KR20170141558A - Composition for window film, window film prepared by using the same and flexible display device comprising the same - Google Patents

Abstract

The present invention provides a composition for a window film capable of realizing the window film having high surface hardness and low curling, the window film formed by using the same, and a flexible display device including the same. The composition for a window film comprises: a first siloxane resin represented by a chemical formula 1 which is [R^1SiO_3/2]_a[SiO_4/2]_b[R^2SiO_3/2]_c or a chemical formula 2 which is [R^3SiO_3/2]_d[SiO_4/2]_e; and a second siloxane resin represented by a chemical formula 3 which is [R^4SiO_3/2]_f[R^5SiO_3/2]_g.

Description

TECHNICAL FIELD [0001] The present invention relates to a composition for a window film, a window film formed therefrom, and a flexible display device including the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0002]

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

In recent years, a flexible display device having flexibility capable of being folded and unfolded while replacing a glass substrate or a hardened substrate with a film in a display device has been developed. The flexible display device is thin, light and strong against impact, and it can be folded and unfolded, so that it can be manufactured in various forms.

In order to implement a flexible display device, various elements included in the device as well as the substrate must have flexibility. Among these, studies for developing a window film capable of replacing a high-hardness window glass substrate disposed at an outermost periphery of a display device have been actively conducted.

Korean Patent Laid-Open No. 10-2014-0004568 (Patent Document 1) discloses an optical film prepared by curing a hard-coating resin composition containing a siloxane resin containing an alicyclic epoxy group. The optical film produced according to Patent Document 1 has a high surface hardness but has a property of being brittle after being cured, resulting in poor flexibility, easy cracking, and curl characteristic, There is a problem that a problem occurs.

Therefore, there is a demand for development of a composition for a window film which has a high surface hardness and a small curl after curing.

It is an object of the present invention to provide a composition for a window film which is capable of realizing a window film having high surface hardness and low curling.

Another object of the present invention is to provide a window film formed by the composition for a window film and a flexible display device including the window film.

In one aspect, the present invention provides a resin composition comprising: a first siloxane resin represented by the following general formula (1) or (2); And a second siloxane resin represented by the following general formula (3).

[Chemical Formula 1]

[R ¹ SiO _3/2 ] _a [SiO _4/2 ] _b [R ² SiO _3/2 ] _c

Wherein R ¹ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, R ² is a glycidyl group or a glycidyl group-containing functional group, 0.30? A? 0.90, 0.01 b 0.50, 0.01? C? And a + b + c = 1.

(2)

^{_{[R 3 SiO 3/2]}} d [SiO 4/2] e

Wherein R ³ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, and 0.30? D? 0.90, 0.10? E? 0.70, and d + e = 1.

(3)

[R ⁴ SiO _3/2 ] _f [R ⁵ SiO _3/2 ] _g

Wherein R ⁴ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, R 5 is a glycidyl group or a glycidyl group-containing functional group, 0.70? F <1, 0 <g≤0.30, f + g = 1 .

In another aspect, the present invention provides a coating composition comprising a base layer and a coating layer formed on one surface of the base layer, wherein the coating layer comprises a first siloxane resin represented by Formula 1 or Formula 2 and a second siloxane resin represented by Formula 3 &Lt; RTI ID = 0.0 &gt; a &lt; / RTI &gt; window film.

In another aspect, the present invention provides a flexible display device including the window film.

The composition for a window film of the present invention can include a hard-type siloxane resin having a specific structure and a soft-type siloxane resin, thereby realizing a window film having a high surface hardness and less curling.

The window film produced by using the composition of the present invention has high surface hardness and can be used as a substitute for a high hardness window glass substrate and has excellent curvature with less curl after curing.

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

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

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

In the present specification, "pencil hardness" means that a window film is cut to a size of 50 mm in width and 50 mm in length to prepare a specimen. The edge of the specimen is stuck on a soda lime glass substrate of 2T thickness using 3M tape, The hardness of the coating layer at the center of the tape was measured using a SHINTO Scientfic HEIDON-14EW instrument. The pencil hardness was measured using a pencil of Mitsubishi's 6B to 9H pencil. The pencil load on the coating layer was 1 kg, the angle of the pencil was 45 °, and the pencil was drawn at a rate of 60 mm / min. 5 times, and when a scratch occurs more than once, it is measured by using a pencil of the pencil hardness level, and when it is 5 times of the evaluation, it is the maximum pencil hardness value when there is no scratch.

Curl "in this specification refers to the curl as shown in Fig. 7, when the window film 1 is cut to a certain size and then placed on the table bottom 2 and left at 25 DEG C and 50% relative humidity, (H) from the surface (2) to the edge portion of the window film (1).

As used herein, unless specifically stated otherwise, at least one hydrogen atom of the functional group may be replaced by a hydroxyl group, an unsubstituted C1 to C10 alkyl group, a C1 to C10 alkoxy group, a C3 to C10 cycloalkyl group, Means a C 1 to C 20 arylalkyl group, a C 7 to C 20 arylalkyl group, a benzophenone group, a C 6 to C 20 aryl group substituted with a C 1 to C 10 alkyl group, or a C 1 to C 10 alkyl group substituted with a C 1 to C 10 alkoxy group do.

As used herein, "cycloaliphatic epoxy group" means an epoxidized C5 to C20 cycloalkyl group. In the present specification, the "alicyclic epoxy group-containing functional group" means a C1 to C12 alkyl group or a C5 to C20 cycloalkyl group having at least one epoxidized C5 to C20 cycloalkyl group.

 As used herein, the term " glycidyl group-containing functional group "means a C1 to C12 alkyl group or a C5 to C20 cycloalkyl group having a glycidoxy group, or a glycidyl group or a glycidoxy group. As used herein, "halogen" means fluorine, chlorine, bromine or iodine.

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

window  Composition for film

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 invention comprises two kinds of siloxane resins having different structures, specifically, a hard type first siloxane resin and a soft type second siloxane resin.

The first siloxane resin may be represented by the following formula (1) or (2).

[Chemical Formula 1]

[R ¹ SiO _3/2 ] _a [SiO _4/2 ] _b [R ² SiO _3/2 ] _c

In the above formula (1), R ¹ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, and specifically may be an epoxycyclohexyl group, an epoxycyclohexylalkyl group, etc. More specifically, an epoxycyclohexyl group, Epoxycyclohexyl) methyl group, (3,4-epoxycyclohexyl) ethyl group, (3,4-epoxycyclohexyl) methyl group, ) Propyl ((3,4-epoxycyclohexyl) propyl) group and the like.

The R ² is a glycidyl group or a glycidyl group-containing functional group. Specifically, it may be a glycidyl group, a glycidoxyalkyl group, or the like. More specifically, it may be a glycidyl group or a glycidoxypropyl group.

A, b, and c are 0.30? A? 0.90, 0.01? B? 0.50, and 0.01? C? 0.40, wherein a + b + c = 1. Specifically, 0.40? A? 0.85, 0.05? B? 0.50, and 0.01? C? 0.35, and more specifically 0.40? A? 0.70, 0.20? B? 0.40, and 0.05? C? When the above range is satisfied, a window film having excellent surface hardness and curling can be produced.

(2)

^{_{[R 3 SiO 3/2]}} d [SiO 4/2] e

In the general formula (2), R ³ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group. Specific examples thereof include an epoxycyclohexyl group, an epoxycyclohexylalkyl group, etc. More specifically, an epoxycyclohexyl group, Epoxycyclohexyl) methyl group, (3,4-epoxycyclohexyl) ethyl group, (3,4-epoxycyclohexyl) methyl group, ) Propyl ((3,4-epoxycyclohexyl) propyl) group and the like.

In the above formula (2), d and e are 0.30? D? 0.90 and 0.10? E? 0.70, wherein d + e = 1. Specifically, 0.40? D? 0.85 and 0.15? E? 0.60, and more specifically, 0.50? D? 0.85 and 0.15? E? When the above range is satisfied, a window film having excellent surface hardness and curling can be produced

It is the first siloxane resin comprises the [SiO _4/2] of a repeating unit having a solid properties after curing, it is possible to improve the hardness of the window film.

Next, the second siloxane resin may be represented by the following formula (3).

(3)

[R ⁴ SiO _3/2 ] _f [R ⁵ SiO _3/2 ] _g

In the above formula (3), R ⁴ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group. Specifically, it may be an epoxycyclohexyl group, an epoxycyclohexylalkyl group, etc. More specifically, an epoxycyclohexyl group, Epoxycyclohexyl) methyl group, (3,4-epoxycyclohexyl) ethyl group, (3,4-epoxycyclohexyl) methyl group, ) Propyl ((3,4-epoxycyclohexyl) propyl) group and the like.

The R ⁵ is a glycidyl group or a glycidyl group-containing functional group. Specifically, it may be a glycidyl group, a glycidoxyalkyl group, or the like. More specifically, it may be a glycidyl group or a glycidoxypropyl group.

In the above formula (3), f and g are 0.70? F <1 and 0 <g? 0.30, respectively, wherein f + g = 1. Specifically, 0.75? F? 0.98 and 0.02? G? 0.25, and more specifically 0.8? F? 0.95 and 0.05? G? 0.2. When the above range is satisfied, a window film having excellent surface hardness and curling can be produced.

The second siloxane resin is a soft type siloxane resin to improve flexibility and reduce curl. Soft type siloxane resins generally have excellent flexibility but low surface hardness. Therefore, when soft type siloxane is mixed and used, the surface hardness generally decreases. However, according to the study of the present inventors, when the soft type siloxane resin represented by the general formula (3) is mixed with the hard type siloxane resin represented by the general formula (1) or (2) as shown in the present invention, the surface hardness is rather improved And the curling phenomenon after curing was remarkably improved.

As described above, the composition of the present invention can simultaneously realize a high surface hardness and a low curling property when a window film is produced by using a first siloxane resin having a specific structure and a second siloxane resin together.

Meanwhile, the composition of the present invention may contain the first siloxane resin and the second siloxane resin in a weight ratio of 2: 8 to 8: 2, preferably 4: 6 to 6: 4 . When the blending ratio is satisfied, both the surface hardness and the curl characteristic are excellent.

The composition of the present invention may further include a crosslinking agent and a curing agent in addition to the first and second siloxane resins.

The crosslinking agent may contain a crosslinking functional group such as an epoxy group or an oxetane group to cure the first siloxane resin and the second siloxane resin to increase the hardness of the window film. Further, the crosslinking agent may further include at least one of a chain aliphatic hydrocarbon group, a cyclic aliphatic hydrocarbon group, and a hydrogenated aromatic hydrocarbon group to further increase the flexibility of the coating layer. Specifically, the crosslinking agent may include at least one of a chain aliphatic epoxy monomer, a cyclic aliphatic epoxy monomer, a hydrogenated aromatic hydrocarbon epoxy monomer, and an oxetane monomer.

The chain type aliphatic epoxy monomer may be 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,7-octadienedepoxide, trimethylol propane Triglycidyl ether, polyethylene glycol diglycidyl ether, glycerin triglycidyl ether, polypropylene glycol diglycidyl ether; Polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin; Diglycidyl esters of aliphatic long chain dibasic acids; Monoglycidyl ethers of aliphatic higher alcohols; Glycidyl ethers of higher fatty acids; Epoxidized soybean oil; Butyl stearate; Octyl stearate; Epoxidized linseed oil; Epoxylated polybutadiene, and the like.

The cyclic aliphatic epoxy monomer is a compound having at least one epoxy group in the alicyclic group, and may specifically include an alicyclic epoxy carboxylate, an alicyclic epoxy (meth) acrylate, and the like. More specifically, (3,4-epoxycyclohexyl) methyl-3 ', 4'-epoxycyclohexyl methyl 3', 4'-epoxycyclohexanecarboxylate, diglycidyl 1, Cyclohexanedicarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane (2- (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxycyclohexylmethyl) adipate, 3,4-epoxycyclohexyl-5,5-spiro- , Bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexylmethyl-3 ', 4 '-Epoxy-6'-methylcyclohexylmethyl-3', 4'-epoxy-6'-methylcyclohexanecarboxylate), ε-caprolactone-modified 3,4-epoxycyclohexyl Methyl-3 ', 4'-epoxycyclohexylmethyl-3'-caprolactone modified 3,4-epoxycyclohexylmethyl- , 4'-epoxy-cyclohexanecarboxylate, trimethylcaprolactone modified 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexylmethyl-3', 4'-epoxy -cyclohexanecarboxylate,? -methyl-? -valerolactone modified 3,4-epoxycyclohexylmethyl-3'4,? -methyl-? -valerolactone modified 3,4-epoxycyclohexylmethyl- 3 ', 4'-epoxycyclohexanecarboxylate), 1,4-cyclohexanedimethanol bis (3,4-epoxycyclohexanecarboxylate), ethylene glycol di 3,4-epoxycyclohexylmethyl) ether, ethylenebis (3,4-epoxycyclohexanecarboxylate), ethylenebis (3,4-epoxycyclohexanecarboxylate), ethylenebis , 4-epoxycyclohexylmethyl (meth) acrylate, 4-vinylcyclohexene diacrylate, 4-vinylcyclohexene dioxide, vinylcyclohexen monoxide, 1,4-cyclohexanedimethanol diglycidyl ether, 2,2 '- ((1 (cyclohexanedimethanol diglycidyl ether) Bis (methyleneethylidene) bis (cyclohexane-4,1-diyloxymethylene) bisoxirane) and the like can be used. .

The hydrogenated aromatic hydrocarbon epoxy monomer means a compound obtained by selectively hydrogenating an aromatic epoxy monomer under a pressure in the presence of a catalyst. Specific examples of the aromatic epoxy monomer include bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; Novolak type epoxy resins such as phenol novolak epoxy resin, cresol novolak epoxy resin, and hydroxybenzaldehyde phenol novolak epoxy resin; But are not limited to, polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxylated polyvinylphenol.

The oxetane monomer may be selected from the group consisting of 3-methyloxetane, 2-methyloxetane, 2-ethylhexyloxetane, 3-oxethanol, 2-methylene oxetane, Methyl-3-oxetanemethanamine, N- (1,2-dimethylbutyl) -3-methyl-3- (3-ethyloxetan-3-yl) methoxy] butan-1-ol, 3-ethyloxetane- May include at least one of 3-hydroxymethyloxetane, xylene bisoxetane and 3- [ethyl-3 [[(3-ethyloxetan-3-yl)] methoxy] methyl] oxetane, But is not limited thereto.

The crosslinking agent is added in an amount of 0.1 to 50 parts by weight, specifically 3 to 30 parts by weight, more specifically 5 to 30 parts by weight per 100 parts by weight of the total siloxane resin containing the first siloxane resin and the second siloxane resin . Within this range, the flexibility and hardness of the coating layer of the window film can be increased.

On the other hand, the initiator is used for curing the siloxane resin and the crosslinking agent, and one or more of a photocationic initiator and a photoradical initiator can be used. The Gwangyang ionic initiator may be any of those conventionally known to those skilled in the art. Specifically, an onium salt including a cation and an anion can be used. Specific examples of the cation include diphenyliodonium, 4-methoxydiphenyliodonium, bis (4-methylphenyl) iodonium, bis (4-tert- butylphenyl) iodonium, bis (dodecylphenyl) Diaryl iodonium such as methylphenyl) [4- (2-methylpropyl) phenyl] iodonium, triarylsulfonium such as triphenylsulfonium and diphenyl-4-thiophenoxyphenylsulfonium, bis [4- (Diphenylsulfonio) phenyl] sulfide, and the like. Specific examples of the anion include hexafluorophosphate, tetrafluoroborate, hexafluoroantimonate, hexafluoroarsenate, and hexachloroantimonate. The initiator may be included in an amount of 0.1 part by weight to 20 parts by weight, specifically 0.5 part by weight to 10 parts by weight, based on 100 parts by weight of the total siloxane resin including the first siloxane resin and the second siloxane resin. The siloxane resin can be sufficiently cured within the above range and the transparency of the window film can be prevented from being lowered with the remaining amount of the initiator.

Meanwhile, the composition for a window film according to the present invention may further comprise nanoparticles, if necessary.

The nanoparticles are intended to further improve the hardness of the window film and may include, but are not limited to, one or more of, for example, silica, aluminum oxide, zirconium oxide, titanium oxide. The nanoparticles may be surface treated with at least a portion of the surface of the silicone compound for mixing with the siloxane resin. On the other hand, the nanoparticles may have a shape of a spherical shape, a plate shape, an amorphous shape and the like and may have an average particle size of 1 nm to 200 nm, specifically 10 nm to 50 nm, but the present invention is not limited thereto. The nanoparticles may be included in an amount of 0.1 part 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 siloxane resin including the first siloxane resin and the second siloxane resin. The hardness of the window film can be increased without affecting the surface roughness and transparency of the window film in the above average particle size and content range.

In addition, the composition for a window film according to the present invention may further comprise an additive. The additive may provide additional functionality to the window film. The additive may include an additive typically added to the window film. Specifically, the additive may include at least one of a UV absorber, a reaction inhibitor, an adhesion improver, a thixotropic agent, a conductivity imparting agent, a colorant adjusting agent, a stabilizer, an antistatic agent, an antioxidant, Do not. The reaction inhibitor may include ethynylcyclohexane. The adhesion improver may include a silane compound having an epoxy or alkoxysilyl group. The thixotropic agent may include pyrous silica and the like. The conductivity-imparting agent may include a metal powder such as silver, copper aluminum and the like. The colorant-adjusting agent may include a pigment, a dye, and the like. The UV absorber can increase the light reliability of the window film. The UV absorbers can be 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 siloxane resin including the first siloxane resin and the second siloxane resin. In this range, the hardness and flexibility of the window film can be improved and the additive effect can be realized.

The composition for a window film according to the present invention may further comprise a solvent for facilitating coatability, coatability or workability. The solvent may include, but is not limited to, one or more of methyl ethyl ketone, methyl isobutyl ketone, and propylene glycol monomethyl ether acetate.

window  film

Next, a window film according to the present invention will be described with reference to the drawings.

1 is a cross-sectional view of a window film according to an embodiment of the present invention.

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

The base layer 110 supports the coating layer 120 and increases the mechanical strength of the window film 100. The base layer 110 may be formed of an optically transparent and flexible resin. For example, the resin may be a polyester resin including polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate and the like, polycarbonate resin, polyimide resin, polystyrene resin, polymethylmethacrylate (Poly (meth) acrylate). &Lt; / RTI &gt;

The thickness of the base layer 110 may be 10 탆 to 200 탆, specifically 30 탆 to 150 탆, more specifically 30 탆 to 100 탆. It can be used in the window film in the above range.

The base layer 110 may be adhered to a display portion, a touch screen panel, or a polarizing plate by an adhesive layer or the like.

Next, the coating layer 120 is formed on the base layer 110 to protect the base layer 110, the display portion, the touch screen panel or the polarizing plate. The composition for a window film according to the present invention is cured . Since the composition for a window film is the same as that described above, a detailed description thereof will be omitted.

The thickness of the coating layer 120 may be 30 탆 to 100 탆, specifically 30 탆 to 80 탆, more specifically 30 탆 to 60 탆.

Although not shown in FIG. 1, the other surface of the coating layer 120 may further include a functional surface layer such as an antireflection layer, an antiglare layer, a hard coating layer, and an antistatic layer.

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

2, a window film 200 according to another embodiment of the present invention includes a substrate layer 110, a coating layer 120 formed on one surface of the substrate layer 110, (130), and the coating layer (120) may be formed of a composition for a window film according to embodiments of the present invention.

As shown in FIG. 2, when the adhesive layer 130 is formed on the other surface of the base layer 110, adhesion between the window film and the touch screen panel, the polarizing plate, or the display portion can be further facilitated. Other components than the adhesive layer are substantially the same as the window film according to the embodiment of the present invention disclosed in Fig. Therefore, only the adhesive layer 130 will be described below.

The adhesive layer 130 is for adhering the window film 200 to a polarizing plate, a touch screen panel, a display unit, or the like. The adhesive layer 130 may be formed of a composition for a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive resin such as a (meth) acrylic resin, a urethane resin, a silicone resin and / or an epoxy resin, a curing agent, a photoinitiator and a silane coupling agent have.

The (meth) acrylic resin may include an ordinary (meth) acrylic copolymer as the (meth) acrylic copolymer having an alkyl group, a hydroxyl group, an aromatic group, a carboxylic acid group, an alicyclic group, a heterocyclic group or the like. Specifically, the (meth) acrylic copolymer is 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 C6 to C20 (Meth) acrylic monomer having an aromatic group, (meth) acrylic monomer having a carboxylic acid group, (meth) acrylic monomer having a C3 to C20 alicyclic group, and (meth) acrylic monomer having a C3 to C10 heteroalicyclic group, May be formed by polymerizing the monomer mixture.

Examples of the curing agent include bifunctional (meth) acrylates such as hexanediol diacrylate as polyfunctional (meth) acrylates; Trifunctional (meth) acrylates of trimethylolpropane tri (meth) acrylate; Tetrafunctional (meth) acrylates such as pentaerythritol tetra (meth) acrylate; Pentafunctional (meth) acrylates such as dipentaerythritol penta (meth) acrylate; And hexafunctional (meth) acrylates such as dipentaerythritol hexa (meth) acrylate, but are not limited thereto.

The photoinitiator may include the above-described photoinitiator as a typical photoinitiator. The silane coupling agent may include a silane coupling agent having an epoxy group such as 3-glycidoxypropyltrimethoxysilane.

Specifically, the composition for a pressure-sensitive adhesive layer may comprise 100 parts by weight of a (meth) acrylic resin, 0.1 to 30 parts by weight of a curing agent, 0.1 to 10 parts by weight of a photoinitiator, and 0.1 to 20 parts by weight of a silane coupling agent . In this range, the window film can be well adhered on the display portion, the touch screen panel or the polarizing plate.

The adhesive layer 130 may have a thickness of 10 mu m to 100 mu m. In this range, the optical element such as the window film and the polarizing plate can be adhered with sufficient adhesive force.

The window film according to the present invention may be prepared by coating a composition for a window film according to the present invention on a substrate layer 110 and curing the composition.

The method for coating the composition for a window film on the base layer 110 is not particularly limited and may be any one of coating methods well known in the art, for example, bar coating, spin coating, dip coating, roll coating, Coating or the like may be used. On the other hand, the curing of the composition for a window film can be carried out by one or more methods of photo-curing and thermosetting. The light curing may be performed, for example, by irradiating the composition for a coated window film with light having a wavelength of 400 nm or less at a light quantity of 10 mJ / cm ² to 1000 mJ / cm ² , Can be performed, for example, by a method of treating the composition for a coated window film at 40 ° C to 200 ° C for 1 hour to 30 hours, but the present invention is not limited thereto.

On the other hand, when the composition for a window film is coated on the base layer 110 and then cured, the composition for a window film is dried and cured to prevent the surface roughness of the coating layer from becoming high due to long-time light curing and thermal curing . The drying can be performed at 40 캜 to 200 캜 for 1 minute to 30 hours, but is not limited thereto.

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

In addition, the window film 100 has a pencil hardness of 7H or more, specifically 7H to 9H, and excellent surface hardness.

The window film 100 has a curl of -10 mm to +10 mm, specifically, -8 mm to +8 mm, more specifically, -6 mm to +6 mm, which is excellent in the processability in mounting the display film on a display device . On the other hand, + and - indicate the direction in which the curling occurs, and + means that convex curling occurs when the base layer is oriented toward the bottom, and - indicates that the coating layer faces the bottom This means that convex curls occur downward.

flexible  Display device

Next, a flexible display device according to the present invention will be described with reference to the drawings.

FIG. 3 is a cross-sectional view of a flexible display device according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view of an exemplary embodiment of the display unit of FIG.

3, a flexible display device 300 according to an embodiment of the present invention includes a display portion 350a, an adhesive layer 360, a polarizing plate 370, a touch screen panel 380, a window film 390, And the window film 390 may be a window film according to embodiments of the present invention.

The display portion 350a is for driving the flexible display device 300 and may include a substrate and an optical element formed on the substrate. In this case, the optical element may be an OLED, an LED, an LCD element, or the like, but is not limited thereto.

Fig. 4 shows an embodiment of the display unit of Fig. 4, the display unit 350a includes a lower substrate 310, a thin film transistor 316, an organic light emitting diode 315, a planarization layer 314, a protection layer 318, and an insulation layer 317 .

The lower substrate 310 supports the display portion 350a and the lower substrate 310 may have a thin film transistor 316 and an organic light emitting diode 315 formed thereon. A flexible printed circuit board (FPCB) for driving the touch screen panel 380 may be formed on the lower substrate 310. The flexible printed circuit board may further include a timing controller for driving the organic light emitting diode array, a power supply unit, and the like.

The lower substrate 310 may include a substrate formed of a flexible resin. The lower substrate 310 may include a flexible substrate such as a silicone substrate, a polyimide substrate, a polycarbonate substrate, or a polyacrylate substrate, but is not limited thereto .

A plurality of pixel regions are defined by a plurality of driving wirings (not shown) and sensor wirings (not shown) crossing the display region of the lower substrate 310, and thin film transistors 316 and thin film transistors 316 And an organic light emitting diode (OLED) 315 connected to the organic light emitting diode array. In a non-display area of the lower substrate, a gate driver for applying an electrical signal to the driving wiring may be formed in the form of a gate in panel. The gate-in panel circuit portion may be formed on one side or both sides of the display region.

The thin film transistor 316 may be formed on the lower substrate 310 by controlling a current flowing through the semiconductor by applying an electric field perpendicular thereto. The thin film transistor 316 may include a gate electrode 310a, a gate insulating film 311, a semiconductor layer 312, a source electrode 313a, and a drain electrode 313b. The thin film transistor 316 includes an oxide thin film transistor using an oxide such as indium gallium zinc oxide (IGZO), ZnO, or TiO.sub.2 as the semiconductor layer 312, an organic thin film transistor using an organic material as a semiconductor layer, an amorphous silicon An amorphous silicon thin film transistor to be used, or a polycrystalline silicon thin film transistor using polycrystalline silicon as a semiconductor layer.

The planarization layer 314 may cover the thin film transistor 316 and the circuit portion 310b so that the top surface of the thin film transistor 316 and the circuit portion 310b may be planarized to form the organic light emitting diode 315. [ The planarization layer 314 may be formed of a spin-on-glass (SOG) film, a polyimide-based polymer, a polyacrylic polymer, or the like, but is not limited thereto.

The organic light emitting diode 315 emits light by self-emission, and may include a first electrode 315a, an organic light emitting layer 315b, and a second electrode 315c stacked in that order. The adjacent organic light emitting diodes may be separated through an insulating film 317. [ The organic light emitting diode 315 may include a bottom emission structure in which light generated in the organic emission layer 315b is emitted through the lower substrate or a top emission structure in which light generated in the organic emission layer 315b is emitted upward.

The passivation layer 318 may cover the organic light emitting diode 315 to protect the organic light emitting diode 315. The passivation layer 318 may be formed of an inorganic material such as SiOx, SiNx, SiC, SiON, SiONC, and aC (amorphous carbon) Methacrylate, epoxy-based polymer, imide-based polymer, and the like. Specifically, the protective layer 318 may include an encapsulation layer in which a layer formed of an inorganic material and a layer formed of an organic material are sequentially stacked one or more times.

3, the adhesive layer 360 is formed of a pressure-sensitive adhesive composition comprising a (meth) acrylate resin, a curing agent, an initiator, and a silane coupling agent to adhere the display portion 350a and the polarizing plate 370 .

The polarizing plate 370 can implement polarizing of the inner light or prevent reflection of the external light to realize the display or to increase the contrast ratio of the display. The polarizing plate may be composed of a polarizer alone. Or the polarizing plate may include a polarizing film and a protective film formed on one or both sides of the polarizing film. Or the polarizing plate may include a polarizer and a protective coating layer formed on one or both sides of the polarizer. The polarizer, the protective film, and the protective coating layer may be conventional ones known to those skilled in the art.

The touch screen panel 380 senses 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 350a can be driven by this signal. The touch screen panel 380 is formed by patterning a flexible conductive conductive material. The touch screen panel 380 may include a first sensor electrode and a second sensor electrode formed between the first sensor electrode and the first sensor electrode. have. The conductor for the touch screen panel 380 may include, but is not limited to, metal nanowires, conductive polymers, carbon nanotubes, and the like.

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

3, an adhesive layer is further formed between the polarizing plate 370 and the touch screen panel 380 and / or between the touch screen panel 380 and the window film 390 to form a polarizing plate, a touch screen panel, Can be strengthened. The pressure-sensitive adhesive layer may be formed of a pressure-sensitive adhesive composition comprising a (meth) acrylate resin, a curing agent, an initiator, and a silane coupling agent. Further, although not shown in FIG. 3, a polarizing plate is further provided under the display unit 350a, so that polarized light can be realized.

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

5, a flexible display device 400 according to another embodiment of the present invention includes a touch screen panel 380 on a lower side of a polarizer 370 without directly forming a touch screen panel 380 on a window film 390, 380) are formed on the flexible display device according to an embodiment of the present invention. At this time, the touch screen panel 380 may be formed together with the display portion 350a. In this case, since the touch screen panel 380 is formed on the display unit 350a together with the display unit 350a, the thickness of the touch screen panel 380 can be thinner and brighter than that of the flexible display device according to an embodiment of the present invention. In this case, the touch screen panel 380 can be formed by deposition or the like, but is not limited thereto. Although not shown in FIG. 5, between the display portion 350a and the touch screen panel 380 and / or between the touch screen panel 380 and the polarizer 370 and / or between the polarizer 370 and the window film 390 By further forming the adhesive layer, the mechanical strength of the display device can be increased. Although not shown in FIG. 5, a polarizing plate is further provided under the display unit 350a to thereby guide polarized light to improve the display image.

Hereinafter, a flexible display device according to another embodiment of the present invention will be described with reference to FIG. 6 is a cross-sectional view of a flexible display device according to another embodiment of the present invention. 6, a flexible display device 500 according to another exemplary embodiment of the present invention includes a display portion 350b and includes a polarizer 370 and a touch screen panel 380, Is substantially the same as the flexible display device according to the embodiment of the present invention. The display portion 350b may include an LCD, an OLED, or an optical element including an LED element formed on the substrate, and the display portion 350b may have a touch screen panel formed therein.

Although the flexible display device has been described above, the flexible display window film of the present embodiments can be used in a non-flexible display device.

Hereinafter, the present invention will be described more specifically by way of specific examples. However, the following examples are intended to illustrate the present invention and should not be construed to limit the scope of the present invention.

Manufacturing example  One - Siloxane  Resin A:

50 mol% of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (KBM-303, Shinetsu), 20 mol% of 3-glycidoxypropyltrimethoxysilane (KBM-403, Shinetsu) (30 mol%) was added to a 500 ml 2-neck flask. To the monomer mixture, 0.5 mol% of KOH and 70 mol% of water based on the total alkoxy groups of the monomer mixture were added, by adding toluene and then stirred for 2 hours, and washed with water to remove the solvent remaining in a vacuum distillation unit, the _{(EcSiO 3/2) 0.50 (} SiO 4/2) 0 .30 (GpSiO 3/2) 0.20 Hard type siloxane resin A (weight average molecular weight: 8000, by gel permeation chromatography) was prepared.

Manufacturing example  2 - Siloxane  Resin B:

A total of 100 g of a monomer mixture comprising 70 mol% of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (KBM-303, Shinetsu) and 30 mol% of tetraethoxysilane , And KOH in an amount of 0.5 mol% based on the monomer mixture and water in an amount of 70 mol% based on the total alkoxy groups of the monomer mixture were added and stirred at 65 DEG C for 2 hours. Then, toluene was added thereto, the solvent was removed, to prepare a _{(EcSiO 3/2) 0.70 (} SiO 4/2) _{0.30 0} hard type of siloxane resin B (Na2 weight average molecular weight of 6000 by gel permeation chromatography).

Manufacturing example  3 - Siloxane  Resin C:

80 mol% of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (KBM-303, Shinrytsu) and 20 mol% of (3-glycidoxypropyl) trimethoxysilane (KBM- Was placed in a 1 L 3-neck flask. It 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) 0.80} (GpSiO 3 _{/ 2} ) _{0 . 20} soft type siloxane resin C (weight average molecular weight by gel permeation chromatography (GPC): 5,000) was prepared.

Example  One

To 100 parts by weight of a siloxane resin prepared by Preparation Example 1 and a siloxane resin C prepared by Preparation Example 3 in a weight ratio of 2: 8, 100 parts by weight of 3,4-epoxycyclohexylmethyl 3 , 10 parts by weight of 4-epoxycyclohexanecarboxylate (Aldrich), 3 parts by weight of I-250 (BASF) as a photoinitiator, and methyl ethyl ketone (MEK, Daejeon Chemical) as a solvent were added to prepare a coating liquid having a solid content of 70% . The coating liquid was coated on a polyimide film (Samsung SDI, thickness: 50 탆), dried at 80 캜 for 5 minutes, irradiated with UV at 1,000 mJ / cm ² and further heated at 100 캜 for 24 hours, A window film having a thickness of 50 탆 was produced.

Example  2

Except that a siloxane resin prepared by mixing the siloxane resin A produced in Production Example 1 with the siloxane resin C produced in Production Example 3 in a weight ratio of 5: 5 was used as the siloxane resin A window film was prepared.

Example  3

Except that a siloxane resin obtained by mixing Siloxane Resin A produced in Production Example 1 with Siloxane Resin C prepared in Production Example 3 in a weight ratio of 8: 2 was used as the siloxane resin A window film was prepared.

Example  4

Except that a siloxane resin obtained by mixing Siloxane Resin B prepared in Preparation Example 2 with Siloxane Resin C prepared in Preparation Example 3 in a weight ratio of 5: 5 was used as the siloxane resin A window film was prepared.

Comparative Example  One

A window film was prepared in the same manner as in Example 1, except that the siloxane resin C prepared in Preparation Example 3 was used alone as the siloxane resin.

Comparative Example  2

A window film was prepared in the same manner as in Example 1, except that the siloxane resin A produced in Production Example 1 was used alone as the siloxane resin.

Comparative Example  3

A window film was prepared in the same manner as in Example 1, except that the siloxane resin B produced in Production Example 2 was used alone as the siloxane resin.

The composition of the composition for a window film used in Examples 1 to 4 and Comparative Examples 1 to 3 is shown in Table 1 below.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Siloxane resin A 20 50 80 - - 100 - B - - - 50 - - 100 C 80 50 20 50 100 - - Cross-linking agent 10 10 10 10 10 10 10 Initiator 3 3 3 3 3 3 3

[Unit: parts by weight]

The pencil hardness and curling characteristics of the window films prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were measured according to the following physical property measuring methods. The measurement results are shown in Table 2 below.

How to measure property

1. Pencil hardness: The window film prepared in the above Examples and Comparative Examples was cut to a size of 50 mm in width and 50 mm in length to prepare a specimen. The edge of the specimen was stuck on a soda lime glass substrate of 2T thickness using 3M tape give. Then, the hardness of the coating layer at the center of the specimen without the 3M tape was measured using a HEIDON-14EW instrument of SHINTO Scientfic. In the pencil hardness measurement, a pencil was used from Mitsubishi's 6B to 9H pencil. The load of the pencil on the coating layer was 1 kg, the angle of drawing the pencil was 45 °, and the drawing speed of the pencil was 60 mm / min. 5 times, and when a scratch occurs more than once, it is measured by using a pencil of the pencil hardness level, and when it is 5 times of the evaluation, it is the maximum pencil hardness value when there is no scratch.

2. Curl (Unit: mm): The window film prepared in the above Examples and Comparative Examples was cut into a size of 100 mm x 100 mm, and then placed on a table. Then, And the height (H) was measured.

Pencil hardness Curling (mm) Example 1 7H +2.5 Example 2 8H +4.75 Example 3 8H +5.25 Example 4 8H +10 Comparative Example 1 4H -3 Comparative Example 2 6H +15 Comparative Example 3 6H +23

As shown in Table 2, the window films of Examples 1 to 4, in which the hard-type siloxane resin and the soft-type siloxane resin were mixed, showed excellent pencil hardness of 7H or more and curling of 10 mm or less have. In particular, the pencil hardness of the window films of Examples 1 to 4 is higher than that of the window films of Comparative Examples 2 and 3 in which the hard type siloxane resin alone is used.

In contrast, in Comparative Example 1 using a soft type siloxane resin alone, pencil hardness was low and it was not suitable for a window film. In the case of Comparative Examples 2 and 3 in which the hard-type siloxane resin alone was used, it was confirmed that the pencil hardness and curling properties were lowered as compared with the window films of Examples 1 to 4.

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

100, 200, 390: window film
110: substrate layer
120: Coating layer
130: adhesive layer
300, 400, 500: Flexible display device
310: Lower substrate
314: Planarizing layer
315: organic light emitting diode
316: Thin film transistor
318: Shield
317: Insulating film
350a:
360: Adhesive layer
370: Polarizer
380: Touch screen panel

Claims (12)

A first siloxane resin represented by the following formula (1) or (2); And
A composition for a window film comprising a second siloxane resin represented by the following formula (3).
[Chemical Formula 1]
[R ¹ SiO _3/2 ] _a [SiO _4/2 ] _b [R ² SiO _3/2 ] _c
Wherein R ¹ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, R ² is a glycidyl group or a glycidyl group-containing functional group, 0.30? A? 0.90, 0.01 b 0.50, 0.01? C? And a + b + c = 1.
(2)
_{^{[R 3 SiO 3/2]}} d [SiO 4/2] e
Wherein R ³ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, and 0.30? D? 0.90, 0.10? E? 0.70, and d + e = 1.
(3)
[R ⁴ SiO _3/2 ] _f [R ⁵ SiO _3/2 ] _g
Wherein R ⁴ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, R 5 is a glycidyl group or a glycidyl group-containing functional group, 0.70? F <1, 0 <g≤0.30, f + g = 1 . The method according to claim 1,
Wherein the first siloxane resin and the second siloxane resin are contained in a weight ratio of 2: 8 to 8: 2. The method according to claim 1,
Wherein the composition for a window film further comprises a crosslinking agent and an initiator. A base layer;
And a coating layer formed on one surface of the substrate layer,
Wherein the coating layer is formed from a composition comprising a first siloxane resin represented by the following formula (1) or (2) and a second siloxane resin represented by the following formula (3).
[Chemical Formula 1]
[R ¹ SiO _3/2 ] _a [SiO _4/2 ] _b [R ² SiO _3/2 ] _c
Wherein R ¹ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, R ² is a glycidyl group or a glycidyl group-containing functional group, 0.30? A? 0.90, 0.01 b 0.50, 0.01? C? And a + b + c = 1.
(2)
_{^{[R 3 SiO 3/2]}} d [SiO 4/2] e
Wherein R ³ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, and 0.30? D? 0.90, 0.10? E? 0.70, and d + e = 1.
(3)
[R ⁴ SiO _3/2 ] _f [R ⁵ SiO _3/2 ] _g
Wherein R ⁴ is a functional group containing an alicyclic epoxy group or an alicyclic epoxy group, R 5 is a glycidyl group or a glycidyl group-containing functional group, 0.70? F <1, 0 <g≤0.30, f + g = 1 . 5. The method of claim 4,
Wherein the coating layer has a thickness after curing of 30 to 100 占 퐉. 5. The method of claim 4,
Wherein the window film has a surface hardness of 7H or more. 5. The method of claim 4,
Wherein the window film has a curl of -10 mm to +10 mm. A flexible display device comprising the window film of claim 4. 9. The method of claim 8,
The flexible display device includes a display unit, a pressure sensitive adhesive layer formed on the display unit, a polarizing plate formed on the pressure sensitive adhesive layer, a touch screen panel formed on the polarizing plate, and a window film formed on the touch screen panel. Display device. 9. The method of claim 8,
Wherein the flexible display device comprises a display unit, a touch screen panel formed on the display unit, a polarizing plate formed on the touch screen panel, and the window film formed on the polarizing plate. 9. The method of claim 8,
Wherein the flexible display device includes a display portion, an adhesive layer formed on the display portion, and the window film formed on the adhesive layer. 12. The method of claim 11,
Wherein the display unit further comprises a polarizer on an upper portion or a lower portion thereof.

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