KR101854157B1 - Hard coating film and polarizing plate and image display device comprising the same - Google Patents

Abstract

More particularly, the present invention relates to a hard coating film formed on at least one side of a base film and having excellent rigidity and flexibility by satisfying specific rigidity parameter values and specific shrinkage values. A polarizing plate including the hard coating film, and an image display device.

Description

Technical Field [0001] The present invention relates to a hard coating film, a polarizing plate including the same,

The present invention relates to a hard coating film, a polarizing plate including the same, and an image display device, and more particularly, to a hard coating film having excellent hardness and flexibility, a polarizing plate including the same and an image display device.

Polarizing plates used in various image display devices such as a liquid crystal display (LCD), an electroluminescence (EL) display, a plasma display (PDP), a field emission display (FED) and an OLED are generally made of polyvinyl alcohol alcohol, PVA) film comprises a polarizer in which an iodine compound or a dichroic polarizing material is adsorbed and oriented, a polarizer protective film is laminated on one side of the polarizer, and a polarizer protective film, a liquid crystal cell Layer structure in which a pressure-sensitive adhesive layer and a release film are laminated in this order.

In the polarizing plate having such a structure, it is possible to use a hard coating as a polarizer protective film. In the conventional hard coating film, if the thickness of the conventional hard coating film is increased to improve the hardness, the hardness of the obtained hard coating film is improved, Hardness and scratch resistance, as well as insufficient impact resistance.

In addition, the conventional hard coating film has a problem that the curl of the end portion of the hard coating film is increased by the hardening shrinkage and the heat and moisture shrinkage, thereby lowering the processability.

Korean Patent Laid-Open Publication No. 2014-0090291 discloses a method of producing a hard-coated polarizing plate, but does not suggest an alternative to the above-mentioned problem.

Korean Patent Publication No. 2014-0090291

It is an object of the present invention to provide a hardcoat film capable of simultaneously realizing hardness and flexibility and suppressing curling.

It is another object of the present invention to provide a polarizing plate and an image display device including the hard coating film.

1. A hard coat layer formed on at least one surface of a base film,

Wherein the hard coat layer has a rigidity value of 400 to 1,000 as expressed by the following formula (1)

Wherein the hard coat layer satisfies the following shrinkage value represented by the following formula (2): 120 or less Hard coat film:

[Equation 1]

Stiffness (MPa 占 퐉) = Storage modulus (MPa) X Layer thickness (占 퐉)

&Quot; (2) "

Shrinkage (N 占 퐉) = Shrinkage force during curing (N) X Layer thickness (占 퐉).

2. The hard coating film of 1 above, wherein the rigidity value is from 440 to 800.

3. The hard coating film of 1 above, wherein said shrinkable value is from 10 to 100.

4. The hard coating film of 1 above, wherein the hard coating layer has a thickness of 1 to 20 mu m.

5. The hard-coating film according to item 1 above, wherein the hard coat layer is formed from a composition for forming a hard coat layer comprising a photopolymerizable compound and a photopolymerization initiator.

6. The photopolymerizable compound of claim 5, wherein the photopolymerizable 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, trimethylol ethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tetra At least one photopolymerizable monomer selected from the group consisting of dipentaerythritol penta (meth) acrylate and pentaerythritol hexa (meth) acrylate; And

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

7. The hard coat film according to 5 above, wherein said photopolymerization initiator is at least one selected from the group consisting of acetophenones, benzoins, acylphosphine oxides, titanocenes, benzophenones, and thioxanthones initiators.

8. The composition for forming a hard coat layer according to 5 above, wherein the composition is an alcohol-based solvent, a ketone-based solvent, an ether-based solvent, Wherein the hard coating film further comprises at least one solvent selected from the group consisting of an acetate-based solvent and a hydrocarbon-based solvent.

9. The hard coating film of claim 6, wherein the content of the photopolymerizable oligomer to the photopolymerizable monomer is 1:10 to 10: 1.

10. The film of claim 1, wherein the base film is selected from the group consisting of triacetylcellulose, acetylcellulose butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butyrylcellulose, acetylpropionylcellulose, polyester, polystyrene, Polyetherimide, polyacrylate, polyimide, polyether sulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether Wherein the hard coat film is selected from the group consisting of polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate, and polycarbonate.

11. A hardcoat film as in 1 above, wherein the pencil hardness is at least 3 H and the curl amount at the time of curing is not more than 50 mm.

12. A polarizer comprising a polarizer and at least one side of the polarizer to which the hard coating film of any one of claims 1 to 11 is adhered.

13. An image display device comprising the polarizing plate of 12 above.

The hard coat layer of the hard coat film of the present invention satisfies the specific anisotropic parameter value and the specific shrink parameter value, so that it is possible to realize a hard coat film having a high hardness while suppressing curl.

In addition, the hard coating film of the present invention satisfies the above-mentioned parameter values, and thus can realize both excellent hardness and flexibility. Therefore, the present invention is suitable for use in a flexible image display device having the hard coating film and the polarizing plate.

The present invention relates to a hard coating film, a polarizing plate and an image display device having the same, and more particularly, to a hard coating film having excellent hardness by satisfying specific rigidity parameter values and specific shrinkage values, A polarizing plate including the same, and an image display device.

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

< Hard coating  Film>

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

The hard coating layer according to the present invention satisfies the following formula (1), wherein the value of the rigidity parameter is 400 to 1,000 and the shrinkage parameter value of the following formula (2) is 120 or less.

[Equation 1]

Stiffness (MPa 占 퐉) = Storage modulus (MPa) X Layer thickness (占 퐉)

&Quot; (2) &quot;

Shrinkage (N 占 퐉) = Shrinkage force during curing (N) X Layer thickness (占 퐉)

The stiffness parameter represented by the formula (1) is derived from a specific relationship between the modulus of elasticity and the thickness, which affects the hardness and bending properties of the film. The shrinking parameter represented by the formula (2) The specific relationship between the contractile force and the thickness is derived.

As described above, the hard coat layer of the present invention can simultaneously improve the hardness of the opposite relationship and the curl amount at the time of curing by satisfying both the specific anisotropy parameter value and the specific shrinkage parameter value. In particular, Making it easy to apply to displays. In this respect, the stiffness value is preferably 440 to 800. The smaller the shrinkability, the more preferable the lower limit is 10 to 100 although the shrinkability is not particularly limited.

The rigidity value of Equation (1) can be satisfied by simultaneously adjusting the storage elastic modulus and the thickness of the hard coat layer to an appropriate range. For example, in the composition for forming a hard coat layer, the kind of the polymerizable compound, the number of functional groups and / Or by controlling the content ratio of the polymerizable monomer and the oligomer, or by using an additive, the rigidity value of the formula (1) can be satisfied.

The storage elastic modulus of the hard coat layer according to the present invention is not particularly limited as long as it satisfies the stiffness relationship of Equation (1), but may be, for example, 50 to 200 MPa, preferably 100 to 150 MPa. If the storage elastic modulus is less than 100 MPa, it may be difficult to secure hardness. If the storage elastic modulus is more than 150 MPa, the durability may be lowered when folding.

The shrinkability value of the formula (2) can be satisfied by simultaneously adjusting the shrinkage force and the thickness of the hard coat layer during curing to an appropriate range. More specifically, the shrinkability value of the hard coat layer may be determined by the kind of the polymerizable compound, The rigidity value of the above formula (1) can be satisfied by adjusting the content or adjusting the content ratio of the polymerizable monomer and the polymerizable oligomer, or using an additive.

The shrinkage force upon curing of the hard coat layer according to the present invention is not particularly limited as long as it satisfies the shrinkage relationship of the formula (2), but may be, for example, 10 to 100 N, preferably 10 to 50 N. When the shrinkage force is less than 10N, there is a possibility that a film whirling around the substrate side in the durability test may occur. If the shrinkage force is more than 50N, curling may occur.

The thickness of the hard coat layer according to the present invention is not particularly limited as long as it is within a range that satisfies the rigidity range of the formula (1) and the shrinkage range of the formula (2), but may be, for example, Lt; RTI ID = 0.0 &gt; 10 &lt; / RTI &gt;

If the thickness of the hard coat layer is more than 20 占 퐉, it is difficult to secure transparency of the coating film, the uniform film can not be secured and the appearance may be poor, and if it is less than 1 占 퐉, hardening is poor and it is difficult to secure desirable mechanical properties. The thickness of the coating layer can be appropriately adjusted to suit the viscosity of the coating liquid and the apparatus (e.g., a coater) used in the coating process.

The hard coat film of the present invention comprises a substrate film having a hard coat layer formed on at least one side thereof.

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.

< Hard coating layer  Composition for forming &gt;

The hard coat layer according to the present invention can be formed of a composition for forming a hard coat layer comprising a photopolymerizable compound, a photopolymerization initiator and a solvent.

Photopolymerization  compound

The photopolymerizable compound used in the formation of the hard coat layer of the present invention includes a photopolymerizable functional group, and may be a photopolymerizable monomer, a photopolymerizable oligomer, or the like, and may be, for example, a photo-radical polymerizable compound.

The photopolymerizable monomer is a commonly used photocurable functional group, and monomers used in the art having unsaturated groups such as (meth) acryloyl group, vinyl group, styryl group and allyl group in the molecule can be used without limitation And more specifically, for example, monofunctional and / or polyfunctional (meth) acrylates. These may be used alone or in combination of two or more.

In the present invention, "(meth) acrylic-" refers to "methacryl- "," acrylic- "

Specific examples of the (meth) acrylate monomer include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, glycerol tri (meth) acrylate, tris (2- (Meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, Acrylate, diethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, diethylene glycol di (Meth) acrylate, glycidyl (meth) acrylate, bis (2-hydroxyethyl) isocyanurate di Adding poly (meth) acrylate; Oligoester (meth) acrylate, oligoether (meth) acrylate, oligourethane (meth) acrylate and oligoepoxy (meth) acrylate having 1 to 3 (meth) acryloyl groups in the molecule; Hydroxypropyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and ethylene oxide or propylene oxide addition products to the (meth) acrylic acid ester; And mono (meth) acrylic acid esters such as iso-octyl (meth) acrylate, iso-decyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl Acrylate and dipentaerythritol hexa (meth) acrylate, dipentaerythritol hydroxy penta (meth) acrylate, pentaerythritol tetra (meth) acrylate, Ditrimethylolpropane tetra (meth) acrylate, and the like. These may be used alone or in combination of two or more.

As the photopolymerizable oligomer, for example, at least one selected from the group consisting of epoxy (meth) acrylate, urethane (meth) acrylate and polyester (meth) acrylate can be used. Specifically, urethane And a polyester (meth) acrylate may be used in combination, or two kinds of polyester (meth) acrylates may be mixed and used. Preferably, a urethane (meth) acrylate oligomer may be used to improve the scratch resistance and hardness of the cured product and to increase the modulus of the hard coat layer.

The urethane (meth) acrylate can be prepared by reacting a compound having a polyfunctional (meth) acrylate having a hydroxyl group in the molecule and an isocyanate group in the presence of a catalyst according to a method known in the art.

Specific examples of the polyfunctional (meth) acrylate having a hydroxyl group in the molecule include 2-hydroxyethyl (meth) acrylate, 2-hydroxyisopropyl (meth) acrylate, 4-hydroxybutyl , A caprolactone ring-opening hydroxyacrylate, a mixture of pentaerythritol tri / tetra (meth) acrylate, and a mixture of dipentaerythritol penta / hexa (meth) acrylate.

Specific examples of the compound having an isocyanate group include 1,4-diisocyanatobutane, 1,6-diisocyanatohexane, 1,8-diisocyanatooctane, 1,12-diisocyanatododecane, 1,5 Diisocyanato-2-methylpentane, trimethyl-1,6-diisocyanatohexane, 1,3-bis (isocyanatomethyl) cyclohexane, trans-1,4-cyclohexane diisocyanate, -Methylenebis (cyclohexylisocyanate), isophorone diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, xylene-1,4-diisocyanate, tetramethyl xylene- Diisocyanate, 1-chloromethyl-2,4-diisocyanate, 4,4'-methylenebis (2,6-dimethylphenyl isocyanate), 4,4'-oxybis (phenylisocyanate), hexamethylene diisocyanate Derived trifunctional isocyanate, and trimethanepropanol adduct Toluene diisocyanate It may be at least one member selected from the group consisting of a carbonate.

More specifically, the urethane (meth) acrylate oligomer may be a compound having two or more substituents each represented by the following formula (1) and (meth) acroyl group in the molecule.

[Chemical Formula 1]

* -OC (= O) NH- *

The urethane (meth) acrylate oligomer may be one produced by reacting 1 mole of a diisocyanate represented by the following formula (2) with 2 moles of an active hydrogen-containing polymerizable unsaturated compound.

(2)

R ₁ -OC (= O) NH-R ₃ -NHC (= O) OR ₂

In the formulas, R ₁ and R ₂ are each independently a substituent group containing a (meth) acryloyl group derived from an active hydrogen-containing polymerizable unsaturated compound, and R ₃ is a divalent substituent derived from a diisocyanate.

Specific examples of the urethane (meth) acrylate oligomer include reaction of 2-hydroxyethyl (meth) acrylate and 2,4-tolylene diisocyanate, reaction of 2-hydroxyethyl (meth) acrylate and isophorone diisocyanate Reaction of 2-hydroxybutyl (meth) acrylate and 2,4-tolylene diisocyanate, reaction of 2-hydroxybutyl (meth) acrylate and isophorone diisocyanate, reaction of pentaerythritol tri (meth) Reaction of 2,4-toluene diisocyanate, reaction of pentaerythritol tri (meth) acrylate and isophorone diisocyanate, reaction of pentaerythritol tri (meth) acrylate and dicyclohexylmethane diisocyanate, reaction of dipentaerythritol penta (Meth) acrylate and isophorone diisocyanate, the reaction of dipentaerythritol penta (meth) acrylate Di-cycloalkyl may be a product of the reaction of cyclohexyl diisocyanate.

The polyester (meth) acrylate can be prepared by reacting a polyester polyol and acrylic acid according to methods known in the art.

The polyester (meth) acrylate may be, for example, a polyester acrylate, a polyester diacrylate, a polyester tetraacrylate, a polyester hexaacrylate, a polyester pentaerythritol triacrylate, a polyester pentaerythritol tetraacrylate , And polyester pentaerythritol hexaacrylate, but is not limited thereto.

The photopolymerizable monomer and the photopolymerizable oligomer may be used singly or in combination. When the photopolymerizable monomer and the photopolymerizable oligomer are mixed, the workability and compatibility of the composition for forming a hard coating layer may be increased.

The content ratio of the photopolymerizable monomer to the photopolymerizable oligomer is not particularly limited and may be appropriately selected in consideration of the storage modulus, shrinkage and workability of the hard coat layer. For example, the content ratio of the polymerizable oligomer to the polymerizable monomer 1: 10 to 10: 1. When the content ratio of the polymerizable oligomer to the polymerizable monomer is out of the above range, the storage elastic modulus of the hard coat layer may be decreased or the shrinkage may be increased to cause the curling due to the decrease of hardness and flexibility.

The content of the photopolymerizable compound is not particularly limited and may be, for example, 1 to 80 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the composition for forming a hard coat layer. When the amount of the polymerizable compound is less than 1 part by weight, the elastic modulus of the coating layer is decreased and cracks can easily occur in the coating layer at the time of bending. When the amount is more than 80 parts by weight, There may be problems with the characteristics.

Light curing Initiator

The photopolymerization initiator used in the formation of the hard coat layer of the present invention is not particularly limited as long as it can form radicals by light irradiation.

Examples of the photopolymerization initiator include a type 1 initiator that generates a radical by decomposition of a molecule due to a chemical structure or a difference in molecular bonding energy, and a type 2 initiator that generates a radical 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; Titanocene compounds; 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, 2-chromothioxanone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, Thioxanthones and the like. These may be used alone or in combination of two or more.

The content of the photopolymerization initiator is not particularly limited and may be, for example, 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the composition for forming a hard coat layer. When 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 coating layer. If the content is more than 10 parts by weight, problems such as poor adhesion, cracks and curl may occur due to curing shrinkage.

menstruum

The solvent used for forming the hard coat layer of the present invention is not limited as long as it can sufficiently dissolve or disperse the above composition. (Methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone and the like), an ether (for example, methanol, ethanol, isopropanol, butanol, and propylene glycol methoxy alcohol) (Such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether and propylene glycol monomethyl ether), acetate type (methyl acetate, ethyl acetate, butyl acetate, propylene (N-hexane, n-heptane, benzene, toluene, xylene, etc.) and the like can be given as examples of the organic solvent. . These may be used alone or in combination of two or more.

The content of the solvent is not particularly limited and may be, for example, 10 to 95 parts by weight, preferably 40 to 70 parts by weight, based on 100 parts by weight of the composition for forming a hard coat layer.

If the content of the sambarma is less than 10 parts by weight, the viscosity of the composition is low and the workability of the composition is low. In addition, if the sambarma content is more than 95 parts by weight, There may be a problem of low economic efficiency.

In addition, the composition for forming a hard coat layer used for forming the hard coat layer according to the present invention may further include additives such as a leveling agent, a UV stabilizer, and a heat stabilizer.

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 hard coat layer formed from the composition for forming a hard coat layer described above is excellent in hardness and scratch resistance and curl is suppressed.

<Polarizing plate and image display device>

The present invention provides a polarizing plate formed by laminating the hard coating film on at least one surface of a polarizer.

The polarizing plate of the present invention is not particularly limited, but various types can be used. Examples of the polarizing plate include a film obtained by adsorbing a dichroic substance such as iodine or a dichroic dye to a hydrophilic polymer film such as a polyvinyl alcohol film and an ethylene-vinyl acetate copolymerization system partial saponification film to obtain a monoaxially stretched film polyvinyl And a polyene-based oriented film such as a dehydration treatment of alcohol or a dehydrochlorination treatment of polyvinyl chloride. However, the present invention is not limited thereto. Of these, a polarizing plate comprising a polyvinyl alcohol film and a dichromatic material such as iodine can be preferably used.

Further, the present invention relates to an image display apparatus capable of simultaneously securing high hardness and flexibility by incorporating a polarizing plate on which the hard coating film is formed in an image display apparatus, and the image display apparatus of the present invention has, in addition to the above- And may further include a known configuration.

The image display device is not particularly limited and may be various image display devices such as a general liquid crystal display device, an electroluminescence display device, a plasma display device, a field emission display device, and the like. In particular, the hard coating film of the present invention is excellent in hardness and flexibility and can be preferably applied to a flexible display.

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- Hard coating layer  Composition for forming

, 5 parts by weight of 10-functional urethane acrylate (SC2153, available from Mitsubishi Heavy Industries, Ltd.), 35 parts by weight of pentaerythritol triacrylate (MISS SPECIALTY CHEMICAL Co.) as polymerization initiator, and 1 part by weight of Igacure 184 2.00 parts by weight of methyl ethyl ketone, 20 parts by weight of propylene glycol monomethyl ether as a solvent, and 0.2 parts by weight of BYK-333 (BYK Chemie) as a leveling agent were mixed with PP Followed by filtration using a filter made of a material to prepare a composition for forming a hard coat layer.

Manufacturing example  2 and 3

A composition for forming a hard coat layer was prepared in the same manner as in Preparation Example 1, except that the composition and the content (parts by weight) shown in Table 1 were used.

division Polymerizable compound Polymerization initiator menstruum additive ingredient content ingredient content ingredient content ingredient content Production Example 1 A-1 / A-2 5/35 B-1 2.8 C-1 / C-2 37/20 D-1 0.2 Production Example 2 A-3 / A-2 10/30 B-1 2.8 C-1 / C-2 37/20 D-1 0.2 Production Example 3 A-1 / A-2 20/20 B-1 2.8 C-1 / C-2 37/20 D-1 0.2 A-1: 10-functional urethane acrylate (SC2153, manufactured by Miwon Specialty Chemicals)
A-2: Pentaerythritol triacrylate (Miwon Specialty Chemicals)
A-3: 6-functional urethane acrylate (PU620D, manufactured by Miwon Specialty Chemicals)

B-1: Igacure 184 (Shiba, 1-hydroxy-cyclohexyl-phenyl-ketone)

C-1: methyl ethyl ketone
C-2: Propylene glycol monomethyl ether

D-1: BYK-333 (BYK Chemie)

Example  And Comparative Example

On one surface of a triacetyl cellulose film having a thickness of 40 탆, the components and thickness described in Table 2 (after drying) were spin-coated, the solvent was dried at 80 캜 for 1 minute and cured by a high pressure mercury lamp to form a hard coating layer To prepare a hard coating film.

division Composition Film thickness
(탆) Example 1 Production Example 1 5 Example 2 Production Example 1 4 Example 3 Production Example 1 6 Example 4 Production Example 2 5 Example 5 Production Example 2 8 Comparative Example 1 Production Example 3 5 Comparative Example 2 Production Example 1 10 Comparative Example 3 Production Example 2 3

Experimental Example

The following evaluations were carried out using the hard coating films of the Examples and Comparative Examples in Table 2 above.

(1) storage modulus and When curing  Contraction force measurement

The solids of the hard coating compositions of Preparations 1 to 3 were loaded on a rheometer and loaded onto a spindle to maintain a gap of 100 占 퐉. The solids were then cured from the opposite side of the spindle to a UV intensity of 200 mJ and a frequency of 10 Hz, a strain of 0.01% And the storage elastic modulus of the spindle was measured. At this time, the load applied to the spindle was measured by the shrinkage force at the time of curing. Each data used data 20 seconds after curing started. The results are shown in Table 3 below.

 (2) Evaluation of pencil hardness

The hard coat films of Examples and Comparative Examples were subjected to a 500 g load using a pencil hardness tester (PHT, Korea Science and Engineering Co., Ltd.), and pencil hardness was measured. The pencil was a product of Mitsubishi, and the experiment was conducted five times per pencil hardness, and the maximum pencil hardness at which the scratch was less than 3 times was expressed by pencil hardness of the hard coating layer. The results are shown in Table 3 below.

 (3) Evaluation of Curl Generation

The hard coating films of Examples and Comparative Examples were cut into a size of 10 x 10 cm and then allowed to stand at 25 DEG C and 48% RH for 24 hours with a film coated side up on a flat glass plate. Four corners The distance was taken as the average value.

The results were evaluated according to the following evaluation criteria, and the results are shown in Table 3 below.

<Evaluation Criteria>

◎: 20 mm or less

○: 20 mm or more and 50 mm or less

?: More than 50 mm

X: Four corners are completely lifted and the film curls in a cylindrical form

(4) Abrasion resistance  evaluation

The hard coating films of the examples and comparative examples were subjected to reciprocating motion ten times under 1 kg / (2 cm x 2 cm) using a steel wool tester (WT-LCM100, Korea Protec Co.) to test scratch resistance. Steel wool used # 0000.

The results were evaluated according to the following evaluation criteria, and the results are shown in Table 3 below.

<Evaluation Criteria>

◎: Scratches less than 10

○: 11 to 20 scratches

B: 21 to 30 scratches

X: More than 31 scratches

division Storage modulus
(MPa) Contraction force
(N) thickness
(탆) rigidity
(MPa 占 퐉) contractility
(N 占 퐉) Pencil hardness curl Abrasion resistance Example 1 110 20 5 550 100 3H ◎ ◎ Example 2 110 20 4 440 80 3H ◎ ◎ Example 3 110 20 6 660 120 4H ○ ◎ Example 4 100 15 5 500 75 3H ◎ ◎ Example 5 100 15 8 800 120 4H ○ ◎ Comparative Example 1 130 30 5 650 150 3H △ ◎ Comparative Example 2 110 20 10 1100 200 4H X ◎ Comparative Example 3 100 15 3.5 350 52.5 2H ◎ ◎

The results are shown in Table 3. As can be seen from Table 3, it was confirmed that the embodiments satisfying the rigidity and shrinkage according to the present invention exhibited excellent pencil hardness and scratch resistance while suppressing the generation of curl.

However, in the case of the comparative examples which do not satisfy the rigidity and shrinkage according to the present invention, hardness and flexibility can not be secured, and curl is generated.

Claims (13)

And a hard coat layer formed on at least one side of the base film,
Wherein the hard coat layer has a rigidity value of 400 to 1,000 as expressed by the following formula (1)
Wherein the hard coat layer satisfies the following shrinkage value represented by the following formula (2): 120 or less:
[Equation 1]
Stiffness (MPa 占 퐉) = Storage modulus (MPa) X Layer thickness (占 퐉)
&Quot; (2) &quot;
Shrinkage (N 占 퐉) = Shrinkage force during curing (N) X Layer thickness (占 퐉).
The hard coating film for flexible display according to claim 1, wherein the rigidity value is 440 to 800.
The hard coating film for flexible display according to claim 1, wherein the shrinkable value is 10 to 100.
The hard coating film for a flexible display according to claim 1, wherein the hard coating layer has a thickness of 1 to 20 占 퐉.
The hard coating film for a flexible display according to claim 1, wherein the hard coating layer is formed from a composition for forming a hard coating layer comprising a photopolymerizable compound and a photopolymerization initiator.
[6] The photopolymerizable compound according to claim 5, wherein the photopolymerizable compound is selected from the group consisting of esters of polyalcohol and (meth) acrylic acid, 1,4-cyclohexanediacrylate, 1,4-butanediol diacrylate, Acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylol propane tri (meth) acrylate, trimethylol ethane tri (meth) acrylate, dipentaerythritol tetra At least one photopolymerizable monomer selected from the group consisting of erythritol penta (meth) acrylate and pentaerythritol hexa (meth) acrylate; And
At least one photopolymerizable oligomer selected from the group consisting of polyester (meth) acrylate, epoxy (meth) acrylate and polyether (meth) acrylate. .
[Claim 6] The hard coating film for flexible display according to claim 5, wherein the photopolymerization initiator is at least one selected from the group consisting of acetophenones, benzoins, acylphosphine oxides, titanocenes, benzophenones, and thioxanthones initiators.
[6] The composition for forming a hard coat layer according to claim 5, wherein the composition for forming the hard coat layer is an alcohol-based solvent, a ketone-based solvent, an ether-based solvent, Wherein the hard coating film further comprises at least one solvent selected from the group consisting of an acetate-based solvent and a hydrocarbon-based solvent.
The hard coating film for flexible display according to claim 6, wherein the content of the photopolymerizable oligomer to the photopolymerizable monomer is 1:10 to 10: 1.
[4] The method according to claim 1, wherein the base film is formed of at least one selected from the group consisting of triacetylcellulose, acetylcellulose butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butyrylcellulose, acetylpropionylcellulose, polyester, polystyrene, polyamide, Polyethersulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, Wherein the hard coating film is selected from the group consisting of polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and polycarbonate.
The hard coating film for flexible display according to claim 1, wherein the pencil hardness is 3H or more and the curl amount when cured is 50 mm or less.
A polarizer comprising a polarizer and a hard coating film for a flexible display according to any one of claims 1 to 11 attached to at least one side of the polarizer.
A flexible display device comprising the polarizer of claim 12.