Process method for curtain-coating protective coating on surface of optical transparent part

Abstract

The invention belongs to the technical field of spraying processes, and particularly relates to a process method for spraying a protective coating on the surface of an optical transparent part, which reduces the initial construction viscosity and reduces the probability of flow mark generation. According to the defect that a protective coating is prone to generating flow marks and defects in a curvature transition area, an overall curtain coating construction process is creatively adopted for an optimized low-viscosity coating, a process thought of'flood irrigation 'is adopted for curvature positions where defects are prone to being generated, the defects generated in the construction process are scoured by utilizing the gravity flowing characteristic of the coating, and therefore the defects generated in the construction process are washed away. A uniform and continuous liquid film is formed on the surface of the optical transparent part; the process step of secondary curtain coating is introduced, the secondary curtain coating process at the interval of 6 hours is determined by further exploring the window period of the coating, and through comprehensive verification, the optimized process greatly improves the optical performance of the protective coating, and key performance indexes such as optical distortion and angular deviation all meet the use requirements. And meanwhile, the wear resistance of the surface of the optical transparent part is very excellent.

Description

Technical Field

[0001] This application belongs to the field of coating process technology, and specifically relates to a process method for coating a protective coating on the surface of an optically transparent part. Background Technology

[0002] Optical transparent components are widely used in the manufacture of critical precision optical devices in fields such as optical instruments, electronics, building curtain walls, high-speed rail, and aerospace, primarily to provide users with a clear field of vision. When used in areas with severe wind, sand, and dust, the abrasion from these elements can cause "foggy" scratches to appear on the optical transparent components within a short period of use, reducing the user's environmental perception and affecting the overall performance. The technical solution to this problem is to coat the surface of the optical transparent component with a protective coating, which, after curing, forms a transparent, wear-resistant protective coating.

[0003] However, current research on the application process performance of protective coatings is limited to planar specimens and has not evaluated the process performance of optically transparent components with large curvature. Furthermore, the evaluation indicators do not include key optical performance metrics such as optical distortion and angular deviation. Application verification of the coating to optically transparent components with large and multi-curvature curvature using existing processes revealed a significant decrease in the optical performance of the cured coating compared to the blank sample. Key optical performance metrics such as optical distortion and angular deviation did not meet the usage requirements. Analysis and experimental verification showed that the main reason for the decrease in optical performance caused by spray coating on optically transparent components with large curvature was the excessively high viscosity of the coating, resulting in insufficient flowability on the application surface and the accumulation of large-area flow marks, thus leading to a decline in optical performance. Summary of the Invention

[0004] To address the aforementioned problems, this application provides a method for applying a protective coating to the surface of an optically transparent part, comprising:

[0005] Setting up the coating environment: In the construction area, an outer dust cover, a work platform, and an inner dust cover are erected in sequence. The work platform is flush with the optically transparent parts. Inside the dust cover, air filtration equipment, cleaning equipment, temperature and humidity control equipment, paint preparation equipment, and area temperature control equipment are installed.

[0006] Protection of non-construction areas: A transparent plastic film is pasted around the construction area of ​​optically transparent parts to extend and cover the non-construction area;

[0007] Surface cleaning treatment: Clean the surface of the optically transparent parts, blow it twice with an electrostatic gun, and wipe it repeatedly with a lint-free cloth;

[0008] First coating application: Use a protective coating with a viscosity lower than the set requirements. Apply the coating to the highest point of the optically transparent part. Utilize the gravity flow characteristics to form a uniform and continuous liquid film. Allow it to stand and cure for 6 hours.

[0009] Secondary coating application: Six hours after the first coating, a second overall coating is applied, and the coating is cured at a controlled temperature of 23℃-28℃ for 72 hours, followed by a curing at a temperature of 50℃±5℃ for 48 hours.

[0010] Preferably, the temperature and humidity control equipment is turned on before spraying, with the ambient temperature at 23℃~28℃ and the humidity ≤50%; the application is carried out after secondary dust removal by the air filtration equipment.

[0011] Preferably, the protective coating has a viscosity between 10-15 cP at 25°C.

[0012] Preferably, the working platform (5) is highly matched to the curvature profile of the optically transparent part (2).

[0013] Preferably, this method is applicable to transparent parts of aircraft cockpits with large curvature and multiple curvatures with a curvature radius ≤500mm, a coating thickness of 20±5μm, and a light transmittance loss ≤0.5%.

[0014] Preferably, the performance of the cured optically transparent part is verified: the transmittance, haze, optical distortion and angular deviation are tested, and the wear resistance is verified by sand erosion test according to GJB1171-91 standard.

[0015] The advantages of this application include: the use of a two-coating and three-curing process enables the optically transparent parts to meet the requirements. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the construction environment setup for a preferred embodiment of this application. Detailed Implementation

[0017] To make the technical solution and advantages of this application clearer, the technical solution of this application will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of this application, and are only used to explain this application, not to limit this application. It should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings. Other related parts can be referred to the general design. In the absence of conflict, the embodiments and technical features in the embodiments of this application can be combined with each other to obtain new embodiments.

[0018] To address the problem of flow marks and subsequent optical performance degradation on the surface of optically transparent components with high or multiple curvatures after applying a protective coating, a novel coating process for optically transparent components is proposed. This technology enhances the flowability of the protective coating on the surface of optically transparent components with high or multiple curvatures, ensuring continuous and uniform distribution of the coating and preventing large-area flow mark buildup defects. This significantly improves the optical performance of the coated components, meeting the application requirements of optically transparent components. To address existing issues, the viscosity of the protective coating was adjusted to reduce the initial application viscosity, improving its flowability on highly curved and multi-curved transparent surfaces and reducing the probability of flow marks. Recognizing the tendency for flow marks and defects in curved transition areas, a novel overall spray coating process was adopted for the optimized low-viscosity coating. For curved areas prone to defects, a "flooding" approach was used, utilizing the coating's gravity flow characteristics to wash away defects generated during application, resulting in a uniform and continuous liquid film on the optically transparent surface. To address the reduced coating thickness and consequently decreased protective performance due to lower viscosity, the process performance was further adjusted. Through repeated testing, a two-stage spray coating process was introduced. Further exploration of the coating's window period led to the determination of a two-stage spray coating process with a 6-hour interval. Comprehensive verification showed that the optimized process significantly improved the optical performance of the protective coating, with key performance indicators such as optical distortion and angular deviation meeting usage requirements. Simultaneously, the surface abrasion resistance of the optically transparent parts was also excellent.

[0019] like Figure 1 As shown, this is a case study of applying a protective coating to the surface of an optically transparent component in an aircraft cockpit. Figure 1 As shown. The specific implementation method is as follows:

[0020] 1) Setting up the coating environment: The environment for the optically transparent component should be set up in the following order: outer protective cover 1, work platform 5, and inner protective cover 1. The work platform should be flush with the optically transparent component. The outer dust cover should house an air filtration system 3, a cleaning system 4, a temperature and humidity control system 6, a paint mixing system 7, and an area temperature control system 8. The coating environment should be dusted and cleaned. After wiping it clean, a second cleaning should be performed using the air filtration system. Before applying the protective coating, the temperature and humidity control system 6 should be turned on to maintain the ambient temperature between 23℃ and 28℃ and the humidity ≤50%.

[0021] 2) Protection of non-construction areas for optically transparent components: A transparent plastic film is pasted around the construction area of ​​the optically transparent component and extends into the non-construction area to complete the protection of the non-construction area.

[0022] 3) Cleaning the surface of the optically transparent parts: Clean the surface of the optically transparent parts, then blow it twice with an electrostatic gun to check for particles on the surface of the optically transparent parts, and then wipe the surface repeatedly with a lint-free cloth for later use.

[0023] 4) Protective coating spraying: Based on the optimized protective coating formula, a low-viscosity coating is prepared. A comprehensive spray coating application is performed on the optically transparent component. Specifically, at the highest point of the transparent component, a "flooding" spraying method is used, utilizing the gravity flow characteristics of the coating to wash away any defects generated during the application process, until a uniform and continuous liquid film forms on the surface of the optically transparent component. Then, it is allowed to stand and cure for 6 hours.

[0024] 5) Second coat of protective coating: To ensure the wear resistance of the protective coating, after the first coat is applied, wait 6 hours before applying the second coat. Observe the surface to ensure it is glossy and free of defects. Then, control the temperature to 23℃-28℃ and cure for 72 hours, followed by curing at 50℃±5℃ for 48 hours.

[0025] 6) Remove protective devices: Remove the protective devices around the optically transparent parts and complete the spray coating construction.

[0026] 7) Performance Verification of Coated Parts: For coated optical transparent parts, transmittance, haze, optical distortion, and angular deviation were tested. The test results are shown in Table 1. Compared with the blank sample, the optical performance of the coated parts showed virtually no decrease. Referring to GJB1171-91 standard sand, with a sand content of 5 g / m³, a test speed of 90 m / s, and a single sand erosion test time of 71.2 s, sand erosion tests were conducted on the blank sample and the coated parts to evaluate the protective effect. The test data are shown in Table 2. The protective coating effectively improved the substrate's resistance to sand erosion, with an improvement factor of 3.8–52. The coated parts exhibited excellent abrasion resistance.

[0027] With the increasing demand for optically transparent components in areas with severe wind, sand, and dust, improving the wear resistance of their surfaces is essential. This patent addresses the process defects of traditional wear-resistant coating solutions for transparent components by proposing a novel protective coating process for optically transparent components. This process ensures continuous and uniform distribution of the protective coating on the surface, avoiding large-area flow mark buildup and significantly improving the optical performance of the coated components while achieving excellent wear resistance. This lays a technological foundation for enhancing the usability of optically transparent components in areas with severe wind, sand, and dust.

[0028] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A process for the application of a protective coating to the surface of an optically transparent article by curtain coating, characterized in that, Comprise: Spraying environment setup: build outer dust cover, working platform and inner dust cover in sequence in the construction area, the working platform is flush with the optical transparency; configure air filtration equipment, cleaning equipment, temperature and humidity control equipment, paint preparation equipment and regional temperature control equipment in the dust cover; Non-construction area protection: paste transparent plastic film around the optical transparency construction area to cover the non-construction area; Surface cleaning treatment: clean the surface of the optical transparency, blow twice with electrostatic gun, and repeatedly scrub with dust-free cloth; First spraying construction: use protective coating with viscosity lower than the set requirement to implement overall spraying at the highest position of the optical transparency, use gravity flow characteristics to make the coating form uniform continuous liquid film, and stand for 6 hours for solidification; Second spraying construction: implement second overall spraying after 6 hours of the first spraying, control temperature 23-28℃ for 72 hours for solidification, and then control temperature 50℃±5℃ for 48 hours for solidification.

2. The process for the application of a protective coating to the surface of an optically transparent article by curtain coating as recited in claim 1 wherein, Turn on the temperature and humidity control equipment before spraying, the environmental temperature is 23-28℃, and the humidity is ≤50%; spray after the air filtration equipment removes dust twice.

3. The process of claim 1 wherein, The protective coating is preferably 10-15cP in viscosity at 25℃.

4. The process of claim 1 wherein, The working platform (5) matches the curvature profile of the optical transparency (2) in height.

5. The process of claim 1 wherein, The method is suitable for large curvature and multi-curvature aircraft cabin transparency with curvature radius ≤500mm, the coating thickness is 20±5μm, and the light transmittance loss is ≤0.5%.

6. The process of claim 1 wherein, Verify the performance of the solidified optical transparency: test the light transmittance, haze, light distortion and angle deviation, and verify the wear resistance by sand erosion test according to GJB1171-91 standard.

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