KR200457139Y1 - Optical film - Google Patents

Abstract

The present invention relates to an optical film comprising a substrate having a microstructure and a resin coating disposed on the microstructure of the substrate. The resin coating comprises a plurality of organic particles and a binder. The microstructure includes a plurality of columnar structures that are equilateral, and the organic particles are tangent to the columnar structure. The height of the organic particles is not smaller than the height of the columnar structure. The optical film of the present invention can distribute the organic particles uniformly and regularly, so that the transmitted light can be uniform and the brightness can be improved.

Description

Optical film {OPTICAL FILM}

The present invention relates to an optical film. In particular, the present invention relates to an optical film having a very uniform optical property, which is useful for a backlight module.

Liquid crystal displays (LCDs) are known to be unable to emit light independently. There is a need for a backlight module as a light source that provides sufficient and uniform brightness to display an image properly. Typical backlight modules use diffuser plates, diffuser films, and brightness enhancement films to uniformly distribute and converge light rays. The function of the diffuser plate and the diffuser film is to provide a uniform area light source. Luminance enhancement films, also known as luminance enhancement films or prism films, converge the light scattered by refraction and total internal reflection, and converge the light in the axial direction at approximately +/- 35 degrees to improve the luminance of the LCD. do.

Conventional brightness enhancing films comprise a substrate 1 (as shown in FIG. 1 and disclosed for example in WO 96/23649 and US Pat. No. 5,262,800) and a plurality of prisms 2 in a parallel arrangement. Each prism then has two inclined surfaces, which meet at the prism top to form a peak 3. The two inclined planes each meet with the inclined plane of the adjacent prism at the bottom of the prism to form a valley 4.

The prism of the brightness enhancing film can be easily scratched when in contact with a display panel or other film, adversely affecting the optical properties of the prism. In order to prevent damage caused by abrasion with other films due to vibration during transportation, the most common solution in the art is to utilize a protective diffuser film, also known as a top diffuser film. In addition to the protective diffusion film, other protective films may be needed during storage and transportation to avoid scratching prior to assembly. However, protective diffusion films and other protective films increase manufacturing costs.

Conventional diffusion films are prepared by coating a resin binder and diffusion particles to form a diffusion layer on a transparent substrate. As the light passes through a diffusion layer containing two media having different refractive indices, refraction, reflection and scattering occur, causing the light to diffuse and become uniform. Diffusion particles used in the art vary widely in size to enhance diffusion. However, scattering irregularities do not effectively utilize all rays. In addition, the diffusion particles may aggregate or adhere to each other during the manufacturing process, reducing the uniformity of the light beam and consequently becoming a dark spot on the display.

Moreover, brightness enhancing films are more expensive than other optical films. To reduce costs, the industry tends to rely on new types of optical films or to change the arrangement of other optical films so that no brightness enhancement film is needed. For example, a transparent microlens may be formed on the substrate, and due to the unique structure and properties of the material, the optical film not only diffuses light but also converges. The optical film (described in US 7,265,907) shown in FIG. 2 has rows of transparent substrate 4 and microlenses 20a and 20b, each row comprising a plurality of microlenses 2a and 2b. However, the manufacturing throughput according to this method is low, and therefore its industrial application is limited. Another example described in US 7,265,907 (also TW 287644) is to release droplets to form microlenses on a substrate. The patent claims that the structure can be made roll-to-roll, but if the droplet falls on the substrate, the rotation of the substrate must be stopped for a while until the droplet completely forms the microlens. Thus, structures cannot be manufactured by non-stop roll-to-roll processes such as slot die coating or roller coating.

The present invention provides an optical film without problems due to the above-mentioned disadvantages.

The optical film according to the present invention provides a specific structure that can block and confine the organic particles so as to reduce the aggregation or adhesion of the organic particles and arrange the particles regularly. Optical film according to the present invention can improve the uniformity of light rays and increase the luminescence by converging and diffusing light rays.

In another aspect, the present invention provides a method of making an optical film having a microstructure by a continuous roll-to-roll technique. The method according to the present invention greatly increases the industrial applicability of the optical film.

In order to achieve the above and other objects, the present invention provides an optical film comprising a substrate having a microstructure and a resin coating disposed thereon. The resin coating comprises organic particles and a binder, the microstructures comprise a plurality of columnar structures that are equilateral, the organic particles are tangent to the columnar structures, and at least a portion of the organic particles. The geometrical arrangement of satisfies the equation H _b ≥ H, where H _b denotes the vertical distance between the top of the organic particle and the bottom of the columnar structure, and H denotes the vertical distance between the apex and the bottom of the columnar structure. Indicates.

Although the detailed description shows a preferred embodiment of the present invention, it is intended for purposes of illustration only and is not intended to limit the scope of the present invention. For example, the words "a" and "an" are treated herein to include both the singular and the plural unless otherwise indicated.

Within the context of this specification, the term "pillar structure" may refer to a prismatic columnar structure, an arc-shaped columnar structure, or a mixture thereof.

Within the context of this specification, the term "prismal columnar structure" refers to a columnar structure having two flat inclined surfaces. The inclined surface meets at the top of the prism to form a peak or is blunt to form a blunt-shaped surface.

Within the context of this specification, the term "arc columnar structure" refers to a columnar structure with two inclined surfaces. The two inclined surfaces meet at the top of the prism to form a peak, or are blunt to form a dull face.

Within the context of this specification, the term "linear columnar structure" refers to columnar structures with linear ridges extending along the longitudinal direction.

Within the context of the present specification, the term “serpentine columnar structure” refers to a columnar structure with an S-shaped floor extending along the length direction. The curvature of the sigmoidal floor varies suitably and the amount of change in the curvature is in the range of 0.2% to 100%, preferably 1% to 20%, of the nominal height of the sigmoidal columnar structure.

Within the context of this specification, the term "zigzag columnar structure" refers to a columnar structure having zigzag ridges extending along the longitudinal direction.

Within the context of the present specification, the symbol "H" represents the height of the columnar structure, which is the vertical distance between the vertex and the bottom of the columnar structure.

Within the context of the present specification, the symbol "H _b " denotes the height of organic particles, which is the vertical distance between the top of the organic particles and the bottom of the columnar structure.

Within the context of the present specification, the symbol "2θ" denotes an apex angle formed by two inclined surfaces of the columnar structure.

Within the context of the present specification, the symbols "R" and "R _a " denote the radius of the organic particles and the average radius of the organic particles, respectively.

Within the context of the present specification, the symbol "r" denotes the radius of curvature of the arc groove.

The optical film according to the present invention includes a resin coating including a substrate having a microstructure and a plurality of organic particles, wherein the microstructure is configured to improve light uniformity and increase luminescence by efficiently converging and diffusing light rays. And a plurality of columnar structures in which the plurality of organic particles are confined, the aggregation or adhesion of the organic particles is reduced, and the organic particles can be arranged regularly.

Substrates having a microstructure used in the present invention may be prepared by any method known to those skilled in the art. For example, the optical film may be embossed or injected; Or by laminating a commercially available brightness enhancing film onto the substrate; Or by attaching a light converging structured surface onto the substrate using a continuous roll-to-roll technique. Commercially available brightness enhancing films suitable for the present invention include BEF90HP ^® C and BEF II 90/50 from Sumitomo 3M, and DIA ART H150100 ^® and P210 from Mitsubishi Rayon.

In a preferred embodiment according to the present invention, a substrate having a microstructure is produced by applying a plurality of columnar structures on the surface of the substrate using a continuous roll-to-roll technique.

The columnar structure may be linear, sigmoidal or zigzag columnar structure. Two adjacent columnar structures may or may not be parallel, and are preferably parallel. Two adjacent columnar structures may or may not be connected to each other. The grooves formed between the two columnar structures may be V-shaped, arced or inverted trapezoids.

The columnar structure used in the present invention is equilateral, may be the same or different in height and width, may be a prismatic columnar structure, an arc-shaped columnar structure or a mixture thereof, of which prismatic columnar structures are preferred. The right angles of the prismatic or arcuate columnar structures can be the same or different and range from 40 ° to 120 °.

Resins used for forming columnar structures in the present invention are those known to those skilled in the art, for example, thermosetting resins or energy ray-curable resins. The energy rays can be ultraviolet rays, infrared rays or visible rays or hot rays such as emission and radiation rays; The exposure luminous intensity is in the range of 1 to 500 mJ / cm ² , preferably 50 to 300 mJ / cm ² . UV-curable resins are preferred. Examples of suitable UV-curable resins include, but are not limited to, acrylate resins such as (meth) acrylate resins, urethane acrylate resins, polyester acrylate resins, epoxy acrylate resins, and mixtures thereof. Medium (meth) acrylate resin is preferable.

The base material according to the present invention may be any suitable material known to those skilled in the art, for example glass and plastic. The plastic substrate may be composed of one or more polymerizable resin layers. The type of resin used for the polymerizable resin layer is not particularly limited, and for example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), poly such as polymethyl methacrylate (PMMA) Polyolefin resins such as acrylate resins, polyethylene (PE) and polypropylene (PP), polycycloolefin resins, polyimide resins, polycarbonate resins, polyurethane resins, triacetyl cellulose (TAC), polylactic acid and combinations thereof It may be any one selected from the group consisting of, but is not limited to these. Among the above, polyester resins, polycarbonate resins and combinations thereof are preferred, and PET is more preferred. The thickness of the substrate depends on the requirements of the optical product and is usually in the range of 15 μm to 300 μm.

In order to diffuse the light beam, the substrate having a microstructure is coated by a resin coating comprising organic particles and a binder. The organic particles in the resin coating are not particularly limited, but may be, but are not limited to, polyacrylate resins, polystyrene resins, urethane resins, silicone resins, or mixtures thereof. Of these resins, polyacrylate resins and silicone resins are preferred, and at least one acrylate monomer having a mono-functional group and at least one acrylate monomer having a multi-functional group More preferred are polyacrylate resins which are included as polymerizable units. In this case, the amount of the acrylate monomer having a polyfunctional group is about 30 to 70% by weight based on the total weight of the monomers. Since the monomer used in the present invention includes a monomer having a polyfunctional group, the crosslinking reaction between the monomers increases the crosslinking degree of the organic particles, thereby increasing the hardness and wear resistance of the organic particles and the solvent resistance to the binder. .

Suitable acrylate monomers having a single functional group include, but are not limited to, methyl methacrylate (MMA), butyl methacrylate, 2-phenoxy ethyl acrylate, ethoxylated 2-phenoxy ethyl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate, cyclic trimethylolpropane formal acrylate, β-carboxyethyl acrylate, lauryl methacrylate, isooctyl acrylate, stearyl methacrylate, isodecyl acrylate Isobornyl methacrylate, benzyl acrylate, 2-hydroxyethyl methacrylate phosphate, hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA) and mixtures thereof Can be.

Suitable acrylate monomers with polyfunctional groups include, but are not limited to, hydroxypivalyl hydroxypivalate diacrylate, ethoxylated 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tricyclo Decane dimethanol diacrylate, ethoxylated dipropylene glycol diacrylate, neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol-A dimethacrylate, 2-methyl-1,3 Propanediol diacrylate, ethoxylated 2-methyl-1,3-propanediol diacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, ethylene glycol dimethacrylate (EGDMA) , Diethylene glycol dimethacrylate, tris (2-hydroxyethyl) isocyanurate triacrylate, pentaerythritol triacrylate, ethoxylated trimethyl Propane triacrylate, propoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, propoxylated Pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, tripropylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate , Alkylated cyclohexyl dimethacrylate, isocyanurate dimethacrylate, ethoxylated trimethylol propane tri-methacrylate, propoxylated glycerol tri-methacrylate, trimethylol propane tri-methacrylate, tris ( Acryloxyethyl) isocyanurate and their It may be selected from the group consisting of compounds.

In a preferred embodiment according to the present invention, the organic particles in the resin coating are polyacrylate resin particles formed from methyl methacrylate and ethylene glycol dimethacrylate monomers, wherein methyl methacrylate monomers to ethylene glycol dimethacrylate monomers The weight ratio of is about 70:30, 60:40, 50:50, 40:60 or 30:70. The degree of crosslinking is better when the amount of ethylene glycol dimethacrylate monomer is about 30 to about 70% by weight relative to the total amount of the monomers.

According to the present invention, the shape of the organic particles in the resin coating is not particularly limited, and may be, for example, spherical, oval or irregular, of which spherical is preferable. The organic particles have an average particle size in the range of about 1 μm to about 100 μm, preferably in the range of about 2 μm to 50 μm, more preferably in the range of 8 μm to 20 μm. Most preferably, the organic particles have an average particle size of 8, 10, 12, 15, 18 or 20 μm. The organic particles can scatter light rays. In order to increase the luminescence of the optical film, the organic particles used in the present invention have a narrow particle size distribution. The particle size of the organic particles is in the range of about ± 30% of the average particle size, preferably in the range of about ± 15% of the average particle size. According to the present invention, for example, when the average particle size of the organic particles is about 15 μm and the particle size distribution is in the range of about ± 30%, the particle size of the organic particles in the resin coating is in the range of about 10.5 μm to about 19.5 μm. to be. Compared with the organic particles used in the prior art having an average particle size of about 15 μm and a particle size distribution in the range of about 1 μm to about 30 μm, organic particles according to the present invention having an average particle size and having a narrower particle size distribution As a result of the remarkable difference in particle size, the scattering range is wide and thus the light emission of the optical film is improved, thereby avoiding waste of the light source.

The organic particles in the resin coating according to the present invention are present in an amount of about 100 to about 300 parts by weight, preferably about 120 to about 220 parts by weight, per 100 parts by weight of solids of the binder. The distribution pattern of the organic particles in the resin coating is not particularly limited, and preferably the organic particles are uniformly distributed in a single layer. The uniform distribution of monolayers not only reduces the cost of the material but also reduces the waste of the light source, thereby improving the luminescence of the optical film.

In order to allow the transmission of light, the binder used in the present invention is preferably transparent. The binder according to the present invention may be selected from UV-curable resins, thermosetting resins, thermoplastic resins and mixtures thereof, wherein the resins may optionally be heat cured, UV cured or It can be processed by heat and UV double curing. In an embodiment according to the present invention, the binder comprises a UV curable resin, and a resin selected from the group consisting of thermosetting resins, thermoplastic resins and mixtures thereof, forming a resin coating having excellent heat resistance and very low volume reduction. To be treated by heat and UV double curing to improve the hardness of the coating and to prevent warping of the film.

UV curable resins suitable for the present invention are formed from at least one of acrylic monomers or acrylate monomers having one or more functional groups, among which acrylate monomers are preferred. Acrylate monomers useful in the present invention include, but are not limited to, for example, methacrylate monomers, acrylic acid ester monomers, urethane acrylate monomers, polyester acrylate monomers or epoxy acrylate monomers, among which acrylate monomers desirable.

For example, acrylate monomers suitable for the UV curable resins according to the present invention include methyl methacrylate, butyl acrylate, 2-phenoxy ethyl acrylate, ethoxylated 2-phenoxy ethyl acrylate, 2- (2- Methoxyethoxy) ethyl acrylate, cyclic trimethylolpropane formal acrylate, β-carboxyethyl acrylate, lauryl methacrylate, isooctyl acrylate, stearyl methacrylate, isodecyl acrylate, isobornyl meta Acrylate, benzyl acrylate, hydroxypivalyl hydroxypivalate diacrylate, ethoxylated 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tricyclodecane dimethanol diacrylate, ethoxylated di Propylene Glycol Diacrylate, Neopentyl Glycol Diacrylate, Propoxylated Neopentyl Glycol Diacryl Ethoxylated bisphenol-A dimethacrylate, 2-methyl-1,3-propanediol diacrylate, ethoxylated 2-methyl-1,3-propanediol diacrylate, 2-butyl-2-ethyl- 1,3-propanediol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate phosphate, tris (2-hydroxyethyl) isocyanurate triacrylate , Pentaerythritol triacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, ethoxy Shisa pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, propoxylated pentaerythritol tetraacrylate , Pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), tripropylene glycol dimethacrylate, 1,4-butanediol Dimethacrylate, 1,6-hexanediol dimethacrylate, allylated cyclohexyl dimethacrylate, isocyanurate dimethacrylate, ethoxylated trimethylol propane trimethacrylate, propoxylated glycerol trimetamethacrylate Acrylate, trimethylol propane trimethacrylate and tris (acryloxyethyl) isocyanurate and mixtures thereof. Preferably, the acrylate monomers include dipentaerythritol hexaacrylate, trimethylolpropane triacrylate and pentaerythritol triacrylate.

In order to improve the film forming properties of the resin coating, the UV curable resin may optionally include oligomers having a molecular weight in the range of 10 ³ to 10 ⁴ . Oligomers such as acrylate oligomers are well known to those skilled in the art. Acrylate oligomers that can be used in the present invention include, but are not limited to, urethane acrylates such as aliphatic urethane acrylates, aliphatic urethane hexaacrylates, and aromatic urethane hexaacrylates; Epoxy acrylates such as bisphenol-A epoxy diacrylate and novolac epoxy acrylate; Polyester acrylates such as polyester diacrylate; Or homo-acrylates.

Suitable thermosetting resins according to the present invention have an average molecular weight in the range of about 10 ⁴ to about 2 × 10 ⁶ , preferably about 2 × 10 ⁴ to 3 × 10 ⁵ , more preferably about 4 × 10 ⁴ to about 10 ⁵ . It is things that have. The thermosetting resin according to the present invention is a polyester resin having a carboxyl (-COOH) and / or hydroxyl (-OH) group, epoxy resin, polyacrylate resin, polymethacrylate resin, polyamide resin, fluoro resin, Polyimide resins, polyurethane resins and alkyd resins, or mixtures thereof. Of the foregoing, polymethacrylate or polyacrylate resins having carboxyl (-COOH) and / or hydroxyl (-OH) groups are preferred, such as polymethacrylate polyol resins.

Suitable thermoplastic resins according to the present invention are selected from the group consisting of polyester resins, polymethacrylate resins such as PMMA, and mixtures thereof.

The thickness of the resin coating of the optical film according to the present invention generally depends on the requirements of the optical product, usually in the range of about 5 μm to 30 μm, preferably in the range of about 10 μm to about 25 μm.

In addition to organic particles and binders, the resin coating of the present invention may optionally include any conventional additive known to those skilled in the art, such as but not limited to leveling agents, stabilizers, antistatic agents, curing agents, fluorescent brighteners, photoinitiators or UV absorbers. It may include.

Moreover, when the substrate is plastic, in order to prevent the plastic substrate from yellowing, inorganic particles capable of absorbing UV light may be selectively added to the resin coating. The inorganic particles include, but are not limited to, zinc oxide, strontium titanate, zirconia, alumina, titanium dioxide, calcium sulfate, barium sulfate, calcium carbonate or mixtures thereof. Of these, titanium dioxide, zirconia, alumina, zinc oxide or mixtures thereof are preferred. The particle size of the aforementioned inorganic particles is generally in the range of about 1 nm to about 100 nm, preferably about 20 nm to about 50 nm.

In order to avoid adhesion between the optical film of the present invention and other components in the backlight module, as shown in FIG. 3, the optical film of the present invention has an anti-stick layer coated on the surface of the substrate 101 opposite the microstructure 107. And optionally 121. The thickness of the anti-stick layer is about 5 μm to 10 μm. Suitable materials for the binder 122 and the organic particles 123 are as described above.

The organic particles in the anti-adhesion layer are present in an amount of about 0.1 to about 5 parts by weight per 100 parts by weight of solids of the binder. The average particle size of the organic particles is about 5 μm to 10 μm, preferably about 5, 8 or 10 μm, most preferably 8 μm.

The anti-stick layer and the resin coating according to the present invention may be composed of the same or different components.

The optical film according to the present invention has a haze in the range of about 80% to about 98% when measured according to the JIS K7136 standard method. Preferably the optical film has a total transmission of at least about 60% according to the JIS K7136 standard method. Therefore, the optical film of the present invention can be used, for example, in light source devices such as advertising light boxes and flat panel displays, especially liquid crystal displays. The present optical film is disposed as a light-converging element on the light emitting surface of the area light source device. In addition, since the optical film of the present invention not only improves luminescence but also can uniformize light rays, two or three optical films of the present invention can be used to replace a conventional design having a prism in combination with another diffusing film. have.

In addition, since the optical film according to the present invention can uniformize and converge the light rays and the organic particles in the optical film are trapped in the grooves between two adjacent columnar structures, the non-uniform distribution of organic particles associated with the conventional diffusion film or on the display The problem of aggregation or distribution of organic particles such as dark spots can be avoided.

Hereinafter, the present invention will be described in detail by embodiments with reference to the drawings, but this is not intended to limit the scope of the present invention. It will be apparent that any modification or change that can be readily made by those skilled in the art is within the scope disclosed herein.

4 shows a preferred embodiment of the optical film according to the present invention. The optical film includes a substrate 101 having a microstructured layer 107 over the substrate 101, the microstructured layer comprising a plurality of parallel columnar structures 109; And a resin coating comprising a plurality of organic particles 113 and a binder 110. Grooves are formed by two adjacent columnar structures and the binder 110, and organic particles 113 are present in these grooves. The distance between the top of at least a portion of the organic particles and the bottom of columnar structure 103 is greater than the distance between apex 105 and the bottom 103 of the columnar structure.

7, 8 and 9 are another embodiment of the optical film according to the present invention. These show that adjacent columnar structures may or may not be connected to each other.

An example in which adjacent columnar structures are connected to each other, that is, an example in which the bottom of columnar structure 109 is connected to the bottom of an adjacent columnar structure, is shown in FIG. 4. In this case, at least some of the organic particles satisfy the following equation:

In the above formula, H represents the vertical distance between the vertex 105 and the bottom 103 of the columnar structure, 2θ represents the right angle of the columnar structure, and R represents the radius of the organic particles 113 tangent to the columnar structure. 5 and 6 are schematic diagrams showing geometric relationships between organic particles and columnar structures.

Examples in which the columnar structures are not connected, ie, there is a particular space between adjacent columnar structures 109, in which the valleys in between are grooves with flat bottoms are shown in FIGS. 7 and 9. The microstructures shown in FIGS. 7 and 9 are formed in different ways. The microstructure shown in FIG. 7 is formed by attaching parallel columnar structures over the substrate surface, and the microstructure shown in FIG. 9 is formed together with the substrate as a unit.

The columnar structure may be prismatic (109 in FIGS. 4, 7 and 9) or arc (109 in FIG. 8). If the columnar structure is a prismatic columnar structure and two adjacent structures are connected, a V-shaped groove is formed and the organic particles 113 are located in the V-shaped groove (as shown in FIG. 4). If the columnar structure is arcuate and two adjacent structures are connected, an arcuate groove desired in the present invention is formed (as shown in FIG. 8).

In the optical film according to the present invention, the curve of the arc-shaped groove formed in the microstructured layer 301 is not particularly limited, and is, for example, arc, elliptical or parabolic, and arc is preferable. 10, the curvature radius (r) of the arc-shaped grooves is proportional to the mean radius (R _a) of the organic particles (302). The ratio of r to R _a may be 1: 100 to 100: 1, preferably 1: 5 to 5: 1, more preferably 1: 2 to 2: 1.

The columnar structure on the optical film according to the present invention is a linear columnar structure in which the floor extends linearly along the length direction as shown in FIG. 11, or the floor is twisted along the length direction as shown in FIG. 12. It may be an elongated sigmoidal columnar structure.

1 is a schematic view of a conventional brightness enhancement film.

2 is a schematic diagram of a conventional optical film having a microlens structure.

3 is a schematic view of an embodiment of an optical film according to the present invention.

4 is a cross-sectional view of an embodiment of an optical film according to the present invention.

5 is a geometrical schematic diagram of columnar structures and organic particles in the optical film according to the present invention.

6 is a schematic diagram showing the geometric relationship between the bottom of the columnar structure and the center of the organic particles.

7 is a schematic view of another embodiment of an optical film according to the present invention.

8 is a schematic view of another embodiment of an optical film according to the present invention.

9 is a schematic view of a further embodiment of an optical film according to the present invention.

10 is a cross-sectional view of an optical film according to the present invention having an arc columnar structure.

11 is a plan view of an embodiment of an optical film according to the present invention.

12 is a plan view of another embodiment of an optical film according to the present invention.

Claims (24)

A substrate having a microstructure; And An optical film comprising a resin coating comprising a plurality of organic particles and a binder and disposed on a microstructure of a substrate, The microstructure comprises a plurality of columnar structures that are equilateral, wherein the organic particles are tangent to the columnar structure and are uniformly distributed in a single layer, wherein at least some of the organic particles satisfy the equation H _b ≧ H, wherein H _b represents the vertical distance between the top of the organic particles and the bottom of the columnar structure, and H represents the vertical distance between the vertex and the bottom of the columnar structure. The method according to claim 1, The microstructures are optical films comprising a plurality of parallel columnar structures. The method according to claim 2, Parallel columnar structures are optical films of the same height, width and right angle. The method according to claim 1, The columnar structure is an optical film of prismatic columnar structure, arc columnar structure, or a mixture thereof. The method according to claim 4, The columnar structure is an optical film having a prismatic columnar structure. The method according to claim 5, An optical film in which prismatic columnar structures are connected and at least some of the particles satisfy the following equation:

In the above formula, H represents the vertical distance between the vertex of the columnar structure and the bottom, 2θ represents the normal angle of the columnar structure, and R represents the radius of the organic particles. The method according to claim 1, The columnar structure is an optical film which is a linear columnar structure, an S-shaped columnar structure, a zigzag columnar structure, or a combination thereof. The method according to claim 1, The columnar structure is an optical film having a linear columnar structure. The method according to claim 1, The organic particles have an average particle size, and the particle size of the organic particles is in the range of ± 30% of the average particle size; The organic particles are in an amount of 100 to 300 parts by weight per 100 parts by weight of solids of the binder. The method according to claim 1, The average particle size of the organic particles is 1 µm to 100 µm. The method according to claim 9, The optical film has a particle size in the range of ± 15% of the average particle size. The method according to claim 1, The optical film on which the substrate and the microstructures thereon are integrally formed together. The method according to claim 1, A substrate having a microstructure is formed by applying a plurality of columnar structures on the surface of the substrate. The method according to claim 1, The organic particles are selected from the group consisting of polyacrylate resins, polymethacrylate resins, polystyrene resins, urethane resins, silicone resins and mixtures thereof. The method according to claim 1, The surface of the substrate opposite the surface with the resin coating comprises an anti-stick layer. A substrate having a microstructure; And An optical film comprising a resin coating comprising a plurality of organic particles and a binder and disposed on a microstructure of a substrate, The organic particles are polymethacrylate resins comprising, as polymerizable units, at least one acrylate monomer having a single functional group and at least one acrylate monomer having a polyfunctional group, wherein the amount of the acrylate monomer having a multifunctional group is the monomer total weight. 30 to 70% by weight relative to the organic particles having an average particle size, the particle size of the organic particles is in the range of ± 30% of the average particle size, the organic particles are in an amount of 100 to 300 parts by weight per 100 parts by weight of the solid content of the binder Optical film. 18. The method of claim 16, The microstructure comprises a plurality of continuously connected and equilateral parallel prismatic columnar structures, wherein the organic particles are tangent to the columnar structure, and at least some of the organic particles satisfy the equation H _b ≧ H, where H _b is Optical film showing the vertical distance between the vertex of the organic particles and the bottom of the columnar structure, H is the vertical distance between the vertex of the columnar structure and the bottom. 18. The method of claim 16, The polyacrylate resin is formed from a monomer comprising methyl methacrylate and ethylene glycol dimethacrylate. 19. The method of claim 18, The ethylene glycol dimethacrylate monomer is 30 to 70% by weight based on the total amount of monomers. 18. The method of claim 16, The thickness of the resin coating is 5 µm to 30 µm in an optical film. 18. The method of claim 16, The average particle size of organic particle | grains is an optical film in the range of 2 micrometers-50 micrometers. 18. The method of claim 16, The organic particles in the resin coating are in an amount of 100 to 300 parts by weight per 100 parts by weight of solids of the binder. 18. The method of claim 16, The substrate is an optical film selected from the group consisting of polyethylene terephthalate, polymethyl methacrylate, polycycloolefin resin, triacetate cellulose, polylactic acid and mixtures thereof. 18. The method of claim 16, The binder is an optical film selected from the group consisting of UV-curable resins, thermosetting resins, thermoplastic resins and mixtures thereof.

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