KR20180099207A - Window substrate and image display apparatus including the same - Google Patents

Abstract

Embodiments of the present invention relate to a window substrate, and more specifically, relate to a window substrate which includes: a base film; an optical film laminated on the base film; and an adhesive layer laminated between the base film and the optical film, and having the immersion adhesion of 5 N or higher. The optical film can be combined to the base film through the adhesive layer. The peeling, cracking, etc. of the adhesive layer and/or the optical film can be prevented when the stress such as bending, folding, and the like is applied at a high humidity environment. Defects can be prevented due to the generation of bubbles.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a window substrate,

The present invention relates to a window substrate and an image display apparatus including the same. More particularly, the present invention relates to a window substrate in which a plurality of layers are stacked, and an image display apparatus including the same.

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 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 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, the window substrate or window film laminate to be applied to the flexible display requires consideration of bending property and thinning, and it is necessary to secure mechanical reliability under severe environments such as high temperature and high humidity conditions.

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 substrate having improved mechanical reliability and flexible characteristics.

It is also an object of the present invention to provide an image display apparatus including a window substrate having improved mechanical reliability and flexible characteristics.

1. Base film; An optical film laminated on the base film; And a pressure-sensitive adhesive layer laminated between the base film and the optical film, the pressure-sensitive adhesive layer having a submerged adhesive strength of 5N or more.

2. The window substrate according to 1 above, wherein the adhesive layer has a flooding adhesive strength of 10 N or more.

3. The window substrate according to item 1 above, wherein the adhesive strength at room temperature of the adhesive layer is 15 N or more.

4. The window substrate according to 3 above, wherein the difference between the normal-temperature cohesive force and the submerged cohesive force of the pressure-sensitive adhesive layer is 10 N or less.

5. The window substrate according to 3 above, wherein the difference between the normal-temperature cohesive force and the submerged cohesive force of the pressure-sensitive adhesive layer is 5N or less.

6. The window substrate according to 1 above, wherein the adhesive layer has a shear adhesive strength of 50 to 500 N.

7. The window substrate of claim 1, wherein the base film includes one surface and the other surface, the optical film is stacked on the one surface, and the other surface is disposed on the viewer side.

8. The window substrate of claim 7, wherein the optical film comprises at least one of a polarizing layer or a touch sensor layer.

9. The window substrate of claim 7, wherein the optical film comprises a polarizing layer and a touch sensor layer.

10. The window substrate according to claim 9, wherein the polarizing layer and the touch sensor layer are sequentially disposed from the one surface of the base film.

11. The window substrate according to claim 9, wherein the touch sensor layer and the polarizing layer are sequentially disposed from the one surface of the base film.

12. The window substrate of claim 9, further comprising an additional adhesive layer formed between the polarizing layer and the touch sensor layer.

13. The window substrate according to 12 above, wherein the additional adhesive layer has a flooding adhesive strength of 5N or more.

14. The window substrate of claim 1, wherein the base film is a window film.

15. An image display apparatus comprising any one of the window substrates 1 to 14 above.

16. The image display device of claim 15, wherein the base film of the window substrate comprises a flexible resin, and is provided as a flexible display device.

The window substrate according to embodiments of the present invention includes a pressure-sensitive adhesive layer that satisfies predetermined immersion pressure, and the optical film may be bonded to the base film or the window film through the pressure-sensitive adhesive layer. Therefore, peeling, cracking, etc. of the adhesive layer and / or the optical film are prevented even when stress such as bending or folding is applied in a high humidity environment, and defects due to bubble formation can be prevented.

In addition, the adhesive layer has a predetermined room temperature adhesive force and is combined with the immersion adhesive force, so that a certain level of durability can be maintained in a comprehensive environment such as high temperature, low temperature, and high humidity.

The base film is combined with the optical film and provided as a window substrate, and the polarizing characteristic is maintained in a harsh environment by the adhesive layer, so that excellent optical characteristics can be realized. In addition, the window substrate may include a touch sensor layer, and the electrical characteristics of the touch sensor may be maintained in a harsh environment by the adhesive layer.

The window substrate may be coupled to the flexible display device to improve the adhesion between the structures and to provide a highly reliable image display device capable of maintaining flexibility even in a harsh environment.

1 is a schematic cross-sectional view illustrating a window substrate according to some embodiments of the present invention.
2 is a schematic cross-sectional view illustrating a window substrate according to some embodiments of the present invention.
3 is a schematic cross-sectional view illustrating a window substrate according to some embodiments of the present invention.

Embodiments of the present invention relate to a window substrate, and more particularly to a base film. An optical film laminated on the base film; And a pressure sensitive adhesive layer laminated between the base film and the optical film and having a water immersion adhesive strength of 5 N or more. The optical film can be bonded to the base film through the pressure sensitive adhesive layer, and stress such as bending and folding in a high humidity environment The optical film is prevented from being peeled, cracked, and the like, and the defects due to the generation of bubbles can be prevented.

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.

<Window substrate>

Figures 1 to 3 are schematic cross-sectional views illustrating a window substrate according to embodiments of the present invention. The window substrate can be applied, for example, as a window substrate or an optical laminate of an image display device such as a flexible display. For example, Figs. 1 to 3 show a window substrate in which an optical film is laminated on an adhesive layer.

Referring to FIG. 1, the window substrate includes a base film 100, an adhesive layer 110, and an optical film 120.

The base film 100 may be provided as a window film in the window substrate. The base film 100 may be made of, for example, a material having durability against external impact and transparency that the user can visually recognize, for example, applied to an LCD device, an OLED device, a touch screen panel (TSP) In addition, the base film 100 may include a plastic material having a predetermined flexibility. In this case, the image display device to which the window substrate is applied may be provided as a flexible display device.

For example, the base film 100 may include at least one selected from the group consisting of polyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethyelenenaphthalate (PEN) (PET), polyethyelene terepthalate (PET), polyphenylene sulfide (PPS), polyallylate, polyimide, polycarbonate, cellulose triacetate (TAC), cellulose acetate pro Cellulose acetate propionate (CAP), and the like. These may be used alone or in combination of two or more.

As shown in FIG. 1, the base film 100 includes a first surface 100b and a second surface 100a which are opposed to each other. For example, the first surface 100b and the second surface 100a may correspond to the upper surface and the lower surface of the base film 100, respectively.

The other surface 100a of the base film 100 may be disposed on the viewer's side when the window substrate is applied to an image display apparatus. For example, an image is implemented to the user on the side of the other side 100a of the base film 100, and a command of the user (for example, via a touch) can be input. One surface 100b of the base film 100 faces, for example, a display panel, and additional films and / or structures of the window substrate may be stacked or arranged on one surface 100b. 1 to 3, an optical film 120, for example, a polarizing layer 121 and / or a touch sensor layer 123 is formed on one surface 100b of the base film 100, The optical film 120 may be disposed between the first and second substrates.

In some embodiments, a light shielding pattern may be further disposed on the periphery of one surface 100b of the base film 100. [ The light shielding pattern may be provided, for example, on the window substrate or the bezel portion of the image display apparatus.

The thickness of the base film 100 is not particularly limited, and may be about 20 to 200 μm, considering the implementation of a thin flexible display device.

The adhesive layer 110 may be adhered or laminated on one surface 100b of the base film 100. [ For example, the adhesive layer 110 may be formed on substantially the entire one surface 100b of the base film 100. [ The adhesive layer 110 may cover the surface of the light-shielding pattern. For example, the adhesive layer 110 may be laminated or disposed between the base film 100 and the optical film 120. [

The material of the adhesive layer 110 is not particularly limited, but may be selected in consideration of adhesion strength with the base film 100 and the optical film 120, flexural characteristics, and / or flexibility. For example, the adhesive layer 110 may comprise an acrylate-based pressure sensitive adhesive (PSA) material or an optically clear adhesive (OCA) material.

For example, the adhesive layer 110 may be formed from a pressure sensitive adhesive composition known in the art, and in some embodiments, the pressure sensitive adhesive composition may be a (meth) acrylic copolymer, a urethane copolymer, a silicone copolymer, Based copolymers, and the like. Among them, a (meth) acrylic copolymer or a silicone copolymer can be preferably used, and more preferably a (meth) acrylic copolymer can be used. The adhesive layer 110 may be formed by applying the pressure-sensitive adhesive composition on the surface of the base film 100 or the optical film 120, and then curing the adhesive composition.

The silicone-based copolymer-containing pressure-sensitive adhesive composition may contain a silicone-based copolymer of vinyl group-containing organopolysiloxane, organohydrogenpolysiloxane, vinyl group-removed polysiloxane, polydimethylsilicon hydride or a combination thereof and an addition reaction catalyst.

In addition, the silicone-based copolymer-containing pressure-sensitive adhesive composition may further include a tackifier in terms of enhancing durability and maintaining flexibility characteristics such as curling property and bending property while minimizing the possibility of occurrence of defects such as peeling and cracking of the window substrate For example, the tackifier may include vinyl benzyl alcohol, vinyl benzyl amine, vinyl phenyl isocyanate and the like, preferably vinyl benzyl alcohol. The tackifier may be included in the silicone-based copolymer-containing pressure-sensitive adhesive composition in an amount of 0.1 to 15 parts by weight based on 100 parts by weight of the silicone-based copolymer, and preferably 6 to 12 parts by weight.

The content of each component of such a silicone-based copolymer-containing pressure-sensitive adhesive composition can be suitably adjusted to such an extent that the pressure-sensitive adhesive composition can fulfill its role and compatibility.

The addition reaction catalyst may be a platinum group metal selected from the group consisting of platinum, rhodium, ruthenium, palladium, osmium or iridium metals and organometallic compounds thereof, and combinations thereof for promoting the curing reaction have.

The (meth) acrylic copolymer-containing pressure-sensitive adhesive composition may include, for example, a (meth) acrylic copolymer, a crosslinking agent and the like.

In one embodiment, the (meth) acrylic copolymer may be polymerized 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 99.5 parts by weight based on 100 parts by weight of the total monomers used in the production of the (meth) acrylic copolymer. If the content is less than 77 parts by weight, the adhesive strength may not be sufficient and the peeling force may be increased. When the content exceeds 99.5 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.

Examples of the crosslinkable monomer include a monomer having a hydroxyl group, a monomer having a carboxyl group, a monomer having an amide group, and a monomer having a tertiary amine group.

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 (in terms of polystyrene, Mw) of 500,000 to 2,000,000, preferably 500,000-170,000, more preferably 500,000-1,000,000 as measured by Gel Permeation Chromatography Is preferably in the range of 800,000 to 1,700,000 in terms of improving the durability and reliability of the adhesive 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.

The crosslinking agent may be, for example, an isocyanate crosslinking agent.

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 pressure-sensitive adhesive composition may further include 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 pressure-sensitive adhesive composition of the present invention may further contain additives such as a tackifier resin, an antioxidant, a corrosion inhibitor, an antistatic agent, a leveling agent, a surface lubricant, a defoamer, , A filler, a light stabilizer, a reaction initiator, a solvent, and the like.

The pressure-sensitive adhesive composition 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 pressure sensitive adhesive, and the kind thereof is not particularly limited as far as it is well known in the art. Examples thereof include thioxanthone, phosphorus, triazine, acetophenone, benzophenone, , Oxime type, and more specifically, azobisisobutyronitrile (AIBN).

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

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

In some embodiments, the adhesive layer 110 may be surface-treated to improve the adhesion before the base film 100 or the optical film 120 is bonded.

The surface treatment method is not particularly limited, and the surface of the pressure-sensitive adhesive film can be activated by a method such as corona treatment, plasma treatment, ultraviolet irradiation, electron beam irradiation or application of an anchoring agent. In one embodiment, at least one side of the adhesive layer 110 may be corona treated to produce an illuminance.

According to some embodiments, the adhesive layer 110 may be provided in the form of an adhesive sheet in which two base films are adhered to both sides of the adhesive layer 110. For example, after one base film is peeled from the adhesive sheet, the adhesive layer 110 is bonded onto the base film 100, and the remaining one base film is peeled and bonded to the optical film 120 , For example, a window substrate can be manufactured.

Examples of the base film include a polyolefin film, a polyester film, an acrylic film, a styrene film, an amide film, a polyvinyl chloride film, a polyvinylidene chloride film and a polycarbonate film. Powder or the like.

According to embodiments of the present invention, the adhesive layer 110 may have a flooding adhesion of at least about 5N.

As used herein, the term "immersion adhesion" refers to the time when the window substrate with the optical film 120 bonded thereto is cut to a predetermined size (for example, cut to 25 mm x 250 mm) (For example, 180 ^{o at} 300 m / min) measured after immersed in water as a whole.

The window substrate according to the embodiments of the present invention includes the adhesive layer 110 having a flooding adhesive strength of 5N or more so that the curling property, the bending property, and the like of the optical film 120 can be improved without causing defects such as peeling and cracking of the optical film 120 even under severe conditions of high temperature and high humidity. A flexible characteristic such as a characteristic can be maintained. If the immersion adhesive strength is less than about 5N, peeling or cracking of the optical film 120 and / or the base film 100 is caused when external stress such as bending or folding under high humidity conditions is applied and bubbles are generated on the structures, The display quality of the display device can be deteriorated.

According to one embodiment, the flooding adhesive force of the adhesive layer 110 may be about 10 N or more. In this case, the mechanical properties such as durability and the flexible property of the window substrate can be improved even under severe conditions.

In some embodiments, the adhesive force at room temperature of the adhesive layer 110 may be about 15 N or greater.

As used herein, the term "normal temperature cohesive force" means that the window substrate to which the optical film 120 is bonded is cut to a predetermined size (for example, cut to 25 mm x 250 mm) Means a peeling force (for example, 180 ^{o at} 300 m / min) to be measured.

When the room temperature adhesive force is less than about 15 N, peeling and lifting of the optical film 120 may not be sufficiently suppressed when an external shock or an internal temperature increase of the image display device occurs.

In some embodiments, the difference in the normal-temperature cohesion and the flood-cohesion of the adhesive layer 110 may be about 10 N or less, and preferably 5 N or less. When the difference between the normal-temperature cohesive force and the submerged cohesive force exceeds 10 N, for example, when the external environment changes such as humidity, temperature, or the like, the deviation of the peeling force or adhesive force is increased, Can be caused. If the difference between the normal-temperature cohesive force and the submerged cohesive force is maintained at about 5N or less, the uniformity of appearance and physical properties of the window substrate or the image display device can be further improved even with the environmental change.

In one embodiment, the adhesive strength of the adhesive layer 110 may be 50 to 500N.

In the present specification, the term "shear adhesion force" is defined as a load or force at which the adhesive layer 110 is broken when both ends of the adhesive layer 110 are fixed and then pulled in parallel while increasing the tensile force, The length at which the adhesive layer 110 is stretched until a crack, a crack, or the like occurs is defined as a breaking distance.

Since the adhesive layer 110 included in the window substrate according to an exemplary embodiment has a shear adhesive strength of 50 to 500 N, the window substrate may be formed by tensile force or shear force from the outside while ensuring the bending property required for the flexible device. Possible peeling, cracking and cracking can be minimized. When the shear adhesive strength of the adhesive layer 110 is less than 50 N, the strength to withstand an external tensile force may be insufficient. When the shear adhesive strength exceeds 500 N, the adhesive layer 110 may be rigid and insufficient in flexibility. Preferably, the shear adhesive strength of the adhesive layer 110 may be 80 to 300 N in view of simultaneously achieving excellent strength and flexibility of the window substrate.

In order to satisfy the above range of flooding adhesion, room temperature adhesion and shear adhesion, it is possible to achieve by satisfactorily adjusting the composition, molecular weight, composition and the like of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 110 described above.

The thickness of the adhesive layer 110 is not particularly limited, but may be about 10 to 100 占 퐉, preferably 20 to 80 占 퐉, in consideration of the transmittance of the window substrate and the viscoelasticity of the adhesive layer 110. [

The optical film 120 is laminated on the base film 100 and may be laminated on one surface 100b of the base film 100, for example, as shown in Fig. For example, the optical film 120 may be adhered or laminated on the base film 100 via the adhesive layer 110 laminated between the base film 100 and the optical film 120.

According to some embodiments, the optical film 120 may comprise a polarizing layer 121, a touch sensor layer 123, or a combination thereof.

According to one embodiment, the optical film 120 may include a polarizing layer 121 and a touch sensor layer 123 and may include a polarizing layer 121 and a touch sensor layer 123, The polarizing layer 121 and the touch sensor layer 123 may be disposed sequentially from one side 100b of the base film 100. In this case,

The polarizing layer 121 may be a single layer of a polarizer or a laminate in which a transparent protective film is bonded to at least one surface of the polarizer.

The polarizer may be formed from a polymer resin and a polymer resin containing a dichroic substance.

The polymer resin may include, for example, a cycloolefin polymer (COP) and / or a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin is preferably a polyvinyl alcohol-based resin 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 copolymerizable with vinyl acetate include acrylamide monomers having an unsaturated carboxylic acid type, an unsaturated sulfonic acid type, an olefin type, a vinyl ether type, and an ammonium group.

As the transparent protective film, a film superior in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like can be used. For example, polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate and polybutylene terephthalate; Cellulose-based resins such as diacetylcellulose and triacetylcellulose; Polycarbonate resin; Acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene resins such as polystyrene and acrylonitrile-styrene copolymer; Polyolefin resins such as polyethylene, polypropylene, cyclo- or norbornene-structured polyolefins, ethylene-propylene copolymers; Vinyl chloride resin; Amide resins such as nylon and aromatic polyamide; Imide resin; Polyether sulfone type resin; Sulfone based resin; Polyether ether ketone resin; A sulfided polyphenylene resin; Vinyl alcohol-based resin; Vinylidene chloride resins; Vinyl butyral resin; Allylate series resin; Polyoxymethylene type resin; Epoxy resin, and the like, and a film composed of the blend of the thermoplastic resin may also be used. Further, a film made of a thermosetting resin such as (meth) acrylic, urethane, acrylic urethane, epoxy, or silicone or a film made of an ultraviolet curable resin may be used.

In some embodiments, the polarizing layer 121 may be formed of a coating layer of a liquid crystal compound. In addition, the polarizing layer 121 may include a liquid crystal layer containing the liquid crystal compound, and may further include an alignment layer for imparting orientation to the liquid crystal layer.

The thickness of the polarizing layer 121 is not particularly limited, but may be about 20 to 200 占 퐉 in consideration of the flexible characteristics and the mechanical durability of the window substrate.

The touch sensor layer 123 may include electrode patterns for converting the user's touch signal input through the other surface 100a or the bottom surface of the base film 110 into an electrical signal. For example, the electrode pattern may include first sensing electrodes and second sensing electrodes arranged to cross each other.

In addition, the touch sensor layer 123 may further include an insulating layer for insulating the first and second sensing electrodes from each other. In the touch sensor layer 123, peripheral wirings connected to the first and second sensing electrodes may be further formed, and the peripheral wirings may be overlapped with the light shielding pattern.

Referring to FIG. 1, the optical film 120 may further include a touch sensor layer 123 laminated on one side of the polarizing layer 121. The touch sensor layer 123 may be laminated on the polarizing layer 121 through an additional adhesive layer or a second adhesive layer 122. The second adhesive layer 122 may be formed between the polarizing layer 121 and the touch sensor layer 123. Hereinafter, the adhesive layer 110 described in FIG. 1 is referred to as a first adhesive layer.

As shown in FIG. 1, a second adhesive layer 122 may be formed between the touch sensor layer 123 and the polarizing layer 121. The second adhesive layer 122 may comprise a PSA-based material or an OCA-based material substantially identical or similar to the first adhesive layer 110.

In the embodiments of the present invention, the second adhesive layer 122 may also satisfy the immersion adhesion, normal-temperature adhesion, and shear adhesion strength of the above-mentioned adhesive layer.

As described above, the second adhesive layer 122 has a flocculant adhesion strength of about 5N or more, and preferably a flocculant adhesion strength of about 10N or more. In addition, the second adhesive layer 122 may have a room temperature adhesive strength of about 15N or more. The difference between the normal-temperature cohesive force and the flooding-adhesion strength of the second adhesive layer 122 may be about 10 N or less, preferably 5 N or less.

As the second adhesive layer 122 satisfies the adhesive force values in the above range, defects such as cracking and peeling of the touch sensor layer 123 are prevented even in a severe environment of high temperature and high humidity, Can be maintained.

2 is a schematic illustration of a window substrate according to some embodiments of the present invention. 2, the optical film 120 includes a polarizing layer 121 and a touch sensor layer 123. The optical film 120 includes a touch sensor layer 123 and a polarizing layer 121 ) Can be arranged in order.

According to the embodiment shown in Fig. 2, the touch sensor layer 123 can be placed closer to the user's visual or touch input surface. Therefore, the sensitivity of the touch sensing and the signal transmission can be further improved.

The same reference numerals are used for substantially the same configurations as those described with reference to FIG. 1, and the description thereof may be omitted.

An additional adhesive layer or a second adhesive layer 122 may be formed between the touch sensor layer 123 and the polarizing layer 121, as described with reference to FIG.

Figure 3 is a schematic illustration of a window substrate according to some embodiments of the present invention.

Referring to FIG. 3, a protective film 130 may be further formed on the optical film 120. The protective film 130 protects the electrode patterns or the polarizing layer 121 included in the touch sensor layer 123 and may be added to improve optical characteristics such as transmittance of the window substrate or the image display device.

The protective film 130 may be formed of, for example, a cellulose ester (e.g., cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and nitrocellulose), polyimide, polycarbonate, polyester, polyethylene terephthalate , Transparent resin films of polystyrene, polyolefin, polysulfone, polyether sulfone, polyarylate, polyether-imide, polymethyl methacrylate, polyether ketone, polyvinyl alcohol and polyvinyl chloride. The above materials may be used alone or in combination of two or more.

In some embodiments, the protective film 130 may be attached to the optical film 120, for example, the polarizing layer 121 or the touch sensor layer 123 via an adhesive layer, And may be formed of a material satisfying one adhesion parameter.

<Image Display Device>

Embodiments of the present invention provide an image display apparatus including the above-described window substrate.

For example, an image display apparatus can be provided by combining the window substrate described with reference to Figs. 1 to 3 on a display panel. Accordingly, the polarizing plate and / or the touch sensor layer are combined with the image display device so that the optical characteristic and the information display characteristic can be realized together.

The image display device may be a liquid crystal display device, a plasma display panel device, an electro luminescent display device, an organic light-emitting diode display device, and the like.

The mechanical reliability of various members or structures including the polarizing plate and the touch sensor layer is improved by the adhesive layer of the window substrate described above and it is possible to improve the mechanical reliability of the flexible display device without causing mechanical failure more effectively, A thin display in which operations such as bending can be implemented can be implemented.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited by the scope of the appended claims, It will be apparent to those skilled in the art that various changes and modifications can be made in the embodiments within the scope of the claims, and such variations and modifications are within the scope of the appended claims.

Production Example 1: Preparation of (meth) acrylic copolymer

Production Example 1-1: Preparation of (meth) acrylic copolymer (A-1)

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 1,000,000 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. .

Production Example 1-2: Preparation of (meth) acrylic copolymer (A-2)

(meth) acrylic copolymer (A-2) having a weight average molecular weight of about 1,000,000 was prepared in the same manner as in Preparation Example 1, except that 99 parts by weight of n-butyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate were used. Respectively.

Production Example 1-3: Preparation of (meth) acrylic copolymer (A-3)

(Meth) acrylic copolymer (A-3) having a weight average molecular weight of about 500,000 was prepared in the same manner as in Preparation Example 1, except that the reaction time was changed to about 4 hours.

Production Example 2: Preparation of window substrate

(1) Production of pressure-sensitive adhesive composition

The pressure-sensitive adhesive compositions of Examples and Comparative Examples were prepared by mixing the components shown in Table 1 below. For example, Examples 1 to 6 and Comparative Examples 1 and 2 are acrylic copolymer-containing pressure-sensitive adhesive compositions, and Examples 7 and 8 and Comparative Example 3 are silicone-based copolymer-containing pressure-sensitive adhesive compositions.

(2) Production of pressure-sensitive adhesive sheet

The pressure-sensitive adhesive composition of Example or Comparative Example was applied on a releasing film coated with a silicone release agent to a thickness of 50 mu m and dried at 100 DEG C for 1 minute to form an adhesive layer.

(3) Manufacturing of window substrate

A COP (Cyclo olefin polymer) base material having a thickness of 80 占 퐉 was prepared as a polarizing layer, and a PET film having a thickness of 38 占 퐉 was prepared as a base film. Thereafter, the release films of the pressure sensitive adhesive sheet thus prepared were peeled off, and then polarizer-adhesive layer-base film were stacked in this order to prepare window substrate samples.

(4) Measurement of immersion adhesion

The immersion adhesive strength of the adhesive layers included in the samples was measured and classified into Examples and Comparative Examples.

The immersed adhesive force was measured by cutting the window substrate with the polarizer plate cut into 25 mm x 250 mm, immersing the substrate in water at 60 ° C for 4 hours, removing the fixture, fixing a knife between the adhesive layer and the polarizer plate, It was defined as the force measured when a peeling force of 180 ^o was applied at 300 m / min.

Table 1 below shows the constitution of the window substrates of Examples and Comparative Examples.

(5) Measurement of Shear Adhesion

Both ends of the window substrate of the examples and comparative examples were fixed to a UTM autograft. Then, the tensile force and the breaking distance of the adhesive layer were measured by increasing the tensile force at a rate of 1 mm / min, and the maximum stress point and the elastic modulus were measured.

Example Comparative Example One 2 3 4 5 6 7 8 One 2 3 Pressure-sensitive adhesive composition Copolymer
(Parts by weight) A-1 100 100 100 - - - - - - - - A-2 - - - 100 100 100 - - - - - A-3 - - - - - - - - 100 100 - A-4 - - - - - - 100 100 - - 100 A-5 - - - - - - 30 30 - - 30 Cross-linking agent
(Parts by weight) B-1 0.03 - - 0.03 - - - - - - - B-2 - 0.03 - - 0.03 - - - 0.1 - - B-3 - - 0.03 - - 0.03 - - - 0.1 - Addition reaction catalyst
(Parts by weight) C-1 - - - - - - 0.5 0.5 - - 0.5 Tackifier D-1 - - - - - - 10 5 - - - menstruum E-1 400 400 400 400 400 400 - - 400 400 - E-2 - - - - - - 200 200 - - 200 Immersion adhesion (N) 19.28 15.94 13.51 7.59 5.7 5.4 11.4 6.7 4.8 4.2 4.1 Shear adhesion (N) 153 84 95 203 112 254 157 124 115 97 86 Breaking distance (mm) 3.0 2.1 2.2 6.1 3.1 6.5 3.8 3.2 3.2 2.8 2.9 A-1: The acrylic copolymer prepared in Production Example 1
A-2: The acrylic copolymer prepared in Production Example 2
A-3: The acrylic copolymer prepared in Production Example 3
A-4: Vinyl-removed polysiloxane (DMS-V05, manufactured by GELIST)
A-5: Polydimethyl silicone hydride (HMS-H11, manufactured by GELIST)
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)
C-1: Platinum-divinyltetramethyldisiloxane complex
D-1: vinylbenzene alcohol
E-1: Ethyl acetate
E-2: Toluene

Experimental Example 1 Evaluation of Bubbles and Peeling According to Immersion Adhesion

Physical forces were applied to both ends of the window substrate with the bending radius of 3R at 60 DEG C at a bending rate of 30 times per minute on the window substrates according to Examples and Comparative Examples. Thereafter, peeling (or lifting) or bubble generation was evaluated between the respective layers of the window substrates. The evaluation results are shown in Table 2 below.

division Immersion adhesion
(Unit: N) Detachment / removal occurred Bubble occurrence Example 1 19.28 No peeling / peeling after 1 million repetitions No air bubbles Example 2 15.94 No peeling / peeling after 1 million repetitions No air bubbles Example 3 13.51 No peeling / peeling after 1 million repetitions No air bubbles Example 4 7.59 Extremely weak excursion after repeating 10,000 times Slight bubbling Example 5 5.7 Weak eruption after repeating 10,000 times Slight bubbling Example 6 5.4 Weak eruption after repeating 10,000 times Slight bubbling Example 7 11.4 Weak eruption after repeating 10,000 times Slight bubbling Example 8 6.7 Weak eruption after repeating 10,000 times Slight bubbling Comparative Example 1 4.8 Peeling / peeling after 5,000 repetitions A large number of bubbles Comparative Example 2 4.2 Peeling / peeling after 5,000 repetitions A large number of bubbles Comparative Example 3 4.1 Peeling / peeling after 3,000 repetitions A large number of bubbles

Experimental Example 2 Evaluation of Bubble and Peeling According to Adhesion at Room Temperature

Among the above embodiments, the samples (Sample 1 to Sample 3) having the flooding adhesive strength of the window substrates of 5N or more were selected and the room temperature cohesion was measured.

The room temperature adhesive force was measured by cutting and fixing the window substrate having the polarizing plate bonded thereto to 25 mm x 250 mm, placing a knife between the adhesive layer and the polarizing plate, and applying a peeling force of 180 ^o at a measuring speed of 300 m / min using an autograft .

In addition, the difference between the room temperature cohesion and the immersion cohesion strength of the samples of the window substrate was also measured. Thereafter, the occurrence of peeling / bubbling due to bending was evaluated in the same manner as in Experimental Example 1, and the results are shown in Table 3 below.

division Adhesion at room temperature
(Unit: N) Adhesion at room temperature - Immersion adhesion
(Unit: N) Detachment / removal occurred Bubble occurrence Sample 1 23.76 4.48 No peeling / peeling after 1 million repetitions No air bubbles Sample 2 16.82 9.23 Extremely weak excursion after repeating 10,000 times No air bubbles Sample 3 19.92 12.33 Weak eruption after repeating 10,000 times Slight bubbling

Experimental Example 3: Evaluation of Flexural Characteristics

The window substrates of each of the examples and comparative examples were fixed to a U-shape non-load U-shaped folding tester (DLDMLH-FS, manufactured by YUASA SYSTEM) and flexural characteristics were evaluated according to IEC 62715 evaluation standard.

The folding characteristics were evaluated by the following evaluation criteria by carrying out folding 10,000 times under high temperature (60 DEG C, 90% RH) condition or low temperature (-20 DEG C) condition.

○: No defective modes such as bubbles, peeling, cracks were observed in the laminate

DELTA: A minute defective mode was visually visually observed in the laminate.

X: Bad mode clearly visible in the folded part of the laminate

Experimental Example 4: Evaluation of Shear Adhesion and Breaking Distance

Both ends of the window substrate of the examples and comparative examples were fixed to a UTM autograft. Then, the tensile force and the breaking distance of the adhesive layer were measured by pulling in parallel while increasing the tensile force at a rate of 1 mm / min. The maximum stress point and the elastic modulus were measured. The results are shown in Table 4 below.

Example Comparative Example One 2 3 4 5 6 7 8 One 2 3 Bending characteristic High temperature (60 ° C, 90% RH) ○ ○ ○ ○ ○ △ △ △ × × × Low temperature (-20 ℃) ○ ○ ○ △ △ ○ ○ △ × × × Shear adhesion (N) 153 84 95 203 112 254 157 124 115 97 86 Breaking distance (mm) 3.0 2.1 2.2 6.1 3.1 6.5 3.8 3.2 3.2 2.8 2.9 Maximum point stress (kPa) 157 131 150 145 152 179 152 174 143 138 140 Modulus of elasticity (kPa) 2846 2175 2555 3041 2745 3248 2210 2781 2548 2486 2089

Referring to Table 2, it can be seen that, in the embodiments in which the adhesive layer has a flooding adhesive strength of 5N or more, there is no peeling or bubble generation or a slight degree of peeling or bubble generation even after folding 10,000 times in the evaluation of bending properties. However, in the case of the comparative example, peeling / lifting and bubbling occur between the substrates after 50,000 repetitions, which indicates that the flexible characteristics are poor and are not suitable for the application of the device.

Further, referring to Table 3, it can be confirmed that the lower the difference between the normal-temperature cohesive force and the submerged cohesive force of 10 N, the better the bending property.

Further, referring to Table 4, it can be confirmed that Examples 1 to 3, in which both the submerged adhesive force and the shear adhesive strength are in an excellent range, show excellent performance in evaluating bending properties under low temperature and high temperature conditions. In addition, the performance of Examples 4 to 8, in which the submerged adhesive force or shear adhesive strength is slightly lower than those of Examples 1 to 3, is somewhat lower than that of Examples 1 to 3, but it is confirmed that the performance is much better than that of Comparative Examples 1 to 3 .

In addition, referring to Table 4, it can be seen that the window substrate of Examples has a good shear adhesion with a high flexural characteristic, a generally good shear adhesion, and a good maximum point stress and elastic modulus Able to know. In particular, in Examples 1 to 3, it can be seen that the flexural characteristics, the shear adhesive strength, and the fracture distance are excellent. However, it can be seen that the window substrate of the comparative examples is not very good in bending property, generally has a low shear adhesive force, and has a short break distance, which is not as good as the embodiments.

100: base film 110: adhesive layer / first adhesive layer
120: optical film 121: polarizing layer
122: additional adhesive layer / second adhesive layer 123: touch sensor layer
130: protective film

Claims (16)

A base film;
An optical film laminated on the base film; And
And a pressure-sensitive adhesive layer laminated between the base film and the optical film, the pressure-sensitive adhesive layer having a flooding adhesive strength of 5N or more.
The window substrate according to claim 1, wherein the adhesion strength of the adhesive layer is 10N or more.
The window substrate according to claim 1, wherein the adhesive force at room temperature of the adhesive layer is 15 N or more.
The window substrate according to claim 3, wherein a difference between the normal-temperature cohesive force and the submerged cohesive force of the pressure-sensitive adhesive layer is 10N or less.
4. The window substrate according to claim 3, wherein the difference between the normal-temperature cohesive force and the submerged cohesive force of the pressure-sensitive adhesive layer is 5N or less.
The window substrate according to claim 1, wherein the adhesive layer has a shear adhesive strength of 50 to 500 N.
The method of claim 1, wherein the base film comprises a first side and a second side,
Wherein the optical film is laminated on the one surface, and the other surface is disposed on the viewer side.
8. The window substrate of claim 7, wherein the optical film comprises at least one of a polarizing layer or a touch sensor layer.
8. The window substrate of claim 7, wherein the optical film comprises a polarizing layer and a touch sensor layer.
10. The window substrate according to claim 9, wherein the polarizing layer and the touch sensor layer are sequentially arranged from the one surface of the base film.
10. The window substrate according to claim 9, wherein the touch sensor layer and the polarizing layer are sequentially disposed from the one surface of the base film.
The window substrate according to claim 9, further comprising an additional adhesive layer formed between the polarizing layer and the touch sensor layer.
The window substrate according to claim 12, wherein the additional adhesive layer has a flooding adhesive strength of 5N or more.
The window substrate according to claim 1, wherein the base film is a window film.
An image display apparatus comprising the window substrate according to any one of claims 1 to 14.
16. The image display apparatus according to claim 15, wherein the base film of the window substrate comprises a flexible resin and is provided as a flexible display device.

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