybrid high-gloss black layer of Example 1 was compared with that of a conventional baking-varnish high-gloss black exterior trim product (this exterior trim product uses a conventional three-spray, two-bake process, with PPG paint as the primer, PPG paint as the color paint, and PPG paint as the clear coat). The results are shown in Figure 2. Figure 2 (a) shows the high-gloss black aluminum alloy exterior trim product prepared in Example 1, and Figure 2 (b) shows the conventional baking-varnish high-gloss black exterior trim product. The boundary clarity and distortion of the object reflection shown in Figure 2 indicate that the appearance of the high-gloss black aluminum alloy exterior trim product of Example 1 is significantly better than that of the conventional baking-varnish high-gloss black exterior trim product.

[0085] The exterior trim product with the organic-inorganic hybrid high-gloss black layer of Example 1 was compared with a conventional high-gloss black exterior trim product with a baking varnish under a stripe inspection light. The difference in product appearance quality can be seen from the reflection of the lamp tube on the product, as shown in Figure 3. Figure 3 (c) shows the high-gloss black aluminum alloy exterior trim product prepared in Example 1, and Figure 3 (d) shows the conventional high-gloss black exterior trim product with a baking varnish. As can be seen from Figure 3, the appearance of the high-gloss black aluminum alloy exterior trim product of Example 1 is significantly better than that of the conventional high-gloss black exterior trim product with a baking varnish.

[0086] A BYK orange peel meter was used to test the orange peel data of the exterior trim products with organic-inorganic hybrid high-gloss black layers of Examples 1-5 and the traditional high-gloss black exterior trim products with baking varnish. The results are as follows: The high-gloss black aluminum alloy exterior trim products prepared in Examples 1-5 have an R value of 9.3-10.5, a SW value of 3.3-5.3, and a LW value of 1.0-3.2; the traditional high-gloss black exterior trim products with baking varnish have an R value of 7.5, a SW value of 25.9, and a LW value of 7.9. From this, it can be judged that the exterior trim products with organic-inorganic hybrid high-gloss black layers of the present invention have a more excellent appearance than the traditional high-gloss black exterior trim products with baking varnish. The test results are shown in Table 1:

[0087] Among them, R value, SW (short wave), and LW (long wave) are data that characterize orange peel; CF is a data characterizing appearance, reflecting the combined results of gloss (15%), distinctness of image (35%), and orange peel (50%). DOI represents distinctness of image.

[0088] Table 1

[0089] The exterior trim product with the organic-inorganic hybrid high-gloss black layer of Example 1, the traditional baking paint high-gloss black exterior trim product (the exterior trim product uses the traditional three-spray two-bake process, in which the primer is PPG paint, the color paint is PPG paint, and the varnish is PPG paint), and the powder-sprayed high-gloss black exterior trim product (the exterior trim product uses Aksu QN009 powder) were subjected to a car wash test. The test results are shown in Table 2:

[0090] Table 2

[0091] Figure 4 shows the appearance after testing according to the car wash resistance test in the DIN EN ISO 20566 (2013) standard.

[0092] Figure 4 (e) shows a powder-coated high-gloss black exterior trim product. It can be seen that the friction marks after the car wash test are very serious. The test results shown in Table 2 show that the 60° gloss retention rate is less than 70%;

[0093] Figure 4 (f) shows a high-gloss black exterior trim product with baking paint. It can be seen that the friction marks after the car wash test are better than those after the powder coating test, but they are still quite serious. The test results shown in Table 2 show that the 60° gloss retention rate is less than 80%;

[0094] Figure (g) in Figure 4 shows the exterior trim product of Example 1 with an organic-inorganic hybrid high-gloss black layer. It can be seen that after the car wash test, there are very few friction marks, which is significantly better than the comparison product. The test results shown in Table 2 show that its 60° gloss retention rate is greater than 90%.

[0095] Figures 6 and 7 show the appearance of exterior trim products with an organic-inorganic hybrid high-gloss black layer, respectively, according to Examples 2 and 5, after undergoing a car wash resistance test. Figures 6 and 7 demonstrate that after the car wash resistance test, the surface friction marks of the products are minimal, almost invisible, significantly outperforming the comparative products. The test results in Table 2 demonstrate that the 60° gloss retention rates for Examples 2 and 5 are both >90%.

[0096] From this, it can be determined that the exterior trim products of the present invention with an organic-inorganic hybrid high-gloss black layer have better car wash resistance than traditional paint high-gloss black exterior trim products and powder-sprayed high-gloss black exterior trim products, and can maintain an excellent appearance for a long time during use.

[0097] Comparative Example 1

[0098] In this comparative example, a high-gloss black aluminum alloy exterior trim product was prepared on the surface of an aluminum alloy substrate, wherein:

[0099] The organooxysilanes used that do not contain epoxy groups are methyltrimethoxysilane and tetraacetylsilane;

[0100] The hydroxyl-containing benzophenone compound used is 2,4-dihydroxybenzophenone;

[0101] The first co-solvent is water;

[0102] The second co-solvent is a mixture of ethanol: isopropanol: dipropylene glycol monomethyl ether in a mass ratio of 25:25:50.

[0103] The specific preparation process is as follows: methyltrimethoxysilane (10.5%) and tetraacetylsilane (11%) are added to a first co-solvent (24%), and hydrolyzed at a pH of 2-4 to generate oligomers. 2,4-dihydroxybenzophenone (14.5%), a second co-solvent (32%), and nano-sized ultrafine carbon black (8%, particle size 5-100 nm) are then added. The mixture is then mixed and stirred at 30-50°C for a certain period of time to obtain a workable coating, which is then applied to a substrate using conventional coating methods such as spraying, dipping, and flow coating. The coating is then cured at 150-200°C for 10-90 minutes to form a high-gloss black organic-inorganic hybrid layer. The thickness of the organic-inorganic hybrid layer is 10-13 μm.

[0104] Comparative Example 2

[0105] In this comparative example, a high-gloss black aluminum alloy exterior trim product was prepared on the surface of an aluminum alloy substrate, wherein:

[0106] The epoxy-containing organooxysilane used is 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane;

[0107] The hydroxyl-containing benzophenone compound used is 2,2',3-trihydroxybenzophenone;

[0108] The first co-solvent is water;

[0109] The second co-solvent is a mixture of ethanol and ethylene glycol monobutyl ether in a mass ratio of 40:60.

[0110] The specific preparation process is as follows: 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane (20%) is selected, a first co-solvent (20%) is added, and an oligomer is hydrolyzed under a pH = 2-4 environment. Then, a copolymer of 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane (12.5%) and 2,2',3-trihydroxybenzophenone (3.2%), a second co-solvent (35%) and nano-sized ultrafine carbon black (9.3%, particle size 5-100nm) are added. Then, the mixture is mixed and stirred at 30-50°C for a certain time to obtain a workable coating, which is applied to the substrate using conventional coating methods such as spraying, dipping, and flow coating, and cured at 150-200°C for 10-90min to form a high-gloss black organic-inorganic hybrid layer; the thickness of the organic-inorganic hybrid layer is 14-17μm.

[0111] Figure 5 (h) shows an exterior trim product with an organic-inorganic hybrid high-gloss black layer in Comparative Example 1. It can be seen that the coating has obvious wrinkles and cracks near the edge area.

[0112] Figure (i) in Figure 5 is the exterior decoration product with an organic-inorganic hybrid high-gloss black layer of Example 2. It can be seen that the coating cracks near the edge area, and particles and some particles can be visually observed to fall off.

Claims

1. A method for surface treatment of a metal or alloy, which comprises forming an organic-inorganic hybrid layer on the surface of an anodic oxide layer on at least one surface of the metal or alloy; in, The organic-inorganic hybrid layer has a spatial network structure formed by silicon dioxide, a copolymer of epoxy-containing organic oxygen silane and hydroxy-containing benzophenone compounds, and nano-sized ultrafine carbon black.

2. The surface treatment method according to claim 1, wherein: The nano-sized ultrafine carbon black is a nano-sized ultrafine carbon black with a particle size D90 of 10-250nm.

3. The surface treatment method according to claim 2, wherein: The nano-sized ultrafine carbon black is a nano-sized ultrafine carbon black with a particle size D90 of 50-150nm.

4. The surface treatment method according to any one of claims 1 to 3, wherein: The spatial network structure formed by silicon dioxide in the organic-inorganic hybrid layer is formed by oligomers generated by dehydration condensation of two or more kinds of organooxysilanes.

5. The surface treatment method according to claim 4, wherein: At least one organooxysilane contains epoxy groups.

6. The surface treatment method according to claim 4 or 5, wherein: The at least one organooxysilane does not contain epoxy groups.

7. The surface treatment method according to any one of claims 4 to 6, wherein: The organooxysilane includes at least one of dialkoxysilanes, trialkoxysilanes and tetraalkoxysilanes, or a combination of two or more thereof.

8. The surface treatment method according to claim 5, wherein: The epoxy-containing organooxysilane includes one or a combination of two or more of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane, 3-[(2,3)-epoxypropyloxy]propylmethyldimethoxysilane, 3-(2,3-epoxypropyloxy)propyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane.

9. The surface treatment method according to claim 6, wherein: The epoxy-free organooxysilane includes the general formula R a SiX (4-a) In the compound shown, a is 0-3, R represents a non-hydrolyzable group selected from alkyl, alkenyl, alkynyl and aryl, and X represents a hydrolyzable group selected from alkoxy, aryloxy, acyloxy and alkylcarbonyl.

10. The surface treatment method according to claim 9, wherein: The epoxy-free organooxysilane includes one or a combination of two or more of methyltrimethoxysilane, tetramethoxysilane, tetraacetylsilane, methylphenyldimethoxysilane, dimethoxydiacetoxysilane, diethyldiacetoxysilane, di-tert-butoxydiacetoxysilane, diethoxydiphenylsilane and trimethylphenoxysilane.

11. The surface treatment method according to any one of claims 1 to 10, wherein: The copolymer of the epoxy-containing organooxysilane and the hydroxy-containing benzophenone compound is cross-linked in the spatial network structure via hydroxyl groups.

12. The surface treatment method according to claim 11, wherein: The hydroxyl-containing benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2',3-trihydroxybenzophenone, 2,2',4-trihydroxybenzophenone, 2,2',5-trihydroxybenzophenone, 2,2',6-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,4-dihydroxy-2',4'-dimethoxybenzophenone, and 2-hydroxy-4-n-octyloxybenzophenone.

13. The surface treatment method according to any one of claims 1 to 12, wherein: The thickness of the organic-inorganic hybrid layer is 5 μm-25 μm.

14. The surface treatment method according to claim 13, wherein: The thickness of the organic-inorganic hybrid layer is 8 μm-20 μm.

15. The surface treatment method according to any one of claims 1 to 14, wherein: The alloy is an aluminum alloy.

16. The surface treatment method according to any one of claims 1 to 15, wherein: The thickness of the anodized layer is 5 μm-20 μm.

17. The surface treatment method according to claim 16, wherein: The thickness of the anodized layer is 8 μm-15 μm.

18. The surface treatment method according to any one of claims 1 to 17, wherein: When preparing the organic-inorganic hybrid layer, the solvent used includes a first co-solvent and a second co-solvent.

19. The surface treatment method according to claim 18, wherein: The organic-inorganic hybrid layer is formed by the following method: at least one epoxy-containing organooxysilane and one epoxy-free organooxysilane are hydrolyzed to generate oligomers, a copolymer of epoxy-containing organooxysilane and hydroxy-containing benzophenone compound and nano-sized ultrafine carbon black are added, a first co-solvent and a second co-solvent are added, mixed and stirred at 30-50° C., then coated on a substrate, and cured at 150-200° C. for 10-90 minutes to form a high-gloss black organic-inorganic hybrid layer.

20. The surface treatment method according to claim 19, wherein: The content of the epoxy-containing organooxysilane in the oligomer generated by hydrolysis is 16.3%-18.5%, the content of the epoxy-free organooxysilane is 3.6%-4.8%, the content of the epoxy-containing organooxysilane in the copolymer generated by the copolymer with the hydroxyl-containing benzophenone compound is 5.3%-15.4%, the content of the hydroxyl-containing benzophenone compound is 1.3%-3.8%, the content of the nano-sized ultrafine carbon black is 2.8%-12.5%, the content of the first co-solvent is 10.0%-30.0%, and the content of the second co-solvent is 30.3%-40.7%.

21. The surface treatment method according to claim 20, wherein: The content of the first co-solvent is 18.2%-24.4%.

22. The surface treatment method according to claim 20, wherein: The content of the second co-solvent is 30.3%-40.7%.

23. The surface treatment method according to claim 19, wherein: The first co-solvent includes water.

24. The surface treatment method according to claim 19, wherein: The second co-solvent includes lower alcohols and / or glycol ethers.

25. The surface treatment method according to claim 24, wherein: The lower alcohol includes one or a combination of two or more of methanol, ethanol, and isopropanol; the diol ether includes one or a combination of two or more of ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether.

26. A metal or alloy product, at least one surface of which has an anodized layer and an organic-inorganic hybrid layer, wherein: The organic-inorganic hybrid layer is formed on the surface of the anodized layer; The organic-inorganic hybrid layer has a spatial network structure formed by silicon dioxide, a copolymer of epoxy-containing organooxysilane and hydroxy-containing benzophenone compounds, and nano-sized ultrafine carbon black.

27. The metal or alloy product according to claim 26, wherein: The nano-sized ultrafine carbon black is a nano-sized ultrafine carbon black with a particle size D90 of 10-250nm.

28. The metal or alloy product according to claim 27, wherein: The nano-sized ultrafine carbon black is a nano-sized ultrafine carbon black with a particle size D90 of 50-150nm.

29. The metal or alloy product according to any one of claims 26 to 28, wherein: The spatial network structure formed by silicon dioxide in the organic-inorganic hybrid layer is formed by oligomers generated by dehydration condensation of two or more kinds of organooxysilanes.

30. The metal or alloy product according to claim 29, wherein: At least one organooxysilane contains epoxy groups.

31. The metal or alloy product according to claim 29 or 30, wherein: The at least one organooxysilane does not contain epoxy groups.

32. The metal or alloy product according to any one of claims 29 to 31, wherein: The organooxysilane includes at least one of dialkoxysilanes, trialkoxysilanes and tetraalkoxysilanes, or a combination of two or more thereof.

33. The metal or alloy product according to claim 30, wherein: The epoxy-containing organooxysilane includes one or a combination of two or more of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane, 3-[(2,3)-epoxypropyloxy]propylmethyldimethoxysilane, 3-(2,3-epoxypropyloxy)propyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane.

34. The metal or alloy article according to claim 31, wherein: The epoxy-free organooxysilane includes the general formula R a SiX (4-a) In the compound shown, a is 0-3, R represents a non-hydrolyzable group selected from alkyl, alkenyl, alkynyl and aryl, and X represents a hydrolyzable group selected from alkoxy, aryloxy, acyloxy and alkylcarbonyl.

35. The metal or alloy product according to claim 34, wherein: The epoxy-free organooxysilane includes one or a combination of two or more of methyltrimethoxysilane, tetramethoxysilane, tetraacetylsilane, methylphenyldimethoxysilane, dimethoxydiacetoxysilane, diethyldiacetoxysilane, di-tert-butoxydiacetoxysilane, diethoxydiphenylsilane and trimethylphenoxysilane.

36. The metal or alloy product according to any one of claims 26 to 35, wherein: The copolymer of the epoxy-containing organooxysilane and the hydroxy-containing benzophenone compound is cross-linked in the spatial network structure via hydroxyl groups.

37. The metal or alloy article according to claim 36, wherein: The hydroxyl-containing benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2',3-trihydroxybenzophenone, 2,2',4-trihydroxybenzophenone, 2,2',5-trihydroxybenzophenone, 2,2',6-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,4-dihydroxy-2',4'-dimethoxybenzophenone, and 2-hydroxy-4-n-octyloxybenzophenone.

38. The metal or alloy product according to any one of claims 26 to 37, wherein: The thickness of the organic-inorganic hybrid layer is 5 μm-25 μm.

39. The metal or alloy product according to claim 38, wherein: The thickness of the organic-inorganic hybrid layer is 8 μm-20 μm.

40. The metal or alloy product according to any one of claims 26 to 39, wherein: The alloy is an aluminum alloy.

41. The metal or alloy product according to any one of claims 26 to 40, wherein: The thickness of the anodized layer is 5 μm-20 μm.

42. The metal or alloy product according to claim 41, wherein: The thickness of the anodized layer is 8 μm-15 μm.

43. The metal or alloy product according to any one of claims 26 to 42, wherein: When preparing the organic-inorganic hybrid layer, the solvent used includes a first co-solvent and a second co-solvent.

44. The metal or alloy article according to claim 43, wherein: The organic-inorganic hybrid layer is formed by the following method: at least one epoxy-containing organooxysilane and one epoxy-free organooxysilane are hydrolyzed to generate oligomers, a copolymer of epoxy-containing organooxysilane and hydroxy-containing benzophenone compound and nano-sized ultrafine carbon black are added, a first co-solvent and a second co-solvent are added, mixed and stirred at 30-50° C., then coated on a substrate, and cured at 150-200° C. for 10-90 minutes to form a high-gloss black organic-inorganic hybrid layer.

45. The metal or alloy article according to claim 44, wherein: The content of the epoxy-containing organooxysilane in the oligomer generated by hydrolysis is 16.3%-18.5%, the content of the epoxy-free organooxysilane is 3.6%-4.8%, the content of the epoxy-containing organooxysilane in the copolymer generated by the copolymer with the hydroxyl-containing benzophenone compound is 5.3%-15.4%, the content of the hydroxyl-containing benzophenone compound is 1.3%-3.8%, the content of the nano-sized ultrafine carbon black is 2.8%-12.5%, the content of the first co-solvent is 10.0%-30.0%, and the content of the second co-solvent is 30.3%-40.7%.

46. ​​The metal or alloy article according to claim 45, wherein: The content of the first co-solvent is 18.2%-24.4%.

47. The metal or alloy article according to claim 45, wherein: The content of the second co-solvent is 30.3%-40.7%.

48. The metal or alloy article according to claim 44, wherein: The first co-solvent includes water.

49. The metal or alloy article according to claim 44, wherein: The second co-solvent includes lower alcohols and / or glycol ethers.

50. The metal or alloy article according to claim 49, wherein: The lower alcohol includes one or a combination of two or more of methanol, ethanol, and isopropanol; the diol ether includes one or a combination of two or more of ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether.

51. The metal or alloy product according to any one of claims 26 to 50, wherein: The metal or alloy product is a high-gloss black aluminum alloy exterior trim.

52. The metal or alloy article according to claim 51, wherein: The orange peel R value of the high-gloss black aluminum alloy exterior trim is greater than 9.5, and the SW value and LW value are both less than 5.

53. The metal or alloy article according to claim 52, wherein: The high-gloss black aluminum alloy exterior trim is an exterior trim of an automobile.

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