KR20180099210A - Window film, window film laminate and image display device comprising the same - Google Patents

Abstract

The present invention relates to a window laminate. More particularly, the present invention relates to a window laminate excellent in mechanical properties such as pencil hardness and durability under severe conditions such as low temperatures, and excellent in bending properties and adhesion to a substrate by comprising: a hard coating film; and an adhesive layer laminated on one side of the hard coating film, wherein the adhesive layer has a storage elastic modulus of 0.05-0.5 MPa at -20°C.

Description

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

The present invention relates to a window film, a window film laminate including the window film, and an image display device.

Recently, display apparatuses capable of displaying information including image images are actively being developed. The display device may be a liquid crystal display (LCD) device, an organic light emitting diode (OLED) device, a plasma display panel (PDP) device, and a field emission display ) Device and the like.

In the display device, a window substrate or a window film for protecting the display panel from an external environment may be disposed on a display panel, such as an LCD panel and an OLED panel. The window substrate or window film may include a base substrate made of a glass material. Recently, a transparent plastic material has been used as the base substrate while a flexible display has been developed.

The flexible display can fold or bend and has a thinned display. However, it is necessary to take measures against damages due to an external impact and delamination between structures or delaminations.

For example, in the window substrate or window film laminate applied to the flexible display, it is necessary to secure mechanical reliability such as durability in a severe environment such as low temperature, high temperature, high humidity, and the like in consideration of bending property and thinning.

Further, when other structures or members are bonded to the window substrate or the window film laminate through the adhesive layer, it is necessary to secure adhesion or adhesion suitable for the flexible display of the adhesive layer.

Korean Patent Publication No. 2011-0111826 discloses a pressure-sensitive adhesive composition for a touch panel comprising an acrylic resin and a multi-functional cross-linking agent, but has limitations in satisfying physical properties required for a flexible display.

Korea Patent Publication No. 2011-0111826

An object of the present invention is to provide a window film having mechanical properties such as excellent pencil hardness and durability at low temperature and ensuring excellent bending properties.

Another object of the present invention is to provide a window film excellent in adhesion to various kinds of substrates, for example, a polarizer or a touch sensor film.

Further, an object of the present invention is to provide a window film laminate and an image display device including the window film described above.

1. Hard Coating Film; And a pressure-sensitive adhesive layer laminated on one surface of the hard coating film, wherein the pressure-sensitive adhesive layer has a storage elastic modulus at -20 캜 of 0.05 to 0.5 MPa.

2. The window film according to 1 above, wherein the pressure-sensitive adhesive layer has a storage elastic modulus at -20 캜 of 0.1 to 0.4 MPa.

3. The window film of claim 1, wherein the hard coating film comprises a base film and a hard coating layer laminated on the base film, wherein the adhesive layer is laminated on one side of the base film side.

4. A window film laminate comprising a window film of any one of items 1 to 3 and a polarizing plate laminated on the adhesive layer side of the window film and a touch sensor film.

5. The window film laminate according to item 4 above, wherein a window film, a polarizing plate, and a touch sensor film are sequentially laminated.

6. The window film laminate according to item 4, wherein the window film, the touch sensor film, and the polarizing plate are sequentially laminated.

7. The window laminate according to item 4 above, wherein the pencil hardness at -20 캜 measured on the opposite surface of the one side of the hard coating film is H or more.

8. An image display device comprising the window film laminate of claim 4 above.

The window film of the present invention has mechanical properties such as pencil hardness and durability which are excellent even under severe conditions such as low temperature, and has excellent bending properties.

Further, the window film of the present invention is excellent in adhesion to various substrates, for example, a polarizer or a touch sensor film.

Therefore, the window film laminate or image display device including the above-described window film has high durability against external impact, and can be applied, for example, to a flexible display.

FIG. 1 is a schematic view for explaining a window film according to embodiments of the present invention. FIG.
2 is a schematic view for explaining a window film laminate according to an embodiment of the present invention.
3 is a schematic view for explaining a window film laminate according to another embodiment of the present invention.

The present invention relates to a window laminate, and more particularly, to a window laminate having a hard coating film; And a pressure-sensitive adhesive layer laminated on one side of the hard coating film. The pressure-sensitive adhesive layer has a storage elastic modulus at -20 캜 of 0.05 to 0.5 MPa. The pressure-sensitive adhesive layer has excellent mechanical properties such as pencil hardness and durability And at the same time has excellent bending properties and adhesion to a base material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings. While the following preferred embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as defined by the following claims. It will be obvious to those skilled in the art that such modifications and variations are within the scope of the appended claims.

In the meantime, in adding the reference numerals to the constituents of the respective drawings, the same or similar reference numerals may be used for substantially the same constituents, even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

< window  Film>

1 is a view for explaining a window film according to embodiments of the present invention.

Referring to FIG. 1, the window film of the present invention includes a hard coating film 10 and an adhesive layer 20.

The hard coating film 10 may be laminated or placed on another substrate such as a polarizing plate or a touch sensor film or on the viewer side of the image display apparatus and may be laminated or placed on the viewer side of the image display apparatus, And may be provided as a substrate or a film that protects the substrate or the image display device.

The hard coating film 10 includes a first surface 10a and a second surface 10b which are opposed to each other. For example, as shown in FIG. 1, the first surface 10a is located on the outer periphery, And the second surface 10b may be a surface in contact with the adhesive layer 20 or the polarizing plate 30 to be described later.

The hard coating film 10 may include, for example, a base film 11 and a hard coating layer 12 laminated on one side of the base film 11. [

The base film 11 may be provided, for example, as a base substrate which can be laminated on a polarizing plate 30 to be described later. The base film 11 may be, for example, a transparent polymer film, and the base film 10 may be made of triacetylcellulose, acetylcellulose butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butyrylcellulose, Polyvinylidene chloride, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, A polymer film such as polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate and cycloolefin polymer (COP) . &Lt; / RTI &gt; The base film may include a cycloolefin polymer film from the standpoint of satisfying mechanical properties such as durability by satisfying transparency and flexibility while having an appropriate hardness, alone or in combination of two or more thereof .

The base film 11 may be subjected to a surface treatment such as a plasma treatment or a corona treatment in order to improve adhesion with the hard coat layer 12 laminated on the base film 11 or the adhesive layer 20 to be described later.

The thickness of the base film 11 is not particularly limited, and may be, for example, 8 to 1000 占 퐉, and preferably 40 to 100 占 퐉. If the thickness of the base film 10 is less than 8 m, the workability may be deteriorated. If the thickness is more than 1000 m, the transparency may decrease or the weight of the polarizing plate may increase.

The hard coat layer 12 may be laminated on the base film 11 in terms of complementing the hardness, scratch resistance and impact resistance of the base film 11 or a window film laminate including the base film 11, an image display device and the like.

The hard coat layer 12 may be formed, for example, by applying a composition for forming a hard coat layer on the base film 11 and then curing by light or heat.

The composition for forming the hard coat layer is not particularly limited and may include, for example, a photo-curable compound and a photoinitiator.

The photo-curing compound may be, for example, a photopolymerizable monomer, a photopolymerizable oligomer, or the like, and may be, for example, a monofunctional and / or polyfunctional ) Acrylate. These may be used alone or in combination of two or more.

In the present invention, "(meth) acrylic-" refers to "methacryl- "," acrylic- "

Specific examples of the photopolymerizable monomer include dipentaerythritol penta / hexa (meth) acrylate, pentaerythritol tri / tetra (meth) acrylate, ditrimethylol propane tetra (meth) acrylate, (meth) acrylic ester, trimethylol (Meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol (meth) acrylate, glycerol tri (meth) acrylate, tris Acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) , Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, bis (2-hydroxyethyl) isocyanurate di (Meth) acrylate, isooctyl (meth) acrylate, isohexyl (meth) acrylate, isohexyl (meth) acrylate, (Meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate and isobonol (meth) acrylate. These may be used alone or in combination of two or more.

The photopolymerizable oligomer may be at least one selected from the group consisting of epoxy (meth) acrylate, urethane (meth) acrylate and polyester (meth) acrylate. Specific examples thereof include urethane (Meth) acrylate or a mixture of two kinds of polyester (meth) acrylates can be used. Preferably, a urethane (meth) acrylate oligomer may be used to improve the scratch resistance and hardness of the cured product and to increase the storage modulus of the hard coat film.

The urethane (meth) acrylate can be prepared by reacting a compound having a polyfunctional (meth) acrylate having a hydroxyl group in the molecule and an isocyanate group in the presence of a catalyst according to a method known in the art.

Specific examples of the urethane (meth) acrylate oligomer include the reaction of 2-hydroxyethyl (meth) acrylate and 2,4-tolylene diisocyanate, the reaction of 2-hydroxyethyl (meth) acrylate and isophorone diisocyanate Reaction of 2-hydroxybutyl (meth) acrylate and 2,4-tolylene diisocyanate, reaction of 2-hydroxybutyl (meth) acrylate and isophorone diisocyanate, reaction of pentaerythritol tri (meth) acrylate And reaction of 2,4-toluene diisocyanate, reaction of pentaerythritol tri (meth) acrylate and isophorone diisocyanate, reaction of pentaerythritol tri (meth) acrylate and dicyclohexylmethane diisocyanate, reaction of dipentaerythritol penta (Meth) acrylate and isophorone diisocyanate, dipentaerythritol penta (meth) acrylate and The product of the reaction of dicyclohexylmethane diisocyanate.

The polyester (meth) acrylate can be prepared by reacting a polyester polyol and acrylic acid according to methods known in the art.

The polyester (meth) acrylate may be, for example, a polyester acrylate, a polyester diacrylate, a polyester tetraacrylate, a polyester hexaacrylate, a polyester pentaerythritol triacrylate, a polyester pentaerythritol tetraacrylate , And polyester pentaerythritol hexaacrylate, but is not limited thereto.

The content of the photocurable compound is not limited, and the composition for forming a hard coat layer may include 10 to 60 parts by weight of the photocurable compound based on 100 parts by weight of the composition for forming a hard coat layer, preferably 20 to 45 parts by weight . If the amount is less than 20 parts by weight, physical properties such as hardness may not be secured in the hard coat layer 12, such as hardness and abrasion resistance, and the flexibility may be lowered. .

The photoinitiator is used for curing the composition for forming a hard coat layer and can be used without limitation as long as it is generally used in the art.

In some embodiments, the photoinitiator may be one that initiates a polymerization reaction of the hard coating composition by generating a cation or Lewis acid by irradiation of an active energy ray, such as visible light, ultraviolet light, X-rays or electron beams, It is advantageous in terms of storage stability and workability even when mixed with a composition for forming a hard coat layer.

The photoinitiator may be at least one selected from the group consisting of hydroxy ketones, aminoketones, and hydrogen recycling photoinitiators.

Specific examples of the photoinitiator include bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenyl Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1, diphenyl ketone benzyl dimethyl ketal, 2-hydroxy- 3-methylacetophenone, 4,4-dichloroacetophenone, 4,4-dichloroacetophenone, 4,4-dihydroxybenzophenone, 4-diaminobenzophenone, 1-hydroxycyclohexyl phenyl ketone, benzophenone, and the like, and commercially available products include IRGACURE 184 (manufactured by Ciba) Etc. may be used.

The content of the photoinitiator is not limited, but it is preferable that the composition for forming a hard coat layer is contained in an amount of 10 parts by weight or less, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the composition for forming a hard coat layer. If the content exceeds 10 parts by weight, cracking may occur due to overaging.

The present invention may contain a solvent in addition to the photocurable compound and the photoinitiator. Since the solvent is a component that can be removed in the course of curing after forming the hard coat layer, it is preferable to use the solvent for diluting the prepared composition for hard coat layer.

The solvent may be used without limitation as long as it is known as a solvent in a composition for forming a hard coat layer in the art.

Examples of the solvent include alcohols such as methanol, ethanol, isopropanol, butanol, methylcellulose, ethylsorbox, etc., ketones such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, (Propylene glycol monomethyl ether, propylene glycol monoethyl ether and the like) and the like can be used as the organic solvent (for example, benzene, toluene, xylene, etc.) have. The solvents exemplified above may be used alone or in combination of two or more.

The composition for forming a hard coat layer may include 0.1 to 85 parts by weight of the solvent based on 100 parts by weight of the composition for forming a hard coat layer. If the content is less than 0.1 parts by weight, the viscosity of the composition may be high and the workability may be deteriorated. If the content is more than 85 parts by weight, the curing process may take a long time and the economical efficiency may decrease.

In one embodiment, the hard coating layer 12 or composition for forming a hard coating may further comprise inorganic nanoparticles. As the inorganic nanoparticles are included, the mechanical properties such as abrasion resistance, scratch resistance, and pencil hardness of the hard coating film or hard coating film can be further improved.

The kind of the inorganic nanoparticles is not particularly limited, and examples thereof include Al ₂ O ₃ , SiO ₂ , ZnO, ZrO ₂ , BaTiO ₃ , TiO ₂ , Ta ₂ O ₅ , Ti ₃ O ₅ , indium- (ITO), indium-zinc-oxide can be a (ATO), ZnO-Al, Nb 2 O 3, SnO, MgO , or metal oxide-based combinations thereof-oxide (IZO), antimony-tin. In one embodiment, Al ₂ O ₃ , SiO ₂ and / or ZrO ₂ may be used as the inorganic nanoparticles.

In one embodiment, the composition for forming a hard coat layer or the hard coat layer 12 may contain, in addition to the above-mentioned components, an antioxidant, a UV absorber, a light stabilizer , A leveling agent, a surfactant, and an antifouling agent.

The application or coating of the composition for forming a hard coating layer may be carried out by a method such as slit coating, knife coating, spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, It may be carried out by a known method such as a spraying method, a spray coating method, a screen printing method, a gravure printing method, a flexo printing method, an offset printing method, an ink jet coating method, a dispenser printing method, a nozzle coating method or a capillary coating method.

After the composition for forming the hard coat layer is applied, the volatiles are evaporated at a temperature of 30 to 150 DEG C for 10 seconds to 90 minutes, more preferably 30 seconds to 70 minutes. And then cured by irradiating UV light. The irradiation amount of the UV light is preferably about 0.01 to 10 J / cm 2, more preferably 0.1 to 2 J / cm 2.

The thickness of the hard coat layer 12 is not particularly limited, and may be, for example, 3 to 15 占 퐉. When the content is within the above range, a surface treatment film for a polarizing plate having both excellent hardness and antireflection effect can be realized, which is preferable.

The adhesive layer 20 is a layer formed for adhering or laminating the hard coating film 10 to other substrates such as the polarizing plate 30 and the touch sensor film 40 and may be laminated on one side of the hard coating film 10 And is stacked on the second surface 10b of the hard coating film 10, for example, as shown in Fig. 1, the adhesive layer 20 may be laminated on one side of the substrate film 11 on which the hard coating layer 12 is laminated.

The pressure-sensitive adhesive layer 20 according to the present invention has a storage elastic modulus at -20 캜 of 0.05 to 0.5 MPa.

The window film is required to have a bending property suitable for a flexible device while having durability that can be laminated, bonded or positioned on an image display device including the window film to withstand external physical and chemical impacts, Type substrate, there is a possibility of occurrence of deformation, lifting, peeling, cracking, etc. in a severe environment such as a low temperature as well as a general environment such as room temperature. However, when the pressure-sensitive adhesive layer for adhesion or adhesion with a window film or other substrate does not satisfy a certain level of elasticity, or does not satisfy a certain hardness, the surface of the window film is deformed due to various external shocks, There is a concern that it may become unsuitable for application.

However, since the storage elastic modulus of the adhesive layer 20 according to the present invention at -20 캜 is 0.05 to 0.5 MPa, the adhesive strength between the other substrates bonded to the hard coating film 10 can be sufficiently realized, It is possible to effectively prevent surface deformation, lifting and peeling of the hard coating film 10 due to an external impact even in a severe environment. When the storage elastic modulus of the adhesive layer 20 at -20 캜 is less than 0.05 MPa, the hardness required of the adhesive layer 20 is not satisfied and the hard coating film 10 can not withstand the external impact sufficiently, , And when it exceeds 0.5 MPa, flexural characteristics or flexibility required for a flexible device is insufficient.

In one embodiment, the storage modulus of the pressure-sensitive adhesive layer 20 at -20 캜 may be 0.1 to 0.4, and is preferable in terms of prevention of deformation of the surface of the hard coating film 10 and improvement of bending property .

In one embodiment, the storage modulus of the adhesive layer 20 at 20 캜 may be 0.05 to 0.5 MPa. In the above range, it is possible to minimize the difference from the storage modulus at low temperatures (-20 DEG C) as described above, thereby minimizing the deformation of the hard coating film 10 or other substrates bonded to the hard coating film 10 according to the temperature condition It is possible to maintain the durability of them and to have excellent durability, which is more preferable. The difference between the (storage) elastic modulus at 20 ° C and the storage elastic modulus at -20 ° C of the adhesive layer 20 is preferably as small as possible, preferably the storage elastic modulus at 20 ° C and the storage at -20 ° C The difference in elastic modulus may be from 0 to 0.2, which is preferable in terms of securing the hardness and bending property suitable for the flexible device and minimizing the possibility of deformation of the hard coating film 10 depending on the temperature.

In one embodiment, the adhesive layer 20 can be formed, for example, by applying and curing a composition for forming an adhesive layer on the second surface 10b of the hard coating film 10 or the base film 11 The kind of the composition for forming an adhesive layer is generally used in the art, and is not particularly limited within the scope of the present invention. For example, the pressure-sensitive adhesive layer 20 may satisfy the above- A composition for forming a pressure-sensitive adhesive or an adhesive layer may be used.

Specifically, the adhesive layer 20 can be formed by a composition for forming a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive copolymer such as a (meth) acrylic, silicone, rubber, urethane, polyester or epoxy copolymer, Optical Clear Adhesive) composition, preferably a coating layer formed of a composition for forming an adhesive layer containing an acrylic copolymer.

The composition for forming a pressure-sensitive adhesive layer containing a (meth) acrylic copolymer may include, for example, a (meth) acrylic copolymer, a crosslinkable monomer, and a crosslinking agent.

In one embodiment, the (meth) acrylic copolymer may be polymerized by further including a (meth) acrylate monomer. Here, (meth) acrylate means acrylate or (meth) acrylate.

The (meth) acrylate monomer is not particularly limited as long as it can be generally used in the pressure-sensitive adhesive composition of the related art, and may be, for example, a (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms.

Examples of the (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms include n-butyl (meth) acrylate, 2-butyl (meth) acrylate, (Meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (Meth) acrylate, nonyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate and lauryl (meth) acrylate. Of these, n-butyl acrylate, Mixtures of these are preferred. These may be used alone or in combination of two or more.

The (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms is preferably contained in an amount of 77 to 98.9 parts by weight based on 100 parts by weight of the total monomers used in the production of the (meth) acrylic copolymer. When the content is less than 77 parts by weight, the adhesive force may not be sufficient and the release film peeling force may be increased. When the content exceeds 98.9 parts by weight, the cohesive strength may be lowered and the durability may be deteriorated.

In one embodiment, the (meth) acrylic copolymer may be polymerized by further including a crosslinkable monomer copolymerizable with the (meth) acrylate monomer described above.

The crosslinkable monomer may include, for example, a monomer having a hydroxyl group, a monomer having a carboxyl group, a monomer having an amide group, a monomer having a tertiary amine group, or a combination thereof.

Specific examples of the monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate, 2-hydroxypropyleneglycol (meth) acrylate, 2-hydroxypropyleneglycol (meth) acrylate, hydroxyalkyl Hydroxypropyl vinyl ether, 6-hydroxyhexyl vinyl ether, 7-hydroxyheptyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9-hydroxybutyl vinyl ether, Hydroxynonyl vinyl ether, 10-hydroxydecyl vinyl ether, and the like.

Examples of the monomer having a carboxyl group include monovalent acids such as (meth) acrylic acid and crotonic acid; Dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid, and monoalkyl esters thereof; 3- (meth) acryloylpropionic acid; A succinic anhydride ring-opening addition adduct of 2-hydroxyalkyl (meth) acrylate in which the alkyl group has 2 to 4 carbon atoms, anhydrous succinic ring opening adduct of a hydroxyalkylene glycol (meth) acrylate having 2 to 4 carbon atoms in the alkylene group , Compounds obtained by ring-opening addition of succinic anhydride to caprolactone adducts of 2-hydroxyalkyl (meth) acrylates whose alkyl groups have 2-3 carbon atoms, and among these, (meth) acrylic acid is preferable.

Examples of the monomer having an amide group include (meth) acrylamide, N-isopropylacrylamide, N-tertiary butyl acrylamide, 3-hydroxypropyl (meth) acrylamide, 4-hydroxybutyl (Meth) acrylamide, 8-hydroxyoctyl (meth) acrylamide and 2-hydroxyethylhexyl (meth) acrylamide. Of these, (meth) acrylamide is preferable.

Examples of the monomer having a tertiary amine group include N, N- (dimethylamino) ethyl (meth) acrylate, N, N- (diethylamino) ethyl (meth) Methacrylate, and the like.

The crosslinkable monomer is preferably contained in an amount of 0.05 to 10 parts by weight, more preferably 1 to 8 parts by weight, based on 100 parts by weight of the (meth) acrylic copolymer. When the content is within the above range, the cohesive force and durability of the pressure-sensitive adhesive are excellent.

Further, in addition to the above monomers, other polymerizable monomers known in the art may be further added in such a range as not to lower the adhesive force, for example, 10 parts by weight or less.

The method of producing the (meth) acrylic copolymer is not particularly limited, and can be produced by a method such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization which is generally used in the art, and solution polymerization is preferable . A polymerization initiator (for example, azobisisobutyronitrile (AIBN) or the like), a chain transfer agent for controlling the molecular weight, and the like can be used.

The (meth) acrylic copolymer preferably has a weight average molecular weight (polystyrene conversion, Mw) of from 500,000 to 170,000, more preferably from 800,000 to 1,500,000 as measured by Gel Permeation Chromatography (GPC) It is good in terms of improving durability and reliability of the layer.

The crosslinking agent further improves the adhesion and durability, and can maintain the reliability at a high temperature and the shape of the pressure-sensitive adhesive.

The crosslinking agent of the present invention may include an isocyanate crosslinking agent specifically in view of improvement in durability and is preferably used in view of improving durability and reliability of the pressure-sensitive adhesive layer formed with excellent compatibility with the (meth) acrylic copolymer Do.

Examples of the isocyanate crosslinking agent include tolylene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethyl xylene diisocyanate , Diisocyanate compounds such as naphthalene diisocyanate; An adduct obtained by reacting 3 equivalents of a diisocyanate compound with 1 equivalent of a polyhydric alcohol compound such as trimethylolpropane, an isocyanurate compound in which 3 equivalents of a diisocyanate compound is self-condensed, a diisocyanate obtained from 2 equivalents in 3 equivalents of a diisocyanate compound, A multifunctional isocyanate compound containing three functional groups such as burette, triphenylmethane triisocyanate and methylene bistriisocyanate in which the remaining one equivalent of diisocyanate is condensed in urea; , But are not limited thereto.

The content of the crosslinking agent is not particularly limited within a range that can fulfill its function. For example, the amount of the crosslinking agent may be 0.01 to 10 parts by weight, preferably 0.02 to 2 parts by weight based on 100 parts by weight of the acrylic copolymer. If the content is less than 0.1 part by weight, the cohesive force becomes small due to insufficient crosslinking, which may impair the physical properties of the durability and cutability. If the content is more than 10 parts by weight, the residual stress due to the excessive crosslinking reaction may be deteriorated.

The crosslinking agent may further include a crosslinking agent known in the art in addition to the isocyanate crosslinking agent. Examples of the crosslinking agent include epoxy, metal chelating, polyfunctional acrylate, and oxazoline. Any combination of species can be used.

In addition to the isocyanate crosslinking agent, melamine derivatives such as hexamethylol melamine, hexamethoxymethyl melamine, hexabutoxymethyl melamine and the like; Polyepoxy compounds, for example, bisphenol A and epichlorohydrin condensate type epoxy compounds; At least one crosslinking agent selected from the group consisting of polyglycidyl ether of polyoxyalkylene polyol, glycerin di- or triglycidyl ether, and tetraglycidyl xylenediamine may be further added and used together.

In one embodiment, the composition for forming an adhesive layer may further comprise a silane coupling agent, if necessary.

The kind of the silane coupling agent is not particularly limited, and examples thereof include vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- 3-glycidoxypropyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, Acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane , N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) Methyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3- 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatepropyltriethoxysilane, substituted acetamide group-containing silane, and the like. It is preferable to use a substituted acetamide group-containing silane in order to simultaneously satisfy the workability. These may be used alone or in combination of two or more.

The silane coupling agent may be contained in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the copolymer based on the solid content. If the content exceeds 10 parts by weight, the durability may be lowered.

The composition for forming an adhesive layer may further contain additives such as a tackifier resin, an antioxidant, an anticorrosive agent, an antistatic agent, a leveling agent, a surface lubricant, and a lubricant to control the adhesion, cohesion, viscosity, elastic modulus, An antifoaming agent, a filler, a light stabilizer, a reaction initiator, a solvent, and the like.

The composition for forming an adhesive layer may further comprise a curing agent, a photoinitiator, a coupling agent, and the like.

 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) acrylate such as dipentaerythritol penta (meth) acrylate; (Meth) acrylate such as dipentaerythritol hexa (meth) acrylate, but are not limited thereto.

The photoinitiator accelerates the internal and surface hardening of the composition for forming a pressure-sensitive adhesive or pressure-sensitive adhesive layer. The type of the photoinitiator is not particularly limited as long as it is known in the art. Examples thereof include thioxanthone, phosphorus, triazine, Benzophenone type, benzoin type or oxime type. Of these, azobisisobutyronitrile (AIBN) may be used.

The curing is not particularly limited, but may include photo-curing using ultraviolet rays.

The method of applying the pressure-sensitive adhesive layer-forming composition is not particularly limited as long as it is a method known in the art, and examples thereof include bar coater, air knife, gravure, reverse roll, kiss roll, spray, blade, die coater, casting, And the like can be used.

In order to satisfy the storage elastic modulus range of the above-described adhesive layer 20, it may be made by appropriately configuring various components that can be included in the adhesive layer 20 or their compositions. For example, the compositions and molecular weights of the photoinitiators and copolymers included in the composition for forming an adhesive layer may be changed, the amount of light may be controlled, or various components contained in the composition for forming an adhesive layer, for example, It is possible to satisfy the storage elastic modulus range of the adhesive layer 20 of the present invention.

The thickness of the adhesive layer 20 is not particularly limited, and may be specifically 10 to 100 占 퐉. When the thickness is within the above range, it is preferable to implement a thin film device and to protect the hard coating film 10 from external impact, and to secure hardness and flexibility.

< window  film The laminate  And image display device>

Figs. 2 and 3 are schematic views for explaining a window film laminate according to embodiments. Fig.

Referring to Figures 2 and 3, the present invention provides a window film laminate comprising the above-described window film.

The window film laminate according to embodiments of the present invention may include the window film, the polarizer 30 and the touch sensor film 40 described above. Specifically, the window film, the adhesive layer 20 of the window film, And a polarizing plate 30 and a touch sensor film 40 laminated on the polarizing plate 30 side.

The window film laminate may comprise the window film described above, for example, the window film may be located on the outermost layer on the viewer side of the window film laminate. Accordingly, the window film according to the present invention can achieve highly desirable performance such as durability and flexural characteristics due to the excellent surface deformation preventing property and the bending property of the window film laminate.

2, a window film, a polarizing plate, and a touch sensor film are sequentially laminated on a window film laminate according to an embodiment of the present invention.

For example, as shown in FIG. 2, the polarizing plate 30 may be laminated on the other surface opposite to one surface of the adhesive layer 20 that is in contact with the second surface 10b of the hard coating film 10.

As the window film is laminated on the polarizing plate 30, the polarizing plate 30 can be effectively protected from external impact and is effectively suitable for a flexible device application. Specifically, the window film according to the present invention has a storage elastic modulus range of the above-described adhesive layer 20 and a pencil hardness range at -20 캜 measured on the first surface 10a of the hard coating film 10, The durability and the bending property of the laminate can be optimally defined. Therefore, it is possible to satisfy the bending property required for the polarizing plate or the image display device including the polarizing plate, and is effective for preventing surface deformation.

The polarizing plate 30 may be a polarizer single layer structure or a laminated structure including a polarizing film and a protective film bonded to at least one surface of the polarizer.

The polarizing plate 30 may be one obtained by swelling, dyeing, crosslinking, stretching, washing with water, and drying a polarizing film commonly used in the art.

The polarizing plate 30 according to the present invention can be a polarizer conventionally used in the art, which is manufactured according to a process including a step of swelling, dyeing, crosslinking, stretching, washing, drying, and the like.

The polarizer-forming film is not particularly limited as long as it is a dichroic material, that is, a film that can be dyed with iodine. For example, a polyvinyl alcohol film, a dehydrated polyvinyl alcohol film, a dehydrochlorinated polyvinyl alcohol film , A polyethylene terephthalate film, an ethylene-vinyl acetate copolymer film, an ethylene-vinyl alcohol copolymer film, a cellulose film, and partially saponified films thereof. Of these, a polyvinyl alcohol-based film is preferable because it has an excellent effect of enhancing the uniformity of the degree of polarization in the plane and is excellent in dye affinity for iodine.

The polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith.

Other monomers copolymerized with vinyl acetate are generally used in the art and are not limited as long as they do not deviate from the object of the present invention. Specific examples thereof include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, For example.

The modified polyvinyl alcohol resin may be a modified polyvinyl alcohol resin. Specific examples thereof include polyvinyl formal and polyvinyl acetal modified with aldehydes.

The degree of saponification of the polyvinyl alcohol-based resin may be 85 to 100 mol%, preferably 98 to 100 mol%, and the degree of polymerization of the polyvinyl alcohol-based resin may be 1,000 to 10,000, preferably 1,500 to 5,000 have.

The thickness of the polarizer-forming film is not particularly limited, and may be, for example, 10 to 150 mu m.

The kind of the protective film is not particularly limited as long as it is a plastic film having transparency, and it is preferable that the protective film is excellent in mechanical strength, thermal stability, moisture barrier property, isotropy, etc., in addition to transparency.

Specific examples of the protective film include polyester films such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate and polybutylene terephthalate; Cellulose-based films such as diacetylcellulose, triacetylcellulose, acetylcellulose butylate, isobutylester cellulose, propionylcellulose, butyrylcellulose, and acetylpropionylcellulose; Polycarbonate film; Acrylic films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene-based films such as polystyrene and acrylonitrile-styrene copolymer; Polyolefin-based films such as polyethylene, polypropylene, cyclo-based or norbornene-based polyolefin-based films, and ethylene propylene copolymers; Ethylene-vinyl acetate copolymer film; Polyamide film; Polyimide, polyetherimide film; Polyethersulfone-based films; Sulfone based films; Polyvinyl chloride, polyvinylidene chloride film; Polyvinyl alcohol, polyvinyl acetal film; Polyetherketone, polyetheretherketone film; Polyurethane, epoxy film and the like. These may be unoriented, uniaxial or biaxially oriented films. Of these, monoaxially or biaxially oriented polyester films, polymethylmethacrylate films or polycycloolefin-based films superior in transparency and heat resistance, and triacetyl cellulose and isobutyl ester cellulose films in terms of transparency and optical anisotropy desirable.

And may be 20 to 100 mu m of the protective film. Though the thickness of the protective film is preferably small, if it is too thin, the strength is lowered and the workability is lowered. If it is too thick, the transparency is lowered or the weight of the polarizing plate is increased.

The window film laminate of the present invention may further include a configuration known in the art in addition to the polarizer 30.

For example, the window film laminate may further include a touch sensor film 40 known in the art. The image display apparatus according to one embodiment may include a touch sensor film 40 stacked on the other surface opposite to one surface of the polarizing plate 30 in which the window film is stacked as shown in FIG. The touch sensor film 40 may be one commonly used in the art, for example, triacetylcellulose (TAC).

The touch sensor film 40 and the polarizer 30 may be formed of a pressure sensitive adhesive layer (not shown) formed through a separate pressure sensitive adhesive layer (not shown), for example, pressure sensitive adhesive (PSA) As shown in Fig.

The polarizing plate 30 and the touch sensor film 40 are effectively protected from external impact due to the window film described above. The window film described above can prevent surface deformation even under severe conditions such as low temperature and has excellent bending property so that the window film laminate according to the present invention can be effectively protected not only at room temperature but also under low temperature conditions and can be realized by a flexible image display device Is very desirable.

3 is a schematic view for explaining a window film laminate according to another embodiment of the present invention.

 Referring to FIG. 3, the window film laminate is sequentially laminated with the window film, the touch sensor film 40, and the polarizer 30 described above. Compared with FIG. 2, the image display apparatus of the embodiment shown in FIG. 3 differs in that the order of stacking the polarizing plate 30 and the touch sensor film 40 is different. For example, the window film laminate according to one embodiment may further include a polarizer 30 laminated on the other surface opposite to one surface of the touch sensor film 40 on which the window film is laminated.

The material, configuration, and adhesion method of the polarizing plate 30 and the touch sensor film 40 are the same as or similar to the materials, construction, and adhesion method of the polarizing plate 30 and the touch sensor film 40 described above, The film laminate is preferable for being realized as a flexible image display device due to the protection effect from the external impact of the window film, the prevention of surface deformation under severe conditions such as low temperature, and the excellent bending characteristic effect.

Further, in the case of the window film laminate of the present invention, the pencil hardness at -20 캜 measured on the opposite surface (for example, the first surface 10a) of the one side of the hard coating film 10 is not less than H . If the pencil hardness is less than H, durability of the hard coating film 10 or the window laminate is insufficient, and there is a risk of scratches and cracks. Since the adhesive layer 20 of the window film laminate of the present invention satisfies the storage elastic modulus range described above, it is possible to effectively prevent surface deformation of the hard coat film 10 due to an external impact, The hard coat film 10 preferably has a thickness of -20 (mm) measured on the other side opposite to the one side of the hard coating film 10, and is preferably suitable for the application of an image display device, more preferably a flexible image display device, The pencil hardness at &lt; RTI ID = 0.0 &gt; 0 C &lt; / RTI &gt; may range from H to 3H, which is desirable in terms of improving durability and ensuring bending properties of the window film laminate.

The present invention also provides an image display apparatus including the above-described window film or window film laminate.

The image display device can position, laminate, or arrange the window film or window film laminate on the outermost periphery of the viewer side of the image display apparatus, for example, and thus has high durability against external impact, Surface deformation can be prevented even under severe conditions, and the bending property is also excellent.

The image display apparatus of the present invention may further include configurations known in the art in addition to the configurations described above.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. It will be apparent to those skilled in the art that these embodiments are illustrative of the present invention and are not intended to limit the scope of the appended claims and that various changes and modifications may be made to the embodiments within the scope and spirit of the invention, Such variations and modifications are intended to be within the scope of the appended claims.

Manufacturing example

(One) ( Meta ) Preparation of acrylic copolymer (A)

A monomer mixture composed of 95 parts by weight of n-butyl acrylate and 5 parts by weight of 4-hydroxybutyl acrylate was added to a 1 L reactor equipped with a cooling device to easily regulate the temperature and nitrogen gas was refluxed, 400 parts by weight of acetate were added. Nitrogen gas was then purged for 1 hour to remove oxygen and then maintained at 62 ° C. (A-1) having a weight-average molecular weight of about 1,500,000 was prepared by reacting the mixture in an amount of 0.07 parts by weight as azobisisobutyronitrile (AIBN) as a reaction initiator and reacting for about 8 hours. .

The content of n-butyl acrylate and 4-hydroxybutyl acrylate and the reaction time were controlled to obtain a (meth) acrylic copolymer according to the above-mentioned method, and the contents of A-2 to A- (Meth) acrylic copolymer.

 (Meth) acrylic copolymer A-1 A-2 A-3 A-4 A-5 A-6 A-7 A-8 A-9 n-butyl acrylate 95 90 92 95 94 100 85 80 75 4-hydroxybutyl acrylate 5 10 8 5 6 - 15 20 25 Reaction time 5hr 2 hr 8hr 6hr 8hr 8hr 8hr 6hr 7hr Molecular Weight 1.5 million 145 million 1.4 million 1 million 52 million 1.8 million 220 million 2 million 2.4 million

(2) Adhesive layer  Preparation of composition for forming

The components shown in Table 2 below were mixed to prepare compositions for the adhesive layer formation of Production Examples 1 to 9.

Composition for forming an adhesive layer Manufacturing example One 2 3 4 5 6 7 8 9 (Meth) acrylic copolymer
(Parts by weight) A-1 100 - - - - - - - - A-2 - 100 - - - - - - - A-3 - - 100 - - - - - - A-4 - - - 100 - - - - - A-5 - - - - 100 - - - - A-6 - - - - - 100 - - - A-7 - - - - - - 100 - - A-8 - - - - - - - 100 - A-9 - - - - - - - - 100 Cross-linking agent
(Parts by weight) B-1 0.03 - - 0.03 - - - - - B-2 - 0.03 - - 0.03 - - - - B-3 - - 0.03 - - 0.03 - - 0.03 menstruum C-1 400 400 400 400 400 400 200 200 400 A-1 to A-9: (meth) acrylic copolymers (see Table 1 above)
B-1: An adduct of trimethylolpropane and xylylene diisocyanate (XDI)
B-2: An adduct of trimethylolpropane and tolylene diisocyanate (TDI)
B-3: An adduct of trimethylolpropane and hexamethylene diisocyanate (HDI)
E-1: Ethyl acetate

Example

Example  One: window  Film and window  film Of the laminate  Produce

(1) Preparation of composition for forming hard coat layer

3-glycidoxypropyltrimethoxysilane and water were mixed at a ratio of 23.63 g: 2.70 g (0.1 mol: 0.15 mol) and placed in a 100 mL 2 neck flask. Then, 0.05 mL of ammonia was added to the mixture as a catalyst, and the mixture was stirred at 60 ° C for 6 hours to prepare a siloxane sol.

The siloxane sol and the diglycidyl ether were mixed in a weight ratio of 100: 10, and 2 parts by weight of triarylsulfonium hexafluoroantimonate salt was mixed with 100 parts by weight of the mixture to prepare a hard coat layer composition .

(2) Manufacture of window films

The composition for forming a hard coat layer was coated on a COP film having a size of 179.1 mm x 105.8 mm and a thickness of 10 m by a corona treatment to form a hard coat layer. The hard coat layer was exposed to a mercury UV (Ultra Violet) lamp (20 mW / cm ² ) for 5 minutes to initiate the reaction by the triarylsulfonium hexafluoroantimonate salt , And subjected to a heat treatment for 60 minutes at 50 캜 and 50% relative humidity.

Thereafter, the composition for forming an adhesive layer of Production Example 1 was coated on one side of the COP film so as to have a thickness of 50 占 퐉 and dried in an oven. Then, the film was irradiated at a speed of 23 m / min using an ultraviolet light irradiator and cured, and dried at 100 ° C for 1 minute to form a pressure-sensitive adhesive layer.

(3) Measurement of storage elastic modulus

The storage elastic modulus of the produced pressure-sensitive adhesive layer at -20 캜 was measured using a rheometer (manufacturer: Anton Paar, model name: MCR-301), and the results are shown in Table 2 below.

(4) Production of window film laminate

(Triacetylcellulose) touch sensor film (first substrate) having a size of 164.89 mm x 104.8 mm and a thickness of 30 m as a touch sensor film on a glass substrate of 300 mm x 300 mm in size (manufactured by JR Kyushu Co., Ltd.) × 104.8 mm and a thickness of 38 μm were sequentially laminated using a pressure-sensitive adhesive, and the remaining release film of the adhesive layer of the window film was removed and attached to the second substrate A window film laminate (see FIG. 2) having a structure of a glass substrate-a first substrate-a second substrate-an adhesive layer-a hard coat layer-a base film was prepared.

(5) Low temperature (-20 ° C) Pencil hardness measurement

Pencil hardness was measured on the upper surface (first side, see 10a in Fig. 2) of the hard coat film of the window film laminate of Examples and Comparative Examples. The pencil hardness was measured at -20 ° C using an evaluation machine manufactured by Pencil Hardness Tester (Mobo Scientific) in accordance with JIS K 5400, 5600 standard, and the pencil was a hardness guarantee pencil manufactured by Mitsubishi Co. 6B to 6H Hardness range Were used. In the measurement, 3 lots were evaluated with 1 lot of 5 times, and when they were visually observed by pressing or scratching, it was treated as fail with 3 times or more scratches or scratches occurring during 5 measurements. Was judged to be OK. When no visual judgment was made, the light leakage in the measurement period was observed using a loupe or using a backlight.

Example  2 to 6 and Comparative Example  1 to 5

A window film or a window film laminate of Examples 2 to 6 and Comparative Examples 1 to 5 was prepared in the same manner as in Example 1 except that the composition for forming an adhesive layer was changed and the first base material and the second base material were different. .

Each window film was classified into Examples or Comparative Examples by measuring the storage elastic modulus of the adhesive layer at -20 캜 in the same manner as in Example 1. The low temperature pencil hardness of the window film laminate of each of the Examples and Comparative Examples was measured The measurement was carried out in the same manner as in Example 1, and the results are shown in Table 3 below.

Example Comparative Example One 2 3 4 5 6 One 2 3 4 5 Adhesive layer Composition for forming an adhesive layer Production Example 1 Production Example 2 Production Example 3 Production Example 4 Production Example 5 Production Example 1 Production Example 6 Production Example 7 Production Example 8 Production Example 9 Production Example 6 Storage modulus
(-20 &lt; 0 &gt; C, MPa) 0.50 0.45 0.44 0.20 0.07 0.48 0.70 1.14 0.92 1.40 0.80 First substrate Configuration TS TS TS TS TS POL TS TS TS TS POL Second substrate Configuration POL POL POL POL POL TS POL POL POL POL TS Low-temperature pencil hardness
(-20 ° C) H H H 2H H H 2H 2H 2H 2H H Bending characteristic ○ ○ ○ ○ ○ ○ X X X X X TS: TAC touch sensor film
POL: polyvinyl alcohol polarizer

Experimental Example : Evaluation of Flexural Characteristics

The window film laminate according to Examples and Comparative Examples was cut into a size of 10 mm x 100 mm to prepare specimens. The hard coating film was inserted into the bending property evaluation device (manufactured by Kobo Tec Co., Ltd.) so that both ends of the sample were fixed with double-sided tape. Thereafter, the curvature radius of the machine was fixed at 3R, folded 10,000 times at a rate of 30 times per minute, and the flexural characteristics were evaluated in accordance with the following evaluation criteria.

○: No cracking or destruction after folding 10,000 times

X: Cracks and fractures occur after folding less than 10,000 times

Referring to Table 3, it can be seen that the window film or window film laminate of Examples having a storage elastic modulus at -20 캜 is excellent in pencil hardness and excellent in bending property. However, it was found that the window film or window film laminate of the comparative examples was cracked or broken in evaluating the bending property, and thus it was difficult to apply to the image display device.

10: hard coating film 10a: first side
10b: second side 11: substrate film
12: hard coating layer 20: adhesive layer
30: polarizer 40: touch sensor film

Claims (8)

Hard coating film; And
And an adhesive layer laminated on one side of the hard coating film,
Wherein the storage elastic modulus of the pressure-sensitive adhesive layer at -20 캜 is 0.05 to 0.5 MPa.
The window film according to claim 1, wherein the pressure-sensitive adhesive layer has a storage elastic modulus at -20 캜 of 0.1 to 0.4 MPa.
The hard coating film of claim 1, wherein the hard coating film comprises a base film and a hard coating layer laminated on the base film,
Wherein the adhesive layer is laminated on one side of the substrate film side.
A window film laminate comprising a window film according to any one of claims 1 to 3 and a polarizer plate and a touch sensor film laminated on the adhesive layer side of the window film.
The window film laminate according to claim 4, wherein the window film, the polarizing plate, and the touch sensor film are sequentially laminated.
The window film laminate according to claim 4, wherein the window film, the touch sensor film, and the polarizing plate are sequentially laminated.
5. The window laminate according to claim 4, wherein pencil hardness at a temperature of -20 DEG C measured on the opposite surface of the one side of the hard coating film is H or more.
An image display device comprising the window film laminate of claim 4.

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