A color-coated plate with a skin effect for a washing machine and a preparation method thereof

Abstract

The application belongs to the technical field of color-coated plates, and specifically discloses a color-coated plate with a washing machine skin effect for household appliances and a preparation method thereof. The color-coated plate with a washing machine skin effect for household appliances comprises a skin layer, a surface coating layer, a base material and a back coating layer, and the skin layer comprises the following raw materials in parts by weight: 35-40 parts of polyester resin, 15-20 parts of polyurethane resin, 3-6 parts of silicon dioxide, 3-5 parts of isocyanate curing agent, 7-9 parts of polymer microspheres and 50-55 parts of solvent. The color-coated plate has excellent adhesion, hardness, weather resistance and corrosion resistance, prevents the base material from being oxidized and corroded in the transportation, installation and use environment, and improves the overall service life and durability of the color-coated plate.

Description

Technical Field

[0001] This application relates to the technical field of color-coated steel sheets, and in particular to a color-coated steel sheet with a skin-feel effect for a washing machine used in household appliances and a method for preparing the same. Background Technology

[0002] Color-coated sheets for home appliances are products made from metal sheets, often cold-rolled steel or hot-dip galvanized steel. After surface pretreatment, one or more layers of organic coating are applied, followed by baking and curing. These are high-performance composite materials that require high processability, the ability to withstand complex bending and stamping, surface durability, corrosion resistance, and diverse appearances to enhance product value.

[0003] In the prior art, a PET-coated color-coated sheet includes a hot-dip galvanized substrate. A polyurethane primer layer and a PET film layer are sequentially disposed on the front side of the hot-dip galvanized substrate, and a pure epoxy back coating layer is disposed on the back side of the hot-dip galvanized substrate. The coated color-coated sheet of the present invention possesses excellent processing, salt spray resistance, and aging resistance, meeting the production requirements of household appliances such as refrigerators and washing machines.

[0004] However, although PET film has a certain degree of toughness, its surface hardness is usually not high. In the production, transportation and daily cleaning of home appliances, it is easily scratched by hard objects, leaving irreparable scratches, which in turn affects the appearance and lifespan of the product. Summary of the Invention

[0005] To address the issue of PET film being easily scratched by hard objects during the production, transportation, and daily cleaning of household appliances, this application provides a color-coated sheet with a skin-feel effect for washing machines used in household appliances and its preparation method.

[0006] This application provides a color-coated sheet with a skin-feel effect for a washing machine used in household appliances, adopting the following technical solution:

[0007] A color-coated sheet for a washing machine in household appliances with a skin-feel effect includes a skin-feel layer, a top coating layer, a substrate, and a back coating layer. The skin-feel layer, by weight, includes the following raw materials: 35-40 parts polyester resin, 15-20 parts polyurethane resin, 3-6 parts silica, 3-5 parts isocyanate curing agent, 7-9 parts polymer microspheres, and 50-55 parts solvent.

[0008] By adopting the above technical solution, the skin-feel layer, as the outermost functional layer of the coating system, provides the washing machine panel with a delicate, warm, and soft skin-friendly touch, possessing anti-fingerprint, scratch-resistant, and stain-resistant functions, enhancing the appearance and user experience of the appliance. The top coating improves the overall adhesion, hardness, weather resistance, and corrosion resistance of the coating, strengthens the bond strength between the skin-feel layer and the substrate, and ensures that the coating will not peel off or crack during long-term use. The substrate, as the main structural support of the color-coated sheet, provides the mechanical strength, rigidity, flatness, and processing performance required by the product, meeting the process requirements of stamping, bending, and forming of the washing machine shell, and ensuring the structural stability of the appliance. The back coating is rust-proof, corrosion-proof, and resistant to damp heat, preventing oxidation and rust on the substrate during transportation, installation, and use, and improving the overall service life and durability of the color-coated sheet.

[0009] In the skin-feel layer structure, polyester resin provides adhesion to the substrate, flexibility, and outdoor weather resistance, ensuring the overall film continuity and mechanical strength of the coating. Polyurethane resin provides a rubber-like elastic feel while enhancing the abrasion resistance and impact resistance of the coating film. In synergy with polyester resin, it improves the feel of the film and enhances the adhesion between the coating and the substrate. Isocyanate curing agent, acting as a crosslinking agent, reacts with the hydroxyl groups in polyester and polyurethane to form a three-dimensional network structure, improving the coating's hardness, solvent resistance, water resistance, and adhesion. Polymer microspheres form microscopic bumps on the coating surface, scattering light to achieve a soft matte effect, giving the coating a soft, delicate, skin-friendly, and warm feel, while further reducing gloss and enhancing the appearance. Silica reduces the surface gloss of the coating, creating a delicate matte effect; it also improves surface smoothness, scratch resistance, and fingerprint resistance. The combination of silica and polymer microspheres adjusts gloss and utilizes its high hardness to enhance the coating's scratch resistance, preventing scratches from being left on the washing machine during assembly or use. Solvents dissolve the resin system, adjust the system viscosity, and ensure good flowability, wettability and workability of the coating, resulting in a uniform and smooth film formation.

[0010] Preferably, the polymer microspheres are composed of a mixture of polystyrene microspheres, chitin, and composite graphene.

[0011] By employing the above technical solutions, polystyrene microspheres provide rigid support and uniform particle size, offering a uniformly sized template for subsequent functional layers (chitosan, graphene), ensuring controllability of the final coating thickness and roughness. Chitosan provides antibacterial properties, interface enhancement, and hydrophilicity regulation, coating the microsphere surface and enhancing the mechanical bonding between the microspheres and subsequent graphene layers, as well as with the external resin matrix (polyester / polyurethane). Composite graphene provides antistatic, barrier, and lubricating properties. It can form a conductive network on the coating surface, rapidly dissipating static charges generated by friction, preventing dust adsorption, and solving the problem of skin-feel coatings being easily soiled. Dense graphene sheets effectively block the penetration of water vapor, oxygen, and detergent molecules, improving the coating's corrosion resistance and yellowing resistance.

[0012] The rigid polystyrene core ensures the microspheres don't collapse, chitosan firmly fixes them within the resin matrix, and graphene provides an outer layer to protect against external scratches. Together, these three elements give the coating a soft feel while providing sufficient mechanical strength to withstand the demands of appliance manufacturing (stamping, bending) and everyday use (washing). Chitosan crystals are rich in hydroxyl and amino groups, while graphene contains oxygen-containing functional groups; both can form hydrogen bonds with polar groups in polyester / polyurethane resins, solving the problem of poor adhesion and easy detachment of ordinary polystyrene microspheres. Chitosan provides antibacterial and antifungal properties, while graphene provides antistatic and dust-resistant properties, collectively ensuring the long-lasting cleanliness of the skin-feel coating in complex usage environments.

[0013] Preferably, the chitosan is pretreated with water-based polyurethane.

[0014] By employing the above technical solution, a layer of aqueous polyurethane film is uniformly coated onto the surface of chitin. The chitin surface is rich in hydroxyl and acetylamino groups, and the aqueous polyurethane molecular chain contains urethane bonds, urea bonds, and hydrophilic segments of carboxyl / sulfonic acid groups. When dispersed in water, the polyurethane molecules are tightly adsorbed onto the whisker surface through hydrogen bonds and van der Waals forces. The adsorbed polyurethane particles fuse to form a film, tightly encapsulating the whiskers, thus forming a flexible yet strong film on the whisker surface. This film will serve as the basis for subsequent reactions.

[0015] Preferably, the composite graphene is composed of hydroxyapatite, graphene, and nano-aluminum sol.

[0016] By employing the above technical solutions, graphene serves as a conductive / thermal conductive network framework and a mechanically reinforcing core, ensuring that the coating surface resistance meets antistatic standards and improving corrosion resistance, scratch resistance, and impact resistance. Hydroxyapatite adsorbed on the graphene sheet surface acts like countless tiny support pillars, effectively preventing the graphene from recombining during drying and processing, thus ensuring its high specific surface area. The Ca²⁺ sites and abundant hydroxyl groups on the surface can both bind to the oxygen-containing functional groups of graphene and interact with subsequent nano-aluminum sols.

[0017] Nano-aluminum sol tightly locks hydroxyapatite and graphene inside, forming stable secondary aggregates. This achieves strong interfacial bonding between the inorganic filler and the organic matrix, significantly improving the scratch resistance and abrasion resistance of the coating surface. The three components work synergistically to ensure the coating's long-lasting cleanliness and durability under the complex operating conditions of washing machines, achieving antistatic, antibacterial, and abrasion-resistant properties.

[0018] Preferably, the topcoat comprises, by weight, the following raw materials: 60-65 parts acrylic resin, 30-35 parts ethylene-acrylic acid copolymer, 2-3 parts montmorillonite, 2-4 parts cellulose acetate butyrate, 1-2 parts defoamer, 4-5 parts curing agent, and 2-3 parts leveling agent.

[0019] By employing the above technical solutions, acrylic resin provides excellent weather resistance, gloss and color retention, and hardness. The ethylene-acrylic acid copolymer acts as a toughening agent and adhesion promoter; the ethylene segments provide flexibility and wettability to the inner lining substrate (metal), while the acrylic segments are compatible with the host resin. This copolymer significantly improves the brittleness of the acrylic resin, enhances the flexibility and processability of the coating (e.g., preventing cracking during bending and stamping), and simultaneously strengthens adhesion to the metal substrate.

[0020] Montmorillonite enhances the coating's hardness, abrasion resistance, and scratch resistance, effectively blocking the penetration of water vapor, oxygen, and detergent molecules, thus improving corrosion resistance. Cellulose acetate butyrate exhibits good compatibility with acrylic resin, controls rheology, and helps the coating spread evenly, achieving high smoothness. Defoamers prevent air bubbles from forming during roller coating or spraying; leveling agents ensure a smooth and even coating. Curing agents work in conjunction with ethylene-acrylic acid copolymers to regulate flexibility. Using high-hardness acrylic resin as the backbone, ethylene-acrylic acid copolymers as toughening agents, montmorillonite as a nano-reinforcing phase, and cellulose acetate butyrate as a flow control agent, a topcoat with combined hardness, flexibility, chemical resistance, and high appearance quality is constructed.

[0021] Preferably, the back coating comprises, by weight, the following raw materials: 20-25 parts epoxy resin, 1-2 parts nano silver, 10-12 parts polymethylphenylsiloxane, 4-6 parts calcium carbonate, and 1-2 parts leveling agent.

[0022] By employing the above technical solutions, epoxy resin, containing highly polar hydroxyl and epoxy groups, can form extremely strong hydrogen bonds and chemical bonds with the surface of metal substrates (iron, zinc), providing optimal substrate wetting and adhesion. Its cured network structure is dense and offers good barrier properties against water, oxygen, and ions. Polymethylphenylsiloxane possesses extremely high heat resistance and low surface energy, reducing the coefficient of friction and ensuring that the back coating does not stick to the top coating of the previous layer during winding and high-temperature stacking. Nano-silver has antibacterial and antifungal properties, effectively inhibiting mold growth and preventing the back coating from blackening and chalking. Calcium carbonate regulates the mechanical properties of the coating, preventing brittleness caused by excessive coating thickness or high cross-linking density. Leveling agents ensure uniform coverage of the back coating under high-speed roller coating, avoiding defects such as pinholes and orange peel.

[0023] Preferably, the substrate is an aluminized zinc plate.

[0024] By adopting the above technical solution, the substrate has excellent mechanical strength, rigidity and corrosion resistance, which can meet the processing requirements of washing machine shell stamping, bending and forming, etc. At the same time, it can effectively improve the overall rust prevention and weather resistance of the color-coated plate, adapt to the long-term use of home appliances, and provide a stable supporting base for the top coating and skin-feel layer.

[0025] Preferably, the thickness of the skin-feel layer is 15-20 μm, the thickness of the top coating layer is 10-12 μm, and the thickness of the back coating layer is 7-9 μm.

[0026] By adopting the above technical solution, the thickness of each coating of the color-coated plate for the washing machine of this household appliance is controlled as follows to balance the skin feel, mechanical performance and service life: the thickness of the skin feel layer is 15-20μm, the thickness of the top coating is 10-12μm, and the thickness of the back coating is 7-9μm.

[0027] The reasonable ratio of coating thicknesses ensures both the delicate touch and appearance of the skin-feel layer, while the top coating enhances adhesion and weather resistance. The back coating provides effective rust protection, and the coating is adapted to the support characteristics of the aluminized zinc substrate to meet the usage requirements of washing machines and other household appliances.

[0028] Secondly, this application also provides a method for preparing a color-coated sheet with a skin-feel effect for a washing machine used in household appliances, comprising the following steps:

[0029] (1) Preparation of skin-feel layer: Polyester resin, polyurethane resin, silica, isocyanate curing agent, polymer microspheres and solvent are mixed to obtain skin-feel layer mixture for later use;

[0030] (2) Preparation of topcoat: Mix acrylic resin, ethylene-acrylic acid copolymer, montmorillonite, cellulose acetate butyrate, defoamer, curing agent and leveling agent to obtain topcoat mixture for later use;

[0031] (3) Preparation of back coating: Epoxy resin, nano silver, polymethylphenylsiloxane, calcium carbonate and leveling agent are mixed to obtain a back coating mixture for later use;

[0032] (4) Preparation of color-coated sheet: Clean the substrate, apply a top coating mixture to one side of the substrate, dry it, then apply a skin-feel layer mixture, apply a back coating mixture to the other side of the substrate, dry and cure it to obtain a color-coated sheet with a skin-feel effect for washing machines for home appliances.

[0033] By adopting the above technical solution and preparation method, the operation is simple and helps to improve the mechanical properties, wear resistance and antibacterial properties of the color-coated sheet with skin-feel effect for home appliance washing machines. The obtained color-coated sheet with skin-feel effect for home appliance washing machines has good comprehensive properties such as durability.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. In this application, the skin-feel layer provides a delicate, warm, and soft skin-friendly touch to the washing machine panel, and has anti-fingerprint, scratch-resistant, and stain-resistant functions, enhancing the appearance and user experience of the appliance; the top coating improves the overall adhesion, hardness, and corrosion resistance of the coating, strengthens the bond strength between the skin-feel layer and the substrate, and ensures that the coating will not peel off or crack during long-term use; the back coating is rust-proof, corrosion-proof, and resistant to damp heat, preventing the substrate from oxidizing and rusting in the transportation, installation, and use environment, and improving the overall service life and durability of the color-coated sheet.

[0036] 2. In the skin-feel layer structure of this application, polyurethane resin can provide a rubber-like elastic touch, while enhancing the abrasion resistance and impact resistance of the coating film. When compounded with polyester resin, it synergistically improves the feel of the film layer and enhances the adhesion between the coating and the substrate.

[0037] 3. In this application, polymer microspheres form microscopic bumps and depressions on the coating surface, scattering light to achieve a soft matte effect, giving the coating a soft, delicate, skin-friendly, and warm touch; silica reduces the gloss of the coating surface, forming a delicate matte effect; at the same time, it improves the surface smoothness, scratch resistance, and anti-fingerprint performance; silica and polymer microspheres are used together to adjust the gloss, improve the scratch resistance of the coating, and prevent the washing machine from leaving scratches during assembly or use. Detailed Implementation

[0038] The present application will be further described in detail below with reference to the embodiments.

[0039] The raw materials used in the examples and comparative examples are all commercially available.

[0040] Preparation Example 1

[0041] The preparation of polymer microspheres includes:

[0042] 12 kg of polystyrene microspheres (particle size 1 μm, purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.) were dispersed in 25 L of 1.5% (w / w) aqueous solution of silane coupling agent KH550, filtered, and dried to obtain the treated product.

[0043] 3.5 kg of chitin (purchased from Hebei Rencan Biotechnology Co., Ltd.) was dispersed in 20 L of 3% acetic acid solution, the treated material was added, sonicated for 3 h, filtered, and dried to obtain composite microspheres;

[0044] 2 kg of composite graphene was dispersed in 100 L of anhydrous ethanol, 0.5 kg of BYK-190 was added, and the mixture was stirred evenly. The mixture was then sprayed onto the surface of the composite microspheres, ground, and dried to obtain polymer microspheres.

[0045] Preparation Example 2

[0046] The difference from Preparation Example 1 is that 12 kg of polystyrene microspheres were dispersed in 25 L of a 1.5% (w / w) aqueous solution of silane coupling agent KH550, sonicated for 3 h, filtered, and dried to obtain composite microspheres.

[0047] 2 kg of composite graphene was dispersed in 100 L of anhydrous ethanol, 0.5 kg of BYK-190 was added, and the mixture was stirred evenly. The mixture was then sprayed onto the surface of the composite microspheres, ground, and dried to obtain polymer microspheres.

[0048] Preparation Example 3

[0049] The difference from Preparation Example 1 is that 12 kg of polystyrene microspheres were dispersed in 25 L of a 1.5% (w / w) aqueous solution of silane coupling agent KH550, filtered, and dried to obtain the treated product;

[0050] 3.5 kg of chitin (purchased from Hebei Rencan Biotechnology Co., Ltd.) was dispersed in 20 L of 3% acetic acid solution, the treated material was added, sonicated for 3 h, filtered, and dried to obtain composite microspheres;

[0051] 100L of anhydrous ethanol was sprayed onto the surface of the composite microspheres, and then ground and dried to obtain polymer microspheres.

[0052] Preparation Example 4

[0053] Chitosan pretreatment:

[0054] 5 kg of chitin powder was dispersed in 22 L of deionized water, and 0.9 kg of waterborne polyurethane (purchased from Guangdong Shuanghong Waterproof and Thermal Insulation Engineering Co., Ltd.) was added. The mixture was filtered, dried, and then dispersed in 20 L of 3% sodium hydroxide solution. The mixture was soaked for 3 hours, washed with water, and dried to obtain pretreated chitin.

[0055] Preparation Example 5

[0056] The difference from Preparation Example 4 is that 5 kg of chitin powder was dispersed in 22 L of deionized water, filtered, dried, and then dispersed in 20 L of 3% sodium hydroxide solution, soaked for 3 h, washed with water, and dried to obtain pretreated chitin.

[0057] Preparation Example 6

[0058] The difference from Preparation Example 4 is that 5 kg of chitin powder was dispersed in 22 L of deionized water, 0.9 kg of aqueous polyurethane was added, filtered, and dried to obtain pretreated chitin.

[0059] Preparation Example 7

[0060] The preparation of composite graphene includes the following:

[0061] 1 kg of hydroxyapatite (purchased from Beijing Deco Island Technology Co., Ltd.) was dispersed in 50 L of deionized water, 3 kg of graphene was added, stirred evenly, dried, ground, and mixed with 0.5 kg of nano aluminum sol (purchased from Beijing Deco Island Technology Co., Ltd.), stirred, dried, and ground to obtain composite graphene.

[0062] Preparation Example 8

[0063] The difference from Preparation Example 7 is that 3 kg of graphene was dispersed in 50 L of deionized water, stirred evenly, dried, ground, mixed with 0.5 kg of nano-aluminum sol, stirred, dried, and ground to obtain composite graphene.

[0064] Preparation Example 9

[0065] The difference from Preparation Example 7 is that 1 kg of hydroxyapatite was dispersed in 50 L of deionized water, 3 kg of graphene was added, stirred evenly, dried, and ground to obtain composite graphene.

[0066] Example 1

[0067] A color-coated sheet for a washing machine with a skin-feel effect includes a skin-feel layer, a top coating, a substrate, and a back coating. The skin-feel layer, by weight, includes the following raw materials: 40 kg of polyester resin (vinyl polyester resin, purchased from Langfang Fuchen New Material Co., Ltd.), 20 kg of polyurethane resin (PU8107, purchased from Guangzhou Qiyuan New Material Co., Ltd.), 3 kg of silica, 3 kg of isocyanate curing agent (purchased from Shaoguan Dongsen Synthetic Material Co., Ltd.), 7 kg of polymer microspheres, and 55 kg of solvent (ethyl acetate).

[0068] The topcoat, by weight, comprises the following raw materials: 65 kg of acrylic resin (purchased from Hebei Ruihan Anticorrosion Materials Co., Ltd.), 35 kg of ethylene-acrylic acid copolymer (purchased from Dongguan Xinshengli Plastic New Materials Technology Co., Ltd.), 3 kg of montmorillonite, 4 kg of cellulose acetate butyrate, 1 kg of defoamer (polydimethylsiloxane), 5 kg of curing agent (fatty amine), and 3 kg of leveling agent (acrylic resin polymer).

[0069] The back coating, by weight, comprises the following raw materials: 25 kg of epoxy resin (purchased from Langfang Tongsheng Anticorrosion Equipment Co., Ltd.), 2 kg of nano silver, 12 kg of polymethylphenylsiloxane, 6 kg of calcium carbonate, and 2 kg of leveling agent (acrylic resin polymer).

[0070] The substrate is aluminum-zinc coated steel sheet.

[0071] The skin-feel layer is 20 μm thick, the top coating layer is 10 μm thick, and the back coating layer is 9 μm thick.

[0072] A method for preparing a color-coated steel sheet with a skin-feel effect for a household appliance washing machine includes the following steps:

[0073] (1) Preparation of skin-feel layer: Polyester resin, polyurethane resin, silica, isocyanate curing agent, polymer microspheres and solvent are mixed to obtain skin-feel layer mixture for later use;

[0074] (2) Preparation of topcoat: Mix acrylic resin, ethylene-acrylic acid copolymer, montmorillonite, cellulose acetate butyrate, defoamer, curing agent and leveling agent to obtain topcoat mixture for later use;

[0075] (3) Preparation of back coating: Epoxy resin, nano silver, polymethylphenylsiloxane, calcium carbonate and leveling agent are mixed to obtain a back coating mixture for later use;

[0076] (4) Preparation of color-coated sheet: Clean the substrate, apply a top coating mixture to one side of the substrate, dry it, then apply a skin-feel layer mixture, apply a back coating mixture to the other side of the substrate, dry it, and cure it (curing at 140℃ for 30s) to obtain a color-coated sheet with a skin-feel effect for washing machines for household appliances.

[0077] The polymer microspheres were prepared in Preparation Example 1, the chitin was prepared in Preparation Example 4, and the composite graphene was prepared in Preparation Example 7.

[0078] Example 2

[0079] A color-coated sheet with a skin-feel effect for a washing machine for home appliances, which differs from Example 1 in that the skin-feel layer, by weight, includes the following raw materials: 35 kg of polyester resin, 15 kg of polyurethane resin, 6 kg of silica, 5 kg of isocyanate curing agent, 9 kg of polymer microspheres, and 50 kg of solvent (ethyl acetate).

[0080] The topcoat, by weight, comprises the following raw materials: 60 kg of acrylic resin, 30 kg of ethylene-acrylic acid copolymer, 2 kg of montmorillonite, 2 kg of cellulose acetate butyrate, 2 kg of defoamer, 4 kg of curing agent, and 2 kg of leveling agent.

[0081] The back coating, by weight, comprises the following raw materials: 20 kg epoxy resin, 1 kg nano silver, 10 kg polymethylphenylsiloxane, 4 kg calcium carbonate, and 1 kg leveling agent.

[0082] The thickness of the skin-feel layer is 15μm, the thickness of the top coating layer is 12μm, and the thickness of the back coating layer is 7μm.

[0083] Example 3

[0084] A color-coated sheet with a skin-feel effect for a washing machine for home appliances differs from Example 1 in that the polymer microspheres are prepared using Preparation Example 2.

[0085] Example 4

[0086] A color-coated sheet with a skin-feel effect for a washing machine for home appliances differs from Example 1 in that the polymer microspheres are prepared using Preparation Example 3.

[0087] Example 5

[0088] A color-coated sheet with a skin-feel effect for a washing machine for home appliances differs from Example 1 in that the chitosan is prepared using Preparation Example 5.

[0089] Example 6

[0090] A color-coated sheet with a skin-feel effect for a washing machine for home appliances differs from Example 1 in that the chitosan is prepared using Preparation Example 6.

[0091] Example 7

[0092] A color-coated sheet with a skin-feel effect for a washing machine for home appliances, which differs from Example 1 in that the composite graphene is prepared using Preparation Example 8.

[0093] Example 8

[0094] A color-coated sheet with a skin-feel effect for a washing machine for home appliances, which differs from Example 1 in that the composite graphene is prepared using Preparation Example 9.

[0095] Comparative Example 1

[0096] A color-coated sheet with a skin-feel effect for a washing machine used in household appliances differs from Example 1 in that it does not contain polymer microspheres.

[0097] Performance testing

[0098] The performance of a color-coated sheet with a skin-feel effect for a household appliance washing machine prepared in Examples 1-8 and Comparative Example 1 was tested.

[0099] Abrasion resistance test: According to the national standard GB1768-(79)88 Test method for abrasion resistance of paint film, the JM-1 type paint film abrasion tester is used. After the number of abrasion cycles, the abrasion resistance is expressed by the weight loss of the paint film.

[0100] Salt spray resistance test: The test was conducted in accordance with GB / T 1771—2007 "Determination of resistance to neutral salt spray of paints and varnishes";

[0101] Scratch resistance test: The scratch resistance of the product was tested according to GB / T 13448-2019 "Test Methods for Color Coated Steel Sheets and Strips"; the test results are shown in Table 1.

[0102] Table 1 Test data for the examples and comparative examples

[0103] Wear rate / % Salt spray tolerance time / h Scratch resistance / kgf Example 1 0.124 1350 5.3 Example 2 0.128 1345 5.1 Example 3 0.158 1325 4.6 Example 4 0.178 1302 4.0 Example 5 0.151 1330 4.7 Example 6 0.139 1337 4.9 Example 7 0.170 1311 4.3 Example 8 0.155 1328 4.6 Comparative Example 1 0.196 1280 3.5

[0104] As shown in Table 1, the color-coated steel sheet with a skin-feel effect for a washing machine prepared in Examples 1-2 of this application has good wear resistance, aging resistance, and durability. Among them, the wear rate of Example 1 is 0.124%, the salt spray resistance time is 1350h, and the scratch resistance is 5.3kgf. It can be seen that the color-coated steel sheet with a skin-feel effect for a washing machine prepared in this application has good comprehensive performance. The color-coated steel sheet is not easily oxidized or corroded in the transportation, installation, and use environment, which improves the overall service life and durability of the color-coated steel sheet. The various raw material components in the skin-feel layer, the top coating layer, and the back coating layer work together to improve the overall adhesion, hardness, weather resistance, and corrosion resistance of the coating, ensuring that the coating will not peel off or crack after long-term use.

[0105] In the preparation of polymer microspheres in Examples 3-4, neither chitin nor composite graphene was added. As shown in Table 1, the wear rate, salt spray resistance, and scratch resistance of Examples 3-4 were significantly worse than those of Examples 1-2. This indicates that chitin is rich in hydroxyl and amino groups, and graphene contains oxygen functional groups. Both form hydrogen bonds with the polar groups in the polyester / polyurethane resin, solving the problem of poor bonding force and easy detachment of ordinary polystyrene microspheres with the resin. Chitin firmly fixes the microspheres in the resin matrix, while graphene resists external scratches on the outer layer, exhibiting good mechanical properties. The combined effect of these three components allows the coating to maintain a soft touch while possessing sufficient mechanical strength to withstand the manufacturing of household appliances and daily use.

[0106] In Examples 5-6, no aqueous polyurethane or sodium hydroxide solution was added during the preparation of chitin. As shown in Table 1, the wear rate, salt spray resistance, and scratch resistance of Examples 5-6 were significantly worse than those of Examples 1-2. This indicates that uniformly coating the chitin surface with an aqueous polyurethane film allows polyurethane molecules to be tightly adsorbed onto the whisker surface through hydrogen bonds and van der Waals forces. The adsorbed polyurethane particles fuse into a film, tightly encapsulating the whiskers and forming a flexible yet strong film on the whisker surface, resulting in better overall performance. The sodium hydroxide solution has a certain degree of abrasion on the chitin surface, making it uneven and increasing the specific surface area of ​​the chitin surface. This facilitates subsequent bonding with composite graphene and polystyrene microspheres, thereby improving the overall performance of the polymer microspheres and ultimately enhancing the durability, wear resistance, and scratch resistance of the color-coated sheet.

[0107] In the preparation of composite graphene in Examples 7-8, neither hydroxyapatite nor nano-aluminum sol was added. As shown in Table 1, the wear rate, salt spray resistance, and scratch resistance of Examples 7-8 were significantly worse than those of Examples 1-2. This indicates that hydroxyapatite adsorbs on the surface of the graphene sheets, effectively preventing the graphene from recombinizing during drying and processing, ensuring its high specific surface area, and enabling it to interact with the subsequent nano-aluminum sol. The nano-aluminum sol firmly locks hydroxyapatite and graphene inside, forming stable secondary aggregates, achieving strong interfacial bonding between the inorganic filler and the organic matrix, significantly improving the scratch resistance and wear resistance of the coating surface. The three components work synergistically to ensure the long-term cleanliness and durability of the coating under the complex operating conditions of the washing machine, achieving durability, antibacterial properties, and wear resistance.

[0108] Comparative Example 1, which did not include polymer microspheres in its skin-feel layer, showed in Table 1 that its wear rate was 0.196%, salt spray resistance time was 1280 hours, and scratch resistance was 3.5 kgf. The wear rate, salt spray resistance, and scratch resistance of Comparative Example 1 were significantly worse than those of Examples 1-2, indicating that the polymer microspheres formed microscopic irregularities on the coating surface, scattering light to achieve a soft matte effect, giving the coating a soft, delicate, skin-friendly, and warm feel. Simultaneously, it further reduced gloss and improved the appearance and texture. Subsequent application of silica further enhances the gloss and scratch resistance of the color-coated sheet, improving the durability of the washing machine.

[0109] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A color-coated sheet with a skin-feel effect for a washing machine used in household appliances, characterized in that, It includes a skin-feel layer, a top coating, a substrate, and a back coating. The skin-feel layer, by weight, includes the following raw materials: 35-40 parts polyester resin, 15-20 parts polyurethane resin, 3-6 parts silica, 3-5 parts isocyanate curing agent, 7-9 parts polymer microspheres, and 50-55 parts solvent.

2. The color-coated sheet for a skin-feel effect in a washing machine for household appliances according to claim 1, characterized in that, The polymer microspheres are composed of polystyrene microspheres, chitin, and composite graphene.

3. The color-coated sheet for a skin-feel effect in a washing machine for household appliances according to claim 2, characterized in that, The chitin is obtained by pretreatment with water-based polyurethane.

4. The color-coated sheet for a skin-feel effect in a washing machine for household appliances according to claim 2, characterized in that, The composite graphene is composed of hydroxyapatite, graphene, and nano-aluminum sol.

5. The color-coated sheet for a skin-feel effect in a washing machine for household appliances according to claim 1, characterized in that, The topcoat, by weight, comprises the following raw materials: 60-65 parts acrylic resin, 30-35 parts ethylene-acrylic acid copolymer, 2-3 parts montmorillonite, 2-4 parts cellulose acetate butyrate, 1-2 parts defoamer, 4-5 parts curing agent, and 2-3 parts leveling agent.

6. The color-coated sheet for a skin-feel effect in a washing machine for household appliances according to claim 1, characterized in that, The back coating layer comprises, by weight, the following raw materials: 20-25 parts epoxy resin, 1-2 parts nano silver, 10-12 parts polymethylphenylsiloxane, 4-6 parts calcium carbonate, and 1-2 parts leveling agent.

7. The color-coated sheet for a skin-feel effect in a washing machine for household appliances according to claim 1, characterized in that, The substrate is an aluminized zinc plate.

8. The color-coated sheet for a skin-feel effect in a washing machine for household appliances according to claim 1, characterized in that, The thickness of the skin-feel layer is 15-20 μm, the thickness of the top coating layer is 10-12 μm, and the thickness of the back coating layer is 7-9 μm.

9. The method for preparing a color-coated sheet with a skin-feel effect for a washing machine in household appliances according to claim 1, characterized in that, Includes the following steps: (1) Preparation of skin-feel layer: Polyester resin, polyurethane resin, silica, isocyanate curing agent, polymer microspheres and solvent are mixed to obtain skin-feel layer mixture for later use; (2) Preparation of topcoat: Mix acrylic resin, ethylene-acrylic acid copolymer, montmorillonite, cellulose acetate butyrate, defoamer, curing agent and leveling agent to obtain topcoat mixture for later use; (3) Preparation of back coating: Epoxy resin, nano silver, polymethylphenylsiloxane, calcium carbonate and leveling agent are mixed to obtain a back coating mixture for later use; (4) Preparation of color-coated sheet: Clean the substrate, apply a top coating mixture to one side of the substrate, dry it, then apply a skin-feel layer mixture, apply a back coating mixture to the other side of the substrate, dry and cure it to obtain a color-coated sheet with a skin-feel effect for washing machines for home appliances.