KR102654651B1 - Adhesive sheet, optical film and display device using the same - Google Patents

Abstract

The present invention relates to an adhesive sheet, and more specifically, to an adhesive sheet including a base film having a water contact angle in a predetermined range, and an adhesive layer disposed on the base film. It is possible to provide an optical film that has excellent adhesion between the base film and the adhesive layer and has excellent adhesive durability and reliability even under harsh conditions such as high temperature and high humidity.

Description

Adhesive sheet, optical film and image display device comprising the same {ADHESIVE SHEET, OPTICAL FILM AND DISPLAY DEVICE USING THE SAME}

The present invention relates to an adhesive sheet, an optical film containing the same, and an image display device. More specifically, it relates to a pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing an acrylic copolymer, and an optical film and image display device including the same.

For example, an adhesive or an adhesive sheet may be used to bond a display panel of an image display device such as a liquid crystal display (LCD) device, an organic light emitting display (OLED) device, and various optical structures or circuit structures. The adhesive needs to have improved transparency and excellent adhesive strength so as not to deteriorate the optical properties of the image display device.

Recently, flexible displays that can be folded or bent have been widely used, and displays that can operate under harsh conditions of high temperature/high humidity or external physical shock are being actively researched. Accordingly, structures coupled to the display are also designed to have appropriate elasticity, flexibility, and durability.

Therefore, the adhesive or adhesive sheet used to bond the structure needs to be formed to prevent the structure from falling off or peeling off despite harsh conditions or physical impact.

For example, Korean Patent Publication No. 2010-0039274 discloses an adhesive for a polarizing plate applied to an image display device.

Korean Patent Publication No. 2010-0039274

One object of the present invention is to provide an adhesive sheet with improved adhesive properties and durability.

One object of the present invention is to provide an optical film or an image display device using the adhesive sheet.

1. A base film having a water contact angle of 40 to 65°; and an adhesive layer disposed on the upper surface of the base film and containing a cured product of an adhesive composition containing an acrylic copolymer and a crosslinking agent,

When the upper surface of the adhesive layer is repeatedly loaded 20 times in one direction parallel to the upper surface of the adhesive layer at a pressure of 1 MPa and a speed of 0.1 m/s, the moving distance (d ₁ ) of the adhesive layer in the one direction is 15 mm. Below, adhesive sheet.

2. The adhesive sheet according to 1 above, wherein the surface roughness (Ra) of the upper surface of the base film is 10 to 50 nm.

3. The adhesive sheet of 1 above, wherein the water contact angle of the base film is 40 to 45°.

4. The adhesive sheet of 1 above, wherein the base film is corona discharge treated or plasma treated.

5. The adhesive sheet of 1 above, wherein the adhesive layer has a gel fraction of 70 to 85% calculated by Equation 1 below:

[Equation 1]

Gel fraction (%) = W2/W1ⅹ100

(In Equation 1, W1 is the initial weight of the adhesive layer, and W2 is the weight measured after immersing the adhesive layer in ethyl acetate at room temperature for 3 days and drying it at 120°C for 24 hours).

6. The adhesive sheet according to 1 above, wherein the acrylic copolymer is a copolymer of a polymerizable compound containing a (meth)acrylate monomer, a (meth)acrylic acid monomer, and a crosslinkable monomer having a polar functional group.

7. The adhesive sheet according to 6 above, wherein the polar functional group includes a hydroxy group, an amide group, or an amine group.

8. The adhesive sheet of item 6 above, wherein the content of the (meth)acrylic acid monomer is 0.01 to 1% by weight based on the total weight of the polymerizable compound.

9. The adhesive sheet according to 1 above, wherein the crosslinking agent includes an isocyanate-based compound or an aziridine-based compound.

10. The adhesive sheet of 1 above, wherein the content of the crosslinking agent is 0.05 to 3 parts by weight based on 100 parts by weight of the acrylic copolymer.

11. The adhesive sheet of 1 above, wherein the adhesive composition further includes an ionic antistatic agent and a silane coupling agent.

12. The adhesive sheet according to item 11 above, wherein the ionic antistatic agent includes an ionic solid with a melting point of 20 to 50°C.

13. The adhesive sheet of item 11 above, wherein the adhesive composition includes 0.01 to 5 parts by weight of the ionic antistatic agent and 0.01 to 2 parts by weight of the silane coupling agent, based on 100 parts by weight of the acrylic copolymer.

14. An optical film comprising an adhesive sheet according to 1 above.

15. The optical film according to item 14 above, further comprising an anti-reflection layer disposed on the lower surface of the base film.

16. An image display device comprising an adhesive sheet according to 1 above.

The adhesive sheet according to embodiments of the present invention has excellent adhesion between the base film and the adhesive layer, and can have excellent adhesive durability and reliability even under harsh conditions of high temperature and high humidity. For example, the adhesive sheet may include a base film having a predetermined surface roughness, and an adhesive layer having a low movement distance (d ₁ ) when a predetermined external force is applied on the base film.

Since the adhesive sheet according to exemplary embodiments does not require a saponification process of the base film, the ease and simplicity of the process can be improved, and contamination of the adhesive sheet due to the saponification process can be prevented.

In addition, the adhesive sheet according to exemplary embodiments has excellent adhesiveness and adhesion, and, for example, when applied to bonding various structures of a flexible display, improved adhesive durability can be maintained even during repeated folding and bending operations.

1 is a schematic cross-sectional view illustrating an adhesive sheet according to example embodiments.
FIG. 2 is an exemplary cross-sectional view illustrating the moving distance (d ₁ ) of the adhesive layer on the base film according to repeated loading on the upper surface of the adhesive layer.
3 is a schematic cross-sectional view illustrating an optical film according to example embodiments.

Embodiments of the present invention provide an adhesive sheet including a base film having a water contact angle of at least one side of 40 to 65°, and an adhesive layer disposed on the upper surface of the base film. For example, the adhesive layer may be formed from an adhesive composition containing an acrylic copolymer, a crosslinking agent, an ionic antistatic agent, and a silane coupling agent.

The adhesive layer may have a moving distance (d ₁ ) of 15 mm or less in one direction when reciprocating load is applied at a predetermined pressure and a predetermined speed in one direction parallel to the one surface of the base film. Accordingly, the adhesion between the base film and the adhesive layer can be excellent, and an adhesive sheet having excellent durability and bending properties even under harsh conditions such as high temperature and high humidity can be provided.

Hereinafter, the present invention will be described in detail.

<Adhesive composition and adhesive sheet>

With reference to the drawings below, embodiments of the present invention will be described in more detail. However, the following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention along with the contents of the above-described invention, so the present invention is described in such drawings. It should not be interpreted as limited to the specifics.

1 is a schematic cross-sectional view showing an adhesive sheet according to example embodiments.

Referring to FIG. 1 , an adhesive sheet according to exemplary embodiments may include a base film 110 and an adhesive layer 120 disposed on one surface of the base film 110 .

According to exemplary embodiments, the adhesive layer 120 may be formed from an adhesive composition containing an acrylic copolymer, a crosslinking agent, an ionic antistatic agent, and a silane coupling agent. For example, the adhesive layer 120 may include a cured product of the adhesive composition described above.

According to exemplary embodiments, the acrylic copolymer may include a copolymer of a polymerizable compound including a (meth)acrylate monomer, a (meth)acrylic acid monomer, and a crosslinkable monomer having a polar functional group. As used in this application, the term “(meth)acrylate” is used to encompass acrylate or methacrylate. As used in this application, the term “(meth)acrylic acid” is used to encompass acrylic acid or methacrylic acid.

The (meth)acrylate monomer may be an alkyl (meth)acrylate monomer having an alkyl group having 1 to 12 carbon atoms. For example, the alkyl (meth)acrylate monomer may be derived from an aliphatic alcohol having 1 to 12 carbon atoms.

Examples of the alkyl (meth)acrylate monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-butyl (meth)acrylate, and t-butyl (meth)acrylate. Acrylate, pentyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate or lauryl (meth)acrylate, etc. I can hear it. These may be used alone or in combination of two or more.

In some embodiments, the content of the (meth)acrylate monomer may be 80 to 99% by weight, preferably 90 to 98% by weight, of the total weight of the polymerizable compound. If the content of (meth)acrylate monomer is less than 80% by weight, the crosslinking density and adhesion of the adhesive composition may decrease. If the content of the (meth)acrylate monomer is more than 99% by weight, the cohesion of the adhesive composition may be lowered and the durability of the adhesive layer may be reduced.

The (meth)acrylic acid monomer may serve to provide adhesive strength to the adhesive composition. For example, as the acrylic copolymer has an acidic group derived from a (meth)acrylic acid monomer in the side chain, the adhesion and crosslinking degree of the adhesive composition can be improved.

However, (meth)acrylic acid monomer may impart hydrophilicity to the adhesive composition and affect the surface transferability of the ionic antistatic agent. In addition, as the crosslinking agent, which will be described later, reacts with an acidic group derived from (meth)acrylic acid and is consumed, the cohesion and adhesion of the adhesive layer may decrease.

In some embodiments, the content of (meth)acrylic acid may be 1% by weight or less based on the total weight of the polymerizable compound. For example, the content of the (meth)acrylic acid monomer may be 0.01 to 1% by weight, preferably 0.05 to 1% by weight, and more preferably 0.1 to 0.7% by weight, based on the total weight of the polymerizable compound. 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 the (meth)acrylic acid monomer exceeds 1% by weight, the adhesion may excessively increase, which may reduce reworkability, and may affect the transfer of the ionic antistatic agent to the surface, thereby reducing durability.

The crosslinkable monomer has a polar functional group and can provide cohesion and adhesive strength to the adhesive layer. For example, the polar functional group may be a hydroxy group, an amide group, and/or an amine group, and may improve the degree of crosslinking of the acrylic copolymer.

In some embodiments, the crosslinkable monomer may include a hydroxy group-containing monomer, an amide group-containing monomer, and/or an amine group-containing monomer. These may be used alone or in combination of two or more.

Examples of the hydroxy group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Latex, 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, 2-hydroxypropylene glycol (meth)acrylate, hydroxyalkylene with 2-4 carbon atoms in the alkylene group Glycol (meth)acrylate, 4-hydroxybutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 7-hydroxyheptyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9-hyde. Examples include roxinonyl vinyl ether and 10-hydroxydecyl vinyl ether.

Examples of the amide group-containing monomers include (meth)acrylamide, N-isopropylacrylamide, N-tertiary butylacrylamide, 3-hydroxypropyl (meth)acrylamide, and 4-hydroxybutyl (meth)acryl. Amide, 6-hydroxyhexyl (meth)acrylamide, 8-hydroxyoctyl (meth)acrylamide, 2-hydroxyethylhexyl (meth)acrylamide, etc. are mentioned.

Examples of the amine group-containing monomer include N,N-(dimethylamino)ethyl(meth)acrylate, N,N-(diethylamino)ethyl(meth)acrylate, N,N-(dimethylamino)propyl ( Meta)acrylate, etc. can be mentioned.

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

In some embodiments, the content of the crosslinkable monomer may be 0.05 to 10% by weight, preferably 0.1 to 8% by weight, based on the total weight of the polymerizable compound. If the content of the crosslinkable monomer is less than 0.05% by weight, the cohesion of the adhesive composition may decrease and durability may decrease. If the content of the crosslinkable monomer exceeds 10% by weight, the gel fraction of the adhesive composition may become excessively high, resulting in reduced adhesive strength and durability.

In some embodiments, in addition to the above monomers, other polymerizable monomers known in the art are used in a range that does not reduce adhesion, for example, 10 parts by weight or less out of 100 parts by weight of the total monomers used in the production of the acrylic copolymer. More may be included.

The manufacturing method of the acrylic copolymer is not particularly limited, and can be manufactured using methods commonly used in the art, such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization, preferably using the solution polymerization method. It can be manufactured. Additionally, commonly used solvents, polymerization initiators, and chain transfer agents for molecular weight control can be used during polymerization.

In some embodiments, the weight average molecular weight (polystyrene conversion, Mw) of the acrylic copolymer may be 50,000 to 2,000,000 g/mol, and preferably 400,000 to 2,000,000 g/mol. For example, 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 g/mol, the adhesive durability may be reduced due to insufficient cohesion between the copolymers. If it exceeds 2,000,000 g/mol, a large amount of diluting solvent may be required to ensure fairness during coating.

The crosslinking agent improves the cohesion, adhesion, and high-temperature reliability of the adhesive, and can play a role in maintaining the shape of the adhesive. For example, the crosslinking agent can improve the cohesion and durability of the adhesive by reacting with the crosslinkable functional group derived from the crosslinkable monomer. Additionally, the crosslinking agent may react with a polar functional group (eg, carboxyl group) on the surface of the base film 110 to improve the adhesion of the adhesive layer 120 to the base material.

In some embodiments, the crosslinking agent may include an isocyanate-based compound, an aziridine-based compound, an epoxy-based compound, a melamine-based compound, a peroxide-based compound, a metal chelate-based compound, or an oxazoline-based compound. Preferably, the crosslinking agent may include an isocyanate-based compound and/or an aziridine-based compound. Isocyanate-based compounds and aziridine-based compounds have high reactivity toward polar functional groups and can have excellent adhesion to base films that have been corona discharge treated or plasma treated.

Examples of the isocyanate-based compounds include tolylene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and tetramethylxylene diisocyanate. Diisocyanate compounds such as isocyanate and naphthalene diisocyanate; An adduct obtained by reacting 3 equivalents of a diisocyanate compound with 1 equivalent of a polyhydric alcohol compound such as trimethylolpropane, an isocyanurate product obtained by self-condensation of 3 equivalents of a diisocyanate compound, 2 out of 3 equivalents of a diisocyanate compound Examples include polyfunctional isocyanate compounds containing three functional groups, such as biuret body, triphenylmethane triisocyanate, and methylene bistriisocyanate, in which the remaining 1 equivalent of diisocyanate is condensed with diisocyanate urea obtained from the equivalent weight. These may be used alone or in combination of two or more. More preferably, the crosslinking agent may include xylene diisocyanate, in which case durability and adhesion to the substrate can be further improved.

Examples of the aziridine-based compounds include pentaerythol-tris-(beta-(N-aziridinyl)propionate, trimethylolpropane-tris(beta-N-aziridinyl)propionate, and trimethylolpropane tris. (2-methyl-1-aziridine propionate), N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'- Bis(1-aziridinecarboxamide), triethylene melamine, bisisoprotaloyl-1-(2-methylaziridine) or tri-1-aziridinylphosphine oxide, etc. These can be used alone. Or, two or more may be used in combination.

In some embodiments, the content of the crosslinking agent may be 0.05 to 3 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the acrylic copolymer. If the content of the cross-linking agent is less than 0.05 parts by weight, cohesion is lowered due to insufficient cross-linking degree, and thus adhesive durability and cutting properties may be reduced. If the content of the cross-linking agent exceeds 3 parts by weight, excessive cross-linking reaction may occur, which may increase residual stress and reduce adhesion to the base film 110.

The ionic antistatic agent may include an ionic salt composed of an anion and a cation, and may provide ionic conductivity to the adhesive layer 120. For example, the surface resistivity value of the adhesive layer 120 may be 6×10 ¹⁰ Ω/□ or less, and preferably 3×10 ¹⁰ Ω/□ or less.

In some embodiments, the ionic antistatic agent may include an alkali metal salt, an ionic liquid, or an ionic solid, and preferably may include an ionic solid.

As the ionic antistatic agent contains an ionic solid, the stability of the adhesive composition over time and the durability of the adhesive layer 120 may be excellent. In addition, the ionic solid has excellent compatibility with the other components mentioned above and can maintain the transparency of the adhesive composition.

In some embodiments, the melting point of the ionic solid may be between 20 and 50°C. In this case, the mobility of the ionic solid is minimized, so the durability and reliability of the adhesive sheet can be excellent. For example, when the melting point of the ionic solid is less than 20°C, as the mobility of the ionic solid increases, the ionic solid may move to the end of the adhesive sheet or anti-reflective film and be eluted.

In some embodiments, the ionic solid is an anion Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , Al2Cl ₇ ^- , BF ₄ ^- , PF ₆ ^- , ClO ₄ ^- , NO ₃ ^- , CO ₃ ^{2 -} , CH ₃ COO ^- , CF ₃ COO ^- , CH ₃ SO ₃ ^- , CF3SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₃ C ^- , AsF ₆ ^- , SbF ₆ ^- , NbF ₆ ^- , TaF ₆ ^- , F(HF) _n ^- , (CN) ₂ N ^- , C ₄ F ₉ SO ₃ ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , C ₃ F ₇ COO ^- , C ₆ H ₅ COO ^- , (CF ₃ SO ₂ )(CF ₃ CO)N ^- , OTf ^- (trifluoromethanesulfonate), OTs ^- (toluenesulfonate), OMs ^- (methanesulfonate) and/or BPh ₄ ^- (tetraphenylborate) may be included.

In some embodiments, the ionic solid may include imidazolium, pyridinium, alkylammonium, alkylpyrrolidium, and/or alkylphosphonium as cations.

For example, the ionic solid may include an imidazolium salt, a pyridinium salt, an alkylammonium salt, an alkylpyrrolidium salt, and/or an alkyl phosphonium salt. These may be used alone or in combination of two or more.

Examples of the imidazolium salt include 1,3-dimethylimidazolium chloride (melting point 125°C), 1-butyl-2,3-dimethylimidazolium chloride (melting point 99°C), and 1-butyl-3-methyl. Midazolium bromide (melting point 78°C), 1-butyl-3-methylimidazolium chloride (melting point 65°C), 1-butyl-3-methylimidazolium methanesulfonate (melting point 75-80°C), 1-butyl -1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-imidazolium hexafluorophosphate (melting point 120-121°C ), 1-ethyl-3-methylimidazolium bromide (melting point 74°C), 1-ethyl-3-methylimidazolium chloride (melting point 80-84°C), 1-ethyl-3-methylimidazolium hexafluoride Lophosphate (melting point 61°C), 1-ethyl-3-methylimidazolium iodide (melting point 79°C), 1-ethyl-2,3-dimethylimidazolium chloride (melting point 181°C), 1-methyl Midazolium chloride (melting point 75°C), 1,2,3-trimethylimidazolium methylsulfate (melting point 113°C), 1-methyl-3-(3,3,4,4,5,5,6,6, 7,7,8,8,8-tridecafluorooctyl)-imidazolium hexafluorophosphate (melting point 80°C), 1-aryl-3-methylimidazolium chloride (melting point 55°C), 1-benzyl -3-methylimidazolium chloride (melting point 70°C), 1-benzyl-3-methylimidazolium hexafluorophosphate (melting point 136°C) or 1-benzyl-3-methylimidazolium tetrafluoroborate (melting point 77°C) and the like.

Examples of the pyridinium salt include 1-butyl-3-methylpyridinium bromide (melting point 43°C), 1-butyl-4-methylpyridinium bromide (melting point 137°C), and 1-butyl-4-methylpyridinium chloride ( Melting point 158℃), 1-butylpyridinium bromide (melting point 104℃), 1-butylpyridinium chloride (melting point 132℃), 1-butylpyridinium hexafluorophosphate (melting point 75℃), 1-hexylpyridinium Hexafluorophosphate (melting point 45°C), 1-octyl-4-methylpyridinium hexafluorophosphate (melting point 44°C), 1-ethylpyridinium bromide (melting point 120°C), 1-ethylpyridinium chloride (melting point 1140) ℃), etc. can be mentioned.

Examples of the alkylammonium salt include cyclohexyltrimethylammonium bis(trifluoromethanesulfonyl)imide (melting point 56°C), tetra-n-butylammonium chloride (melting point 75°C), and tetrabutylammonium bromide (melting point 119°C). , tributylmethylammonium methyl sulfate (melting point 62°C), tetrabutylammonium bis(trifluoromethylsulfonyl)imide (melting point 94-96°C), tetraethylammonium trifluoromethanesulfonate (melting point 161-163°C) ), tetrabutylammonium benzoate (melting point 64-67℃), tetrabutylammonium methanesulfate (melting point 78-80℃), tetrabutylammonium nonafluorobutanesulfonate (melting point 50-53℃), tetra-n-butyl Ammonium hexafluorophosphate (melting point 246℃), tetrabutylammonium trifluoroacetate (melting point 74-76℃), tetrahexylammonium tetrafluoroborate (melting point 90-92℃), tetrahexylammonium bromide (melting point 97℃) , tetrahexylammonium iodide (melting point 99℃), tetraoctylammonium chloride (melting point 50-54℃), tetraoctylammonium bromide (melting point 95-98℃), tetraheptylammonium bromide (melting point 89-91℃), tetra Examples include pentylammonium bromide (melting point 99°C) and n-hexadecyltrimethylammonium hexafluorophosphate (melting point 185°C).

Examples of the alkylpyrrolidium salt include 1-butyl-1-methylpyrrolidium bromide (melting point 160°C or higher), 1-butyl-1-methylpyrrolidium chloride (melting point 114°C or higher), 1-butyl-1-methylpyrrole. and lithium tetrafluoroborate (melting point 152°C).

Examples of the alkylphosphonium salt include tetrabutylphosphonium bromide (melting point 104°C), tetrabutylphosphonium chloride (melting point 62-66°C), tetrabutylphosphonium tetrafluoroborate (melting point 96-99°C), tetrabutyl Phosphonium methanesulfonate (melting point 59-62°C), tetrabutylphosphonium p-toluenesulfonate (melting point 54-57°C), and tributylhexadecylphosphonium bromide (melting point 57-62°C).

Preferably, the ionic solid may include 1-hexylpyridinium hexafluorophosphate and/or 1-octyl-4-methylpyridinium hexafluorophosphate.

In some embodiments, the content of the ionic antistatic agent may be 0.01 to 5 parts by weight based on 100 parts by weight of the acrylic copolymer. If the content of the ionic antistatic agent is less than 0.01 parts by weight, the antistatic property of the adhesive layer may be low, and if the content of the ionic antistatic agent is more than 5 parts by weight, the ionic antistatic agent may precipitate and the adhesive layer durability may decrease.

The silane coupling agent may serve to improve adhesion between the base film 110 and the adhesive layer 120. For example, the silane coupling agent can increase the adhesive strength of the adhesive composition, prevent bubbles or lifting, and improve the durability of the adhesive sheet.

Examples of the silane coupling agent include vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropyltrimethoxy. Silane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyltri Ethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2 -(Aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltriethoxy Silane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyl Trimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide or 3-isocyanate propyltri Ethoxysilane, etc. can be mentioned. These may be used alone or in combination of two or more.

In some embodiments, the content of the silane coupling agent may be 0.01 to 3 parts by weight, preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the acrylic copolymer. Within the above range, the adhesive sheet may have excellent durability and adhesion.

The adhesive composition may further include common additives known in the art to adjust adhesive strength, cohesion, viscosity, elastic modulus, glass transition temperature, etc. required for the purpose. For example, it may include tackifiers, antioxidants, corrosion inhibitors, leveling agents, surface lubricants, dyes, pigments, anti-foaming agents, fillers, light stabilizers, plasticizers, etc.

The adhesive layer 120 may be formed by applying the above-described adhesive composition on one side of the base film 110 and performing a drying and/or curing process. For example, the adhesive layer 120 can be formed by applying the adhesive composition on the base film 110 using a coating method such as roll coating, gravure coating, reverse coating, spray coating, air knife coating, or die coater. .

According to exemplary embodiments, the gel fraction of the adhesive layer 120 may be 70 to 85%, and preferably 70 to 80%. The gel fraction of the adhesive layer 120 can be calculated using Equation 1 below.

[Equation 1]

Gel fraction (%) = W2/W1ⅹ100

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.

If the gel fraction of the adhesive layer 120 is less than 70%, durability and reworkability over time may be reduced due to a decrease in crosslinking degree and cohesion. If the gel fraction of the adhesive layer is more than 85%, the durability and adhesion of the adhesive layer 120 may decrease due to excessive crosslinking, and damage to the object may occur when the adhesive sheet is peeled off.

According to exemplary embodiments, the water contact angle of the surface of the base film 110 may be 40 to 65°, preferably 40 to 50°, and more preferably 40 to 45°. For example, the contact angle of the bonding surface of the base film 110 on which the adhesive layer 120 is disposed with respect to deionized water (DIW) may be 40 to 65 degrees. For example, the water contact angle may be a contact angle measured 5 seconds after dropping 0.1 ml of deionized water (DIW) on one side of the base film 110 under conditions of 23°C and 50%RH.

For example, the adhesive layer 120 may be formed by applying the adhesive composition to one surface of the base film 110 having the water contact angle described above and curing it. When the water contact angle of the base film 110 is within the above range, affinity for the acrylic copolymer may be high, and accordingly, adhesion between the adhesive layer and the base film may be improved.

FIG. 2 is an exemplary cross-sectional view illustrating the movement distance (d ₁ ) of the adhesive layer 120 on the base film 110 due to external force.

Figure 2 (a) is an exemplary cross-sectional view for explaining the initial state of the adhesive sheet, and Figure 2 (b) is an exemplary cross-sectional view for explaining the state of the adhesive sheet after repeated loading.

According to exemplary embodiments, the adhesive layer 120 is loaded in one direction parallel to the upper surface of the adhesive layer 120 20 times at a pressure of 1 MPa and a speed of 0.1 m/s. The moving distance (d ₁ ) may be 15 mm or less. Preferably, the movement distance (d ₁ ) of the adhesive layer 120 on one side of the base film 110 may be greater than 0 mm and less than or equal to 15 mm.

For example, the movement distance d1 of the adhesive layer 120 may refer to the distance the adhesive layer 120 moves in one direction from the initial state, based on the initial state of the adhesive sheet.

Specifically, the movement distance (d ₁ ) is determined by fixing the entire surface of the base film 110 on the opposite side to which the adhesive layer 120 is attached to a SUS304 plate through a double-sided adhesive tape, and then measuring the upper surface of the adhesive layer 120. With respect to this, the maximum distance moved by the adhesive layer 120 can be measured by reciprocating the elastic rubber 20 times in one direction parallel to the upper surface of the adhesive layer 120 at a pressure of 1 MPa and a speed of 0.1 m/s.

When the movement distance (d ₁ ) of the adhesive layer 120 on the base film 110 is within the above range, adhesion and adhesion between the adhesive layer 120 and the base film 110 may be excellent. Accordingly, the adhesive durability of the adhesive sheet can be excellent, and for example, lifting and peeling between structures within an image display device can be prevented.

For example, in the case of a conventional pressure-sensitive adhesive sheet, the adhesion and adhesion to the pressure-sensitive adhesive may be deteriorated because the surface of the substrate is hydrophobic. In this case, in order to improve the adhesion between the substrate and the adhesive, a pretreatment process may be performed to saponify the surface of the substrate by immersing it in an aqueous alkaline solution, or a separate coating layer may be formed between the substrate and the adhesive.

However, when performing a saponification process or forming a separate coating layer, the yield of the adhesive sheet may decrease as the process becomes more complex, and contamination and quality deterioration of the adhesive sheet may occur due to additional processes.

In the adhesive sheet according to exemplary embodiments, the adhesive layer 120 includes a cured product of the adhesive composition described above, so that one surface of the base film 110 on which the adhesive layer 120 is disposed has the water contact angle described above. Even so, the adhesion between the base film 110 and the adhesive layer 120 may be excellent.

Accordingly, even if the bonding surface between the base film 110 and the adhesive layer 120 does not include a separate coating layer, for example, an anchor layer, the adhesion and adhesion between the base film 110 and the adhesive layer 120 can be excellent. You can. Additionally, since saponification treatment is not required for the base film 110, alkali treatment can be omitted and quality deterioration of the adhesive sheet can be prevented.

According to exemplary embodiments, the surface roughness (Ra) of at least one side of the base film 110 may be 10 to 100 nm, and preferably 20 to 60 nm. The surface roughness can be measured using an atomic force microscope (AFM).

For example, the adhesive layer 120 may be formed by applying the adhesive composition to one side of the base film 110 having the surface roughness described above and curing it. The surface roughness can increase the surface area of the base film. In this case, as the adhesive composition enters the curves or irregularities of the surface of the base film 110 and hardens, the adhesion and adhesion between the base film 110 and the adhesive layer 120 may be improved.

In some embodiments, the surface of the base film 110 to which the adhesive layer 120 is attached may be surface treated. The surface treatment may include corona discharge treatment or plasma treatment. For example, the base film 110 may be subjected to corona discharge treatment or plasma treatment to form the above-described surface roughness (Ra) and/or water contact angle.

A carboxylic acid derivative (R-COOH) may be generated on the surface of the base film 110 by the surface treatment. The carboxyl group of the carboxylic acid derivative may react with the crosslinking agent of the adhesive composition, and thus the crosslinking density, cohesion, and adhesion to the base film 110 of the adhesive layer 120 may be further improved.

According to exemplary embodiments, the base film 110 may include acrylic, cellulose, polyolefin, or polyester. In this case, the transparency, mechanical strength, thermal stability, moisture shielding, isotropy, etc. of the base film 110 may be excellent.

For example, the base film 110 may be made of an acrylic resin such as polymethyl (meth)acrylate or polyethyl (meth)acrylate; Polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate; Cellulose resins such as diacetylcellulose, triacetylcellulose, cellulose acetate butylene; It may include polyolefin resins such as polyethylene, polypropylene, cycloolefin, polyolefin with a norbornene structure, and ethylene-propylene copolymer.

In some embodiments, the adhesive sheet may further include a release film disposed on one side of the adhesive layer 120. For example, the base film 110, the adhesive layer 120, and the release film may be arranged sequentially.

For example, the adhesive sheet 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 may be removed and the exposed surface of the adhesive layer 120 may be attached to an object (eg, a display panel).

<Optical film, image display device>

3 is a schematic cross-sectional view illustrating an optical film according to example embodiments.

Referring to FIG. 3, the optical film may include a base film 110, an adhesive layer 120 disposed on the top surface of the base film 110, and an optical functional layer 130 disposed on the bottom surface of the base film. You can.

For example, the optical film is formed by forming the optical function layer 130 on one side of the base film 110, and then applying and curing the adhesive composition on the other side of the base film 110 to form the adhesive layer 120. can be formed.

In some embodiments, the optical functional layer 130 may include an anti-reflection layer, a hard coating layer, a retardation layer, or a polarizer. For example, the optical film may be provided as an anti-reflection film, hard coating film, window film, retardation film, or polarizing plate depending on the optical function layer 130.

In some embodiments, the optical film may further include a release film disposed on one side of the adhesive layer 120 that is not in contact with the base film 110 . 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 may be removed and the exposed surface of the adhesive layer 120 may be attached to an adhesive object (eg, a display panel).

According to example embodiments, an image display device including the adhesive sheet or the optical film may be provided.

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

The display panel may be a liquid crystal display panel (LCD) or an organic light emitting display panel (OLED).

The image display device may further include other configurations known in the art in addition to the above configurations. For example, retardation film, hard coating film, protective film, window film, touch panel, etc. may be further included. The components may be attached to each other using adhesive compositions according to exemplary embodiments.

As described above, improved durability and stability can be achieved due to excellent adhesion and bonding between the base film 110 and the adhesive layer 120. Therefore, the adhesion reliability of the image display device can be maintained for a long period of time even under physical external forces such as repetitive bending and folding, or under harsh conditions such as high temperature and high humidity, and each component can be prevented from breaking, peeling, and lifting.

Hereinafter, experimental examples including specific examples and comparative examples are presented to help understand the present invention, but these are only illustrative of the present invention and do not limit the scope of the appended claims, and do not limit the scope and technology of the present invention. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope of the spirit, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

Manufacturing example

Preparation Example 1: Preparation of acrylic copolymer (A-1)

In a 1L reactor equipped with a cooling device to reflux nitrogen gas and facilitate temperature control, 98 parts by weight of n-butylacrylate (BA), 0.5 parts by weight of acrylic acid (AA), and 2-hydroxyethyl methacrylate (2-HEMA) were added. ) After adding 1.5 parts by weight of the monomer mixture, 100 parts by weight of ethyl acetate (EAc) was added as a solvent. Afterwards, nitrogen gas was introduced for 1 hour to remove oxygen, and the temperature was maintained at 62°C. After mixing the mixture uniformly, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and reaction was performed for 8 hours to prepare an acrylic copolymer (weight average molecular weight: approximately 1.3 million).

Preparation Example 2: Preparation of acrylic copolymer (A-2)

In a 1L reactor equipped with a cooling device to reflux nitrogen gas and facilitate temperature control, 98.1 parts by weight of n-butylacrylate (BA), 0.3 parts by weight of acrylic acid (AA), and 2-hydroxyethyl methacrylate (2-HEMA) were added. ) After adding 1.6 parts by weight of the monomer mixture, 100 parts by weight of ethyl acetate (EAc) was added as a solvent. Afterwards, nitrogen gas was introduced for 1 hour to remove oxygen, and the temperature was maintained at 80°C. After mixing the mixture uniformly, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and reaction was performed for 8 hours to prepare an acrylic copolymer (weight average molecular weight: approximately 1.3 million).

Preparation Example 3: Preparation of acrylic copolymer (A-3)

97 parts by weight of n-butylacrylate (BA), 1.5 parts by weight of acrylic acid (AA), and 2-hydroxyethyl methacrylate (2-HEMA) were added to a 1L reactor equipped with a cooling device to reflux nitrogen gas and facilitate temperature control. ) After adding 1.5 parts by weight of the monomer mixture, 100 parts by weight of ethyl acetate (EAc) was added as a solvent. Afterwards, nitrogen gas was introduced for 1 hour to remove oxygen, and the temperature was maintained at 80°C. After mixing the mixture uniformly, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and reaction was performed for 8 hours to prepare an acrylic copolymer (weight average molecular weight: approximately 1.3 million).

Preparation Example 4: Preparation of TAC film

A triacetyl cellulose (TAC) film was prepared. The TAC film was corona discharge treated to have the surface roughness and water contact angle shown in Table 1 below, and the surface roughness and water contact angle were measured as follows.

1) Surface roughness measurement

The surface roughness (Ra) of the TAC film was measured using an optical surface roughness meter (Wyko NT9100, manufactured by Veeco Metrogy Group).

2) Water contact angle measurement

At 23°C and 50%RH, 0.1ml of deionized water (DIW) was dropped on the surface of the TAC film, and after 5 seconds, the contact angle of water was measured using a contact angle meter (DSA100).

division Corona discharge treatment saponification treatment surface roughness
(nm) water contact angle
(°) E-1 ○ × 20 44 E-2 × × 130 77 E-3 × × 110 50

Example

(1) Preparation of adhesive composition

After mixing the ingredients and amounts as shown in Tables 2 and 3 below, the adhesive compositions of Examples and Comparative Examples were prepared by diluting with ethyl acetate to a concentration of 20% by weight of solid content. At this time, the content is parts by weight.

(2) Manufacturing of adhesive sheet

The prepared adhesive composition was applied on 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. An adhesive sheet was manufactured by bonding the prepared TAC film on the formed adhesive layer.

division
(part by weight) Adhesive composition TAC film
(E) Acrylic copolymer (A) crosslinking agent
(B) Antistatic agent
(C) Silane coupling agent
(D) Example 1 100
(A-1) 0.5
(B-1) 3 0.5 E-1 Example 2 100
(A-1) 0.5
(B-1) 3 One E-1 Example 3 100
(A-1) 0.5
(B-2) 3 0.5 E-1 Example 4 100
(A-1) 0.5
(B-2) 3 One E-1 Example 5 100
(A-1) 0.7
(B-2) 3 0.5 E-1 Example 6 100
(A-2) 0.5
(B-2) 3 0.5 E-1 Example 7 100
(A-1) 0.2
(B-3) 3 0.5 E-1 Example 8 100
(A-1) 0.5
(B-3) 3 0.5 E-1 Example 9 100
(A-2) 0.2
(B-3) 3 0.5 E-1 Example 10 100
(A-1) 0.5
(B-1) 3 0.5 E-2 Example 11 100
(A-1) 0.5
(B-2) 3 0.5 E-2 Example 12 100
(A-1) 0.7
(B-2) 3 0.5 E-2 Example 13 100
(A-1) 0.2
(B-3) 3 0.5 E-2 Example 14 100
(A-2) 0.2
(B-3) 3 0.5 E-2 Example 15 100
(A-1) 0.5
(B-1) 3 0.5 E-3 Example 16 100
(A-1) 0.7
(B-2) 3 0.5 E-3

division
(part by weight) Adhesive composition TAC film
(E) Acrylic copolymer (A) crosslinking agent
(B) Antistatic agent
(C) Silane coupling agent
(D) Comparative Example 1 100
(A-1) 3.1
(B-1) 3 0.5 E-1 Comparative Example 2 100
(A-3) 0.5
(B-1) 3 0.5 E-1 Comparative Example 3 100
(A-3) 0.5
(B-2) 3 0.5 E-1 Comparative Example 4 100
(A-3) 0.5
(B-3) 3 0.5 E-1 Comparative Example 5 100
(A-1) 3.1
(B-1) 3 0.5 E-2 Comparative Example 6 100
(A-3) 0.5
(B-1) 3 0.5 E-2 Comparative Example 7 100
(A-3) 0.5
(B-2) 3 0.5 E-2 Comparative Example 8 100
(A-3) 0.5
(B-3) 3 0.5 E-2 Comparative Example 9 100
(A-3) 0.5
(B-1) 3 0.5 E-3 Comparative Example 10 100
(A-3) 0.5
(B-2) 3 0.5 E-3

The specific ingredient names listed in Table 2 and Table 3 are as follows.

Acrylic copolymer (A)

A-1: Copolymer prepared in Preparation Example 1 above

A-2: Copolymer prepared in Preparation Example 2 above

A-3: Copolymer prepared in Preparation Example 3 above

Cross-linking agent (B)

B-1: Coronate-HXR (made by Japan Polyurethane Industry)

B-2: D-110N (made by Mitsui Chemicals)

B-3: CL-427 (made by Menadiona)

Antistatic agent (C)

1-Octyl-4-methylpyridinium hexafluorophosphate

Silane coupling agent (D)

3-Glycidoxypropyl trimethoxysilane (KBM-403, manufactured by Shin-Etsu)

TAC film (E)

TAC film listed in Table 1 above

Experiment example

(1) Moving distance when external force is applied (d _One ) measurement

The prepared adhesive sheet was cut into a size of 25 mm in length x 50 mm in width and attached to a SUS304 plate using a double-sided adhesive tape (width: 25 mm, Sugwangsa) on the side of the TAC film. Afterwards, using an elastic rubber (neoprene rubber, Gouda), 20 times in the length (25 mm) direction at a pressure of 1 MPa and a speed of 0.1 m/s in a direction parallel to the top surface of the adhesive layer. round trip. At this time, the moving distance (d1) was measured by measuring the distance that the adhesive layer was pushed on the TAC film.

(2) Durability (heat resistance, moisture heat resistance) evaluation

The prepared adhesive sheet was cut into 200 mm in length MPa) to produce a specimen. At this time, the applied pressure was 5 kg/cm2 and work was done in a clean room to prevent bubbles or foreign substances from forming.

Heat resistance was evaluated by leaving the specimen at a temperature of 80°C for 1000 hours and observing whether bubbles or peeling occurred. In the evaluation of heat and moisture resistance, the specimen was left for 1000 hours under conditions of 60°C and 90%RH and then observed for the occurrence of bubbles or peeling. At this time, immediately before evaluating the condition of the specimen, it was left at room temperature for 24 hours and observed.

<Evaluation criteria>

ⓞ: No bubbles or peeling.

○: Bubbles or peeling < 5

△: 5 ≤ bubbles or peeling < 10

×: 10 ≤ Bubble or peeling

(3) Adhesion evaluation

The prepared adhesive sheet was cut to 25 mm in length x 100 mm in width, the release film was peeled off, and the exposed adhesive layer was attached to a glass substrate and autoclaved (50°C x 30 min, 0.5 MPa) to prepare a specimen.

To measure room temperature adhesion, the prepared specimen was left for 24 hours at a temperature of 23°C and 50%RH. Using a universal tensile tester (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 adhesive strength at room temperature.

To measure heated adhesion, the prepared specimen was left for 48 hours at a temperature of 50°C and 50%RH. Afterwards, using a universal tensile tester (UTM, manufactured by Instron) under the conditions of a temperature of 23°C and 50%RH, 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 heated adhesive strength. was measured.

(4) Gel fraction evaluation

Approximately 0.25 g of the adhesive layer of the adhesive sheet was attached to a finely sized 250 mesh wire mesh (100 mm x 100 mm) and wrapped to prevent the gel from leaking. After accurately measuring the weight with a precision balance, the wire mesh was immersed in an ethyl acetate solution for 3 days. The immersed wire mesh was taken out, washed with a small amount of ethyl acetate solution, dried at 120°C for 24 hours, and its weight was measured. Using the measured weight, the gel fraction was calculated using Equation 1 below.

[Equation 1]

Gel fraction (%) = (C-A)/(B-A) x 100

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 dried after immersion. Therefore, (B-A) refers to the initial weight of the adhesive layer, and (C-A) refers to the weight of the dried adhesive layer after immersion.

The results are shown in Tables 4 and 5 below.

division distance traveled
(mm) durability Adhesion (N/25mm) gel fraction
(%) heat resistance heat and moisture resistance Room temperature adhesion Warm adhesion Example 1 8 ⓞ ⓞ 3.3 7.7 79 Example 2 8 ⓞ ⓞ 2.5 8.2 82 Example 3 9 ⓞ ⓞ 3.1 7.5 80 Example 4 8 ⓞ ○ 2.9 8.4 81 Example 5 9 ⓞ ⓞ 1.9 5.8 78 Example 6 7 ⓞ ○ 2.7 7.1 79 Example 7 8 ⓞ ○ 2.3 6.2 80 Example 8 7 ⓞ ⓞ 1.8 5.5 82 Example 9 9 ⓞ ⓞ 1.6 5.4 79 Example 10 13 ⓞ ⓞ 3.1 7.5 79 Example 11 13 ⓞ ⓞ 2.9 7.6 80 Example 12 14 ⓞ ⓞ 1.8 6.1 78 Example 13 12 ⓞ ○ 2.1 6.4 80 Example 14 13 ⓞ ⓞ 1.5 5.2 79 Example 15 10 ⓞ ⓞ 3.1 7.7 80 Example 16 11 ⓞ ⓞ 1.8 5.4 79

division distance traveled
(mm) durability Adhesion (N/25mm) Gel fraction
(%) heat resistance heat and moisture resistance Room temperature adhesion Warm adhesion Comparative Example 1 19 × × 0.5 4.2 78 Comparative Example 2 25 △ × 0.9 4.8 83 Comparative Example 3 25 △ △ 1.1 4.7 80 Comparative Example 4 25 × × 0.9 4.9 79 Comparative Example 5 25 × × 0.3 3.9 77 Comparative Example 6 25 × × 0.7 4.3 80 Comparative Example 7 25 × × 0.9 4.4 75 Comparative Example 8 25 × × 0.8 4.9 78 Comparative Example 9 25 × × 0.8 4.5 79 Comparative Example 10 25 × × 1.0 4.5 76

It can be confirmed that the adhesive sheets according to the above-described examples have excellent durability and heat resistance, as the movement distance (d ₁ ) of the adhesive layer on the unsaponifiable TAC film is 15 mm or less. For example, because the adhesive layer has excellent adhesion even to an unsaponifiable TAC film, fracture, cutting, and peeling of the adhesive sheet can be suppressed.

However, the adhesive sheets according to the comparative examples did not substantially achieve adhesion of the adhesive layer to the unsaponifiable TAC film, and thus durability and heat resistance were reduced.

110: Base film 120: Adhesive layer
130: Optical functional layer

Claims (16)

A base film containing acrylic resin or cellulose resin and having a water contact angle of 40 to 65°; and
It is disposed on the upper surface of the base film and includes an adhesive layer containing a cured product of an adhesive composition containing an acrylic copolymer and a crosslinking agent,
The acrylic copolymer is a copolymer of a polymerizable compound containing a (meth)acrylate monomer, a (meth)acrylic acid monomer, and a crosslinkable monomer having a polar functional group, and the content of the (meth)acrylic acid monomer is determined by the total amount of the polymerizable compound. 0.01 to 1% by weight of the weight,
The adhesive composition does not contain any other copolymers other than the acrylic copolymer,
When repeatedly loaded 20 times at a pressure of 1 MPa and a speed of 0.1 m/s in one direction parallel to the upper surface of the adhesive layer with respect to the upper surface of the adhesive layer, the moving distance (d ₁ ) of the adhesive layer in the one direction is 15 mm. Below, adhesive sheet.
The adhesive sheet according to claim 1, wherein the surface roughness (Ra) of the upper surface of the base film is 10 to 100 nm.
The adhesive sheet of claim 1, wherein the water contact angle of the base film is 40 to 45°.
The adhesive sheet of claim 1, wherein the base film is corona discharge treated or plasma treated.
The adhesive sheet of claim 1, wherein the adhesive layer has a gel fraction of 70 to 85% calculated by Equation 1 below:
[Equation 1]
Gel fraction (%) = W2/W1ⅹ100
(In Equation 1, W1 is the initial weight of the adhesive layer, and W2 is the weight measured after immersing the adhesive layer in ethyl acetate at room temperature for 3 days and drying it at 120°C for 24 hours).
delete The adhesive sheet according to claim 1, wherein the polar functional group includes a hydroxy group, an amide group, or an amine group.
delete The adhesive sheet of claim 1, wherein the crosslinking agent includes an isocyanate-based compound or an aziridine-based compound.
The adhesive sheet of claim 1, wherein the content of the crosslinking agent is 0.05 to 3 parts by weight based on 100 parts by weight of the acrylic copolymer.
The adhesive sheet of claim 1, wherein the adhesive composition further includes an ionic antistatic agent and a silane coupling agent.
The adhesive sheet of claim 11, wherein the ionic antistatic agent includes an ionic solid having a melting point of 20 to 50°C.
The adhesive sheet of claim 11, wherein the adhesive composition includes 0.01 to 5 parts by weight of the ionic antistatic agent and 0.01 to 2 parts by weight of the silane coupling agent, based on 100 parts by weight of the acrylic copolymer.
An optical film comprising the adhesive sheet according to claim 1.
The optical film of claim 14, further comprising an anti-reflection layer disposed on a lower surface of the base film.
An image display device comprising the adhesive sheet according to claim 1.