KR20170080089A - Anti-reflection film capable of controlling concave surface - Google Patents

Abstract

The present invention relates to an antireflection film capable of controlling surface irregularities, and more particularly, to an antireflection film capable of controlling the surface irregularity, and more particularly, To an antireflection film having sharpness and haze and capable of surface unevenness control.

Description

(ANTI-REFLECTION FILM CAPABLE OF CONTROLLING CONCAVE SURFACE)

The present invention relates to an antireflection film capable of controlling surface irregularities, and more particularly, to an antireflection film capable of controlling the surface irregularity, and more particularly, To an antireflection film having sharpness and haze and capable of surface unevenness control.

Recently, image display devices (FPD) such as liquid crystal display (LCD), plasma display (PDP), cathode ray tube (CRT) and electroluminescence display (EL) -Display), a notebook, a monitor, a TV, a PC, a digital camera, and a PDA. Among them, LCD is required to have wide viewing angle, high resolution, fast response, excellent color reproducibility, and focuses on technology development to meet this demand.

In such a display, the image of the screen viewed by the eye should solve the problem of deterioration of contrast and visibility due to external light (incident light) reflected or reflected by the display surface.

An anti-glare (AG) film is disposed on the front surface of the display for reducing irregularities and reducing visibility of reflected light by scattering incident light by forming irregularities on the surface irregularities to improve visibility Anti-reflection (AR) films are also used, which alternately coat and laminate low refractive materials and high refractive materials to lower the reflectance of incident light through destructive interference during interfacial reflection.

For example, the antiglare film is formed by coating a resin containing a filler such as silica (silicon dioxide) particles having a size of several micrometers on the surface of a transparent substrate. Such an antiglare film is a type in which a concavo-convex structure is formed on the surface by aggregation of particles such as cohesive silica using sandblast, amboshing roll, chemical etching or the like, a type in which a hard coating agent for forming an anti- Or a filler having a concavity and convexity is laminated on the surface of the layer to transfer the concavo-convex shape. Among these techniques, currently preferred is a type in which a light-scattering coating composition is prepared with a resin in which inorganic or organic particles are dispersed in a hard coating agent.

The coating composition prepared by the above method is described in Korean Patent No. 467,822 (Applicant: LG Chemical Co., Ltd.) as a flame-retardant coating composition, and includes reactive oligomers, polyfunctional monomers, fine particles (silica) Initiators and solvents. Korean Patent No. 785,380 (Applicant: Doosan) relates to a method for producing an antiglare film, which comprises coating a resin composition liquid containing fine particles (silicon oxide) on a substrate and curing the coating.

The antireflective coating composition composed of the thermosetting or thermoplastic resin in which the organic and inorganic particles are dispersed is applied to a transparent substrate, followed by drying and curing. The surface irregularities vary depending on the size and content of the particles used.

When an antiglare film containing such organic and inorganic particles is used, particles having a large average particle diameter cause a problem of flashing, which is a phenomenon in which a display pixel coming out from a light source inside the display is distorted by a lens functioning as a large surface irregularity.

On the other hand, in the case of using particles having a small average particle diameter, it is possible to prevent flickering on the screen, but there is a problem in that whitening occurs on the surface of the film, thereby deteriorating optical characteristics such as resolution, contrast and transparency.

In order to stabilize the dispersion of particles, a milling process is performed using a separate milling machine. However, the problem of agglomeration and sedimentation of particles having a size of several to several tens of micrometers in a coating composition makes it difficult to disperse uniform particles in the composition, It is becoming the main cause of various defects.

Further, a coating composition for realizing a coating layer containing organic beads of several to several tens of 탆 or inorganic particles such as silica is a form in which particles are dispersed in an organic solvent. The coating composition containing the particles is characterized by a non-Newtonian fluid whose viscosity varies depending on the shear stress due to the particles, and the discharge imbalance of the coating composition in the die during the slot die coating and drying Resulting in poor appearance of the coating and defective optical properties, which causes the yield to be lowered.

Disclosure of the Invention The present invention has been conceived to solve the problems described above. It is an object of the present invention to provide a hard coating composition containing a methyl cellulose resin and controlling the molecular weight, content, An object of the present invention is to provide an antireflection film capable of controlling surface irregularities.

The present invention relates to a triacetylcellulose film as a substrate layer; And a hard coating layer on at least one side of the triacetylcellulose film, wherein the hard coating composition of the hard coating layer comprises 6 to 10 functional urethane acrylate, 3 to 6 functional acrylate, methyl cellulose resin, curable resin, photoinitiator and solvent An antireflection film capable of surface unevenness control is provided.

At this time, the methyl cellulose resin preferably has a molecular weight of 10,000 to 65,000.

In addition, the methylcellulose resin preferably contains 0.2 to 1.0 wt% based on the total weight of the hard coating composition.

In addition, the antireflection film preferably has a haze of 0.5 to 2%, a transmission sharpness of 280 to 320%, and a transmittance of 92% or more.

The antireflection film according to the present invention includes a methyl cellulose resin in a hard coating composition and can control precise surface irregularities by controlling the molecular weight, content, composition and solid content of the resin, thereby realizing transmission sharpness and haze suitable for high resolution display And it is possible to obtain a uniform surface coating layer by controlling the flowability of the coating composition containing the conventional inorganic particles to reduce the coating thickness deviation upon slot die coating and to improve the coating appearance and optical property defects of the film, The yield increase can be expected.

Hereinafter, the present invention will be described in detail so that those skilled in the art can readily understand the present invention and can carry out the present invention without undue experimentation.

In describing the present invention, the terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms.

The antireflection film of the present invention comprises a triacetylcellulose film as a substrate layer; And a hard coating layer on at least one side of the triacetylcellulose film.

In this case, the hard coating composition of the hard coating layer comprises 6 to 10 functional urethane acrylate, 3 to 6 functional acrylate, methyl cellulose resin, curing resin, photoinitiator and solvent.

Hereinafter, the present invention will be described in more detail with respect to each configuration.

materials

The base material of the present invention may be, for example, 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, 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 , Polybutylene Terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, and epoxy. An unoriented uniaxial or biaxial oriented film can be used.

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, Acetylcellulose films may be suitably used, but triacetylcellulose films are preferred.

At this time, in order to improve the crack defects of the film, it is preferable to use the film by heat treatment. The heat treatment is preferably performed at a speed of 80 m / min, but is not limited thereto.

The hard coat layer Hard coating  Composition

(a) 6 to 10 functional urethane acrylate, 3 to 6 functional acrylate; And

(b) a methylcellulose resin, a curable resin, a photoinitiator and a solvent.

In the acrylate, the functional group means a reactive functional group. For example, the hexafunctional urethane acrylate includes a C = C bond included in each of six acrylate groups (-O-CO-H = CH ₂ ) .

When the number of functional groups of the urethane acrylate is large, the surface resistance of the obtained surface protective layer tends to be poor and the weather resistance tends to decrease. In addition, the surface tends to cause a wave on the surface to lower the specularity. On the other hand, when the number of functional groups is small, the cross-linking density is lowered and the resistance to scratches is insufficient. That is, the higher the number of functional groups, the more excellent the resistance to scratches, that is, the hard coat property, and the hard coat property requires moderate softness.

The hexafunctional urethane acrylate is commercially available from Miramer M600, PU510, PU20, PU640, HS Chemtron, UA-8560TL, UA-800, AGI 230A2, 670A2, 675 and Ebecryl 1290 from Cytec E But is not limited thereto.

On the other hand, the hard coating composition of the present invention may further include a lower functional oligomer having 3 to 6 functional acrylates.

When the low-functional oligomer is included, the composition has a low viscosity, a good wettability, and may be advantageous in terms of curl in curing. In addition, since the low-functionality oligomer has a small number of reactors, it generally has a small shrinkage after curing.

On the other hand, the methyl cellulose resin contained in the hard coating composition of the present invention is intended to control the visibility and haze due to the unevenness formation on the surface of the antireflection film.

Conventionally, inorganic particles such as organic beads or silica having a size of several to several tens of micrometers have been added to the coating composition to form the unevenness of the film. However, such a coating composition is a form in which particles are dispersed in an organic solvent. The coating composition containing the particles has a non-Newtonian fluid property that varies in viscosity according to shear stress due to the particles, There is a problem in that when the slot die coating is performed, uneven dispensing of the in-die coating composition and unevenness during drying may occur, resulting in appearance of the coating and poor optical characteristics.

Accordingly, in order to solve the above problems, the present invention is characterized by including a methylcellulose resin in a hard coating composition.

The methyl cellulose resin and the acrylate resin are separated by the difference in boiling point of the mixed solvent in a drying process to be described later, and a part separated by non-compatibility is formed in the coating layer. The incompatible portion thus formed has a fine structure with a size of several tens of um and causes haze in the coating layer. The haze can be controlled by controlling the molecular weight, content, resin composition, solid content, etc. of the methyl cellulose resin.

The molecular weight of such a methyl cellulose resin is preferably 10,000 to 65,000, but is not limited thereto.

In addition, the methylcellulose resin preferably contains 0.2 to 1.0 wt% based on the total weight of the hard coating composition. If the content of the methyl cellulose resin is less than 0.2% by weight, the number of unevenness on the surface of the coating layer is reduced and the antiglare effect is not exhibited. On the other hand, if the methyl cellulose resin content exceeds 1.0% by weight, The sharpness may be lowered and whitening phenomenon may occur.

On the other hand, specific examples of the curable resin include, but are not limited to, an ionizing radiation curable resin, an ionizing radiation curable resin, an ultraviolet curable resin, a thermosetting resin, and the like which are curable by ultraviolet rays or electron beams.

Specific examples of the ionizing radiation curable resin include an acrylate-based compound having an acrylate-based functional group such as a polyester resin, a polyether resin, an acrylic resin, an epoxy resin, a urethane resin, an alkyd resin, a spiroacetal resin, Oligomers or prepolymers of polyfunctional compounds such as polybutadiene resins, polythiol polyene resins and polyhydric alcohols such as (meth) acrylates, and reactive diluents, but are not limited thereto.

Specific examples of the ionizing radiation curable resin include monofunctional monomers and polyfunctional monomers such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene and N-vinylpyrrolidone, Tri (meth) acrylate, triethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol (Meth) acrylate, isocyanuric acid-modified diacrylate, isocyanuric acid-modified triacrylate, bisphenol F-modified (meth) acrylate, Diacrylate, and the like, but are not limited thereto.

Specific examples of the thermosetting resin include phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine- Polysiloxane resin, and the like, but are not limited thereto.

At this time, the ultraviolet ray hardening type resin is a component that substantially implements the anti-scattering property, and has a light transmittance of 85% or more, preferably 90% or more, and a compound having two or more acrylic functional groups in the molecule from the viewpoint of scratch resistance Can be used. Examples of the ultraviolet curable resin having two or more functional groups include pentaerythritol hexaacrylate, trimethylol propane triacrylate, tetraethylene glycol diacrylate, and pentaerythritol triacrylate. More preferably, an aliphatic urethane acrylate oligomer, an aromatic urethane acrylate oligomer or an acrylate monomer can be used, and an ultraviolet curable resin having three or more acrylate functional groups, a compound containing two or more acrylic functional groups in the molecule alone Or a mixture of two or more of them may be used.

In the hard coating composition of the present invention, the ultraviolet curable resin is a form containing a polyfunctional acrylate oligomer, a monomer or a mixture thereof, and is preferably contained in an amount of 10 to 50% by weight of the entire composition.

If the content is less than 10% by weight, a coating film may not be formed due to a low viscosity. In order to obtain a sufficient thickness of the antiglare layer after drying, the coating amount of the coating composition must be increased, If it exceeds 50% by weight, the coating property is deteriorated due to an increase in viscosity due to an increase in resin solid content.

On the other hand, the photoinitiator is used for curing the curable resin, and conventional photoinitiators used in the hard coating composition may be used.

In the examples of the present invention, 1-hydroxycyclohexyl phenyl ketone is used as the most preferable photo initiator, but the present invention is not limited thereto.

Thus, examples of other compounds that may be selected from among the known photoinitiators include 2-hydroxy-2-methyl-1-phenyl-1-one, 4-hydroxycyclophenyl ketone, dimethoxy- , Anthraquinone, fluorene, triphenylamine, carbazole, 3-methylacetophenone, 4-quinoloacetophenone, 4,4-dimethoxyacetophenone, 4,4-diaminobenzophenone, Methyl-2- (4-methylthio) phenyl) -2-mercapto propanone, diphenylphosphoryl mesyl methanone, 2-hydroxyl- , Triethylamine, 2,2'-dimethoxy-1,2-diphenylethanone, mixtures thereof, etc., and commercialized photoinitiators can be used.

In the hard coating composition of the present invention, the content of the photoinitiator is preferably 0.5 to 4 wt%, and if the content of the photoinitiator is less than 0.5 wt%, the ultraviolet curable resin can not be cured sufficiently, An excessive amount of photoinitiator acts as an impurity.

Meanwhile, the solvent used in the present invention is used to adjust the solid content of the entire hard coating composition. In the present invention, a solvent having a high boiling point is advantageous, and an acetate type solvent which gives erosion to the triacetylcellulose film is preferable (Methanol, ethanol, isopropyl alcohol, butyl alcohol, etc.), alkoxy alcohol solvents (such as 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol Etc.), ketone solvents (methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, etc.), ether acetate solvents (propylene glycol monomethyl ether acetate and the like)

When the content of the solvent of the present invention is 100 wt%, the content of the solvent is adjusted to the content of 100 wt% minus the sum of the contents of the other ingredients. If the content of the solvent is too low, the drying and curing processes take a long time.

The hard coating composition of the present invention may contain, in addition to the above components, a light stimulant, an antioxidant, a UV absorber, a light stabilizer, a thermal polymerization inhibitor, a leveling agent, a surfactant, a lubricant and the like.

On the other hand, the hard coating layer includes a drying process of applying a hard coating composition on a substrate onto a base film to dry the applied base film, and a UV curing process of curing the hard coating composition.

The drying process and the UV curing process will be described in more detail as follows.

The drying process is to dry the coating composition applied on the substrate film.

Examples of the method of applying the coating composition include a coating method using a die coater, a spin coater, a spray coater, a curtain coater, a roll coater or the like, a coating method by screen printing or the like, or a dipping method.

The film coated with the coating composition is allowed to stand or move at 30 to 100 DEG C for 1 to 5 minutes in an oven, in which the solvent contained in the coating composition is evaporated and dried.

The UV curing process can be performed by UV irradiation at a light amount of 100 to 800 mJ / cm ² .

The antireflection film of the present invention produced as described above can control surface irregularities by controlling the molecular weight, content, resin composition, solid content and the like of the methyl cellulose resin. Thus, the antireflection film of the present invention can produce an antireflection film having a haze of 0.5 to 2%, a transmission sharpness of 280 to 320%, and a transmittance of 92% or more, and having transmission sharpness and haze suitable for a high resolution display.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are for illustrating the present invention specifically, and the scope of the present invention is not limited to these examples.

How to measure property

1) Transmittance of haze: Total transmittance and haze were measured using a spectrophotometer (HM-150, manufactured by Murakami) (measurement method conformed to JIS K7136).

2) Permeation clarity (%): Transparent clarity of the antiglare film was measured using a transmission sharpness measuring instrument (Suga, ICM-1T). The transmission sharpness was determined by summing the values of the transmission sharpness values of the slit intervals of 0.01 mm, 0.5 mm, 1.0 mm and 2.0 mm. The transmission sharpness value is correlated with the sharpness, and the larger the transmission sharpness value is, the clearer it is.

Example  One

One type of Ebyl 1290 (molecular weight: 1,000) of Cytec Company was blended with one type of acrylate acrylate monomer as a hexafunctional urethane acrylate oligomer, and then 0.7 weight% of a methyl cellulose resin having a molecular weight of 14,000 and 81 g of a photo- Were added and mixed to prepare a coating composition.

Propylene glycol monomethyl ether acetate was added as an acetate-based solvent to the above-prepared coating composition and applied on a triacetyl cellulose film substrate. Thereafter, the organic solvent was evaporated off by drying, and the ultraviolet curable resin was cured by a UV curing process, and the finally obtained film was wound.

Example  2

A film was prepared in the same manner as in Example 1, except that a methylcellulose resin having a molecular weight of 17,000 was used instead of the methylcellulose resin having a molecular weight of 14,000.

Example  3

A film was prepared in the same manner as in Example 1, except that a methylcellulose resin having a molecular weight of 41,000 was used instead of the methylcellulose resin having a molecular weight of 14,000.

Example  4

A film was prepared in the same manner as in Example 1, except that a methylcellulose resin having a molecular weight of 63,000 was used instead of the methylcellulose resin having a molecular weight of 14,000.

Comparative Example  One

A film was prepared in the same manner as in Example 1, except that a methylcellulose resin having a molecular weight of 88,000 was used instead of the methylcellulose resin having a molecular weight of 14,000.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Methylcellulose molecular weight 14,000 17,000 41,000 63,000 88,000 Haze (%) 0.89 1.07 1.13 1.87 2.61

Example  5

A film was prepared in the same manner as in Example 3, except that 0.2 wt% was used instead of 0.7 wt% of methyl cellulose resin.

Example  6

A film was prepared in the same manner as in Example 3, except that 0.5% by weight was added instead of 0.7% by weight of methyl cellulose resin.

Example  7

A film was prepared in the same manner as in Example 3, except that 0.8% by weight of methyl cellulose resin was added instead of 0.7% by weight.

Example  8

A film was prepared in the same manner as in Example 3, except that 1.0 wt% was used instead of 0.7 wt% of methyl cellulose resin.

Comparative Example  2

A film was prepared in the same manner as in Example 3, except that 0.1% by weight was added instead of 0.7% by weight of methyl cellulose resin.

Comparative Example  3

A film was prepared in the same manner as in Example 3, except that 1.5% by weight of methyl cellulose resin was used instead of 0.7% by weight of methyl cellulose resin.

Example 5 Example 6 Example 7 Example 8 Comparative Example 2 Comparative Example 3 Methylcellulose content (%) 0.2 0.5 0.8 1.0 0.1 1.5 Haze (%) 0.51 0.74 1.13 1.45 0.34 2.67 Transparency sharpness (%) 323 305 288 257 340 -

Claims (4)

A triacetylcellulose film as a base layer; And
Wherein the triacetylcellulose film comprises a hard coating layer on at least one side thereof,
Wherein the hard coat composition of the hard coat layer comprises 6 to 10 functional urethane acrylate, 3 to 6 functional acrylate, methyl cellulose resin, curable resin, photoinitiator and solvent.
The method according to claim 1,
Wherein the methyl cellulose resin has a molecular weight of 10,000 to 65,000.
The method according to claim 1,
Wherein the methylcellulose resin comprises 0.2 to 1.0 wt% based on the total weight of the hard coating composition.
4. The method according to any one of claims 1 to 3,
Wherein the antireflection film has a haze of 0.5 to 2%, a transmission sharpness of 280 to 320%, and a transmittance of 92% or more.