WO2023008747A1 - Adhesive sheet, and optical film and image display device comprising same - Google Patents

Abstract

The present invention relates to an adhesive sheet and, more specifically, to an adhesive sheet comprising a substrate film having a predetermined range of water contact angle and an adhesive layer disposed on the substrate film. The present invention may provide an optical film having a high degree of adhesion between a substrate film and an adhesive layer, and having improved adhesion durability and reliability even in harsh conditions (for example, high temperature, high humidity, and the like).

Description

Adhesive sheet, optical film and image display device including the same

The present invention relates to a pressure-sensitive adhesive sheet, and an optical film and an image display device including the same. 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 an image display device including the pressure-sensitive adhesive sheet.

For example, an adhesive or a pressure-sensitive adhesive sheet may be used 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. The pressure-sensitive adhesive needs to have improved transparency and high adhesive strength so as not to degrade the optical properties of the image display device.

Recently, a flexible display capable of being folded or bent has been widely used, and a display capable of operating under harsh conditions of high temperature/high humidity or external physical impact is being actively researched. Accordingly, the structure coupled to the display is also designed to have appropriate elasticity, flexibility and durability.

Therefore, the pressure-sensitive adhesive or the pressure-sensitive adhesive sheet used for joining the structure needs to be formed to prevent the structure from falling off or peeling 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.

One object of the present invention is to provide a pressure-sensitive adhesive sheet having improved adhesion properties and durability.

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

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

When the upper surface of the pressure-sensitive adhesive layer is 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 pressure-sensitive adhesive layer, the moving distance (d ₁ ) of the pressure-sensitive adhesive layer in the one direction is 15 mm Below, the adhesive sheet.

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

3. The pressure-sensitive adhesive sheet according to 1 above, wherein the base film has a water contact angle of 40° to 45°.

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

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

[Equation 1]

Gel fraction (%) = W2/W1×100

(In Equation 1, W1 is the initial weight of the pressure-sensitive adhesive layer, and W2 is the weight measured after immersing the pressure-sensitive adhesive layer in ethyl acetate at room temperature for 3 days and drying 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 including a (meth)acrylate monomer, a (meth)acrylic acid monomer, and a crosslinkable monomer having a polar functional group.

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

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

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

11. The pressure-sensitive adhesive sheet according to 1 above, wherein the pressure-sensitive adhesive composition further comprises an ionic antistatic agent and a silane coupling agent.

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

13. The adhesive sheet according to 11 above, wherein the pressure-sensitive adhesive composition comprises 0.01 part by weight to 5 parts by weight of the ionic antistatic agent and 0.01 part by weight 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 the pressure-sensitive adhesive sheet according to 1 above.

15. The optical film according to 14 above, further comprising an antireflection layer disposed on a lower surface of the base film.

16. An image display device including the pressure-sensitive adhesive sheet according to 1 above.

The pressure-sensitive adhesive sheet according to exemplary embodiments has high adhesion between the base film and the pressure-sensitive adhesive layer, and may have improved adhesion durability and reliability even under harsh conditions of high temperature/high humidity. For example, the pressure-sensitive adhesive sheet may include a base film having a predetermined surface roughness, and a pressure-sensitive adhesive layer having a low moving distance (d ₁ ) when a predetermined external force is applied on the base film.

As the pressure-sensitive adhesive sheet according to exemplary embodiments does not require a saponification process of the base film, the ease and simplicity of the process may be improved. In addition, contamination of the adhesive sheet due to the saponification step can be prevented.

In addition, the adhesive sheet according to exemplary embodiments has high adhesiveness and adhesion, and may be applied to bonding various structures of a flexible display to maintain improved adhesive durability even in repeated folding and bending operations.

1 is a schematic cross-sectional view illustrating an adhesive sheet according to exemplary embodiments.

2A and 2B are exemplary cross-sectional views for explaining the moving distance (d ₁ ) of the pressure-sensitive adhesive layer on the base film according to the repeated load on the upper surface of the pressure-sensitive adhesive layer.

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

Embodiments of the present invention provide a pressure-sensitive adhesive sheet including a base film having a water contact angle within a predetermined range and a pressure-sensitive adhesive layer disposed on one surface of the base film. For example, the pressure-sensitive adhesive layer may be formed from a pressure-sensitive adhesive composition containing an acrylic copolymer.

When the pressure-sensitive adhesive layer is reciprocally loaded at a predetermined pressure and a predetermined speed in one direction parallel to the one surface of the base film, a moving distance (d ₁ ) in the one direction may be small. Accordingly, adhesion between the base film and the pressure-sensitive adhesive layer may be high, and a pressure-sensitive adhesive sheet having improved durability and bending characteristics even under severe conditions such as high temperature and high humidity may be provided.

Hereinafter, the present invention will be described in detail.

<Adhesive composition and adhesive sheet>

With reference to the following drawings, 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 together with the contents of the above-described invention, so the present invention is described in such drawings should not be construed as limited to

1 is a schematic cross-sectional view illustrating an adhesive sheet according to exemplary embodiments.

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

According to exemplary embodiments, the pressure-sensitive adhesive layer 120 may be formed from a pressure-sensitive adhesive composition including an acrylic copolymer, a crosslinking agent, an ionic antistatic agent, and a silane coupling agent. For example, the pressure-sensitive adhesive layer 120 may include a cured product of the pressure-sensitive 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 herein, the term "(meth)acrylate" is used to encompass either acrylate or methacrylate. As used herein, the term "(meth)acrylic acid" is used to encompass either 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, t-butyl (meth) acrylate, pentyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate or lauryl (meth) acrylate, etc. can be heard 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, based on the total weight of the polymerizable compound. When the content of the (meth)acrylate monomer is less than 80% by weight, the crosslinking density and adhesion of the pressure-sensitive adhesive composition may decrease. When the content of the (meth)acrylate monomer is greater than 99% by weight, the cohesive force of the pressure-sensitive adhesive composition is lowered, and thus durability of the pressure-sensitive adhesive layer may be deteriorated.

The (meth)acrylic acid monomer may serve to impart adhesiveness to the pressure-sensitive adhesive composition. For example, as the acrylic copolymer has an acidic group derived from a (meth)acrylic acid monomer in its side chain, the adhesiveness and crosslinking degree of the pressure-sensitive adhesive composition may be improved.

However, the (meth)acrylic acid monomer imparts hydrophilicity to the pressure-sensitive adhesive composition and may affect the surface migration of the ionic antistatic agent. In addition, as the crosslinking agent to be described later reacts with an acidic group derived from (meth)acrylic acid and is consumed, the cohesive strength and adhesion of the pressure-sensitive adhesive layer may decrease.

In some embodiments, the amount 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 wt% to 1 wt%, preferably 0.05 wt% to 1 wt%, more preferably 0.1 wt% to 0.7 wt%, based on the total weight of the polymerizable compound. may be %. When the content of the (meth)acrylic acid monomer is less than 0.01% by weight, the adhesive strength of the pressure-sensitive adhesive composition may decrease. When the content of the (meth)acrylic acid monomer is greater than 1% by weight, the adhesive strength may be excessively increased and reworkability may be deteriorated, and durability may be deteriorated by affecting the transfer of the ionic antistatic agent to the surface.

The crosslinkable monomer has a polar functional group, and may impart cohesive force and adhesive strength to the pressure-sensitive adhesive layer. For example, the polar functional group may be a hydroxyl 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 hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Rate, 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, 2-hydroxypropylene glycol (meth)acrylate, hydroxyalkylene having 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-hydroxy Roxynonyl vinyl ether, 10-hydroxydecyl vinyl ether, etc. are mentioned.

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

As examples of the amine group-containing monomer, N, N- (dimethylamino) ethyl (meth) acrylate, N, N- (diethylamino) ethyl (meth) acrylate, N, N- (dimethylamino) propyl ( meta) acrylate; and the like.

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

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. When the content of the crosslinkable monomer is less than 0.05% by weight, the cohesive force of the pressure-sensitive adhesive composition is reduced, and thus durability may be deteriorated. When the content of the crosslinkable monomer exceeds 10% by weight, the adhesive strength and durability may decrease as the gel fraction of the pressure-sensitive adhesive composition becomes excessively high.

In some embodiments, in addition to the above monomers, other polymerizable monomers known in the art do not reduce the adhesiveness, for example, 10 parts by weight or less out of 100 parts by weight of the total monomers used in the preparation of the acrylic copolymer. More may be included.

The method for producing the acrylic copolymer is not particularly limited, and may be prepared using methods such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization commonly used in the art, preferably using a solution polymerization method. It can be manufactured by In addition, solvents, polymerization initiators, and chain transfer agents for molecular weight control, which are commonly used during polymerization, may be used.

In some embodiments, the weight average molecular weight (polystyrene equivalent, Mw) of the acrylic copolymer may be 50,000 g/mol to 2,000,000 g/mol, preferably 400,000 g/mol to 2,000,000 g/mol. . For example, the weight average molecular weight can be measured by gel permeation chromatography (GPC). When the weight average molecular weight of the acrylic copolymer is less than 50,000 g/mol, cohesive strength between the copolymers may be insufficient and adhesion durability may be deteriorated. 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 may improve cohesion, adhesion, and high-temperature reliability of the pressure-sensitive adhesive, and may serve to maintain the shape of the pressure-sensitive adhesive. For example, the crosslinking agent may react with a crosslinkable functional group derived from the crosslinkable monomer to improve cohesive strength and durability of the pressure-sensitive adhesive. In addition, the crosslinking agent may react with a polar functional group (eg, a carboxyl group) on the surface of the base film 110 to improve adhesion of the pressure-sensitive adhesive layer 120 to the substrate.

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. The isocyanate-based compound and the aziridine-based compound have high reactivity to polar functional groups and may have high adhesion to a corona discharge-treated or plasma-treated base film.

Examples of the isocyanate-based compound 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 obtained by self-condensation of 3 equivalents of a diisocyanate compound, 2 out of 3 equivalents of a diisocyanate compound Diisocyanate obtained from the equivalent biuret body obtained by condensation of 1 equivalent of diisocyanate with urea, polyfunctional isocyanate compounds containing three functional groups such as triphenylmethane triisocyanate and methylene bistriisocyanate. These may be used alone or in combination of two or more. More preferably, the crosslinking agent may include xylene diisocyanate, and in this case, durability and adhesion to a substrate may be further improved.

Examples of the aziridine-based compound 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 alone Alternatively, two or more may be used in combination.

In some embodiments, the content of the crosslinking agent may be 0.05 parts by weight to 3 parts by weight, preferably 0.1 parts by weight to 2 parts by weight, based on 100 parts by weight of the acrylic copolymer. When the content of the crosslinking agent is less than 0.05 parts by weight, cohesive strength is lowered due to an insufficient crosslinking degree, and thus adhesive durability and cutting properties may be deteriorated. When the content of the crosslinking agent exceeds 3 parts by weight, a crosslinking reaction may occur excessively, resulting in increased residual stress and reduced adhesion to the base film 110 .

The ionic antistatic agent may include an ionic salt composed of anions and cations, and may impart ionic conductivity to the pressure-sensitive adhesive layer 120 . For example, the surface resistivity of the pressure-sensitive adhesive layer 120 may be 6×10 ¹⁰ Ω/□ or less, 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, preferably an ionic solid.

As the ionic antistatic agent includes the ionic solid, stability of the pressure-sensitive adhesive composition over time and durability of the pressure-sensitive adhesive layer 120 may be improved. In addition, the ionic solid has high compatibility with the above-mentioned other components and can maintain high transparency of the pressure-sensitive adhesive composition.

In some embodiments, the melting point of the ionic solid may be between 20°C and 50°C. In this case, since the mobility of the ionic solid is minimized, durability and reliability of the adhesive sheet may be improved. 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 the antireflection film and be eluted.

In some embodiments, the ionic solid is Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , AlCl ₇ ^- , BF ₄ ^- , PF ₆ ^- , ClO ₄ ^- , NO ₃ ^- , CO ₃ ² as an anion. ^- , 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); and the like.

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

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°C to 80°C), 1- Butyl-1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-imidazolium hexafluorophosphate (melting point 120 ℃ to 121 ℃), 1-ethyl-3-methylimidazolium bromide (melting point 74 ℃), 1-ethyl-3-methylimidazolium chloride (melting point 80 ℃ to 84 ℃), 1-ethyl-3-methylimida Zolium hexafluorophosphate (melting point 61°C), 1-ethyl-3-methylimidazolium iodide (melting point 79°C), 1-ethyl-2,3-dimethylimidazolium chloride (melting point 181°C), 1 -methylimidazolium chloride (melting point 75°C), 1,2,3-trimethylimidazolium methyl sulfate (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 tetrafluoro Borate (melting point 77 degreeC) etc. are mentioned.

As an example of the pyridinium salt, 1-butyl-3-methylpyridinium bromide (melting point 43 ° C.), 1-butyl-4-methylpyridinium bromide (melting point 137 ° C.), 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 °C), etc.

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 methylsulfate (melting point 62°C), tetrabutylammonium bis(trifluoromethylsulfonyl)imide (melting point 94°C to 96°C), tetraethylammonium trifluoromethanesulfonate (melting point 161-163 ℃), tetrabutylammonium benzoate (melting point 64 ℃ to 67 ℃), tetrabutylammonium methane sulfate (melting point 78 ℃ to 80 ℃), tetrabutylammonium nonafluorobutanesulfonate (melting point 50 ℃ to 53 ℃), tetra -n-butylammonium hexafluorophosphate (melting point 246°C), tetrabutylammonium trifluoroacetate (melting point 74°C to 76°C), tetrahexylammonium tetrafluoroborate (melting point 90°C to 92°C), 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°C to 91°C), tetrapentylammonium bromide (melting point: 99°C), and n-hexadecyltrimethylammonium hexafluorophosphate (melting point: 185°C).

As examples of the alkylpyrrolidium salt, 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 Lithium tetrafluoroborate (melting point 152 degreeC) etc. are mentioned.

Examples of the alkylphosphonium salt include tetrabutylphosphonium bromide (melting point: 104° C.), tetrabutylphosphonium chloride (melting point: 62° C. to 66° C.), tetrabutylphosphonium tetrafluoroborate (melting point: 96° C. to 99° C.), Tetrabutylphosphonium methanesulfonate (melting point 59°C to 62°C), tetrabutylphosphonium p-toluenesulfonate (melting point 54°C to 57°C), tributylhexadecylphosphonium bromide (melting point 57°C to 62°C), etc. can be heard

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

In some embodiments, the amount of the ionic antistatic agent may be 0.01 parts by weight to 5 parts by weight based on 100 parts by weight of the acrylic copolymer. When the content of the ionic antistatic agent is less than 0.01 parts by weight, the antistatic properties of the pressure-sensitive adhesive layer may be low, and when the content of the ionic antistatic agent exceeds 5 parts by weight, the ionic antistatic agent may be precipitated, and the pressure-sensitive adhesive layer durability may deteriorate.

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

Examples of the silane coupling agent include vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 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-isocyanatepropyltri Ethoxysilane etc. are 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 part by weight to 3 parts by weight, preferably 0.01 part by weight to 2 parts by weight, based on 100 parts by weight of the acrylic copolymer. Within the above range, durability and adhesion of the pressure-sensitive adhesive sheet may be improved.

The pressure-sensitive adhesive composition may further include conventional additives known in the art in order to adjust adhesive force, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. required according to use. For example, tackifiers, antioxidants, corrosion inhibitors, leveling agents, surface lubricants, dyes, pigments, antifoaming agents, fillers, light stabilizers, plasticizers, and the like may be included.

The pressure-sensitive adhesive layer 120 may be formed by applying the above-described pressure-sensitive adhesive composition on one surface of the base film 110 and performing a drying and/or curing process. For example, the pressure-sensitive adhesive layer 120 may be formed by applying the pressure-sensitive adhesive composition on the base film 110 by 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 pressure-sensitive adhesive layer 120 may be 70% to 85%, preferably 70% to 80%. The gel fraction of the pressure-sensitive adhesive layer 120 can be calculated by Equation 1 below.

[Equation 1]

Gel fraction (%) = W2/W1×100

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

When the gel fraction of the pressure-sensitive adhesive layer 120 is less than 70%, durability and reworkability over time may be deteriorated due to a decrease in crosslinking and cohesion. When the gel fraction of the pressure-sensitive adhesive layer exceeds 85%, durability and adhesion of the pressure-sensitive adhesive layer 120 may be deteriorated due to excessive crosslinking, and damage to the object may occur when the pressure-sensitive 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 pressure-sensitive adhesive layer 120 is disposed with respect to deionized water (DIW) may be 40° to 65°. 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 surface of the base film 110 under conditions of 23° C. and 50% RH.

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

2A and 2B are exemplary cross-sectional views for explaining the moving distance d ₁ of the pressure-sensitive adhesive layer 120 by an external force on the base film 110 .

2A is an exemplary cross-sectional view for explaining an initial state of the pressure-sensitive adhesive sheet, and FIG. 2B is an exemplary cross-sectional view for explaining a state of the pressure-sensitive adhesive sheet after repeated loading.

According to exemplary embodiments, the pressure-sensitive adhesive layer 120 may be 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 120 in the one direction. The movement distance (d ₁ ) may be 15 mm or less. Preferably, the moving distance (d ₁ ) of the pressure-sensitive adhesive layer 120 on one surface of the base film 110 may be greater than 0 mm and less than or equal to 15 mm.

For example, the movement distance (d ₁ ) of the pressure-sensitive adhesive layer 120 may refer to a distance that the pressure-sensitive adhesive layer 120 moves in one direction from the initial state of the pressure-sensitive adhesive sheet.

Specifically, the moving distance (d ₁ ) is determined by fixing the entire surface of the base film 110 on the opposite side to which the pressure-sensitive adhesive layer 120 is attached to a SUS304 plate through a double-sided adhesive tape, and then fixing the upper surface of the pressure-sensitive adhesive layer 120. The maximum distance that the pressure-sensitive adhesive layer 120 moved can be measured by reciprocating the elastic rubber 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 pressure-sensitive adhesive layer 120.

When the moving distance (d ₁ ) of the pressure-sensitive adhesive layer 120 on the base film 110 is within the above range, adhesion and adhesiveness between the pressure-sensitive adhesive layer 120 and the base film 110 may be improved. Accordingly, the adhesive durability of the adhesive sheet may be increased, and, for example, lifting or peeling between structures in the image display device may be prevented.

For example, in the case of a pressure-sensitive adhesive sheet having a hydrophobic surface, adhesion and adhesive strength of the pressure-sensitive adhesive to the substrate may deteriorate. In this case, in order to improve the adhesion between the substrate and the pressure-sensitive adhesive, a pretreatment process of saponification by immersing the surface of the substrate in an aqueous alkali solution may be performed, or a separate coating layer may be formed between the substrate and the pressure-sensitive adhesive.

However, when the saponification process is performed or a separate coating layer is formed, the yield of the pressure-sensitive adhesive sheet may be lowered as the process becomes complicated, and contamination and quality deterioration of the pressure-sensitive adhesive sheet may occur due to additional processes.

In the pressure-sensitive adhesive sheet according to exemplary embodiments, as the pressure-sensitive adhesive layer 120 includes a cured product of the pressure-sensitive adhesive composition described above, one side of the base film 110 on which the pressure-sensitive adhesive layer 120 is disposed has an angle of 40° to 65°. Even with a water contact angle, adhesion between the base film 110 and the pressure-sensitive adhesive layer 120 may be high.

Accordingly, the adhesion and adhesiveness between the base film 110 and the pressure-sensitive adhesive layer 120 can be improved even if a separate coating layer, for example, an anchor layer, is not included on the bonding surface between the base film 110 and the pressure-sensitive adhesive layer 120. can In addition, 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 surface of the base film 110 may be 10 nm to 100 nm, preferably 20 nm to 60 nm. The surface roughness can be measured using an atomic force microscope (AFM).

For example, the pressure-sensitive adhesive layer 120 may be formed by applying the pressure-sensitive adhesive composition to one surface of the base film 110 having the above-described surface roughness and curing the pressure-sensitive adhesive composition. The surface roughness may increase the surface area of the base film. In this case, as the pressure-sensitive adhesive composition is introduced into the curves or irregularities of the surface of the base film 110 and cured, adhesion between the base film 110 and the pressure-sensitive adhesive layer 120 may be improved.

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

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 pressure-sensitive adhesive composition, and thus, the crosslinking density, cohesive force, and adhesion of the pressure-sensitive adhesive layer 120 to the base film 110 may be further improved.

According to exemplary embodiments, the base film 110 may include acrylic, cellulose, polyolefin, or polyester. In this case, transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and the like of the base film 110 may be improved.

For example, the base film 110 may include acrylic resins such as polymethyl (meth)acrylate and polyethyl (meth)acrylate; polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate; cellulosic resins such as diacetyl cellulose, triacetyl cellulose, and cellulose acetate butylene; and polyolefin-based resins such as polyethylene, polypropylene, cycloolefin, polyolefin having a norbornene structure, and ethylene-propylene copolymer.

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

For example, the pressure-sensitive adhesive sheet may be provided in a form in which the base film 110 and the release film are attached to both sides of the pressure-sensitive adhesive layer 120 . In this case, the release film formed on one surface of the pressure-sensitive adhesive layer 120 may be removed and the exposed surface of the pressure-sensitive 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 upper surface of the base film 110, and an optical function layer 130 disposed on the lower surface of the base film. can

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

In some embodiments, the optical function layer 130 may include an antireflection layer, a hard coating layer, a retardation layer, or a polarizer. For example, the optical film may be provided as an antireflection film, a hard coating film, a window film, a retardation film, or a 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 pressure-sensitive adhesive layer 120 that does not contact the base film 110 . For example, the optical film may be provided in a form in which the base film 110 and the release film are attached to both sides of the pressure-sensitive adhesive layer 120 . In this case, the release film formed on one surface of the pressure-sensitive adhesive layer 120 may be removed and the exposed surface of the pressure-sensitive 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 an upper surface of the display panel via the pressure-sensitive adhesive layer 120 . For example, an image display device may be provided by removing the release film from the optical film and then attaching the exposed pressure-sensitive adhesive layer 120 to a 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 components known in the art in addition to the above configurations. For example, a retardation film, a hard coating film, a protective film, a window film, a touch panel, and the like may be further included. The components may be adhered to each other by the pressure-sensitive adhesive composition according to exemplary embodiments.

As described above, as the adhesion and bonding between the base film 110 and the pressure-sensitive adhesive layer 120 is improved, durability and stability may be improved. Therefore, the adhesiveness of the image display device can be maintained for a long period of time even under physical external force such as repetitive bending or folding or under severe conditions of high temperature and high humidity, and breakage, peeling, and lifting of structures can be prevented.

Hereinafter, experimental examples including specific examples and comparative examples are presented to aid understanding of the present invention, but these are only illustrative of the present invention and do not limit the scope of the appended claims, and 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 these changes and modifications fall within the scope of the appended claims.

manufacturing example

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

98 parts by weight of n-butyl acrylate (BA), 0.5 parts by weight of acrylic acid (AA), 2-hydroxyethyl methacrylate (2-HEMA ) After adding the monomer mixture consisting of 1.5 parts by weight, 100 parts by weight of ethyl acetate (EAc) was added as a solvent. Thereafter, nitrogen gas was introduced for 1 hour to remove oxygen, followed by substitution, and the temperature was maintained at 62°C. After uniformly mixing the mixture, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours to prepare an acrylic copolymer (weight average molecular weight of about 1.3 million).

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

98.1 parts by weight of n-butyl acrylate (BA), 0.3 parts by weight of acrylic acid (AA), 2-hydroxyethyl methacrylate (2-HEMA ) After adding the monomer mixture consisting of 1.6 parts by weight, 100 parts by weight of ethyl acetate (EAc) was added as a solvent. Thereafter, nitrogen gas was introduced for 1 hour to remove oxygen, followed by substitution, and the temperature was maintained at 80°C. After uniformly mixing the mixture, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours to prepare an acrylic copolymer (weight average molecular weight of about 1.3 million).

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

97 parts by weight of n-butyl acrylate (BA), 1.5 parts by weight of acrylic acid (AA), 2-hydroxyethyl methacrylate (2-HEMA ) After adding the monomer mixture consisting of 1.5 parts by weight, 100 parts by weight of ethyl acetate (EAc) was added as a solvent. Thereafter, nitrogen gas was introduced for 1 hour to remove oxygen, followed by substitution, and the temperature was maintained at 80°C. After uniformly mixing the mixture, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours to prepare an acrylic copolymer (weight average molecular weight of about 1.3 million).

Preparation Example 4: Preparation of TAC film

A triacetyl cellulose (TAC) film was prepared. The TAC film was subjected to corona discharge treatment 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. When the corona discharge treatment was performed, it was indicated by “○”, and when the corona discharge treatment was not performed, it was indicated by “×”. Saponification treatment was not performed.

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) Measurement of water contact angle

0.1 ml of deionized water (DIW) was dropped on the surface of the TAC film at 23° C. and 50% RH, and after 5 seconds, the contact angle of water was measured using a contact angle measuring instrument (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 pressure-sensitive adhesive composition

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

(2) Manufacture of adhesive sheet

The prepared pressure-sensitive adhesive composition was applied onto a release film coated with a silicone release agent and dried at 100° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 20 μm. A pressure-sensitive adhesive sheet was prepared by bonding the prepared TAC film onto the formed pressure-sensitive adhesive layer.

division (parts by weight)	adhesive composition				TAC film (E)
	Acrylic Copolymer (A)	cross-linking 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 (parts by weight)	adhesive composition				TAC film (E)
	Acrylic Copolymer (A)	cross-linking 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 component names listed in Tables 2 and 3 are as follows.

Acrylic Copolymer (A)

A-1: Copolymer prepared in Preparation Example 1

A-2: Copolymer prepared in Preparation Example 2

A-3: Copolymer prepared in Preparation Example 3

Crosslinking agent (B)

B-1: Coronate-HXR (manufactured by Nippon Polyurethane Industry)

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

B-3: CL-427 (manufactured 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)

The TAC film described in Table 1 above

Experimental example

(1) Measurement of movement distance when external force is applied

The prepared pressure-sensitive adhesive sheet was cut into a size of 25 mm in length x 50 mm in width, and attached to the SUS304 plate through a double-sided adhesive tape (width: 25 mm, light receiving thread) on the surface of the TAC film. Thereafter, by using elastic rubber (Neoprene rubber, Kouda), the upper surface of the pressure-sensitive adhesive layer is applied 20 times in a direction parallel to the upper surface of the pressure-sensitive adhesive layer at a pressure of 1 MPa and a speed of 0.1 m/s in a length (25 mm) direction. round trip At this time, the moving distance (d ₁ ) was measured by measuring the distance that the pressure-sensitive adhesive layer was pushed on the TAC film.

(2) Evaluation of durability (heat resistance, moist heat resistance)

After cutting the prepared adhesive sheet into a length of 200 mm × 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 treated with an autoclave (50 ° C × 30 min 0.5 mm). MPa) to prepare a specimen. At this time, the applied pressure was 5 kg/cm 2 , and clean room work was performed to prevent bubbles or foreign matter from occurring.

To evaluate heat resistance, the specimen was left at a temperature of 80° C. for 1000 hours, and then whether bubbles or peeling occurred was observed. To evaluate heat and moisture resistance, the specimen was left for 1000 hours under conditions of 60° C. and 90% RH, and then the occurrence of bubbles or peeling was observed. At this time, immediately before evaluating the state of the specimen, it was observed after leaving it at room temperature for 24 hours. The evaluation criteria are as follows.

<Evaluation Criteria>

ⓞ: No bubbles or peeling

○: Bubbles or exfoliation < 5

△: 5 ≤ bubbles or peeling < 10

×: 10 ≤ bubbles or peeling

(3) Adhesion evaluation

The prepared adhesive sheet was cut into a length of 25 mm × width of 100 mm, the release film was peeled off, the exposed adhesive layer was attached to a glass substrate, and an autoclave treatment (50 ° C × 30 minutes, 0.5 MPa) was performed to prepare a specimen.

In order to measure the room temperature adhesive force, the prepared specimen was left for 24 hours under conditions of 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 peel speed of 300 mm/min and a peel angle of 180 ^° , and the adhesive strength at room temperature was measured.

For the measurement of adhesive strength by heating, the prepared specimen was left for 48 hours under conditions of a temperature of 50° C. and 50% RH. Thereafter, the adhesive sheet was peeled from the glass substrate at a peel rate of 300 mm/min and a peel angle of 180 ^° using a universal tensile tester (UTM, manufactured by Instron) under conditions of 23 ° C. was measured.

(4) Gel fraction evaluation

About 0.25 g of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was applied to a precisely weighed 250-mesh wire mesh (100 mm × 100 mm), and wrapped so as not to leak the gel powder. 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 then weighed. The gel fraction was calculated by Equation 1 below using the measured weight.

[Equation 1]

Gel fraction (%) = (C-A)/(B-A) × 100

In the formula, A is the weight of the wire mesh, B is the weight of the wire mesh to which the adhesive layer is attached, and C is the weight of the wire mesh dried after immersion. Therefore, (B-A) means the initial weight of the pressure-sensitive adhesive layer, and (C-A) means the weight of the pressure-sensitive adhesive layer dried after immersion.

The results are shown together in Table 4 and Table 5 below.

division	travel distance (mm)	durability		Adhesion (N/25mm)		gel fraction (%)
		heat resistance	Moist heat resistance	room temperature adhesion	Heated 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	travel distance (mm)	durability		Adhesion (N/25mm)		gel fraction (%)
		heat resistance	Moist heat resistance	room temperature adhesion	Heated 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

As the pressure-sensitive adhesive sheet according to the above-described embodiments has a moving distance (d ₁ ) of the pressure-sensitive adhesive layer on the untested TAC film of 15 mm or less, it can be confirmed that durability and heat resistance of the pressure-sensitive adhesive sheet are improved. For example, since the pressure-sensitive adhesive layer has high adhesion even to an untested TAC film, breakage, cutting, and peeling of the pressure-sensitive adhesive sheet can be suppressed.

However, the adhesive sheet according to Comparative Examples did not substantially exhibit adhesion of the adhesive layer to the untested TAC film, and thus, durability and heat resistance were reduced.

Claims (16)

1. A base film having a water contact angle of 40° to 65°; and

   It is disposed on the upper surface of the base film and includes a pressure-sensitive adhesive layer containing a cured product of a pressure-sensitive adhesive composition containing an acrylic copolymer and a crosslinking agent,

   When the upper surface of the pressure-sensitive adhesive layer is 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 pressure-sensitive adhesive layer, the moving distance (d ₁ ) of the pressure-sensitive adhesive layer in the one direction is 15 mm Below, the adhesive sheet.
2. The pressure-sensitive adhesive sheet according to claim 1, wherein the surface roughness (Ra) of the upper surface of the base film is 10 nm to 100 nm.
3. The pressure-sensitive adhesive sheet according to claim 1, wherein the base film has a water contact angle of 40° to 45°.
4. The pressure-sensitive adhesive sheet according to claim 1, wherein the base film is corona discharge treated or plasma treated.
5. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer has a gel fraction of 70% to 85% calculated by Equation 1 below:

   [Equation 1]

   Gel fraction (%) = W2/W1×100

   (In Equation 1, W1 is the initial weight of the pressure-sensitive adhesive layer, and W2 is the weight measured after immersing the pressure-sensitive adhesive layer in ethyl acetate at room temperature for 3 days and drying at 120 ° C. for 24 hours).
6. The pressure-sensitive adhesive sheet according to claim 1, wherein the acrylic copolymer is 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.
7. The pressure-sensitive adhesive sheet according to claim 6, wherein the polar functional group includes a hydroxyl group, an amide group, or an amine group.
8. The pressure-sensitive adhesive sheet of claim 6, 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 pressure-sensitive adhesive sheet according to claim 1, wherein the crosslinking agent includes an isocyanate-based compound or an aziridine-based compound.
10. The pressure-sensitive adhesive sheet of claim 1, wherein the amount of the crosslinking agent is 0.05 parts by weight to 3 parts by weight based on 100 parts by weight of the acrylic copolymer.
11. The pressure-sensitive adhesive sheet of claim 1, wherein the pressure-sensitive adhesive composition further comprises an ionic antistatic agent and a silane coupling agent.
12. The pressure-sensitive adhesive sheet of claim 11, wherein the ionic antistatic agent comprises an ionic solid having a melting point of 20°C to 50°C.
13. The pressure-sensitive adhesive sheet of claim 11 , wherein the pressure-sensitive adhesive composition comprises 0.01 part by weight to 5 parts by weight of the ionic antistatic agent and 0.01 part by weight 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 the pressure-sensitive adhesive sheet according to claim 1 .
15. The optical film according to claim 14 , further comprising an antireflection layer disposed on a lower surface of the base film.
16. An image display device comprising the adhesive sheet according to claim 1.

Images