Anti-settling high-metal-texture water-based electrosilvering coating as well as preparation method and application thereof

Abstract

The invention provides an anti-settling high-metal-texture water-based electrosilvering coating as well as a preparation method and application thereof. The water-based electrosilvering coating comprises the following components in parts by mass: 0.5-3 parts of water-based electrosilvering paste; 4 to 12 parts of acrylic acid modified polyurethane resin; 2-6 parts of an acrylic emulsion; 0.5 to 2 parts of amino resin; 0.5 to 2 parts of water-based blocked isocyanate; 2-6 parts of a directional anti-settling agent; 25 to 35 parts of a cosolvent; and 30-60 parts of water. Compared with a traditional water-based electrosilvering coating, the water-based electrosilvering coating provided by the invention has better anti-settling performance and aluminum powder directionality, the fineness of the coating is smaller, the coating is more stable, and a manufactured water-based electrosilvering coating is stronger in metal texture.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and specifically comprises an anti-settling high-metallic-texture water-based electroplated silver coating, and a preparation method and application thereof. Background Art

[0002] As a common means of transportation, cars have entered thousands of households. With the improvement of people's living standards, the requirements for car appearance are getting higher and higher. In order to improve the appearance of vehicles, various aluminum alloy wheels with more personality are becoming more and more popular on the market, among which the proportion of electroplated silver wheels is gradually increasing. Wheels painted with electroplated silver paint can achieve the same effect as electroplating, with a bright and fashionable surface, which can significantly increase the appearance of the product. Therefore, the demand for electroplated silver paint by wheel manufacturers is also increasing.

[0003] CN115873462A discloses a water-based electroplated silver coating for automobile wheels prepared with modified water-based polyurethane and water-based group-modified acrylic acid as the base resin. The coating prepared by the coating meets the application requirements in terms of hardness, initial adhesion and other properties. At the same time, it has excellent performance in terms of recoating adhesion, water resistance, compatibility with transparent powder, salt spray resistance and acid and alkali resistance. It can meet the outdoor use requirements in humid environments or acid rain environments, and is not prone to corrosion. However, the patent does not provide research on how to prevent the sedimentation of water-based silver paste. For electroplated silver coatings, due to the presence of a large amount of water and cosolvents, the coating viscosity is low, and aluminum powder precipitation is prone to occur. If it is not stirred evenly during use, it may cause color abnormalities, color differences and other problems. In CN112694805A, the arrangement and storage stability of silver powder are improved by introducing an aluminum powder directing agent, and the risk of stratification during storage is reduced. However, due to the differences in polymer structures formed by different base resins, when introducing aluminum powder directing agents or anti-settling agents into new coating systems, there may be problems of poor applicability, making it difficult to maintain some conventional properties of the coating. Therefore, efforts should be made to develop electroplated silver coating formulas that meet application requirements under different coating systems, so as to provide better technical guidance for researchers. Summary of the invention

[0004] In view of the above problems existing in the prior art, the first object of the present invention is to provide a water-based electroplated silver coating for automobile wheels. By introducing a directional anti-settling agent into the formula and controlling the addition method thereof, the anti-settling property of the water-based electroplated silver coating and the stability of the directional arrangement of aluminum powder can be significantly improved, the coating has a smaller fineness and is more stable, and when added to a specific coating system, the manufactured water-based electroplated silver coating has a stronger metallic texture and does not turn yellow when baked at high temperature.

[0005] The second object of the present invention is to provide a method for preparing the water-based electroplating silver coating as described above.

[0006] The third object of the present invention is to provide a use of the water-based electroplating silver paint as described above in the preparation of paint for automobile wheels.

[0007] To achieve the above first object, the technical solution adopted by the present invention includes:

[0008] The present invention discloses a water-based electroplated silver coating for automobile wheels. The water-based electroplated silver coating comprises

[0009] 0.5-3 parts of water-based electroplating silver paste;

[0010] 4-12 parts of acrylic acid modified polyurethane resin;

[0011] 2-6 parts of acrylic emulsion;

[0012] Amino resin 0.5-2 parts;

[0013] 0.5-2 parts of water-based blocked isocyanate;

[0014] 2-6 parts of directional anti-settling agent;

[0015] 25-35 parts of cosolvent;

[0016] 30-60 parts of water.

[0017] Furthermore, the directional anti-settling agent is selected from one or more of ethylene-vinyl acetate copolymer wax emulsion, polyethylene wax emulsion and polyamide wax emulsion; preferably polyamide wax emulsion.

[0018] Furthermore, the acrylic modified polyurethane resin is selected from one or more of Sanyo Chemical Ucoat ux-3945, allnex Daotan TW 6431, allnex NewHua-6928 and allnex Daotan 7061.

[0019] Furthermore, the amino resin is selected from one or more of INEOS HM-2608, allnex CYMEL 303, allnex CYMEL 325 and Changchun Chemical M-40ST.

[0020] Further, the acrylic emulsion is selected from one or more of allnex SETAQUA 6802, allnex SETAQUA 6803, Jinhuili HD-MB019 and allnex SC6807.

[0021] Furthermore, the water-based blocked isocyanate is selected from one or more of MR-850 from Zhide, Imprafix 2794 from Covestro and WM44-L70G from Asahi Kasei.

[0022] Furthermore, the co-solvent is selected from one or more of methanol, ethanol, n-propanol, isopropanol, propylene alcohol, ethylene glycol, ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether and diethylene glycol butyl ether.

[0023] Furthermore, the water-based electroplating silver paint further comprises 0.5-2 parts of a neutralizer; the neutralizer is selected from dimethylethanolamine and / or triethylamine.

[0024] To achieve the above second purpose, the technical solution adopted by the present invention includes:

[0025] The present invention discloses a method for preparing the water-based electroplated silver coating as described above, comprising the following steps:

[0026] (1) adding 0.5-3 parts of aqueous silver electroplating paste and 2-6 parts of co-solvent to the first reactor under stirring, and continuing stirring for 8-15 minutes to obtain an aqueous silver electroplating paste dilution;

[0027] (2) adding 4-12 parts of acrylic modified polyurethane resin, 0.5-2 parts of amino resin, 2-6 parts of acrylic emulsion, remaining co-solvent and 0.5-2 parts of water-based blocked isocyanate to the second reactor under stirring, stirring for 20-40 minutes and filtering to obtain a resin mixture;

[0028] (3) adding 2-6 parts of directional anti-settling agent, part of water and part of the resin mixed solution prepared in step (2) to the third reactor under stirring to prepare a directional anti-settling agent mixed solution;

[0029] (4) under stirring conditions, adding the aqueous silver electroplating slurry dilution prepared in step (1), the directional anti-settling agent mixed solution prepared in step (3) and the remaining water into the second reactor to obtain.

[0030] Furthermore, when preparing the directional anti-settling agent mixed solution in step (3), the amount of water added is 0.5-1.5 parts by mass of water per 1 part by mass of the directional anti-settling agent;

[0031] The amount of the resin mixture added is 0.5-1.5 parts by mass of the resin mixture per 1 part by mass of the directional anti-settling agent.

[0032] To achieve the third objective, the technical solution adopted by the present invention includes:

[0033] The present invention discloses the use of the water-based electroplating silver paint in preparing paint for automobile wheels.

[0034] Beneficial effects of the present invention:

[0035] The present invention discloses an anti-settling high metallic texture water-based electroplated silver coating, which exhibits excellent pencil hardness, adhesion, CASS resistance, neutral salt spray resistance and other properties when various components are used in combination, and at the same time, the anti-settling of the coating and the metallic gloss of the coating film are significantly improved. Compared with ordinary water-based electroplated silver coatings, the coating has the following improvements:

[0036] 1. The present invention introduces a directional anti-settling agent into the coating formula, which can prevent aluminum powder from settling and significantly improve the stability of the directional arrangement of aluminum powder, so that the water-based electroplated silver coating can be stably placed at room temperature for more than 3 days without obvious sedimentation, and the metallic luster of the coating film is stronger.

[0037] 2. Through a large number of experimental attempts, the method of adding directional anti-settling agent was improved, that is, the directional anti-settling agent was mixed with part of the water and resin mixture in advance, and then added back to the resin mixture. This can improve the compatibility of the directional anti-settling agent with the coating system, make the resulting coating finer and more stable, and prevent the coating from coarsening and obvious particles from appearing during spraying.

[0038] 3. The acrylic modified polyurethane resin used in the formula of the present invention can react with the amino resin to produce a polymer with a high cross-linking density. The introduction of the water-based acrylic emulsion can further improve the orientation of the aluminum powder and the metallic gloss of the coating film. The introduction of the water-based blocked isocyanate can also improve the recoating adhesion of the coating film and improve the comprehensive performance of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0040] Figure 1 The actual pictures of the coatings prepared in Example 1, Example 2 and Comparative Example 1 after being placed at room temperature for 5 days are shown. DETAILED DESCRIPTION

[0041] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and drawings. It should be clear that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In the case of illustrating and explaining the purpose of the present invention through the following examples, the components of the composition are explained in parts by weight as a general standard. Unless otherwise specified, for the sake of simplicity, the "parts" described in the examples of the present invention have the same meaning as parts by weight.

[0043] Aiming at the problems of easy precipitation of aluminum powder and poor metallic gloss of the coating film in the traditional water-based electroplated silver coating, the present invention provides an anti-sedimentation high metallic texture water-based electroplated silver coating, which comprises, by weight,

[0044] 0.5-3 parts of water-based electroplating silver paste;

[0045] 4-12 parts of acrylic acid modified polyurethane resin;

[0046] 2-6 parts of acrylic emulsion;

[0047] Amino resin 0.5-2 parts;

[0048] 0.5-2 parts of water-based blocked isocyanate;

[0049] 2-6 parts of directional anti-settling agent;

[0050] 25-35 parts of cosolvent;

[0051] 30-60 parts of water.

[0052] The coating system provided by the present invention is based on acrylic acid modified polyurethane resin as main resin, which can react with amino resin to obtain a polymer with high crosslinking density. In the initial experimental design, it was found that after adding a directional anti-settling agent to the coating system, the problems of aluminum powder precipitation, floating color and arrangement orientation can indeed be improved to a certain extent. In a specific embodiment, the directional anti-settling agent is selected from one or more of ethylene-vinyl acetate copolymer wax emulsion, polyethylene wax emulsion and polyamide wax emulsion, preferably polyamide wax emulsion. The directional anti-settling agent can be directly purchased from commercial products or can be prepared by itself. Exemplarily, the polyamide wax emulsion is composed of 33 parts of polyamide wax, 1 part of ethylene glycol butyl ether and 66 parts of water.

[0053] Furthermore, the polyamide wax is selected from one or more of BYK-8421, Hemmings PW-2100, Walter PA-800 and Walter PA-600.

[0054] Furthermore, the acrylic modified polyurethane resin is selected from one or more of Sanyo Chemical Ucoat ux-3945, allnex Daotan TW 6431, allnex NewHua-6928 and allnex Daotan 7061.

[0055] Furthermore, the amino resin is selected from one or more of INEOS HM-2608, allnex CYMEL 303, allnex CYMEL 325 and Changchun Chemical M-40ST.

[0056] Further, the acrylic emulsion is selected from one or more of allnex SETAQUA 6802, allnex SETAQUA 6803, Jinhuili HD-MB019 and allnex SC6807.

[0057] Furthermore, the water-based blocked isocyanate is selected from one or more of MR-850 from Zhide, Imprafix 2794 from Covestro and WM44-L70G from Asahi Kasei.

[0058] Furthermore, the electrical conductivity of the water is 0.055-10 μS / cm.

[0059] Furthermore, the co-solvent is selected from one or more of methanol, ethanol, n-propanol, isopropanol, propylene alcohol, ethylene glycol, ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether and diethylene glycol butyl ether.

[0060] Furthermore, the water-based electroplating silver paint further comprises 0.5-2 parts of a neutralizer; the neutralizer is selected from dimethylethanolamine and / or triethylamine; illustratively, it can be selected from BASF DMEA.

[0061] Furthermore, the water-based electroplated silver coating further comprises one or more of a leveling agent, a wetting agent and a defoaming agent. For example, the leveling agent is selected from one or two of BYK333 and Dow Corning DC-51, the wetting agent is selected from one or two of BYK348 and BYK345, and the defoaming agent is selected from one or two of BYK011 and BYK028.

[0062] As for the preparation process of electroplated silver paint, technicians usually add the electroplated silver paste directly into a mixed solution containing components such as resin and additives, and stir and mix to obtain a qualified electroplated silver paint product. However, it was found in experiments that after being prepared according to the conventional preparation process, the electroplated silver paint of the present invention will appear coarsening, the fineness will increase, and even particles will appear during spraying, which seriously affects the appearance of the coating film. It was later discovered that it was mainly caused by the addition method of the directional anti-settling agent. For the coating system provided by the present invention, the fineness of the finished coating is very sensitive to the addition method of the directional anti-settling agent, and the coating fineness obtained by different addition methods is different. To this end, the present invention improves the preparation process of the electroplated silver paint, and provides a preparation method of a water-based electroplated silver paint suitable for the coating system of the present invention, comprising the following steps:

[0063] (1) adding 0.5-3 parts of aqueous silver electroplating paste and 2-6 parts of co-solvent to the first reactor under stirring, and continuing stirring for 8-15 minutes to obtain an aqueous silver electroplating paste dilution;

[0064] (2) adding 4-12 parts of acrylic modified polyurethane resin, 0.5-2 parts of amino resin, 2-6 parts of acrylic emulsion, remaining co-solvent and 0.5-2 parts of water-based blocked isocyanate to the second reactor under stirring, stirring for 20-40 minutes and filtering to obtain a resin mixture;

[0065] (3) adding 2-6 parts of directional anti-settling agent, part of water and part of the resin mixed solution prepared in step (2) to the third reactor under stirring to prepare a directional anti-settling agent mixed solution;

[0066] (4) under stirring conditions, adding the aqueous silver electroplating slurry dilution prepared in step (1), the directional anti-settling agent mixed solution prepared in step (3) and the remaining water into the second reactor to obtain.

[0067] In the preparation method, the directional anti-settling agent is first pre-mixed and then added to the resin mixture, which is conducive to the good dissolution of polyamide wax in the aqueous electro-silvering system, and the phenomenon of coarsening and deterioration of fineness will not occur, which affects the appearance of the paint film. If only one of water or part of the resin mixture is mixed with the directional anti-settling agent during the pre-mixing process, the effect of improving the coarsening and the fineness of the coating is limited. In addition, the mixing ratio between the directional anti-settling agent, water and the resin mixture also needs to be controlled. In a specific embodiment, the addition of water is that the directional anti-settling agent of every 1 mass part adds 0.5-1.5 mass parts of water, and the addition of the resin mixture is that the directional anti-settling agent of every 1 mass part adds 0.5-1.5 mass parts of resin mixture, which is more obvious to the effect of improving the coarsening and the fineness of the coating.

[0068] Furthermore, in step (1), the stirring speed is 400-500 r / min; in step (2), the stirring speed is 300-350 r / min; in step (3), the stirring speed is 800-1000 r / min; in step (4), the stirring speed is 400-500 r / min.

[0069] The technical solution will be further described below through the following embodiments.

[0070] Example 1

[0071] This embodiment provides a water-based electroplating silver coating, and its formula is shown in Table 1.

[0072] Table 1

[0073]

[0074] The polyamide wax emulsion is prepared according to the following steps:

[0075] Under stirring conditions, 66 parts of pure water, 1 part of ethylene glycol butyl ether and 33 parts of polyamide wax (Hemmings THIXATROLP2100W) are mixed and stirred for 20-40 minutes to obtain the obtained product.

[0076] This embodiment also provides a method for preparing a water-based electroplated silver coating, the steps of which are as follows:

[0077] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0078] Under stirring conditions of 300-350 r / min, 9.3 parts of acrylic modified polyurethane resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer, 3.5 parts of acrylic emulsion and 0.8 parts of water-based blocked isocyanate were added to the second reactor in sequence, stirred for 20-40 minutes and then filtered to obtain a resin mixture for water-based electroplating silver;

[0079] Under stirring conditions of 800-1000 r / min, 3 parts of pure water, 3 parts of polyamide wax emulsion and 3 parts of the resin mixed solution in the second reactor were added into the third reactor to obtain a polyamide wax mixed solution;

[0080] Under stirring condition of 400-500 r / min, add the aqueous silver plating paste dilution in the first reactor and the polyamide wax mixed solution in the third reactor into the second reactor, and then add 42.4 parts of pure water to obtain.

[0081] Example 2

[0082] This embodiment provides a water-based electroplating silver coating, and its formula is shown in Table 2.

[0083] Table 2

[0084]

[0085] The preparation of the polyamide wax emulsion is the same as in Example 1.

[0086] This embodiment also provides a method for preparing a water-based electroplated silver coating, the steps of which are as follows:

[0087] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0088] Under stirring conditions of 300-350 r / min, 9.3 parts of acrylic modified polyurethane resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer, 3.5 parts of acrylic emulsion and 0.8 parts of water-based blocked isocyanate were added to the second reactor in sequence, stirred for 20-40 minutes and then filtered to obtain a resin mixture for water-based electroplating silver;

[0089] Under stirring conditions of 800-1000 r / min, 6 parts of pure water, 6 parts of polyamide wax emulsion, and 6 parts of the resin mixture in the second reactor were added to the third reactor to obtain a polyamide wax mixture;

[0090] Under stirring conditions of 400-500 r / min, add the aqueous silver plating paste dilution in the first reactor and the polyamide wax mixed solution in the third reactor into the second reactor, and then add 36.4 parts of pure water to obtain.

[0091] Example 3

[0092] This embodiment provides a water-based electroplating silver coating, and its formula is shown in Table 3.

[0093] Table 3

[0094]

[0095]

[0096] The preparation of the polyamide wax emulsion is the same as in Example 1.

[0097] This embodiment also provides a method for preparing a water-based electroplated silver coating, the steps of which are as follows:

[0098] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0099] Under stirring conditions of 300-350 r / min, 9.3 parts of acrylic modified polyurethane resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer, 3.5 parts of acrylic emulsion and 0.8 parts of water-based blocked isocyanate were added to the second reactor in sequence, stirred for 20-40 minutes and then filtered to obtain a resin mixture for water-based electroplating silver;

[0100] Under stirring conditions of 800-1000 r / min, 6 parts of pure water, 5 parts of polyamide wax emulsion, and 6 parts of the resin mixture in the second reactor were added to the third reactor to obtain a polyamide wax mixture;

[0101] Under stirring conditions of 400-500 r / min, add the aqueous silver plating paste dilution in the first reactor and the polyamide wax mixed solution in the third reactor into the second reactor, and then add 37.4 parts of pure water to obtain.

[0102] Comparative Example 1

[0103] The water-based electroplating silver coating provided in this comparative example is similar to the formulation of Example 1, except that the polyamide wax emulsion is not added.

[0104] This comparative example also provides a method for preparing a water-based electroplated silver coating, the steps of which are as follows:

[0105] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0106] Under stirring conditions of 300-350 r / min, 9.3 parts of acrylic modified polyurethane resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer, 3.5 parts of acrylic emulsion and 0.8 parts of water-based blocked isocyanate were added to the second reactor in sequence, stirred for 20-40 minutes and then filtered to obtain a resin mixture for water-based electroplating silver;

[0107] Under stirring condition of 400-500 r / min, add the aqueous silver plating slurry dilution in the first reactor into the second reactor, and then add 45.4 parts of pure water to obtain.

[0108] Comparative Example 2

[0109] The water-based electroplating silver coating provided in this comparative example is similar to the formulation of Example 1, except that no water-based blocked isocyanate is added.

[0110] The preparation of the polyamide wax emulsion is the same as in Example 1.

[0111] This comparative example also provides a method for preparing a water-based electroplated silver coating, the steps of which are as follows:

[0112] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0113] Under stirring conditions of 300-350 r / min, 9.3 parts of acrylic modified polyurethane resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer and 3.5 parts of acrylic emulsion were added to the second reactor in sequence, stirred for 20-40 minutes and then filtered to obtain a resin mixture for water-based electroplating silver;

[0114] Under stirring conditions of 800-1000 r / min, 3 parts of pure water, 3 parts of polyamide wax emulsion, and 3 parts of the resin mixture in the second reactor were added to the third reactor to obtain a polyamide wax mixture;

[0115] Under stirring condition of 400-500 r / min, add the aqueous silver plating paste dilution in the first reactor and the polyamide wax mixed solution in the third reactor into the second reactor, and then add 42.4 parts of pure water to obtain.

[0116] Comparative Example 3

[0117] The water-based electroplating silver coating provided in this comparative example has the same formulation as that of Example 1, the only difference being the method of adding the polyamide wax emulsion.

[0118] The preparation of the polyamide wax emulsion is the same as in Example 1.

[0119] This comparative example also provides a method for preparing a water-based electroplated silver coating, the steps of which are as follows:

[0120] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0121] Under stirring conditions of 300-350 r / min, 9.3 parts of acrylic modified polyurethane resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer, 3.5 parts of acrylic emulsion, and 0.8 parts of water-based blocked isocyanate were added to the second reactor in sequence, stirred for 20-40 minutes, and then filtered to obtain a resin mixture for water-based electroplating silver;

[0122] Under stirring conditions of 400-500 r / min, add the polyamide wax emulsion and the aqueous electroplating silver paste dilution in the first reactor into the second reactor, and then add 45.4 parts of pure water to obtain the product.

[0123] Comparative Example 4

[0124] The water-based electroplating silver coating provided in this comparative example is similar to the formulation of Example 1, except that the acrylic modified polyurethane resin NewHua-6928 is replaced by polyester resin 5050-B-75, and the other components are the same as those in Example 1.

[0125] The preparation of the polyamide wax emulsion is the same as in Example 1.

[0126] This comparative example also provides a method for preparing a water-based electroplated silver coating, the steps of which are as follows:

[0127] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0128] Under stirring conditions of 300-350 r / min, 9.3 parts of polyester resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer, 3.5 parts of acrylic emulsion and 0.8 parts of water-based blocked isocyanate were added to the second reactor in sequence, stirred for 20-40 minutes and then filtered to obtain a resin mixture for water-based electroplating silver;

[0129] Under stirring conditions of 800-1000 r / min, 3 parts of pure water, 3 parts of polyamide wax emulsion, and 3 parts of the resin mixture in the second reactor were added to the third reactor to obtain a polyamide wax mixture;

[0130] Under stirring condition of 400-500 r / min, add the aqueous silver plating paste dilution in the first reactor and the polyamide wax mixed solution in the third reactor into the second reactor, and then add 42.4 parts of pure water to obtain.

[0131] Comparative Example 5

[0132] The water-based electroplating silver coating provided in this comparative example is similar to the formulation of Example 1, except that the acrylic resin SC6807 is used to replace the acrylic modified polyurethane resin NewHua-6928, and the other components are the same as those in Example 1.

[0133] The preparation of the polyamide wax emulsion is the same as in Example 1.

[0134] This comparative example also provides a method for preparing a water-based electroplated silver coating, the steps of which are as follows:

[0135] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0136] Under stirring conditions of 300-350 r / min, 9.3 parts of acrylic resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer, 3.5 parts of acrylic emulsion and 0.8 parts of water-based blocked isocyanate were added to the second reactor in sequence, stirred for 20-40 minutes and then filtered to obtain a resin mixture for water-based electroplating silver;

[0137] Under stirring conditions of 800-1000 r / min, 3 parts of pure water, 3 parts of polyamide wax emulsion, and 3 parts of the resin mixture in the second reactor were added to the third reactor to obtain a polyamide wax mixture;

[0138] Under stirring condition of 400-500 r / min, add the aqueous silver plating paste dilution in the first reactor and the polyamide wax mixed solution in the third reactor into the second reactor, and then add 42.4 parts of pure water to obtain.

[0139] Comparative Example 6

[0140] The water-based electroplating silver coating provided in this comparative example is similar to the formulation of Example 1, except that the acrylic modified polyurethane resin NewHua-6928 is replaced by the polyurethane resin VTW6462, and the other components are the same as those in Example 1.

[0141] The preparation of the polyamide wax emulsion is the same as in Example 1.

[0142] This comparative example also provides a method for preparing a water-based electroplated silver coating, the steps of which are as follows:

[0143] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0144] Under stirring conditions of 300-350 r / min, 9.3 parts of polyurethane resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer, 3.5 parts of acrylic emulsion and 0.8 parts of water-based blocked isocyanate were added to the second reactor in sequence, stirred for 20-40 minutes and then filtered to obtain a resin mixture for water-based electroplating silver;

[0145] Under stirring conditions of 800-1000 r / min, 3 parts of pure water, 3 parts of polyamide wax emulsion, and 3 parts of the resin mixture in the second reactor were added to the third reactor to obtain a polyamide wax mixture;

[0146] Under stirring condition of 400-500 r / min, add the aqueous silver plating paste dilution in the first reactor and the polyamide wax mixed solution in the third reactor into the second reactor, and then add 42.4 parts of pure water to obtain.

[0147] Comparative Example 7

[0148] The water-based electroplating silver coating provided in this comparative example has the same formulation as that of Example 1, the only difference being the method of adding the polyamide wax emulsion.

[0149] Under stirring conditions of 400-500 r / min, 2 parts of aqueous electroplating silver paste and 4 parts of ethylene glycol butyl ether were added to the first reactor, and stirring was continued for 8-15 minutes to obtain an aqueous electroplating silver paste dilution solution;

[0150] Under stirring conditions of 300-350 r / min, 9.3 parts of acrylic modified polyurethane resin, 1 part of amino resin, 29 parts of cosolvent, 1.7 parts of neutralizer, 0.15 parts of wetting agent, 0.15 parts of defoamer, 3.5 parts of acrylic emulsion and 0.8 parts of water-based blocked isocyanate were added to the second reactor in sequence, stirred for 20-40 minutes and then filtered to obtain a resin mixture for water-based electroplating silver;

[0151] Under stirring conditions of 800-1000 r / min, 3 parts of pure water and 3 parts of polyamide wax emulsion were added into the third reactor to obtain a polyamide wax mixed liquid;

[0152] Under stirring condition of 400-500 r / min, add the aqueous silver plating paste dilution in the first reactor and the polyamide wax mixed solution in the third reactor into the second reactor, and then add 42.4 parts of pure water to obtain.

[0153] Comparative Example 8

[0154] This comparative example provides a black coating formula with polyester resin, acrylic emulsion resin and amino resin as base resins, which is used to illustrate that polyamide wax emulsion can be directly added into the coating system without affecting the fineness and appearance.

[0155] The preparation of the polyamide wax emulsion is the same as in Example 1.

[0156] Under stirring conditions of 400-500 r / min, 40.7 parts of waterborne polyester resin, 0.5 parts of pH adjuster and 6.22 parts of pure water were added to the first reactor, and stirring was continued for 8-15 minutes;

[0157] Under stirring condition of 300-350r / min, 6.08 parts of amino resin, 14.66 parts of acrylic emulsion resin, 3.47 parts of auxiliary agent, 12.48 parts of solvent and 4 parts of polyamide wax emulsion were added into the first reactor in sequence, and then 11.89 parts of pure water were added to obtain the product.

[0158] Test 1

[0159] The water-based electroplating silver coatings prepared in Example 1, Example 2 and Comparative Example 1 were placed at room temperature for 5 days to observe their sedimentation state. Figure 1 .from Figure 1 It can be clearly observed that the coating with the addition of polyamide wax emulsion has excellent anti-settling effect, and the greater the amount of polyamide wax emulsion added, the better the anti-settling effect. After testing, the sample of Example 1 can be stably placed at room temperature for more than 3 days without precipitation, the sample of Example 2 can be stably placed at room temperature for more than 5 days without precipitation, while the sample of Comparative Example 1 was found to have obvious precipitation after only 1 day at room temperature.

[0160] Test 2

[0161] A matching mid-coat is selected for spraying on the substrate to obtain a mid-coat, wherein the mid-coat is an IPP water-based electroplated silver mid-coat (mixed with polyester, acrylic acid, and amino resin), with a viscosity of 17s (coating 4# cup, 23°C), a sprayed paint film thickness of 20μm, and a substrate size of 75mm*150mm*0.5mm.

[0162] Then, the water-based electroplated silver paint prepared in each embodiment or comparative example is continued to be sprayed on the formed paint film. The spraying stage is carried out by combining a rotary cup and an air gun. The specific process parameters are: the voltage of the rotary cup is 60KV; the paint spraying amount of the rotary cup is 130cc / min; the rotation speed of the rotary cup is 30000 rpm; the paint output of the air gun is 100cc / min; the atomization pressure is 0.5MPa, and the thickness of the formed paint film is 2-5μm.

[0163] The paint film prepared by using the paint of Comparative Example 1 was used as a control, and the spraying data of the paint films prepared by using the paint of Example 1 and Example 2 were compared. The results are shown in Table 3.

[0164] Table 3

[0165]

[0166] It can be seen from Table 3 that compared with Comparative Example 1, the addition of polyamide wax emulsion can enhance the aluminum powder silver row effect, showing a higher L value, brighter overall color, and stronger metallic luster.

[0167] Test Three

[0168] The performance tests were conducted on the water-based electroplated silver coatings prepared in Examples 1-3 and Comparative Examples 1-7:

[0169] (1) Prepare a 75*150*0.8 mm aluminum plate with a completely cured powder primer and a completely cured black midcoat, and wipe it clean;

[0170] (2) The prepared water-based electroplating silver paint was sprayed on the above-mentioned aluminum plate (Iwata 101 type spray gun, spraying pressure 0.4MPa, control dry film thickness 1-2μm), leveled for 8-10min, placed in a 140°C oven, and baked for 30min.

[0171] (3) Electrostatically spray 158C121 powder clear paint (control the dry film thickness to 80-100 μm), place in an oven at 180°C, and bake for 30 minutes.

[0172] The performance test method of water-based electroplated silver coating is shown in Table 4, and the test results are shown in Table 5.

[0173] Table 4

[0174]

[0175] Table 5

[0176]

[0177]

[0178] As can be seen from Table 5, adding water-based blocked isocyanate is very helpful for recoating adhesion. Different ways of adding polyamide wax emulsion have a great impact on the fineness of the finished coating. Poor fineness will cause spraying particles and affect the appearance of the paint film. Simply using polyester resin as the main resin will affect the hardness of the paint film, recoating adhesion and weather resistance. Simply using acrylic resin has good weather resistance, but poor recoating adhesion. Simply using polyurethane resin has poor weather resistance and metallic feel.

[0179] Comparative Example 8 is a polyester, acrylic amino paint, in which the polyamide wax emulsion can be directly added, the fineness can reach below 15 μm, and there will be no problems such as appearance particles. For the water-based electroplating silver system, the polyamide wax needs to be added according to a special process.

[0180] The water-based electroplating silver coatings for automobile wheels prepared in Examples 1-3 also have excellent pencil hardness, adhesion, CASS resistance, neutral salt spray resistance and other properties compared with ordinary water-based electroplating silver coatings, without causing any performance degradation. At the same time, the embodiments have good aluminum powder orientation, stronger recoating adhesion performance, higher metallic gloss and excellent anti-settling effect.

[0181] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A water-based electroplating silver coating for automobile wheels, characterized in that: The water-based electroplating silver coating comprises, by weight, 0.5-3 parts of water-based electroplating silver paste; 4-12 parts of acrylic acid modified polyurethane resin; 2-6 parts of acrylic emulsion; Amino resin 0.5-2 parts; 0.5-2 parts of water-based blocked isocyanate; 2-6 parts of directional anti-settling agent; 25-35 parts of cosolvent; 30-60 parts of water.

2. The water-based electroplating silver paint according to claim 1, characterized in that: The directional anti-settling agent is selected from one or more of ethylene-vinyl acetate copolymer wax emulsion, polyethylene wax emulsion and polyamide wax emulsion; preferably polyamide wax emulsion.

3. The water-based electroplating silver paint according to claim 1, characterized in that: The acrylic modified polyurethane resin is selected from one or more of Sanyo Chemical Ucoat ux-3945, Allnex Daotan TW 6431, Allnex NewHua-6928 and Allnex Daotan 7061; Preferably, the amino resin is selected from one or more of INEOS HM-2608, allnex CYMEL 303, allnex CYMEL 325 and Changchun Chemical M-40ST.

4. The water-based electroplating silver paint according to claim 1, characterized in that: The acrylic emulsion is selected from one or more of allnex SETAQUA6802, allnex SETAQUA6803, Jinhuili HD-MB019 and allnex SC6807.

5. The water-based electroplating silver paint according to claim 1, characterized in that: The water-based blocked isocyanate is selected from one or more of Zhide MR-850, Covestro Imprafix 2794 and Asahi Kasei WM44-L70G.

6. The water-based electroplating silver paint according to claim 1, characterized in that: The co-solvent is selected from one or more of methanol, ethanol, n-propanol, isopropanol, propylene alcohol, ethylene glycol, ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether and diethylene glycol butyl ether.

7. The water-based electroplating silver paint according to claim 1, characterized in that: The water-based electroplating silver paint further comprises 0.5-2 parts of a neutralizing agent; The neutralizing agent is selected from dimethylethanolamine and / or triethylamine.

8. A method for preparing a water-based electroplating silver coating as claimed in any one of claims 1 to 7, characterized in that: The steps include: (1) adding 0.5-3 parts of aqueous silver electroplating paste and 2-6 parts of co-solvent to the first reactor under stirring, and continuing stirring for 8-15 minutes to obtain an aqueous silver electroplating paste dilution; (2) adding 4-12 parts of acrylic modified polyurethane resin, 0.5-2 parts of amino resin, 2-6 parts of acrylic emulsion, remaining co-solvent and 0.5-2 parts of water-based blocked isocyanate to the second reactor under stirring, stirring for 20-40 minutes and filtering to obtain a resin mixture; (3) adding 2-6 parts of directional anti-settling agent, part of water and part of the resin mixed solution prepared in step (2) to the third reactor under stirring to prepare a directional anti-settling agent mixed solution; (4) under stirring conditions, adding the aqueous silver electroplating slurry dilution prepared in step (1), the directional anti-settling agent mixed solution prepared in step (3) and the remaining water into the second reactor to obtain.

9. The preparation method according to claim 8, characterized in that: When preparing the directional anti-settling agent mixed solution in step (3), the amount of water added is 0.5-1.5 parts by mass of water per 1 part by mass of the directional anti-settling agent; The amount of the resin mixture added is 0.5-1.5 parts by mass of the resin mixture per 1 part by mass of the directional anti-settling agent.

10. Use of the water-based electroplating silver paint according to any one of claims 1 to 7 in preparing paint for automobile wheels.

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