KR20170120848A - Adhesive film, optical member comprising the same and optical display apparatus comprising the same - Google Patents

Abstract

The present invention provides an adhesive film, an optical member including the same, and an optical display device including the same. The adhesive film has a thickness of 10-200 micrometers and includes a hydroxyl (meth) acrylic copolymer, and a variation of dynamic stability is not more than 10%. The provided adhesive film is hardly deformed even after being folded many times. The provided adhesive film has excellent curvature reliability at a low temperature or high temperature/humidity.

Description

TECHNICAL FIELD [0001] The present invention relates to an adhesive film, an optical member including the adhesive member, and an optical display device including the adhesive member. [0002]

The present invention relates to an adhesive film, an optical member including the same, and an optical display device including the same.

The optical display device includes a display element including a window film, a conductive film, and an organic light emitting element. A touch pad has a structure in which a transparent clear adhesive (OCA) is laminated between a window film and a conductive film. The touch pad is operated by a signal generated by changing the capacitance due to contact of a window film of a human hand or a predetermined object or the like. The transparent adhesive film may be laminated between two kinds of window films, conductive films, polarizing plates and organic light emitting devices.

In recent years, a flexible display device having flexibility that can be folded and unfolded in an optical display device has been developed. The flexible display device can be folded and unfolded, so that it can be manufactured in various forms, and is thin, light and strong against impact.

Flexible display devices require that the various optical elements included in the apparatus have flexibility. Since the transparent pressure-sensitive adhesive film is formed between the window film and the conductive film, the adhesive force of both sides must be excellent. In order to be used in a flexible display device, the folding property should be good. In addition, the bending reliability should be excellent not to cause bubble generation or delamination in various temperature ranges, for example, at room temperature but also in repeated folding at low temperature or high temperature and high humidity.

The background art of the present invention is disclosed in Korean Patent Publication No. 2007-0055363.

A problem to be solved by the present invention is to provide an adhesive film with less deformation of an adhesive film even if folding is repeated several times.

Another problem to be solved by the present invention is to provide an adhesive film excellent in bending reliability at low temperature or high temperature / high humidity.

Another object of the present invention is to provide a pressure-sensitive adhesive film having good foldability over a wide temperature range.

Another object to be solved by the present invention is to provide an adhesive film excellent in peel strength and excellent in optical transparency.

Another object of the present invention is to provide an optical member and an optical display device including the adhesive film.

The pressure-sensitive adhesive film of the present invention has a thickness of 10 탆 to 200 탆 and includes a hydroxyl group-containing (meth) acrylic copolymer, and the change in restitution force of the following formula 1 may be 10% or less:

<Formula 1>

Variation of restitution force = P ¹ - P ²⁰

(In the above-mentioned formula 1, P ¹ and P ²⁰ are as defined in the detailed description of the present invention).

The optical member of the present invention may include an optical film and an adhesive film of the present invention formed on at least one side of the optical film.

The optical display device of the present invention may include the above-mentioned pressure-sensitive adhesive film.

INDUSTRIAL APPLICABILITY The present invention provides an adhesive film with less deformation of an adhesive film even when folding is repeated several times.

INDUSTRIAL APPLICABILITY The present invention provides an adhesive film excellent in bending reliability at low temperature or high temperature / high humidity.

The present invention provides a pressure-sensitive adhesive film having good foldability even under a wide temperature range.

The present invention provides an adhesive film excellent in peel strength and excellent in optical transparency.

The present invention provides an optical member and an optical display device including the pressure-sensitive adhesive film.

1 is a sectional view and a plan view of a specimen for measuring the restoring force.
2 is a graph for calculating the restoring force.
3 is a cross-sectional view of an optical display device according to an embodiment of the present invention.
4 is a conceptual diagram of a specimen for peel strength measurement.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

The terms "upper" and "lower" in this specification are defined with reference to the drawings, wherein "upper" may be changed to "lower", "lower" What is referred to as "on" may include not only superposition, but also intervening other structures in the middle. On the other hand, what is referred to as "directly on" or "directly above"

As used herein, "(meth) acrylic" may mean acrylic and / or methacrylic. As used herein, "copolymer" may include oligomers, polymers or resins.

In this specification, the "modulus" of the pressure-sensitive adhesive film is a storage modulus (G '), and a plurality of pressure-sensitive adhesive films are laminated and perforated to prepare specimens having a thickness of 500 μm and a diameter of 8 mm, and a shear rate of 1 rad / strain was carried out by using a jig of 8 mm under the condition that a load of 300 gf was applied to the specimen and the temperature was raised at a rate of 5 ° C / min at -60 ° C to 90 ° C. The modulus was determined at 25 캜 and 80 캜, respectively.

As used herein, the term "good folding" means that there is no streaking at the folding site during folding, no cracking, peeling, peeling, or cracking of the PET film.

The "average particle size" of the organic nanoparticles in the present specification is a particle size which is expressed by a Z-average value measured by a Zetasizer nano-ZS instrument of Malvern in an aqueous or organic solvent and confirmed by SEM / TEM observation.

Hereinafter, an adhesive film according to an embodiment of the present invention will be described.

The adhesive film according to the present embodiment may have a restitution change amount of 10% or less in the following formula 1:

<Formula 1>

Variation of restitution force = P ¹ - P ²⁰

(Length x length, 20 mm x 20 mm) of the first PET film / second adhesive film (hereinafter referred to as &quot; first end portion / adhesive film &quot;) of the PET (polyethylene terephthalate) And a second end of the second PET film in the order of the first end, the second end, and the second end of the second PET film. The jig is fixed to both ends of the first PET film and the second PET film, and one jig is fixed at 10 MPa in the pull at 25 ℃ the other fixture at a speed of 300mm / min initial thickness (X ₀₎ (unit: ㎛) of the pressure-sensitive adhesive loaded with a (㎛ 10 times the thickness, X _2, unit) length of 1000% of the And the tensile strength of the adhesive film was increased to the length of 1000% of the thickness of the adhesive film when the extended length of the adhesive film was taken as X-axis and the force applied to the adhesive film as the Y-axis (300 mm / min) which is equal to the speed at which the adhesive film is pulled back, and a force of 0 kPa is applied to the adhesive film When said cycle to say,: the length of the increased pressure-sensitive adhesive film when X ₁ (㎛ units)

P ¹ is the value (unit:%) calculated by the following formula 2 after the cycle once,

P ²⁰ is a value (unit:%) calculated by the following formula 2 after repeating the cycle 20 times.

<Formula 2>

Resilience = (1 - (X ₁ ) / (X ₂ )) x 100.

1 (a) and 1 (b) are a cross-sectional view and a plan view, respectively, of one specific example of a specimen for measuring a restoring force, and FIGS. 1A and 1B show the amounts of PET (polyethylene terephthalate) films (length x width x thickness: 50 mm x 20 mm x 75 m) The end portions of the first PET film and the second PET film were adhered to each other by a pressure-sensitive adhesive film of a width x length (20 mm x 20 mm) (20 mm x 20 mm) of the contact area between the first PET film, the adhesive film, and the second PET film in the order of the second end of the second PET film. Fig. 2 is a graph when the stretched length of the adhesive film is measured on the X-axis and the force applied on the adhesive film is measured on the Y-axis. The initial thickness (X ₀ ) of the adhesive film may be 10 μm to 200 μm. The restoring force can be measured with TA.XT_Plus Texture Analyzer (Stable Micro System). The restoring force is measured by repeating the next cycle immediately without leaving the sample for a predetermined period between each cycle in the cycle repetition.

The restoring force can be restored to original state after the adhesive film is folded once, and the restoring force change amount can evaluate whether the adhesive film is reliable not only at room temperature but also at low temperature or high temperature / high humidity even when repeatedly folding at least twice. When the amount of change in the restoring force is 10% or less, the adhesive film can exhibit good bending reliability even in repetitive folding when used in a flexible optical display device, maintain the initial properties even after repetitive folding, Which means that there is less deformation. Specifically, the amount of change in the restoring force may be 0.1% to 6%. In addition, the adhesive film of the present invention can exhibit good bending reliability even when the peeling strength is high even in a thin thickness of 10 占 퐉 to 200 占 퐉, as described below. The adhesive film can be formed by a pressure-sensitive adhesive composition, which will be described later in detail.

In the adhesive film, P ¹ in the formula (1) may be 50% to 99%, specifically 60% to 95%. In the above range, the adhesive film can be restored to the original state after folding, has no folding at the folded portion, can have good foldability, and can therefore be used in a flexible display device. The pressure-sensitive adhesive film may have a P ²⁰ of the formula 1 in the range of 40% to 95%, specifically 55% to 95%. Flexibility reliability may be good even in repetitive folding in the above range.

The peel strength of the pressure-sensitive adhesive film is preferably 700 gf / in or more, specifically 900 gf / in or more, specifically 900 gf / in. To 3000 gf / in at 25 ° C, in. Within this range, the adhesive strength and reliability at room temperature are excellent. The peel strength of the pressure-sensitive adhesive film at 60 占 폚 is preferably from 500 gf / in to 3,000 gf / in, specifically from 600 gf / in to 2,500 gf / in, Specifically, it can be 700 gf / in to 2,000 gf / in. Within the above range, the peel strength and reliability at high temperature can be excellent. In the present specification, the "peel strength" is the T-PEEL peel strength.

The adhesive film may have a glass transition temperature (Tg) of -100 ° C to -10 ° C, specifically -70 ° C to -30 ° C. Within this range, folding reliability can be improved. The adhesive film may have a haze of 2% or less, specifically 0.1% to 1% and a total light transmittance of 90% or more, specifically 95% to 99% in a visible light region (e.g., a wavelength of 380 nm to 780 nm). Within this range, transparency is good and can be used in optical display devices. The thickness of the adhesive film may be 10 占 퐉 to 200 占 퐉, specifically 10 占 퐉 to 100 占 퐉. In the above range, it can be used in an optical display device.

The pressure-sensitive adhesive film was prepared by the same method as in Example 1, except that the first pressure-sensitive adhesive film (thickness: 100 占 퐉) / pressure-sensitive adhesive film (thickness: 10 占 퐉 to 200 占 퐉) / transparent conductive film (film having a transparent conductive layer formed on one side of a 50 占 퐉 thick polycarbonate resin film) -20 占 폚 or 60 占 폚 and 93 占 폚 for a specimen (length x width, rectangular shape of 100 mm x 160 mm) laminated in this order from the first PET film (thickness: 10 占 퐉 to 200 占 퐉) / second PET film When folding at 180 ° in a width direction (160 mm direction) toward the first PET film at a relative humidity of 3 mm and folding it at a time of 30 folds per minute, the maximum folding that does not cause peeling, cracking, The number of times may be 100,000 or more, for example, 10 to 200,000 times. In the above range, the bending reliability at low temperature or high temperature and high humidity may be good. The specimen is a specimen of window film / adhesive film / transparent conductive film / adhesive film / OLED panel. Bubble generation can be evaluated by bubble generation area. The bubble generation area is not particularly limited, but an image obtained by photographing a bubble-generating portion of the adhesive film with an optical microscope (Olympus, EX-51, 30 magnification) is analyzed by Mountech's Mac-view software, (%) Of the total bubble area. When the bubble generation area is 0%, it is evaluated that there is no bubble generation.

The pressure-sensitive adhesive film comprises (A) a monomer mixture containing a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate or a (meth) acrylic copolymer produced by partial polymerization thereof, (B) a macromonomer, And (C) an initiator.

The monomer mixture may form a hydroxyl group-containing (meth) acrylic copolymer. The hydroxyl group-containing (meth) acrylic copolymer forms a matrix of a pressure-sensitive adhesive film and can exhibit adhesiveness. The hydroxyl group-containing (meth) acryl-based copolymer can increase the peel strength of the pressure-sensitive adhesive film at high temperatures, and exhibits little change in modulus at low temperatures or high temperatures together with organic nanoparticles or macromonomers. .

The glass transition temperature of the hydroxyl group-containing (meth) acrylic copolymer may be -150 ° C to -13 ° C, specifically -100 ° C to -20 ° C. In the above range, the pressure-sensitive adhesive film is excellent in foldability under the folding condition and excellent in adhesion and reliability over a wide temperature range. The refractive index of the hydroxyl group-containing (meth) acrylic copolymer may be 1.40 to 1.70, specifically 1.48 to 1.60. Within this range, transparency can be maintained when laminated with other optical films.

The hydroxyl group-containing (meth) acrylate may be a (meth) acrylate containing at least one hydroxyl group. For example, the hydroxyl group-containing (meth) acrylate may be at least one selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) (Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, (Meth) acrylate, diethylene glycol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (Meth) acrylate, trimethylolethane di (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4- Hydroxycyclopentyl (meth) acrylate Sites may be one or more species of 4-hydroxy-cyclohexyl (meth) acrylate and cyclohexanedimethanol mono (meth) acrylate. In this case, the productivity of the adhesive film is improved, and the adhesive force of the adhesive film can be further improved. (Meth) acrylate having a primary hydroxyl group such as 4-hydroxybutyl (meth) acrylate and a hydroxyl group-containing (meth) acrylate having a secondary hydroxyl group such as 2-hydroxypropyl (meth) Rate can be used to increase the restoring force.

The hydroxyl group-containing (meth) acrylate is used in an amount of 4 to 45% by weight, for example 4 to 40% by weight, 5 to 45% by weight, based on the total of (A) %, 10 wt% to 35 wt%, 10 wt% to 30 wt%, and 15 wt% to 25 wt%. The adhesive strength and endurance reliability of the adhesive film can be further improved in the above range. In particular, when 10 to 30% by weight and 15 to 25% by weight are included, the flexural reliability may be better.

The alkyl group-containing (meth) acrylate may form a matrix of an adhesive film. The alkyl group-containing (meth) acrylate may include an unsubstituted linear or branched alkyl (meth) acrylate having 1 to 20 carbon atoms. (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, (Meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl Acrylate, decyl (meth) acrylate, and lauryl (meth) acrylate. Specifically, by using an alkyl (meth) acrylic monomer having 4 to 8 carbon atoms, the effect of increasing the initial adhesive strength may be further increased. Specifically, the use of a branched alkyl (meth) acrylate monomer may further increase the initial adhesive strength. The alkyl group-containing (meth) acrylate is used in an amount of 50 to 90% by weight, specifically 55 to 90% by weight, 60 to 90% by weight and 60 to 80% by weight in (A) . Within the above range, there may be an adhesive force, a restoring force and an endurance reliability effect of the adhesive film.

In addition, the monomer mixture may further include at least one of monomers having ethylene oxide, monomers having propylene oxide. These may be contained in an amount of 20% by weight or less, specifically 0.5 to 10% by weight in (A) + (B). In the above range, the amount of change of the restoring force is small and the folding performance can be excellent.

As the monomer having an ethylene oxide, one or more (meth) acrylate monomers containing an ethylene oxide group (-CH ₂ CH ₂ O-) may be used. (Meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate, polyethylene oxide monoethyl ether (meth) acrylate, polyethylene oxide monopropyl ether (meth) acrylate, (Meth) acrylate, polyethylene oxide monoethyl ether (meth) acrylate, polyethylene oxide monobutyl ether (meth) acrylate, polyethylene oxide monopentyl ether (meth) acrylate, polyethylene oxide dimethyl ether (Meth) acrylate such as polyethylene oxide monoisobutyl ether (meth) acrylate, polyethylene oxide monoisobutyl ether (meth) acrylate, and polyethylene oxide mono butyl ether (meth) acrylate. Ah The.

The monomer having propylene oxide is at least one monomer selected from the group consisting of polypropylene oxide monomethyl ether (meth) acrylate, polypropylene oxide monoethyl ether (meth) acrylate, polypropylene oxide monopropyl ether (meth) acrylate, polypropylene oxide monobutyl ether (Meth) acrylate, polypropylene oxide diethyl ether (meth) acrylate, polypropylene oxide monoisopropyl ether (meth) acrylate, polypropylene oxide dimethyl ether (Meth) acrylate such as polypropylene oxide monoisobutyl ether (meth) acrylate, polypropylene oxide mono butyl ether (meth) acrylate, and the like, but is not limited thereto no All.

(Meth) acrylate, the alkyl group-containing (meth) acrylate, the alkyl group-containing (meth) acrylate and the alkyl group-containing (meth) acrylate in an amount of from 10 to 30% by weight, specifically from 15 to 25% 80 to 80% by weight, 0 to 20% by weight, specifically 0.5 to 10% by weight, of a monomer having ethylene oxide or a monomer having propylene oxide. In the above range, the amount of change of the restoring force is small and the folding performance can be excellent.

The monomer mixture may further comprise a copolymerizable monomer having no hydroxyl group, alkyl group, ethylene oxide group or propylene oxide group. Specifically, the copolymerizable monomer may include at least one of a monomer having an amine group, a monomer having an amide group, a monomer having an alkoxy group, a monomer having a phosphoric acid group, a monomer having a sulfonic acid group, a monomer having a phenyl group, and a monomer having a silane group .

Monomers having an amine group include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, dimethylaminoethyl Acrylic acid-containing (meth) acrylate such as diethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, N-tert- butylaminoethyl (meth) acrylate, and methacryloxyethyltrimethylammonium chloride But are not necessarily limited to, monomers.

The amide group-containing monomer may be at least one monomer selected from the group consisting of (meth) acrylamide, N-methyl acrylamide, N-methylmethacrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (Meth) acryl-based monomer having an amide group such as bis (meth) acrylamide or 2-hydroxyethyl acrylamide, but is not limited thereto.

Examples of the monomer having an alkoxy group include 2-methoxyethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, 2-ethoxypropyl (meth) (Meth) acrylate, methoxypentyl (meth) acrylate, 3-ethoxypentyl (meth) acrylate, 2-ethoxypentyl ) Acrylate, 3-butoxyhexyl (meth) acrylate, and the like.

Monomers having a phosphoric acid group include monomers such as 2-methacryloyloxyethyldiphenyl phosphate (meth) acrylate, trimethacryloyloxyethylphosphate (meth) acrylate, triacryloyloxyethylphosphate (meth) Acrylic monomer having a phosphoric acid group, but the present invention is not limited thereto.

The monomer having a sulfonic acid group may be an acrylic monomer having a sulfonic acid group such as sodium sulfopropyl (meth) acrylate, sodium 2-sulfoethyl (meth) acrylate, and sodium 2-acrylamido-2-methylpropane sulfonate But is not necessarily limited thereto.

The monomer having a phenyl group can be an acrylic vinyl monomer having a phenyl group such as p-tert-butylphenyl (meth) acrylate, o-biphenyl (meth) acrylate and phenoxyethyl (meth) acrylate, It is not.

The monomer having a silane group may be selected from the group consisting of 2-acetoacetoxyethyl (meth) acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethyl) silane, vinyltriacetoxysilane, Butoxypropyltrimethoxysilane, and the like, but is not limited thereto.

The copolymerizable monomer may be contained in the monomer mixture in an amount of 10% by weight or less, specifically 7% by weight or less, more specifically 0.1% by weight to 10% by weight. In the above range, the pressure-sensitive adhesive composition can further improve the adhesive strength and durability of the pressure-sensitive adhesive film.

In one embodiment, the monomer having an alkyl group (meth) acrylate, the monomer having an ethylene oxide, the monomer having a propylene oxide and the copolymerizable monomer have a glass transition temperature (Tg) of from -150 ° C to 0 ° C, for example, -150 ° C to -20 ° C, or -150 ° C to -40 ° C. In this case, the glass transition temperature of the copolymer can be lowered, and excellent adhesion can be maintained even at a low temperature (-20 ° C), and a similar storage modulus value can be obtained at a high temperature (80 ° C) and a low temperature (-20 ° C). (Meth) acrylate, ethylene oxide-containing monomer, propylene oxide-containing monomer and copolymerizable monomer having a glass transition temperature of the homopolymer of -150 ° C to 0 ° C form a matrix of a pressure-sensitive adhesive film, Methacrylic copolymer can lower the glass transition temperature of the acrylic copolymer so that the adhesive film can satisfy the restoring force.

The monomer mixture may further comprise a monomer having a carboxylic acid group. The monomer having a carboxylic acid group may be at least one monomer selected from the group consisting of (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, 3-carboxypropyl (meth) acrylate, 4-carboxybutyl (meth) acrylate, itaconic acid, Maleic anhydride, and the like, but are not necessarily limited thereto. The monomer having a carboxylic acid group may be contained in an amount of 5% by weight or less, specifically 3% by weight or less, more specifically 1% by weight or less, of (A) + (B). Within this range, the pressure-sensitive adhesive composition can further improve the adhesion and durability of the pressure-sensitive adhesive film without corrosion of the metal adherend.

The macromonomer can be polymerized with the monomer mixture to form a hydroxyl group-containing (meth) acrylic copolymer, whereby the strength of the pressure-sensitive adhesive film can be increased. The macromonomer is included in the adhesive film so that the peeling strength can be increased even for a thin adhesive film.

For example, the macromonomer can attain the peel strength described above also for the thickness of the adhesive film of 10 탆 to 50 탆. The macromonomer may have a functional group curable by an active energy ray and may be polymerized with a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate. Specifically, the macromonomer may be represented by the following formula (1): &lt; EMI ID =

&Lt; Formula 1 >

(In Formula 1, R ¹ is hydrogen or a methyl group, X represents a single bond or a divalent coupler, Y is methyl (meth) acrylate, ethyl (meth) acrylate, n- butyl (meth) acrylate, iso- butyl (Meth) acrylate, t-butyl (meth) acrylate, styrene, and (meth) acrylonitrile.

The macromonomer may have a number average molecular weight of 2,000 to 20,000, specifically 2,000 to 10,000, more specifically 4,000 to 8,000. Within the above range, sufficient adhesive strength can be obtained, heat resistance is excellent, and deterioration of workability due to an increase in viscosity of the pressure-sensitive adhesive composition can be suppressed. The macromonomer may have a glass transition temperature of from 40 캜 to 150 캜, specifically from 60 캜 to 140 캜, more specifically from 80 캜 to 130 캜. In the above range, the pressure-sensitive adhesive film can exhibit sufficient cohesive strength, and the degree of stickiness and deterioration of the adhesive force can be suppressed.

2 the coupler is an arylene group, -NR a C1 to C10 alkyl groups, C7 to C13 aryl alkyl group, C6 to C12 ² - (wherein, R ² is an alkyl group of hydrogen, or a C1 to C5), COO-, - _{O-, -S-, -SO 2 NH-,} -NHSO 2 -, may be a group derived from -NHCOO-, -OCONH, or heterocyclic.

The divalent linking group may be represented by the following formulas (1a) to (1d):

<Formula 1a>

&Lt; EMI ID =

&Lt; Formula 1c >

<Formula 1d>

(In the above Chemical Formulas (1a) to (1d), * denotes the connecting site of the element)

Commercial macromonomers may be used. For example, a macromonomer wherein the terminal is methacryloyl group and the segment corresponding to Y is methyl methacrylate, the segment corresponding to Y is styrene, the segment corresponding to Y is a styrene / acryl Macromonomers in which the segment corresponding to Y is butyl acrylate, and the like can be used.

The macromonomer may be contained in an amount of 20 wt% or less, specifically 0.1 wt% to 20 wt%, 0.1 wt% to 10 wt%, or 0.5 wt% to 5 wt% in (A) + (B). Within this range, it is possible to balance the viscoelasticity, the modulus and the restoring force of the pressure-sensitive adhesive film, and the increase in haze of the pressure-sensitive adhesive film can be prevented.

The organic nanoparticles have good foldability at room temperature and high temperature of the adhesive film, have excellent low temperature and / or room temperature viscoelasticity of the adhesive film, have a crosslinked structure, and stably exhibit high temperature viscoelasticity of the adhesive film. The pressure-sensitive adhesive film may have a modulus of 20 kPa to 500 kPa, specifically 20 kPa to 300 kPa at 80 ° C. Within this range, high temperature reliability improvement effects can be obtained. The pressure-sensitive adhesive film may have a modulus of 25 kPa to 500 kPa, specifically 30 kPa to 300 kPa at 25 ° C. Within the above range, viscoelastic characteristics are exhibited at room temperature, the resilience is excellent, and the number of cycles of the foldable test can be increased. The pressure-sensitive adhesive film may have a modulus of 20 kPa to 500 kPa, specifically 30 kPa to 500 kPa and 30 kPa to 300 kPa at -20 ° C. Within the above range, viscoelastic characteristics are exhibited at low temperatures, and the resilient force is excellent. The adhesive film may have a modulus ratio at a modulus of -20 占 폚 at 80 占 폚 of from 1: 1 to 1:10, specifically from 1: 1 to 1: 6, more specifically from 1: 1 to 1: 5. Within the above range, the adhesive film does not deteriorate the adhesive force between the adherend in a wide temperature range (-20 DEG C to 80 DEG C), is reliable, and can be used for a flexible optical member.

By controlling the nanoparticles having a specific average particle diameter and the refractive index difference of the (meth) acrylic copolymer having a hydroxyl group to be small, the adhesive film has excellent transparency even though it contains nanoparticles .

The organic nanoparticles may have an average particle diameter of 10 nm to 400 nm, specifically 10 nm to 300 nm, more specifically 10 nm to 200 nm, more specifically 50 nm to 150 nm. Within this range, aggregation of the organic nanoparticles can be prevented, the folding of the adhesive film is not affected, and the transparency of the adhesive film can be good. The difference in refractive index between the organic nanoparticles and the (meth) acrylic copolymer having a hydroxyl group is 0.05 or less, specifically 0 or more and 0.03 or less, specifically 0 or more and 0.02 or less. In the above range, the transparency of the adhesive film can be excellent. The refractive index of the organic nanoparticles may be 1.40 to 1.70, specifically 1.48 to 1.60. Within the above range, the transparency of the adhesive film may be excellent.

The organic nanoparticles may include, but are not limited to, core-shell nanoparticles such as a bead type as well as core-shell nanoparticles. In the case of the core-shell type, the core and the shell can satisfy the following formula 3: When the particle type as described above is used, the folding property of the pressure-sensitive adhesive film is good and it may be effective for balance and physical properties of elasticity and flexibility.

<Formula 3>

Tg (c) < Tg (s)

(Wherein Tg (c) is the glass transition temperature (unit: 占 폚) of the core,

Tg (s) is the glass transition temperature (unit: ° C) of the shell).

As used herein, the term "shell" means the outermost layer of the organic nanoparticles. The core may be a single spherical particle. However, the core may further comprise additional layers surrounding the spherical particles if they have the above glass transition temperature.

Specifically, the glass transition temperature of the core may be -150 ° C to 10 ° C, specifically -150 ° C to -5 ° C, more specifically -150 ° C to -20 ° C. Within this range, there may be a low temperature and / or room temperature viscoelastic effect of the adhesive film. The core may include at least one of polyalkyl (meth) acrylate, polysiloxane, and polybutadiene having the above glass transition temperature.

The polyalkyl (meth) acrylate may be at least one selected from the group consisting of polymethyl acrylate, polyethylacrylate, polypropyl acrylate, polybutyl acrylate, polyisopropyl acrylate, polyhexyl acrylate, polyhexyl methacrylate, polyethylhexyl acrylate And polyethylhexyl methacrylate, polysiloxane, and is not necessarily limited thereto.

The polysiloxane can be, for example, an organosiloxane (co) polymer. The organosiloxane (co) polymer may be one which is not cross-linked, or a cross-linked (co) polymer may be used. In order to impart impact resistance and colorability, an organosiloxane (co) polymer in a crosslinked state can be used. It is a crosslinked form of organosiloxane, specifically crosslinked dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane or a mixture of two or more thereof. By using a copolymerized form of two or more organosiloxanes, the refractive index can be adjusted from 1.41 to 1.50.

The crosslinking state of the organosiloxane (co) polymer can be determined by the degree of dissolution by various organic solvents. As the crosslinking state deepens, the degree of dissolution by the solvent becomes smaller. As the solvent for determining the crosslinking state, acetone, toluene and the like can be used. Specifically, the organosiloxane (co) polymer may have a portion which is not dissolved by acetone or toluene. The insoluble matter to the toluene of the organosiloxane copolymer may be 30% or more.

Additionally, the organosiloxane (co) polymer may further comprise an alkyl acrylate crosspolymer. The alkyl acrylate crosslinked polymer may be selected from the group consisting of methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. For example, n-butyl acrylate or 2-ethylhexyl acrylate having a low glass transition temperature may be used.

Specifically, the glass transition temperature of the shell may be from 15 캜 to 150 캜, specifically from 35 캜 to 150 캜, more specifically from 50 캜 to 140 캜. In the above range, the dispersibility of the organic nanoparticles in the (meth) acrylic copolymer may be excellent. The shell may comprise a polyalkyl methacrylate having said glass transition temperature. For example, it is possible to use polymethylmethacrylate (PMMA), polyethylmethacrylate, polypropylmethacrylate, polybutylmethacrylate, polyisopropylmethacrylate, polyisobutylmethacrylate and polycyclohexylmethacrylate Rate, &lt; / RTI &gt; but is not necessarily limited thereto.

The core may comprise from 30 wt% to 99 wt%, specifically from 40 wt% to 95 wt%, and more specifically from 50 wt% to 90 wt%, of the organic nanoparticles. Within the above range, the folding property of the pressure-sensitive adhesive film may be good in a wide temperature range. The shell may comprise from 1 wt% to 70 wt%, specifically from 5 wt% to 60 wt%, more specifically from 10 wt% to 50 wt%, of the organic nanoparticles. Within the above range, the folding property of the pressure-sensitive adhesive film may be good in a wide temperature range.

The organic nanoparticles may be contained in an amount of 0.1 to 10% by weight and 0.5 to 8% by weight of the adhesive film. The organic nanoparticles may be contained in an amount of 10 wt% or less, specifically 0.1 wt% to 10 wt% and 0.5 wt% to 8 wt% in (A) + (B). Within this range, it is possible to balance the viscoelasticity, modulus and restitution of the adhesive film.

Organic nanoparticles can be prepared by emulsion polymerization, suspension polymerization, or solution polymerization.

The initiator can cure a monomer mixture comprising a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate or a (meth) acrylic copolymer produced by partial polymerization thereof. The initiator may include a radical photopolymerization initiator. The initiator may be an acetophenone-based compound, a benzylketal-type compound, or a mixture thereof, but is not limited thereto. Preferably, the acetophenone compound is selected from the group consisting of 2,2-dimethoxy-2-phenylacetophenone, 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2-methyl-1- (4-methylpiperazin-1-yl) methyl) -1,3-benzodiazepinone, 2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, or mixtures thereof .

The initiator may be included in an amount of 0.001 to 5 parts by weight, specifically 0.005 to 3 parts by weight, more specifically 0.01 to 1 part by weight based on 100 parts by weight of (A) + (B). In the above range, the curing reaction can be completely carried out, and the remaining amount of the initiator remains, the permeability can be prevented from being lowered, the bubble generation can be lowered, and the reactivity can be improved.

The pressure-sensitive adhesive composition may further include a crosslinking agent. The cross-linking agent can increase the degree of crosslinking of the pressure-sensitive adhesive composition and increase the mechanical strength of the pressure-sensitive adhesive film. The crosslinking agent can further reduce the amount of change in the restoring force of the pressure-sensitive adhesive composition of the present invention. The crosslinking agent may comprise a multifunctional (meth) acrylate capable of curing with an active energy beam. In an embodiment, the crosslinking agent is selected from the group consisting of 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (Meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate, di (Meth) acrylate, trimethylolpropane di (meth) acrylate, acryloyloxyethyl isocyanurate, allyl cyclohexyl di (meth) acrylate, tricyclodecane dimethanol Acrylate, di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified trimethylpropane di (meth) acrylate, adamantanedi It is 9,9-bis [4- (2-yl-acryloyl oxy) phenyl] 2-functional acrylate, such as fluorene; (Meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide Trifunctional acrylates such as modified trimethylolpropane tri (meth) acrylate, trifunctional urethane (meth) acrylate or tris (meth) acryloxyethylisocyanurate; Tetrafunctional acrylates such as diglycerin tetra (meth) acrylate or pentaerythritol tetra (meth) acrylate; Pentafunctional acrylates such as dipentaerythritol penta (meth) acrylate; (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate or urethane (meth) acrylate (ex. Isocyanate monomer and trimethylol propane tri (Meth) acrylates of polyhydric alcohols can be used as the crosslinking agent. The polyfunctional (meth) acrylates of polyhydric alcohols may be used alone or in combination of two or more. .

The crosslinking agent may be included in an amount of 0.001 to 10 parts by weight, specifically 0.003 to 7 parts by weight, and particularly 0.01 to 5 parts by weight, based on 100 parts by weight of (A) + (B). There is an effect of excellent adhesion and reliability in the above range.

The pressure-sensitive adhesive composition may further include a silane coupling agent. As the silane coupling agent, those conventionally known to those skilled in the art can be used. For example, there can be mentioned 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyl tri A silicon compound having an epoxy structure such as methoxysilane; A polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane and (meth) acryloxypropyltrimethoxysilane; Containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane. ; And 3-chloropropyltrimethoxysilane, and the like, but are not limited thereto. Preferably, a silane coupling agent having an epoxy structure can be used.

The silane coupling agent may be contained in an amount of 0.01 part by weight to 0.1 part by weight, specifically 0.05 part by weight to 0.1 part by weight based on 100 parts by weight of (A) + (B). There is an effect of increasing the reliability in the above range.

The pressure-sensitive adhesive composition may optionally contain a curing accelerator, an ionic liquid, a lithium salt, an inorganic filler, a softener, a molecular weight modifier, an antioxidant, an antioxidant, a stabilizer, a tackifier resin, a modifying resin (polyol resin, phenol resin, (Coloring pigments, extender pigments, etc.), treating agents, ultraviolet light blocking agents, fluorescent whitening agents, dispersing agents, heat stabilizers, antioxidants, antioxidants, A light stabilizer, an ultraviolet absorber, an antistatic agent, a coagulant, a lubricant and a solvent.

The pressure-sensitive adhesive composition may have a viscosity at 25 ° C ranging from 300 cPs to 50,000 cPs, and may have an effect of obtaining excellent coating and thickness uniformity in the above range.

The pressure-sensitive adhesive composition can be prepared by partially polymerizing the monomer mixture, and comprising macromonomer, at least one of organic nanoparticles, and an initiator. A crosslinking agent, a silane coupling agent, an additive, and the like may be further included. The pressure-sensitive adhesive composition can be prepared by partially polymerizing the above-mentioned monomer mixture and a mixture containing at least one of macromonomer and organic nanoparticles and including an initiator. A crosslinking agent, a silane coupling agent, an additive, and the like may be further included. Partial polymerization may include solution polymerization, suspension polymerization, photopolymerization, bulk polymerization, or emulsion polymerization. Specifically, the solution polymerization can be carried out at 50 DEG C to 100 DEG C by adding an initiator to the monomer mixture. The initiator may be an acetophenone radical photopolymerization initiator including 2,2-dimethoxy-2-phenylacetophenone and the like. Partial polymerization can be carried out at 25 DEG C with a viscosity of from 1,000 cPs to 10,000 cPs, specifically from 4,000 cPs to 9,000 cPs.

The adhesive film can be produced by a conventional method. For example, the pressure-sensitive adhesive composition may be coated on a release film and cured. Curing may include irradiation of the irradiation dose 400mJ / cm ² to 3000mJ / cm ² at a wavelength of 300nm to 400nm into a low-pressure lamp in an oxygen-free state.

The optical member according to an embodiment of the present invention includes an optical film and an adhesive film formed on at least one side of the optical film, and the adhesive film may include an adhesive film according to embodiments of the present invention. Thus, the optical member has good bending and / or good folding properties and can be used in a flexible display device.

The optical film may be at least one selected from the group consisting of a window film, a window, a polarizing plate, a color filter, a retardation film, an elliptically polarizing film, a reflective polarizing film, an antireflection film, OLED device barrier layers, plastic LCD substrates, indium tin oxide (ITO), fluorinated tin oxide (FTO), aluminum doped zinc oxide (AZO), carbon nanotubes (CNT), nanowires such as Ag nanowires and graphene , And the like. The method for producing an optical film can be easily manufactured by a person having ordinary skill in the art to which the present invention belongs.

For example, the touch panel can be formed by attaching the touch pad to a window or an optical film using an adhesive film. Or may be applied to an ordinary polarizing film as an adhesive film as in the prior art.

The optical display device of the present invention may include the pressure-sensitive adhesive film of the present invention. The optical display device may include an organic light emitting diode display, a liquid crystal display, and the like. The optical display device may include a flexible display device. However, the optical display device may include a non-flexible display device.

Hereinafter, a flexible display device according to an embodiment of the present invention will be described with reference to FIG. 3 is a cross-sectional view of a flexible display device according to an embodiment of the present invention.

3, the flexible display device 100 according to an exemplary embodiment of the present invention includes a display unit 110, an adhesive layer 120, a polarizer 130, a touch screen panel 140, and a flexible window film 150, and the adhesive layer 120 may include an adhesive film according to an embodiment of the present invention.

The display unit 110 is for driving the flexible display device 100 and may include an optical element including an OLED, an LED, a quantum dot light emitting diode (QLED) formed on a substrate and a substrate, or an LCD device. Although not shown in FIG. 3, the display unit 110 may include a lower substrate, a thin film transistor, an organic light emitting diode, a planarization layer, a protection layer, and an insulation layer.

The polarizing plate 130 may implement polarizing of the inner light or prevent reflection of the external light to realize the display or increase the contrast ratio of the display. The polarizing plate may be composed of a polarizer alone. Or the polarizing plate may include a polarizing film and a protective film formed on one or both sides of the polarizing film. Or the polarizing plate may include a polarizer and a protective coating layer formed on one or both sides of the polarizer. The polarizer, the protective film, and the protective coating layer may be conventional ones known to those skilled in the art.

The touch screen panel 140 senses a change in capacitance caused when a conductor such as a human body or a stylus touches, and generates an electrical signal. The display unit 110 can be driven by this signal. The touch screen panel 140 may include a first sensor electrode and a second sensor electrode formed between the first sensor electrode and the first sensor electrode, which are formed by patterning a conductive conductive material. have. The conductors for the touch screen panel 340 may include, but are not limited to, metal nanowires, conductive polymers, carbon nanotubes, and the like.

The flexible window film 150 may be formed at the outermost portion of the flexible display device 300 to protect the display device.

Although not shown in FIG. 3, an adhesive layer is further formed between the polarizer 130 and the touch screen panel 140 and / or between the touch screen panel 140 and the flexible window film 150 to form a polarizing plate, a touch screen panel, It is possible to strengthen the bonding between the window films. In one embodiment, the adhesive layer may be formed of a pressure sensitive adhesive composition comprising a (meth) acrylate based resin, a curing agent, an initiator, and a silane coupling agent. In other embodiments, the adhesive layer may comprise an adhesive film according to one embodiment of the present invention. Further, although not shown in FIG. 3, a polarizing plate is further provided under the display unit 110, so that polarized light can be realized.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It should be understood, however, that the same is by way of illustration and example only and is not to be construed in any way as limiting the invention.

Manufacturing example

Wherein the core is polybutyl acrylate, the shell is polymethyl methacrylate, the core is 65 wt% of the organic nanoparticles, the shell is 35 wt% of the organic nanoparticles, the average particle diameter is 100 nm, the refractive index is 1.48 was prepared.

Example  One

48 parts by weight of 2-ethylhexyl acrylate (2-EHA), 20 parts by weight of n-butyl acrylate (BA), 10 parts by weight of 2-ethylhexyl diethylene glycol ether (meth) acrylate (EHDG- , 5 parts by weight of hydroxypropyl acrylate (HOP-A), 15 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 1 part by weight of macromonomer AA-6 (Toakosei) , And 0.03 part by weight of Irgacure 651 as an initiator were mixed well in the reactor. The dissolved oxygen in the reactor was replaced with a nitrogen gas, and the mixture was partially polymerized by irradiation with ultraviolet rays using a low-pressure mercury lamp for several minutes to prepare a viscous liquid having a viscosity of 5,000 cps at 25 ° C. 0.5 part by weight of initiator Irgacure 184 was added to the viscous liquid and mixed to prepare a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition was applied to a PET (polyethylene terephthalate) film as a release film, and irradiated with ultraviolet light at a light quantity of 2000 mJ / cm ² to produce a pressure-sensitive adhesive sheet of a pressure-sensitive adhesive film and a PET film having a thickness of 10 탆.

Example  2 to Example  6

A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1, except that the composition of the mixture and the thickness of the pressure-sensitive adhesive film were changed as shown in Table 1 below.

Comparative Example  1 to Comparative Example  2

A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1, except that the composition of the mixture and the thickness of the pressure-sensitive adhesive film were changed as shown in Table 1 below.

The properties of the pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples were evaluated in the following Table 1, and the results are shown in Table 1 below.

(1) Resilience according to cycle repetition: A PET release film was released on the pressure-sensitive adhesive sheet of Examples and Comparative Examples to obtain an adhesive film. The restoring force was evaluated by TA.XT_Plus Texture Analyzer (Stable Micro System) at 25 ° C.

Referring to FIG. 1, two end portions of a PET (polyethylene terephthalate) film (thickness: 75 μm) having a length x width (50 mm × 20 mm) were adhered to each other by an adhesive film having a width x length (20 mm × 20 mm) / Adhesive film / second PET film were laminated in this order and a contact area between the PET film and the pressure-sensitive adhesive film was set to a width x length (20 mm x 20 mm). A jig was fixed to both ends of the PET film of the specimen. The contact area of each of the first PET film and the second PET film and the jig was set so as to have a length x width (15 mm x 20 mm). One jig was fixed at 10 MPa and the other jig was pulled to a length of 1000% of the thickness of the adhesive film (10 times the initial thickness of the adhesive film, X ₂ ) at a speed of 300 mm / min, and a length of 1000% And maintained for 10 seconds, and then restored to the same speed (300 mm / min) as the pulling speed. When the adhesive film was stretched to 1000% of the initial thickness of the adhesive film, the stretched length of the adhesive film when a force of 0 kPa was applied to the adhesive film was defined as X ₁ , which was referred to as one cycle. Referring to FIG. 2, a graph was obtained by plotting the stretched length of the adhesive film on the X-axis and the force applied on the adhesive film on the Y-axis. The cycle was repeated once, five times, ten times, and twenty times, and the restoring force was calculated according to the formula 2.

(2) Variation of restitution force: Calculated according to Equation 1 using the restitution force obtained according to (1).

(3) Peel Strength: The corona was treated twice (total dose: 156 dose) with a PET film of length x width x thickness (150 mm x 25 mm x 75 m) while discharging the plasma at a dose of 78 doses using a corona processor. An adhesive film having a size of 100 mm x 25 mm (length x width) was obtained from the pressure-sensitive adhesive sheet of Examples and Comparative Examples. The corona-treated side of the PET film was laminated on both sides of the adhesive film to prepare the specimen shown in Fig. 4 (a). The specimen was autoclaved at a pressure of 3.5 bar at 50 ° C for 1000 seconds and the specimens were fixed on a TA.XT_Plus Texture Analyzer (Stable Micro System). Referring to FIG. 4 (b), the T-Peel peel strength was measured by fixing one PET film at 25 ° C. and pulling the other PET film at a rate of 50 mm / min in a TA.XT_plus Texture Analyzer.

(4) Modulus: The viscoelasticity was measured by a rheometer (Anton Paar MCR-501), which is a dynamic viscoelasticity measuring device, at a shear rate of 1 rad / sec and a strain of 1% under an auto strain condition. After removing the release film from the pressure-sensitive adhesive sheets of Examples and Comparative Examples, a plurality of pressure-sensitive adhesive films were laminated, laminated to a thickness of 500 탆, and the laminate was perforated with a perforator having a diameter of 8 mm. A load of 300 gf was applied to the specimen using an 8 mm jig. The temperature was raised at a temperature rising rate of 5 ° C / min from -60 ° C to 90 ° C, and the modulus was measured at -20 ° C.

(5) Low temperature bending reliability: laminated in the order of a window film / a first adhesive film / a transparent conductive film / a polarizer / a second adhesive film / an OLED panel, and the first adhesive film and the second adhesive film, The flexural reliability of the module using the adhesive film obtained from the adhesive sheet was evaluated. Specimens for the flexural reliability evaluation (rectangular cross-section of length x width, 100 mm x 160 mm) are as follows:

(i) Window film: PET film (thickness: 100 m, Cosmoshine TA015, Toyobo);

(ii) First adhesive film and second adhesive film: An adhesive film produced by releasing a PET release film from the adhesive sheets of Examples and Comparative Examples;

(iii) Transparent conductive film: A silver nanowire-containing solution (Clearohm-A G4-05, Cambrios, silver nanowire and binder-containing solution) was spin-coated on one surface of a polycarbonate film A transparent conductive film on which a transparent conductive layer is formed by thermal curing;

(iv) OLED panel: Replaced with PET film (thickness: 100 μm).

The folding of the test piece by folding the window film in the width direction (160 mm direction) 180 degrees at a curvature radius of 3 mm toward the inside was folded once, and folding 30 times per minute was repeated at 100 deg. In particular, it was evaluated whether or not a crack occurred in the adhesive film on the window film side. "Good" when no crack occurred, and "Bad" when crack occurred.

(6) High-temperature / high-humidity bending reliability 1: The bending reliability was evaluated in the same manner as in (5) except that it was folded at 60 ° C and 93% relative humidity (RH) instead of -20 ° C .

(7) High-temperature / high-humidity bending reliability 2: Corona treatment (total dose: 156 dose) was applied to one side of the PET film while plasma was discharged at a dose of 78 dose using a corona processor. PET films were released from the pressure-sensitive adhesive sheets of Examples and Comparative Examples to obtain pressure-sensitive adhesive films. The corona-treated side of the PET film was laminated on both sides of the adhesive film and laminated in a three-layer structure of PET film (thickness: 75 mu m) / adhesive film / PET film (thickness: 75 mu m) A rectangular specimen having a cross section of x width (70 mm x 25 mm) was prepared. The specimens were folded so that the radius of curvature was 3 mm at the center in the longitudinal direction (70 mm direction) of the specimen, and the specimens were fixed in a mold and stored in a 60 ° C. and 93% relative humidity oven for 3 days. Thereafter, bubbling and delamination delamination) were evaluated. When there was no bubble generation and delamination, "good", bubble generation, and delamination were evaluated as "poor" if any.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 (A) 2-EHA
(Parts by weight) 48 58 58 59 59 77 75 97 BA
(Parts by weight) 20 10 10 10 10 0 0 0 EHDG-AT
(Parts by weight) 10 10 10 10 10 0 0 0 HOP-A
(Parts by weight) 5 10 10 10 10 0 10 0 4-HBA
(Parts by weight) 15 10 10 10 10 20 10 3 IBXA
(Parts by weight) 0 0 0 0 0 0 5 0 (B) AA6
(Parts by weight) One One One One 0 0 0 0 Organic nanoparticles
(Parts by weight) One One One 0 One 3 0 0 Irgacure184
(Parts by weight) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Thickness of adhesive film
(탆) 10 50 100 50 50 50 10 50 Resilience (%) according to cyclic repetition 1 time 94 91 85 89 89 87 82 58 5 times 94 90 84 88 88 86 75 26 10 times 93 89 83 86 86 85 66 8 20 times 92 86 80 84 83 82 52 0 The amount of change in the restoring force (%) in Equation 1 2 5 5 5 6 5 30 58 Peel strength
(gf / in, @ 25 &lt; 0 &gt; C) 950 1350 1600 1400 1380 1410 490 680 Modulus (kPa, @ -20 ℃) 135 120 120 115 112 104 98 61 Low temperature bending reliability
@ -20 ℃ Good Good Good Good Good Good Good Bad High temperature / high humidity bending reliability 1 @ 60 ℃ and 93% RH Good Good Good Good Good Good Bad Bad High temperature / high humidity bending reliability 2 @ 60 ℃ and 93% RH Good Good Good Good Good Good Bad Bad

* In Table 1, IBXA: isobornyl acrylate

As shown in Table 1, the pressure-sensitive adhesive film of the present invention was excellent in bending reliability at a low temperature or a high temperature / high humidity as the variation in restitution force was 10% or less. Further, the pressure-sensitive adhesive film of the present invention was excellent in peel strength even at a thin thickness.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (16)

(Meth) acrylic copolymer having a thickness of 10 탆 to 200 탆 and a change in restitution force of the following formula (1) is 10% or less:
<Formula 1>
Variation of restitution force = P ¹ - P ²⁰
(Length x length, 20 mm x 20 mm) of the first PET film / second adhesive film (hereinafter referred to as &quot; first end portion / adhesive film &quot;) of the PET (polyethylene terephthalate) And a second end portion of the second PET film were adhered in this order,
The jig was fixed to both ends of the first PET film and the second PET film with respect to the specimen and one jig was fixed at 10 MPa and the other jig was pulled at a rate of 300 mm / (X ₀₎ (unit: ㎛) length of 1000% (10 times the thickness, X ₂₎ (unit: ㎛) of the extended length of the after reaching the holding for 10 seconds, and the pressure-sensitive adhesive film to the X-axis, the pressure-sensitive adhesive film When a graph is obtained with the applied force as a Y axis, the adhesive film is stretched to a length of 1000% of the thickness of the adhesive film, and then restored to a speed of 300 mm / min at the same speed as the pulling speed to apply a force of 0 kPa to the adhesive film Quot; X _{1 &quot;} (unit: 占 퐉) is the length at which the adhesive film stretched at the time when the adhesive film is stretched,
P ¹ is the value (unit:%) calculated by the following formula 2 after the cycle once,
P ²⁰ is the value (unit:%) calculated by the following formula 2 after repeating the cycle 20 times
<Formula 2>
Resilience = (1 - (X ₁ ) / (X ₂ )) x 100.
The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive film has a P ²⁰ of 40% to 95% in the formula (1).
The adhesive film according to claim 1, wherein the adhesive film has a peel strength of at least 700 gf / in at 25 캜.
The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive film has a glass transition temperature of -100 ° C to -10 ° C.
The adhesive film according to claim 1, wherein the adhesive film has a haze of 2% or less in a visible light region.
The adhesive film according to claim 1, wherein the pressure-sensitive adhesive film comprises (A) a monomer mixture containing a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate or a (meth) acrylic copolymer produced by partial polymerization thereof; (B) at least one of macromonomer, organic nanoparticles; And (C) an initiator.
The adhesive film of claim 6, wherein the monomer mixture further comprises at least one of a monomer having ethylene oxide, and a monomer having propylene oxide.
The composition according to claim 6, which comprises 10 to 30% by weight of the hydroxyl group-containing (meth) acrylate, 50 to 90% by weight of the alkyl group-containing (meth) acrylate, a monomer having ethylene oxide, Is from 0 to 20% by weight of at least one of the monomers it has.
7. The adhesive film according to claim 6, wherein at least one of the alkyl group-containing (meth) acrylate, the ethylene oxide-containing monomer and the propylene oxide-containing monomer has a glass transition temperature of -150 DEG C to 0 DEG C .
The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive film has a modulus of 20 kPa to 500 kPa at -20 캜.
The adhesive film according to claim 6, wherein the organic nanoparticles have an average particle diameter of 10 nm to 400 nm.
The adhesive film according to claim 6, wherein the organic nanoparticles are contained in an amount of 0.1 to 10 wt% of the adhesive film.
The pressure-sensitive adhesive film according to claim 6, wherein the macromonomer is contained in an amount of 0.1 to 20 wt% of the pressure-sensitive adhesive film.
The pressure-sensitive adhesive film according to claim 6, wherein the pressure-sensitive adhesive composition further comprises at least one of a silane coupling agent and a crosslinking agent.
An optical film, and an adhesive film formed on at least one side of the optical film, wherein the adhesive film comprises the adhesive film according to any one of claims 1 to 14.
     An optical display device comprising the adhesive film of claim 1.

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