A coating and its preparation method and application

Abstract

This invention provides a coating, its preparation method, and its application. The coating of this invention is prepared from raw materials comprising component A, component B, and component C. Component A includes epoxy-modified acrylic resin, polyurethane resin, black paste, defoamer, substrate wetting agent, solvent A, solvent B, organotin drier, dispersant, abrasion-resistant agent, matting agent, thickener, water, and pH adjuster. Component B includes isocyanate, and component C includes water. The coating of this invention achieves an extremely low L value, provides higher blackness and optical properties, and exhibits good scratch resistance and abrasion resistance. This invention also provides a method for preparing the coating and its application.

Description

Technical Field

[0001] This invention belongs to the field of matte coating technology, specifically relating to a coating, its preparation method, and its application. Background Technology

[0002] In the relevant technical field, the L-value of traditional matte coatings is typically around 24, a value representing the intensity of light reflected by the coating. The lower the L-value, the higher the blackness of the coating and the less light it reflects, thus making the coating surface appear deeper. However, although some ultra-matte coatings can achieve even lower L-values, even below 21, to achieve a deeper blackness effect, these coatings exhibit significant shortcomings in other aspects.

[0003] Achieving an ultra-matte finish typically requires a large amount of matting powder, which is used to reduce the gloss of the coating and enhance its matte effect. However, excessive matting powder can cause these particles to accumulate on the surface of the paint film, negatively impacting the physical properties of the coating. Specifically, excessive accumulation of these matting powders significantly reduces the coating's scratch resistance. Scratch resistance is a crucial indicator of paint durability, especially in applications where maintaining the coating's appearance for an extended period is crucial. Furthermore, the coating's abrasion resistance is also affected; ultra-matte coatings are more prone to scratches or abrasions, making them more susceptible to damage during use, particularly in environments requiring high durability. This damage not only affects the coating's aesthetics but can also lead to substrate exposure, compromising the overall protective effect of the coating.

[0004] Currently, there are almost no coatings on the market that simultaneously meet the requirements of high blackness and excellent scratch resistance. This is especially true in the field of optical equipment, where the blackness requirements for coatings are even higher. In optical equipment, coatings with high L-values ​​can cause stray scattering of light, thus affecting the imaging quality of the equipment. High-blackness coatings can effectively suppress stray scattering of light, improve the imaging performance of optical components, and make the equipment perform better in high-precision applications. Therefore, in these application areas, the requirements for coatings are not only their matte appearance, but more importantly, the blackness of the coating must achieve optimal optical performance. Furthermore, most existing ultra-matte coatings use solvent-based systems, meaning they contain high levels of volatile organic compounds (VOCs). These VOCs are released into the air during the production and use of the coatings, adversely affecting the environment. VOCs not only pose potential hazards to human health but also contribute to air pollution, exacerbating environmental problems. Therefore, there is an urgent need in the market for an environmentally friendly and high-performance coating to meet the dual requirements of modern industry and environmental protection. To overcome these challenges, a new type of coating needs to be developed. This coating not only achieves extremely low L-values, thus providing higher blackness and optical performance, but also needs to possess excellent scratch and abrasion resistance. Simultaneously, the coating formulation should minimize the content of volatile organic compounds (VOCs) to reduce negative environmental impact. Such a coating will be able to meet the demands of demanding optical applications, providing long-lasting durability while complying with environmental standards. This will not only enhance the market competitiveness of coatings but also, against the backdrop of continuous scientific and technological advancements, bring more efficient and environmentally friendly solutions to related industries. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a coating that achieves an extremely low L value, provides higher blackness and optical properties, and possesses good scratch resistance and abrasion resistance.

[0006] The present invention also provides a method for preparing a coating.

[0007] The present invention also provides the application of coatings in optical components.

[0008] A first aspect of the present invention provides a coating, the raw materials for which are prepared include component A, component B and component C, wherein, by mass parts, component A comprises:

[0009] Epoxy-modified acrylic resin: 30-40 parts,

[0010] Polyurethane resin: 10-20 parts

[0011] Black paste: 10-15 parts,

[0012] Defoamer: 0.2-0.3 parts

[0013] Substrate wetting agent: 0.5-1.0 parts,

[0014] Solvent A: 3.0-5.0 parts,

[0015] Solvent B: 3.0-5.0 parts,

[0016] Organotin drying agent: 0.1-0.2 parts,

[0017] Dispersant: 3.0-4.0 parts,

[0018] Wear-resistant additive: 3-5 parts

[0019] Matte powder: 4-6 parts

[0020] Tackifier: 0.2-0.3 parts,

[0021] Water: 10-30 parts

[0022] pH adjuster: 0.1-0.2 parts;

[0023] Component B includes isocyanate;

[0024] Component C includes water.

[0025] One of the technical solutions of the present invention concerning coatings has at least the following beneficial effects:

[0026] This invention uses an aqueous system, which can achieve good scratch resistance (almost no mark residue on the skin) at an L value of around 17, while also satisfying good adhesion and chemical resistance.

[0027] This invention employs a water-based PU system, which has stricter VOC requirements and a smaller range of raw material options compared to solvent-based products. In the coatings of this invention, inorganic matting agents have higher matting efficiency than organic ones due to their larger oil absorption and specific surface area. However, inorganic matting agents have lower strength and abrasion resistance than organic ones. Achieving an ultra-matte finish with organic matting agents is difficult, resulting in insufficient blackness. The key issue is how to achieve an ultra-matte finish while maintaining scratch resistance and abrasion resistance using inorganic matting agents. The resin B used in this invention has strong powder encapsulation properties and is itself a matte resin, further reducing the amount of matting agent in the formulation. This reduces the amount of matting agent that floats to the paint film surface during drying, thus improving scratch resistance. Furthermore, the resin in this invention contains benzene rings or carbonate bonds, both of which are structurally stable groups that can improve the rigidity of the paint film, thereby improving abrasion resistance and solving the aforementioned problems. By using precisely proportioned matte powder and thickener, this invention achieves a near-ultra-matte finish while maintaining high blackness, effectively suppressing stray light scattering and improving optical performance.

[0028] The coating of this invention has excellent adhesion to a variety of complex substrates, good chemical and weather resistance, and can be adapted to optical devices made of different types of materials.

[0029] The water-based system and optimized formulation simplify the coating preparation process, reducing production complexity and costs, while also making the coating easier to handle and control during application. Excellent adhesion to a variety of substrates makes this coating suitable for a wide range of applications, including different types of optical equipment, ensuring its reliability and durability. Improved chemical and weather resistance allows the coating to maintain stability under various environmental conditions, extending its service life.

[0030] According to some embodiments of the present invention, the epoxy-modified acrylic resin includes DIC's WLW-270.

[0031] The epoxy-modified acrylic resin used in this invention exhibits excellent chemical resistance, hardness, and adhesion on many substrates, and its internal hydroxyl groups react with isocyanates to form crosslinks. According to some embodiments of the invention, the polyurethane resin includes Covestro's... U 2757.

[0032] The polyurethane resin used in this invention has good elasticity, self-healing ability, good chemical resistance and scratch resistance, and is also a self-matting resin.

[0033] According to some embodiments of the present invention, the black paste uses carbon black produced by the high-pigment furnace process as raw material. The raw materials include: 30 parts carbon black, 30 parts dispersant, 35 parts deionized water, 0.2 parts defoamer, 0.6 parts pH adjuster, 0.2 parts thickener, and 4 parts solvent. Specifically, the carbon black is Orion FW200, the dispersant is BYK2013, the defoamer is BYK011, the pH adjuster is DMEA, the thickener is Tego3060, and the solvent is propylene glycol. Preparation steps:

[0034] 1. Prepare materials and clean equipment;

[0035] 2. Add deionized water, and while stirring at 300-500 rpm, add defoamer, dispersant and carbon black in sequence. Stir for 2-3 minutes, disperse at 600-800 rpm for 10-15 minutes (temperature controlled at 5-40℃ throughout). Grind until fineness ≤15um, then add pH adjuster and solvent in sequence, stir for 3-5 minutes, and adjust pH to 7.5-8.5 with DMEA.

[0036] According to some embodiments of the present invention, the defoamer is at least one of polyether siloxane copolymer and polydimethylsiloxane.

[0037] According to some embodiments of the present invention, the defoamer is at least one of Tego810 and Tego902W from Tego Inc. and BYK024 from BYK Chemicals.

[0038] According to some embodiments of the present invention, the substrate wetting agent is a polyether siloxane copolymer. The wetting agent is used to improve the wetting of the coating on the substrate, reduce the surface energy of the material, improve the flowability of the coating on the substrate, and prevent pinholes.

[0039] According to some embodiments of the present invention, at least one of the Tego 270 and BYK 347 from the Tigo company.

[0040] According to some embodiments of the present invention, solvent A and solvent B are both alcohol ether solvents.

[0041] Solvents are mainly used to lower the Tg point of coatings, so that they can be cured into films at lower temperatures. The solvent used in this invention can lower the Tg point by 30-40°C.

[0042] According to some embodiments of the present invention, solvent A comprises diethylene glycol butyl ether (DB).

[0043] According to some embodiments of the present invention, solvent B comprises dipropylene glycol methyl ether (DPM).

[0044] According to some embodiments of the present invention, solvent A dries relatively quickly and solvent B dries relatively slowly. By adjusting the wet film solvent evaporation gradient through their different evaporation rates, the leveling properties of the paint film are improved, the problem of paint spraying gun clogging is solved, and the workability is improved.

[0045] According to some embodiments of the present invention, the organotin drier improves the drying performance of waterborne two-component polyurethane coatings, reduces drying time, and simultaneously improves the scratch resistance, hardness, and mechanical resistance of the coating film.

[0046] According to some embodiments of the present invention, the organotin drying agent is Borchers' LH 10.

[0047] According to some embodiments of the present invention, the dispersant is at least one of a high molecular weight block copolymer solution, a copolymer containing pigment affinity groups, and an organic modified polyacrylate solution containing pigment affinity groups. The dispersant is used to disperse matting powder, so that the prepared coating has strong uniformity, is delicate and does not develop uneven color.

[0048] According to some embodiments of the present invention, the dispersant is at least one of BYK2012 and BYK2013 from BYK and Tego Dispers 735W and Tego Dispers 750W from Tego Corporation.

[0049] According to some embodiments of the present invention, the wear-resistant additive contains active hydroxyl groups at both ends, which can participate in the crosslinking reaction with isocyanate, thereby improving the crosslinking degree and hardness of the paint film, improving scratch resistance and resistance to matte and glossy scratches, having a certain matting effect, and slightly reducing the amount of matte powder used.

[0050] According to some embodiments of the present invention, the wear-resistant additive is M-3062B from Guangzhou Chuying New Materials.

[0051] According to some embodiments of the present invention, the matting powder is a surfactant-treated precipitated silica matting powder, which is easily dispersed, has an average particle size of 1.5 μm, and high matting efficiency. A small amount added can achieve a coating gloss level below 0.2°. It has excellent transparency and can be used for matting without damaging the base color of the coating. The special surface treatment ensures its high stability in the system and prevents the formation of hard deposits.

[0052] According to some embodiments of the present invention, the matting agent is Evonik's TS-100.

[0053] According to some embodiments of the present invention, the thickener is a low-shear polyurethane thickener used to provide thixotropy to the coating and prevent the wet film of the coating from sagging.

[0054] According to some embodiments of the present invention, the tackifier is Evonik's Tego3060.

[0055] According to some embodiments of the present invention, the pH adjuster is an amine neutralizer, which mainly adjusts the pH of the coating to a weakly alkaline range, which is beneficial for the storage of water-based coatings, improves activation and prevents sedimentation.

[0056] According to some embodiments of the present invention, the pH adjuster is DMEA.

[0057] According to some embodiments of the present invention, the mass ratio of component A, component B and component C is 10:3:1 to 3.

[0058] According to some embodiments of the present invention, component B comprises isocyanate, including hexamethylene diisocyanate, specifically Covestro's. XP 2487 / 1.

[0059] According to some embodiments of the present invention, the preparation method of component A includes the following steps:

[0060] (1) Add the epoxy-modified acrylic resin and the polyurethane resin to a dispersion container at the first stirring speed, add the premixed solvent A and solvent B and stir, then add the substrate wetting agent, black paste, wear-resistant additive and organotin drying agent, stir for 5-8 minutes, increase the speed to the second stirring speed, add the defoamer and dispersant, and stir for 5-10 minutes.

[0061] (2) Add deionized water while reducing the speed, gradually increase the speed to the third stirring speed, add the matting powder, and stir for 20-30 minutes;

[0062] (3) Add the pre-mixed water and pH adjuster, add the thickener, and filter with a 250-350 mesh filter to obtain component A.

[0063] According to some embodiments of the present invention, the first stirring speed is 300 rpm to 500 rpm.

[0064] According to some embodiments of the present invention, the second stirring speed is 500 rpm to 800 rpm.

[0065] According to some embodiments of the present invention, the third stirring speed is 800 rpm to 1500 rpm.

[0066] According to some embodiments of the present invention, the preparation method of component A may be:

[0067] S1. Add resin A and resin B slowly at 300-500 rpm into the dispersion container;

[0068] S2. Add the premixed solvent one and solvent two at a slow speed of 300-500 rpm, stir for 3-5 minutes, and scrape the sides carefully.

[0069] S3. Then add wetting agent, black paste, wear-resistant agent and drying agent at 300-500 rpm, stir for 5-8 minutes, increase the speed to 500-800 rpm, add defoamer and dispersant, stir for 5-10 minutes;

[0070] S4. Add deionized water while reducing the speed, and gradually increase the speed to 800-1500 rpm to add matting powder. Stir at high speed for 20-30 minutes, and pay attention to cooling during the process.

[0071] S5. Add deionized water, pH adjuster and thickener. Please mix the deionized water and pH adjuster in advance and let them stand at room temperature for more than 5 minutes before adding them. Adjust the pH with pH adjuster and adjust the viscosity with deionized water. (Control the temperature between 5-35℃ throughout the process).

[0072] S6. Filter and package using a 250-350 mesh filter to obtain component A.

[0073] A second aspect of the present invention provides a method for preparing the coating of the first aspect of the present invention, the method comprising the step of mixing the components A, B and C.

[0074] One technical solution of the present invention relating to the preparation method of coatings has at least the following beneficial effects:

[0075] The coating preparation method of this invention does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are readily available, the production cost is low, and it is easy to industrialize.

[0076] The third aspect of the present invention provides the application of the coating of the first aspect of the present invention in optical components.

[0077] The present invention relates to a technical solution for the application of coatings in optical components, which has at least the following beneficial effects:

[0078] Imaging quality is improved. The high blackness of the coating effectively suppresses stray light scattering, reduces light reflection and scattering on the surface of components, thereby improving image clarity and contrast, and optimizing the imaging performance of optical equipment.

[0079] It enhances optical performance. Low L-value coatings can reduce light reflection and absorption on optical components, resulting in better performance in high-precision applications and improving the overall performance and effectiveness of optical equipment.

[0080] It improves durability. The coating's excellent scratch and abrasion resistance ensures its durability during long-term use, preventing optical performance degradation due to surface damage and maintaining the long-term stability and reliability of components.

[0081] Multi-substrate adaptability. This coating achieves excellent adhesion on a variety of complex substrates, ensuring stable performance and results in optical components with different materials and surface types.

[0082] Environmental performance. Using a water-based system instead of a solvent-based system reduces the emission of volatile organic compounds (VOCs), meets environmental protection requirements, and helps protect the environment and improve operational safety.

[0083] Improved production efficiency. Optimized coating formulations and processes simplify coating and drying, increasing production efficiency and reducing manufacturing costs, making the production of optical components more economical and efficient.

[0084] During application, add components B and C to component A, spray it onto the surface of various substrates such as PC / PC+ABS, with a film thickness of 15-30μm, flash dry at room temperature for 3-5 minutes, and then bake at 80℃ for 2 hours to obtain a coating that meets the performance requirements. Detailed Implementation

[0085] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0086] In a first aspect, in some embodiments of the present invention, a coating is provided, the raw materials for which are prepared include component A, component B and component C, wherein, by mass parts, component A includes:

[0087] Epoxy-modified acrylic resin: 30-40 parts,

[0088] Polyurethane resin: 10-20 parts

[0089] Black paste: 10-15 parts,

[0090] Defoamer: 0.2-0.3 parts

[0091] Substrate wetting agent: 0.5-1.0 parts,

[0092] Solvent A: 3.0-5.0 parts,

[0093] Solvent B: 3.0-5.0 parts,

[0094] Organotin drying agent: 0.1-0.2 parts,

[0095] Dispersant: 3.0-4.0 parts,

[0096] Wear-resistant additive: 3-5 parts

[0097] Matte powder: 4-6 parts

[0098] Tackifier: 0.2-0.3 parts,

[0099] Water: 10-30 parts

[0100] pH adjuster: 0.1-0.2 parts;

[0101] Component B includes isocyanate;

[0102] Component C includes water.

[0103] It is understood that the present invention uses an aqueous system, which can achieve good scratch resistance (almost no mark residue on the skin) at an L value of around 17, while also satisfying good adhesion and chemical resistance.

[0104] This invention employs a water-based PU system, which has stricter VOC requirements and a smaller range of raw material options compared to solvent-based products. In the coatings of this invention, inorganic matting agents have higher matting efficiency than organic ones because they have greater oil absorption and specific surface area. However, inorganic matting agents have lower strength and abrasion resistance than organic ones. Achieving an ultra-matte finish with organic matting agents is difficult, resulting in insufficient blackness. The key issue is how to achieve an ultra-matte finish while maintaining scratch resistance and abrasion resistance. The resin B used in this invention has strong powder encapsulation properties and is itself a matte resin, further reducing the amount of matting agent in the formulation. This reduces the amount of matting agent that floats to the paint film surface during drying, thus improving scratch resistance. Furthermore, the resin in this invention contains benzene rings or carbonate bonds, both of which are structurally stable groups that can improve the rigidity of the paint film, thereby improving abrasion resistance and solving the aforementioned problems. By using precisely proportioned matte powder and thickener, this invention achieves a near-ultra-matte finish while maintaining high blackness, effectively suppressing stray light scattering and improving optical performance.

[0105] The coating of this invention has excellent adhesion to a variety of complex substrates, good chemical and weather resistance, and can be adapted to optical devices made of different types of materials.

[0106] The water-based system and optimized formulation simplify the coating preparation process, reducing production complexity and costs, while also making the coating easier to handle and control during application. Excellent adhesion to a variety of substrates makes this coating suitable for a wide range of applications, including different types of optical equipment, ensuring its reliability and durability. Improved chemical and weather resistance allows the coating to maintain stability under various environmental conditions, extending its service life.

[0107] In conjunction with the first aspect, in some embodiments of the present invention, the epoxy-modified acrylic resin includes DIC's WLW-270.

[0108] The epoxy-modified acrylic resin used in this invention exhibits excellent chemical resistance, hardness, and adhesion on many substrates, and its internal hydroxyl groups react with isocyanates to form crosslinks. According to some embodiments of the invention, the polyurethane resin includes Covestro's... U 2757.

[0109] The polyurethane resin used in this invention has good elasticity, self-healing ability, good chemical resistance and scratch resistance, and is also a self-matting resin.

[0110] In conjunction with the first aspect, in some embodiments of the present invention, the black paste uses carbon black produced by the high-pigment furnace process as raw material. The raw materials are: 30 parts carbon black, 30 parts dispersant, 35 parts deionized water, 0.2 parts defoamer, 0.6 parts pH adjuster, 0.2 parts thickener, and 4 parts solvent. Specifically, the carbon black is Orion FW200, the dispersant is BYK2013, the defoamer is BYK011, the pH adjuster is DMEA, the thickener is Tego3060, and the solvent is propylene glycol. Preparation steps:

[0111] 1. Prepare materials and clean equipment;

[0112] 2. Add deionized water, and while stirring at 300-500 rpm, add defoamer, dispersant and carbon black in sequence. Stir for 2-3 minutes, disperse at 600-800 rpm for 10-15 minutes (temperature controlled at 5-40℃ throughout). Grind until fineness ≤15um, then add pH adjuster and solvent in sequence, stir for 3-5 minutes, and adjust pH to 7.5-8.5 with DMEA.

[0113] In conjunction with the first aspect, in some embodiments of the present invention, the defoamer is at least one of polyether siloxane copolymer and polydimethylsiloxane.

[0114] In conjunction with the first aspect, in some embodiments of the present invention, the defoamer is at least one of Tego810 and Tego902W from Tego Inc. and BYK024 from BYK Chemicals.

[0115] In conjunction with the first aspect, in some embodiments of the present invention, the substrate wetting agent is a polyether siloxane copolymer. The wetting agent is used to improve the wetting of the coating on the substrate, reduce the surface energy of the material, improve the flowability of the coating on the substrate, and prevent pinholes.

[0116] In conjunction with the first aspect, in some embodiments of the present invention, at least one of Tego 270 and BYK 347 from the company Tego is used.

[0117] In conjunction with the first aspect, in some embodiments of the present invention, solvent A and solvent B are both alcohol ether solvents.

[0118] Solvents are mainly used to lower the Tg point of coatings, so that they can be cured into films at lower temperatures. The solvent used in this invention can lower the Tg point by 30-40°C.

[0119] In conjunction with the first aspect, in some embodiments of the present invention, solvent A comprises diethylene glycol butyl ether (DB).

[0120] In conjunction with the first aspect, in some embodiments of the present invention, solvent B comprises dipropylene glycol methyl ether (DPM).

[0121] In conjunction with the first aspect, in some embodiments of the present invention, solvent A dries relatively quickly and solvent B dries relatively slowly. By adjusting the wet film solvent evaporation gradient through their different evaporation rates, the leveling properties of the paint film are improved, the problem of paint spraying gun clogging is solved, and the workability is improved.

[0122] In conjunction with the first aspect, in some embodiments of the present invention, organotin driers improve the drying performance of waterborne two-component polyurethane coatings, reduce drying time, and simultaneously improve the scratch resistance, hardness, and mechanical resistance of the coating film.

[0123] In conjunction with the first aspect, in some embodiments of the present invention, the organotin drying agent is Borchers' LH 10.

[0124] In conjunction with the first aspect, in some embodiments of the present invention, the dispersant is at least one of a high molecular weight block copolymer solution, a copolymer containing pigment affinity groups, and an organic modified polyacrylate solution containing pigment affinity groups. The dispersant is used to disperse matting powder, so that the prepared coating has strong uniformity, is delicate and does not develop uneven color.

[0125] In conjunction with the first aspect, in some embodiments of the present invention, the dispersant is at least one of BYK 2012 and BYK 2013 from BYK and Tego Dispers 735W and Tego Dispers 750W from Tego Corporation.

[0126] In conjunction with the first aspect, in some embodiments of the present invention, the wear-resistant additive contains active hydroxyl groups at both ends, which can participate in the crosslinking reaction with isocyanate, thereby improving the crosslinking degree and hardness of the paint film, improving scratch resistance and resistance to matte and glossy scratches, having a certain matting effect, and slightly reducing the amount of matte powder used.

[0127] In conjunction with the first aspect, in some embodiments of the present invention, the wear-resistant additive is M-3062B from Guangzhou Chuying New Materials.

[0128] In conjunction with the first aspect, in some embodiments of the present invention, the matting agent is a surfactant-treated precipitated silica matting agent, which is easily dispersed, has an average particle size of 1.5 μm, and high matting efficiency. A small amount added is sufficient to achieve a coating gloss level below 0.2°. It has excellent transparency and can be used for matting without damaging the base color of the coating. The special surface treatment ensures its high stability in the system and prevents the formation of hard deposits.

[0129] In conjunction with the first aspect, in some embodiments of the present invention, the matting agent is Evonik's TS-100.

[0130] In conjunction with the first aspect, in some embodiments of the present invention, the tackifier is a low-shear polyurethane thickener used to provide thixotropy to the coating and prevent the wet film of the coating from sagging.

[0131] In conjunction with the first aspect, in some embodiments of the present invention, the tackifier is Evonik's Tego3060.

[0132] In conjunction with the first aspect, in some embodiments of the present invention, the pH adjuster is an amine neutralizer, which mainly serves to adjust the pH of the coating to a weakly alkaline range, which is beneficial for the storage of water-based coatings, improves activation and prevents sedimentation, etc.

[0133] In conjunction with the first aspect, in some embodiments of the present invention, the pH adjuster is DMEA.

[0134] In conjunction with the first aspect, in some embodiments of the present invention, the mass ratio of component A, component B and component C is 1:3:1 to 3.

[0135] In conjunction with the first aspect, in some embodiments of the present invention, component B includes isocyanates, specifically hexamethylene diisocyanate, specifically Covestro's... XP 2487 / 1.

[0136] In conjunction with the first aspect, in some embodiments of the present invention, the preparation method of component A includes the following steps:

[0137] (1) Add epoxy modified acrylic resin and polyurethane resin to a dispersion container at the first stirring speed, add premixed solvent A and solvent B and stir, then add substrate wetting agent, black paste, wear-resistant additive and organotin drying agent, stir for 5-8 minutes, then increase the speed to the second stirring speed, add defoamer and dispersant, stir for 5-10 minutes.

[0138] (2) Add deionized water while reducing the speed, gradually increase the speed to the third stirring speed, add matting powder, and stir for 20-30 minutes;

[0139] (3) Add pre-mixed water and pH adjuster, add thickener, and filter with a 250-350 mesh filter to obtain component A.

[0140] In conjunction with the first aspect, in some embodiments of the present invention, the first stirring speed is 300 rpm to 500 rpm.

[0141] In conjunction with the first aspect, in some embodiments of the present invention, the second stirring speed is 500 rpm to 800 rpm.

[0142] In conjunction with the first aspect, in some embodiments of the present invention, the third stirring speed is 800 rpm to 1500 rpm.

[0143] In conjunction with the first aspect, in some embodiments of the present invention, the preparation method of component A may be:

[0144] S1. Add resin A and resin B slowly at 300-500 rpm into the dispersion container;

[0145] S2. Add the premixed solvent one and solvent two at a slow speed of 300-500 rpm, stir for 3-5 minutes, and scrape the sides carefully.

[0146] S3. Then add wetting agent, black paste, wear-resistant agent and drying agent at 300-500 rpm, stir for 5-8 minutes, increase the speed to 500-800 rpm, add defoamer and dispersant, stir for 5-10 minutes;

[0147] S4. Add deionized water while reducing the speed, and gradually increase the speed to 800-1500 rpm to add matting powder. Stir at high speed for 20-30 minutes, and pay attention to cooling during the process.

[0148] S5. Add deionized water, pH adjuster and thickener. Please mix the deionized water and pH adjuster in advance and let them stand at room temperature for more than 5 minutes before adding them. Adjust the pH with pH adjuster and adjust the viscosity with deionized water. (Control the temperature between 5-35℃ throughout the process).

[0149] S6. Filter and package using a 250-350 mesh filter to obtain component A.

[0150] In a second aspect, some embodiments of the present invention provide a method for preparing the coating of the first aspect of the present invention, the method comprising the step of mixing component A, component B and component C.

[0151] One technical solution of the present invention relating to the preparation method of coatings has at least the following beneficial effects:

[0152] The coating preparation method of this invention does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are readily available, the production cost is low, and it is easy to industrialize.

[0153] In a third aspect, some embodiments of the present invention provide the application of the coating of the first aspect of the present invention in optical components.

[0154] This invention relates to the application of coatings in optical components, which improves image quality. The high blackness of the coating effectively suppresses stray light scattering, reduces light reflection and scattering on the component surface, thereby improving image clarity and contrast, and optimizing the imaging performance of optical devices.

[0155] It enhances optical performance. Low L-value coatings can reduce light reflection and absorption on optical components, resulting in better performance in high-precision applications and improving the overall performance and effectiveness of optical equipment.

[0156] It improves durability. The coating's excellent scratch and abrasion resistance ensures its durability during long-term use, preventing optical performance degradation due to surface damage and maintaining the long-term stability and reliability of components.

[0157] Multi-substrate adaptability. This coating achieves excellent adhesion on a variety of complex substrates, ensuring stable performance and results in optical components with different materials and surface types.

[0158] Environmental performance. Using a water-based system instead of a solvent-based system reduces the emission of volatile organic compounds (VOCs), meets environmental protection requirements, and helps protect the environment and improve operational safety.

[0159] Improved production efficiency. Optimized coating formulations and processes simplify coating and drying, increasing production efficiency and reducing manufacturing costs, making the production of optical components more economical and efficient.

[0160] During application, add components B and C to component A, spray it onto the surface of various substrates such as PC / PC+ABS, with a film thickness of 15-30μm, flash dry at room temperature for 3-5 minutes, and then bake at 80℃ for 2 hours to obtain a coating that meets the performance requirements.

[0161] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0162] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0163] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0164] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0165] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0166] Example 1

[0167] A coating was prepared using components A, B, and C as raw materials. Component A, based on 100 parts by weight, comprises: epoxy-modified acrylic resin: 30 parts, polyurethane resin: 20 parts, black paste: 10 parts, defoamer: 0.2 parts, substrate wetting agent: 0.5 parts, solvent A: 5.0 parts, solvent B: 4.0 parts, organotin drier: 0.1 parts, dispersant: 3.0 parts, abrasion-resistant additive: 4.0 parts, matting agent: 5 parts, thickener: 0.2 parts, pH adjuster: 0.2 parts, with the remainder being water, making up to 100 parts.

[0168] Component B is an isocyanate, specifically hexamethylene diisocyanate, from Covestro. XP 2487 / 1.

[0169] Component C is water.

[0170] The mass ratio of component A, component B and component C is 10:3:3.

[0171] In component A, the epoxy-modified acrylic resin is DIC's WLW-270, and the polyurethane resin is Covestro's. U 2757. Solvent A is diethylene glycol butyl ether. Solvent B is dipropylene glycol methyl ether.

[0172] The black paste uses carbon black produced by the high-pigment furnace process as raw material. The raw materials are: 30 parts carbon black, 30 parts dispersant, 35 parts deionized water, 0.2 parts defoamer, 0.6 parts pH adjuster, 0.2 parts thickener, and 4 parts solvent. Specifically, the carbon black is Orion FW200, the dispersant is BYK2013, the defoamer is BYK011, the pH adjuster is DMEA, the thickener is Tego3060, and the solvent is propylene glycol. Preparation steps:

[0173] 1. Prepare materials and clean equipment;

[0174] 2. Add deionized water, and while stirring at 300-500 rpm, add defoamer, dispersant and carbon black in sequence. Stir for 2-3 minutes, disperse at 600-800 rpm for 10-15 minutes (temperature controlled at 5-40℃ throughout). Grind until fineness ≤15um, then add pH adjuster and solvent in sequence, stir for 3-5 minutes, and adjust pH to 7.5-8.5 with DMEA.

[0175] The defoamer is Tego 810, the substrate wetting agent is Tego 270, the organotin drying agent is Borchers LH 10, the dispersant is Tego Dispers 735W, the wear-resistant additive is Guangzhou Chuying New Materials M-3062B, the matting agent is Evonik TS-100, the tackifier is Evonik Tego3060, and the pH adjuster is DMEA.

[0176] The preparation method of component A is as follows:

[0177] S1. Add resin A and resin B slowly at 400 rpm into the dispersion container;

[0178] S2. Add the premixed solvent one and solvent two at a slow speed of 400 rpm, stir for 4 minutes, and be careful to scrape the sides.

[0179] S3. Then add wetting agent, black paste, wear-resistant agent and drying agent at 400 rpm, stir for 6 minutes, increase the speed to 700 rpm, add defoamer and dispersant, and stir for 7 minutes;

[0180] S4. Add deionized water while reducing the speed, then gradually increase the speed to 1200 rpm and add matting powder. Stir at high speed for 25 minutes, and pay attention to cooling during the process.

[0181] S5. Add deionized water, pH adjuster and thickener. Please mix the deionized water and pH adjuster in advance and let them stand at room temperature for more than 5 minutes before adding them. Adjust the pH with pH adjuster and adjust the viscosity with deionized water. (Control the temperature between 5-35℃ throughout the process).

[0182] S6. Filter and package using a 300-mesh filter to obtain component A.

[0183] The coating is prepared by mixing component A, component B and component C in a certain proportion.

[0184] Examples 2 to 4

[0185] A separate coating was prepared, differing from Example 1 in that the amounts of each component added were different. Details are shown in Table 1.

[0186] Table 1

[0187]

[0188]

[0189] Comparative Examples 1 to 4

[0190] A separate coating was prepared, differing from Example 1 in that the amounts of each component added were different. Details are shown in Table 1.

[0191] Table 2

[0192] Comparative Serial Number 1 2 3 4 Epoxy modified acrylic resin 40 60 0 0 polyurethane resin 0 0 40 60 Black paste 10 10 10 10 Defoamer 0.2 0.2 0.2 0.2 wetting agent 0.5 0.5 0.5 0.5 Solvent A 5.0 5.0 5.0 5.0 Solvent B 4.0 4.0 4.0 4.0 dispersant 3.0 3.0 3.0 3.0 Drier 0.1 0.1 0.1 0.1 matting powder 5.0 5.0 5.0 5.0 wear-resistant additives 5.0 5.0 5.0 5.0 Thickener 0.2 0.2 0.2 0.2 pH adjuster 0.2 0.2 0.2 0.2 Deionized water margin margin margin margin total 100.00 100.00 100.00 100.00

[0193] The coatings prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were sprayed onto the surface of a PC substrate to form a film with a thickness of 20 micrometers. The film was flash-dried at room temperature for 3 minutes and then baked at 80°C for 2 hours. The film performance was then tested. The results are shown in Table 3.

[0194] Table 3

[0195]

[0196]

[0197]

[0198] It should be noted that the coating of the present invention is applicable not only to PC substrates, but also to the surfaces of various substrates such as PC+ABS.

[0199] This invention utilizes a water-based PU system, which, compared to traditional oil-based products, exhibits low VOCs, meeting environmental protection requirements. It also solves the problem of ultra-matte coatings being prone to scratches, combining low blackness with scratch resistance and excellent abrasion resistance. Furthermore, this invention's coating demonstrates good adhesion to various complex substrates and exhibits excellent chemical and weather resistance.

[0200] It should also be noted that the purpose of this invention is to solve the problems of poor scratch resistance and abrasion resistance of conventional coatings while achieving an ultra-matte finish. Guided by this, the resin raw materials used in this invention were selected through screening, because many resins cannot achieve an ultra-matte effect with a gloss level of less than 1° even with the addition of excessive amounts of matting powder. The resins used in this invention can all achieve an ultra-matte effect, but their abrasion resistance and scratch resistance are not ideal when used alone. This invention, by compounding them in a certain proportion, has obtained a solution that can meet all performance requirements.

[0201] In the coatings of this invention, epoxy-modified acrylic resin exhibits poor scratch resistance and abrasion resistance when used alone, and its L value is relatively high because the resin itself has a high gloss, resulting in a higher gloss than the polyurethane resin solution when the same amount of matting powder is added. Polyurethane resin is a self-matting resin with a self-healing film. When used alone, it can achieve a lower L value and relatively better surface scratch resistance, but it still does not meet the requirements. The adhesion of the film is average, and the hardness is also poor because the resin belongs to the polycarbonate type of polyurethane, which has average hardness. Its larger molecular weight results in lower film density than epoxy-modified acrylic resin. However, due to its larger molecular weight, it has stronger encapsulation of matting powder, thus exhibiting better scratch resistance compared to epoxy-modified acrylic resin.

[0202] The present invention increases the amount of wear-resistant additive, which further improves the Taber test. Based on the comprehensive evaluation of various performance aspects, the range disclosed in this invention is close to the optimal addition amount.

[0203] When used in optical components, the coating of this invention exhibits high blackness, effectively suppressing stray light scattering and reducing light reflection and scattering on the component surface. This improves image clarity and contrast, optimizing the imaging performance of the optical equipment. The low L-value coating reduces light reflection and absorption on optical components, resulting in better performance in high-precision applications and enhancing the overall performance and effectiveness of the optical equipment. The coating's excellent scratch resistance and abrasion resistance ensure durability over long-term use, preventing optical performance degradation due to surface damage and maintaining the long-term stability and reliability of the components. This coating achieves excellent adhesion on various complex substrates, ensuring stable performance and effectiveness in optical components with different materials and surface types. Using an aqueous system instead of a solvent-based system reduces volatile organic compound (VOC) emissions, meeting environmental protection requirements and contributing to environmental protection and operational safety. The optimized coating formulation and process simplify the coating and drying process, improving production efficiency and reducing manufacturing costs, making the production of optical components more economical and efficient.

[0204] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A coating for use in optical devices to suppress stray light scattering, characterized in that, The raw materials include component A, component B, and component C, wherein the mass ratio of component A, component B, and component C is 10:3:1 to 3. Component A, by mass, comprises: Epoxy-modified acrylic resin: 30-40 parts, Polyurethane resin: 10-20 parts Black paste: 10-15 parts, Defoamer: 0.2-0.3 parts Substrate wetting agent: 0.5-1.0 parts, Solvent A: 3.0-5.0 parts, Solvent B: 3.0-5.0 parts, Organotin drying agent: 0.1-0.2 parts, Dispersant: 3.0-4.0 parts, Wear-resistant additive: 3-5 parts Matte powder: 4-6 parts Tackifier: 0.2-0.3 parts, Water: 10-30 parts pH adjuster: 0.1-0.2 parts; Component B includes isocyanate; Component C includes water; The epoxy-modified acrylic resin is DIC's WLW-270; The polyurethane resin is from Covestro. U 2757; The matting agent is Evonik's TS-100; Solvent A is diethylene glycol butyl ether; Solvent B is dipropylene glycol methyl ether.

2. The coating according to claim 1, characterized in that, The preparation method of component A includes the following steps: S1. Add the epoxy-modified acrylic resin and the polyurethane resin to a dispersion container at a first stirring speed, add the premixed solvent A and solvent B and stir, then add the substrate wetting agent, black paste, wear-resistant additive and organotin drying agent, stir for 5-8 minutes, increase the speed to a second stirring speed, add the defoamer and dispersant, and stir for 5-10 minutes. S2. Add deionized water while reducing the speed, gradually increase the speed to the third stirring speed, add the matting powder, and stir for 20-30 minutes. S3. Add the pre-mixed water and pH adjuster, add the thickener, and filter with a 250-350 mesh filter to obtain component A.

3. The coating according to claim 2, characterized in that, The first stirring speed is 300 rpm to 500 rpm; and / or, the second stirring speed is 500 rpm to 800 rpm; and / or, the third stirring speed is 800 rpm to 1500 rpm.

4. A method for preparing the coating as described in any one of claims 1 to 3, characterized in that, The method includes the step of mixing the components A, B and C.

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