KR101938039B1 - Composition for window film and flexible window film prepared using the same - Google Patents

Abstract

Wherein the crosslinking agent comprises a mixture of a first crosslinking agent having an epoxidized alicyclic group and a second crosslinking agent having an epoxidized alicyclic group and a vinyl group, Wherein the first crosslinking agent is contained in an amount of 5 to 30 parts by weight and the second crosslinking agent is contained in an amount of 5 to 20 parts by weight.

Description

FIELD OF THE INVENTION The present invention relates to a composition for a window film,

The present invention relates to a composition for a window film and a flexible window film formed therefrom.

Flexible display devices have been developed that can be folded and unfolded while replacing a glass substrate or a hardened substrate with a film in a display device. The flexible display device is thin, light, strong against impact, and can be folded and unfolded.

The window film is positioned at the outermost portion of the display device, so that flexibility and hardness are good. The window film can be prepared by applying a coating solution on a substrate layer and then curing. If the curing rate of the coating solution is low, the hardness may be low even if it is cured for the same time, but if the curing time is increased, the fairness may be lowered. If the curing rate is not uniform depending on the thickness from the base layer, the surface hardness of the window film is high, but sufficient hardness can not be secured near the base layer and reliability may be deteriorated.

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

A problem to be solved by the present invention is to provide a composition for a window film which is excellent in pencil hardness and flexibility and can realize a curled window film.

Another problem to be solved by the present invention is to provide a composition for a window film which has a high curing rate, a uniform and high curing rate on the basis of thickness, and can realize a window film.

Another object of the present invention is to provide a flexible window film which is excellent in pencil hardness and flexibility, low in curling and uniform in hardness on the basis of thickness.

The composition for a window film of the present invention comprises a silicone resin, a crosslinking agent, and an initiator, wherein the crosslinking agent comprises a mixture of a first crosslinking agent having an epoxidized alicyclic group and a second crosslinking agent having an epoxidized alicyclic group and a vinyl group , 5 to 30 parts by weight of the first crosslinking agent may be included in 100 parts by weight of the silicone resin, and 5 to 20 parts by weight of the second crosslinking agent may be included.

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

The present invention provides a composition for a window film which is excellent in pencil hardness and flexibility and can realize a curled window film.

The present invention provides a composition for a window film which has a high curing rate, a uniform and high curing rate based on thickness, and can realize a window film.

The present invention provides a flexible window film having excellent pencil hardness and flexibility, low curling, and uniform curing degree on the basis of thickness.

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 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 the curl measurement.

The present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. 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, wherein "upper" may be changed to "lower", "lower" What is referred to as " on " may include not only superposition, but also intervening other structures in the middle. On the other hand, what is referred to as " directly on " or " directly above "

As used herein, the term " epoxy group " means a glycidyl group, a glycidoxin group or an epoxidized C4 to C20 cycloalkyl group, and an " epoxy group-containing functional group " means a C5 to C20 cycloalkyl group having a C1 to C20 alkyl group or an epoxy group having an epoxy group to be.

As used herein, "halogen" means fluorine, chlorine, bromine, or iodine, "(meth) acryl" means acryl and / or methacrylic, and "substituted" A hydrogen atom is replaced by 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 C20 aryl group, a C7 to C20 arylalkyl group, A substituted C6 to C20 aryl group, or a C1 to C10 alkyl group substituted with a C1 to C10 alkoxy group.

In the present specification, "Ec" is 2- (3,4-epoxycyclohexyl) ethyl group and "Gp" is 3-glycidoxypropyl group. As used herein, "(meth) acrylate" means acrylate and / or methacrylate.

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 an embodiment of the present invention includes a silicone resin, a crosslinking agent, and an initiator, wherein the crosslinking agent is a mixture of a first crosslinking agent having an epoxidized alicyclic group and a second crosslinking agent having an epoxidized alicyclic group and a vinyl group ≪ / RTI > The first crosslinking agent may be included in an amount of 5 to 30 parts by weight based on 100 parts by weight of the silicone resin, and 5 to 20 parts by weight may be included in the second crosslinking agent. Within the above range, a window film having a high curing speed, excellent pencil hardness and flexibility, low curling, and uniform curing rate based on thickness can be produced. Particularly, the amount of the first crosslinking agent may be 5 parts by weight to 20 parts by weight, the amount of 5 parts by weight to 15 parts by weight, and the amount of the second crosslinking agent may be 5 parts by weight to 15 parts by weight, based on 100 parts by weight of the silicone resin. Within this range, the first crosslinking agent and the second crosslinking agent may better represent the function as a crosslinking agent in the composition and may not use an excess amount of an initiator. A composition for a window film comprising a silicone resin, in particular a silicone resin having an epoxidized alicyclic group and a first crosslinking agent having an epoxidized alicyclic group, can ensure pencil hardness and flexibility but curl in the opposite direction Drying) is difficult to apply to the process, and the curing speed is slow, thereby decreasing reliability. However, when only the first crosslinking agent is added, the reverse curling becomes higher and the pencil hardness decreases. The invention further comprises a second crosslinking agent having an epoxidized alicyclic group and a vinyl group in a specific amount and comprises only a first crosslinking agent having an epoxidized alicyclic group by controlling the content of the first crosslinking agent having an epoxidized alicyclic group In the case of the pencil hardness was higher, but the curl could be significantly lowered. In addition, a window film having a uniform curing ratio based on thickness can be realized.

Hereinafter, the silicone resin will be described.

The silicone resin is a binder for forming a window film, which can improve the hardness and flexibility of a window film and can be represented by the following chemical formula 1:

≪ Formula 1 >

(R ¹ SiO _3/2 ) _x (R ² R ³ SiO _2/2 ) _y (R ⁴ R ⁵ R ⁶ SiO _1/2 ) _z (SiO _4/2 ) _w

(Wherein R ¹ represents an epoxy group or an epoxy group-containing functional group,

R ² and R ³ are each independently hydrogen, a crosslinkable functional group, an unsubstituted or substituted C 1 to C 20 alkyl group, or an unsubstituted or substituted C 5 to C 20 cycloalkyl group,

R ⁴ , R ⁵ and R ⁶ are each independently selected from the group consisting of hydrogen, a crosslinkable functional group, an unsubstituted or substituted C 1 to C 20 alkyl group, an unsubstituted or substituted C 5 to C 20 cycloalkyl group, An aryl group of C30,

0 &lt; y < 1, 0? Y <1, 0? Z <1, 0? W <1, x + y + z + w = 1).

Specifically, R ¹ may be a C1 to C20 alkyl group having an epoxidized C4 to C20 cycloalkyl group, or a C1 to C20 alkyl group having a glycidoxy group, more specifically an epoxycyclohexylethyl group or a glycidoxypropyl group . Specifically, R ² and R ³ may be independently a C1 to C20 alkyl group having a C4 to C20 cycloalkyl group which is epoxidized, a C1 to C10 alkyl group, more specifically an epoxycyclohexylethyl group or a methyl group. In the formula (1), the crosslinkable functional group means an epoxy group, an epoxy group-containing functional group, an oxetanyl group or an oxetanyl group-containing functional group.

In one embodiment, the silicone resin may be represented by the following formula 1-1 or 1-2:

&Lt; Formula 1-1 >

(R ^1a SiO _3/2 ) _{x 1} (R ^1b SiO _3/2 ) _{x 2}

(Wherein R ^1a and R ^1b are epoxy or epoxy group-containing functional groups, 0 <x 1 <1, 0 <x 2 <1, x 1 + x 2 = 1, and R ^1a and R ^1b are different from each other)

(1-2)

(R ^1a SiO _3/2 ) _{x 1} (R ^1b SiO _3/2 ) _{x 2} (SiO _4/2 ) _w

(In the above formula 1-2, R ^1a, R ^1b is an epoxy group or the epoxy group-containing functional group, 0 <x1 <1, 0 <x2 <1, 0 <w <1, x1 + x2 + w = 1, R 1a and R ^1b are different).

In particular, the present invention can be applied to a silicone resin having a rigid structure composed of T units and T units as shown in the above formula (1-1) or (1-2) as well as the first crosslinking agent and the second crosslinking agent, Flexibility and curling can be improved.

X1 < 1, 0 < x2 < 0.20, . X1 < 0.35, 0.01 < x2 < 0.35, 0.05 < w0.5, more specifically 0.40 < X? 1? 0.7, 0.05? X? 2? 0.35, and 0.2? W? 0.4. In the above range, the flexibility and hardness of the window film may be improved when the first crosslinking agent and the second crosslinking agent are included. In the formulas 1-1 and 1-2, R ^1a may be a C1 to C20 alkyl group having an epoxidized C4 to C20 cycloalkyl group, and R ^1b may be a C1 to C20 alkyl group having a glycidyl group or a glycidoxy group .

More specifically, the silicone resin may be represented by the following formula 1-1-1 or 1-2-1:

&Lt; Formula 1-1-1-1 &

(EcSiO3 / ₂ ) _x1 (GpSiO3 / ₂ ) _x2

(0 <x1 <1, 0 <x2 <1, x1 + x2 = 1 in the formula 1-1-1).

<Formula 1-2-1>

(EcSiO3 / ₂ ) _x1 (GpSiO3 / ₂ ) _x2 (SiO4 / ₂ ) _w

(0 <x1 <1, 0 <x2 <1, 0 <w <1, x1 + x2 + w = 1 in the formula 1-2-1).

In the above formulas 1-1-1 and 1-2-1, x1, x2 and w may represent the ranges described in the above formulas 1-1 and 1-2. In the above range, the flexibility and hardness of the window film may be improved when the first crosslinking agent and the second crosslinking agent are included.

The silicone resin may have a weight average molecular weight of 2,000 to 20,000, specifically 4,000 to 10,000, more specifically 4,500 to 8,000. Within this range, there is an effect of supporting the coating layer of the window film in the above range. The silicone resin may have a polydispersity (PDI) of 1.0 to 3.0, specifically 1.5 to 2.5, and an epoxy equivalent of 0.1 to 100 mol, particularly 0.3 mol / 100 g to 0.8 mol / 100 g. Within the above range, the coating property of the composition for a window film is good, and the coating property may be stable.

Hereinafter, the first crosslinking agent and the second crosslinking agent will be described.

The first crosslinking agent and the second crosslinking agent may each be cured with a silicone resin by containing a crosslinking functional group. The first crosslinking agent and the second crosslinking agent may be used in the specific amounts described above, respectively, to realize a composition for a window film and a window film having the effect of the present invention. In particular, the second crosslinking agent can increase the pencil hardness by making the degree of curing uniform even in the thickness direction, while increasing the curing speed of the composition for the window film. The first crosslinking agent and the second crosslinking agent are different from each other, and they may be contained in one or more of the compositions for the window film.

The first crosslinking agent may be a crosslinking agent having one or more, preferably two or more, epoxidized alicyclic groups. Specifically, the first crosslinking agent may include C4 to C7 alicyclic groups epoxidized with an epoxidized alicyclic group, for example, an epoxycyclohexyl group and the like. The first crosslinking agent may be a non-vinyl crosslinking agent containing no vinyl group. For example, the first crosslinking agent may be selected from the group consisting of (3,4-epoxycyclohexyl) methyl-3 ', 4'-epoxycyclohexanecarboxylate, diglycidyl 1,2-cyclohexanedicarboxylate, 2- Epoxycyclohexyl) -5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxy-6-methylcyclohexyl) adipate, 3,4- Epoxycyclohexylmethyl-3 ', 4'-epoxy-6'-methylcyclohexanecarboxylate, epsilon -caprolactone-modified 3,4-epoxycyclohexylmethyl-3' Epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, β-methyl-δ-valerolactone-modified 3,4-epoxycyclohexylmethyl-3' 4-cyclohexane dimethanol bis (3,4-epoxycyclohexanecarboxylate), di (3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylene Bis (3,4-epoxy Chloride-hexane-carboxylate)), bis (3,4-epoxycyclohexylmethyl) may include one or more of the adipate.

The second crosslinking agent may be a crosslinking agent comprising at least one epoxidized alicyclic group and a vinyl group. Here, the vinyl group may be defined to include not only a vinyl group (CH ₂ = CH-) but also (meth) acrylate. Preferably, the vinyl group may refer to a vinyl group (CH ₂ = CH-). The epoxidized alicyclic group may include an epoxidized C4 to C7 alicyclic group such as an epoxycyclohexyl group. Specifically, the second crosslinking agent may include at least one of 4-vinyl-1,2-epoxycyclohexane and 3,4-epoxycyclohexylmethyl (meth) acrylate.

The first crosslinking agent and the second crosslinking agent may be contained in a weight ratio of 1: 0.1 to 1: 3 (first crosslinking agent: second crosslinking agent) to the total of the first crosslinking agent and the second crosslinking agent. Within this range, the hardness and flexibility of the window film is good and the curling can be low. Specifically in a weight ratio of 1: 0.5 to 1: 2. Within this range, the first crosslinking agent and the second crosslinking agent can better represent the function as a crosslinking agent in the composition, and the hardening rate can be increased without using an excessive amount of an initiator.

Hereinafter, the initiator will be described.

The initiator may cure the silicone resin, the first crosslinking agent and the second crosslinking agent, and may comprise a mixture of a photocationic initiator and a photocatalytic initiator. The photocationic initiator cures the silicone resin, the first crosslinking agent and the second crosslinking agent, and the photo-radical initiator induces a fast curing reaction between the second crosslinking agent. The Gwangyang ionic initiator may be included in an amount of 0.1 to 10 parts by weight, specifically 0.5 to 5 parts by weight, based on 100 parts by weight of the silicone resin. The photo-radical initiator may be included in an amount of 0.1 to 10 parts by weight, specifically 0.1 to 5 parts by weight, based on 100 parts by weight of the silicone resin. Within this range, there may be pencil hardness elevation and curl control effects.

As the Gwangyang ionic initiator, any one ordinarily known to those skilled in the art can be used, and onium salts including cations and anions can be used. Specifically, the cation is at least one selected from the group consisting of diphenyl iodonium, 4-methoxydiphenyl iodonium, bis (4-methylphenyl) iodonium, bis (4-tert- butylphenyl) iodonium, bis (dodecylphenyl) Triarylsulfonium such as diaryliodonium such as [methylphenyl] [4- (2-methylpropyl) phenyl] iodonium, triphenylsulfonium and diphenyl-4-thiophenoxyphenylsulfonium, bis [4 - (diphenylsulfonio) phenyl] sulfide, and the anions include hexafluorophosphate, tetrafluoroborate, hexafluoroantimonate, hexafluoroarsenate, hexachloroantimonate, etc. . The photo radical initiator may be an amino ketone type, benzoin type, hydroxy ketone type or phosphine oxide type. Specifically, the photo radical initiator may be benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin iso Propyl ether, benzoin n-butyl ether, benzoin isobutyl ether, 2,2-dimethoxy-2-phenylacetophenone, 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2 2-methylpropiophenone, pt-butyl trichloroacetophenone, pt-butyldichloroacetophenone, 4-chloroacetophenone, 2,2'-dichloro-4- phenoxyacetophenone, dimethylaminoacetophenone , 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy- Methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-methyl- Propane (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-nonocydiethylaminobenzophenone, dichlorobenzo Thioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, , 4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo [2-hydroxy- -Methylvinyl) phenyl] propanone] and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and the like.

The initiator may be included in an amount of 0.1 to 10 parts by weight, specifically 0.5 to 5 parts by weight, based on 100 parts by weight of the silicone resin. In this range, the silicone resin can be sufficiently cured and the remaining amount of the initiator remains, thereby preventing the optical characteristics (transmittance, hue, and light reliability) of the window film from being lowered.

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

Nanoparticles can further increase the hardness of the window film. The nanoparticles may include, but are not limited to, one or more of silica, aluminum oxide, zirconium oxide, and titanium oxide. The nanoparticles may be surface treated with some or all of the surface of the silicone compound for mixing with the silicone resin. Nanoparticles are not limited in shape and size. Specifically, the nanoparticles may include spherical, plate-like, amorphous, etc. particles. The nanoparticles may have an average particle diameter (D50) of 1 nm to 200 nm, specifically 10 nm to 50 nm. The hardness of the window film can be increased without affecting the surface roughness and transparency of the window film in the above range. The nanoparticles may be included in an amount of 0.1 to 60 parts by weight, specifically 10 to 50 parts by weight based on 100 parts by weight of the silicone resin. The hardness of the window film can be increased without affecting the surface roughness and transparency of the window film in the above range.

The composition for a window film according to this embodiment may further include 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, but is not limited to, 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 and an antioxidant. 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. Specifically, the UV absorber may include, but is not limited to, one or more UV absorbers based on triazine, benzimidazole, benzophenone, and benzotriazole. 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 silicone 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 this embodiment may further include a solvent to facilitate coating, coating or processability. The solvent may include, but is not limited to, one or more of methyl ethyl ketone (MEK, methylethylketone), methyl isobutyl ketone, and propylene glycol monomethyl ether acetate.

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

1, a flexible window film 100 according to an exemplary embodiment of the present invention includes a base layer 110 and a coating layer 120, And the like.

The substrate layer 110 supports 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 adhered to a display portion, a touch screen panel, or a polarizing plate by an adhesive layer or the like. The substrate layer 110 may be formed of an optically transparent and flexible resin. For example, the resin includes a polyester resin including a polyethylene terephthalate, a polyethylene naphthalate, a polybutylene terephthalate, a polybutylene naphthalate, etc., a polycarbonate resin, a polyimide resin, a polystyrene resin, polymethylmethacrylate (Meth) acrylate resin. &Lt; / RTI &gt; The resin may be contained in the base layer 110 alone or in combination. The base layer 110 may have a thickness of 10 占 퐉 to 200 占 퐉, specifically, 20 占 퐉 to 150 占 퐉, more specifically, 50 占 퐉 to 100 占 퐉. Can be used in the flexible window film in the above range.

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, to improve the appearance, to have high flexibility and high hardness and to be used in a flexible display device can do. The thickness of the coating layer 120 may be 5 占 퐉 to 100 占 퐉, specifically 10 占 퐉 to 80 占 퐉. Can be used in 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, or a hard coating layer may be further formed on the other surface of the coating layer 120 to provide additional functions to the flexible window film. 1, a coating layer 120 may be further formed on the other surface of the substrate layer 110. [

The flexible window film 100 may have a total light transmittance of 88% or more, specifically 88% to 100% and a haze of 1% or less, specifically 0.01% to 1%, in the visible light region specifically at a wavelength of 400 nm to 800 nm. It can be used as a flexible window film in the above range. The flexible window film 100 may have a pencil hardness of 7H or more, a radius of curvature of 5.0 mm or less, and an absolute value of curl of 3 mm or less. In the above range, the film can be used as a flexible window film with good hardness and flexibility. Specifically, the flexible window film 100 may have a pencil hardness of 7H to 9H, a radius of curvature of 0.1 mm to 5.0 mm, and an absolute value of curl of 0 mm to 2 mm. In the above range, a transparent screen can be realized even if it is used at the outermost part of the display device. The flexible window film 100 may have a thickness of 5 占 퐉 to 300 占 퐉. It can be used as a flexible window film in the above range.

Hereinafter, a flexible window film according to another embodiment of the present invention will be described with reference to FIG. 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 another embodiment of the present invention includes a flexible window film 200 according to an exemplary embodiment of the present invention, except that an adhesive layer 130 is further formed on the other surface of the substrate layer 110. As shown in FIG. Is substantially the same as the flexible window film (100). The adhesive layer 130 is further formed on the other surface of the base layer 110, so that adhesion between the flexible window film and the touch screen panel, the polarizing plate, or the display portion can be facilitated. Is substantially the same as the flexible window film according to an embodiment of the present invention, except that an adhesive layer is further formed. Hereinafter, only the adhesive layer 130 will be described.

The adhesive layer 130 adheres to a polarizing plate, a touch screen panel, or a display unit that can be disposed under the flexible window film 200, and may be formed of a composition for a pressure-sensitive adhesive layer. Specifically, the adhesive layer 130 may be formed of a composition for a pressure-sensitive adhesive layer including a pressure-sensitive adhesive resin such as a (meth) acrylic resin, a urethane resin, a silicone resin, and an epoxy resin, a curing agent, a photoinitiator and a 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 an unsubstituted C1 to C10 alkyl group, a (meth) acrylic monomer having a C1 to C10 alkyl group having at least one hydroxyl group, a (meth) acrylic monomer having an C6 to C20 aromatic group (Meth) acrylic monomer having a carboxylic acid group, a (meth) acrylic monomer having a C3 to C20 alicyclic group, a C3 to C10 heteroalicyclic group having at least one of nitrogen (N), oxygen (O) (Meth) acryl-based monomer having at least one group selected from the group consisting of (meth) acryl-based monomers.

The curing agent may be a bifunctional (meth) acrylate such as hexanediol diacrylate as a polyfunctional (meth) acrylate; 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; (Meth) acrylate such as dipentaerythritol hexa (meth) acrylate, but are not limited thereto.

The photoinitiator may include the above-described photoinitiator 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 composition for the 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. Within this range, the flexible window film can be adhered well onto the display portion, the touch screen panel or the polarizing plate.

The thickness of the adhesive layer 130 may be 10 占 퐉 to 100 占 퐉. In the above range, the optical element such as the flexible window film and the polarizing plate can be sufficiently adhered.

Hereinafter, a flexible display device according to an embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. 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, the flexible display device 300 according to an exemplary embodiment of the present invention includes a display portion 350a, an adhesive layer 360, a polarizing plate 370, a touch screen panel 380, a flexible window film 390 , And the flexible window film 390 may comprise a flexible window film according to embodiments of the present invention.

The display unit 350a is for driving the flexible display device 300 and may include an optical element including an OLED, an LED, or an LCD device formed on a substrate and a substrate. 4 is a cross-sectional view according to an embodiment of the display unit of FIG. 4, the display portion 350a may include 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 have.

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 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. Specifically, the lower substrate 310 may include, but is not limited to, a flexible substrate such as a silicon substrate, a polyimide substrate, a polycarbonate substrate, and a polyacrylate substrate.

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 flexible 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 flexible window film 390 to form a polarizing plate, a touch screen panel, a flexible It is possible to strengthen the bonding between the window films. 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.

Hereinafter, 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, the flexible display device 400 according to another embodiment of the present invention includes a display portion 350a, a touch screen panel 380, a polarizer 370, and a flexible window film 390, The window film 390 may comprise a flexible window film according to embodiments of the present invention. Except that the touch screen panel 380 is not directly formed on the flexible window film 390 but the touch screen panel 380 is formed below the polarizer 370. In this case, Device. 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, a gap 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 flexible window film 390 An adhesive layer is further formed, thereby increasing the mechanical strength of the display device. 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. 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, the flexible display device 500 according to another exemplary embodiment of the present invention includes a display portion 350b, an adhesive layer 360, and a flexible window film 390. The flexible window film 390 includes a flexible window film 390, May comprise a flexible window film according to embodiments of the present invention. Is substantially the same as the flexible display device according to an embodiment of the present invention, except that only the display portion 350b is capable of driving the device and the polarizing plate and the touch screen panel are excluded.

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.

Hereinafter, a method for manufacturing a composition for a window film according to an embodiment of the present invention will be described. The composition may be prepared by mixing a silicone resin with a first crosslinking agent, a second crosslinking agent, and an initiator. Silicone resin according to the present embodiment is a silicon monomer to provide a silicon monomer alone, or (R ¹ SiO _3/2) to provide _{^{(R 1 SiO 3/2)}} ; And _{^{(R 2 R 3 SiO 2/}} 2) a silicon monomer, to provide a ^{(R 4 R 5 R 6 SiO} 1/2) to provide the silicon monomer, (SiO _4/2) at least one mixture of the silicone monomers to provide for &Lt; / RTI &gt; (R ¹ SiO _3/2) to provide a silicone monomer is 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyl triethoxysilane, 3- doksi glycidyl trimethoxysilane, 3-glycidoxypropyltrimethoxysilane and the like can be the doksi propyl _{^{triethoxysilane, (R 2 R 3 SiO 2}} /2) to provide a silicon monomer include dimethyl dimethoxysilane, dimethyl diethoxysilane (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethylmethyltriethoxysilane and the like, and SiO _{2 / 2} ) may be, but not limited to, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and the like. In one embodiment, the monomer mixture (R ¹ SiO _3/2) silicone monomer 100mol% which provides, in particular 85mol% to about 99mol%, 1mol% to about 15mol%, 40mol% to about 75mol%, 5mol% to 35mol%, It can be a (SiO _4/2) silicone monomer 0mol%, 20mol% to 40mol% for service. Within this range, the hardness and flexibility of the window film can be improved.

The hydrolysis and condensation reaction of the monomer mixture can be carried out according to a conventional method for producing a silicone resin. Hydrolysis may comprise reacting the monomer mixture with water and a mixture of one or more of the desired acids and bases. Specifically, the acid may be HCl, HNO ₃ , acetic acid or the like, and the base may be NaOH, KOH, or the like. The hydrolysis is carried out at 20 ° C to 100 ° C for 10 minutes to 10 hours, and the condensation reaction can be carried out at 20 ° C to 100 ° C for 10 minutes to 12 hours under the same conditions as the hydrolysis. The production yield of the silicone resin in the above range may be high.

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

The flexible window film 100 can be manufactured by a method of manufacturing a flexible window film including coating and curing a composition for a window film according to embodiments of the present invention on a substrate layer 110. [

The method for coating the composition for a window film on the base layer 110 may be, but not limited to, bar coating, spin coating, dip coating, roll coating, flow coating, die coating and the like. A composition for a window film can be coated on the base layer 110 to a thickness of 5 to 100 mu m. It is possible to secure a desired coating layer within the above range, and to have an excellent hardness and flexibility. Curing is a process of curing the composition for a window film to form a coating layer, which may include at least one of light curing and heat curing. Photocuring may involve irradiation with light amount of 10mJ / cm ² to 1,000mJ / cm ² at a wavelength of 400nm or less. Thermal curing may include treating at 40 占 폚 to 200 占 폚 for 1 hour to 30 hours. Within this range, the composition for a window film can be sufficiently cured. For example, it is possible to photo-cure and then thermally cure, resulting in a higher hardness of the coating layer. The method may further include drying the composition for the window film before coating the composition for the window film on the substrate layer 110 and then curing the composition. By drying and curing, it is possible to prevent the surface roughness of the coating layer from becoming high due to long-time light curing and thermal curing. The drying may be performed at 40 캜 to 200 캜 for 1 minute to 30 hours, but is not limited thereto.

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

Manufacturing Example: Silicon  Suzy

95 mol% of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (KBM-303, ShinYeatsu) and 5 mol% of (3-glycidoxypropyl) trimethoxysilane (KBM- Was placed in a 1 L 3-neck flask. After adding 0.1 mol% of KOH to the silicone monomer mixture and 1 equivalent of water relative to the total silicone monomer, the mixture was stirred at 65 DEG C for 8 hours, washed with toluene and concentrated to obtain a silicone resin (GPC (gel chromatography) Weight average molecular weight by weight: 8,000) (EcSiO _3/2 ) _0.95 (GpSiO _3/2 ) _0.05 .

Example  One

10 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate as the first crosslinking agent, 10 parts by weight of 4-vinyl-1,2-epoxycyclohexane ( CELLOXIDE 2000), 3 parts by weight of Irgacure 250 (BASF) as a light initiator, and 0.3 parts by weight of Irgacure 369 (BASF) as a photo radical initiator were mixed, and methyl ethyl ketone To prepare a composition for a window coating layer having a concentration of 70% by weight.

The composition for the coating layer was applied to a polyimide film (thickness: 50 탆), dried at 80 캜 for 5 minutes, exposed to ultraviolet light of 1000 mJ / cm ² and further cured at 80 캜 in an oven for 24 hours, A window film having a thickness of 50 mu m was prepared.

Example  2 to Example  5

A window film was prepared in the same manner as in Example 1, except that the composition for the window coating layer was changed as shown in Table 1 below.

Comparative Example  1 to Comparative Example  4

A window film was prepared in the same manner as in Example 1, except that the composition for the window coating layer was changed as shown in Table 1 below.

The following properties of the window films prepared in Examples and Comparative Examples were measured and are shown in Table 1 below.

(1) Pencil hardness: Measured by the JIS K5400 method using a pencil hardness meter (Heidon) for the coating layer of the window film. 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) Curling: Referring to FIG. 7, the window film 1 prepared in Examples and Comparative Examples in which the thickness of the substrate layer was 80 mu m and the thickness of the coating layer was 50 mu m was cut into a width x length (10 cm x 10 cm) (H) from the bottom surface 2 to the edge portion of the flexible window film 1 is measured when it is placed on the bottom surface 2 with the window coating layer at the top and left at 25 ° C. and 40% And the average value was calculated. In the curled display, "+" means that the window film is dried toward the coating layer, and "-" means that the window film is dried toward the substrate layer. The lower the absolute value of the curl value, the lower the curl value.

(3) Radius of curvature: Window film (width x length, 1 cm x 10 cm) was visually evaluated for crack occurrence with a vernier caliper for curvature test. At this time, the direction of compression was such that the coating layers were in contact with each other in a direction in which the coating layer was not bent, and the tensile direction was in contact with the base layer in the direction of curving. The radius of curvature was measured by decreasing the radius from the larger value to the smaller value in the compression direction. The radius of curvature was determined as the minimum radius of the JIG without cracking.

Example Comparative Example One 2 3 4 5 One 2 3 4 Silicone resin
(Parts by weight) 100 100 100 100 100 100 100 100 100 The first crosslinking agent
(Parts by weight) 10 10 10 5 15 10 3 10 10 The second crosslinking agent
(Parts by weight) 5 10 15 10 10 0 10 3 25 Gwangyang ionic initiator
(Parts by weight) 3 3 3 3 3 3 3 3 3 Photo radical initiator
(Parts by weight) 0.3 0.3 0.3 0.3 0.3 0 0.3 0.3 0.3 Pencil hardness 7H 8H 8H 8H 8H 6H 8H 6H 5H curling
(mm) -One -1.75 -0.5 2 -One -3.75 9 -2 -6.5 Radius of curvature
(mm) One One One One One One One One One

As shown in Table 1, the pencil hardness of the window film of the present invention was lower than that of Comparative Example 1, which did not include the second crosslinking agent, and the absolute value of curling was low. In addition, the window film of the present invention has a low absolute value and a good pencil hardness as compared with Comparative Examples 2 to 5, in which the first crosslinking agent and the second crosslinking agent are out of the range of the present invention.

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.

Claims (10)

A silicone resin, a crosslinking agent, and an initiator,
Wherein the crosslinking agent comprises a mixture of a first crosslinking agent having an epoxidized alicyclic group and a second crosslinking agent having an epoxidized alicyclic group and a vinyl group,
Wherein the first crosslinking agent is contained in an amount of 5 to 30 parts by weight based on 100 parts by weight of the silicone resin, and the second crosslinking agent is included in an amount of 5 to 20 parts by weight.
The composition for a window film according to claim 1, wherein the amount of the first crosslinking agent is 5 parts by weight to 20 parts by weight, and the amount of the second crosslinking agent is 5 parts by weight to 15 parts by weight based on 100 parts by weight of the silicone resin.
The composition for a window film according to claim 1, wherein the first crosslinking agent and the second crosslinking agent are contained in a weight ratio of 1: 0.1 to 1: 3 in the mixture.
The method according to claim 1, wherein the first cross-linking agent is at least one selected from the group consisting of (3,4-epoxycyclohexyl) methyl-3 ', 4'-epoxycyclohexanecarboxylate, diglycidyl 1,2-cyclohexanedicarboxylate, (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxy-6-methylcyclohexyl) adipate, Epoxycyclohexylmethyl-3 ', 4'-epoxy-6'-methylcyclohexanecarboxylate, epsilon -caprolactone-modified 3,4-epoxycyclohexylmethyl-3', 4'- Cyclohexanecarboxylate, trimethylcaprolactone-modified 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, β-methyl-δ-valerolactone-modified 3,4-epoxycyclohexylmethyl Cyclohexanedimethanol bis (3,4-epoxycyclohexanecarboxylate), ethylene glycol di (3,4-epoxycyclohexylmethyl) -3 ', 4'-epoxycyclohexanecarboxylate, 1,4- Ether, ethylene bis (3 , 4-epoxycyclohexanecarboxylate)), and bis (3,4-epoxycyclohexylmethyl) adipate.
The composition for a window film according to claim 1, wherein the second crosslinking agent comprises at least one of 4-vinyl-1,2-epoxycyclohexane and 3,4-epoxycyclohexylmethyl (meth) acrylate.
The composition for a window film according to claim 1, wherein the silicone resin is represented by the following formula (1)
&Lt; Formula 1 >
(R ¹ SiO _3/2 ) _x (R ² R ³ SiO _2/2 ) _y (R ⁴ R ⁵ R ⁶ SiO _1/2 ) _z (SiO _4/2 ) _w
(Wherein R ¹ represents an epoxy group or an epoxy group-containing functional group,
R ² and R ³ are each independently hydrogen, a crosslinkable functional group, an unsubstituted or substituted C 1 to C 20 alkyl group, or an unsubstituted or substituted C 5 to C 20 cycloalkyl group,
R ⁴ , R ⁵ and R ⁶ are each independently selected from the group consisting of hydrogen, a crosslinkable functional group, an unsubstituted or substituted C 1 to C 20 alkyl group, an unsubstituted or substituted C 5 to C 20 cycloalkyl group, An aryl group of C30,
0 &lt; y < 1, 0? Y <1, 0? Z <1, 0? W <1, x + y + z + w = 1).
The composition for a window film according to claim 1, wherein the silicone resin is represented by the following formula (1-1-1):
&Lt; Formula 1-1-1-1 &
(EcSiO3 / ₂ ) _x1 (GpSiO3 / ₂ ) _x2
(Wherein, in the formula 1-1-1, Ec is a 2- (3,4-epoxycyclohexyl) ethyl group, Gp is a 3-glycidoxypropyl group, 0 <x1 <1, 0 <x2 <1, x1 + x2 = 1).
The composition for a window film according to claim 7, wherein 0.85? X1? 0.99 and 0.01? X2? 0.15.
The composition of claim 1, wherein the initiator comprises a mixture of a light-initiator and a photo-radical initiator.
A flexible window film comprising a substrate layer and a coating layer formed on the substrate layer, wherein the coating layer is formed from the composition for a window film of any one of claims 1 to 9.

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