KR102097799B1 - Proctective film for optical display apparatus, optical member comprising the same and optical display apparatus comprising the same - Google Patents

Abstract

The first base layer, the intermediate layer, the second base layer, and the hard coating layer are sequentially formed, the first base layer is formed of a thermoplastic polyurethane, and the total thickness of the first base layer, the intermediate layer, and the second base layer is A protective film for an optical display device, which is 300 µm or more, and an optical display device including the same are provided.

Description

Protective film of optical display device, optical member including the same, and optical display device including the same {PROCTECTIVE FILM FOR OPTICAL DISPLAY APPARATUS, OPTICAL MEMBER COMPRISING THE SAME AND OPTICAL DISPLAY APPARATUS COMPRISING THE SAME}

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

Currently, as the development of a foldable optical display device becomes visible, a protective film for the foldable optical display device from an external environment is being developed. For example, the protective film of the optical display device may include a protective film for protecting the window film is formed on the window film and the window film to be disposed on the outside of the optical display device to view the display image. In particular, the protection film for the window film in the past was given priority to the protection from the external environment and the rework property, but it was difficult to apply to the foldable optical display device because the folding property was not realized.

The protection properties to the external environment can be realized by generally increasing the curing density or improving the curing degree, and combining the resins with rigid structures and organic / inorganic particles to make them hard. On the other hand, in the case of folding characteristics, it can be implemented by reducing the curing density and making a soft coating film by crosslinking with a resin having good flexibility.

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

The problem to be solved by the present invention is to provide a protective film for an optical display device having excellent folding property, scratch resistance and impact resistance.

Another problem to be solved by the present invention is to provide a protective film for an optical display device that is excellent in scratch resistance, impact resistance and folding property even in a thin thickness coating layer.

Another problem to be solved by the present invention is to provide a protective film for an optical display device having excellent optical properties.

In the protective film for an optical display device of the present invention, a first base layer, an intermediate layer, a second base layer, and a hard coating layer are sequentially formed, and the first base layer is formed of a thermoplastic polyurethane, and the first base layer, The total thickness of the intermediate layer and the second base layer may be 300 μm or more.

In the protective film for an optical display device of the present invention, a first base layer, an intermediate layer, a second base layer, and a hard coating layer are sequentially formed, and the hard coating layer is a urethane (meth) acrylate oligomer, an epoxy (meth) acrylate oligomer , (Meth) acrylate monomer, zirconia particles, an initiator and a composition for a hard coating layer containing a silicone-based additive, wherein the urethane (meth) acrylate oligomer is the urethane (meth) acrylate oligomer, epoxy (meth) acrylate Oligomer, (meth) acrylate monomer, may be included in 10 parts by weight to 50 parts by weight of 100 parts by weight of the total of zirconia particles.

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

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

The present invention provides a protective film for an optical display device excellent in folding, scratch resistance and impact resistance.

The present invention provides a protective film for an optical display device that is excellent in scratch resistance, impact resistance, and folding property even in a thin thickness coating layer.

The present invention provides a protective film for an optical display device having excellent optical properties.

1 is a cross-sectional view of a protective film according to an embodiment of the present invention.
2 is a cross-sectional view of a protective film according to another embodiment of the present invention.
3 is a cross-sectional view of an optical display device according to an embodiment of the present invention.
4 is a cross-sectional view of an optical display device according to another embodiment of the present invention.

Embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. In the drawings, parts not related to the description are omitted in order to clearly describe the present invention, and the same reference numerals are used for the same or similar elements throughout the specification.

In this specification, "upper" and "lower" are defined based on the drawings, and "upper" may be changed to "lower" and "lower" may be changed to "upper" according to the viewpoint of the city, or "on" or What is referred to as "on" may include not only directly above, but also through other structures in the middle. On the other hand, what is referred to as "directly on", "directly above" or "directly formed" means that there is no intervening structure.

As used herein, "(meth) acrylic" means acrylic and / or methacryl.

As used herein, "Shore hardness" means that measured by a shore hardness meter (JIS K7311).

As used herein, "elongation" means measured by the Instron instrument method (JIS K7311).

As used herein, “directly forming” means that no other point / adhesion layer, optical layer is formed between the layers.

The "average particle size" of the organic nanoparticles in this specification is the particle size of the organic nanoparticles expressed by the Z-average value and the particle diameter confirmed when SEM / TEM is observed by measuring in an aqueous or organic solvent with a Zetasizer nano-ZS equipment of Malvern. .

In this specification, "in-plane retardation (Re)" is an in-plane retardation value at a wavelength of 550 nm, and is a value represented by Equation 3:

<Equation 3>

Re = (nx-ny) x d

(In the above formula 3, nx, ny are the refractive index in the slow axis direction and the refractive index in the slow axis direction of the substrate layer at a wavelength of 550 nm, respectively, d is the thickness of the substrate layer (unit: nm)).

In the present specification, "protective film for optical display device" may include a window film that is disposed on the outer side of the optical display device to view an image and / or a protective film formed on the window film to protect the window film. have.

Hereinafter, a protective film (hereinafter referred to as a “protective film”) of an optical display device 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 base layer 110, an intermediate layer 120, a second base layer 130, and a hard coating layer 140. The protective film 100 may have a structure in which the first base layer 110, the intermediate layer 120, the second base layer 130, and the hard coating layer 140 are sequentially stacked.

The first base layer 110 supports the protective film 100, and although not shown in FIG. 1, an adhesive layer is formed on the lower surface of the first base layer 110, and the window film or optical display device is formed by the adhesive layer. Various optical elements, for example, a polarizing plate and the like can be adhered.

The first base layer 110 may be formed of a thermoplastic polyurethane (TPU). In addition, the entire thickness of the first base layer 110, the intermediate layer 120, and the second base layer 130 may be 300 μm or more. Therefore, the protective film of the present invention can increase the impact resistance and scratch resistance at the same time and have good folding properties even if a hard coating layer of thin thickness, for example, 3 μm or more and less than 20 μm, specifically 3 μm or more and 15 μm or less is formed. have. When the thickness of the first base layer 110, the intermediate layer 120 and the second base layer 130 is 300 µm or more, when the first base layer is not formed of a thermoplastic polyurethane, the display panel and the protective film during folding There may be a problem of lifting or buckling in between. Even if the first base layer is formed of a thermoplastic polyurethane, when the thickness of the entire first base layer 110, the intermediate layer 120, and the second base layer 130 is less than 300 μm, impact resistance may be deteriorated. . Preferably, the entire thickness of the first base layer 110, the intermediate layer 120, and the second base layer 130 may be 300 μm to 500 μm.

In one embodiment, the first base layer 110 may be a non-adhesive thermoplastic polyurethane film having a thickness of 100 μm or more and 200 μm or less and Shore hardness of 93A to 98A. The first base layer having the above thickness and Shore hardness range, by folding the curvature radius of the protective film together with the intermediate layer 120, the second base layer 130, and the hard coating layer 140 when folding the protective film, increases the folding property. It can be used for a foldable optical display device. In addition, even if the hard coating layer 120 has a thin thickness, for example, 3 µm or more and less than 20 µm, specifically 3 µm or more and 15 µm or less, the impact resistance and scratch resistance can be increased to prevent damage to the OLED panel and the like. The film can be thinned.

In addition, the first base layer 110 having the thickness and Shore hardness range may maintain the impact resistance and scratch resistance of the protective film even if the adhesive layer described below is adhered. In general, when the adhesive layer is laminated under the first base layer, there may be a problem that impact resistance and scratch resistance are lowered compared to the case where the adhesive layer is not provided.

The first base layer 110 may be formed of a thermoplastic polyurethane alone, or may be formed by further including an additive for preventing yellowing in the thermoplastic polyurethane, for example, a stabilizer. The thermoplastic polyurethane is not particularly limited as long as it is a material capable of meeting Shore hardness in the thickness range. For example, the thermoplastic polyurethane may be derived from a polyfunctional polyfunctional polyol or more than a bifunctional polyfunctional isocyanate, and further a chain extender may be further included. The polyol may include at least one 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, the yellowing of the protective film may be small. The polyol may include, but is not limited to, one or more of polyester diol, polycarbonate diol, polyolefin diol, polyether diol, polythioether diol, polysiloxane diol, polyacetaldiol, polyesteramide diol. The polyfunctional isocyanate can include any aliphatic, alicyclic or aromatic isocyanate. 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 changing the amount of the block level of the polyfunctional isocyanate and / or chain extender in the thermoplastic polyurethane or controlling the polymerization time. In the production of a thermoplastic polyurethane, a tin compound such as a tin salt of a carboxylic acid, an amine such as dimethylcyclohexylamine or triethylenediamine may be further included as a catalyst for promoting the formation of a urethane bond. Other conventional components, such as surfactants, flame retardants, fillers, pigments, etc. may be further included in the production of the thermoplastic polyurethane.

The first base 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 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 can be defined by the following Equation 1:

<Equation 1>

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

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

The first base layer 110 may have a refractive index of 1.40 to 1.65, specifically 1.45 to 1.60. In the above range, the refractive index of the intermediate layer, the second base layer and the hard coating layer is appropriate, so that the optical properties of the protective film may be good, and the screen visibility may be improved when laminated on the window film.

The first base layer 110 may have a light transmittance of 85% to 100%, specifically 90% to 99% at a wavelength of 550 nm. In the above range, it can be used in an optical display device.

The first base layer 110 may be an optically isotropic film or a retardation film.

In one embodiment, the first base layer is an isotropic film, and may be a film having Re of 5 nm or less, for example, 0 nm to 1 nm. The isotropic film may exhibit its own function without interfering with the retardation function of the window film or various retardation films positioned under the window film.

In another embodiment, the first base layer is a retardation film, and Re may be greater than 5 nm, specifically 50 nm to 30,000 nm. The retardation film may have an optical compensation function while supporting the hard coating layer, thereby providing an additional function to the optical display device. For example, in the first base layer, Re may be 100 nm to 160 nm, for example, a λ / 4 phase difference film (QWP film). In this case, a polarized sunglass effect may be exhibited. For example, the first base layer may have Re of 200 nm to 300 nm, for example, a λ / 2 phase difference film (HWP film). In this case, it can be stacked together with the λ / 4 retardation film to improve the display shape. For example, the first base layer may be an ultra-high phase difference film having Re of 8,000 nm or more, 15,000 nm or more, and 30,000 nm or less. In this case, the occurrence of rainbow mura or stain can be suppressed.

The first base layer 110 may be produced by film-forming a composition for a first base layer comprising a thermoplastic polyurethane alone or a thermoplastic polyurethane and an additive by melt extrusion or solvent casting. The produced film can be stretched by a conventional method to have a phase difference.

The intermediate layer 120 is formed on the first base layer 110 to connect the first base layer 110 and the second base layer 130. The intermediate layer 120 is directly formed on the first base layer 110 and the second base layer 130, respectively. The "directly formed" means that there are no other adhesive layers, adhesive layers, or optical layers interposed between the intermediate layer and the first base layer, and between the intermediate layer and the second base layer.

The intermediate layer 120 is formed between the first base layer 110 and the second base layer 130 to improve the folding property of the protective film by alleviating stress between the base layers when folding the protective film. The base layer of a single layer having the same thickness as the entire thickness of the first base layer and the second base layer without the intermediate layer 120 may have good impact resistance and scratch resistance, but has poor folding properties, resulting in excitation or buckling. You can.

In one embodiment, the intermediate layer 120 may be an adhesive layer, an adhesive layer, or a point adhesive layer. For example, the intermediate layer 120 is a (meth) acrylic adhesive layer, and may be formed of an optical clear adhesive (OCA) adhesive composition containing a (meth) acrylic copolymer.

For example, the pressure-sensitive adhesive composition 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 monomer mixture state in which polymerization is not 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 a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate.

The hydroxyl group-containing (meth) acrylate may provide the adhesive strength of the adhesive layer. The hydroxyl group-containing (meth) acrylate may be a (meth) acrylate containing one or more hydroxyl groups. For example, hydroxyl-containing (meth) acrylates include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, 1-chloro-2-hydroxy Hydroxypropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, Neopentyl glycol mono (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolethane di (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4- Hydroxycyclopentyl (meth) acrylate Ytite, 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%, 10% to 30% of the sum of the hydroxyl group-containing (meth) acrylate and the alkyl group-containing (meth) acrylate. It may be included in weight percent. The adhesive strength and durability reliability of the adhesive layer in the above range may 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 unsubstituted linear or branched alkyl (meth) acrylic acid esters 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 Late, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) Acrylate, decyl (meth) acrylate, lauryl (meth) acrylate and isobornyl (meth) acrylate. The alkyl group-containing (meth) acrylate is 60% by weight to 95% by weight, for example, 65% by weight to 92% by weight, 68% by weight to 90% from the sum of the hydroxyl group-containing (meth) acrylate and the alkyl group-containing (meth) acrylate It may be included in weight%, 70% to 90% by weight. The adhesive strength and durability reliability of the adhesive layer in the above range may be further improved.

The monomer mixture may further include a copolymerizable monomer. The copolymerizable monomer is included in the (meth) acrylic copolymer, and may provide additional effects to the (meth) acrylic copolymer, the adhesive composition, or the adhesive layer. The copolymerizable monomer is a monomer different from a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate, 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.

As the monomer having ethylene oxide, one or more (meth) acrylate-based monomers containing an ethylene oxide group (-CH ₂ CH ₂ O-) can be used. 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 monotertyl ether (meth) acrylate, but is not limited thereto.

Monomers having propylene oxide include polypropylene oxide monomethyl ether (meth) acrylate, polypropylene oxide monoethyl ether (meth) acrylate, polypropylene oxide monopropyl ether (meth) acrylate, and 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 alkyl ether (meth) acrylates such as acrylate, polypropylene oxide monoisobutyl ether (meth) acrylate, and polypropylene oxide monoterbutyl ether (meth) acrylate, but it is not necessarily limited thereto. no All.

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

The monomer having an alkoxy group is 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) ) Acrylate, 3-butoxyhexyl (meth) acrylate, but is not limited thereto.

Monomers having a phosphoric acid group include 2-methacryloyloxyethyl diphenyl phosphate (meth) acrylate, trimethacryloyloxyethyl phosphate (meth) acrylate, and triacryloyloxyethyl phosphate (meth) acrylate. It may be an acrylic monomer having a phosphoric acid group, but is not limited thereto.

The monomer having a sulfonic acid group may be an acrylic monomer having a sulfonic acid group such as sodium sulfopropyl (meth) acrylate, sodium 2-sulfoethyl (meth) acrylate, sodium 2-acrylamido-2-methylpropanesulfonic acid. However, it is not necessarily 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, and phenoxyethyl (meth) acrylate, but is necessarily limited thereto. It does not work.

The monomer having a silane group is 2-acetoacetoxyethyl (meth) acrylate, vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tris (2-methoxyethyl) silane, vinyl triacetoxysilane, (meth) acrylic It may be a vinyl monomer having a silane group such as royloxypropyl trimethoxysilane, but is not 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, fumaric acid And maleic anhydride, and the like, but is not 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 is 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 hydroxyl group-containing (meth) acrylate and alkyl group-containing (meth) acrylate total You can. The pressure-sensitive adhesive composition in the above range can further improve the adhesion and recovery properties of the pressure-sensitive adhesive film.

The initiator may be used to cure (partially polymerize) the monomer mixture with a (meth) acrylic copolymer or to cure a viscous liquid into a film. The initiator may include at least one of a photopolymerization initiator and a thermal polymerization initiator. Any photopolymerization initiator may be used as long as it can induce the polymerization reaction of the radically polymerizable compounds described below in the curing process by light irradiation or the like. For example, a benzoin-based, hydroxy-ketone-based, amino-ketone-based or phosphine oxide-based photoinitiator can be used. The thermal polymerization initiator is not particularly limited as long as it has the above-described physical properties, and for example, a conventional initiator such as an azo-based compound, a peroxide-based compound, or a redox-based 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 (meth) acrylate and alkyl group-containing (meth) acrylate constituting the (meth) acrylic copolymer Can be included. In the above range, the curing reaction can proceed completely, the residual amount of initiator remains, and the transmittance can be prevented from being lowered, and the generation of air bubbles can be lowered and excellent reactivity can be obtained.

The macromonomer has a functional group that is curable by active energy rays, and can be polymerized with a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate. Specifically, the macromonomer may be represented by Formula 1 below:

<Formula 1>

(In Formula 1, R ¹ is hydrogen or a 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 (Meth) acrylate, t-butyl (meth) acrylate, styrene, a polymer chain obtained by polymerizing one or two or more selected from (meth) acrylonitrile).

The macromonomer may have a number average molecular weight of 2,000 to 20,000, specifically 2,000 to 10,000, and more specifically 4,000 to 8,000. Within the above range, sufficient adhesive strength can be obtained, excellent heat resistance, and reduction in workability due to increase in viscosity of the pressure-sensitive adhesive composition can be suppressed. The macromonomer may have a glass transition temperature of 40 ° C to 150 ° C, specifically 60 ° C to 140 ° C, and more specifically 80 ° C to 130 ° C. In the above range, the adhesive layer can exhibit sufficient cohesive force, and can suppress a sticky degree or a decrease in adhesive force.

The divalent linking group is a C1 to C10 alkylene group, a C7 to C13 arylalkylene group, a C6 to C12 arylene group, -NR ^2- (where R ² is hydrogen, or a 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 formulas 1a to 1d:

<Formula 1a>

<Formula 1b>

<Formula 1c>

<Formula 1d>

(In the formulas 1a to 1d, * is a linkage site of an element)

The commercially available macromonomer can be used. For example, while the terminal is a methacryloyl group, the macromonomer where the segment corresponding to Y is methyl methacrylate, the macromonomer where the segment corresponding to Y is styrene, and the segment corresponding to Y is styrene / acrylic. The macromonomer which is a nitrile, the macromonomer whose segment is a butyl acrylate segment, 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, and 0.5 parts by weight based on 100 parts by weight of the total amount of the hydroxyl group-containing (meth) acrylate and alkyl group-containing (meth) acrylate Part to 5 parts by weight may be included. In the above range, it is possible to balance the viscoelasticity, modulus and resilience of the adhesive layer, and to prevent the haze of the adhesive layer 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, it does not affect the folding of the adhesive layer, and the total light transmittance in the visible light region is 90% or more, so the transparency of the adhesive layer may be good.

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 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 adhesive layer may be excellent.

The organic nanoparticles may include core-shell type and simple nanoparticles such as bead type, but are not limited thereto. 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 the above-described particle form, the adhesive layer has good folding properties, and may have an effect on balance properties of elasticity and flexibility.

<Equation 2>

Tg (c) <Tg (s)

(In the formula 2, Tg (c) is the glass transition temperature of the core (unit: ℃), Tg (s) is the glass transition temperature of the shell (unit: ℃)).

"Shell" as used herein refers to the outermost layer of organic nanoparticles. The core may be one spherical particle. However, the core may further include 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 ° C to 10 ° C, specifically -150 ° C to -5 ° C, more specifically -150 ° C to -20 ° C. In the above range, there may be 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 glass transition temperature.

Polyalkyl (meth) acrylates include polymethylacrylate, polyethylacrylate, polypropylacrylate, polybutylacrylate, polyisopropylacrylate, polyhexylacrylate, polyhexylmethacrylate, and polyethylhexylacrylate And it may include one or more of polyethylhexyl methacrylate, polysiloxane, but is not limited thereto.

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

The crosslinking state of the organosiloxane (co) polymer can be determined by the degree of dissolution by various organic solvents. The deeper the crosslinking state, the smaller the degree of dissolution by the solvent. Acetone, toluene, or the like can be used as a solvent for determining the crosslinking state, and specifically, the organosiloxane (co) polymer may have a portion that is not dissolved by acetone or toluene. The organosiloxane copolymer may have an insoluble component in toluene of 30% or more.

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

Specifically, the glass transition temperature of the shell may be 15 ° C to 150 ° C, specifically 35 ° C to 150 ° C, more specifically 50 ° C to 140 ° C. In the above range, the dispersibility of the organic nanoparticles in the (meth) acrylic copolymer may be excellent. The shell may include polyalkyl methacrylate having the glass transition temperature. For example, polymethylmethacrylate (PMMA), polyethylmethacrylate, polypropyl methacrylate, polybutylmethacrylate, polyisopropylmethacrylate, polyisobutylmethacrylate and polycyclohexylmethacrylate It may include one or more of the rate, but is not limited thereto.

The core may include 30 to 99% by weight of the organic nanoparticles, specifically 40 to 95% by weight, and more specifically 50 to 90% by weight. In the above range, the foldability of the adhesive layer in a wide temperature range may be good. The shell may be included in 1% to 70% by weight of the organic nanoparticles, specifically 5% to 60% by weight, and more specifically 10% to 50% by weight. In the above range, the foldability 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 alkyl group-containing (meth) acrylate It may be included in 8 parts by weight. In the above range, the modulus of the adhesive layer at a high temperature can be increased, the foldability at room temperature and high temperature of the adhesive layer can be improved, and the viscoelasticity at low temperature and / or room temperature of the adhesive layer can be excellent.

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

The pressure-sensitive adhesive composition may further include a silane coupling agent. Silane coupling agents can be used conventionally known to those skilled in the art. For example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyl dimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyl tree 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, and 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 to these. 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 may be secured in the bending state at the high temperature and high humidity described above, and the difference in peel force between low temperature, normal temperature, and high temperature may be low.

The pressure-sensitive adhesive composition may further include a crosslinking agent. The crosslinking agent may increase the mechanical strength of the adhesive layer by increasing the degree of crosslinking of the adhesive composition. The crosslinking agent may include a polyfunctional (meth) acrylate capable of curing with active energy rays, for example, a bifunctional (meth) acrylate such as hexanediol diacrylate, or a trifunctional to 6functional (meth) acrylate. You can. The crosslinking agent is 0.001 part by weight to 5 parts by weight, specifically 0.003 part by weight to 3 parts by weight, specifically 0.005 part by weight to 1 part by weight, based on 100 parts by weight of the total of the (meth) acrylate containing the hydroxyl group and the (meth) acrylate containing the alkyl group It can be included as a wealth. In the above range, there is an effect of increasing excellent adhesion and reliability.

In another embodiment, the intermediate layer 120 may be formed by curing a self-adhesive or self-adhesive resin. The self-adhesive or self-adhesive resin has no tackiness or tackiness before curing, but is applied to any one of the first base layer 110 and the second base layer 130 and is cured after bonding the remaining base layer and then curing. It may contain the usual resin shown.

The intermediate layer 120 may have a thickness of 10 μm or more, preferably 15 μm or more and 50 μm or less. In the above range, impact resistance, scratch resistance, and folding property may be excellent.

The second base layer 130 is formed on the intermediate layer 120 to protect the hard coating layer 140.

The second base layer 130 may be a non-adhesive film or coating layer having a thickness of 100 μm or more and 200 μm or less and Shore hardness of 93A to 98A. When having the thickness and Shore hardness range, the protective film may have an excellent impact resistance and scratch resistance.

In one embodiment, the second base layer 130 may be a film formed of the thermoplastic polyurethane described above in the first base layer 110. The second base layer may exhibit the same or different materials and thicknesses compared to the first base layer 110. For example, the second base layer is a thermoplastic polyurethane and other non-urethane-based optical resins, such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and the like. , Cellulose esters including cyclic olefin polymer (COP), triacetyl cellulose (TAC), polyvinyl acetate, polyvinyl chloride (PVC), polynorbornene, polycarbonate (PC), polyamide, polyacetal, It may be a film formed of one or more of polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, polyimide.

The second base layer 130 may be the optically isotropic film or retardation film described above in the first base layer 110. The second base layer 130 may have a phase difference of the optically isotropic film or retardation film described above in the first base layer 110.

The hard coating layer 140 may be formed on the second base layer 130 to protect the window film or various devices mounted under the window film in an optical display device, for example, a polarizing plate. The hard coating layer 140 is directly formed on the second base layer 130.

The hard coating layer 140 has a thickness of 3 µm or more and less than 20 µm, specifically 3 µm or more and 15 µm or less, and is directly formed on the second base layer 130 to improve impact resistance and scratch resistance even with a thin protective film. You can.

The hard coating layer 130 may have a refractive index of 1.40 to 1.75, specifically 1.45 to 1.65. In the above range, the refractive index of the second base layer is appropriate, so that the optical properties of the protective film may be good, and the screen visibility may be improved when laminated on the window film.

The hard coating layer 130 may have a refractive index difference (refractive index of the second base layer-refractive index of the hard coating layer) compared to the second base layer of 0.3 or less, for example, 0.01 to 0.2. In the above range, it can be used in an optical display device.

The hard coating layer 140 may be formed of a composition for a hard coating layer including urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, zirconia particles, initiator, and silicone-based additive. In this case, scratch resistance and impact resistance may be high even in a hard coating layer having a thickness of 3 μm or more and less than 20 μm, specifically 3 μm or more and 15 μm or less.

The urethane (meth) acrylate oligomer forms a matrix of the hard coating layer, and can increase the impact resistance, scratch resistance and folding property of the protective film. A protective film formed of a composition without a urethane (meth) acrylate oligomer may have problems in that adhesion between a second base layer formed of a thermoplastic polyurethane and a hard coating layer decreases and the scratch resistance of the protective film is poor.

The urethane (meth) acrylate oligomer is a 7- to 10-functional (meth) acrylate oligomer, and may have 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%. Within the above range, the impact resistance, scratch resistance, and bending resistance of the protective film can be improved. Preferably, the urethane (meth) acrylate oligomer is a 9- to 10-functional (meth) acrylate system, and may have a weight average molecular weight of 1500 g / mol or more and 2500 g / mol or less and an elongation of 5% or more and 10% or less. . In the above-mentioned range, the above-described impact resistance, scratch resistance, and folding property can be improved even in the hard coating layer having a thin thickness, and wear resistance can be further improved.

Urethane (meth) acrylate oligomer, urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, may be included in 10 to 50 parts by weight out of 100 parts by weight of the total of zirconia particles . In the above range, the impact resistance and scratch resistance of the protective film are excellent and the bending radius can be lowered together with the base layer to increase the folding property. Preferably, 20 parts by weight to 50 parts by weight, 25 parts by weight to 40 parts by weight, 20 parts by weight to 30 parts by weight may be included.

Urethane (meth) acrylate oligomers can be prepared by polymerization of polyfunctional polyols, polyfunctional isocyanate compounds and (meth) acrylate compounds having hydroxyl groups. 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, hydroxy Hydroxybutyl (meth) acrylate, chlorohydroxypropyl (meth) acrylate, hydroxyhexyl (meth) acrylate, and the like, but are not limited thereto.

The epoxy (meth) acrylate oligomer forms a matrix of the hard coating layer, and can increase the impact resistance, scratch resistance, and folding property of the protective film. The protective film formed of the composition without the epoxy (meth) acrylate oligomer may have problems that the scratch resistance is poor and the folding property is poor compared to the composition to which the epoxy (meth) acrylate oligomer is added.

The epoxy (meth) acrylate oligomer may include an oligomer having two or more functional (meth) acrylate groups. Specifically, the epoxy (meth) acrylate may include an oligomer obtained by modifying a bisphenol-based, for example, bisphenol A, bisphenol F, bisphenol S, preferably bisphenol A epoxy resin with a (meth) acrylic compound.

Epoxy (meth) acrylate oligomer is urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, 10 to 50 parts by weight of 100 parts by weight of the total of zirconia particles, for example It may be included in 20 parts by weight to 50 parts by weight, 30 parts by weight to 35 parts by weight. In the above range, the above-described impact resistance, scratch resistance, and folding property can be improved even in the thin-walled hard coating layer.

The (meth) acrylate monomer is a bifunctional to hexafunctional (meth) acrylate monomer, and can be cured together with a urethane (meth) acrylate oligomer and an epoxy (meth) acrylate oligomer to increase hardness.

(Meth) acrylate monomers include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol (600) di (meth) Polyethylene glycol di (meth) acrylate including neoacrylate, neopentyl glycol adipate di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylic Rate, ethylene oxide-modified di (meth) acrylate, di (meth) acryloxy ethyl isocyanurate, allylated cyclohexyl di (meth) acrylate, tricyclodecanedimethanol (meth) acrylate, dimethylol dish Clopentane di (meth) acrylate, ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified tree Bifunctional (meth) acrylates such as tilpropane di (meth) acrylate, adamantane di (meth) acrylate or 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene ; Trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide Ethylene oxide-modified trimethylolpropane tri (meth) acrylate including trimethylolpropane tri (meth) acrylate, ethoxylated (6) trimethylolpropane tri (meth) acrylate, or tris (meth) Trifunctional (meth) acrylates such as acryloxyethyl isocyanurate; Tetrafunctional (meth) acrylates such as diglycerin tetra (meth) acrylate or pentaerythritoltetra (meth) acrylate; Pentafunctional (meth) acrylates such as dipentaerythritol penta (meth) acrylate; And six functional acrylates such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate, but are not limited thereto. Preferably, the (meth) acrylate monomer includes a mixture of the bifunctional and trifunctional (meth) acrylate monomers, thereby further improving the impact resistance and scratch resistance due to crosslinking density control.

The (meth) acrylate monomer is 20 parts by weight to 60 parts by weight of 100 parts by weight of the urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, and zirconia particles, for example 20 It may be included in parts by weight to 50 parts by weight, 35 parts by weight to 45 parts by weight. In the above range, the above-described impact resistance, scratch resistance, and folding property can be improved even in the thin-walled hard coating layer.

Preferably, the (meth) acrylate monomer may include a mixture of difunctional (meth) acrylate and trifunctional (meth) acrylate. In this case, the scratch resistance may be more excellent compared to when the bifunctional (meth) acrylate monomer is used alone. The bifunctional (meth) acrylate monomer may be included in an excessive amount compared to the bifunctional (meth) acrylate monomer. The bifunctional (meth) acrylate monomer may preferably be polyethylene glycol di (meth) acrylate including polyethylene glycol (600) di (meth) acrylate and the like. The trifunctional (meth) acrylate may preferably be ethylene oxide-modified trimethylolpropane tri (meth) acrylate, including ethoxylated (6) trimethylolpropane tri (meth) acrylate and the like. The trifunctional (meth) acrylate monomer may be included in 5 to 10 parts by weight out of 100 parts by weight of the urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, and zirconia particles. . The bifunctional (meth) acrylate monomer may be included in 30 to 35 parts by weight out of 100 parts by weight of the urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, and zirconia particles. . In the above range, there may be an effect of simultaneously satisfactory bending resistance and scratch resistance.

Zirconia particles can improve the scratch resistance of the hard coating layer together with urethane (meth) acrylate oligomers and epoxy (meth) acrylate oligomers. When silica particles are included instead of zirconia particles, scratch resistance may be deteriorated when combined with urethane (meth) acrylate oligomers and epoxy (meth) acrylate oligomers. The zirconia particles may have an average particle diameter (D50) of 200 nm or less, specifically 5 nm or more and 100 nm or less. Within this range, the haze of the hard coating layer is not increased, and scratch resistance can be improved. The average particle diameter (D50) means a common average particle diameter known to those skilled in the art.

The zirconia particles may not be surface treated, but the surface is treated with a (meth) acrylate compound to provide a protective film due to good dispersibility with urethane (meth) acrylate oligomers, epoxy (meth) acrylate oligomers, and (meth) acrylate monomers. Can lower haze.

Zirconia particles are urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, 0.01 to 10 parts by weight of 100 parts by weight of the total of zirconia particles, for example, 1 to 4 parts by weight It may be included in parts by weight, 2 parts by weight to 5 parts by weight. In the above range, the above-described impact resistance, scratch resistance, and folding property can be improved even in the thin-walled hard coating layer.

The initiator may include a radical type photoinitiator. The initiator may be an acetophenone compound, a benzyl ketal type compound, or a mixture thereof, but is not limited thereto. Preferably an acetophenone-based compound, 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 propan-1-one, 2-benzyl-2-dimethyl amino-1- (4-morpholino phenyl) -butan-1-one, or mixtures thereof .

The initiator is 0.01 parts by weight to 10 parts by weight, specifically 1 part by weight to 5 parts by weight based on 100 parts by weight of the urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, and zirconia particles. It can be included as a wealth. In the above range, the curing reaction can proceed completely, the residual amount of initiator remains, it is possible to prevent the permeability from being lowered, it is also possible to lower the generation of bubbles 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 coating layer. For example, the silicone-based additive may include, but is not limited to, polyether-modified acrylic polydimethylsiloxane. The silicone-based additive is 0.01 parts by weight to 5 parts by weight, specifically 0.1 parts by weight to 2 parts by weight based on 100 parts by weight of the urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, and zirconia particles. It may be included in parts by weight, 0.1 parts by weight to 1 part by weight. In the above range, the surface properties of the hard coating layer may be good without affecting other components.

The composition for a hard coating layer may further include a solvent to facilitate coating properties of the composition for a hard coating layer. The solvent may include, but is not limited to, methyl ethyl ketone, methyl isobutyl ketone, and the like.

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, dyes, antistatic agents, leveling agents, surface energy modifiers, antifoaming agents, UV absorbers, low refractive agents, and the like.

The protective film 100 may have an indentation modulus of 0.3 GPa or more and less than 1.5 GPa measured by a nano indentor with respect to the hard coating layer 140. In the above range, the foldability and scratch resistance of the protective film are excellent. The protective film 100 may have an indentation hardness of 0.1 GPa or more and less than 0.3 GPa. In the above range, the foldability and scratch resistance of the protective film are excellent and can be used as a protective film. Since the protective film is located on the outermost side of the optical display device, it should be excellent in scratch resistance. Preferably, the protective film 100 has an indentation modulus of 0.4 GPa or more and less than 1.0 GPa, more preferably 0.4 GPa or more and less than 0.9 GPa, and an indentation hardness of 0.15 GPa or more and less than 0.3 GPa, more preferably measured by a nanoindenter. May be 0.15 GPa or more and 0.29 GPa or less.

The protective film 100 may have a radius of curvature of 5 mm or less, for example, 0 mm or more and 5 mm or less. Specifically, when the protective film 100 is folded in the direction of the hard coating layer 140, the radius of curvature may be 5 mm or less, for example, 0 mm or more and 5 mm or less. When folded in the direction of the first base layer 110, the protective film 100 may have a radius of curvature of 5 mm or less, 3 mm or less, for example, 0 mm or more, 5 mm or less, 0 mm or more and 3 mm or less. In the above range, it is excellent in folding property and can be used in a flexible optical display device.

The protective film 100 may have a thickness of 500 μm or less, specifically 310 μm to 500 μm. In the above range, it can be used in an optical display device. The protective film 100 has a total light transmittance of 91% or more, 91% to 99%, haze of 2% or less, 0% to 1.5%, and a yellow index (YI) of 1.1 or less in a visible light region, for example, at a wavelength of 380 nm to 780 nm. It can be 0 to 1.1. In the above range, it can be used in an optical display device.

Although not shown in FIG. 1, a functional layer is further formed on the hard coating layer to provide additional functions to the protective film. For example, the functional layer is one of anti-reflection, low reflection, anti-glare, anti-finger, anti-contamination, diffusion, and refraction functions. The above functions can be provided. The functional layer may be formed by applying a composition for forming a functional layer on the hard coating layer 140 or may be laminated on the hard coating layer 140 through an adhesive layer or an adhesive layer. In another embodiment, the functional layer may be formed such that one surface of the hard coating layer 140 is 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 and the protective film 100 according to an embodiment of the present invention, except that the adhesive layer 150 is further formed on the lower surface of the first base layer 110 It is practically the same. Since the adhesive layer 150 is further formed, the protective film 200 can be adhered to the window film or various optical elements mounted under the window film, for example, a polarizing plate, an optical sheet, and the like, and the folding property can be improved. .

The adhesive layer 150 may be formed of a pressure-sensitive adhesive composition applicable to the intermediate layer or a conventional pressure-sensitive adhesive composition known to those skilled in the art.

Although not illustrated in FIG. 2, a release film may be further formed on the lower surface of the adhesive layer 150. The release film is a conventional film known to those skilled in the art, and can prevent the adhesive layer from being contaminated by foreign substances.

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

Referring to FIG. 3, the flexible optical display device 300 includes a display unit 310, a polarizing plate 320, a touch screen panel 330, a window film 340, a protective film 350, and a protective film ( 350) may include a protective film according to an embodiment of the present invention.

The display unit 310 is for driving the flexible optical display device 300, and may include an optical element including an OLED, an LED, a quantum dot light emitting diode (QLED) or an LCD element formed on the substrate and the substrate. . Although not shown in FIG. 3, the display unit 310 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 polarizing plate 320 may implement polarization of internal light or prevent reflection of external light to implement a display or increase the contrast ratio of the display. The polarizing plate may be composed of a polarizer alone. Alternatively, the polarizing plate may include a polarizer and a protective film formed on one or both surfaces 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. As the polarizer, the protective film, and the protective coating layer, conventional ones known to those skilled in the art can be used.

The touch screen panel 330 detects a change in capacitance generated when a conductor such as a human body or a stylus touches, and generates an electrical signal. The display unit 310 may be driven by the signal. The touch screen panel 330 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 and crossing the first sensor electrode. have. Conductors for the touch screen panel 330 may include, but are not limited to, metal nanowires, conductive polymers, and carbon nanotubes.

The window film 340 may be formed outside the flexible optical display device 300 to protect the optical display device. The window film 340 may be a window coating layer alone or a film having a window coating layer formed on a base layer. The base layer is a poly (meth) acrylate resin including polyester resin, polycarbonate resin, polymethyl methacrylate, etc., including polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc., It may be a film comprising one or more of polystyrene resin, polyamide resin, polyimide resin, cycloolefin polymer. The base layer may be a single layer, or may be a multi-layer in which a plurality of films are laminated by an adhesive layer. For example, the base layer may be a film laminate in which the first film, the adhesive layer, and the second film are sequentially stacked. The adhesive layer may be formed of the above-described OCA adhesive composition. The window coating layer may be formed of a composition for a window coating layer comprising a silicone resin, a crosslinking agent, and an initiator.

Although not illustrated in FIG. 3, an adhesive film is further formed between the polarizing plate 320 and the touch screen panel 330 and / or between the touch screen panel 330 and the window film 340, thereby enabling the polarizing plate, touch screen panel, and window film It can strengthen the bond between the liver.

Hereinafter, an optical display device according to another embodiment of the present invention will be described with reference to FIG. 4. 4 is a cross-sectional view of an optical display device according to another embodiment of the present invention.

Referring to FIG. 4, the flexible optical display device 400 includes a display unit 310, a polarizing plate 320, a touch screen panel 330, a window film 340 ′, and a protective film 350 ′, a window The film 340 ′ may include a protective film according to an embodiment of the present invention.

The protective film 350 ′ may include a protective film for a window film that is commonly used. However, a case where the protective film 350 ′ includes a protective film according to an embodiment of the present invention may also be included in the scope of the present invention.

The flexible optical display device has been described above, but the optical display device of the present invention may also include a non-flexible optical display device.

The optical member of the present invention may include the protective film of the present invention.

In one embodiment, the optical member includes a window film and a protective film formed on the window film, and the protective film can include a protective film according to embodiments of the present invention. The window film and the protective film can be formed by directly contacting. The window film is not particularly limited, but may include a window coating layer formed of a base layer and a silicone resin for folding.

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

Each component of the composition for a protective film used in Examples and Comparative Examples is as follows.

(A) Urethane (meth) acrylate oligomer: UA11064 (manufacturer: Entis, 10-functional (meth) acrylate system, weight average molecular weight: 2,000 g / mol, elongation: 6%, solid content: 100%)

(B) Epoxy (meth) acrylate oligomer: CN120 (manufacturer: SARTOMER, bisphenol A epoxy system, bifunctional (meth) acrylate system)

(C) (C1) (meth) acrylate monomer: SR499 (manufacturer: Sartomer, trifunctional (meth) acrylate system, solid content 100%)

(C2) (meth) acrylate monomer: SR610 (manufacturer: Sartomer, bifunctional (meth) acrylate system, solid content 100%)

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

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

(F) Initiator: Irgacure 184 (manufacturer: BASF, 25% solids)

(G) Solvent: methyl ethyl ketone (manufacturer: Samjeon Pure Medicine)

(H) Silica particles: SSI330U (manufacturer: Ranco, average particle diameter (D50): 20 nm to 50 nm)

* The elongation of urethane (meth) acrylate oligomer was evaluated by an Instron measurement method.

Example  One

Based on solid content, (A) 26.00 parts by weight of urethane (meth) acrylate oligomer, (B) 32.50 parts by weight of epoxy (meth) acrylate oligomer, 6.50 parts by weight of (C1) (meth) acrylate monomer, (C2) (meth) ) 32.50 parts by weight of acrylate monomer, (D) 2.50 parts by weight of zirconia particles, (E) 0.10 parts by weight of silicon-based additive, (F) 3.00 parts by weight of the above ingredients are mixed and 55 parts by weight of methyl ethyl ketone as a solvent By doing so, a composition for a hard coating layer was prepared.

The core is a poly-butyl acrylate (PBA), the shell is a core-shell structure composed of polymethyl methacrylate (PMMA), the shell is 40% by weight of the organic nanoparticles, the average particle diameter is 230 nm, the refractive index is 1.48 Organic nanoparticles were prepared. 70 parts by weight of 2-ethylhexyl acrylate, 30 parts by weight of 4-hydroxybutyl acrylate, 4 parts by weight of the prepared organic nanoparticles and photopolymerization initiator (Irgacure 651) 0.005 parts by weight based on 100 parts by weight of the monomer mixture The parts were mixed well in a glass container. Partial polymerization with a hydroxyl group having a viscosity of about 1000 CPS by replacing dissolved oxygen in a glass container with nitrogen gas and irradiating ultraviolet light with a low pressure lamp (BL Lamp manufactured by Sankyo) for a few 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, 50 µm thick) to form an adhesive film having a predetermined thickness. After covering the release film with a thickness of 75 μm on the top, a transparent pressure-sensitive adhesive sheet was obtained by irradiating on both sides with a low pressure lamp (BL Lamp manufactured by Sankyo) for 6 minutes. The PET film was removed from the transparent adhesive sheet to obtain an adhesive layer having a predetermined thickness.

As the first base layer, the obtained adhesive layer was laminated on a thermoplastic polyurethane (TPU) film (thickness: 140 µm, Shore hardness: 96A, ΔE: 1.0 in Formula 1, manufacturer: Sheedom Co.).

A thermoplastic polyurethane (TPU) film (thickness: 140 µm, Shore hardness: 96A, ΔE: 1.0 in the above formula 1, manufacturer: Sheedom Co.) was laminated on the adhesive layer as a second base layer.

The composition for the hard coating layer prepared above was coated on the second base layer, dried at 80 ° C. for 2 minutes, and irradiated with a light amount of 300 mJ / cm ² under a nitrogen purging condition under a light source (metal halide lamp) to make a hard 5 μm thick. A coating layer was formed.

A protective film was prepared by adhering an adhesive layer (thickness: 30 µm) to the other surface of the first base layer. The adhesive layer was formed of an acrylic adhesive.

Example  2 to Example  4

A protective film was prepared in the same manner as in Example 1, except that the first base layer and the second base layer were changed as shown in Table 1 below.

Example 5  To Example  7

In Example 1, except for changing the content of (A), (B), (C), (D), (E), (F) in the composition for the hard coating layer as in Table 2 below, in the same manner A protective film was prepared.

Comparative example  1 to Comparative example  7

A protective film was prepared in the same manner as in Example 1, except that the first base layer and the second base layer were changed as shown in Table 1 below.

Comparative example  8 to Comparative example  10

In Example 1, except that the content of (A), (B), (C), (D), (E), (F), (H) in the composition for the hard coating layer was changed as shown in Table 2 below A protective film was prepared in the same way.

1st base layer 2nd base layer Hard coating layer
Thickness (㎛) Total thickness *
(㎛) material thickness
(㎛) Shore hardness material thickness
(㎛) Shore hardness Example 1 TPU 140 96A TPU 140 96A 5 310 Example 2 TPU 140 96A TPU 200 96A 5 370 Example 3 TPU 200 96A TPU 140 96A 5 370 Example 4 TPU 200 96A TPU 200 96A 5 430 Comparative Example 1 - - - TPU 140 96A 5 140 Comparative Example 2 - - - TPU 200 96A 5   200 Comparative Example 3 TPU 100 98A TPU 100 98A 5 230 Comparative Example 4 TPU 50 96A TPU 100 98A 5 180 Comparative Example 5 TPU 100 98A TPU 50 96A 5 180 Comparative Example 6 TPU 200 96A TPU 50 96A 5 280 Comparative Example 7 TPU 50 96A TPU 200 96A 5 280

* Total thickness: the first base layer; A second base layer; And the total thickness of the intermediate layer formed between the first base layer and the second base layer.

(A) (B) (C) (D) (E) (F) (H) (C1) (C2) Example 1 26.00 32.50 6.50 32.50 2.50 0.10 3.00 0.00 Example 5 30.00 30.00 7.50 30.00 2.50 0.10 3.00 0.00 Example 6 22.00 35.00 5.50 35.00 2.50 0.10 3.00 0.00 Example 7 25.60 32.50 6.40 32.50 3.00 0.10 3.00 0.00 Comparative Example 8 26.00 32.50 6.50 32.50 0.00 0.10 3.00 2.50 Comparative Example 9 0.00 32.50 32.50 32.50 2.50 0.10 3.00 0.00 Comparative Example 10 62.00 10.00 15.50 10.00 2.50 0.10 3.00 0.00

The following physical properties were evaluated for the protective films of Examples and Comparative Examples, and the results are shown in Tables 3 and 4 below.

(1) Haze: Haze was measured by putting the protective films of Examples and Comparative Examples in NDH-9600 (Nippon denshoku) and pointing the hard coating layer toward the light source.

(2) Total light transmittance and yellow index (YI): The protective films of Examples and Comparative Examples were put in CM-3600A (Konica Minolta), and the total light transmittance and yellow index were measured by pointing the hard coating layer toward the light source, respectively.

(3) Foldability: A polyethylene terephthalate film (thickness: 75 µm) was laminated on the lower surfaces of the adhesive layers of the protective films of Examples and Comparative Examples to prepare specimens (length x width: 10 cm x 5 cm). When the specimens prepared at room temperature (25 ° C.) were folded to have a radius of curvature of 1 mm to be 1/2 in the longitudinal direction, the number of cracks generated in the folded portion was evaluated. The lower the number of cracks, the better the folding property. Among the specimens, folding toward the polyethylene terephthalate film was taken as the out folding direction (tensile direction), and folding toward the hard coating layer was taken as the in folding direction (compression direction).

(4) Scratch resistance: Specimens were prepared by laminating a glass plate (thickness: 75 µm) on the lower surface of the adhesive layer of the protective films of Examples and Comparative Examples. The prepared specimen was fixed to a surface property measuring instrument (Heidon), mounted with steel wool # 0000, raised a weight of 1.5 kg, and evaluated the number of scratches after 10 round trips to the 50 mm scale on the surface of the hard coating layer. Did. The lower the number, the higher the scratch resistance. When the scratch resistance is evaluated, the number of scratches is 5 or less, so the scratch resistance can be used.

(5) Pen Drop Impact Resistance: A polyethylene terephthalate film (thickness: 125 μm) was laminated on the lower surface of the adhesive layer of the protective films of Examples and Comparative Examples to prepare specimens. Among the prepared specimens, a ball pen (manufacturer: Bic) was freely dropped on a hard coating layer at a predetermined height to evaluate the first height at which cracks occurred on the surface of the hard coating layer. Cracks were confirmed with an optical microscope. The higher the height, the better the pen drop impact resistance. The height of 10cm or more can be used because of its high impact resistance.

Haze
(%)
Total light transmittance
(%)
YI
Folding property
Scratch resistance
(Count)
Pen drop impact resistance
(cm)
In folding
(Count) Folding out
(Count) Example 1 1.14 91.5 0.98 0 4 3 15 Example 2 1.10 91.56 1.02 0 3 4 > 15 Example 3 1.15 91.52 1.02 0 One 3 > 15 Example 4 1.17 91.47 1.09 0 4 5 > 15 Comparative Example 1 0.90 91.71 0.8 0 One One 5 Comparative Example 2 0.71 90.96 1.11 0 NG 2 11 Comparative Example 3 1.10 91.53 0.94 0 6 5 8 Comparative Example 4 1.16 91.62 0.87 0 4 9 7 Comparative Example 5 1.35 91.54 0.87 0 3 5 6 Comparative Example 6 1.27 91.57 0.92 0 8 5 9 Comparative Example 7 1.19 91.55 0.95 Excitement One 10 9

Haze
(%)
Glow beam
Transmittance
(%)
YI
Folding property Scratch resistance
(Count)
Pen drop impact resistance
(cm)
In folding
(Count) Folding out
(Count) Example 1 1.14 91.5 0.98 0 4 3 15 Example 5 1.11 91.54 0.95 0 4 3 15 Example 6 1.08 91.51 0.99 0 3 4 15 Example 7 1.13 91.5 0.94 0 3 4 15 Comparative Example 8 1.16 91.54 0.97 0 3 10 15 Comparative Example 9 1.14 91.57 1.15 0 2 NG > 15 Comparative Example 10 1.11 91.44 1.13 0 8 5 12

As shown in Table 3 to Table 4, the protective film according to an embodiment of the present invention has excellent folding, scratch resistance and impact resistance, and also has excellent scratch resistance, impact resistance, and folding property even in a thin thickness coating layer. A protective film was provided. In addition, the present invention provided a protective film excellent in optical properties.

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

Claims (24)

The first base layer, the intermediate layer, the second base layer, and the hard coating layer are sequentially formed,
The first base layer is formed of a thermoplastic polyurethane,
The first base layer, the intermediate layer, and the total thickness of the second base layer is 300㎛ or more, as a protective film for an optical display device,
The intermediate layer is a monomer mixture for a (meth) acrylic copolymer having a hydroxyl group; Initiator; And a (meth) acrylic adhesive layer formed of an adhesive composition comprising at least one of a macromonomer and organic nanoparticles. The first base layer, the intermediate layer, the second base layer, and the hard coating layer are sequentially formed,
The hard coating layer is formed of a composition for a hard coating layer comprising urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, zirconia particles, initiator, and silicone-based additive,
The urethane (meth) acrylate oligomer, the urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, includes 10 to 50 parts by weight out of 100 parts by weight of the total of zirconia particles As a protective film for an optical display device,
The intermediate layer is a monomer mixture for a (meth) acrylic copolymer having a hydroxyl group; Initiator; And a (meth) acrylic adhesive layer formed of an adhesive composition comprising at least one of a macromonomer and organic nanoparticles. The protective film for an optical display device according to claim 2, wherein the first base layer is formed of a thermoplastic polyurethane. The protective film for an optical display device according to claim 2, wherein the total thickness of the first base layer, the intermediate layer and the second base layer is 300 μm or more. The protective film for an optical display device according to claim 1 or 3, wherein the thermoplastic polyurethane is aliphatic or alicyclic. delete The protective film for an optical display device according to claim 1 or 2, wherein the first base layer has a thickness of 100 μm or more and 200 μm or less and a Shore hardness of 93A to 98A. The protective film for an optical display device according to claim 1 or 2, wherein the second base layer has a thickness of 100 μm or more and 200 μm or less and a Shore hardness of 93A to 98A. delete delete The protective film for an optical display device according to claim 1 or 2, wherein the hard coating layer has a thickness of 3 μm or more and 15 μm or less. According to claim 1, The hard coating layer is formed of a composition for a hard coating layer comprising a urethane (meth) acrylate oligomer, an epoxy (meth) acrylate oligomer, a (meth) acrylate monomer, zirconia particles, initiator, silicone-based additive, Protective film for optical displays. The urethane (meth) acrylate oligomer according to claim 2 or 12, wherein the urethane (meth) acrylate oligomer comprises a urethane (meth) acrylate oligomer having 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 an optical display device. The protective film for an optical display device according to claim 2 or 12, wherein the epoxy (meth) acrylate oligomer comprises a bisphenol-based epoxy (meth) acrylate oligomer. The protective film for an optical display device according to claim 2 or 12, wherein the zirconia particles have an average particle diameter (D50) of 100 nm or less. The urethane (meth) acrylate oligomer according to claim 2 or 12, wherein the urethane (meth) acrylate oligomer, an epoxy (meth) acrylate oligomer, a (meth) acrylate monomer, and 100 parts by weight of zirconia particles are added. Is 20 parts by weight to 30 parts by weight, the epoxy (meth) acrylate oligomer is 30 parts by weight to 35 parts by weight, the (meth) acrylate monomer is 35 parts by weight to 45 parts by weight, and the zirconia particles are 2 parts by weight to Included in 5 parts by weight, a protective film for an optical display device. The method of claim 2 or 12, wherein the urethane (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, (meth) acrylate monomer, with respect to 100 parts by weight of the total amount of zirconia particles, the silicone-based additive is 0.01 weight A protective film for an optical display device, which is included in parts to 5 parts by weight. The protective film for an optical display device according to claim 1 or 2, wherein an adhesive layer is further formed on a lower surface of the first base layer. The protective film for an optical display device according to claim 1 or 2, wherein a functional layer is further formed on an upper surface of the hard coating layer. The method of claim 19, wherein the functional layer is anti-reflection, low reflection, anti-glare, anti-finger, anti-contamination, diffusion, A protective film for an optical display device that provides one or more of the refraction functions. The protective film according to claim 1 or 2, wherein the protective film has a radius of curvature of 5 mm or less when folded in the direction of the first base layer. The protective film for an optical display device according to claim 1 or 2, wherein the second base layer includes an isotropic film or a retardation film. An optical member comprising the protective film for an optical display device according to claim 1 or 2. An optical display device comprising the protective film for the optical display device of claim 1 or claim 2.

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