Adhesive composition, and adhesive sheet and image display device using same

Abstract

Provided in the present invention are an adhesive composition comprising an acrylic copolymer, a crosslinking agent, and a pigment, and an adhesive sheet and an image display device using same, wherein the full-wavelength transmittance of an adhesive layer after curing satisfies a specific range under specific thickness conditions. The adhesive composition according to the present invention imparts excellent light-shielding properties while presenting no problems in terms of adhesive properties, and has heat resistance and moist heat resistance durability allowing use adjacent to a light source.

Description

Adhesive composition, adhesive sheet using the same, and image display device

[0001] The present invention relates to an adhesive composition, an adhesive sheet using the same, and an image display device. More specifically, it relates to an adhesive composition having heat resistance and moisture resistance durability that provides excellent light-blocking properties without issues in terms of adhesive physical properties and can be used in proximity to a light source, an adhesive sheet using the same, and an image display device.

[0002] A light-blocking adhesive composition is required to prevent light leakage or reflection from the backlight source of a liquid crystal display (LCD) or the self-emissive element of an organic light-emitting display (OLED).

[0003] Conventional light-blocking adhesive compositions were prepared by adding carbon black particles as light-blocking particles to an adhesive resin and a curing agent.

[0004] For example, Korean Patent Publication No. 10-2020-0045427 discloses an adhesive sheet having excellent light-blocking properties by having an adhesive layer in which carbon black particles are dispersed.

[0005] However, light-blocking adhesive compositions using carbon black particles as light-blocking particles had problems such as relatively insufficient adhesive strength or surface precipitation of carbon black particles that impairs light uniformity.

[0006] In addition, since light-blocking adhesive compositions can be used in proximity to light sources, there is a need for technological development of light-blocking adhesive compositions that exhibit excellent durability even under high temperature or high temperature and humidity conditions.

[0007] One objective of the present invention is to provide an adhesive composition having heat resistance and moisture resistance durability that provides excellent light-blocking properties without issues in terms of adhesive properties and can be used in proximity to a light source.

[0008] Another objective of the present invention is to provide an adhesive sheet using the adhesive composition.

[0009] Another objective of the present invention is to provide an image display device comprising the adhesive sheet.

[0010] On the other hand, the present invention relates to an adhesive composition comprising an acrylic copolymer, a crosslinking agent, and a pigment, wherein

[0011] The above pigment includes an organic black pigment, and

[0012] The present invention provides an adhesive composition having a full-wave transmittance of 3% or more and less than 10% at a thickness of 50㎛ of the adhesive layer after curing.

[0013]

[0014] In one embodiment of the present invention, the acrylic copolymer may comprise 20% to 40% by weight of an alkyl (meth)acrylate monomer having 1 to 3 carbon atoms, 55% to 75% by weight of an alkyl (meth)acrylate monomer having 4 to 12 carbon atoms, and 1% to 10% by weight of a monomer comprising a crosslinkable polar functional group.

[0015] In one embodiment of the present invention, the crosslinking agent may include an isocyanate-based crosslinking agent.

[0016] In one embodiment of the present invention, the pigment may include lactam black.

[0017]

[0018] On the other hand, the present invention provides an adhesive sheet formed using the adhesive composition.

[0019] On the other hand, the present invention provides an image display device comprising the adhesive sheet.

[0020] The adhesive composition according to the present invention provides excellent light-blocking properties without issues in terms of adhesive physical properties, and has heat resistance and moisture resistance durability that allows it to be used in close proximity to a light source.

[0021] The present invention will be described in more detail below.

[0022]

[0023] One embodiment of the present invention relates to an adhesive composition comprising an acrylic copolymer, a crosslinking agent, and a pigment, wherein the pigment comprises an organic black pigment, and the adhesive composition satisfies a specific range of full-wavelength transmittance under specific thickness conditions of the adhesive layer after curing.

[0024]

[0025] An adhesive composition according to one embodiment of the present invention provides excellent light-blocking properties without issues in terms of adhesive properties and has heat resistance and moisture resistance durability that allows it to be used in proximity to a light source.

[0026] Specifically, the adhesive composition according to one embodiment of the present invention has a full-wave transmittance of 3% or more and less than 10% at a thickness of 50 μm of the adhesive layer after curing.

[0027]

[0028] The above-mentioned full-wave transmittance refers to the transmittance in the visible light region, for example, the full-wave region of 200 nm to 800 nm.

[0029] In this specification, the full-wave transmittance value represents the maximum transmittance in the full-wave region.

[0030]

[0031] When the conditions for the full-wavelength transmittance of the adhesive layer after curing are satisfied, excellent light-blocking properties can be secured.

[0032] Specifically, if the full-wavelength transmittance of the adhesive layer after curing exceeds the upper limit, it may be difficult to secure light-blocking properties, and if the lower limit is not satisfied, alignment during bonding may not be easy.

[0033] The conditions for the full-wavelength transmittance of the adhesive layer after curing can be controlled by adjusting the type and / or content of the pigment used, the type and / or content of the constituent monomers of the acrylic copolymer, etc.

[0034] The full-wave transmittance of the above adhesive layer can be measured by the method described in the experimental example below.

[0035]

[0036] An adhesive composition according to one embodiment of the present invention may have an optical density of 1.0 or higher at a thickness of 50 μm of the adhesive layer after curing.

[0037] If the above optical density is less than 1.0, it may be difficult to secure light-blocking properties.

[0038] The above optical concentration can be measured by the method described in the experimental examples below.

[0039]

[0040] Acrylic copolymer (A)

[0041] In one embodiment of the present invention, the acrylic copolymer (A) may be a copolymer of a monomer comprising a carbon-1 to carbon-12 alkyl (meth)acrylate monomer and a crosslinkable polar functional group, serving as a component that controls the viscosity-to-elasticity balance of the adhesive composition. Here, (meth)acrylate means acrylate and / or methacrylate.

[0042] Preferably, the acrylic copolymer may include a monomer having 1 to 3 carbon atoms, an alkyl (meth)acrylate monomer having 4 to 12 carbon atoms, and a monomer having a crosslinkable polar functional group in order to satisfy the full-wavelength transmittance condition of the adhesive layer after curing described above and to improve heat resistance and moisture resistance.

[0043] The above alkyl (meth)acrylate monomer having 1 to 3 carbon atoms is a (meth)acrylate monomer having 1 to 3 carbon atoms, and specific examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, etc. These may be used alone or in a mixture of two or more.

[0044] The above alkyl (meth)acrylate monomer having 1 to 3 carbon atoms may be included in an amount of 20% to 40% by weight, preferably 25% to 35% by weight, based on 100% by weight of the total monomer used in the manufacture of the acrylic copolymer. When the above alkyl (meth)acrylate monomer having 1 to 3 carbon atoms is used in the above content range, the adhesive strength and durability are excellent, and light-blocking properties are easy to control.

[0045] The above alkyl (meth)acrylate monomer having 4 to 12 carbon atoms is a (meth)acrylate monomer having an alkyl group having 4 to 12 carbon atoms, and specific examples thereof include n-butyl (meth)acrylate, 2-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, pentyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, etc. Among these, n-butyl (meth)acrylate is preferred. These may be used alone or in a mixture of two or more types.

[0046] The above alkyl (meth)acrylate monomer having 4 to 12 carbon atoms may be included in an amount of 55% to 75% by weight, preferably 60% to 70% by weight, based on 100% by weight of the total monomer used in the manufacture of the acrylic copolymer. When the above alkyl (meth)acrylate monomer having 4 to 12 carbon atoms is used in the above content range, the adhesive strength and durability are excellent, and light-blocking properties are easy to control.

[0047] The monomer containing the above-mentioned crosslinkable polar functional group is a component intended to impart durability and cutability by providing cohesive force or adhesive strength through chemical bonding with the crosslinking agent described later, and examples include monomers having hydroxyl groups, monomers having amide groups, monomers having tertiary amine groups, monomers having carboxyl groups, etc. These may be used alone or in a mixture of two or more types.

[0048] Monomers having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, 2-hydroxypropylene glycol (meth)acrylate, hydroxyalkylene glycol (meth)acrylate having 2-4 carbon atoms in the alkylene group, 4-hydroxybutylvinyl ether, 5-hydroxypentylvinyl ether, 6-hydroxyhexylvinyl ether, 7-hydroxyheptylvinyl ether, 8-hydroxyoctylvinyl ether, 9-hydroxynonylvinyl ether, and Examples include 10-hydroxydecyl vinyl ether, among which 4-hydroxybutyl acrylate, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl vinyl ether, etc. are preferred.

[0049] Monomers having an amide group include (meth)acrylamide, N-isopropyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, 3-hydroxypropyl(meth)acrylamide, 4-hydroxybutyl(meth)acrylamide, 6-hydroxyhexyl(meth)acrylamide, 8-hydroxyoctyl(meth)acrylamide, 2-hydroxyethylhexyl(meth)acrylamide, etc., among which (meth)acrylamide is preferred.

[0050] Monomers having a tertiary amine group include N,N-(dimethylamino)ethyl(meth)acrylate, N,N-(diethylamino)ethyl(meth)acrylate, N,N-(dimethylamino)propyl(meth)acrylate, etc.

[0051] Monomers having a carboxyl group include monoprotic acids such as (meth)acrylic acid and crotonic acid; diprotic acids such as maleic acid, itaconic acid and fumaric acid and their monoalkyl esters; 2-carboxyethyl acrylate; 3-(meth)acryloylpropionic acid; succinic anhydride ring-opening adducts of 2-hydroxyalkyl (meth)acrylate having 2-3 carbon atoms in the alkyl group; succinic anhydride ring-opening adducts of hydroxyalkylene glycol (meth)acrylate having 2-4 carbon atoms in the alkyl group; and compounds obtained by ring-opening succinic anhydride to caprolactone adducts of 2-hydroxyalkyl (meth)acrylate having 2-3 carbon atoms in the alkyl group, among which (meth)acrylic acid and 2-carboxyethyl acrylate are preferred.

[0052] The monomer containing the above-mentioned crosslinkable polar functional group may be included in an amount of 1% to 10% by weight, preferably 2% to 7% by weight, based on 100% by weight of the total monomer used in the manufacture of the acrylic copolymer. When the monomer containing the above-mentioned crosslinkable polar functional group is used in the above content range, the adhesive strength and durability are excellent.

[0053] In one embodiment of the present invention, regarding adhesive strength, durability and light-blocking properties, the acrylic copolymer may comprise 20% to 40% by weight of an alkyl (meth)acrylate monomer having 1 to 3 carbon atoms, 55% to 75% by weight of an alkyl (meth)acrylate monomer having 4 to 12 carbon atoms, and 1% to 10% by weight of a monomer comprising a crosslinkable polar functional group.

[0054] In one embodiment of the present invention, the acrylic copolymer may further include an aromatic acrylic monomer as a monomer to improve light-blocking properties and heat resistance and moisture resistance.

[0055] The above aromatic acrylic monomer is an acrylic monomer having an aromatic group within its molecule, and specific examples include pentabromophenyl (meth)acrylate, 2-(naphthalene-2-yloxy)ethyl (meth)acrylate, 2-(naphthalene-2-ylthio)ethyl (meth)acrylate, 1-ethoxylatedphenol (meth)acrylate, phenylphenol ethoxy (meth)acrylate, phenoxybenzyl (meth)acrylate, phenoxyethyl (meth)acrylate, biphenylmethyl (meth)acrylate, 1-pyrenemethyl (meth)acrylate, etc., among which phenoxyethyl (meth)acrylate is preferred. These may be used alone or in a mixture of two or more types.

[0056] The above aromatic acrylic monomer may be included in an amount of 15% by weight or less, for example, 1% to 5% by weight, based on 100% by weight of the total monomer used in the manufacture of the acrylic copolymer. When the above aromatic acrylic monomer is used in the above content range, durability is excellent.

[0057] The above acrylic copolymer may further contain other monomers in addition to the monomers in a range that does not reduce physical properties such as adhesiveness, durability, adhesion, and light-blocking properties, for example, 10 weight percent or less relative to the total amount of monomers.

[0058] The method for manufacturing the above acrylic copolymer is not particularly limited and can be manufactured using methods commonly used in the field, such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization, with solution polymerization being preferred. In addition, solvents, polymerization initiators, and chain transfer agents commonly used during polymerization may be used.

[0059] The above acrylic copolymer has a weight-average molecular weight (polystyrene equivalent, Mw) measured by gel permeation chromatography (GPC) typically ranging from 50,000 to 2 million, and preferably from 400,000 to 2 million. If the weight-average molecular weight is less than 50,000, the cohesive force between copolymers is insufficient, which may cause problems with adhesive durability, and if it exceeds 2 million, a large amount of dilution solvent may be required to ensure processability during coating.

[0060]

[0061] Crosslinking agent (B)

[0062] In one embodiment of the present invention, the crosslinking agent (B) is a component capable of improving adhesion and durability, and maintaining reliability at high temperatures and the shape of the adhesive.

[0063] Specifically, the above-mentioned crosslinking agents may include isocyanate-based, aziridine-based, epoxy-based, melamine-based, peroxide-based, metal chelate-based, and oxazoline-based agents, and among these, isocyanate-based crosslinking agents are preferred in terms of tackiness, durability, adhesion, and light-blocking properties.

[0064] Specifically, the above isocyanate-based crosslinking agent may be a diisocyanate compound such as tolylene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethylxylene diisocyanate, naphthalene diisocyanate, etc.; an adduct formed by reacting 3 moles of a diisocyanate compound with 1 mole of a polyhydric alcohol compound such as trimethylolpropane, an isocyanurate formed by self-condensing 3 moles of a diisocyanate compound, a biuret formed by condensing the remaining 1 mole of diisocyanate with a diisocyanate urea obtained from 2 moles of the 3 moles of diisocyanate compounds, a polyfunctional isocyanate compound containing three functional groups such as triphenylmethane triisocyanate, methylene bistriisocyanate, etc.

[0065] As the above isocyanate-based crosslinking agent, a non-yellowing isocyanate-based crosslinking agent is preferred, and in particular, xylene diisocyanate, or an adduct obtained by reacting 3 moles of xylene diisocyanate with 1 mole of a polyhydric alcohol compound such as trimethylolpropane is preferred.

[0066] The above aziridine-based crosslinking agent may include trimethylolpropane-tri-β-aziridinyl propionate, tetramethylolmethane-tri-β-aziridinyl propionate, N,N'-hexamethylene-1,6-bis(1-aziridine carboxyamide), N,N'-toluene-2,4-bis(1-aziridine carboxyamide), N,N'-diphenylmethane-4-4'-bis(1-aziridine carboxyamide), or trimethylolpropane-tri-β-(2-methylaziridine)propionate.

[0067] The above epoxy crosslinking agent may be sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, resorcin diglycidyl ether, or N,N,N',N'-tetraglycidyl-m-xylenediamine.

[0068] The above melamine-based crosslinking agent may include hexamethoxymethylol melamine, etc.

[0069] The above metal chelate-based crosslinking agents include diisopropoxyaluminum monooleylacetoacetate, monoisopropoxyaluminum bisoleylacetoacetate, monoisopropoxyaluminum monooleate monoethylacetoacetate, diisopropoxyaluminum monolaurylacetoacetate, diisopropoxyaluminum monostearylacetoacetate, diisopropoxyaluminum monoisostearylacetoacetate, monoisopropoxyaluminum mono-N-lauroyl-β-aranate monolaurylacetoacetate, aluminum trisacetylacetonate, aluminum bis(isobutylacetonate) chelate monoacetylacetonate, aluminum bis(isobutylacetonate) chelate monoacetylacetonate, aluminum bis(2-ethylhexylacetoacetate) chelate, Monoacetylacetonate aluminum bis(dodecylacetoacetate) chelate, monoacetylacetonate aluminum bis(oleylacetoacetate) chelate, etc. can be used.

[0070] These crosslinking agents can be used alone or in combination of two or more.

[0071]

[0072] The above crosslinking agent may be contained in an amount of 0.1 to 3 parts by weight, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the acrylic copolymer. If the content of the crosslinking agent is less than 0.1 parts by weight, the cohesive force becomes small due to insufficient degree of crosslinking, which may impair the properties of adhesive durability and cutability; if it exceeds 3 parts by weight, problems may arise in relieving residual stress due to excessive crosslinking reaction.

[0073]

[0074] Pigment (C)

[0075] In one embodiment of the present invention, the pigment (C) includes an organic black pigment as a component that provides light-blocking properties.

[0076] The above organic black pigment may be one having a polycyclic structure and may be used as any known pigment without special limitations, but specifically, lactam black, aniline black, perylene black, etc. may be used. These may be used individually or in combination of two or more types.

[0077] Among organic black pigments, using lactam black may be desirable in terms of controlling the full-wavelength transmittance conditions of the adhesive layer after curing as described above and improving heat resistance and moisture resistance durability.

[0078] The above organic black pigment may be included in an amount of 50% or more, for example, 50% to 100% by weight, preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more, based on 100% by weight of the total pigment in terms of adhesion, durability, and light-blocking properties.

[0079] In particular, the above pigment may be composed of an organic black pigment in terms of adhesion, durability, and light-blocking properties.

[0080] The amount of the above pigment can be controlled so as to satisfy the full-wavelength transmittance condition of the adhesive layer after curing described above while ensuring adhesion and durability.

[0081] For example, the pigment may be contained in an amount of 0.01 to 1 part by weight, preferably 0.1 to 1 part by weight, and more preferably 0.1 to 0.5 parts by weight, per 100 parts by weight of the acrylic copolymer.

[0082]

[0083] An adhesive composition according to one embodiment of the present invention may further include a silane coupling agent.

[0084] Examples of the above silane coupling agents include vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, Examples include N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatepropyltriethoxysilane, and substituted acetamide group-containing silanes, and 3-glycidoxypropyltrimethoxysilane is particularly preferred in terms of durability.

[0085] The content of the silane coupling agent may be 0.01 to 2 parts by weight per 100 parts by weight of the acrylic copolymer. It is desirable for the content of the silane coupling agent to be within this range in terms of durability.

[0086]

[0087] In addition to the above-mentioned components, an adhesive composition according to one embodiment of the present invention may further include an antistatic agent, an antioxidant, a corrosion inhibitor, a leveling agent, a surface lubricant, an antifoaming agent, a filler, a plasticizer, a light stabilizer, a reaction initiator, a solvent, etc., in order to control the adhesive strength, cohesive strength, viscosity, elastic modulus, glass transition temperature, coating properties, etc., required according to the application.

[0088]

[0089] In order to satisfy the full-wavelength transmittance condition of the adhesive layer after curing described above, and to ensure excellent heat resistance and moisture resistance durability, the adhesive composition according to one embodiment of the present invention may contain carbon black in an amount of less than 0.1 weight%, preferably less than 0.05 weight%, and more preferably may not substantially contain carbon black.

[0090]

[0091] One embodiment of the present invention relates to an adhesive sheet formed using the adhesive composition.

[0092] An adhesive sheet according to one embodiment of the present invention is formed using the adhesive composition described above, thereby exhibiting excellent light-blocking properties without issues in terms of adhesive physical properties, and possessing heat resistance and moisture resistance durability that allows it to be used in proximity to a light source.

[0093] In addition, the adhesive sheet according to one embodiment of the present invention may have fewer than 5 bubbles or peeling after attaching one side of the adhesive sheet to a glass substrate and leaving it at a temperature of 95°C for 1000 hours.

[0094] In addition, the adhesive sheet according to one embodiment of the present invention may have fewer than 5 bubbles or peeling after attaching one side of the adhesive sheet to a glass substrate and leaving it for 1,000 hours at a temperature of 85°C and a relative humidity of 85%.

[0095]

[0096] The adhesive sheet above may have an adhesive layer formed from an adhesive composition according to the present invention on a substrate film, or an adhesive layer formed from an adhesive composition according to the present invention interposed between two substrate films.

[0097] Examples of the above-described films include polyolefin-based films, polyester-based films, acrylic-based films, styrene-based films, amide-based films, polyvinyl chloride films, polyvinylidene chloride films, polycarbonate films, etc., and these may be appropriately released using silicone-based, fluorine-based, silica powder, etc.

[0098] It is preferable that the thickness of the above-mentioned substrate film be 30㎛ to 80㎛. If it is less than 30㎛, the substrate film is susceptible to defects such as scratches, and if it exceeds 80㎛, handling performance may be reduced.

[0099] An adhesive layer can be formed by applying an adhesive composition onto a single substrate film. The application method is not particularly limited as long as it is a method known in the field, and, for example, methods such as a bar coater, air knife, gravure, reverse roll, kiss roll, spray, blade, die coater, casting, and spin coating may be used. Specifically, the adhesive layer can be formed by applying an adhesive composition onto a single substrate film and curing it by drying at 30 to 150°C for 1 second to 2 hours, preferably 5 seconds to 1 hour. Subsequently, another substrate film can be bonded onto the adhesive layer.

[0100] The thickness of the adhesive layer may be 5㎛ to 200㎛, preferably 30㎛ to 100㎛. If the thickness of the adhesive layer is less than 5㎛, the durability may be poor, and if it exceeds 200㎛, the peelability may be poor.

[0101] An adhesive sheet according to one embodiment of the present invention may improve adhesion by surface treating the adhesive layer before bonding.

[0102] The surface treatment method is not particularly limited. For example, the surface of the adhesive layer can be activated by methods such as corona discharge treatment, plasma treatment, ultraviolet irradiation, electron beam irradiation, or the application of an anchoring agent.

[0103]

[0104] An adhesive sheet according to one embodiment of the present invention can be applied to various image display devices, such as conventional liquid crystal displays (LCDs), electroluminescent displays (EL), plasma display displays (PDPs), field emission displays (FEDs), and organic light-emitting diodes (OLEDs).

[0105] Specifically, it can be used for bonding between components of a liquid crystal display (LCD) or an organic light-emitting diode (OLED) for purposes such as preventing light leakage or preventing reflection. For example, in a liquid crystal display device equipped with a liquid crystal display module unit (LCD unit) and a backlight unit (BL unit), it can be used for bonding between the said LCD unit and the said BL unit. In addition, it can be used for bonding between a window glass and an OLED device.

[0106]

[0107] Accordingly, one embodiment of the present invention relates to an image display device comprising the adhesive sheet.

[0108]

[0109] The present invention will be explained more specifically below through examples, comparative examples, and experimental examples. These examples, comparative examples, and experimental examples are intended solely to illustrate the present invention, and it is obvious to those skilled in the art that the scope of the present invention is not limited thereto.

[0110]

[0111] Preparation Example: Preparation of acrylic copolymer

[0112] Preparation Example 1: Acrylic copolymer (A-1)

[0113] 69.5 wt% of n-butyl acrylate (BA), 25 wt% of methyl acrylate (MA), 0.5 wt% of acrylic acid (AA), and 5 wt% of 2-hydroxyethyl acrylate (2-HEA) were added to a 1 L reactor equipped with a cooling device for easy temperature control and nitrogen gas reflux, and then 100 wt% of ethyl acetate (EA) was added as a solvent. Afterward, nitrogen gas was introduced for 1 hour to remove oxygen and the mixture was recirculated, and the temperature was maintained at 62°C. After uniformly stirring the mixture, 0.07 wt% of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours to produce a copolymer (A-1) with a weight-average molecular weight of 1.23 million.

[0114]

[0115] Preparation Example 2: Acrylic copolymer (A-2)

[0116] An acrylic copolymer (A-2) was prepared by carrying out the same procedure as in Preparation Example 1 above, but controlling the monomer content and weight-average molecular weight as shown in Table 1 below.

[0117]

[0118] Preparation Example 3: Acrylic copolymer (A-3)

[0119] An acrylic copolymer (A-3) was prepared by carrying out the same procedure as in Preparation Example 1 above, but controlling the monomer content and weight-average molecular weight as shown in Table 1 below.

[0120]

[0121] Copolymer Monomer Weight Average Molecular Weight (Mw) M-1 M-2 M-3 M-4 Preparation Example 1A-169.5% 25.0% 0.5% 5.0% 1,230,000 Preparation Example 2A-264.5% 30.0% 0.5% 5.0% 1,200,000 Preparation Example 3A-362.0% 35.0% 0.5% 2.5% 1,270,000

[0122]

[0123] M-1: n-butyl acrylate

[0124] M-2: Methyl acrylate

[0125] M-3: Acrylic acid

[0126] M-4: 2-hydroxyethyl acrylate

[0127]

[0128] Examples and Comparative Examples: Preparation of Adhesive Composition and Adhesive Sheet

[0129] An adhesive composition was prepared by mixing according to the composition of Table 2 below (parts by weight). The adhesive composition was mixed with an ethyl acetate solvent to achieve a solid content of 20% by weight, taking into account coating properties.

[0130]

[0131] Copolymer Crosslinking Agent Silane Coupling Agent Pigment Type Content Type Content Type Content Type Content Example 1A-1100B-10.15C-10.3D-10.3 Example 2A-2100B-10.15C-10.3D-10.3 Example 3A-2100B-20.15C-10.3D-10.3 Example 4A-3100B-10.2C-10.3D-10.3 Comparative Example 1A-1100B-10.15C-10.3E-10.3 Comparative Example 2A-1100B-10.15C-10.3E-10.14 Comparative Example 3A-1100B-10.15C-10.3

[0132]

[0133] copolymer

[0134] A-1 to A-3: Acrylic copolymers prepared in Preparation Examples 1 to 3, respectively

[0135] crosslinking agent

[0136] B-1: D-110N (Xylene diisocyanate (XDI)-based crosslinking agent, Mitsui Chemical)

[0137] B-2: Coronate-HXR (Hexamethylene diisocyanate (HDI)-based crosslinking agent, Japan Polyurethane Industry)

[0138] Silane coupling agent

[0139] C-1: KBM-403 (3-glycidoxypropyl trimethoxysilane, Shin-Etsu)

[0140] organic pigments

[0141] D-1: Irgaphor® Black S 0100 CF (BASF)

[0142] inorganic pigments

[0143] E-1: Carbon Black

[0144]

[0145] The adhesive compositions of the examples and comparative examples prepared above were applied onto a silicone release-treated film and dried at 100°C for 2 minutes, after which the release film was laminated to form an adhesive sheet.

[0146]

[0147] Experimental Example 1:

[0148] The physical properties of the adhesive sheets prepared in the examples and comparative examples were measured by the following method, and the results are shown in Table 3 below.

[0149]

[0150] (1) Adhesion

[0151] After removing one layer of the release film from an adhesive sheet manufactured to a thickness of 50 μm, the sheet was bonded to 50 μm PET and cut to a size of 25 mm x 85 mm. After peeling off the remaining release film, corona treatment or plasma treatment was performed on the surface of the adhesive, followed by lamination onto a glass substrate and autoclave treatment to produce a specimen. Room temperature adhesion strength was measured by leaving the prepared specimen under conditions of 23°C and 50% RH for 24 hours, and then peeling the adhesive layer using a universal tensile testing machine (UTM, Instron) at a peeling speed of 300 mm / min and a peeling angle of 180°. High temperature and high temperature / high humidity adhesion strength were measured after leaving the specimen in the measurement chamber of the universal tensile testing machine under conditions of 95°C and 85°C / 85% RH for 2 hours, respectively.

[0152]

[0153] (2) Transmittance and optical density

[0154] An adhesive sheet manufactured to a thickness of 50 μm was cured by leaving it at room temperature for 7 days, after which the release films on both sides were removed and a specimen was prepared on an organic substrate. The transmission spectrum at wavelengths from 200 nm to 800 nm was measured using a spectrophotometer (Shimadzu, UV-2450). The optical densitometer was measured using a transmission densitometer (X-rite).

[0155]

[0156] (3) Durability (heat resistance, moisture resistance)

[0157] An adhesive sheet manufactured to a thickness of 50 µm was cut to a size of 200 mm x 300 mm, and after peeling off the release film, the exposed adhesive layer was attached to a glass substrate (210 mm x 350 mm x 0.7 mm) and subjected to autoclave treatment (50°C x 20 min, 0.5 MPa) to prepare a specimen. For heat resistance evaluation, the occurrence of bubbles or delamination was observed after leaving the specimen at temperatures of 80°C and 95°C for 1,000 hours. For moisture resistance evaluation, the occurrence of bubbles or delamination was observed after leaving the specimen at 60°C and 90% RH, and at 85°C and 85% RH for 1,000 hours. At this time, the specimen was observed after being left at room temperature for 24 hours immediately before evaluating its condition.

[0158] <Evaluation Criteria>

[0159] ⓞ: No bubbles or peeling.

[0160] ○: Bubbles or peeling < 5

[0161] △: 5 items ≤ bubbles or peeling < 10 items

[0162] X: 10 pieces ≤ bubbles or peeling

[0163]

[0164] Adhesion [N / 25mm] Wavelength Transmittance (%) [Maximum Value] Optical Density [OD] Durability Heat Resistance Humidity Resistance Room Temperature 95℃ 85℃ / 85% 80℃ 95℃ 60℃ / 90% 85℃ / 85% Example 1 15.4 17.8 18.18.11.58 ◎○ ◎○ Example 2 18.1 18.5 18.37.9 1.61 ◎◎ ◎○ Example 3 17.5 18.0 17.9 7.8 1.61 ◎◎ ◎○ Example 4 20.2 23.5 24.0 7.5 1.66 ◎◎ ◎ Comparative Example 1 23.6 28.5 28.5 03.55 ○ △ ○ X Comparative Example 2 24.1 22.0 23.5 8.3 1.13 ◎ ○ ◎△ Comparative Example 323.112.011.092.30.03◎◎◎◎

[0165]

[0166] Through Table 3 above, it can be confirmed that the adhesive sheets of Examples 1 to 4 according to the present invention exhibit excellent light-blocking properties by satisfying a specific range of full-wavelength transmittance under specific thickness conditions of the adhesive layer after curing, while having no problems in terms of adhesive properties and possessing heat resistance and moisture resistance durability that allows them to be used in proximity to a light source.

[0167] On the other hand, in Comparative Example 1, the transmittance was too low compared to the target, and a problem that was relatively visible in appearance occurred during the durability evaluation. In addition, in Comparative Example 2, when compared to Example 1, the optical density value was lower relative to the equivalent transmittance, indicating a disadvantage in terms of light leakage. Meanwhile, in Comparative Example 3, the transmittance across the entire wavelength was found to be poor.

[0168]

[0169] As specific parts of the present invention have been described in detail above, it is evident to those skilled in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of the present invention. Those skilled in the art will be able to make various applications and modifications within the scope of the present invention based on the above description.

[0170] Accordingly, the substantial scope of the present invention shall be defined by the appended claims and their equivalents.

Claims

1. An adhesive composition comprising an acrylic copolymer, a crosslinking agent, and a pigment, wherein The above pigment includes an organic black pigment, and An adhesive composition having a full-wave transmittance of 3% or more and less than 10% at a thickness of 50㎛ of the adhesive layer after curing.

2. The adhesive composition according to claim 1, wherein the acrylic copolymer comprises 20% to 40% by weight of an alkyl (meth)acrylate monomer having 1 to 3 carbon atoms, 55% to 75% by weight of an alkyl (meth)acrylate monomer having 4 to 12 carbon atoms, and 1% to 10% by weight of a monomer containing a crosslinkable polar functional group.

3. The adhesive composition according to claim 1, wherein the crosslinking agent comprises an isocyanate-based crosslinking agent.

4. In claim 1, the pigment is an adhesive composition comprising lactam black.

5. An adhesive sheet formed using an adhesive composition according to any one of claims 1 to 4.

6. An image display device including an adhesive sheet according to paragraph 5.