KR102063208B1 - Composition for window film, flexible window film prepared using the same and flexible display apparatus comprising the same - Google Patents

Abstract

Provided is a composition for a window film comprising a siloxane resin of Formula 1, a crosslinking agent and an initiator of Formula 2, a flexible window film formed therefrom, and a flexible display device including the same.

Description

COMPOSITION FOR WINDOW FILM, FLEXIBLE WINDOW FILM PREPARED USING THE SAME AND FLEXIBLE DISPLAY APPARATUS COMPRISING THE SAME}

The present invention relates to a composition for a window film, a flexible window film formed therefrom, and a flexible display device including the same.

Recently, flexible display devices having flexibility to be folded and unfolded in display devices have been developed. In the flexible display device, various elements included in the device as well as the substrate should have flexibility. The window film should also be flexible and should not be cracked even after repeated bending, so it should be reliable and have good scratch resistance. Since the window film is prepared by coating and curing the composition for the coating layer on the base layer, curling may occur.

Background art of the present invention is disclosed in Japanese Patent Laid-Open No. 2007-176542.

The problem to be solved by the present invention is to provide a composition for a window film that can implement a flexible window film having a high hardness, good flexibility, low curl and optically transparent.

Another problem to be solved by the present invention is to provide a composition for a window film that can implement a flexible window film excellent in scratch resistance.

Another problem to be solved by the present invention is to provide a flexible window film having excellent flexibility, hardness, low curling resistance, and excellent scratch resistance.

Another object of the present invention is to provide a window film excellent in impact resistance.

The composition for a window film of the present invention may include a siloxane resin of Formula 1, a crosslinking agent and an initiator of Formula 2 below:

<Formula 1>

(R ¹ SiO _3/2 ) _x (R ² SiO _3/2 ) _y (R ³ R ⁴ SiO _2/2 ) _z (SiO _4/2 ) _w

(In Formula 1, R ¹ , R ² , R ³ , R ⁴ , x, y, z and w are as defined in the detailed description of the invention),

<Formula 2>

(In Formula 2, R ⁵ , R ⁶ are as defined in the following detailed description).

The flexible window film of the present invention is a flexible window film including a base layer and a coating layer formed on the base layer, and the flexible window film may be formed of the composition for a window film of the present invention.

The flexible display device of the present invention may include the flexible window film.

The present invention provides a composition for a window film that can implement a flexible window film having high hardness, good flexibility, low curl, and optically transparent.

The present invention provides a composition for a window film that can implement a flexible window film excellent in scratch resistance.

The present invention provides a flexible window film having excellent flexibility, hardness, low curl, and excellent scratch resistance.

The present invention provides a window film excellent in impact resistance.

1 is a cross-sectional view of a flexible window film according to an embodiment of the present invention.
2 is a cross-sectional view of a flexible window film according to another embodiment of the present invention.
3 is a cross-sectional view of a flexible window film according to another embodiment of the present invention.
4 is a cross-sectional view of a flexible display device according to an embodiment of the present invention.
5 is a cross-sectional view of a flexible display device according to another exemplary embodiment of the present invention.
6 is a schematic diagram of curl measurement.

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

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

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

As used herein, an "alicyclic epoxy group-containing functional group" means a substituted or unsubstituted C1 to C20 alkyl group having an alicyclic epoxy group, a substituted or unsubstituted C5 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 group. By aryl group, "alicyclic epoxy group" can be an epoxidized C4 to C20 cycloalkyl group, for example an epoxycyclohexyl group.

As used herein, a "glycidyl group-containing functional group" means a glycidoxy group; Substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C5 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group having a glycidyl group or glycidoxy group.

In this specification, "substituted" means, unless specifically stated, that at least one hydrogen atom of the functional group is a hydroxyl group, an unsubstituted C1 to C10 alkyl group, a C1 to C10 alkoxy group, a C3 to C10 cycloalkyl group, an unsubstituted C6 to It means substituted with an alkyl group of C1 to C10 substituted with an aryl group of C20, an arylalkyl group of C7 to C20, a C6 to C20 aryl group substituted with an alkyl group of C1 to C10, or an alkoxy group of C1 to C10.

As used herein, "halogen" means fluorine, chlorine, bromine or iodine.

In the present specification, "Ec" is a 2- (3,4-epoxycyclohexyl) ethyl group, and "Gp" is a 3-glycidoxypropyl group.

In the present specification, the "modulus" of the adhesive layer is a storage modulus, and is used as an auto strain condition at a shear rate of 1 rad / sec and a strain of 1% using ARES (Anton Paar, 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.

Hereinafter, a composition for a window film according to an embodiment of the present invention will be described. The composition for a window film according to the present embodiment may include a siloxane resin of Formula 1, a crosslinking agent and an initiator of Formula 2 below:

<Formula 1>

(R ¹ SiO _3/2 ) _x (R ² SiO _3/2 ) _y (R ³ R ⁴ SiO _2/2 ) _z (SiO _4/2 ) _w

(In Formula 1, R ¹ is an alicyclic epoxy group-containing functional group,

R ² is a glycidyl group-containing functional group,

R ³ and R ⁴ are each independently hydrogen, an alicyclic epoxy group-containing functional group, a glycidyl group-containing functional group, an unsubstituted or substituted C1 to C20 alkyl group, an unsubstituted or substituted C5 to C20 cycloalkyl group, or an unsubstituted or Substituted C6 to C20 aryl group,

0 <x <1, 0 <y ≦ 0.5, 0 ≦ z <1, 0 ≦ w <1, x + y + z + w = 1).

The composition for a window film according to the present embodiment includes a siloxane resin of Formula 1, and has excellent pencil hardness, appearance, and transparency, low curvature radius, good flexibility, low curling, and high enough hardness without nanoparticles such as oxide. It is possible to implement a window film having. In particular, even if the indentation hardness of the window film is low, scratch resistance can be improved and curling can be reduced.

Specifically, in Formula 1, 0 <y ≦ 0.5, 0 <y ≦ 0.3, 0 <y ≦ 0.2, specifically 0.01 ≦ y ≦ 0.15. In the above range, it is possible to implement a window film having high hardness, low curling, and excellent bending reliability. In particular, in the case of 0.01 ≦ y ≦ 0.15, a difference in refractive index compared to the base layer when the base layer is coated can be implemented to achieve a window film having good optical transparency.

Specifically, R ¹ may be an unsubstituted or substituted C1 to C10 alkyl group having an alicyclic epoxy group, more specifically an epoxycyclohexylethyl group, or an epoxycyclohexylmethyl group. Specifically, R ² may be an unsubstituted or substituted C1 to C10 alkyl group, more specifically a glycidoxypropyl group, having a glycidoxy group. Specifically, R ³ and R ⁴ are each independently a methyl group, an ethyl group, a phenyl group, a (3,4-epoxycyclohexyl) methyl group, a (3,4-epoxycyclohexyl) ethyl group, (3,4-epoxycyclohexyl) propyl Groups or glycidoxypropyl groups.

The siloxane resin of Formula 1 may have a weight average molecular weight of 1,000 g / mol to 10,000 g / mol, specifically 5,000 g / mol to 10,000 g / mol, more specifically 5,000 g / mol to 7,000 g / mol. Supporting the coating layer of the window film in the above range, it can be effective to lower the curling, improve scratch resistance. The siloxane resin of Formula 1 may have a polydispersity (PDI) of 1.0 to 4.0, specifically 1.5 to 3.0, epoxy equivalent of 0.1 mol / 100 g to 1.0 mol / 100 g, specifically 0.3 mol / 100 g to 0.8 mol / 100 g. have. The coating properties in the polydispersity and epoxy equivalent range may be good while the coating properties are stable.

Hereinafter, specific examples of the siloxane resin of Formula 1 will be described.

In one embodiment, the siloxane resin of Formula 1 may be a siloxane resin in T units and T units of Formula 1-1:

<Formula 1-1>

(R ¹ SiO _3/2 ) _x (R ² SiO _3/2 ) _y

(In Formula 1-1, R ¹ and R ² are the same as defined in Formula 1,

0.5 ≦ x <1, 0 <y ≦ 0.5, x + y = 1). In Formula 1-1, 0.70 ≦ x <1, 0 <y ≦ 0.30, specifically 0.80 ≦ x <1, 0 <y ≦ 0.20, more specifically 0.85 ≦ x ≦ 0.99, 0.01 ≦ y ≦ 0.15. have. In the above range, it is possible to implement a window film having high hardness, low curvature radius, flexibility, low curling, and high bending reliability. Specifically, the siloxane resin of Formula 1-1 may be (EcSiO _3/2 ) _x (GpSiO _3/2 ) _y .

The siloxane resin of Formula 1 may be included in 50 parts by weight to 99.9 parts by weight, specifically 50 parts by weight to 90 parts by weight of the total 100 parts by weight of the siloxane resin of Formula 1 and the crosslinking agent of Formula 2. In the above range, the hardness and flexibility of the coating layer of the window film may be good.

When the crosslinking agent of Formula 2 is combined with the siloxane resin of Formula 1, the curing reaction speed between the oxetane group and the siloxane resin of the crosslinking agent is high, the curing rate may be increased, the indentation hardness may be increased, and the scratch resistance may be high due to the hydroxyl group of the crosslinking agent. It is possible to realize a window film having low curling and excellent flexibility (particularly, compression direction). In general, the higher the indentation hardness, the better the scratch resistance. However, when the crosslinking agent having a hydroxyl group and an oxetane group is added as in Chemical Formula 2, the scratch resistance may be excellent even if the indentation hardness is low:

<Formula 2>

(In Formula 2, R ⁵ is hydrogen, an alkyl group having 1 to 10 carbon atoms unsubstituted or substituted with a hydroxyl group, an aryl group having 6 to 10 carbon atoms substituted or unsubstituted with a hydroxyl group, or substituted or unsubstituted with a hydroxyl group. An arylalkyl group having 7 to 10 carbon atoms,

R ⁶ is an alkylene group having 1 to 10 carbon atoms, a single bond or an alkoxylene group having 2 to 10 carbon atoms).

In general, the photocationic initiator has a lower curing rate of the siloxane resin than the photo radical initiator, and thus requires an additional aging step. The temperature and / or relative humidity in the aging process affects the cure rate. The aging process is generally carried out at 85 ° C. and 85% relative humidity conditions. However, during the aging process, the surface barrier property of the coating layer is increased to increase the barrier property of the surface, and thus the mechanical properties may be different due to different curing rates between the surface of the coating layer and the inside of the coating layer. For this reason, even if the indentation hardness (surface hardness) of a coating layer comes out high, scratch resistance may fall. By using the cross-linking agent of the formula (2) of the present invention, due to the oxetane group in the cross-linking agent of the formula (2) also increases the internal curing rate at the time of curing the composition to improve scratch resistance and further improve the indentation hardness. In addition, when an oxetane monomer having no hydroxyl group is used as a crosslinking agent, the curling value may be high and scratch resistance may not be good. In particular, the composition for a window film of the present invention may be excellent in scratch resistance even if the indentation hardness is low.

Specifically, in Formula 2, R ⁵ may be hydrogen or an alkyl group having 1 to 10 carbon atoms substituted or unsubstituted with a hydroxyl group. R ⁶ may be an alkylene group having 1 to 10 carbon atoms.

Specifically, the crosslinking agent of Formula 2 may include one or more of 3-ethyl-3-hydroxymethyloxetane, oxetane-3-methanol, 3-oxetanol, 3,3-oxetanedimethanol. Preferably, the crosslinking agent of formula (2) may comprise one or more of 3-ethyl-3-hydroxymethyloxetane, oxetane-3-methanol.

The crosslinking agent of Chemical Formula 2 may be included in an amount of 0.1 parts by weight to 50 parts by weight, specifically 10 parts by weight to 50 parts by weight, based on 100 parts by weight of the total amount of the siloxane resin of Formula 1 and the crosslinking agent of Formula 2. In the above range, the scratch resistance of the coating layer of the window film can be high and the curling can be low.

The initiator is to cure the siloxane resin of the formula (1) and the crosslinking agent of the formula (2), one or more of a photocationic initiator, an optical radical initiator may be used. Photocationic initiators can be used those commonly known to those skilled in the art. Specifically, onium salts containing cations and anions can be used. As a specific example of a cation, diphenyl iodonium, 4-methoxy diphenyl iodonium, bis (4-methylphenyl) iodonium, bis (4-tert- butylphenyl) iodonium, bis (dodecylphenyl) iodonium, (4- Triaryl sulfoniums, such as diaryl iodonium, such as methylphenyl) [4- (2-methylpropyl) phenyl] iodonium, triphenylsulfonium, and diphenyl-4-thiophenoxy phenylsulfonium, bis [4- (Diphenyl sulfonio) phenyl] sulfide etc. are mentioned. Specific examples of the anion include hexafluorophosphate, tetrafluoroborate, hexafluoroantimonate, hexafluoroarsenate, hexachloroantimonate, and the like. Preferably, a photocationic initiator can be used.

The initiator may be included in an amount of 0.1 parts by weight to 20 parts by weight, specifically 0.5 parts by weight to 10 parts by weight, based on 100 parts by weight of the total amount of the siloxane resin of Formula 1 and the crosslinking agent of Formula 2. In the above range, the siloxane resin can be sufficiently cured and the transparency of the window film can be prevented from decreasing with the remaining amount of initiator.

The composition for a window film according to the present embodiment may further include nanoparticles.

Nanoparticles can further increase the hardness of the window film. Nanoparticles may include, but are not limited to, one or more of silica, aluminum oxide, zirconium oxide, titanium oxide. The nanoparticles may be surface treated with at least a portion of the surface with a silicone compound for mixing with the siloxane resin. Nanoparticles may have a spherical shape, a plate shape, an amorphous shape, and the like, but an average particle diameter may be 1 nm to 200 nm, specifically 10 nm to 50 nm, but is not limited thereto. The nanoparticles may be included in an amount of 0.1 parts by weight to 60 parts by weight, specifically 10 parts by weight to 50 parts by weight, based on 100 parts by weight of the total amount of the siloxane resin of Formula 1 and the crosslinking agent of Formula 2. It is possible to increase the hardness of the window film without affecting the surface roughness and transparency of the window film in the average particle diameter and content range.

The composition for a window film according to the present embodiment may further include an additive. The additive may provide additional functionality to the window film. The additives may include additives that are typically added to the window film. Specifically, the additive may include, but is not limited to, UV absorbers, reaction inhibitors, adhesion enhancers, thixotropy agents, conductivity granters, colorant, stabilizers, antistatic agents, antioxidants, leveling agents. Do not. The reaction inhibitor may include ethynylcyclohexane. An adhesion promoter may include a silane compound having an epoxy or alkoxysilyl group. The thixotropic agent may include fumed silica and the like. The conductivity providing agent may include metal powder such as silver and copper aluminum. Dye control agents may include pigments, dyes and the like. The UV absorber can increase the light resistance of the window film. UV absorbers can be used conventional absorbents known to those skilled in the art. The additive may be included in an amount of 0.01 to 5 parts by weight, specifically 0.1 to 2.5 parts by weight, based on 100 parts by weight of the total amount of the siloxane resin of Formula 1 and the crosslinking agent of Formula 2. In the above range can improve the hardness and flexibility of the window film and implement the additive effect.

The composition for a window film according to the present embodiment may further include a solvent in order to facilitate coating, coatability, or processability. The solvent may include one or more of methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, but is not limited thereto.

The composition for a window film according to the present embodiment may have a refractive index of 1.4 to 1.6. In the above range, it is possible to implement a window film having excellent optical transparency by having a proper refractive index when directly coating the substrate layer, in particular the substrate layer formed of a polyimide resin.

Hereinafter, a flexible window film of an embodiment of the present invention will be described with reference to FIG. 1. 1 is a cross-sectional view of a flexible window film of one embodiment of the present invention.

Referring to FIG. 1, the flexible window film 100 according to the present embodiment includes a base layer 110 and a coating layer 120, and the coating layer 120 is a composition for a window film according to an embodiment of the present invention. Can be formed.

The base layer 110 may support the flexible window film 100 and the coating layer 120 to increase the mechanical strength of the flexible window film 100. The base layer 110 may be attached onto the display unit, the touch screen panel, or the polarizer by an adhesive layer. The base layer 110 may be formed of an optically transparent and flexible resin. For example, the resins include polyester resins including polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate and the like, polycarbonate resins, polyimide resins, polystyrene resins, polymethylmethacrylates, and the like. It may include at least one of poly (meth) acrylate resin, cycloolefin polymer resin. In particular, the film formed of the polyimide resin as the base layer 110 may have a refractive index of 1.6 to 1.7. The base layer 110 may have a thickness of 10 μm to 200 μm, specifically 20 μm to 150 μm, and more specifically 50 μm to 100 μm. It can be used for the flexible window film in the above range.

The coating layer 120 may be formed on the base layer 110 to protect the base layer 110, the display unit, the touch screen panel, or the polarizing plate, and may be used in a flexible display device having high flexibility and high hardness. The coating layer 120 may have a thickness of 5 μm to 100 μm, specifically 10 μm to 80 μm. It can be used for the flexible window film in the above range. Although not shown in FIG. 1, a functional surface layer such as an antireflection layer, an antiglare layer, a hard coating layer, an antistatic layer may be further formed on the other surface of the coating layer 120 to provide additional functions to the flexible window film. In addition, although not shown in FIG. 1, the coating layer 120 may be further formed on the other surface of the substrate layer 110.

The flexible window film 100 is optically transparent and can be used in a transparent display device. Specifically, the flexible window film 100 may have a light transmittance of 88% or more and specifically 88% to 100% in the visible light region, specifically, the wavelength 400nm to 800nm. It can be used as a flexible window film in the said range.

A flexible window film 100 may indentation hardness can be 35mN / mm ² to 100mN / mm ² to 35mN / mm ² or more specifically. Within this range, the hardness can be used as a window film. Generally, high indentation hardness does not mean high scratch resistance. Even if the indentation hardness is low, the flexible window film 100 of the present invention may have high scratch resistance.

The flexible window film 100 may have a compression radius of curvature of 5 mm or less, specifically 0.1 mm to 5 mm, and a tensile direction curvature radius of 5 mm or less, specifically 0.1 mm to 5 mm. The flexible window film 100 of the present invention has high flexibility in both the compression direction and the tensile direction, thereby increasing the usability when used as a window film of the display.

The flexible window film 100 may have a curl of 5 mm or less, specifically 0.1 mm to 5 mm. In the above range, the curling is low, it can be used as a flexible window film.

The flexible window film 100 may have a thickness of 50 μm to 300 μm. It can be used as a flexible window film in the said range.

Hereinafter, a flexible window 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 flexible window film according to another embodiment of the present invention.

2, the flexible window film 200 according to the present exemplary embodiment is substantially the same as the flexible window film 100 according to the exemplary embodiment of the present invention except that the adhesive window 130 further includes an adhesive layer 130. Do. Thus, only the adhesive layer 130 will be described below.

The adhesive layer 130 may adhere a polarizing plate, a touch screen panel, or a display that may be disposed below the flexible window film 200.

In one embodiment, the pressure-sensitive adhesive layer 130 may be formed of a pressure-sensitive adhesive layer containing a pressure-sensitive resin, such as (meth) acrylic resin, urethane resin, silicone resin, epoxy resin, curing agent, photoinitiator, silane coupling agent. The (meth) acrylic resin is a (meth) acrylic copolymer having an alkyl group, a hydroxyl group, an aromatic group, a carboxylic acid group, an alicyclic group, a heteroalicyclic group, or the like, and may include a conventional (meth) acrylic copolymer. Specifically, a (meth) acrylic monomer having a C1 to C10 unsubstituted alkyl group, a (meth) acrylic monomer having a C1 to C10 alkyl group having at least one hydroxyl group, a (meth) acrylic monomer having a C6 to C20 aromatic group , A (meth) acrylic monomer having a carboxylic acid group, a (meth) acrylic monomer having a C3 to C20 alicyclic group, and a monomer mixture containing at least one of a (meth) acrylic monomer having a C3 to C10 heteroalicyclic group can be formed. have. The curing agent is a polyfunctional (meth) acrylate, such as bifunctional (meth) acrylates such as hexanediol diacrylate; Trifunctional (meth) acrylate of trimethylolpropane tri (meth) acrylate; Tetrafunctional (meth) acrylates such as pentaerythritol tetra (meth) acrylate; 5-functional (meth) acrylates such as dipentaerythritol penta (meth) acrylate; 6 functional (meth) acrylates, such as dipentaerythritol hexa (meth) acrylate, may be included, but is not limited thereto. The photoinitiator may include the photoradical initiator described above as a conventional photoinitiator. The silane coupling agent may include a silane coupling agent having an epoxy group such as 3-glycidoxypropyltrimethoxysilane and the like. The adhesive layer composition may include 100 parts by weight of the (meth) acrylic resin, 0.1 parts by weight to 30 parts by weight of the curing agent, 0.1 parts by weight to 10 parts by weight of the photoinitiator, and 0.1 parts by weight to 20 parts by weight of the silane coupling agent. In the above range, the flexible window film may be attached well on the display unit, the touch screen panel or the polarizing plate.

In another embodiment, the adhesive layer 130 may be the adhesive layer 110c described below.

The adhesive layer 130 may have a thickness of about 10 μm to about 100 μm. Optical elements, such as a flexible window film and a polarizing plate, can fully be adhere | attached in the said range.

Hereinafter, a window film according to another embodiment of the present invention will be described with reference to FIG. 3. 3 is a cross-sectional view of a window film according to another embodiment of the present invention.

Referring to FIG. 3, the flexible window film 150 is substantially the same as the flexible window film 100 according to the present embodiment except that the substrate window 110 includes a substrate layer 110A instead of the substrate layer 110. .

The base layer 110A includes a first film 110a, a second film 110b, and an adhesive layer 110c formed between the first film 110a and the second film 110b. By including the base layer 110A, the flexible window film may further have an effect of further improving impact resistance. Specifically, the impact resistance may be 1.5 cm or more when the PEN DROP TEST. Within this range, it is possible to prevent panel damage when mounted on the OLED panel. In this case, the OLED panel may include an OELD panel commonly used by those skilled in the art.

The first film 110a and the second film 110b may respectively support the flexible window film 150. Each of the first film 110a and the second film 110b may be formed of the optically transparent and flexible resin. The first film 110a and the second film 110b may be formed of the same or different resins. For example, the first film 110a and the second film 110b are each formed of at least one resin of polyester resin, polycarbonate resin, polyimide resin, poly (meth) acrylate resin, and cyclic olefin polymer resin. It may be a film.

The first film 110a and the second film 110b may have different thicknesses or the same. The first film 110a and the second film 110b may each have a thickness of 10 μm to 100 μm, preferably 30 μm to 50 μm. In the above range, there may be an excellent effect of flexibility and impact resistance.

The base layer 110A may have a thickness of 10 μm to 200 μm, specifically 20 μm to 150 μm, and more specifically 50 μm to 110 μm. It can be used for the flexible window film in the above range.

3 illustrates a case where the coating layer 120 is directly formed on the second film 110b, but when the coating layer 120 is directly formed on the first film 110a, that is, the second film 110b and the adhesive layer ( 110c), the case where the first film 110a and the coating layer 120 are sequentially formed may also be included in the scope of the present invention.

The adhesive layer 110c may be formed between the first film 110a and the second film 110b to adhere them to each other. The adhesive layer 110c may increase the bending reliability when repeatedly folding the window film, and may increase the impact strength of the window film.

The adhesive layer 110c may have a modulus of 10 kPa to 1000 kPa at 25 ° C. In the above range, the impact resistance of the window film can be increased, and reliability may be good even once or repeatedly folding the window film at room temperature. Preferably, the adhesive layer 120 may have a modulus of 10 kPa to 800 kPa at 25 ° C.

The adhesive layer 110c may have a modulus of 10 kPa to 1000 kPa at 80 ° C. In the above range, the impact resistance of the window film can be increased, and reliability may be good even once or repeatedly folding the window film at high temperature and high humidity. Preferably, the adhesive layer 110c may have a modulus of 10 kPa to 800 kPa at 80 ° C.

The adhesive layer 110c may have a modulus of 10 kPa to 1000 kPa at -20 ° C. In the above range, the impact resistance of the window film can be increased, and reliability may be good even once or repeatedly folding the window film at a low temperature. Preferably, the adhesive layer 110c may have a modulus of 10 kPa to 500 kPa at -20 ° C.

The adhesive layer 110c may have a modulus at 25 ° C .: modulus at −20 ° C. of 1: 1 to 1: 4, specifically 1: 1 to 1: 3.5, and more particularly 1: 1 to 1: 2.8. have. In the above range, since the adhesive layer has a small change in physical properties due to temperature change in a wide temperature range (-20 ° C to 25 ° C), the stress of the adherend is reduced, and no peeling or bubbles are generated in the foldable test. It can be used for a flexible optical member.

The adhesive layer 110c may have a modulus of modulus: 80 ° C. at −20 ° C. of 1: 1 to 1:10, specifically 1: 1 to 1: 8, and more specifically 1: 1 to 1: 5. have. In the above range, the adhesive layer does not degrade the adhesive strength between the adhesives in a wide temperature range (-20 ° C. to 80 ° C.), and may be used for a flexible optical member.

The adhesive layer 110c may have a thickness of about 10 μm to about 75 μm. In the above range, there may be an excellent effect of flexibility and impact resistance. Preferably, the adhesive layer 110c may have a thickness of 10 μm to 50 μm and 10 μm to 30 μm.

The adhesive layer 110c may have a haze of 5% or less, specifically 3% or less, and more specifically 1% or less in the visible light region at a thickness of 100 μm. In the above range, excellent transparency is exhibited when the adhesive layer is used in an optical display device.

The adhesive layer 110c may have a glass transition temperature (Tg) of 0 ° C or less, for example, -150 ° C to 0 ° C, specifically -150 ° C to -20 ° C, and more specifically -150 ° C to -30 ° C. have. In the above range, the adhesive layer is excellent in viscoelastic properties at low and normal temperatures.

The adhesive layer 110c may be formed of an optical clear adhesive (OCA). The adhesive layer 110c may include a monomer mixture for a (meth) acrylic copolymer having a hydroxyl group; Initiator; And it may be formed of a composition for pressure-sensitive adhesive layer comprising one or more of macromonomer 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 composition for pressure-sensitive adhesive layer is 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. The alkyl group-containing (meth) acrylate is 60% to 95% by weight, for example, 65% to 92%, 68% to 90% by weight of the total of the hydroxyl group-containing (meth) acrylate and the alkyl group-containing (meth) acrylate. It may be included in the weight percent, 70% to 90% by weight. 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. Specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylanino acetophenone, 2,2-dimethone Methoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1one, 1-hydroxycyclohexylphenylketone, 2-methyl -1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone , p-phenylbenzophenone, 4,4-nondidiaminoaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methyl Thioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoic acid ester , Hitting [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane paddy] and 2,4,6-trimethylbenzoyl-phosphine oxide, etc. may be mentioned - diphenyl. The thermal polymerization initiator is not particularly limited as long as it has the above-described physical properties. For example, a common initiator such as an azo compound, a peroxide compound, or a redox compound can be used. Examples of the azo compound in the above are 2,2-azobis (2-methylbutyronitrile), 2,2-triazobis (isobutyronitrile), 2,2-triazobis (2,4-dimethyl Valeronitrile), 2,2-nitazobis-2-hydroxymethylpropionitrile, dimethyl-2,2-methylazobis (2-methylpropionate), and 2,2-pioazobis (4- Methoxy-2,4-dimethylvaleronitrile) and the like, and examples of the peroxide-based compound include inorganic peroxides such as potassium peroxide, ammonium persulfate or hydrogen peroxide; Or diacyl peroxide, peroxy dicarbonate, peroxy ester, tetramethylbutylperoxy neodecanoate, bis (4-butylcyclohexyl) peroxydicarbonate, di (2-ethylhexyl) peroxy carbonate, butylper Oxy neodecanoate, dipropyl peroxy dicarbonate, diisopropyl peroxy dicarbonate, diethoxyethyl peroxy dicarbonate, diethoxyhexyl peroxy dicarbonate, hexyl peroxy dicarbonate, dimethoxybutyl peroxy dicarbonate , Bis (3-methoxy-3-methoxybutyl) peroxy dicarbonate, dibutyl peroxy dicarbonate, dicetyl peroxy dicarbonate, dimyristyl peroxy dicarbonate, 1,1 , 3,3-tetramethylbutyl peroxypivalate, hexyl peroxy pivalate, butyl peroxy pivalate, trimethyl hexanoyl peroxide, dimethyl hydroxybutyl peroxy Odecanoate, amyl peroxyneodecanoate, butyl peroxyneodecanoate, t-butylperoxy neoheptanoate, amylperoxy pivalate, t-butylperoxy pivalate, t-amyl Organic peroxides such as peroxy-2-ethylhexanoate, lauryl peroxide, dilauuroyl peroxide, didecanoyl peroxide, benzoyl peroxide or dibenzoyl peroxide, and the like. Examples of the compound include, but are not limited to, a mixture using a peroxide compound and a reducing agent in combination.

The initiator 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 3:

<Formula 3>

(In Formula 3, 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 bond group is C1 to C10 alkylene group, C7 to C13 arylalkylene group, C6 to C12 arylene group, -NR ^2- (wherein R ² is hydrogen or C1 to C5 alkyl group), COO-,- O-, -S-, -SO ₂ NH-, -NHSO _2- , -NHCOO-, -OCONH, or a group derived from a heterocycle.

In addition, the divalent linking group may be represented by the following formula 3a to 3d:

<Formula 3a>

<Formula 3b>

<Formula 3c>

<Formula 3d>

(In Formulas 3a to 3d, * 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 Equation 1: 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 1>

Tg (c) <Tg (s)

(In Formula 1, 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 ℃. 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, and 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 pressure-sensitive adhesive layer 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-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 the composition for adhesion layers, and can raise the mechanical strength of an adhesion 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.

3 illustrates a case where the base layer is a film laminate in which the first film 110a and the second film 110b are laminated by the adhesive layer 110c. However, the case where the base material layer includes three or more films and at least two or more of them is a film laminate laminated with each other by the adhesive layer 110c may also be included in the scope of the present invention.

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

Referring to FIG. 4, the flexible display device 300 according to the present exemplary embodiment includes a display unit 350a, an adhesive layer 360, a polarizer 370, a touch screen panel 380, and a flexible window film 390. In addition, the flexible window film 390 may include a flexible window film according to embodiments of the present invention. 3 illustrates that the display unit 350a, the adhesive layer 360, the polarizer 370, the touch screen panel 380, and the flexible window film 390 are sequentially formed, but the display unit 350a and the touch screen panel are shown in FIG. 380, the polarizer 370, and the flexible window film 390 may be formed in this order. In this case, since the touch screen panel 380 is formed together with the display unit 350a, the display panel 350a may be thinner and brighter than the flexible display device according to the exemplary embodiment of the present invention, so that visibility may be good.

The display unit 350a is for driving the flexible display device 300 and may include a substrate and an optical element including an OLED, an LED, or an LCD element formed on the substrate.

The adhesive layer 360 adheres the display unit 350a and the polarizing plate 370, and may be formed of an adhesive composition including a (meth) acrylate-based resin, a curing agent, an initiator, and a silane coupling agent.

The polarizer 370 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 include a polarizer alone or a protective film formed on one or both sides of the polarizer and the polarizer. As the polarizer and the protective film, conventional ones known to those skilled in the art can be used.

The touch screen panel 380 may generate an electrical signal by detecting a change in capacitance. The touch screen panel 380 is formed by patterning a flexible and conductive conductor, and the conductor for the touch screen panel 380 may include metal nanowires, conductive polymers, carbon nanotubes, or the like. It is not limited.

The flexible window film 390 may be formed on the outermost side of the flexible display device 300 to protect the display device.

Although not shown in FIG. 4, an adhesive layer may be further formed between the polarizer 370 and the touch screen panel 380 and / or between the touch screen panel 380 and the flexible window film 390. The adhesive layer is as described above. In addition, although not shown in FIG. 4, a polarizer may be further formed below the display unit 350a to implement polarization of the internal light.

Hereinafter, a flexible display device according to another exemplary embodiment of the present invention will be described with reference to FIG. 5. 5 is a cross-sectional view of a flexible display device according to another exemplary embodiment of the present invention.

Referring to FIG. 5, the flexible display device 400 according to another exemplary embodiment of the present invention may be driven only by the display unit 350b, except that a polarizer and a touch screen panel are excluded. It is substantially the same as the flexible display device 300 according to the example. The display unit 350b may include a substrate and an optical element including an LCD, an OLED, or an LED element formed on the substrate, and the display unit 350b may have a touch screen panel therein.

4 and 5 illustrate a flexible display device, the present invention is not limited thereto, and the window film according to the embodiments may be applied to a non-flexible display device.

Hereinafter, the manufacturing method of the siloxane resin of General formula (1) of this invention is demonstrated.

The siloxane resin represented by Formula 1 of the present embodiment is a monomer mixture of the first silicone monomer of Formula 4 and the second silicone monomer of Formula 5 alone, or the third silicone monomer of Formula 6, to the monomer mixture, It can be prepared by the hydrolysis and condensation reaction of the monomer mixture further comprising one or more of the fourth silicon monomer of. Silicone monomers may be included alone or in combination of two or more kinds:

<Formula 4>

Si (R ¹ ) (R ⁷ ) (R ⁸ ) (R ⁹ )

<Formula 5>

Si (R ² ) (R ¹⁰ ) (R ¹¹ ) (R ¹² )

<Formula 6>

Si (R ³ ) (R ⁴ ) (R ¹³ ) (R ¹⁴ )

(In Chemical Formulas 4, 5 and 6, R ¹ , R ² , R ³ and R ⁴ are the same as defined in Chemical Formula 1, R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a halogen, a hydroxyl group or a C1 to C10 alkoxy group).

<Formula 7>

Si (OR ¹⁵ ) ₄

(In Formula 7, R ¹⁵ is an alkyl group of C1 to C10).

Specifically, the first silicon monomer is 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, (3,4-epoxycyclohexyl) methyltrimethoxysilane, 2- (3,4-epoxycyclohexyl ) Ethyltriethoxysilane, (3,4-epoxycyclohexyl) methyltriethoxysilane, and the like. Specifically, the second silicon monomer may include (3-glycidoxypropyl) trimethoxysilane, (3-glycidoxypropyl) triethoxysilane, and the like. Specifically, the third silicon monomer may include dimethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethylmethyldiethoxysilane, (3-glycidoxypropyl) methyldiethoxysilane, and the like. Specifically, the fourth silicon monomer may include one or more of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraisopropoxysilane. In one embodiment, the monomer mixture is at least 70 mol% of the first silicone monomers but less than 100 mol%, at least 80 mol% and less than 100 mol%, or 85 mol% to 99 mol%, greater than 0 mol% and less than 30 mol%, more than 0 mol% and 20 mol% or less of the second silicon monomer. Or 1 mol% to 15 mol%. In the above range, the pencil hardness is high, the appearance is good, and the curvature radius is also low can implement a good window film.

The hydrolysis and condensation reaction of the monomers can be carried out according to a conventional method for producing a siloxane resin. Hydrolysis can include reacting the monomer mixture in water and in a mixture of one or more of the desired acids, bases. Specifically, the acid may be HCl, HNO ₃ , acetic acid and the like, the base may be NaOH, KOH and the like. The hydrolysis may be performed at 20 ° C. to 100 ° C. for 10 minutes to 10 hours, and the condensation reaction may be performed at 20 ° C. to 100 ° C. for 10 minutes to 12 hours under the same conditions as the hydrolysis. In the above range, the production efficiency of the siloxane resin of the formula (1) can be increased.

Hereinafter, a method of manufacturing a flexible window film according to an embodiment of the present invention.

The method of manufacturing the flexible window film according to the present embodiment may include coating and curing the composition for a window film according to an embodiment of the present invention on the base layer 110. The method of coating the composition for the window film on the base layer 110 is not particularly limited, and the composition for the window film may be the base layer 110 by bar coating, spin coating, dip coating, roll coating, flow coating, or die coating. It can be coated on the thickness of 5㎛ to 100㎛. It is possible to secure the desired coating layer in the above range and may be excellent in hardness and flexibility, reliability. Curing may include one or more of light curing, thermal curing (aging). Light curing involving treatment for 10mJ / cm ² to is to investigate the quantity of light of 1000mJ / cm ^2, thermal curing is 40 ℃ to 200 ℃ and 1 hour to 30 hours from 50% to 85% relative humidity at a wavelength of 400nm or less can do. In the above range, the composition for a window film may be sufficiently cured. Preferably, the photocuring may be followed by thermosetting. Before the composition for window film is coated on the base layer 110 and then cured, the composition for the window film is dried and cured to prevent the surface roughness of the coating layer from being increased due to prolonged photo curing and thermal curing. Drying may be performed at 40 ° C. to 200 ° C. for 1 minute to 30 hours, but is not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example  One

99 mol% of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (KBM-303, Shin-Yestsu) and 1 mol% of (3-glycidoxypropyl) trimethoxysilane (KBM-403, Shin-Yestsu) 400 g of the containing silicone monomer mixture was placed in a 1 L 3-neck flask. Was added to the silicone monomer mixture compared to 0.1mol% of KOH and 1 equivalent of the total silicon monomer compared to water, and stirred at 65 ℃ for 8 hours, followed by washing with water and concentrated with _{toluene, (EcSiO 3/2) 0.99} (GpSiO 3 _{/ 2} ) _{0 .} A siloxane resin (weight average molecular weight: 5,500 g / mol by gel permeation chromatography (GPC)) of ₀₁ was prepared.

90 parts by weight of the siloxane resin prepared above, 10 parts by weight of the crosslinking agent OXT-101 (Toagosei, 3-ethyl-3-hydroxymethyl-oxetane), (4-methylphenyl) [4- (2-methylpropyl) phenyl as a photoinitiator ] 3 parts by weight of iodonium hexafluorophosphate (Irgacure-250, BASF) was mixed, and solvent methyl ethyl ketone was mixed to prepare a composition for a window coating layer (all components except solvent: 45 wt%).

The prepared composition for a window coating layer was applied to one surface of a transparent polyimide film (PI film, thickness: 80 μm) as a base layer with a Mey bar, dried at 80 ° C. for 5 minutes, and 1000 mJ / cm ² Was irradiated with UV and heated for 20 hours in an 85 ° C. and 85% relative humidity chamber to prepare a window film having a window coating layer (thickness: 10 μm) formed on one surface of the transparent polyimide film.

Example  2 to Example  5

A window film was manufactured in the same manner as in Example 1, except that the siloxane resin and the crosslinking agent content were changed as shown in Table 1 below.

Example  6

85 mol% of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (KBM-303, Shin-Yestsu) and 15 mol% of (3-glycidoxypropyl) trimethoxysilane (KBM-403, Shin-Yestsu) 400 g of the containing silicone monomer mixture was placed in a 1 L 3-neck flask. Was added to the silicone monomer mixture compared to 0.1mol% of KOH and 1 equivalent of the total silicon monomer compared to water, and stirred at 65 ℃ for 8 hours, followed by washing with water and concentrated with _{toluene, (EcSiO 3/2) 0.85} (GpSiO 3 _{/ 2} ) _{0 . 15} siloxane resin (weight average molecular weight: 5,500 g / mol by gel permeation chromatography (GPC)) was prepared.

A window film was prepared in the same manner as in Example 1 using the prepared siloxane resin.

Example  7

A window film was prepared in the same manner except in Example 1, 10 parts by weight of oxetane-3-methanol was used instead of 10 parts by weight of the crosslinking agent OXT-101.

Example  8

The core is a poly-butyl acrylate (PBA), the shell is a core-shell structure consisting of polymethyl methacrylate (PMMA), the shell is 40% by weight of the organic particles, an average particle diameter of 230 nm, an organic refractive index of 1.48 Nanoparticles were prepared. 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.

One side of the polyethylene terephthalate film (PET film, thickness: 40㎛) and one side of the other polyethylene terephthalate film (PET film, thickness: 40㎛) were adhered to the prepared adhesive layer, and the PET film, adhesive layer, and PET film were sequentially The film laminated body of the laminated 3-layered structure was manufactured.

The window film was manufactured by the method similar to Example 1 using the prepared film laminated body as a base material layer.

Comparative example  One

A window film was manufactured in the same manner as in Example 1, except that 10 parts by weight of the crosslinking agent CY-179 (CIBA, cyclic aliphatic epoxy crosslinking agent) was used instead of 10 parts by weight of the crosslinking agent OXT-101.

Comparative example  2

A window film was prepared in the same manner except in Example 1, 20 parts by weight of the crosslinking agent CY-179 was used instead of 10 parts by weight of the crosslinking agent OXT-101.

Comparative example  3

10 weight part of crosslinking agent OXT-221 (3-ethyl-3 [[[3-ethyloxetan-3-yl] methoxy] methyl] oxetane (without hydroxyl group) instead of 10 weight part of crosslinking agent OXT-101 in Example 1 A window film was manufactured in the same manner except that parts were used.

The physical properties of Table 1 were evaluated for the window films prepared in Examples and Comparative Examples.

(1) Indentation Hardness: The window film is placed on a 2T thick soda-lime glass plate at 25 ° C. with the window coating layer on top. The window coating layer was pressed with a constant force of 30mN load for 15 seconds, creep for 5 seconds, and relaxed for 20 seconds to measure the indentation hardness with a straight diamond pyramid-shaped micro indentor (Vicker particle) having a square base. Indentation hardness was measured using HM2000LT Micro Indentor (Fisher). Five measurements were taken to obtain an average value.

(2) Scuff test (scratch resistance test): Using a Scuff tester, the steel wool (Ribenon # 0000) mounted tip (diameter: 11 mm) on the window coating layer of the window film, load 2 kg, It is moved on the surface of the window coating layer under conditions of a speed of 60 mm / sec and a moving distance of 40 mm. Record the number of scratches that occurred after 30 iterations. The lower the number, the better the scratch resistance. If the number is less than five, it can be used as a window film.

(3) Curvature radius: Wind the window film (width x length, 3cmx15cm) to the curvature radius test JIG (CFT-200R, COVOTECH Co., Ltd.), hold the wound state for 5 seconds or more, and then crack the film in the film Whether it occurred was visually evaluated. The radius of curvature in the compression direction (compression direction) is measured by making the window coating layer contact JIG. The radius of curvature in the tensile direction is measured by allowing the window coating layer to contact JIG. The radius of curvature was measured by gradually decreasing the diameter of the JIG starting from the maximum radius of the JIG, and the minimum radius of the JIG in which no crack occurred was determined as the radius of curvature.

(4) Curing: Referring to FIG. 6, the window film 1 is cut horizontally x vertically (10 cm x 10 cm), placed on the bottom surface 2, and left at 25 ° C. and 40% relative humidity. The highest height H from 2) to the edge part of the flexible window film 1 was measured, and the average value was computed.

(5) Impact resistance: Adhesion film (thickness: 50 mu m, 3M OCA 8146) was attached to the window films of Examples and Comparative Examples, and the window film was placed on a polyethylene terephthalate (PET) film (thickness: 2500 mu m, Mitsubishi). The window coating layer was fixed at the top. An aluminum foil and a stainless plate (SUS plate) were sequentially placed on the lower surface of the PET film to prepare a specimen. Among the specimens, a pen with a weight of 5.8 g at a predetermined height and a ball size (diameter) of PEN of 0.7 mm was dropped from the window coating layer to evaluate an initial height of visually discernible marks on the surface of the aluminum foil and the window coating layer. The average value was obtained by repeating five times. The higher the initial height, the higher the impact resistance of the window film. According to PEN DROP TEST, if the initial height of the marks is more than 1.5cm, it means that there is no impact even if the OLED panel is mounted.

Example Comparative example One 2 3 4 5 6 7 8 One 2 3 Siloxane resin (parts by weight) 90 80 70 60 50 90 90 90 90 80 90 Crosslinking agent (parts by weight)


OXT-101 10 20 30 40 50 10 - 10 - - - Oxetane-3-methanol - - - - - - 10 - - - - CY-179 - - - - - - - - 10 20 - OXT-221 - - - - - - - - - - 10 Initiator
(Part by weight) 3 3 3 3 3 3 3 3 3 3 3 Substrate layer PI film PI film PI film PI film PI film PI film PI film Film laminate PI film PI film PI film Indentation hardness
(mN / mm ² ) 99 85 70 46.75 35 90 95 82 80 73 88 Scuff tests () 0 0 0 0 5 0 0 One 5 10 0 Radius of curvature
(mm)
Compression direction 2 2 2 One One 2 2 2 2 2 2 Tensile direction 5 4 3 2 One 4 5 5 10 7 10 curling
(mm) 0 0 0 2 5 5 0 0 0 0 10 Impact resistance
(cm) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2.5 1.5 1.5 1.5

As shown in Table 1, the composition for a window film of the present invention is excellent in scratch resistance and low curvature radius, excellent in flexibility, good impact resistance and low curling. In particular, the composition for window films of this invention was excellent in scratch resistance even if the indentation hardness was low.

On the other hand, Comparative Examples 1 to 2 including a crosslinking agent without an oxetane group had a high radius of curvature and thus had low flexibility and poor scratch resistance. In particular, Comparative Example 1 has a higher indentation hardness than Examples 3 to 5, but the scratch resistance was low according to the scuff test.

In addition, Comparative Example 3 containing an oxetane crosslinking agent having no hydroxyl group had a lower indentation hardness than that of Example 1 and a high curl value.

Simple modifications or changes of the present invention can be easily carried out 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)

A composition for a window film comprising a siloxane resin of the formula (1), a crosslinking agent of the formula (2) and an initiator,
<Formula 1>
(R ¹ SiO _3/2 ) _x (R ² SiO _3/2 ) _y (R ³ R ⁴ SiO _2/2 ) _z (SiO _4/2 ) _w
(In Formula 1, R ¹ is an alicyclic epoxy group-containing functional group,
R ² is a glycidyl group-containing functional group,
R ³ and R ⁴ are each independently hydrogen, an alicyclic epoxy group-containing functional group, a glycidyl group-containing functional group, an unsubstituted or substituted C1 to C20 alkyl group, an unsubstituted or substituted C5 to C20 cycloalkyl group, or an unsubstituted or Substituted C6 to C20 aryl group,
0 <x <1, 0.01≤y≤0.15, 0≤z <1, 0≤w <1, x + y + z + w = 1),
<Formula 2>

(In Formula 2, R ⁵ is hydrogen, an alkyl group having 1 to 10 carbon atoms unsubstituted or substituted with a hydroxyl group, an aryl group having 6 to 10 carbon atoms substituted or unsubstituted with a hydroxyl group, or substituted or unsubstituted with a hydroxyl group. An arylalkyl group having 7 to 10 carbon atoms,
R ⁶ is an alkylene group having 1 to 10 carbon atoms, a single bond or an alkoxylene group having 2 to 10 carbon atoms,
Of 100 parts by weight of the total amount of the siloxane resin of Formula 1 and the crosslinking agent of Formula 2, the siloxane resin of Formula 1 is 50 parts by weight to 90 parts by weight, the crosslinking agent of Formula 2 is contained in 10 parts by weight to 50 parts by weight Phosphorus, the composition for window films.
delete The method of claim 1, wherein the siloxane resin of Formula 1 is (EcSiO _3/2 ) _x (GpSiO _3/2 ) _y (wherein Ec is a 2- (3,4-epoxycyclohexyl) ethyl group, and Gp is a 3-glycol). A composition for a window film containing a cydoxy propyl group, 0.85 <= <= 0.99, 0.01 <= y <= 0.15, and x + y = 1) siloxane resin.
The composition of claim 1, wherein the siloxane resin of Formula 1 has a weight average molecular weight of 5,000 g / mol to 10,000 g / mol.
According to claim 1, wherein the crosslinking agent of Formula 2 comprises at least one of 3-ethyl-3-hydroxymethyloxetane, oxetane-3-methanol, 3-oxetanol, 3,3-oxetanedimethanol The composition for a window film.
delete A flexible window film comprising a substrate layer and a coating layer formed on the substrate layer, wherein the coating layer is formed of the composition for a window film of any one of claims 1, 3, 4, 5, flexible Window film.
The flexible window film of claim 7, wherein an adhesive layer is further formed on the other surface of the substrate layer.
The flexible window film of claim 7, wherein the flexible window film has a radius of curvature of 5.0 mm or less.
The method of claim 7, wherein the base layer comprises a film laminate,
The said film laminated body is a flexible window film in which two or more films are laminated | stacked by the adhesion layer.
The flexible window film according to claim 10, wherein the film laminate has a first film, a second film, and the first film and the second film laminated by the adhesive layer.
The method of claim 11, wherein the first film and the second film is a film formed of at least one resin, respectively, polyester resin, polycarbonate resin, polyimide resin, poly (meth) acrylate resin, cyclic olefin polymer resin Flexible window film.
The method of claim 11, wherein the pressure-sensitive adhesive layer is a monomer mixture for the (meth) acrylic copolymer having a hydroxyl group; Initiator; And a composition for a pressure-sensitive adhesive layer comprising at least one of macromonomers and organic nanoparticles.
The flexible window film of claim 13, wherein the monomer mixture comprises a hydroxyl group-containing (meth) acrylate and an alkyl group-containing (meth) acrylate.
The flexible window film of claim 14, wherein the monomer mixture further comprises a comonomer.
The flexible window film of claim 13, wherein the organic nanoparticles include core-shell particles satisfying Formula 1 below.
<Equation 1>
Tg (c) <Tg (s)
(In Formula 1, Tg (c) is the glass transition temperature (unit: ° C) of the core, Tg (s) is the glass transition temperature (unit: ° C) of the shell).
The flexible window film of claim 13, wherein the organic nanoparticles have an average particle diameter of 10 nm to 400 nm.
The flexible window film of claim 11, wherein each of the first film and the second film has a thickness of 10 μm to 100 μm, and the adhesive layer has a thickness of 10 μm to 75 μm.
A flexible display device comprising the flexible window film of claim 7.

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