KR102106810B1 - Manufacturing method of light-diffusing film and backlight unit - Google Patents

Abstract

The present invention relates to a light diffusion film, a manufacturing method thereof, and a backlight unit for a liquid crystal display employing the same.
In the light-diffusion film of the present invention, at least two or more layers of the fiber layers arranged in parallel in one direction are alternately arranged in the transparent polymer resin layer, and in particular, an angle of 90 °, ± θ compared to the arrangement direction of the fibers constituting the fiber layer Alternatively, depending on the structural characteristics of the multi-axis alternating arrangement at an angle combination of ± θ after the 90 ° alignment, the incident light source is scattered in two dimensions to realize a uniform light diffusion effect regardless of the direction of the initial incident light. Accordingly, the light-diffusion film of the present invention excellent in uniform light diffusion effect can be used instead of the conventional bead-type light-diffusion film, and by employing the same, the backlight unit for a liquid crystal display with improved physical properties of excellent hiding power and light diffusion effect is improved. Can provide.

Description

Manufacturing method of light diffusion film and backlight unit for liquid crystal display employing the same {MANUFACTURING METHOD OF LIGHT-DIFFUSING FILM AND BACKLIGHT UNIT}

The present invention relates to a light-diffusion film, a method for manufacturing the same, and a backlight unit for a liquid crystal display employing the same, more specifically, a structure in which at least two or more layers of fiber layers arranged in parallel in one direction are alternately arranged in a transparent polymer resin layer. As, as the light source is scattered in two dimensions, a novel light diffusion film that realizes a uniform light diffusion effect irrespective of the direction of the initial incident light, a manufacturing method thereof, and a backlight unit for a liquid crystal display employing the same .

Since the liquid crystal display cannot emit light by itself, it requires bright and uniform white light from the outside. Such a device that supplies light from the back of the LCD is called a backlight unit.

The backlight unit (BLU) is a very important core component that affects the chromaticity, contrast, and image quality of a liquid crystal display (LCD), and its performance improvement is continuously required.

In recent years, the BLU industry is developing optical films with improved performance or researching on composite optical components that integrate several sheets of optical films into one.

In particular, the light-diffusion film for a liquid crystal display backlight unit passes a light from linear light irradiated from a cold cathode fluorescent lamp located on the side or rear to obtain a clear image of the display, and induces uniform surface light to obtain a clear light image. do.

Therefore, in the field of the light diffusion film for a liquid crystal display backlight unit, the focus is on the development of a light diffusion film having a function of concealing and uniformly diffusing light that is radiated from the light source lamp and passes through the diffusion plate or the light guide plate without loss.

In general, a light-diffusion film is known as a form in which a light-diffusing layer is formed by using transparent organic particles or inorganic particles as a light-diffusing agent on a transparent plastic film and applying a transparent resin binder [Japanese Patent Publication No. Hei 7-174909, 2000-27862 and 1998-20430]. However, the light-diffusion film of the present invention has a problem in that luminance is lowered because light passes directly without refraction or scattering due to a cross-section in which the light-diffusion layer is formed using transparent organic particles or inorganic particles having a constant average particle diameter.

Therefore, the bead-type light-diffusion film of conventional organic particles or inorganic particles, etc., depends on the type, size, refractive index control and dispersion degree of the light-diffusion agent particles used, the hiding power and luminance characteristics of the light-diffusion film depend. .

Other types of light-diffusion films include uniformly distributed light intensity from a light source, or to improve the brightness of a screen, by placing anisotropic particles in an isotropic material at specific intervals (Japanese Publication No. Hei 11-509014), or multiple birefringence A form in which fibers are arranged in parallel is known (Japanese Publication No. 2003-302507).

However, the known light-diffusion film arranges the spun fibers on an isotropic material and then bonds them with a press.

3 is a cross-sectional photograph of a conventional light-diffusion film, in the case of a light-diffusion film manufactured in this way, the fiber layer in the film is agglomerated, resulting in loss of light due to back scattering scattered from the back with respect to the direction of incident light travel Due to this size, the problem that the display becomes dark is pointed out. Accordingly, there is a demand for a light diffusion film capable of efficiently diffusing light forward.

Accordingly, the present inventors tried to solve the problems of the conventional light diffusion film, and as a result, in the transparent polymer resin layer, at least two or more layers of fiber layers arranged in parallel in one direction are alternately arranged, due to two-dimensional scattering of the incident light source. By showing excellent hiding power and light diffusion effect, it was confirmed that it is useful as a light diffusion film for a liquid crystal display backlight unit, thereby completing the present invention.

An object of the present invention is to provide a matrix-type light-diffusing film in which at least two or more layers of fiber layers are arranged in parallel in one direction in a transparent polymer resin layer.

Another object of the present invention is to provide a method for manufacturing the light-diffusion film.

Another object of the present invention is to provide a backlight unit for a liquid crystal display employing a light diffusion film.

In order to achieve the above object, the present invention provides a matrix-type light-diffusion film in which at least two or more layers of fiber layers are arranged in parallel in one direction in a transparent polymer resin layer.

In the light-diffusion film of the present invention, the transparent polymer resin layer is made of an isotropic or anisotropic polymer resin.

In the light-diffusion film of the present invention, the fiber layers are arranged in parallel while maintaining a constant distance between surrounding fibers. At this time, it is preferable that the multi-axis is alternately arranged in an angle combination of 90 °, ± θ with respect to the arrangement direction of the nanofibers, or an angle of ± θ after 90 ° alignment.

At this time, it is preferable that the fiber layers are alternately arranged in two or more layers, more preferably in two to five layers.

In addition, a birefringent organic fiber is used as the fiber layer, and more preferably, the refractive index of the organic fiber is designed to be higher than the refractive index of the polymer resin constituting the transparent polymer resin layer. According to the refractive index design, a light transmittance of 40% or more is realized.

Preferred organic fibers used in the fiber layer of the present invention include polyethylene naphthalate (PEN), copolyethylene naphthalate (co-PEN), polyethylene terephthalate (PET), polycarbonate (PC), polycarbonate (PC) alloy, Polystyrene (PS), heat-resistant polystyrene (PS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), poly Urethane (PU), polyimide (PI), polyvinyl chloride (PVC), styrene acrylonitrile blend (SAN), ethylene vinyl acetate (EVA), polyamide (PA), polyacetal (POM), phenol, epoxy (EP), urea (UF), melamine (MF), unsaturated polyester (UP), silicone (SI), and one or more selected from the group consisting of an elastomer and a cycloolefin polymer.

In addition, the organic fiber constituting the fiber layer is a cross section selected from circles, triangles, or squares; Or it may have a heterogeneous cross-section of these combinations.

Accordingly, the present invention 1) birefringent organic fiber and transparent polymer resin is used in a weight ratio of 1: 9 to 5: 5, and the birefringent organic fiber and transparent polymer resin are simultaneously introduced into an extruder including a bicomponent composite nozzle and extruded. And through the two-component composite nozzle,
Inside the transparent polymer resin layer made of the transparent polymer resin, arranged to be arranged in parallel in one direction while maintaining the spacing between the birefringent organic fibers, and continuously orthogonal to the arrangement direction of the birefringent organic fibers (90 ° arrangement) or After the orthogonal arrangement, the fiber layers are formed by stacking them so that they are alternately arranged in multiple axes by arranging at an angle of diagonal (± θ after arranging 90 °),

2) After the extrusion, a method of manufacturing a light-diffusion film is performed by continuously stretching and cooling processes.

In addition, as another manufacturing method of the present invention, 1) to form a single-layer fiber layer disposed in parallel in one direction in the transparent polymer resin layer, 2) 90˚, ± θ with respect to the arrangement direction of the fiber layer of the single layer Provided is a method of manufacturing a light-diffusion film consisting of at least two or more layers of crossing in an angle combination of ± θ after an angle of 90 ° or 90 ° array, and 3) complexing them.

In this case, the complexation may be performed by any one selected from the group consisting of a double belt press method, a lamination method, and a calendar method.

Furthermore, the present invention provides a backlight unit for a liquid crystal display employing the light diffusion film.

According to the present invention, in the transparent polymer resin layer, it is possible to provide a matrix type light-diffusion film in which at least two or more layers of fiber layers arranged in parallel in one direction are alternately arranged.

The light-diffusion film of the present invention implements a uniform light-diffusion effect regardless of the direction of the initial incident light by the two-dimensional scattering of the incident light source by a multi-axis alternating fiber layer in the transparent polymer resin layer, so that the conventional bead-type light Diffusion films can alternatively be used.

In addition, the light-diffusion film of the present invention can be produced by composite spinning, and by employing the light-diffusion film obtained therefrom, it is possible to provide a backlight unit for a liquid crystal display with improved physical properties of excellent hiding power and light diffusion effect.

1 is a schematic view of the light-diffusion film structure of the present invention,
2 is a cross-sectional photograph of the light diffusion film of the present invention,
3 is a cross-sectional photograph of a conventional light diffusion film,
Figure 4 is a picture of observing the birefringence of the light diffusing film of the present invention according to the distance between the cross polarizer (a is 45˚, b is 0˚),
5 is a surface photograph of nanofibers constituting the light-diffusion film of the present invention,
6 is a scattering pattern experiment results for the light diffusion film of the present invention,
FIG. 7 shows the contour map and light distribution angle measurement results along the horizontal (0 °), diagonal (45 °) and vertical (90 °) angles for the light-diffusion film of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention provides a matrix type light-diffusion film (1) in which at least two or more layers of fiber layers (10) are arranged in parallel in a transparent polymer resin layer (20).

1 shows the light-diffusion film structure of the present invention, in the isotropic or anisotropic transparent polymer resin layer 20, the fiber layers 10 disposed in parallel in one direction alternately arranged in at least two or more mutually orthogonal directions Structure. As shown in FIG. 1, in the light-diffusion film of the present invention, fibers are disposed parallel to one direction in a transparent polymer resin layer (n _p ), and are continuously stacked in mutually orthogonal directions with respect to the fibers. The light source incident by this structure is scattered in two dimensions.

At this time, the transparent polymer resin layer (n _p ) used in the embodiment of the present invention is isotropic or anisotropic, and the organic fibers 11 constituting the fiber layer 10 have an extraordinary refractive index (n _e ) of 1.650 and 1.460 It is a birefringent material having an (ordinary) refractive index (n _o ), and the refractive index will not be limited thereto.

2 is a cross-sectional photograph of the light-diffusion film of the present invention, in the light-diffusion film 1, the fiber layer 10 is arranged in parallel while maintaining a constant distance between the surrounding fibers. In addition, the fiber layer 10 in which at least two or more layers are alternately arranged is preferably multi-axis alternately arranged in an angle combination of 90 degrees, ± θ, or 90 degrees after 90 degrees alignment with respect to the arrangement direction of the fibers. As the most preferred example, in the embodiment of the present invention, the description is limited to the mutually orthogonal (90 °) direction, but when spaced apart between the organic fibers of the fiber layers and two or more layers are alternately arranged, diagonal lines are arranged at a constant angle (± θ). Or, it may be performed at an angle combination of ± θ after orthogonal (90 °) arrangement.

In the light-diffusion film 1 of the present invention, the fiber layer 10 has a structure in which at least two or more layers are stacked, and more preferably, it is alternately arranged in 2 to 5 layers. At this time, if the fibrous layer 10 has a single-layer structure of less than two layers, there is a problem in that one-dimensional scattering occurs, and if it is stacked in excess of five layers, light loss increases due to absorption and reflection of light occurring in each layer. It is not desirable.

In the light-diffusion film 1 of the present invention, the organic fibers 11 constituting the fiber layer 10 are birefringent organic fibers are used, and more preferably, the polymers in which the refractive index of the organic nanofibers are transparent polymer resin layers It is designed to be more than 0.05 higher than the refractive index of the resin. According to the refractive index design, a light transmittance of 40% or more is realized.

Preferred examples of the organic fiber 11 used in the fiber layer 10 of the present invention are polyethylene naphthalate (PEN), copolyethylene naphthalate (co-PEN), polyethylene terephthalate (PET), polycarbonate (PC), Polycarbonate (PC) alloy, polystyrene (PS), heat-resistant polystyrene (PS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), acrylic Nitrile Butadiene Styrene (ABS), Polyurethane (PU), Polyimide (PI), Polyvinyl Chloride (PVC), Styrene Acrylonitrile Mixture (SAN), Vinyl Ethylene Acetate (EVA), Polyamide (PA), Poly Use one or more selected from the group consisting of acetal (POM), phenol, epoxy (EP), urea (UF), melamine (MF), unsaturated polyester (UP), silicone (SI), elastomer and cycloolefin polymer. do. In the embodiment of the present invention, polyethylene naphthalate (PEN) is selected and described as the most preferable material, but will not be limited thereto.

Figure 4 is a photograph of the birefringence of the light diffusing film (1) of the present invention according to the distance from the cross polarizer, a is 45 °, when the highest transmittance can be confirmed, b is 0 ° or 90 ° In this case, the result of zero transmittance can be confirmed.

When explaining mainly the embodiment of the present invention, the monolayer light-diffusion film in which the fiber layer 10 is arranged in one direction parallel to the isotropic polymer numerical layer 20 exhibits birefringence. Specifically, when placed at the angle Ψ with the cross polarizer, the transmittance of the light-diffusing film exhibiting birefringence is calculated in the following equations (1) and (2).

At this time, from the equations (1) and (2), when the angle Ψ is 45, the transmittance is the highest, whereas, when the angle Ψ is 0˚ or 90˚, it shows the transmittance of the zero value, Figure 4 From the results, the birefringence can be confirmed by the arrangement of the fiber layers 10 in the polymer resin layer 20 in the light-diffusion film 1 of the present invention.

Figure 5 4 is a surface photograph of the nanofibers constituting the light diffusion film.

6 is a scattering pattern test result for the light-diffusion film of the present invention, the light guide plate (Light Guide Plate, LGP) portion of the backlight unit is observed a dot-shaped spot, here, a single layer of a transparent polymer resin layer As a result of placing the light diffusion film with the nanofiber layer embedded therein, a fine dot-like spot is still observed, so that a sufficient diffusion effect cannot be expected. On the other hand, in the case of a structure in which the nanofiber layer 10 is alternately arranged in two layers on the transparent polymer resin layer 20, the light-diffusion film 1 of the present invention exhibits excellent hiding power in which dot spots are hardly observed.

Accordingly, the light source incident by the structure of the light diffusion film 1 of the present invention is scattered two-dimensionally, so that light can be uniformly diffused regardless of the direction of the initial incident light.

FIG. 7 shows the contour map and light distribution angle measurement results along the horizontal (0 °), diagonal (45 °) and vertical (90 °) angles for the light-diffusion film of the present invention.

Specifically, FIG. 7 (a) is a case where only the LGP is measured without the light diffusion film of the present invention, and the light distribution angle is not uniform due to the white dot-like spot on the LGP surface, while (b) the light diffusion of the present invention In the results for the film, it is possible to confirm a remarkably uniform light distribution angle since it passes through the light diffusion film through LGP.

Accordingly, the light-diffusion film of the present invention is a one-dimensional scattering (scattering polarizing plate) for selective polarization and the light transparency by a more transparent polymer resin combination is improved to realize a uniform light diffusion effect, so a conventional bead type light diffusion film Can be used instead.

Furthermore, in the light-diffusion film 1 of the present invention, the circular cross section of the organic fiber 11 constituting the fiber layer 10 is described, but is not limited thereto, and is selected from circles, triangles, or squares. Any one cross section; Or it may have a release cross-section of these combinations, and at this time, it may be designed by changing the fiber material and the refractive index between the fibers constituting the release cross-section.

In the light-diffusion film (1) of the present invention, the transparent polymer resin layer 20 may be used without particular limitation as long as it is a transparent resin that can be used for optical purposes, and preferred examples include polymethyl methacrylate (PMMA), It can be selected from polystyrene (PS), polyethylene terephthalate (PET), random copolymer resin of styrene and methyl methacrylate (MS resin) or polycarbonate (PC).

In addition, since the transparent polymer resin layer 20 of the present invention forms a transparent polymer resin layer 20 and a fiber layer 10 by complex spinning a transparent polymer resin and fibers, the transparent polymer resin used is not limited to isotropy. Anisotropic materials can be used.

The present invention provides a method for manufacturing the light diffusion film.

The preferred method of manufacturing the first embodiment of the present invention is 1) using birefringent organic fiber and transparent polymer resin in a weight ratio of 1: 9 to 5: 5, and using the birefringent organic fiber and transparent polymer resin bicomponent composite nozzle Simultaneous injection into the included extruder and extrusion through the bicomponent composite nozzle,
Inside the transparent polymer resin layer made of the transparent polymer resin, arranged to be arranged in parallel in one direction while maintaining the spacing between the birefringent organic fibers, and continuously orthogonal (90 ° arrangement) to the arrangement direction of the birefringent organic fibers or After the orthogonal arrangement, the fiber layers are formed by stacking them so that they are alternately arranged in multiple axes by arranging at an angle of a diagonal line (± θ after arranging 90 °),

2) After the extrusion, stretching and cooling are continuously performed.

In the step 1), the transparent polymer resin layer 20, the fiber layer 10 made of birefringent organic fibers is contained in 10 to 90% by weight, more preferably 10 to 80% by weight. At this time, when the content of the birefringent organic nanofiber is 90% by weight or more, scattering of light is greatly generated, which is not preferable.

In addition, the fibers in the step 1) can be obtained by extruding the melt of the above component into a two-component composite nozzle and spinning at a spinning speed of 1 to 7 km / min to obtain nanofibers meeting the nano size of 500 nm or less in fiber diameter. In addition, it can be made of filament-like nano-long fibers by the high-speed spinning. At this time, in the embodiment of the present invention, a bicomponent composite nozzle having 3,800 holes is used, but the hole in the spinneret is not limited to this because it can be extended and applied around the above range.

Among the manufacturing methods of the present invention, the desired birefringence of the fiber layer can be realized by the stretching step in step 2). That is, in the embodiment of the present invention, the organic fiber 11 constituting the fiber layer has birefringence having an extraordinary refractive index (n _e ) of 1.650 and an ordinary refractive index (n _o ) of 1.460.

In addition, the transparent polymer resin layer 20 is preferably isotropic, but anisotropic polymer resin may be used.

In addition, the manufacturing method of the second preferred embodiment of the present invention is 1) birefringent organic fiber and transparent polymer resin is used in a weight ratio of 1: 9 to 5: 5, and the birefringent organic fiber and transparent polymer resin are bicomponent composites. Simultaneously injected into an extruder including a nozzle and extruded through the bicomponent composite nozzle,
Inside the transparent polymer resin layer made of the transparent polymer resin, the birefringent organic fibers are arranged to be arranged in parallel in one direction while maintaining the spacing, and successively alternately arranged in an orthogonal direction to the arrangement direction of the birefringent organic fibers. After manufacturing the light-diffusion film in which the layered fiber layer of the two-layer structure is formed, and 2) at least two or more of the light-diffusion films of step 1) are orthogonal to each other (arrangement of 90 degrees) or the orthogonal to each other. It consists of laminating so as to be alternately arranged in multiple axes at an angle of diagonal (± θ after 90 ° arrangement), and 3) continuously compounding them.

In the above manufacturing method, step 1) is a step of forming a single-layer fiber layer, and the description of the transparent polymer resin layer and the fiber layer is the same as above, so a detailed description is omitted.

The process of alternately arranging at least two or more layers in the step 2) is preferably to stack up to 2 to 5 layers, and when alternately arranging each layer, preferably arranged in an orthogonal (90 °) with respect to the arrangement direction of the nanofibers. Thus, it can be produced in a grid form, and is not limited thereto, and may be arranged diagonally at a constant angle (± θ), or may be performed in an angle combination of ± θ after orthogonal (90 °) arrangement.

In the manufacturing method of the present invention, the complexing in step 3) is performed by a heat bonding method, and more preferably, it can be performed at any one selected from the group consisting of a double belt press method, a lamination method, and a calendar method at 100 to 220 ° C. have.

Furthermore, the present invention provides a backlight unit for a liquid crystal display employing a light diffusion film.

The light-diffusing film 1 of the present invention has a structure in which at least two or more layers of the nanofiber layers 10 arranged in parallel in one direction are alternately arranged in the transparent polymer resin layer 20. It is scattered dimensionally, and can diffuse light uniformly regardless of the direction of the initial incident light.

Thus, since the light diffusion film 1 of the present invention has excellent uniform light diffusion effect, a conventional bead type light diffusion film can be used as an alternative, and by adopting the same, the liquid crystal having improved physical properties of excellent hiding power and light diffusion effect is improved. A backlight unit for a display can be provided.

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

This example is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

< Example  1>

RT 18)를 1:9 중량비율로 혼합하고, 상기 복굴절성의 유기섬유 및 투명 고분자 수지를 이성분 복합 노즐을 포함한 압출기에 동시 투입하여 압출시키되, 상기 이성분 복합 노즐을 통해, 상기 유기 나노섬유가 고분자 수지로 이루어진 층상에 일 방향으로 평행하게 배치되도록 하고 연속적으로 상기 나노섬유의 배열방향 대비 직교방향으로 교대 배열하여 2층의 적층 구조로 압출하였다. 이후 공기를 불어주면서 신속히 냉각 및 경화시키고, 고온 고압 공기에 의해 연신공정을 수행하였다. 상기 연신공정에 의해 원하는 복굴절성을 가지는 나노섬유를 얻었다. 상기 나노섬유의 정상(ordinary) 굴절률(n_o)은 등방성의 투명 고분자 수지층(n_p)과 일치하고, 나노섬유의 이상(extraordinary) 굴절률(n_e)은 등방성의 투명 고분자 수지층(n_p)과 불일치하였으며, 이때, 나노섬유의 이상(extraordinary) 굴절률(n_e)과 정상(ordinary) 굴절률(n_o) 수치는 각각 1.650과 1.460이었다. As a nanofiber component, polyethylenenaphthalate (PEN) was melted, and spinning was performed at a speed of 1 km / min through a spinning nozzle having 3,800 holes in a pressurized state to prepare organic nanofibers. The prepared 3,800 organic nanofibers and transparent polymer resin (TPX

RT 18) is mixed at a weight ratio of 1: 9, and the birefringent organic fiber and transparent polymer resin are simultaneously put into an extruder including a bicomponent composite nozzle and extruded. Through the bicomponent composite nozzle, the organic nanofiber is On a layer made of a polymer resin, it was arranged to be parallel in one direction, and successively alternately arranged in an orthogonal direction to the arrangement direction of the nanofibers and extruded into a two-layer stacked structure. Then, while blowing and rapidly cooling and curing the air, the stretching process was performed by high temperature and high pressure air. Nanofibers having a desired birefringence were obtained by the stretching process. The normal (ordinary) refractive index (n _o ) of the nanofibers coincides with the isotropic transparent polymer resin layer (n _p ), and the extraordinary refractive index (n _e ) of the nanofibers is isotropic transparent polymer resin layer (n _p) ), And the nanofibers had extraordinary refractive index (n _e ) and normal refractive index (n _o ) values of 1.650 and 1.460, respectively.

< Example  2>

RT 18)로 이루어진 수지층 내에 복굴절성 나노섬유가 일 방향으로 평행하게 배치되고 연속적으로 상기 배치방향에 대하여 직교방향으로 교대 배열된 2층 구조의 광확산 필름을 제조하였다. Transparent polymer resin layer in Example 1 (TPX

In the resin layer made of RT 18), birefringent nanofibers were arranged in parallel in one direction, and a light-diffusing film having a two-layer structure was continuously arranged alternately in the direction perpendicular to the placement direction.

The two sheets of the light-diffusing film were superimposed so as to be orthogonal to the arrangement direction of the nanofibers arranged in the nanofiber layer, and heat-sealed in a double belt press with a belt speed of 1.0 m / min maintained at 195 ° C, to form a four-layer nanofiber layer A light diffusion film alternately arranged in the transparent polymer resin layer was prepared.

< Example  3>

RT 18)를 4:6 중량비율로 혼합하여 동시 압출하는 것을 제외하고는 상기 실시예 1과 동일하게 수행하여 광확산 필름을 제조하였다. Organic nanofiber and transparent polymer resin prepared in Example 1 (TPX

RT 18) was mixed in a 4: 6 weight ratio to prepare a light-diffusing film by performing the same method as in Example 1, except for co-extrusion.

< Example  4>

RT 18)를 5:5 중량비율로 혼합하여 동시 압출하는 것을 제외하고는 상기 실시예 1과 동일하게 수행하여 광확산 필름을 제조하였다. Organic nanofiber and transparent polymer resin prepared in Example 1 (TPX

RT 18) was mixed in a 5: 5 weight ratio and co-extruded to prepare a light-diffusing film in the same manner as in Example 1.

< Comparative example  1>

RT 18) 내에 복굴절성 나노섬유가 일 방향으로 평행하게 배치된 나노섬유층이 배열된 단일층 구조의 광확산 필름을 제조하였다.Transparent polymer resin layer in Example 1 (TPX

In RT 18), a light-diffusing film having a single-layer structure in which nanofiber layers in which birefringent nanofibers are arranged in parallel in one direction is arranged was prepared.

< Comparative example  2>

RT 18)를 8:2 중량비율로 혼합하여 동시 압출하는 것을 제외하고는, 상기 실시예 1과 동일하게 수행하여 광확산 필름을 제조하였다. Organic nanofiber and transparent polymer resin prepared in Example 1 (TPX

RT 18) was mixed in an 8: 2 weight ratio, and coextruded to prepare a light-diffusing film in the same manner as in Example 1.

< Experimental Example  1> Birefringence  Measure

The light diffusing film prepared in Example 1 was measured for transmittance when the distance from the cross polarizer was 45 ° or 0 °.

In FIG. 4, a is a result of observing the film surface when placed at an angle of 45 ° from the cross polarizer, while b shows a high transmittance, while b indicates a zero transmittance when set at 0 °.

The above results are consistent with the theoretical birefringence results calculated by the following equations (1) and (2) in the case of a nanofiber layer having a single-layer structure arranged in one direction parallel to the isotropic transparent polymer resin layer, and thus the present invention It supports the well-formed arrangement of the nanofiber layers.

< Experimental example  2> Nanofiber  Surface measurement

The results of measuring the nanofiber layer used in the transmittance experiment performed in Experimental Example 1 with a scanning electron microscope are shown in FIG. 5. As a result, nanofibers smaller than the micro size were confirmed.

< Experimental Example  3> Light diffusion  Measurement of film scattering pattern

In order to measure the scattering pattern of the light-diffusion film prepared in Example 1, the light-diffusion film was placed on a light guide plate (LGP) of the backlight unit to observe the pattern.

The results are shown in FIG. 6. Specifically, when only LGP is raised, dot-like spots are clearly observed, and when a single layer of nanofiber layers is arranged, light incident parallel to the long axis of the nanofibers is transparent to the refractive index (n _e ) of the nanofibers and isotropic be scattered only by the match between the refractive index (n _p) of the polymer resin layer and the vertical light of the long axis of the nanofiber is transmitted by matching the refractive index (n _o) and refractive index (n _p) of the resin layer is a transparent polymer of the nanofibers, Therefore, scattering only in the long axis direction of the nanofibers, dot-shaped spots were still observed.

On the other hand, the light-diffusion film of Example 1 showed excellent hiding power in which dot spots were hardly observed. These results confirmed that the light-diffusion film of Example 1 was due to the two-dimensional scattering of incident light due to structural features in which the nanofiber layers were alternately arranged in two layers in the transparent polymer resin layer.

< Experimental example  4> Light diffusion  Film Optical distribution angle  Measure

In order to confirm the light distribution according to the use of the light-diffusion film prepared in Example 1, the contour map and light distribution measurement along the horizontal (0 °), diagonal (45 °) and vertical (90 °) ELDIM (EZ Contrast XL88 system).

The results are shown in FIG. 7, where (a) is a case where only LGP is measured without the light diffusion film of the present invention, and is horizontal (0 °), oblique (45 °), and vertical due to a white dot spot on the LGP surface. While the light distribution for the (90 °) direction is not uniform, (b) the incident light passes through the light diffusion film of Example 1 through LGP, so horizontal (0 °), oblique (45 °), and vertical (90 °) The uniformity of the light distribution along the direction was confirmed.

As described above, the present invention provides a matrix type light diffusion film in which at least two or more layers of nanofiber layers arranged in parallel in one direction are alternately arranged in a transparent polymer resin layer.

The light-diffusing film of the present invention implements a uniform light-diffusing effect regardless of the direction of the initial incident light by two-dimensional scattering of the incident light source by a multi-axis alternating nanofiber layer arranged in the transparent polymer resin layer. A light diffusing film can be used instead.

Furthermore, the backlight unit for a liquid crystal display employing the light diffusion film of the present invention can expect excellent hiding power and light diffusion effect.

In the above, the present invention has been described in detail only with respect to the described embodiments, but it is apparent to those skilled in the art that various modifications and variations are possible within the scope of the technical idea of the present invention, and it is natural that such modifications and modifications belong to the appended claims.

10: fiber layer
11: Organic fiber
20: transparent polymer resin layer
1: light diffusion film

Claims (7)

1) Birefringent organic fiber and transparent polymer resin are used in a weight ratio of 1: 9 to 5: 5, and the birefringent organic fiber and transparent polymer resin are simultaneously introduced into an extruder including a bicomponent composite nozzle and extruded, and the bicomponent composite Through the nozzle,
Inside the transparent polymer resin layer made of the transparent polymer resin, arranged to be arranged in parallel in one direction while maintaining the spacing between the birefringent organic fibers, and continuously orthogonal to the arrangement direction of the birefringent organic fibers (90 ° arrangement) or After the orthogonal arrangement, the fiber layers are formed by stacking them so that they are alternately arranged in multiple axes by arranging at an angle of diagonal (± θ after arranging 90 °),
2) After the extrusion, stretching and cooling are continuously performed,
When the refractive index of the organic fiber is designed to be 0.05 or higher than the refractive index of the polymer resin of the transparent polymer resin layer, the method of manufacturing a light diffusion film, characterized in that the light transmittance is 40% or more. 1) Birefringent organic fiber and transparent polymer resin are used in a weight ratio of 1: 9 to 5: 5, and the birefringent organic fiber and transparent polymer resin are simultaneously introduced into an extruder including a bicomponent composite nozzle and extruded, and the bicomponent composite Through the nozzle,
Inside the transparent polymer resin layer made of the transparent polymer resin, the birefringent organic fibers are arranged to be arranged in parallel in one direction while maintaining the spacing, and successively alternately arranged in an orthogonal direction to the arrangement direction of the birefringent organic fibers. To prepare a light-diffusion film having a laminated two-layer fiber layer,
2) For at least two or more sheets of the light-diffusion film of step 1), the arrangement direction of each interlayer fiber is mutually orthogonal (90 ° arrangement) or multi-axis alternately arranged at an angle of oblique line (± θ after 90 ° arrangement) after each other. Laminate,
3) This is continuously compounded,
When the refractive index of the organic fiber is designed to be 0.05 or higher than the refractive index of the polymer resin of the transparent polymer resin layer, the method of manufacturing a light diffusion film, characterized in that the light transmittance is 40% or more. delete The method for manufacturing a light-diffusion film according to claim 1 or 2, wherein the fiber layers are alternately arranged in 2 to 5 layers. delete According to claim 1 or claim 2, wherein the cross-section of the organic fiber is any one cross-section selected from a circle, a triangle or a square; Or a release cross-section of these combinations; Method for producing a light-diffusion film, characterized by having. A backlight unit for a liquid crystal display employing a light-diffusion film prepared from claim 1 or 2.

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