A protective film

Abstract

This invention relates to the field of thin-film optics, and particularly to a protective film. To address the problem of light stabilizer precipitation at high concentrations, this invention provides a protective film. The protective film sequentially comprises an anti-glare film, an adhesive layer, and a barrier film; the adhesive layer is formed from an adhesive layer coating liquid; the adhesive layer coating liquid comprises an acrylate copolymer, a light stabilizer, an isocyanate curing agent, and a solvent; the light stabilizer has isocyanate groups. The light stabilizer in the adhesive layer of the protective film will not precipitate or migrate.

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 UV-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 to the protective film is an effective method. The protective film absorbs ultraviolet rays from sunlight, protecting the e-ink and materials from damage. For example, adding UV400 light stabilizer can achieve this purpose. Although the secondary alcohols on the side chains of this type of light stabilizer have some reactivity, they are not as reactive as primary alcohols. With increasing addition ratios, unreacted portions of the light stabilizer are prone to precipitate from the molecular network of the main resin. Under conditions of high temperature and humidity, or high temperature, the light stabilizer in existing protective films may slowly migrate from the molecular chain network to the surface, posing a high risk of precipitation and thus reducing the performance of the product itself. Summary of the Invention

[0004] While meeting UV cutoff requirements, addressing the issue of light stabilizer leaching at higher concentrations is crucial. This invention provides a light stabilizer, an adhesive composition, and a protective film. The adhesive composition includes a main resin and the light stabilizer of this invention; the protective film comprises an adhesive layer formed from the adhesive composition provided by this invention. The light stabilizer in this protective film will not leach from the adhesive layer.

[0005] The light stabilizer provided by this invention has a reactive functional group, which is an isocyanate group (-NCO). 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 precipitate from the adhesive layer, solving the problem of existing light stabilizers easily precipitating from the adhesive layer, while still meeting 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 precipitate from the adhesive layer and still meets the UV cutoff requirements of the product.

[0006] To solve the above problems, the present invention adopts the following technical solution.

[0007] The present invention provides a light stabilizer having reactive functional groups.

[0008] Furthermore, the reactive functional group is an isocyanate group (-NCO).

[0009] This invention provides a light stabilizer having an isocyanate group (-NCO).

[0010] This invention provides a light stabilizer obtained by reacting isocyanate with 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol. This light stabilizer is also referred to as a modified light stabilizer. The light stabilizer utilizes isocyanate modified with 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol.

[0011] A portion of 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 possesses an active isocyanate group (-NCO).

[0012] Because isocyanates have multiple functional groups, such as hexamethylene diisocyanate, one of the isocyanate groups reacts with triazine, leaving an unreacted isocyanate group (-NCO).

[0013] The isocyanate group is modified on the host of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol, thereby enabling 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol to form bonds with hydroxyl or carboxyl groups on acrylate copolymers.

[0014] The modified light stabilizer is obtained by reacting 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and hexamethylene diisocyanate in an organic solvent. The organic solvent includes ethyl acetate and toluene.

[0015] The preparation method of the modified light stabilizer is as follows:

[0016] Dissolve 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol in toluene, and dissolve isocyanate in ethyl acetate. Add the toluene solution of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol dropwise to the ethyl acetate solution of isocyanate, and incubate at 60°C for approximately 1-3 hours. The resulting solution is called the modified light stabilizer solution. The light stabilizer in the solution is the product of the reaction between 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and isocyanate, containing isocyanate groups (-NCO). The amount of phenolic hydroxyl groups is less than the amount of isocyanate groups.

[0017] The present invention also provides a method for preparing the above-mentioned light stabilizer, a method for preparing a modified light stabilizer by synthesizing isocyanate and 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol, comprising the following steps:

[0018] (1) Weigh m1g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing V1ml of toluene. After dissolving completely, prepare a clear solution.

[0019] (2) Weigh m2 g of isocyanate (w1% solid content, w2% NCO content, functionality n) and add it to a single-necked flask containing V2 ml of ethyl acetate. Then add the solution obtained in step (1) dropwise to the single-necked flask.

[0020] (3) After all the ingredients are added, the solution is kept at 60°C for about 1-3 hours, and the reaction progress is detected by FTIR spectroscopy.

[0021] (4) As the reaction time increases, the intensity of the characteristic infrared peak (2273 cm-1) corresponding to the NCO functional group gradually decreases, indicating that the isocyanate has 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.

[0022] (5) Generally, it is preferred that the amount of phenolic hydroxyl group is less than the amount of isocyanate group (NCO-);

[0023] (m1×98% / 341)mol<(m2×w1%×w2% / 42)mol;

[0024] (6) When adding curing agent later, this part of isocyanate needs to be considered to avoid adding too much isocyanate curing agent, which will affect the curing effect of the bonding adhesive layer.

[0025] Preferably, the isocyanate can be a trimer obtained by reacting trimethylolpropane with a difunctional isocyanate compound or by self-polymerization. The isocyanate can be selected from one or more of aliphatic isocyanate compounds, alicyclic isocyanate compounds, or aromatic isocyanate compounds.

[0026] The aliphatic isocyanate compounds may be selected from one or more of hexamethylene diisocyanate, trimethylhexyl diisocyanate, pentamethylene diisocyanate, or 1,2-propylidene diisocyanate. The alicyclic isocyanate compounds may be selected from one or more of isophorone diisocyanate, methylene bis(4-cyclohexyl) isocyanate, 1,4-cyclohexane diisocyanate, or methyl-2,6-cyclohexane diisocyanate. The aromatic isocyanate compounds may be selected from one or more of 1,3-toluene diisocyanate, 2,6-toluyl diisocyanate, 2,4-toluyl diisocyanate, 4,4'-diphenylmethane diisocyanate, or xylene diisocyanate.

[0027] Furthermore, the isocyanate is a diisocyanate.

[0028] Furthermore, the isocyanate is hexamethylene diisocyanate.

[0029] When the isocyanate is hexamethylene diisocyanate, the modified light stabilizer synthesized with 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol has the following structural formula:

[0030]

[0031] The unreacted "-NCO" groups in the modified light stabilizer can react with the hydroxyl or carboxyl groups in the acrylate copolymer in the adhesive layer composition, allowing the modified light stabilizer to be chemically bonded to the acrylate copolymer (i.e., the main resin) and preventing it from precipitating out of the adhesive layer.

[0032] The present invention provides an adhesive layer composition comprising the light stabilizer provided by the present invention.

[0033] An adhesive layer composition includes an acrylate copolymer, hexamethylene diisocyanate, and a light stabilizer provided by the present invention. The acrylate copolymer is the main resin, which disperses the light stabilizer and bonds the moisture barrier film (commercially available i-components, TBF1016) and the anti-glare film (commercially available DAICEL, AG08) together.

[0034] Furthermore, the present invention provides an adhesive layer composition comprising (meth)acrylate copolymer, hexamethylene diisocyanate, ethyl acetate, and a modified light stabilizer solution; the modified light stabilizer solution is a solution obtained by reacting 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and hexamethylene diisocyanate in an organic solvent. The organic solvent includes ethyl acetate and toluene.

[0035] The adhesive layer composition provided by the present invention comprises the following components in weight percentage: 25.12% (meth)acrylate copolymer, 2.13% hexamethylene diisocyanate, 17.45% ethyl acetate, and a modified light stabilizer solution; the modified light stabilizer solution is a solution obtained by reacting 0.20%-0.60% 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and 0.85% hexamethylene diisocyanate in 38.33% ethyl acetate and 15.52%-15.92% toluene.

[0036] The copolymer functional monomers of the (meth)acrylate copolymer are preferably derived from (meth)acrylate monomers containing hydroxyl or carboxyl groups. The hydroxyl-containing (meth)acrylate monomers may be selected from one or a combination of at least two of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, or 6-hydroxyhexyl (meth)acrylate. The carboxyl-containing (meth)acrylate monomers are commonly used vinyl-containing unsaturated carboxylic acids, including one or a combination of at least two of acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid.

[0037] The isocyanate curing agent is selected from the reaction of trimethylolpropane with a difunctional isocyanate compound. Such difunctional isocyanates can be one or more of aliphatic isocyanates, alicyclic isocyanates, or aromatic isocyanates.

[0038] Aliphatic isocyanates may be selected from one or more of hexamethylene diisocyanate, trimethylhexyl diisocyanate, pentamethylene diisocyanate, or 1,2-propylidene diisocyanate. Alicyclic isocyanates may be selected from one or more of isophorone diisocyanate, methylene bis(4-cyclohexyl) isocyanate, 1,4-cyclohexane diisocyanate, or methyl-2,6-cyclohexane diisocyanate. Aromatic isocyanates may be selected from one or more of 1,3-toluene diisocyanate, 2,6-toluyl diisocyanate, 2,4-toluyl diisocyanate, 4,4'-diphenylmethane diisocyanate, or xylene diisocyanate.

[0039] The protective film provided by the present invention comprises, from top to bottom, an anti-glare film, an adhesive layer, and a barrier film.

[0040] Furthermore, the protective film consists of, from top to bottom, an anti-glare film, an adhesive layer, and a barrier film.

[0041] Furthermore, the anti-glare film can be commercially available DAICL or AG08. The barrier film can be commercially available i-components or TBF1016.

[0042] The present invention provides a protective film, comprising, in sequence, an anti-glare film, an adhesive layer, and a barrier film; the adhesive layer is formed by an adhesive layer coating liquid.

[0043] Furthermore, the adhesive coating liquid includes an acrylate copolymer, a light stabilizer, an isocyanate curing agent, and a solvent.

[0044] Furthermore, the adhesive coating liquid comprises 15.072 grams of acrylate copolymer, light stabilizer, 1.278 grams of isocyanate curing agent, and 15 grams of ethyl acetate solvent.

[0045] The light stabilizer is the light stabilizer provided by the present invention.

[0046] Furthermore, the light stabilizer is obtained by reacting 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol with an isocyanate. The isocyanate has a functionality ≥2.

[0047] Furthermore, the light stabilizer is obtained by reacting 0.120 g to 0.360 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol with 0.510 g of hexamethylene diisocyanate. The amount of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol can be 0.120 g, 0.180 g, 0.240 g, 0.300 g, or 0.360 g.

[0048] Furthermore, the solid content of hexamethylene diisocyanate is 100%, and the NCO content is 21.25%.

[0049] On the other hand, the invention also provides a method for preparing a protective film, the method comprising the following steps:

[0050] 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol was added to toluene and stirred until fully dissolved. Then, it was added dropwise to an ethyl acetate solution containing hexamethylene diisocyanate. After all the solution was added, the solution was kept at 60°C for about 1-3 hours to prepare a solution of the modified light stabilizer.

[0051] Subsequently, the acrylate copolymer, isocyanate curing agent, and the above-mentioned modified light stabilizer solution were added to ethyl acetate to prepare the bonding adhesive coating liquid (i.e., bonding adhesive coating liquid, also known as bonding adhesive composition).

[0052] The above-mentioned adhesive coating liquid is applied to the surface of the anti-glare film. The anti-glare film coated with the adhesive coating liquid is dried, and the adhesive coating liquid forms an adhesive coating layer. The barrier film is placed on the side of the anti-glare film with the adhesive coating layer, pressed and dried to obtain the finished protective film.

[0053] Furthermore, the present invention also provides a method for preparing a protective film, the method comprising the following steps:

[0054] Weigh 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing toluene. Stir until fully dissolved, then add it dropwise to a single-necked flask containing an ethyl acetate solution of hexamethylene diisocyanate (commercially available Aekyung Chemical AH-2100, 100% solids, 21.25% NCO). After all the solution has been added, incubate the solution at 60°C for about 1-3 hours to prepare a solution of the modified light stabilizer.

[0055] Subsequently, the acrylate copolymer (commercially available DICA807), isocyanate curing agent, and the above-mentioned modified light stabilizer solution were weighed and added to a beaker. Ethyl acetate was added to dilute the adhesive solution and adjust it to a suitable viscosity range for coating. Then, the mixture was stirred at 500 rpm / min for 30 minutes to prepare the bonding adhesive coating solution (bonding adhesive composition).

[0056] The adhesive coating solution is applied to the surface of the anti-glare film. The anti-glare film coated with the adhesive coating solution is placed in an 85°C oven for 3 minutes and then removed. A barrier film is placed over the side of the anti-glare film with the adhesive coating, and then placed between the bonding rollers. The bonding rollers apply a pressure of 0.5 MPa, and the film passes through the bonding rollers at a uniform speed. The laminated film is then placed in a 60°C oven and left to stand for 24 hours to obtain the finished protective film.

[0057] In the technical solution provided by this invention, the modified light stabilizer is modified with isocyanate groups (-NCO). These isocyanate groups (-NCO) have the ability to react with active groups in acrylates (such as hydroxyl and carboxyl groups in acrylic resins). The modified light stabilizer forms chemical bonds with the main resin (acrylate copolymer) through amide bonds, thereby directly participating in the overall reaction. Unlike traditional physical mixing methods or the less active secondary alcohol groups in UV400, the modified light stabilizer with isocyanate groups can be chemically bonded to the molecular network of the main resin through amide bonds. Therefore, the modified light stabilizer in the adhesive layer of the protective film (i.e., the light stabilizer 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. Attached Figure Description

[0058] 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).

[0059] like Figure 2 The image shown is the FTIR spectrum of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol after the reaction with hexamethylene diisocyanate. It shows the characteristic infrared peak (2273 cm⁻¹) corresponding to the NCO functional group. -1 This indicates that after the reaction, the light stabilizer carries an isocyanate group (-NCO). Detailed Implementation

[0060] To better understand the structure, functional features, and advantages of the present invention, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings:

[0061] Example 1

[0062] This invention provides a light stabilizer, an adhesive layer composition, and a protective film. The preparation method is as follows:

[0063] Weigh 0.120 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 10 ml of toluene. Stir until fully dissolved, then add it dropwise to a 100 ml single-necked flask containing 25 ml of ethyl acetate solution of 0.510 g of hexamethylene diisocyanate (commercially available Aekyung Chemical AH-2100, 100% solids, 21.25% NCO). After all the solution has been added, incubate the solution at 60 °C for about 1-3 hours to prepare a solution of the modified light stabilizer.

[0064] Subsequently, 15.072 g of acrylate copolymer (commercially available DICA807), 1.278 g of isocyanate curing agent (Aekyung Chemical AH-2100), and the above-mentioned modified light stabilizer solution were weighed and added to a beaker. 15 g of ethyl acetate was added to dilute the adhesive solution and adjust it to a suitable viscosity range for coating. The solution was then stirred at 500 rpm / min for 30 minutes to prepare the bonding adhesive coating solution (bonding adhesive composition).

[0065] Using a No. 4 wire rod, the above-mentioned adhesive coating solution was applied to the surface of a 100μm thick 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℃ 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 0.5MPa, and the film was passed through the bonding roller at a uniform speed. The laminated film was then placed in a 60℃ oven and left to stand for 24 hours to obtain the finished protective film, which was used for subsequent performance testing.

[0066] Example 2

[0067] This invention provides a light stabilizer, an adhesive layer composition, and a protective film. The preparation method is as follows:

[0068] Weigh 0.180 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 10 ml of toluene. Stir until fully dissolved, then add it dropwise to a 100 ml single-necked flask containing 25 ml of ethyl acetate solution of 0.510 g of hexamethylene diisocyanate (commercially available Aekyung Chemical AH-2100, 100% solids, 21.25% NCO). After all the solution has been added, incubate the solution at 60 °C for about 1-3 hours to prepare a solution of the modified light stabilizer.

[0069] Subsequently, 15.072 g of acrylate copolymer (commercially available DICA807), 1.278 g of isocyanate curing agent (Aekyung Chemical AH-2100), and the above-mentioned modified light stabilizer solution were weighed and added to a beaker. 15 g of ethyl acetate was added to dilute the adhesive solution and adjust it to a suitable viscosity range for coating. The solution was then stirred at 500 rpm / min for 30 minutes to prepare the bonding adhesive coating solution (bonding adhesive composition).

[0070] Using a No. 4 wire rod, the above-mentioned adhesive coating solution was applied to the surface of a 100μm thick 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℃ 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 0.5MPa, and the film was passed through the bonding roller at a uniform speed. The laminated film was then placed in a 60℃ oven and left to stand for 24 hours to obtain the finished protective film, which was used for subsequent performance testing.

[0071] Example 3

[0072] This invention provides a light stabilizer, an adhesive layer composition, and a protective film. The preparation method is as follows:

[0073] Weigh 0.240 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 10 ml of toluene. Stir until fully dissolved, then add it dropwise to a 100 ml single-necked flask containing 25 ml of ethyl acetate solution of 0.510 g of hexamethylene diisocyanate (commercially available Aekyung Chemical AH-2100, 100% solids, 21.25% NCO). After all the solution has been added, incubate the solution at 60 °C for about 1-3 hours to prepare a solution of the modified light stabilizer.

[0074] Subsequently, 15.072 g of acrylate copolymer (commercially available DICA807), 1.278 g of isocyanate curing agent (Aekyung Chemical AH-2100), and the above-mentioned modified light stabilizer solution were weighed and added to a beaker. 15 g of ethyl acetate was added to dilute the adhesive solution and adjust it to a suitable viscosity range for coating. The solution was then stirred at 500 rpm / min for 30 minutes to prepare the bonding adhesive coating solution (bonding adhesive composition).

[0075] Using a No. 4 wire rod, the above-mentioned adhesive coating solution was applied to the surface of a 100μm thick 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℃ 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 0.5MPa, and the film was passed through the bonding roller at a uniform speed. The laminated film was then placed in a 60℃ oven and left to stand for 24 hours to obtain the finished protective film, which was used for subsequent performance testing.

[0076] Example 4

[0077] This invention provides a light stabilizer, an adhesive layer composition, and a protective film. The preparation method is as follows:

[0078] Weigh 0.300 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 10 ml of toluene. Stir until fully dissolved, then add it dropwise to a 100 ml single-necked flask containing 25 ml of ethyl acetate solution of 0.510 g of hexamethylene diisocyanate (commercially available Aekyung Chemical AH-2100, 100% solids, 21.25% NCO). After all the solution has been added, incubate the solution at 60 °C for about 1-3 hours to prepare a solution of the modified light stabilizer.

[0079] Subsequently, 15.072 g of acrylate copolymer (commercially available DICA807), 1.278 g of isocyanate curing agent (Aekyung Chemical AH-2100), and the above-mentioned modified light stabilizer solution were weighed and added to a beaker. 15 g of ethyl acetate was added to dilute the adhesive solution and adjust it to a suitable viscosity range for coating. The solution was then stirred at 500 rpm / min for 30 minutes to prepare the bonding adhesive coating solution (bonding adhesive composition).

[0080] Using a No. 4 wire rod, the above-mentioned adhesive coating solution was applied to the surface of a 100μm thick 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℃ 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 0.5MPa, and the film was passed through the bonding roller at a uniform speed. The laminated film was then placed in a 60℃ oven and left to stand for 24 hours to obtain the finished protective film, which was used for subsequent performance testing.

[0081] Example 5

[0082] This invention provides a light stabilizer, an adhesive layer composition, and a protective film. The preparation method is as follows:

[0083] Weigh 0.360 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol (commercially available TCI, 98% purity) and add it to a beaker containing 10 ml of toluene. Stir until fully dissolved, then add it dropwise to a 100 ml single-necked flask containing 25 ml of ethyl acetate solution of 0.510 g of hexamethylene diisocyanate (commercially available Aekyung Chemical AH-2100, 100% solids, 21.25% NCO). After all the solution has been added, incubate the solution at 60 °C for about 1-3 hours to prepare a solution of the modified light stabilizer.

[0084] Subsequently, 15.072 g of acrylate copolymer (commercially available DICA807), 1.278 g of isocyanate curing agent (Aekyung Chemical AH-2100), and the above-mentioned modified light stabilizer solution were weighed and added to a beaker. 15 g of ethyl acetate was added to dilute the adhesive solution and adjust it to a suitable viscosity range for coating. The solution was then stirred at 500 rpm / min for 30 minutes to prepare the bonding adhesive coating solution (bonding adhesive composition).

[0085] Using a No. 4 wire rod, the above-mentioned adhesive coating solution was applied to the surface of a 100μm thick 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℃ 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 0.5MPa, and the film was passed through the bonding roller at a uniform speed. The laminated film was then placed in a 60℃ oven and left to stand for 24 hours to obtain the finished protective film, which was used for subsequent performance testing.

[0086] Comparative Example 1

[0087] A bonding adhesive layer composition and a protective film are provided. The preparation method is as follows:

[0088] Weigh 15.072 g of acrylate copolymer (commercially available DICA807) and 1.278 g of isocyanate curing agent (Aekyung Chemical AH-2100) and add them to a beaker. Add 15 g of ethyl acetate to dilute the adhesive solution and adjust the viscosity of the adhesive solution to a suitable range for coating. Then stir at 500 rpm / min for 30 minutes to prepare the bonding adhesive coating solution (bonding adhesive composition).

[0089] Using a No. 4 wire rod, the above-mentioned adhesive coating solution was applied to the surface of a 100μm thick 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℃ 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 0.5MPa, and the film was passed through the bonding roller at a uniform speed. The laminated film was then placed in a 60℃ oven and left to stand for 24 hours to obtain the finished protective film, which was used for subsequent performance testing.

[0090] No light stabilizer was added to the bonding adhesive liquid in Comparative Example 1.

[0091] Comparative Example 2

[0092] The adhesive layer composition and protective film provided in Comparative Example 1 are prepared by the following method:

[0093] Weigh 15.072 g of acrylate copolymer (commercially available DICA807), 1.278 g of isocyanate curing agent (Aekyung Chemical AH-2100), and 0.153 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 composition).

[0094] Using a No. 4 wire rod, the above-mentioned adhesive coating solution was applied to the surface of a 100μm thick 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℃ 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 0.5MPa, and the film was passed through the bonding roller at a uniform speed. The laminated film was then placed in a 60℃ oven and left to stand for 24 hours to obtain the finished protective film, which was used for subsequent performance testing.

[0095] The adhesive coating liquid of Comparative Example 2 contains a commercially available light stabilizer.

[0096] Comparative Example 3

[0097] The adhesive layer composition and protective film provided in Comparative Example 1 are prepared by the following method:

[0098] Weigh 15.072 g of acrylate copolymer (commercially available DICA807), 1.278 g of isocyanate curing agent (Aekyung Chemical AH-2100), and 0.459 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 composition).

[0099] Using a No. 4 wire rod, the above-mentioned adhesive coating solution was applied to the surface of a 100μm thick 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℃ 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 0.5MPa, and the film was passed through the bonding roller at a uniform speed. The laminated film was then placed in a 60℃ oven and left to stand for 24 hours to obtain the finished protective film, which was used for subsequent performance testing.

[0100] The adhesive coating liquid of Comparative Example 3 contains a commercially available light stabilizer, and the amount of light stabilizer added is greater than that of Comparative Example 2.

[0101] The finished products provided in the examples and comparative examples were tested for performance according to the following standards:

[0102] Precipitation test of light stabilizer in adhesive layer: The finished film prepared above was placed in a high temperature and high humidity test chamber 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.

[0103] FTIR testing of the modified light stabilizer: The reacted modified light stabilizer solution was coated onto a KBr film and then dried in a 60°C oven. Subsequently, its infrared spectra were characterized using a Nicolet iS 5 infrared spectrometer, primarily monitoring the 2273 cm⁻¹ wavelength. -1 The absorption peak intensity is used to characterize the reaction and remaining status of the isocyanate group.

[0104] 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.

[0105] Table 1 shows the performance test results of the finished products provided in the examples and comparative examples.

[0106]

[0107]

[0108] 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 the UVA band (315nm-380nm). The low transmittance at 280nm is due to the absorption of this wavelength by the PET substrate.

[0109] 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 network 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.

[0110] Examples 1-5 used the modified light stabilizer of the present invention. Because the isocyanate group in the light stabilizer of the present invention has higher reactivity, it can chemically bond with the hydroxyl or carboxyl groups in the acrylate copolymer, 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 performance requirements of the protective film product of the present invention.

[0111] Example 5 shows a more pronounced cutoff effect in the UVA band, lower transmittance at 380nm, and "no precipitation" under high temperature and high humidity conditions, making it the optimal implementation scheme of the present invention.

[0112] 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 layer coating liquid; the adhesive layer coating liquid includes an acrylate copolymer, a light stabilizer, an isocyanate curing agent, and a solvent; the light stabilizer is obtained by reacting 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and hexamethylene diisocyanate in an organic solvent.

2. The protective film according to claim 1, characterized in that, The light stabilizer was obtained by reacting 0.120 g to 0.360 g of 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol and 0.510 g of hexamethylene diisocyanate.

3. A method for preparing a protective film according to claim 1, characterized in that, The method includes the following steps: 4-(4,6-diphenyl-S-triazine)-1,3-resorcinol was added to toluene and stirred until fully dissolved. Then, it was added dropwise to an ethyl acetate solution containing hexamethylene diisocyanate. After all the solution was added, the solution was kept at 60°C for 1-3 hours to prepare a solution of the light stabilizer. Subsequently, the acrylate copolymer, isocyanate curing agent and the above-mentioned light stabilizer solution were added to ethyl acetate to prepare the bonding adhesive coating liquid; The above-mentioned adhesive coating liquid is applied to the surface of the anti-glare film. The anti-glare film coated with the adhesive coating liquid is dried, and the adhesive coating liquid forms an adhesive layer. The barrier film is placed on the side of the anti-glare film with the adhesive layer, pressed and dried to prepare a protective film.

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