KR20180126950A - Hard coating film and image display device using the same - Google Patents

Abstract

The present invention relates to a hard coating film which comprises a cured product of a hard coating composition on at least one surface of a polyimide-based substrate film, is controlled so that the refractive index difference between a substrate film and the cured product of the hard coating composition is at most 0.03, and thus can be applied to a flexible image display apparatus and prevent the occurrence of an interference pattern; and an image display apparatus comprising the hard coating film.

Description

TECHNICAL FIELD [0001] The present invention relates to a hard coating film and an image display device including the hard coating film.

The present invention relates to a hard coating film and an image display device including the same.

Description of the Related Art [0002] In an image display apparatus such as a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display (PDP), an electroluminescent display (ELD) It is required to reduce the reflection by the reflector and to increase the visibility thereof. In this connection, by using an optical laminate (for example, an antireflection laminate) in which an antireflection layer or an antireflection layer is formed on a light-transmitting base material, reflection on the image display surface of the image display device is reduced, Method is generally performed.

However, when the refractive index of the light-transmitting substrate is different from the refractive index of the hard coating layer, interference patterns may occur.

In this regard, Korean Patent Registration No. 10-1063902 discloses a structure for suppressing the generation of interference fringes, which includes a plurality of transparent layers having different refractive indexes, wherein the contact interface between the plurality of transparent layers is a 10- (Rz) of 0.72 μm ≦ Rz ≦ 3.5 μm. However, this method has a problem that the manufacturing process is complicated and the manufacturing time is increased because a plurality of transparent layers must be formed.

Korean Patent Laid-Open Publication No. 10-2013-0117694 discloses a method for suppressing generation of interference fringes as described above, which comprises a base film comprising a (meth) acrylic resin as a main component and a hard coat layer, A common layer in which a material constituting the base film and a material constituting the hard coating layer are used is formed in the vicinity of the interface, but the acrylic resin is vulnerable to flexible characteristics in which repetitive stress is applied , There is a problem that it can not be applied to a flexible image display device which has been recently developed in various fields.

Korean Patent No. 10-1063902 (September 22, 2011) Korean Patent Publication No. 10-2013-0117694 (Oct. 28, 2013)

An object of the present invention is to provide a hard coating film which can be applied to a flexible image display apparatus and can prevent the occurrence of interference fringes and an image display apparatus including the hard coating film.

In order to accomplish the above object, the present invention provides a hard coating film comprising a polyimide base material and a cured product of the hard coating composition on at least one side of the base material, wherein the difference in refractive index between the base material and the hard coating composition is 0.03 or less .

Further, the image display device of the present invention is characterized by including the above-mentioned hard coating film.

 The hard coating film according to the present invention can be applied to a flexible image display device by including a polyimide base material having excellent bending durability, and can be used as a cured product of a polyimide base material and a hard coating composition; It is possible to prevent the occurrence of interference fringes and to provide an excellent hardness and adhesion.

Further, the image display apparatus according to the present invention has the advantage that it can be a flexible image display device, and interference fringes are also prevented by including the above-mentioned hard coating film.

When a member is referred to as being " on "another member in the present invention, this includes not only when a member is in contact with another member but also when another member exists between the two members.

Whenever a part is referred to as "including " an element in the present invention, it is to be understood that it may include other elements as well, without departing from the other elements unless specifically stated otherwise.

Hereinafter, the present invention will be described in more detail.

< Hard coating  Film>

A hard coating film according to an aspect of the present invention includes a cured product of a hard coating composition on at least one surface of a polyimide based substrate and adjusts a difference in refractive index between the substrate and the cured product of the hard coating composition to 0.03 or less . Further, according to an embodiment of the present invention, it is more preferable that the difference in refractive index is less than 0.02. As described above, the hard coating film of the present invention can be applied to a flexible image display device using a polyimide base material having excellent bending durability as a base material. The difference in refractive index between the base material and the hard coating composition is 0.03 or less The occurrence of interference fringes is prevented, and the hardness and adhesion are also excellent.

Polyimide-based substrate

The hard coating film according to one aspect of the present invention includes a polyimide-based substrate.

As described above, the hard coating film according to an embodiment of the present invention has a polyimide base material having excellent durability (bending durability) against repetitive bending, which is advantageous in that it can be applied to a flexible image display device.

In the present invention, the polyimide base material means a base material containing a polyimide base compound as a main component, and examples thereof include polyimide, polyamide imide and the like, but not limited thereto, If any, can be used without any particular limitation.

The polyimide-based substrate may be one obtained by polymerizing a monomer including a tetracarboxylic acid dianhydride and a diamine.

The tetracarboxylic acid dianhydride is not particularly limited, and examples thereof include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides.

Examples of the aliphatic tetracarboxylic acid dianhydride include bicyclo [2.2.2] octo-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, bicyclo [2.2.2] , 5,6-tetracarboxylic acid dianhydride, 5- (dioxotetrahydrofuryl-3-methyl) -3-cyclohexene-1,2-dicarboxylic acid anhydride, 4- Tetrahydrofuran-3-yl) -tetralin-1,2-dicarboxylic acid anhydride, tetrahydrofuran-2,3,4,5-tetracarboxylic acid dianhydride, bicyclo- 4,4'-tetracarboxylic dianhydride, 3c-carboxymethylcyclopentane-1r, 2c, 4c-tricarboxylic acid 1,4,2,3-dianhydride, 1,2,4,5-cyclohexane Tetracarboxylic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride, and the like.

Examples of the aromatic tetracarboxylic acid dianhydride include 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,3 ', 3,4'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic acid dianhydride, 4,4'-tetracarboxylic dianhydride, m-terphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride, 4,4' - (2, Bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2- Bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 7-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,2-bis (3, 4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3 , 3-hexafluoropropane dianhydride, (1,1 ': 3', 1 "-terphenyl) -3,3", 4,4 "-tetracarboxylic dianhydride, 4,4 '- Siladiiyl) diphthalic dianhydride, and 4,4 '- (1,4-phenylenebis (oxy)) diphthalic dianhydride.

From the above-mentioned tetracarboxylic acid dianhydride, from the viewpoint of obtaining a polyimide base material having excellent chemical and physical properties, it is preferably an aromatic tetracarboxylic acid dianhydride, more preferably a biphenyltetracarboxylic acid dianhydride And 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,3 ', 3,4'- More preferably biphenyltetracarboxylic acid dianhydride.

The above-mentioned tetracarboxylic acid dianhydrides may be used alone or in combination of two or more.

Examples of the diamine include, but are not limited to, aliphatic diamines and aromatic diamines.

Examples of the aliphatic diamine include diaminobutane, diaminopentane, diaminohexane, diaminoheptane, diaminooctane, diaminononane, diaminodecane, diaminoundecane, diaminododecane, 1,4-diaminocyclo Hexane, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 3-methyl-1,4-diaminocyclohexane, 5,5-dimethylcyclohexylamine, Bis (aminocyclohexyl) methane, bis (3,3'-methyl-4,4'-aminocyclohexyl) methane, bis (aminomethyl) Tricyclo [5,2,1,0] decane, isophoronediamine, and 1,3-diaminoamidanthane.

Examples of the aromatic diamine include p-phenylenediamine, metaphenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'- diaminodiphenylmethane, 4,4'- Diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, (Trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-bis 4-aminophenyl) sulfide, 4,4'-diaminodiphenylsulfone, 4,4'-diaminobenzanilide, 1,4-bis (4-aminophenoxy) benzene, 1,3- (3-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis Bis (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2- Bis [4- (4-aminophenoxy) phenyl] hexafluoropropane It can be given.

Among the aforementioned diamines, from the viewpoint of obtaining a polyimide base material having excellent chemical and physical properties, an aromatic diamine is preferable, and p-phenylenediamine is more preferable.

The above-mentioned diamines may be used alone or in combination of two or more.

As described above, the polyimide base material can be obtained by polymerizing a monomer including a tetracarboxylic acid dianhydride and a diamine. More specifically, a polyimide base material can be prepared by (1) synthesizing a polyamic acid by reacting a tetracarboxylic acid dianhydride and a diamine in an organic solvent, and (2) imidizing the obtained polyamic acid .

(1) Synthesis of polyamic acid

The polyamic acid can be synthesized by reacting a tetracarboxylic acid dianhydride and a diamine in an organic solvent.

This reaction is preferably carried out by dissolving the diamine in an organic solvent and slowly adding the tetracarboxylic dianhydride while stirring the obtained diamine solution.

Examples of the organic solvent that can be used include, but are not limited to, amide solvents such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, ; cyclic ester solvents such as? -butyrolactone,? -valerolactone,? -valerolactone,? -caprolactone,? -caprolactone and? -methyl-? -butyrolactone; Carbonate solvents such as ethylene carbonate and propylene carbonate; Glycol solvents such as triethylene glycol; phenol-based solvents such as m-cresol, p-cresol, 3-chlorophenol and 4-chlorophenol; Acetophenone; 1,3-dimethyl-2-imidazolidinone; Sulfolane; Dimethyl sulfoxide and the like. In addition, it is also possible to use phenol, O-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, Methyl ethyl ketone, acetone, butanol, isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol , Ethanol, xylene, toluene, chlorobenzene, terpene, mineral spirit, and petroleum naphtha-based solvents.

Of these, it is preferable to use an amide-based solvent, and the organic solvent may be used alone or in combination of two or more.

(2) Production of polyimide substrate

A polyimide base material can be produced by imidizing the polyamic acid obtained in the above (1).

The production of the polyimide substrate can be carried out, for example, by pouring a solution containing a polyamic acid onto a support and heating it.

The solution containing the polyamic acid may include a polyamic acid and an organic solvent, and may further include an imidization catalyst, an organic phosphorus-containing compound, an inorganic fine particle, and the like, if necessary.

As the polyamic acid, those obtained in the above (1) can be used. At this time, the polyamic acid may be used alone or in combination of two or more. The content of the polyamic acid is preferably 10 to 30 mass% with respect to the total amount of the solution containing the polyamic acid.

As the solvent, the above-mentioned organic solvent may be used.

The imidization catalyst may serve to improve the physical properties (elongation, end tear resistance, etc.) of the polyimide film.

The imidation catalyst specifically includes a substituted or unsubstituted nitrogen-containing heterocyclic compound and the N-oxide compound; A substituted or unsubstituted amino acid compound; An aromatic hydrocarbon compound having a hydroxyl group; Aromatic heterocyclic compounds, but are not limited thereto.

More specifically, it is preferable to use at least one selected from the group consisting of 1,2-dimethylimidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, Dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine, 4-methylpyridine, 4-methylpyridine, 4- n-propylpyridine and the like.

Specific examples of the organophosphorus compound include monocaproyl phosphate ester, monoctyl phosphate ester, monolauryl phosphate ester, monomyristyl phosphate ester, monocetyl phosphate ester, monostearyl phosphate ester, triethylene glycol monotrityl ether , Monophosphoric acid esters of tetraethylene glycol monolauryl ether, monophosphoric acid esters of diethylene glycol monostearyl ether, dicaproyl phosphate esters, dioctylphosphoric acid esters, dicapryl phosphate esters, dilauryl phosphate esters, Diisostearyl phosphate ester, dicetyl phosphate ester, distearyl phosphate ester, diphosphoric acid ester of tetraethylene glycol mononeopentyl ether, diphosphoric acid ester of triethylene glycol mono-tridecyl ether, dipentaerythritol monolauryl ether of diethylene glycol monolauryl ether Phosphoric acid esters, diethylene glycol The phosphoric acid esters, amine salts of these phosphoric acid esters such as di-phosphate esters of noseute aryl ethers can be used. Examples of the amine salt include ammonia, monomethylamine, monoethylamine, monopropylamine, monobutylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, trimethylamine, triethylamine, tripropylamine, tributyl Amine salts such as amine, monoethanolamine, ethanolamine, triethanolamine, and the like, but are not limited thereto. The organic phosphorous-containing compounds may be used alone or in combination of two or more.

Specific examples of the inorganic fine particles include inorganic oxide powders such as particulate titanium dioxide powder, silicon dioxide (silica) powder, magnesium oxide powder, aluminum oxide (alumina) powder and zinc oxide powder; Inorganic nitride powders such as fine silicon nitride powder and titanium nitride powder; Inorganic carbide powder such as silicon carbide powder; Inorganic calcium phosphate powder, calcium carbonate powder, fine calcium carbonate powder, calcium sulfate powder, barium sulfate powder and the like, but is not limited thereto. These inorganic fine particles may be used alone or in combination of two or more. In order to uniformly disperse the inorganic fine particles in the solution containing the polyamic acid, means known per se can be applied.

As a support for softening the solution containing the polyamic acid, a known support such as a stainless steel substrate, a stainless steel belt, or the like may be used, but is not limited thereto. At this time, it is preferable that the support is smooth, and it is preferable that the support is an endless support such as an endless belt from the viewpoint of enabling continuous production.

The method of softening the solution containing the polyamic acid is not particularly limited, but it is preferably an extrusion coating or a melt coating.

When a solution containing a polyamic acid is plied to a support, a coating film having self-supporting property can be obtained.

At this time, a solution containing a surface treatment agent may be applied to one side or both sides of the resultant coated film having self-supportability, if necessary. In the present specification, the treatment of the polyimide base with the surface treatment agent is not included in the &quot; surface treatment of the polyimide base &quot; described later.

The solution containing the surface treatment agent may include a surface treatment agent and an organic solvent.

Specific examples of the surface treatment agent include, but are not limited to, a silane coupling agent, a borane coupling agent, an aluminum coupling agent, an aluminum chelating agent, a titanate coupling agent, an iron coupling agent and a copper coupling agent. Among them, it is preferable to use a silane coupling agent or a titanate coupling agent.

Specific examples of the silane coupling agent include epoxy silane compounds such as? -Glycidoxypropyltrimethoxysilane,? -Glycidoxypropyldiethoxysilane, and? - (3,4-epoxycyclohexyl) ethyltrimethoxysilane Coupling agents; Vinyl silane coupling agents such as vinyltrichlorosilane, vinyltris (? -Methoxyethoxy) silane, vinyltriethoxysilane and vinyltrimethoxysilane; acrylsilane-based coupling agents such as? -methacryloxypropyltrimethoxysilane; Aminopropyltrimethoxysilane, N -? - (aminoethyl) -? - aminopropyltrimethoxysilane, N -? - Aminosilane-based coupling agents such as aminopropyltrimethoxysilane; ? -mercaptopropyltrimethoxysilane,? -chloropropyltrimethoxysilane, and the like, but are not limited thereto.

Examples of the titanate-based coupling agent include isopropyltriisostearoyl titanate, isopropyltridecylbenzene sulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctylphosphine) Bis (di-tridecyl) phosphite titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate) Rosin phosphate) ethylene titanate, isopropyltri octanoyl titanate, isopropyl tricumyl phenyl titanate, and the like, but is not limited thereto.

Among the above-mentioned surface treatment agents, it is preferable to use an aminosilane coupling agent and γ-aminopropyltriethoxysilane, N -? - (aminoethyl) -? - aminopropyltriethoxysilane, N- Aminopropyltriethoxysilane, N- [? - (phenylamino) -ethyl] -? - aminopropyltriethoxysilane, N- Phenyl-gamma -aminopropyltrimethoxysilane is more preferably used, and it is more preferable to use N-phenyl- gamma -aminopropyltrimethoxysilane.

The above-mentioned surface treatment agents may be used alone or in combination of two or more.

As specific examples of the organic solvent, specific examples of the organic solvent used in the synthesis of the above-mentioned polyamic acid can be similarly applied.

Examples of a method of applying the solution containing the surface treatment agent to a coating film having self-supporting properties include a gravure coating method, a spin coating method, a silk screen method, a dip coating method, a spray coating method, a bar coating method, a knife coating method , A roll coating method, a blade coating method, a die coating method and the like.

The thus obtained coating film having a self-supporting property or a coating film obtained by applying a solution containing a self-supporting coating film and a surface treatment agent is heated to cause imidization of the polyamic acid to produce a polyimide base material .

The heating temperature of the imidization is not particularly limited as long as it is a temperature at which the imidization proceeds, but it is preferably 100 to 550 ° C, more preferably 100 to 400 ° C. In this case, it is preferable to carry out the heating stepwise. For example, the first heating treatment may be performed at 100 to 170 캜, the second heating treatment may be performed at 170 to 220 캜, 400 DEG C and the fourth heat treatment may be performed at 400 to 550 DEG C. [

At the time of heating, the film may be stretched if necessary. This makes it possible to appropriately control the physical properties such as the coefficient of thermal expansion of the polyimide base material. In this case, the stretching method may be biaxial stretching such as biaxial stretching or simultaneous biaxial stretching, or uniaxial stretching. The stretching ratio is preferably 2 to 10 times in the longitudinal direction and in the transverse direction, respectively. From the viewpoint of improving the dimensional stability of the polyimide base material, a relaxation treatment may be performed after stretching.

The polyamic acid may be imidized in place of the heating or by chemical imidization with heating.

A specific method of the chemical imidization is not particularly limited, but can be carried out, for example, by pouring a solution obtained by further adding a dehydrating agent and a catalyst to a solution containing the polyamic acid described above on a support and heating it.

The dehydrating agent is not particularly limited, and examples thereof include aliphatic acid anhydrides, aromatic acid anhydrides, alicyclic acid anhydrides, and heterocyclic acid anhydrides. Specific examples thereof include acetic anhydride, anhydrous propionic acid, anhydrous butyric acid, formic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, benzoic anhydride and anhydrous picolinic acid. Of these, acetic anhydride is preferably used. The dehydrating agent may be used alone or in combination of two or more.

Examples of the catalyst include aliphatic tertiary amines, aromatic tertiary amines and heterocyclic tertiary amines. Specific examples thereof include trimethylamine, triethylamine, dimethylaniline, pyridine,? -Picoline, isoquinoline, Quinoline, and the like. Of these, isoquinoline is preferably used, but not limited thereto.

With respect to the softening and heating of the support, the polyimide base material can be produced by the same method as described above.

As the polyimide-based substrate, a known polyimide-based substrate prepared by, for example, reacting a tetracarboxylic acid dianhydride with diisocyanate may be used in addition to the above.

Hard coating  Composition

The hard coating film according to one embodiment of the present invention comprises a cured product of a hard coating composition and the difference in refractive index between the cured product of the hard coating composition and the aforementioned polyimide based material is adjusted to 0.03 or less, Thereby preventing the occurrence of interference fringes, and having an advantage of being excellent in hardness and adhesion.

High Refraction  Suzy

According to one embodiment of the present invention, the hard coating composition includes an advantage of being able to reduce the difference in refractive index between the cured product of the hard coating composition containing the high refractive index resin and the polyimide based substrate. According to one embodiment of the present invention, it is preferable that the refractive index after curing of the high refractive index resin is 1.55 or more in order to minimize a refractive index difference with the polyimide base material.

In the present invention, the type of the high refractive index resin is not particularly limited, but may specifically be a polymer resin or a photo-curable (meth) acrylate oligomer or a monomer, and more specifically, a thioether, a sulfone, a cyclic thiophene, Thiadiazole series, thianthrene series and the like; Halogen derivative resins including bromine, iodine groups and the like; Carbazole-based, phosphonate-based, phosphazene-based, and the like; Fluorene derivative resins; Biphenol-based derivative resins; And carbodiimide derivative resins; &Lt; RTI ID = 0.0 &gt; and / or &lt; / RTI &gt;

According to an embodiment of the present invention, the content of the high refractive index resin may be adjusted to control the refractive index of the cured product of the hard coating composition, To 10% by weight, preferably 20% to 100% by weight, and more preferably 30% to 100% by weight based on 100% by weight of the composition. When the content of the high refractive index resin satisfies the above range, the refractive index of the cured product of the hard coating composition containing the high refractive index resin is increased, thereby easily reducing the difference in refractive index between the hardened resin and the polyimide based substrate.

According to one embodiment of the present invention, the hard coating composition may further include at least one selected from the group consisting of a light transmitting resin, a solvent and a photoinitiator.

Translucency  Suzy

The hard coating composition of the present invention may further comprise a light transmitting resin, and the light transmitting resin may include a photocurable (meth) acrylate oligomer or (meth) acrylate monomer which can be cured by ultraviolet rays.

The photocurable (meth) acrylate oligomer may be a commercially available epoxy (meth) acrylate oligomer, urethane (meth) acrylate oligomer, or the like, and preferably includes a urethane (meth) acrylate oligomer.

The urethane (meth) acrylate oligomer may be any of those used in the art, but is preferably a urethane (meth) acrylate oligomer prepared by reacting a compound having a polyfunctional (meth) acrylate having a hydroxyl group in a molecule with an isocyanate group in the presence of a catalyst May be used.

Specific examples of the (meth) acrylate having a hydroxy group in the molecule include 2-hydroxyethyl (meth) acrylate, 2-hydroxyisopropyl (meth) acrylate, 4-hydroxybutyl (Metha) acrylate mixture, and a mixture of dipentaerythritol penta / hexa (meth) acrylate, but are not limited thereto, and they may be used alone or in combination of two or more kinds These can be used in combination.

Specific examples of the compound having an isocyanate group in the molecule include 1,4-diisocyanatobutane, 1,6-diisocyanatohexane, 1,8-diisocyanatooctane, 1,12-diisocyanatododecane, Diisocyanato-2-methylpentane, trimethyl-1,6-diisocyanatohexane, 1,3-bis (isocyanatomethyl) cyclohexane, trans-1,4-cyclohexane diisocyanate, Diisocyanate, toluene-2,6-diisocyanate, xylene-1,4-diisocyanate, tetramethyl xylene-1, Diisocyanate, 1-chloromethyl-2,4-diisocyanate, 4,4'-methylenebis (2,6-dimethylphenyl isocyanate), 4,4'-oxybis (phenylisocyanate), hexamethylene diisocyanate &Lt; / RTI &gt; trifunctional isocyanate and trimethane propanol adduct derived from toluene di SOCCIA but are the carbonate or the like, not limited to this, and these may be used alone or in combination of two or more.

The photocurable (meth) acrylate monomer means a photocurable functional group having in its molecule an unsaturated group such as a (meth) acryloyl group, a vinyl group, a styryl group or an allyl group, and includes a (meth) acryloyl group desirable.

Examples of the monomer having a (meth) acryloyl group as described above include neopentyl glycol acrylate, 1,6-hexanediol (meth) acrylate, propylene glycol di (meth) acrylate, triethylene glycol di Acrylate, trimethylolpropane tri (meth) acrylate, trimethylol ethane tri (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di Acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, pentaerythritol tri (Meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa Acrylate, isopentyl (meth) acrylate, isopentyl (meth) acrylate, tripentaerythritol tri (meth) acrylate, tripentaerythritol hexa trit (meth) acrylate, , But are not limited to, stearyl (meth) acrylate, tetrahydroperfuryl (meth) acrylate, phenoxyethyl (meth) acrylate and isobonol They may be used alone or in combination of two or more.

The content of the light transmitting resin is not particularly limited in the present invention, but may be in the range of 1 to 80% by weight based on 100% by weight of the entire hard coating composition. When the light-transmitting resin is contained within the above range, the hardness is improved and curling can be suppressed.

Photoinitiator

The hard coating composition of the present invention may further comprise a photoinitiator.

The photoinitiator serves to change the liquid hard coating liquid to a solid phase, and any photoinitiator used in the art can be used without any particular limitation.

Specific examples thereof include hydroxycetones, aminoketones, and hydrogen recyclable photoinitiators, and more specifically 2-methyl-1- [4- (methylthio) phenyl] 2- morpholinepropanone- Ketone, benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-1-one, 4-hydroxycyclophenyl ketone, 2,2-dimethoxy- , Triphenylamine, carbazole, 3-methylacetophenone, 4-quinoloroacetophenone, 4,4-dimethoxyacetophenone, 4,4-diaminobenzophenone, 1-hydroxycyclohexylphenylketone, benzophenone , Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, and the like. However, the present invention is not limited thereto, and they may be used alone or in combination of two or more.

The content of the photoinitiator is not particularly limited in the present invention, but is preferably 0.1 to 10% by weight, more preferably 1 to 5% by weight based on 100% by weight of the total hard coat composition. When the photoinitiator satisfies the above range, the physical properties of the cured product of the hard coating composition may be improved due to a sufficient degree of curing.

solvent

The hard coating composition of the present invention may further comprise a solvent.

The above-mentioned solvent can dissolve or disperse the above-mentioned components and can be used without any particular limitation as long as it is used as a solvent in the art.

Specific examples of the solvent include alcohol-based solvents such as methanol, ethanol, isopropanol, butanol, methylcellulose, ethylcellulose and the like; ketones such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, , Propyleneglycol monomethyl ether acetate, propyleneglycol acetate, propyleneglycol monomethylether acetate, propyleneglycol monomethylether acetate, propyleneglycol monomethylether acetate, propyleneglycol monomethylether acetate, ethyleneglycol monomethylether acetate, (Hexane, heptane, octane, etc.), benzene (benzene, toluene, xylene and the like), ether (methacrylic acid and the like) Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether Propylene glycol monomethyl ether, etc.) and the like are preferably used, but not limited thereto, and they may be used alone or in combination of two or more.

The content of the solvent in the present invention is not particularly limited, but may be in the range of 10 to 95% by weight based on 100% by weight of the hard coat composition. When the content of the solvent is within the above range, the viscosity of the hard coating composition can be easily controlled, workability is improved, swelling of the substrate film used can be sufficiently progressed, time can be saved in the drying process, This is an excellent advantage.

In addition, the hard coating composition of the present invention may further contain additives such as other polymer compounds, hardeners, leveling agents, adhesion promoters, antioxidants, ultraviolet absorbers, anti-aggregation agents and the like, if necessary.

As described above, the hard coating film according to one aspect of the present invention comprises a cured product of a hard coating composition on at least one side of a polyimide-based substrate, and the difference in refractive index between the substrate and the hard coating composition is 0.03 or less . Further, according to an embodiment of the present invention, it is more preferable that the difference in refractive index is less than 0.02. As described above, the hard coating film of the present invention can be applied to a flexible image display device using a polyimide base material having excellent bending durability as a base material. The difference in refractive index between the base material and the hard coating composition is 0.03 or less The occurrence of interference fringes is prevented, and the hardness and adhesion are also excellent.

<Image Display Device>

Another aspect of the present invention is an image display apparatus including the above-mentioned hard coating film.

The image display apparatus is not particularly limited, and examples thereof include a liquid crystal display (LCD), a field emission display (FED), a plasma display (PDP), an organic electroluminescence (OLED) .

Particularly, the image display device according to one embodiment of the present invention is advantageous in application to a flexible image display device because it includes a hard coating film provided with a polyimide base material having excellent bending durability.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. , And it is natural that such variations and modifications fall within the scope of the appended claims. In the following Examples and Comparative Examples, "%" and "part" representing the contents are by weight unless otherwise specified.

Manufacturing example : Hard coating  Preparation of composition

Manufacturing example  One.

25 wt% of pentaerythritol triacrylate, 25 wt% of fluorene high refractive index acrylate (Osaka Gas Chemical Co., OGSOL EA-F5003, cured refractive index 1.58), 10 wt% of methyl ethyl ketone (purified gold) , 37 weight% of monomethyl ether (purified gold powder), 2.5 weight% of 1-hydroxy-cyclohexylphenyl-ketone and 0.5 weight% of a leveling agent (BYK Chemie, BYK3570) were blended using a stirrer, (PP) filter to prepare a hard coating composition.

Manufacturing example  2.

25% by weight of pentaerythritol triacrylate, 25% by weight of cadmium high refractive index acrylate (Taoka Chemical Industries, TBIS-MPEC, cured refractive index 1.59), 10% by weight of methyl ethyl ketone (purified gold), propylene glycol monomethyl , 2.5 weight% of 1-hydroxy-cyclohexyl-phenyl-ketone, and 0.5 weight% of a leveling agent (BYK Chemie, BYK3570) were mixed using a stirrer and polypropylene (PP ) &Lt; / RTI &gt; filter to prepare a hardcoat composition.

Manufacturing example  3.

25 wt% of pentaerythritol triacrylate, 25 wt% of bifluorene high refractive index acrylate (MIIS Specialty Chemicals, HR6042, refractive index after curing 1.61), 10 wt% of methyl ethyl ketone (purified gold powder), propylene glycol monomethyl , 2.5 weight% of 1-hydroxy-cyclohexyl-phenyl-ketone, and 0.5 weight% of a leveling agent (BYK Chemie, BYK3570) were mixed using a stirrer and polypropylene (PP ) &Lt; / RTI &gt; filter to prepare a hardcoat composition.

Manufacturing example  4.

50 wt% of pentaerythritol triacrylate, 10 wt% of methyl ethyl ketone (purified gold powder), 37 wt% of propylene glycol monomethyl ether (purified gold powder), 2.5 wt% of 1-hydroxy-cyclohexyl- And 0.5% by weight of a leveling agent (BYK 3570, BYK 3570) were mixed using a stirrer and filtered using a filter made of polypropylene (PP) to prepare a hard coating composition.

Example  And Comparative Example : Hard coating  Production of film

Example  One.

Using the hard coating composition of Preparation Example 1, a coating film was formed on a polyimide (PI) film (refractive index: 1.55) having a thickness of 80 탆 so as to have a thickness of 10 탆 after curing and then dried at 80 캜 for 2 minutes , And UV curing light amount of 1 J / cm &lt; ² &gt; At this time, the refractive index after curing of the cured product of the hard coating composition was 1.545, and the difference in refractive index between the cured product of the polyimide base film and the hard coating composition was 0.005.

At this time, the refractive index was measured by measuring the refractive index of a 589 nm wavelength using a reflectometer (STX-4000, manufactured by CAMAC Co., Ltd.) after coating the hard coating composition on a silicon wafer to a thickness of 1 μm after curing.

Example  2.

A hard coat film was prepared in the same manner as in Example 1, except that the hard coat composition of Production Example 2 was used instead of the hard coat composition of Production Example 1 in Example 1. At this time, the refractive index after curing of the cured product of the hard coating composition was 1.55, and the difference in refractive index between the cured product of the polyimide base film and the hard coating composition was zero.

At this time, the refractive index was measured by the same method as in Example 1 described above.

Example  3.

A hard coat film was prepared in the same manner as in Example 1 except that the hard coat composition of Production Example 3 was used instead of the hard coat composition of Production Example 1 in Example 1. At this time, the refractive index after curing of the cured product of the hard coating composition was 1.56, and the difference in refractive index between the cured product of the polyimide base film and the hard coating composition was 0.01.

At this time, the refractive index was measured by the same method as in Example 1 described above.

Comparative Example  One.

A hard coat film was prepared in the same manner as in Example 1 except that the hard coat composition of Production Example 4 was used instead of the hard coat composition of Production Example 1 in Example 1. At this time, the refractive index after curing of the cured product of the hard coating composition was 1.51, and the difference in refractive index between the cured product of the polyimide base film and the hard coating composition was 0.04.

Comparative Example  2.

The same constitution and the same method as in Example 1 were used except that a polymethyl methacrylate (PMMA) film (refractive index 1.5) having a thickness of 80 mu m was used instead of the polyimide substrate of Production Example 1 in Example 1 To prepare a hard coating film. At this time, the refractive index after curing of the cured product of the hard coating composition was 1.545, and the difference in refractive index between the polymethyl methacrylate based film and the cured product of the hard coating composition was 0.045.

Comparative Example  3.

Except that a polymethyl methacrylate (PMMA) film (refractive index 1.5) having a thickness of 80 μm was used in place of the polyimide substrate of Production Example 1 in Example 1, and the hard coating composition of Production Example 4 was used A hard coating film was prepared by the same constitution and the same method as in Example 1. At this time, the refractive index after curing of the cured product of the hard coating composition was 1.51, and the difference in refractive index between the polymethylmethacrylate based film and the cured product of the hard coating composition was 0.01.

Experimental Example

Experimental Example  1: Evaluation of prevention of interference fringing

The surface of the substrate film was bonded to a black acrylic plate using a transparent pressure-sensitive adhesive so that the hard coating layer of the hard coating film prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was on the upper side. Under the three-wavelength lamp, the level of occurrence of interference fringes on the surface of the hard coating layer was visually evaluated as follows, and the results are shown in Table 1 below.

<Evaluation Criteria>

○: Interference pattern is not recognized

△: The interference pattern is weakly recognized.

X: Interference pattern is clearly recognized

Experimental Example  2: pencil hardness experiment

In the hard coating films of Examples 1 to 3 and Comparative Examples 1 to 3, the surface of the base film was fixed to the glass so that the hard coating layer surface was located on the upper side, and then a pencil hardness tester (PHT, The pencil hardness was measured. The test was carried out five times at a length of 1 cm using a pencil of the same hardness and the hardness at which no cissing occurred after the test was carried out four times or more was described in Table 1 as pencil hardness.

Experimental Example  3: Adhesion test

In the hard coating films of Examples 1 to 3 and Comparative Examples 1 to 3, the surface of the base film was bonded to the glass using a transparent pressure-sensitive adhesive so that the hard coating layer surface was on the upper side, and then 100 squares The hard coat surface was scratched with a cutter knife, and then the adhesion test was conducted three times using a nicotine tape. The results are set forth in Table 1 below, and the numerical values set forth in Table 1 below are expressed as "number of squares remaining unremoved after adhesion test / 100 ".

Experimental Example  4: Bending durability

The hard coating films of Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to repetitive bending tests of 200,000 times in which the hard coating layer was folded outward so that the distance between the films was 5 mm. Are shown in Table 1 below.

<Evaluation Criteria>

○: No film break occurred

X: film break

Interference fringe prevention property Pencil hardness Adhesiveness Bending durability Example 1 ○ 3H 100/100 ○ Example 2 ○ 3H 100/100 ○ Example 3 △ 3H 100/100 ○ Comparative Example 1 × 3H 100/100 ○ Comparative Example 2 × 3H 100/100 × Comparative Example 3 ○ 3H 100/100 ×

Referring to Table 1, when the difference between the refractive indexes of the cured product of the polyimide base film and the hard coating composition is 0.03 or less (Examples 1 to 3), the difference in refractive index is greater than 0.03 It can be confirmed that the occurrence of interference fringes was suppressed without deterioration of hardness and adhesion properties in the case of deviating from the scope of the present invention (Comparative Examples 1 and 2), and even if the difference in refractive index satisfied the range of the present invention, In the case of using other films (Comparative Examples 2 and 3), it is confirmed that the durability against repetitive bending is poor.

Claims (7)

A hard coating film comprising a cured product of a hard coating composition on at least one side of a polyimide based substrate,
Wherein the difference in refractive index between the substrate and the cured product of the hard coating composition is 0.03 or less. The method according to claim 1,
Wherein the hard coating composition comprises a high refractive index resin. 3. The method of claim 2,
Wherein the refractive index after curing of the high refractive index resin is 1.55 or more. 3. The method of claim 2,
Wherein the hard coating composition further comprises at least one selected from the group consisting of a light transmitting resin, a photoinitiator and a solvent. 3. The method of claim 2,
Wherein the content of the high refractive index resin is in the range of 10 to 100% by weight based on 100% by weight of the entire hard coating composition. An image display device comprising the hard coating film of any one of claims 1 to 5. The method according to claim 6,
Wherein the image display device is a flexible image display device.