KR102040299B1 - Protective film for window film, optical member comprising the same and display apparatus comprising the same - Google Patents

Abstract

A first layer, a pressure-sensitive adhesive layer, a second layer and a hard coating layer is a protective film for a window film sequentially laminated, the first layer is a film formed of a thermoplastic polyurethane, the first layer has a elastic modulus of 1GPa at 25 ℃ The second layer has an elastic modulus of 1 GPa to 6 GPa at 25 ° C., and the hard coating layer has an elastic modulus of 2 GPa or less at 25 ° C., and has a radius of curvature of 1 mm to 3 mm. Provided is a protective film for a window film having an bending stiffness of 20 N or less when bent in the direction, an optical member including the same, and a display device including the same.

Description

Protective film for a window film, an optical member including the same, and a display device including the same {PROTECTIVE FILM FOR WINDOW FILM, OPTICAL MEMBER COMPRISING THE SAME AND DISPLAY APPARATUS COMPRISING THE SAME}

The present invention relates to a protective film for a window film, an optical member including the same, and a display device including the same.

As the development of a foldable display device becomes visible, a protective film for protecting a foldable display device, in particular a window film, from an external environment is being developed. Conventional protective films have prioritized the protection and rework characteristics from the external environment, but it has been difficult to apply to the foldable display device because it does not implement the folding characteristics.

In general, the protection of the external environment can be achieved by hardening the combination of organic / inorganic particles and resins having a hardened density, improved hardenability, and rigid structure. On the other hand, the folding properties can be realized by reducing the curing density and making a soft coating through crosslinking with a resin having good flexibility.

Background art of the present invention is described in Korea Patent Publication No. 2010-0055160.

The problem to be solved by the present invention is to provide a protective film for a window film excellent in both scratch resistance and folding resistance.

In the protective film for window film of the present invention, the first layer, the adhesive layer, the second layer, and the hard coating layer are sequentially laminated, and the first layer is a film formed of thermoplastic polyurethane, and the first layer is elastic at 25 ° C. The modulus is 1 GPa or less, the second layer has an elastic modulus of 1GPa to 6GPa at 25 ° C, the hard coating layer has an elastic modulus of 2GPa or less at 25 ° C, and a radius of curvature of 1 mm to 3 mm. When bending in the direction of the first layer, the bending stiffness may be 20 N or less.

The optical member of the present invention may include a window film and a protective film for a window film of the present invention formed on the window film.

The display device of the present invention may include the protective film for a window film of the present invention.

The present invention provides a protective film for a window film which is excellent in both scratch resistance and folding property.

1 is a cross-sectional view of a protective film for a window film according to an embodiment of the present invention.
2 is a cross-sectional view of a protective film for a window film according to another embodiment of the present invention.
3 is a conceptual diagram of bending stiffness evaluation in the present invention.

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", "directly on" or "directly formed" means not intervening in the other structures.

As used herein, "(meth) acryl" refers to acrylic and / or methacryl.

In the present specification, "Shore hardness" means a value measured by a shore hardness tester according to JIS K7311.

As used herein, "elongation" means a value measured by the Instron instrument method in accordance with JIS K7311.

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

In the present specification, the "modulus" of the adhesive layer is storage modulus, and is used as an auto strain condition at a shear rate of 1 rad / sec and strain of 1% using ARES (Anton Paar Co., Ltd. MCR-501), a dynamic viscoelasticity measuring device. Viscoelasticity was measured. After removing the release film, the pressure-sensitive adhesive layer was laminated to a thickness of 500 μm, and the laminate was punched out using a perforator having a diameter of 8 mm to be used as a specimen. The measurement was performed at a temperature rising rate of 5 ° C./min in a temperature range of −60 ° C. to 90 ° C. using a jig of 8 mm, and modulus was recorded at −20 ° C., 25 ° C. and 80 ° C.

The "elastic modulus" of the first layer herein is the indentation modulus. The elastic modulus was placed on a 2T thick soda lime glass plate at 25 ° C., and the first layer was pressurized for 20 seconds with a constant force of 300 mN with a straight diamond pyramid-shaped micro indentor (Vicker particle) having a square base. Creep for seconds and relax for 20 seconds to measure elastic modulus. Elastic modulus can be measured using the HM2000LT Micro Indentor (Fisher), but is not limited thereto.

In this specification, the "elastic modulus" of each of the second layer and the hard coating layer is an indentation modulus. It can measure in the same way as the said 1st layer.

"Elastic modulus" herein means a value at 25 ° C.

Hereinafter, a protective film for a window film (hereinafter referred to as a "protective film") according to an embodiment of the present invention will be described with reference to FIG. 1. 1 is a cross-sectional view of a protective film according to an embodiment of the present invention.

Referring to FIG. 1, the protective film 100 may include a first layer 111, an adhesive layer 112, a second layer 113, and a hard coating layer 120. In the protective film 100, a first layer 111, an adhesive layer 112, a second layer 113, and a hard coating layer 120 are sequentially stacked, and the adhesive layer 112 is formed of the first layer 111. The hard coat layer 120 is formed directly on the second layer 113, respectively, and is directly formed on the second layer 113. The "directly formed" means that no other adhesive layer, adhesive layer or adhesive layer is interposed between the layers.

The first layer 111 is a thermoplastic polyurethane (TPU) film and has an elastic modulus of 1 GPa or less, and the second layer 113 has a larger elastic modulus than the first layer. The elastic modulus is 1GPa to 6GPa, and the hard coating layer 120 may have an elastic modulus of 2 GPa or less. In general, a laminate in which a plurality of films or layers are stacked has a trade off relationship between scratch resistance and folding resistance due to external impact. According to the present invention, scratch resistance and folding resistance can be simultaneously obtained by controlling the elastic modulus of the first layer, the second layer, and the hard coating layer.

When the protective film of the present invention is bent in the first layer direction with a radius of curvature of 1 mm to 3 mm, bending stiffness may be 20 N or less. Bending stiffness is a force applied to the protective film when the protective film is bent at a radius of curvature of 1 mm to 3 mm in the direction of the first layer. The greater the bending stiffness, the greater the force applied to the protective film when the protective film is bent to a radius of curvature of 1 mm to 3 mm, causing cracks in one or more of the first layer, second layer and / or hard coating layer when the protective film is bent. . In particular, the protective film of the present invention can be prevented from cracking even when the entire protective film is bent without separation between the first layer, the adhesive layer, the second layer and the hard coating layer. Bending stiffness can be measured according to FIG. 3.

In addition, the protective film of the present invention can improve the scratch resistance in the hard coating layer. If only the elastic modulus of the hard coat layer is increased, scratch resistance can be increased, but cracks are more likely to occur when the protective film is bent in the direction of the first layer.

Particularly, in the present invention, when the thickness of the hard coating layer is 1 μm or more and less than 10 μm, specifically 1 μm or more and 5 μm or less, the elastic modulus of the first layer and the second layer falls within the above range, thereby reducing the bending stiffness and the scratch resistance. Could make it good.

EMBODIMENT OF THE INVENTION Hereinafter, the protective film of this invention is demonstrated in detail.

The laminate composed of the first layer 111, the adhesive layer 112, and the second layer 113 supports the hard coat layer 120.

The first layer 111 supports the adhesive layer, the second layer, and the hard coating layer.

The first layer 111 may be formed of thermoplastic polyurethane. When the first layer is a film made of a material other than thermoplastic polyurethane, the bending stiffness may be increased and thus the folding property may not be good. Even when the first layer is formed of thermoplastic polyurethane, peeling with the adhesive layer does not occur when the protective film is bent. The present invention forms the first layer of thermoplastic polyurethane and further has an elastic modulus of 1 GPa or less, for example 0.01 GPa to 1 GPa. In the above range, even if the hard coating layer having the elastic modulus described below is formed, the bending stiffness of the protective film can be lowered to improve the folding property and the scratch resistance. As described below, the elastic modulus of the hard coat layer may affect the bending of the protective film in the first layer direction. The elastic modulus of the first layer can be obtained by adjusting the change in the production of the thermoplastic polyurethane film, the change of the extrusion method, and other methods.

The first layer 111 may have a thickness of 100 μm or more and 200 μm or less and a Shore hardness of 95A to 98A. The first layer having the thickness and the Shore hardness range can be used in the foldable display device by lowering the radius of curvature of the protective film together with the second layer and the hard coating layer to increase flexibility, and the hard coating layer has a thin thickness. For example, even if it has 1 micrometer or more and less than 10 micrometers, specifically, 1 micrometer or more and 5 micrometers or less, impact resistance and scratch resistance can be improved, the damage of an OLED panel etc. can be prevented, and a protective film can be made thin.

The first layer 111 may be formed as a coating layer or a film, and may be formed by a thermoplastic polyurethane alone, or may further include an additive, such as a stabilizer, to prevent yellowing in the thermoplastic polyurethane. The thermoplastic polyurethane is not particularly limited as long as it is a material capable of satisfying Shore hardness in the thickness range. For example, thermoplastic polyurethanes can be derived from bifunctional or higher polyfunctional polyols and bifunctional or higher polyfunctional isocyanates, and may further comprise chain extenders. The polyol may include one or more of an aromatic polyol, an aliphatic polyol, and an alicyclic polyol. Preferably, it may be a polyurethane formed of at least one of an aliphatic polyol and an alicyclic polyol. In this case, yellowing of the protective film may be less. The polyol may include, but is not limited to, one or more of polyester diols, polycarbonate diols, polyolefin diols, polyether diols, polythioether diols, polysiloxane diols, polyacetal diols, polyesteramide diols. Multifunctional isocyanates may include any aliphatic, cycloaliphatic or aromatic isocyanates. Chain extenders can include diols such as aliphatic diols, amino alcohols, diamines, hydrazines, hydrazides or mixtures thereof. The Shore hardness of the thermoplastic polyurethane can be obtained by varying the block level amount of the polyfunctional isocyanate and / or chain extender in the thermoplastic polyurethane or by controlling the polymerization time. In preparing the thermoplastic polyurethane, a catalyst for promoting the formation of a bond of the urethane may further include a tin compound such as tin salt of carboxylic acid, an amine such as dimethylcyclohexylamine or triethylenediamine. Other conventional components such as surfactants, flame retardants, fillers, pigments and the like may also be included in the production of thermoplastic polyurethanes.

The first layer 110 may have a yellow index YI of 2.0 or less, for example, 0.1 or more and 1.5 or less, and a color difference change ΔE of 3.0 or less, for example, 0.1 or more and 2.0 or less. In the above range, it can be used as a protective film, there may be a light stability effect. The color difference change ΔE may be defined by Equation 1 below:

<Equation 1>

△ E = [(△ L * ) 2 + (△ a *) 2 + (△ b *) 2] 1/2

In Formula 1, ΔL * is (L *) _2- (L *) ₁ , Δa * is (a *) _2- (a *) ₁ , and Δb * is (b *) _2- (b *) ₁ , (L *) ₂ is the L * value (brightness-related value) of the first layer after light resistance measurement, (L *) ₁ is L * of the first layer before light resistance measurement, and (a * ) ₂ is a * of the first layer after light resistance measurement, (a *) ₁ is a * of the first layer before light resistance measurement, (b *) ₂ is b * of the first layer after light resistance measurement, (b *) ₁ is b * of the first layer before light resistance measurement). In this case, the measurement of light resistance means that the first layer is treated under a UV-B light source for 72 hours. L *, a * and b * can be measured with a colorimeter Konica minlota CM-3600A.

The first layer 111 may have a refractive index of 1.40 to 1.65, specifically 1.45 to 1.60. In the above range, the refractive index is appropriate relative to the adhesive layer may be good optical properties of the protective film, it is possible to improve the screen visibility when laminated on the window film.

The first layer 111 may have a light transmittance of 85% to 100%, specifically 90% to 99% at a wavelength of 550nm. In the above range, it can be used in the display device.

The second layer 113 may be formed between the adhesive layer 112 and the hard coating layer 120 to act as a buffer when the protective film is bent and to improve scratch resistance.

The second layer may have a larger elastic modulus than the first layer, and the elastic modulus may be 1 GPa to 6 GPa. Within this range, it is possible to lower the bending stiffness of the protective film and to set the scratch resistance. When the second layer has the same or smaller elastic modulus than the first layer, the bending stiffness of the protective film may be lowered, but the scratch resistance may be lowered when the hard coat layer has the following elastic modulus range. When the elastic modulus of the second layer is less than 1 GPa, the bending stiffness of the protective film can be lowered to improve the folding property, but since the second layer is formed directly with the hard coating layer, a hard coating layer having the following elastic modulus is formed. In this case, scratch resistance of the protective film may be lowered. When the elastic modulus of the second layer exceeds 6 GPa, the folding property may be poor. Preferably, the second layer may have an elastic modulus of 2 GPa to 6 GPa. Specifically, when the second layer is a film made of a polyester resin such as polyethylene terephthalate, the elastic modulus may be 1 GPa to 5 GPa, and when the film is made of a polyimide resin, the elastic modulus may be 3 GPa to 6 GPa. The elastic modulus of the second layer can be obtained by adjusting the change of the resin, the change of the extrusion method, and other methods in forming the second layer described below, but is not limited thereto.

The second layer may have a thickness of 100 μm or less, for example, 10 μm to 50 μm, and 20 μm to 40 μm. In the above range, the protective film may be formed between the adhesive layer and the hard coating layer, there may be an advantageous effect on the flexibility.

The second layer may be formed of an optically transparent resin. For example, the resin is a non-urethane resin, specifically, a polyester resin, polycarbonate resin, polyimide resin, polystyrene resin, including polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, Poly (meth) acrylate resins including polymethyl methacrylate, cyclic olefin polymer resins, non-halogenated acyclic polyolefin resins including polyethylene, polypropylene, etc., polychlorotrifluoroethylene (PCTFE) resins, and the like. It may include one or more of the halogenated acyclic polyolefin resin comprising.

The adhesive layer 112 is formed between the first layer and the second layer to adhere the first layer and the second layer to each other. The adhesive layer must also be bent when the protective film is bent, so the elastic modulus must be controlled.

The adhesive layer 112 has a smaller elastic modulus than the first layer and the second layer. Therefore, when the protective film formed between the first layer and the second layer is bent, the stress applied to the first layer and the second layer can be alleviated.

The adhesive layer may have a storage modulus of 10 kPa to 1000 kPa at 25 ° C. In the above range, the impact resistance of the protective film can be increased, and reliability may be good even once or repeatedly folding the protective film at room temperature. Preferably, the adhesive layer may have a storage modulus of 10 kPa to 800 kPa at 25 ° C.

Meanwhile, the adhesive layer may have a storage modulus of 10 kPa to 1000 kPa at 80 ° C. Within this range, the impact resistance of the protective film can be increased, and reliability may be good even in one or repeated folding of the window film at high temperature and high humidity. Preferably, the adhesive layer may have a storage modulus of 10 kPa to 800 kPa at 80 ° C. The adhesive layer may have a storage modulus of 10 kPa to 1000 kPa at -20 ° C. In the above range, the impact resistance of the protective film can be improved, and even at a low temperature, even once or repeated folding of the window film, the reliability may be good. Preferably, the adhesive layer may have a storage modulus of 10 kPa to 500 kPa at -20 ° C. The pressure-sensitive adhesive layer 110c has a storage modulus at 25 ° C .: −20 ° C., and a ratio of 1: 1 to 1: 4, specifically 1: 1 to 1: 3.5, and more particularly, 1: 1 to 1: 2.8. Can be. In the above range, the adhesive layer reduces the stress of the adherend in the wide temperature range (-20 to 25 ° C.) due to the change in temperature, and is flexible because no peeling or bubbles occur in the foldable test. Can be used for (flexible) optical members. The adhesive layer may have a ratio of storage modulus at 80 ° C .: storage modulus at −20 ° C. in the range of 1: 1 to 1:10, specifically 1: 1 to 1: 8, and more specifically 1: 1 to 1: 5. . In the above range, the adhesive layer does not fall off the adhesive strength between the adhesives in a wide temperature range (-20 to 80 ℃), it can be used for a flexible (flexible) optical member.

In addition, the adhesive layer should have high peel strength for both the first layer of the thermoplastic polyurethane film and the second layer of the non-urethane film. Thus, the pressure-sensitive adhesive layer is formed of the pressure-sensitive adhesive layer composition described below.

The adhesive layer composition may be formed of an optical clear adhesive (OCA) adhesive composition including a (meth) acrylic copolymer as a (meth) acrylic adhesive layer.

For example, the composition for pressure-sensitive adhesive layers may include a monomer mixture for a (meth) acrylic copolymer having a hydroxyl group; Initiator; And macromonomers and organic nanoparticles. The monomer mixture may be included in the pressure-sensitive adhesive composition in a state in which the monomer mixture is not polymerized at all, but the monomer mixture may be included as a partially polymerized partial polymer. Preferably, the pressure-sensitive adhesive composition comprises a monomer mixture for a (meth) acrylic copolymer having a hydroxyl group; Initiator; And organic nanoparticles.

The monomer mixture may be composed of 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 layer. 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. The hydroxyl group-containing (meth) acrylate is 5% to 40% by weight, for example, 8% to 30% by weight, 10% to 30% by weight of the total of the hydroxyl group-containing (meth) acrylate and the alkyl group-containing (meth) acrylate. It may be included in weight percent. In the above range, the adhesion and durability of the pressure-sensitive adhesive layer can be further improved.

The alkyl group-containing (meth) acrylate can be a copolymer to form a matrix of the adhesive layer. 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, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, iso-butyl (meth) acrylic Latex, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) And at least one of acrylate, decyl (meth) acrylate, lauryl (meth) acrylate and isobornyl (meth) acrylate. Alkyl group-containing (meth) acrylate is 60% to 95% by weight, for example 70% to 92%, 70% to 90% by weight of the total hydroxyl group-containing (meth) acrylate and alkyl group-containing (meth) acrylate It may be included in weight percent. In the above range, the adhesion and durability of the pressure-sensitive adhesive layer can be further improved.

The monomer mixture may further include 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 layer. 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 and 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), such as an acrylate, diethylaminoethyl (meth) acrylate, N-tert- butylaminoethyl (meth) acrylate, and (meth) acryloxyethyl trimethylammonium chloride (meth) acrylate It may be an acrylic monomer, 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.

The monomer having a silane group is 2-acetoacetoxyethyl (meth) acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyl tris (2-methoxyethyl) silane, vinyltriacetoxysilane, (meth) acrylic 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.

The copolymerizable monomer may be included in an amount of 15 parts by weight or less, specifically 10 parts by weight or less, and more specifically 0.05 parts by weight to 8 parts by weight, based on 100 parts by weight of the total of the hydroxyl group-containing (meth) acrylate and the alkyl group-containing (meth) acrylate. Can be. The pressure-sensitive adhesive composition in the above range can further improve the adhesion and recovery of the adhesive film.

The initiator can be used to cure (partial polymerization) the monomer mixture into a (meth) acrylic copolymer or to cure a 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 can be used. 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.

The initiator is 0.0001 parts by weight to 5 parts by weight, specifically 0.001 parts by weight to 3 parts by weight based on 100 parts by weight of the total of the hydroxyl group-containing (meth) acrylate and alkyl group-containing (meth) acrylate constituting the (meth) acrylic copolymer. May be included. 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.

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 layer can exhibit sufficient cohesion, and can suppress a decrease in stickiness or adhesion.

The divalent bonding 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 is 20 parts by weight or less, specifically 0.1 parts by weight to 20 parts by weight, 0.1 parts by weight to 10 parts by weight, 0.5 parts by weight based on 100 parts by weight of the total of the hydroxyl group-containing (meth) acrylate and the alkyl group-containing (meth) acrylate. It may be included from 5 parts by weight. In the above range, the viscoelasticity and modulus of the pressure-sensitive adhesive layer and the restoring force can be balanced, and the haze of the pressure-sensitive adhesive layer can be prevented from rising.

The organic nanoparticles may have an average particle diameter of 10 nm to 400 nm, specifically 10 nm to 300 nm, more specifically 30 nm to 280 nm, and more specifically 50 nm to 280 nm. In the above range, the folding of the pressure-sensitive adhesive layer is not affected, and the transparency of the pressure-sensitive adhesive layer may be good as the total light transmittance is 90% or more in the visible light region.

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 layer may be excellent. The organic nanoparticles may have a refractive index of 1.35 to 1.70, specifically 1.40 to 1.60. In the above range, the transparency of the pressure-sensitive adhesive layer 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 formula 2: That is, both the core and the shell may be nanoparticles which are organic materials. When having a particle form as described above, the adhesion of the adhesive layer 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 have a low temperature and / or room temperature viscoelastic effect of the adhesive layer. The core may include at least one of polyalkyl (meth) acrylate, polysiloxane or polybutadiene 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 to be dissolved by various organic solvents. The deeper the crosslinking state, the smaller the degree of dissolution by the solvent. Acetone, toluene, or the like may be used as a solvent for determining the crosslinking state. Specifically, the organosiloxane (co) polymer may have a portion that 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 layer 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 layer in a wide temperature range may be good.

The organic nanoparticles are 0.1 parts by weight to 20 parts by weight, specifically 0.5 parts by weight to 10 parts by weight, specifically 0.5 parts by weight to 100 parts by weight of the total amount of the hydroxyl group-containing (meth) acrylate and the alkyl group-containing (meth) acrylate. It may be included in 8 parts by weight. Within this range, the modulus of the pressure-sensitive adhesive layer at high temperature can be increased, the folding properties at normal temperature and high temperature of the pressure-sensitive adhesive layer can be improved, and the low-temperature and / or normal temperature viscoelasticity of the pressure-sensitive adhesive layer can be made excellent.

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

The composition for the pressure-sensitive adhesive layer may further include a silane coupling agent. 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. 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 total of the hydroxyl group-containing (meth) acrylate and alkyl group-containing (meth) acrylate. 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 peeling force between low temperature, room temperature, and high temperature can be low.

The adhesive layer composition may further include a crosslinking agent. A crosslinking agent can raise the degree of crosslinking of an adhesive composition, and can raise the mechanical strength of an adhesive layer. The crosslinking agent may include a polyfunctional (meth) acrylate capable of curing with an active energy ray, for example, a bifunctional (meth) acrylate such as hexanediol diacrylate, or a trifunctional to 6 functional (meth) acrylate. Can be. The crosslinking agent is 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 total of the hydroxyl group-containing (meth) acrylate and alkyl group-containing (meth) acrylate. It can be included as a wealth. There is an effect of excellent adhesion and increased reliability in the above range.

The adhesive layer 112 may have a thickness of 10 μm to 75 μm. In the above range, there may be an excellent effect of flexibility and impact resistance. Preferably, the adhesive layer may have a thickness of 10 μm to 50 μm and 10 μm to 30 μm.

The hard coating layer 120 may be formed on the laminate of the first layer, the adhesive layer, and the second layer to protect various elements mounted on the lower portion of the window film in the window film and the display device.

The hard coat layer 120 may have an elastic modulus of 2 GPa or less, for example, 0.5 GPa to 2 GPa. Within the above range, the scratch resistance of the protective film is good and the bending property is good when bending, and the crack may not occur even when the bending stiffness is 20N or less. The elastic modulus of the hard coat layer may be formed of a composition for a hard coat layer described below.

The hard coating layer 120 may have a thickness of 1 μm or more and less than 10 μm, specifically 1 μm or more and 5 μm or less. In the above range, the bending property of the protective film may be good.

The hard coating layer 120 may have a refractive index of 1.40 to 1.75, specifically 1.45 to 1.65. In the above range, the refractive index is appropriate relative to the laminate may be good optical properties of the protective film, it is possible to improve the screen visibility when laminated on the window film.

The hard coating layer 120 is a composition for a hard coating layer comprising a first urethane (meth) acrylate oligomer, a second urethane (meth) acrylate oligomer, a (meth) acrylate monomer, zirconia particles, an initiator, a silicone-based additive and a fluorine-based additive It can be formed as.

On a solids basis, among the total 100 parts by weight of the first urethane (meth) acrylate oligomer, the second urethane (meth) acrylate oligomer, the (meth) acrylate monomer, and the zirconia particles, the first urethane (meth) acrylate oligomer is 10 parts by weight to 50 parts by weight of the second urethane (meth) acrylate oligomer may be included in 40 parts by weight to 80 parts by weight. Within this range, the elastic modulus can be obtained, and the impact resistance and scratch resistance of the protective film can be excellent, and the folding radius can be increased by lowering the radius of curvature together with the laminate. Preferably, the first urethane (meth) acrylate oligomer may be included in 30 parts by weight to 50 parts by weight, 30 parts by weight to 45 parts by weight, and the second urethane (meth) acrylate oligomer may be included in 40 parts by weight to 60 parts by weight. . Within this range, the above-described impact resistance, scratch resistance, and folding property can be improved even in the thin coating layer having a thin thickness.

In the present specification, "solid content basis" means the entirety of the hard coating layer except for the solvent.

The first urethane (meth) acrylate oligomer and the second urethane (meth) acrylate oligomer can be cured by the initiator to form a matrix of the hard coating layer and, together with the zirconia particles, to improve impact resistance, scratch resistance and good bendability. . The composition for the hard coating layer includes a first urethane (meth) acrylate oligomer having a lower weight average molecular weight than the second urethane (meth) acrylate oligomer but having a large number of functional groups and a low elongation, thereby impact resistance of the protective film including the hard coating layer. It can improve scratch resistance and flexibility. While the second urethane (meth) acrylate oligomer is a soft component, the first urethane (meth) acrylate oligomer is a hard component.

The first urethane (meth) acrylate oligomer is a 7- to 10-functional (meth) acrylate-based weight average molecular weight of 1000g / mol or more, less than 4000g / mol, elongation can be 1% or more and less than 15%. Within this range, the impact resistance, scratch resistance and bendability of the protective film can be improved. Preferably, the first urethane (meth) acrylate oligomer is a 9- to 10-functional (meth) acrylate-based, having a weight average molecular weight of 1500 g / mol or more and 2500 g / mol or less and elongation of 5% or more and 10% or less. Can be. In the above range, the above-described impact resistance, scratch resistance, and folding properties can be improved even in the thin-coated hard coating layer, and more wear resistance can be achieved.

The second urethane (meth) acrylate oligomer is a tetrafunctional to six-functional (meth) acrylate-based, and may have a weight average molecular weight of 4000 g / mol or more and 8000 g / mol or less and elongation of 15% or more and 25% or less. Within this range, the impact resistance, scratch resistance and bendability of the protective film can be improved. Preferably, the second urethane (meth) acrylate oligomer is a 5-functional to 6-functional (meth) acrylate-based, and may have a weight average molecular weight of 4000 g / mol to 6000 g / mol and an elongation of 15% or more and 20% or less. have. In the above range, the above-described impact resistance, scratch resistance, and folding properties can be improved even in the hard coat layer having a thin thickness, and the stretching effect can be further improved.

The second urethane (meth) acrylate oligomer may be included in a predetermined amount compared to the first urethane (meth) acrylate oligomer. In such a case, when included together with the zirconia particles, the impact resistance, scratch resistance and flexibility can be improved. Specifically, the second urethane (meth) acrylate oligomer may be included in an amount of 80% to 200% of the first urethane (meth) acrylate oligomer. In the above range, the above-described impact resistance, scratch resistance, and folding properties can be improved even in the hard coat layer having a thin thickness, and the stretching effect can be further improved.

The first urethane (meth) acrylate oligomer and the second urethane (meth) acrylate oligomer can be prepared by polymerization of a (meth) acrylate compound having a polyfunctional polyol, a polyfunctional isocyanate compound and a hydroxyl group, respectively. The polyfunctional polyol may include the polyfunctional polyol described above, and the polyfunctional isocyanate compound may include the polyfunctional isocyanate compound described above. The (meth) acrylate compound having a hydroxyl group is hydroxyethyl (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, hydroxypropyl (meth) acrylate, and hydride Hydroxybutyl (meth) acrylate, chlorohydroxypropyl (meth) acrylate, hydroxyhexyl (meth) acrylate, and the like, but are not limited thereto.

The (meth) acrylate monomer is a bifunctional to six functional (meth) acrylate monomer, which is cured together with the first urethane (meth) acrylate oligomer and the second urethane (meth) acrylate oligomer to increase the hardness. (Meth) acrylate monomers include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentylglycol di (meth) acrylate, polyethylene glycol di (meth) acrylate Neopentyl glycol 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, tricyclodecanedimethanol (meth) acrylate, dimethylol dicyclopentanedi (meth) acrylate, ethylene oxide modified hexahydro Phthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified trimethylpropane di (meth) acrylate, adamantane di (meth) acrylic Or 9,9-bis-byte bi-functional (meth) acrylates such as [4- (2-oxy-acrylic) phenyl] fluorene; Trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ethylene oxide modified Trifunctional (meth) acrylates such as trimethylolpropane tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, or tris (meth) acryloxyethyl isocyanurate; Tetrafunctional (meth) acrylates such as diglycerin tetra (meth) acrylate or pentaerythritol tetra (meth) acrylate; 5-functional (meth) acrylates such as dipentaerythritol penta (meth) acrylate; And difunctional acrylates such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate, and the like, but are not limited thereto. Preferably, the (meth) acrylate monomer is trifunctional to tetrafunctional, and may further have an effect of improving impact resistance and scratch resistance due to crosslinking density control.

1 to 30 parts by weight of the (meth) acrylate monomer in a total of 100 parts by weight of the first urethane (meth) acrylate oligomer, the second urethane (meth) acrylate oligomer, the (meth) acrylate monomer and the zirconia particles, For example, it may be included in 5 parts by weight to 20 parts by weight, 5 parts by weight to 15 parts by weight. Within this range, the above-described impact resistance, scratch resistance, and folding property can be improved even in the thin coating layer having a thin thickness.

The zirconia particles can increase the scratch resistance of the hard coating layer together with the first urethane (meth) acrylate oligomer and the second urethane (meth) acrylate oligomer. When silica particles were included instead of zirconia particles, scratch resistance was poor when combined with the first urethane (meth) acrylate oligomer and the second urethane (meth) acrylate oligomer. The zirconia particles may not be surface treated, but are dispersible with the first urethane (meth) acrylate oligomer, the second urethane (meth) acrylate oligomer, and the (meth) acrylate monomer by being surface treated with the (meth) acrylate compound. This haze can lower the haze of the protective film. The zirconia particles may have an average particle diameter (D50) of 200 nm or less, 100 nm or less, specifically 5 nm or more and 100 nm or less. Within this range, scratch resistance can be improved without increasing the haze of the hard coat layer. Among 100 parts by weight of the total of the first urethane (meth) acrylate oligomer, the second urethane (meth) acrylate oligomer, the (meth) acrylate monomer and the zirconia particles, the zirconia particles are 0.01 parts by weight to 10 parts by weight, for example 1 It may be included in parts by weight to 4 parts by weight. Within this range, the above-described impact resistance, scratch resistance, and folding property can be improved even in the thin coating layer having a thin thickness.

The initiator may comprise a radical type photoinitiator. The initiator may be an acetophenone-based compound, a benzyl ketal type compound, or a mixture thereof, but is not limited thereto. Preferably, the acetophenone compound is 2,2-dimethoxy-2-phenylacetophenone, 2,2'-diethoxy acetophenone, 2,2'-dibutoxy acetophenone, 2-hydroxy-2-methyl Propiophenone, pt-butyl trichloro acetophenone, pt-butyl dichloro acetophenone, 4-chloro acetophenone, 2,2'-dichloro-4-phenoxy acetophenone, 2-methyl-1- (4- (methyl Thio) phenyl) -2-morpholino propane-1-one, 2-benzyl-2-dimethyl amino-1- (4-morpholino phenyl) -butan-1-one, or mixtures thereof. .

0.01 to 10 parts by weight, specifically 1 part by weight, based on 100 parts by weight of the total of the first urethane (meth) acrylate oligomer, the second urethane (meth) acrylate oligomer, the (meth) acrylate monomer and the zirconia particles It may be included from 5 parts by weight. In the above range, the curing reaction can proceed completely, remaining amount of initiator can remain to prevent the transmittance from decreasing, can also lower the bubble generation and have excellent reactivity.

Silicone-based additives may include conventional silicone-based additives known to those skilled in the art to improve the surface properties of the hard coat layer. For example, the silicone-based additive may include, but is not limited to, polyether modified acrylic polydimethylsiloxane and the like. The silicone-based additive is 0.01 parts by weight to 5 parts by weight, specifically 0.1 based on 100 parts by weight of the total of the first urethane (meth) acrylate oligomer, the second urethane (meth) acrylate oligomer, the (meth) acrylate monomer and the zirconia particles. It may be included in parts by weight to 2 parts by weight, 0.1 parts by weight to 1 parts by weight. Within this range, the surface properties of the hard coat layer may be good without affecting other components.

The fluorine-based additive may include conventional fluorine-based additives known to those skilled in the art to improve the surface properties of the hard coat layer. The fluorine-based additive is 0.01 parts by weight to 5 parts by weight, specifically 0.1 based on 100 parts by weight of the total of the first urethane (meth) acrylate oligomer, the second urethane (meth) acrylate oligomer, the (meth) acrylate monomer and the zirconia particles. It may be included in parts by weight to 2 parts by weight. Within this range, the surface properties of the hard coat layer may be good without affecting other components.

The composition for a hard coating layer can further facilitate the coating property of the composition for a hard coating layer by further comprising a solvent. The solvent may include methyl ethyl ketone, methyl isobutyl ketone, and the like, but is not limited thereto. The composition for the hard coating layer may further include conventional additives known to those skilled in the art to impart additional functions to the hard coating layer. Additives may include, but are not limited to, antioxidants, stabilizers, surfactants, pigments, antistatic agents, leveling agents, and the like.

The protective film 100 may have a thickness of 400 μm or less, specifically 150 μm to 400 μm. In the above range, it can be used in the display device. The protective film 100 has a total light transmittance of 90% or more, 90% to 99%, haze of 1% or less, 0% to 1%, a yellow index (YI) of 1 or less, in a visible light region, for example, a wavelength of 380 nm to 780 nm. It can be 0 to 1. In the above range, it can be used in the display device.

Although not shown in FIG. 1, a functional layer may be further formed on the hard coat layer to provide additional functions to the protective film. For example, the functional layer may be one of anti-reflection, low reflection, anti-glare, anti-finger, anti-contamination, diffusion, and refractive functions. The above function can be provided. The functional layer may be formed by applying a composition for forming a functional layer on the hard coating layer 120 or may be laminated on the hard coating layer 120 through an adhesive layer or an adhesive layer. In another embodiment, the functional layer may be formed such that one surface of the hard coat layer 120 becomes a functional layer.

Hereinafter, a protective film according to another embodiment of the present invention will be described with reference to FIG. 2. 2 is a cross-sectional view of a protective film according to another embodiment of the present invention.

Referring to FIG. 2, the protective film 200 according to the present exemplary embodiment is substantially the same as the protective film 100 except that the adhesive layer 130 is further formed on the lower surface of the first layer 111. . By further forming the adhesive layer 130, the protective film 200 may be adhered to the window film and the folding property may be improved.

The adhesive layer 130 may be formed of a conventional adhesive known to those skilled in the art, for example, an optical clear adhesive (OCA). Alternatively, the adhesive layer 130 may be the same as the adhesive layer 112 described above.

The optical member of the present invention may include a window film and a protective film formed on the window film, and the protective film may include a protective film according to embodiments of the present invention. The window film and the protective film may be formed in direct contact with each other. The window film is not particularly limited, but may include a window coating layer formed of a base layer and a silicone resin for foldability.

The display device of the present invention may include the protective film for a window film of the present invention. The display device may include, but is not limited to, a light emitting display device, a liquid crystal display device, and the like including an organic light emitting display device. The display device may include a flexible device, but the protective film of the present invention may be used in a non-flexible device.

In one embodiment, the flexible display device includes a display unit, a polarizer, a touch screen panel, a window film, a protective film, the protective film may include a protective film for window film protection according to an embodiment of the present invention.

The display unit is for driving a flexible display device, and may include an optical device including an OLED, an LED, a quantum dot light emitting diode (QLED), or an LCD device formed on the substrate. The display unit may further 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 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 detects a change in capacitance generated when a human body or a conductor such as a stylus touches to generate an electrical signal. The display unit may be driven by the signal. The touch screen panel 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. The conductor for the touch screen panel may include, but is not limited to, metal nanowires, conductive polymers, carbon nanotubes, and the like.

The window film may be formed outside the flexible display device to protect the display device. The window film may be a film having a window coating layer formed on the window coating layer alone or the base layer. The base layer may be a film formed of an optically transparent resin such as a polyimide film. The window coating layer may be formed of a composition for a window coating layer including a silicone resin, a crosslinking agent, and an initiator.

Since an adhesive film is further formed between the polarizing plate and the touch screen panel and / or between the touch screen panel and the window film, bonding between the polarizing plate, the touch screen panel and the window film may 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 in no sense can be construed as limiting the present invention.

Production Example  One: For hard coating  Preparation of Composition 1

Each component of the composition for a hard coating layer used in Preparation Example 1 is as follows.

(A) First urethane (meth) acrylate oligomer: UA11064 (manufacturer: Entis company, 10 functional (meth) acrylate type, weight average molecular weight: 2,000 g / mol, elongation: 6%, solid content: 100%)

(B) Second urethane (meth) acrylate oligomer: CHTF-9696AN (manufacturer: Kempton, 6 functional (meth) acrylate type, weight average molecular weight: 4,500 g / mol, elongation: 16%, solid content 83%)

(C) (meth) acrylate monomer: SR499 (manufacturer: Sartomer, trifunctional (meth) acrylate type, solid content 100%)

(D) Zirconia particles: SZK330A (manufacturer: Ranco, average particle diameter (D50): 20nm to 50nm, solid content 30%)

(E) Silicone additive: BYK-3500 (manufacturer: BYK, 10% solids)

(F) Fluorine-based additive: RS-78 (manufacturer: DIC, 10% solids)

(G) Initiator: Irgacure 184 (Manufacturer: BASF, 25% solids)

(H) Solvent: Methyl ethyl ketone (manufacturer: Samjeon Pure Chemicals)

(I) (meth) acrylate oligomer: EB9310 (manufacturer: Entis company)

* Elongation in the first urethane (meth) acrylate resin and the second urethane (meth) acrylate resin was evaluated by the Instron measuring method.

Based on solids, 30 parts by weight of the first urethane (meth) acrylate oligomer, 60 parts by weight of the second urethane (meth) acrylate oligomer, 7 parts by weight of the (meth) acrylate monomer, 3 parts by weight of zirconia particles, 0.1 weight of the silicone additive To the part, 0.4 parts by weight of fluorine-based additives, 2.5 parts by weight of the initiator was mixed, and 50 parts by weight of methyl ethyl ketone as a solvent to prepare a composition for a hard coating layer.

The composition for the hard coating layer was applied on a glass plate with a thickness of 5 μm, dried at 80 ° C. for 2 minutes, and cured with a light amount of 300 mJ / cm ² under a light source (metal halide lamp) under nitrogen purging conditions to form a 5 μm hard coating layer. Specimens were prepared for measuring the modulus. The elastic modulus of the hard coat layer was measured in the same manner as in Table 1 for the prepared specimen. The elastic modulus of the hard coat layer is 1.5 GPa at 25 ° C.

Production Example  2: For hard coating layer  Composition 2 Preparation

Based on the solid content, the components are mixed so that 70 parts by weight of the (meth) acrylate oligomer, 20 parts by weight of the (meth) acrylate monomer, 0.1 part by weight of the silicone additive, 0.4 part by weight of the fluorine additive, and 2.5 parts by weight of the initiator, and methyl as a solvent. Mixing 50 parts by weight of ethyl ketone to prepare a composition for a hard coating layer.

The elastic modulus of the hard coat layer was measured in the same manner as in Preparation Example 1 for the prepared hard coat layer composition. The elastic modulus of the hard coat layer is 5 GPa at 25 ° C.

Preparation Example 3 Preparation of Adhesion Layer Composition

The core is a core-shell structure consisting of polybutyl acrylate (PBA) and the shell is polymethyl methacrylate (PMMA), the shell is 40% by weight of the organic particles, the core is 60% by weight of the organic particles, the average particle diameter Silver 230nm, and the refractive index was 1.48 to produce organic nanoparticles. 4 parts by weight of the prepared organic nanoparticles and 100 parts by weight of a monomer mixture including 70% by weight of 2-ethylhexyl acrylate and 30% by weight of 4-hydroxybutyl acrylate and 0.005% by weight of a photopolymerization initiator (Irgacure 651) The parts were mixed well in a glass vessel. Partial polymerization with hydroxyl groups having a viscosity of about 1000 CPS was achieved by polymerizing the mixture by replacing the dissolved oxygen in the glass vessel with nitrogen gas and irradiating with ultraviolet light using a low pressure lamp (BL Lamp manufactured by Sankyo) for several minutes ( A solution containing a meth) acrylic copolymer was obtained. An adhesive composition was prepared by adding 0.35 parts by weight of an additional photopolymerization initiator (c2) (Irgacure 184) to the (meth) acrylic copolymer having a hydroxyl group. The resulting pressure-sensitive adhesive composition was coated on a release-treated PET (polyethylene terephthalate film, thickness 50㎛) to form an adhesive film having a thickness of 25㎛. After covering a release film having a thickness of 75㎛ on the top, and irradiated on both sides using a low pressure lamp (BL Lamp manufactured by Sankyo) for 6 minutes to obtain a transparent adhesive sheet. The PET film was removed from the transparent adhesive sheet to obtain an adhesive layer having a thickness of 25 μm.

Table 1 shows specific specifications of the films used in the following Examples and Comparative Examples. Elastic modulus of the film was measured using HM2000LT Micro Indentor (Fisher). Place the film of Table 1 on a 2T thick soda-lime glass plate at 25 ° C, pressurize the film for 20 seconds with a constant force of 300mN and creep for 5 seconds with a straight diamond pyramid-shaped micro indentor having a square base. In addition, the elastic modulus was measured by relaxation for 20 seconds.

Film material Elastic Modulus (GPa) Film thickness
(Μm) Film name,
manufacturer Film 1 TPU 0.05 150 DUS-451, Sheedom Film 2 PET 2.0 23 U403, Toray Film 3 PI 6.0 30 Grade 無, Koion Film 4 PCTFE 0.5 25 DF0025C1, Daikin

* TPU: thermoplastic polyurethane, PET: polyethylene terephthalate, PI: polyimide, PCTFE: polychlorotrifluoroethylene

Example  One

The laminated body was manufactured by laminating | stacking the film 2 by the adhesive layer of film 1, the manufacturing example 3, and the 2nd layer as a 1st layer. Coating the composition for the hard coating layer of Preparation Example 1 on the second layer of the laminate and dried for 2 minutes at 80 ℃, the thickness by irradiating a light amount of 300mJ / cm ² under a light source (metal halide lamp) under nitrogen purging conditions A protective film was prepared by forming a 5 μm hard coat layer.

Example  2

A protective film was manufactured in the same manner as in Example 1, except that the protective film structure was changed as shown in Table 2 below.

Comparative example  1 to Comparative example  4

A protective film was manufactured in the same manner as in Example 1, except that the protective film structure was changed as shown in Table 2 below.

Comparative example  5

The laminated body was manufactured by laminating | stacking the film 2 by the adhesive layer of film 1, the manufacturing example 3, and the 2nd layer as a 1st layer. Coating the composition for the hard coating layer of Preparation Example 2 on the second layer of the laminate and dried for 2 minutes at 80 ℃, irradiated with a light amount of 300mJ / cm ² under a light source (metal halide lamp) under nitrogen purging conditions thickness A protective film was prepared by forming a 5 μm hard coat layer.

The following physical properties were evaluated about the protective film for window films of an Example and a comparative example, and the result is shown in Table 2 below.

(1) Bending stiffness: Bending stiffness was measured by TA-XT plus (Texture Technologies). The protective films of Examples and Comparative Examples were cut into rectangles of width x length (18 cm x 10 cm) to prepare specimens. Bending stiffness was measured at 25 ° C.

Referring to FIG. 3A, the specimen is bent in half in the horizontal direction of the specimen and in the direction of the first layer of the specimen, and then the upper jig of the TA-XT plus and the lower jig opposite thereto. Fixed in between. At the time of fixation, the end of the specimen was fixed to the portion other than the portion folded in TA-XT plus using an acrylic adhesive tape. At this time, the center portion of the specimen bent and the upper jig and lower jig of the TA-XT plus were matched with each other. Before pressing the upper jig, the distance between the upper jig and the lower jig was 20 mm.

Referring to FIG. 3B, while the lower jig is fixed and the upper jig is pressed at a speed of 10.2 mm / sec, a distance between the upper jig and the lower jig is 2 mm (corresponding to a radius of curvature 1 mm) and 4 mm (curvature radius 2 mm). ), Or 6mm (corresponds to the radius of curvature 3mm) was measured while pressing in the direction of the arrow, respectively.

(2) Scuff test: A test piece was prepared by attaching the adhesive layer of Preparation Example 3 to the first layer of the protective films of the Examples and Comparative Examples, and laminating a polyethylene terephthalate film (thickness: 75 µm). The prepared specimens were fixed to the wear resistance measuring instrument (Daesung Precision), steel wool # 0000 was mounted, 1.5kg weight was added, and the number of scratches occurred after 10 round trips with 50mm scale on the surface of the hard coating layer. It was. The lower the number, the higher the scratch resistance. When the scratch resistance is evaluated, the number is less than one, so the scratch resistance is high, and thus it can be used. When the scratch resistance was evaluated, the number was 1 or less, and when more than 1, NG was evaluated.

Example Comparative example One 2 One 2 3 4 5 Hard Coating Layer Preparation Example 1 Preparation Example 1 Preparation Example 1 Preparation Example 1 Preparation Example 1 Preparation Example 1 Preparation Example 2 Hard Coating Layer Modulus (GPa) 1.5 1.5 1.5 1.5 1.5 1.5 5 The second layer Film 2
(PET) Film 3
(PI) Film 1
(TPU) Film 4
(PCTFE) Film 2
(PET) Film 3
(PI) Film 2
(PET) 2nd layer modulus
(GPa) 2.0 6.0 0.05 0.5 2.0 6.0 2.0 First floor Film 1
(TPU) Film 1
(TPU) Film 1
(TPU) Film 1
(TPU) Film 2
(PET) Film 3
(PI) Film 1
(TPU) 1st layer modulus
(GPa) 0.05 0.05 0.05 0.05 2.0 6.0 0.05 Bending stiffness (N, bending radius 1mm) 11 20 20 10 35 50 23 Bending stiffness (N, bending radius 2mm) 5 7 8 4 12 15 6 Bending stiffness (N, bending radius 3mm) 2 2.5 3 2 8 10 2 Scratch resistance OK OK NG NG OK OK OK

As shown in Table 2, the protective film for a window film according to the embodiment of the present invention was excellent in both scratch resistance and folding resistance. However, Comparative Examples 1 to 5, which deviate from the configuration of the present invention, do not have good scratch resistance, or have a bad folding property exceeding the bending stiffness 20N at a predetermined curvature radius.

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 (19)

The first layer, the adhesive layer, the second layer and the hard coating layer is a protective film for a window film sequentially laminated,
The first layer is a film formed of thermoplastic polyurethane,
The first layer has an elastic modulus of 1 GPa or less at 25 ° C.,
The second layer has an elastic modulus of 1 GPa to 6 GPa at 25 ° C.,
The second layer has a larger elastic modulus at 25 ° C. than the first layer,
The hard coating layer has an elastic modulus of less than 2 GPa at 25 ℃,
A bending film having a bending stiffness of 20 N or less when the protective film for window film is bent in the first layer direction with a radius of curvature of 1 mm to 3 mm.
The protective film for a window film of claim 1, wherein the hard coating layer has an elastic modulus of 0.5 GPa to 2 GPa at 25 ° C. 7.
The protective film for a window film according to claim 1, wherein the second layer comprises a non-urethane resin film.
The method of claim 3, wherein the second layer is polyester resin, polycarbonate resin, polyimide resin, polystyrene resin, poly (meth) acrylate resin, cyclic olefin polymer resin, non-halogenated acyclic polyolefin resin, halogenated A protective film for a window film, comprising at least one of acyclic polyolefin resin.
The protective film for a window film of claim 1, wherein the first layer has a smaller elastic modulus at 25 ° C. than the hard coating layer.
According to claim 1, wherein the thermoplastic polyurethane is an aliphatic or alicyclic polyurethane comprising a protective film for a window film.
The said 1st layer is a protective film for window films of Claim 1 whose thickness is 100 micrometers or more and 200 micrometers or less and Shore hardness is 95A-98A.
The window of claim 1, wherein the first layer has a thickness of 100 μm to 200 μm, the second layer has a thickness of 10 μm to 50 μm, and the hard coating layer has a thickness of 3 μm or more and less than 10 μm. Protective film for film.
The method of claim 1, wherein the hard coating layer has a different elongation of the first urethane (meth) acrylate oligomer and the second urethane (meth) acrylate oligomer, (meth) acrylate monomers, zirconia particles, initiators, silicone-based additives and The protective film for a window film formed from the composition for hard-coat layers containing a fluorine-type additive.
The protective film for window film according to claim 9, wherein the first urethane (meth) acrylate oligomer has a weight average molecular weight of 1000 g / mol or more and less than 4000 g / mol and an elongation of 1% or more and less than 15%.
The protective film for window films according to claim 9, wherein the second urethane (meth) acrylate oligomer has a weight average molecular weight of 4000 g / mol or more and 8000 g / mol or less and an elongation of 15% or more and 25% or less.
The said zirconia particle is a protective film for window films of Claim 9 whose average particle diameter (D50) is 100 nm or less.
The method according to claim 9, wherein the (meth) acrylate monomer in a total of 100 parts by weight of the first urethane (meth) acrylate oligomer, the second urethane (meth) acrylate oligomer, the (meth) acrylate monomer, the zirconia particles 1 part by weight to 30 parts by weight, the zirconia particles will be included in 0.01 parts by weight to 10 parts by weight, protective film for a window film.
The silicone-based additive according to claim 9, wherein the silicone-based additive is 0.01% by weight based on 100 parts by weight of the first urethane (meth) acrylate oligomer, the second urethane (meth) acrylate oligomer, the (meth) acrylate monomer, and the zirconia particles. 5 parts by weight to 5 parts by weight, the fluorine-based additive is included in 0.01 parts by weight to 5 parts by weight, protective film for a window film.
The protective film for a window film according to claim 1, wherein the adhesive layer has a smaller elastic modulus than the first layer and the second layer, respectively.
The method of claim 1, wherein the pressure-sensitive adhesive layer is a monomer mixture for the (meth) acrylic copolymer having a hydroxyl group; Initiator; And formed into a composition for pressure-sensitive adhesive layer comprising organic nanoparticles, a protective film for a window film.
The protective film for a window film according to claim 16, wherein the organic nanoparticles include core-shell particles satisfying Equation 2.
<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).
Window film; And a protective film for a window film according to any one of claims 1 to 17 formed on the window film.
A display device comprising the protective film for a window film of any one of claims 1 to 17.

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