Adhesive composition, adhesive sheet, optical film, and image display device

Abstract

The invention provides an adhesive composition, an adhesive sheet, an optical film, and an image display device. The adhesive composition according to an embodiment of the present invention comprises an acrylic copolymer, a cross-linking agent, and an ionic antistatic agent that is an ionic compound represented by Chemical Formula 1, in Chemical Formula 1, R1 is hydrogen or a methyl group, and R2 is an alkyl group having 10-30 carbon atoms. According to an embodiment of the present invention, an adhesive sheet and an optical film comprising an adhesive layer formed from the adhesive composition are provided. Chemical formula 1 # imgabs0 #

Description

Technical Field

[0001] The present invention relates to an adhesive composition, an adhesive sheet, an optical film, and an image display device. Background Art

[0002] In order to bond a display panel of an image display device such as a liquid crystal display (LCD) device or an organic light emitting display (OLED) device to various optical structures or circuit structures, an adhesive or an adhesive sheet can be used. The above-mentioned adhesive needs to have improved transparency to avoid deteriorating the optical characteristics of the image display device, and at the same time have high adhesive strength.

[0003] In recent years, active research has been conducted on displays that are highly reliable even under severe conditions of high temperature and high humidity or external physical shocks. Therefore, structures combined with the above-mentioned displays also need to be formed so as to prevent the structures from falling off or peeling even under severe conditions and external shocks.

[0004] Therefore, there is a need for an adhesive or an adhesive sheet that has high adhesive strength and durability and can bond the above-mentioned display structures. Summary of the Invention

[0005] Problems to be Solved

[0006] One problem of the present invention is to provide an adhesive composition capable of forming an adhesive layer having improved durability.

[0007] One problem of the present invention is to provide an adhesive sheet including an adhesive layer formed using the above-mentioned adhesive composition and an optical film manufactured from the above-mentioned adhesive sheet.

[0008] Means for Solving the Problems

[0009] 1. An adhesive composition comprising an acrylic copolymer, a crosslinking agent, and an ionic antistatic agent which is an ionic compound represented by the following Chemical Formula 1:

[0010] [Chemical Formula 1]

[0011]

[0012] (In the above Chemical Formula 1, R1 is hydrogen or methyl, and R2 is an alkyl group having 10 to 30 carbon atoms).

[0013] 2. The adhesive composition according to 1 above, wherein in the above Chemical Formula 1, R2 is a linear alkyl group having 12 to 18 carbon atoms.

[0014] 3. The adhesive composition according to 1 above, wherein the melting point of the ionic antistatic agent is 23°C or higher.

[0015] 4. The pressure-sensitive adhesive composition as described in 1 above, wherein the melting point of the ionic antistatic agent is 25°C to 70°C.

[0016] 5. The pressure-sensitive adhesive composition as described in 1 above, wherein the content of the ionic antistatic agent is 0.01 parts by weight to 7 parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0017] 6. The pressure-sensitive adhesive composition as described in 1 above, wherein the content of the ionic antistatic agent is 1 part by weight to 5 parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0018] 7. The pressure-sensitive adhesive composition as described in 1 above, wherein the acrylic copolymer is formed from a polymerizable mixture containing (meth)acrylic acid alkyl ester monomers, (meth)acrylic acid ester monomers containing an aromatic group, and crosslinkable monomers containing a polar functional group.

[0019] 8. The pressure-sensitive adhesive composition as described in 7 above, wherein the (meth)acrylic acid alkyl ester monomers include a first monomer and a second monomer, the first monomer is a (meth)acrylic acid alkyl ester monomer having 1 to 3 carbon atoms, and the second monomer is a (meth)acrylic acid alkyl ester monomer having 4 to 12 carbon atoms.

[0020] 9. The pressure-sensitive adhesive composition as described in 7 above, wherein the polar functional group of the crosslinkable monomer containing a polar functional group includes at least one of a carboxyl group, a hydroxyl group, an amide group, and an amine group.

[0021] 10. The pressure-sensitive adhesive composition as described in 1 above, wherein the crosslinking agent includes a non-yellowing isocyanate-based crosslinking agent.

[0022] 11. The pressure-sensitive adhesive composition as described in 1 above, wherein the content of the crosslinking agent is 0.1 parts by weight to 3 parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0023] 12. The pressure-sensitive adhesive composition as described in 1 above, which further includes a silane coupling agent.

[0024] 13. The pressure-sensitive adhesive composition as described in 12 above, wherein the content of the silane coupling agent is 0.01 parts by weight to 3 parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0025] 14. A pressure-sensitive adhesive sheet, which includes a base film and a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is disposed on the base film and formed using the pressure-sensitive adhesive composition described in 1 above.

[0026] 15. The pressure-sensitive adhesive sheet as described in 14 above, wherein the base film includes at least one selected from the group consisting of a polarizer, an antireflection layer, a hard coat layer, and a retardation layer.

[0027] 16. The pressure-sensitive adhesive sheet as described in 14 above, wherein the surface resistivity value of the pressure-sensitive adhesive layer has a value of 1×10 11 Ω / □ or less.

[0028] 17. An optical film comprising a base film, a pressure-sensitive adhesive layer, and an antireflection layer, wherein the pressure-sensitive adhesive layer is disposed on the upper surface of the base film and formed using the pressure-sensitive adhesive composition described in 1 above, and the antireflection layer is disposed on the lower surface of the base film.

[0029] 18. An image display device comprising the optical film described in 17 above.

[0030] Advantages of the Invention

[0031] With the pressure-sensitive adhesive composition of the exemplary embodiments of the present invention, a pressure-sensitive adhesive layer having improved adhesive force can be formed. In addition, with the above pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer having a low surface resistivity value can be achieved.

[0032] The pressure-sensitive adhesive sheet of the exemplary embodiments of the present invention can firmly adhere to an adherend even in a high-temperature and / or high-humidity environment, and can have improved adhesive force and sealing property. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 and Figure 2 is a schematic cross-sectional view for explaining the pressure-sensitive adhesive sheet of the exemplary embodiment.

[0034] Figure 3 is a schematic cross-sectional view for explaining the optical film of the exemplary embodiment.

[0035] Figure 4 is a schematic cross-sectional view for explaining the image display device of the exemplary embodiment.

[0036] REFERENCE SIGNS

[0037] 110: Base film 120: Pressure-sensitive adhesive layer

[0038] 130: Release film 140: Optical functional layer

[0039] 200: Display panel DETAILED DESCRIPTION

[0040] The pressure-sensitive adhesive composition of the embodiments of the present invention includes an acrylic copolymer, a crosslinking agent, and an ionic antistatic agent having a long-chain alkyl group. In addition, according to the embodiments of the present invention, there are provided a pressure-sensitive adhesive sheet and an optical film having a pressure-sensitive adhesive layer formed from the above pressure-sensitive adhesive composition.

[0041] Hereinafter, the present disclosure will be described in detail with reference to the drawings. However, this is merely illustrative, and the present disclosure is not limited by the specific embodiments illustrated.

[0042] <Adhesive Composition>

[0043] The adhesive composition of the exemplary embodiment contains an ionic antistatic agent. The above ionic antistatic agent has an imidazolium-based cation and a bis(fluorosulfonyl)imide anion. The above ionic antistatic agent may contain an ionic compound having an imidazolium-based cation and a bis(fluorosulfonyl)imide anion. The above ionic antistatic agent can impart ionic conductivity to the adhesive layer formed from the adhesive composition.

[0044] By including the above ionic compound as an ionic antistatic agent, the stability of the adhesive composition over time and the durability of the adhesive layer can be improved. In addition, the ionic solid has high compatibility, and the transparency of the adhesive composition can be maintained high.

[0045] The above ionic compound can be a solid at room temperature. Thus, the above ionic compound and the adhesive composition containing it can be easily handled. In addition, the exudation phenomenon of the adhesive layer formed from the adhesive composition containing a liquid ionic compound can be reduced, and the contamination of the adherend can be prevented.

[0046] In the exemplary embodiment, the melting point of the ionic antistatic agent can be 23 °C or higher. In some embodiments, the melting point of the ionic antistatic agent can be 25 °C to 70 °C. In this case, the mobility of the ionic antistatic agent inside the adhesive layer at room temperature can be reduced. Thus, the ionic antistatic agent does not dissolve out to the end of the adhesive layer, and the contamination of the adherend can be prevented.

[0047] The above ionic antistatic agent may contain a long-chain alkyl group bonded to the cationic nitrogen of the imidazolium skeleton. Thus, the ionic antistatic agent is an ionic solid at room temperature and does not dissolve out of the adhesive layer.

[0048] In some embodiments, the above ionic antistatic agent may contain an ionic compound represented by the following Chemical Formula 1.

[0049] [Chemical Formula 1]

[0050]

[0051] In the above Chemical Formula 1, R1 can be hydrogen or methyl. For example, R1 can be methyl.

[0052] In the above Chemical Formula 1, R2 can be an alkyl group having 10 to 30 carbon atoms. For example, R2 can be an alkyl group having 12 to 28 carbon atoms, an alkyl group having 12 to 18 carbon atoms, or an alkyl group having 13 to 17 carbon atoms.

[0053] According to an exemplary embodiment, the above R2 may be a straight-chain alkyl group having 12 to 18 carbon atoms. The above ionic antistatic agent may include, for example, 1-dodecyl-3-methylimidazolium, 1-tetradecyl-3-methylimidazolium, 1-octadecyl-3-methylimidazolium, etc. as the above imidazolium-based cations. They may be used alone or in combination of two or more.

[0054] In the exemplary embodiment, the content of the above ionic antistatic agent may be 0.01 part by weight to 5 parts by weight relative to 100 parts by weight of the above acrylic copolymer. In some embodiments, the content of the above ionic antistatic agent may be 0.1 part by weight to 4.5 parts by weight, 1 part by weight to 4 parts by weight, 1.5 parts by weight to 3.5 parts by weight, or 2 parts by weight to 3 parts by weight relative to 100 parts by weight of the above acrylic copolymer.

[0055] Within the above range, the antistatic property of the adhesive layer can be improved, and the durability of the adhesive layer can be maintained excellently.

[0056] The adhesive composition of the exemplary embodiment may include an acrylic copolymer. The above acrylic copolymer may include an acrylic copolymer formed from a polymerizable mixture, and the above polymerizable mixture may include a (meth)acrylate-based monomer, a (meth)acrylate-based monomer containing an aromatic group, and a crosslinkable monomer containing a polar functional group.

[0057] The term “(meth)acrylate” used in this specification is used in the sense of covering acrylate or methacrylate.

[0058] The above (meth)acrylate-based monomer may be a (meth)acrylate-based monomer having 1 to 12 carbon atoms. The above (meth)acrylate-based monomer having 1 to 12 carbon atoms may include a first (meth)acrylate-based monomer having 1 to 3 carbon atoms and a second (meth)acrylate-based monomer having 4 to 12 carbon atoms. According to the exemplary embodiment, the above polymerizable mixture contains both the first monomer and the second monomer, so that improved adhesive strength can be achieved, and defects of the adhesive sheet can be prevented from occurring even in a high-temperature and / or high-humidity environment.

[0059] Each of the above first monomer and the above second monomer may be a compound derived from an aliphatic alcohol having 1 to 12 carbon atoms.

[0060] Examples of the above first monomer may include (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, etc. For example, it may be (meth)acrylic acid methyl ester. They may be used alone or in combination of two or more.

[0061] In an exemplary embodiment, the content of the above-mentioned first monomer in the total weight of the above-mentioned polymerizable mixture may be 15% by weight to 45% by weight. In some embodiments, the content of the above-mentioned first monomer in the total weight of the above-mentioned polymerizable mixture may be 20% by weight to 40% by weight or 25% by weight to 35% by weight. Within the above range, the adhesive strength and heat resistance of the adhesive sheet can be sufficiently improved.

[0062] Examples of the above-mentioned second monomer include n-butyl (meth)acrylate, 2-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, etc. The above-mentioned second monomer may be, for example, n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate. They can be used alone or in combination of two or more.

[0063] In an exemplary embodiment, the content of the above-mentioned second monomer in the total weight of the above-mentioned polymerizable mixture may be 40% by weight to 80% by weight. In some embodiments, the content of the above-mentioned second monomer in the total weight of the above-mentioned polymerizable mixture may be 45% by weight to 70% by weight or 55% by weight to 70% by weight. Within the above range, a decrease in the durability of the adhesive layer due to a decrease in the cohesion of the adhesive composition can be prevented, and the crosslinking density and adhesion of the adhesive layer can be improved.

[0064] In an exemplary embodiment, in the total weight of the above-mentioned polymerizable mixture, the ratio of the content of the above-mentioned second monomer to the content of the above-mentioned first monomer may be 1 to 3. In some embodiments, in the total weight of the above-mentioned polymerizable mixture, the ratio of the content of the above-mentioned second monomer to the content of the above-mentioned first monomer may be 1.2 to 2.7.

[0065] Within the above range, the content of the second monomer having a longer alkyl group than the first monomer can be equal to or more than the content of the first monomer, thereby improving the heat resistance of the adhesive sheet.

[0066] According to an exemplary embodiment, the above-mentioned polymerizable mixture may contain an aromatic group-containing (meth)acrylate monomer. Thus, the acrylic copolymer can contain a highly heat-resistant and bulky aromatic group, and the durability of the adhesive sheet in a harsh environment can be improved. In addition, the acrylic copolymer formed from the polymerizable mixture containing the aromatic group-containing (meth)acrylate monomer can increase the refractive index of the adhesive composition, thereby improving the light leakage phenomenon.

[0067] According to an exemplary embodiment, the aromatic group of the above-mentioned aromatic group-containing (meth)acrylate monomer may include an aryl group having 6 to 20 carbon atoms. The above-mentioned aryl group refers to a hydrocarbon group containing at least one aromatic ring. For example, it may include a phenyl group, a biphenyl group, a naphthyl group, etc.

[0068] According to an exemplary embodiment, the above-mentioned aromatic group-containing (meth)acrylate monomer may include an aryloxy group having 6 to 20 carbon atoms. The above-mentioned aryloxy group may refer to a group formed by the combination of an oxygen atom and an aryl group. For example, the above-mentioned aryloxy group may include a phenoxy group, a biphenoxy group, a naphthyloxy group, etc.

[0069] According to an exemplary embodiment, the above-mentioned aromatic group-containing (meth)acrylate monomer may include a structure in which the (meth)acrylate group is bonded to an aryloxy group having 6 to 20 carbon atoms through an alkylene linking group.

[0070] According to some embodiments, the above-mentioned aromatic group-containing (meth)acrylate monomer may include a structure in which an aryl group having 6 to 20 carbon atoms and a (meth)acrylate group are bonded through a polyether segment. The so-called "polyether segment" may refer to a linking group structure containing a divalent alkylene oxide repeating unit (-O-(CH2) m -).

[0071] The above-mentioned aromatic group-containing (meth)acrylate monomer may be represented by the following Chemical Formula 2.

[0072] [Chemical Formula 2]

[0073]

[0074] In the above Chemical Formula 2, Ar may be an aryl group having 6 to 20 carbon atoms.

[0075] In the above Chemical Formula 2, R3 may be an alkylene group having 1 to 5 carbon atoms, R4 may be hydrogen or methyl, and m may be an integer from 1 to 10.

[0076] Examples of the above-mentioned aromatic group-containing (meth)acrylate monomer include phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, biphenoxymethyl (meth)acrylate, biphenoxyethyl (meth)acrylate, biphenoxypropyl (meth)acrylate, phenoxyethoxyethyl (meth)acrylate, phenoxyethoxyethoxyethyl (meth)acrylate, etc. The above-mentioned aromatic group-containing (meth)acrylate monomer may be, for example, phenoxyethyl (meth)acrylate. They may be used alone or in combination of two or more.

[0077] According to an exemplary embodiment, the content of the above-mentioned aromatic group-containing (meth)acrylate monomer in the total weight of the above-mentioned polymerizable mixture may be 1% by weight to 15% by weight. According to some embodiments, the content of the above-mentioned aromatic group-containing (meth)acrylate monomer in the total weight of the above-mentioned polymerizable mixture may be 5% by weight to 10% by weight. Within the above range, a light compensation function against light leakage can be imparted by controlling the refractive index without reducing the adhesive properties.

[0078] The above-mentioned crosslinkable monomer containing a polar functional group may include a crosslinkable group capable of polymerizing with the above-mentioned (meth)acrylate monomer to form a copolymer and a polar functional group capable of being included in the form of binding to the copolymer chain.

[0079] The above-mentioned crosslinkable monomer containing a polar functional group can increase the crosslinking degree of the acrylic copolymer. In addition, by reacting with a crosslinking agent described later, it is possible to prevent the cohesion of the adhesive layer from decreasing under high-temperature / high-humidity conditions and impart adhesive strength.

[0080] The above-mentioned polar functional group may include a carboxyl group, a hydroxyl group, an amide group, an amine group, etc. In some embodiments, the above-mentioned crosslinkable monomer containing a polar functional group may include a crosslinkable monomer containing a carboxyl group, a crosslinkable monomer containing a hydroxyl group, a crosslinkable monomer containing an amide group, and / or a crosslinkable monomer containing an amine group. They can be used alone or in combination of two or more.

[0081] In one embodiment, the above-mentioned crosslinkable monomer containing a polar functional group may include a crosslinkable monomer containing a carboxyl group and a crosslinkable monomer containing a hydroxyl group.

[0082] In some embodiments, the content of the above-mentioned crosslinkable monomer having a polar functional group in the total weight of the above-mentioned polymerizable mixture may be 0.05% by weight to 10% by weight, for example, 0.1% by weight to 3% by weight. Within the above range, the cohesion of the adhesive composition can be ensured to improve the durability of the adhesive sheet, and the gel fraction of the adhesive composition is appropriate, so that the adhesive strength and durability can be improved.

[0083] Each of the above-mentioned crosslinkable monomer containing a carboxyl group and the crosslinkable monomer containing a hydroxyl group may include a carboxyl group or a hydroxyl group capable of being included in the form of binding to the copolymer chain, and may include a crosslinkable group capable of polymerizing with the above-mentioned (meth)acrylate monomer to form a copolymer.

[0084] The above-mentioned crosslinkable monomer containing a carboxyl group can function to impart adhesive strength to the adhesive composition. For example, since the acrylic copolymer has an acidic group derived from the carboxyl group-containing monomer, the adhesion and crosslinking degree of the adhesive composition can be improved.

[0085] Examples of the above carboxyl group-containing crosslinkable monomers include acrylic acid, methacrylic acid, etc. They can be used alone or in combination of two or more.

[0086] The content of the above carboxyl group-containing crosslinkable monomer in the total weight of the above polymerizable mixture can be 0.01% by weight to 0.5% by weight. For example, the content of the carboxyl group-containing crosslinkable monomer in the total weight of the polymerizable mixture can be 0.1% by weight to 0.5% by weight.

[0087] When the content of the carboxyl group-containing crosslinkable monomer is within the above range, the adhesive strength of the adhesive sheet formed from the adhesive composition can be appropriately increased, and the above ionic antistatic agent can be prevented from transferring to the surface of the adhesive sheet.

[0088] If the above polymerizable mixture does not contain a carboxyl group-containing crosslinkable monomer, the adhesive strength, adhesion, and durability under extreme environments of the adhesive layer may decrease.

[0089] The above hydroxyl group-containing crosslinkable monomer can impart highly polar hydroxyl groups to the acrylic copolymer. Therefore, the adhesive strength of the acrylic copolymer to the polar substrate can be increased.

[0090] Examples of the above hydroxyl group-containing crosslinkable monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethyleneglycol (meth)acrylate, 2-hydroxypropyleneglycol (meth)acrylate, hydroxyalkylene glycol (meth)acrylates 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, etc. They can be used alone or in combination of two or more.

[0091] In some embodiments, the content of the above hydroxyl group-containing crosslinkable monomer in the total weight of the polymerizable mixture can be 0.5% by weight to 5% by weight. For example, the content of the hydroxyl group-containing crosslinkable monomer in the total weight of the polymerizable mixture can be 0.5% by weight to 4% by weight.

[0092] Examples of the above amide group-containing crosslinkable 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, 2-hydroxyethylhexyl (meth)acrylamide, etc. They can be used alone or in combination of two or more.

[0093] As the above-mentioned amine-containing crosslinkable monomer, a crosslinkable monomer containing a tertiary amino group may be included. Examples of the above-mentioned crosslinkable monomer containing a tertiary amino group include N,N-(dimethylamino)ethyl (meth)acrylate, N,N-(diethylamino)ethyl (meth)acrylate, N,N-(dimethylamino)propyl (meth)acrylate, and the like. They may be used alone or in combination of two or more.

[0094] In some embodiments, in addition to the above monomers, other polymerizable monomers well-known in the art may be further used within a range that does not reduce the adhesive strength. For example, the content of the above other polymerizable monomers may be 10% by weight or less in the total weight of the polymerizable mixture.

[0095] The method for producing the above acrylic copolymer is not particularly limited, and it can be produced by methods such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization commonly used in the art. Preferably, it can be produced by solution polymerization. In addition, solvents, polymerization initiators, chain transfer agents for controlling the molecular weight, etc. commonly used can be used during polymerization.

[0096] In some embodiments, the above adhesive composition contains a crosslinking agent. The above crosslinking agent can play a role in improving the cohesion, adhesion, and high-temperature reliability of the adhesive and maintaining the shape of the adhesive.

[0097] In some embodiments, the above crosslinking agent may be a non-yellowing isocyanate-based crosslinking agent. The yellowing isocyanate-based crosslinking agent may refer to a compound in which the nitrogen atom of the isocyanate in the isocyanate-based crosslinking agent is directly connected to the carbon of the phenyl group, and the non-yellowing isocyanate-based crosslinking agent may refer to the remaining compounds in the above isocyanate-based crosslinking agent other than the above yellowing isocyanate-based crosslinking agent.

[0098] The above isocyanate-based compound may have high reactivity with polar functional groups and may have improved adhesion to a substrate film treated by corona discharge or plasma treatment.

[0099] Examples of the above-mentioned isocyanate compounds include: diisocyanate compounds such as xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and tetramethylxylene diisocyanate; adducts obtained by reacting 1 equivalent of a polyol compound such as trimethylolpropane with 3 equivalents of a diisocyanate compound, isocyanurate bodies obtained by self-condensation of 3 equivalents of a diisocyanate compound, biuret bodies obtained by condensing diisocyanate urea obtained from 2 equivalents of 3 equivalents of a diisocyanate compound with the remaining 1 equivalent of a diisocyanate, polyfunctional isocyanate compounds having 3 functional groups such as triphenylmethane triisocyanate and methylene bis triisocyanate, etc. They can be used alone or in combination of two or more.

[0100] In some embodiments, relative to 100 parts by weight of the above acrylic copolymer, the content of the above crosslinking agent can be 0.1 part by weight to 3 parts by weight, for example, it can be 0.1 part by weight to 2 parts by weight. Within the above range, appropriate crosslinking can be achieved between acrylic copolymer chains to improve the adhesion durability and cut-off property of the adhesive layer. In addition, the adhesion between the adhesive sheet and the adherend can be improved.

[0101] The above adhesive composition may further contain a silane coupling agent. The above silane coupling agent can inhibit the warping and peeling of the adhesive layer formed by the adhesive composition by forming a covalent bond or a hydrogen bond with a functional group present on the surface of the adherend, and can improve the adhesive force.

[0102] The above silane coupling agent may include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyldimethylethoxysilane, etc. They can be used alone or in combination of two or more.

[0103] In some embodiments, relative to 100 parts by weight of the above acrylic copolymer, the content of the above silane coupling agent can be 0.01 part by weight to 3 parts by weight, for example, it can be 0.1 part by weight to 2 parts by weight.

[0104] The above adhesive composition may further contain commonly known additives in the art to adjust the required adhesive force, cohesion, tackiness, elastic modulus, glass transition temperature, etc. according to the use. For example, the above adhesive composition may contain a tackifier, an antioxidant, a corrosion inhibitor, a leveling agent, a surface lubricant, a dye, a pigment, an antifoaming agent, a filler, a light stabilizer, a plasticizer, etc. as additives.

[0105] <Adhesive Sheet>

[0106] Hereinafter, embodiments of the present invention will be described more specifically with reference to the accompanying drawings. However, the following drawings attached to this specification are illustrative embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the above-described invention content. Therefore, the present invention should not be construed as being limited only to the matters described in these drawings.

[0107] Figure 1 It is a schematic cross-sectional view showing an adhesive sheet of an exemplary embodiment.

[0108] Referring to Figure 1 , the adhesive sheet of the 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.

[0109] The adhesive layer may be formed of the adhesive composition. For example, the adhesive layer 120 may be formed by coating an adhesive composition containing an acrylic copolymer, a crosslinking agent, and an ionic antistatic agent having an imidazolium-based cation of Chemical Formula 1 and a bis(fluorosulfonyl)imide anion on the base film 110 and then curing it.

[0110] In some embodiments, the base film 110 may include an acrylic resin, a cellulose resin, a polyolefin resin, a polyester resin, or the like. In this case, the transparency, mechanical strength, thermal stability, moisture resistance, isotropy, etc. of the base film 110 can be improved.

[0111] For example, the base film 110 may include: acrylic resins such as poly(methyl)methacrylate, poly(methyl)acrylate; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polybutylene naphthalate; cellulose resins such as diacetyl cellulose, triacetyl cellulose, butene cellulose acetate; polyolefin resins such as polyethylene, polypropylene, cycloolefin, polyolefin having a norbornene structure, ethylene-propylene copolymer; sulfone resins; polyether-ether-ketone resins; allylated resins; or a mixture of the above resins.

[0112] In some embodiments, the base film 110 may include a polarizer, an antireflection layer, a hard coat, a retardation layer, etc. For example, the base film 110 may be provided as a polarizing plate, an antireflection film, a hard coat film, a window film, a retardation film, etc.

[0113] For example, since the base film 110 includes a polarizer, the base film 110 may be provided as a polarizing plate.

[0114] In one embodiment, at least one surface of the above-mentioned 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, sandblasting treatment, primer treatment, etc. can be performed on one surface of the above-mentioned base film 110.

[0115] Through the above surface treatment, carboxylic acid derivatives (R-COOH) can be generated on the surface of the base film 110. The carboxyl group of the above carboxylic acid derivatives can react with the adhesive composition, thereby enabling the adhesion between the adhesive layer and the base film to be further improved.

[0116] In one embodiment, the surface of the above-mentioned base film 110 may not be subjected to saponification treatment. Since the surface of the base film for the adhesive sheet is hydrophobic, the adhesion and adhesiveness to the adhesive may deteriorate. In this case, a pretreatment process of immersing the surface of the base film in an alkaline aqueous solution for saponification can be performed, or a separate coating can be formed between the base material and the adhesive, or the surface of the base film can be subjected to corona or plasma treatment to improve the adhesiveness between the base material and the adhesive.

[0117] However, in the case of performing the saponification process or forming a separate coating, the process becomes complicated, which may lead to a decrease in the yield and processability of the adhesive sheet, and due to the additional pretreatment or coating formation process, contamination and quality degradation of the adhesive sheet may occur.

[0118] The adhesive composition of the above embodiment can improve the adhesion between the adhesive layer 120 and the surface of the base film 110 because the organosilicon compound having a malonyl group or an acetoacetyl group increases the affinity between the surface of the base film 110 and the adhesive composition. In addition, heat resistance, heat and humidity resistance durability, and adhesion reliability can be maintained under harsh conditions of high temperature and high humidity, and improved reworkability can be achieved even after long-term placement under the above harsh conditions.

[0119] The surface resistivity value of the adhesive layer can be 1×10 11 Ω / □ or less. In exemplary embodiments, it can be 6×10 10 Ω / □ or less or 5.5×10 10 Ω / □ or less.

[0120] The adhesive layer 120 can be formed by coating the above-mentioned adhesive composition on at least one surface of the base film 110 and drying and / or curing it. For example, the above-mentioned adhesive composition can be coated on the base film 110 by coating methods such as roll coating, gravure coating, reverse coating, spraying, air knife coating, die coating, etc., thereby forming the adhesive layer 120.

[0121] According to an exemplary embodiment, the gel fraction of the above-mentioned adhesive layer 120 may be 60% to 80%, for example, it may be 65% to 75%. The gel fraction of the adhesive layer 120 can be calculated by the following formula 1.

[0122] [Formula 1]

[0123] Gel fraction (%) = W2 / W1 × 100

[0124] In Formula 1, W1 may be the initial weight of the adhesive layer. W2 may be the weight measured after immersing the above-mentioned adhesive layer in an ethyl acetate solution at room temperature for 3 days and drying it at 120 °C for 24 hours.

[0125] When the gel fraction of the adhesive layer 120 is less than 60%, due to the low crosslinking degree and cohesion, the durability over time and the reworkability may decrease. When the gel fraction of the adhesive layer 120 is higher than 80%, due to excessive crosslinking, the durability and adhesion of the adhesive layer 120 may decrease, and damage may occur to the object when peeling off the adhesive sheet.

[0126] 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 above-mentioned adhesive sheet may be sequentially provided with a base film 110, an adhesive layer 120, and a release film 130.

[0127] In some embodiments, the above-mentioned adhesive sheet may be provided in a form with a base film 110 and a release film 130 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 then the exposed adhesive layer 120 can be attached to an object to be adhered (for example, a display panel).

[0128] In some embodiments, the above-mentioned adhesive sheet may be provided in a form with release films 130 attached to both sides of the adhesive layer 120.

[0129] For example, the release film 130 attached to one surface of the adhesive sheet can be removed, and an optical base film 110 or a functional layer (for example, an antireflection layer) can be attached to the exposed surface of the adhesive layer 120, thereby forming a laminate.

[0130] In one embodiment, the antireflection layer can also be provided as an antireflection plate attached to one surface of the optical base film 110, and the adhesive layer 120 of the adhesive sheet can also be attached to the other surface of the optical base film 110.

[0131] <Optical film, Image display device>

[0132] Figure 3It is a schematic cross-sectional view of an optical film for illustrating exemplary embodiments.

[0133] Referring to Figure 3 , the optical film may include a substrate film 110, an adhesive layer 120 disposed on one surface of the substrate film 110, and an optical functional layer 140 disposed on the other surface of the substrate film 110.

[0134] For example, the optical film may be formed by forming an optical functional layer 140 on one surface of the substrate film 110, and then coating and curing an adhesive composition on the other surface of the substrate film 110 to form the adhesive layer 120.

[0135] In some embodiments, the optical functional layer 140 may include an antireflection layer, a hard coat layer, a retardation layer, a polarizer, etc. For example, the optical film may be provided as an antireflection film, a hard coat film, a window film, a retardation film, a polarizing plate, etc. according to the difference of the optical functional layer 140.

[0136] In some embodiments, the optical film may further include a release film disposed on one surface of the adhesive layer 120. For example, the optical film may be provided in a form in which the substrate film 110 and the release film are attached to both surfaces of the adhesive layer 120. In this case, the release film formed on one surface of the adhesive layer 120 may be removed, and then the exposed surface of the adhesive layer 120 may be attached to an object (e.g., a display panel).

[0137] In some embodiments, when release films 130 are attached to both surfaces of the adhesive layer 120, after removing the release film 130 on one surface, the above-mentioned optical functional layer 140 may be attached to the exposed surface, and after removing the release film 130 remaining on the other surface of the above-mentioned adhesive layer 120, the object (e.g., a display panel) may be attached to the exposed surface.

[0138] Figure 4 It is a schematic cross-sectional view of an image display device for illustrating exemplary embodiments.

[0139] According to an exemplary embodiment, the above-mentioned image display device may include a display panel 200 and an optical film disposed on the above-mentioned display panel 200.

[0140] In some embodiments, the image display device may include a display panel 200 and an optical film disposed on the upper surface of the above-mentioned display panel via an adhesive layer 120. For example, the image display device may be provided by removing the release film from the above-mentioned optical film and attaching the exposed adhesive layer 120 to the display panel 200.

[0141] The above-mentioned 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).

[0142] In addition to the above-described components, the image display device may further include other components well-known in the art. For example, it may further include a retardation film, a hard coat film, a protective film, a window film, a touch panel, etc. The above-described components may be attached to each other using the adhesive composition of the exemplary embodiment.

[0143] As described above, by improving the adhesion and bonding between the substrate film 110 and the adhesive layer 120, improved durability and stability can be achieved. Therefore, even under physical external forces such as repeated bending or under harsh conditions of high temperature and high humidity, the adhesion reliability of the image display device can be maintained for a long time, and breakage, peeling, and warping of each component can be prevented.

[0144] In addition, when reworking after long-term placement under harsh conditions of high temperature and high humidity, the adhesive sheet can be peeled off without damage to the object or residue of the adhesive substance.

[0145] Hereinafter, the embodiments of the present invention will be further described with reference to specific experimental examples. It will be apparent to those skilled in the art that the examples and comparative examples included in the experimental examples are merely illustrative of the present invention and do not limit the scope of the appended claims. Various changes and modifications can be made to the examples within the scope and technical concept of the present invention, and of course, such changes and modifications also fall within the scope of the appended claims.

[0146] Production Example 1: Production of Acrylic Copolymer (A-1)

[0147] In a 1L reactor with nitrogen reflux and a cooling device for easy temperature adjustment, 100 parts by weight of a polymerizable mixture containing 65.8% by weight of n-butyl acrylate (BA), 25% by weight of methyl acrylate (MA), 8% by weight of phenoxyethyl acrylate (PEA), 0.2% by weight of acrylic acid (AA), and 1.0% by weight of 2-hydroxyethyl acrylate (2-HEA) and 100 parts by weight of ethyl acetate (EA) as a solvent were introduced to prepare a mixture. To remove oxygen, nitrogen was passed through the mixture for 1 hour for replacement, and then the temperature was maintained at 62°C. After the mixture was uniformly stirred, 0.07 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was introduced and reacted for 8 hours to prepare an acrylic copolymer (A-1) with a weight average molecular weight of 1.51 million.

[0148] Production Examples 2 to 9

[0149] As shown in Table 1 below, the monomer types and contents were adjusted, and except for this, acrylic copolymers were prepared by the same method as in Production Example 1. The monomer contents are expressed in units of % by weight based on the total weight of the polymerizable mixture.

[0150] [Table 1]

[0151]

[0152] M-1: n-Butyl acrylate

[0153] M-2: Methyl acrylate

[0154] M-3: Phenoxyethyl acrylate

[0155] M-4: Acrylic acid

[0156] M-5: 2-Hydroxyethyl acrylate (2-HEA)

[0157] Examples 1 to 17 and Comparative Examples 1 to 3

[0158] (1) Preparation of the adhesive composition

[0159] Prepare a mixture according to the components and contents shown in Table 2 below, and then dilute it in ethyl acetate to a concentration with a solid content of 14% by weight, thereby preparing the adhesive compositions of the examples and comparative examples. The content unit of each component in the following table is parts by weight relative to 100 parts by weight of the acrylic copolymer.

[0160] (2) Preparation of the adhesive sheet

[0161] Apply the prepared adhesive composition onto a release film coated with a silicone release agent, and dry it at 100 °C for 2 minutes to form an adhesive layer with a thickness of 20 μm. Laminate a polarizing plate as a base film on the formed adhesive layer to prepare an adhesive sheet. The above polarizing plate uses an iodine-based polarizing plate (thickness 185 μm) in which a corona-discharge-treated cycloolefin (COP) film is laminated on one side of a polyvinyl alcohol (PVA) polarizer and a triacetyl cellulose (TAC) film is laminated on the other side. Laminate in such a manner that the corona-discharge-treated COP film surface contacts the above adhesive layer.

[0162] [Table 2]

[0163]

[0164] A-1 to A-9: Acrylic copolymers of Production Examples 1 to 9

[0165] B-1 D-110N: XDI-based crosslinking agent (Mitsui Chemicals)

[0166] B-2 Coronate-HXR: HDI-based crosslinking agent (Nippon Polyurethane Industry Co., Ltd.)

[0167] C-1: KBM-403 (3-Glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu)

[0168] D-1: The compound represented by the following Chemical Formula 1-1 (ImC12-FSI, melting point: 42 °C)

[0169] [Chemical Formula 1-1]

[0170]

[0171] D-2: The compound represented by the following Chemical Formula 1-2 (ImC14-FSI, melting point: 66 °C)

[0172] [Chemical Formula 1-2]

[0173]

[0174] D-3: The compound represented by the following Chemical Formula 1-3 (ImC18-FSI, melting point: 48 °C)

[0175] [Chemical Formula 1-3]

[0176]

[0177] D-4: The compound represented by the following Chemical Formula 1-4 (H-ImC14-FSI, melting point: 40 °C)

[0178] [Chemical Formula 1-4]

[0179]

[0180] D-5: The compound represented by the following Chemical Formula 1-5 (ImC10-FSI, melting point: below 25 °C)

[0181] [Chemical Formula 1-5]

[0182]

[0183] D-6: IL-P-18-2 (1-octyl-4-methylpyridinium hexafluorophosphate, manufactured by Kyoei Chemical)

[0184] D-7: The compound represented by the following Chemical Formula 4

[0185] [Chemical Formula 4]

[0186]

[0187] D-8: The compound represented by the following Chemical Formula 5 (ImC8-FSI, melting point: below 25 °C)

[0188] [Chemical Formula 5]

[0189]

[0190] Experimental Example

[0191] (1) Adhesion evaluation

[0192] After cutting the adhesive sheets of the examples and comparative examples into a length of 25 mm × a width of 100 mm and peeling off the release film, the exposed adhesive layer was attached to a glass substrate (#1737, manufactured by Corning), and autoclave treatment was performed at a temperature of 50 °C and a pressure of 5 atmospheres for 20 minutes to produce test pieces.

[0193] To measure the adhesion, the test pieces produced above were placed at a temperature of 23 °C and a humidity of 50% RH for 24 hours. Using a universal tensile testing machine (UTM, manufactured by Instron), the adhesive sheet was peeled from the glass substrate at a peeling speed of 300 mm / min and a peeling angle of 180 o to measure the adhesion at room temperature.

[0194] (2) Durability (heat resistance, damp heat resistance) evaluation

[0195] After cutting the adhesive sheets of the examples and comparative examples into a length of 200 mm × a width of 300 mm and peeling off the release film, the exposed adhesive layer was attached to a glass substrate (210 mm × 350 mm × 0.7 mm), and then autoclave treatment (50 °C × 30 minutes, 0.5 MPa) was performed to produce test pieces. At this time, the applied pressure was 5 kg / cm 2 , and clean room operation was performed to prevent the generation of bubbles or foreign matters.

[0196] In the heat resistance evaluation, after the test pieces were placed at a temperature of 80 °C or 95 °C for 1000 hours, it was observed whether bubbles or peeling occurred. In the damp heat resistance evaluation, after the test pieces were placed at 60 °C, 90% RH or at 65 °C, 95% RH for 1000 hours, it was observed whether bubbles or peeling occurred. At this time, before evaluating the state of the test pieces, they were placed at room temperature for 24 hours and then observed.

[0197] <Evaluation criteria>

[0198] : No bubbles or peeling;

[0199] ○: Less than 5 bubbles or peeling;

[0200] △: 5 ≤ bubbles or peeling < 10;

[0201] ×: 10 ≤ bubbles or peeling.

[0202] (3) Sealing property measurement

[0203] The above - manufactured adhesive sheet is cut into a size of 25 mm in length x 50 mm in width, and the polarizing plate is attached to the SUS304 plate with a double - sided adhesive tape (width: 25 mm, manufactured by SOOKWANG) on one side. Then, using elastic rubber (neoprene), a pressure of 1 MPa and a speed of 0.1 m / s are applied to one side of the adhesive layer, and it reciprocates 20 times in the length (25 mm) direction. Measure the distance that the adhesive layer is pushed on the TAC film at this time, and thereby judge the adhesion.

[0204] (4) Measurement of antistatic property

[0205] After cutting the above - manufactured adhesive sheet into a length of 200 mm × width of 300 mm and peeling off the release film, measure the surface resistivity value of the exposed adhesive layer, and thereby evaluate the antistatic property. Regarding the measurement method, use a resistivity meter HIRESTA UP - HT450 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.) to measure the surface resistivity under the conditions of 25 °C, 50% RH, 500 V, and 10 seconds.

[0206] The results are shown in Table 3 below.

[0207] [Table 3]

[0208]

[0209] Referring to Table 3 above, the adhesive force and adhesion of the adhesive sheet of the example containing the adhesive layer formed of the adhesive composition containing the ionic compound of Chemical Formula 1 are improved. In addition, the surface resistivity value of the adhesive sheet of the example is low, and it has improved antistatic property. Moreover, even when placed in a high - temperature and high - humidity environment for a long time, the bonding quality can be maintained without deterioration.

[0210] The adhesive sheet of the comparative example is formed of an adhesive composition containing an ionic antistatic agent different from the ionic compound of Chemical Formula 1. Therefore, a large number of bubbles or peeling occur in a high - temperature and high - humidity environment, and the durability is reduced. In addition, the surface resistivity of the adhesive sheet of the comparative example has a higher value compared to the surface resistivity of the adhesive sheet of the example.

[0211] What is described above is only an example of applying the principle of the present disclosure, and other configurations may also be included within the scope of the present invention without departing from the scope of the present invention.

Claims

1. An adhesive composition, comprising: An acrylic copolymer; A crosslinking agent; and An ionic antistatic agent which is an ionic compound represented by the following Chemical Formula 1: Chemical Formula 1 In the Chemical Formula 1, R1 is hydrogen or methyl, and R2 is an alkyl group having 10 to 30 carbon atoms.

2. The adhesive composition according to claim 1, wherein in the Chemical Formula 1, R2 is a straight-chain alkyl group having 12 to 18 carbon atoms.

3. The adhesive composition according to claim 1, wherein the ionic antistatic agent has a melting point of 23°C or higher.

4. The adhesive composition according to claim 1, wherein the ionic antistatic agent has a melting point of 25°C to 70°C.

5. The adhesive composition according to claim 1, wherein the content of the ionic antistatic agent is 0.01 parts by weight to 7 parts by weight based on 100 parts by weight of the acrylic copolymer.

6. The adhesive composition according to claim 1, wherein the content of the ionic antistatic agent is 1 part by weight to 5 parts by weight based on 100 parts by weight of the acrylic copolymer.

7. The adhesive composition according to claim 1, wherein the acrylic copolymer is formed from a polymerizable mixture comprising (meth)acrylic acid alkyl ester monomers, (meth)acrylic acid ester monomers containing an aromatic group, and crosslinkable monomers containing a polar functional group.

8. The adhesive composition according to claim 7, wherein the (meth)acrylic acid alkyl ester monomers comprise a first monomer and a second monomer, the first monomer is a (meth)acrylic acid alkyl ester monomer having 1 to 3 carbon atoms, and the second monomer is a (meth)acrylic acid alkyl ester monomer having 4 to 12 carbon atoms.

9. The adhesive composition according to claim 7, wherein the polar functional group of the crosslinkable monomer containing a polar functional group comprises at least one of a carboxyl group, a hydroxyl group, an amide group, and an amine group.

10. The adhesive composition according to claim 1, wherein the crosslinking agent comprises a non-yellowing isocyanate-based crosslinking agent.

11. The adhesive composition according to claim 1, wherein the content of the crosslinking agent is 0.1 parts by weight to 3 parts by weight based on 100 parts by weight of the acrylic copolymer.

12. The adhesive composition according to claim 1, further comprising a silane coupling agent.

13. The adhesive composition according to claim 12, wherein the content of the silane coupling agent is 0.01 parts by weight to 3 parts by weight based on 100 parts by weight of the acrylic copolymer.

14. An adhesive sheet, comprising a base film and an adhesive layer, The adhesive layer is disposed on the base film and is formed using the adhesive composition according to claim 1.

15. The adhesive sheet according to claim 14, wherein the base film comprises at least one selected from the group consisting of a polarizer, an antireflection layer, a hard coat, and a retardation layer.

16. The pressure-sensitive adhesive sheet according to claim 14, wherein the surface resistivity value of the pressure-sensitive adhesive layer has a value of 1×10 11 Ω / □ or less.

17. An optical film, comprising a base film, an adhesive layer, and an antireflection layer, The adhesive layer is disposed on the upper surface of the base film and is formed using the adhesive composition according to claim 1, The antireflection layer is disposed on the lower surface of the base film.

18. An image display device, which includes the optical film described in claim 17.

Images