A high-strength, high-transmittance antireflective film and its preparation method

Abstract

This invention discloses a high-strength, high-transmittance antireflective film and its preparation method, relating to the field of antireflective film technology. The antireflective film comprises an inner layer, a middle layer, an outer layer, and a coating layer. The inner layer materials include ethylene-vinyl acetate copolymer, nano-cerium dioxide, ethylene-acrylic acid copolymer, and antioxidants. The middle layer materials include metallocene linear low-density polyethylene, low-density polyethylene, nano-boron nitride, maleic anhydride-grafted polyethylene, antioxidants, and light stabilizers. The outer layer materials include nano-magnesium fluoride, ethylene-vinyl acetate copolymer, metallocene linear low-density polyethylene, maleic anhydride-grafted polyethylene, light stabilizers, and silane coupling agents. The coating layer materials include hollow silica-coated boron nitride composite material, diluent, and curing agent. The antireflective film prepared by this invention exhibits excellent optical properties, strong mechanical properties, and good stability.

Description

Technical Field

[0001] This invention relates to the field of antireflective film technology, specifically to a high-strength, high-transmittance antireflective film and its preparation method. Background Technology

[0002] With the rapid development of facility agriculture, the optical, mechanical, and durability properties of agricultural films have become core factors affecting crop yield and quality. Traditional agricultural films generally suffer from insufficient light transmittance, high reflection loss, and excessive haze, resulting in a significant reduction in effective photosynthetic photon flux and severely restricting the growth efficiency of greenhouse crops. More seriously, existing anti-reflective films often sacrifice mechanical strength in pursuit of optical performance, leading to a high breakage rate under extreme weather conditions such as strong winds and hail, significantly increasing agricultural production costs. Furthermore, agricultural films are prone to photo-oxidative degradation under long-term ultraviolet radiation and high temperature and humidity environments, resulting in decreased light transmittance and loss of tensile strength, forcing a drastically shortened replacement cycle, which is seriously contrary to the needs of sustainable development in modern agriculture.

[0003] Prior art with publication number CN112919826B discloses a method for preparing a high-transmittance, dual-reflective antireflective film. This method uses a sol-gel method combined with chemical vapor deposition to prepare a high-transmittance, dual-reflective antireflective film based on a glass substrate, improving optical properties such as transmittance. However, it cannot be applied to flexible materials due to insufficient durability. Prior art with publication number CN113601929A discloses a high-performance agricultural greenhouse film, prepared using a three-layer co-extrusion technology to create an "inner-middle-outer" composite structure greenhouse film. While this improves mechanical properties, it does not solve problems such as reflection loss and insufficient stability.

[0004] In summary, although the existing technical solutions have improved certain properties of agricultural films to some extent, the following technical problems still exist: poor optical performance, insufficient mechanical properties, and low stability. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a high-strength, high-transmittance antireflective film and its preparation method, achieving the following objectives: improving the optical performance, mechanical properties, and stability of the antireflective film.

[0006] To achieve the above objectives, the following technical solution is adopted:

[0007] A high-strength, high-transmittance antireflective film, the antireflective film being composed of an inner layer, a middle layer, an outer layer, and a coating layer.

[0008] The inner layer raw material components include: 60-70 parts of ethylene-vinyl acetate copolymer, 3-5 parts of nano-cerium dioxide, 5-10 parts of ethylene-acrylic acid copolymer, and 0.1-0.2 parts of antioxidant.

[0009] The intermediate layer raw material components include: 40-50 parts of metallocene linear low-density polyethylene, 10-15 parts of low-density polyethylene, 3-5 parts of nano boron nitride, 5-8 parts of maleic anhydride grafted polyethylene, 0.2-0.3 parts of antioxidant, and 0.3-0.5 parts of light stabilizer.

[0010] The outer layer raw material components include: 8-10 parts of nano-magnesium fluoride, 10-20 parts of ethylene-vinyl acetate copolymer, 30-40 parts of metallocene linear low-density polyethylene, 5-8 parts of maleic anhydride grafted polyethylene, 0.3-0.5 parts of light stabilizer, and 0.5-1 parts of silane coupling agent.

[0011] The raw material components of the coating layer include: 60-70 parts of hollow silica-coated boron nitride composite material, 20-30 parts of diluent, and 5-8 parts of curing agent.

[0012] The hollow silica-coated boron nitride composite material is obtained by in-situ synthesis of silica nanoparticles on the surface of aminated boron nitride using tetraethyl orthosilicate, followed by reaction with hydrochloric acid.

[0013] This invention also provides a method for preparing a high-strength, high-transmittance antireflective film, the steps of which are as follows:

[0014] Step 1: Preparation of hollow silica-coated boron nitride composite material

[0015] (1) Boron nitride pretreatment

[0016] Nano-boron nitride was added to an ethanol solution (50% by volume), with a boron nitride to ethanol mass ratio of 1:(18-20). The mixture was ultrasonically dispersed for 30-40 minutes at a power of 300-350 W. Then, a 30% hydrogen peroxide solution was added, with a hydrogen peroxide to boron nitride mass ratio of (5-8):1. The temperature was raised to 60-70℃, and ultrasonic treatment continued for 1-2 hours. After ultrasonication, the mixture was cooled to... At room temperature, adjust the pH of the system to 4-5 with hydrochloric acid solution; slowly add γ-aminopropyltriethoxysilane, where γ-aminopropyltriethoxysilane is 1-3% of the mass of nano-boron nitride; after stirring until homogeneous, heat to 60-70℃, stirring at 300-400 rpm for 2-3 hours; after the reaction is complete, centrifuge at 8000-9000 rpm for 10-15 minutes; then dry at 60-70℃ for 6-7 hours to obtain amino-modified boron nitride. The hydrochloric acid solution is 5% (w / w) dilute hydrochloric acid.

[0017] (2) Synthesis of silica-coated boron nitride composite material

[0018] Aminated boron nitride was added to an ethanol solution (80% by volume), with a boron nitride to ethanol mass ratio of 1:(40-42). The mixture was sonicated until the boron nitride was completely dispersed at 300-350 W. A template agent was added and stirred to dissolve the mixture, with a template agent to boron nitride mass ratio of (0.5-1):10. Ammonia was added dropwise to adjust the pH to 9-10. Tetraethyl orthosilicate was then slowly added, with a tetraethyl orthosilicate to boron nitride mass ratio of (0.5-1):1. The mixture was stirred at room temperature for 8-10 hours at 300-400 rpm. After the reaction was complete, the mixture was centrifuged at 9000-10000 rpm for 15-20 minutes. The mixture was then dried to obtain a silica-coated boron nitride composite material. The drying process involves a temperature of 60-70℃ and a drying time of 8-9 hours; the template agent is hexadecyltrimethylammonium bromide; and the ammonia solution has a mass concentration of 25%.

[0019] (3) Prepare hollow silica-coated boron nitride composite material

[0020] The silica-coated boron nitride composite material was added to hydrochloric acid with a concentration of 0.4-0.5 mol / L, and the silica-coated boron nitride composite material accounted for 2-3% of the mass of hydrochloric acid. The temperature was raised to 70-80℃, the stirring speed was 300-400 rpm, and the stirring time was 3-4 h. After stirring, the mixture was centrifuged at 9000-10000 rpm for 15-20 min, and then dried at 60-70℃ for 6-7 h to obtain the hollow silica-coated boron nitride composite material.

[0021] Step 2: Prepare the coating solution

[0022] Hollow silica-coated boron nitride composite material is added to a diluent and stirred at a speed of 300-400 rpm for 30-40 minutes. After stirring, ultrasonic treatment is performed at a power of 300-350 W for 30-60 minutes. Then, a curing agent is added and stirring is continued for 10-20 minutes to obtain the coating solution.

[0023] Step 3: Co-extrusion molding

[0024] The raw materials for the inner, middle, and outer layers are mixed separately according to the formula to form premixes for each layer. These premixes are then added to a three-layer co-extrusion extruder. The extruder temperature settings are as follows: feed section 110-140℃, compression section 140-160℃, melt section 160-180℃, homogenization section 170-190℃, connector section 175-195℃, transition section 180-200℃, distributor section 180-200℃, and die exit temperature 185-205℃. After extrusion, the film is blown, cooled, and corona-treated to obtain the co-extruded film. Blowing parameters are set as follows: blow ratio 3.0, traction speed 15m / min; cooling parameters: air ring cooling temperature 20℃; corona treatment parameters: corona treatment power 10kW, treatment speed 15m / min.

[0025] Step 4: Coating and curing to form a film

[0026] The co-extruded film is coated after passing through a cooling roller using a microgravure coating method with a screen count of 140-160 lines / cm and a dry film thickness of 0.5-1.0μm. After coating, it is cured by first drying with hot air at 75-80℃ for 1-2 minutes, then raising the temperature to 130-140℃ and controlling the humidity at 50±5%RH for 3-4 minutes. After slowly cooling to room temperature, the film is wound up to obtain the product.

[0027] Mechanism of action of this invention:

[0028] The hollow structure of the boron nitride composite material coated with hollow silica can reduce the interface reflection between the coating layer and the air; after the boron nitride is coated with silica, it forms a "rigid skeleton" in the coating layer while reducing reflection, which significantly improves the hardness and impact resistance of the coating layer.

[0029] This invention's antireflective film, through a specific multilayer structure design and by adjusting the components of each layer, achieves a gradient decrease in refractive index from the substrate to air, significantly reducing the refractive index difference at each interface and minimizing reflection. The interactions between components and the synergistic effects at the interfaces greatly enhance the film's mechanical properties, while the curing effect of the coating further strengthens the film's surface hardness and impact resistance. The selection of raw materials for each layer and the structural design work synergistically to ultimately optimize overall performance.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) The antireflective film prepared by the present invention has high transmittance, low reflectance, and low haze. The transmittance reaches 94.9-95.5%, and the haze reaches 14.3-15.7%.

[0032] (2) The antireflective film prepared by the present invention has excellent mechanical properties, with a transverse tensile strength of 42.1-46.3 MPa, a longitudinal tensile strength of 46.5-49.8 MPa, a dart impact strength of 425-468 g, and a puncture strength of 52.6-57.1 N.

[0033] (3) The antireflective film prepared by the present invention has excellent stability. After ultraviolet aging treatment and damp heat aging treatment, the transmittance and mechanical strength are well maintained. Attached Figure Description

[0034] Appendix Figure 1 This is a transmission electron microscope (TEM) image of the hollow silica-coated boron nitride composite material prepared in the step of "Preparation of hollow silica-coated boron nitride composite material".

[0035] Appendix Figure 2 The reflectance spectrum of the antireflection film prepared in this invention in the visible light band of 380-780nm. Detailed Implementation

[0036] Example 1: A high-strength, high-transmittance antireflective film

[0037] A high-strength, high-transmittance antireflective film, comprising an inner layer, a middle layer, an outer layer, and a coating layer.

[0038] The inner layer raw material components include: 60 parts of ethylene-vinyl acetate copolymer, 5 parts of nano-cerium dioxide, 10 parts of ethylene-acrylic acid copolymer, and 0.1 parts of antioxidant.

[0039] The intermediate layer raw material components include: 40 parts of metallocene linear low-density polyethylene, 15 parts of low-density polyethylene, 5 parts of nano boron nitride, 8 parts of maleic anhydride grafted polyethylene, 0.2 parts of antioxidant, and 0.3 parts of light stabilizer.

[0040] The outer layer raw material components include: 8 parts of nano-magnesium fluoride, 20 parts of ethylene-vinyl acetate copolymer, 30 parts of metallocene linear low-density polyethylene, 8 parts of maleic anhydride grafted polyethylene, 0.3 parts of light stabilizer, and 0.5 parts of silane coupling agent.

[0041] The raw material components of the coating layer include: 60 parts of hollow silica-coated boron nitride composite material, 20 parts of diluent, and 5 parts of curing agent.

[0042] The light stabilizer is a hindered phenolic light stabilizer, model number NOR356.

[0043] The antioxidant is a hindered phenolic and phosphite complex antioxidant, model B225.

[0044] The silane coupling agent is KH550.

[0045] The diluent is an ethanol solution with a mass fraction of 10-20%.

[0046] The curing agent is tetraethyl orthosilicate.

[0047] All the above quantities are by weight.

[0048] A method for preparing a high-strength, high-transmittance antireflective film, comprising the following steps:

[0049] Step 1: Preparation of hollow silica-coated boron nitride composite material

[0050] (1) Boron nitride pretreatment

[0051] Nano-sized boron nitride was added to an ethanol solution (50% by volume, with a boron nitride to ethanol mass ratio of 1:18) and ultrasonically dispersed for 30 min at a power of 350 W. Then, a 30% hydrogen peroxide solution (5:1 by mass) was added, and the mixture was heated to 60°C and ultrasonically treated for 2 h. After ultrasonication, the mixture was cooled to room temperature, and the pH was adjusted to 4 with hydrochloric acid. γ-aminopropyltriethoxysilane (1% by mass of boron nitride) was slowly added dropwise, and the mixture was stirred until homogeneous. The mixture was then heated to 60°C, stirred at 300 rpm, and reacted for 3 h. After the reaction, the mixture was centrifuged at 8000 rpm for 15 min. Finally, the mixture was dried at 60°C for 7 h to obtain amino-modified boron nitride. The hydrochloric acid solution was a 5% (w / w) dilute hydrochloric acid solution.

[0052] (2) Synthesis of silica-coated boron nitride composite material

[0053] Aminated boron nitride was added to an ethanol solution (80% by volume), with a boron nitride to ethanol mass ratio of 1:40. The mixture was sonicated until the boron nitride was completely dispersed at 300W. A template agent was added and stirred to dissolve the mixture (template agent to boron nitride mass ratio of 0.5:10). Ammonia was added dropwise to adjust the pH to 9. Then, tetraethyl orthosilicate was slowly added dropwise (tetraethyl orthosilicate to boron nitride mass ratio of 0.5:1). The mixture was stirred at room temperature for 8 hours at 400 rpm. After the reaction was complete, the mixture was centrifuged at 9000 rpm for 20 minutes. After centrifugation, the mixture was dried to obtain a silica-coated boron nitride composite material. The drying temperature was 60℃ for 9 hours. The template agent was hexadecyltrimethylammonium bromide. The ammonia concentration was 25%.

[0054] (3) Prepare hollow silica-coated boron nitride composite material

[0055] The silica-coated boron nitride composite material was added to hydrochloric acid with a concentration of 0.4 mol / L, and the silica-coated boron nitride composite material accounted for 2% of the mass of hydrochloric acid. The temperature was raised to 70℃, the stirring speed was 300 rpm, and the stirring time was 4 h. After stirring, the mixture was centrifuged at 9000 rpm for 20 min, and then dried at 60℃ for 7 h to obtain the hollow silica-coated boron nitride composite material.

[0056] Step 2: Prepare the coating solution

[0057] Hollow silica-coated boron nitride composite material was added to a diluent and stirred at 300 rpm for 40 min. After stirring, ultrasonic treatment was performed at 300 W for 60 min. Then, a curing agent was added and stirring was continued for 10 min to obtain the coating solution.

[0058] Step 3: Co-extrusion molding

[0059] The raw materials for the inner, middle, and outer layers were mixed according to the formula to form premixes for each layer. These premixes were then added to a three-layer co-extrusion extruder. The temperature and process conditions for each zone of the extruder are shown in Table 1. After extrusion through the die, the film was blown, cooled, and corona-treated to obtain the co-extruded film. Blown film parameters were set as follows: blow ratio 3.0, traction speed 15 m / min; cooling parameters: air ring cooling temperature 20℃; corona treatment parameters: corona treatment power 10 kW, treatment speed 15 m / min.

[0060] Table 1 Temperature and process conditions in each zone of the extruder

[0061]

[0062] Step 4: Coating and curing to form a film

[0063] The co-extruded film is coated after passing through a cooling roller using a microgravure coating method with a screen count of 140 lines / cm, controlling the dry film thickness to 0.5μm. After coating, curing is performed. First, it is dried with hot air at 75℃ for 2 minutes, then the temperature is raised to 130℃, the humidity is controlled at 50±5%RH, and the curing time is 4 minutes. The film is then slowly cooled to room temperature and wound up to obtain the product. The resulting product has a thickness of 0.15mm±5%, with the thickness ratio of the inner layer, middle layer, and outer layer being 1:1:1.

[0064] Example 2: A high-strength, high-transmittance antireflective film

[0065] A high-strength, high-transmittance antireflective film, the antireflective film being composed of an inner layer, a middle layer, an outer layer, and a coating layer.

[0066] The inner layer raw material components include: 65 parts of ethylene-vinyl acetate copolymer, 5 parts of nano-cerium dioxide, 10 parts of ethylene-acrylic acid copolymer, and 0.2 parts of antioxidant.

[0067] The intermediate layer raw material components include: 50 parts of metallocene linear low-density polyethylene, 15 parts of low-density polyethylene, 5 parts of nano boron nitride, 8 parts of maleic anhydride grafted polyethylene, 0.3 parts of antioxidant, and 0.5 parts of light stabilizer.

[0068] The outer layer raw material components include: 10 parts of nano-magnesium fluoride, 15 parts of ethylene-vinyl acetate copolymer, 35 parts of metallocene linear low-density polyethylene, 8 parts of maleic anhydride grafted polyethylene, 0.5 parts of light stabilizer, and 1 part of silane coupling agent.

[0069] The raw material components of the coating layer include: 70 parts of hollow silica-coated boron nitride composite material, 30 parts of diluent, and 8 parts of curing agent.

[0070] All the above quantities are by weight.

[0071] The light stabilizer, antioxidant, silane coupling agent, diluent, and curing agent are the same as in Example 1.

[0072] A method for preparing a high-strength, high-transmittance antireflective film, comprising the following steps:

[0073] Step 1: Preparation of hollow silica-coated boron nitride composite material

[0074] (1) Boron nitride pretreatment

[0075] Nano-sized boron nitride was added to an ethanol solution (50% by volume, with a boron nitride to ethanol mass ratio of 1:20) and ultrasonically dispersed for 40 min at a power of 350 W. Then, a 30% hydrogen peroxide solution (7:1 by mass) was added, and the mixture was heated to 70°C and ultrasonically treated for 1 h. After ultrasonication, the mixture was cooled to room temperature, and the pH was adjusted to 5 with hydrochloric acid. γ-aminopropyltriethoxysilane (2% by mass of the boron nitride) was slowly added dropwise, and the mixture was stirred until homogeneous. The mixture was then heated to 70°C, stirred at 400 rpm, and reacted for 3 h. After the reaction, the mixture was centrifuged at 9000 rpm for 15 min. Finally, the mixture was dried at 70°C for 6 h to obtain amino-modified boron nitride. The hydrochloric acid solution was a 5% (w / w) dilute hydrochloric acid solution.

[0076] (2) Synthesis of silica-coated boron nitride composite material

[0077] Aminated boron nitride was added to an 80% (v / v) aqueous ethanol solution at a mass ratio of 1:40. The mixture was ultrasonically treated until the aminated boron nitride was completely dispersed at a power of 350 W. A template agent was added and stirred until dissolved at a mass ratio of 1:10 (v / v). Ammonia was added dropwise to adjust the pH to 10. Then, tetraethyl orthosilicate (tetraethyl orthosilicate to aminated boron nitride) was slowly added dropwise at a mass ratio of 1:1. The mixture was stirred at room temperature for 10 hours at a stirring speed of 400 rpm. After the reaction was complete, the mixture was centrifuged at 10,000 rpm for 20 minutes. After centrifugation, the mixture was dried to obtain a silica-coated boron nitride composite material. The drying temperature was 70°C for 8 hours. The template agent was hexadecyltrimethylammonium bromide. The ammonia concentration was 25%.

[0078] (3) Prepare hollow silica-coated boron nitride composite material

[0079] The silica-coated boron nitride composite material was added to 0.5 mol / L hydrochloric acid, with the silica-coated boron nitride composite material accounting for 3% of the mass of hydrochloric acid. The temperature was raised to 80℃, the stirring speed was 400 rpm, and the stirring time was 4 h. After stirring, the mixture was centrifuged at 10000 rpm for 20 min, and then dried at 70℃ for 7 h to obtain the hollow silica-coated boron nitride composite material.

[0080] Step 2: Prepare the coating solution

[0081] Hollow silica-coated boron nitride composite material was added to a diluent and stirred at 300 rpm for 40 minutes. After stirring, ultrasonic treatment was performed at 350 W for 60 minutes. Then, a curing agent was added and stirring was continued for 20 minutes to obtain the coating solution.

[0082] Step 3: Co-extrusion molding

[0083] The raw materials for the inner, middle, and outer layers were mixed according to the formula to form premixes for each layer. These premixes were then added to a three-layer co-extrusion extruder. The temperature and process conditions for each zone of the extruder are shown in Table 2. After extrusion through the die, the film was blown, cooled, and corona-treated to obtain the co-extruded film. Blown film parameters were set as follows: blow ratio 3.0, traction speed 15 m / min; cooling parameters: air ring cooling temperature 20℃; corona treatment parameters: corona treatment power 10 kW, treatment speed 15 m / min.

[0084] Table 2 Temperature and process conditions in each zone of the extruder

[0085]

[0086] Step 4: Coating and curing to form a film

[0087] The co-extruded film is coated after passing through a cooling roller using a microgravure coating method with a screen count of 140-160 lines / cm, controlling the dry film thickness to be 0.5-1.0 μm. After coating, curing is performed. First, it is dried with hot air at 75-80℃ for 1-2 minutes, then the temperature is raised to 130-140℃, the humidity is controlled at 50±5%RH, and the curing time is 3-4 minutes. It is then slowly cooled to room temperature and wound up to obtain the product. The resulting product has a thickness of 0.15mm±5%, with the thickness ratio of the inner layer, middle layer, and outer layer being 1:1:1.

[0088] Example 3: A high-strength, high-transmittance antireflective film

[0089] A high-strength, high-transmittance antireflective film, the antireflective film being composed of an inner layer, a middle layer, an outer layer, and a coating layer.

[0090] The inner layer raw material components include: 70 parts of ethylene-vinyl acetate copolymer, 3 parts of nano-cerium dioxide, 5 parts of ethylene-acrylic acid copolymer, and 0.2 parts of antioxidant.

[0091] The intermediate layer raw material components include: 50 parts of metallocene linear low-density polyethylene, 10 parts of low-density polyethylene, 3 parts of nano boron nitride, 5 parts of maleic anhydride grafted polyethylene, 0.3 parts of antioxidant, and 0.5 parts of light stabilizer.

[0092] The outer layer raw material components include: 10 parts of nano-magnesium fluoride, 10 parts of ethylene-vinyl acetate copolymer, 40 parts of metallocene linear low-density polyethylene, 5 parts of maleic anhydride grafted polyethylene, 0.5 parts of light stabilizer, and 1 part of silane coupling agent.

[0093] The raw material components of the coating layer include: 70 parts of hollow silica-coated boron nitride composite material, 30 parts of diluent, and 8 parts of curing agent.

[0094] The light stabilizer, antioxidant, silane coupling agent, diluent, and curing agent are the same as in Example 1.

[0095] All the above quantities are by weight.

[0096] A method for preparing a high-strength, high-transmittance antireflective film, comprising the following steps:

[0097] Step 1: Preparation of hollow silica-coated boron nitride composite material

[0098] (1) Boron nitride pretreatment

[0099] Nano-sized boron nitride was added to an ethanol solution (50% by volume, with a boron nitride to ethanol mass ratio of 1:20) and ultrasonically dispersed for 40 min at a power of 300 W. Then, a 30% hydrogen peroxide solution (8:1 by mass) was added, and the mixture was heated to 70°C and ultrasonically treated for 1.5 h. After ultrasonication, the mixture was cooled to room temperature, and the pH was adjusted to 5 with hydrochloric acid. γ-aminopropyltriethoxysilane (3% by mass of the boron nitride) was slowly added dropwise, and the mixture was stirred until homogeneous. The mixture was then heated to 70°C, stirred at 400 rpm, and reacted for 2 h. After the reaction, the mixture was centrifuged at 9000 rpm for 10 min and then dried at 70°C for 6 h to obtain amino-modified boron nitride. The hydrochloric acid solution was a 5% (w / w) dilute hydrochloric acid solution.

[0100] (2) Synthesis of silica-coated boron nitride composite material

[0101] Aminated boron nitride was added to an 80% (v / v) aqueous ethanol solution with a boron nitride to ethanol mass ratio of 1:42. The mixture was ultrasonically treated until the boron nitride was completely dispersed at a power of 350 W. A template agent was added and stirred to dissolve the mixture; the template agent to boron nitride mass ratio was 1:10. Ammonia was added dropwise to adjust the pH to 10. Then, tetraethyl orthosilicate (TES) was slowly added dropwise; the TES mass ratio was 1:1. The mixture was stirred at room temperature for 10 hours at a speed of 300 rpm. After the reaction was complete, the mixture was centrifuged at 10,000 rpm for 15 minutes. After centrifugation, the mixture was dried to obtain a silica-coated boron nitride composite material. The drying temperature was 70℃, and the drying time was 8 hours. The template agent was hexadecyltrimethylammonium bromide, and the ammonia concentration was 25%.

[0102] (3) Prepare hollow silica-coated boron nitride composite material

[0103] The silica-coated boron nitride composite material was added to 0.5 mol / L hydrochloric acid, with the silica-coated boron nitride composite material accounting for 3% of the mass of hydrochloric acid. The temperature was raised to 80℃, the stirring speed was 400 rpm, and the stirring time was 3 h. After stirring, the mixture was centrifuged at 10000 rpm for 15 min, and then dried at 70℃ for 6 h to obtain the hollow silica-coated boron nitride composite material.

[0104] Step 2: Prepare the coating solution

[0105] Hollow silica-coated boron nitride composite material was added to a diluent and stirred at 400 rpm for 30 minutes. After stirring, ultrasonic treatment was performed at 350 W for 30 minutes. Then, a curing agent was added and stirring was continued for 20 minutes to obtain the coating solution.

[0106] Step 3: Co-extrusion molding

[0107] The raw materials for the inner, middle, and outer layers were mixed according to the formula to form premixes for each layer. These premixes were then added to a three-layer co-extrusion extruder. The temperature and process conditions for each zone of the extruder are shown in Table 3. After extrusion through the die, the film was blown, cooled, and corona-treated to obtain the co-extruded film. Blown film parameters were set as follows: blow ratio 3.0, traction speed 15 m / min; cooling parameters: air ring cooling temperature 20℃; corona treatment parameters: corona treatment power 10 kW, treatment speed 15 m / min.

[0108] Table 3 Temperature and process conditions in each zone of the extruder

[0109]

[0110] Step 4: Coating and curing to form a film

[0111] The co-extruded film is coated after passing through a cooling roller using a microgravure coating method with a screen count of 160 lines / cm, controlling the dry film thickness to 1.0 μm. After coating, it undergoes curing. First, it is dried with hot air at 80℃ for 1 minute, then the temperature is raised to 140℃, the humidity is controlled at 50±5%RH, and the curing time is 3 minutes. It is then slowly cooled to room temperature and wound up to obtain the product. The resulting product has a thickness of 0.15 mm±5%, with the thickness ratio of the inner layer, middle layer, and outer layer being 1:1:1.

[0112] Comparative Example 1

[0113] An antireflective film, the antireflective film comprising an inner layer, an intermediate layer, an outer layer, and a coating layer.

[0114] The inner layer raw material components include: 65 parts of ethylene-vinyl acetate copolymer, 5 parts of nano-cerium dioxide, 10 parts of ethylene-acrylic acid copolymer, and 0.2 parts of antioxidant.

[0115] The intermediate layer raw material components include: 50 parts of metallocene linear low-density polyethylene, 15 parts of low-density polyethylene, 5 parts of nano boron nitride, 8 parts of maleic anhydride grafted polyethylene, 0.3 parts of antioxidant, and 0.5 parts of light stabilizer.

[0116] The outer layer raw material components include: 10 parts of nano-magnesium fluoride, 15 parts of ethylene-vinyl acetate copolymer, 35 parts of metallocene linear low-density polyethylene, 8 parts of maleic anhydride grafted polyethylene, 0.5 parts of light stabilizer, and 1 part of silane coupling agent.

[0117] The raw material components of the coating layer include: 70 parts hollow silica, 30 parts diluent, and 8 parts curing agent.

[0118] All the above quantities are by weight.

[0119] A method for preparing an antireflective film, comprising the following steps:

[0120] Step 1: Prepare the coating solution

[0121] Hollow silica was added to the diluent and stirred at 300 rpm for 40 minutes. After stirring, ultrasonic treatment was performed at 350 W for 60 minutes. Then, the curing agent was added and stirring was continued for 20 minutes to obtain the coating solution.

[0122] Step 2: Co-extrusion molding

[0123] This step is the same as the "co-extrusion molding" step in Example 2.

[0124] Step 3: Coating and curing to form a film

[0125] This step is the same as the "coating and curing to form a film" step in Example 2.

[0126] Example 4 Performance Testing

[0127] (a) Optical performance testing

[0128] The antireflective films prepared in Examples 1-3 and Comparative Example 1 were subjected to transmittance and haze tests according to the test methods provided in GB / T 2410-2008. The specific test results are shown in Table 4. Reflectance was measured using a spectrophotometer in the visible light band of 380-780 nm. Specific data are attached. Figure 2 .

[0129] Table 4

[0130]

[0131] As shown in Table 4, the antireflective films prepared in Examples 1-3 have a transmittance of 94.9-95.5% and a haze of 14.3-15.7%, which are significantly improved compared to the comparative examples. Figure 2 It can be seen that the reflectivity of the antireflective films prepared in Examples 1-3 is significantly reduced.

[0132] (ii) Mechanical property testing

[0133] The antireflective films prepared in Examples 1-3 and Comparative Example 1 were tested for transverse and longitudinal tensile strength according to the test method provided in GB / T 1040-2006, for dart impact strength according to the test method provided in GB / T 9639.1-2008, and for puncture strength according to the test method provided in GB / T 10004-2008. The specific test results are shown in Table 5.

[0134] Table 5

[0135]

[0136] As shown in Table 5, the antireflective films prepared in Examples 1-3 have a transverse tensile strength of 42.1-46.3 MPa, a longitudinal tensile strength of 46.5-49.8 MPa, a dart impact strength of 425-468 g, and a puncture strength of 52.6-57.1 N.

[0137] (III) Stability Testing

[0138] The antireflective films prepared in Examples 1-3 and Comparative Example 1 were subjected to ultraviolet aging and damp heat aging tests. Following the standard GB / T16422.3, long-term light exposure was simulated in an ultraviolet aging chamber, and the changes in transmittance and tensile strength after 2000 hours of light exposure were tested. After damp heat aging, the films were placed in a constant temperature and humidity chamber (85℃ / 85%RH) for 1000 hours, and the changes in transmittance and tensile strength were tested. Specific test results are shown in Table 6.

[0139] Table 6

[0140]

[0141] As shown in Table 6, the antireflective films prepared in Examples 1-3 maintained a transmittance of 91.8-92.5%, a transverse tensile strength of 40.8-44.7 MPa, and a longitudinal tensile strength of 43.2-46.5 MPa after UV aging treatment. After damp heat aging treatment, the transmittance remained at 91.5-92.2%, the transverse tensile strength at 39.3-43.2 MPa, and the longitudinal tensile strength at 42.8-45.6 MPa. Compared with the comparative examples, they retained higher transmittance and tensile strength, indicating that the antireflective films prepared by this invention have excellent stability.

[0142] The specific parameters of the raw materials used in this invention are as follows:

[0143] The density of the metallocene linear low-density polyethylene is 0.914-0.922 g / cm³.

[0144] The density of the low-density polyethylene is 0.917-0.925 g / cm³. 3 .

[0145] The ethylene-acrylic acid copolymer has an AA content of 15-20%.

[0146] The VA content of the ethylene-vinyl acetate copolymer is 12-15%.

[0147] The maleic anhydride-grafted polyethylene has a density of 0.925-0.935 g / cm³ and a grafting rate of 0.8-1.5%.

[0148] It should be noted that any changes made under the inventive concept of this invention will fall within the protection scope of this invention.

Claims

1. A high-strength, high-transmittance antireflective film, characterized in that: The antireflective film consists of an inner layer, a middle layer, an outer layer, and a coating layer; The inner layer raw material components include: 60-70 parts of ethylene-vinyl acetate copolymer, 3-5 parts of nano-cerium dioxide, 5-10 parts of ethylene-acrylic acid copolymer, and 0.1-0.2 parts of antioxidant; The intermediate layer raw material components include: 40-50 parts of metallocene linear low-density polyethylene, 10-15 parts of low-density polyethylene, 3-5 parts of nano boron nitride, 5-8 parts of maleic anhydride grafted polyethylene, 0.2-0.3 parts of antioxidant, and 0.3-0.5 parts of light stabilizer. The outer layer raw material components include: 8-10 parts of nano-magnesium fluoride, 10-20 parts of ethylene-vinyl acetate copolymer, 30-40 parts of metallocene linear low-density polyethylene, 5-8 parts of maleic anhydride grafted polyethylene, 0.3-0.5 parts of light stabilizer, and 0.5-1 parts of silane coupling agent. The raw material components of the coating layer include: 60-70 parts of hollow silica-coated boron nitride composite material, 20-30 parts of diluent, and 5-8 parts of curing agent; the diluent is an ethanol solution with a mass fraction of 10-20%. All the above quantities are by weight. The hollow silica-coated boron nitride composite material is obtained by in-situ synthesis of silica nanoparticles on the surface of aminated boron nitride using tetraethyl orthosilicate, followed by reaction with hydrochloric acid.

2. The method for preparing a high-strength, high-transmittance antireflective film according to claim 1, characterized in that: The process includes the steps of preparing hollow silica-coated boron nitride composite material, preparing coating solution, co-extrusion molding, coating and curing to form a film; The preparation of hollow silica-coated boron nitride composite material includes the following steps: boron nitride pretreatment, synthesis of silica-coated boron nitride composite material, and preparation of hollow silica-coated boron nitride composite material. The boron nitride pretreatment process involves adding nano-boron nitride to an ethanol solution and ultrasonically dispersing it; then adding hydrogen peroxide solution, heating to 60-70℃, and continuing ultrasonic treatment for 1-2 hours; after ultrasonic treatment, cooling to room temperature, and adjusting the pH of the system to 4-5 with hydrochloric acid solution; slowly adding γ-aminopropyltriethoxysilane, stirring until homogeneous, heating to 60-70℃, and stirring for 2-3 hours; after the reaction is complete, centrifuging and drying yields amino-modified boron nitride.

3. The method for preparing a high-strength, high-transmittance antireflective film according to claim 2, characterized in that: In the boron nitride pretreatment step, the ethanol solution is a 50% (v / v) aqueous ethanol solution, and the mass ratio of nano-boron nitride to the ethanol solution is 1:(18-20); the hydrogen peroxide solution is a 30% (v / v) aqueous hydrogen peroxide solution, and the mass ratio of hydrogen peroxide solution to nano-boron nitride is (5-8):1; the amount of γ-aminopropyltriethoxysilane added is 1-3% of the mass of nano-boron nitride.

4. The method for preparing a high-strength, high-transmittance antireflective film according to claim 2, characterized in that: The synthesis of the silica-coated boron nitride composite material is as follows: aminated boron nitride is added to an ethanol solution and ultrasonically dispersed; a template agent is added, stirred and dissolved, and ammonia is added dropwise to adjust the pH value to 9-10; then tetraethyl orthosilicate is slowly added, and the mixture is stirred at room temperature for 8-10 hours; after the reaction is completed, the silica-coated boron nitride composite material is obtained after centrifugation and drying.

5. The method for preparing a high-strength, high-transmittance antireflective film according to claim 4, characterized in that: In the step of synthesizing the silica-coated boron nitride composite material, the ethanol solution is an 80% (v / v) aqueous ethanol solution, and the mass ratio of aminated boron nitride to the ethanol solution is 1:(40-42); the template agent is hexadecyltrimethylammonium bromide, and the mass ratio of the template agent to aminated boron nitride is (0.5-1):10; the mass ratio of tetraethyl orthosilicate to aminated boron nitride is (0.5-1):

10.

6. The method for preparing a high-strength, high-transmittance antireflective film according to claim 2, characterized in that: The hollow silica-coated boron nitride composite material was prepared by adding the silica-coated boron nitride composite material to hydrochloric acid with a concentration of 0.4-0.5 mol / L and the silica-coated boron nitride composite material accounting for 2-3% of the mass of hydrochloric acid. The temperature was raised to 70-80℃ and stirred for 3-4 hours. After stirring, the composite material was obtained by centrifugation and drying.

7. The method for preparing a high-strength, high-transmittance antireflective film according to claim 2, characterized in that: The coating solution is prepared by adding the hollow silica-coated boron nitride composite material to the diluent and stirring for 30-40 minutes. After stirring, ultrasonic treatment is performed with an ultrasonic power of 300-350W for 30-60 minutes. Then, the curing agent is added and stirring is continued for 10-20 minutes to obtain the coating solution.

8. The method for preparing a high-strength, high-transmittance antireflective film according to claim 2, characterized in that: The coating and curing process involves curing after coating is completed. The curing process involves first drying with hot air at 75-80℃ for 1-2 minutes, then raising the temperature to 130-140℃, controlling the humidity at 50±5%RH, and curing for 3-4 minutes.

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