Adhesive film, optical component, and optical display device

Abstract

An adhesive film is provided comprising a thermoset product of an adhesive composition containing a (meth)acrylic copolymer, a curing agent, a monofunctional or mono-functional compound containing an aromatic group, a monofunctional or mono-functional compound containing a long-chain alkyl group, and an initiator, wherein the adhesive film has a peel force change rate of 1.0 or less before light irradiation, an optical member containing the same and an optical display device containing the same are provided.

Description

Technical Field

[0001] The present invention relates to an adhesive film, an optical member, and an optical display device.

Background Art

[0002] In recent years, the development of optical display devices based on organic light-emitting diodes (OLEDs) has been progressing. In particular, optical display devices based on organic light-emitting diodes having flexible characteristics have attracted attention.

[0003] A flexible panel based on an organic light-emitting diode having flexible characteristics includes plastic films such as polyimide-based films on the upper and lower portions of the panel, respectively. The flexible panel is relatively flexible compared to a liquid crystal panel and a panel based on a normal organic light-emitting diode. Therefore, scratches may occur on the surface of the flexible panel during processes such as processing, assembly, and / or inspection of the flexible panel, and a protective film for the process for protecting the panel must be temporarily adhered to the flexible panel. When there are defects such as appearance abnormalities and foreign matters during inspection of the flexible panel, the protective film for the process must have a low peeling force so that it can be easily peeled from the flexible panel. After inspection of the flexible panel, a reinforcing protective film that permanently adheres to the panel must be adhered to support the panel and protect the panel from the external environment. Therefore, it is preferable that the reinforcing protective film has a higher peeling force and reliability than the protective film for the process.

[0004] By the way, in the conventional panel manufacturing process, the process of laminating a temporary protective film for the process on the panel, the process of peeling the temporary protective film for the process from the panel, and the process of laminating a reinforcing protective film on the panel must all proceed sequentially, so the process is complicated. In addition, since the protective film for the process must be discarded after the peeling process, there is a problem that the economic efficiency and environmental friendliness are reduced.

[0005] The background art of this invention is disclosed in Japanese Patent Publication No. 5683369, among others. [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide an adhesive protective film that can be easily removed after being adhered to an optical element and can be fixed to the optical element with high reliability by a predetermined process.

[0007] Another object of the present invention is to provide an adhesive protective film that exhibits a low rate of increase in peeling force even after a long period of time has elapsed since it was adhered to an optical element, and that can be easily removed from the optical element even after a long period of time has elapsed.

[0008] Another object of the present invention is to provide an adhesive protective film that adheres to an optical element with low peeling force before light irradiation, temporarily protects the optical element, and can be easily removed from the optical element without deformation and / or damage by selectively cutting only the unnecessary portion.

[0009] Another object of the present invention is to provide an adhesive protective film that, after light irradiation and heat treatment, exhibits significantly higher peeling force compared to before light irradiation, is fixed to the optical element, and can enhance the durability of the optical element. [Means for solving the problem]

[0010] One aspect of the present invention is an adhesive film.

[0011] The adhesive film is an adhesive film comprising a thermoset product of an adhesive composition containing a (meth)acrylic copolymer, a curing agent, a monofunctional or monofunctional compound containing an aromatic group, a monofunctional or monofunctional compound containing a long-chain alkyl group, and an initiator, wherein the adhesive film has a peel force increase rate of 1.0 or less according to the following formula 1 before light irradiation.

[0012] [Formula 1] Increase rate of peeling force = (P2 - P1) / P1 (In formula 1 above, P1 is the peel force (unit: gf / inch) of the adhesive film against the adherend after leaving a test piece, manufactured by adhering the adhesive film to the adherend, at 25°C and 50% relative humidity for 30 minutes. P2 is the peel force (unit: gf / inch) of the adhesive film against the adherend after leaving a test specimen, prepared by adhering the adhesive film to the adherend, at 25°C and 50% relative humidity for 30 days.

[0013] The optical component of the present invention includes the adhesive film of the present invention.

[0014] The optical display device of the present invention includes the adhesive film of the present invention. [Effects of the Invention]

[0015] The present invention provides an adhesive protective film that can be easily removed after being adhered to an optical element and can be reliably fixed to an optical element by a predetermined process.

[0016] The present invention provides an adhesive protective film that exhibits a low rate of increase in peeling force even after a long period of time has elapsed since it was first adhered to an optical element, and that can be easily removed from the optical element even after a long period of time.

[0017] The present invention provides an adhesive protective film that adheres to an optical element with low peeling force before light irradiation, temporarily protects the optical element, and can be easily removed from the optical element without deformation and / or damage by selectively cutting only the unnecessary portion.

[0018] The present invention provides an adhesive protective film that, after light irradiation and heat treatment, exhibits significantly higher peeling strength compared to before light irradiation, allowing it to be fixed to optical elements and enhance the durability of those optical elements. [Brief explanation of the drawing]

[0019] [Figure 1]FIG. (a) shows a test piece for measuring the T-peel strength, and FIG. (b) shows the measurement drive during the measurement of the T-peel strength from the test piece.

DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in detail so that those with ordinary knowledge in the technical field to which the present invention pertains can easily implement it by referring to the accompanying drawings. The present invention can be embodied in various different forms and is not limited to the embodiments described herein.

[0021] The terms used herein are merely used to explain exemplary embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0022] As used herein, “(meth)acrylic” can mean acrylic and / or methacrylic.

[0023] As used herein, “copolymer” may include polymers or resins.

[0024] As used herein, “glass transition temperature” can mean the glass transition temperature (Tg) measured using a TA Instrument DSC Discovery for the monomer or compound being measured. Specifically, after raising the temperature of the homopolymer of the monomer or compound being measured to 180° C. at a heating rate of 20° C. / min, gradually cooling it to -100° C., and then raising the temperature to 100° C. at a heating rate of 10° C. / min to obtain data of the endothermic transition curve, the inflection point of the endothermic transition curve can be determined as the glass transition temperature.

[0025] As used herein, “peel strength” can be a value measured at 25° C. unless otherwise specified.

[0026] In this specification, the "melting point (Tm)" referred to in "compounds containing one or more long-chain alkyl groups" may mean the melting point (Tm) measured using TA Instrument's DSC Discovery. Specifically, the homopolymer monomer to be measured can be heated to 180°C at a heating rate of 20°C / min, then gradually cooled to -100°C, and then heated to 100°C at a heating rate of 10°C / min. Data can then be obtained from the endothermic transition curve, and the inflection point of the endothermic transition curve can be determined as the melting point.

[0027] In this specification, "weight-average molecular weight" can be determined using gel permeation chromatography as a polystyrene equivalent.

[0028] In this specification, when a numerical range is described, "X~Y" means X or greater and Y or less (X ≤ and ≤ Y).

[0029] The adhesive film of the present invention exhibits high temporal stability of peel strength before light irradiation, possesses both photosensitivity and heat sensitivity, and shows a significantly increased peel strength after light irradiation and heat treatment. Before light irradiation, the adhesive film can adhere to the substrate with low peel strength.

[0030] The adhesive film is in its pre-light irradiation state and is an adhesive film with low peel strength (also called "initial peel strength"). Before light irradiation, the adhesive film has an appropriate range of peel strength to the adherend, but adheres to the adherend with low peel strength, temporarily protects the adherend, and can be easily removed from the adherend without deformation and / or damage to the adherend. Therefore, the adhesive film can be used as an adhesive protective film. This is different from conventional photocurable adhesive compositions that form adhesive films, which have no peel strength at all before light irradiation, and the coatings formed with the aforementioned photocurable adhesive compositions cannot provide any temporary protection to the adherend.

[0031] In one specific example, the adhesive film may have an initial peel force from the adherend greater than 0 gf / inch and less than or equal to 100 gf / inch, such as 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 gf / inch, for example, 10 gf / inch to 100 gf / inch, 20 gf / inch to 70 gf / inch, 30 gf / inch to 70 gf / inch, or 30 gf / inch to 60 gf / inch. Within this range, the adhesive film can be easily removed from the adherend without deformation and / or damage to the adherend. The "initial peel force" can be measured by the method described below.

[0032] In this specification, "adheren" may include, for example, polyester films such as polyimide (PI) films, polycarbonate (PC) films, polyethylene naphthalate (PEN) films, polyethylene terephthalate (PET) films, polyethersulfone films, and polyurethane films as plastic films.

[0033] In one specific example, the adherend may be a polyimide film. The "polyimide film" may be a polymer film provided by a polymerization reaction of a precursor polyamic acid, containing imide groups and aromatic groups within its repeating units. The polyimide film has excellent mechanical properties and can be widely used as a substrate for flexible OLED panels. For example, it may be polyimide film GF200 (SKCKOLON, thickness: 50 μm).

[0034] In one specific example, the adherend can be part of an optical element. When the adhesive film adheres to the adherend, even after a long period of time, the adhesive film can be removed from the adherend without deformation and / or damage to the optical element. After light irradiation and heat treatment, the adhesive film is fixed to the adherend with significantly higher peeling force compared to before light irradiation, thereby protecting the optical element and increasing its durability. For example, the adherend may be the aforementioned plastic film or a flexible substrate containing the aforementioned plastic film.

[0035] In one specific example, the optical element is an optical element included in a foldable, flexible, or rollable display device, and may, for example, be a panel for a foldable, flexible, or rollable optical display device. In one specific example, the optical element may be a panel for an optical display device including the aforementioned flexible substrate.

[0036] The adhesive film, in its state before light irradiation, exhibits a low rate of increase in peeling force even after a long period of time has elapsed since adhering to the substrate, and can be easily removed from the substrate without deformation and / or damage to the substrate, even after a long period of time.

[0037] The adhesive film has a peel force change rate of 1.0 or less before light irradiation, as shown in Formula 1 below. Within this range, even after a long time has passed since adhesion to the substrate, the peel force to the substrate remains low, and it can be easily removed from the substrate. For example, the peel force change rate in Formula 1 below can be 0.01 to 1.0, for example, 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, for example, 0.01 to 0.5, 0.05 to 0.3.

[0038] [Formula 1] Change rate of peeling force = (P2 - P1) / P1 (In formula 1 above, P1 is the peel force (unit: gf / inch) of the adhesive film against the adherend after leaving a test piece, manufactured by adhering the adhesive film to the adherend, at 25°C and 50% relative humidity for 30 minutes. P2 is the peel force (unit: gf / inch) of the adhesive film against the adherend after a test specimen, manufactured by adhering the adhesive film to the adherend, has been left at 25°C and 50% relative humidity for 30 days.

[0039] In one specific example, in formula 1, P1 (initial peeling force) can be greater than 0 gf / inch and less than or equal to 100 gf / inch, for example, 10 gf / inch to 100 gf / inch, 20 gf / inch to 70 gf / inch, 30 gf / inch to 70 gf / inch, or 30 gf / inch to 60 gf / inch. In another specific example, in formula 1, P2 can be greater than P1 and greater than 0 gf / inch and less than or equal to 170 gf / inch, for example, 10 gf / inch to 100 gf / inch or 30 gf / inch to 85 gf / inch.

[0040] The adhesive film is a peel-strength-enhancing adhesive film in which the peel strength against the adherend increases significantly after light irradiation and heat treatment compared to before light irradiation. After light irradiation and heat treatment, the adhesive film exhibits significantly increased peel strength, adheres to the adherend, enhances the adherend's durability, and provides permanent protection. Therefore, the adhesive film simultaneously provides a temporary protective film for the process and a reinforcing protective film for permanent protection, achieving process simplification, cost-effectiveness, and environmental friendliness. The temporary protective film for the process is a film that temporarily adheres to the adherend and is then removed, thus providing temporary protection. The reinforcing protective film may be a film that permanently adheres to the adherend, protects the adherend from the external environment, and is not removed from the adherend.

[0041] In particular, the adhesive film showed a significant increase in peeling force against the adherend after light irradiation and heat treatment compared to before light irradiation. While the peeling force against the adherend can be increased simply by irradiating the adhesive film with light, the present invention significantly increases the peeling force against the adherend compared to light irradiation alone by adding heat treatment, which significantly improves the durability of the adherend and the optical element equipped with the adherend.

[0042] The adhesive film can be used as a reinforcing protective film. In one specific example, the reinforcing protective film may mean a protective film that is laminated on at least one surface of a flexible panel to protect the flexible panel from external impacts, etc.

[0043] In one specific example, the adhesive film has a peel force increase rate of 10 or more as shown in Formula 2 below. Within this range, the film adheres to the substrate, is irradiated with light, and then heat-treated, thereby significantly enhancing the protective and adhesive effects on the substrate by adhering with high peel force and high reliability.

[0044] [Formula 2] Increase in peeling force = P3 / P1 (In formula 2 above, P1 is the peel force (unit: gf / inch) of the adhesive film against the adherend after leaving a test piece, manufactured by adhering the adhesive film to the adherend, at 25°C and 50% relative humidity for 30 minutes. P3 is the peel force (unit: gf / inch) of the adhesive film against the substrate after a test specimen, prepared by adhering the adhesive film to the substrate, is left at 25°C and 50% relative humidity for 30 minutes, irradiated with light, and then heat-treated.

[0045] In one specific example, the peeling force increase rate in formula 2 can be 10 to 200, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, for example, 10 to 50, 10 to 20. Within this range, it is possible to easily ensure the initial peeling force of the adhesive film and the peeling force after light irradiation and subsequent heat treatment.

[0046] In formula 2, the adhesive film can have a peel force P1 (initial peel force) greater than 0 gf / inch and less than or equal to 100 gf / inch, for example, 10 gf / inch to 100 gf / inch, 20 gf / inch to 70 gf / inch, or 30 gf / inch to 70 gf / inch. Within this range, it can be easily removed from the adherend without deformation and / or damage to the optical component, and after light irradiation and then heat treatment, the peel force can be easily increased.

[0047] The adhesive film has a peel strength of 500 gf / inch or more, for example, 500 gf / inch to 2000 gf / inch or 500 gf / inch to 1000 gf / inch, as indicated by formula 2, P3 (peel strength after light irradiation followed by heat treatment). Within this range, the adhesive film can adhere to the substrate with high peel strength and high reliability, thereby improving the adhesion effect to the substrate and the durability of the optical element.

[0048] P3 is a value measured after irradiating test pieces of adhesive film and adherend with light and then heat-treating them. In this invention, after light irradiation and heat treatment, the peeling force of the adhesive film after light irradiation and heat treatment is increased by the physical changes of the adhesive film due to the improvement of the cohesive force and / or modulus of the adhesive film.

[0049] The aforementioned "light irradiation" is performed at wavelengths of 280-430 nm, for example, 350-390 nm, 380-390 nm, and 385 nm at a concentration of 1000 mJ / cm². 2 This may include irradiating with UV irradiation energy. UV irradiation can be performed using one or more of the following: UV LED, high-pressure mercury lamp, or metal halide lamp.

[0050] The aforementioned "heat treatment" may include leaving the area at a constant temperature of 50°C for 20 minutes.

[0051] In one specific example, the adhesive film can have a peel force increase rate of 3 or more and less than 10 in the following formula 3: Within this range, it adheres to the substrate, and after light irradiation, adheres to the substrate with high peel force and high reliability, thereby significantly enhancing the protective and adhesive effect on the substrate.

[0052] [Formula 3] Increase in peeling force = P4 / P1 (In formula 3 above, P1 is the peel force (unit: gf / inch) of the adhesive film against the adherend after leaving a test piece, manufactured by adhering the adhesive film to the adherend, at 25°C and 50% relative humidity for 30 minutes. P4 is the peeling force (unit: gf / inch) of the adhesive film against the adherend after a test specimen, manufactured by adhering the adhesive film to the adherend, is left at 25°C and 50% relative humidity for 30 minutes and then irradiated with light.

[0053] For example, the peeling force increase rate in formula 3 can be 3-9, 4-8, or 5-7. The "light irradiation" is 1000 mJ / cm² at wavelengths of 280-430 nm, for example, 350-390 nm, 380-390 nm, and 385 nm. 2 This may include irradiating with UV irradiation energy. UV irradiation can be performed using one or more of the following: UV LED, high-pressure mercury lamp, or metal halide lamp.

[0054] The adhesive film is formed from an adhesive composition comprising a (meth)acrylic copolymer, a curing agent, a monofunctional or monofunctional compound containing an aromatic group, a monofunctional or monofunctional compound containing a long-chain alkyl group, and an initiator.

[0055] In one specific example, the adhesive film may be a thermoset product of an adhesive composition comprising a (meth)acrylic copolymer, a curing agent, a monofunctional or mono-functional compound containing an aromatic group, a monofunctional or mono-functional compound containing a long-chain alkyl group, and an initiator.

[0056] In one specific example, the adhesive film may have an adhesive film matrix, which is a thermoset product of a (meth)acrylic copolymer and a curing agent, in which a compound containing one or more aromatic groups, a compound containing one or more long-chain alkyl groups, and an initiator are dispersed.

[0057] (meth)acrylic copolymer (Meth)acrylic copolymers can form the matrix of an adhesive film and, upon curing with a curing agent, provide the initial peel strength of the adhesive film. Furthermore, (meth)acrylic copolymers, together with monofunctional or monofunctional compounds containing aromatic groups and monofunctional or monofunctional compounds containing long-chain alkylene groups, can contribute to improving the cohesive strength of the adhesive film after light irradiation and heat treatment.

[0058] (Meth)acrylic copolymers can have a glass transition temperature (Tg) of -10°C or lower, for example, -20°C or lower, or -60°C to -20°C. Within this range, they can contribute to providing wettability (adhesion) to the adherend and the initial peel strength of the adhesive film. After light irradiation and heat treatment, the peel strength can be increased by suppressing shrinkage of the adhesive film through adjustment of the glass transition temperature of the adhesive film.

[0059] The (meth)acrylic copolymer may have a weight-average molecular weight of 500,000 g / mol or more, specifically 600,000 to 2,500,000 g / mol. Within this range, it can contribute to providing wettability to the adherend and initial peel strength of the adhesive film.

[0060] The (meth)acrylic copolymer may include a copolymer of monomer mixtures containing alkyl group-containing (meth)acrylic monomers and hydroxyl group-containing (meth)acrylic monomers.

[0061] The alkyl group-containing (meth)acrylic monomer forms the matrix of the adhesive film and may include unsubstituted linear or branched alkyl group-containing (meth)acrylic acid esters having 1 to 20 carbon atoms, for example, 1 to 10 carbon atoms or 1 to 6 carbon atoms.

[0062] For example, the alkyl group-containing (meth)acrylic monomer may contain one or more of the following: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, iso-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, and lauryl (meth)acrylate.

[0063] Alkyl-containing (meth)acrylic monomers may be present in the monomer mixture at concentrations of 85 mol% to 99.5 mol%, specifically 90 mol% to 99 mol%, or 95 mol% to 98 mol%. Within this range, they may be effective in providing wettability to the adherend and initial peel strength of the adhesive film.

[0064] A hydroxyl group-containing (meth)acrylic monomer may be a (meth)acrylate containing one or more hydroxyl groups. For example, a hydroxyl group-containing (meth)acrylate may include an alkyl group-containing (meth)acrylic acid ester having 1 to 20 carbon atoms, specifically 2 to 11 carbon atoms, substituted with one or more hydroxyl groups. For example, the hydroxyl group-containing (meth)acrylic monomer may be one or more of the following: 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, 1-chloro-2-hydroxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, 1,6-hexanediol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, neopentyl glycol mono(meth)acrylate, trimethylolpropanedi(meth)acrylate, trimethylolethanedi(meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, 4-hydroxycyclopentyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, and cyclohexanedimethanol mono(meth)acrylate.

[0065] Hydroxyl group-containing (meth)acrylic monomers may be present in monomer mixtures in amounts of 0.1 mol% to 15 mol%, specifically 0.5 mol% to 15 mol%, 0.5 mol% to 5 mol%, 2 mol% to 10 mol%, and 1 mol% to 5 mol%. Within these ranges, they may be effective in imparting cohesive force to the adhesive film and providing initial peeling force to the adhesive film.

[0066] The monomer mixture may further contain a carboxylic acid group-containing monomer. The carboxylic acid group-containing monomer can contribute to increasing the glass transition temperature of the (meth)acrylic copolymer and providing initial tackiness. The carboxylic acid group-containing monomer may, but is not limited to, (meth)acrylic acid.

[0067] The monomer containing the carboxylic acid group may be present in the monomer mixture in amounts of 0 to 5 mol%, specifically 0.05 mol% to 5 mol%, or 0.1 mol% to 5 mol%. Within this range, it may be effective in imparting cohesive force to the adhesive film and providing the initial peel force of the adhesive film.

[0068] The monomer mixture may include (meth)acrylic monomers having a homopolymer glass transition temperature of -80°C to 0°C, specifically -60°C to -20°C. Within this range, it may be possible to easily produce (meth)acrylic copolymers having the aforementioned glass transition temperature range.

[0069] The monomer mixture may contain, but is not limited to, methyl acrylate, acrylic acid, methacrylic acid, etc.

[0070] In one specific example, the monomer mixture does not necessarily have to contain monomers having aromatic groups. The (meth)acrylic copolymer may be a non-aromatic (meth)acrylic copolymer. An adhesive film formed from a composition containing a (meth)acrylic copolymer formed from a monomer mixture containing monomers having aromatic groups may have difficulty reaching the peel strength increase rate of Formula 2 described above.

[0071] In one specific example, the sum of alkyl group-containing (meth)acrylic monomers, hydroxyl group-containing (meth)acrylic monomers, and carboxylic acid group-containing monomers may be present in the monomer mixture in an amount of 95 mol% or more, for example, 95-100 mol% or 100 mol%. Within this range, the effects of the present invention can be easily realized.

[0072] (Meth)acrylic copolymers can be produced by polymerizing monomer mixtures using conventional polymerization methods. These polymerization methods may include conventional methods known to those skilled in the art. For example, (meth)acrylic copolymers can be produced by adding an initiator to a monomer mixture, followed by conventional copolymer polymerization, such as suspension polymerization, emulsion polymerization, or solution polymerization. The polymerization temperature can be 60°C to 70°C, and the polymerization time can be 4 to 8 hours. Conventional initiators can be used, including azo polymerization initiators and / or peroxides such as benzoyl peroxide or acetyl peroxide.

[0073] hardening agent The curing agent can contribute to providing the initial peel strength of the adhesive film by thermally curing the (meth)acrylic copolymer to form the matrix of the adhesive film.

[0074] The curing agent may contain one or more of the following as a thermosetting agent: isocyanate-based curing agents, metal chelate-based curing agents, carbodiimide-based curing agents, aziridine-based curing agents, and epoxy-based curing agents.

[0075] In one specific example, the curing agent may include an isocyanate-based curing agent alone or a mixture of an isocyanate-based curing agent and a metal chelating curing agent. The aforementioned mixture may further facilitate the realization of the effects of the present invention. For example, it may include a mixture of an isocyanate-based curing agent and a metal chelating curing agent.

[0076] The isocyanate-based curing agent may include two or more functional isocyanate-based curing agents, specifically, two- to six-functional isocyanate-based curing agents. In one specific example, the isocyanate-based curing agent may include one or more of the following: xylene diisocyanate (XDI) containing m-xylene diisocyanate, methylenebis(phenyl isocyanate) (MDI) containing 4,4'-methylenebis(phenyl isocyanate), naphthalene diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, or adducts thereof. For example, the adduct may be a trimethylolpropane adduct of tolylene diisocyanate, a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate, a trimethylolpropane adduct of xylene diisocyanate, an isocyanurate of tolylene diisocyanate, an isocyanurate of hexamethylene diisocyanate, or an isocyanurate of isophorone diisocyanate. The isocyanate-based curing agent may include one or more of the above compositions.

[0077] The isocyanate curing agent may be included in an amount of 5 parts by weight or less per 100 parts by weight of the (meth)acrylic copolymer, for example, 0.001 to 3 parts by weight or 0.01 to 2 parts by weight. Within this range, the reliability of the adhesive film can be improved. Preferably, the isocyanate curing agent may be included in an amount of 0.3 to 2 parts by weight per 100 parts by weight of the (meth)acrylic copolymer. Within this range, the reliability of the adhesive film can be improved, and the effects of the present invention can be easily realized.

[0078] The metal chelating curing agent can be a conventional metal chelating curing agent, and may include curing agents containing metals such as aluminum, titanium, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. For example, the metal chelating curing agent may include one or more of the following: aluminum ethyl acetacetate diisopropylate, aluminum tris(ethyl acetate), alkyl acetacetate aluminum diisopropylate, aluminum isopropylate, mono-sec-butoxyaluminum diisopropylate, aluminum-sec-butyrate, aluminum ethylacetate, tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, titanium acetylacetonate, titanium octylene glycolate, titanium tetraacetylacetonate, titanium ethyl acetate, polyhydroxytitanium stearate, and aluminum acetylacetonate.

[0079] The metal chelating curing agent may be included in an amount of 3 parts by weight or less per 100 parts by weight of the (meth)acrylic copolymer, for example, 0.001 to 1 part by weight or 0.01 to 1 part by weight. Within this range, further effects can be obtained without affecting the effect of the adhesive film of the present invention. Preferably, the metal chelating curing agent may be included in an amount of 0.2 to 1 part by weight per 100 parts by weight of the (meth)acrylic copolymer. Within this range, the reliability of the adhesive film can be increased, and the effects of the present invention can be easily realized.

[0080] The curing agent may be included in an amount of 0.01 to 8 parts by weight, for example, 0.01 to 3 parts by weight or 0.5 to 3 parts by weight, per 100 parts by weight of the (meth)acrylic copolymer. Within this range, the reliability of the adhesive film can be improved. In one specific example, the curing agent may be included in an amount of 0.5 to 3 parts by weight per 100 parts by weight of the (meth)acrylic copolymer. Within this range, the effects of the adhesive film of the present invention can be easily realized.

[0081] Compounds containing one or more aromatic groups A compound containing one or more aromatic groups has one or more functional groups that can react (e.g., cure) with an initiator. The "functional group" may mean a vinyl group or a (meth)acrylate group. In one specific example, a compound containing one or more aromatic groups may be a UV-reactive compound containing one or more aromatic groups.

[0082] Compounds containing one or more aromatic groups can increase the cohesive force of adhesive films after light irradiation. Therefore, when an adhesive film is photocured while it is adhered to the surface of an object, the adhesive film adheres to the object with even greater peeling force, thereby increasing the peeling force of the adhesive film.

[0083] Compounds containing one or more aromatic groups are photosensitive and can enhance the peeling force of adhesive films through physical changes caused by light irradiation.

[0084] The aromatic group-containing monofunctional or greater compound is an aromatic group-containing monofunctional or greater monomer, and it is preferable that the glass transition temperature of the monomer homopolymer is within a predetermined range compared to the glass transition temperature of the (meth)acrylic copolymer. Through this, even if the adhesive film hardens due to light irradiation, the shrinkage of the adhesive film can be suppressed, thereby increasing the peeling force after light irradiation.

[0085] In one specific example, the glass transition temperature of a homopolymer of a compound containing one or more aromatic groups is higher than that of the (meth)acrylic copolymer, and the difference is preferably 20°C or more, for example, 20°C to 120°C or 40°C to 100°C. Within this range, an increase in peeling strength after light irradiation can be expected.

[0086] Compounds containing one or more aromatic groups can have a glass transition temperature of 0°C or higher for homopolymers, for example, 0°C to 50°C or 5°C to 50°C. Within this range, the glass transition temperature is higher compared to (meth)acrylic copolymers, and an effect of improving the peeling strength of adhesive films due to improved cohesive force after light irradiation can be obtained.

[0087] A compound containing one or more aromatic groups may have one or more aromatic groups. A UV-reactive compound having one or more aromatic groups can increase the peeling force of formula 2.

[0088] Compounds containing one or more aromatic groups may include, but are not limited to, the compound of the following chemical formula 1.

[0089] [ka] ...chemical formula 1 (In the above chemical formula 1, R 1 is a hydrogen or methyl group, s is an integer between 0 and 10. R 2 This is a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 50 carbon atoms. T is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, or a substituted or unsubstituted alkylene oxy group having 1 to 6 carbon atoms.

[0090] In this specification, "substituted or unsubstituted" means that one or more hydrogen atoms are substituted with a C1-C10 alkyl group, a C1-C10 thioalkyl group, a C1-C10 alkoxy group, a halogen (F, Cl, Br, or I), a C3-C10 cycloalkyl group, or a C6-C20 aryl group.

[0091] Specifically, R 2Examples include substituted or unsubstituted phenoxy groups, benzyl groups, phenyl groups, biphenyl groups, terphenyl groups, naphthyl groups, and the like.Specifically, compounds containing one or more aromatic groups include phenoxy(meth)acrylate, 2-ethylphenoxy(meth)acrylate, 2-phenoxyethyl(meth)acrylate (ethylene glycol phenyl ether(meth)acrylate), benzyl(meth)acrylate, phenyl(meth)acrylate, 2-ethylthiophenyl(meth)acrylate, 2-phenylethyl(meth)acrylate, 3-phenylpropyl(meth)acrylate, 4-phenylbutyl(meth)acrylate, and 2-(2-methylphenyl)ethyl(meth)acrylate. 2-(3-methylphenyl)ethyl(meth)acrylate, 2-(4-methylphenyl)ethyl(meth)acrylate, 2-(4-propylphenyl)ethyl(meth)acrylate, 2-(4-(1-methylethyl)phenyl)ethyl(meth)acrylate, 2-(4-methoxyphenyl)ethyl(meth)acrylate, 2-(4-cyclohexylphenyl)ethyl(meth)acrylate, 2-(2-chlorophenyl)ethyl(meth)acrylate, 2-(3-chlorophenyl)ethyl(meth)acrylate 2-(4-chlorophenyl)ethyl (meth)acrylate, 2-(4-bromophenyl)ethyl (meth)acrylate, 2-(3-phenylphenyl)ethyl (meth)acrylate, orthobiphenyl (meth)acrylate, metabiphenyl (meth)acrylate, parabiphenyl (meth)acrylate, 2,6-terphenyl (meth)acrylate, orthoterphenyl (meth)acrylate, metaterphenyl (meth)acrylate, paraterphenyl (meth)acrylate, 4-(4-methylphenyl)phenyl (meth)acrylate It may contain one or more of the following: acrylate, 4-(2-methylphenyl)phenyl(meth)acrylate, 2-(4-methylphenyl)phenyl(meth)acrylate, 2-(2-methylphenyl)phenyl(meth)acrylate, 4-(4-ethylphenyl)phenyl(meth)acrylate, 4-(2-ethylphenyl)phenyl(meth)acrylate, 2-(4-ethylphenyl)phenyl(meth)acrylate, and 2-(2-ethylphenyl)phenyl(meth)acrylate, and may contain one or more of these individually or as a mixture of two or more.

[0092] In one specific example, the aromatic group-containing compound with one or more functionalities may include one or more of the following: benzyl (meth)acrylate, ethylene glycol phenyl ether (meth)acrylate, phenyl benzyl (meth)acrylate, ethoxylated phenyl (meth)acrylate including ethoxylated phenyl acrylate (especially Phenyl(EO)1 acrylate, Phenyl(EO)2 acrylate), ethoxylated phenylphenol (meth)acrylate including ethoxylated phenylphenol acrylate (o-Phenylphenol(EO) acrylate), phenoxy benzyl (meth)acrylate including phenoxy benzyl acrylate, biphenylmethyl (meth)acrylate including biphenylmethyl acrylate, naphthyl (meth)acrylate including 1-naphthyl acrylate, etc.

[0093] A compound containing one or more aromatic groups may be included in an amount of 1 to 25 parts by weight, for example, 1 to 20 parts by weight or 5 to 20 parts by weight, per 100 parts by weight of the (meth)acrylic copolymer. Within this range, it can contribute to increasing the peel strength of the adhesive film after light irradiation.

[0094] Long-chain alkyl group-containing monofunctional or more compounds Compounds containing one or more long-chain alkyl groups are photosensitive and can increase the peeling force of adhesive films through physical changes caused by light irradiation. Unlike compounds containing one or more aromatic groups, compounds containing one or more long-chain alkyl groups are heat-sensitive and can maximize the increase in peeling force through heat treatment. That is, compounds containing one or more long-chain alkyl groups themselves have no melting point. However, compounds containing one or more long-chain alkyl groups are converted into polymer forms by light irradiation and acquire a melting point within a predetermined range. At temperatures below the melting point, the long-chain alkyl groups crystallize in the adhesive film, providing low peeling force. However, when heat-treated at a temperature above the melting point while attached to an adherend, the long-chain alkyl groups provide fluidity, thereby increasing the peeling force. In one specific example, the melting point can be 30-60°C, for example, 30-50°C or 40-50°C. Within this range, the effects of the present invention can be easily realized. Here, "light irradiation" can be under the same conditions as described above.

[0095] Furthermore, compounds containing one or more long-chain alkyl groups can contribute to reducing the rate of increase in peel force of Formula 1 by providing thermal stability to the adhesive film through the presence of long-chain alkyl groups.

[0096] A compound containing one or more long-chain alkyl groups has one or more functional groups that can react (e.g., cure) with an initiator. The "functional group" may mean a vinyl group or a (meth)acrylate group. In one specific example, a compound containing one or more long-chain alkyl groups may be a UV-reactive monomer containing one long-chain alkyl group.

[0097] In one specific example, a compound containing one or more long-chain alkyl groups may be a non-aromatic compound that does not have an aromatic group.

[0098] Compounds containing one or more long-chain alkyl groups can be selected and applied if they provide the aforementioned melting point after light irradiation. For example, a compound containing one or more long-chain alkyl groups may be a (meth)acrylate containing a long-chain alkyl group, in which case the long-chain alkyl group can be an unsubstituted alkyl group with 12 or more carbon atoms, for example, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, for example, a linear or branched alkyl group with 12-30 or 12-28 carbon atoms. Here, "number of carbon atoms" refers to the number of carbon atoms forming the main chain in the ester moiety of the (meth)acrylate.

[0099] For example, a monofunctional compound containing a long-chain alkyl group may contain one or more of the following: stearyl (meth)acrylate, behenyl (meth)acrylate, and cetyl (meth)acrylate.

[0100] A compound containing one or more long-chain alkyl groups may be included in amounts of 1 to 50 parts by weight per 100 parts by weight of the (meth)acrylic copolymer, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 parts by weight, for example, 1 to 10 parts by weight or 1 to 5 parts by weight. Within the above range, it can contribute to increasing the peel strength of the adhesive film after heat treatment.

[0101] Initiator The initiator can provide a physical change in the adhesive film upon light irradiation by curing a monofunctional compound containing an aromatic group. The initiator comprises one or more photoradical initiators and cationic photoinitiators, and may further contain a thermal initiator.

[0102] In one specific example, the initiator may include a photoinitiator having the maximum absorption wavelength within the range of irradiation wavelengths applied during the aforementioned light irradiation. For example, the initiator may have the maximum absorption wavelength in the range of 280 nm to 430 nm. Within this range, the photocuring effect of a monofunctional or more aromatic group-containing compound can be obtained by light irradiation. Specifically, the photoinitiator may include, but is not limited to, phosphorus-based initiators and ketone-based initiators.

[0103] The initiator may be present in an amount of 0.01 to 7.5 parts by weight, for example, 0.03 to 4.5 parts by weight or 0.1 to 1 part by weight, per 100 parts by weight of the (meth)acrylic copolymer. Within this range, a uniform curing effect on aromatic group-containing monofunctional or greater compounds by light irradiation and an effect of preventing a decrease in the transparency of the adhesive film due to the remaining amount of initiator can be provided.

[0104] The adhesive composition may further contain a curing accelerator.

[0105] Curing accelerators can assist the curing reaction of adhesive films and further enhance the cohesive force of the adhesive layer. Curing accelerators may include conventional curing accelerators known to those skilled in the art. Examples include tin-based metal compounds, zinc-based metal compounds, amine compounds, titanium-based metal compounds, bismuth-based metal compounds, and aluminum-based metal compounds. Among these, tin-based metal compounds are preferred. For example, tetravalent or divalent organotin compounds such as dibutyltin dilaurate, bis-acetylacetonate-dibutyltin, dibutyltin dimaleate, and dimaleate tin may be included, but are not limited to these.

[0106] The curing accelerator may be included in an amount of 0.001 to 3 parts by weight per 100 parts by weight of the (meth)acrylic copolymer. Within this range, it is possible to increase the curing speed of the adhesive film and contribute to improving its cohesive strength.

[0107] The adhesive composition may further contain a silane coupling agent.

[0108] Silane coupling agents can further enhance the peeling force of adhesive films. The silane coupling agent may include conventional silane coupling agents known to those skilled in the art. For example, the silane coupling agent may include, but is not limited to, epoxy group-containing silane coupling agents such as glycidoxypropyltrimethoxysilane and glycidoxypropylmethyldimethoxysilane.

[0109] The silane coupling agent may be included in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the (meth)acrylic copolymer. Within this range, further improvement in peel strength can be expected.

[0110] The adhesive composition may further contain additives. These additives are those contained in the adhesive film and may include common additives known to those skilled in the art. For example, the additives may include, but are not limited to, one or more of the following: pigments, ultraviolet absorbers, antioxidants, leveling agents, antistatic agents, retarders, catalysts, and rework agents.

[0111] The adhesive composition may further contain a solvent. The solvent can enhance the coatability of the adhesive composition, resulting in an adhesive film with a thin thickness and a uniform surface. The solvent may include common types known to those skilled in the art. For example, the solvent may include, but is not limited to, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, toluene, etc. In one specific example, the adhesive composition may contain 15% to 40% by weight of solids in the adhesive film, specifically 20% to 30% by weight. Within this range, the composition exhibits excellent coatability.

[0112] The adhesive film can have a haze of 5% or less in the visible light region (e.g., wavelength 380nm to 780nm), specifically 0.1% to 2%, and a total light transmittance of 80% or more, specifically 85% to 95%. Within this range, it has good optical transparency and can be used in optical display devices.

[0113] The thickness of the adhesive film can be 200 μm or less, specifically, more than 0 μm and 100 μm or less, and more specifically, 5 μm to 50 μm. Within this range, it can contribute to providing a protective effect on the flexible panel.

[0114] The adhesive film can be manufactured by applying the adhesive composition to one surface of a release film, drying it, and then curing (or heat-curing) it. The drying can be carried out by treating it at 50°C to 100°C for 1 minute to 30 minutes. The curing (or heat-curing) can be carried out by treating it at 30°C to 70°C for 1 day to 10 days.

[0115] The optical component of the present invention includes the adhesive film of the present invention.

[0116] In one specific example, the optical member includes an optical element and an adhesive film laminated on at least one surface of the optical element, and the adhesive film may include an adhesive film according to an embodiment of the present invention.

[0117] In one specific example, the optical component may include an optical element on which an adherend is laminated on its lowest surface, and an adhesive film according to an embodiment of the present invention laminated on the lower surface of the adherend.

[0118] The optical element is an optical element included in a foldable, flexible, or rollable display device, and may, for example, be a panel for a foldable, flexible, or rollable optical display device.

[0119] The panel for the optical display device may include a flexible substrate. The flexible substrate can serve to support optical elements such as organic light-emitting diodes. The flexible substrate may include, as a plastic film, polyester films including polyimide films, polyethylene terephthalate films, polyethylene naphthalate films, polycarbonate films, polyethersulfone films, etc.

[0120] The optical elements may further include basic elements for optical display devices that are laminated on the upper surface of a flexible substrate and provide certain optical functions in an optical display device, such as light emission, polarization, optical compensation, display image quality improvement, and / or conductivity. Examples of basic elements for optical display devices include OLED elements, window films, windows, polarizers, color filters, phase difference films, elliptic polarizing films, reflective polarizing films, anti-reflective films, compensation films, brightness enhancement films, alignment films, light diffusion films, glass shatterproof films, surface protection films, OLED element barrier layers, plastic LCD substrates, transparent electrode films containing ITO (indium tin oxide), FTO (fluorinated tin oxide), AZO (aluminum dopped zinc oxide), CNT (carbon nanotube), Ag nanowires, graphene, etc.

[0121] The optical element may further include a protective layer laminated on the lower surface of the flexible substrate.

[0122] The protective layer is not particularly limited as long as it is optically transparent and can provide flexibility. For example, the protective layer may include a polyester film containing polyethylene terephthalate film, polyethylene naphthalate film, polycarbonate film, polyethersulfone film, etc.

[0123] In one specific example, the optical component may include an optical display panel including a flexible substrate, the adhesive film laminated on the lower surface of the flexible substrate, and a protective layer laminated on the lower surface of the adhesive film.

[0124] Optical components can be manufactured by modifying conventional methods known to those skilled in the art. For example, an optical component can be manufactured by preparing a flexible panel including a flexible substrate, bonding a laminate of adhesive film and protective layer to the lower surface of the flexible substrate, and, if there are no defects such as appearance abnormalities or foreign matter in the flexible substrate or flexible panel, bonding the laminate of adhesive film and protective layer to the flexible panel with high peeling force by performing the aforementioned light irradiation. However, if there are the aforementioned appearance abnormalities or defects, the laminate of adhesive film and protective layer can be peeled off from the flexible panel.

[0125] The optical display device of the present invention includes the adhesive film of the present invention.

[0126] The optical display device may include organic light-emitting element display devices, liquid crystal display devices, and the like. The optical display device may also include flexible display devices. However, the optical display device may also include non-flexible display devices. [Examples]

[0127] The configuration and operation of the present invention will be described in more detail below based on preferred embodiments of the present invention. However, these are presented as preferred examples of the present invention and should not be construed as limiting the present invention in any way.

[0128] Manufacturing Example 1 Ethyl acetate was added as a solvent to a 1 L reactor equipped with a cooling device to facilitate temperature control and to reflux nitrogen gas. 100 parts by weight of a monomer mixture containing 85 mol% n-butyl acrylate (n-BA), 10 mol% methyl acrylate (MA), 4 mol% 4-hydroxybutyl acrylate (4HBA), and 1 mol% acrylic acid (AA) was added to the reactor. Nitrogen gas was added to the monomer mixture for 30 minutes to remove oxygen, and the internal temperature of the reactor was maintained at 62°C. The monomer mixture was uniformly stirred, and 0.07 parts by weight of the initiator AIBN (azobisisobutyronitrile) was added. The reaction was carried out at 62°C for 8 hours to produce a (meth)acrylic copolymer (glass transition temperature: -50°C, weight-average molecular weight: 1,191,000 g / mol). Ethyl acetate was added as a solvent to produce a (meth)acrylic copolymer solution (solid content 25% by weight).

[0129] Manufacturing Example 2 Toluene was added as a solvent to a 1 L reactor equipped with a cooling device to facilitate temperature control and to which nitrogen gas was refluxed. 100 parts by weight of a monomer mixture containing 95 mol% stearyl methacrylate and 5 mol% t-butyl acrylate was added to the reactor. After removing oxygen by introducing nitrogen gas into the monomer mixture for 30 minutes, the internal temperature of the reactor was maintained at 76°C. The monomer mixture was uniformly stirred, 0.2 parts by weight of the initiator AIBN (azobisisobutyronitrile) was added, and the mixture was reacted at 76°C for 4 hours to produce a (meth)acrylic oligomer. Toluene was added as a solvent to produce a (meth)acrylic oligomer solution (solid content 30% by weight).

[0130] Example 1 Based on the solid content, 100 parts by weight of the (meth)acrylic copolymer produced in Production Example 1, 0.7 parts by weight of TD-75 (isocyanate-based curing agent, Soken), 0.5 parts by weight of Hardener M-2 (aluminum chelate-based curing agent, Saiden), 15 parts by weight of benzyl acrylate (Miwon Specialty Chemical) as an aromatic group-containing monomer, 3 parts by weight of stearyl methacrylate (Aldrich) as a long-chain alkylene group-containing monomer, and 0.4 parts by weight of Irgacure TPO (BASF, phosphorus-based photoinitiator) as a photoinitiator were added, methyl ethyl ketone was added, and the mixture was diluted to produce an adhesive composition (solid content 25% by weight).

[0131] The prepared adhesive composition was applied to one side of a polyethylene terephthalate (PET) film (SKC Corporation, thickness: 75 μm, with an antistatic coating on one side) to a thickness of 13 μm, dried at 90°C for 4 minutes, and then a release film (thickness: 25 μm, with a silicone release treatment on one side) was bonded to the resulting adhesive layer. The sheet was left at 50°C for 2 days to produce an adhesive film-containing sheet in which the adhesive film (thickness: 13 μm) and the release film were sequentially laminated on the base film.

[0132] Examples 2 to 4 An adhesive film-containing sheet was manufactured in the same manner as in Example 1, except that the type and / or content of each component was changed as shown in Table 1 below. In Table 1 below, "-" means that the component was not included.

[0133] Comparative Examples 1 to 5 An adhesive film-containing sheet was manufactured in the same manner as in Example 1, except that the type and / or content of each component was changed as shown in Table 1 below.

[0134] Comparative Example 6 An adhesive film-containing sheet was manufactured in the same manner as in Example 1, except that the type and / or content of each component was changed as shown in Table 1 below.

[0135] The components used in the examples and comparative examples are as follows, as shown in Table 1 below.

[0136] Compound A: Benzyl acrylate Compound B: Ethylene glycol phenyl ether acrylate Compound C: Stearyl methacrylate Compound D: Behenyl acrylate Compound E: (meth)acrylic oligomer produced in Production Example 2 The physical properties of the adhesive film-containing sheets produced in the examples and comparative examples were evaluated as shown in Table 1 below, and the results are shown in Table 1 below.

[0137] (1) Initial peel strength (unit: gf / inch): At 23°C and 50% relative humidity, the release film was peeled off from the adhesive film-containing sheet manufactured in the examples and comparative examples to expose the adhesive film. A polyimide film (GF200, SKCKOLON, thickness: 50 μm) was adhered to the surface of the exposed adhesive film, and it was pressed with a roll with a 2 kg load. The sheet was then cut to a size of 25 mm × 100 mm in width × length to produce a test specimen. The produced test specimen was left at 25°C and 50% relative humidity for 30 minutes. The obtained test specimen is shown in Figure 1(a). Referring to Figure 1(a), the PET film 1, adhesive film 2, and polyimide film 3 are sequentially laminated. Based on JIS Z 2037, the peel force was measured when a polyimide film was peeled from an adhesive film using a tensile testing machine texture analyzer (TA Industry Co., Ltd.) at a peel temperature of 25°C, a peel speed of 2400 mm / min, and a peel angle of 180°, according to the T peel force measurement method. The measured peel force is the state before UV irradiation or before prolonged adhesion to the substrate, and is called the initial peel force.

[0138] The T-peel force can be measured by referring to Figure 1(b). The T-peel force is the force required to peel the polyimide film 3 from the PET film 1 and adhesive film 2. When measuring the T-peel force, the PET film 1 and adhesive film 2 are fixed to the TA Instrument jig, and the polyimide film 3 is peeled off by pulling it in the direction of the arrow in Figure 1(b).

[0139] (2) Peel strength after 30 days (unit: gf / inch): The release film was peeled off from the adhesive film-containing sheets of the examples and comparative examples at 23°C and 50% relative humidity to expose the adhesive film. A polyimide film (GF200, SKCKOLON, thickness: 50 μm) was attached to the surface of the exposed adhesive film, and it was pressed with a roll with a 2 kg load. The specimens were then cut to a size of 25 mm × 100 mm in width × length to produce test pieces.

[0140] The manufactured test specimens were left at 25°C and 50% relative humidity for 30 days. The peel force when the polyimide film was peeled from the adhesive film was measured using the same method as in (1).

[0141] (3) Peel strength after UV irradiation (unit: gf / inch): A test specimen was prepared by laminating a PET film, adhesive film, and polyimide film in the same manner as in (1) above. The prepared test specimen was left at 23°C and 50% relative humidity for 30 minutes. The test specimen was irradiated from the PET film side using a UV LED irradiation device (SUV-L5160A, UVSMT) at a wavelength of 385 nm and a UV irradiation energy of 1000 mJ / cm². 2 The samples were irradiated and left for 30 minutes at 23±1℃ and 55±5% relative humidity. Based on JIS Z 2037, the peel force was measured when the polyimide film was peeled from the adhesive film using a tensile testing machine (Texture analyzer, TA Industry Co., Ltd.) in the same manner as in (1), with a peel temperature of 25℃, a peel speed of 2400 mm / min, and a peel angle of 180°, using the T peel force measurement method.

[0142] (4) Peel strength after UV irradiation and heat treatment (unit: gf / inch): Test specimens were prepared by laminating PET film, adhesive film, and polyimide film in the same manner as in (1) above. The prepared test specimens were subjected to UV irradiation from the PET film side using a UV LED irradiation device (SUV-L5160A, UVSMT) at a wavelength of 385 nm and a UV irradiation energy of 1000 mJ / cm². 2 The specimens were irradiated with [a specific light source]. After that, they were left in a 50°C oven for 20 minutes. After removing the specimens from the oven, they were left at 23°C and 50% relative humidity for 30 minutes. Based on JIS Z 2037, the peel force was measured using a tensile testing machine, Texture analyzer (TA Industry Co., Ltd.), in the same manner as in (1), when the polyimide film was peeled from the adhesive film using the T peel force measurement method at a peel temperature of 25°C, a peel speed of 2400 mm / min, and a peel angle of 180°.

[0143] [Table 1]

[0144] As shown in Table 1 above, the adhesive film of the present invention exhibited a low rate of increase in peel strength after adhering to an adherend, adhered to the adherend with low peel strength before light irradiation, and showed significantly higher peel strength after light irradiation and heat treatment compared to before light irradiation.

[0145] On the other hand, the adhesive film of the comparative example could not satisfy all the effects of the present invention.

[0146] Simple modifications and alterations of the present invention can be readily carried out by a person with ordinary skill in the art, and all such modifications and alterations can be considered to fall within the scope of the present invention.

Claims

1. An adhesive film comprising a thermoset product of an adhesive composition containing a (meth)acrylic copolymer, a curing agent, a monofunctional or mono-functional compound containing an aromatic group, a monofunctional or mono-functional compound containing a long-chain alkyl group, and an initiator, The adhesive film is an adhesive film in which, before light irradiation, the rate of change of peeling force in the following formula 1 is 1.0 or less. [Formula 1] Change rate of peeling force = (P2 - P1) / P1 (In formula 1 above, P1 is the peel force (unit: gf / inch) of the adhesive film against the adherend after leaving a test piece, manufactured by adhering the adhesive film to the adherend, at 23°C and 50% relative humidity for 30 minutes. P2 is the peel force (unit: gf / inch) of the adhesive film against the adherend after leaving a test piece, manufactured by adhering the adhesive film to the adherend, at 23°C and 50% relative humidity for 30 days.

2. The adhesive film according to claim 1, wherein the peeling force increase rate of the following formula 2 is 10 or more. [Formula 2] Peeling force increase rate = P3 / P1 (In formula 2 above, P1 is the peel force (unit: gf / inch) of the adhesive film against the adherend after leaving a test piece, manufactured by adhering the adhesive film to the adherend, at 25°C and 50% relative humidity for 30 minutes. P3 is the peel force (unit: gf / inch) of the adhesive film against the adherend after a test piece, manufactured by adhering the adhesive film to the adherend, is left at 25°C and 50% relative humidity for 30 minutes, then heat-treated by light irradiation.

3. The adhesive film according to claim 2, wherein P3 in formula 2 is 500 gf / inch or more.

4. The adhesive film according to claim 1, wherein the adhesive film has a matrix for adhesive films which is a thermoset product of the (meth)acrylic copolymer and the curing agent, in which the aromatic group-containing monofunctional or more compound, the long-chain alkyl group-containing monofunctional or more compound, and the initiator are dispersed.

5. The adhesive film according to claim 1, wherein the long-chain alkyl group-containing monofunctional compound forms a polymer having a melting point of 30 to 60°C upon light irradiation.

6. The adhesive film according to claim 1, wherein the long-chain alkyl group-containing monofunctional compound comprises a linear or branched alkyl group-containing (meth)acrylate having 12 or more carbon atoms.

7. The adhesive film according to claim 1, wherein the long-chain alkyl group-containing monofunctional compound comprises one or more of stearyl (meth)acrylate, behenyl (meth)acrylate, and cetyl (meth)acrylate.

8. The adhesive film according to claim 1, wherein the long-chain alkyl group-containing monofunctional or more compound is contained in an amount of 1 to 50 parts by weight per 100 parts by weight of the (meth)acrylic copolymer.

9. The adhesive film according to claim 1, wherein the glass transition temperature of the homopolymer of the aromatic group-containing monofunctional compound is higher than that of the (meth)acrylic copolymer.

10. The adhesive film according to claim 9, wherein the difference between the glass transition temperature of the homopolymer of the aromatic group-containing monofunctional compound and the glass transition temperature of the (meth)acrylic copolymer is 20°C or more.

11. The adhesive film according to claim 1, wherein the aromatic group-containing monofunctional or more compound includes the compound of the following chemical formula 1. 【Chemistry 1】 ...Chemical formula 1 (In the above chemical formula 1, R １ is a hydrogen or methyl group, s is an integer between 0 and 10. R ２ This is a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 50 carbon atoms. T is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, or a substituted or unsubstituted alkylene oxy group having 1 to 6 carbon atoms.

12. The adhesive film according to claim 1, wherein the aromatic group-containing monofunctional compound is present in an amount of 1 to 25 parts by weight per 100 parts by weight of the (meth)acrylic copolymer.

13. The adhesive film according to claim 1, wherein the (meth)acrylic copolymer comprises a copolymer of a monomer mixture containing an alkyl group-containing (meth)acrylic monomer, a hydroxyl group-containing (meth)acrylic monomer, and a carboxylic acid group-containing (meth)acrylic monomer.

14. The adhesive film according to claim 1, wherein the curing agent comprises a mixture of an isocyanate-based curing agent and a metal chelate-based curing agent.

15. The adhesive film according to claim 1, wherein the curing agent is contained in an amount of 0.01 to 8 parts by weight per 100 parts by weight of the (meth)acrylic copolymer.

16. An optical component comprising an adhesive film according to any one of claims 1 to 15.

17. The optical member according to claim 16, wherein the optical member includes a panel for an optical display device including a flexible substrate, the adhesive film laminated on the lower surface of the flexible substrate, and a protective layer laminated on the lower surface of the adhesive film.

18. An optical display device comprising an adhesive film according to any one of claims 1 to 15.

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