WO2018159923A1 - Window film, window film laminate comprising same and image display device - Google Patents

Abstract

The present invention relates to a window laminate, and more specifically, to a window laminate comprising: a hard coating film; and an adhesive layer laminated on one surface of the hard coating film, wherein the storage modulus of the adhesive layer at -20°C is 0.05 to 0.5 MPa, and thus excellent mechanical properties such as pencil hardness, durability, etc. may be obtained even under severe conditions such as low temperatures, etc., and at the same time, excellent bending properties and excellent adhesion to a substrate may be exhibited.

Description

Window film, window film laminated body and image display apparatus including the same

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

In recent years, display devices capable of displaying information including image images have been actively developed. The display device includes a liquid crystal display (LCD) device, an organic light emitting display (OLED) device, a plasma display panel (PDP) device, and a field emission display (FED) device. ) Devices and the like.

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

The flexible display can be folded or bent and has a merit of implementing a thin display, but measures for damage due to external impact and peeling of structures or interlayers are required.

For example, the window substrate or window film laminate applied to the flexible display needs to secure mechanical reliability such as durability under harsh environments such as low temperature, high temperature, and high humidity, with consideration of bending characteristics and thinning.

In addition, when other structures or members are bonded to the window substrate or the window film laminate through an adhesive layer, it is necessary to secure an adhesive force or adhesive force 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 including an acrylic resin and a multifunctional crosslinking agent, but there is a limit to satisfy the physical properties required for a flexible display.

One object of the present invention is to provide a window film having excellent mechanical properties such as excellent pencil hardness and durability even at low temperatures, while ensuring excellent bending characteristics.

Moreover, one subject of this invention is providing the window film excellent in the adhesive force with various base materials, such as a polarizer or a touch sensor film.

Moreover, one subject of this invention is providing the window film laminated body and image display apparatus containing the above-mentioned window film.

1. Hard coating film; And an adhesive layer laminated on one surface of the hard coating film, wherein the storage elastic modulus at −20 ° C. of the adhesive layer is 0.05 to 0.5 MPa.

2. In the above 1, the storage elastic modulus of the pressure-sensitive adhesive layer at -20 ℃ is 0.1 to 0.4MPa, the window film.

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

4. The window film of any one of the above 1-3 and the window film laminate comprising a polarizing plate and a touch sensor film laminated on the adhesive layer side of the window film.

5. In the above 4, the window film, the polarizing plate and the touch sensor film is sequentially laminated, the window film laminate.

6. In the above 4, the window film, the touch sensor film and the polarizing plate is sequentially laminated, the window film laminate.

7. In the above 4, the pencil hardness at -20 ℃ measured on the other side of the one side of the hard coating film is at least H, the window laminate.

8. Image display device including the window film laminate of the above 4.

The window film of the present invention ensures excellent mechanical properties such as pencil hardness and durability even under harsh conditions such as low temperature and has excellent bending characteristics.

Moreover, the window film of this invention is excellent in adhesive force with various base materials, such as a polarizer or a touch sensor film.

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

1 is a schematic diagram illustrating a window film according to embodiments of the present invention.

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, a hard coating film; And a pressure-sensitive adhesive layer laminated on one surface of the hard coat film, wherein the storage elastic modulus at -20 ° C. of the pressure-sensitive adhesive layer is 0.05 to 0.5 MPa, so that mechanical properties such as excellent pencil hardness and durability even under harsh conditions such as low temperature The present invention relates to a window laminate having excellent flexural properties and good adhesion to a substrate while ensuring the stability.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Although the following describes preferred embodiments of the present invention, these embodiments are only illustrative of the present invention and are not intended to limit the scope of the appended claims, and various modifications to the embodiments within the scope and spirit of the present invention. Modifications and variations are apparent to those skilled in the art, and such variations and modifications are naturally within the scope of the appended claims.

On the other hand, in adding reference numerals to the components of each drawing, the same or similar reference numerals may be used for substantially the same components, even if shown on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description may be omitted.

< 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 coat film 10 may be laminated or positioned on another substrate such as a polarizing plate, a touch sensor film, or the viewing side of an image display device, for example. It can be provided as a base material or a film which protects a base material or an image display apparatus.

The hard coat film 10 includes a first surface 10a and a second surface 10b opposed to each other, for example, as shown in FIG. 1, the first surface 10a is located at the outer side or the viewing side. 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 coat film 10 may include, for example, a base film 11 and a hard coat layer 12 stacked on one surface of the base film 11.

The base film 11 may be provided as a base substrate that may be stacked on, for example, the 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 triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propy O'Neill cellulose, polyester, polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, Polymer films such as polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and cycloolefin polymer (COP) It may include. The base film may include a single or two or more of them, and preferably may include a cycloolefin polymer film in terms of satisfying mechanical properties such as durability by satisfying transparency and flexibility while having an appropriate hardness. .

The base film 11 may be a surface treatment such as a plasma treatment, a corona treatment, or the like, for improving adhesion to the hard coating layer 12 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 μm, and preferably 40 to 100 μm. If the thickness of the base film 10 is less than 8㎛ processability may be lowered, if it is more than 1000㎛ transparency may be reduced or the weight of the polarizing plate may be undesired.

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 same, an image display device, and the like.

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

The hard coating layer-forming composition is not particularly limited and may include, for example, a photocurable compound and a photoinitiator.

The photocurable compound may be used without limitation generally used in the art, for example, the photocurable compound may be a photopolymerizable monomer, a photopolymerizable oligomer, and the like, for example, monofunctional and / or polyfunctional (meta ) Acrylate. These can be used individually or in mixture of 2 or more types.

In the present invention, "(meth) acryl-" refers to "methacryl-", "acryl-" or both.

Specific examples of the photopolymerizable monomer include dipentaerythritol penta / hexa (meth) acrylate, pentaerythritol tri / tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, (meth) acrylic ester and trimethylol Propane tri (meth) acrylate, glycerol tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate, tri (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol (meth ) Acrylate, 1,3-butanedioldi (meth) acrylate, 1,4-butanedioldi (meth) acrylate, 1,6-hexanedioldi (meth) acrylate, neopentylglycoldi (meth) acrylate , Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, bis (2-hydroxyethyl) isocyanurate di (meth) a Acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, isooctyl (meth) acrylate, iso-decyl (meth) acrylate, stearyl ( Meth) acrylate, tetrahydroperfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornone (meth) acrylate, and the like. These may be used alone or in combination of two or more thereof.

The photopolymerizable oligomer may be used, for example, at least one selected from the group consisting of epoxy (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate, and specifically, urethane (meth) acryl The rate and polyester (meth) acrylate can be mixed and used, or 2 types of polyester (meth) acrylates can be mixed and used. Preferably urethane (meth) acrylate oligomers 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.

Urethane (meth) acrylates can be prepared by reacting a polyfunctional (meth) acrylate having a hydroxyl group in a molecule with a compound having an isocyanate group in the presence of a catalyst according to methods known in the art.

Specific examples of the urethane (meth) acrylate oligomers include the reaction of 2-hydroxyethyl (meth) acrylate and 2,4-tolylene diisocyanate, of 2-hydroxyethyl (meth) acrylate and isophorone diisocyanate. Reaction, reaction of 2-hydroxybutyl (meth) acrylate and 2,4-tolylene diisocyanate, reaction of 2-hydroxybutyl (meth) acrylate and isophorone diisocyanate, 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 dicyclohexyl methane diisocyanate, dipentaerythritol penta ( Reaction of meth) acrylate and isophorone diisocyanate, dipentaerythritol penta (meth) acrylate and It may be the product of the reaction of dicyclohexyl methane diisocyanate.

Polyester (meth) acrylates can be prepared by reacting polyester polyols with acrylic acid according to methods known in the art.

Polyester (meth) acrylate is polyester acrylate, polyester diacrylate, polyester tetraacrylate, polyester hexaacrylate, polyester pentaerythritol triacrylate, polyester pentaerythritol tetraacrylate, for example. And, and may be selected from the group consisting of 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. It can be included as a wealth. If it is more than 60 parts by weight may cause cracking problems due to over-cure, if less than 20 parts by weight may not secure the required physical properties such as hardness and hardness in the hard coating layer 12, such as hardness, abrasion resistance due to uncured and flexibility may be reduced There is.

The photoinitiator is used to cure the composition for forming the hard coat layer may be used without limitation as long as it is generally used in the art.

In some embodiments, the photoinitiator may be to generate a cation or Lewis acid by irradiation of active energy rays such as visible light, ultraviolet light, X-rays or electron beams to initiate polymerization of the hard coating composition. Because of the catalytic action, there are aspects that are excellent in storage stability and workability even when mixed with the composition for forming a hard coat layer.

The photoinitiator may be used at least one selected from the group consisting of hydroxy ketones, amino ketones, and hydrogen decyclic photoinitiator.

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 Phosphinate, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinepropanone-1, diphenylketonebenzyldimethylketal, 2-hydroxy-2-methyl-1-phenyl-1 -One, 4-hydroxycyclophenylketone, dimethoxy-2-phenylatetophenone, anthraquinone, fluorene, triphenylamine, carbazole, 3-methylacetophenone, 4-knoloacetophenone, 4,4 At least one selected from the group consisting of dimethoxyacetophenone, 4,4-diaminobenzophenone, 1-hydroxycyclohexylphenyl ketone, benzophenone, and the like can be used, and as a commercially available product, IRGACURE 184 (manufactured by CIBA) Etc. can be used.

Although the content of the photoinitiator is not limited, the composition for forming the hard coating layer is preferably 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 coating layer. If the content exceeds 10 parts by weight, cracks may occur due to over curing.

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 during the curing process after forming the hard coating layer, it is preferable to use when diluting the prepared composition for forming a hard coating layer.

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

Examples of the solvent include alcohols (methanol, ethanol, isopropanol, butanol, methylcellulose, ethyl solusorb, etc.), ketones (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, Cyclohexanone, etc.), hexane-based (hexane, heptane, octane, etc.), benzene-based (benzene, toluene, xylene, etc.), ether-based (propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc.) may be used. have. The solvents exemplified above may be used alone or in combination of two or more.

The hard coating layer-forming composition may be added in an amount of 0.1 to 85 parts by weight based on 100 parts by weight of the hard coating layer-forming composition. If the content is less than 0.1 parts by weight, the composition may have a high viscosity, which may lower workability. If the content is more than 85 parts by weight, the curing process may take a lot of time and may be economically inferior.

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

The type of the inorganic nanoparticles is not particularly limited, but for example, Al ₂ O ₃ , SiO ₂ , ZnO, ZrO ₂ , BaTiO ₃ , TiO ₂ , Ta ₂ O ₅ , Ti ₃ O ₅ , indium-tin-oxide (ITO), indium-zinc-oxide (IZO), antimony-tin-oxide (ATO), ZnO-Al, Nb ₂ O ₃ , SnO, MgO or a combination of metal oxides. In one embodiment, Al ₂ O ₃ , SiO ₂ and / or ZrO ₂ may be used as the inorganic nanoparticles.

In one embodiment, the hard coating layer-forming composition or hard coating layer 12 is an antioxidant, UV absorber, light stabilizer generally used in the art within the range that does not reduce the effect of the present invention in addition to the above components. It may further comprise at least one selected from the group consisting of a leveling agent, a surfactant, an antifouling agent.

The coating or coating of the composition for forming the hard coating layer is a slit coating method, knife coating method, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method Method, spray coating method, screen printing method, gravure printing method, flexographic printing method, offset printing method, inkjet coating method, dispenser printing method, nozzle coating method, capillary coating method and the like.

After applying the composition for forming the hard coat layer, the volatiles are dried by evaporation at a temperature of 30 to 150 ° C. for 10 seconds to 90 minutes, more preferably for 30 seconds to 70 minutes. After curing by irradiation with UV light. It is preferable that it is about 0.01-10J / cm <2>, and, as for the irradiation amount of the said UV light, it is more preferable that it is 0.1-2J / cm <2>.

The thickness of the hard coat layer 12 is not particularly limited, and may be, for example, 3 to 15 μm. When included in the above range, it is preferable to implement a surface treatment film for a polarizing plate having an excellent hardness and antireflection effect at the same time.

The adhesive layer 20 is a layer formed for bonding or laminating the hard coat film 10 to another substrate such as the polarizing plate 30 and the touch sensor film 40, and is laminated on one surface of the hard coat film 10. For example, as shown in FIG. 1, it is laminated on the second surface 10b of the hard coat film 10. In addition, as shown in FIG. 1, the adhesive layer 20 may be stacked on one surface of the base film 11 on which the hard coating layer 12 is stacked.

The storage modulus at −20 ° C. of the pressure-sensitive adhesive layer 20 according to the present invention is 0.05 to 0.5 MPa.

The window film is required to have a bending property suitable for a flexible device while being durable to withstand external physical and chemical impacts by being laminated, bonded or positioned on an image display device including the same, particularly a film such as a window film. In the case of the substrate in the form, there is a possibility that deformation, lifting, peeling, cracking, etc. may occur under severe conditions such as low temperature as well as general environment such as room temperature, and thus it is required to reduce it. However, when the adhesive layer for adhesion or adhesion with the window film and other substrates does not satisfy a certain level of elastic modulus or does not satisfy a certain hardness, the surface of the window film is deformed according to various external shocks. There is a risk of inadequate application.

However, the storage elastic modulus at -20 ° C of the pressure-sensitive adhesive layer 20 according to the present invention is 0.05 to 0.5 MPa, so that the adhesion between the hard coating film 10 and other substrates to be bonded can be sufficiently realized, but not only at room temperature but also at low temperature. Even in harsh environments, surface deformation, lifting, and peeling of the hard coat film 10 due to external impact can be effectively prevented. If the storage elastic modulus at -20 ° C of the adhesive layer 20 is less than 0.05 MPa, the hard coating film 10 cannot withstand the external impact sufficiently because it does not satisfy the hardness required for the adhesive layer 20 and is not suitable for application of the device. In the case of more than 0.5 MPa, the bending property or flexibility required for the flexible device is not preferable.

In one embodiment, the storage elastic modulus of the pressure-sensitive adhesive layer 20 at -20 ° C may be 0.1 to 0.4, it is preferable in terms of preventing the surface deformation of the hard coat film 10 and improve the bending characteristics when in the above range. .

In one embodiment, the storage modulus at 20 ° C. of the adhesive layer 20 may be 0.05 to 0.5 MPa. When in the above range, while minimizing the difference with the above-described storage modulus of the low temperature (-20 ℃) while minimizing the deformation of the hard coating film 10 or other substrate bonded to the hard coating film 10 according to the temperature conditions It is more preferable because they can maintain their durability and can have excellent durability. The smaller the difference between the (storage) elastic modulus at 20 ° C. and the storage elastic modulus at −20 ° C. of the adhesive layer 20, the better. Preferably, the storage modulus at 20 ° C. and the storage at −20 ° C. of the adhesive layer 20 are better. The difference in modulus of elasticity may be 0 to 0.2, and is preferable in terms of securing hardness and bending characteristics suitable for a flexible device and minimizing deformation of the hard coat film 10 according to temperature.

In one embodiment, the adhesive layer 20 may be formed by, for example, applying and curing the composition for forming an adhesive layer on the second surface 10b or the base film 11 of the hard coat film 10. The kind of the adhesive layer forming composition is generally used in the art, and there is no particular limitation within the scope not departing from the object of the present invention, for example, to satisfy the above-described storage elastic modulus range of the adhesive layer 20. An adhesive or the composition for adhesion layer formation can be used.

Specifically, the adhesive layer 20 may be a composition for forming an adhesive layer or an optically transparent adhesive including an adhesive copolymer such as (meth) acrylic, silicone, rubber, urethane, polyester, or epoxy copolymers known in the art. Optical Clear Adhesive) may be a coating layer of the composition, and preferably may be a coating layer formed of a composition for forming an adhesive layer including an acrylic copolymer.

The composition for forming a (meth) acrylic copolymer-containing pressure-sensitive adhesive layer 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 further comprising 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 in the art, for example, may be a (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms.

As a (meth) acrylate monomer which has a C1-C12 alkyl group, n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) Acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, pentyl (meth) acrylate, n-octyl (meth) acrylate, Isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, and the like, among which n-butyl acrylate, 2-ethylhexyl acrylate or Mixtures of these are preferred. These can be used individually or in mixture of 2 or more types.

It is preferable that the (meth) acrylate monomer which has a C1-C12 alkyl group is contained by 77-98.9 weight part with respect to 100 weight part of total monomers used for manufacture of a (meth) acrylic-type copolymer. If the content is less than 77 parts by weight, the adhesive force may not be sufficient and release film peeling force enhancement problem may occur, and when the content is more than 98.9 parts by weight, the cohesion may be lowered and the durability may be reduced.

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

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

Specifically, as the monomer having a hydroxy group, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) Acrylate, 6-hydroxyhexyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxypropylene glycol (meth) acrylate, hydroxyalkyl having 2-4 carbon atoms of an alkylene group Lenglycol (meth) acrylate, 4-hydroxybutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 7-hydroxyheptyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9- Hydroxynonyl vinyl ether, 10-hydroxydecyl vinyl ether, etc. are mentioned.

As a monomer which has the said carboxyl group, Monovalent acids, such as (meth) acrylic acid and crotonic acid; Diacids such as maleic acid, itaconic acid and fumaric acid, and monoalkyl esters thereof; 3- (meth) acryloylpropionic acid; Succinic anhydride ring-opening adduct of 2-hydroxyalkyl (meth) acrylate with 2-3 carbon atoms of an alkyl group, Succinic anhydride ring opening adduct of hydroxyalkylene glycol (meth) acrylate with 2-4 carbon atoms of an alkylene group And a compound obtained by ring-opening addition of succinic anhydride to a caprolactone adduct of 2-hydroxyalkyl (meth) acrylate having 2 to 3 carbon atoms of an alkyl group, among which (meth) acrylic acid is preferred.

Examples of the monomer having an amide group include (meth) acrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, 3-hydroxypropyl (meth) acrylamide, 4-hydroxybutyl (meth) acrylamide, 6-hydroxyhexyl (meth) acrylamide, 8-hydroxyoctyl (meth) acrylamide, 2-hydroxyethylhexyl (meth) acrylamide, etc. are mentioned, Among 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) acrylate, and N, N- (dimethylamino) propyl ( Meth) acrylate, etc. are mentioned.

It is preferable that the said crosslinkable monomer is contained in 0.05-10 weight part with respect to 100 weight part of (meth) acrylic-type copolymers, More preferably, it is 1-8 weight part. If the content is within the above range, the cohesion and durability of the pressure-sensitive adhesive is excellent.

In addition, in addition to the monomers, other polymerizable monomers known in the art may be further included in a range that does not lower the adhesion, such as 10 parts by weight or less.

The method for preparing the (meth) acrylic copolymer is not particularly limited, and may be prepared using methods such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization, which are commonly used in the art, and solution polymerization is preferable. . Moreover, the solvent normally used at the time of superposition | polymerization, a polymerization initiator (for example, azobisisobutyronitrile (AIBN) etc.), the chain transfer agent for molecular weight control, etc. can be used.

The (meth) acrylic copolymer has a weight average molecular weight (polystyrene equivalent, Mw) measured by gel permeation chromatography (GPC) of 500,000 to 1.7 million, more preferably 800,000 to 1.5 million Good in terms of durability and reliability of the layer.

The crosslinking agent may further improve adhesion and durability, and maintain the shape of the adhesive and the reliability at high temperature.

The crosslinking agent of the present invention may specifically include an isocyanate-based crosslinking agent in terms of durability improvement, and has excellent compatibility with the (meth) acrylic copolymer and is preferable in view of further improving durability and reliability of the formed adhesive layer. Do.

As isocyanate type crosslinking agent, tolylene diisocyanate, xylene diisocyanate, 2, 4- diphenyl methane diisocyanate, 4, 4- diphenyl methane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethyl xylene diisocyanate Diisocyanate compounds such as naphthalene diisocyanate; Diisocyanate obtained from 2 equivalents of an adduct obtained by reacting 3 equivalents of a diisocyanate compound with 1 equivalent of a polyhydric alcohol compound such as trimethylolpropane, an isocyanurate having 3 equivalents of a diisocyanate compound, and 3 equivalents of a diisocyanate compound Polyfunctional isocyanate compound containing three functional groups, such as a biuret body, triphenylmethane triisocyanate, and methylene bistriisocyanate which the remaining 1 equivalent of diisocyanate condensed in urea; And the like, but is not limited thereto.

The content of the crosslinking agent is not particularly limited within the range capable of performing its function, for example, may be included in 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 may be reduced due to insufficient crosslinking degree, thereby impairing the adhesive durability and the cutting property. If the content is more than 10 parts by weight, problems may occur in relieving residual stress due to an excessive crosslinking reaction.

In addition to the isocyanate-based crosslinking agent, the crosslinking agent may further include a crosslinking agent known in the art. For example, epoxy, metal chelate, polyfunctional acrylate, oxazoline, and the like may be used without limitation. It can be used in combination of more than one species.

Further, in addition to the isocyanate-based crosslinking agent, melamine derivatives such as hexamethyrolmelamine, hexamethoxymethylmelamine, hexabutoxymethylmelamine and the like; Polyepoxy compounds such as bisphenol A and epichlorohydrin condensate epoxy compounds; One or more crosslinking agents selected from the group consisting of polyglycidyl ethers of polyoxyalkylene polyols, glycerin di- or triglycidyl ethers, tetraglycidyl xylenediamine and the like can be further added and used together.

In one embodiment, the composition for forming the pressure-sensitive adhesive layer may further include a silane coupling agent as necessary.

The kind of the silane coupling agent is not particularly limited, and for example, vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxy Propyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-metha Krilloxypropyl triethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyl diethoxysilane, 3-acryloxypropyl trimethoxysilane , N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyl Methyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyl Dimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatepropyltriethoxysilane, substituted acetamide group-containing silanes, and the like. In order to satisfy workability simultaneously, it is preferable to use the substituted acetamide group containing silane. These can be used individually or in mixture of 2 or more types.

The silane coupling agent may be included in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the copolymer, and preferably 0.1 to 2 parts by weight. If the content is more than 10 parts by weight, durability may be reduced.

In addition, the composition for forming the pressure-sensitive adhesive layer is a tackifying resin, antioxidant, corrosion inhibitor, antistatic agent, leveling agent, surface lubricant, in order to control the adhesion, cohesion, viscosity, elastic modulus, glass transition temperature, etc. Additives, such as an antifoamer, a filler, a light stabilizer, a reaction initiator, and a solvent, can be further contained.

In addition, the composition for forming an adhesive layer may further include a curing agent, a photoinitiator, a coupling agent and the like.

 The said hardening | curing agent is bifunctional (meth) acrylate, such as hexanediol diacrylate, as polyfunctional (meth) acrylate; Trifunctional (meth) acrylate of trimethylolpropane tri (meth) acrylate; Tetrafunctional (meth) acrylates such as pentaerythritol tetra (meth) acrylate; 5-functional (meth) acrylates, such as dipentaerythritol penta (meth) acrylate; Six functional (meth) acrylates, such as dipentaerythritol hexa (meth) acrylate, may be included, but is not limited thereto.

The photoinitiator promotes internal and surface hardening of the pressure-sensitive adhesive or pressure-sensitive adhesive layer-forming composition, and is not particularly limited as long as it is known in the art. For example, thioxanthone, phosphorus, triazine, acetophenone, One or more of benzophenone, benzoin, and oxime may be used, and specifically, may be azobisisobutyronitrile (AIBN).

The curing method is not particularly limited, but may include photocuring using ultraviolet light.

The method of applying the composition for forming an adhesive layer is not particularly limited as long as it is a method known in the art, for example, a bar coater, an air knife, gravure, a reverse roll, a kiss roll, a spray, a blade, a die coater, casting, and spin coating. And the like can be used.

In order to satisfy the storage elastic modulus range of the adhesive layer 20 described above, it may be made by appropriately configuring various components or compositions thereof that may be included in the adhesive layer 20. For example, the composition of the photoinitiator, copolymer, etc. included in the pressure-sensitive adhesive layer forming composition, the molecular weight, or adjust the amount of light irradiation, or various components contained in the pressure-sensitive adhesive layer-forming composition, for example a crosslinking agent By changing suitably, the storage elastic modulus range of the adhesion layer 20 of this invention can be satisfy | filled.

The thickness of the adhesive layer 20 is not particularly limited, and specifically, may be 10 to 100 μm. In the above range, it is preferable to implement a thin film device and to secure the hardness, flexibility, and protection against external impact of the hard coat film 10.

< window  film Laminate  And image display device>

2 and 3 are schematic views for explaining the window film laminate according to the embodiments.

2 and 3, the present invention provides a window film laminate including the above-described window film.

The window film laminate according to the embodiments of the present invention may include the above-described window film, the polarizing plate 30, the touch sensor film 40, specifically, the window film, the adhesive layer 20 of the window film It may include a polarizing plate 30 and a touch sensor film 40 stacked on the side.

The window film laminate may include the above-described window film, and for example, the window film may be located at the viewer-side outermost layer of the window film laminate. Accordingly, due to the effects of excellent surface deformation prevention characteristics and bending characteristics of the window film according to the present invention, it is possible to implement very desirable performance such as durability and bending characteristics in the window film laminate.

Specifically, referring to FIG. 2, in the window film laminate according to the exemplary embodiment, the window film, the polarizing plate, and the touch sensor film are sequentially stacked.

For example, as illustrated in FIG. 2, the polarizing plate 30 may be laminated on the other 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 flexible device applications. Specifically, the window film according to the present invention is due to the above-described storage elastic modulus range of the adhesive layer 20 and the pencil hardness range at −20 ° C. measured on the first surface 10a of the hard coat film 10. Since the durability and the bending property of the laminate can be optimally defined, the bending property required for the polarizing plate or the image display device including the same can be satisfied while being effective in preventing surface deformation.

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

The polarizing plate 30 may be obtained by swelling, dyeing, crosslinking, stretching, washing, and drying a film for forming a polarizer which is commonly used in the art.

The polarizing plate 30 according to the present invention may be a polarizer commonly used in the art manufactured according to a process including the steps of swelling, dyeing, crosslinking, stretching, washing, drying, and the like for forming a polarizer film.

The polarizer-forming film is not particularly limited as long as it is a dichroic substance, that is, a film that can be dyed with iodine. For example, a polyvinyl alcohol film, a polyvinyl alcohol film dehydrated, a polyvinyl alcohol film treated with dehydrochloric acid , Polyethylene terephthalate film, ethylene-vinyl acetate copolymer film, ethylene-vinyl alcohol copolymer film, cellulose film, partially saponified film thereof, and the like. Among them, polyvinyl alcohol-based films are preferred in that they are excellent in effect of enhancing uniformity in polarization degree and excellent in dyeing affinity for iodine.

The polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetate-based resin. As polyvinyl acetate type resin, besides polyvinyl acetate which is a homopolymer of vinyl acetate, the copolymer etc. of vinyl acetate and the other monomer copolymerizable with this are mentioned.

Other monomers copolymerized to vinyl acetate are generally used in the art and are not limited so long as they do not depart from the object of the present invention. Specifically, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and the like are used. For example.

The polyvinyl alcohol-based resin may be a modified one, and specific examples thereof include polyvinyl formal and polyvinyl acetal modified with aldehydes.

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

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

The protective film is not particularly limited as long as it is a plastic film having transparency, and is preferably excellent in mechanical strength, thermal stability, moisture shielding, isotropy, etc. with transparency.

Specific examples of the protective film may include polyester-based films such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate; Cellulose films such as diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose, propionyl cellulose, butyryl cellulose and acetyl propionyl cellulose; Polycarbonate film; Acrylic films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene films such as polystyrene and acrylonitrile-styrene copolymers; Polyolefin-based films such as polyethylene, polypropylene, cyclo- or polyolefin-based films having a norbornene structure, and ethylene propylene copolymers; Ethylene-vinyl acetate copolymer film; Polyamide film; Polyimide, polyetherimide film; Polyether sulfone-based film; Sulfone film; Polyvinyl chloride, polyvinylidene chloride films; Polyvinyl alcohol, polyvinyl acetal film; Polyether ketone, polyether ether ketone film; Polyurethane, an epoxy film, etc. are mentioned. These can use an unstretched, uniaxial or biaxially oriented film. Among them, uniaxial or biaxially stretched polyester film, polymethyl methacrylate film or polycycloolefin-based film having excellent transparency and heat resistance, but triacetyl cellulose and isobutyl ester cellulose film in view of transparency and optical anisotropy desirable.

It may be 20 to 100㎛ of the protective film. The thickness of the protective film is preferably thin, but if too thin, the strength is lowered and workability is lowered. If the thickness is too thick, transparency is reduced 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 polarizing plate 30.

For example, the window film laminate may further include a touch sensor film 40 known in the art. As illustrated in FIG. 2, the image display apparatus according to the exemplary embodiment may include the touch sensor film 40 stacked on the other surface of the polarizing plate 30 on which the aforementioned window film is stacked. The touch sensor film 40 may be used generally used in the art, for example, may include triacetyl cellulose (TAC).

The above-described touch sensor film 40 and the polarizing plate 30 are separate adhesive layers (not shown), for example, an adhesive layer (not shown) formed through a pressure sensitive adhesive (PSA) known in the art. Can be adhered to.

The polarizing plate 30 and the touch sensor film 40 are effectively protected from external impact due to the window film described above. The aforementioned window film prevents surface deformation and has excellent bending characteristics even under severe conditions such as low temperature, so that the window film laminate according to the present invention can be effectively protected not only at room temperature but also at low temperature, and thus implemented as a flexible image display device. 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, in the window film laminate, the window film, the touch sensor film 40, and the polarizing plate 30 are sequentially stacked. Compared to FIG. 2, the image display device of the exemplary embodiment illustrated in FIG. 3 differs in that the stacking order of the polarizing plate 30 and the touch sensor film 40 is different. For example, the window film laminate according to an embodiment may further include a polarizing plate 30 laminated on the other surface of the touch sensor film 40 on which the window film is stacked.

The material, composition, and adhesion method of the polarizing plate 30 and the touch sensor film 40 are the same as or similar to the material, composition, and adhesion method of the polarizing plate 30 and the touch sensor film 40 described above, and thus the window The film laminate is preferable to be implemented as a flexible image display device due to the effect of protecting the window film from external impact, preventing surface deformation under severe conditions such as low temperature, and excellent bending characteristics.

In the case of the window film laminate of the present invention, the pencil hardness at −20 ° C. measured on the other side of the one surface of the hard coat film 10 (for example, the first surface 10a) is not less than H. . If the pencil hardness is less than H, there is a lack of durability of the hard coating film 10 or the window laminate, there is a risk of scratches, cracks and the like. In the window film laminate of the present invention, since the adhesive layer 20 satisfies the above-described storage modulus range, surface deformation to the hard coat film 10 due to external impact can be effectively prevented, and at the same time, the window film laminate Durability and flexural properties are simultaneously implemented and are very suitable for application of an image display device comprising the same, more preferably a flexible image display device, preferably, -20 measured on the other side of the opposite side of the hard coat film 10 Pencil hardness at ℃ may be H to 3H, in this case it is preferable in terms of improving the durability and securing bending characteristics of the window film laminate.

Moreover, this invention provides the image display apparatus containing the window film or window film laminated body mentioned above.

For example, the image display device may position, stack, or arrange the window film or the window film laminate on the viewer's outermost side of the image display device, thereby having a strong durability against external impact, Surface deformation can be prevented even under severe conditions, and bending characteristics are also excellent.

The image display device of the present invention may further include a configuration known in the art in addition to the above-described configuration.

Hereinafter, the present invention will be described in detail with reference to Examples. These examples are merely illustrative of the present invention and are not intended to limit the appended claims, it will be apparent to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and spirit of the invention. It is natural that such variations and modifications fall within the scope of the appended claims.

Production Example

(One) ( Meta Production of Acrylic Copolymer (A)

Nitrogen gas was refluxed, and a monomer mixture consisting 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 for easy temperature control, followed by ethyl as a solvent. 400 parts by weight of acetate was added. Nitrogen gas was then purged for 1 hour to remove oxygen and then held at 62 ° C. After uniformly mixing the mixture, 0.07 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and reacted for about 8 hours to react with a weight average molecular weight of about 1.5 million (meth) acrylic copolymer (A-1). Was prepared.

In addition, the (meth) acrylic copolymer was prepared according to the above method, but the content of n-butyl acrylate and 4-hydroxybutyl acrylate and reaction time were adjusted to adjust the content of A-2 to A-9 as shown in Table 1 below. A (meth) acrylic copolymer was prepared.

(2) Adhesive layer  Preparation of Forming Composition

The components of Table 2 were prepared by mixing the components of Table 2 below.

Example

Example 1: Preparation of Window Film and Window Film Laminate

(1) Preparation of a composition for forming a hard coat layer

3-glycidoxypropyltrimethoxysilane and water were mixed in 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 siloxane sol was prepared by adding 0.05 mL of ammonia as a catalyst to the mixture and stirring at 60 ° C. for 6 hours.

The siloxane sol and diglycidyl ether are mixed in a weight ratio of 100: 10, and 2 parts by weight of a triarylsulfonium hexafluoroantimonate salt is mixed with respect to 100 parts by weight of the mixture to form a hard coat layer. Was prepared.

(2) production of window film

The hard coating layer-forming composition was coated with a thickness of 10 μm on a COP film having a size of 179.1 mm × 105.8 mm and a thickness of 80 μm surface treated by corona to form a hard coating layer. The hard coating layer was exposed to a mercury UV (Ultra Violet) lamp (20 mW / cm ² ) for 5 minutes by applying the coating composition for forming a hard coating layer to initiate a reaction by the triarylsulfonium hexafluoro antimonate salt It was formed by conducting moisture heat treatment for 60 minutes under 50 ° C. and 50% relative humidity conditions.

Thereafter, the pressure-sensitive adhesive layer-forming composition of Preparation Example 1 was coated to have a thickness of 50 μm on one side of the COP film, and then dried in a drying furnace. Thereafter, by irradiating at a rate of 23 m / min using an ultraviolet irradiator, the coating was cured and dried at 100 ° C. for 1 minute to form an adhesive layer, thereby preparing the window film of Example 1.

(3) measurement of storage modulus

The storage modulus at −20 ° C. of the prepared adhesive layer was measured using a rheometer (manufacturer: Anton Paar, model name: MCR-301), and the results are shown in Table 2 below.

(4) Manufacture of window film laminate

Size 164.89 mm × 104.8 mm, TAC (triacetylcellulose) touch sensor film (first substrate) having a thickness of 164.89 mm × 104.8 mm, thickness of 30 μm on a glass substrate (manufactured by JMC Glass Co., Ltd.) of 300 mm × 300 mm size, size of 164.89 mm as a polarizer. By laminating a polyvinyl alcohol polarizer (second base material) having a thickness of 104.8 mm and a thickness of 38 μm (second base material) in sequence using a pressure-sensitive adhesive, by removing the remaining release film of the pressure-sensitive adhesive layer of the window film and attaching it on the second base A window film laminate (see FIG. 2) having a structure of a glass substrate-first substrate-second substrate-adhesive layer-hard coating layer-substrate film was prepared.

(5) Low temperature (-20 ℃) pencil hardness measurement

Pencil hardness was measured on the upper surface (first surface, 10a of FIG. 2) of the hard coat film of the window film laminated body of an Example and a comparative example. Pencil hardness was measured at -20 ℃ using an evaluation device manufactured by Pencil Hardness Tester in accordance with JIS K 5400, 5600 standards. Pencils range from 6B to 6H hardness of the hardness assurance pencils manufactured by Mitsubishi. Was used. When measuring, move to the coating direction and perform 3 lot evaluation with 1 lot 5 times. First, observe pressing or scratching with the naked eye. If pressing or scratch occurs more than 3 times in 5 times, treat it as fail. What occurred until was determined to be OK. If it was not visually determined, the light leakage was observed using a loupe or by using a backlight.

Examples 2-6 and Comparative Examples 1-5

The window films or the window film laminates of Examples 2 to 6 and Comparative Examples 1 to 5 were manufactured in the same constitution and method as in Example 1, except that the composition for forming an adhesive layer was changed and the first and second substrates were different. Prepared.

Each window film was divided into Examples or Comparative Examples by measuring the storage elastic modulus at −20 ° C. of the pressure-sensitive adhesive layer in the same manner as in Example 1, and subjected to low temperature pencil hardness of the window film laminate of each Example or Comparative Example. Measurement was carried out in the same manner as in Example 1, and the results are shown in Table 3 below.

Experimental Example: Evaluation of Flexural Characteristics

A sample was prepared by cutting the window film laminate according to Examples and Comparative Examples to a size of 10 mm × 100 mm. The hard coating film was inserted into the bending property evaluation device (manufactured by Kobotech Co., Ltd.), and both ends of the sample were fixed with double-sided tape. Thereafter, the radius of curvature of the machine was fixed to 3R, and folded 10,000 times at a speed of 30 times per minute, and the flexural properties were evaluated according to the following evaluation criteria and are shown in Table 3 above.

○: No crack or break even after 10,000 folding

Ⅹ: Crack and break after less than 10,000 folding

Referring to Table 3, it can be seen that the window film or the window film laminate of the embodiments having a storage modulus at −20 ° C. may be excellent in pencil hardness, but also has excellent bending characteristics. However, it has been found that the window film or the window film laminate of the comparative examples is difficult to apply to an image display device because cracks and fractures occur in the evaluation of bending characteristics.

[Description of the code]

10: hard coating film 10a: first side

10b: 2nd side 11: base film

12: hard coating layer 20: adhesive layer

30: polarizing plate 40: touch sensor film

Claims (8)

1. Hard coating film; And

   It includes an adhesive layer laminated on one surface of the hard coating film,

   The storage elastic modulus at -20 ° C of the adhesive layer is 0.05 to 0.5 MPa, the window film.
2. The window film according to claim 1, wherein the storage modulus at −20 ° C. of the adhesive layer is 0.1 to 0.4 MPa.
3. The method of claim 1, wherein the hard coating film comprises a base film and a hard coating layer laminated on the base film,

   The adhesive layer is laminated on one side of the base film, a window film.
4. The window film laminated body containing the window film of any one of Claims 1-3, and a polarizing plate and a touch sensor film laminated | stacked on the adhesion layer side of the window film.
5. The window film laminate according to claim 4, wherein the window film, the polarizing plate, and the touch sensor film are sequentially stacked.
6. The window film laminate according to claim 4, wherein the window film, the touch sensor film, and the polarizing plate are sequentially stacked.
7. 5. The window laminate of claim 4, wherein the pencil hardness at −20 ° C. measured on the other surface opposite the one surface of the hard coat film is H or higher.
8. An image display device comprising the window film laminate of claim 4.

Images