Adhesive compositions, adhesive sheets, and optical films

Abstract

Provided is an adhesive composition capable of forming an adhesive layer having improved adhesive properties and reworkability. The adhesive composition includes an acrylic copolymer, a non-yellowing type isocyanate-based or aziridine-based crosslinking agent, and an organosilicon compound having at least two carbonyl groups. The adhesive layer formed from the adhesive composition has high adhesion to a substrate film, and can provide an optical film with improved reworkability even after being left for a long time under harsh conditions such as high temperature and high humidity.

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition, an adhesive sheet, and an optical film, and more particularly to an adhesive composition comprising an acrylic copolymer, an adhesive sheet manufactured therefrom, and an optical film manufactured from the adhesive sheet. [Background technology]

[0002] For example, adhesives or adhesive sheets can be used to bond display panels of image display devices, such as liquid crystal displays (LCDs) and organic light-emitting displays (OLEDs), to various optical structures or circuit structures. The adhesive must have improved transparency and high adhesive strength so as not to degrade the optical properties of the image display device.

[0003] In recent years, there has been active research into displays that offer high reliability even under harsh conditions of high temperature and humidity, or under external physical shocks. Consequently, structures bonded to these displays must also be designed to prevent detachment or peeling even under harsh conditions and external shocks. Therefore, there is a need for adhesives or adhesive sheets that possess high wettability and durability and can bond these display structures.

[0004] For example, Korean Published Patent No. 2010-0039274 discloses an adhesive for polarizing plates applied to image display devices. However, conventional known adhesives have limitations in adequately ensuring the aforementioned properties required for flexible displays. [Overview of the project] [Problems that the invention aims to solve]

[0005] One objective of the present invention is to provide an adhesive composition that can form an adhesive layer having improved adhesive properties and reworkability.

[0006] One object of the present invention is to provide an adhesive sheet including an adhesive layer formed using the adhesive composition, and an optical film produced from the adhesive sheet.

Means for Solving the Problems

[0007] 1. An adhesive composition comprising an acrylic copolymer, a non-yellowing type isocyanate-based or aziridine-based crosslinking agent, and an organosilicon compound having at least two carbonyl groups.

[0008] 2. The adhesive composition according to item 1, wherein the acrylic copolymer is formed from a polymerizable mixture containing a (meth)acrylate monomer and a (meth)acrylic acid monomer.

[0009] 3. The adhesive composition according to item 2, wherein the polymerizable mixture further contains a crosslinkable monomer containing a polar functional group.

[0010] 4. The adhesive composition according to item 3, wherein the polar functional group of the crosslinkable monomer containing a polar functional group includes at least one of a hydroxy group, an amide group, or an amine group.

[0011] 5. The adhesive composition according to item 3, wherein the content of the crosslinkable monomer containing a polar functional group is 0.1% by weight to 5% by weight based on the total weight of the polymerizable mixture.

[0012] 6. The adhesive composition according to item 2, wherein the (meth)acrylate monomer includes a first monomer which is an alkyl (meth)acrylate monomer having 1 to 3 carbon atoms and a second monomer which is an alkyl (meth)acrylate monomer having 4 to 12 carbon atoms.

[0013] 7. The adhesive composition according to item 6, wherein the content of the first monomer is 10% by weight to 40% by weight based on the total weight of the polymerizable mixture.

[0014] 8. In item 2 above, the content of the (meth)acrylic acid monomer is 0.01% to 1% by weight relative to the total weight of the polymerizable mixture, an adhesive composition.

[0015] 9. In item 1 above, the organosilicon compound is an adhesive composition comprising a nitrogen atom or a sulfur atom.

[0016] 10. In item 9 above, the organosilicon compound is an adhesive composition comprising an amine group or a sulfide group.

[0017] 11. In item 1 above, the organosilicon compound is an adhesive composition having two carbonyl groups linked by a methylene group.

[0018] 12. In item 11 above, the organosilicon compound is an adhesive composition having a malonyl group or an acetoacetyl group.

[0019] 13. In item 1 above, the organosilicon compound comprises a compound represented by the following chemical formula 1 or the following chemical formula 2, in an adhesive composition.

[0020] [ka] [ka] (R1 is an alkoxy group having 1 to 12 carbon atoms, R6 is an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms, and R2 and R7 are each independently divalent aliphatic hydrocarbons having 1 to 30 carbon atoms.) R3-R5 and R8-R 10 Each of these is independently a hydrogen atom, a C1-C12 alkyl group, a C2-C12 alkenyl group, a C2-C12 alkynyl group, or a C1-C12 alkoxy group.

[0021] 14. The adhesive composition according to item 1 above, comprising 0.1 to 3 parts by weight of the non-yellowing type isocyanate or aziridine crosslinking agent and 0.01 to 3 parts by weight of the organosilicon compound, per 100 parts by weight of the acrylic copolymer.

[0022] 15. In item 1 above, the adhesive composition further comprises an ionic antistatic agent.

[0023] 16. An adhesive sheet comprising a base film and an adhesive layer disposed on the base film and formed using the adhesive composition described in item 1.

[0024] 17. In item 16 above, the adhesive sheet wherein the rate of change of adhesive strength according to the following formula 2 is 0.8 to 2.2. [Formula 2] Adhesion change rate = P H / P C (In formula 2, P C This is the adhesive strength measured by attaching the adhesive sheet to the target object, leaving it for 24 hours under conditions of 23°C and 50%RH, and then peeling the adhesive sheet from the target object at a peeling speed of 300 mm / min and a peeling angle of 180°. P H This refers to the adhesive strength measured after attaching the adhesive sheet to the target object, leaving it for 48 hours under conditions of 50°C and 50%RH, and then peeling the adhesive sheet from the target object at a peeling speed of 300 mm / min and a peeling angle of 180° under conditions of 23°C and 50%RH.

[0025] 18. An optical film comprising a base film, an adhesive layer disposed on the upper surface of the base film and formed using the adhesive composition described in item 1, and an anti-reflective layer disposed on the lower surface of the base film.

[0026] 19. An image display device including the optical film described in item 18 above. [Effects of the Invention]

[0027] An example embodiment of the adhesive composition may include an acrylic copolymer, an organosilicon compound having at least two carbonyl groups, and a non-yellowing isocyanate or aziridine crosslinking agent. This can improve the chemical stability and reworkability of the adhesive composition. [Brief explanation of the drawing]

[0028] [Figure 1] This is a schematic cross-sectional view illustrating an adhesive sheet according to an exemplary embodiment. [Figure 2] This is a schematic cross-sectional view illustrating an adhesive sheet according to an exemplary embodiment. [Figure 3] This is a schematic cross-sectional view illustrating an optical film according to an exemplary embodiment. [Figure 4] This is a schematic cross-sectional view illustrating an image display device according to an exemplary embodiment. [Modes for carrying out the invention]

[0029] Embodiments of the present invention provide an adhesive composition comprising an acrylic copolymer, a non-yellowing isocyanate-based or aziridine-based crosslinking agent, and an organosilicon compound having at least two carbonyl groups. Also provided are an adhesive sheet and an optical film comprising an adhesive layer formed from the adhesive composition.

[0030] The present invention will be described in detail below.

[0031] <Adhesive composition> The adhesive composition according to the exemplary embodiment may include an acrylic copolymer. The acrylic copolymer may include a copolymer formed from a polymerizable mixture containing (meth)acrylate monomers and (meth)acrylic acid. As used in this application, the term "(meth)acrylate" is used to mean both acrylate and methacrylate. As used in this application, the term "(meth)acrylic acid" is used to mean both acrylic acid and methacrylic acid.

[0032] The (meth)acrylate monomer may include a first monomer of an alkyl (meth)acrylate having 1 to 3 carbon atoms and a second monomer of an alkyl (meth)acrylate having 4 to 12 carbon atoms.

[0033] The first monomer and the second monomer may be compounds derived from aliphatic alcohols having 1 to 12 carbon atoms.

[0034] Examples of the first monomer include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate, and preferably methyl (meth)acrylate. These can be used alone or in combination of two or more.

[0035] In some embodiments, the content of the first monomer may be 10% to 40% by weight, preferably 15% to 35% by weight, relative to the total weight of the polymerizable mixture. If the content of the first monomer is less than 10% by weight, sufficient adhesion may not be achieved. If the content of the first monomer exceeds 40% by weight, the adhesion may increase too much, reducing reworkability.

[0036] Examples of the second monomer include n-butyl (meth)acrylate, 2-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, and lauryl (meth)acrylate. The second monomer may preferably be n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate. These can be used individually or in combination of two or more.

[0037] In some embodiments, the content of the second monomer may be 60% to 89% by weight of the total weight of the polymerizable mixture, preferably 65% ​​to 80% by weight. If the content of the first monomer is less than 60% by weight, sufficient adhesive strength may not be achieved. Within this range, it is possible to prevent a decrease in the cohesive force of the adhesive composition and a decrease in the durability of the adhesive layer, and to improve the crosslinking density and adhesion strength of the adhesive layer.

[0038] According to exemplary embodiments, the polymerizable mixture contains both the first monomer and the second monomer, which can achieve improved tackiness while preventing damage to the substrate and residue of adhesive material during rework.

[0039] The (meth)acrylic acid monomer can play a role in imparting tackiness to the adhesive composition. For example, if the acrylic copolymer has acidic groups derived from the (meth)acrylic acid monomer, the adhesion and degree of crosslinking of the adhesive composition can be improved.

[0040] However, as the (meth)acrylic acid monomer content increases, the hydrophilicity of the adhesive composition may increase, which may degrade the surface migration properties of the ionic antistatic agent described later. In addition, the crosslinking agent described later may be consumed by reacting with the acidic groups derived from (meth)acrylic acid, which may reduce the cohesive force and adhesion of the adhesive layer.

[0041] In some embodiments, the content of (meth)acrylic acid may be 1% by weight or less relative to the total weight of the polymerizable mixture. For example, the content of (meth)acrylic acid monomer may be 0.01% to 1% by weight relative to the total weight of the polymerizable mixture, preferably 0.05% to 1% by weight, and more preferably 0.05% to 0.5% by weight. If the content of (meth)acrylic acid monomer is less than 0.01% by weight, the adhesive strength of the adhesive composition may decrease. If the content of (meth)acrylic acid monomer exceeds 1% by weight, the adhesive strength may increase too much, reducing reworkability, affecting the surface migration of the ionic antistatic agent, and potentially reducing durability.

[0042] According to exemplary embodiments, the polymerizable mixture may further comprise a crosslinkable monomer containing a polar functional group. For example, the acrylic copolymer may include a copolymer formed from a polymerizable mixture comprising a (meth)acrylate monomer, (meth)acrylic acid, and a crosslinkable monomer having a polar functional group.

[0043] The aforementioned polar functional group-containing crosslinkable monomer can improve the degree of crosslinking of acrylic copolymers. Furthermore, it can react with non-yellowing isocyanate-based or aziridine-based crosslinking agents, as described later, to prevent the breakdown of cohesive force in the adhesive layer under high temperature and high humidity conditions, thereby imparting adhesive strength.

[0044] The crosslinkable monomer may contain polar functional groups such as hydroxyl groups, amide groups, and amine groups. In some embodiments, the crosslinkable monomer may contain a hydroxyl group-containing monomer, an amide group-containing monomer, and / or an amine group-containing monomer. These can be used individually or in combination of two or more.

[0045] Examples of the hydroxyl group-containing monomers 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 with 2 to 4 carbon atoms in the alkylene group, 4-hydroxybutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 7-hydroxyheptyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9-hydroxynonyl vinyl ether, and 10-hydroxydecyl vinyl ether. These can be used individually or in combination of two or more.

[0046] Examples of the amide group-containing monomers include (meth)acrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, 3-hydroxypropyl(meth)acrylamide, 4-hydroxybutyl(meth)acrylamide, 6-hydroxyhexyl(meth)acrylamide, 8-hydroxyoctyl(meth)acrylamide, and 2-hydroxyethylhexyl(meth)acrylamide. These can be used individually or in combination of two or more.

[0047] The amine group-containing monomer may include a tertiary amine group-containing monomer. Examples of the tertiary amine group-containing monomer include N,N-(dimethylamino)ethyl (meth)acrylate, N,N-(diethylamino)ethyl (meth)acrylate, and N,N-(dimethylamino)propyl (meth)acrylate. These can be used individually or in combination of two or more.

[0048] Preferably, the crosslinkable monomer may include 4-hydroxybutyl vinyl ether and / or (meth)acrylamide.

[0049] In some embodiments, the content of the crosslinkable monomer having the polar functional group may be 0.05% to 5% by weight, preferably 0.1% to 3% by weight, relative to the total weight of the polymerizable mixture. If the content of the crosslinkable monomer is less than 0.05% by weight, the cohesive force of the adhesive composition may decrease, resulting in reduced durability. If the content of the crosslinkable monomer exceeds 5% by weight, the gel fraction of the adhesive composition may become too high, resulting in reduced tackiness and durability.

[0050] In some embodiments, in addition to the monomer, other polymerizable monomers known in the art may be further included in amounts that do not reduce the adhesiveness, for example, 10% by weight or less of the total weight of the polymerizable mixture.

[0051] The method for producing the acrylic copolymer is not particularly limited and can be used by methods commonly used in this field, such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization, and is preferably produced using solution polymerization. In addition, solvents commonly used during polymerization, polymerization initiators, and chain transfer agents for controlling molecular weight can be used.

[0052] In some embodiments, the weight-average molecular weight (polystyrene equivalent, Mw) of the acrylic copolymer may be 50,000 to 2,000,000, preferably 400,000 to 2,000,000. For example, the weight-average molecular weight can be measured by gel permeation chromatography (GPC). If the weight-average molecular weight of the acrylic copolymer is less than 50,000, the cohesive force between copolymers may be insufficient, resulting in reduced adhesive durability. If it exceeds 2,000,000, a large amount of diluent solvent may be required to ensure processability during coating.

[0053] The aforementioned non-yellowing isocyanate-based or aziridine-based crosslinking agents can improve the cohesive force, adhesion, and high-temperature reliability of the adhesive, and can also play a role in maintaining the shape of the adhesive.

[0054] A yellowing-type isocyanate crosslinking agent can refer to a compound in which the nitrogen atom of the isocyanate is directly bonded to the carbon atom of the phenyl group. A non-yellowing-type isocyanate crosslinking agent can refer to the remaining isocyanate crosslinking agents after excluding the yellowing-type isocyanate crosslinking agent.

[0055] Non-yellowing isocyanate and aziridine compounds exhibit high reactivity to polar functional groups and can provide improved adhesion to substrate films treated with corona discharge or plasma.

[0056] Examples of the isocyanate compounds include diisocyanate compounds such as xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and tetramethylxylene diisocyanate; adducts obtained by reacting 3 equivalents of a diisocyanate compound with 1 equivalent of a polyhydric alcohol compound such as trimethylolpropane; isocyanurates obtained by self-condensation of 3 equivalents of a diisocyanate compound; biuretes obtained by condensing the remaining 1 equivalent of diisocyanate onto a diisocyanate urea obtained from 2 equivalents of 3 equivalents of a diisocyanate compound; and polyfunctional isocyanate compounds containing three functional groups, such as triphenylmethane triisocyanate and methylenebis triisocyanate. These can be used individually or in combination of two or more.

[0057] Examples of the aforementioned aziridine compounds include pentaerythritol-tris-(β-(N-aziridinyl)propionate, trimethylolpropane-tris(β-N-aziridinyl)propionate, trimethylolpropane-tris(2-methyl-1-aziridinepropionate), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), triethylenemelamine, bisisoprotaloyl-1-(2-methylaziridine), or tri-1-aziridinylphosphine oxide. These can be used individually or in combination of two or more.

[0058] In some embodiments, the content of the crosslinking agent may be 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 may be low due to insufficient crosslinking, which may reduce adhesive durability and cleavage. If the content of the crosslinking agent exceeds 3 parts by weight, the crosslinking reaction may occur too much, resulting in high residual stress and reduced adhesion to the object to which the crosslinking agent is applied.

[0059] An adhesive composition according to an exemplary embodiment may contain an organosilicon compound having at least two carbonyl groups. In one embodiment, the organosilicon compound may contain two carbonyl groups linked by a methylene group. Therefore, the organosilicon compound can increase the adhesive strength of the adhesive composition and suppress the generation of bubbles, lifting, and rupture of the adhesive layer.

[0060] In some embodiments, the organosilicon compound may contain a malonyl group or an acetoacetyl group. In this case, the malonyl group or acetoacetyl group can further improve the tackiness of the adhesive composition and enhance its heat resistance and heat- and moisture resistance.

[0061] In some embodiments, the organosilicon compound may contain a nitrogen atom or a sulfur atom. For example, the organosilicon compound may contain an amine group or a sulfide group. The presence of an amine group or sulfide group in addition to a malonyl group or acetoacetyl group in the organosilicon compound can improve reworkability even after being left for a long time under heat-resistant and humid heat-resistant conditions, thereby improving adhesive durability and adhesive reliability.

[0062] In some embodiments, the organosilicon compound may include a compound represented by the following chemical formula 1 or chemical formula 2.

[0063] [ka] [ka]

[0064] R1 may be an alkoxy group having 1 to 12 carbon atoms. Examples of R1 include a methoxy group, an ethoxy group, an isopropyloxy group, etc., and from the viewpoint of reworkability, a methoxy group is preferred.

[0065] R6 may be an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms. Examples of R6 include a methyl group, an ethyl group, an isopropyl group, a methoxy group, an ethoxy group, an isopropyloxy group, etc., and from the viewpoint of reworkability, a methyl group or a methoxy group is preferred.

[0066] R2 and R7 may each be independently divalent aliphatic hydrocarbon groups having 1 to 30 carbon atoms. For example, R2 and R7 may be alkylene groups having 1 to 30 carbon atoms, alkenylene groups having 2 to 30 carbon atoms, and alkylene groups having 2 to 30 carbon atoms.

[0067] R3-R5 and R8-R 10may each independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. At least one of said R3 to R5 and at least one of R8 to R 10 is preferably an alkoxy group having 1 to 12 carbon atoms, and the number of carbon atoms can be adjusted in consideration of the relationship between adhesive strength and reworkability.

[0068] In some embodiments, the content of the organosilicon compound may be 0.01 to 3 parts by weight, preferably 0.1 to 2 parts by weight, more preferably 0.1 to 1 part by weight, based on 100 parts by weight of the acrylic copolymer. Within this range, the durability and adhesion of the adhesive layer formed from the adhesive composition can be improved.

[0069] In some embodiments, the adhesive composition may further contain an ionic antistatic agent. The ionic antistatic agent can contain an ionic salt composed of an anion and a cation, and can impart ionic conductivity to the adhesive layer formed from the adhesive composition. For example, the surface resistivity value of the adhesive layer may be 10×10 10 Ω / □ or less, preferably 7×10 10 Ω / □ or less.

[0070] In some embodiments, the ionic antistatic agent can contain an alkali metal salt, an ionic liquid or an ionic solid, and preferably can contain an ionic solid.

[0071] By including an ionic solid as the ionic antistatic agent, the stability over time of the adhesive composition and the durability of the adhesive layer can be improved. Also, the ionic solid has high compatibility with the other components described above and can maintain high transparency of the adhesive composition.

[0072] In some embodiments, the melting point of the ionic solid may be 20°C or higher, specifically 20°C to 50°C. In this case, the mobility of the ionic solid is minimized, improving the durability and reliability of the adhesive sheet or optical film. For example, if the melting point of the ionic solid is below 20°C, the mobility of the ionic solid increases, and the ionic solid may migrate to the edges of the adhesive sheet or optical film and dissolve.

[0073] In some embodiments, the ionic solid is an anion of Cl - , Br - , I - AlCl4 - Al2Cl7 - BF4 - PF6 - ClO4 - NO3 - CO3 2- CH3COO - CF3COO - CH3SO3 - CF3SO3 - , (FSO2)2N - (CF3SO2)2N - , (CF3SO2)3C - AsF6 - SbF6 - , NbF6 - TaF6 - , F(HF) n - , (CN)2N - , C4F9SO3 - (C2F5SO2)2N - C3F7COO - , C6H5COO - (CF3SO2)(CF3CO)N - ,OTf - (Trifluoromethanesulfonate), OTs - (Toluene sulfonate), OMs - (Methanesulfonate), and / or BPh4 - It may contain (tetraphenylborate), etc.

[0074] In some embodiments, the ionic solid may include, as a cation, imidazolium, pyridinium, alkylammonium, alkylpyrrolidium, and / or alkylphosphonium.

[0075] In some embodiments, the content of the ionic antistatic agent may be 0.01 to 5 parts by weight per 100 parts by weight of the acrylic copolymer. Within this range, the antistatic properties of the adhesive layer can be improved, and the durability of the adhesive layer can be maintained at an excellent level.

[0076] The adhesive composition may further contain conventional additives known in the art to adjust the required adhesive strength, cohesive force, viscosity, modulus of elasticity, glass transition temperature, etc., depending on the application. For example, the adhesive composition may include additives such as tackifiers, antioxidants, corrosion inhibitors, leveling agents, surface lubricants, dyes, pigments, defoamers, fillers, light stabilizers, and plasticizers.

[0077] <Adhesive sheet> Embodiments of the present invention will be described more specifically below with reference to the drawings. However, the drawings accompanying this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to help further understand the technical concept of the present invention. Therefore, the present invention is not to be construed as being limited only to what is shown in the drawings.

[0078] Figure 1 is a schematic cross-sectional view showing an adhesive sheet according to an exemplary embodiment.

[0079] Referring to Figure 1, an adhesive sheet according to an exemplary embodiment may include a base film 110, an adhesive layer 120 disposed on the upper surface of the base film 110, and a release film 130 disposed on the upper surface of the adhesive layer 120.

[0080] The adhesive layer can be formed from the adhesive composition described above. For example, the adhesive layer 120 can be formed by applying an adhesive composition containing an acrylic copolymer, a non-yellowing type isocyanate or aziridine crosslinking agent, and an organosilicon compound having at least two carbonyl groups onto a base film 110 and curing it.

[0081] In some embodiments, the base film 110 may include acrylic resins, cellulose resins, polyolefin resins, or polyester resins. In this case, the transparency, mechanical strength, thermal stability, moisture shielding properties, isotropy, etc., of the base film 110 can be improved.

[0082] For example, the base film 110 may contain acrylic resins such as polymethyl (meth)acrylate and polyethyl (meth)acrylate; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene naphthalate; cellulosin resins such as diacetylcellulose, triacetylcellulose, and cellulose acetate butylene; polyolefin resins such as polyethylene, polypropylene, cycloolefin, polyolefin having a norbornene structure, and ethylene-propylene copolymer; sulfone resins; polyether ether ketone resins; arylate resins; or mixtures of the above resins.

[0083] In one embodiment, at least one surface of the base film 110, for example, the surface on which the adhesive layer 120 is formed, can be surface-treated. For example, corona discharge treatment, plasma treatment, blast treatment, primer treatment, etc., can be performed on one surface of the base film 110.

[0084] The surface treatment described above can generate a carboxylic acid derivative (R-COOH) on the surface of the base film 110. The carboxyl group of the carboxylic acid derivative can react with the adhesive composition, thereby further improving the adhesion of the adhesive layer to the base film.

[0085] In one embodiment, the base film 110 does not need to be saponified. Because the surface of a base film used in an adhesive sheet is hydrophobic, its adhesion to the adhesive and adhesive strength may deteriorate. In this case, the adhesion between the base film and the adhesive can be improved by performing a pretreatment step of saponifying the surface of the base film by immersing it in an alkaline aqueous solution, forming another coating layer between the base film and the adhesive, or treating the surface of the base film with corona or plasma.

[0086] However, when a saponification process is performed or another coating layer is formed, the process becomes more complex, which can reduce the yield and processability of the adhesive sheet, and additional pretreatment or coating layer formation steps may cause contamination and deterioration of the quality of the adhesive sheet.

[0087] The adhesive composition according to the above embodiment can improve the adhesion of the adhesive layer 120 to the surface of the base film 110 by increasing the affinity between the surface of the base film 110 and the adhesive composition through the organosilicon compound having a malonyl group or an acetoacetyl group. Furthermore, it can maintain heat resistance, heat and humidity resistance, durability, and adhesive reliability under harsh conditions of high temperature and high humidity, and can achieve improved reworkability even after being left for a long time under the aforementioned harsh conditions.

[0088] The adhesive layer 120 can be formed by applying the aforementioned adhesive composition to at least one surface of the base film 110, and then drying and / or curing it. For example, the adhesive layer 120 can be formed by applying the adhesive composition onto the base film 110 using a coating method such as roll coating, gravure coating, reverse coating, spray coating, air knife coating, or die coating.

[0089] According to an exemplary embodiment, the gel fraction of the adhesive layer 120 may be 60% to 80%, preferably 65% ​​to 75%. The gel fraction of the adhesive layer 120 can be calculated using the following formula 1.

[0090] [Formula 1] Gel fraction (%) = W2 / W1 × 100

[0091] In Equation 1, W1 may be the initial weight of the adhesive layer. W2 may be the weight measured after immersing the adhesive layer in an ethyl acetate solution at room temperature for 3 days and drying it at 120°C for 24 hours.

[0092] If the gel fraction of the adhesive layer 120 is less than 60%, the degree of crosslinking and cohesive force will be low, which may reduce durability over time and reworkability. If the gel fraction of the adhesive layer 120 exceeds 80%, excessive crosslinking may reduce the durability and adhesion of the adhesive layer 120, and damage to the target object may occur when the adhesive sheet is peeled off.

[0093] According to an exemplary embodiment, the rate of change of adhesive strength of the adhesive sheet according to the following formula 2 may be 0.8 to 2.2, preferably 1.1 to 2.1. Within this range, adhesive reliability at room temperature and high temperature can be ensured, and improved reworkability can be achieved.

[0094] [Formula 2] Adhesion change rate = P H / P C

[0095] In formula 2, P C This indicates the adhesive strength measured by leaving an adhesive sheet attached to an object to be adhered to for 24 hours under conditions of 23°C and 50%RH, and then peeling the adhesive sheet from the object to be adhered to at a peeling speed of 300 mm / min and a peeling angle of 180° under the same conditions.

[0096] P HThis indicates the adhesive strength measured by leaving an adhesive sheet attached to an object to be adhered to for 48 hours under conditions of 50°C and 50%RH, and then peeling the adhesive sheet from the object to be adhered to at a peeling speed of 300 mm / min and a peeling angle of 180° under conditions of 23°C and 50%RH.

[0097] The aforementioned rate of change in adhesive strength can represent the ratio of the adhesive strength at heated temperatures (approximately 50°C) to the adhesive strength at room temperature (approximately 23°C), and can be used as a measure to judge the reworkability after being left heated for a long period of time.

[0098] Referring to Figure 1, the adhesive sheet may further include a release film 130 disposed on one surface of the adhesive layer 120. For example, the adhesive sheet may have a base film 110, an adhesive layer 120, and a release film 130 arranged in sequence.

[0099] In some embodiments, the adhesive sheet can be provided in a form in which a base film 110 and a release film 130 are attached to both sides. Referring to Figure 2, when using the adhesive sheet, the release film 130 can be removed from the adhesive sheet. In this case, the release film 130 can be removed from the adhesive sheet, and the exposed adhesive layer 120 can be attached to the object to be adhered (for example, a display panel).

[0100] In some embodiments, the adhesive sheet can be provided in a form in which a release film 130 is attached to both sides of the adhesive layer 120.

[0101] For example, a laminate can be formed by removing the release film 130 attached to one side of the adhesive sheet and attaching an optical substrate film 110 or a functional layer (e.g., an anti-reflective layer) to the exposed surface of the adhesive layer 120.

[0102] In one embodiment, the anti-reflective layer may be provided as an anti-reflective plate attached to one side of the optical substrate film 110, or it may be attached to the other side of the optical substrate film 110 to which the adhesive layer 120 of an adhesive sheet is attached.

[0103] <Optical film, image display device> Figure 3 is a schematic cross-sectional view illustrating an optical film according to an exemplary embodiment.

[0104] Referring to Figure 3, the optical film may include a base film 110, an adhesive layer 120 disposed on one surface of the base film 110, and an optical functional layer 140 disposed on the other surface of the base film 110.

[0105] For example, an optical film can be formed by first forming an optical functional layer 140 on one surface of a base film 110, and then applying and curing an adhesive composition on the other surface of the base film 110 to form an adhesive layer 120.

[0106] In some embodiments, the optical functional layer 140 may include an anti-reflective layer, a hard coat layer, a phase difference layer, a polarizer, and the like. For example, the optical film can be provided as an anti-reflective film, a hard coat film, a window film, a phase difference film, a polarizer, and the like, depending on the optical functional layer 140.

[0107] In some embodiments, the optical film may further include a release film disposed on one side of the adhesive layer 120. For example, the optical film may be provided in a form in which a base film 110 and a release film are attached to both sides of the adhesive layer 120. In this case, the release film formed on one side of the adhesive layer 120 can be removed, and the exposed side of the adhesive layer 120 can be attached to an object (e.g., a display panel).

[0108] In some embodiments, when release films 130 are attached to both sides of the adhesive layer 120, the release film 130 on one side of the adhesive layer 120 can be removed, and the optical functional layer 140 can be attached to the exposed surface. Additionally, any remaining release film 130 on the other side of the adhesive layer 120 can be removed, and an object (e.g., a display panel) can be attached to the exposed surface.

[0109] Figure 4 is a schematic cross-sectional view illustrating an image display device according to an exemplary embodiment.

[0110] According to an exemplary embodiment, the image display device may include a display panel 200 and an optical film disposed on the display panel 200.

[0111] In some embodiments, the image display device may include a display panel 200 and an optical film disposed on the upper surface of the display panel via an adhesive layer 120. For example, the image display device can be provided by removing the release film from the optical film and attaching the exposed adhesive layer 120 to the display panel 200.

[0112] The display panel 200 may be a liquid crystal display panel (LCD), an organic light-emitting display panel (OLED), or a quantum dot light-emitting display panel (QLED).

[0113] In addition to the above configuration, the image display device may further include other configurations known in the art. For example, it may further include a phase difference film, a hard coat film, a protective film, a window film, a touch panel, and the like. These configurations can be attached to one another by an adhesive composition according to an exemplary embodiment.

[0114] As described above, the improved adhesion and bonding between the base film 110 and the adhesive layer 120 result in enhanced durability and stability. Therefore, the adhesive reliability of the image display device can be maintained for a long period of time, even under physical external forces such as repeated bending, or under harsh conditions of high temperature and humidity, and breakage, peeling, and lifting of each component can be prevented.

[0115] Furthermore, even after being left for a long period of time under harsh conditions of high temperature and humidity, the adhesive sheet can be peeled off without damaging the object during rework or leaving any adhesive residue.

[0116] The following are preferred embodiments to aid in understanding the present invention. These embodiments are merely illustrative 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 embodiments are possible within the scope of the present invention and the technical concept, and that such variations and modifications naturally fall within the scope of the appended claims.

[0117] Manufacturing example Manufacturing Example 1: Production of Acrylic Copolymer (A-1) In a 1 L reactor equipped with a cooling device to facilitate temperature control and reflux of nitrogen gas, 100 parts by weight of a monomer mixture consisting of 68.8% by weight of n-butyl acrylate (BA), 30% by weight of methacrylate (MA), 0.2% by weight of acrylic acid (AA), and 1.0% by weight of 2-hydroxyethyl methacrylate (2-HEMA) was added. Then, 100 parts by weight of ethyl acetate (EA) was added as a solvent. After that, nitrogen gas was added for 1 hour to remove oxygen and replace the mixture, and the temperature was maintained at 62°C. After homogenizing the mixture, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and the mixture was reacted for 8 hours to produce an acrylic copolymer (A-1) with a molecular weight of approximately 1.24 million.

[0118] Manufacturing Example 2: Production of Acrylic Copolymer (A-2) An acrylic copolymer (A-2) with a molecular weight of approximately 1.27 million was prepared in the same manner as in Production Example 1, except that a monomer mixture consisting of 78.8% by weight of n-butyl acrylate (BA), 20% by weight of methacrylate (MA), 0.2% by weight of acrylic acid (AA), and 1.0% by weight of 2-hydroxyethyl methacrylate (2-HEMA) was added.

[0119] Manufacturing Example 3: Production of Acrylic Copolymer (A-3) An acrylic copolymer (A-3) with a molecular weight of approximately 1.42 million was produced in the same manner as in Production Example 1, except that a monomer mixture consisting of 74% by weight of n-butyl acrylate (BA), 25% by weight of methacrylate (MA), 0.3% by weight of acrylic acid (AA), and 0.7% by weight of 2-hydroxyethyl methacrylate (2-HEMA) was added.

[0120] Manufacturing Example 4: Manufacturing of Acrylic Copolymer (A-4) An acrylic copolymer (A-4) with a molecular weight of approximately 1.4 million was prepared in the same manner as in Production Example 1, except that a monomer mixture consisting of 53.3% by weight of n-butyl acrylate (BA), 45% by weight of methacrylate (MA), 0.2% by weight of acrylic acid (AA), and 1.5% by weight of 2-hydroxyethyl methacrylate (2-HEMA) was added.

[0121] Manufacturing Example 5: Production of Acrylic Copolymer (A-5) An acrylic copolymer (A-5) with a molecular weight of approximately 1.41 million was prepared in the same manner as in Production Example 1, except that a monomer mixture consisting of 93.8% by weight of n-butyl acrylate (BA), 5% by weight of methacrylate (MA), 0.2% by weight of acrylic acid (AA), and 1.0% by weight of 2-hydroxyethyl methacrylate (2-HEMA) was added.

[0122] Manufacturing Example 6: Production of Acrylic Copolymer (A-6) An acrylic copolymer (A-6) with a molecular weight of approximately 1.39 million was produced in the same manner as in Production Example 1, except that a monomer mixture consisting of 67.8% by weight of n-butyl acrylate (BA), 30% by weight of methacrylate (MA), 1.2% by weight of acrylic acid (AA), and 1.0% by weight of 2-hydroxyethyl methacrylate (2-HEMA) was added.

[0123] Manufacturing Example 7: Manufacturing of Acrylic Copolymer (A-7) An acrylic copolymer (A-7) with a molecular weight of approximately 1.4 million was produced in the same manner as in Production Example 1, except that a monomer mixture consisting of 69% by weight of n-butyl acrylate (BA), 30% by weight of methacrylate (MA), and 1.0% by weight of 2-hydroxyethyl methacrylate (2-HEMA) was added.

[0124] Examples (1) Manufacturing of adhesive compositions The adhesive compositions of the examples and comparative examples were prepared by mixing the components and their respective contents as shown in Table 1 below, and then diluting them with ethyl acetate to a concentration of 20% by weight of solids. Here, the content is in parts by weight.

[0125] (2) Manufacturing of adhesive sheets The manufactured adhesive composition was applied onto a release film coated with a silicone release agent, and dried at 100°C for 2 minutes to form an adhesive layer with a thickness of 20 μm. A corona-discharge treated triacetylcellulose (TAC) film was laminated onto the formed adhesive layer to produce an adhesive sheet.

[0126] [Table 1] JPEG0007899324000006.jpg55150

[0127] The specific ingredient names shown in Table 1 are as follows: Acrylic copolymer (A) A-1: Copolymer produced in Production Example 1 A-2: Copolymer produced in the above production example 2 A-3: Copolymer produced in the above production example 3 A-4: Copolymer produced in the above production example 4 A-5: Copolymer produced in the above production example 5 A-6: Copolymer produced in the above production example 6 A-7: Copolymer produced in the above production example 7 Crosslinking agent (B) B-1:D-110N (manufactured by Mitsui Chemicals) B-2: Coronate-HXR (manufactured by Nippon Polyurethane Industry Co., Ltd.) B-3: CL-467 (Made by MENADIONA) B-4: Coronate-L (manufactured by Nippon Polyurethane Industry Co., Ltd.) Organosilicon compounds (C) C-1: Compound represented by the following chemical formula 1-1 [ka] C-2: Compound represented by the following chemical formula 2-1 [ka] C-3: Compound represented by the following chemical formula 3 [ka] Antistatic agent (D) 1-Octyl-4-methylpyridinium hexafluorophosphate

[0128] Experimental example (1) Evaluation of adhesive strength The adhesive sheet manufactured as described above was cut to a length of 25 mm x width of 100 mm, the release film was peeled off, and the exposed adhesive layer was attached to a glass substrate (#1737, Corning agent) with a pressure of 0.25 MPa. A test specimen was prepared by autoclaving at a temperature of 50°C and 5 atmospheres for 20 minutes.

[0129] To measure the adhesive strength at room temperature, the test specimens prepared as described above were left for 24 hours under conditions of 23°C and 50% RH. Using a universal tensile testing machine (UTM, Instron), the adhesive sheet was peeled from the glass substrate at a peeling speed of 300 mm / min and a peeling angle of 180° to measure the adhesive strength at room temperature.

[0130] To measure the heated adhesive strength, the test specimens prepared as described above were left for 48 hours under conditions of 50°C and 50%RH. Subsequently, the heated adhesive strength was measured by peeling the adhesive sheet from the glass substrate at a peeling speed of 300 mm / min and a peeling angle of 180° using a universal tensile testing machine (UTM, Instron) under conditions of 23°C and 50%RH.

[0131] (2) Measurement of reworkability The adhesive sheet manufactured as described above was cut to a length of 25 mm x width of 100 mm, the release film was peeled off, and the exposed adhesive layer was attached to a glass substrate with a pressure of 0.25 MPa. A test specimen was then prepared by autoclaving at a temperature of 50°C and 5 atmospheres for 20 minutes.

[0132] To measure the heat reworkability, the test specimens prepared as described above were left in an 80°C oven for 10 hours, then removed and stored at room temperature for 120 hours, after which the adhesive layer was peeled off at a speed of 1.3 cm / sec.

[0133] To measure the moisture and heat reworkability, the test specimens prepared as described above were left in an oven at 60°C and 90% RH for 12 hours, then stored at room temperature for 120 hours, and finally the adhesive layer was peeled off at a speed of 1.3 cm / sec. The evaluation criteria are as follows.

[0134] <Evaluation Criteria> ○: In both heat-resistant and moisture-resistant reworkability, no adhesive residue is left on the glass substrate, and the base film (TAC film) peels off cleanly without tearing. ×: In either the heat-resistant reworkability or the moisture-resistant heat-resistant reworkability, adhesive residue remains on the glass substrate, or the base film (TAC film) tears during peeling.

[0135] (3) Evaluation of durability (heat resistance, moisture resistance) The manufactured adhesive sheet was cut to a length of 200 mm x width of 300 mm, the release film was peeled off, and the exposed adhesive layer was attached to a glass substrate (210 mm x 350 mm x 0.7 mm). Test specimens were then prepared by autoclaving (50°C x 30 minutes, 0.5 MPa). The pressure applied during this process was 5 kg / cm². 2 Therefore, the work was performed in a cleanroom to prevent the generation of air bubbles or foreign matter.

[0136] The heat resistance was evaluated by leaving the test specimens at 80°C for 1000 hours and then observing for the presence of bubbles or delamination. The humid heat resistance was evaluated by leaving the test specimens at 60°C and 90% RH for 1000 hours and then observing for the presence of bubbles or delamination. At this time, the test specimens were left at room temperature for 24 hours immediately before evaluation. The evaluation criteria are as follows.

[0137] <Evaluation Criteria> ◎: No bubbles or peeling. ○: Bubbles or peeling <5 pieces △: 5 or fewer bubbles or peeling < 10 ×: 10 or fewer bubbles or peeling

[0138] (4) Measurement of adhesion The adhesive sheet manufactured as described above was cut to a size of 25 mm in length and 50 mm in width, and attached to a SUS304 plate via double-sided adhesive tape (width: 25 mm, manufactured by SOOKWANG) on the TAC film surface. Then, the adhesive layer surface was moved back and forth 20 times in the length (25 mm) direction using elastic rubber (neoprene rubber, manufactured by Gouda) at a pressure of 1 MPa and a speed of 0.1 m / s. At this time, the distance the adhesive layer was extruded on the TAC film was measured to determine the adhesion. The evaluation criteria are as follows.

[0139] ◎: Less than 10mm ○: 10mm or more and less than 15mm △: 15mm or more and less than 20mm ×: 20mm or more

[0140] (5) Evaluation of gel fraction Approximately 0.25g of the adhesive layer of an adhesive sheet was attached to a 250-mesh wire mesh (100mm x 100mm), and the mesh was surrounded to prevent leakage of the gel powder. After measuring the weight (B) with a precision balance, the wire mesh was immersed in an ethyl acetate solution for 3 days. The immersed wire mesh was removed, washed with a small amount of ethyl acetate solution, dried at 120°C for 24 hours, and then its weight (C) was measured. The gel fraction was calculated using the measured weight with the following formula 1.

[0141] [Formula 1] Gel fraction (%) = (CA) / (BA) × 100

[0142] In the formula, A is the weight of the wire mesh, B is the weight of the wire mesh with the adhesive layer attached, and C is the weight of the wire mesh after immersion and drying. Therefore, (BA) represents the initial weight of the adhesive layer, and (CA) represents the weight of the gelled adhesive layer.

[0143] The evaluation results are summarized in Table 2 below.

[0144] The adhesive strength ratio in Table 2 below refers to the ratio of heated adhesive strength to adhesive strength at room temperature.

[0145] [Table 2] JPEG0007899324000011.jpg58155

[0146] The adhesive sheet according to the above-described example can achieve improved reworkability even after being left for a long time while ensuring adhesion to the base film. Therefore, it can be confirmed that durability such as heat resistance and heat and humidity resistance is improved when the organosilicon compound contains a malonyl group or an acetoacetyl group, and an amine group or a sulfide group. In contrast, it can be confirmed that the adhesive sheet according to the comparative example does not have a malonyl group or an acetoacetyl group in the organosilicon compound, and its reworkability after being left for a long time in a high-temperature and high-humidity environment is significantly reduced.

Claims

1. Acrylic copolymers and Non-yellowing type isocyanate-based or aziridine-based crosslinking agent, It comprises an organosilicon compound having at least two carbonyl groups, The aforementioned acrylic copolymer is a polymer obtained by polymerizing a polymerizable mixture containing a first monomer which is an alkyl (meth)acrylate monomer having 1 to 3 carbon atoms, a second monomer which is an alkyl (meth)acrylate monomer having 4 to 12 carbon atoms, a (meth)acrylic acid monomer, and a polar functional group-containing crosslinkable monomer. The polymerizable mixture contains 15% to 35% by weight of the first monomer, 60% to 89% by weight of the second monomer, and 0.01% to 1% by weight of the (meth)acrylic acid monomer. The content of the non-yellowing type isocyanate-based or aziridine-based crosslinking agent is 0.1 to 3 parts by weight per 100 parts by weight of the acrylic copolymer, in an adhesive composition.

2. The adhesive composition according to claim 1, wherein the polar functional group of the crosslinkable monomer containing the polar functional group comprises at least one of a hydroxyl group, an amide group, and an amine group.

3. The adhesive composition according to claim 1, wherein the content of the polar functional group-containing crosslinkable monomer is 0.1% to 5% by weight relative to the total weight of the polymerizable mixture.

4. The adhesive composition according to claim 1, wherein the organosilicon compound comprises a nitrogen atom or a sulfur atom.

5. The adhesive composition according to claim 4, wherein the organosilicon compound comprises an amine group or a sulfide group.

6. The adhesive composition according to claim 1, wherein the organosilicon compound has two carbonyl groups linked by a methylene group.

7. The adhesive composition according to claim 6, wherein the organosilicon compound has a malonyl group or an acetoacetyl group.

8. The adhesive composition according to claim 1, wherein the organosilicon compound comprises a compound represented by the following chemical formula 1 or the following chemical formula 2. 【Chemistry 1】 【Chemistry 2】 (In the above chemical formulas 1 and 2, R １ R is an alkoxy group having 1 to 12 carbon atoms. ６ R is an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms. ２ and R ７ Each of these is independently a divalent aliphatic hydrocarbon having 1 to 30 carbon atoms. R ３ ~R ５ and R ８ ~R １０ These are, independently, hydrogen, a C1-C12 alkyl group, a C2-C12 alkenyl group, a C2-C12 alkynyl group, or a C1-C12 alkoxy group.

9. The adhesive composition according to claim 1, comprising 0.1 to 3 parts by weight of the non-yellowing type isocyanate or aziridine crosslinking agent and 0.01 to 3 parts by weight of the organosilicon compound, per 100 parts by weight of the acrylic copolymer.

10. The adhesive composition according to claim 1, further comprising an ionic antistatic agent.

11. A base film and An adhesive sheet comprising an adhesive layer disposed on the base film and formed using the adhesive composition described in claim 1.

12. The adhesive sheet according to claim 11, wherein the rate of change of adhesive strength of the adhesive sheet according to the following formula 2 is 0.8 to 2.

2. [Formula 2] Adhesion change rate = P Ｈ / P Ｃ (In formula 2, P Ｃ This is the adhesive strength measured by attaching the adhesive sheet to the target object, leaving it for 24 hours under conditions of 23°C and 50% RH, and then peeling the adhesive sheet from the target object at a peeling speed of 300 mm / min and a peeling angle of 180°. P Ｈ This refers to the adhesive strength measured after attaching the adhesive sheet to the target object, leaving it for 48 hours under conditions of 50°C and 50% RH, and then peeling the adhesive sheet from the target object at a peeling speed of 300 mm / min and a peeling angle of 180° under conditions of 23°C and 50% RH.

13. A base film and An adhesive layer is disposed on the upper surface of the base film and formed using the adhesive composition described in claim 1, An optical film comprising an anti-reflective layer disposed on the lower surface of the base film.

14. An image display device comprising the optical film described in Claim 13.

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