Wear-resistant vacuum coating layer and preparation process thereof
By preparing waterborne acrylate and waterborne polyurethane emulsions based on dehydro-divanillin and combining them with vacuum metallization process, an interpenetrating molecular network is formed, which solves the problem of insufficient adhesion of waterborne UV curing coatings and achieves a vacuum coating layer with high adhesion and wear resistance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DONGGUAN CHUNYANG VACUUM TECH CO LTD
- Filing Date
- 2026-04-10
- Publication Date
- 2026-06-19
AI Technical Summary
Existing water-based UV-curable vacuum coatings have insufficient adhesion to the substrate and metal coating, resulting in insufficient wear resistance and limiting their large-scale application.
Aqueous acrylate and waterborne polyurethane emulsions were prepared using dehydro-divanillin. By introducing vanillin-based structures, an interpenetrating molecular network was formed, which improved the adhesion and abrasion resistance of the coatings. Combined with vacuum metallization, an abrasion-resistant vacuum coating layer was formed.
It improves the adhesion between the coating and the substrate and the vacuum coating layer, enhances wear resistance, solves the problem of easy coating peeling in the prior art, and realizes a vacuum coating layer with high adhesion and wear resistance.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of coating technology, specifically to a wear-resistant vacuum coating layer and its preparation process. Background Technology
[0002] Vacuum coating is a coating system that integrates decoration and function. It usually consists of a primer, vacuum coating, and topcoat. The primer, also known as vacuum coating coating, is generally applied directly to the substrate and is the key to determining the adhesion and wear resistance of the coating.
[0003] Early vacuum coatings generally used thermosetting systems, which suffered from high curing temperatures, high energy consumption, and long curing times, and were prone to deformation and damage to heat-sensitive substrates. While subsequent UV curing technologies offered advantages such as rapid curing, low-temperature processing, and high hardness, traditional organic solvent-based UV coatings had high VOC emissions, posing environmental and safety risks. Therefore, developing environmentally friendly water-based UV-curable vacuum coatings has become an inevitable trend in the industry. However, existing water-based systems still face problems such as insufficient adhesion to the substrate and metal coating, and easy interface peeling during friction, leading to insufficient wear resistance, thus limiting their large-scale application.
[0004] In conclusion, solving the above problems and preparing a wear-resistant vacuum coating layer is of great significance. Summary of the Invention
[0005] The purpose of this invention is to provide a wear-resistant vacuum coating layer and its preparation process to solve the problems mentioned in the background art.
[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A process for preparing a wear-resistant vacuum coating layer includes the following steps: coating a vacuum coating material onto a substrate surface and curing it to form a primer; vacuum-plating aluminum onto the primer to obtain a wear-resistant vacuum coating layer. The vacuum coating material comprises the following raw materials, by weight: 60-70 parts of waterborne acrylic emulsion, 40-45 parts of waterborne polyurethane emulsion, 2-4 parts of photoinitiator, 0.3-0.5 parts of leveling agent, 0.1-0.3 parts of defoamer, 1-2 parts of film-forming agent, and 0.5-2 parts of adhesion promoter.
[0007] Preferably, the solid content of the aqueous acrylic emulsion is 35-40 wt%. The preparation method of the aqueous acrylate emulsion includes the following steps: vanillin monomer, acrylic acid, methyl methacrylate, hydroxyethyl methacrylate, butyl acrylate, and benzoyl peroxide are added to propylene glycol methyl ether and mixed evenly. The mixture is stirred and reacted at 120~125℃ for 2~2.5h, then cooled to 110~115℃. Glycidyl methacrylate and triphenylphosphine are added, and the mixture is stirred and reacted for another 1~2h. The mixture is then cooled to 50~60℃, neutralized with triethylamine, and emulsified with deionized water under high-speed stirring. The mixture is then filtered to obtain the aqueous acrylate emulsion.
[0008] Preferably, the aqueous acrylate emulsion comprises the following raw materials in parts by weight: 15-20 parts vanillin monomer, 6-10 parts acrylic acid, 5-10 parts methyl methacrylate, 10-14 parts hydroxyethyl methacrylate, 35-40 parts butyl acrylate, 1-2 parts benzoyl peroxide, 9-12 parts glycidyl methacrylate, and 0.1-0.2 parts triphenylphosphine.
[0009] Preferred method for preparing vanillin-based monomer includes the following steps: under a nitrogen atmosphere, dehydro-divanillin, glycidyl methacrylate, and 4-dimethylaminopyridine are added to N,N-dimethylformamide and mixed evenly. The mixture is stirred and reacted at 60-65°C for 4-6 hours. Ice water is added to precipitate the mixture, which is then washed and dried to obtain vanillin-based monomer.
[0010] Preferably, the raw materials for the vanillin monomer include dehydro-divanillin and glycidyl methacrylate in a mass ratio of 6:2.8~2.9; and the 4-dimethylaminopyridine accounts for 1.5~2wt% of the total reactants.
[0011] Preferably, the solid content of the waterborne polyurethane emulsion is 35-40 wt%. The preparation method of the waterborne polyurethane emulsion includes the following steps: (1) Methylated divanillin and 4,4-diaminodiphenylmethane are added to N,N-dimethylformamide and mixed evenly. The mixture is stirred and reacted at 65~70℃ for 6~8h. Ice water is added to precipitate the emulsion, and the mixture is filtered, washed, and dried to obtain vanillin-based chain extender. (2) Under a nitrogen atmosphere, isophorone diisocyanate was heated to 45-50°C, dibutyltin dilaurate was added, and castor oil was added dropwise. The temperature was raised to 65-70°C and the dropwise addition time was controlled to be 1.5h. The reaction was stirred for 30-40min. Acetone was added to reduce the viscosity. Vanillin chain extender was added and the reaction was stirred for 1.5-2h. The temperature was raised to 70-75°C, 2,2-dimethylolpropionic acid was added and the reaction was stirred for 1.5-2h. The temperature was lowered to 60-65°C, pentaerythritol triacrylate was added and the reaction was stirred for 2-3h. Triethylamine was added to adjust the pH to 7-8. Deionized water was added under high-speed stirring to emulsify. Small molecules were removed by rotary evaporation under reduced pressure to obtain an aqueous polyurethane emulsion.
[0012] Preferably, the raw materials for the vanillin-based chain extender include methylated divanillin and 4,4-diaminodiphenylmethane in a mass ratio of 1:1.2~1.3; the methylated divanillin is prepared by methylation of dehydro-divanillin with iodomethane. The aqueous polyurethane emulsion comprises the following raw materials, by mass parts: 50-60 parts isophorone diisocyanate, 0.1-0.2 parts dibutyltin dilaurate, 65-70 parts castor oil, 5-10 parts acetone, 6-8 parts vanillin-based chain extender, 13-15 parts 2,2-dimethylolpropionic acid, and 5-8 parts pentaerythritol triacrylate.
[0013] Preferably, the photoinitiator is Irgacure 2959; the film-forming agent includes dipropylene glycol methyl ether; and the adhesion promoter includes 3-(isobutenoyloxy)propyltrimethoxysilane.
[0014] Preferably, during the curing process, the material is first dried at 60-70°C for 5-10 minutes, and then cured at an energy level of 600-1200 mJ / cm². 2 UV curing for 8-15 minutes; The vacuum aluminum plating is vacuum magnetron sputtering aluminum plating, and the process is as follows: sputtering gas pressure is 0.01~0.1Pa, argon flow rate is 10~50sccm, power is 500~2000W, and time is 120~180 seconds.
[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention uses dehydro-divanillin as a bio-based raw material to sequentially prepare water-based acrylic emulsion and water-based polyurethane emulsion, which are used for vacuum coating to prepare primer. The coating has good adhesion to the substrate and the vacuum-coated metal layer, is not easy to fall off, and thus has excellent wear resistance.
[0016] The preparation method of the aqueous acrylic emulsion is as follows: the phenolic hydroxyl group of dehydro-divanillin reacts with the epoxy group of glycidyl methacrylate under the catalysis of 4-dimethylaminopyridine to obtain a vanillin-based monomer containing unsaturated bonds; further, benzoyl peroxide is used as an initiator to carry out free radical copolymerization of vanillin-based monomer, acrylic acid, methyl methacrylate, hydroxyethyl methacrylate and butyl acrylate as mixed monomers to form a basic copolymer; then, under the catalysis of triphenylphosphine, the epoxy group of glycidyl methacrylate reacts with the carboxyl group of the side chain of the basic copolymer to emulsify and obtain an aqueous acrylic emulsion.
[0017] The method for preparing the waterborne polyurethane emulsion is as follows: using potassium carbonate as an acid-binding agent, methyl iodide is used to methylate the phenolic hydroxyl groups in dehydro-divanillin to obtain methylated divanillin; further, two molecules of 4,4-diaminodiphenylmethane react with the aldehyde group of methylated divanillin to obtain a vanillin-based diamine chain extender containing a Schiff base structure; further, an isocyanate prepolymer is prepared using castor oil and isophorone diisocyanate, and the vanillin-based chain extender and 2,2-dimethylolpropionic acid are added sequentially for chain extension, and the emulsification is performed with pentaerythritol triacrylate to obtain the waterborne polyurethane emulsion.
[0018] Dehydro-divanillin, formed by the oxidative coupling of two molecules of bio-based vanillin, exhibits a biphenyl structure characterized by high rigidity and thermal stability. Its introduction into coatings effectively enhances the hardness and strength of the coating while maintaining dimensional stability during processing. However, dehydro-divanillin is highly hydrophobic and has poor film-forming properties, requiring its integration into aqueous polymer segments to maximize its effectiveness. This invention utilizes a coating primarily composed of aqueous acrylate and supplemented with aqueous polyurethane, introducing a similar vanillin-based structure into its molecular segments. This improves the compatibility of the two phases, effectively forming an interpenetrating molecular network. This enhances the coating's stability while simultaneously increasing its adhesion to the substrate and vacuum-deposited film, thereby improving wear resistance.
[0019] In the preparation of waterborne polyurethane, dehydro-divanillin requires methylation treatment because it has multiple crosslinking sites, which would lead to excessive crosslinking density in the waterborne polyurethane, reducing coating stability and adhesion. Furthermore, the ether bonds generated by methylation can provide abundant hydrogen bonding sites, increasing emulsion uniformity and improving coating strength. By further introducing 4,4-diaminodiphenylmethane, a vanillin-based diamine chain extender containing a Schiff base structure is prepared. Its Schiff base structure can undergo reversible hydrolysis upon heating, exhibiting a certain self-healing effect, enhancing its adhesion to the metal coating, and thus improving adhesion. In the preparation of waterborne acrylate, the retained phenolic hydroxyl groups can react with epoxy groups to introduce double bonds, thereby introducing vanillin groups into the waterborne acrylate molecular chain. Detailed Implementation
[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] It should be noted that the following quantities are by weight. There are no special restrictions on the manufacturers from which the raw materials involved in this invention can be purchased. Exemplary examples include: dehydro-divanillin (CAS No.: 2092-49-1); glycidyl methacrylate (CAS No.: 106-91-2); 4-dimethylaminopyridine (CAS No.: 1122-58-3); methyl methacrylate (CAS No.: 80-62-6); hydroxyethyl methacrylate (CAS No.: 868-77-9); butyl acrylate (CAS No.: 141-32-2); 4,4-diaminodiphenylmethane (CAS No.: 101-77-9); isophorone diisocyanate (CAS No.: 4098-71-9); castor oil (CAS No.: 8001-79-4); 2,2-dimethylolpropionic acid (CAS No.: 4767-03-7); pentaerythritol triacrylate (CAS No.: 3524-68-3).
[0022] In the following examples, parts refer to parts by weight, and all raw materials mentioned above and others not mentioned are commercially available.
[0023] In the following embodiments, the photoinitiator is Irgacure 2959; the leveling agent is AC-8333; the defoamer is VOK®-DF 50; the film-forming agent is dipropylene glycol methyl ether; and the adhesion promoter is 3-(isobutenoyloxy)propyltrimethoxysilane.
[0024] Among them, vacuum aluminizing is vacuum magnetron sputtering aluminizing, and the process is as follows: sputtering gas pressure is 0.1 Pa, argon flow rate is 40 sccm, power is 1500 W, and time is 150 seconds.
[0025] Pre-preparation: Preparation of methylated divanillin: Dehydro-divanillin was added to N,N-dimethylformamide and mixed evenly. Potassium carbonate was added, and iodomethane was added dropwise. The mixture was stirred at 80°C for 14 hours, precipitated with cold water, washed, and dried to obtain methylated divanillin. The raw materials for methylated divanillin included dehydro-divanillin, potassium carbonate, and iodomethane in a mass ratio of 1:1.92:2.77.
[0026] Example 1: A process for preparing a wear-resistant vacuum coating layer includes the following steps: Step 1: Preparation of aqueous acrylate emulsion: (1) Under a nitrogen atmosphere, dehydro-divanillin, glycidyl methacrylate, and 4-dimethylaminopyridine were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 60°C for 5 hours. Ice water was added to precipitate the mixture, which was then washed and dried to obtain vanillin-based monomers. The raw materials for the vanillin-based monomers included dehydro-divanillin and glycidyl methacrylate in a mass ratio of 6:2.85. The 4-dimethylaminopyridine accounted for 2 wt% of the total reactants. (2) 16 parts vanillin monomer, 8 parts acrylic acid, 8 parts methyl methacrylate, 12 parts hydroxyethyl methacrylate, 35 parts butyl acrylate, and 1.5 parts benzoyl peroxide were added to propylene glycol methyl ether and mixed evenly. The mixture was stirred at 120°C for 2 hours, then cooled to 110°C. 10 parts glycidyl methacrylate and 0.1 parts triphenylphosphine were added and stirred for another 1.5 hours. The mixture was then cooled to 55°C, neutralized with triethylamine, and emulsified with deionized water under high-speed stirring. The mixture was filtered and deionized water was added to bring the solid content to 40 wt% to obtain an aqueous acrylic emulsion. Step 2: Preparation of waterborne polyurethane emulsion: (1) Methylated divanillin and 4,4-diaminodiphenylmethane were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 65°C for 7 hours. Ice water was added to precipitate the emulsion. The emulsion was filtered, washed, and dried to obtain a vanillin-based chain extender. The raw materials for the vanillin-based chain extender included methylated divanillin and 4,4-diaminodiphenylmethane in a mass ratio of 1:1.25. (2) Under a nitrogen atmosphere, 55 parts of isophorone diisocyanate were heated to 45°C, 0.1 parts of dibutyltin dilaurate were added, and 66 parts of castor oil were added dropwise. The temperature was raised to 65°C and the dropwise addition time was controlled to be 1.5h. The reaction was stirred for 35min, 8 parts of acetone were added to reduce the viscosity, 7 parts of vanillin-based chain extender were added, and the reaction was stirred for 2h. The temperature was raised to 70°C, 14 parts of 2,2-dimethylolpropionic acid were added, and the reaction was stirred for 2h. The temperature was lowered to 60°C, 8 parts of pentaerythritol triacrylate were added, and the reaction was stirred for 2h. Triethylamine was added to adjust the pH to 7~8. Deionized water was added under high speed stirring to emulsify. Small molecules were removed by rotary evaporation under reduced pressure. Deionized water was added to make up to a solid content of 40wt% to obtain an aqueous polyurethane emulsion. Step 3: Preparation of the wear-resistant vacuum coating layer: S1: 65 parts of waterborne acrylic emulsion, 42 parts of waterborne polyurethane emulsion, 3 parts of photoinitiator, 0.4 parts of leveling agent, 0.2 parts of defoamer, 1.2 parts of film-forming agent, and 1 part of adhesion promoter are mixed at high speed and uniformly to obtain a vacuum coating. S2: Apply a vacuum coating to the substrate surface, dry it at 65℃ for 8 minutes, and then apply it at an energy of 1000mJ / cm². 2 The primer was cured under ultraviolet light for 12 minutes to obtain the primer. S3: Vacuum plating aluminum onto the primer to obtain a wear-resistant vacuum coating layer.
[0027] Example 2: A process for preparing a wear-resistant vacuum coating layer includes the following steps: Step 1: Preparation of aqueous acrylate emulsion: (1) Under a nitrogen atmosphere, dehydro-divanillin, glycidyl methacrylate, and 4-dimethylaminopyridine were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 60°C for 5 hours. Ice water was added to precipitate the mixture, which was then washed and dried to obtain vanillin-based monomers. The raw materials for the vanillin-based monomers included dehydro-divanillin and glycidyl methacrylate in a mass ratio of 6:2.85. The 4-dimethylaminopyridine accounted for 2 wt% of the total reactants. (2) 16 parts vanillin monomer, 8 parts acrylic acid, 8 parts methyl methacrylate, 12 parts hydroxyethyl methacrylate, 35 parts butyl acrylate, and 1.5 parts benzoyl peroxide were added to propylene glycol methyl ether and mixed evenly. The mixture was stirred at 120°C for 2 hours, then cooled to 110°C. 10 parts glycidyl methacrylate and 0.1 parts triphenylphosphine were added and stirred for another 1.5 hours. The mixture was then cooled to 55°C, neutralized with triethylamine, and emulsified with deionized water under high-speed stirring. The mixture was filtered and deionized water was added to bring the solid content to 40 wt% to obtain an aqueous acrylic emulsion. Step 2: Preparation of waterborne polyurethane emulsion: (1) Methylated divanillin and 4,4-diaminodiphenylmethane were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 65°C for 7 hours. Ice water was added to precipitate the emulsion. The emulsion was filtered, washed, and dried to obtain a vanillin-based chain extender. The raw materials for the vanillin-based chain extender included methylated divanillin and 4,4-diaminodiphenylmethane in a mass ratio of 1:1.25. (2) Under a nitrogen atmosphere, 55 parts of isophorone diisocyanate were heated to 45°C, 0.1 parts of dibutyltin dilaurate were added, and 66 parts of castor oil were added dropwise. The temperature was raised to 65°C and the dropwise addition time was controlled to be 1.5h. The reaction was stirred for 35min, 8 parts of acetone were added to reduce the viscosity, 7 parts of vanillin-based chain extender were added, and the reaction was stirred for 2h. The temperature was raised to 70°C, 14 parts of 2,2-dimethylolpropionic acid were added, and the reaction was stirred for 2h. The temperature was lowered to 60°C, 8 parts of pentaerythritol triacrylate were added, and the reaction was stirred for 2h. Triethylamine was added to adjust the pH to 7~8. Deionized water was added under high speed stirring to emulsify. Small molecules were removed by rotary evaporation under reduced pressure. Deionized water was added to make up to a solid content of 40wt% to obtain an aqueous polyurethane emulsion. Step 3: Preparation of the wear-resistant vacuum coating layer: S1: 60 parts of waterborne acrylic emulsion, 45 parts of waterborne polyurethane emulsion, 3 parts of photoinitiator, 0.4 parts of leveling agent, 0.2 parts of defoamer, 1.2 parts of film-forming agent, and 1 part of adhesion promoter are mixed at high speed and uniformly to obtain a vacuum coating. S2: Apply a vacuum coating to the substrate surface, dry it at 65℃ for 8 minutes, and then apply it at an energy of 1000mJ / cm². 2 The primer was cured under ultraviolet light for 12 minutes to obtain the primer. S3: Vacuum plating aluminum onto the primer to obtain a wear-resistant vacuum coating layer.
[0028] Example 3: A process for preparing a wear-resistant vacuum coating layer includes the following steps: Step 1: Preparation of aqueous acrylate emulsion: (1) Under a nitrogen atmosphere, dehydro-divanillin, glycidyl methacrylate, and 4-dimethylaminopyridine were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 60°C for 5 hours. Ice water was added to precipitate the mixture, which was then washed and dried to obtain vanillin-based monomers. The raw materials for the vanillin-based monomers included dehydro-divanillin and glycidyl methacrylate in a mass ratio of 6:2.85. The 4-dimethylaminopyridine accounted for 2 wt% of the total reactants. (2) 16 parts vanillin monomer, 8 parts acrylic acid, 8 parts methyl methacrylate, 12 parts hydroxyethyl methacrylate, 35 parts butyl acrylate, and 1.5 parts benzoyl peroxide were added to propylene glycol methyl ether and mixed evenly. The mixture was stirred at 120°C for 2 hours, then cooled to 110°C. 10 parts glycidyl methacrylate and 0.1 parts triphenylphosphine were added and stirred for another 1.5 hours. The mixture was then cooled to 55°C, neutralized with triethylamine, and emulsified with deionized water under high-speed stirring. The mixture was filtered and deionized water was added to bring the solid content to 40 wt% to obtain an aqueous acrylic emulsion. Step 2: Preparation of waterborne polyurethane emulsion: (1) Methylated divanillin and 4,4-diaminodiphenylmethane were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 65°C for 7 hours. Ice water was added to precipitate the emulsion. The emulsion was filtered, washed, and dried to obtain a vanillin-based chain extender. The raw materials for the vanillin-based chain extender included methylated divanillin and 4,4-diaminodiphenylmethane in a mass ratio of 1:1.25. (2) Under a nitrogen atmosphere, 55 parts of isophorone diisocyanate were heated to 45°C, 0.1 parts of dibutyltin dilaurate were added, and 66 parts of castor oil were added dropwise. The temperature was raised to 65°C and the dropwise addition time was controlled to be 1.5h. The reaction was stirred for 35min, 8 parts of acetone were added to reduce the viscosity, 7 parts of vanillin-based chain extender were added, and the reaction was stirred for 2h. The temperature was raised to 70°C, 14 parts of 2,2-dimethylolpropionic acid were added, and the reaction was stirred for 2h. The temperature was lowered to 60°C, 8 parts of pentaerythritol triacrylate were added, and the reaction was stirred for 2h. Triethylamine was added to adjust the pH to 7~8. Deionized water was added under high speed stirring to emulsify. Small molecules were removed by rotary evaporation under reduced pressure. Deionized water was added to make up to a solid content of 40wt% to obtain an aqueous polyurethane emulsion. Step 3: Preparation of the wear-resistant vacuum coating layer: S1: 70 parts of waterborne acrylic emulsion, 40 parts of waterborne polyurethane emulsion, 3 parts of photoinitiator, 0.4 parts of leveling agent, 0.2 parts of defoamer, 1.2 parts of film-forming agent, and 1 part of adhesion promoter are mixed at high speed and uniformly to obtain a vacuum coating. S2: Apply a vacuum coating to the substrate surface, dry it at 65℃ for 8 minutes, and then apply it at an energy of 1000mJ / cm². 2 The primer was cured under ultraviolet light for 12 minutes to obtain the primer. S3: Vacuum plating aluminum onto the primer to obtain a wear-resistant vacuum coating layer.
[0029] Comparative Example 1: Based on Example 1, the amount of waterborne polyurethane emulsion introduced was increased, while the rest of the process remained unchanged, as follows: Step 1: Preparation of aqueous acrylate emulsion: (1) Under a nitrogen atmosphere, dehydro-divanillin, glycidyl methacrylate, and 4-dimethylaminopyridine were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 60°C for 5 hours. Ice water was added to precipitate the mixture, which was then washed and dried to obtain vanillin-based monomers. The raw materials for the vanillin-based monomers included dehydro-divanillin and glycidyl methacrylate in a mass ratio of 6:2.85. The 4-dimethylaminopyridine accounted for 2 wt% of the total reactants. (2) 16 parts vanillin monomer, 8 parts acrylic acid, 8 parts methyl methacrylate, 12 parts hydroxyethyl methacrylate, 35 parts butyl acrylate, and 1.5 parts benzoyl peroxide were added to propylene glycol methyl ether and mixed evenly. The mixture was stirred at 120°C for 2 hours, then cooled to 110°C. 10 parts glycidyl methacrylate and 0.1 parts triphenylphosphine were added and stirred for another 1.5 hours. The mixture was then cooled to 55°C, neutralized with triethylamine, and emulsified with deionized water under high-speed stirring. The mixture was filtered and deionized water was added to bring the solid content to 40 wt% to obtain an aqueous acrylic emulsion. Step 2: Preparation of waterborne polyurethane emulsion: (1) Methylated divanillin and 4,4-diaminodiphenylmethane were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 65°C for 7 hours. Ice water was added to precipitate the emulsion. The emulsion was filtered, washed, and dried to obtain a vanillin-based chain extender. The raw materials for the vanillin-based chain extender included methylated divanillin and 4,4-diaminodiphenylmethane in a mass ratio of 1:1.25. (2) Under a nitrogen atmosphere, 55 parts of isophorone diisocyanate were heated to 45°C, 0.1 parts of dibutyltin dilaurate were added, and 66 parts of castor oil were added dropwise. The temperature was raised to 65°C and the dropwise addition time was controlled to be 1.5h. The reaction was stirred for 35min, 8 parts of acetone were added to reduce the viscosity, 7 parts of vanillin-based chain extender were added, and the reaction was stirred for 2h. The temperature was raised to 70°C, 14 parts of 2,2-dimethylolpropionic acid were added, and the reaction was stirred for 2h. The temperature was lowered to 60°C, 8 parts of pentaerythritol triacrylate were added, and the reaction was stirred for 2h. Triethylamine was added to adjust the pH to 7~8. Deionized water was added under high speed stirring to emulsify. Small molecules were removed by rotary evaporation under reduced pressure. Deionized water was added to make up to a solid content of 40wt% to obtain an aqueous polyurethane emulsion. Step 3: Preparation of the wear-resistant vacuum coating layer: S1: 42 parts of waterborne acrylic emulsion, 65 parts of waterborne polyurethane emulsion, 3 parts of photoinitiator, 0.4 parts of leveling agent, 0.2 parts of defoamer, 1.2 parts of film-forming agent, and 1 part of adhesion promoter are mixed at high speed and uniformly to obtain a vacuum coating. S2: Apply a vacuum coating to the substrate surface, dry it at 65℃ for 8 minutes, and then apply it at an energy of 1000mJ / cm². 2 The primer was cured under ultraviolet light for 12 minutes to obtain the primer. S3: Vacuum plating aluminum onto the primer to obtain a wear-resistant vacuum coating layer.
[0030] Comparative Example 2: Based on Example 1, the waterborne acrylate does not introduce vanillin monomers, and the remaining processes remain unchanged, as follows: Step 1: Preparation of waterborne acrylic emulsion: (1) Add 8 parts acrylic acid, 24 parts methyl methacrylate, 12 parts hydroxyethyl methacrylate, 35 parts butyl acrylate, and 1.5 parts benzoyl peroxide to propylene glycol methyl ether and mix evenly. Stir and react at 120°C for 2 hours. Cool down to 110°C, add 10 parts glycidyl methacrylate and 0.1 parts triphenylphosphine, continue stirring and reacting for 1.5 hours, cool down to 55°C, neutralize with triethylamine, and emulsify with deionized water under high-speed stirring. Filter and add deionized water to make up to a solid content of 40 wt% to obtain waterborne acrylic emulsion; Step 2: Preparation of waterborne polyurethane emulsion: (1) Methylated divanillin and 4,4-diaminodiphenylmethane were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 65°C for 7 hours. Ice water was added to precipitate the emulsion. The emulsion was filtered, washed, and dried to obtain a vanillin-based chain extender. The raw materials for the vanillin-based chain extender included methylated divanillin and 4,4-diaminodiphenylmethane in a mass ratio of 1:1.25. (2) Under a nitrogen atmosphere, 55 parts of isophorone diisocyanate were heated to 45°C, 0.1 parts of dibutyltin dilaurate were added, and 66 parts of castor oil were added dropwise. The temperature was raised to 65°C and the dropwise addition time was controlled to be 1.5h. The reaction was stirred for 35min, 8 parts of acetone were added to reduce the viscosity, 7 parts of vanillin-based chain extender were added, and the reaction was stirred for 2h. The temperature was raised to 70°C, 14 parts of 2,2-dimethylolpropionic acid were added, and the reaction was stirred for 2h. The temperature was lowered to 60°C, 8 parts of pentaerythritol triacrylate were added, and the reaction was stirred for 2h. Triethylamine was added to adjust the pH to 7~8. Deionized water was added under high speed stirring to emulsify. Small molecules were removed by rotary evaporation under reduced pressure. Deionized water was added to make up to a solid content of 40wt% to obtain an aqueous polyurethane emulsion. Step 3: Preparation of the wear-resistant vacuum coating layer: S1: 65 parts of waterborne acrylic emulsion, 42 parts of waterborne polyurethane emulsion, 3 parts of photoinitiator, 0.4 parts of leveling agent, 0.2 parts of defoamer, 1.2 parts of film-forming agent, and 1 part of adhesion promoter are mixed at high speed and uniformly to obtain a vacuum coating. S2: Apply a vacuum coating to the substrate surface, dry it at 65℃ for 8 minutes, and then apply it at an energy of 1000mJ / cm². 2 The primer was cured under ultraviolet light for 12 minutes to obtain the primer. S3: Vacuum plating aluminum onto the primer to obtain a wear-resistant vacuum coating layer.
[0031] Comparative Example 3: Based on Example 1, the waterborne polyurethane does not introduce vanillin-based chain extenders, and the remaining processes remain unchanged, as follows: Step 1: Preparation of aqueous acrylate emulsion: (1) Under a nitrogen atmosphere, dehydro-divanillin, glycidyl methacrylate, and 4-dimethylaminopyridine were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 60°C for 5 hours. Ice water was added to precipitate the mixture, which was then washed and dried to obtain vanillin-based monomers. The raw materials for the vanillin-based monomers included dehydro-divanillin and glycidyl methacrylate in a mass ratio of 6:2.85. The 4-dimethylaminopyridine accounted for 2 wt% of the total reactants. (2) 16 parts vanillin monomer, 8 parts acrylic acid, 8 parts methyl methacrylate, 12 parts hydroxyethyl methacrylate, 35 parts butyl acrylate, and 1.5 parts benzoyl peroxide were added to propylene glycol methyl ether and mixed evenly. The mixture was stirred at 120°C for 2 hours, then cooled to 110°C. 10 parts glycidyl methacrylate and 0.1 parts triphenylphosphine were added and stirred for another 1.5 hours. The mixture was then cooled to 55°C, neutralized with triethylamine, and emulsified with deionized water under high-speed stirring. The mixture was filtered and deionized water was added to bring the solid content to 40 wt% to obtain an aqueous acrylic emulsion. Step 2: Preparation of waterborne polyurethane emulsion: (1) Under a nitrogen atmosphere, 55 parts of isophorone diisocyanate were heated to 45°C, 0.1 parts of dibutyltin dilaurate were added, and 66 parts of castor oil were added dropwise. The temperature was raised to 65°C and the dropwise addition time was controlled to be 1.5h. The reaction was stirred for 35min, 8 parts of acetone were added to reduce the viscosity, 7 parts of 1,4-butanediol were added, and the reaction was stirred for 2h. The temperature was raised to 70°C, 14 parts of 2,2-dimethylolpropionic acid were added, and the reaction was stirred for 2h. The temperature was lowered to 60°C, 8 parts of pentaerythritol triacrylate were added, and the reaction was stirred for 2h. Triethylamine was added to adjust the pH to 7~8. Deionized water was added under high speed stirring to emulsify. Small molecules were removed by rotary evaporation under reduced pressure. Deionized water was added to make up to a solid content of 40wt% to obtain waterborne polyurethane emulsion. Step 3: Preparation of the wear-resistant vacuum coating layer: S1: 65 parts of waterborne acrylic emulsion, 42 parts of waterborne polyurethane emulsion, 3 parts of photoinitiator, 0.4 parts of leveling agent, 0.2 parts of defoamer, 1.2 parts of film-forming agent, and 1 part of adhesion promoter are mixed at high speed and uniformly to obtain a vacuum coating. S2: Apply a vacuum coating to the substrate surface, dry it at 65℃ for 8 minutes, and then apply it at an energy of 1000mJ / cm². 2 The primer was cured under ultraviolet light for 12 minutes to obtain the primer. S3: Vacuum plating aluminum onto the primer to obtain a wear-resistant vacuum coating layer.
[0032] Comparative Example 4: Based on Example 1, the dehydro-divanillin was not premethylated during the preparation of the vanillin-based chain extender, and the remaining processes remained unchanged, as follows: Step 1: Preparation of aqueous acrylate emulsion: (1) Under a nitrogen atmosphere, dehydro-divanillin, glycidyl methacrylate, and 4-dimethylaminopyridine were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 60°C for 5 hours. Ice water was added to precipitate the mixture, which was then washed and dried to obtain vanillin-based monomers. The raw materials for the vanillin-based monomers included dehydro-divanillin and glycidyl methacrylate in a mass ratio of 6:2.85. The 4-dimethylaminopyridine accounted for 2 wt% of the total reactants. (2) 16 parts vanillin monomer, 8 parts acrylic acid, 8 parts methyl methacrylate, 12 parts hydroxyethyl methacrylate, 35 parts butyl acrylate, and 1.5 parts benzoyl peroxide were added to propylene glycol methyl ether and mixed evenly. The mixture was stirred at 120°C for 2 hours, then cooled to 110°C. 10 parts glycidyl methacrylate and 0.1 parts triphenylphosphine were added and stirred for another 1.5 hours. The mixture was then cooled to 55°C, neutralized with triethylamine, and emulsified with deionized water under high-speed stirring. The mixture was filtered and deionized water was added to bring the solid content to 40 wt% to obtain an aqueous acrylic emulsion. Step 2: Preparation of waterborne polyurethane emulsion: (1) Dehydro-divanillin and 4,4-diaminodiphenylmethane were added to N,N-dimethylformamide and mixed evenly. The mixture was stirred at 65°C for 7 hours. Ice water was added to precipitate the emulsion. The emulsion was filtered, washed, and dried to obtain vanillin-based chain extender. The raw materials of vanillin-based chain extender included dehydro-divanillin and 4,4-diaminodiphenylmethane in a mass ratio of 0.9:1.25. (2) Under a nitrogen atmosphere, 55 parts of isophorone diisocyanate were heated to 45°C, 0.1 parts of dibutyltin dilaurate were added, and 66 parts of castor oil were added dropwise. The temperature was raised to 65°C and the dropwise addition time was controlled to be 1.5h. The reaction was stirred for 35min, 8 parts of acetone were added to reduce the viscosity, 7 parts of vanillin-based chain extender were added, and the reaction was stirred for 2h. The temperature was raised to 70°C, 14 parts of 2,2-dimethylolpropionic acid were added, and the reaction was stirred for 2h. The temperature was lowered to 60°C, 8 parts of pentaerythritol triacrylate were added, and the reaction was stirred for 2h. Triethylamine was added to adjust the pH to 7~8. Deionized water was added under high speed stirring to emulsify. Small molecules were removed by rotary evaporation under reduced pressure. Deionized water was added to make up to a solid content of 40wt% to obtain an aqueous polyurethane emulsion. Step 3: Preparation of the wear-resistant vacuum coating layer: S1: 65 parts of waterborne acrylic emulsion, 42 parts of waterborne polyurethane emulsion, 3 parts of photoinitiator, 0.4 parts of leveling agent, 0.2 parts of defoamer, 1.2 parts of film-forming agent, and 1 part of adhesion promoter are mixed at high speed and uniformly to obtain a vacuum coating. S2: Apply a vacuum coating to the substrate surface, dry it at 65℃ for 8 minutes, and then apply it at an energy of 1000mJ / cm². 2 The primer was cured under ultraviolet light for 12 minutes to obtain the primer. S3: Vacuum plating aluminum onto the primer to obtain a wear-resistant vacuum coating layer.
[0033] Performance testing: (1) The adhesion of each prepared primer to the PC substrate and the adhesion of the primer to the vacuum aluminum plating layer were measured according to GB / T 9286; (2) The pencil hardness of each prepared primer was measured according to GB / T 6739; (3) A coating was prepared on the surface of tinplate according to GB / T1733, and after sealing the edges, it was soaked in deionized water at 80℃ for 2h. The surface was observed to see if there were any phenomena such as loss of gloss, discoloration, wrinkling, bubbling, or peeling; (4) A primer was prepared on the PC substrate according to GB / T 1735, and vacuum aluminum plating was performed. The substrate was baked continuously at 120℃ for 2h, and the adhesion of the primer and the aluminum plating layer was measured again. The experimental data are shown in the table below.
[0034] Conclusions: As shown in the table, in Comparative Example 1, increasing the amount of waterborne polyurethane emulsion introduced reduced the adhesion of the coating and the aluminized layer. Furthermore, after heat treatment, the adhesion to the aluminized layer significantly decreased. This is because waterborne polyurethane contains a large number of unsaturated double bonds; exceeding a certain proportion leads to excessive cross-linking, resulting in high curing shrinkage stress, cracks between the coating and the aluminized layer, and decreased adhesion. In Comparative Examples 2 and 3, the absence of vanillin monomers in the waterborne acrylate and waterborne polyurethane resulted in a lack of the reinforcing effect of the rigid biphenyl structure of dehydro-divanillin, and reduced compatibility between the two phases, leading to decreased hardness, adhesion, and abrasion resistance of the primer. In Comparative Example 4, the lack of pre-methylation of dehydro-divanillin during the preparation of the vanillin chain extender significantly increased the cross-linking density of the waterborne polyurethane, decreased dispersion uniformity, and resulted in an uneven emulsion. Consequently, the prepared coating exhibited reduced water resistance and thermal stability.
[0035] In summary, this invention, based on dehydro-divanillin as a bio-based raw material, sequentially prepared aqueous acrylic emulsion and aqueous polyurethane emulsion, which were used in vacuum coating to prepare a primer. This coating exhibits good adhesion to the substrate and the vacuum-coated metal layer, is not easily detached, and thus possesses excellent wear resistance.
[0036] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A process for preparing a wear-resistant vacuum coating layer, characterized in that: Includes the following steps: A vacuum coating is applied to the substrate surface and cured to form a primer; aluminum is then vacuum-plated onto the primer to obtain a wear-resistant vacuum coating layer. The vacuum coating material comprises the following raw materials, by weight: 60-70 parts of waterborne acrylic emulsion, 40-45 parts of waterborne polyurethane emulsion, 2-4 parts of photoinitiator, 0.3-0.5 parts of leveling agent, 0.1-0.3 parts of defoamer, 1-2 parts of film-forming agent, and 0.5-2 parts of adhesion promoter.
2. The preparation process of a wear-resistant vacuum coating layer according to claim 1, characterized in that: The solid content of the aqueous acrylic emulsion is 35-40 wt%. The preparation method of the aqueous acrylate emulsion includes the following steps: vanillin monomer, acrylic acid, methyl methacrylate, hydroxyethyl methacrylate, butyl acrylate, and benzoyl peroxide are added to propylene glycol methyl ether and mixed evenly. The mixture is stirred and reacted at 120~125℃ for 2~2.5h, then cooled to 110~115℃. Glycidyl methacrylate and triphenylphosphine are added, and the mixture is stirred and reacted for another 1~2h. The mixture is then cooled to 50~60℃, neutralized with triethylamine, and emulsified with deionized water under high-speed stirring. The mixture is then filtered to obtain the aqueous acrylate emulsion.
3. The preparation process of a wear-resistant vacuum coating layer according to claim 1, characterized in that: The aqueous acrylate emulsion comprises the following raw materials, by mass parts: 15-20 parts vanillin monomer, 6-10 parts acrylic acid, 5-10 parts methyl methacrylate, 10-14 parts hydroxyethyl methacrylate, 35-40 parts butyl acrylate, 1-2 parts benzoyl peroxide, 9-12 parts glycidyl methacrylate, and 0.1-0.2 parts triphenylphosphine.
4. The preparation process of a wear-resistant vacuum coating layer according to claim 2, characterized in that: The preparation method of the vanillin-based monomer includes the following steps: under a nitrogen atmosphere, dehydro-divanillin, glycidyl methacrylate, and 4-dimethylaminopyridine are added to N,N-dimethylformamide and mixed evenly. The mixture is stirred and reacted at 60~65℃ for 4~6h. Ice water is added to precipitate the mixture, which is then washed and dried to obtain the vanillin-based monomer.
5. The preparation process of a wear-resistant vacuum coating layer according to claim 4, characterized in that: The raw materials for the vanillin monomer include dehydro-divanillin and glycidyl methacrylate in a mass ratio of 6:2.8~2.9; the 4-dimethylaminopyridine accounts for 1.5~2wt% of the total reactants.
6. The preparation process of a wear-resistant vacuum coating layer according to claim 1, characterized in that: The solid content of the waterborne polyurethane emulsion is 35-40 wt%. The preparation method of the waterborne polyurethane emulsion includes the following steps: (1) Methylated divanillin and 4,4-diaminodiphenylmethane are added to N,N-dimethylformamide and mixed evenly. The mixture is stirred and reacted at 65~70℃ for 6~8h. Ice water is added to precipitate the emulsion, and the mixture is filtered, washed, and dried to obtain vanillin-based chain extender. (2) Under a nitrogen atmosphere, isophorone diisocyanate was heated to 45-50°C, dibutyltin dilaurate was added, and castor oil was added dropwise. The temperature was raised to 65-70°C and the dropwise addition time was controlled to be 1.5h. The reaction was stirred for 30-40min. Acetone was added to reduce the viscosity. Vanillin chain extender was added and the reaction was stirred for 1.5-2h. The temperature was raised to 70-75°C, 2,2-dimethylolpropionic acid was added and the reaction was stirred for 1.5-2h. The temperature was lowered to 60-65°C, pentaerythritol triacrylate was added and the reaction was stirred for 2-3h. Triethylamine was added to adjust the pH to 7-8. Deionized water was added under high-speed stirring to emulsify. Small molecules were removed by rotary evaporation under reduced pressure to obtain an aqueous polyurethane emulsion.
7. The preparation process of a wear-resistant vacuum coating layer according to claim 6, characterized in that: The raw materials for the vanillin-based chain extender include methylated divanillin and 4,4-diaminodiphenylmethane in a mass ratio of 1:1.2~1.3; the methylated divanillin is prepared by methylation of dehydro-divanillin with iodomethane. The aqueous polyurethane emulsion comprises the following raw materials, by mass parts: 50-60 parts isophorone diisocyanate, 0.1-0.2 parts dibutyltin dilaurate, 65-70 parts castor oil, 5-10 parts acetone, 6-8 parts vanillin-based chain extender, 13-15 parts 2,2-dimethylolpropionic acid, and 5-8 parts pentaerythritol triacrylate.
8. The preparation process of a wear-resistant vacuum coating layer according to claim 1, characterized in that: The photoinitiator is Irgacure 2959; the film-forming agent includes dipropylene glycol methyl ether; and the adhesion promoter includes 3-(isobutenoyloxy)propyltrimethoxysilane.
9. The preparation process of a wear-resistant vacuum coating layer according to claim 1, characterized in that: During the curing process, the material is first dried at 60-70°C for 5-10 minutes, and then cured at an energy level of 600-1200 mJ / cm². 2 Cured under ultraviolet light for 8-15 minutes; The vacuum aluminum plating is vacuum magnetron sputtering aluminum plating, and the process is as follows: sputtering gas pressure is 0.01~0.1Pa, argon flow rate is 10~50sccm, power is 500~2000W, and time is 120~180 seconds.
10. The wear-resistant vacuum coating layer prepared by the process described in any one of claims 1 to 9.