KR101853387B1 - Hard coating film for flexible display - Google Patents

Abstract

The present invention relates to a composition for forming a hard coat layer, and more particularly to a composition for forming a hard coat layer, which comprises an optical radically polymerizable compound, a photo radical polymerization initiator, an epoxy-based photo cationic polymerizable compound, a polyol compound and a photo- To a composition for forming a hard coat layer which is capable of forming a hard coat layer having improved scratch resistance and adhesion, curling is suppressed, and crack resistance against bending is improved.

Description

Hard Coating Film for Flexible Display {HARD COATING FILM FOR FLEXIBLE DISPLAY}

The present invention relates to a hard coating film for a flexible display.

BACKGROUND ART [0002] Recently, a thin display device using a flat panel display device such as a liquid crystal display or an organic light emitting diode (OLED) display has received great attention. Particularly, these thin display devices are realized in the form of a touch screen panel, and are characterized by being portable not only in a smart phone, a tablet PC, but also in various wearable devices It is widely used in various smart devices.

These portable touch screen panel based display devices have a window cover for display protection on a display panel in order to protect the display panel from scratches or external impacts, and in most cases, the tempered glass for display is used as a window cover. Tempered glass for displays is thinner than ordinary glass, but is characterized by high strength and scratch resistance.

However, since the tempered glass has a disadvantage that it is not suitable for weight reduction of a portable device due to its heavy weight, it is difficult to realize an unbreakable property because it is vulnerable to an external impact, and is not bendable, It is not suitable as a flexible display material having a foldable function.

In recent years, studies on optical plastic covers having strength or scratch resistance corresponding to tempered glass, while ensuring flexibility and impact resistance, have been made variously. Polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polyacrylate (PAR), polycarbonate (PC) , Polyimide (PI), and the like. However, these polymer plastic substrates not only lack physical properties in terms of hardness and scratch resistance as compared with tempered glass used as a window cover for display protection, but also have insufficient impact resistance. Therefore, various attempts have been made to complement the physical properties required by coating the composite resin composition on these plastic substrates.

In the case of a general hard coating, a composition comprising a resin containing a photocurable functional group, a curing agent or a curing catalyst and other additives is used. In particular, in the case of a composite resin having a high functional group, it is coated on an optical plastic substrate film to produce hardness and scratch resistance It is possible to use it as a display protection window with improved performance.

However, in the case of a general photocurable composite resin, it is difficult to realize a high hardness corresponding to tempered glass, curl phenomenon due to shrinkage during curing is largely generated, and flexibility is not sufficient, It is not suitable as a protective window cover.

Korean Patent Laid-Open Publication No. 2013-74167 discloses a plastic substrate.

Korea Patent Publication No. 2013-74167

It is an object of the present invention to provide a composition for forming a hard coat layer capable of simultaneously realizing hardness and flexibility.

It is an object of the present invention to provide a hard coating film having a hard coating name made from the above composition.

1. A composition for forming a hard coat layer, comprising a photo-radical polymerizable compound, a photo-radical polymerization initiator, an epoxy-based photo-cationic polymerizable compound, a polyol compound and a photo cationic polymerization initiator.

2. The photo-radical polymerizable compound of claim 1, wherein the photo-radical polymerizable compound is an ester of a polyalcohol and (meth) acrylic acid, 1,4-cyclohexane diacrylate, 1,4butanediol diacrylate, (Meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylol propane tri (meth) acrylate, trimethylol ethane tri ) At least one monomer selected from the group consisting of dipentaerythritol penta (meth) acrylate and pentaerythritol hexa (meth) acrylate; And

At least one oligomer selected from the group consisting of polyester (meth) acrylate, epoxy (meth) acrylate and polyether (meth) acrylate.

3. The composition for forming a hard coat layer according to 1 above, wherein the photo radical polymerization initiator is at least one selected from the group consisting of acetophenones, benzoins, acylphosphine oxides, titanocenes, benzophenones and thioxanthone initiators.

4. The composition for forming a hard coat layer according to item 1 above, wherein the epoxy-based photo cationic polymerizable compound and the polyol compound are contained so as to satisfy the following formula:

[Equation 1]

1? R? 15

(Wherein R is epoxy equivalents / alcohol equivalents, epoxy equivalents are represented by Formula 2, and alcohol equivalents are represented by Formula 3)

&Quot; (2) "

(G / eq) of epoxy-based photo cationic polymerizable compound (g) / epoxy group equivalent of epoxy-based photo cationic polymerizable compound}

&Quot; (3) "

? (Content of polyol compound (g) / hydroxyl group equivalent (g / eq) of polyol compound).

5. The composition for forming a hard coat layer according to 4 above, wherein R is from 1.5 to 10.

6. The epoxy resin composition according to item 1, wherein the epoxy-based photo cationic polymerizable compound is 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl- Bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, vinylcyclohexane-1, Hexene monoxide, 1,2-epoxy-4-vinylcyclohexane, bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, aliphatic cyclic epoxy resin, brominated epoxy resin, rubber modified epoxy resin , A urethane-modified epoxy resin, a glycidyl ester compound, an epoxidized polybutadiene, and an epoxidized SBS.

7. The polyol compound according to item 1 above, wherein the polyol compound is a polyester polyol; Polycarbonate polyol; Polyethylene glycol; Polypropylene glycol; Polycaprolactone polyol; Polytetramethylene glycol; Tetramethyl trimethylol and polyols derived therefrom; Glycerin and polyols derived therefrom; Pentaerythritol tetra alcohol and polyols derived therefrom; Dipentaerythritol hexa alcohols and polyols derived therefrom; A polyacrylate polyol which is an alcohol (macromer type) contained in a polymer side chain; And polyvinyl alcohol. The composition for forming a hard coat layer according to claim 1,

8. The positive electrode of claim 1, wherein the cationic polymerization initiator is at least one selected from the group consisting of an iron-arene complex compound, an aromatic diazonium salt, an aromatic iodonium salt, an aromatic sulfonium salt, a pyridinium salt, Composition for forming hard coat layer

9. The composition for forming a hard coat layer according to 1 above, further comprising at least one solvent selected from the group consisting of a ketone solvent, an acetate solvent and a hydrocarbon solvent.

10. A hard coat film comprising a hard coat layer formed on at least one surface of a substrate, the hard coat layer being formed by a light transmitting composition with the composition for forming a hard coat layer as described in any one of the above 1 to 9.

11. The hard coating film of claim 10, wherein the hard coating layer has a rigidity value of 7 to 12 kPa-mm,

&Quot; (4) "

Rigidity (kPa.mm) = elastic modulus (GPa) x layer thickness (占 퐉).

12. An image display device comprising the hard coating film of the above 10.

The composition for forming a hard coat layer of the present invention includes both a photo cationic polymerization system and a photo radical polymerization system, and both radical polymerization and cationic polymerization are performed at the time of curing. As a result, an interpenetrating polymer network (IPN) can be formed to form a hard coating layer exhibiting excellent hardness and flexibility at the same time.

In the composition for forming a hard coat layer of the present invention, the hardness and flexibility are further improved by controlling the equivalents of the epoxy group and the hydroxy group to a specific range, whereby the scratch resistance and adhesion are improved, the curl is suppressed, This excellent hard coat layer can be formed.

An object of the present invention is to provide a photocurable composition which exhibits excellent hardness and flexibility by including a photo-radical polymerizable compound, a photo-radical polymerization initiator, an epoxy-based photo-cationic polymerizable compound, a polyol compound and a photo cationic polymerization initiator, The present invention relates to a composition for forming a hard coat layer which is capable of forming a hard coat layer which is suppressed in curling and has excellent resistance to bending cracking.

Hereinafter, the present invention will be described in detail.

< Hard coating layer  Composition for forming &gt;

The composition for forming a hard coat layer of the present invention includes a photo-radical polymerizable compound, a photo-cationic polymerizable compound, a photo-radical polymerization initiator, and a photo cationic polymerization initiator.

The composition for forming a hard coat layer of the present invention includes a curing system to each other to thereby form an interpenetrating polymer network by curing to improve hardness and flexibility.

The photo-radical polymerizable compound according to the present invention may be, for example, a photo-radical polymerizable monomer, a photo-radical polymerizable oligomer, or the like. These may be used alone or in combination of two or more.

As the photo-radical polymerizable monomer, a polyfunctional (meth) acrylate having 2 to 6 functional groups can be used. Specific examples include esters of polyhydric alcohol and (meth) acrylic acid (for example, ethylene glycol di (meth) acrylate), 1,4-cyclohexane diacrylate, 1,4-butanediol diacrylate, (Meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylol propane tri (meth) acrylate, trimethylol ethane tri (Meth) acrylate, dipentaerythritol penta (meth) acrylate, pentaerythritol hexa (meth) acrylate, and the like. These may be used alone or in combination of two or more.

Examples of the oligomer include polyester (meth) acrylate, epoxy (meth) acrylate, and polyether (meth) acrylate. These may be used alone or in combination of two or more.

The content ratio of the photo-radical polymerizable monomer to the oligomer is not particularly limited and may be suitably selected in consideration of workability and the like, and may be included in a ratio of, for example, 0:10 to 10: 0.

The photo-radical polymerizable compound according to the present invention is preferably a neutral or acidic compound which contains a radical polymerizable functional group and is not basic. If it is basic, it can react with hydrogen ions during cationic curing and decrease cation hardening. Examples of such compounds include compounds containing a nitrogen atom, and specific examples thereof include urethane (meth) acrylate, melamine (meth) acrylate, acrylomorpholine, and novinyl pyrrolidone.

The photo radical polymerization initiator is not particularly limited as long as it can form a radical by light irradiation.

The photo radical polymerization initiator includes a first type initiator that generates radicals by decomposition of a molecule due to a chemical structure or molecular binding energy difference, and a second type initiator that generates radicals by hydrogen reclamation. The first type initiator and the second type initiator may be used alone or in combination.

Specific examples of usable type 1 initiators include 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyl trichloroacetophenone, diethoxyacetophenone, 2- 2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2- Acetophenones such as methylpropane-1-one, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone and 1-hydroxycyclohexyl phenyl ketone; Benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzyl dimethyl ketal; Acylphosphine oxides; Titanocenes; And the like. These may be used alone or in combination of two or more.

Specific examples of usable type 2 initiators include benzophenone, benzoylbenzoic acid, benzoylbenzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, Benzophenones such as 3'-methyl-4-methoxybenzophenone; Thioxanthone such as thioxanthone, 2-chromothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone and isopropylthioxanthone. These may be used alone or in combination of two or more.

The content of the photo-radical polymerization initiator is not particularly limited and may be, for example, 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the photo-radical polymerizable compound. If the content is less than 0.1 part by weight, hardening may not proceed sufficiently, and it may be difficult to realize the mechanical properties and adhesion of the hard coat layer. If the content is more than 20 parts by weight, problems such as poor adhesion, cracks and curl may occur due to shrinkage.

As the photo cationic polymerizable compound, an epoxy-based polymerizable compound is used. As the epoxy-based polymerizable compound, a monomer or a resin containing an epoxy group (oxiranyl group) or an oxetanyl group can be used.

Examples of the monomer include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4- Bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, vinylcyclohexene monoxide 1,2- Vinylcyclohexane and the like. These may be used alone or in combination of two or more.

Examples of the resin include, for example, bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, aliphatic cyclic epoxy resin, brominated epoxy resin, rubber modified epoxy resin, urethane modified epoxy resin, glycidyl An esterified compound, an epoxidized polybutadiene, an epoxidized SBS (SBS is a styrene-butadiene-styrene copolymer), and the like. These may be used alone or in combination of two or more.

The epoxy equivalent of the epoxy-based photo cationic polymerizable compound according to the present invention is not particularly limited, and may be, for example, 50 to 500 g / eq. When the equivalent weight is less than or equal to the above range, it may be difficult to satisfy the equivalent ratio of the following formula (1). When the epoxy group equivalent is less than 50 g / eq, the curing efficiency is low and it is difficult to effectively form the interpenetrating molecular network structure, so that the hardness may be lowered. When the equivalent weight exceeds 500 g / eq, the curing density is low, It can be difficult.

The polyol compound is used together with the photo cationic polymerizable compound to further improve the flexibility and hardenability of the hard coat layer.

The polyol according to the present invention is an oligomer having 1 to 6, preferably 2 to 4, hydroxyl groups per molecule, for example, a number average molecular weight of 100 to 5,000.

The structure of the alcohol is not particularly limited and may be a primary, secondary or tertiary alcohol, but a primary alcohol is preferable in terms of reaction yield and rate.

Specific examples of the polyol according to the present invention include polyester polyol; Polycarbonate polyol; Polyethylene glycol; Polypropylene glycol; Polycaprolactone polyol; Polytetramethylene glycol; Tetramethyl trimethylol and polyols derived therefrom; Glycerin and polyols derived therefrom; Pentaerythritol tetra alcohol and polyols derived therefrom; Dipentaerythritol hexa alcohols and polyols derived therefrom; A polyacrylate polyol which is an alcohol (macromer type) contained in a polymer side chain; Polyvinyl alcohol; And the like. These may be used alone or in combination of two or more.

The hydroxyl group equivalent of the polyol according to the present invention is not particularly limited and may be, for example, 20 to 2500 g / eq. When the equivalent weight is less than or equal to the above range, it may be difficult to satisfy the equivalent ratio of the following formula (1). If the hydroxyl group equivalent is less than 20 g / eq, the flexibility of the hard coat layer may deteriorate. If it is more than 2500 g / eq, the viscosity may be increased and the processability may be deteriorated.

The epoxy-based photo cationic polymerizable compound and the polyol compound may be included so as to satisfy the following formula (1).

[Equation 1]

1? R? 15

(Wherein R is the total epoxy equivalent weight of the epoxy-based photo cationic polymerizable compound / the total hydroxyl equivalent weight of the polyol compound).

The total epoxy equivalent of the epoxy-based photo cationic polymerizable compound can be represented by the following formula (2).

&Quot; (2) &quot;

(G) / (epoxy group equivalent (g / eq)) of the epoxy-based photo cationic polymerizable compound.

The total hydroxyl equivalent weight of the polyol compound can be expressed by the following equation (3).

&Quot; (3) &quot;

? (Content of polyol compound (g) / hydroxyl group equivalent (g / eq) of polyol compound).

The formula (2) is obtained by adding the epoxy equivalent of each epoxy-based photo cationic polymerizable compound, and the formula (3) is the addition of the hydroxyl group equivalent of each polyol compound.

Specifically, in Equation (2), for example, when 80 g of a polymerizable compound having an epoxy equivalent of 160 g / eq alone is contained in an amount of 80 g, the total epoxy equivalent of the epoxy-based cationic photopolymerizable compound is 0.5. When 40 g of the polymerizable compound having an epoxy equivalent of 160 g / eq and 60 g of a polymerizable compound having an epoxy equivalent of 120 g / eq are contained, the total epoxy equivalent of the epoxy-based photo cationic polymerizable compound is 0.75, which is the sum of 0.25 and 0.5 . This calculation is also applied to Equation 3 in the same manner.

If R is less than 1, the hardness and reliability of the hard coating layer may be lowered. If the R is less than 1, the hardening rate may be lowered, resulting in a lower process yield and lower flexibility of the hard coating layer. From the standpoint of simultaneously exhibiting excellent hardness and flexibility, R may preferably be 1.5 to 10.

The photo cationic polymerization initiator is not particularly limited as long as it can form cations upon irradiation with light, and examples thereof include iron-arene complex compounds, aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, pyridinium salts, / Silyl ether, and the like. These may be used alone or in combination of two or more.

Specific examples of commercially available photo cationic polymerization initiators include IRGACURE 250 (manufactured by BASF), OPTOMER SP-150 (manufactured by Asahi Denka Kogyo), OPTOMER SP-151 (manufactured by Asahi Denka Kogyo), OPTOMER SP-170 (Manufactured by Nippon Soda Co., Ltd.), SANAID SI-100L (manufactured by Sanshin Chemical Industry Co., Ltd.), CI-2064 (manufactured by Nippon Soda Co., Ltd.), UVE-1014 (manufactured by Asahi Denka Kogyo Co., (Manufactured by Nippon Soda), CI-2481 (manufactured by Nippon Soda), RHODORSIL Photoinitiator 2074 (manufactured by Rhone Poulenc GmbH), UVI-6990 (manufactured by Union Carbide), BBI-103 (Manufactured by Midori Kagaku), DPS-103 (manufactured by Midori Kagaku), NAT-103 (manufactured by Midori Kagaku), TPS-103 (manufactured by Midori Kagaku) , NDS-103 (manufactured by Midori Kagaku), and the like.

The mixing ratio of the photo-radical polymerizable compound to the photo-cationic polymerizable compound is not particularly limited. For example, the photo-cationic polymerizable compound is contained in an amount of 50 to 200 parts by weight, preferably 80 to 200 parts by weight, 120 parts by weight. When the mixing ratio is out of the above range, it is difficult to sufficiently form the interpenetrating polymer network, and the effect of improving hardness and flexibility may be deteriorated.

The composition for forming a hard coat layer of the present invention may further comprise a solvent and additives such as inorganic particles, a leveling agent, a UV stabilizer, and a heat stabilizer.

The solvent can be used without limitation as long as it can dissolve or disperse the above components.

However, the above reaction can be carried out with an alcohol solvent (methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol, methyl cellosolve, ethyl cellosolve, propyl cellosolve, etc.) capable of participating in the reaction of the photo- It is preferable not to include an alkaline solvent (n-methylpyrrolidone, dimethylformamide, N, N-dimethyl etchamide, etc.) which may interfere with the reaction.

For example, ketone type (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, etc.); Acetate-based (methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxyacetate and the like); Hydrocarbon type (normal hexane, normal heptane, benzene, toluene, xylene, etc.); And the like. These may be used alone or in combination of two or more.

The content of the solvent is not particularly limited and can be suitably adjusted, for example, such that the solid content of the composition excluding the solvent is 10 to 80% by weight, preferably 30 to 60% by weight.

The inorganic particles are components that improve the mechanical properties such as abrasion resistance and scratch resistance of the hard coat layer.

The inorganic particles preferably have an average particle diameter of 1 nm to 100 nm, more preferably 5 nm to 50 nm. If the average particle diameter is less than 1 nm, coagulation may occur in the composition and it may be difficult to form a uniform coating film. If it exceeds 100 nm, the optical characteristics and mechanical properties of the hard coating layer may be deteriorated.

The inorganic particles may be metal oxide particles. For example, _{Al 2 O 3, SiO 2,} ZnO, ZrO 2, BaTiO 3, TiO 2, Ta 2 O 5, Ti 3 O 5, ITO, IZO, ATO, ZnO-Al, Nb 2 O 3, SnO, MgO Or alloy particles thereof, preferably Al ₂ O ₃ , SiO ₂ , ZrO _2, or alloy particles thereof. These may be used alone or in combination of two or more.

The inorganic particles may be dispersed in an organic solvent at a concentration of 20 to 60% by weight.

The inorganic particles may be contained in an amount of, for example, 5 to 80% by weight, and preferably 10 to 60% by weight, based on the total weight of the composition for forming a hard coat layer, but are not limited thereto.

The leveling agent is a component that imparts smoothness and coatability of the coating film.

The leveling agent includes, for example, a silicon leveling agent, a fluorine leveling agent, and an acrylic high molecular weight leveling agent. These may be used alone or in combination of two or more.

Specific examples of commercially available leveling agents include BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377 and BYK- Glide 410, TEGO Glide 411, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, , TEGO Rad 2500, FC-4430 and FC-4432 of 3M Company.

The leveling agent may be included, for example, in an amount of 0.1 to 1% by weight based on the total weight of the composition for forming a hard coat layer, but is not limited thereto.

The ultraviolet stabilizer is a component that blocks or absorbs ultraviolet rays to prevent decomposition, discoloration, and breakage of the cured hard coat layer by exposure to ultraviolet rays.

UV stabilizers include absorbents, Quenchers, Hindered Amine Light Stabilizers (HALS), etc., classified according to the mechanism of action; In addition, it can be classified into phenyl salicylates, benzophenone, benzotriazole, nickel derivatives, radical scavengers, ; Etc. may be used. These may be used alone or in combination of two or more.

Examples of the thermal stabilizer include polyphenol as a primary heat stabilizer, phosphite as a secondary heat stabilizer, and a lactone type heat stabilizer. These may be used alone or in combination of two or more.

The above-mentioned composition for forming a hard coat layer of the present invention can form a hard coat layer having remarkably improved hardness and flexibility. Accordingly, the hard coat layer formed of the composition of the present invention has excellent hardness, scratch resistance and adhesion, curl is suppressed at the same time, and crack resistance against bending is excellent.

< Hard coating  Film>

The present invention also provides a hard coat film having a hard coat layer formed from the composition for forming the hard coat layer.

The hard coating film of the present invention comprises a base film having a hard coating layer formed on at least one side thereof with the composition.

The base film can be used regardless of whether the base film is a transparent polymer film or not, and examples thereof include triacetylcellulose, acetylcellulose butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butyrylcellulose, acetylpropionylcellulose, Polyolefins such as polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyether sulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether A film formed of a polymer such as a ketone, a polyether ether ketone, a polyether sulfone, a polymethyl methacrylate, a polyethylene terephthalate, a polybutylene terephthalate, a polyethylene naphthalate, or a polycarbonate. These polymers may be used alone or in combination of two or more.

In the case of a crystalline polymer base material film, an engineering plastic base material, or a polymer base film whose surface becomes hydrophilic due to hydrolysis or saponification, which is difficult to impart adhesion force after coating in the base film, it is difficult to increase adhesion when using a composition for forming a conventional hard coating layer, The mechanical properties may deteriorate. However, the above-mentioned composition for forming a hard coat layer of the present invention can achieve excellent adhesion without deteriorating the mechanical properties of these base film.

The base film may be subjected to a surface treatment such as a plasma treatment or a corona treatment in order to improve adhesion with the hard coat layer.

The hard coating layer is formed by applying a composition for forming a hard coating layer on a base film and curing the coating. The coating may be performed by a slit coating method, a knife coating method, a spin coating method, a casting method, a microgravure coating method, A roll coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, a gravure printing method, a flexo printing method, an offset printing method, an inkjet coating method, a dispenser printing method, Can be used.

The thickness of the hard coat layer is not particularly limited, and may be, for example, 5 to 100 占 퐉. When the thickness is within the above range, excellent hardness and flexibility are exhibited, and the curling phenomenon can be prevented.

The hard coat layer may have a rigidity value of 7 to 12 kPa · mm expressed by the following formula (4).

&Quot; (4) &quot;

Rigidity (kPa.mm) = elastic modulus (GPa) x layer thickness (占 퐉).

The hardness parameter represented by Equation (4) is a result of a specific relationship between the modulus of elasticity and the thickness, which affects the hardness and bending properties of the film. The hard coating layer formed with the composition of the present invention exhibits a certain range of rigidity, It is possible to simultaneously improve the hardness and the bending property of the relationship. Therefore, the resistance to fatigue failure is remarkably improved and the application to a flexible display is facilitated.

The elastic modulus of the hard coating layer according to the present invention is not particularly limited as long as it satisfies the stiffness relationship of Equation (4), but may be, for example, 1 to 10 GPa, preferably 3 to 6 GPa. If the elastic modulus is lower than the above range, it is difficult to ensure hardness. If the elastic modulus is above the above range, durability may be lowered at the time of folding. By adjusting the elastic modulus to an appropriate range at the same time as the thickness, the rigidity value of Equation (4) can be satisfied.

The present invention also provides an image display apparatus having the hard coating film.

The hard coating film of the present invention is excellent in hardness and flexibility, so that the hard coating film can be used, for example, as a window cover of an image display apparatus, and is particularly applicable to a flexible image display apparatus.

The image display device may be any of various image display devices such as a liquid crystal display device, an electroluminescence display device, a plasma display device, a field emission display device, and the like.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Manufacturing example  One. Radical Polymerizable  Preparation of composition (A-1)

, 55 parts by weight of hexafunctional acrylate DPEA-12 (Nippon Kayaku Co., Ltd.), 40 parts by weight of bifunctional acrylate M-280 (MWSS) and 5 parts by weight of a photoinitiator Igacure-184 (BASF Corp.) .

Manufacturing example  2. Radical Polymerizable  Preparation of compound (A-2)

30 parts by weight of hexafunctional acrylate DPEA-12, 25 parts by weight of a 10-functional urethane acrylate oligomer UV-1700 (SK-cytec), 40 parts by weight of Nanocryl C165 (Evonix) BASF Corp.) were mixed to prepare a radical polymerizable composition.

Manufacturing example  3. Cation Polymerizable  Preparation of the composition (B)

A cationic polymerizable composition was prepared with the composition and weight parts shown in Table 1 below.

division CEL-2021 PLACCEL-303 PLACCEL-305 Igacure-250 R B-1 69.2 24.8 - 6 2.2 B-2 79.6 14.4 - 6 4.3 B-3 83.6 9.9 - 6 6.5 B-4 80.3 - 13.7 6 8.3 B-5 82.7 - 11.3 6 10.3 B-6 85.1 - 8.9 6 13.5 B-7 90.2 3.8 - 6 18.3 B-8 49.5 44.5 - 6 0.86 B-9 87.2 - 6.8 6 18.0 B-10 38.5 55.5 - 6 0.98 B-11 94 - - 6 - CEL-2021: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, an epoxy equivalent of 130 g / eq,
PLACCEL-303: Polycaprolactone triol, a hydroxyl group equivalent of 100 g / eq,
PLACCEL-305: Polycaprolactone triol, a hydroxyl group equivalent of 183 g / eq,
Igacure-250: BASF

Example  And Comparative Example

A composition for forming a hard coat layer was prepared with the composition and weight parts shown in Table 2 below.

division Radical Polymerizable Composition Cationic polymerizable composition ingredient content ingredient content Example 1 A-1 100 B-1 100 Example 2 A-1 100 B-2 100 Example 3 A-1 100 B-3 100 Example 4 A-1 100 B-4 100 Example 5 A-1 100 B-5 100 Example 6 A-1 100 B-6 100 Example 7 A-1 100 B-4 200 Example 8 A-1 100 B-4 50 Example 9 A-2 100 B-1 100 Example 10 A-1 100 B-7 100 Example 11 A-1 100 B-8 100 Example 12 A-1 100 B-9 100 Example 13 A-1 100 B-10 100 Comparative Example 1 A-2 200 - - Comparative Example 2 - - B-4 200 Comparative Example 3 A-1 100 B-11 100

Hard coating  Film manufacturing and evaluation

The compositions of Examples and Comparative Examples were coated on one surface of a polyimide film (Mitsubishi Gas Chemical Co., Ltd., 100 占 퐉, L-3430) to a thickness of 20 占 퐉 and dried in an oven at 80 占 폚 for 5 minutes. Thereafter, the metal halide lamp (FE) was cured at a light amount of 1000 mJ and then treated in an oven at 80 ° C for 30 minutes to produce a hard coating film.

(1) Pencil Hardness

The pencil hardness was measured by applying a load of 500 g using a pencil hardness tester (PHT, Korea Science and Engineering Corp.). The pencil was a product of Mitsubishi and was subjected to an experiment five times per pencil hardness so that the maximum pencil hardness at which scratches were less than or equal to one time was expressed as the pencil hardness of the hard coating layer.

(2) Abrasion resistance

And scratch resistance was tested by reciprocating ten times under 1 kg / (2 cm x 2 cm) using a steel wool tester (WT-LCM100, Korea Protec Co.). Steel wool used # 0000.

S: 0 scratches

A: 1 to 10 scratches

B: 11-20 scratches

C: 21 ~ 30 scratches

D: More than 31 scratches

(3) Adhesion

11 straight lines were drawn on the coated side of the film at intervals of 1 mm to form 100 squares, and then peel test was performed three times using a tape (CT-24, Nichii Co., Ltd.). Three 100 squares were tested and the average was recorded.

The adhesion was recorded as follows.

Adhesion = n / 100

n: the number of rectangles that are not to be peeled out of the entire rectangle

100: total number of squares

Therefore, when one of them was not peeled off, it was recorded as 100/100.

(4) Curl

A sample cut into a square of A4 size (29.7 x 21.0 cm) was placed on a flat glass plate with the coated side of the film facing up, and the distance from the four glass plates was measured at 25 DEG C and 50% RH, As a measurement value.

S: 0 to 10 mm, A: more than 10 mm to 20 mm, B: more than 20 mm to 30 mm, C: more than 30 mm to 40 mm, D:

(5) Mandrell

In order to evaluate the cracking property, a coated film sample cut into a size of 1 cm x 10 cm was placed on a steel bar of each diameter (2? ~ 10?), The coating layer was turned upside down by hand and the smallest diameter Respectively.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Pencil hardness 5H 5H 5H 5H 6H 6H 4H 4H 4H 6H 3H 6H 3H Abrasion resistance S S S S S S B B C S C S C Adhesiveness 100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/100 70/100 100/100 80/100 100/100 curl S S S S A A A A A B S B S Mandrell 2φ 2φ 2φ 2φ 3φ 3φ 3φ 4φ 3φ 5φ 2φ 5φ 2φ Elastic modulus
(Gpa) 4.1 4.2 4.8 5.1 5.2 5.4 5.3 4.7 4.0 5.5 3.9 3.7 3.8 rigidity
(kPa · mm ³ ) 8.2 8.4 9.6 10.2 10.4 10.8 10.6 9.4 8.0 11.0 7.8 7.4 7.6

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Pencil hardness 4H H 4H Abrasion resistance S D B Adhesiveness 0/100 100/100 100/100 curl D D C Mandrell 7φ 2φ 6φ Modulus of elasticity (Gpa) 6.2 2.5 6.9 Rigidity (kPa · mm ³ ) 12.4 5.0 13.8

Referring to the above table, in the case of the hard coat film having the hard coat layer prepared by the composition for forming the hard coat layer in the examples, the hard coat layer had excellent pencil hardness and scratch resistance, and excellent adhesion to the film. Further, the curl of the hard coating film was small, and the crack resistance against bending was excellent.

However, in the case of the comparative example, it was confirmed that the anti-cracking property to the bending property and the bending property was low or the hardness was remarkably low.

Claims (12)

A light radical polymerization initiator, an epoxy-based photo-cationic polymerizable compound, a polyol compound, and a photo-cation polymerization initiator,
A hard coating film for flexible display having a rigidity value of 7 to 12 kPa 占 퐉 represented by the following formula (4): &quot;
&Quot; (4) &quot;
Rigidity (kPa.mm) = elastic modulus (GPa) x layer thickness (占 퐉).
The photo-radical polymerizable compound of claim 1, wherein the photo-radical polymerizable compound is selected from the group consisting of esters of polyhydric alcohols and (meth) acrylic acid, 1,4-cyclohexane diacrylate, 1,4-butanediol diacrylate, Acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylol propane tri At least one monomer selected from the group consisting of dipentaerythritol penta (meth) acrylate and pentaerythritol hexa (meth) acrylate; And
At least one oligomer selected from the group consisting of polyester (meth) acrylate, epoxy (meth) acrylate and polyether (meth) acrylate.
The hard coating film for flexible display according to claim 1, wherein the photo radical polymerization initiator is at least one selected from the group consisting of acetophenones, benzoins, acylphosphine oxides, titanocenes, benzophenones, and thioxanthone initiators.
The hard coating film for a flexible display according to claim 1, wherein the epoxy-based photo cationic polymerizable compound and the polyol compound are included so as to satisfy the following formula:
[Equation 1]
1? R? 15
(Wherein R is epoxy equivalents / alcohol equivalents, epoxy equivalents are represented by Formula 2, and alcohol equivalents are represented by Formula 3)
&Quot; (2) &quot;
(G / eq) of epoxy-based photo cationic polymerizable compound (g) / epoxy group equivalent of epoxy-based photo cationic polymerizable compound}
&Quot; (3) &quot;
? (Content of polyol compound (g) / hydroxyl group equivalent (g / eq) of polyol compound).
5. The hard coating film for flexible display according to claim 4, wherein R is 1.5 to 10.
[2] The composition of claim 1, wherein the epoxy-based photo cationic polymerizable compound is 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2- (3,4- (3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, vinylcyclohexene mono Epoxy-4-vinylcyclohexane, bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, bisphenol F epoxy resin, novolak epoxy resin, aliphatic cyclic epoxy resin, brominated epoxy resin, rubber modified epoxy resin, urethane A modified epoxy resin, a glycidyl ester compound, an epoxidized polybutadiene, and an epoxidized SBS.
[2] The composition of claim 1, wherein the polyol compound is a polyester polyol; Polycarbonate polyol; Polyethylene glycol; Polypropylene glycol; Polycaprolactone polyol; Polytetramethylene glycol; Tetramethyl trimethylol and polyols derived therefrom; Glycerin and polyols derived therefrom; Pentaerythritol tetra alcohol and polyols derived therefrom; Dipentaerythritol hexa alcohols and polyols derived therefrom; A polyacrylate polyol which is an alcohol (macromer type) contained in a polymer side chain; And polyvinyl alcohol. The hard coating film for flexible display according to claim 1,
The positive electrode of claim 1, wherein the cationic polymerization initiator is at least one selected from the group consisting of an iron-arene complex compound, an aromatic diazonium salt, an aromatic iodonium salt, an aromatic sulfonium salt, a pyridinium salt, Hard coating film for display.
The hard coating film for a flexible display according to claim 1, further comprising at least one solvent selected from the group consisting of a ketone solvent, an acetate solvent and a hydrocarbon solvent.
A hard coating film for a flexible display comprising the hard coating layer according to any one of claims 1 to 9 on at least one surface of a substrate.
delete The image display apparatus according to claim 10, comprising a hard coating film for a flexible display.