JP2021120758A - Composition for forming hard coat layer - Google Patents

Abstract

To provide a composition for forming a hard coat layer.SOLUTION: There is provided a composition for forming a hard coat layer capable of forming a hard coat layer which exhibits excellent hardness and flexibility by containing a photo-radical polymerizable compound, a photoradical polymerization initiator, an epoxy-based cation photopolymerizable compound, a polyol compound and a photo cationic polymerization initiator, is improved in scratch resistance and adhesiveness and suppressed in curling and excellent in crack resistance to bending.SELECTED DRAWING: None

Description

The present invention relates to a composition for forming a hard coat layer.

In recent years, a thin display device using a flat plate display device such as a liquid crystal display device or an organic light emitting display display has attracted attention. In particular, these thin display devices are realized in the form of touch screen panels (touch screen panels), and not only smartphones (smart phones) and tablets (tablet) PCs, but also various wearable devices (wearable devices). It is widely used in various smart devices characterized by portability.

Display devices based on these portable touch screen panels have a display protective window cover on the display panel to protect the display panel from scratches and external shocks, and in most cases the display. Tempered glass is used as a window cover. Tempered glass for displays is thinner than ordinary glass, but has the characteristics of high strength and scratch resistance.

However, tempered glass is not only heavy and unsuitable for reducing the weight of mobile devices, but also vulnerable to external impacts, so it is difficult to realize unbreakable properties, and it is constant. It does not bend above the standard. For this reason, tempered glass is not suitable as a material for flexible displays having a bendable or foldable function.

Recently, active studies have been conducted on optical plastic covers that ensure flexibility and impact resistance, and have strength and scratch resistance equivalent to tempered glass. Generally, as a material of a transparent plastic cover for optics, which is more flexible than tempered glass, polyethylene terephthalate (PET), polyether sulfone (PES), polyethylene naphthalate (PEN), polyacrylate (PAR), polycarbonate (PC) ), Polyimide (PI) and the like. However, these polymer plastic substrates not only exhibit insufficient 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 sufficient impact resistance. No. Therefore, various attempts have been made to complement the required physical properties by coating these plastic substrates with a composite resin composition.

In a normal hard coat, a composition consisting of a resin containing a photocurable functional group and a curing agent, a curing catalyst, and other additives is used, but in particular, in the case of a composite resin having a high functional group, this is optically used. By coating on a plastic base film for use, it can be used as a display protection window with improved hardness and scratch resistance.

However, it is difficult for a general photocurable composite resin to achieve a high hardness equivalent to that of tempered glass, and a curl phenomenon due to shrinkage during curing occurs significantly, and the flexibility is not sufficient. It has the drawback of not being suitable as a protective window cover for application to flexible displays.

Korean Publication No. 2013-74167 (Patent Document 1) discloses a plastic substrate.

Korean Publication No. 2013-74167 Gazette

An object of the present invention is to provide a composition for forming a hard coat layer capable of simultaneously achieving high hardness and flexibility.

Another object of the present invention is to provide a hard coat film provided with a hard coat layer produced from the above composition.

1. 1. The composition for forming a hard coat layer according to the present invention contains a photoradical polymerizable compound, a photoradical polymerization initiator, an epoxy-based photocationic polymerizable compound, a polyol compound, and a photocationic polymerization initiator.

2. Preferably, the photoradical polymerizable compound is an ester of polyalcohol and (meth) acrylic acid, 1,4-cyclohexanediacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, Pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropanthry (meth) acrylate, trimethylol ethanetri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) One or more monomers selected from the group consisting of acrylates and pentaerythritol hexa (meth) acrylates, and
One or more oligomers selected from the group consisting of polyester (meth) acrylates, epoxy (meth) acrylates, and polyether (meth) acrylates, and one or more selected from the group consisting of polyether (meth) acrylates.

3. 3. Preferably, the photoradical polymerization initiator is one or more selected from the group consisting of acetophenones, benzoins, acylphosphine oxides, titanocene, benzophenones, and thioxanthones initiators.

4. Preferably, the epoxy-based photocationic polymerizable compound and the polyol compound are contained so as to satisfy the following formula 1.
[Formula 1]
1 ≤ R ≤ 15
(In the formula, R is an epoxy equivalent / alcohol equivalent, the epoxy equivalent is represented by the formula 2, and the alcohol equivalent is represented by the formula 3.)
[Formula 2]
Σ {Content of epoxy-based photocationic polymerizable compound (g) / Epoxy group equivalent of epoxy-based photocationically polymerizable compound (g / eq)}
[Formula 3]
Σ {Polyol compound content (g) / Hydroxy group equivalent of polyol compound (g / eq)}

5. Preferably, the R is 1.5 to 10.

6. Preferably, the epoxy-based photocationic polymerizable compound is 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4). -Epoxy) cyclohexane-meth-dioxane, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, vinylcyclohexene monooxide, 1,2-epoxy-4- Vinyl cyclohexane, bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, bisphenol F epoxy resin, novolak epoxy resin, alicyclic epoxy resin, brominated epoxy resin, rubber-modified epoxy resin, urethane-modified epoxy resin, glycidyl ester compound, epoxy One or more selected from the group consisting of polybutadiene and epoxidized SBS.

7. Preferably, the polyol compound is a polyester polyol; a polycarbonate polyol; a polyethylene glycol; a polypropylene glycol; a polycaprolactone polyol; a polytetramethylene glycol; a tetramethyltrimethylol and a polyol derived from it; a glycerin and a polyol derived from it; a penta. It is selected from the group consisting of erythritol tetraalcohol and polyol derived from it; dipentaerythritol hexaalcohol and polyol derived from it; polyacrylate polyol which is an alcohol (macromer type) contained in the polymer side chain; polyvinyl alcohol; One or more.

8. Preferably, the photocationic polymerization initiator is 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 and an aluminum complex / silyl ether. One or more.

9. Preferably, it further contains one or more solvents selected from the group consisting of ketone solvents, acetate solvents and hydrocarbon solvents.

10. The hard coat film according to the present invention includes a hard coat layer formed from the composition for forming a hard coat layer according to any one of items 1 to 9 on at least one surface of a base material.

11. Preferably, the hard coat layer has a rigidity value of 7 to 12 kPa · mm represented by the following mathematical formula 4.
[Formula 4]
Rigidity (kPa · mm) = elastic modulus (GPa) x layer thickness (μm)

12. The image display device according to the present invention includes the hard coat film according to item 10.

According to the composition for forming a hard coat layer of the present invention, both a photocationic polymerization system and a photoradical polymerization system are included, and radical polymerization and cationic polymerization are performed together at the time of curing. As a result, an interpenetrating polymer network structure (IPN) can be formed, and a hard coat layer exhibiting excellent hardness and flexibility can be formed at the same time.

Further, according to the composition for forming a hard coat layer of the present invention, the hardness and flexibility are further improved by adjusting the equivalents of the epoxy group and the hydroxy group to a specific range, whereby scratch resistance and adhesion are obtained. Can be improved, curl is suppressed, and a hard coat layer having excellent crack resistance against bending can be formed.

The present invention exhibits excellent hardness and flexibility by including a photoradical polymerizable compound, a photoradical polymerization initiator, an epoxy-based photocationic polymerizable compound, a polyol compound, and a photocationic polymerization initiator. The present invention relates to a composition for forming a hard coat layer, which is capable of forming a hard coat layer having improved scratch resistance and adhesion, suppressing curling, and having excellent crack resistance against bending.

Hereinafter, the present invention will be described in detail.

<Composition for forming a hard coat layer>
The composition for forming a hard coat layer of the present invention contains a photoradical polymerizable compound, a photocationic polymerizable compound, a photoradical polymerization initiator, and a photocationic polymerization initiator.

As described above, the composition for forming a hard coat layer of the present invention can form interpenetrating polymers by curing by containing different curing systems, and can improve hardness and flexibility.

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

As the photoradical polymerizable monomer, a polyfunctional (meth) acrylate having 2 to 6 functions can be used. Specific examples include an ester of polyalcohol and (meth) acrylic acid (for example, ethylene glycol di (meth) acrylate), 1,4-cyclohexanediacrylate, 1,4-butanediol diacrylate, and 1,6-hexane. Didiol diacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropanthry (meth) acrylate, trimethylol ethanetri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol There are penta (meth) acrylate, pentaerythritol hexa (meth) acrylate and the like. These can 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 can be used alone or in combination of two or more.

The content ratio of the photoradical polymerizable monomer and the oligomer is not particularly limited and can be appropriately selected in consideration of workability and the like, but can be contained in a ratio of, for example, 0:10 to 10: 0.

The photoradical polymerizable compound according to the present invention is preferably a neutral or acidic compound containing a radically polymerizable functional group and not basic. This is because if it is basic, it may react with hydrogen ions during cation curing to reduce cation curing. Examples of such compounds include compounds containing a nitrogen atom, and specific examples thereof include urethane (meth) acrylate, melamine (meth) acrylate, acrylomorpholine, and normal vinylpyrrolidone.

The photoradical polymerization initiator is not particularly limited as long as it can form radicals by irradiation with light.

Photoradical polymerization initiators include type I initiators that generate radicals by decomposition of molecules due to differences in chemical structure or molecular bond energy, and type II initiators that generate radicals by abstraction of hydrogen. Type I initiators and type II initiators can be used alone or in combination.

Specific examples of type I initiators that can be used include 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyltrichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl. Propane-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropane-1-one, Acetphenones such as 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenyl ketone; benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzyl dimethyl ketal; Acylphosphenyl oxides; titanocene; etc. may be mentioned. These can be used alone or in combination of two or more.

Specific examples of type II initiators that can be used include benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzol-4'-methyldiphenylsulfide, 3,3'-methyl. Benzophenones such as -4-methoxybenzophenone; thioxanthones such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone; and the like. These can be used alone or in combination of two or more.

The content of the photoradical 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 photoradical polymerizable compound. If the content is less than 0.1 parts by weight, curing does not proceed sufficiently, and it may be difficult to realize the mechanical properties and adhesion of the hard coat layer. If it exceeds 20 parts by weight, adhesion due to curing shrinkage may occur. Problems such as poor force, cracks, and curl may occur.

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

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

Examples of the resin include bisphenol A epoxy resin, hydride bisphenol A epoxy resin, bisphenol F epoxy resin, novolak epoxy resin, alicyclic epoxy resin, brominated epoxy resin, rubber-modified epoxy resin, urethane-modified epoxy resin, and glycidyl ester. Examples include compounds, epoxidized polybutadiene, epoxidized SBS (SBS means styrene-butadiene-styrene copolymer) and the like. These can be used alone or in combination of two or more.

The epoxy group equivalent of the epoxy-based photocationic polymerizable compound according to the present invention is not particularly limited, and may be, for example, 50 to 500 g / eq. If the equivalent is less than the above range or exceeds the above range, it may be difficult to satisfy the equivalent ratio of Equation 1 described later. Further, if the epoxy group equivalent is less than 50 g / eq, the curing efficiency is low and it is difficult to efficiently form the interpenetrating molecular network structure, so that the hardness may decrease, and if the equivalent exceeds 500 g / eq. , The curing density becomes low, and it may be difficult to achieve sufficient hardness as well.

The polyol compound is used together with a photocationically polymerizable compound and is a component that further improves the flexibility and the degree of curing of the hard coat layer.

The polyol according to the present invention is an oligomer containing 1 to 6 hydroxy groups, preferably 2 to 4 hydroxy groups per molecule, and may have, for example, a number average molecular weight of 100 to 5000.

The structure of the alcohol is not particularly limited, and it may be a primary, secondary or tertiary alcohol, but it is preferably a primary alcohol 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; tetramethyltrimethylol and a polyol derived from it; glycerin and a polyol derived from it; Pentaerythritol tetraalcohol and polyol derived from it; dipentaerythritol hexaalcohol and polyol derived from it; polyacrylate polyol which is an alcohol (macromer type) contained in the polymer side chain; polyvinyl alcohol; and the like. These can be used alone or in combination of two or more.

The hydroxy group equivalent of the polyol according to the present invention is not particularly limited and may be, for example, 20 to 2500 g / eq. If the equivalent is less than the above range or exceeds the above range, it may be difficult to satisfy the equivalent ratio of Equation 1 described later. Further, if the hydroxy group equivalent is less than 20 g / eq, the flexibility of the hard coat layer may decrease, and if it exceeds 2500 g / eq, the viscosity may increase, the processability may decrease, and curing may occur. The density becomes low, and it may be difficult to secure mechanical properties.

The epoxy-based photocationic polymerizable compound and the polyol compound can be included so as to satisfy the following formula 1.

[Formula 1]
1 ≤ R ≤ 15
(In the formula, R is the total epoxy group equivalent of the epoxy-based photocationic polymerizable compound / the total hydroxy group equivalent of the polyol compound.)

The total epoxy group equivalent of the epoxy-based photocationic polymerizable compound can be expressed by the following mathematical formula 2.

[Formula 2]
Σ {Content of epoxy-based photocationic polymerizable compound (g) / Epoxy group equivalent of epoxy-based photocationically polymerizable compound (g / eq)}

The total hydroxy group equivalent of the polyol compound can be expressed by the following formula 3.

[Formula 3]
Σ {Polyol compound content (g) / Hydroxy group equivalent of polyol compound (g / eq)}

Formula 2 is the sum of the epoxy group equivalents of various epoxy-based photocationic polymerizable compounds, and Formula 3 is the sum of the hydroxy group equivalents of various polyol compounds.

As a specific example of Formula 2, when 80 g of a polymerizable compound having an epoxy group equivalent of 160 g / eq is contained alone, the total epoxy group equivalent of the epoxy-based photocationic polymerizable compound is 0.5. When 40 g of a polymerizable compound having an epoxy group equivalent of 160 g / eq and 60 g of a polymerizable compound having an epoxy group equivalent of 120 g / eq are contained, the total epoxy group equivalent of the epoxy-based photocationic polymerizable compound is 0.25. And 0.5, which is 0.75. Such a calculation is similarly applied to Equation 3.

If R represented by the formula 1 is less than 1, the hardness and reliability of the hard coat layer may decrease, and if it exceeds 15, the curing rate becomes slow, the yield of the process decreases, and the hard coat layer becomes hard. The flexibility of the coat layer may decrease. From the viewpoint of simultaneously exhibiting excellent hardness and flexibility, R may be preferably 1.5 to 10.

The photocationic polymerization initiator is not particularly limited as long as it can form a cation by light irradiation, and is, for example, an iron-allene complex compound, an aromatic diazonium salt, an aromatic iodonium salt, an aromatic sulfonium salt, a pyridinium salt, and the like. Examples include aluminum composite / silyl ether. These can be used alone or in combination of two or more.

Specific examples of commercially available photocationic polymerization initiators that can be used include IRGACURE 250 (manufactured by BASF), OPTOMER SP-150, OPTOMER SP-151, OPTOMER SP-170, and OPTOMER SP-171 (all manufactured by Asahi Denka Kogyo Co., Ltd.). ), UVE-1014 (manufactured by General Electric Co., Ltd.), CD-1012 (manufactured by Sartmer Co., Ltd.), SANAID SI-100L (manufactured by Sanshin Chemical Industry Co., Ltd.), CI-2064, CI-2339, CI-2624, CI-2481 (manufactured by Sanshin Chemical Industry Co., Ltd.) (Manufactured by Nippon Soda), RHODORISIL Photoinitiator 2074 (manufactured by Rhone Poulenc GmbH), UVI-6990 (manufactured by Union Carbide), BBI-103, MPI-103, TPS-103, MDS-103, DTS-103, NAT -103, NDS-103 (all manufactured by Midori Kagaku Co., Ltd.) and the like can be mentioned.

The mixing ratio of the photoradical polymerizable compound and the photocationic polymerizable compound is not particularly limited, and for example, 50 to 200 parts by weight of the photocationic polymerizable compound is preferably used with respect to 100 parts by weight of the photoradical polymerizable compound. Can be included in 80-120 parts by weight. When the mixing ratio is out of the above range, it is difficult to sufficiently form the interpenetrating polymer network structure, so that the effect of improving hardness and flexibility may decrease.

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

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

However, the reaction can be inhibited with an alcohol solvent (methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol, methyl cellosolve, ethyl cellosolve, propyl cellosolve, etc.) that can participate in the reaction of the photocationic polymerizable compound described above. It is preferably not contained in an alkaline solvent (normal methylpyrrolidone, dimethylformamide, N, N-dimethylacetamide, etc.).

For example, ketone type (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, etc.); acetate type (methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxyacetate, etc.); hydrocarbon type (normal hexane, normal hexane, etc.) Normal heptane, benzene, toluene, xylene, etc.); etc. These can be used alone or in combination of two or more.

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

Inorganic particles are components that improve mechanical properties such as wear resistance and scratch resistance of the hard coat layer.

The inorganic particles preferably have an average particle size of 1 nm to 100 nm, and more preferably 5 nm to 50 nm. If the average particle size is less than 1 nm, aggregation occurs in the composition and it is difficult to form a uniform coating film, and if it exceeds 100 nm, the optical properties and mechanical properties of the hard coat layer deteriorate. Sometimes.

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 These alloy particles may be used, preferably Al ₂ O ₃ , SiO ₂ , ZrO _2, or alloy particles thereof. These can be used alone or in combination of two or more.

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

The inorganic particles can be contained, for example, in an amount of 5 to 80% by weight, 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. No.

The leveling agent is a component that imparts smoothness and coating properties to the coating film.

Examples of the leveling agent include a silicon-based leveling agent, a fluorine-based leveling agent, and an acrylic polymer-based leveling agent. These can be used alone or in combination of two or more.

Specific examples of commercially available leveling agents that can be used include BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377, BYK-378, and TEGO of Big Chemie. TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 440, TEGO Glide 440, TEGO Glide 450, TEGO Examples thereof include 2300, TEGO Rad 2500, FC-4430 and FC-4432 from 3M.

The leveling agent can be contained, 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 due to ultraviolet irradiation.

Examples of the ultraviolet stabilizer include an absorbent classified by the mechanism of action, a quencher (Quenchers), a hindered amine light stabilizer (HALS, Hindered Amine Light Stabilizer), and the like; and a phenyl salicylate classified by a chemical structure (Phenyl Salicylates, absorption). Agent), benzophenone (absorbent), benzotriazole (absorber), nickel derivative (quenching agent), free group capture agent (Radical Scavenger); and the like can be used. These can be used alone or in combination of two or more.

Examples of the heat stabilizer include polyphenol-based primary heat stabilizers, phosphite-based secondary heat stabilizers, lactone-based heat stabilizers, and the like. These can be used alone or in combination of two or more.

According to the above-mentioned composition for forming a hard coat layer of the present invention, a hard coat layer having significantly improved hardness and flexibility can be formed. As a result, the hard coat layer formed from the composition of the present invention is excellent in hardness, scratch resistance and adhesion, curl is suppressed, and crack resistance against bending is excellent.

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

The hard coat film of the present invention includes a base film having a hard coat layer formed from the composition on at least one surface.

The base film can be used without limitation as long as it is a transparent polymer film, for example, triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, polystyrene. , Polyester, Polyetherimide, Polyacrylic, Polyester, Polyethersulfone, Polysulfone, Polyester, Polyester, Polymethylpentene, Polyvinyl chloride, Polyvinylidene chloride, Polyvinyl alcohol, Polyvinylacetal, Polyetherketone, Polyetheretherketone, Poly It may be a film formed from a polymer such as ether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polycarbonate. These polymers can be used alone or in admixture of two or more.

Of the base films, crystalline polymer base films, engineering plastic base films, and polymer base films whose surface has changed to hydrophilic due to hydrolysis or saponification, which are difficult to impart adhesive force after coating, are usually used. When the composition for forming a hard coat layer is used, it may be difficult to increase the adhesive force, or the mechanical properties may be deteriorated due to this. However, the above-mentioned composition for forming a hard coat layer of the present invention can realize excellent adhesion to these base films without deteriorating mechanical properties.

The base film may have undergone surface treatment such as plasma treatment or corona treatment in order to improve the adhesion to the hard coat layer.

The hard coat layer is formed by applying a composition for forming a hard coat layer on a base film and curing the composition. For application, slit coating method, knife coating method, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, spray coating method, screen Known methods such as a printing method, a gravure printing method, a flexo printing method, an offset printing method, an inkjet coating method, a dispenser printing method, a nozzle coating method, and a capillary coating method can be used.

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

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

[Formula 4]
Rigidity (kPa · mm) = elastic modulus (GPa) x layer thickness (μm)

The rigidity parameter represented by the mathematical formula 4 derives a specific relationship between the elastic modulus and the thickness, which affect the hardness and bending characteristics of the film. The hard coat layer formed from the composition of the present invention can simultaneously improve the hardness and bending properties that are in a contradictory relationship by exhibiting a rigidity value in a specific range. Therefore, the resistance to fatigue fracture is greatly improved, and the application to the flexible display is facilitated.

The elastic modulus of the hard coat layer according to the present invention is not particularly limited as long as it satisfies the rigidity relationship of the above formula 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 secure the hardness, and if it is more than the above range, the durability may be lowered when folded. By adjusting the elastic modulus to an appropriate range at the same time as the thickness, the rigidity value of the equation 4 can be satisfied.

The present invention also provides an image display device provided with the hard coat film.

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

The image display device may be various image display devices such as a normal liquid crystal display device, a field emission display device, a plasma display device, and a field emission display device.

Hereinafter, suitable examples will be shown to aid the understanding of the present invention, but these examples merely exemplify the present invention and do not limit the scope of the attached claims, and are within the scope of the present invention. And it is clear to those skilled in the art that changes to the examples are diverse and amendable within the scope of the technical idea, and within the scope of the claims to which such changes and amendments are attached. It is natural to belong.

Production example 1. Production of Radical Polymerizable Composition (A-1)
55 parts by weight of hexafunctional acrylate DPEA-12 (manufactured by Nippon Kayaku Co., Ltd.), 40 parts by weight of bifunctional acrylate M-280 (manufactured by Miwon Specialty Chemical), and 5 parts by weight of photoinitiator Irgacure-184 (manufactured by BASF). Was mixed to prepare a radically polymerizable composition.

Production example 2. Production of radically polymerizable compound (A-2)
6-functional acrylate DPEA-12 (manufactured by Nippon Kayaku Co., Ltd.) 30 parts by weight, 10-functional urethane acrylate oligomer UV-1700 (manufactured by SK-cytec) 25 parts by weight, Nanocryl C165 (manufactured by Ebonic) 40 parts by weight, A radically polymerizable composition was prepared by mixing with 5 parts by weight of the photoinitiator Irgacure-184 (manufactured by BASF).

Production example 3. Production of Cationic Polymerizable Composition (B)
A cationically polymerizable composition was prepared according to the composition and parts by weight shown in Table 1 below.

Examples and Comparative Examples A composition for forming a hard coat layer was prepared according to the composition and parts by weight shown in Table 2 below.

Manufacture and Evaluation of Hard Coat Film The compositions of Examples and Comparative Examples were coated on one surface of a polyimide film (manufactured by Mitsubishi Gas Chemical Company, Ltd., 100 μm, L-3430) so that the thickness after drying was 20 μm. It was dried in an oven at 80 ° C. for 5 minutes. Then, it was cured by a metal halide lamp (FE) with a light amount of 1000 mJ, and post-treated in an oven at 80 ° C. for 30 minutes to produce a hard coat film.

(1) Pencil hardness Using a pencil hardness tester (PHT, manufactured by Sokubo Kagaku Co., Ltd., Korea), the pencil hardness was measured by applying a load of 500 g. For pencils, Mitsubishi products were used, and experiments were conducted 5 times for each pencil hardness, and the maximum pencil hardness indicated by scratches of 1 time or less was defined as the pencil hardness of the hard coat layer.

(2) Scratch resistance Using a steel wool tester (WT-LCM100, manufactured by Korea Protech Co., Ltd.), the scratch resistance was tested by reciprocating 10 times under 1 kg / (2 cm × 2 cm). As the steel wool, # 0000 was used.
S: 0 scratches A: 1 to 10 scratches B: 11 to 20 scratches C: 21 to 30 scratches D: 31 or more scratches

(3) Adhesion Eleven cuts were made vertically and horizontally at 1 mm intervals on the surface coated with the film to create 100 squares. Then, a peeling test was performed three times using a tape (CT-24, manufactured by Nichiban Co., Ltd.), and the average value of the number of peeled quadrangles was recorded.
Adhesion was recorded as follows.
Adhesion = n / 100
(N: Number of quadrangles not peeled out of all quadrangles, 100: Number of quadrangles in total)
When none of them was peeled off, it was recorded at 100/100.

(4) Curl A sample cut to A4 size (29.7 x 21.0 cm) was placed on a flat glass plate with the film-coated side facing up, and separated from the square glass plate. The distance was measured at 25 ° C. and 50% RH, and the average value was taken as the measured value.
S: 0-10 mm
A: Over 10 mm to 20 mm
B: Over 20 mm to 30 mm
C: Over 30 mm to 40 mm
D: Over 40 mm

(5) Mandrel In order to evaluate crackability, a coated film sample cut into a size of 1 cm × 10 cm is placed on an iron rod having a diameter (2φ to 10φ), and the coat layer is turned up. Folded by hand to indicate the smallest diameter without cracks on the surface.

As can be seen from the above table, the hard coat film provided with the hard coat layer produced from the composition for forming the hard coat layer of the examples is excellent in pencil hardness and scratch resistance of the hard coat layer, and also to the film. Has excellent adhesion. Further, the curl of the hard coat film is reduced, and the crack resistance against bending is excellent.

On the other hand, in the case of the comparative example, it can be confirmed that the flexibility and crack resistance to bending are low, or the hardness is extremely low.

Claims (12)

A composition for forming a hard coat layer containing a photoradical polymerizable compound, a photoradical polymerization initiator, an epoxy-based photocationic polymerizable compound, a polyol compound, and a photocationic polymerization initiator. The photoradical polymerizable compound includes an ester of polyalcohol and (meth) acrylic acid, 1,4-cyclohexanediacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and pentaerythritol tetra (). Meta) Acrylate, Pentaerythritol Tri (Meta) Acrylate, Trimethylol Propantri (Meta) Acrylate, Trimethylol Ethantri (Meta) Acrylate, Dipentaerythritol Tetra (Meta) Acrylate, Dipentaerythritol Penta (Meta) Acrylate, and Penta One or more monomers selected from the group consisting of erythritol hexa (meth) acrylate, and
1 The composition for forming a hard coat layer according to the above. The photoradical polymerization initiator is one or more selected from the group consisting of acetophenones, benzoins, acylphosphine oxides, titanocenes, benzophenones, and thioxanthones initiators, according to claim 1. Composition for forming a hard coat layer. The epoxy-based photocationic polymerizable compound and the polyol compound are described in the following formula 1
[Formula 1]
1 ≤ R ≤ 15
(In the formula, R is an epoxy equivalent / alcohol equivalent, the epoxy equivalent is represented by the formula 2, and the alcohol equivalent is represented by the formula 3 [Formula 2].
Σ {Content of epoxy-based photocationic polymerizable compound (g) / Epoxy group equivalent of epoxy-based photocationically polymerizable compound (g / eq)}
[Formula 3]
Σ {Polyol compound content (g) / Hydroxy group equivalent of polyol compound (g / eq)})
The composition for forming a hard coat layer according to claim 1, which is contained so as to satisfy the above conditions. The composition for forming a hard coat layer according to claim 4, wherein R is 1.5 to 10. The epoxy-based photocationic polymerizable compound includes 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate and 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane. -Meta-dioxane, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, vinylcyclohexene monooxide, 1,2-epoxy-4-vinylcyclohexane, bisphenol A epoxy resin, hydride bisphenol A epoxy resin, bisphenol F epoxy resin, novolak epoxy resin, alicyclic epoxy resin, brominated epoxy resin, rubber modified epoxy resin, urethane modified epoxy resin, glycidyl ester compound, epoxidized polybutadiene and epoxy The composition for forming a hard coat layer according to claim 1, which is one or more selected from the group consisting of chemical SBS. The polyol compounds are polyester polyol; polycarbonate polyol; polyethylene glycol; polypropylene glycol; polycaprolactone polyol; polytetramethylene glycol; tetramethyltrimethylol and a polyol derived from it; glycerin and a polyol derived from it; pentaerythritol tetraalcohol and One or more selected from the group consisting of a polyol derived from it; a dipentaerythritol hexaalcohol and a polyol derived from it; a polyacrylate polyol which is an alcohol (macromer type) contained in a polymer side chain; a polyvinyl alcohol; The composition for forming a hard coat layer according to claim 1. The photocationic polymerization initiator is one or more selected from the group consisting of an iron-allene complex compound, an aromatic diazonium salt, an aromatic iodonium salt, an aromatic sulfonium salt, a pyridinium salt and an aluminum complex / silyl ether. The composition for forming a hard coat layer according to claim 1. The composition for forming a hard coat layer according to claim 1, further comprising one or more solvents selected from the group consisting of a ketone solvent, an acetate solvent, and a hydrocarbon solvent. A hard coat film comprising a hard coat layer formed from the composition for forming a hard coat layer according to any one of claims 1 to 9 on at least one surface of a base material. The hard coat layer is
[Formula 4]
Rigidity (kPa · mm) = elastic modulus (GPa) x layer thickness (μm)
The hard coat film according to claim 10, wherein the value of rigidity represented by is 7 to 12 kPa · mm. An image display device including the hard coat film according to claim 10.