A protective film

Abstract

The present application relates to the field of thin film optical technology, and particularly relates to a light stabilizer and a protective film. In order to solve the problem that the light stabilizer is precipitated from the adhesive layer of the protective film at a large amount of addition, the present application provides a light stabilizer and a protective film. The protective film comprises, from top to bottom, an anti-glare film, an adhesive layer and a barrier film; the adhesive layer is formed by an adhesive composition, and the adhesive composition comprises an acrylate, a photoinitiator and a light stabilizer; the light stabilizer is obtained by the reaction of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and 2-isocyanate ethyl acrylate. The light stabilizer in the adhesive layer of the protective film provided by the present application will not be precipitated or migrated.

Description

Technical Field

[0001] This invention relates to the field of thin-film optics, and particularly to a light stabilizer and a protective film. Background Technology

[0002] Electronic paper display (EPD) is a special type of thin and light display screen, also known as an "electronic ink screen." Unlike traditional display screens, electronic ink screens do not emit light themselves; they rely on reflecting ambient light to display images, thus eliminating the need for a backlight or backlight module. Electronic ink screens are widely used due to their low power consumption, wide viewing angles, eye-friendly design, and reusability. The components of an electronic ink screen include a substrate, electronic paper, a protective film, and electronic components, with the protective film playing a crucial role in protecting the electronic paper.

[0003] When e-ink screens are used in outdoor displays, such as bus stop signs and billboards, the ultraviolet rays in sunlight cause severe aging of the e-ink and materials. Therefore, the adhesive layer of the protective film must have ultraviolet blocking capabilities. The most significant threats to materials come from the UV-A band (315nm-380nm) and UV-B band (280nm-315nm) of sunlight. Adding light stabilizers is an effective method to absorb ultraviolet rays from sunlight, protecting the e-ink and materials from damage.

[0004] Adhesives are required in the preparation of protective films, but thermosetting adhesives need to be cured at 60°C for 24 hours or at 25°C for 7 days. Curing involves the reaction of isocyanate groups with the hydroxyl or carboxyl groups in the main resin, resulting in a tighter cross-linked resin network. This curing process not only prolongs the product preparation cycle but also easily leads to warping issues. Adding light stabilizers to UV-curable adhesives can solve the problem of UV-induced damage to electronic paper and materials, as well as the long curing cycle and warping problems associated with the process.

[0005] Adding UV400 light stabilizer can achieve the above purpose, but as the proportion of addition increases, the light stabilizer is prone to precipitation from the molecular network of the main resin. Under conditions of high temperature and humidity, or high temperature, the light stabilizer tends to slowly migrate from the molecular chain network to the surface, posing a high risk of precipitation. Summary of the Invention

[0006] To address the problem of light stabilizers leaching from the adhesive layer of a protective film at higher concentrations, this invention provides a light stabilizer and a protective film.

[0007] A modified triazine light stabilizer was added to the adhesive composition. By introducing 2-isocyanate ethyl acrylate into the triazine light stabilizer, this light stabilizer was endowed with the ability to undergo free radical polymerization. Furthermore, it can undergo free radical polymerization with other active components of the photocurable resin, thereby effectively avoiding the problem that existing free light stabilizers are prone to slow precipitation from the photocurable resin under high temperature or high temperature and high humidity conditions.

[0008] The adhesive composition provided by this invention forms an adhesive layer that bonds a moisture barrier film (commercially available i-components, TBF1016) and an anti-glare film (commercially available DAICL, AG08) together. The light stabilizer in the adhesive layer is chemically bonded to the main resin and will not leach from the adhesive layer, thus solving the problem of existing light stabilizers easily leaching from the adhesive layer. Simultaneously, it meets the UV cutoff requirements of the product. The protective film provided by this invention has similar moisture barrier and anti-glare capabilities to existing protective films, but the light stabilizer does not leach from the adhesive layer, and it meets the UV cutoff requirements of the product while also solving the warpage problem.

[0009] To solve the above problems, the present invention adopts the following technical solution.

[0010] This invention provides a light stabilizer having reactive functional groups.

[0011] Furthermore, the reactive functional group is a free radical polymeric group. Furthermore, the reactive functional group is a vinyl group.

[0012] This invention provides a light stabilizer having free radical polymeric groups.

[0013] This invention provides a light stabilizer obtained by reacting 2-isocyanate ethyl acrylate with 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol. This light stabilizer is also called a modified light stabilizer. The light stabilizer utilizes 2-isocyanate ethyl acrylate as a modifier for 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol. The amount of 2-isocyanate ethyl acrylate is greater than the amount of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol to ensure sufficient reaction of the latter. 2-isocyanate ethyl acrylate reacts with 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol in a solvent. The solvent is phenoxybenzyl acrylate (PBA), which acts as both a diluent and a solvent. The "-NCO" group in the isocyanate reacts with the phenolic hydroxyl group "-OH" in 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol in a synthetic reaction. After the reaction, the light stabilizer has a free radical polymerization group (-CH=CH2).

[0014] The following is a method for preparing a UV-curable modified light stabilizer monomer by synthesizing 2-isocyanate ethyl acrylate and 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol: (1) Weigh m1 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a single-necked flask containing V1 ml of phenoxybenzyl acrylate PBA, and stir until fully dissolved; (2) Weigh m2 grams of 2-isocyanate ethyl acrylate (commercially available Showa Chemical AOI-VM, 96% purity) and add it to the above adhesive solution; (3) After all the ingredients have been added, the solution is kept at 60°C for about 1 hour, and the reaction progress is detected by FTIR spectroscopy. (4) With the extension of reaction time, the characteristic infrared peak (2273 cm⁻¹) corresponding to the NCO functional group increases. -1 The intensity gradually decreased, indicating that the isocyanate had successfully reacted with the phenolic hydroxyl group of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol to synthesize a reactive modified light stabilizer and its solution. (5) Generally, it is preferred that the amount of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol is less than the amount of 2-isocyanate ethyl acrylate, i.e. (m1×98% / 341) mol < (m2×96% / 141) mol, so as to ensure that the proportion of free triazine derivative is low enough.

[0015] Modified light stabilizer monomers with UV-curable properties were prepared using the above method.

[0016] In this invention, the synthetic route and molecular structure of the modified light stabilizer synthesized using 2-isocyanate ethyl acrylate and 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol are as follows:

[0017] Compared to free light stabilizers, modified light stabilizer monomers can serve as active components in photocurable resins. Through the vinyl groups, they can undergo free radical polymerization reactions with other vinyl-containing monomers or oligomers in the photocurable resins, thereby effectively suppressing the risk of light stabilizers precipitating under harsh reliability conditions (such as high temperature and high humidity).

[0018] The adhesive composition provided by the present invention includes a photocurable resin and a light stabilizer provided by the present invention, wherein the amount of light stabilizer added is 0.9-2.8 wt% of the photocurable resin.

[0019] The present invention provides a protective film, which includes, from top to bottom, an anti-glare film, an adhesive layer and a barrier film.

[0020] This invention provides a protective film, which consists of an anti-glare film, an adhesive layer, and a barrier film from top to bottom.

[0021] The adhesive layer comprises a photocurable resin and a light stabilizer provided by this invention. The photocurable resin is an acrylic photocurable resin.

[0022] The adhesive layer is formed from an adhesive composition comprising acrylates, a photoinitiator, and the aforementioned modified light stabilizer. The acrylates include monofunctional, difunctional, and trifunctional acrylates.

[0023] The adhesive layer is formed from an adhesive composition comprising a diacrylate, a photoinitiator, and the aforementioned modified light stabilizer.

[0024] The adhesive layer is formed by an adhesive composition comprising 30 (ethoxy) bisphenol A diacrylate, 10 (ethoxy) bisphenol fluorene diacrylate, photoinitiator TPO, and the above-mentioned modified light stabilizer.

[0025] The adhesive composition comprises 10 grams of 30(ethoxy)bisphenol A diacrylate, 10 grams of 10(ethoxy)bisphenol fluorene diacrylate, 1 gram of photoinitiator TPO, and 0.2-0.6 grams of the above-mentioned modified light stabilizer. The modified light stabilizer may be 0.2 grams, 0.3 grams, 0.4 grams, 0.5 grams, or 0.6 grams.

[0026] The light stabilizer is obtained by reacting 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol with 2-isocyanate ethyl acrylate.

[0027] The light stabilizer was obtained by reacting 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and 2-isocyanate ethyl acrylate in phenoxybenzyl acrylate PBA.

[0028] The light stabilizer was prepared by reacting 0.133 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and 0.055 g of 2-isocyanate ethyl acrylate in 5 g of phenoxybenzyl acrylate PBA.

[0029] The protective film provided by the present invention comprises, from top to bottom, an anti-glare film (commercially available DAICL, AG08), an adhesive layer, and a barrier film (commercially available i-components, TBF1016).

[0030] The adhesive layer is formed by photocuring an adhesive composition (also known as an adhesive coating liquid). The adhesive composition includes (30-ethoxy)bisphenol A diacrylate, 10-(ethoxy)bisphenol fluorene diacrylate, phenoxybenzyl acrylate (PBA), the photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and the light stabilizer provided in this invention. Phenoxybenzyl acrylate (PBA) serves as a diluent and solvent.

[0031] The steps for preparing the protective film are as follows: (1) Weigh (30 ethoxy) bisphenol A diacrylate, 10 (ethoxy) bisphenol fluorene diacrylate, phenoxybenzyl acrylate PBA, photoinitiator diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and the light stabilizer provided in this invention in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (2) Drop the adhesive composition obtained in the above steps onto the surface of the anti-glare film (commercially available DAICEL, AG08), spread the adhesive composition evenly with a #4 wire rod, cover the evenly coated adhesive composition surface with a barrier film (commercially available i-components, TBF1016), and transfer the film surface to a UV curing device with a curing energy of 500 mJ / cm². 2 After curing, the adhesive composition forms an adhesive layer, resulting in a protective film, which is then subjected to subsequent performance testing.

[0032] The present invention also provides a method for preparing a protective film, the method comprising the following steps: (1) Weigh 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and add it to a beaker containing phenoxybenzyl acrylate PBA. Stir until fully dissolved, then add 2-isocyanate ethyl acrylate and keep warm at 60°C for about 3 hours to synthesize a modified light stabilizer solution with reactive groups. (2) Weigh 30 (ethoxy) bisphenol A diacrylate, 10 (ethoxy) bisphenol fluorene diacrylate, photoinitiator TPO and the above modified light stabilizer and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (3) The adhesive composition obtained in the above steps is dropped onto the surface of the anti-glare film, the adhesive composition is evenly coated, the barrier film is covered on the evenly coated adhesive composition surface, the film surface is transferred to the ultraviolet curing equipment, and after curing, the adhesive composition forms an adhesive layer, thus obtaining the protective film of the present invention.

[0033] Furthermore, the method includes the following steps: (1) Weigh 0.133 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 5 g of phenoxybenzyl acrylate PBA. Stir until fully dissolved, then add 0.055 g of 2-isocyanate ethyl acrylate (commercially available Showa Chemical AOI-VM, 96% purity). Keep the mixture at 60°C for about 3 hours and detect the reaction progress by FTIR spectroscopy. As the reaction time increases, the characteristic infrared peak corresponding to the NCO functional group (2273 cm⁻¹) increases. -1 The strength gradually decreased to a stable level, indicating that 2-isocyanate ethyl acrylate had successfully reacted with the phenolic hydroxyl group of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol to synthesize a modified light stabilizer adhesive with reactive groups. (2) Weigh 10g of 30 (ethoxy) bisphenol A diacrylate, 10g of 10 (ethoxy) bisphenol fluorene diacrylate, 1g of photoinitiator TPO and 0.2g of the above modified light stabilizer in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (3) Drop the adhesive composition obtained in the above steps onto the surface of the anti-glare film (commercially available DAICEL, AG08), spread the adhesive composition evenly with a #4 wire rod, cover the surface of the evenly coated adhesive composition with a barrier film (commercially available i-components, TBF1016), and transfer the film surface to a UV curing device with a curing energy of 500 mJ / cm². 2 After curing, the adhesive composition forms an adhesive layer, resulting in the protective film of the present invention, which is then subjected to subsequent performance testing.

[0034] In the technical solution provided by this invention, the modified light stabilizer is modified with free radical polymeric groups, forming a chemical bond with the photocurable resin. Unlike traditional physical mixing methods or the less active secondary alcohol groups in UV400, the modified light stabilizer with modified free radical polymeric groups can be chemically bonded to the molecular network of the main resin. Therefore, the light stabilizer in the adhesive layer of the protective film provided by this invention will not precipitate or migrate. Simultaneously, the light stabilizer in the adhesive layer can absorb ultraviolet light in the UV-A (315nm-380nm) and UV-B (280nm-315nm) ranges, protecting the electronic paper and other materials from damage. Since there is no curing process, the warpage problem is also solved. Attached Figure Description

[0035] like Figure 1 As shown, 04 is the protective film of the present invention, 01 is the anti-glare film (commercially available DAICL, AG08), 02 is the adhesive layer, and 03 is the barrier film (commercially available i-components, TBF1016).

[0036] like Figure 2 The image shown is the FTIR spectrum of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol after the reaction with 2-isocyanate ethyl acrylate. It shows the characteristic infrared peak (2273 cm⁻¹) corresponding to the NCO functional group. -1 ). Detailed Implementation

[0037] To facilitate a better understanding of the structure, functional features, and advantages of this invention, the preferred embodiments of the invention are described in detail below with reference to the accompanying drawings: Example 1

[0038] This invention provides a light stabilizer, a photocurable adhesive composition, and a protective film. The preparation method is as follows: (1) Weigh 0.133 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 5 g of phenoxybenzyl acrylate PBA. Stir until fully dissolved, then add 0.055 g of 2-isocyanate ethyl acrylate (commercially available Showa Chemical AOI-VM, 96% purity). Keep the mixture at 60°C for about 3 hours and detect the reaction progress by FTIR spectroscopy. As the reaction time increases, the characteristic infrared peak corresponding to the NCO functional group (2273 cm⁻¹) increases. -1 The strength gradually decreased to a stable level, indicating that 2-isocyanate ethyl acrylate had successfully reacted with the phenolic hydroxyl group of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol to synthesize a modified light stabilizer adhesive with reactive groups. (2) Weigh 10g of 30 (ethoxy) bisphenol A diacrylate, 10g of 10 (ethoxy) bisphenol fluorene diacrylate, 1g of photoinitiator TPO and 0.2g of the above modified light stabilizer in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (3) Drop the adhesive composition obtained in the above steps onto the surface of the anti-glare film (commercially available DAICEL, AG08), spread the adhesive composition evenly with a #4 wire rod, cover the surface of the evenly coated adhesive composition with a barrier film (commercially available i-components, TBF1016), and transfer the film surface to a UV curing device with a curing energy of 500 mJ / cm². 2 After curing, the adhesive composition forms an adhesive layer, resulting in the protective film of the present invention, which is then subjected to subsequent performance testing.

[0039] Example 2

[0040] This invention provides a light stabilizer, a photocurable adhesive composition, and a protective film. The preparation method is as follows:

[0041] (1) Weigh 0.133 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 5 g of phenoxybenzyl acrylate PBA. Stir until fully dissolved, then add 0.055 g of 2-isocyanate ethyl acrylate (commercially available Showa Chemical AOI-VM, 96% purity) to the above solution. Keep warm at 60°C for about 3 hours, and detect the reaction progress by FTIR spectroscopy; as the reaction time increases, the characteristic infrared peak (2273 cm⁻¹) corresponding to the NCO functional group increases. -1 The strength gradually decreased to a stable level, indicating that 2-isocyanate ethyl acrylate had successfully reacted with the phenolic hydroxyl group of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol to synthesize a reactive modified light stabilizer solution. (2) Weigh 10g of 30 (ethoxy) bisphenol A diacrylate, 10g of 10 (ethoxy) bisphenol fluorene diacrylate, 1g of photoinitiator TPO and 0.3g of the above modified light stabilizer in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (3) Drop the adhesive composition obtained in the above steps onto the surface of the anti-glare film (commercially available DAICEL, AG08), spread the adhesive composition evenly with a #4 wire rod, cover the surface of the evenly coated adhesive composition with a barrier film (commercially available i-components, TBF1016), and transfer the film surface to a UV curing device with a curing energy of 500 mJ / cm². 2 After curing, the protective film of the present invention is obtained, which is then subjected to subsequent performance testing.

[0042] Example 3

[0043] This invention provides a light stabilizer, a photocurable adhesive composition, and a protective film. The preparation method is as follows:

[0044] (1) Weigh 0.133 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 5 g of phenoxybenzyl acrylate PBA. Stir until fully dissolved, then add 0.055 g of 2-isocyanate ethyl acrylate (commercially available Showa Chemical AOI-VM, 96% purity) to the above solution. Keep warm at 60°C for about 3 hours, and detect the reaction progress by FTIR spectroscopy; as the reaction time increases, the characteristic infrared peak (2273 cm⁻¹) corresponding to the NCO functional group increases. -1 The strength gradually decreased to a stable level, indicating that 2-isocyanate ethyl acrylate had successfully reacted with the phenolic hydroxyl group of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol to synthesize a reactive modified light stabilizer solution. (2) Weigh 10g of 30 (ethoxy) bisphenol A diacrylate, 10g of 10 (ethoxy) bisphenol fluorene diacrylate, 1g of photoinitiator TPO and 0.4g of the above modified light stabilizer in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (3) Drop the adhesive composition obtained in the above steps onto the surface of the anti-glare film (commercially available DAICEL, AG08), spread the adhesive composition evenly with a #4 wire rod, cover the surface of the evenly coated adhesive composition with a barrier film (commercially available i-components, TBF1016), and transfer the film surface to a UV curing device with a curing energy of 500 mJ / cm². 2 After curing, the protective film of the present invention is obtained, which is then subjected to subsequent performance testing.

[0045] Example 4

[0046] This invention provides a light stabilizer, a photocurable adhesive composition, and a protective film. The preparation method is as follows:

[0047] (1) Weigh 0.133 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 5 g of phenoxybenzyl acrylate PBA. Stir until fully dissolved, then add 0.055 g of 2-isocyanate ethyl acrylate (commercially available Showa Chemical AOI-VM, 96% purity) to the above solution. Keep the above solution at 60°C for about 3 hours, and detect the reaction progress by FTIR spectroscopy; as the reaction time increases, the characteristic infrared peak (2273 cm⁻¹) corresponding to the NCO functional group increases. -1 The strength gradually decreased to a stable level, indicating that 2-isocyanate ethyl acrylate had successfully reacted with the phenolic hydroxyl group of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol to synthesize a reactive modified light stabilizer solution. (2) Weigh 10g of 30 (ethoxy) bisphenol A diacrylate, 10g of 10 (ethoxy) bisphenol fluorene diacrylate, 1g of photoinitiator TPO and 0.5g of the above modified light stabilizer in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (3) Drop the adhesive composition obtained in the above steps onto the surface of the anti-glare film (commercially available DAICEL, AG08), spread the adhesive composition evenly with a #4 wire rod, cover the surface of the evenly coated adhesive composition with a barrier film (commercially available i-components, TBF1016), and transfer the film surface to a UV curing device with a curing energy of 500 mJ / cm². 2 After curing, the protective film of the present invention is obtained, which is then subjected to subsequent performance testing. Example 5

[0048] This invention provides a light stabilizer, a photocurable adhesive composition, and a protective film. The preparation method is as follows: (1) Weigh 0.133 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 5 g of phenoxybenzyl acrylate PBA. Stir until fully dissolved, then add 0.055 g of 2-isocyanate ethyl acrylate (commercially available Showa Chemical AOI-VM, 96% purity) to the above solution. Keep the above solution at 60°C for about 3 hours, and detect the reaction progress by FTIR spectroscopy; as the reaction time increases, the characteristic infrared peak (2273 cm⁻¹) corresponding to the NCO functional group increases. -1 The strength gradually decreased to a stable level, indicating that 2-isocyanate ethyl acrylate had successfully reacted with the phenolic hydroxyl group of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol to synthesize a reactive modified light stabilizer solution. (2) Weigh 10g of 30 (ethoxy) bisphenol A diacrylate, 10g of 10 (ethoxy) bisphenol fluorene diacrylate, 1g of photoinitiator TPO and 0.6g of the above modified light stabilizer in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (3) Drop the adhesive composition obtained in the above steps onto the surface of the anti-glare film (commercially available DAICEL, AG08), spread the adhesive composition evenly with a #4 wire rod, cover the surface of the evenly coated adhesive composition with a barrier film (commercially available i-components, TBF1016), and transfer the film surface to a UV curing device with a curing energy of 500 mJ / cm². 2 After curing, the protective film of the present invention is obtained, which is then subjected to subsequent performance testing.

[0049] Comparative Example 1 A photocurable adhesive composition and a protective film are provided. The preparation method is as follows: (1) Weigh 10g of 30 (ethoxy) bisphenol A diacrylate, 10g of 10 (ethoxy) bisphenol fluorene diacrylate and 1g of photoinitiator TPO in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (2) Drop the adhesive composition obtained in the above steps onto the surface of the anti-glare film (commercially available DAICEL, AG08), spread the adhesive composition evenly with a #4 wire rod, cover the evenly coated adhesive composition surface with a barrier film (commercially available i-components, TBF1016), and transfer the film surface to a UV curing device with a curing energy of 500 mJ / cm². 2 After curing, a protective film is obtained, which will be tested for performance later.

[0050] Comparative Example 2 A photocurable adhesive composition and a protective film are provided. The preparation method is as follows: (1) Weigh 10g of 30 (ethoxy) bisphenol A diacrylate, 10g of 10 (ethoxy) bisphenol fluorene diacrylate, 1g of photoinitiator TPO and 0.2g of light stabilizer (commercially available BASF Tinuvin UV400) in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (2) Drop the adhesive composition obtained in the above steps onto the surface of the anti-glare film (commercially available DAICEL, AG08), spread the adhesive composition evenly with a #4 wire rod, cover the evenly coated adhesive composition surface with a barrier film (commercially available i-components, TBF1016), and transfer the film surface to a UV curing device with a curing energy of 500 mJ / cm². 2 After curing, a protective film is obtained, which will be tested for performance later.

[0051] Comparative Example 3 A photocurable adhesive composition and a protective film are provided. The preparation method is as follows: (1) Weigh 10g of 30 (ethoxy) bisphenol A diacrylate, 10g of 10 (ethoxy) bisphenol fluorene diacrylate, 1g of photoinitiator TPO and 0.6g of light stabilizer (commercially available BASF Tinuvin UV400) in sequence and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (2) The adhesive composition obtained in the above steps is dropped onto the surface of the anti-glare film (commercially available DAICEL, AG08). The adhesive composition is evenly coated with a No. 4 wire rod. The barrier film (commercially available i-components, TBF1016) is covered on the evenly coated adhesive composition surface. The film surface is transferred to a UV curing device with a curing energy of 500mJ / cm2. After curing, a protective film is obtained, which will be tested for subsequent performance.

[0052] Comparative Example 4 A thermosetting adhesive composition and a protective film are provided. The preparation method is as follows: Weigh 15 g of acrylate copolymer (commercially available DIC A807), 0.3 g of isocyanate curing agent (Aekyung Chemical AH-2100), and 0.6 g of light stabilizer solution (commercially available BASF Tinuvin UV400) and add them to a beaker. Add 15 g of ethyl acetate to dilute the adhesive solution and adjust it to a suitable viscosity range for coating. Then stir at 500 rpm / min for 30 minutes to prepare the bonding adhesive coating solution (bonding adhesive layer composition).

[0053] Using a No. 4 wire rod, the above-mentioned adhesive coating solution was applied to the surface of the anti-glare film (commercially available DAICL, AG08). The anti-glare film (commercially available DAICL, AG08) coated with the adhesive coating solution was placed in an 85°C oven for 3 minutes and then removed. A barrier film (commercially available i-components, TBF1016) was placed on the side of the anti-glare film (commercially available DAICL, AG08) with the adhesive coating and placed in the middle of the bonding roller. The bonding roller pressure was 0.5 MPa, and the film was passed through the bonding roller at a uniform speed. The laminated film was then placed in a 60°C oven and allowed to stand for 24 hours to cure, thus preparing a protective film for subsequent performance testing.

[0054] The finished products provided in the examples and comparative examples were tested for performance according to the following standards: Precipitation test of modified light stabilizer in adhesive layer: The finished films prepared above were placed in high temperature and high humidity test chambers with conditions of 65°C and 95%RH and 85°C and 85%RH respectively. After 500 hours, the precipitation on the surface of the film was observed and divided into "no precipitation", "slight precipitation" and "severe precipitation", among which "no precipitation" is the qualified product of this invention.

[0055] FTIR testing of modified light stabilizer: The reacted modified light stabilizer solution was coated onto a KBr film and then placed in a 60°C oven for solvent surface drying. Subsequently, it was characterized by infrared spectroscopy using a Nicolet iS 5 infrared spectrometer, with the intensity of the 2273 cm⁻¹ absorption peak being monitored to characterize the reaction of the isocyanate group.

[0056] 200nm-780nm transmittance test: Optical tests were performed on the finished film using an Agilent Cary 5000 UV-Vis-NIR spectrophotometer according to ASTM D1003 standard. The transmittance in the visible light band was the average transmittance from 381nm to 780nm. A visible light transmittance greater than 88%, transmittance less than 1% at 280nm and 360nm, and transmittance less than 6% at 380nm constitute a qualified product of this invention.

[0057] Warpage Test: Cut the sample to size B7 (91mm × 128mm) using a utility knife. Place the film naturally on the marble countertop with the anti-glare film (commercially available DAICEL, AG08) facing upwards. Measure the distance between the four corners of the B7 film and the marble countertop using a steel ruler. The maximum distance among the four corners is the warpage value of the B7 sample. A distance of 2 mm or less is considered a qualified product according to this invention.

[0058] Table 1. Performance test results of the finished products provided in the examples and comparative examples.

[0059] As can be seen from the test results of the above examples and comparative examples, Comparative Example 1 did not add any light stabilizer, so it did not absorb any UVA band (315nm-380nm). The low transmittance at 280nm is due to the absorption of this wavelength by the PET substrate.

[0060] Both Comparative Examples 2 and 3 used commercially available light stabilizers. In Comparative Example 2, due to the relatively small amount added, the transmittance at 380 nm was greater than 6%, which did not meet the performance requirements of the protective film product. Therefore, the amount of light stabilizer was increased in Comparative Example 3, resulting in a transmittance at 380 nm of less than 6%, meeting the performance requirements of the protective film product. However, due to the increased amount, "slight precipitation" occurred under both 65℃ / 95% RH and 85℃ / 85% RH conditions. This is because the light stabilizer in the adhesive layer is freely dispersed in the resin mesh without chemical bonding. Under the driving force of high temperature and high humidity, the light stabilizer molecules agglomerate together, and when the amount accumulates to a certain level, it precipitates in the resin surface. The precipitation of the light stabilizer also leads to a decrease in visible light transmittance.

[0061] Examples 1-5 used the modified light stabilizer of the present invention. Since the light stabilizer of the present invention contains free radical polymer groups, it chemically bonds with acrylic resin under the action of free radicals, and can exist stably in the cross-linked resin network. It does not precipitate under high temperature and high humidity conditions, and can meet the requirements of ultraviolet cutoff. The warpage problem is also solved.

[0062] Example 5 shows a more significant cutoff effect in the UVA band, a lower transmittance at 380nm, and "no precipitation" under high temperature and high humidity conditions, with warpage values ​​meeting the standards. It is the optimal implementation scheme of the present invention.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. All equivalent variations and modifications made based on the content of the present invention are covered within the patent scope of the present invention.

Claims

1. A protective film, characterized in that, The protective film comprises, from top to bottom, an anti-glare film, an adhesive layer, and a barrier film; the adhesive layer is formed by an adhesive composition comprising 30(ethoxy)bisphenol A diacrylate, 10(ethoxy)bisphenol fluorene diacrylate, a photoinitiator, and a light stabilizer; the light stabilizer is obtained by reacting 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and 2-isocyanate ethyl acrylate.

2. The protective film according to claim 1, characterized in that, The photoinitiator is TPO.

3. The protective film according to claim 1 or 2, characterized in that, The light stabilizer was obtained by reacting 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and 2-isocyanate ethyl acrylate in phenoxybenzyl acrylate.

4. The protective film according to claim 1 or 2, characterized in that, The light stabilizer was prepared by reacting 0.133 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and 0.055 g of 2-isocyanate ethyl acrylate in 5 g of phenoxybenzyl acrylate PBA.

5. A method for preparing a protective film according to any one of claims 1-4, characterized in that, The method includes the following steps: (1) Weigh 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and add it to a beaker containing phenoxybenzyl acrylate PBA. Stir until fully dissolved, then add 2-isocyanate ethyl acrylate and keep warm at 60°C for 3 hours to synthesize a light stabilizer with reactive groups. (2) Weigh 30 (ethoxy) bisphenol A diacrylate, 10 (ethoxy) bisphenol fluorene diacrylate, photoinitiator TPO and the above light stabilizer and add them to a glass beaker. Stir at 1000 rpm for 2 hours and let stand to defoam for 1 hour. (3) The adhesive composition obtained in the above steps is dropped onto the surface of the anti-glare film, the adhesive composition is evenly coated, the barrier film is covered on the evenly coated adhesive composition surface, the film surface is transferred to the ultraviolet curing equipment, and after curing, the adhesive composition forms an adhesive layer to obtain a protective film.

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