KR20140084613A - Anti-reflection film and polarising plate includig the same - Google Patents

Abstract

More particularly, the present invention relates to an antireflection film and a polarizing plate comprising the same, and more particularly, to a polarizing plate comprising a transparent substrate having a surface roughness (Ra) of 0.5 nm or more and a wavelength range A hard coat layer formed by curing a composition for forming a hard coat layer containing not more than 10 parts by weight of a photoinitiator of 350 to 450 nm is formed on the hard coat layer and a physical adhesion force at the interface between the hard coat layer and the low refractive layer To an antireflection film exhibiting excellent physical properties such as transmittance, haze, scratch resistance, pencil hardness and the like, and a polarizing plate comprising the antireflection film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an antireflection film,

The present invention relates to an antireflection film excellent in chemical resistance and a polarizing plate comprising the same.

In order to prevent scratches and the like, a polarizing plate is mounted with a cover plate made of glass or plastic. However, this is disadvantageous in terms of cost and weight, and a polarizing plate hard-coated on the surface is recently used.

The hard-coated polarizing plate is usually implemented by attaching a hard coating film having a hard coat layer formed on a transparent plastic film substrate to the polarizing plate surface.

However, the display with the hard coating film performs reflection prevention treatment because light is reflected on the surface of the polarizing plate and visibility is lowered.

The antireflection treatment is designed to reduce the refractive index by producing a single layer laminate composed of a thin film multilayer laminate or a low refractive index material made of a material having a different refractive index. Considering the simplicity and economy of the double process, a single-layer laminate is preferable.

The antireflection-treated hard coat film has a weak interlayer adhesion and tends to cause interfacial destruction with the hard coat layer, so that it is difficult to satisfy durability such as film strength and chemical resistance.

A method of improving the adhesion at the laminated interface between the hard coat layer and the antireflection layer by various surface modification treatments such as corona discharge treatment has been proposed (Japanese Patent Application Laid-Open No. 9-222503).

However, the above method has disadvantages in that the film strength and chemical resistance are improved, but the non-uniformity of the hard coating layer and uneven application of the antireflection layer due to this tend to occur, making it difficult to realize antireflection characteristics.

Also, an antireflection hard coat film has been proposed in which the antireflection layer has excellent adhesion to a high refractive index hard coat layer (JP-A-9-226062). However, it is difficult to satisfy the hardness together with the adhesion by the reactive organosilicon compound contained in the high refractive index hard coat layer.

The present invention provides an antireflection film having excellent chemical resistance by improving the adhesion between the hard coating layer and the low refractive layer without decreasing the transmittance, haze, scratch resistance and pencil hardness characteristics, And the like.

It is another object of the present invention to provide a polarizing plate comprising the antireflection film.

In order to attain the above object, the present invention provides a transparent substrate, comprising at least one surface of a transparent substrate and having a surface roughness (Ra) of 0.5 nm or more and a wavelength range of 350 to 450 nm based on 100 parts by weight of solid content in the total composition, And a low refractive index layer is formed on the hard coating layer. The antireflection film according to claim 1, wherein the cured hard coating layer is formed on the hard coating layer.

Preferably, the hard coat layer has a surface roughness (Ra) of 0.5 to 10 nm.

The photoinitiator may be selected from the group consisting of 2-methyl-1- [4- (methylthio) phenyl] 2-morpholinopropanone-1, diphenyl ketone benzyl dimethyl ketal, 2- , 4-hydroxycyclophenyl ketone, dimethoxy-2-phenylacetophenone, anthraquinone, fluorene, triphenylamine, carbazole, 3-methylacetophenone, (4,4-diaminobenzophenone), 1-hydroxycyclohexyl phenyl ketone, benzophenone, and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide .

The composition for forming a hard coat layer may contain 90 to 99.95 parts by weight of a (meth) acrylate monomer and 0.05 to 10 parts by weight of a photoinitiator having a wavelength range of 350 to 450 nm, based on 100 parts by weight of the solid content of the entire composition .

The refractive index of the low refraction layer may be 1.2 to 1.49 at 25 占 폚.

The present invention also provides a polarizing plate provided with the antireflection film.

The antireflection film of the present invention improves the physical adhesion at the interface between the hard coat layer and the low refractive index layer in the formation of the low refractive layer on the hard coat layer, so that the antireflection film is excellent in chemical resistance and has a transmittance, haze, scratch resistance , Pencil hardness, and the like, and thus can be usefully applied to polarizing plates and display devices.

The present invention relates to an antireflection film excellent in chemical resistance and a polarizing plate comprising the same.

Hereinafter, the present invention will be described in detail.

The antireflection film of the present invention is characterized in that at least one surface of a transparent substrate contains 10 parts by weight or less of a photoinitiator having a surface roughness (Ra) of 0.5 nm or more and a wavelength range of 350 to 450 nm based on 100 parts by weight of a solid content in the whole composition A cured hard coat layer is formed, and a low refractive layer is formed on the hard coat layer.

The present invention controls the surface roughness of the hard coat layer by using a composition for forming a hard coat layer in which the content of the photoinitiator is controlled to a specific range. The chemical resistance of the interface can be increased by controlling the surface roughness of the hard coat layer to improve the physical adhesion of the interface between the hard coat layer and the low refractive layer.

Preferably, the hard coat layer has a surface roughness (Ra) of 0.5 to 10 nm. If the surface roughness is less than 0.5 nm, there may occur a problem that the low refraction layer coated on the upper surface of the hard coating layer is peeled off during the saponification treatment.

The composition for forming a coating layer contains a (meth) acrylate-based monomer and a photoinitiator having a wavelength range of 350 to 450 nm.

(Meth) acrylate monomers are included to improve the hardness of the hard coating layer and to improve the curling property.

The (meth) acrylate monomer may be any of those generally used in the art. Preferably, the (meth) acrylate monomer is selected from the group consisting of dipentaerythritol penta / hexa (meth) acrylate, pentaerythritol tri / tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, (meth) Acrylate, trimethylolpropane tri (meth) acrylate, glycerol tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate, tri (meth) acrylate, ethylene glycol di (meth) Acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,3-butanediol di (meth) Acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, bis (2- hydroxyethyl) isocyanurate di (Meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, isooctyl (Meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, isobonol (meth) acrylate and the like.

The content of the (meth) acrylate monomer is not limited, but it is preferable that the composition for forming a hardcoat film is contained in an amount of 90 to 99.95 parts by weight, more preferably 92 to 99.5 parts by weight It is preferable that it is contained. If the content is less than 90 parts by weight, cracking may occur due to over-curing. If the content is more than 99.95 parts by weight, physical properties may be deteriorated due to uncured.

A photoinitiator having a wavelength range of 350 to 450 nm can be applied without limitation as long as it is generally used in the art.

Specific examples of the photoinitiator include bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenyl Phosphonate, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, phenyl- bis (2,4,6-trimethylbenzoyl) phosphine oxide, Bistrichloromethyl-6-p-methoxystyryl-s-triazine, 2-p-methoxystyryl-4,6-bisttrichloromethyl-s-triazine, 2,4- 6-triazine, 2,4-trichloromethyl-4-methylnaphthyl-6-triazine, 2- (o- chlorophenyl) -4,5-diphenylimidazole dimer, 2- ) -4,5-di (m-methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer 2-methyl- 1- [4- (methylthio) phenyl ] -2-morpholinopropanone-1, diphenyl ketone benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-1-one, dimethoxy- Gin may be at least one selected from the group.

The content of the photoinitiator is not limited, but the composition for forming a hard coating film is preferably 10 parts by weight or less, preferably 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight based on 100 parts by weight of the solid content of the composition . When the content is more than 10 parts by weight, cracks may occur in the overcuring process.

The present invention may contain a solvent in addition to the (meth) acrylate-based monomer and the photoinitiator having a wavelength range of 350 to 450 nm. Since the solvent is a component that can be removed in the course of curing into a film after the formation of the hard coat layer, it is preferable to use the solvent for diluting the prepared composition for hard coat layer formation.

The solvent may be used without limitation as long as it is known as a solvent in the composition for forming a hard coat layer in the technical field.

Examples of the solvent include alcohols such as methanol, ethanol, isopropanol, butanol, methylcellulose, ethylsorbox, etc., ketones such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, Cyclohexanone, etc.), hexane (hexane, heptane, octane etc.), benzene (benzene, toluene, xylene and the like) The solvents exemplified above may be used alone or in combination of two or more.

The solvent may be added in an amount of 0.1 to 90 parts by weight based on 100 parts by weight of the total composition of the composition for forming a hard coat film. If the content is less than 0.1 parts by weight, the viscosity may be high and the workability may be deteriorated. If the content is more than 90 parts by weight, the curing process may take a long time and the economical efficiency may be deteriorated.

The hard coating film according to the present invention may contain, in addition to the above-mentioned components, an antioxidant, a UV absorber, a light stabilizer, a leveling agent, a surfactant and an antifouling agent, which are generally used in the art within the range not lowering the effect of the present invention , And the like.

In the present invention, the composition for forming a hard coating layer is applied to one side or both sides of a transparent substrate and then hardened to form a hard coating layer. Thereafter, the low refractive index layer forming composition is coated on the hard coating layer and then cured to form a low refractive index layer on the hard coating layer.

The low refraction layer is preferably 1.20 to 1.49, preferably 1.30 to 1.44 at 25 ° C. An excellent low reflection effect can be obtained within the above range.

The low refraction layer may be formed using a composition for forming a low refraction layer generally used in the art, as long as it satisfies the refractive index range. For example, a fluorine-containing copolymer, a fine particle having a void, an initiator, and a solvent may be used.

Any film can be used as long as the transparent substrate is a plastic film having transparency. Examples of the transparent substrate include a cycloolefin-based derivative having a unit of a monomer including a cycloolefin such as norbornene or a polycyclic norbornene monomer, diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, isobutyl Cellulose acetate, vinyl acetate copolymer, polyester, polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyethersulfone, polyether sulfone, polyether sulfone, polyether sulfone, Polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyethersulfone, polymethylmethacrylate, polyethylene terephthalate, polyethylene terephthalate, polyethylene terephthalate , Polybutyl Terephthalate, may be used polyethylene naphthalate, polycarbonate, polyurethane, may be used one selected from among epoxy, non-stretched uniaxially or biaxially stretched film.

Of these, preferred are monoaxially or biaxially oriented polyester films which are excellent in transparency and heat resistance, cycloolefin-based derivative films which are excellent in transparency and heat resistance and capable of coping with the enlargement of the film, transparency and optical anisotropy, An acetylcellulose film may suitably be used.

The thickness of the transparent substrate is preferably 8 to 1000 占 퐉, more preferably 40 to 100 占 퐉.

Application of the composition for forming a hard coat layer and the composition for forming a low refractive layer may be carried out by a suitable method such as die coater, air knife, reverse roll, spray, blade, casting, gravure and spin coating.

The composition for forming a hard coat layer and the composition for forming a low refractive index layer are applied and then dried by evaporation of volatiles at a temperature of 30 to 150 DEG C for 10 seconds to 1 hour, preferably 30 seconds to 10 minutes. Then, UV light is irradiated for curing. The irradiation amount of the UV light is about 0.01 to 10 J / cm ² , preferably 0.1 to 2 J / cm ² .

At this time, the thickness of the hard coat layer is preferably 2 to 30 mu m, more preferably 3 to 10 mu m. The thickness of the composition for forming a low refractive index layer is preferably 80 to 120 nm, more preferably 90 to 105 nm.

The present invention also provides a polarizing plate provided with the antireflection film.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Manufacturing example  : Low refraction layer  Composition for forming

5 parts by weight of isopropanol and 3 parts by weight of ethyl acetate 3 (trade name) were added to 10 parts by weight of a hollow silica-containing UV coating solution (MB1030: a catalyst having a solid content concentration of 5% by weight and containing about 3% by weight of hollow silica in a solid content and containing a polymerizable monomer and a polymerization initiator) And the mixture was stirred at room temperature for 30 minutes. The mixture was filtered through a polypropylene filter having a pore size of 3 mu m to prepare a composition for forming a low refraction layer having a refractive index of 1.35.

Example  1-7 and Comparative Example  1-7

A composition for forming a hard coat layer was prepared using the composition shown in Table 1 below.

division
(Parts by weight) (Meth)
Acrylate
Monomer menstruum Photoinitiator additive surface
asperity
(Ra, nm) Long wavelength Short wavelength MEK MEC A-1 A-2 A-3 Example 1 45 27 27 One - - - 0.02 0.704 Example 2 45 27 27 - One - - 0.02 0.607 Example 3 45 27 27 - - One - 0.02 0.647 Example 4 45 27.5 27.5 0.5 - - - 0.02 0.698 Example 5 45 26.4 26.4 2.2 - - - 0.02 0.569 Example 6 45 26 26 3 - - - 0.02 0.516 Example 7 45 25.5 25.5 4 - - - 0.02 0.487 Comparative Example 1 45 27 27 - - - One 0.02 0.331 Comparative Example 2 45 26.4 26.4 - - - 2.2 0.02 0.351 Comparative Example 3 45 26 26 - - - 3 0.02 0.342 Comparative Example 4 45 26.4 26.4 0.66 - - 1.54 0.02 0.442 Comparative Example 5 45 26.4 26.4 1.1 - - 1.1 0.02 0.410 Comparative Example 6 45 24 24 6.5 - - - 0.02 0.440 (Meth) acrylate monomer: pentaerythritol tri / tetraacrylate (MWCM, M340)
MEK: Methyl ethyl ketone (purified water)
MEC: 2-Methoxyethanol (Pure Triple Action)
Short-wavelength photoinitiator: 1-hydroxycyclohexyl phenyl ketone (Ciba, I-184), wavelength range 240 to 370 nm
A-1: diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (BASF, TPO), a wavelength range of 340 to 440 nm
A-2: bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (Ciba, I-819), wavelength range 320 to 440 nm
A-3: ethyl-2,4,6-trimethylbenzoyl phenylphosphinate (BASF, TPO-L), a wavelength range of 340 to 440 nm
Additive: Modified silicone polymer (BYK-3530, BYK)

The composition for forming a hard coat layer prepared above was stirred for 1 hour and then coated on a transparent base film (80 탆, TAC) with a thickness of 5 탆 Meyer bar (a kind of gravure coater), followed by drying at 70 캜 for 1 minute. And then photocured at 500 mJ / cm < ² > to prepare a hard coat layer.

Preparative example a hard-to-forming low refractive index layer prepared above composition has a thickness of the coating layer such that the coating and 0.1㎛ 70 ℃ by Meyer bar (Meyer bar) and dried for 1 minute and then cured with 1mJ / cm ² low-refractive An antireflection film including a hard coating layer having a layer formed thereon was prepared.

Experimental Example

The physical properties of Examples 1-7 and Comparative Examples 1-7 were measured as follows, and the results are shown in Table 2 below.

One. Surface roughness ( Surface roughness , Ra ( nm ))

The Ra (nm) value of the surface of the hard coat layer of the antireflection film was measured under the test conditions of Non-Contact mode, scan size: 1 μm × 1 μm and scan rate: 1.0 Hz using AFM (PSIA XE-100) And the results are shown in Table 1.

2. Total light transmittance  And Hayes

Total transmittance and total haze value of the antireflection film were measured using a spectrophotometer (HZ-1, manufactured by Nippon Sugar) toward the light source (D65).

3. Pencil Hardness

The surface of the low refraction layer of the manufactured antireflection film was subjected to a pencil hardness tester (PHT, manufactured by Mabo Scientific Co., Ltd.) under a load of 500 g and the pencil hardness was measured. The pencil was made five times per pencil hardness using Mitsubishi products.

4. Scratch resistance

The test piece was reciprocated 10 times under 1 kg / (2 cm x 2 cm) using a steel wool tester (WT-LCM100, Korea Protec Co.) to test the scratch resistance of the low refractive index layer of the antireflection film. Steel wool used # 0000.

[Assessment Methods]

A: 0 scratches

A ': 1 to 10 scratches

B: 11 to 20 scratches

C: 21 to 30 scratches

D: More than 31 scratches

5. Chemical resistance ( Saponification )

The low refraction layer of the antireflection film was immersed in a potassium hydroxide aqueous solution (5N concentration) for 1 minute and then dried in an oven at 80 DEG C, and the presence or absence of the low refraction layer was confirmed.

division Total light transmittance
(%) Hayes
(%) Pencil hardness
(H) Scratch resistance Chemical resistance Example 1 91.2 0.3 2 A U Example 2 91.2 0.3 2 A ' U Example 3 91.2 0.3 2 A ' U Example 4 91.2 0.3 2 A ' U Example 5 91.3 0.3 2 A U Example 6 91.2 0.3 2 A U Example 7 91.2 0.3 2 A U Comparative Example 1 91.2 0.3 2 A radish Comparative Example 2 91.2 0.3 2 A radish Comparative Example 3 91.1 0.3 2 A radish Comparative Example 4 91.1 0.3 2 A radish Comparative Example 5 91.1 0.3 2 A radish Comparative Example 6 91.1 0.3 2 A ' radish

As shown in Table 2, the antireflection films of Examples 1 to 7, in which a hard coating layer containing a certain amount of long wavelength initiator and having a specific range of surface roughness values were formed according to the present invention, Not only the transmittance, the haze, the scratch resistance and the pencil hardness were maintained, but also the physical adhesion at the interface between the hard coat layer and the low refractive layer was improved, and the chemical resistance was improved.

Claims (6)

A composition for forming a hard coat layer containing a photoinitiator having a surface roughness (Ra) of 0.5 nm or more and a wavelength range of 350 to 450 nm in an amount of 10 parts by weight or less based on 100 parts by weight of a solid content in the whole composition A cured hard coat layer is formed,
Wherein a low refractive index layer is formed on the hard coating layer.
The antireflection film according to claim 1, wherein the hard coat layer has a surface roughness (Ra) of 0.5 to 10 nm.
The method of claim 1, wherein the photoinitiator is selected from the group consisting of bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, ethyl 2,4,6- Benzoyl phenylphosphinate, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) 4-bistricloromethyl-6-p-methoxystyryl-s-triazine, 2-p-methoxystyryl-4,6-bisttrichloromethyl- Methyl-6-triazine, 2,4-trichloromethyl-4-methylnaphthyl-6-triazine, 2- (o- chlorophenyl) -4,5-diphenylimidazole dimer, 2- Methylphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenyl imidazole dimer 2-methyl-1- [4- (methylthio Phenyl] -2-morpholinopropanone-1, diphenyl ketone benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-1-one, dimethoxy- Wherein the antireflection film is at least one selected from the group consisting of antireflection films.
[2] The composition for forming a hard coat layer according to claim 1, wherein the entire composition comprises 90 to 99.95 parts by weight of a (meth) acrylate monomer and 100 parts by weight of a photoinitiator 0.05 to 350 nm in a wavelength range of 350 to 450 nm To 10 parts by weight of the antireflection film.
The antireflection film according to claim 1, wherein the low refractive index layer has a refractive index of 1.2 to 1.49 at 25 캜.
6. A polarizing plate comprising the anti-reflection film according to any one of claims 1 to 5.