Adhesive film, optical member and optical display device

Abstract

To provide an adhesive protective film which can be easily removed after being adhered to an optical element and is fixed to the optical element with high reliability by a predetermined step.SOLUTION: There is provided an adhesive film which contains a cured product of an adhesive composition comprising a (meth)acrylic copolymer, a curing agent, a mono- or higher functional compound containing an aromatic group, a mono- or higher functional compound containing a polar functional group and an initiator. The adhesive film has a peel force increase rate of 3 or more, as determined by the following numerical expression 1. The adhesive film has a peel strength of 50 gf / inch or more against an adherend at 105°C after leaving a test piece, produced by adhering the adhesive film to the adherend, at 25°C and 50% relative humidity for 30 minutes, followed by light irradiation. [Numerical expression 1] Peel force increase rate=[P2 / P1]SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, optical display devices based on organic light-emitting diodes (OLEDs) have been developed, and particularly, optical display devices based on organic light-emitting diodes with flexible properties have attracted attention.

[0003] Flexible panels based on flexible organic light-emitting diodes (OLEDs) have plastic films, such as polyimide-based films, on the top and bottom of the panel. Flexible panels are more flexible than LCD panels and conventional OLED-based panels. Therefore, scratches can occur on the surface of the flexible panel during processes such as processing, assembly, and / or inspection. To protect the panel, a protective film for processing must be temporarily attached to the flexible panel. If defects such as visual anomalies or foreign particles are found during inspection of the flexible panel, the protective film for processing can be easily peeled from the flexible panel only if it has low peel strength (i.e., easy peeling). After inspection of the flexible panel, a reinforcing protective film must be permanently attached to the panel to support it and protect it from the external environment. Therefore, it is preferable that the reinforcing protective film have higher peel strength (i.e., higher peel resistance) and higher reliability than the protective film for processing.

[0004] In the conventional panel manufacturing process, the steps of laminating a temporary protective film for processing to a panel, peeling the temporary protective film from the panel, and laminating a reinforcing protective film to the panel must all be performed in sequence, which is complicated. Furthermore, the protective film for processing must be discarded after the peeling process, which is economically and environmentally unfriendly.

[0005] The background art of the present invention is disclosed in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5683369 Summary of the Invention [Problem to be solved by the invention]

[0007] An 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 reliably fixed to the optical element by a predetermined process.

[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, thereby temporarily protecting the optical element, and that can be selectively cut off only to remove unnecessary portions from the optical element without deforming and / or damaging the optical element.

[0009] It is still another object of the present invention to provide an adhesive protective film that has a high peel strength after irradiation with light and can be reliably fixed to an optical element.

[0010] It is still another object of the present invention to provide an adhesive protective film that has a high peel strength at high temperatures after light irradiation and that can increase the durability of an optical element after being fixed to the optical element. [Means for solving the problem]

[0011] According to one embodiment, the adhesive film comprises a cured product of an adhesive composition comprising a (meth)acrylic copolymer, a curing agent, an aromatic group-containing monofunctional or higher compound, a polar functional group-containing monofunctional compound, and an initiator, and the adhesive film has a peel strength increase rate of 3 or more as shown in the following equation 1. The adhesive film is prepared by adhering the adhesive film to an adherend, and a test piece is left at 25°C and 50% relative humidity for 30 minutes, and then irradiated with light. After that, the peel strength of the adhesive film from the adherend at 105°C is 50 gf / inch or more.

[0012] [Formula 1] Peel force increase rate = P2 / P1

[0013] In Formula 1, P1 is the peel strength (unit: gf / inch) of the adhesive film to the adherend at 25°C after leaving the test piece prepared by adhering the adhesive film to the adherend at 25°C and 50% relative humidity for 30 minutes, P2 is the peel strength (unit: gf / inch) of the adhesive film to the adherend at 25°C after a test piece made by adhering the adhesive film to the adherend is left at 25°C and 50% relative humidity for 30 minutes and then exposed to light.

[0014] According to one embodiment, an optical member includes the above-mentioned adhesive film.

[0015] According to one embodiment, an optical display device includes the above-described adhesive film. [Effects of the Invention]

[0016] The present invention can provide an adhesive protective film that can be easily removed after being adhered to an optical element and can be reliably fixed to the optical element through a predetermined process.

[0017] Furthermore, the present invention can provide an adhesive protective film that adheres to an optical element with low peeling force before light irradiation, thereby temporarily protecting the optical element, and that can be easily removed from the optical element by selectively cutting only the unnecessary portions without deforming and / or damaging the optical element.

[0018] Furthermore, the present invention can provide an adhesive protective film that has a high peel strength after irradiation with light and can be fixed to an optical element with high reliability.

[0019] Furthermore, the present invention can provide an adhesive protective film that has a high peel strength at high temperatures after irradiation with light, and therefore can increase the durability of an optical element after being fixed to the optical element. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1(a) is a diagram showing a test piece for a T-peel test, and FIG. 1(b) is a diagram showing the test piece during measurement of the peel force in the T-peel test. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention. The present invention can be embodied in various different forms and is not limited to the embodiments described below.

[0022] The terms used in this specification are merely for the purpose of describing exemplary embodiments and are not intended to limit the present invention. Unless otherwise specified in the context, the singular expression includes the plural expression.

[0023] As used herein, "(meth)acrylic" can mean acrylic and / or methacrylic.

[0024] As used herein, a "copolymer" can include a polymer or a resin.

[0025] As used herein, "glass transition temperature" may refer to the glass transition temperature (Tg) measured for a homopolymer of a target monomer or compound using a DSC Discovery (manufactured by TA Instruments). Specifically, the homopolymer of a target monomer or compound is heated to 180°C at a heating rate of 20°C / min, then slowly 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. Based on the obtained data, the inflection point of the endothermic transition curve can be determined as the glass transition temperature.

[0026] In this specification, the "weight average molecular weight" may be determined in terms of polystyrene using gel permeation chromatography.

[0027] In this specification, when a numerical range is stated, "X to Y" means X or more and Y or less.

[0028] According to one embodiment, the PSA film has a low peel strength (also referred to as "initial peel strength") before light irradiation. The PSA film has an appropriate range of peel strength relative to the adherend before light irradiation, and adheres to the adherend with a low peel strength, thereby temporarily protecting the adherend. Only the unnecessary portions are selectively cut off, allowing the PSA film to be easily removed from the adherend without deformation and / or damage. Therefore, the PSA film may be used as an adhesive protective film. This is distinct from coatings for forming PSA films that have no peel strength before light irradiation when formed using conventional photocurable PSA compositions. Coatings formed using conventional photocurable PSA compositions are completely unable to provide temporary protection for the adherend.

[0029] In one embodiment, the PSA film may have an initial peel strength from an adherend of more than 0 gf / inch to 50 gf / inch or less, 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, 50 gf / inch, or 1 gf / inch to 50 gf / inch. Within the above range, the PSA film can be easily removed from the adherend without deformation and / or damage to the adherend. The "initial peel strength" may be measured by the method described below.

[0030] In this specification, the "adherend" refers to a plastic film, and may include, for example, polyester films including polyimide (PI)-based films, polycarbonate (PC)-based films, polyethylene naphthalate (PEN)-based films, polyethylene terephthalate (PET)-based films, polyethersulfone-based films, and polyurethane-based films.

[0031] In one embodiment, the adherend may be a polyimide (PI) film. A "polyimide film" may be a polymer film obtained by polymerization of a precursor polyamic acid, containing imide and aromatic groups within the repeating unit. Due to their excellent mechanical properties, polyimide films are widely used as substrates for flexible OLED panels, and an example of such a film may be polyimide film GF200 (SKCKOLON, thickness: 50 μm).

[0032] In one embodiment, the adherend may be a part of an optical element. When the adhesive film is adhered to the adherend, the adhesive film provides a temporary protective function, allowing the optical element to be removed from the adherend without deformation and / or damage. After light irradiation, the adhesive film has a higher peel strength than before light irradiation, allowing it to be reliably fixed to the adherend, thereby protecting the optical element. The adhesive film also has a high peel strength measured at high temperatures after light irradiation, allowing the durability of the optical element to be improved. For example, the adherend may be the above-mentioned plastic film or a flexible substrate including the above-mentioned plastic film.

[0033] In one embodiment, the optical element may be an optical element included in a foldable, flexible, or rollable display device, for example, a panel for a foldable, flexible, or rollable optical display device. In one embodiment, the optical element may be a panel for an optical display device including the flexible substrate described above.

[0034] According to one embodiment, the pressure-sensitive adhesive film is a cured product of the pressure-sensitive adhesive composition described below before irradiation with light. According to one embodiment, the pressure-sensitive adhesive film may be a heat-cured product of the pressure-sensitive adhesive composition described below.

[0035] According to one embodiment, the adhesive film is a release-strengthening adhesive film that exhibits a higher peel strength from an adherend after light irradiation compared to before light irradiation. The adhesive film exhibits a higher peel strength after light irradiation and adheres to the adherend after light irradiation, thereby increasing the durability of the adherend and providing a permanent protective effect. Thus, the adhesive film can be simultaneously used as a temporary protective film for processing that provides temporary protection for the adherend and a reinforcing protective film that provides permanent protection for the adherend, thereby achieving the effects of process simplification, economy, and environmental friendliness. The temporary protective film for processing is a film that is temporarily adhered to the adherend and then removed, providing temporary protection for the adherend, while the reinforcing protective film may be a film that is permanently adhered to the adherend, protecting the adherend from the external environment, etc., and is not removable from the adherend.

[0036] After light irradiation, the adhesive film exhibits a significantly increased peel strength with respect to the adherend compared to before light irradiation. This can significantly improve the reliability of the adherend and the optical element equipped with the adherend. The adhesive film can increase not only its peel strength at room temperature after light irradiation, but also its peel strength at high temperatures after light irradiation.

[0037] The adhesive film may be used as a reinforcing protective film. In one embodiment, the reinforcing protective film may refer to a protective film that is laminated on at least one surface of a flexible panel to protect the flexible panel from external impacts, etc.

[0038] According to one embodiment, the PSA film has a peel strength increase rate of 3 or more as determined by the following formula 1. If the increase rate is within this range, the PSA film adheres to the adherend, and after light irradiation, adheres to the adherend with high peel strength and high reliability, thereby significantly improving the protection and adhesion effect on the adherend.

[0039] [Formula 1] Peel force increase rate = P2 / P1

[0040] In Formula 1, P1 is the peel strength (unit: gf / inch) of the adhesive film to the adherend at 25°C after leaving the test piece prepared by adhering the adhesive film to the adherend at 25°C and 50% relative humidity for 30 minutes, P2 is the peel strength (unit: gf / inch) of the adhesive film to the adherend at 25°C after a test piece made by adhering the adhesive film to the adherend is left at 25°C and 50% relative humidity for 30 minutes and then exposed to light.

[0041] For example, the peel force increase rate of Equation 1 may be 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 3 to 100, 10 to 90, 20 to 80, and 30 to 70. If the increase rate is within the above range, the above-mentioned effects can be achieved and the PSA film can be easily manufactured.

[0042] "Light irradiation" refers to 1000 mJ / cm at a wavelength of 280 nm to 430 nm, for example, 350 nm to 390 nm, 380 nm to 390 nm, and 385 nm. 2 The UV irradiation may be performed by one or more of a UV LED, a high-pressure mercury lamp, and a metal halide lamp.

[0043] According to one embodiment, the PSA film may have an initial peel strength (P1) in Formula 1 of more than 0 gf / inch and not more than 50 gf / inch, 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, 50 gf / inch, or 1 gf / inch to 50 gf / inch. Within the above range, the optical component can be easily removed from the adherend without deformation and / or damage, and the peel strength can easily increase after irradiation with light.

[0044] According to one embodiment, P2 (peel strength after light irradiation) in Equation 1 may be 500 gf / inch or more, for example, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000 gf / inch, 500 gf / inch to 2000 gf / inch, and 500 gf / inch to 1000 gf / inch. Within the above ranges, the PSA film adheres to the adherend with high peel strength and high reliability, thereby exhibiting an adhesive effect on the adherend and an effect of improving the durability of the optical element.

[0045] According to one embodiment, the present invention increases the peel strength of an adhesive film after light irradiation through a physical change in the adhesive film due to an increase in the cohesive strength and / or modulus of the adhesive film after light irradiation.

[0046] According to one embodiment, a test piece prepared by adhering the adhesive film to an adherend is left at 25°C and 50% relative humidity for 30 minutes, and then irradiated with light. The peel strength of the adhesive film from the adherend at 105°C is 50 gf / inch or more. Within this range, the adhesive film also has a high peel strength at high temperatures after light irradiation, allowing it to be fixed to an optical element and enhance the durability of the optical element. Generally, an adhesive film with high peel strength at room temperature may have a significantly lower peel strength at high temperatures. On the other hand, the adhesive film according to one embodiment not only has a high peel strength at room temperature, but also at high temperatures. In one embodiment, the peel force at 105°C may be 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 gf / inch, 50 gf / inch to 200 gf / inch, and 50 gf / inch to 100 gf / inch.

[0047] The adhesive film is formed from an adhesive composition containing a (meth)acrylic copolymer, a curing agent, an aromatic group-containing monofunctional or higher functional compound, a polar functional group-containing monofunctional compound, and an initiator.

[0048] In one embodiment, the pressure-sensitive adhesive film may be a cured product, preferably a thermoset product, of a pressure-sensitive adhesive composition comprising a (meth)acrylic copolymer, a curing agent, an aromatic group-containing monofunctional or higher functional compound, a polar functional group-containing monofunctional compound, and an initiator.

[0049] In one embodiment, the adhesive film may have an aromatic group-containing monofunctional or higher compound, a polar functional group-containing monofunctional compound, and an initiator dispersed in an adhesive film matrix which is a thermosetting product of a (meth)acrylic copolymer and a curing agent.

[0050] <(Meth)acrylic copolymer> The (meth)acrylic copolymer forms the matrix of the adhesive film and, when cured with a curing agent, can provide the initial peel strength of the adhesive film. Furthermore, the (meth)acrylic copolymer can also promote the improvement of the cohesive strength of the adhesive film after light irradiation, together with the aromatic group-containing monofunctional or higher functional compound and the polar functional group-containing monofunctional compound.

[0051] The (meth)acrylic copolymer may have a glass transition temperature (Tg) of −10° C. or lower, for example, −60, −55, −50, −40, −35, −30, −25, −20, −15, −10° C., or −20° C. or lower, or −60° C. to −20° C. If the Tg is within the above range, it is possible to promote wetting (adhesion) to the adherend and the initial peel strength of the adhesive film, and after light irradiation, it is possible to increase the peel strength by suppressing shrinkage of the adhesive film through adjustment of the glass transition temperature of the adhesive film.

[0052] The (meth)acrylic copolymer may have a weight-average molecular weight of 500,000 g / mol or more, specifically 600,000 g / mol to 2,500,000 g / mol, which can promote wettability to the adherend and initial peel strength of the PSA film.

[0053] The (meth)acrylic copolymer may include a copolymer of a monomer mixture containing a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group.

[0054] The (meth)acrylic monomer having an alkyl group forms the matrix of the adhesive film and may include an unsubstituted, linear or branched (meth)acrylic acid ester having an alkyl group of 1 to 20 carbon atoms, for example, 1 to 10 carbon atoms, and 1 to 6 carbon atoms.

[0055] For example, the (meth)acrylic monomer having an alkyl group may include one or more of 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.

[0056] The (meth)acrylic monomer having an alkyl group may be contained in the monomer mixture at 85 mol% to 99.5 mol%, specifically 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.5 mol%, 90 mol% to 99 mol%, and 95 mol% to 98 mol%. Within the above ranges, this may be effective in providing wettability to the adherend and initial peel strength of the PSA film.

[0057] The (meth)acrylic monomer having a hydroxyl group may be a (meth)acrylate containing one or more hydroxyl groups. For example, the hydroxyl group-containing (meth)acrylate may include a (meth)acrylic acid ester containing an alkyl group having 1 to 20 carbon atoms, specifically 2 to 11 carbon atoms, substituted with one or more hydroxyl groups. For example, the (meth)acrylic monomer having a hydroxyl group may be one or more of 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, trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, 4-hydroxycyclopentyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, and cyclohexanedimethanol mono(meth)acrylate.

[0058] The (meth)acrylic monomer having a hydroxyl group may be contained in the monomer mixture at 0.1 mol% to 15 mol%, specifically 0.5 mol% to 15 mol%, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 mol%, 0.5 mol% to 5 mol%, 2 mol% to 10 mol%, and 1 mol% to 5 mol%. If the amount is within the above range, it may be effective in imparting cohesive strength to the PSA film and providing the initial peel strength of the PSA film.

[0059] In one embodiment, the total amount of the (meth)acrylic monomer having an alkyl group and the (meth)acrylic monomer having a hydroxyl group may be 95 mol % or more, for example, 95 mol % to 100 mol %, or 100 mol %, in the monomer mixture. Within this range, the effects of the present invention can be easily achieved.

[0060] The monomer mixture may further include a carboxylic acid group-containing monomer. The carboxylic acid group-containing monomer may increase the glass transition temperature of the (meth)acrylic copolymer and promote the provision of initial adhesive strength. The carboxylic acid group-containing monomer may include, but is not limited to, (meth)acrylic acid.

[0061] The carboxylic acid group-containing monomer may be contained in the monomer mixture in an amount of 0 mol % to 5 mol %, specifically 0.05 mol % to 5 mol %, and 0.1 mol % to 5 mol %. If the amount is within the above range, it may be effective in imparting cohesive strength to the PSA film and providing the initial peel strength of the PSA film.

[0062] In one embodiment, the total content of the (meth)acrylic monomer having an alkyl group, the (meth)acrylic monomer having a hydroxyl group, and the monomer having a carboxylic acid group in the monomer mixture may be 95 mol % or more, for example, 95 mol % to 100 mol %, or 100 mol %. Within this range, the effects of the present invention can be easily achieved.

[0063] The monomer mixture may contain a (meth)acrylic monomer having a homopolymer glass transition temperature of −80° C. or higher and 0° C. or lower, specifically, −60° C. to −20° C. If the temperature is within the above range, it may be easy to produce a (meth)acrylic copolymer having the above-mentioned glass transition temperature range.

[0064] The monomer mixture may include, but is not limited to, methyl acrylate, acrylic acid, methacrylic acid, and the like.

[0065] In one embodiment, the monomer mixture may not contain a monomer having an aromatic group. The (meth)acrylic copolymer may be a non-aromatic (meth)acrylic copolymer. A PSA film formed from a composition containing a (meth)acrylic copolymer formed from a monomer mixture containing a monomer having an aromatic group may have difficulty achieving the range of the peel force increase rate defined by Equation 1 above.

[0066] The (meth)acrylic copolymer may be produced by polymerizing a monomer mixture using a conventional polymerization method. The polymerization method can be carried out using conventional methods known to those skilled in the art. For example, the (meth)acrylic copolymer may be produced by adding an initiator to the monomer mixture and then performing conventional copolymer polymerization, such as suspension polymerization, emulsion polymerization, or solution polymerization. The polymerization temperature may be 65°C to 70°C, and the polymerization time may be 6 to 8 hours. As the initiator, conventional initiators including azo polymerization initiators and / or peroxides such as benzoyl peroxide or acetyl peroxide may be used.

[0067] <Curing agent> The curing agent can form a matrix of the adhesive film by thermally curing the (meth)acrylic copolymer, and can promote the provision of initial peel strength of the adhesive film.

[0068] The curing agent is a thermal curing agent and may include at least one of an isocyanate-based curing agent, a metal chelate-based curing agent, a carbodiimide-based curing agent, an aziridine-based curing agent, and an epoxy-based curing agent.

[0069] In one embodiment, the curing agent may include an isocyanate-based curing agent alone or a mixture of an isocyanate-based curing agent and a metal chelate-based curing agent. The mixture may more easily achieve the effects of the present invention, and may include, for example, a mixture of an isocyanate-based curing agent and a metal chelate-based curing agent.

[0070] The isocyanate-based curing agent may include a difunctional or higher isocyanate-based curing agent, specifically a difunctional to hexafunctional isocyanate-based curing agent. In one embodiment, the isocyanate-based curing agent may include one or more of xylylene diisocyanate (XDI) including m-xylylene diisocyanate, methylene bis(phenyl isocyanate) (MDI) including 4,4'-methylene bis(phenyl isocyanate), naphthalene diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate, or an adduct 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.

[0071] The isocyanate curing agent may be contained in an amount of 5 parts by weight or less, for example, 0.001 to 3 parts by weight, or 0.01 to 2 parts by weight, per 100 parts by weight of the (meth)acrylic copolymer. Within the above range, the reliability of the PSA film can be improved. Preferably, the isocyanate curing agent may be contained in an amount of 0.3 to 2 parts by weight per 100 parts by weight of the (meth)acrylic copolymer. Within the above range, the reliability of the PSA film can be improved, making it easier to achieve the effects of the present invention.

[0072] The metal chelate curing agent can be a conventional metal chelate curing agent, and examples of the metal chelate curing agent 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 chelate curing agent can include one or more of aluminum ethyl acetoacetate diisopropylate, aluminum tris(ethyl acetoacetate), alkyl acetoacetate aluminum diisopropylate, aluminum isopropylate, mono-sec-butoxyaluminum diisopropylate, aluminum sec-butylate, aluminum ethylate, tetraisopropyl titanate, tetra-normal-butyl titanate, butyl titanate dimer, titanium acetylacetonate, titanium octylene glycolate, titanium tetraacetylacetonate, titanium ethyl acetoacetate, polyhydroxytitanium stearate, and aluminum acetylacetonate.

[0073] The metal chelate curing agent may be contained in an amount of 3 parts by weight or less, for example, 0.001 to 1 part by weight, and 0.01 to 1 part by weight, per 100 parts by weight of the (meth)acrylic copolymer. Within this range, the effects of the PSA film of the present invention are not affected, and additional effects can be obtained. Preferably, the metal chelate curing agent may be contained 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 PSA film is increased, making it easier to achieve the effects of the present invention.

[0074] The curing agent may be contained in an amount of 0.01 to 8 parts by weight, for example, 0.01 to 3 parts by weight, and 0.5 to 3 parts by weight, per 100 parts by weight of the (meth)acrylic copolymer. Within this range, the reliability of the PSA film can be improved. In one embodiment, the curing agent may be contained 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 PSA film of the present invention can be easily achieved.

[0075] <Aromatic group-containing monofunctional or higher functional compounds> The aromatic group-containing mono- or higher functional compound has one or more functional groups that can be reacted (e.g., cured) by an initiator. The "functional group" may be a vinyl group or a (meth)acrylate group. In one embodiment, the aromatic group-containing mono- or higher functional compound may be an aromatic group-containing mono- or higher functional UV-reactive compound.

[0076] According to one embodiment, the aromatic group-containing monofunctional or higher functional compound can increase the cohesive strength of the adhesive film after light irradiation, so that when the adhesive film is photocured while adhering to the surface of the adherend, the adhesive film can be adhered to the adherend with a high peel strength, thereby increasing the peel strength of the adhesive film.

[0077] According to one embodiment, the aromatic group-containing mono- or higher functional compound has photosensitivity, and therefore, when irradiated with light, the peeling force can be increased through a physical change in the adhesive film.

[0078] According to one embodiment, the aromatic group-containing monofunctional or higher functional compound is an aromatic group-containing monofunctional or higher functional monomer, and the glass transition temperature of the homopolymer of the monomer is preferably within a predetermined range compared to the glass transition temperature of the (meth)acrylic copolymer, thereby suppressing shrinkage of the adhesive film even when the adhesive film is cured by light irradiation, thereby increasing the peel strength after light irradiation.

[0079] In one embodiment, the glass transition temperature of the homopolymer of the aromatic group-containing mono- or higher functional compound is higher than the glass transition temperature of the (meth)acrylic copolymer, and the difference therebetween is preferably 20° C. or more, for example, 20° C. to 120° C. and 40° C. to 100° C. If the temperature is within the above range, the peel strength after light irradiation can be increased.

[0080] The aromatic group-containing monofunctional or higher functional compound may have a homopolymer glass transition temperature of 0° C. or higher, for example, 0° C. to 50° C., or 5° C. to 50° C. If the temperature is within the above range, the glass transition temperature is higher than that of a (meth)acrylic copolymer, and therefore the effect of improving the peel strength of the pressure-sensitive adhesive film due to the improved cohesive strength after light irradiation can be obtained.

[0081] The aromatic group-containing monofunctional or higher functional compound may have one or more aromatic groups. The UV-reactive compound having one or more aromatic groups can increase the peel force increase rate of Equation 1.

[0082] According to one embodiment, the aromatic group-containing monofunctional or higher functional compound is an aromatic group-containing mono(meth)acrylate, which may include, but is not limited to, a compound represented by the following Chemical Formula 1:

[0083] [Chemical formula 1] [ka]

[0084] In Chemical Formula 1, R 1 is hydrogen or a methyl group, s is an integer from 0 to 10; R 2 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 alkyleneoxy group having 1 to 6 carbon atoms.

[0085] As used herein, "substituted or unsubstituted" means that one or more hydrogen atoms are substituted with an alkyl group having 1 to 10 carbon atoms, a thioalkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a halogen (F, Cl, Br, or I), a cycloalkyl group having 3 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0086] Specifically, R 2may be a substituted or unsubstituted phenoxy group, benzyl group, phenyl group, biphenyl group, terphenyl group, naphthyl group, or the like.Specifically, the aromatic group-containing monofunctional or higher functional compound is 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, 2-(2-methylphenyl)ethyl(meth)acrylate, ) 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 (meth)acrylate, 2-(4-bromophenyl)ethyl (meth)acrylate, 2-(3-phenylphenyl)ethyl (meth)acrylate, ortho-biphenyl (meth)acrylate, meta-biphenyl (meth)acrylate, para-biphenyl (meth)acrylate, 2,6-terphenyl (meth)acrylate, ortho-terphenyl (meth)acrylate, meta-terphenyl (meth)acrylate, para-terphenyl (meth)acrylate, 4-(4-methylphenyl)phenyl (meth)acrylate, 4-(2- The acrylic acid ester may include one or more of 2-(4-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, which may be included alone or in combination of two or more.

[0087] In one embodiment, the aromatic group-containing monofunctional or higher functional compound may include one or more of benzyl (meth)acrylate, ethylene glycol phenyl ether (meth)acrylate, phenylbenzyl (meth)acrylate, ethoxylated phenyl (meth)acrylates including ethoxylated phenyl acrylate (particularly, Phenyl(EO)1 acrylate, Phenyl(EO)2 acrylate), etc., ethoxylated phenylphenol (meth)acrylates including ethoxylated phenylphenol acrylate (o-Phenylphenol(EO) acrylate), etc., phenoxybenzyl (meth)acrylates including phenoxybenzyl acrylate, etc., biphenylmethyl (meth)acrylates including biphenylmethyl acrylate, etc., and naphthyl (meth)acrylates including 1-naphthyl acrylate, etc.

[0088] The aromatic group-containing monofunctional or higher functional compound may be contained in an amount of 50 to 200 parts by weight, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200 parts by weight, 50 to 150 parts by weight, and 50 to 100 parts by weight, relative to 100 parts by weight of the (meth)acrylic copolymer. If the amount is within the above range, it can contribute to an increase in the peel strength of the adhesive film after irradiation with light.

[0089] <Monofunctional compound containing polar functional group> A polar functional group-containing monofunctional compound (also referred to as a "polar functional group-containing monofunctional compound") can increase the peel strength of a PSA film at high temperatures after light irradiation. This is thought to be due to the interaction between the polar functional group and the aromatic group after light irradiation, but the present invention is not limited to this.

[0090] The polar functional group-containing monofunctional compound has one functional group that can be reacted (e.g., cured) by an initiator. The "functional group" may be a vinyl group or a (meth)acrylate group. In one embodiment, the polar functional group-containing monofunctional compound may be a polar functional group-containing monofunctional UV-reactive monomer.

[0091] In one embodiment, the polar functional group-containing monofunctional compound may be a non-aromatic compound that does not have an aromatic group.

[0092] According to one embodiment, the polar functional group of the polar functional group-containing monofunctional compound may be a hydroxyl group (-OH), a carboxylic acid group (-COOH), an amide group (-CONH2), or a morpholine group.

[0093] [Morpholine group] [ka]

[0094] For example, the polar functional group-containing monofunctional compound can include one or more of (meth)acryloylmorpholine, (meth)acrylic acid, (meth)acrylamide, hydroxybutyl (meth)acrylates including 4-hydroxybutyl (meth)acrylate, etc., and hydroxyethyl (meth)acrylates including 2-hydroxyethyl (meth)acrylate, etc. For example, the polar functional group-containing monofunctional compound can include one or more of acryloylmorpholine, acrylic acid, acrylamide, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate.

[0095] According to one embodiment, the aromatic group-containing mono- or polyfunctional compound may be included in an amount of 1000 to 3000 parts by weight, for example, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000 parts by weight, and 1200 to 2000 parts by weight, per 100 parts by weight of the polar functional group-containing monofunctional compound. Within this range, the rate of increase in peel strength after light irradiation is high, and the peel strength at high temperatures after light irradiation can also be easily increased.

[0096] The polar functional group-containing monofunctional compound may be contained in an amount of 1 to 20 parts by weight, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts by weight, 1 to 10 parts by weight, and 3 to 10 parts by weight, relative to 100 parts by weight of the (meth)acrylic copolymer. If it is in the above range, it can contribute to increasing the rate of increase in peel strength after light irradiation and can contribute to increasing the peel strength of the PSA film at high temperatures after light irradiation.

[0097] According to one embodiment, the sum of the polar functional group-containing monofunctional compound and aromatic group-containing mono- or more functional compound may be contained in the PSA film in an amount of 20 to 60% by weight, for example, 20, 25, 30, 35, 40, 45, 50, 55, 60% by weight, and 30 to 50% by weight. Within this range, the rate of increase in peel strength after light irradiation is high, and the peel strength at high temperatures after light irradiation can also be easily increased.

[0098] <Initiator> The initiator can provide a physical change in the adhesive film by curing the aromatic group-containing monofunctional or higher functional compound and the polar functional group monofunctional compound upon irradiation with light. The initiator includes at least one of a photoradical initiator and a cationic photoinitiator, and may further include a thermal initiator.

[0099] In one embodiment, the initiator may include a photoinitiator having a maximum absorption wavelength within the irradiation wavelength range applied upon irradiation with the above-mentioned light. For example, the initiator may have a maximum absorption wavelength in the wavelength range of 280 nm to 430 nm. If the wavelength is within this range, the aromatic group-containing monofunctional or higher functional compound and the polar functional group-containing monofunctional compound can be photocured upon irradiation with light. Specifically, the photoinitiator may include, but is not limited to, a phosphorus-based initiator, a ketone-based initiator, etc.

[0100] The initiator may be contained in an amount of 0.01 to 8 parts by weight, for example, 0.01 to 7.5 parts by weight, 0.03 to 4.5 parts by weight, or 0.1 to 1 part by weight, relative to 100 parts by weight of the (meth)acrylic copolymer. Within the above ranges, a uniform curing effect can be achieved on the aromatic group-containing monofunctional or higher compounds and polar functional group-containing monofunctional compounds upon irradiation with light, and the transparency of the PSA film can be prevented from decreasing due to the remaining initiator.

[0101] The pressure-sensitive adhesive composition may further include a curing accelerator.

[0102] The curing accelerator can accelerate the curing reaction of the pressure-sensitive adhesive film and further increase the cohesive strength of the pressure-sensitive adhesive layer. The curing accelerator can include conventional curing accelerators known to those skilled in the art. Examples of the curing accelerator include tin-based metal compounds, zinc 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, the curing accelerator can include, but is not limited to, tetravalent or divalent organotin compounds such as dibutyltin dilaurate, bis-acetylacetonate-dibutyltin, dibutyltin dimaleate, and tin dimaleate.

[0103] The curing accelerator may be contained in an amount of 0.001 to 3 parts by weight per 100 parts by weight of the (meth)acrylic copolymer. Within this range, the curing speed of the adhesive film can be increased and the cohesive strength can be improved.

[0104] The pressure-sensitive adhesive composition may further contain a silane coupling agent.

[0105] The silane coupling agent can further increase the peel strength of the PSA film. The silane coupling agent can include a conventional silane coupling agent known to those skilled in the art. For example, the silane coupling agent can include, but is not limited to, an epoxy group-containing silane coupling agent such as glycidoxypropyltrimethoxysilane or glycidoxypropylmethyldimethoxysilane.

[0106] The silane coupling agent may be contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer. If the amount is within this range, the peel strength can be further improved.

[0107] The PSA composition may further contain additives. The additives may include typical additives known to those skilled in the art as being contained in PSA films. For example, the additives may include, but are not limited to, one or more of a pigment, a UV absorber, an antioxidant, a leveling agent, an antistatic agent, a retarder, a catalyst, and a rework agent.

[0108] The pressure-sensitive adhesive composition may further contain a solvent. The solvent can improve the coatability of the pressure-sensitive adhesive composition and enable the production of a thin pressure-sensitive adhesive film with a uniform surface. The solvent may include common solvents 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 embodiment, the pressure-sensitive adhesive composition may contain 15% to 40% by weight, specifically 20% to 30% by weight, of the solid content of the pressure-sensitive adhesive film. Within this range, the composition may exhibit excellent coatability.

[0109] The adhesive film may have a haze of 5% or less, specifically 0.1% to 2%, in the visible light region (e.g., wavelength 380 nm to 780 nm), and a total light transmittance of 80% or more, specifically 85% to 95%. If the haze is within the above range, the adhesive film has good optical transparency and can be used in optical display devices.

[0110] The thickness of the adhesive film may be 200 μm or less, specifically more than 0 μm and 100 μm or less, and more specifically 5 μm to 50 μm, which can enhance the protection effect for the flexible panel.

[0111] The PSA film may be produced by applying the PSA composition to one side of a release film, drying it, and then aging (or heat curing). Drying can be carried out by treating at 50°C to 100°C for 1 to 30 minutes. Aging (or heat curing) can be carried out at 30°C to 70°C for 1 to 10 days.

[0112] The optical member of the present invention includes a pressure-sensitive adhesive film according to an embodiment.

[0113] In one embodiment, 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 the adhesive film according to the embodiment.

[0114] In one embodiment, the optical member may include an optical element having an adherend laminated on its bottom surface, and an adhesive film according to the embodiment laminated on the bottom surface of the adherend.

[0115] The optical element may be an optical element included in a foldable, flexible, or rollable display device, for example, a panel for a foldable, flexible, or rollable optical display device.

[0116] The optical display panel may include a flexible substrate that supports an optical element such as an organic light emitting diode (OLED). The flexible substrate may be a plastic film, such as a polyester film including a polyimide film, a polyethylene terephthalate film, or a polyethylene naphthalate film, a polycarbonate film, or a polyethersulfone film.

[0117] The optical element may further include a base element for an optical display device that is laminated on the upper surface of the flexible substrate and provides a certain optical function of the optical display device, such as light emission, polarization, optical compensation, improvement of display quality, and / or conductivity. Examples of base elements for optical display devices include OLED devices, window films, windows, polarizers, color filters, retardation films, elliptical polarizing films, reflective polarizing films, anti-reflection films, compensation films, brightness enhancement films, alignment films, light diffusion films, shatterproof glass films, surface protection films, OLED device barrier layers, plastic LCD substrates, and transparent electrode films including indium tin oxide (ITO), fluorinated tin oxide (FTO), aluminum doped zinc oxide (AZO), carbon nanotubes (CNTs), Ag nanowires, and graphene.

[0118] The optical element may further include a protective layer laminated on the lower surface of the flexible substrate.

[0119] 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 protective film including a polyester film such as a polyethylene terephthalate film or a polyethylene naphthalate film, a polycarbonate film, or a polyethersulfone film.

[0120] In one embodiment, the optical member may include an optical display panel including a flexible substrate, an adhesive film laminated on a lower surface of the flexible substrate, and a protective layer laminated on a lower surface of the adhesive film.

[0121] Optical components may be manufactured by modifying conventional methods known to those skilled in the art. For example, optical components can be manufactured by preparing a flexible panel including a flexible substrate, bonding a laminate of an adhesive film and a protective layer to the lower surface of the flexible substrate, and, if the flexible substrate or flexible panel has no defects such as visual abnormalities or foreign matter, bonding the laminate of the adhesive film and the protective layer to the flexible panel with a high peel force by irradiating with the above-mentioned light. On the other hand, if visual abnormalities or defects are present, the laminate of the adhesive film and the protective layer can be peeled off from the flexible panel.

[0122] The optical display device of the present invention includes the pressure-sensitive adhesive film according to the embodiment.

[0123] The optical display device may include an organic light emitting diode display device, a liquid crystal display device, etc. The optical display device may include a flexible display device, or a non-flexible display device. [Example]

[0124] The present invention will be described in more detail with reference to preferred examples thereof below, but the following examples are presented as preferred examples of the present invention and should not be construed as limiting the present invention in any way.

[0125] <Production of (meth)acrylic copolymer> Ethyl acetate was added as a solvent to a 1-L reactor equipped with a cooling device for easy temperature control and refluxing nitrogen gas. 100 parts by weight of a monomer mixture containing 95 mol% n-butyl acrylate (n-BA) and 5 mol% 4-hydroxybutyl acrylate (4HBA) was added to the reactor. Nitrogen gas was introduced into 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 stirred uniformly, and 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as an initiator. The reaction was continued at 62°C for 8 hours to produce a (meth)acrylic copolymer (glass transition temperature: -50°C, weight-average molecular weight: 1,200,000 g / mol). Ethyl acetate was added as a solvent to produce a (meth)acrylic copolymer solution (solids content: 25 wt%).

[0126] Example 1 A pressure-sensitive adhesive composition (solids content 25 wt%) was prepared by adding 100 parts by weight of the prepared (meth)acrylic copolymer, 0.5 parts by weight of TD-75 (isocyanate-based curing agent, Soken Co.) as a curing agent, 1.0 part by weight of Hardener BXX-4805 (aluminum chelate-based curing agent, Samyoung Co., Ltd.), 80 parts by weight of ethoxylated phenyl acrylate (Phenyl(EO)2 acrylate, Miwon Specialty Chemical Co.) as an aromatic group-containing monomer, 5 parts by weight of acryloylmorpholine as a polar functional group-containing monofunctional compound, and 0.5 parts by weight of Irgacure TPO (BASF, phosphorus-based photoinitiator) as a photoinitiator, based on the solid content, and diluting with methyl ethyl ketone.

[0127] The prepared adhesive composition was applied to one side of a polyethylene terephthalate (PET) film (SKC, thickness: 75 μm, one side of which was treated with an antistatic coating) as a base film in a thickness of 13 μm, and dried at 90°C for 4 minutes to form an adhesive layer. Thereafter, a release film (thickness: 25 μm, one side of which was treated with a silicone release agent) was bonded to the adhesive layer, and the mixture was left at 50°C for 2 days to prepare an adhesive film-containing sheet in which an adhesive film (thickness: 13 μm) and a release film were sequentially laminated on the base film.

[0128] (Examples 2 to 6) A PSA film-containing sheet was manufactured using the same manufacturing method as in Example 1, except that the type of polar functional group-containing monofunctional compound in Example 1 was changed as shown in the following Table 1. In the following Table 1, "-" means that the corresponding component was not included.

[0129] (Comparative Examples 1 to 3) An adhesive film-containing sheet was produced using the same production method as in Example 1, except that a non-polar functional group-containing monofunctional compound was used instead of the polar functional group-containing monofunctional compound in Example 1, as shown in Table 1 below.

[0130] Comparative Example 4 An adhesive film-containing sheet was produced using the same production method as in Example 1, except that acryloylmorpholine in Example 1 was not included.

[0131] In Table 1 below, the components used in the examples and comparative examples are as follows.

[0132] Compound A: acryloylmorpholine Compound B: acrylic acid Compound C: Acrylamide Compound D: 4-hydroxybutyl acrylate Compound E: 2-hydroxyethyl acrylate Compound F: 2-hydroxyethyl methacrylate Compound G: Isobornyl acrylate Compound H: Isobornyl methacrylate Compound I: Cyclohexyl acrylate

[0133] The physical properties of the adhesive film-containing sheets produced in the examples and comparative examples were evaluated, and the evaluation results are also shown in Table 1 below.

[0134] <Evaluation> (1) Initial peel force (unit: gf / inch) The release films were peeled off from the adhesive film-containing sheets prepared in 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 adhered to the surface of the exposed adhesive film, pressed with a roll loaded with 2 kg, and cut to a size of 25 mm x 100 mm in width x length to prepare a test specimen. The prepared test specimen was left at 25°C and 50% relative humidity for 30 minutes. The structure of the test specimen is shown in Figure 1(a). Referring to Figure 1(a), the test specimen is sequentially laminated with a PET film 1, an adhesive film 2, and a polyimide film 3. The peel strength was measured when the polyimide film was peeled off from the adhesive film using a tensile tester (Texture analyzer, TA Industry) in accordance with JIS Z 2037, at a peel temperature of 25°C, a peel speed of 2400 mm / min, and a peel angle of 180°. The measured peel strength is the peel strength of the adhesive film before UV irradiation, and corresponds to the initial peel strength.

[0135] The peel strength measured in the T-peel test (hereinafter referred to as "T-peel strength" for convenience) may be measured with reference to Figure 1(b). The T-peel strength is the peel strength when the polyimide film 3 is peeled from the PET film 1 and the adhesive film 2. When measuring the T-peel strength, the PET film 1 and the adhesive film 2 are fixed to the jig of the TA Instrument, and the polyimide film 3 is pulled in the direction of the arrow in Figure 1(b) and peeled off.

[0136] (2) Peeling force after UV irradiation (unit: gf / inch) A test specimen was prepared by laminating a PET film, an adhesive film, and a polyimide film in this order using the same method as in (1). The prepared test specimen was left at 23°C and 50% relative humidity for 30 minutes. After that, the test specimen was irradiated with UV light from the PET film side using a UV LED irradiator (SUV-L5160A, UVSMT) at a wavelength of 385 nm with an energy of 1000 mJ / cm. 2 The film was then exposed to light at 23±1°C and left for 30 minutes at a relative humidity of 55±5%. Based on JIS Z2037, a tensile tester (Texture analyzer, TA industry) was used to measure the peel strength (i.e., T-peel strength) when the polyimide film was peeled from the PSA film in a T-peel test at a peel temperature of 25°C, a peel speed of 2400 mm / min, and a peel angle of 180°.

[0137] (3) Peel strength at high temperature after UV irradiation (unit: gf / inch) A test specimen was prepared by laminating a PET film, an adhesive film, and a polyimide film in this order using the same method as in (1). The test specimen was irradiated with UV light at a wavelength of 385 nm and an energy of 1000 mJ / cm using a UV LED irradiator (SUV-L5160A, UVSMT) from the PET film side. 2 After irradiating with UV light, the film was left at 23±1°C and a relative humidity of 55±5% for 30 minutes. Based on JIS Z2037, a tensile tester (Texture analyzer, TA industry) was used to measure the peel strength (i.e., T-peel strength) when the polyimide film was peeled from the PSA film in a T-peel test at a peel temperature of 105°C, a peel speed of 2400 mm / min, and a peel angle of 180°.

[0138] [Table 1]

[0139] As shown in Table 1, the adhesive films of the examples had low initial peel strength and adhered to the substrate with low peel strength before light irradiation, but after light irradiation, the peel strength became significantly higher than before light irradiation, and the peel strength at high temperatures also became significantly higher after light irradiation.

[0140] On the other hand, the adhesive films of the comparative examples did not achieve the effects of the present invention at all.

[0141] Simple variations and modifications of the present invention can be easily implemented by those skilled in the art, and all such variations and modifications can be considered to be included within the scope of the present invention. [Explanation of symbols]

[0142] 1 PET film 2 adhesive film 3 Polyimide film

Claims

1. An adhesive film, The pressure-sensitive adhesive film comprises a cured product of a pressure-sensitive adhesive composition including a (meth)acrylic copolymer, a curing agent, an aromatic group-containing monofunctional or higher functional compound, a polar functional group-containing monofunctional compound, and an initiator; The adhesive film has a peel strength increase rate of 3 or more as determined by the following formula 1: The pressure-sensitive adhesive film is a pressure-sensitive adhesive film in which a test piece produced by adhering the pressure-sensitive adhesive film to an adherend is left at 25°C and 50% relative humidity for 30 minutes, and then irradiated with light, and the peel strength of the pressure-sensitive adhesive film from the adherend at 105°C is 50 gf / inch or more. [Formula 1] Peel force increase rate = P2 / P1 (In the above formula 1, P1 is the peel strength (unit: gf / inch) of the PSA film from the adherend at 25°C after leaving a test piece prepared by adhering the PSA film to the adherend at 25°C and 50% relative humidity for 30 minutes, P2 is the peel strength (unit: gf / inch) of the PSA film from the adherend at 25°C after a test piece prepared by adhering the PSA film to the adherend is left at 25°C and 50% relative humidity for 30 minutes and then irradiated with light.

2. P1 in the formula 1 is more than 0 gf / inch and 50 gf / inch or less, The pressure-sensitive adhesive film according to claim 1, wherein P2 in the formula 1 is 500 gf / inch or more.

3. The adhesive film according to claim 1, wherein the aromatic group-containing monofunctional or higher compound, the polar functional group-containing monofunctional compound, and the initiator are dispersed in an adhesive film matrix which is a thermosetting product of the (meth)acrylic copolymer and the curing agent.

4. The pressure-sensitive adhesive film according to claim 1 , wherein the polar functional group-containing monofunctional compound is a non-aromatic compound having no aromatic group.

5. The pressure-sensitive adhesive film according to claim 1 , wherein the polar functional group of the polar functional group-containing monofunctional compound is a hydroxyl group, a carboxylic acid group, an amide group, or a morpholine group.

6. The polar functional group-containing monofunctional compound comprises one or more of (meth)acryloylmorpholine, (meth)acrylic acid, (meth)acrylamide, hydroxybutyl (meth)acrylate, and hydroxyethyl (meth)acrylate. The adhesive film according to claim 1.

7. The pressure-sensitive adhesive film according to claim 1 , wherein the aromatic group-containing mono- or polyfunctional compound is contained in an amount of 1,000 to 3,000 parts by weight per 100 parts by weight of the polar functional group-containing monofunctional compound.

8. The pressure-sensitive adhesive film according to claim 1 , wherein the polar functional group-containing monofunctional compound is contained in an amount of 1 to 20 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer.

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

10. The pressure-sensitive adhesive film according to claim 9, wherein the difference between the glass transition temperature of the homopolymer of the aromatic group-containing mono- or polyfunctional 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 higher functional compound comprises a compound represented by the following Chemical Formula 1: [Chemical formula 1] 【Chemistry 1】 (In the above Chemical Formula 1, R １ is hydrogen or a methyl group, s is an integer from 0 to 10; R ２ 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 alkyleneoxy group having 1 to 6 carbon atoms.

12. The pressure-sensitive adhesive film according to claim 1 , wherein the aromatic group-containing mono- or polyfunctional compound is contained in an amount of 50 to 200 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer.

13. The pressure-sensitive 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 and a hydroxyl group-containing (meth)acrylic monomer.

14. The pressure-sensitive 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 pressure-sensitive adhesive film according to claim 1 , wherein the curing agent is contained in an amount of 0.01 to 8 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer.

16. An optical member comprising the pressure-sensitive adhesive film according to any one of claims 1 to 15.

17. 17. The optical member of claim 16, comprising: an optical display panel including a flexible substrate; the adhesive film laminated on a lower surface of the flexible substrate; and a protective layer laminated on a lower surface of the adhesive film.

18. An optical display device comprising the pressure-sensitive adhesive film according to any one of claims 1 to 15.

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