Adhesive film and optical display device including same

Abstract

Disclosed herein are an adhesive film and an optical display device including the same. The adhesive film includes: a (meth) acrylic copolymer; a chain transfer agent; a photoinitiator; and an ultraviolet absorber mixture, wherein the ultraviolet absorber mixture includes an indole-based ultraviolet absorber as a first ultraviolet absorber; and at least one of a triazine ultraviolet light absorber 2-hydroxyphenyl-s-triazine and a benzotriazole ultraviolet light absorber 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1, 1-dimethylethyl)-4-methylphenol is included as the second ultraviolet light absorber, and at least one of the two ultraviolet light absorbers is included as the first ultraviolet light absorber and the benzotriazole ultraviolet light absorber 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1, 1-dimethylethyl)-4-methylphenol.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefits of Korean Patent Application No. 10-2023-0080006 filed in the Korean Intellectual Property Office on June 21, 2023, and all disclosures of the Korean Patent Application are incorporated herein by reference. Technical Field

[0003] The present invention relates to an adhesive film and an optical display device including the same. Background Art

[0004] Recently, many attempts have been made to remove polarizing plates from optical display devices. This can reduce the thickness of optical display devices, reduce manufacturing costs, and improve processability. Here, an adhesive film is used to replace the function of a typical polarizing plate.

[0005] In an optical display device that does not include a polarizer, an adhesive film needs to be formed on an upper surface of an organic light emitting diode (OLED) panel (i.e., a surface of the OLED panel on which external light is incident) to protect the OLED from ultraviolet (UV)-induced damage.

[0006] The adhesive film can be made by partially curing the adhesive film composition to a predetermined degree before being attached to the OLED panel. The adhesive film made can be post-cured after being attached to the OLED panel. Compared with the fully cured adhesive film, the partially cured adhesive film has a relatively low storage modulus. Therefore, the partially cured adhesive film can be better attached to the OLED panel. Here, since the adhesive film is post-cured on the OLED panel, light curing can be preferably used for the post-curing of the adhesive film.

[0007] Therefore, there is a need for an adhesive film having an appropriate range of storage modulus and peel strength both in a partially cured state and after post-cure while protecting an organic light emitting diode from UV-induced damage.

[0008] The background art of the present invention is disclosed in Korean Patent Laid-Open No. 2007-0055363. Summary of the invention

[0009] An aspect of the present invention is to provide an adhesive film that is a partially cured film and ensures a storage modulus and peel strength in an appropriate range both in a partially cured state and after post-curing while protecting an organic light emitting diode from UV-induced damage.

[0010] According to one aspect of the present invention, an adhesive film is provided.

[0011] The adhesive film comprises: a (meth)acrylic acid copolymer; a chain transfer agent; a photoinitiator; and a UV absorber mixture, wherein the UV absorber mixture comprises an indole-based UV absorber as a first UV absorber; and comprises at least one of a triazine-based UV absorber, 2-hydroxyphenyl-s-triazine, and a benzotriazole-based UV absorber, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, as a second UV absorber.

[0012] According to another aspect of the present invention, an optical display device is provided.

[0013] The optical display device includes a cured product of the adhesive film.

[0014] Embodiments of the present invention provide an adhesive film that is a partially cured film and ensures a storage modulus and peel strength in an appropriate range both in a partially cured state and after post-curing while protecting an organic light emitting diode from UV-induced damage. DETAILED DESCRIPTION

[0015] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. It should be understood that the present invention can be implemented in different ways and is not limited to the following embodiments.

[0016] The terms used herein are for the purpose of describing exemplary embodiments and are not intended to limit the present invention. Unless the context clearly indicates otherwise, the singular forms "a and an" and "the" used herein are intended to include the plural forms as well.

[0017] As used herein, "post-curing" is photocuring, wherein photocuring may include curing with a metal halide lamp at 1,000 mJ / cm 2 Up to 3,000mJ / cm 2 , preferably 2,000 mJ / cm 2 Up to 3,000mJ / cm 2 The adhesive film (eg, 100 μm to 200 μm thick) is cured by irradiating with 315 nm to 400 nm UV light.

[0018] As used herein, “partial curing” means photocuring, wherein the photocuring may include coating the adhesive film composition on one surface of the release film to a predetermined thickness and curing the film by using a black light (BL) lamp at 300 mJ / cm 2 Up to 2,000mJ / cm2 The adhesive film composition is cured by irradiating with UV light of 315 nm to 400 nm.

[0019] As used herein, the "homopolymer glass transition temperature" may refer to the glass transition temperature (Tg) measured for a homopolymer of a target monomer using a differential scanning calorimeter (Discovery, TA Instruments Inc.). Specifically, the homopolymer of the target monomer is heated to 180° C. at a heating rate of 20° C. / min, gradually cooled to −100° C., and heated to 100° C. at a heating rate of 10° C. / min to obtain data on an endothermic transition curve, and then the glass transition temperature is determined by the inflection point of the endothermic transition curve.

[0020] The “average particle size” of organic nanoparticles used herein refers to the Z-average particle size of organic nanoparticles obtained by measuring in an aqueous or organic solvent using a Zetasizer (Nano ZS instrument, Malvern Instruments Ltd.), and the average particle size of organic nanoparticles obtained by observing scanning electron microscope (SEM) / transmission electron microscope (TEM) images.

[0021] As used herein, "(meth)acryloyl" refers to acryloyl and / or methacryloyl.

[0022] As used herein, "index of refraction" is a value measured in the visible spectrum (eg, at a wavelength of 550 nm).

[0023] As used herein, "light transmittance" refers to single transmittance.

[0024] The expression “X to Y” used herein to express a specific numerical range means “greater than or equal to X and less than or equal to Y (X≤ and ≤Y)”.

[0025] One aspect of the present invention relates to an optically clear adhesive (OCA) film.

[0026] According to one aspect of the present invention, an adhesive film is provided. In this article, the adhesive film is a partially cured product of the following adhesive film composition. As will be described below, when the adhesive film is used in an optical display device that does not include a polarizing plate, the adhesive film can be finally bonded and fixed to an adherend (e.g., an optical display panel) by bonding the adhesive film to the optical display panel and then performing a post-curing process.

[0027] In one embodiment, a “post-cured adhesive film” refers to an adhesive film having a storage modulus ratio calculated according to Equation 1 of 100%.

[0028] The adhesive film refers to the adhesive film before post-curing and has a storage modulus different from that of the post-cured adhesive film when measured at the same temperature. This enables determination that the adhesive film has a different degree of curing from that of the post-cured adhesive film.

[0029] In one embodiment, the adhesive film may have a storage modulus ratio of 80% to less than 100%, for example, 80% to 95%, calculated according to Equation 1:

[0030] Storage modulus ratio = (A / B) × 100, ----(1)

[0031] Where A is the storage modulus of the adhesive film measured at 25°C (in kPa), and

[0032] B is the storage modulus of the post-cured adhesive film measured at 25°C (unit: kPa).

[0033] In this regard, the adhesive film may have a UV curing conversion of 80% to less than 100%, for example, 90% to 99%. The UV curing conversion may be measured as follows:

[0034] First, the adhesive film composition was measured using a Fourier transform infrared (FT-IR) spectrometer (NICOLET 4700, Thermo Electronics) at 1,635 cm -1 (C=C) and 1,720cm -1 Thereafter, the composition was applied to a glass substrate, and then irradiated with 1,000 mJ / cm by using a black light (BL) lamp. 2The film was irradiated with UV light of 315 nm to 400 nm to perform photocuring, thereby obtaining an adhesive film sample of 20 cm×20 cm×3 μm (width×length×thickness). Thereafter, the obtained adhesive film sample was divided into equal parts, and then an FT-IR spectrometer (Nicolit 4700, Thermo Fisher Scientific) was used to measure the 1635 cm -1 (C=C) and 1720cm -1 The intensity of the absorption peak near (C=O). The UV curing conversion rate is calculated according to Equation 2:

[0035] UV curing conversion rate (%) = |1-(C / D)| × 100, ----(2)

[0036] Where C is 1635 cm measured for the adhesive film -1 The absorption peak near 1720cm -1 and D is the intensity ratio of the absorption peak near 1635 cm-1 measured for the adhesive film composition. -1 The absorption peak near 1720cm -1 The intensity ratio of the nearby absorption peaks.

[0037] The adhesive film has a storage modulus and a peel strength in an appropriate range even in a partially cured state, and thus can be reliably bonded to an adherend.

[0038] In one embodiment, the adhesive film may have a storage modulus of 150 kPa or less, e.g., 10 kPa, 20 kPa, 30 kPa, 40 kPa, 50 kPa, 60 kPa, 70 kPa, 80 kPa, 90 kPa, 100 kPa, 110 kPa, 120 kPa, 130 kPa, 140 kPa, 150 kPa, 10 kPa to 150 kPa, when measured at 25° C. Within this range, the adhesive film may have good flexural reliability due to good viscoelasticity after post-curing.

[0039] In one embodiment, the adhesive film may have a storage modulus of 100 kPa or less, e.g., 10 kPa, 20 kPa, 30 kPa, 40 kPa, 50 kPa, 60 kPa, 70 kPa, 80 kPa, 90 kPa, 100 kPa, 10 kPa to 50 kPa, when measured at 60° C. Within this range, the adhesive film may have good flexural reliability due to good viscoelasticity after post-curing.

[0040] In one embodiment, the adhesive film may have a peel strength of 4,000 gf / inch or more, for example, 4,000 gf / inch to 6,000 gf / inch, when measured relative to a glass plate. Within this range, the adhesive film may not be easily peeled from the optical display panel after post-curing, thereby providing good reliability.

[0041] The adhesive film has a storage modulus and peel strength in an appropriate range after post-curing, and thus may be capable of being reliably adhered and fixed to an adherend while providing good flexural reliability under repeated bending.

[0042] In one embodiment, the adhesive film may have a storage modulus of 150 kPa or less, e.g., 10 kPa, 20 kPa, 30 kPa, 40 kPa, 50 kPa, 60 kPa, 70 kPa, 80 kPa, 90 kPa, 100 kPa, 10 kPa to 150 kPa, when measured at 25° C. after post-curing. Within this range, the adhesive film may have good flexural reliability due to good viscoelasticity after post-curing.

[0043] In one embodiment, the adhesive film may have a storage modulus of 50 kPa or less, for example 10 to 50 kPa, when measured at 60° C. after post-curing. Within this range, the adhesive film may have good flexural reliability due to good viscoelasticity after post-curing.

[0044] In one embodiment, the adhesive film may have a peel strength of 4,000 gf / inch or more, for example, 4,000 gf / inch to 6,000 gf / inch, when measured relative to a glass plate after post-curing. Within this range, the adhesive film may not be easily peeled from the optical display panel after post-curing, thereby providing good reliability.

[0045] The adhesive film protects the organic light emitting diode from UV-induced damage. According to one aspect of the present invention, the adhesive film may have a predetermined light transmittance in a predetermined wavelength region after post-curing, thereby protecting the organic light emitting diode from UV-induced damage. In addition, the adhesive film may have a predetermined light transmittance in a predetermined wavelength region before post-curing, thereby protecting the organic light emitting diode from UV-induced damage.

[0046] In one embodiment, the adhesive film may have a light transmittance of 1% or less, such as 0% to less than 1% or 0.01% to 0.5%, when measured at a wavelength of 380 nm. Within this range, the adhesive film may protect the organic light emitting diode from UV-induced damage.

[0047] In one embodiment, the adhesive film may have a light transmittance of 3% or less, such as 0% to less than 3% or 0.01% to 2.5%, when measured at a wavelength of 405 nm. Within this range, the adhesive film may protect the organic light emitting element from UV-induced damage.

[0048] Here, the values ​​of the above-mentioned “light transmittance at a wavelength of 380 nm” and “light transmittance at a wavelength of 405 nm” are values ​​measured for both the adhesive film and the post-cured adhesive film.

[0049] In one embodiment, the adhesive film may have a light transmittance of 70% or more, for example, 70% to 85% or 75% to 80%, when measured at a wavelength of 430 nm. Within this range, the adhesive film can be used as an optically transparent adhesive film in an optical display device.

[0050] Here, the value of the above-mentioned “light transmittance at a wavelength of 430 nm” is a value measured for both the adhesive film and the post-cured adhesive film.

[0051] The adhesive film may be formed by partially curing the adhesive film composition described below by irradiation with UV light. In order to ensure that the adhesive film has a light transmittance within the above range at wavelengths of 380 nm and 405 nm, respectively, the adhesive film composition includes the following specific UV absorbers: an indole-based UV absorber as a first UV absorber; and at least one of a triazine-based UV absorber, 2-hydroxyphenyl-s-triazine, and a benzotriazole-based UV absorber, 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol as a second UV absorber. Generally speaking, a UV absorber reduces the degree of curing by absorbing UV light during photocuring.

[0052] The adhesive film includes a first UV absorber and a second UV absorber.

[0053] The first UV absorber and the second UV absorber allow the adhesive film composition including the (meth)acrylic copolymer described below to be partially cured, thereby ensuring that an adhesive film formed from the adhesive film composition has a storage modulus and a peel strength within the above ranges.

[0054] When the adhesive film includes the second UV absorber as well as the first UV absorber, the adhesive film may have significantly lower light transmittance at wavelengths of 380 nm and 405 nm than when the adhesive film does not contain the second UV absorber but includes the same amount of the first UV absorber.

[0055] In addition, when the adhesive film includes the second UV absorber as well as the first UV absorber, the adhesive film may have significantly lower light transmittance at wavelengths of 380 nm and 405 nm than when the adhesive film includes a different type of UV absorber instead of the second UV absorber while including the same amount of the first UV absorber.

[0056] If the adhesive film contains a different type of UV absorber instead of the second UV absorber but includes the first UV absorber, the adhesive film may be less effective in protecting the organic light emitting diode from UV-induced damage due to reduced UV absorption performance and degradation of reflective color quality due to reduced color uniformity.

[0057] Specifically, according to the present invention, the adhesive film can be formed from an adhesive film composition including the following (meth)acrylic copolymer, a chain transfer agent and a photoinitiator, thereby providing the desired beneficial effects described herein. The adhesive film according to one aspect of the present invention will be described below.

[0058] The adhesive film comprises a (meth)acrylic copolymer, a chain transfer agent, a photoinitiator and a UV absorber mixture, wherein the UV absorber mixture comprises an indole-type UV absorber as a first UV absorber; and comprises at least one of a triazine-type UV absorber, 2-hydroxyphenyl-s-triazine, and a benzotriazole-type UV absorber, 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, as a second UV absorber.

[0059] The (meth)acrylic copolymer may be a copolymer of a monomer mixture including an alkyl group-containing (meth)acrylic monomer and a hydroxyl group-containing (meth)acrylic monomer.

[0060] The alkyl-containing (meth)acrylic monomer may form the matrix of the adhesive film. The alkyl-containing (meth)acrylic monomer may be an unsubstituted linear or branched (meth)acrylic ester containing a C1 to C2 alkyl group. For example, the alkyl-containing (meth)acrylic monomer may include at least one of 2-ethylhexyl (meth)acrylate, n-butyl (meth)acrylate, isooctyl (meth)acrylate, propyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, or decyl (meth)acrylate, preferably at least one of 2-ethylhexyl (meth)acrylate, n-butyl (meth)acrylate, or isooctyl (meth)acrylate, and more preferably 2-ethylhexyl acrylate or n-butyl acrylate.

[0061] The alkyl-containing (meth)acrylic monomer may have a homopolymer glass transition temperature of -20°C or less, for example, -80°C to -20°C or -80°C to -40°C. Within this range, the adhesive film may have improved foldability under low temperature conditions and high temperature and high humidity conditions.

[0062] The alkyl-containing (meth)acrylic monomer may be present in an amount of 10 wt % to 90 wt % (e.g., 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %, 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %, 21 wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt %, 30 wt %, 31 wt %, 32 wt %, 33 wt %, 34 wt %, 35 wt %, 36 wt %, 37 wt %, 38 wt %, 39 wt %, 40 wt %, 41 wt %, 42 wt %, 43 wt %, 44 wt %, 45 wt %, 46 wt %, 47 wt %, 48 wt %, 49 wt %, 50 wt %, 51 wt %, 52 wt %, 53 wt %, 54 wt %, %, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%), or an amount from 20 wt% to 60 wt% (e.g., 25 wt% to 55 wt% or 30 wt% to 50 wt%) is present in the monomer mixture. Within this range, the adhesive film may have improved foldability under low temperature conditions and under high temperature and high humidity conditions.

[0063] The hydroxyl group-containing (meth)acrylic monomer is used to improve the peel strength of the adhesive film.

[0064] The hydroxyl-containing (meth)acrylic acid monomer may be a linear or branched C1 to C2 10 (Meth)acrylate. For example, the hydroxyl-containing (meth)acrylic acid monomer may include at least one of 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, or 6-hydroxyhexyl (meth)acrylate, but is not limited thereto.

[0065] The hydroxyl-containing (meth)acrylic monomer may have a homopolymer glass transition temperature of 0° C. or less, for example, -70° C. to 0° C., -60° C. to -10° C., or -50° C. to -10° C. Within this range, the adhesive film may have improved peel strength and foldability.

[0066] The hydroxyl-containing (meth) acrylic monomer may be present in the monomer mixture in an amount of 0.1 wt % to 30 wt % (e.g., 0.1 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %, 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %, 21 wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt %, 30 wt %), 1 wt % to 30 wt %, 5 wt % to 25 wt %, or 10 wt % to 25 wt %. Within this range, the adhesive film may have further improved peel strength and durability.

[0067] The monomer mixture may also include (meth)acrylic or vinyl monomers having high homopolymer glass transition temperatures.

[0068] The (meth)acrylic or vinyl monomer having a high homopolymer glass transition temperature is used to improve the peel strength of the adhesive film or to enhance the cohesion of the adhesive film composition.

[0069] In one embodiment, the (meth)acrylic acid or vinyl monomer may have a higher homopolymer glass transition temperature than each of the alkyl-containing (meth)acrylic acid monomer and the hydroxyl-containing (meth)acrylic acid monomer. In this way, compared with when the monomer mixture only includes the alkyl-containing (meth)acrylic acid monomer and the hydroxyl-containing (meth)acrylic acid monomer having a low homopolymer glass transition temperature, it is possible to ensure that the storage modulus of the adhesive film can easily reach the above range while enabling the adhesive film to have improved peel strength.

[0070] For example, the (meth)acrylic acid or vinyl monomer may have a homopolymer glass transition temperature of 5° C. or higher, for example, 5° C., 10° C., 15° C., 20° C., 25° C., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., 105° C., 110° C., 115° C., 120° C., 125° C., 130° C., 135° C., 140° C., 145° C., 150° C., 155° C., 160° C., 165° C., 170° C., 175° C., 180° C., 185° C., 190° C., 195° C., 200° C., 5° C. to 200° C., or 10° C. to 200° C. Within this range, the adhesive film may have improved peel strength.

[0071] The type of the (meth)acrylic or vinyl monomer having a high homopolymer glass transition temperature is not particularly limited as long as the (meth)acrylic or vinyl monomer has a homopolymer glass transition temperature within the above range.

[0072] In one embodiment, the (meth) acrylic acid or vinyl monomer may be a nitrogen-containing (meth) acrylic acid or vinyl monomer for promoting the dilution of the UV absorber described below. Since the adhesive film can be formed from the solvent-free adhesive film composition, the UV absorber in the adhesive film composition needs to be sufficiently diluted to avoid an increase in the haze of the adhesive film. The solvent-free adhesive film composition can provide an adhesive film with a homogeneous surface when photocured.

[0073] In one embodiment, the (meth)acrylic or vinyl monomer may include at least one of a heterocycloaliphatic group-containing (meth)acrylic or vinyl monomer or a cycloaliphatic group-containing (meth)acrylic or vinyl monomer to maximize the dispersion of the UV absorber in the adhesive film composition and improve the peel strength of the adhesive film.

[0074] In one embodiment, the (meth)acrylic or vinyl monomer may be a mixture of a (meth)acrylic or vinyl monomer containing a heterocycloaliphatic group and a (meth)acrylic or vinyl monomer containing a cycloaliphatic group.

[0075] The (meth)acrylic or vinyl monomer containing a heterocyclic aliphatic group may be (meth)acryloylmorpholine, N-vinylpyrrolidone, or the like.

[0076] The (meth) acrylic or vinyl monomer containing a heterocyclic aliphatic group may be present in the monomer mixture in an amount of 0.1 wt % to 30 wt %, (e.g., 0.1 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %, 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %, 21 wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt %, 30 wt %), 1 wt % to 20 wt %, 5 wt % to 20 wt %, or 5 wt % to 15 wt %. Within this range, the adhesive film may have further improved peel strength and durability.

[0077] The cycloaliphatic group-containing (meth)acrylic or vinyl monomer may be dihydrodicyclopentadienyl (meth)acrylate (eg, dihydrodicyclopentadienyl acrylate (DCPA)), isobornyl (meth)acrylate, or the like.

[0078] The (meth) acrylic or vinyl monomer containing a cycloaliphatic group may be present in the monomer mixture in an amount of 0.1 wt % to 30 wt % (e.g., 0.1 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %, 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %, 21 wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt %, 30 wt %), 1 wt % to 20 wt %, 5 wt % to 20 wt %, or 5 wt % to 15 wt %. Within this range, the adhesive film may have further improved peel strength and durability.

[0079] The (meth) acrylic or vinyl monomer having a high homopolymer glass transition temperature can be present in the monomer mixture in an amount of 0 wt % to 70 wt % (e.g., 0 wt %, 5 wt %, 10 wt %, 15 wt %, 20 wt %, 25 wt %, 30 wt %, 35 wt %, 40 wt %, 45 wt %, 50 wt %, 55 wt %, 60 wt %, 65 wt %, 70 wt %), 10 wt % to 50 wt %. Within this range, the adhesive film can have improved adhesion.

[0080] In one embodiment, the alkyl-containing (meth) acrylic monomer, the hydroxyl-containing (meth) acrylic monomer and the (meth) acrylic or vinyl monomer having a high homopolymer glass transition temperature may be present in the monomer mixture in an amount of 80 wt % or more, such as 80 wt %, 81 wt %, 82 wt %, 83 wt %, 84 wt %, 85 wt %, 86 wt %, 87 wt %, 88 wt %, 89 wt %, 90 wt %, 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, 99 wt %, 100 wt %, 80 wt % to 100 wt %. Within this range, the adhesive film can easily provide the desired beneficial effects described herein.

[0081] The monomer mixture may further include an aromatic group-containing (meth)acrylic monomer.

[0082] The aromatic group-containing (meth)acrylic monomer is used to reduce the dielectric constant of the adhesive film or adjust the refractive index of the adhesive film before and after post-curing.

[0083] The aromatic group-containing (meth)acrylic monomer may be a substituted or unsubstituted C6 to C 20 Aromatic (meth) acrylic monomer or substituted or unsubstituted C7 to C 20 Aralkyl (meth)acrylic acid monomers, for example, benzyl (meth)acrylate, phenyl (meth)acrylate, naphthyl (meth)acrylate, phenoxy (meth)acrylate, and benzylphenyl (meth)acrylate.

[0084] The (meth)acrylic monomer containing an aromatic group may be 70 wt% or less, for example, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, %, 40 wt %, 41 wt %, 42 wt %, 43 wt %, 44 wt %, 45 wt %, 46 wt %, 47 wt %, 48 wt %, 49 wt %, 50 wt %, 51 wt %, 52 wt %, 53 wt %, 54 wt %, 55 wt %, 56 wt %, 57 wt %, 58 wt %, 59 wt %, 60 wt %, 61 wt %, 62 wt %, 63 wt %, 64 wt %, 65 wt %, 66 wt %, 67 wt %, 68 wt %, 69 wt %, 70 wt %, 10 wt % to 40 wt % are present in the monomer mixture. Within this range, the (meth) acrylic monomer containing an aromatic group can help reduce the dielectric constant of the adhesive film or adjust the refractive index of the adhesive film.

[0085] In one embodiment, the alkyl-containing (meth) acrylic monomer, the hydroxyl-containing (meth) acrylic monomer, the (meth) acrylic or vinyl monomer having a high homopolymer glass transition temperature, and the aromatic-containing (meth) acrylic monomer may be present in the monomer mixture in an amount of 95 wt % or more, for example, 95 wt % to 100 wt %. Within this range, the adhesive film can easily provide the desired beneficial effects described herein.

[0086] The (meth)acrylic copolymer may be prepared from the above-mentioned monomer mixture by a typical polymerization method known in the art.

[0087] The chain transfer agent is used to increase the fluidity of the (meth)acrylic acid copolymer by adjusting the weight average molecular weight of the (meth)acrylic acid copolymer. The chain transfer agent may include at least one of a monofunctional or polyfunctional primary or secondary thiol compound, a thioglycolic acid compound, a thiocarbonyl compound, or a mercaptopropionic acid compound.

[0088] Specifically, the chain transfer agent may include β-mercaptopropionic acid, 2-ethylhexyl-3-mercaptopropionate, n-octyl-3-mercaptopropionate, methoxybutyl-3-mercaptopropionate, stearyl-3-mercaptopropionate, trimethylolpropane tris(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, pentaerythritol tetrakis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), dipentaerythritol hexa(3-mercaptopropionate), 3,3'-thiodipropionic acid, dithiopropionic acid, laurylthiopropionic acid, thioglycolic acid, ammonium thioglycolic acid, monoethanolamine thioglycolic acid, diammonium thioglycolic acid, and the like.

[0089] The chain transfer agent may be present in an amount of 0.01 to 2 parts by weight (e.g., 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2), 0.1 to 1, 0.1 to 0.5, or 0.1 to 0.3 parts by weight, relative to 100 parts by weight of the (meth)acrylic copolymer in the adhesive film composition or relative to 100 parts by weight of the cured product of the (meth)acrylic copolymer in the adhesive film, based on solid content. Within this range, the chain transfer agent may improve the fluidity of the (meth)acrylic copolymer by adjusting the weight average molecular weight of the (meth)acrylic copolymer without reducing the transparency of the adhesive film due to an excessive amount of the chain transfer agent.

[0090] As used herein, the “cured product of the (meth)acrylic copolymer” refers to a product obtained by partially curing the (meth)acrylic copolymer using a photoinitiator.

[0091] The chain transfer agent may be present in the adhesive film in an amount of 0.01 wt % to 2 wt %, for example 0.01 wt % to 0.5 wt %. Within this range, the chain transfer agent can improve the fluidity of the (meth)acrylic copolymer by adjusting the weight average molecular weight of the (meth)acrylic copolymer without reducing the transparency of the adhesive film due to an excessive amount of the chain transfer agent.

[0092] The photoinitiator is used to cure the adhesive film composition into an adhesive film and to post-cure the adhesive film. Preferably, the photoinitiator comprises a photo radical initiator.

[0093] The type of the photoinitiator is not particularly limited as long as the photoinitiator can cure the adhesive film composition when irradiated with UV light.

[0094] For example, the photoinitiator can be a benzoin photoinitiator, a hydroxyketone photoinitiator, an aminoketone photoinitiator, or a phosphine oxide photoinitiator.

[0095] The photoinitiator may be present in an amount of 0.1 to 2 parts by weight, for example 0.1 to 1 part by weight or 0.3 to 0.6 parts by weight, based on solid content, relative to 100 parts by weight of the (meth)acrylic copolymer in the adhesive film composition. Within this range, the photoinitiator may promote the curing of the adhesive film composition into an adhesive film and post-cure the adhesive film.

[0096] The photoinitiator may be present in the adhesive film in an amount of 0.01 wt % to 5 wt %, for example 0.01 wt % to 1 wt % or 0.2 wt % to 0.6 wt %. Within this range, the photoinitiator may promote curing of the adhesive film composition into an adhesive film and post-cure the adhesive film.

[0097] The adhesive film includes an indole-based UV absorber as a first UV absorber.

[0098] The indole-based UV absorber is used to reduce the light transmittance of the adhesive film at a wavelength of 380 nm or 405 nm. Therefore, when used in an optical display device, the adhesive film can protect the organic light emitting diode from UV-induced damage.

[0099] The indole-based UV absorber may have a maximum absorption wavelength of 390 nm or more, specifically 390 nm to 400 nm, more specifically greater than 390 nm to less than 400 nm. Within this range, the adhesive film may sufficiently absorb light at a wavelength of 420 nm or less, light at a wavelength of 400 nm to 420 nm, and light at a wavelength of 405 nm or less, among external light incident on the adhesive film, thereby reducing UV transmittance and thus reducing UV-induced damage to the organic light emitting diode. Here, the "maximum absorption wavelength" refers to a wavelength at which a maximum absorption peak occurs, i.e., a wavelength corresponding to the maximum absorbance in an absorbance curve as a function of wavelength. Here, the "absorbance" may be measured by any typical method known in the art.

[0100] The indole-based UV absorber may include a compound represented by Formula 1:

[0101]

[0102] Where R 1 is hydrogen or substituted or unsubstituted C1 to C 10 alkyl,

[0103] R 2 is hydrogen or a substituted or unsubstituted C6 to C20 Aryl,

[0104] R 3 is hydrogen or substituted or unsubstituted C1 to C 10 alkyl,

[0105] R 4 is hydrogen, cyano (CN), or substituted or unsubstituted C1 to C 10 Alkyl, and

[0106] R 5 is cyano or -(C=O)OR 6 (R 6 is substituted or unsubstituted C1 to C 10 Alkyl or substituted or unsubstituted C6 to C 20 aryl).

[0107] Specifically, R 1 It can be a C1 to C5 alkyl group, specifically a methyl group, R 2 Available in C6 to C 10 Aryl, specifically phenyl, R 3 may be hydrogen or C1 to C5 alkyl, specifically hydrogen, R 4 may be cyano, and R 5 Can be cyano or -(C=O)OR 6 (R 6 is a substituted or unsubstituted C1 to C5 alkyl).

[0108] More specifically, the indole-based UV absorber may include a compound represented by Formula 1-1 or Formula 1-2:

[0109] [Formula 1-1]

[0110]

[0111] [Formula 1-2]

[0112]

[0113] In one embodiment, the indole-based UV absorber may have a melting point of 100° C. or higher, specifically 140° C. to 220° C., and may be in a solid phase at room temperature.

[0114] In terms of solid content, the indole-based UV absorber may be 0.01 to 0.5 parts by weight, 0.01 parts by weight, 0.05 parts by weight, 0.06 parts by weight, 0.07 parts by weight, 0.08 parts by weight, 0.09 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2.1 parts by weight, 2.2 parts by weight, 2.3 parts by weight, 2.4 parts by weight, 2.5 parts by weight, 2.6 parts by weight, 2.7 parts by weight, 2.8 parts by weight, 2.9 parts by weight, 3. .8 parts by weight, 1.9 parts by weight, 2 parts by weight, 2.1 parts by weight, 2.2 parts by weight, 2.3 parts by weight, 2.4 parts by weight, 2.5 parts by weight, 2.6 parts by weight, 2.7 parts by weight, 2.8 parts by weight, 2.9 parts by weight, 3 parts by weight, 3.1 parts by weight, 3.2 parts by weight, 3.3 parts by weight, 3.4 parts by weight, 3.5 parts by weight, 3.6 parts by weight, 3.7 parts by weight, 3.8 parts by weight, 3.9 parts by weight, 4 parts by weight, 4.1 parts by weight, 4.2 parts by weight, 4.3 parts by weight, 4.4 parts by weight, 4.5 parts by weight, 4.6 parts by weight, 4.7 parts by weight, 4.8 parts by weight, 4.9 parts by weight, 5 parts by weight, for example, 0.05 parts by weight to 0.5 parts by weight or 0.05 parts by weight to 0.3 parts by weight. Within this range, the indole-based UV absorber can help protect the organic light emitting diode from UV-induced damage without reducing the UV curing conversion rate when irradiated with UV light.

[0115] The indole-based UV absorber may be present in the adhesive film in an amount of 0.01 wt % to 10 wt %, for example 0.01 wt % to 5 wt %, or 0.01 wt % to 3 wt %. Within this range, the indole-based UV absorber may help protect the organic light emitting diode from UV-induced damage without reducing the UV curing conversion rate during photocuring.

[0116] The adhesive film includes at least one of a triazine-based UV absorber, 2-hydroxyphenyl-s-triazine, and a benzotriazole-based UV absorber, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, as a second UV absorber. The second UV absorber protects the organic light-emitting diode from UV-induced damage by absorbing UV light, ensures that the storage modulus and peel strength of the adhesive film easily reach the above ranges during the partial curing of the adhesive film composition, and significantly reduces the light transmittance of the adhesive film at wavelengths of 380 nm and 405 nm in combination with the first UV absorber.

[0117] In one embodiment, the triazine-based UV absorber may be a compound represented by Formula 2:

[0118] [Formula 2]

[0119]

[0120] The triazine-based UV absorber can be prepared by a method known in the art, or can be a commercially available product, such as Tinuvin 477.

[0121] The benzotriazole-based UV absorber may be a compound represented by Formula 3:

[0122] [Formula 3]

[0123]

[0124] The benzotriazole-based UV absorber can be prepared by a method known to those skilled in the art, or may be a commercially available product, such as Tinnafin 326.

[0125] In terms of solid content, the second UV absorber may be present in an amount of 0.01 to 5 parts by weight (e.g., 0.01, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 3.7, 3.8, 3.9, 4.7, 4.8, 4.9, 5.1 The second UV absorber can be present in an amount of 0.1 to 5 parts by weight. Within this range, the second UV absorber can protect the organic light emitting diode from UV-induced damage by absorbing UV light.

[0126] The second UV absorber may be present in the adhesive film in an amount of 0.01 wt % to 5 wt %, for example 0.05 wt % to 5 wt % or 0.1 wt % to 5 wt %. Within this range, the second UV absorber can protect the organic light emitting diode from UV-induced damage by absorbing UV light.

[0127] In order to ensure that the adhesive film composition is partially cured both by the absorption of UV light by the second UV absorber and by a UV-initiated photocuring reaction, the weight ratio of the photoinitiator to the second UV absorber in the adhesive film or the adhesive film composition calculated according to Equation 3 is adjusted to a range of 0.06 to 6 (e.g., 0.06, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6), preferably 0.1 to 3. Within this range, it is possible to ensure that the UV-initiated photocuring reaction occurs while ensuring that the second UV absorber protects the organic light emitting diode from UV-induced damage by absorbing UV light.

[0128] <Equation 3>

[0129] Weight ratio = photoinitiator / second UV absorber, ----(3)

[0130] The first UV absorber and the second UV absorber may be present in an amount of 95 wt % or more, for example, 95 wt % to 100 wt %, based on the total weight of all UV absorbers contained in the adhesive film. Within this range, the adhesive film can provide the desired beneficial effects described herein without increasing haze due to an excess of UV absorbers. Here, among all UV absorbers, UV absorbers other than the first UV absorber and the second UV absorber may be any typical absorber known in the art for absorbing light in the UV spectrum.

[0131] The first UV absorber and the second UV absorber may be present in the adhesive film at a weight ratio (first UV absorber: second UV absorber) of 1:0.5 to 1:90, preferably 1:0.5 to 1:85. Within this range, the UV absorber can easily provide the desired beneficial effects described herein.

[0132] The adhesive film may further include a cross-linking agent.

[0133] The crosslinking agent is used to increase the degree of crosslinking of the adhesive film composition, thereby improving the mechanical strength of the adhesive film.

[0134] The crosslinking agent may include an actinic radiation curable multifunctional (meth)acrylate. For example, the crosslinking agent may include: a difunctional (meth)acrylate, such as 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified di(meth)acrylate, di(meth)acryloyloxyethyl isocyanurate, allylated cyclohexyl di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, dimethylol dicyclopentane di(meth)acrylate, ethylene oxide-modified hexahydrophthalic acid di(meth)acrylate, neopentyl glycol-modified trimethylpropane di(meth)acrylate, adamantane di(meth)acrylate, or 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene; a trifunctional The invention also includes a functional (meth)acrylate such as trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, trifunctional urethane (meth)acrylate or tri(meth)acryloyloxyethyl isocyanurate; a tetrafunctional (meth)acrylate such as diglycerol tetra(meth)acrylate or pentaerythritol tetra(meth)acrylate; a pentafunctional (meth)acrylate such as dipentaerythritol penta(meth)acrylate; and a hexafunctional (meth)acrylate such as dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified urethane (meth)acrylate, or a reaction product of an isocyanate monomer and trimethylolpropane tri(meth)acrylate, but is not limited thereto.

[0135] The crosslinking agent may be present in an amount of 5 parts by weight or less, for example, 0.01 to 1 parts by weight, relative to 100 parts by weight of the (meth)acrylic copolymer or relative to 100 parts by weight of the cured product of the (meth)acrylic copolymer in the adhesive film composition, based on solid content. Within this range, the crosslinking agent may improve the mechanical strength of the adhesive film without affecting other properties of the adhesive film.

[0136] The adhesive film may further include a silane coupling agent.

[0137] The silane coupling agent is used to further enhance the peel strength of the adhesive film relative to the adherend. The silane coupling agent may include any typical silane coupling agent known in the art. For example, the silane coupling agent may include at least one selected from the group consisting of: a silicon compound having an epoxy structure, such as 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; a polymerizable silicon compound containing an unsaturated group, such as vinyltrimethoxysilane, vinyltriethoxysilane, and (meth)acryloxypropyltrimethoxysilane; an amino group-containing silicon compound, such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; and 3-chloropropyltrimethoxysilane, but not limited thereto.

[0138] The silane coupling agent may be present in an amount of 5 parts by weight or less, for example, 0.1 to 3 parts by weight, relative to 100 parts by weight of the (meth)acrylic copolymer or relative to 100 parts by weight of the cured product of the (meth)acrylic copolymer in the adhesive film composition, based on solid content. Within this range, the silane coupling agent can improve the adhesion of the adhesive film to the adherend without affecting other properties of the adhesive film.

[0139] The silane coupling agent may be present in the adhesive film in an amount of 0 wt % to 5 wt %, specifically 0.1 wt % to 3 wt %. Within this range, the silane coupling agent may improve the adhesion of the adhesive film to an adherend without affecting other properties of the adhesive film.

[0140] The adhesive film may contain typical additives such as antistatic agents, surfactants, curing accelerators, ionic liquids, lithium salts, inorganic fillers, softeners, molecular weight modifiers, antioxidants, anti-aging agents, stabilizers, adhesion-imparting resins, modified resins (e.g., polyol resins, phenolic resins, acrylic resins, polyester resins, polyolefin resins, epoxy resins, epoxidized polybutadiene resins, etc.), leveling agents, defoaming agents, plasticizers, dyes, pigments (coloring pigments, extender pigments, etc.), treating agents, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, flocculants, and lubricants.

[0141] The additive may be present in the adhesive film in an amount of 10 wt % or less, specifically 0.01 wt % to 10 wt %, more specifically 0.01 wt % to 1 wt %. Within this range, the additive may provide the desired effect without affecting the adhesion and reliability of the adhesive film.

[0142] The adhesive film may have a thickness of 200 μm or less, for example, greater than 0 μm to 200 μm or 150 μm to 200 μm. Within this range, the adhesive film may be used in an optical display device.

[0143] The adhesive film can be made by applying the adhesive film composition to one surface of the base film to form a coating, followed by drying and photocuring the coating. A release film can also be attached to one surface of the adhesive film to prevent foreign matter from adhering to the adhesive film after aging of the coating. The coating can be dried by heat treatment at a temperature of 100°C to 150°C for 0.5 minutes to 5 minutes. If not required, the drying of the coating can be omitted. In addition, the photocuring can be partially cured. Here, it is necessary to control the injection amount of UV radiation so that the adhesive film has a UV curing conversion rate of less than 100% calculated according to Equation 2, that is, the adhesive film is not completely cured.

[0144] Next, an adhesive film according to another aspect will be explained.

[0145] The adhesive film comprises a (meth)acrylic copolymer, a chain transfer agent, a photoinitiator, a UV absorber mixture and organic nanoparticles, wherein the UV absorber mixture comprises an indole-type UV absorber as a first UV absorber; and comprises at least one of a triazine-type UV absorber—2-hydroxyphenyl-s-triazine, or a benzotriazole-type UV absorber—2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol as a second UV absorber.

[0146] The adhesive film is substantially the same as the above-described adhesive film except that the adhesive film further comprises organic nanoparticles. The addition of organic nanoparticles does not affect the properties of the above-described adhesive film. The organic nanoparticles are used to increase the impact resistance of the adhesive film.

[0147] The organic nanoparticles may improve the impact resistance of an OLED panel that does not include a polarizing plate on its upper surface.

[0148] The organic nanoparticles may have an average particle size of 10 nm to 400 nm, specifically 10 nm to 300 nm, more specifically 30 nm to 280 nm, and even more specifically 50 nm to 280 nm. Within this range, the adhesive film may have good transparency (total light transmittance in the visible spectrum is 90% or more) while maintaining foldability.

[0149] The organic nanoparticles may have a refractive index of about 1.35 to about 1.70, for example about 1.40 to about 1.60. Within this range, the adhesive film may have good transparency.

[0150] Organic nanoparticles may include core-shell nanoparticles or simple nanoparticles such as bead-type nanoparticles, but are not limited thereto. When organic nanoparticles include core-shell nanoparticles, the core and shell of the organic nanoparticles may satisfy equation 4. In other words, the core and shell of the organic nanoparticles may be formed of organic materials. This core-shell particle morphology ensures a good balance between the good foldability of the adhesive film and the elasticity and flexibility of the adhesive layer.

[0151] <Equation 4>

[0152] Tg(c) <Tg(s),----(4)

[0153] Wherein Tg(c) is the glass transition temperature of the core (unit: °C), and Tg(s) is the glass transition temperature of the shell (unit: °C).

[0154] As used herein, "shell" refers to the outermost layer of an organic nanoparticle. The core may be a single spherical particle. However, the core may also include additional layers surrounding the spherical particle, as long as Equation 4 is satisfied.

[0155] Specifically, the core may have a glass transition temperature of -150°C to 10°C, specifically -150°C to -5°C, more specifically -150°C to -20°C. Within this range, the adhesive film may have viscoelasticity at low temperatures and / or room temperature. The core may include at least one of poly(alkyl acrylate), polysiloxane, or polybutadiene having a glass transition temperature within the above range.

[0156] The poly(alkyl acrylate) may include at least one of poly(methyl acrylate), poly(ethyl acrylate), poly(propyl acrylate), poly(butyl acrylate), poly(isopropyl acrylate), poly(hexyl acrylate), poly(hexyl methacrylate), poly(ethylhexyl acrylate), poly(ethylhexyl methacrylate), or polysiloxane, but is not limited thereto.

[0157] Polysiloxane can be, for example, an organosiloxane (co)polymer. The organosiloxane (co)polymer can be cross-linked or uncross-linked. Cross-linked organosiloxane (co)polymer can be used to ensure the impact resistance and colorability of the adhesive film. Here, the cross-linked organosiloxane can include cross-linked dimethylsiloxane, cross-linked methylphenylsiloxane, cross-linked diphenylsiloxane or a mixture thereof. When a copolymer of two or more organosiloxanes is used as a core, the refractive index of the organic nanoparticles can be adjusted to a range of 1.41 to 1.50.

[0158] The degree of crosslinking of the organosiloxane (co)polymer can be determined based on the degree of solubility of the organosiloxane (co)polymer in various organic solvents. As the degree of crosslinking of the organosiloxane (co)polymer increases, the solubility of the organosiloxane (co)polymer in the solvent decreases. Solvents such as acetone or toluene can be used to determine the degree of crosslinking of the organosiloxane (co)polymer. Specifically, the organosiloxane (co)polymer may have a portion that is insoluble in acetone or toluene. For example, the content of toluene-insoluble components in the organosiloxane (co)polymer may be 30% or greater.

[0159] The organosiloxane (co)polymer may also include a cross-linked alkyl acrylate polymer. The cross-linked alkyl acrylate polymer may be methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, etc. For example, the cross-linked alkyl acrylate polymer may be n-butyl acrylate or 2-ethylhexyl acrylate having a low glass transition temperature.

[0160] Specifically, the shell may have a glass transition temperature of 15° C. to 150° C., specifically 35° C. to 150° C., more specifically 50° C. to 140° C. Within this range, the organic nanoparticles may have good dispersibility in the (meth)acrylic acid copolymer. The shell may include a poly(alkyl methacrylate) having a glass transition temperature within the above range. For example, the shell may include at least one of poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate), poly(propyl methacrylate), poly(butyl methacrylate), poly(isopropyl methacrylate), poly(isobutyl methacrylate), or poly(cyclohexyl methacrylate), but is not limited thereto.

[0161] The core can be present in the organic nanoparticles in an amount of 30 wt % to 99 wt %, specifically 40 wt % to 95 wt %, more specifically 50 wt % to 90 wt %. Within this range, the adhesive film can have good foldability over a wide temperature range. The shell can be present in the organic nanoparticles in an amount of 1 wt % to 70 wt %, specifically 5 wt % to 60 wt %, more specifically 10 wt % to 50 wt %. Within this range, the adhesive film can have good foldability over a wide temperature range.

[0162] In terms of solid content, the organic nanoparticles may be present in an amount of 10 parts by weight or less, for example, 0.1 to 9 parts by weight, relative to 100 parts by weight of the (meth)acrylic copolymer or relative to 100 parts by weight of the cured product of the (meth)acrylic copolymer in the adhesive film composition. Within this range, the adhesive film may have improved impact resistance without increasing haze due to an excessive amount of the organic nanoparticles.

[0163] The organic nanoparticles may be present in the adhesive film in an amount of 0.1 to 20 wt %, specifically 0.5 to 10 wt % or 0.5 to 8 wt %. Within this range, the adhesive film may have improved impact resistance without increasing haze due to an excess of organic nanoparticles.

[0164] Organic nanoparticles may be made by any typical method known in the art, such as emulsion polymerization, suspension polymerization, and solution polymerization.

[0165] Next, an optical display device according to an embodiment of the present invention will be explained.

[0166] The optical display device includes an adhesive film according to the present invention. Preferably, the optical display device includes a light emitting diode (LED) panel and an adhesive film attached to the light emitting surface of the LED panel, wherein the adhesive film may be a post-cured product of the adhesive film according to the present invention. The post-cured product of the adhesive film has a light transmittance within the above range measured at a wavelength of 380nm or 405nm, a storage modulus within the above range measured at a temperature of 25°C to 60°C, and a peel strength within the above range measured relative to a glass plate. Therefore, the post-cured product of the adhesive film can replace the polarizing plate, thereby allowing the optical display device to not include the polarizing plate.

[0167] Next, the present invention will be described in more detail with reference to some examples. However, it should be noted that these examples are only for illustration and are not to be interpreted as limiting the present invention in any way.

[0168] Example 1

[0169] In a reactor, 100 parts by weight of a monomer mixture including 40 parts by weight of 2-ethylhexyl acrylate, 20 parts by weight of 4-hydroxybutyl acrylate, 10 parts by weight of acryloyl morpholine, 10 parts by weight of dihydrodicyclopentadienyl acrylate (DCPA) and 20 parts by weight of benzyl acrylate was placed, and then toluene was added as a solvent. Thereafter, a photoinitiator was added, and then the monomer mixture was polymerized by stirring for 30 minutes under nitrogen purge, thereby obtaining a (meth) acrylic acid copolymer derived from 2-ethylhexyl acrylate, 4-hydroxybutyl acrylate, acryloyl morpholine, dihydrodicyclopentadienyl acrylate and benzyl acrylate.

[0170] Based on the solid content, 100 parts by weight of the obtained (meth)acrylic copolymer was mixed with 0.06 parts by weight of a crosslinking agent, 0.3 parts by weight of a photoinitiator, 0.13 parts by weight of an indole-based UV absorber, 0.10 parts by weight of Tinafon 477 (BASF Chemicals Co., Ltd.), 0.15 parts by weight of a chain transfer agent, and 0.10 parts by weight of a silane coupling agent to prepare an adhesive film composition.

[0171] The prepared adhesive film composition was coated on a polyethylene terephthalate film (no release agent, thickness: 75 μm, TU73A, SKC Co., Ltd.) as a release film at a thickness of 200 μm, and then irradiated with a black light (BL) lamp at 1,000 mJ / cm 2 The film was irradiated with UV light of 315 nm to 400 nm at an injection volume of 100 nm, thereby producing an adhesive film (partially cured, UV curing conversion rate according to Equation 2: 95%, thickness: 200 μm) attached to one surface of the release film.

[0172] Example 2 to Example 6

[0173] An adhesive film was prepared in the same manner as in Example 1, except that the kind and / or content of each component was changed as listed in Table 1.

[0174] Comparative Examples 1 to 4

[0175] An adhesive film was prepared in the same manner as in Example 1, except that the kind and / or content of each component was changed as listed in Table 1.

[0176]

[0177] * In Table 1,

[0178] Crosslinker: Hexanediol diacrylate,

[0179] Photoinitiator: TPO (BASF Chemical Co., Ltd.),

[0180] Chain transfer agent: 2-ethylhexyl-3-mercaptopropionate (EHMP, TCI Co., Ltd.),

[0181] Silane coupling agent: KBM-403 (Shin-Etsu Chemical Co., Ltd.),

[0182] Organic particles: core-shell organic nanoparticles produced by emulsion polymerization (core: poly(butyl acrylate), shell: poly(methyl methacrylate), shell content: 35 wt%, core content: 65 wt%, average particle size (D50): 100 nm, refractive index: 1.48),

[0183] UA-3912 (Orient Chemical Industries Co., Ltd.): Indole UV absorber,

[0184] Tinnafin 477 (BASF Chemical Co., Ltd.): triazine UV absorber,

[0185] Tinnafin 326 (BASF Chemical Co., Ltd.): Benzotriazole UV absorber,

[0186] Tinnafin 479 (BASF Chemical Co., Ltd.): triazine UV absorber (with a different chemical structure from Tinnafin 477),

[0187] Tinnafin 460 (BASF Chemicals Co., Ltd.): triazine UV absorber (with a different chemical structure from Tinnafin 477),

[0188] Tinnafin 384-2 (BASF Chemicals GmbH): a benzotriazole UV absorber (with a different chemical structure from Tinnafin 326), and

[0189] Equation 3: (content of photoinitiator in adhesive film (in weight %)) / (total content of triazine UV absorber and benzotriazole UV absorber in adhesive film (in weight %)) (weight ratio)

[0190] The following properties were evaluated for each of the adhesive films produced in Examples 1 to 6 and Comparative Examples 1 to 4. The results are shown in Table 2.

[0191] (1) Storage modulus (unit: kPa): The storage modulus was measured using a dynamic viscoelasticity tester (DHR-3, TA Instruments) in an automatic strain mode under the conditions of an axial force of 1.0 N, a sensitivity of 0.1 N, a frequency of 1.0 Hz, and a strain of 1.0%. Specifically, an adhesive film stack having a thickness of 800 μm was prepared, and then the adhesive film stack was perforated using a perforator having a diameter of 8 mm to prepare a circular sample. The storage modulus of the sample was measured at a heating rate of 5° C. / min from -60° C. to 90° C., thereby obtaining the storage modulus values ​​of the adhesive film at 25° C. and 60° C.

[0192] (2) Peel strength relative to glass plate (unit: g-f / inch): The peel strength relative to the alkali-free glass plate was measured. After a plasma-treated PET film (NK-P50DP) was attached to one surface of each of the adhesive films prepared in Examples 1 to 6 and Comparative Examples 1 to 4, the adhesive film was cut into a size of 2.5 cm×10 cm (width×length). After the PET release film was removed from the adhesive film, the adhesive film was bonded to an alkali-free glass plate (soda-lime glass plate), thereby preparing a sample in which the alkali-free glass plate, the adhesive film, and the plasma-treated PET film were stacked in sequence. The prepared sample was fixed to a texture analyzer (TA) instrument, and then the peel strength of the stack of the adhesive film and the PET film relative to the alkali-free glass plate was measured under the conditions of a temperature of 25° C., a peel rate of 300 mm / min, and a peel angle of 180°.

[0193] (3) Light transmittance (unit: %) and transmittance b*: First, the light transmittance of the alkali-free glass plate was measured using a V650 spectrometer (JASCO Inc.) to determine a baseline. After removing the release film from the adhesive film, the adhesive film was attached to the alkali-free glass plate to prepare a sample for measuring light transmittance. The light transmittance of the prepared sample was measured using a V650 spectrometer (JASCO Inc.). The transmittance b* value was also measured in the same manner as the light transmittance.

[0194] (4) Impact resistance (unit: cm): After the adhesive film with the release film removed was attached to one surface of the OLED panel (including an organic light-emitting layer sandwiched between two substrates), a PET film (thickness: 50 μm, SH86, Sunkyung Chemical Co., Ltd.) was attached to the other surface of the adhesive film, and then the minimum height of the indentation on the PET film and / or damage to the PET film caused by the dropping of a BIC pen was measured.

[0195] Table 2

[0196]

[0197] Use a metal halide lamp at 1000 mJ / cm 2 Each of the adhesive films produced in Examples 1 to 6 and Comparative Examples 1 to 4 was irradiated with UV light of 315 nm to 400 nm at a dose of 100 nm to produce a post-cured adhesive film (completely cured, UV curing conversion rate according to equation 2: 100%, thickness: 200 μm). The properties of the post-cured adhesive film were evaluated in the same manner as above. The results are shown in Table 3.

[0198]

[0199] As can be seen from Tables 2 and 3, the light transmittance of the adhesive film according to the present invention at wavelengths of 380 nm and 405 nm is 1% or less and 3% or less, respectively. In addition, after post-curing, the light transmittance of the adhesive film according to the present invention at wavelengths of 380 nm and 405 nm is 1% or less and 3% or less, respectively, and thus it is expected to be able to protect the organic light emitting diode from UV-induced damage. In addition, despite being in a partially cured state, the adhesive film according to the present invention can also be attached to the adherend with high reliability by satisfying the storage modulus and peel strength ranges described herein, and exhibits good flexural reliability due to good viscoelasticity after post-curing.

[0200] In contrast, the adhesive films of the comparative examples failed to provide the desired benefits described herein.

[0201] It should be understood that various modifications, changes, variations and equivalent embodiments may be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. An adhesive film comprising: (Meth) acrylic acid copolymer; chain transfer agent; photoinitiator; and ultraviolet absorber mixture, The ultraviolet absorber mixture includes an indole ultraviolet absorber as a first ultraviolet absorber; and includes at least one of a triazine ultraviolet absorber, 2-hydroxyphenyl-s-triazine, and a benzotriazole ultraviolet absorber, 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, as a second ultraviolet absorber.

2. The adhesive film according to claim 1, wherein the adhesive film has a storage modulus ratio of 80% to less than 100% calculated according to Equation 1: Storage modulus ratio = (A / B) × 100, ----(1) wherein A is the storage modulus of the adhesive film measured at 25° C., in kPa, and B is the storage modulus of the adhesive film measured at 25° C. after post-curing, in kPa. 3 . The adhesive film according to claim 1 , wherein the adhesive film has a light transmittance of 1% or less at a wavelength of 380 nm. 4 . The adhesive film according to claim 1 , wherein the adhesive film has a light transmittance of 3% or less at a wavelength of 405 nm. 5 . The adhesive film according to claim 1 , wherein the adhesive film has a storage modulus of 150 kPa or less at 25° C. and a storage modulus of 100 kPa or less at 60° C.

6. The adhesive film according to claim 1, wherein the indole-based ultraviolet absorber comprises a compound represented by Formula 1: Where R 1 is hydrogen or substituted or unsubstituted C1 to C 10 alkyl, R 2 is hydrogen or a substituted or unsubstituted C6 to C 20 Aryl, R 3 is hydrogen or substituted or unsubstituted C1 to C 10 alkyl, R 4 is hydrogen, cyano, or a substituted or unsubstituted C1 to C 10 Alkyl, and R 5 is cyano or -(C=O)OR 6 , R 6 is substituted or unsubstituted C1 to C 10 Alkyl or substituted or unsubstituted C6 to C 20 Aryl. 7 . The adhesive film according to claim 1 , wherein the indole-based ultraviolet absorber is present in the adhesive film in an amount of 0.01 wt % to 10 wt %. 8 . The adhesive film of claim 1 , wherein the second ultraviolet absorber is present in the adhesive film in an amount of 0.01 wt % to 5 wt %.

9. The adhesive film according to claim 1, wherein the photoinitiator and the second ultraviolet absorber are present in the adhesive film at a weight ratio of 0.06 to 6 calculated according to Equation 3: Weight ratio = photoinitiator / second ultraviolet absorber, ----(3). 10 . The adhesive film according to claim 1 , wherein the first ultraviolet absorber and the second ultraviolet absorber are present in the ultraviolet absorber mixture in an amount of 95 wt % or more in total. 11 . The adhesive film according to claim 1 , wherein the (meth)acrylic copolymer is a copolymer of a monomer mixture including an alkyl-containing (meth)acrylic monomer, a hydroxyl-containing (meth)acrylic monomer, and a (meth)acrylic acid or vinyl monomer having a high homopolymer glass transition temperature. 12 . The adhesive film according to claim 11 , wherein the (meth)acrylic or vinyl monomer having a high homopolymer glass transition temperature has a higher homopolymer glass transition temperature than each of the alkyl-containing (meth)acrylic monomer and the hydroxyl-containing (meth)acrylic monomer. 13 . The adhesive film according to claim 11 , wherein the (meth)acrylic or vinyl monomer having a high homopolymer glass transition temperature comprises at least one of a nitrogen-containing (meth)acrylic or vinyl monomer or a cycloaliphatic group-containing (meth)acrylic or vinyl monomer. 14 . The adhesive film according to claim 11 , wherein the (meth)acrylic or vinyl monomer having a high homopolymer glass transition temperature comprises at least one of (meth)acryloylmorpholine, N-vinylpyrrolidone, dihydrodicyclopentadienyl acrylate, or isobornyl (meth)acrylate. 15 . The adhesive film according to claim 11 , wherein the monomer mixture further comprises an aromatic group-containing (meth)acrylic monomer.

16. The adhesive film according to claim 1, comprising: 100 parts by weight of the (meth)acrylic acid copolymer; 0.01 to 2 parts by weight of the chain transfer agent; 0.1 to 2 parts by weight of the photoinitiator; 0.01 to 0.5 parts by weight of the first ultraviolet absorber; and 0.01 to 5 parts by weight of the second ultraviolet absorber.

17. The adhesive film according to claim 1, further comprising: Organic nanoparticles.

18. The adhesive film according to claim 17, wherein the organic nanoparticles are core-shell type and satisfy Equation 4: Tg(c) <Tg(s),----(4) Where Tg(c) is the glass transition temperature of the core in °C, and Tg(s) is the glass transition temperature of the shell in °C.

19. The adhesive film according to claim 1, further comprising: At least one of a cross-linking agent or a silane coupling agent.

20. An optical display device comprising a post-cured product of the adhesive film according to any one of claims 1 to 19.

21. The optical display device according to claim 20, wherein the optical display device does not include a polarizing plate.

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