Adhesive composition for optical member, adhesive sheet, and display comprising same

Abstract

The present invention relates to an adhesive composition for an optical member, including an acrylic copolymer and a plasticizer, an adhesive sheet, and a display comprising same. The acrylic copolymer is a product of copolymerization of: a) a (meth) acrylate monomer having 1 to 3 carbon atoms; b) a (meth) acrylate monomer having 4 to 12 carbon atoms; and c) a monomer containing at least one functional group selected from a hydroxyl group (OH) and a carboxyl group (COOH), wherein the adhesive sheet comprising the adhesive composition has an elastic modulus at -20 ℃ of 5.0 E+05 Pa to 1.0 E+07 Pa.

Description

Adhesive composition for optical member, adhesive sheet, and display including the same

[0001] The present invention relates to an adhesive composition for an optical member, an adhesive sheet, and a display including the same.

[0002]

[0003] The display industry uses a number of optically transparent pressure-sensitive adhesives to mount touch panels or touch screens or to achieve high brightness and high transmittance.

[0004] In the above display industry, adhesives used to attach transparent films or UTG (ultra thin glass) to touch screens or touch panels are required to have both adhesion to various substrates and durability that can suppress curling or bubble formation even when exposed to harsh conditions such as high temperature and high humidity. In particular, in fields such as electronic materials that require precise dimensional stability, there is a need for the development of an adhesive composition that can prevent curling, bubble formation, or peeling under harsh conditions such as high temperature and high humidity as described above, and has excellent durability as the impact resistance performance of the top layer is improved as the cover glass is thinned.

[0005] Korean Patent Publication No. 10-0995510 discloses an acrylic pressure-sensitive adhesive composition comprising: a) an acrylic copolymer; b) a hydrophilic plasticizer; and c) a hydrophobic plasticizer, thereby exhibiting excellent wettability regardless of the surface properties of the adherend and simultaneously preventing smudging under humid and heat conditions, thereby enhancing the adherend's stain resistance. However, the acrylic copolymer disclosed in the patent has the disadvantage of low durability, which can easily lead to defects such as lifting and breaking during folding.

[0006] Accordingly, there is a need for the development of an adhesive composition, an adhesive sheet, and a display including the same that has excellent folding properties, is impact-resistant, and has excellent adhesive performance without degradation.

[0007]

[0008] To address the above-described problems, the present invention provides an adhesive composition, an adhesive sheet, and a display comprising the same, which have improved properties in terms of low-temperature elastic modulus, impact resistance, and foldability. In particular, the present invention provides a display having improved elastic modulus, foldability, and impact resistance at low temperatures of -20°C.

[0009] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0010]

[0011] The present invention relates to an adhesive composition for an optical member comprising an acrylic copolymer and a plasticizer, wherein the acrylic copolymer is copolymerized by including: a) a (meth)acrylate monomer having 1 to 3 carbon atoms; b) a (meth)acrylate monomer having 4 to 12 carbon atoms; and c) a monomer containing at least one functional group selected from a hydroxyl group (OH) and a carboxyl group (COOH), and the elastic modulus of an adhesive sheet comprising the adhesive composition at -20°C is characterized by being 5.0E+05Pa to 1.0E+07Pa.

[0012] In the present invention, the above b) alkyl (meth)acrylate monomer having 4 to 12 carbon atoms may have a straight or branched alkyl chain.

[0013] In the present invention, the acrylic copolymer may be polymerized by including, based on 100 parts by weight of the total monomers included in the polymerization, a) 20 to 45 parts by weight of an alkyl (meth)acrylate monomer having 1 to 3 carbon atoms; b) 30 to 79.95 parts by weight of an alkyl (meth)acrylate monomer having 4 to 12 carbon atoms; and c) 0.05 to 3 parts by weight of a monomer containing a hydroxyl group or carboxylic acid.

[0014] In the present invention, the weight average molecular weight (Mw) of the acrylic copolymer may be 50,000 to 2,000,000.

[0015] The present invention may include at least one selected from a non-polar plasticizer selected from the group consisting of an adipate compound, a maleate compound, and a non-phthalate compound, and a polar plasticizer including at least one functional group selected from a hydroxyl group, a carboxyl group, and an amide group, and in particular, at least one selected from a non-polar plasticizer selected from dioctyl adipate, diisononyl adipate, diisooctyl adipate, dioctyl maleate, bis(2-ethylhexyl)maleate, dibutyl maleate, diethylhexylcyclohexane, and 1,2-cyclohexane dicarboxylic acid diisononyl ester.

[0016] The present invention may include 0.5 to 10 parts by weight of a plasticizer per 100 parts by weight of the acrylic copolymer.

[0017] The adhesive composition of the present invention may further include at least one selected from the group consisting of a crosslinking agent, a silane coupling agent, an adhesive-providing resin, an antioxidant, an anti-corrosion agent, a leveling agent, a surface lubricant, a dye, a pigment, an anti-foaming agent, a filler, a light stabilizer, an antistatic agent, and a solvent.

[0018] In addition, the present invention relates to an adhesive sheet comprising the adhesive composition for an optical member, wherein the adhesive sheet may have excellent folding performance even after folding at 25 times / min and holding for 0.2 seconds after folding once for 50,000 times or more.

[0019] The present invention also relates to a display including the adhesive sheet.

[0020]

[0021] The adhesive composition according to the present invention and the adhesive sheet comprising the same can have improved properties in terms of elasticity, impact resistance, and folding performance by satisfying the range of elasticity modulus at -20°C of 5.0E+05Pa to 1.0E+07Pa, and in particular, exhibit excellent durability and folding performance even at low temperatures of -20°C.

[0022] In addition, according to the present invention, a display having excellent folding characteristics can be provided by including an adhesive composition and an adhesive sheet including the same.

[0023]

[0024] The present invention relates to an adhesive composition for an optical member having improved low-temperature elastic modulus, impact resistance and foldability, an adhesive sheet and a display including the same.

[0025] Specifically, the present invention relates to an adhesive composition for an optical member comprising an acrylic copolymer and a plasticizer, wherein the acrylic copolymer is copolymerized by including a) a (meth)acrylate monomer having 1 to 3 carbon atoms; b) a (meth)acrylate monomer having 4 to 12 carbon atoms; and c) a monomer containing at least one functional group selected from a hydroxyl group (OH) and a carboxyl group (COOH), and an elastic modulus at -20°C of an adhesive sheet comprising the adhesive composition may be characterized by being 5.0E+05Pa to 1.0E+07Pa, and relates to a display comprising the same. An adhesive sheet comprising an adhesive composition according to one embodiment of the present invention has excellent properties in terms of low-temperature elastic modulus, impact resistance, and folding performance by satisfying the -20°C elastic modulus range, and specifically, can exhibit excellent folding performance even after folding at 25 times / min and holding for 0.2 seconds after folding once for more than 50,000 times. In the present invention, excellent folding performance means that substantially no abnormality occurs at the folding portion, and specifically, it can mean that substantially no breakage, lifting, and / or peeling occurs at the folding portion, and more specifically, it can mean that no defects such as breakage, lifting, and / or peeling occur when folding at a radius of curvature of 2 mm for more than 50,000 times.

[0026]

[0027] Hereinafter, embodiments of the present invention will be described in more detail. The terms used herein are for the purpose of describing embodiments and are not intended to limit the present invention.

[0028] As used herein, the terms 'comprises' and / or 'comprising' are used to mean that they do not exclude the presence or addition of one or more other components and / or ingredients other than the mentioned components and / or ingredients.

[0029] In this specification, the adhesive sheet may mean an adhesive layer and an adhesive film.

[0030]

[0031] <Adhesive composition for optical elements>

[0032] The pressure-sensitive adhesive composition for an optical member of the present invention is characterized by comprising an acrylic copolymer and a plasticizer, wherein the acrylic copolymer is copolymerized by including: a) a (meth)acrylate monomer having 1 to 3 carbon atoms; b) a (meth)acrylate monomer having 4 to 12 carbon atoms; and c) a monomer containing at least one functional group selected from a hydroxyl group (OH) and a carboxyl group (COOH). In addition, the pressure-sensitive adhesive composition for an optical member may further comprise, as necessary, at least one selected from the group consisting of a crosslinking agent, a silane coupling agent, a tackifying resin, an antioxidant, a corrosion inhibitor, a leveling agent, a surface lubricant, a dye, a pigment, an antifoaming agent, a filler, a light stabilizer, an antistatic agent, and a solvent.

[0033] The resin (polymer) included in the pressure-sensitive adhesive composition for optical members must have an appropriately controlled glass transition temperature (Tg) to satisfy basic physical properties such as flexibility, hardness, appearance, and pigment dispersibility while having adhesiveness with the substrate and / or material. In general, (meth)acrylate monomers are monomers with a low glass transition temperature, and in conventional copolymers, they are included only in a very small amount of 2% or less for reasons such as increasing the plasticity and viscosity of the copolymer. However, in the present invention, for the unique purpose of improving foldability at low temperatures, a copolymer can be produced by including a (meth)acrylate monomer in an excess amount compared to the conventional technology. In particular, according to one embodiment of the present invention, among them, a (meth)acrylate monomer having a carbon number of 1 to 3 and a (meth)acrylate monomer having a carbon number of 4 to 12, which have relatively high glass transition temperatures, are included, thereby controlling adhesive durability and physical properties, and a plasticizer is included to control low-temperature elastic modulus to be within a target range, thereby increasing impact resistance, and preventing breakage, lifting, and / or peeling, etc., even during low-temperature folding.

[0034]

[0035] Acrylic copolymer

[0036] The acrylic copolymer included in the pressure-sensitive adhesive composition for an optical member of the present invention may be a copolymerized copolymer including: a) a (meth)acrylate monomer having 1 to 3 carbon atoms; b) a (meth)acrylate monomer having 4 to 12 carbon atoms; and c) a monomer containing at least one functional group selected from a hydroxyl group (OH) and a carboxyl group (COOH). In the present specification, the term "(meth)acrylate" refers to both acrylate and methacrylate.

[0037]

[0038] The above a) (meth)acrylate monomer having 1 to 3 carbon atoms may preferably be linear, and specific examples of the (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, etc.

[0039] In particular, the above a) (meth)acrylate monomer having 1 to 3 carbon atoms has a glass transition temperature (Tg) somewhat higher than the b) (meth)acrylate monomer having 4 to 12 carbon atoms described below, so that the adhesive strength and durability of the adhesive sheet for optical members can be improved, and thus the impact resistance can be improved.

[0040] The acrylic copolymer of the present invention may contain 20 to 45 parts by weight, preferably 22 to 40 parts by weight, of the a) (meth)acrylate monomer having 1 to 3 carbon atoms, based on 100 parts by weight of the total monomers included in the acrylic copolymer polymerization. When the content range is satisfied, adhesion and durability are improved, and there is an advantage in terms of impact resistance.

[0041]

[0042] The above b) (meth)acrylate monomer having 4 to 12 carbon atoms may be linear or branched.

[0043] The glass transition temperature of the above b) (meth)acrylate monomer having 4 to 12 carbon atoms is preferably 0℃ or lower in terms of impact resistance, elastic modulus, and folding property, and examples thereof include n-butyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, etc.

[0044] The acrylic copolymer of the present invention may contain 30 to 79.95 parts by weight, preferably 35 to 77 parts by weight, of the (meth)acrylate monomer having 4 to 12 carbon atoms, based on 100 parts by weight of the total monomers included in the acrylic copolymer polymerization. When the content range is satisfied, there is an advantage in terms of impact resistance, elastic modulus, and folding property.

[0045]

[0046] The monomer containing at least one functional group selected from c) a hydroxyl group (OH) and a carboxyl group (COOH) is, for example, a monoacid such as (meth)acrylic acid, crotonic acid, isocrotonic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, etc.; a diacid such as maleic acid, itaconic acid, fumaric acid, etc., and a monoalkyl ester thereof; Compounds obtained by ring-opening succinic acid to a ring-opening adduct of a 2-hydroxyalkyl (meth)acrylate having 2 to 3 carbon atoms in the alkyl group, a ring-opening adduct of a hydroxyalkylene glycol (meth)acrylate having 2 to 4 carbon atoms in the alkylene group, a caprolactone adduct of a 2-hydroxyalkyl (meth)acrylate having 2 to 3 carbon atoms in the alkyl group, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl acrylate, N-methylol(meth)acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, etc., and among these, acrylic acid (AA), 2-hydroxyethyl methacrylate (2-HEMA), etc. can be preferably used.

[0047] The acrylic copolymer of the present invention may contain 0.05 to 3 parts by weight, preferably 1.0 to 2.5 parts by weight, of the monomer containing at least one functional group selected from c) a hydroxyl group (OH) and a carboxyl group (COOH), based on 100 parts by weight of the total monomers included in the acrylic copolymer polymerization. When the content range is satisfied, there is an advantage in terms of durability.

[0048]

[0049] In addition, the above-mentioned conventional acrylic copolymer may further include other monomers commonly used in the technical field to which the present invention pertains, in addition to the above-mentioned monomers, within a range that does not lower the adhesive strength, and may further include at least one selected from the group consisting of a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, a cyano group-containing monomer, a vinyl ester monomer, an aromatic vinyl monomer, an acid anhydride group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, an imide group-containing monomer, an epoxy group-containing monomer, an ether group-containing monomer, and a nitrogen monomer.

[0050] The above sulfonic acid group-containing monomers include, for example, styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl(meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, sodium vinylsulfonate, etc.

[0051] The above-mentioned phosphoric acid group-containing monomer may include, for example, 2-hydroxyethylacryloyl phosphate, and the above-mentioned cyano group-containing monomer may include, for example, (meth)acrylonitrile.

[0052] The above vinyl ester monomers include, for example, vinyl acetate, vinyl propionate, vinyl laurate, etc., and the above aromatic vinyl monomers include, for example, styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, other substituted styrenes, etc.

[0053] The above acid anhydride-containing monomers include, for example, maleic anhydride, itaconic anhydride, and acid anhydrides thereof.

[0054] The above amide group-containing monomers include, for example, (meth)acrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, 3-hydroxypropyl(meth)acrylamide, 4-hydroxybutyl(meth)acrylamide, 6-hydroxyhexyl(meth)acrylamide, 8-hydroxyoctyl(meth)acrylamide, 2-hydroxyethylhexyl(meth)acrylamide, etc.

[0055] The amino group-containing monomers include, for example, N,N-(dimethylamino)ethyl(meth)acrylate, N,N-(diethylamino)ethyl(meth)acrylate, N,N-(dimethylamino)propyl(meth)acrylate, etc., and the imide group-containing monomers include, for example, cyclohexylmaleimide, isopropyl maleimide, etc.

[0056] The above epoxy group-containing monomers include, for example, (meth)acrylic acid glycidyl, (meth)acrylic acid methyl glycidyl, etc., and the above ether group-containing monomers include, for example, 3-methoxybutyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-methoxybutyl (meth)acrylate, methoxypolyethylene glycol acrylate having an added mole number of oxyethylene of 1 to 15, ethoxy-diethylene glycol (meth)acrylate, ethyl carbitol (meth)acrylate, etc.

[0057] The above nitrogen monomer may include N-(butoxymethyl)acrylamide, etc.

[0058] The above other monomers may be further included in an amount of 10 parts by weight or less based on 100 parts by weight of the total monomers included in the acrylic copolymer polymerization.

[0059]

[0060] The method for producing the copolymer is not particularly limited, and can be produced using methods commonly used in the field, such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization, with solution polymerization being preferred. Additionally, solvents, polymerization initiators, and chain transfer agents for molecular weight control commonly used during polymerization can be used.

[0061] An acrylic copolymer manufactured according to one embodiment of the present invention has the advantage of having a high low-temperature elastic modulus value, thereby improving impact resistance, and can also exhibit properties suitable for a foldable display, such as coatability and adhesion, despite being included in an excessive amount compared to the prior art.

[0062] The above acrylic copolymer preferably has a weight average molecular weight (polystyrene equivalent, Mw) of 50,000 to 2,000,000, preferably 400,000 to 2,000,000, as measured by gel permeation chromatography (GPC). If the weight average molecular weight is less than 50,000, cohesion between copolymers may be insufficient, which may cause problems with adhesive durability, and if it exceeds 2,000,000, a large amount of dilution solvent may be required to ensure fairness during coating.

[0063]

[0064] plasticizer

[0065] The above plasticizer is an additive that reduces the viscosity of a material and increases its plasticity. In one embodiment of the present invention, the adhesive composition for an optical member may include one or two or more of a non-polar plasticizer and a polar plasticizer.

[0066] The above non-polar plasticizer may be at least one selected from the group consisting of adipate compounds, maleate compounds, and non-phthalate compounds. Specifically, the adipate compounds include dioctyl adipate, diisononyl adipate, diisooctyl adipate, etc., the maleate compounds include dioctyl maleate, bis(2-ethylhexyl) maleate, dibutyl maleate, etc., and the non-phthalate compounds include diethylhexylcyclohexane, and 1,2-cyclohexane dicarboxylic acid diisononyl ester, etc.

[0067] The polar plasticizer contains at least one polar functional group within the molecule, and the polar plasticizer of the present invention may be a fatty acid series substance having a polar functional group generally used in foods. The polar plasticizer may contain at least one polar functional group such as a hydroxyl group, a carboxyl group, and / or an amide group, and may contain 1 to 4, preferably 2 to 3, polar functional groups within the molecule. By including the polar functional group within the above range, the adhesive force can be maintained while reducing the elastic modulus.

[0068] The polar plasticizer may be used having a weight average molecular weight (Mw) of 200 to 1,500, preferably 200 to 1,000. When the weight average molecular weight of the polar plasticizer satisfies the above range, there is an advantage in that the possibility of occurrence of defects due to precipitation, etc. in reliability is reduced.

[0069] Specifically, the polar plasticizer may include at least one selected from the group consisting of compounds represented by the following chemical formulas 1 to 3. For example, the compound represented by the following chemical formula 1 may be commonly called castor oil, the compound represented by the following chemical formula 2 may be commonly called dimer acid, and the compound represented by the following chemical formula 3 may be commonly called ricinoleic acid.

[0070] [Chemical Formula 1]

[0071]

[0072]

[0073] [Chemical Formula 2]

[0074]

[0075]

[0076] [Chemical Formula 3]

[0077]

[0078] In one embodiment of the present invention, when a plasticizer is used in an adhesive composition for an optical member, it may be more effective in terms of low-temperature folding properties to use a non-polar plasticizer rather than a polar plasticizer because it exhibits lower low-temperature elastic modulus characteristics.

[0079] The pressure-sensitive adhesive composition for an optical member of the present invention may contain 0.5 to 10 parts by weight, preferably 1.0 to 5 parts by weight, of the plasticizer relative to 100 parts by weight of the total acrylic copolymer. When the content range is satisfied, there is an advantage in terms of low-temperature elastic modulus. When the plasticizer is contained in an excessive amount exceeding the above range, a bleed-out phenomenon in which the adhesive flows out of the area may occur, which may cause problems with durability. When the plasticizer is contained in an amount less than the above range, there may be a disadvantage in that low-elasticity characteristics cannot be exhibited.

[0080]

[0081] Other additives and solvents

[0082] The above additives may be selectively added as needed, and may include crosslinking agents, silane coupling agents, adhesive-providing resins, antioxidants, corrosion inhibitors, leveling agents, surface lubricants, dyes, pigments, antifoaming agents, fillers, light stabilizers, antistatic agents, etc., in order to control the adhesive strength, cohesive strength, viscosity, elastic modulus, glass transition temperature, etc. required depending on the intended use.

[0083] The crosslinking agent is a component included to enhance the cohesive strength of the adhesive. Any component capable of enhancing the cohesive strength of the adhesive by appropriately crosslinking the acrylic copolymer described above is not particularly limited. Accordingly, adhesion and durability can be improved, and reliability and the shape of the adhesive can be maintained at high temperatures.

[0084] The crosslinking agent may include, for example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a metal chelate-based compound (organometallic compound), etc. These may be used alone or in combination of two or more, but are not limited thereto.

[0085] Examples of the above isocyanate crosslinking agent include polyfunctional isocyanate compounds such as toluene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, tetramethylxylene diisocyanate, or naphthalene diisocyanate, or compounds obtained by reacting the above polyfunctional isocyanate compounds with polyol compounds such as trimethylol propane. These may be used alone or in combination of two or more. Products include D-110N and D-103 (Mitsui Chemicals).

[0086] Examples of the above epoxy crosslinking agent include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidyl ethylenediamine, and glycerin diglycidyl ether. These may be used alone or in combination of two or more.

[0087] Examples of the above oxazoline-based crosslinking agent include copolymers polymerized by including at least one monomer containing an oxazoline group, such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. These may be used alone or in combination of two or more.

[0088] Examples of the above aziridine crosslinking agent include N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), triethylene melamine, bisisopropyl-1-(2-methylaziridine), and tri-1-aziridinylphosphineoxide. These may be used alone or in combination of two or more.

[0089] Examples of the above metal chelating cross-linking agent include compounds in which a polyvalent metal such as aluminum, iron, zinc, tin, titanium, antimony, magnesium and / or vanadium is coordinated to acetylacetone or ethyl acetoacetate. These may be used alone or in combination of two or more.

[0090] In one embodiment of the present invention, when a metal chelate compound crosslinking agent is included, there is a technical advantage in that the occurrence of fracture, lifting, peeling, etc. at the folding site can be minimized. Specifically, since other crosslinking agents are crosslinked through covalent bonds, they may cause cracks during folding, but the metal chelate compound is crosslinked through ionic bonds with higher bond energy than these, and when included in the adhesive composition together with the acrylic copolymer, it can be more advantageous in achieving the purpose of improving foldability by acting as a stress relief function during folding from the perspective of foldability.

[0091] The crosslinking agent is preferably included in an amount of 0.1 to 1 part by weight, and more preferably, 0.1 to 0.5 part by weight, based on the total weight of the acrylic copolymer. If the content of the crosslinking agent is less than 0.1 part by weight, the adhesive strength or cohesive strength of the adhesive composition may be somewhat reduced, and if it exceeds 1 part by weight, compatibility may be somewhat reduced, surface migration may occur, and the crosslinking reaction may proceed too much, resulting in somewhat reduced adhesive strength.

[0092] The above silane coupling agent may be necessary, for example, to improve adhesion with the lower substrate. The above silane coupling agent is, for example, (3-glycidoxypropyl)trimethoxysilane, (3-glycidoxypropyl)triethoxysilane, (3-glycidoxypropyl)methyldimethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane, (3-glycidoxypropyl)dimethylethoxysilane, 3,4-epoxybutyltrimethoxysilane, 3,4-epoxybutyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3 dimethyl-butylidene)propylamine, N-2(aminoethyl)3-aminopropyltrimethoxysilane, It may be one or a mixture of two or more selected from the group consisting of N-2(aminoethyl)3-aminopropyltriethoxysilane, N-2(aminoethyl)3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and (3-isocyanatepropyl)triethoxysilane.

[0093] The type of the above adhesion promoter is not particularly limited, and specific examples of adhesion promoters that can be used include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatepropyltrimethoxysilane, and Examples include 3-isocyanatepropyltriethoxysilane.

[0094] The type of the above-mentioned anti-coagulant is not particularly limited, but specific examples that can be used include sodium polyacrylate, etc.

[0095]

[0096] The additives exemplified above may be used singly or in combination of two or more. The additive may be included in an amount of typically 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, per 100 parts by weight of the acrylic copolymer.

[0097]

[0098] The above solvent may be any common solvent without particular limitation, taking into account physical properties, as long as it is effective in dissolving other components included in the above-described adhesive composition, and in particular, ethers, aromatic hydrocarbons, ketones, alcohols, esters, or amides are preferable.

[0099] The solvents above are specifically ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether; diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, and diethylene glycol dibutyl ether; ethylene glycol alkyl ether acetates such as methyl cellosolve acetate and ethyl cellosolve acetate; alkylene glycol alkyl ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, methoxybutyl acetate, and methoxypentyl acetate; aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; Examples thereof include ketones such as methyl ethyl ketone, acetone, methyl amyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol, and glycerin; esters such as ethyl 3-ethoxypropionate and methyl 3-methoxypropionate; and cyclic esters such as γ-butyrolactone.

[0100] The above solvent is preferably an organic solvent having a boiling point of 100°C to 200°C in terms of applicability and drying properties, and more preferably, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, cyclohexanone, ethyl lactate, butalactate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, etc. can be used.

[0101] The above solvents can be used alone or in combination of two or more.

[0102] The above solvent may be included as a residual amount. Specifically, in the present invention, "residual amount" refers to the weight of the remaining portion of the composition further including the essential components of the present invention and other additional components, and the meaning of "residual amount" is not limited to the composition of the present invention not including additional components.

[0103]

[0104] <Adhesive sheet and display including same>

[0105] The present invention provides an adhesive sheet manufactured using the above-described adhesive composition, wherein the adhesive sheet is characterized in that its elastic modulus at -20°C is 5.0E+05Pa to 1.0E+07Pa. In addition, the adhesive sheet can have excellent folding performance even after performing 25 folds / min and holding for 0.2 seconds after one fold for more than 50,000 times, and also has excellent impact resistance.

[0106]

[0107] In order to provide the adhesive sheet of the present invention, in addition to including the above-described adhesive composition, a composition and a manufacturing method commonly used for manufacturing adhesive layers, adhesive films, and adhesive sheets in the same field can be used.

[0108]

[0109] In addition, the present invention provides a display including the adhesive sheet described above, and the display of the present invention may include a configuration commonly known in the art, as long as it includes the adhesive composition and / or adhesive sheet of the present invention.

[0110]

[0111]

[0112] Hereinafter, experimental examples including specific examples and comparative examples are presented to help understand the present invention, but these are only illustrative of the present invention and do not limit the scope of the appended claims. It will be apparent to those skilled in the art that various changes and modifications to the examples are possible within the scope and technical idea of ​​the present invention, and it is natural that such changes and modifications fall within the scope of the appended claims. “%” and “parts” in the examples mean “mass%” and “mass parts”, respectively, unless otherwise specified.

[0113]

[0114] < Manufacturing Example >

[0115]

[0116] Manufacturing Example 1: Acrylic copolymer A-1

[0117] In a 1 L reactor equipped with a cooling device for refluxing nitrogen gas and easy temperature control, 65.5 parts by weight of n-butylacrylate (BA), 33 parts by weight of methyl acrylate (MA), 0.5 parts by weight of acrylic acid (AA), and 1.0 parts by weight of 2-hydroxyethyl methacrylate (2-HEA) were charged, and then 100 parts by weight of ethyl acetate (EA) as a solvent was added. After that, nitrogen gas was introduced for 1 hour to remove oxygen and the mixture was replaced, and the temperature was maintained at 62°C. After stirring the mixture uniformly, 0.07 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was added and reacted for 8 hours to produce an acrylic copolymer A-1 having a weight average molecular weight (Mw) of 1.1 million or more.

[0118]

[0119] Manufacturing Example 2: Acrylic copolymer A-2

[0120] An acrylic copolymer A-2 having a weight average molecular weight (Mw) of 1.2 million or more was prepared in the same manner as in Manufacturing Example 1, but using 75.7 parts by weight of n-butylacrylate (BA), 22 parts by weight of methylacrylate (MA), 0.3 parts by weight of acrylic acid (AA), and 2.0 parts by weight of 2-hydroxyethyl methacrylate (2-HEMA).

[0121]

[0122] Manufacturing Example 3: Acrylic copolymer A-3

[0123] An acrylic copolymer A-3 having a weight average molecular weight (Mw) of 1.15 million or more was prepared in the same manner as in Manufacturing Example 1, but using 38.5 parts by weight of n-butylacrylate (BA), 20 parts by weight of 2-ethylhexyl acrylate (EHA), 40 parts by weight of methyl acrylate (MA), 0.5 parts by weight of acrylic acid (AA), and 1 part by weight of 2-hydroxyethyl methacrylate (2-HEMA).

[0124]

[0125] Manufacturing Example 4: Acrylic copolymer A-4

[0126] An acrylic copolymer A-4 having a weight average molecular weight (Mw) of 1.2 million or more was manufactured in the same manner as in Manufacturing Example 1, but using 89.99 parts by weight of n-butylacrylate (BA), 10 parts by weight of methylacrylate (MA), and 0.01 parts by weight of acrylic acid (AA).

[0127]

[0128] < Examples and Comparative Examples: Adhesive Composition and Preparation of Adhesive Sheet Containing the Same >

[0129] An adhesive composition was prepared by mixing the components and contents as shown in Table 1 below, and diluting the composition with an organic solvent (ethyl acetate) to a solid content of 20 wt% in consideration of the coating property. The prepared adhesive composition was applied to a film coated with a silicone release agent to a thickness of 10 μm after drying, and then dried at 100°C for 2 minutes, and then laminated with a release film to form an adhesive sheet corresponding to each example and comparative example.

[0130] Classification (weight part) Acrylic copolymer Crosslinking agent Silane coupling agent Plasticizer Type Content Type Content Type Content Type Content Example 1A-1100B-10.5C-10.5D-13 Example 2A-1100B-10.5C-10.5D-23 Example 3A-1100B-10.5C-10.5D-33 Example 4A-1100B-10.5C-10.5D-45 Example 5A-2100B-20.5C-10.5D-13 Example 6A-310 0B-20.5C-10.5D-12Example 7A-1100B-10.5C-10.5D-11Example 8A-1100B-10.5C-10.5D-15Comparative Example 1A-1100B-10.5C-10.5--Comparative Example 2A-4100B-10.5C-10.5D-13Comparative Example 3A-4100B-10.5C-10.5D-45Comparative Example 4A-1100B-10.5C-10.5D-111

[0131] - A-1: ​​Acrylic copolymer manufactured according to Manufacturing Example 1

[0132] - A-2: Acrylic copolymer manufactured according to Manufacturing Example 2

[0133] - A-3: Acrylic copolymer manufactured according to Manufacturing Example 3

[0134] - A-4: Acrylic copolymer manufactured according to Manufacturing Example 4

[0135] - B-1: D-110N (Mitsui Chemical)

[0136] - B-2: D-103 (Mitsui Chemical)

[0137] - C-1: KBM-403 (3-glycidoxypropyl trimethoxysilane, Shin-Etsu)

[0138] - D-1: Diisooctyl adipate (DOA)

[0139] - D-2: Dioctyl maleate (DOM)

[0140] - D-3: 1,2-cyclohexane dicarboxylic acid diisononyl ester (DEHCH)

[0141] - D-4: Castor oil

[0142]

[0143] <Experimental Example>

[0144] 1. Elastic modulus measurement

[0145] For each adhesive sheet before the optical member layer manufactured in the above examples and comparative examples was laminated, the storage modulus was measured using a viscoelasticity measuring device (MCR-301, Anton Paar). More specifically, the adhesive sheet was cut to a size of 30 mm in length X 30 mm in width, the release film attached to one side of the cut adhesive sheet was removed, and it was bonded to a glass substrate. Thereafter, while in contact with the measurement tip, the measurement was performed under the conditions of a frequency of 1.0 Hz, a strain of 1%, and a heating rate of 5°C / min in a temperature range of -30°C to 100°C, and the measurement value at -20°C was read at this time, and the measurement results are shown in Table 2 below.

[0146]

[0147] 2. Impact test (pen drop)

[0148] The adhesive film was cut into 100 mm x 100 mm pieces, the release film of the adhesive sheet was removed, and the adhesive sheet was bonded to a 1.1T glass substrate. Then, the release film on the opposite side was removed and a 50 μm glass was bonded to produce a specimen. With the 50 μm glass as the topmost layer, a commercial ballpoint pen (BIC Crystal Fine 0.7 mm) was dropped from a certain height, and the highest height at which no cracks occurred on the 50 μm glass substrate was measured, and the results are shown in Table 2 below.

[0149]

[0150] 3. Folding performance evaluation

[0151] The adhesive films produced in the examples and comparative examples were bonded to 50㎛ PET, cut into 20mmx100mm, and used as specimens. The specimens were fixed to a bending evaluation device (COVOTECH, CFT-720C) for folding evaluation, folded with a radius of curvature of 2mm, and the folding evaluation was performed under the conditions of 25 foldings per minute and holding for 0.2 seconds after each folding at -20℃. When applying the folding evaluation, 1 folding is referred to as 1 cycle, and the number of foldings at which stripes, etc. are generated at the folding site after folding, or the adhesive film is broken, lifted, or peeled by 0.3mm or more is observed, is evaluated according to the evaluation criteria below, and is recorded in Table 2 below.

[0152] <Evaluation Criteria>

[0153] ◎: No defects after folding more than 50,000 times

[0154] ○: Defects occur between 20,000 and 50,000 folding cycles.

[0155] ×: Defects occur when the number of folding cycles is less than 20,000.

[0156] Classification -20℃Elasticity modulus [Pa]Impact test [mm] -20℃Folding propertyExample 17.73E+0640◎Example 26.27E+0637◎Example 37.13E+0638◎Example 48.56E+0545○Example 58.56E+0545◎Example 65.98E+0535◎Example 78.58E+0643◎Example 85.98E+0536◎Comparative example 15.92E+0745xComparative example 23.32E+0522○Comparative example 34.04E+059○Comparative example 41.13E+0511○

[0157] According to the experimental data in Table 2 above, in the case of the adhesive sheet including the adhesive composition for an optical member according to the present invention of Examples 1 to 8, the elastic modulus at -20°C was 5.0E+05 Pa to 1.0E+07 Pa, and the results of the impact test for pen drop and the folding resistance evaluation at -20°C were also excellent. On the other hand, in the case of Comparative Example 1, which does not include a plasticizer in the adhesive composition, the elastic modulus at -20°C exceeded 1.0E+07 Pa, and defects such as breakage, lifting, and peeling easily occurred during the folding evaluation. On the other hand, in the case of Comparative Examples 2 and 3, which include an acrylic copolymer in which the content of the monomer included in the polymerization of the acrylic copolymer was changed beyond the scope of the present invention, the elastic modulus at -20°C was less than 5.0E+05 Pa, and the impact resistance also showed a poor result.

[0158] In addition, in the case of Comparative Example 4, in which the content of the plasticizer exceeds 10 parts by weight based on 100 parts by weight of the acrylic copolymer, the elastic modulus at -20°C was less than 5.0E+05Pa, indicating a result of vulnerability to impact.

[0159]

[0160]

[0161]

[0162]

[0163] The adhesive composition according to the present invention and the adhesive sheet comprising the same can have improved properties in terms of elasticity, impact resistance, and folding performance by satisfying the range of elasticity modulus at -20°C of 5.0E+05Pa to 1.0E+07Pa, and in particular, exhibit excellent durability and folding performance even at low temperatures of -20°C.

Claims

1. An adhesive composition for an optical member, comprising an acrylic copolymer and a plasticizer, The above acrylic copolymer is, a) (meth)acrylate monomer having 1 to 3 carbon atoms; b) a (meth)acrylate monomer having 4 to 12 carbon atoms; and c) a copolymer including a monomer containing at least one functional group selected from among a hydroxyl group (OH) and a carboxyl group (COOH); An adhesive composition for an optical member, characterized in that the elastic modulus of an adhesive sheet containing the adhesive composition at -20°C is 5.0E+05Pa to 1.0E+07Pa.

2. In claim 1, The above b) alkyl (meth)acrylate monomer having 4 to 12 carbon atoms is an adhesive composition for an optical member having a straight or branched alkyl chain.

3. In claim 1, The above acrylic copolymer is, for a total of 100 parts by weight of monomers included in the polymerization, a) 20 to 45 parts by weight of an alkyl (meth)acrylate monomer having 1 to 3 carbon atoms; b) 30 to 79.95 parts by weight of an alkyl (meth)acrylate monomer having 4 to 12 carbon atoms; and c) An adhesive composition for an optical member, which is polymerized by including 0.05 to 3 parts by weight of a hydroxyl group or carboxylic acid-containing monomer.

4. In claim 1, An adhesive composition for an optical member, wherein the weight average molecular weight (Mw) of the acrylic copolymer is 50,000 to 2,000,000.

5. In claim 1, An adhesive composition for an optical member, wherein the plasticizer comprises at least one selected from a nonpolar plasticizer selected from the group consisting of an adipate compound, a maleate compound, and a non-phthalate compound, and a polar plasticizer containing at least one functional group selected from a hydroxyl group, a carboxyl group, and an amide group.

6. In claim 5, An adhesive composition for an optical member, wherein the plasticizer comprises at least one non-polar plasticizer selected from dioctyl adipate, diisononyl adipate, diisooctyl adipate, dioctyl maleate, bis(2-ethylhexyl) maleate, dibutyl maleate, diethylhexylcyclohexane, and 1,2-cyclohexane dicarboxylic acid diisononyl ester.

7. In claim 1, An adhesive composition for an optical member, comprising 0.5 to 10 parts by weight of a plasticizer per 100 parts by weight of a total acrylic copolymer.

8. In claim 1, An adhesive composition for an optical member, wherein the adhesive composition further comprises at least one selected from the group consisting of a crosslinking agent, a silane coupling agent, an adhesive-providing resin, an antioxidant, an anti-corrosion agent, a leveling agent, a surface lubricant, a dye, a pigment, an anti-foaming agent, a filler, a light stabilizer, an antistatic agent, and a solvent.

9. An adhesive sheet comprising an adhesive composition for an optical member according to any one of claims 1 to 8.

10. In claim 9, The above adhesive sheet is an adhesive sheet that has excellent folding performance even after folding 25 times / min and maintaining 0.2 seconds after folding once for more than 50,000 times.

11. A display comprising the adhesive sheet of claim 9.

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