A thermosetting back coating for optical diffusion film, its preparation method and application

Abstract

This invention belongs to the field of optical diffusion film technology, and relates to a thermosetting back coating for optical diffusion films, its preparation method, and its application. The coating liquid comprises the following substances in parts by weight: adhesive: 30-35 parts by weight, curing agent: 2.2-3.7 parts by weight, organic particles: 0.2-1 parts by weight, leveling agent: 0.2-0.5 parts by weight, N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent: 0.3-0.8 parts by weight, and organic solvent: 60-66 parts by weight. The technical solution of this application can obtain a thermosetting back coating with stable impedance effect, strong weather resistance, no precipitation after aging test, and no reduction in coating adhesion.

Description

Technical Field

[0001] This invention belongs to the field of diffusion film technology, and relates to a thermosetting back coating of optical diffusion film, its preparation method and application. Background Technology

[0002] Diffusion films are primarily used in the optical display field, including products such as televisions, tablets, laptops, automotive displays, and mobile phones. Their back coating mainly serves to resist scratches and abrasion, prevent adhesion, and prevent static electricity. The addition of antistatic agents to the back coating effectively reduces dust and lint adsorbed due to static electricity by lowering the coating's impedance, significantly reducing the risk of "white spot" defects on the screen after assembly. In production, it can improve uneven winding and reduce friction between the film surface and guide rollers caused by static electricity, thus reducing film surface damage.

[0003] Existing optical diffusion films often have poor antistatic agents in their thermosetting backing resin coatings. Specifically, the coating lacks impedance, has high static electricity, attracts dust, and causes spot-like defects on the film. Summary of the Invention

[0004] This application provides a thermosetting back coating for optical diffusion film, its preparation method and application. This technology selects an antistatic agent with good compatibility with adhesives to obtain a thermosetting back coating with stable impedance effect, strong weather resistance, no precipitation after aging test and no reduction in coating adhesion.

[0005] To achieve the above technical objectives, the technical solution adopted in this application is a thermosetting back coating for an optical diffusion film, which is formed by coating with a coating liquid, wherein the coating liquid comprises the following substances in parts by weight: Adhesive: 30-35 parts by weight Hardener: 2.2~3.7 parts by weight Organic particles: 0.2~1 parts by weight N-Hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent: 0.3~0.8 parts by weight Leveling agent: 0.2~0.5 parts by weight Organic solvent: 60-66 parts by weight; The N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent is prepared using the following steps: (1) Obtaining the reaction solution: 9.3 parts of 4-methylpyridine, 18 parts of 1-chlorohexane, 40 parts of DMF solvent, and 1.66 parts of potassium iodide were used as catalysts. The mixture was stirred at 500 r / min in an oil bath at 115 °C. A sample was taken and diluted, and AgNO3 solution was added until no precipitate was formed. (2) Obtaining the precipitated solid: After cooling the reaction solution to room temperature, 400 parts of ethyl acetate were added to precipitate a pale yellow solid; (3) Obtain N-hexyl-4-methylpyridine chloride: Take out the pale yellow solid from step (2), wash with ethyl acetate to remove the by-reaction product from step (1), and dry under vacuum at 55°C for 24 hours to obtain N-hexyl-4-methylpyridine chloride; (4) Obtaining the solution: Take 10 parts of N-hexyl-4-methylpyridine chloride obtained in step (3) and dissolve it in 80 parts of deionized water to prepare solution 1. Take 10 parts of NaN(SO2F)2 and dissolve it in 30 parts of deionized water to prepare solution 2. (5) Add solution 2 to solution 1, and obtain a viscous liquid precipitated under stirring. Collect the precipitated liquid and wash until no Cl is found in the wash. - The product was dried to obtain a pale yellow solid, which was then used to prepare N-hexyl-4-methylpyridine difluorosulfonylimide salt as an antistatic agent.

[0006] As an improved technical solution of this application, the adhesive is selected from one or more of acrylic resin and polyurethane resin in any weight ratio.

[0007] As an improved technical solution of this application, the organic particles are one or more of polymethyl methacrylate, polybutyl methacrylate, and polyamide in any weight ratio.

[0008] As an improved technical solution of this application, the curing agent includes one or more of aliphatic polyisocyanates and aromatic polyisocyanates in any weight ratio.

[0009] As an improved technical solution of this application, the leveling agent is one or more of the following: an organosilicon surface-modified leveling agent, an acrylate leveling agent, or any weight ratio thereof.

[0010] As an improved technical solution of this application, the solvent is one or more of ethyl acetate, butyl acetate, and butanone in any weight ratio.

[0011] As an improved technical solution of this application, the coating liquid is applied by gravure coating.

[0012] Another technical objective of this application is to provide a method for preparing a thermosetting back coating of an optical diffusion film, comprising the following steps: Step 1: Mix the organic solvent and organic particles according to the specified ratio and stir for 20 minutes; Step 2: Add leveling agent, N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent, and adhesive to Step 1 according to the specified proportions, and stir for 20 minutes to disperse and obtain a suspension; Step 3: Add the curing agent to the mixture from Step 2 according to the specified ratio, and stir for 10 minutes to obtain the final coating liquid; Step 4: Apply the obtained coating liquid to the corona-exposed surface of the PET base film using a doctor blade, and then heat and cure it in an oven to obtain a thermosetting back coating.

[0013] Another objective of this application is to provide an application of the aforementioned optical diffusion film thermosetting back coating in a display module.

[0014] Beneficial effects (1) The combination of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent and leveling agent solves the problem of incompatibility between most antistatic agents and leveling agents. By adding a certain proportion of leveling agent to the coating, the uniformity of the coating surface can be improved during the production process; in addition, due to the addition of leveling agent, the wettability and fluidity of the coating on the base film surface are enhanced, the leveling time of the coating is shortened, and the production speed can be increased.

[0015] (2) When N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent is added to thermosetting acrylic resin, after polyurethane coating, it will not migrate to the interface between the coating and the base film to form a weak interface layer, thereby reducing the adhesion of the coating; it will also not produce side reactions with curing agents (such as HDI), consume curing agents, and affect the curing efficiency of the coating.

[0016] (3) N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent has low requirements for environmental humidity and its surface resistance can remain stable for a long time, thereby reducing the probability of the film adsorbing dust and causing black spot defects.

[0017] (4) Compared with existing antistatic agents (the antistatic agents in the back coating of optical diffusion films are mainly of two types: ionic and conductive filler type. Conductive filler type antistatic agents are not widely mass-produced because they affect the optical performance of the finished product, have poor dispersion in the coating liquid, are easy to agglomerate, and cause uneven surface resistance of the coating surface; ionic antistatic agents are mainly of three types: pyridinium salt, quaternary ammonium salt, and imidazolium salt. Through testing, it was found that the addition of quaternary ammonium salt and imidazolium type antistatic agents to thermosetting acrylic resin coatings will reduce the coating strength). The curing rate of the coating layer can be affected, and even the adhesion of the coating can be compromised. Quaternary ammonium salt antistatic agents tend to migrate to the interface between the coating and the base film, damaging the coating adhesion; the hydrogen at the C2 position of the imidazole ring in imidazole salt antistatic agents can react with the curing agent, consuming the curing agent and affecting the coating curing efficiency. The N-hexyl-4-methylpyridine difluorosulfonyl ammonium salt antistatic agent of this invention is a pyridine onionium salt antistatic agent. Its advantage lies in that it does not reduce the curing rate of the coating while ensuring that the surface resistance meets product requirements. Its improvement lies in the fact that the synthesized antistatic agent does not react with the curing agent (such as HDI), and ions do not migrate to the interface between the coating and the base film, reducing the coating adhesion. It can be used in conjunction with organosilicon surface-modifying leveling agents to ensure the uniformity of the coating surface.

[0018] In summary, this application, based on the antistatic agent N-hexyl-4-methylpyridine difluorosulfonylimide salt, effectively solves the problem of "white spots" defects caused by electrostatic adsorption of dust in optical diffusion films after module assembly by adjusting the components such as adhesives, leveling agents, organic particles, and solvents, and simultaneously adjusting the dosage of each component. It also reduces the risk of film surface scratches during winding. The resulting thermosetting back coating of optical diffusion films meets the product design requirements in terms of surface resistance, peel force of the protective film, optical performance, and coating adhesion. Attached Figure Description

[0019] Figure 1 Synthesis reaction diagram for the preparation of N-hexyl-4-methylpyridine chloride; Figure 2 Synthetic reaction diagram for the preparation of N-hexyl-4-methylpyridine difluorosulfonyl ammonium salt; Figure 3 : Schematic diagram of optical diffusion film structure; In the figure, 1 is the light-diffusing layer; 2 is the substrate; and 3 is the back coating containing an antistatic agent. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] Unless otherwise specified, the materials used in this technology are commercially available products, and the methods employed are conventional technical means.

[0022] Material description: PBMA, Polybutyl methacrylate; PMMA, Polymethyl methacrylate; HDI, Hexamethylene Diisocyanate; TDI, Toluene Diisocyanate; DMF, N,N-Dimethylformamide, N,N-Dimethylformamide; NaFSI, Sodium bis(fluorosulfonyl)imide.

[0023] A thermosetting back coating for an optical diffusion film is formed by gravure coating using a coating liquid, wherein the coating liquid comprises the following substances in parts by weight: Adhesive: 30-35 parts by weight Hardener: 2.2~3.7 parts by weight Organic particles: 0.2~1 parts by weight Hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent: 0.3~0.8 parts by weight Leveling agent: 0.2~0.5 parts by weight Organic solvent: 60~66 parts by weight.

[0024] The N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent is prepared using the following steps: (1) Obtaining the reaction solution: Add 9.3 parts of 4-methylpyridine, 18 parts of 1-chlorohexane, 40 parts of DMF solvent, and 1.66 parts of potassium iodide as catalyst to a three-necked flask equipped with a reflux condenser. Stir at 500 r / min in an oil bath at 115℃. Take a sample every 12 hours to dilute and add AgNO3 solution until no precipitate is formed. Record the stirring time as 90 hours. (2) Obtaining the precipitated solid: After the reaction solution is cooled to room temperature, 400 parts of ethyl acetate are slowly added to the flask, and a pale yellow solid is precipitated. (3) Obtain N-hexyl-4-methylpyridine chloride: Take out the pale yellow solid from step (2), wash it 5 times with ethyl acetate to remove the by-reaction products from step (1), and dry it under vacuum at 55°C for 24 hours to obtain N-hexyl-4-methylpyridine chloride; (4) Obtaining the solution: Take 10 parts of N-hexyl-4-methylpyridine chloride obtained in step (3) and dissolve it in 80 parts of deionized water to prepare solution 1. Take 10 parts of NaN(SO2F)2 and dissolve it in 30 parts of deionized water to prepare solution 2. (5) Slowly add solution 2 to solution 1, set the speed to 800 r / min, and stir for 20 h to obtain a viscous liquid precipitate. Collect the precipitate and wash it 5 times with deionized water until no Cl is found in the washes. - Drying at 90℃ for 36 hours yields a pale yellow solid, which is then used to prepare N-hexyl-4-methylpyridine difluorosulfonylimide salt as an antistatic agent.

[0025] Existing technologies also employ N-hexyl-4-methylpyridine bis(trifluoromethanesulfonyl)imide salt antistatic agents. The anionic portion is bis(trifluoromethanesulfonyl)imide, containing two trifluoromethanesulfonyl groups (-SO2CF3) and a CF3 bond. In practical applications, these antistatic agents can slowly migrate from product surfaces, volatilize, or wear off, entering home and office environments and becoming a source of PFAS in indoor dust. This application's N-hexyl-4-methylpyridine bis(fluoromethanesulfonyl)imide salt antistatic agent, an anionic bis(fluoromethanesulfonyl)imide containing two fluorosulfonyl groups (-SO2F) and no CF3 bond, meets industry environmental testing standards and poses no harm to human health.

[0026] In some embodiments, the adhesive is selected from one or more of acrylic resins and polyurethane resins in any weight ratio. As the main component of the coating material, the adhesive encapsulates organic particles and functional additives, providing a coating with good adhesion. Combined with a suitable anilox roller, it completes the online coating process. Insufficient or excessive application primarily affects optical performance and production efficiency.

[0027] In some embodiments, the organic particles include one or more of polymethyl methacrylate, polybutyl methacrylate, and polyamide in any weight ratio. By selecting particles of different materials, particle sizes, and particle size distributions, the addition of organic particles can reduce the risk of adsorption between the film and the diffuser plate, and reduce the risk of scratching the light guide plate.

[0028] In some embodiments, the curing agent includes one or more of aliphatic polyisocyanates and aromatic polyisocyanates in any weight ratio. Specifically, aliphatic polyisocyanates include HDI, and aromatic polyisocyanates include TDI. The curing agent and adhesive undergo initial curing at high temperature, initially forming a molecular network with a certain cross-linking density. Subsequently, a specific temperature is set, and after several hours or even tens of hours of curing, a coating with high hardness, weather resistance, and flexibility is finally formed.

[0029] In some embodiments, the leveling agent is one or more of the following: silicone surface-modified leveling agent, polyacrylate leveling agent, or any weight ratio thereof. Insufficient leveling agent will result in a mottled finished film surface and unsatisfactory appearance. It will also affect the surface resistivity of the coating. Excessive leveling agent will reduce the effectiveness of the protective film application and cause a decrease in peel strength. It can effectively improve surface defects during coating production, such as pinholes and orange peel, and improve the smoothness of the coating.

[0030] In some embodiments, the organic solvent is one or more of ethyl acetate, butyl acetate, and butanone, used in combination. The role of the solvent is to have a specific evaporation rate gradient. Selecting a combination of solvents with high and low evaporation rates can reduce the occurrence of pinholes and orange peel in the coating. It also reduces corrosiveness to the substrate and effectively dissolves adhesives, antistatic agents, and related additives.

[0031] The use of an antistatic agent based on an optical diffusion film thermosetting back coating in this application includes the following steps: Step 1: Mix the organic solvent and organic particles according to the specified ratio and stir for 20 minutes; Step 2: Add leveling agent, N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent, and adhesive to Step 1 according to the specified proportions, and stir for 20 minutes to disperse and obtain a suspension; Step 3: Add the curing agent to the mixture from Step 2 according to the specified ratio, and stir for 10 minutes to obtain the final coating liquid; Step 4: Apply the obtained coating liquid to the surface of the corona-treated / non-corona-treated PET base film using a doctor blade, and then heat and cure it in an oven to obtain a thermosetting back coating.

[0032] Example 1 A thermosetting back coating for an optical diffusion film, its preparation method, and its application. The structure of the finished diffusion film is as follows: Figure 3 The coating comprises a light-emitting layer 1, a substrate 2, and a back coating layer 3 containing an antistatic agent. Both the light-emitting layer 1 and the back coating layer 2 containing the antistatic agent are applied using a gravure coating process. The antistatic agent is N-hexyl-4-methylpyridine difluorosulfonylimide salt, which meets the impedance requirements of the product without compromising the adhesion of the coating.

[0033] The specific preparation steps of a thermosetting back coating for an optical diffusion film are as follows: Step 1: Preparation of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent. Figure 1 and Figure 2 The specific steps for creating the synthesis roadmap are as follows: (1) Add 9.3 parts of 4-methylpyridine, 18 parts of 1-chlorohexane, 40 parts of DMF solvent, and 1.66 parts of potassium iodide as catalyst to a three-necked flask equipped with a reflux condenser. Stir at 500 r / min in an oil bath at 115 °C. Take a sample every 12 hours to dilute and add 0.1 mol / L AgNO3 solution. Continue stirring until no precipitate is formed. Record the stirring time as 90 hours. (2) After the reaction solution is cooled to room temperature, 400 parts of ethyl acetate are slowly added to the flask, and a pale yellow solid is precipitated. (3) Take out the pale yellow solid from step (2), wash it 5 times with ethyl acetate to remove the by-reaction products from step (1), and dry it under vacuum at 55°C for 24 hours to obtain N-hexyl-4-methylpyridine chloride. (4) Take 10 parts of N-hexyl-4-methylpyridine chloride obtained in step (3), dissolve it in 80 parts of deionized water to prepare solution 1, and take 10 parts of NaN(SO2F)2 to dissolve in 30 parts of deionized water to prepare solution 2; (5) Slowly add solution 2 to solution 1, set the speed to 800 r / min, and stir for 20 h to obtain a viscous liquid precipitate. Collect the precipitate and wash it 5 times with deionized water until no Cl is found in the washes. - Drying at 90℃ for 36 hours yields a pale yellow solid, which is then used to prepare N-hexyl-4-methylpyridine difluorosulfonylimide salt as an antistatic agent.

[0034] Step 2: The preparation method of a thermosetting back coating for an optical diffusion film is as follows: (1) Mix 32 parts of ethyl acetate, 32 parts of butyl acetate and 0.2 parts of PBMA particles with a particle size distribution of 7 μm, and stir at a speed of 800 r / min for 20 min; (2) Add 0.2 parts of organosilicon surface modifier leveling agent (BYK Chemical), 0.5 parts of N-hexyl-4-methylpyridine difluorosulfonyl imide salt antistatic agent, and 32 parts of acrylic resin to step two (1), set the speed to 800 r / min, and stir for 20 min to disperse and obtain a suspension. (3) Add 3 parts of aliphatic polyisocyanate curing agent to the suspension in step (2) and stir for 10 min to obtain the final coating liquid; (4) The obtained coating liquid is applied to the corona surface of the PET base film using a scraper. The oven is set to 120°C and the baking time is 1 minute to obtain a diffusion film back coating with an antistatic agent coating.

[0035] Example 2 As provided in Example 1, the preparation method of the thermosetting back coating of the optical diffusion film is as follows: in step two (1), 1 part of PBMA particles with a particle size of 7 μm, 33 parts of ethyl acetate, and 33 parts of butyl acetate are used; in step two (2), 0.5 parts of organosilicon surface-modifying leveling agent (BYK Chemical), 0.3 parts of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent, and 30 parts of acrylic resin are used; in step two (3), 2.2 parts of aliphatic polyisocyanate are used, and the other conditions remain unchanged.

[0036] Example 3 As provided in Example 1, the method for preparing an optical diffusion film thermosetting back coating is as follows: in step two (1), 0.2 parts of PMMA particles with a particle size of 7 μm, 30 parts of ethyl acetate, and 30 parts of butyl acetate are used; in step two (2), 0.3 parts of organosilicon surface-modifying leveling agent (BYK Chemical), 0.8 parts of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent, and 35 parts of acrylic resin are used; in step two (3), 3.7 parts of aliphatic polyisocyanate are used, and the other conditions remain unchanged.

[0037] Example 4 As provided in Example 1, the preparation method of the thermosetting back coating of the optical diffusion film is as follows: in step two (1), 0.3 parts of PMMA particles with a particle size of 7 μm, 32 parts of ethyl acetate, and 32 parts of butyl acetate are used; in step two (2), 0.2 parts of organosilicon surface-modifying leveling agent (BYK Chemicals), 0.5 parts of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent, and 32 parts of polyurethane resin are used; in step two (3), 3 parts of aliphatic polyisocyanate are used, and the other conditions remain unchanged.

[0038] Example 5 As provided in Example 1, the method for preparing an optical diffusion film thermosetting back coating is as follows: in step two (1), 0.3 parts of PBMA particles with a particle size of 7 μm, 32 parts of ethyl acetate, and 32 parts of butyl acetate are used; in step two (2), 0.2 parts of organosilicon surface-modifying leveling agent (BYK Chemical), 0.3 parts of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent, and 32 parts of polyurethane resin are used; in step two (3), 3.2 parts of aromatic polyisocyanate are used, and the other conditions remain unchanged.

[0039] Example 6 As provided in Example 1, the preparation method of the thermosetting back coating of the optical diffusion film is as follows: in step two (1), 0.3 parts of PBMA particles with a particle size of 7 μm, 32 parts of ethyl acetate, and 32 parts of butanone are used; in step two (2), 0.2 parts of polyacrylate leveling agent, 0.5 parts of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent, and 32 parts of acrylic resin are used; in step two (3), 3 parts of aromatic polyisocyanate are used, and the other conditions remain unchanged.

[0040] Example 7 As provided in Example 1, the method for preparing an optical diffusion film thermosetting back coating is as follows: in step two (4), the baking time is 40 seconds, and the other conditions remain unchanged.

[0041] Comparative Example 1 As provided in Example 1, a method for preparing an optical diffusion film thermosetting back coating is provided, wherein in step two (1), 0.3 parts of PBMA particles with a particle size distribution of 7 μm are replaced with 1.3 parts of PBMA particles with a particle size distribution of 7 μm, and the other conditions remain unchanged.

[0042] Comparative Example 2 As provided in Example 1, a method for preparing a thermosetting back coating of an optical diffusion film is provided, wherein in step two (1), 32 parts of butyl acetate are replaced with 32 parts of toluene, and the other conditions remain unchanged.

[0043] Comparative Example 3 As provided in Example 1, a method for preparing an optical diffusion film thermosetting back coating is provided, wherein in step two (2), 0.5 parts of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent are replaced with 0.5 parts of quaternary ammonium salt antistatic agent, and the other conditions remain unchanged.

[0044] Comparative Example 4 As provided in Example 1, a method for preparing an optical diffusion film thermosetting back coating is provided, wherein in step two (2), 0.5 parts of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent are replaced with 0.1 parts of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent, and the other conditions remain unchanged.

[0045] Comparative Example 5 As provided in Example 1, a method for preparing an optical diffusion film thermosetting back coating is provided, wherein in step two (2), 0.2 parts of organosilicon surface-modifying leveling agent (BYK Chemical) are replaced with 0 parts of organosilicon surface-modifying leveling agent, and the other conditions remain unchanged.

[0046] Comparative Example 6 As provided in Example 1, a method for preparing a thermosetting back coating of an optical diffusion film is provided, wherein step two (4) of applying the coating to the corona-exposed surface of the PET base film using a scraper is replaced by applying the coating to the non-corona-exposed surface of the PET base film using a scraper, while the other conditions remain unchanged.

[0047] The performance of the optical diffusion film-based thermosetting back coatings obtained in the above embodiments and comparative examples was evaluated using the following method: (1) Coating adhesion test: Use a cross-cutting tool with a 1mm spacing, with the tip perpendicular to the film, apply a certain force to make one cut, rotate the tip 90° and make another cut, then clean the debris with a brush, use 3M 600 tape to stick to the cross-cutting area, quickly tear it off, and observe the cross-cutting peeling. Test data ≥4B is qualified.

[0048] (2) Peel strength test of protective film: Use a 3-5g protective film, apply it to the coating surface, and press it firmly with a roller. Use a tensile tester to test, and the test data ≥2g is qualified.

[0049] (3) Surface resistance test: The surface resistance of the coated reflective film was tested using a SIMCO ST-4 surface resistance meter. The test value was <10. 13 It is qualified; (4) Haze / transmittance test: TH-110 haze meter (Hangzhou Caipu Technology Co., Ltd.) was used.

[0050] (5) Solubility test: The antistatic agent is dropped into different solvents and observed for layering and precipitation. If there is precipitation, it is unqualified.

[0051] (6) High temperature and high humidity precipitation test: Cut the coated reflective film into A4 samples and put them into a high temperature and high humidity aging chamber. After aging for 240 h at 60 °C and 90% RH, test whether there is precipitation on the appearance of the film and the resistance stability.

[0052] The performance characterization results of each embodiment and comparative example are shown in Table 1. The coating adhesion test was conducted according to the national standard GB / T9286. 5B means 0% peeling within 100 cross-sections, 4B means less than 5% peeling within 100 cross-sections, 3B means 5-15% peeling within 100 cross-sections, 2B means 15-35% peeling within 100 cross-sections, 1B means 35-65% peeling within 100 cross-sections, and 0B means greater than 65% peeling within 100 cross-sections.

[0053] Table 1 Performance characterization results of Examples 1-6 and Comparative Examples 1-8 Example 1 5B 3.2 12.1 5.06% 90.23% good none ◎ Example 2 5B 2.4 12.7 15.68% 89.12% good none ◎ Example 3 5B 3.1 11.6 4.81% 90.33% good none ◎ Example 4 5B 3.2 12.3 5.75% 89.26% good none ◎ Example 5 5B 3.3 12.8 5.03% 89.84% good none ◎ Example 6 5B 3.1 12.2 5.45% 89.89% good none ◎ Example 7 5B 3.0 12.1 5.12% 90.21% good none ◎ Comparative Example 1 5B 1.8 12.2 22.68% 88.75% good none ○ Comparative Example 2 5B 1.6 13.5 6.07% 89.8% Difference have △ Comparative Example 3 0B 3.1 9.3 5.18% 89.36% good none △ Comparative Example 4 5B 3.2 13.2 5.56% 89.34% good none ○ Comparative Example 5 5B 3.5 13.5 5.51% 89.84% good none △ Comparative Example 6 3B 2.9 12.1 5.05% 89.74% good none △ Note: ◎ indicates excellent; ○ indicates good; △ indicates poor.

[0054] According to the results of Example 1 and Comparative Example 1, when the proportion of organic particles increases, the surface resistance and coating adhesion are OK, but the peel force decreases to 1.8g, which is unqualified.

[0055] According to the results of Example 1 and Comparative Example 2, the N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent has poor dispersion in toluene, with a surface resistivity of 13.5, which is unqualified.

[0056] According to the results of Example 1 and Comparative Example 3, the coating adhesion was unqualified after the antistatic agent was replaced with a quaternary ammonium salt antistatic agent.

[0057] According to the results of Example 1 and Comparative Example 4, when the amount of N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent added is less than the stated weight, the surface resistance is 13.2, which is greater than 13 and therefore unqualified.

[0058] Based on the results of Example 1 and Comparative Example 5, the surface resistance was 13.5 without the addition of a leveling agent, which is unacceptable. This indicates that the N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent must be used in conjunction with a leveling agent.

[0059] According to the results of Example 1 and Comparative Example 6, the adhesion of the coating on the non-corona-treated surface of the PET base film is worse than that on the corona-treated surface, which is unqualified.

Claims

1. An optical diffusion film thermoset backcoat, characterized by, It is applied using a coating liquid, which comprises the following substances in parts by weight: Adhesive: 30-35 parts by weight Hardener: 2.2~3.7 parts by weight Organic particles: 0.2~1 parts by weight N-Hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent: 0.3~0.8 parts by weight Leveling agent: 0.2~0.5 parts by weight Organic solvent: 60-66 parts by weight; The N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent is prepared using the following steps: (1) Obtaining the reaction solution: 9.3 parts of 4-methylpyridine, 18 parts of 1-chlorohexane, 40 parts of DMF solvent, and 1.66 parts of potassium iodide were used as catalysts. The mixture was stirred at 500 r / min in an oil bath at 115 °C. A sample was taken and diluted, and AgNO3 solution was added until no precipitate was formed. (2) Obtaining the precipitated solid: After cooling the reaction solution to room temperature, 400 parts of ethyl acetate were added to precipitate a pale yellow solid; (3) Obtain N-hexyl-4-methylpyridine chloride: Take out the pale yellow solid from step (2), wash with ethyl acetate to remove the by-reaction product from step (1), and dry under vacuum at 55°C for 24 hours to obtain N-hexyl-4-methylpyridine chloride; (4) Obtaining the solution: Take 10 parts of N-hexyl-4-methylpyridine chloride obtained in step (3) and dissolve it in 80 parts of deionized water to prepare solution 1. Take 10 parts of NaN(SO2F)2 and dissolve it in 30 parts of deionized water to prepare solution 2. (5) Add the solution 2 to the solution 1, and obtain the precipitated viscous liquid under stirring, collect the precipitated liquid, and wash until there is no Cl in the washing liquid - ; dry to obtain light yellow solid, and prepare N-hexyl-4-methylpyridine bisfluorosulfonyl imide salt antistatic agent.

2. The thermoset backcoat for optical diffuser film of claim 1, wherein, The adhesive is selected from one or more of acrylic resins and polyurethane resins in any weight ratio.

3. The thermoset backcoat for optical diffusion film of claim 1, wherein, The organic particles are one or more of polymethyl methacrylate, polybutyl methacrylate, and polyamide in any weight ratio.

4. The thermoset backcoat for optical diffusion film of claim 1, wherein, The curing agent includes one or more of aliphatic polyisocyanates and aromatic polyisocyanates in any weight ratio.

5. The thermoset backcoat for optical diffusion film of claim 1, wherein, The leveling agent is one or more of the following: an organosilicon surface-modified leveling agent, an acrylate leveling agent, or any weight ratio thereof.

6. The thermosetting back coating for an optical diffusion film according to claim 1, characterized in that, The solvent is one or more of ethyl acetate, butyl acetate, and butanone in any weight ratio.

7. The thermosetting back coating for an optical diffusion film according to claim 1, characterized in that, It is produced by gravure coating using a coating liquid.

8. A method for preparing a thermosetting back coating of an optical diffusion film as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Mix the organic solvent and organic particles according to the specified ratio and stir for 20 minutes; Step 2: Add leveling agent, N-hexyl-4-methylpyridine difluorosulfonylimide salt antistatic agent, and adhesive to Step 1 according to the specified proportions, and stir for 20 minutes to disperse and obtain a suspension; Step 3: Add the curing agent to the mixture from Step 2 according to the specified ratio, and stir for 10 minutes to obtain the final coating liquid; Step 4: Apply the obtained coating liquid to the corona-exposed surface of the PET base film using a doctor blade, and then heat and cure it in an oven to obtain a thermosetting back coating.

9. The application of the optical diffusion film thermosetting back coating as described in any one of claims 1-7 in a display module.

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