KR102020891B1 - Adhesive film, optical member comprising the same and optical display apparatus comprising the same - Google Patents

Abstract

It is a pressure-sensitive adhesive film containing a (meth) acrylic copolymer having a hydroxyl group and organic nanoparticles, and having a glass transition temperature of -35 ° C. or lower, a first PET film (thickness: 100 µm), an adhesive film (thickness: 50 µm), and a second PET For the folding test, a five-layered specimen (horizontal x vertical) (100 cm x 160 cm) of a film (thickness: 50 m), an adhesive film (thickness: 50 m), and a third PET film (thickness: 125 m) were sequentially stacked. 30 cycles per minute (fixed) to the measuring device to be folded in the direction of the third PET film to fold the half of the longitudinal length of the specimen, and to be folded 180 ° so that the radius of curvature is 3mm Ii) -20 ° C, ii) adhesive film and PET film when bending (folding) (with one cycle of bending and slicing the specimen in one cycle) at one or more of 60 ° C and 93% relative humidity. Adhesion more than 50,000 times until peeling, cracking or foaming of liver A film, an optical member including the same, and an optical display device including the same are provided.

Description

Adhesive film, optical member including the same, and optical display including the same {ADHESIVE FILM, OPTICAL MEMBER COMPRISING THE SAME AND OPTICAL DISPLAY APPARATUS COMPRISING THE SAME}

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 device including a window film, a conductive film, an organic light emitting device, and the like. Various display elements in the optical display device may be adhered by an optical clear adhesive (OCA). Recently, a flexible optical display device has been developed as an optical display device.

The adhesive film used in the flexible optical display device should not only have good folding property at room temperature but also have folding properties even under severe conditions such as low temperature (eg -20 ° C) or high temperature and high humidity (eg 60 ° C and 93% relative humidity). This should be good. In particular, at low temperatures, even when the adhesive film has a good folding property at room temperature due to a low external temperature of the adhesive film, folding may not be implemented at low temperatures. On the other hand, the pressure-sensitive adhesive film is included in the optical display device is bonded to each other rather than included separately from the optical element, the optical film. Therefore, even if the adhesive film alone has good folding properties, when the adhesive film is laminated with a plurality of optical devices and optical films, the optical films and optical films having different physical properties may be affected when folding. You may lose your sex. In addition, the pressure-sensitive adhesive film may be exposed to both low temperature and high temperature as well as room temperature, in which case when the modulus difference between the low temperature and high temperature of the pressure-sensitive adhesive film is much, the reliability of the pressure-sensitive adhesive film may be deteriorated.

Background art of the present invention is disclosed in Korean Patent Laid-Open No. 2007-0055363.

The problem to be solved by the present invention is to provide a pressure-sensitive adhesive film having good foldability at low temperature (-20 ℃) and / or high temperature high humidity (60 ℃ and 93% relative humidity) as well as room temperature.

Another problem to be solved by the present invention is to provide an adhesive film having a good folding property at low temperature and / or high temperature and high humidity even when laminated together on a plurality of display elements and optical films as well as the case of the adhesive film alone.

Another problem to be solved by the present invention is to provide a pressure-sensitive adhesive film with low reliability difference between low temperature and high temperature.

Another problem to be solved by the present invention is to provide an adhesive film having a high peel strength on the display device and / or the optical film.

Another object of the present invention is to provide an adhesive film that can be used in an optical display device is optically transparent.

A (meth) acrylic copolymer having a hydroxyl group formed of a monomer mixture comprising a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate of the present invention, wherein the glass transition temperature is -35 ° C or lower, and the first PET A film (thickness: 100 mu m), the pressure-sensitive adhesive film (thickness: 50 mu m), the second PET film (thickness: 50 mu m), the pressure-sensitive adhesive film (thickness: 50 mu m), and the third PET film (thickness: 125 mu m) The laminated five-layer specimen (width x length) (100 cm x 160 cm) is fixed to the folding test instrument to be folded in the direction of the third PET film so as to fold the half point of the longitudinal length of the specimen, Fold at 180 ° to obtain a 3 mm radius of curvature at a rate of 30 cycles per minute (i) -20 ° C, ii) bending (folding) at one or more of the conditions of 60 ° C and 93% relative humidity. 1 cycle to bend and release once in half) A number of folding until the peeling, cracking or bubbling between the adhesive film and the PET film may be at least 5 million times.

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 surface of the optical film.

The optical display device of the present invention may include the adhesive film of the present invention.

The present invention provides a pressure-sensitive adhesive film having good folding properties at low temperature and / or high temperature and high humidity as well as room temperature.

The present invention provides a pressure-sensitive adhesive film having good folding property at low temperature and / or high temperature and high humidity even when laminated on a plurality of display elements and an optical film as well as the case of the adhesive film alone.

The present invention has a low difference between the modulus at a low temperature and a high temperature to provide an excellent adhesive film.

The present invention provides an adhesive film having a high peel strength on a display device and / or an optical film.

The present invention provides an adhesive film that is optically transparent and can be used in an optical display device.

1 is a cross-sectional view of an optical display device according to an exemplary embodiment of the present invention.
2 is a schematic diagram for measuring peel strength.
Figure 3 shows a cross-sectional view and the folding direction of the specimen for folding evaluation.
4 is a cross-sectional view and a plan view of a specimen for measuring the restoring force.
5 is a graph for restoring force measurement.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

In the present specification, "upper" and "lower" are defined based on the drawings, and according to a viewpoint, "upper" may be changed to "lower" and "lower" to "upper", and "on" or What is referred to as “on” may include not only the above but also intervening other structures in the middle. On the other hand, what is referred to as "directly on" or "directly on" means that there is no intervening structure in between. As used herein, "(meth) acryl" may mean acrylic and / or methacryl.

As used herein, "copolymer" may include oligomers, polymers or resins.

In the present specification, the "average particle diameter" of the organic nanoparticles is a particle diameter of organic nanoparticles, which are expressed in Z-average values and confirmed by SEM / TEM, measured in an aqueous or organic solvent with a Zetasizer nano-ZS device manufactured by Malvern.

In this specification, "modulus" is a storage modulus (G ').

In the present specification, "folding evaluation" refers to a first PET film (thickness: 100 µm), an adhesive film (thickness: 50 µm), a second PET film (thickness: 50 µm), an adhesive film (thickness: 50 µm), a third PET film ( A thickness of 125 μm) of a five-layered test piece (horizontal x vertical) (100 cm x 160 cm) is placed in a folding test measuring instrument (COVOTEC, CFT series) to be 1/2 of the longitudinal length of the specimen. Fixed to fold in the direction of the third PET film to fold, bending at 180 ° with a radius of curvature of 3 mm, bending at -20 ° C or 60 ° C and 93% relative humidity at a rate of 30 cycles per minute It is meant to repeat (folding) (one cycle of bending and releasing the specimen once in half). The specimens simulate a display device in which a display unit, an adhesive film, an optical film (polarizing plate or touch screen panel), an adhesive film, and a window film are sequentially stacked. As used herein, the term "good foldability" refers to a folding count of 50,000 times or more until peeling, cracking and / or foaming occurs between the adhesive film and the PET film when the folding evaluation is performed at -20 ° C or 60 ° C and 93% relative humidity. It means the case. Whether the bubble is generated is not particularly limited, but can be evaluated by the bubble generation area. The bubble generation area is an image of the bubble generated portion of the adhesive film by optical microscope (Olympus, EX-51, 30x magnification) and analyzed by Mountech's Mac-view software. The percentage (%) is calculated. If the bubble generation area is 0%, no bubble is generated.

"Resilience" herein can be calculated by the following equation:

<Equation 1>

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

(Equation 1, when the both ends of the PET (polyethylene terephthalate) film, respectively, the first end, the second end, the first end of the first PET film / adhesive film (width x length, 20mm x 20mm) / In a state in which a specimen was bonded to the second end of the second PET film in order, and then fixed to each end of the first PET film and the second PET film, the jig was fixed to one end of the second PET film, and one jig was fixed at 10 MPa. Pull the other jig at a speed of 300 mm / min at 25 ° C. to reach a length (10 times the thickness, X _2, unit: μm) of the initial thickness (X ₀ ) (unit: μm) of the adhesive film. After maintaining for 10 seconds, when the length of the pressure-sensitive adhesive film X-axis, the force applied to the pressure-sensitive adhesive film to obtain a graph, when the pressure-sensitive adhesive film stretched to the length of 1000% of the thickness of the pressure-sensitive adhesive film pulled 0 kPa is applied to the pressure-sensitive adhesive film by restoring at the same speed (300 mm / min) as the speed. A) The increase in the pressure-sensitive adhesive film when the length X ₁ (㎛ unit).

4 (a) and 4 (b) are cross-sectional views and a plan view of one embodiment of a specimen for measuring the restoring force, respectively, and the amount of PET (polyethylene terephthalate) film (length x width x thickness: 50 mm x 20 mm x 75 μm) When the distal end is referred to as the first end and the second end, respectively, the end portions of the two PET films are adhered to each other by an adhesive film of width x length (20 mm x 20 mm), and the first end / adhesive film / of the first PET film It shows the test piece which is adhered in the order of the second end of the second PET film, and the contact area between the first PET film, the adhesive film, and the second PET film becomes the width x length (20 mm x 20 mm) of the adhesive film. Figure 5 shows the graph when the length of the pressure-sensitive adhesive film X-axis, the force applied to the pressure-sensitive adhesive film Y-axis when measuring the restoring force. The initial thickness (X ₀ ) of the adhesive film may be 10㎛ to 200㎛. Resilience can be measured with the TA.XT_Plus Texture Analyzer (Stable Micro System).

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

The adhesive film according to this embodiment (hereinafter, 'adhesive film') includes a (meth) acrylic copolymer having a hydroxyl group formed of a monomer mixture containing a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate. , The glass transition temperature of the adhesive film is -35 ℃ or less, i) -20 ℃, ii) peeling, crack and / or between the adhesive film and PET film when the folding evaluation under one or more conditions of 60 ℃ and 93% relative humidity The number of times of folding until there is a bubble can be more than 50,000 times. i) -20 ° C, ii) the number of times of folding until the peeling, cracking and / or foaming occurs in the evaluation of folding at one or more of 60 ° C and 93% relative humidity, more than 50,000 times specifically 60,000 to 200,000 times In this case, high reliability may be used for the flexible display device. No bubble generation means that the bubble generation area is 0%. In particular, the adhesive film had good folding properties even when laminated together with a plurality of optical films as in the example of folding evaluation as well as the adhesive film alone. In addition, the adhesive film had good folding properties under both i) -20 ° C and ii) 60 ° C and 93% relative humidity.

The adhesive film includes a (meth) acrylic copolymer having a hydroxyl group; And at least one of macromonomer and organic nanoparticles, and having a glass transition temperature of −35 ° C. or lower, so that a bubble generation area is 0% when evaluating folding at −20 ° C. or 60 ° C. and 93% relative humidity. The number of folding can be more than 50,000 times. Specifically, the pressure-sensitive adhesive film may have a glass transition temperature of −35 ° C. or lower, for example, −60 ° C. to −35 ° C., in which one of i) −20 ° C., ii) 60 ° C. and 93% relative humidity is present. In the above, even when laminated together with the optical element and the optical film, good folding properties can be exhibited. The adhesive film includes a (meth) acrylic copolymer having a hydroxyl group; And by including any one or more of the macromonomer, organic nanoparticles can reduce the modulus difference between low temperature and high temperature to improve the reliability and increase the peel strength. (Meth) acrylic copolymers, macromonomers and organic nanoparticles having hydroxyl groups are described in more detail below.

Pressure-sensitive adhesive film may be at least 60%, 80% or more, specifically 80% to 95% restoring force at 25 ℃. The restoring force is a measure of the degree to which the adhesive film returns to its original state after folding when the adhesive film is laminated and folded on the optical film and the optical element. A pressure-sensitive adhesive film containing at least one of macromonomers and organic nanoparticles and having a restoring force in the above range may be laminated with an optical film and an optical element even at one or more of i) -20 ° C., ii) 60 ° C. and 93% relative humidity. Good folding properties can be exhibited.

The pressure-sensitive adhesive film may have a ratio of modulus at 80 ° C .: modulus at −20 ° C. of 1: 1 to 1:10, specifically 1: 1 to 1: 8, and more specifically 1: 1 to 1: 6. . In the above range, the modulus difference between the high and low temperature of the pressure-sensitive adhesive film is low, which increases the reliability of the pressure-sensitive adhesive film, improves the life of the optical display device, and does not reduce the adhesive strength between the adhesives in a wide temperature range (-20 ° C to 80 ° C), It can be used for optical display devices. The adhesive film may have a modulus of 10 kPa to 500 kPa, specifically 10 kPa to 300 kPa at 80 ° C. In the above range, there may be an effect of improving the high temperature reliability. The adhesive film may have a modulus of 10 kPa to 500 kPa, specifically 20 kPa to 500 kPa at -20 ° C. In the above range, the viscoelastic properties are expressed at low temperatures, there is an advantage that the restoring force is excellent. The adhesive film may have a modulus of 25 kPa to 500 kPa, specifically, 25 kPa to 300 kPa at 25 ° C. In the above range, viscoelastic properties are expressed at room temperature, not only excellent restoring force but also good folding properties can be expressed.

The adhesive film may have a peel strength of 700 gf / in or more, specifically 900 gf / in or more, specifically 900 gf / in to 3000 gf / in at 25 ° C. In the above range, the peeling between the adhesive film and the adherend when used in the flexible display device may be less reliable.

The adhesive film may have a haze of 2% or less, specifically 0.1% to 1%, total light transmittance of 90% or more, and specifically 95% to 99% in a visible light region (for example, a wavelength of 380 nm to 780 nm). Within this range, the optical transparency is good and can be used for the optical display device. The adhesive film may have a thickness of 10 μm to 300 μm, specifically 15 μm to 175 μm. Within this range, it can be used for an optical display device.

The pressure-sensitive adhesive film may be prepared by photocuring the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition may be a monomer mixture for a (meth) acrylic copolymer having a hydroxyl group; And macromonomers or organic nanoparticles. The monomer mixture may be included in the pressure-sensitive adhesive composition in an unpolymerized monomer mixture, but the monomer mixture may be included as a partially polymerized partial polymer.

The monomer mixture may form a (meth) acrylic copolymer having a hydroxyl group. The (meth) acrylic copolymer having a hydroxyl group forms a matrix of the adhesive film and may exhibit adhesiveness. The (meth) acrylic copolymer having a hydroxyl group may have a glass transition temperature of -100 ° C to -10 ° C, specifically -70 ° C to -30 ° C. In the above range, the adhesive film has the effect of having excellent adhesive strength and reliability in a wide temperature range. The (meth) acrylic copolymer having a hydroxyl group may have a refractive index of 1.40 to 1.70, specifically 1.45 to 1.60. Within this range, transparency can be maintained when laminating with other optical films. The monomer mixture may comprise hydroxyl group containing (meth) acrylate and alkyl group containing (meth) acrylate.

The hydroxyl group-containing (meth) acrylate can provide the adhesive force of the adhesive film. The hydroxyl group-containing (meth) acrylate may be a (meth) acrylate containing one or more hydroxyl groups. For example, the hydroxyl group-containing (meth) acrylate is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, 1-chloro-2-hydrate Oxypropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, Neopentylglycol mono (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolethane di (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4- Hydroxycyclopentyl (meth) acrylate Y, 4-hydroxycyclohexyl (meth) acrylate and cyclohexanedimethanol mono (meth) acrylate. In particular, the hydroxyl group-containing (meth) acrylate is an alkyl group-containing (meth) acrylate having 2 or 4 carbon atoms having at least one hydroxyl group, for example, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) By being an acrylate or the like, the folding property can be remarkably good when the folding is evaluated at -20 ° C and / or 60 ° C and 93% relative humidity. The hydroxyl group-containing (meth) acrylate may be included in 10% to 30% by weight, for example 12% to 25% by weight, 15% to 25% by weight in the monomer mixture. In the above range, the adhesion and durability of the pressure-sensitive adhesive film is improved, the folding property is good, and the modulus difference between the high temperature and the low temperature of the pressure-sensitive adhesive film may be good. In particular, when included in an amount of 15% to 25% by weight may be better folding properties at low temperature and high temperature and high humidity.

The alkyl group-containing (meth) acrylate may form a matrix of the adhesive film. The alkyl group-containing (meth) acrylate may include an unsubstituted linear or branched alkyl (meth) acrylic acid ester having 1 to 20 carbon atoms. For example, the alkyl group-containing (meth) acrylate is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate , iso-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth ), Nonyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate and isobornyl (meth) acrylate. In particular, the alkyl group-containing (meth) acrylates are alkyl group-containing (meth) acrylates having 4 to 8 carbon atoms, for example, butyl acrylate, ethylhexyl (meth) acrylate, and the like, so that -20 ° C and / or 60 ° C and 93% The folding property at the relative humidity can be improved. The alkyl group-containing (meth) acrylate may be included in an amount of 70% to 90% by weight, for example 75% to 88%, 75% to 85% by weight in the monomer mixture. The adhesion and durability of the pressure-sensitive adhesive film in the above range can be further improved.

The monomer mixture may further comprise a copolymerizable monomer. The copolymerizable monomer may be included in the (meth) acrylic copolymer to provide additional effects to the (meth) acrylic copolymer, the pressure-sensitive adhesive composition or the pressure-sensitive adhesive film. The copolymerizable monomer is a monomer different from the hydroxyl group-containing (meth) acrylate and the alkyl group-containing (meth) acrylate, and includes a monomer having ethylene oxide, a monomer having propylene oxide, a monomer having an amine 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, a monomer having a silane group, a monomer having a carboxylic acid group, and an amide group-containing (meth) acrylate.

Monomers having ethylene oxide may be at least one (meth) acrylate monomer containing an ethylene oxide group (-CH ₂ CH ₂ O-). For example, polyethylene oxide monomethyl ether (meth) acrylate, polyethylene oxide monoethyl ether (meth) acrylate, polyethylene oxide monopropyl ether (meth) acrylate, polyethylene oxide monobutyl ether (meth) acrylate, polyethylene oxide mono Pentyl ether (meth) acrylate, polyethylene oxide dimethyl ether (meth) acrylate, polyethylene oxide diethyl ether (meth) acrylate, polyethylene oxide monoisopropyl ether (meth) acrylate, polyethylene oxide monoisobutyl ether (meth) It may be a polyethylene oxide alkyl ether (meth) acrylate, such as acrylate, polyethylene oxide monotertbutyl ether (meth) acrylate, but is not necessarily limited thereto.

Monomers with propylene oxide include 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 monopentyl ether (meth) acrylate, polypropylene oxide dimethyl ether (meth) acrylate, polypropylene oxide diethyl ether (meth) acrylate, polypropylene oxide monoisopropyl ether (meth) acrylic Polypropylene oxide alkylether (meth) acrylates, such as latex, polypropylene oxide monoisobutyl ether (meth) acrylate, polypropylene oxide monotertbutyl ether (meth) acrylate, but are not necessarily limited thereto. no All.

Monomers having an amine group include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, dimethylaminoethyl (meth Amine group-containing (meth) acrylic monomers such as acrylate, diethylaminoethyl (meth) acrylate, N-tert-butylaminoethyl (meth) acrylate, and methacryloxyethyltrimethylammonium chloride (meth) acrylate May be, but is not necessarily limited thereto.

Monomers having an alkoxy group include 2-methoxy ethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, 2-ethoxypropyl (meth) acrylate, 2-butoxypropyl (meth) acrylate, 2 -Methoxypentyl (meth) acrylate, 2-ethoxypentyl (meth) acrylate, 2-butoxyhexyl (meth) acrylate, 3-methoxypentyl (meth) acrylate, 3-ethoxypentyl (meth ), 3-butoxyhexyl (meth) acrylate, but is not necessarily limited thereto.

Monomers having a phosphoric acid group include 2-methacryloyloxyethyldiphenyl phosphate (meth) acrylate, trimethacryloyloxyethyl phosphate (meth) acrylate, triacryloyloxyethyl phosphate (meth) acrylate, and the like. It may be an acrylic monomer having a phosphoric acid group, but is not necessarily 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. However, the present invention is not limited thereto.

The monomer having a phenyl group may be an acrylic vinyl monomer having a phenyl group such as p-tert-butylphenyl (meth) acrylate, o-biphenyl (meth) acrylate, phenoxyethyl (meth) acrylate, but is not limited thereto. It doesn't happen.

Monomers having a silane group include 2-acetoacetoxyethyl (meth) acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyl tris (2-methoxyethyl) silane, vinyltriacetoxysilane, and (meth) acryl It may be a vinyl monomer having a silane group such as royloxypropyl trimethoxysilane, but is not necessarily limited thereto.

Monomers having a carboxylic acid group include (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, 3-carboxypropyl (meth) acrylate, 4-carboxybutyl (meth) acrylate, itaconic acid, crotonic acid, maleic acid, and fumaric acid. And maleic anhydride, and the like, but are not necessarily limited thereto.

Amide group-containing (meth) acrylates include (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N, N-methylene Bis (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide. In particular, N-hydroxyethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide are well embodied in the effects of the present invention, and include alkyl group-containing (meth) acrylates and hydroxyl group-containing (meth) acrylates. The compatibility may be excellent effect.

The copolymerizable monomer may be included in an amount of 10% by weight or less, specifically 7% or less, more specifically 0.05% to 10% by weight of the monomer mixture. The pressure-sensitive adhesive composition in the above range can further improve the adhesive strength and durability of the adhesive film. The monomer having a carboxylic acid group may be included in an amount of 5 wt% or less, specifically 3 wt% or less, more specifically 1 wt% or less in the monomer mixture. The pressure-sensitive adhesive composition in the above range can further improve the adhesive strength and durability of the adhesive film.

The organic nanoparticles may have an average particle diameter of 10 nm to 400 nm, specifically 10 nm to 300 nm, and more specifically 50 nm to 150 nm. In the above range, it is possible to prevent the aggregation of the organic nanoparticles, does not affect the folding of the pressure-sensitive adhesive film, transparency of the pressure-sensitive adhesive film may be good within the range of the refractive index difference as described below.

The organic nanoparticles may have a refractive index difference of 0.1 or less, specifically 0 or more and 0.05 or less, specifically 0 or more and 0.02 or less, with a (meth) acrylic copolymer having a hydroxyl group. In the above range, the transparency of the pressure-sensitive adhesive film may be excellent. The organic nanoparticles may have a refractive index of 1.40 to 1.70, specifically 1.45 to 1.60. In the above range, the transparency of the adhesive film may be excellent.

The organic nanoparticles may include, but are not limited to, simple nanoparticles such as a bead type as well as a core-shell type. In the case of the core-shell type, the core and the shell may satisfy the following Equation 2: That is, both the core and the shell may be nanoparticles that are organic materials. When having a particle form as described above, the folding property of the pressure-sensitive adhesive film is good, it may be effective in the balance physical properties of elasticity and flexibility.

<Equation 2>

Tg (c) <Tg (s)

(In Formula 2, Tg (c) is the glass transition temperature (unit: ° C) of the core, Tg (s) is the glass transition temperature (unit: ° C) of the shell).

As used herein, "shell" refers to the outermost layer of organic nanoparticles. The core may be one spherical particle. However, the core may further comprise an additional layer surrounding the spherical particles if it has the above glass transition temperature.

Specifically, the glass transition temperature of the core may be -150 ℃ to 10 ℃, specifically -150 ℃ to -5 ℃, more specifically -150 ℃ to -20 ℃. In the above range 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, polybutadiene or polysiloxane having the above glass transition temperature.

Polyalkyl (meth) acrylates are polymethylacrylate, polyethylacrylate, polypropylacrylate, polybutylacrylate, polyisopropylacrylate, polyhexyl acrylate, polyhexyl methacrylate, polyethylhexyl acrylate And polyethylhexyl methacrylate, polysiloxane, but are not necessarily limited thereto.

The polysiloxane can be, for example, an organosiloxane (co) polymer. The organosiloxane (co) polymer may be one which is not crosslinked, or a crosslinked (co) polymer may be used. Crosslinked organosiloxane (co) polymers can be used for impact resistance and colorability. This is a crosslinked organosiloxane, specifically, crosslinked dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane or a mixture of two or more thereof may be used. The refractive index of 1.41 to 1.50 can be adjusted by using a form in which two or more organosiloxanes are copolymerized.

The crosslinking state of the organosiloxane (co) polymer can be judged with the degree of dissolution by various organic solvents. The deeper the crosslinking state, the smaller the degree of dissolution by the solvent. Acetone or toluene may be used as a solvent for determining the crosslinking state. Specifically, the organosiloxane (co) polymer may have a portion which is not dissolved by acetone or toluene. The insoluble component of the organosiloxane copolymer to toluene may be 30% or more.

Additionally, the organosiloxane (co) polymer may further include an alkylacrylate crosspolymer. As the alkyl acrylate crosspolymer, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and the like can be used. For example, n-butyl acrylate or 2-ethylhexyl acrylate having a low glass transition temperature can be used.

Specifically, the glass transition temperature of the shell may be 15 ℃ to 150 ℃, specifically 35 ℃ to 150 ℃, more specifically 50 ℃ to 140 ℃. 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 the glass transition temperature. For example, polymethyl methacrylate (PMMA), polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, polyisopropyl methacrylate, polyisobutyl methacrylate and polycyclohexyl methacrylate It may include one or more of the rate, but is not necessarily limited thereto.

The core may be included in 30 to 99% by weight, specifically 40 to 95% by weight, more specifically 50 to 90% by weight of the organic nanoparticles. In the above range, the folding property of the adhesive film in a wide temperature range may be good. The shell may comprise 1% to 70% by weight, specifically 5% to 60% by weight, more specifically 10% to 50% by weight of the organic nanoparticles. In the above range, the folding property of the adhesive film in a wide temperature range may be good.

The organic nanoparticles may be included in an amount of 0.1 to 20 parts by weight, specifically 0.5 to 10 parts by weight, specifically 0.5 to 5 parts by weight, based on 100 parts by weight of the monomer mixture. In the above range, the modulus of the pressure-sensitive adhesive film at a high temperature can be increased, the folding property at the low temperature to the high temperature of the pressure-sensitive adhesive film can be improved, and the low temperature and / or room temperature viscoelasticity of the pressure-sensitive adhesive film can be excellent.

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

The macromonomer may be polymerized with the monomer mixture to form a hydroxyl group-containing (meth) acrylic copolymer, thereby increasing the strength of the pressure-sensitive adhesive film. The macromonomer may be included in the pressure-sensitive adhesive film to increase the peel strength of the pressure-sensitive adhesive film. For example, the macromonomer may reach the above-described peeling strength even for the adhesive film thickness of 10 μm to 50 μm. Macromonomers have functional groups curable by active energy rays and can be polymerized with hydroxyl group-containing (meth) acrylates and alkyl group-containing (meth) acrylates. Specifically, the macromonomer may be represented by the following Chemical Formula 1:

<Formula 1>

(In Formula 1, R ¹ is hydrogen or methyl group, X is a single bond or a divalent bond group, Y is methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl Polymer chain obtained by polymerizing one or two or more selected from (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. In the said range, sufficient adhesive strength can be obtained, it is excellent in heat resistance, and the fall of the workability by the viscosity raise of an adhesive composition can be suppressed. Macromonomer may have a glass transition temperature of 40 ℃ to 150 ℃, specifically 60 ℃ to 140 ℃, more specifically 80 ℃ to 130 ℃. In the above range, the pressure-sensitive adhesive film can exhibit sufficient cohesion, and can suppress a decrease in stickiness or adhesion.

The divalent bond group is C1 to C10 alkylene group, C7 to C13 arylalkylene group, C6 to C12 arylene group, -NR ^2- (wherein R ² is hydrogen or C1 to C5 alkyl group), COO-,- O-, -S-, -SO ₂ NH-, -NHSO _2- , -NHCOO-, -OCONH, or a group derived from a heterocycle. In addition, the divalent linking group may be represented by the following Formula 1a to Formula 1d:

<Formula 1a>

<Formula 1b>

<Formula 1c>

<Formula 1d>

(In Formula 1a to Formula 1d, * is a linking site of the element)

Macromonomer can use a commercial item. For example, a macromonomer whose terminal is a methacryloyl group and the segment corresponding to Y is methyl methacrylate, the macromonomer where the segment corresponding to Y is the styrene segment, and the segment of the segment Y is the styrene / acryl The macromonomer which is ronitrile, the macromonomer whose segment is butylacrylate, etc. can be used.

The macromonomer may be included in an amount of 0.1 to 20 parts by weight, specifically 0.5 to 10 parts by weight, specifically 0.5 to 5 parts by weight, based on 100 parts by weight of the monomer mixture. In the above range, it is possible to balance the viscoelasticity and modulus and the restoring force of the pressure-sensitive adhesive film, it is possible to prevent the haze rise of the pressure-sensitive adhesive film.

The pressure-sensitive adhesive composition may further include one or more of an initiator, a crosslinking agent, and a silane coupling agent.

The initiator may cure the monomer mixture (partial polymerization) with the (meth) acrylic copolymer or cure the viscous liquid into a film. The initiator may comprise one or more of a photopolymerization initiator and a thermal polymerization initiator.

As a photoinitiator, as long as it can induce the polymerization reaction of the radically polymerizable compound mentioned above in the hardening process by light irradiation etc., any can be used. For example, a benzoin type, a hydroxy ketone type, an amino ketone type, or a phosphine oxide type photoinitiator etc. can be used, Specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether , Benzoin n-butyl ether, benzoin isobutyl ether, 2,2-dimethoxy-2-phenylacetophenone, 2,2'-diethoxy acetophenone, 2,2'-dibutoxy acetophenone, 2-hydride Acetophenone compounds such as oxy-2-methyl propiophenone, pt-butyl trichloro acetophenone, pt-butyl dichloro acetophenone, 4-chloro acetophenone, 2,2'-dichloro-4-phenoxy acetophenone, Dimethylanino acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1one, 2 -Benzyl-2-dimethyl amino-1- (4-morpholino phenyl) -butan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl]- 2- PORINO-PROPAN-1-ON, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4-nonsidiethylaminobenzo Phenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chloro Thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoic acid ester, oligo [2-hydroxy-2-methyl-1- [ 4- (1-methylvinyl) phenyl] propanone], 2,4,6-trimethylbenzoyl- diphenyl-phosphine oxide, etc. are mentioned. In the present application, one or more of the above may be used, but is not limited thereto.

The thermal polymerization initiator is not particularly limited as long as it has the above-described physical properties. For example, a common initiator such as an azo compound, a peroxide compound, or a redox compound can be used. Examples of the azo compound in the above are 2,2-azobis (2-methylbutyronitrile), 2,2-triazobis (isobutyronitrile), 2,2-triazobis (2,4-dimethyl Valeronitrile), 2,2-nitazobis-2-hydroxymethylpropionitrile, dimethyl-2,2-methylazobis (2-methylpropionate) and 2,2-piazobis (4- Methoxy-2,4-dimethylvaleronitrile) and the like, and examples of the peroxide-based compound include inorganic peroxides such as potassium peroxide, ammonium persulfate or hydrogen peroxide; Or diacyl peroxide, peroxy dicarbonate, peroxy ester, tetramethylbutylperoxy neodecanoate, bis (4-butylcyclohexyl) peroxydicarbonate, di (2-ethylhexyl) peroxy carbonate, butylper Oxy neodecanoate, dipropyl peroxy dicarbonate, diisopropyl peroxy dicarbonate, diethoxyethyl peroxy dicarbonate, diethoxyhexyl peroxy dicarbonate, hexyl peroxy dicarbonate, dimethoxybutyl peroxy dicarbonate , Bis (3-methoxy-3-methoxybutyl) peroxy dicarbonate, dibutyl peroxy dicarbonate, dicetyl peroxy dicarbonate, dimyristyl peroxy dicarbonate, 1,1 , 3,3-tetramethylbutyl peroxypivalate, hexyl peroxy pivalate, butyl peroxy pivalate, trimethyl hexanoyl peroxide, dimethyl hydroxybutyl peroxy Odecanoate, amyl peroxyneodecanoate, butyl peroxyneodecanoate, t-butylperoxy neoheptanoate, amylperoxy pivalate, t-butylperoxy pivalate, t-amyl Organic peroxides such as peroxy-2-ethylhexanoate, lauryl peroxide, dilauuroyl peroxide, didecanoyl peroxide, benzoyl peroxide or dibenzoyl peroxide, and the like. Examples of the compound include, but are not limited to, a mixture using a peroxide compound and a reducing agent in combination.

The initiator may be included in an amount of 0.0001 parts by weight to 5 parts by weight, specifically 0.001 parts by weight to 3 parts by weight, and more specifically 0.001 parts by weight to 1 parts by weight, based on 100 parts by weight of the monomer mixture constituting the (meth) acrylic copolymer. In this range, the curing reaction can proceed completely, remaining amount of initiator can remain to prevent the transmittance from decreasing, and also it is possible to lower the bubble generation and have excellent reactivity.

The crosslinking agent may increase the degree of crosslinking of the pressure-sensitive adhesive composition to increase the mechanical strength of the pressure-sensitive adhesive film. The crosslinking agent may comprise a polyfunctional (meth) acrylate that is curable with active energy rays. In an embodiment, the crosslinking agent is 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentylglycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Neopentylglycol adipate di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate, di (meth ) Acryloxy ethyl isocyanurate, allylated cyclohexyl di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, dimethylol dicyclopentanedi (meth) acrylate, ethylene oxide modified hexahydrophthalic acid Di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentylglycol modified trimethylpropane di (meth) acrylate, adamantane di (meth) acrylic Bifunctional acrylates such as late or 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene and the like; Trimethylolpropane tri (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) acryloxyethyl isocyanurate; Tetrafunctional acrylates such as diglycerin tetra (meth) acrylate or pentaerythritol tetra (meth) acrylate; 5-functional acrylates, such as dipentaerythritol penta (meth) acrylate; And dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate or urethane (meth) acrylate (ex. Isocyanate monomers and trimethylolpropane tri (meth) acrylate 6 functional acrylates such as reactants, etc., but are not limited thereto.They may be used singly or in mixture of two or more. Preferably, the crosslinking agent may be a polyfunctional (meth) acrylate of a polyhydric alcohol. The crosslinking agent may be included in an amount of 0.001 to 5 parts by weight, specifically 0.003 to 3 parts by weight, specifically 0.005 to 1 part by weight, based on 100 parts by weight of the monomer mixture constituting the (meth) acrylic copolymer. There is an effect of excellent adhesion and increased reliability in the above range.

The pressure-sensitive adhesive composition may further include a silane coupling agent. The silane coupling agent can be made reliable because there is no bubble or peeling even if the pressure-sensitive adhesive film is left for a predetermined time at a high temperature and high humidity in a frame having a predetermined radius of curvature. Silane coupling agents can be used conventionally known to those skilled in the art. For example, 3-glycidoxy propyl trimethoxysilane, 3-glycidoxy propyl triethoxysilane, 3-glycidoxy propylmethyl dimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltri Silicon compounds having an epoxy structure such as methoxysilane; Polymerizable unsaturated group-containing silicon compounds such as vinyl trimethoxy silane, vinyl triethoxy silane, and (meth) acryloxy propyl trimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl methyl dimethoxysilane ; And 3-chloro propyl trimethoxysilane and the like may include one or more selected from the group consisting of, but is not limited thereto. Preferably, a silane coupling agent having an epoxy structure can be used. The silane coupling agent may be included in an amount of 0.01 to 3 parts by weight, specifically 0.01 to 1 part by weight, based on 100 parts by weight of the monomer mixture constituting the (meth) acrylic copolymer. In the above range, reliability can be ensured in the bending state at the high temperature and high humidity described above, and the difference in peel strength between low temperature, room temperature, and high temperature can be low.

The pressure-sensitive adhesive composition may optionally include a curing accelerator, an ionic liquid, a lithium salt, an inorganic filler, a softener, a molecular weight regulator, an antioxidant, an antioxidant, a stabilizer, a tackifying resin, a modified resin (polyol resin, a phenol resin, an acrylic resin, a polyester resin). , Polyolefin resins, epoxy resins, epoxidized polybutadiene resins, etc.), leveling agents, antifoaming agents, plasticizers, dyes, pigments (colored pigments, sieving pigments, etc.), treatment agents, sunscreen agents, fluorescent brighteners, dispersants, thermal stabilizers Conventional additives such as light stabilizers, ultraviolet absorbers, antistatic agents, flocculants, lubricants and solvents may be further included.

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

The pressure-sensitive adhesive composition may be prepared by partially polymerizing a monomer mixture for a (meth) acrylic copolymer having a hydroxyl group with an initiator and including one or more of additional macromonomers and organic nanoparticles. The above-mentioned initiator, crosslinking agent, silane coupling agent, and additives may be further included. Alternatively, the pressure-sensitive adhesive composition may be prepared by partially polymerizing a mixture including at least one of a monomer mixture, a macromonomer, and an organic nanoparticle for a (meth) acrylic copolymer having a hydroxyl group, and including an additional initiator. The crosslinking agent, silane coupling agent, additive, etc. which were mentioned above may further be included. Partial polymerization can include solution polymerization, suspension polymerization, photopolymerization, bulk polymerization, or emulsion polymerization. Specifically, solution polymerization may be performed at 50 ° C. to 100 ° C. by adding an initiator to the monomer mixture. As an initiator, photoinitiators, such as an acetophenone type and 1-hydroxycyclohexyl phenyl ketone containing 2, 2- dimethoxy- 2-phenylacetophenone etc. can be used. Partial polymerization may be polymerized at 25 ° C. with a viscosity of 1,000 cPs to 10,000 cPs, specifically 4,000 cPs to 9,000 cPs. The adhesive film can be manufactured by a conventional method. For example, the pressure-sensitive adhesive composition may be prepared by coating a release film and curing the same. 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.

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

In one embodiment, the optical film provides certain optical functions of the display device, such as polarization, optical compensation, display quality improvement, and / or conductivity, wherein the optical film is a window film, a window, a polarizer, a color filter, a retardation film. , Elliptical polarizing film, reflective polarizing film, antireflection film, compensation film, brightness enhancement film, alignment film, light diffusion film, glass scattering prevention film, surface protection film, OLED element barrier layer, plastic LCD substrate, ITO (indium tin oxide) And transparent electrode films including fluorinated tin oxide (FTO), aluminum dopped zinc oxide (AZO), carbon nanotube (CNT), Ag nanowires, graphene, and the like. The manufacturing method of the optical film can be easily manufactured by those skilled in the art to which the present invention pertains.

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

In another embodiment, the optical film is an optically transparent optical film, the optical member including the optical film and the adhesive film may serve as a support layer of the display element. For example, the display element may include a window film or the like. The window film may include the optical member and a window coating layer (eg, a silicon based coating layer) formed on the optical member. The window film can be a flexible window film. Specifically, the optical film has a total light transmittance of 90% or more in the visible region, and includes a cellulose resin including triacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, and the like. Formed of at least one of a poly (meth) acrylate resin, a cyclic olefin polymer resin, an acrylic resin, a polyamide resin, including a polyester resin, a polycarbonate resin, a polyimide resin, a polystyrene resin, a polymethylmethacrylate, and the like It may be a film. The optical film may have a thickness of 10 μm to 100 μm, specifically 20 μm to 75 μm, and more specifically 30 μm to 50 μm. It can be used as the support layer of the display element in the above range.

The optical member may be an optical member having two layers including an optical film and an adhesive film formed on one surface of the optical film. Alternatively, the optical member may include two or more optical films, and at least two or more of the optical films may be three or more film laminates laminated by the adhesive film of the present invention.

In one embodiment, the optical member may be a first optical film, a second optical film, and a three-layer film laminate in which the first optical film and the second optical film are laminated by the adhesive film of the present invention. Each of the first optical film and the second optical film may be a film formed of at least one of polyethylene terephthalate resin, polycarbonate resin, polyimide resin, poly (meth) acrylate resin, cyclic olefin polymer resin, and acrylic resin. Can be. Each of the first optical film and the second optical film has a thickness of 10 μm to 100 μm, specifically 20 μm to 75 μm, more specifically 30 μm to 50 μm, and the adhesive film has a thickness of 10 μm to 100 μm. This can be In the above range, it can be effective to maximize the impact resistance while maintaining good folding properties. The first optical film and the second optical film may be the same or different in thickness and material, respectively.

The optical display device of the present invention may include the adhesive film of the present invention. The optical display device may include an organic light emitting display device, a liquid crystal display device 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 exemplary embodiment of the present invention will be described with reference to FIG. 1. 1 is a cross-sectional view of a flexible display device according to an embodiment of the present invention.

Referring to FIG. 1, the flexible display apparatus 100 according to an exemplary embodiment of the present invention may include a display unit 110, an adhesive layer 120, a polarizing plate 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 apparatus 100 and may include a substrate and an optical element including an OLED, an LED, a quantum dot light emitting diode (QLED), or an LCD element formed on the substrate. Although not shown in FIG. 1, the display unit 110 may include a lower substrate, a thin film transistor, an organic light emitting diode, a planarization layer, a protective film, and an insulating film.

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

The touch screen panel 140 generates an electrical signal by detecting a change in capacitance generated when a human body or a conductor such as a stylus touches the touch screen panel. The display 110 may be driven by the signal. The touch screen panel 140 is formed by patterning a flexible and conductive conductor, and may include a second sensor electrode formed between the first sensor electrode and the first sensor electrode to cross the first sensor electrode. have. The conductor for the touch screen panel 340 may include, but is not limited to, metal nanowires, conductive polymers, carbon nanotubes, and the like.

1 illustrates that the polarizing plate 130 and the touch screen panel 140 are laminated by an adhesive film or an adhesive film, but the polarizing plate 130 and the touch screen panel (including the polarizer or the polarizing plate in the touch screen panel 140). 140 may be integrated.

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

Although not shown in FIG. 1, the adhesive film of the embodiment of the present invention is further formed between the polarizing plate 130 and the touch screen panel 140 and / or between the touch screen panel 140 and the flexible window film 150. Bonding between the screen panel and the flexible window film can be strengthened.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, this is presented as a preferred example of the present invention and should not be construed as limiting the present invention by any means.

Production Example

By emulsion polymerization method, organic nanoparticles were prepared. The core is polybutylacrylate, the shell is polymethylmethacrylate, the shell is 35% by weight of the organic nanoparticles, the core is 65% by weight of the organic nanoparticles, the average particle diameter is 100nm, the organic nanoparticles having a refractive index of 1.48 Was prepared.

Example 1

To 100 parts by weight of the mixture of hydroxyl group-containing (meth) acrylate and alkyl group-containing (meth) acrylate in Table 1, 5 parts by weight of organic nanoparticles of the preparation, 0.005 parts by weight of the initiator Irgacure651 was well mixed in the reactor. The monomer mixture was partially polymerized by exchanging dissolved oxygen in the reactor with nitrogen gas and then irradiating with ultraviolet light using a low pressure mercury lamp for a few minutes to prepare a viscous liquid having a viscosity of 5,000 cps at 25 ° C. 0.3 weight part of initiator Irgacure184, 0.01 weight part of crosslinking agents, and 0.1 weight part of silane coupling agents 3-glycidoxy propyl trimethoxysilane (KBM-403) were added to a viscous liquid, and the adhesive composition was mixed. Was prepared. The pressure-sensitive adhesive composition was applied to a PET (polyethylene terephthalate) film which is a release film, and irradiated with an ultraviolet light amount of 2000 mJ / cm ² to prepare a pressure-sensitive adhesive sheet of the pressure-sensitive adhesive film and PET film.

Example  2 to Example  5

Except for changing the configuration of the pressure-sensitive adhesive composition in Example 1 to prepare a pressure-sensitive adhesive sheet of the pressure-sensitive adhesive film and PET film in the same manner.

Comparative Example 1

Except for changing the configuration of the pressure-sensitive adhesive composition in Example 1 to prepare a pressure-sensitive adhesive sheet of the pressure-sensitive adhesive film and PET film in the same manner.

The physical properties of Table 1 below were evaluated for the pressure sensitive adhesive sheets prepared in Examples and Comparative Examples, and the results are shown in Table 1 below.

(1) Modulus: Viscoelasticity was measured under auto strain conditions at a shear rate of 1 rad / sec and strain of 1% using a rheometer (Anton Paar MCR-501). After the release film was removed from the pressure-sensitive adhesive sheet, a plurality of 50 μm thick adhesive films were laminated and stacked to a thickness of 500 μm, and the laminate was punched out using an 8 mm diameter perforator to be used as a specimen. The measurement was performed while raising the temperature at a temperature rising rate of 5 ° C./min from −60 ° C. to 90 ° C. with a load of 300 gf applied to the specimen using an 8 mm jig, and −20 ° C., 25 ° C. and 80 ° C. Each modulus was obtained at.

(2) Glass transition temperature of the adhesive film: After removing the release film from the adhesive sheet, the glass transition temperature of the adhesive film was measured using a DSC Q20 of TA Instrument for the adhesive film having a thickness of 50㎛. After removing the release film from the adhesive sheet, the adhesive film of 0.005g was placed on the pan and sealed to raise the temperature of the adhesive film to about 100 ° C. at a rate of 10 ° C./minute, and then maintained equilibrium for 5 minutes, and 10 ° C./min. Lower the temperature to about -120 ℃ at a rate of 10 minutes and hold. After the data of the endothermic transition curve when the temperature was raised from −120 ° C. to about 160 ° C. at a rate of 10 ° C./min was obtained, the inflection point of the endothermic transition curve was determined as the glass transition temperature.

(3) Folding evaluation: By using the pressure-sensitive adhesive film prepared in Example and Comparative Example, as shown in Figure 3, by sequentially laminating the display unit, the first adhesive film, the optical film, the second adhesive film, the window film A specimen simulating a five-layer flexible display device was manufactured.

-Display unit: Replaced with the first PET film (thickness: 100㎛, Cosmoshine TA015, Toyobo)

-First adhesive film: adhesive film of Example and Comparative Example (thickness: 50㎛)

-Optical film (polarizing plate, touch screen panel): replaced by second PET film (thickness: 50㎛)

-Second adhesive film: adhesive film of Example and Comparative Example (thickness: 50㎛)

-Window film: replaced by the third PET film (thickness: 125㎛)

The prepared specimens were cut to a size of width x length (100 cm x 160 cm) to prepare folding test specimens, and the prepared specimens were treated in an autoclave at 50 ° C. and 3.6 bar pressure for 1000 sec. As shown in Fig. 3, the specimen is fixed to the folding test measuring device (COVOTEC Co., CFT series) to be folded in the window film direction so that the half point of the longitudinal length of the specimen is folded, and the radius of curvature is 180 mm. Detachment or foaming was repeated by folding and squeezing at ° C at 30 cycles per minute at -20 ° C and 60 ° C and 93% relative humidity (bending the specimen once in half and releasing it in 1 cycle). The maximum number of folding without was evaluated. The absence of bubbles is a case where the bubble generation area is 0%, and the bubble generation area is analyzed by Mountech's Mac-view software by analyzing an image measured by an optical microscope (Olympus, EX-51). Calculated as the ratio of the total area of bubble generation to.

(4) Resilience: A PET release film was released to the adhesive sheets of Examples and Comparative Examples to obtain an adhesive film. Resilience was evaluated by TA.XT_Plus Texture Analyzer (Stable Micro System) at 25 ° C.

Referring to FIG. 4, a first PET film is formed by adhering two end portions of a PET (polyethylene terephthalate) film (thickness: 75 μm) having a length x width (50 mm × 20 mm) by a horizontal x vertical (20 mm x 20 mm) adhesive film. The specimen was laminated in the order of / adhesive film / second PET film and the contact area between the PET film and the adhesive film became horizontal x vertical (20 mm x 20 mm). The jig was fixed to both ends of the PET film of the specimen. The contact area of each of the first PET film, the second PET film and the jig was such that the length x width (15 mm x 20 mm). One jig is fixed at 10 MPa and the other jig is pulled up to 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 1000% of the thickness of the adhesive film. After reaching for 10 seconds, and then restored to the same speed (300mm / min) to the pulled speed. After the pressure-sensitive adhesive film was stretched to 1000% of the initial thickness of the pressure-sensitive adhesive film, the length of the pressure-sensitive adhesive film increased when X kPa was applied to the pressure-sensitive adhesive film was X ₁ . Referring to Figure 5, the length of the pressure-sensitive adhesive film X-axis, the force applied to the pressure-sensitive adhesive film as a Y-axis was obtained. The restoring force was calculated according to Equation 1 above.

(5) Peeling strength: A corona treatment was performed on a PET (polyethylene terephthalate) film having a width x length x thickness (150 mm x 25 mm x 75 μm) using a corona treatment (Two doses of corona twice at a dose of 78 doses). Corona-treated surfaces of the PET film were laminated on both sides of an adhesive film (width x length x thickness, 100mmx25mmx50㎛), respectively, to prepare a specimen shown in FIG. The specimens were autoclaved at pressure of 3.5 bar at 50 ° C. for 1000 seconds and the specimens were fixed in a TA.XT_Plus Texture Analyzer (Stable Micro System). Referring to (b) of FIG. 2, T-Peel peel strength was measured when one PET film was fixed at 25 ° C. and the other PET film was pulled at a speed of 50 mm / min in a TA.XT_Plus Texture Analyzer. .

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 n-BA (part by weight) 5 10 0 0 0 0 2-EHA (parts by weight) 75 75 80 75 80 65 4-HBA (parts by weight) 15 10 20 25 20 0 3-HPA (parts by weight) 5 5 0 0 0 0 2-HEA (parts by weight) 0 0 0 0 0 35 Organic nanoparticles
(Part by weight) 5 3 3 3 0 0 Macromonomer
(Part by weight) 0 0 0 0 5 0 Irgacure651
(Part by weight) 0.005 0.005 0.005 0.005 0.005 0.005 Irgacure184
(Part by weight) 0.3 0.3 0.3 0.3 0.3 0.3 Crosslinking agent
(Part by weight) 0.01 0 0 0 0 0 Silane coupling agent
(Part by weight) 0.1 0.1 0 0 0.1 0 Modulus
(kPa) ＠ -20 ℃ 140 105 74 87.7 97 695 ＠ 25 ℃ 42 27 29 38.1 34 38 ＠ 80 ℃ 30 18 25 27.3 18 29 ＠ 80 ℃ Modulus: ＠ -20 ℃ Modulus 1: 4.67 1: 5.83 1: 2.96 1: 3.21 1: 5.39 1: 23.97 Glass transition temperature (℃) -56.1 -57.2 -48.4 -47.6 -53.2 -30.9 Folding rating
(＠ -20 ℃, time) 200,000 times 200,000 times 200,000 times 60,000 times 150,000 times 10,000 times Folding rating
(＠ 60 ℃ and 93% relative humidity, times) 110,000 times 130,000 times 100,000 times 50,000 times 120,000 times 1000 times Restorative force (＠ 25 ℃,%) 92 86 85 88 90 89 Peel strength
(＠ 25 ℃, gf / in) 1428 1324 1136 1468 1333 1700

n-BA: n-butyl acrylate, 2-EHA: 2-ethylhexyl acrylate (LG Chemical Co., Ltd.), 4-HBA: 4-hydroxybutyl acrylate (Osaka Yugisa Co., Ltd.), 3-HPA: 3-Hyde Hydroxybutyl acrylate, 2-HEA: 2-hydroxyethyl acrylate (Japan Catalyst Co., Ltd.), macromonomer: AA-6 (Toakosei), crosslinking agent: 1,6-hexanediol diacrylate, silane coupling agent: 3 Glycidoxypropyltrimethoxysilane

As shown in Table 1, the pressure-sensitive adhesive film of the present invention has good folding properties even at low temperatures, and especially when laminated on a plurality of display elements and optical films, the folding properties were good at low temperatures and high temperatures and high humidity. In addition, the pressure-sensitive adhesive film of the present invention can be excellent in reliability because the difference in the modulus at low and high temperatures. In addition, the adhesive film of the present invention had a high peel strength on the optical film.

Simple modifications and variations of the present invention can be easily made by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (21)

A (meth) acrylic copolymer having a hydroxyl group formed of a monomer mixture comprising a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate,
It is an adhesive film whose glass transition temperature is -35 ℃ or less,
Of the first PET film (thickness: 100 m), the adhesive film (thickness: 50 m), the second PET film (thickness: 50 m), the adhesive film (thickness: 50 m), and the third PET film (thickness: 125 m) A 5-layered test piece (horizontal x vertical) (sequentially stacked) (100 cm x 160 cm) is laminated to the third PET film in such a way as to fold a point that becomes half of the longitudinal length of the specimen to the folding test measuring instrument. And bending at 180 ° to obtain a 3 mm radius of curvature at a rate of 30 cycles per minute (i) -20 ° C, ii) bending at one or more of the conditions of 60 ° C and 93% relative humidity (the When the test piece was repeatedly bent and halved once in 1 cycle), the number of times of folding until peeling, cracking or foaming between the adhesive film and the PET film was 50,000 or more times.
The pressure-sensitive adhesive film is a modulus of the modulus at 80 ℃: -20 ℃ 1: 1 to 1:10,
The pressure-sensitive adhesive film may include a monomer mixture including the hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate or a (meth) acrylic copolymer having the hydroxyl group prepared by partially polymerizing the monomer mixture; It is formed of a pressure-sensitive adhesive composition comprising at least one of a macromonomer, organic nanoparticles,
The hydroxyl group-containing (meth) acrylate in the monomer mixture is 10 to 30% by weight, wherein the alkyl group-containing (meth) acrylate is included in 70% by weight to 90% by weight, the adhesive film.
The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive film has a glass transition temperature of -60 ° C to -35 ° C.
The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive film has a restoring force of 60% or more at 25 ° C.
<Equation 1>
Resilience = (1-(X ₁ ) / (X ₂ )) x 100
(Equation 1, when the both ends of the PET (polyethylene terephthalate) film, respectively, the first end, the second end, the first end of the first PET film / adhesive film (width x length, 20mm x 20mm) / In a state in which a specimen was bonded to the second end of the second PET film in order, and then fixed to each end of the first PET film and the second PET film, the jig was fixed to one end of the second PET film, and one jig was fixed at 10 MPa. Pull the other jig at a speed of 300 mm / min at 25 ° C. to reach a length (10 times the thickness, X _2, unit: μm) of the initial thickness (X ₀ ) (unit: μm) of the adhesive film. After maintaining for 10 seconds, when the length of the pressure-sensitive adhesive film X-axis, the force applied to the pressure-sensitive adhesive film to obtain a graph, when the pressure-sensitive adhesive film stretched to the length of 1000% of the thickness of the pressure-sensitive adhesive film pulled 0 kPa is applied to the pressure-sensitive adhesive film by restoring at the same speed (300 mm / min) as the speed. A) The increase in the pressure-sensitive adhesive film when the length X ₁ (㎛ unit).
delete The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive film has a modulus of 10 kPa to 500 kPa at -20 ° C.
delete The pressure-sensitive adhesive film of claim 1, wherein the hydroxyl group-containing (meth) acrylate comprises an alkyl group-containing (meth) acrylate having 2 to 4 carbon atoms having at least one hydroxyl group.
The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive composition further comprises an initiator.
The pressure-sensitive adhesive film of claim 1, wherein the organic nanoparticles have an average particle diameter of 10 nm to 400 nm.
The method of claim 1, wherein the organic nanoparticles are core-shell particles,
The core and the shell to satisfy the following formula 2, the adhesive film:
<Equation 2>
Tg (c) <Tg (s)
(In Formula 2, Tg (c) is the glass transition temperature (unit: ° C) of the core, Tg (s) is the glass transition temperature (unit: ° C) of the shell).
The pressure-sensitive adhesive film of claim 1, wherein the organic nanoparticles are included in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the monomer mixture.
The pressure-sensitive adhesive film of claim 1, wherein the macromonomer is included in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the monomer mixture.
The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive film further comprises at least one of a crosslinking agent and a silane coupling agent.
The pressure-sensitive adhesive film of claim 1, wherein the pressure-sensitive adhesive film has a haze of 2% or less at a wavelength of 380 nm to 780 nm.
An optical film, and an adhesive film formed on at least one surface of the optical film,
The adhesive film is to include the adhesive film of claim 1, the optical member.
The optical member according to claim 15, wherein the optical member is a first optical film, a second optical film, and a three-layer film laminate in which the first optical film and the second optical film are laminated by the adhesive film. .
The method of claim 16, wherein the first optical film and the second optical film is one of polyethylene terephthalate resin, polycarbonate resin, polyimide resin, poly (meth) acrylate resin, cyclic olefin polymer resin, acrylic resin Optical member which is a film formed from the above resin.
The optical member of claim 16, wherein each of the first optical film and the second optical film has a thickness of 10 μm to 100 μm, and the adhesive film has a thickness of 10 μm to 100 μm.
The optical member of claim 16, wherein the optical member is for a window film.
An optical display device comprising the adhesive film of claim 1.
The optical member according to any one of claims 15 to 19; And a window coating layer formed on the optical member.

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