Optical film having a multilayer structure and display device including the same

Abstract

The present invention provides an optical film including a light-transmitting substrate and a primer layer, the optical film having a yellowness index (Y0) of 5.0 or less and a yellowing index (ΔY.I) of 5.5 or less before a light resistance test, and an excellent total light transmittance, and a display device including the optical film.

Description

[Technical Field]

[0001] The present invention relates to an optical film having a multilayer structure and a display device including the same. [Background technology]

[0002] Recently, as display devices have become thinner, lighter, and more flexible, the use of optical films containing polymer resins as cover windows instead of glass has been considered. In order for an optical film to be used as a cover window of a display device, it must have excellent optical and mechanical properties.

[0003] On the other hand, optical films containing polymer resins have the problem that they have a high initial yellowness or the yellowness increases significantly over time.

[0004] Therefore, there is a need to develop a film that has excellent mechanical properties such as insolubility, chemical resistance, and heat resistance, as well as excellent optical properties such as light resistance. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of one embodiment of the present invention is to provide an optical film that is excellent in scratch resistance (hardness), flexibility, and light resistance.

[0006] Another embodiment of the present invention aims to provide a display device including an optical film that is excellent in scratch resistance (hardness), flexibility, and light resistance. [Means for solving the problem]

[0007] To achieve the above object, one embodiment of the present invention provides an optical film comprising a light-transmitting substrate; and a primer layer; wherein the yellowness index (Y0) before a light resistance test is 5.0 or less and the yellowing index (ΔY.I) is 5.5 or less.

[0008] Here, the degree of yellowing (ΔY.I) is the difference (Y1 - Y0) between the yellowness (Y1) after the light resistance test and the yellowness (Y0) before the light resistance test, and the light resistance test is carried out under UV conditions [0.8 W / m 2 , @420 nm (863.4 kJ / m 2 , 30 o C / 30 RH% Chamber, 55 o C Black Panel × 300 hr).

[0009] The optical film can satisfy the following formula (1) with respect to the degree of yellowing (ΔY.I), the color difference (ΔE ab ) before and after the light resistance test, and the difference (ΔT) in total light transmittance.

[0010] [Formula 1] (ΔY.I - ΔE ab ) / [(ΔT) × (ΔE ab + |ΔT|)] ≥ 1

[0011] Here, the ΔE ab is the color difference before and after the light resistance test, and the ΔT is the difference (T1 - T0) between the total light transmittance (T1) after the light resistance test and the total light transmittance (T0) before the light resistance test. However, when the ΔT is 0 or less, the ΔT is set to 0.1 to calculate Formula 1, and the |ΔT| is calculated using Formula 1 with the original value of ΔT that is not 0.1 even when the ΔT is 0 or less.

[0012] The primer layer contains a curable resin, an ultraviolet absorber, and a pigment, and the curable resin may contain at least one selected from acrylic resins, urethane resins, and siloxane resins.

[0013] The curable resin may contain a siloxane resin polymerized by containing an alkoxysilane represented by the following Chemical Formula 1 and an alkoxysilane represented by the following Chemical Formula 2.

[0014] [Chemical Formula 1] R 1 n Si(OR 2 )4-n

[0015] In the above formula 1, R 1 is a C1-C10 linear, branched or alicyclic alkyl group substituted with epoxy or acryl, and R 2 is a C1-C8 linear, branched or alicyclic alkyl group, and n is an integer of 1 to 3.

[0016] [Chemical formula 2] Si(OR 3 )4

[0017] In the above formula 2, R 3 is a C1 to C4 linear or branched alkyl group.

[0018] The ultraviolet absorber may be included in an amount of 0.01 to 5.00 parts by weight based on 100 parts by weight of the curable resin, and the pigment may be included in an amount of 0.01 to 5.00 parts by weight based on 100 parts by weight of the curable resin.

[0019] The ultraviolet absorber and the pigment may be contained in a weight ratio of 50 to 100:1 (ultraviolet absorber:pigment=50 to 100:1).

[0020] The ultraviolet absorber may include a hydroxyphenyltriazine-based compound.

[0021] The pigment may include a copper phthalocyanine-based compound.

[0022] The primer layer may further include an additive.

[0023] The additive may include a polyether siloxane copolymer.

[0024] The total light transmittance (T0) before the light resistance test may be 88.0 or more.

[0025] The primer layer may have a thickness of 0.1 to 10 μm.

[0026] The optical film further includes a hard coat layer on top of the primer layer, and the light-transmissive substrate, the primer layer, and the hard coat layer may be laminated in the described order.

[0027] The hard coat layer may include at least one of a siloxane resin, an acrylic resin, a urethane resin, and an epoxy resin.

[0028] Another embodiment of the present invention provides a display device including a display panel; and the optical film disposed on the display panel.

Advantages of the Invention

[0029] According to one embodiment of the present invention, by including a novel primer layer, an optical film excellent in light resistance can be provided.

[0030] According to another embodiment of the present invention, a display device including an optical film excellent in light resistance can be provided.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0032] Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments described below are presented for illustrative purposes to assist in a clear understanding of the present invention and do not limit the scope of the present invention.

[0033] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are exemplary, and thus the present invention is not limited to the matters shown in the drawings. Throughout the specification, the same components may be denoted by the same reference numerals. In describing the present invention, if a detailed description of related known technologies is determined to unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

[0034] When terms such as "comprising," "having," and "performed" referred to in this specification are used, other parts may be added unless the expression "only" is used. When a component is expressed in the singular, it includes a plurality unless otherwise explicitly stated. Also, when interpreting a component, it is interpreted to include the range of error even without a separate explicit description.

[0035] In the case of an explanation of the positional relationship, for example, when the positional relationship between two parts is explained by "on," "above," "below," "next to," etc., there may be one or more other parts located between the two parts unless the expressions "immediately" or "directly" are used.

[0036] Terms expressing relative positions in space, such as "below," "beneath," "lower," "above," and "upper," may be used to easily describe the relationship of one element or component to another, as illustrated in the figures. Terms expressing relative positions in space should be understood to encompass different orientations of elements in use or operation, in addition to the orientation depicted in the figures. For example, if an element depicted in the figures is upside down, an element described as "below" or "beneath" another element may be positioned "above" the other element. Thus, the exemplary term "below" can encompass both an orientation of below and above. Similarly, the exemplary term "upper" can encompass both an orientation of above and below.

[0037] When describing a temporal relationship, for example, when the temporal sequence is described using "after," "following," "next to," or "before," it may not necessarily be consecutive, unless the words "immediately" or "directly" are used.

[0038] Although terms such as "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, a first component referred to below may be a second component within the scope of the technical concept of the present invention.

[0039] The term "at least one" should be understood to include all possible combinations of one or more related items. For example, "at least one of the first, second, and third items" means not only the first, second, or third item, but also all possible combinations of two or more of the first, second, and third items.

[0040] Each feature of various embodiments of the present invention can be partially or wholly combined or combined with each other, enabling various linkages and drives technically. Each embodiment may be implemented independently of each other or may be implemented together in a related relationship.

[0041] Prior to the detailed description of the present invention below, it should be understood that the terms used in this specification are for the purpose of describing specific embodiments and are not limited only by the appended patent claims. All technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which the present invention pertains, unless otherwise stated.

[0042] Also, hereinafter, in interpreting the terms and words used in this specification and the claims, based on the principle that the inventor can appropriately define the concept of the terms in order to explain his invention in the best way, it should not be interpreted only by the general or dictionary meaning. Instead, it must be interpreted in a meaning and concept consistent with the technical idea of the present invention according to what is described in this specification.

[0043] One embodiment of the present invention provides an optical film (100). FIG. 1 is a cross-sectional view of an optical film (100) according to one embodiment of the present invention.

[0044] As shown in FIG. 1, an optical film (100) according to one embodiment of the present invention includes a light-transmissive substrate (110); and a primer layer (120).

[0045] An optical film (100) according to an embodiment of the present invention has a yellowness (Y0) of 5.0 or less and a yellowing degree (ΔY.I) of 5.5 or less before the light resistance test. The yellowing degree (ΔY.I) is the difference (Y1 - Y0) between the yellowness (Y1) after the light resistance test and the yellowness (Y0) before the light resistance test, and the light resistance test is performed under UV conditions. The yellowness (Y0) before the light resistance test can be measured using a color difference meter. Specifically, the optical film (100) is cut into 50 mm × 50 mm, and using a color difference meter, for example, a color difference meter (model name: CM-3600A) manufactured by KONICA MINOLTA, based on ASTM D1925, with a D65 light source, a viewing angle of 2 degrees, and in transmission mode, the yellowness is measured 5 times, and the average value of the 5 measured yellownesses is calculated to measure the yellowness (Y0) before the light resistance test. The yellowness (Y1) after the light resistance test can be measured in the same manner as the method for measuring the yellowness (Y0) before the light resistance test after the light resistance test is performed.

[0046] Specifically, for the yellowing degree (ΔY.I) of the optical film (100), the yellowness (Y0) of the optical film (100) after the light resistance test is measured, and using a light resistance test device, for example, a light resistance test device (model name: Ci3000) manufactured by ATLAS, at 0.8 W / m 2 , @420 nm (863.4 kJ / m 2 , 30 o C / 30 RH% Chamber, 55 o C Black Panel × 300 hr) conditions, the light resistance test of the optical film (100) is performed. The yellowness (Y1) of the optical film (100) after the light resistance test is measured again. The value obtained by subtracting the yellowness (Y0) before the light resistance test from the yellowness (Y1) after the light resistance test measured in this way is the yellowing degree (the difference in yellowness; ΔY.I).

[0047] If the optical film (100) has a yellowness index (Y0) of 5.0 or less and a yellowing index (ΔY.I) of 5.5 or less before the light resistance test, the optical film (100) has excellent UV resistance and is suitable for use as a cover window for a display device. The polymer resin contained in the light-transmitting substrate (110) of the optical film (100) has a large amount of aromatic rings, which causes it to take on a yellowish color when exposed to ultraviolet (UV) wavelength light. Therefore, the yellowness index of the optical film (100) also increases over time. On the other hand, an optical film (100) with excellent UV resistance shows only a small increase in yellowness even when exposed to ultraviolet (UV) wavelength light. The optical film (100) according to one embodiment of the present invention has a primer layer (120) disposed on the light-transmitting substrate (110), which improves UV resistance and results in a yellowing index (ΔY.I) of 5.5 or less.

[0048] The optical film 100 according to an embodiment of the present invention may satisfy the following formula 1.

[0049] [Formula 1] (ΔY.I-ΔE ab ) / [(ΔT)×(ΔE ab +|ΔT|)] ≥ 1

[0050] Here, ΔE ab is the color difference before and after the light fastness test, and ΔT is the difference (T1-T0) between the total light transmittance after the light fastness test (T1) and the total light transmittance before the light fastness test (T0). If ΔT is 0 or less, ΔT is set to 0.1 to calculate Equation 1, and the absolute value ΔT (|ΔT|) is calculated using the original ΔT value instead of 0.1 even when ΔT is 0 or less.

[0051] Color difference before and after lightfastness test (ΔE ab ) is calculated by the following formula 2 using the difference in L*, a*, and b* of the optical film (100) before and after the light resistance test.

[0052] [Formula 2] ΔE ab =[(ΔL*) 2 +(Δa*) 2 +(Δb*)2 ] 1 / 2

[0053] In Equation 2, ΔL* is the difference between L* after the lightfastness test and L* before the lightfastness test, Δa* is the difference between a* after the lightfastness test and a* before the lightfastness test, and Δb* is the difference between b* after the lightfastness test and b* before the lightfastness test.

[0054] The L*, a*, and b* of the optical film (100) can be measured using a color difference meter. Specifically, the optical film (100) is cut into a piece of 50 mm x 50 mm, and the L*, a*, and b* are measured five times using a color difference meter, for example, a KONICA MINOLTA color difference meter (model name: CM-3600A), under a D65 light source, a viewing angle of 2 degrees, and transmission mode. The average values of the five measured L*, a*, and b* values are calculated to be the L*, a*, and b* of the optical film (100).

[0055] The total light transmittance (T0) before the lightfastness test can be measured using a haze meter. Specifically, the optical film (100) is cut to a size of 50 mm x 50 mm, and the total light transmittance is measured five times according to ASTM D1003 using a haze meter, for example, a MURAKAMI haze meter (model name: HM-150). The total light transmittance before the lightfastness test (T0) can be measured by calculating the average value of the five total light transmittance measurements. The total light transmittance after the lightfastness test (T1) can be measured after the lightfastness test using the same method as the method for measuring the total light transmittance before the lightfastness test (T1).

[0056] The optical film (100) according to one embodiment of the present invention may satisfy the above formula 1. As a result of experimental evaluation of the optical film (100), the inventors of the present invention found that when the yellowness index (Y0) of the optical film (100) before the light resistance test is 5.0 or less, the yellowness index (ΔY.I) and color difference (ΔE ab It was confirmed that the greater the difference between the color difference (ΔE) and the total light transmittance difference (ΔT) before and after the lightfastness test, the better the lightfastness. ab) multiplied by the sum of "and |ΔT|", the yellowness degree (ΔY.I) and the color difference (ΔE ab ) The greater the difference from, the greater the tendency was confirmed. However, when ΔT is a negative number, the value of the entire mathematical formula becomes a negative number and a result contrary to the tendency appears. Therefore, when ΔT is a negative number, it was calculated as 0.1. Thus, when the optical film (100) satisfies the above formula 1, that is, the color difference (ΔE ab ) is subtracted from the yellowness degree (ΔY.I) of the optical film (100), the value obtained by adding the absolute value (|ΔT|) of the difference between the color difference (ΔE ab ) and the total light transmittance is greater than or equal to the value obtained by multiplying the difference in total light transmittance (ΔT) by the sum of the absolute value (|ΔT|) of the difference between the color difference (ΔE

[0057] According to an embodiment of the present invention, the total light transmittance (T0) of the optical film (100) before the light resistance test can be 88.0 or more.

[0058] The light-transmissive substrate (110) of an embodiment of the present invention may include a polymer resin. Since the polymer resin is excellent in bending characteristics and impact resistance, etc., it is suitable for use as a cover window of a flexible display device.

[0059] The polymer resin can be included in the film in various shapes and forms such as in the form of solid content powder, in a form dissolved in a solution, and in a matrix form solidified after being dissolved in a solution. As long as it is a resin containing the same repeating unit as the present invention, regardless of the shape and form, any of them can be regarded as the same as the polymer resin of the present invention. Generally, the polymer resin in the film may exist in a matrix form obtained by applying a polymer resin solution and then drying and solidifying it.

[0060] The polymer resin according to an embodiment of the present invention may be any light-transmitting resin. For example, the polymer resin may include at least one selected from the group consisting of cycloolefin-based derivatives, cellulose-based polymers, ethylene-vinyl acetate-based copolymers, polyester-based polymers, polystyrene-based polymers, polyamide-based polymers, polyamide-imide-based polymers, polyetherimide-based polymers, polyacrylic-based polymers, polyimide-based polymers, polyethersulfone-based polymers, polysulfone-based polymers, polyethylene-based polymers, polypropylene-based polymers, polymethylpentene-based polymers, polyvinyl chloride-based polymers, polyvinylidene chloride-based polymers, polyvinyl alcohol-based polymers, polyvinyl acetal-based polymers, polyetherketone-based polymers, polyetheretherketone-based polymers, polymethylmethacrylate-based polymers, polyethylene terephthalate-based polymers, polybutylene terephthalate-based polymers, polyethylene naphthalate-based polymers, polycarbonate-based polymers, polyurethane-based polymers, and epoxy-based polymers. Preferably, the polymer resin according to an embodiment of the present invention may include at least one of polyimide-based polymers, polyamide-based polymers, and polyamideimide-based polymers. In particular, polyimide-based polymers, polyamide-based polymers, and polyamideimide-based polymers have excellent physical properties such as thermal properties, hardness, abrasion resistance, and flexibility, as well as optical properties such as light transmittance and haze, so it is preferable that the light-transmitting substrate 110 of the optical film 100 used as the cover window of a display device includes at least one of polyimide-based polymers, polyamide-based polymers, and polyamideimide-based polymers, although the present invention is not limited thereto.

[0061] According to an embodiment of the present invention, the light-transmitting substrate 110 may include a polymer resin including at least one of an imide repeating unit and an amide repeating unit. The light-transmitting substrate 110 may be any of a polyimide-based substrate, a polyamide-based substrate, and a polyamideimide-based substrate. However, the embodiment of the present invention is not limited thereto, and any substrate having light-transmitting properties may be used as the light-transmitting substrate 110 according to an embodiment of the present invention.

[0062] In one embodiment of the present invention, the primer layer 120 may include a curable resin; an ultraviolet absorber; and a pigment.

[0063] According to an embodiment of the present invention, the curable resin may include at least one selected from an acrylic resin, a urethane resin, and a siloxane resin. The curable resin may include any one selected from an acrylic resin, a urethane resin, and a siloxane resin depending on the type of the light-transmitting substrate 110 and the physical properties of the optical film 100. Preferably, the curable resin may include a siloxane resin.

[0064] The siloxane-based resin of one embodiment of the present invention can be produced through a hydrolysis and condensation reaction between alkoxysilanes containing organic compounds in the presence of a hydroxyl group. Specifically, the siloxane-based resin of one embodiment of the present invention can be produced by polymerizing a monomer containing an alkoxysilane represented by the following Chemical Formula 1 and an alkoxysilane represented by the following Chemical Formula 2:

[0065] [Chemical formula 1] R 1 n Si(OR 2 ) 4-n

[0066] In the above formula 1, R 1 is a C1-C10 linear, branched or alicyclic alkyl group substituted with epoxy or acryl, and R 2 is a C1-C8 linear, branched or alicyclic alkyl group, and n is an integer of 1 to 3.

[0067] [Chemical Formula 2] Si(OR 3 )4

[0068] In the above Chemical Formula 2, R 3 is a linear or branched alkyl group having 1 to 4 carbon atoms.

[0069] Although the above hydrolysis and condensation reaction can be carried out at room temperature, in order to accelerate the reaction, it can be stirred at 100 rpm for 1 hour to 120 hours at 50 to 120 o °C using a mechanical stirrer, but it is not limited thereto. In the present invention, sodium hydroxide is used as a catalyst during the reaction. However, acid catalysts such as hydrochloric acid, acetic acid, hydrogen fluoride, nitric acid, sulfuric acid, and iodic acid, base catalysts such as ammonia, potassium hydroxide, barium hydroxide, and imidazole, and ion exchange resins such as AmberLite can be used for the hydrolysis and condensation reaction. Further, it can be selected and used from the group consisting of these combinations. The amount of the catalyst is not particularly limited, but although 0.0001 to about 10 parts by weight can be added, it is not limited thereto. When the hydrolysis and condensation reaction is carried out, water or alcohol, which are by-products, are generated. By removing these, the reverse reaction can be reduced and the forward reaction can be carried out more quickly, and thus the reaction rate can be adjusted. Further, after the reaction is completed, the by-products can be removed by heating while reducing the pressure.

[0070] According to an embodiment of the present invention, an organic solvent can be added, but is not limited thereto, in order to control the viscosity of the siloxane resin to further facilitate processability and at the same time adjust the thickness of the coating film. The addition amount of the organic solvent is not particularly limited. The usable organic solvent may include, but is not limited to, one or more selected from solvents composed of ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, cyclohexanone, etc., or cellosolves such as methyl cellosolve, butyl cellosolve, etc., or ethers such as ethyl ether, dioxane, etc., alcohols such as isobutyl alcohol, isopropyl alcohol, butanol, methanol, etc., or halogenated hydrocarbons such as dichloromethane, chloroform, trichloroethylene, etc., or hydrocarbons such as normal hexane, benzene, toluene, etc.

[0071] According to an embodiment of the present invention, the siloxane resin may include, but is not limited to, an antioxidant in order to suppress the oxidation reaction caused by the polymerization reaction.

[0072] According to an embodiment of the present invention, the siloxane resin composition may additionally include, but is not limited to, a leveling agent or a coating aid.

[0073] According to an embodiment of the present invention, the polymerization may include, but is not limited to, a step of light irradiation or heating.

[0074] According to an embodiment of the present invention, after molding such as coating, casting, and molding using the siloxane resin composition, a high-hardness coating cured product can be manufactured by photopolymerization or thermal polymerization. In the case of photopolymerization, a uniform surface can be obtained by heat treatment before light irradiation, which can be performed at a temperature of 40 o °C or more and about 300 o °C or less, but is not limited thereto. Also, in the case of the light irradiation amount, it can be performed under conditions of 50 mJ / cm 2 or more and 20000 mJ / cm 2 or less, but is not limited thereto.

[0075] According to one embodiment of the present invention, an initiator may be additionally included for the polymerization of the siloxane resin. For example, a photopolymerization initiator such as an onium salt or an organometallic salt, and a thermal polymerization initiator such as an amine or an imidazole may be used, but it is not limited thereto. The addition amount of the initiator is not particularly limited, but although about 0.5 to 3.0 parts by weight may be added with respect to 100 parts by weight of the siloxane resin, it is not limited thereto.

[0076] According to one embodiment of the present invention, the primer layer (120) may include a curable resin, an ultraviolet absorber, and a pigment. The primer layer (120) may include 0.01 to 5.00 parts by weight of an ultraviolet absorber with respect to 100 parts by weight of the curable resin, and may include 0.01 to 5.00 parts by weight of a pigment with respect to 100 parts by weight of the curable resin.

[0077] The primer layer (120) may include 0.01 to 5.00 parts by weight of an ultraviolet absorber with respect to 100 parts by weight of the curable resin. When the ultraviolet absorber exceeds 5.00 parts by weight with respect to 100 parts by weight of the curable resin, the yellowness (Y0) of the optical film (100) before the light resistance test may exceed 5.0. When the yellowness (Y0) of the optical film (100) before the light resistance test exceeds 5.0, it is not suitable for use as a cover window of the display device. On the other hand, when the ultraviolet absorber is less than 0.01 part by weight with respect to 100 parts by weight of the curable resin, since the ultraviolet rays cannot be sufficiently absorbed, the improvement of the light resistance of the optical film (100) is low, so the degree of yellowing (ΔY.I) exceeds 5.5, and the formula 1 cannot be satisfied.

[0078] The primer layer (120) may include 0.01 to 5.00 parts by weight of a pigment with respect to 100 parts by weight of the curable resin. When the pigment exceeds 5.00 parts by weight with respect to 100 parts by weight of the curable resin, the transmittance of the optical film (100) decreases and the visibility of the optical film (100) deteriorates. On the other hand, when the pigment is less than 0.01 part by weight with respect to 100 parts by weight of the curable resin, the yellowness (Y0) of the optical film (100) before the light resistance test increases, and it is not suitable for use as a cover window of the display device.

[0079] According to one embodiment of the present invention, the ultraviolet absorber and the pigment can be included in a weight ratio of 50 to 100:1 (ultraviolet absorber: pigment = 50 - 100:1).

[0080] When the amount of the pigment contained is more than the weight ratio of the ultraviolet absorber and the pigment, the transmittance of the optical film (100) decreases and the visibility of the optical film (100) deteriorates. On the contrary, when the amount of the pigment contained is less than the weight ratio of the ultraviolet absorber and the pigment, the yellowness (Y0) of the optical film (100) before the light resistance test increases, which is not suitable for use as a cover window of a display device.

[0081] According to one embodiment of the present invention, the ultraviolet absorber may include a hydroxyphenyl-triazine-based compound. Specifically, the ultraviolet absorber may include 2-hydroxyphenyl-s-triazine or hydroxyphenyl-s-triazine. However, the present invention is not limited thereto, and other ultraviolet absorbers may be used in addition to the hydroxyphenyl-triazine-based compound.

[0082] According to one embodiment of the present invention, the pigment may include a Cu-phthalocyanine-based compound. However, the present invention is not limited thereto, and other pigments may be used in addition to the Cu-phthalocyanine-based compound.

[0083] According to one embodiment of the present invention, the primer layer (120) may further include an additive. The additive may include an additive that serves to increase the surface energy of the primer layer and improve the adhesion during additional functional surface treatment. When the primer layer (120) includes an additive, a surface characteristic with a water contact angle of 90 degrees or less can be realized to improve the adhesion.

[0084] According to one embodiment of the present invention, the additive may include a polyether siloxane copolymer, but the present invention is not limited thereto and other additives may be used in addition to the polyether siloxane copolymer.

[0085] According to one embodiment of the present invention, the primer layer 120 may contain 0.1 to 0.5 parts by weight of additives per 100 parts by weight of curable resin. If the amount exceeds 0.5 parts by weight per 100 parts by weight of curable resin, the weather resistance of the optical film 100 may be reduced, making it unsuitable for use as a cover window for a display device. On the other hand, if the amount of additives is less than 0.1 part by weight per 100 parts by weight of curable resin, the effect of increasing the surface energy of the optical film 100 may be weak, which may reduce adhesion when additional functional surface treatments are performed on the upper surface.

[0086] According to one embodiment of the present invention, the primer layer 120 may further include an initiator, such as, but not limited to, a photopolymerization initiator such as an onium salt or an organic metal salt, or a thermal polymerization initiator such as an amine or an imidazole. The initiator is not particularly limited, but may be included in an amount of about 0.5 to 3.0 parts by weight per 100 parts by weight of the curable resin.

[0087] According to an embodiment of the present invention, the optical film 100 may have optical transparency and flexibility. For example, the optical film according to an embodiment of the present invention may have bending, folding, and rollable properties.

[0088] The optical film 100 according to an embodiment of the present invention may have an adhesion strength of 5B or more even after being coated with a siloxane-based functional coating, an acrylic-based functional coating, or a urethane-based functional coating.

[0089] According to an embodiment of the present invention, the primer layer (120) may have a thickness of 0.1 to 10 μm. Preferably, the primer layer (120) may have a thickness of 1 to 5 μm.

[0090] When the thickness of the primer layer (120) exceeds 10 μm, the flexibility of the optical film (100) may decrease. When the thickness of the primer layer (120) is less than 0.1 μm, the light resistance of the optical film (100) may decrease.

[0091] According to an embodiment of the present invention, the optical film (101) may further include a hard coat layer (130) on the primer layer (120). FIG. 2 is a cross-sectional view of the optical film (101) further including the hard coat layer (130).

[0092] As shown in FIG. 2, the optical film (101) further including the hard coat layer (130) may be laminated in the order of the light transmissive substrate (110), the primer layer (120), and the hard coat layer (130).

[0093] The hard coat layer (130) is a layer that protects the optical film (101) and the adherend to which the optical film (101) is attached from the external environment. According to an embodiment of the present invention, the hard coat layer (130) may include at least one of a siloxane resin, an acrylic resin, a urethane resin, and an epoxy resin.

[0094] According to an embodiment of the present invention, the hard coat layer (130) may have a thickness of 1 to 10 μm, and preferably may have a thickness of 1 to 5 μm. However, the present invention is not limited thereto.

[0095] The optical film (100) according to an embodiment of the present invention is applied to a display device and can protect the display surface of the display panel. The optical film (100) according to an embodiment of the present invention may have a thickness sufficient to protect the display panel. For example, the optical film (100) may have a thickness of 20 to 120 μm. However, the present invention is not limited thereto.

[0096] Hereinafter, with reference to FIGS. 3 and 4, a display device using an optical film (100) according to an embodiment of the present invention will be described.

[0097] FIG. 3 is a cross-sectional view showing a part of a display device (200) according to another embodiment of the present invention, and FIG. 4 is an enlarged cross-sectional view showing the “P” part of FIG. 3.

[0098] Referring to FIG. 3, a display device (200) according to another embodiment of the present invention includes a display panel (501) and an optical film (100) on the display panel (501).

[0099] Referring to FIGS. 3 and 4, the display panel (501) includes a substrate (510), a thin film transistor (TFT) on the substrate (510), and an organic light emitting element (570) connected to the thin film transistor (TFT). The organic light emitting element (570) includes a first electrode (571), an organic light emitting layer (572) on the first electrode (571), and a second electrode (573) on the organic light emitting layer (572). The display device (200) disclosed in FIGS. 3 and 4 is an organic light emitting display device.

[0100] The substrate (510) can be made of glass or plastic. Specifically, the substrate (510) can be made of plastic such as a polyimide resin. Although not shown, a buffer layer can be disposed on the substrate (510).

[0101] The thin film transistor (TFT) is disposed on the substrate (510). The thin film transistor (TFT) includes a semiconductor layer (520), a gate electrode (530) insulated from the semiconductor layer (520) and overlapping at least a part of the semiconductor layer (520), a source electrode (541) connected to the semiconductor layer (520), and a drain electrode (542) spaced apart from the source electrode (541) and connected to the semiconductor layer (520).

[0102] 4, a gate insulating layer 535 is disposed between a gate electrode 530 and a semiconductor layer 520. An interlayer insulating layer 551 is disposed on the gate electrode 530, and a source electrode 541 and a drain electrode 542 may be disposed on the interlayer insulating layer 551.

[0103] The planarization film (552) is disposed on the thin film transistor (TFT) and flattens the top of the thin film transistor (TFT).

[0104] The first electrode (571) is disposed on the planarization film (552). The first electrode (571) is connected to the thin film transistor (TFT) through a contact hole provided in the planarization film (552).

[0105] The bank layer 580 is disposed on a portion of the first electrode 571 and the planarization film 552, and defines a pixel region or a light-emitting region. For example, the bank layer 580 may be disposed in a matrix structure in the boundary region between multiple pixels, thereby defining the pixel region.

[0106] The organic light-emitting layer 572 is disposed on the first electrode 571. The organic light-emitting layer 572 may also be disposed on the bank layer 580. The organic light-emitting layer 572 may include a single light-emitting layer or may include two or more light-emitting layers stacked one above the other. The organic light-emitting layer 572 may emit light having one of red, green, and blue colors, or may emit white light.

[0107] A second electrode (573) is disposed on the organic light-emitting layer (572).

[0108] The organic light emitting element (570) may be formed by stacking a first electrode (571), an organic light emitting layer (572), and a second electrode (573).

[0109] Although not shown, when the organic light-emitting layer (572) emits white light, each pixel may include a color filter for filtering the white light emitted from the organic light-emitting layer (572) by wavelength. The color filter is formed on the light travel path.

[0110] A thin film encapsulation layer (590) may be disposed on the second electrode (573). The thin film encapsulation layer (590) may include at least one organic film and at least one inorganic film, and at least one organic film and at least one inorganic film may be alternately disposed.

[0111] An optical film (100) is disposed on the display panel (501) having the stacked structure described above.

[0112] Hereinafter, the present invention will be described more specifically with reference to exemplary examples and comparative examples. However, the present invention is not limited by the examples and comparative examples described below.

[0113] [Production Example 1: Production of Light-Transmissive Substrate] After filling 776.655 g of DMAc (N,N-dimethylacetamide) into a 1 L reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller, and a cooler while passing nitrogen, the temperature of the reactor was adjusted to 25 o °C, and then 54.439 g (0.17 mol) of TFDB was dissolved and this solution was maintained at 25 o °C. 15.005 g (0.051 mol) of BPDA was added thereto, and after stirring for 3 hours to completely dissolve BPDA, 22.657 g (0.051 mol) of 6FDA was added and completely dissolved. After lowering the temperature of the reactor to 10 o °C, 13.805 g (0.068 mol) of TPC was added, and then reacted at 25 o °C for 12 hours to obtain a polymer solution having a solid content concentration of 12% by weight.

[0114] 17.75 g of pyridine and 22.92 g of acetic anhydride were added to the obtained polymer solution, and the mixture was stirred for 30 minutes. Then, it was stirred at 70 o °C for 1 hour, cooled to room temperature. 20 L of methanol was added to the obtained polymer solution to precipitate the solid content. The precipitated solid content was filtered, pulverized, washed again with 2 L of methanol, and then dried under vacuum at 100 o °C for 6 hours to obtain a powdery polyimide-based polymer solid content. The polyimide-based polymer solid content produced here is the solid content of the polyamideimide polymer.

[0115] After filling a 1 L reactor with 550 g of DMAc, the temperature of the reactor was maintained at 10 o °C and stirred for a certain period of time. Then, 75 g of the powdery polyimide-based polymer solid content produced was added, stirred for 1 hour, and then heated to 25 o °C to produce a liquid polyimide-based resin solution.

[0116] The obtained polyimide-based resin solution was applied to a glass substrate with an applicator, and then dried with hot air at 130 o °C for 30 minutes to produce a film. After that, the produced film was peeled off from the glass substrate and fixed to a frame with pins.

[0117] The frame with the film fixed was placed in a vacuum oven and slowly heated from 100 o °C to 300 o °C over 2 hours, then gradually cooled and separated from the frame to obtain a polyimide-based light-transmissive substrate. The polyimide-based light-transmissive substrate was heat-treated again at 250 o °C for 5 minutes to produce a polyimide-based light-transmissive substrate with a thickness of 50 μm.

[0118] [Production Example 2: Production of Curable Resin] 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane (TCI), TEOS (Tetraethyl orthosilicate, Sigma-Aldrich), and H2O were mixed in a ratio of 747.66 mL:38.28 mL:93.88 mL and placed in a 1500 mL flask. 0.1 g of sodium hydroxide was added as a catalyst and the resulting mixture was stirred for 60 minutes. o The mixture was stirred at C for 10 hours, and then filtered using a 0.45 μm Teflon (registered trademark) filter to obtain an epoxy-based siloxane resin.

[0119] [Example 1] To the epoxy siloxane resin prepared in Preparation Example 2, 600 mL of a mixture of MEK (methyl ethyl ketone):MIBK (methyl isobutyl ketone) diluted at a ratio of 2:8 was added. Then, 3 parts by weight of IRGACURE 250 (BASF) as a photoinitiator was added per 100 parts by weight of the prepared epoxy siloxane resin. Then, 2.5 parts by weight of Tinuvin 477 (solid content 80 wt%, BASF) as an ultraviolet absorber, 2.5 parts by weight of Tinuvin 479 (solid content 100 wt%, BASF) as an ultraviolet absorber, and 2.5 parts by weight of Terasol P-Blue-10 (solid content 10 wt%, BASF) as a pigment were added per 100 parts by weight of the epoxy siloxane resin. A primer layer coating composition was obtained by adding 0.05 parts by weight of PEG-406 (solid content 50 wt%, TEGO) based on the solid content to 100 parts by weight of the epoxy siloxane resin, and further adding 0.25 parts by weight of Glide 406 (solid content 50 wt%, TEGO) as an additive based on the solid content to 100 parts by weight of the epoxy siloxane resin.

[0120] The primer layer coating composition was applied to the upper surface of the polyimide-based light-transmitting substrate prepared in Preparation Example 1 using a bar, and then dried at 100° C. for 10 minutes.

[0121] Subsequently, it was exposed with an ultraviolet lamp having a wavelength of 315 nm at 1 J / cm 2 to produce an optical film having a primer layer with a thickness of 1 μm.

[0122] [Examples 2 to 6] In the same manner as in Example 1, by changing the types and contents of the ultraviolet absorber, pigment, and additive, the thickness of the primer layer, and the base material, optical films of Examples 2 to 6 were produced.

[0123] The specific types and contents of the ultraviolet absorber, pigment, and additive, the thickness of the primer layer, and the base material of Examples 2 to 6 are as shown in Table 1 below.

[0124] [Comparative Examples 1 to 6] In the same manner as in Example 1, by changing the types and contents of the ultraviolet absorber, pigment, and additive, the thickness of the primer layer, and the base material, optical films of Comparative Examples 1 to 6 were produced.

[0125] The specific types and contents of the ultraviolet absorber, pigment, and additive, the thickness of the primer layer, and the base material of Comparative Examples 1 to 6 are as shown in Table 1 below.

[0126] [Table 1]

[0127] Tinuvin 477 (BASF): hydroxyphenyl-s-triazine Tinuvin 479 (BASF): 2-hydroxyphenyl-s-triazine Terasol P-Blue-10 (AMTE): copper phthalocyanine-based compound Glide 406 (TEGO): solution of a polyether siloxane copolymer H33L (KOLON Industries, Product Name ASTROLL, Type H33L): 50 μm thick PET substrate

[0128] [Measurement example] The following measurements were carried out on the optical films prepared in Examples 1 to 6 and Comparative Examples 1 to 6. In the following measurement examples, the yellowness index, color difference, and total light transmittance were measured before the light resistance test and then measured again after the light resistance test.

[0129] The light resistance test was carried out in a light resistance test chamber (ATLAS, Ci3000) under UV conditions of 0.8 W / m 2 , @420nm, chamber condition 30 o C / 30% for 300 hours.

[0130] 1) Yellowness before (Y0) and after (Y1) light fastness test The optical films manufactured in the examples and comparative examples were cut into 50 mm x 50 mm pieces, and the yellowness index was measured five times using a KONICA MINOLTA color difference meter (model name: CM-3600A) under a D65 light source, a viewing angle of 2 degrees, and a transmission mode in accordance with ASTM D1925. The yellowness index (Y0, Y1) before and after the light fastness test was measured by calculating the average value of the five yellowness index measurements.

[0131] 2) Color difference before and after light fastness test (ΔE ab ) Color difference before and after lightfastness test (ΔE ab ) was calculated by the following formula 2 using the differences in L*, a*, and b* before and after the light resistance test for the optical films produced in the examples and comparative examples.

[0132] [Formula 2] ΔE ab =[(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 ] 1 / 2

[0133] In Equation 2, ΔL* is the difference between L* after the light resistance test and L* before the light resistance test, Δa* is the difference between a* after the light resistance test and a* before the light resistance test, and Δb* is the difference between b* after the light resistance test and b* before the light resistance test.

[0134] The L*, a*, and b* of the optical film were measured using a color difference meter. Specifically, the optical film was cut into 50 mm × 50 mm, and L*, a*, and b* were measured 5 times in transmission mode with a D65 light source, a 2-degree viewing angle, using a color difference meter (model name: CM-3600A) manufactured by KONICA MINOLTA. The average values of the 5 measured L*, a*, and b* were calculated and used as the L*, a*, and b* of the optical film.

[0135] 3) Total light transmittance (T1) after the light resistance test and total light transmittance (T0) before the light resistance test The optical films produced in the examples and comparative examples were cut into 50 mm × 50 mm, and using a haze meter, for example, a haze meter (model name: HM-150) manufactured by MURAKAMI, the total light transmittance was measured 5 times based on ASTM D1003, and the average value of the 5 measured total light transmittances was calculated to measure the total light transmittances (T0, T1) before and after the light resistance test.

[0136] 4) Value of Equation 1 The yellowness (Y0) before the light resistance test and after the light resistance test, the color difference (ΔE ab ) before and after the light resistance test, the total light transmittance (T1) after the light resistance test and the total light transmittance (T0) before the light resistance test, which were measured above, were substituted into the following Equation 1 to calculate the value of Equation 1.

[0137] [Equation 1] (ΔY.I - ΔE ab ) / [(ΔT) × (ΔE ab + |ΔT|)]

[0138] The measurement results are as shown in Table 2 below.

[0139]

Table 2

[0140] As disclosed in the measurement results in Table 2 above, for the optical films of Examples 1 to 6 of the present invention, the yellowness (Y0) before the light resistance test was 5.0 or less, the degree of yellowing (ΔY.I) was 5.5 or less, and the value calculated by Equation 1 was 1 or more.

[0141] However, for the optical films of Comparative Examples 1 to 6, the yellowness (Y0) before the light resistance test was 5.0 or less, the degree of yellowing (ΔY.I) exceeded 5.5, or the value calculated by Equation 1 was less than 1.

[0142] The features, structures, effects, etc. exemplified in the above-described respective examples can be combined or modified for other examples by those skilled in the art to which the examples belong and implemented. Therefore, the content related to such combinations and modifications should be construed as being included in the scope of the present invention.

Explanation of Reference Numerals

[0143] 100, 101: Optical film 110: Light-transmissive substrate 120: Primer layer 130: Hard coat layer 200: Display device 501: Display panel

Claims

1. A light-transmissive substrate; and A primer layer; comprising The primer layer is A curable resin; An ultraviolet absorber; and A pigment; comprising The curable resin comprises at least one selected from the group consisting of acrylic resins, urethane resins, and siloxane resins, The curable resin comprises a siloxane resin polymerized by including an alkoxysilane represented by the following Chemical Formula 1 and an alkoxysilane represented by the following Chemical Formula 2, The ultraviolet absorber and the pigment are included in a weight ratio of 50 to 100:1 (ultraviolet absorber:pigment = 50 - 100:1), The primer layer has a thickness of 0.1 to 10 μm, Yellowness (Y 0 ) before the light resistance test is 5.0 or less, The degree of yellowing (ΔY.I) is 5.5 or less, An optical film: Here, the degree of yellowing (ΔY.I) is the difference in yellowness (Y 1 ) after the light resistance test and the yellowness (Y 0 ) before the light resistance test (Y 1 - Y 0 ), and The light resistance test is carried out under UV conditions [0.8 W / m 2 , @420 nm (863.4 kJ / m 2 , 30 o C / 30 RH% chamber, 55 o C black panel × 300 hr). [Chemical Formula 1] R 1 n Si(OR 2 ) 4-n In the above Chemical Formula 1, R 1 is a C1-C10 linear, branched or alicyclic alkyl group substituted with epoxy or acrylic, and R 2 is a C1-C8 linear, branched or alicyclic alkyl group, and n is an integer from 1 to 3. [Chemical Formula 2] Si(OR 3 ) 4 In the above chemical formula 2, R 3 is a linear or branched alkyl group having 1 to 4 carbon atoms.

2. The yellowing degree (ΔY.I), the color difference (ΔE ab ) before and after the light resistance test, and the difference in total light transmittance (ΔT) satisfy the following formula 1: The optical film according to Claim 1: [Formula 1] (ΔY.I-ΔE ab ) / [(ΔT)×(ΔE ab +|ΔT|)]≧1 Here, the ΔE ab is the color difference before and after the light resistance test, The ΔT is the difference between the total light transmittance (T 1 ), after the light resistance test, and the total light transmittance (T 0 ), before the light resistance test, (T 1 −T 0 ). However, when the ΔT is 0 or less, the ΔT is set to 0.1 for calculating Formula 1, and the |ΔT| is calculated using Formula 1 with the original value of ΔT, not 0.1, even when the ΔT is 0 or less.

3. The ultraviolet absorber contains 0.01 to 5.00 parts by weight with respect to 100 parts by weight of the curable resin, The pigment contains 0.01 to 5.00 parts by weight with respect to 100 parts by weight of the curable resin, The optical film according to Claim 1.

4. The ultraviolet absorber contains a hydroxyphenyltriazine-based compound, The optical film according to Claim 1.

5. The pigment contains a copper phthalocyanine-based compound, The optical film according to Claim 1.

6. The primer layer further contains an additive, The optical film according to Claim 1.

7. The additive contains a polyether siloxane copolymer, The optical film according to Claim 6.

8. The total light transmittance (T 0 ) before the light resistance test is 88.0 or more, The optical film according to Claim 2.

9. The primer layer further includes a hard coat layer thereon, The light-transmissive substrate, the primer layer, and the hard coat layer are laminated in the described order, The optical film according to Claim 1.

10. The hard coat layer contains at least one of siloxane resins, acrylic resins, urethane resins, and epoxy resins, The optical film according to Claim 9.

11. A display panel; and An optical film according to any one of Claims 1 to 10 disposed on the display panel; comprising A display device.

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