KR20150007153A - Light-diffusing film, manufacturing method thereof and backlight unit - Google Patents

Light-diffusing film, manufacturing method thereof and backlight unit Download PDF

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KR20150007153A
KR20150007153A KR20130081208A KR20130081208A KR20150007153A KR 20150007153 A KR20150007153 A KR 20150007153A KR 20130081208 A KR20130081208 A KR 20130081208A KR 20130081208 A KR20130081208 A KR 20130081208A KR 20150007153 A KR20150007153 A KR 20150007153A
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light
polymer resin
layers
fiber
layer
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KR20130081208A
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Korean (ko)
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임대영
정원영
김태형
최석원
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한국생산기술연구원
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/04—Prisms
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors

Abstract

The present invention relates to a light-diffusing film, a method of manufacturing the same, and a backlight unit for a liquid crystal display employing the same. In the light-diffusing film of the present invention, at least two layers of fiber layers disposed in one direction in parallel, are alternately aligned within a transparent polymer resin layer, and especially, incident light is scattered two-dimensionally due to a structural characteristic in which at least two layers are arranged in a multi-axis alternation by a combination of 90°, an angle of ±θ, or ±θ after 90° arrangement with respect to an arrangement direction of a fiber constituting the fiber layers, thereby realizing an uniform light-diffusing effect regardless of a direction of initial incident light. Therefore, the light-diffusing film of the present invention having an excellent uniform light-diffusing can replace a typical bead-type light-diffusing film. The present invention can provide a backlight unit for a liquid crystal display excellent in hiding power and improved in a light-diffusing effect by employing the light-emitting film.

Description

TECHNICAL FIELD [0001] The present invention relates to a light diffusion film, a method of manufacturing the same, and a backlight unit for a liquid crystal display employing the same. BACKGROUND ART [0002] LIGHT- DIFFUSING FILM, MANUFACTURING METHOD THEREOF AND BACKLIGHT UNIT,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusion film, a method of manufacturing the same, and a backlight unit for a liquid crystal display employing the same. More particularly, To a novel light diffusion film which realizes a uniform light diffusion effect irrespective of the direction of the initial incident light as the incident light source is two-dimensionally scattered, a manufacturing method thereof, and a backlight unit for a liquid crystal display employing the same .

Liquid crystal displays (LCDs) can not emit themselves, so they need bright, uniform white light from the outside. In this way, a device that supplies light from the back of the LCD is called a backlight unit (backlight unit).

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

Recently, in the BLU industry, research is being conducted on composite optical components that develop improved optical films or integrate multiple optical films into one.

In particular, a light diffusion film for a liquid crystal display backlight unit is formed by passing light from a linear light emitted from a cold cathode fluorescent lamp located on a side or a rear surface in order to obtain a clear image of a display, do.

Accordingly, 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 concealing function for uniformly diffusing light transmitted through a diffusion plate or a light guide plate from a light source lamp without loss.

It is generally known that a light diffusion film is formed by using transparent organic particles or inorganic particles as a light diffusing agent on a transparent plastic film and coating the resultant with a transparent resin binder to form a light diffusion layer (JP-A-7-174909, 2000-27862 and 1998-20430]. However, since the light diffusion film of the present invention uses transparent organic particles or inorganic particles having a constant average particle size, the light is directly transmitted without refraction or scattering due to the cross section where the light diffusion layer is formed.

Therefore, the bead type light diffusing film such as organic particles or inorganic particles depends on the type, size, refractive index control and dispersion degree of the light diffusing agent particle to be used, and the hiding power and luminance characteristic of the light diffusing film are influenced .

As another type of light diffusion film, anisotropic particles are arranged at specific intervals in an isotropic material to uniform the intensity distribution of the light from the light source or to improve the brightness of the screen [Japanese Laid-open Patent Publication No. 11-509014] And a form in which the fibers are arranged in parallel is known (Japanese Laid-Open Patent Publication No. 2003-302507).

However, in the known light diffusion film, the spun fibers are arranged on an isotropic material and then bonded together by a press.

3 is a cross-sectional photograph of a conventional light-diffusing film. In the case of a light-diffusing film produced in this manner, a fiber bundle in a film is a bundle of fiber bundles, and light loss due to back scattering, which is scattered backward with respect to the traveling direction of incident light Because of this size, it is pointed out that the display becomes dark. Accordingly, there is a demand for a light diffusion film capable of efficiently diffusing light forward.

The present inventors have made efforts to solve the problems of the conventional light diffusion film. As a result, the present inventors have found that at least two layers of fibers arranged in parallel in one direction are alternately arranged in the transparent polymer resin layer, It is proved that it is useful as a light diffusion film for a liquid crystal display backlight unit because it exhibits excellent hiding power and light diffusion effect.

An object of the present invention is to provide a matrix type light diffusion film in which at least two fibrous layers arranged in parallel in one direction in a transparent polymer resin layer are alternately arranged.

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

It is still another object of the present invention 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 fibrous layers arranged in parallel in one direction are alternately arranged 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-diffusing film of the present invention, the fibrous layers are arranged parallel to each other while maintaining a constant gap between the peripheral fibers. At this time, it is preferable that the nanofibers are alternately arranged in the multiaxial arrangement with an angle of 90 [deg.], An angle of [theta] [theta] or an angle of + [theta] after 90 [deg.].

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

The birefringent organic fiber is used as the fiber layer, and more preferably the refractive index of the organic fiber is designed to be 0.05 or more 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 for use in the fibrous layer of the present invention include polyethylene naphthalate (PEN), copolyethylene naphthalate (co-PEN), polyethylene terephthalate (PET), polycarbonate (PC), polycarbonate (PS), heat-resistant polystyrene (PS), polymethylmethacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (PU), polyimide (PI), polyvinyl chloride (PVC), styrene acrylonitrile blend (SAN), ethylene vinyl acetate (EVA), polyamide (PA), polyacetal (EP), urea (UF), melamine (MF), unsaturated polyester (UP), silicone (SI), elastomers and cycloolefin polymers.

The organic fibers constituting the fibrous layer may have a cross section selected from a circle, triangle or square; Or a modified cross section of these combinations.

Accordingly, the present invention provides: 1) a transparent polymer resin component and a birefringent fiber component are arranged in parallel in one direction in a transparent polymer resin layer through a two-component composite nozzle, Or a combination of angles of ± θ after 90 ° arrangement, a nanofiber layer is formed so that at least two layers are alternately arranged in multiple axes,

2) After the above process, a process for producing a light diffusion film in which a stretching and cooling process is performed is provided.

Further, as another manufacturing method of the present invention, there is provided a method for producing a single-layer fiber layer, comprising the steps of: 1) forming a single-layer fiber layer disposed in parallel in one direction in a transparent polymer resin layer; 2) At least two or more layers are mated in an angle combination of ± θ after 90 ° arrangement, and 3) a composite of the two or more layers is provided.

At this time, the compounding may be performed by any one selected from the group consisting of a double belt press method, a lamination method and a calendar method.

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

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

The light diffusion film of the present invention realizes a uniform light diffusion effect irrespective of the direction of the initial incident light due to the two-dimensional scattering of the incident light source by the multi-axis alternately arranged fiber layers in the transparent polymer resin layer, Diffusion films can be used alternatively.

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

1 is a schematic view of a light diffusion film structure of the present invention,
2 is a cross-sectional photograph of the light-diffusing film of the present invention,
3 is a cross-sectional photograph of a conventional light diffusion film,
4 is a photograph of the birefringence observed in accordance with the distance between the light-diffusing film of the present invention and the crossed polarizer (a is 45 deg. And b is 0 deg.),
5 is a photograph of a surface of a nanofiber constituting the light diffusion film of the present invention,
6 is a scattering pattern experiment result for the light diffusion film of the present invention,
7 shows contour maps and measurement results of light distribution angles according to horizontal (0 deg.), Oblique (45 deg.) And vertical (90 deg.) Angles of 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 fibrous layers (10) arranged in parallel in one direction are alternately arranged in a transparent polymer resin layer (20).

1 shows a light diffusion film structure according to the present invention. In a transparent polymer resin layer 20 of an isotropic or anisotropic phase, fiber layers 10 arranged in parallel in one direction are alternately arranged in at least two mutually orthogonal directions Structure. As shown in Fig. 1, in the light diffusion film of the present invention, fibers are arranged in parallel in one direction in the 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 two-dimensionally scattered.

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 fiber 11 constituting the fiber layer 10 has an extraordinary refractive index n e of 1.450 (N o ) of the birefringent material, where the refractive index is not limited thereto.

Fig. 2 is a cross-sectional photograph of the light diffusion film of the present invention. In the light diffusion film 1, the fibrous layer 10 is arranged in parallel with maintaining a constant gap between the peripheral fibers. Further, it is preferable that the fiber layers 10 alternately arranged in at least two layers are arranged alternately in the multiaxial arrangement with respect to the arrangement direction of the fibers by an angle of 90 [deg.], An angle [theta] However, when two or more layers are alternately arranged, it is possible to arrange the organic fibers in a diagonal arrangement at a certain angle (+ -) Or may be performed with angular combinations of ± θ after orthogonal (90 °) alignment.

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

In the light diffusion film (1) of the present invention, the organic fiber (11) constituting the fiber layer (10) is a birefringent organic fiber, and more preferably the refractive index of the organic nanofiber is a polymer Which is designed to be 0.05 or more higher than the refractive index of the resin. According to the refractive index design, a light transmittance of 40% or more is realized.

Preferable examples of the organic fiber 11 used in the fiber layer 10 of the present invention include polyethylene naphthalate (PEN), co-polyethylene naphthalate (co-PEN), polyethylene terephthalate (PET), polycarbonate (PC) (PS), polystyrene (PS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), acrylonitrile (ABS), polyurethane (PU), polyimide (PI), polyvinyl chloride (PVC), styrene acrylonitrile blend (SAN), ethylene vinyl acetate (EVA), polyamide At least one selected from the group consisting of acetal (POM), phenol, epoxy (EP), urea (UF), melamine (MF), unsaturated polyester (UP), silicone (SI), elastomers and cycloolefin polymers do. In the embodiment of the present invention, polyethylene naphthalate (PEN) is selected as the most preferable material, but the present invention is not limited thereto.

FIG. 4 is a photograph of the birefringence of the light diffusion film 1 of the present invention observed along the interval between the polarizer and the cross polarizer. In the case where a is 45 °, the highest transmittance can be confirmed. B is 0 ° or 90 ° , The result of permeability zero can be confirmed.

With reference to the embodiment of the present invention, a single-layer light diffusion film in which the fibrous layer 10 is arranged in parallel in one direction in an isotropic numerical layer 20 exhibits birefringence. Specifically, the transmittance of the light-diffusing film exhibiting birefringence is calculated by the following equations (1) and (2) when it is placed at the angle? With the crossed polarizer.

Figure pat00001

Figure pat00002

From the above equations (1) and (2), the transmittance is highest when the angle is 45, while when the angle is 0 or 90, the transmittance of the zero value is shown. The birefringence can be confirmed by arranging 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 photograph of the surface of the nanofiber constituting the light diffusion film.

6 is a scattering pattern experiment result of the light diffusion film of the present invention. As a result of the scattering pattern experiment, dot spot is observed at a portion where a light guide plate (LGP) of a backlight unit is located, As a result of placing a light diffusion film embedded with a nano fiber layer, a fine dot-type spot is still observed, so that a sufficient diffusion effect can not be expected. On the other hand, in the light diffusion film 1 of the present invention, when the nanofiber layer 10 is arranged on the transparent polymer resin layer 20 in a two-layer structure, excellent dot coverage is hardly observed.

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

7 shows contour maps and measurement results of light distribution angles according to horizontal (0 deg.), Oblique (45 deg.) And vertical (90 deg.) Angles of the light diffusion film of the present invention.

Specifically, Fig. 7 (a) shows 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 spot of the white color dot on the LGP surface, whereas (b) The result of the film passes through the LGP and passes through the light diffusing film, so that a substantially uniform light distribution angle can be confirmed.

Therefore, the light diffusion film of the present invention has improved light transparency by combining one-dimensional scattering (scattering polarizing plate) for selective polarization and a more transparent polymer resin, so that a uniform light diffusion effect is realized, Can be used alternatively.

Furthermore, although the circular cross section of the organic fiber 11 constituting the fiber layer 10 is described in the light diffusion film 1 of the present invention, the circular cross section is not limited to this, but may be circular, triangular or square Any one section; Or a combination thereof. In this case, it is also possible to design the fiber by changing the fiber material constituting the deformed section and the refractive index between the fibers.

In the light-diffusing film (1) of the present invention, the transparent polymer resin layer (20) is not particularly limited as long as it is a transparent resin generally usable for optical use, and preferred examples thereof include polymethylmethacrylate (PMMA) (PS), polyethylene terephthalate (PET), random copolymer resin (MS resin) of styrene and methyl methacrylate, or polycarbonate (PC).

In addition, the transparent polymer resin layer 20 of the present invention forms the transparent polymer resin layer 20 and the fiber layer 10 by spin-coating the transparent polymer resin and the fiber, so that the transparent polymer resin used is not limited to isotropic Anisotropic materials may be used.

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

The production method of the first preferred embodiment of the present invention is characterized in that 1) a transparent polymer resin component and a birefringent fiber component are arranged in parallel in one direction in the transparent polymer resin layer through a two-component composite nozzle, At least two layers are alternately arranged in the multiaxial arrangement in an angle combination of 90 占 and 占 占 or 占 占 after the arrangement of 90 占,

2) After the above process, the drawing and cooling process are performed.

The fiber layer 10 made of the birefringent organic fibers is contained in the transparent polymer resin layer 20 in the step 1) in an amount of 10 to 90% by weight, more preferably 10 to 80% by weight. At this time, if the content of the birefringent organic nanofibers is 90 wt% or more, scattering of light is largely undesirable.

In addition, the fibers in the step 1) can be obtained by extruding and extruding a 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 a nanofiber satisfying a nano size of a fiber diameter of 500 nm or less . In addition, the nanofiber can be produced by filament-type nanofiber by the high-speed spinning. In this case, the bicomponent composite nozzle having 3800 holes is used in the embodiment of the present invention, but the hole in the spinneret can be extended around the above range, so it is not limited thereto.

In the manufacturing method of the present invention, desired birefringence of the fiber layer can be realized by the stretching process in the step 2). That is, in the embodiment of the present invention, the organic fibers 11 constituting the fiber layer have birefringence with an extraordinary refractive index n e and an ordinary refractive index n o of 1.460.

The transparent polymer resin layer 20 is preferably isotropic, but an anisotropic polymer resin may also be used.

In addition, the manufacturing method of the second preferred embodiment of the present invention is characterized in that (1) a single-layer fiber layer disposed in parallel in one direction in a transparent polymer resin layer is formed, and (2) , An angle of ± θ, or a combination of angles of ± θ after 90 ° arrangement, and 3) composing them.

In the above-mentioned manufacturing method, the 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 described above.

Step 2) is preferably arranged so that the layers are alternately arranged in the order of two to five layers, and arranged alternately at right angles (90 DEG) with respect to the arrangement direction of the nanofibers The present invention is not limited to this, and it may be performed at an angle of ± θ or at an angle of ± θ after orthogonal (90 °) arrangement.

In the production process of the present invention, the compounding in step 3) may be carried out by a thermal bonding method, more preferably at 100 to 220 ° C in any one selected from the group consisting of a double belt press method, a lamination method and a calendar method have.

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

The light diffusion film (1) of the present invention has a structure in which at least two layers of nanofiber layers (10) arranged in parallel in one direction are alternately arranged in the transparent polymer resin layer (20) So that the light can be uniformly diffused irrespective of the direction of the initial incident light.

Therefore, the light diffusion film (1) of the present invention is excellent in uniform light diffusion effect, and thus can be replaced with a conventional bead type light diffusion film. By adopting the light diffusion film, a liquid crystal A backlight unit for a display can be provided.

Hereinafter, the present invention will be described in more detail with reference to Examples.

The present invention is intended to more specifically illustrate the present invention, and the scope of the present invention is not limited to these embodiments.

< Example  1>

Organic nanofibers were prepared by melting polyethylene naphthalate (PEN) as a nanofiber component and spinning at a rate of 1 km / min through a spinning nozzle with 3,800 holes under pressure. The above-prepared 3,800 organic nanofibers and a transparent polymer resin (TPX

Figure pat00003
RT 18) were mixed at a weight ratio of 1: 9 and simultaneously extruded. The organic nanofibers were alternately arranged in a direction orthogonal to the arrangement direction of the nanofibers so that the organic nanofibers were arranged parallel to one direction on the polymer resin layer, Layer laminate structure. Thereafter, the steel sheet was rapidly cooled and cured while blowing air, and the drawing process was performed by high-temperature, high-pressure air. A nanofiber having desired birefringence was obtained by the above stretching process. The ordinary refractive index n o of the nanofiber coincides with the isotropic transparent polymer resin layer n p and the extraordinary refractive index n e of the nanofiber is equal to the refractive index n p of the isotropic transparent polymer resin layer n p The extraordinary refractive index (n e ) and the ordinary refractive index (n o ) of the nanofibers were 1.650 and 1.460, respectively.

< Example  2>

In Example 1, the transparent polymer resin layer (TPX

Figure pat00004
RT 18), the birefringent nanofibers were arranged in one direction in parallel and alternately arranged in the direction orthogonal to the arrangement direction.

Two sheets of the above-prepared light diffusion films were superimposed in a direction orthogonal to the arrangement direction of the nanofibers arranged in the nanofiber layer and thermally adhered to each other in a double belt press at a belt speed of 1.0 m / min maintained at 195 DEG C, A light diffusion film alternately arranged in the transparent polymer resin layer was prepared.

< Example  3>

The organic nanofibers prepared in Example 1 and the transparent polymer resin (TPX

Figure pat00005
RT 18) were mixed in a weight ratio of 4: 6 and co-extruded, to prepare a light diffusion film.

< Example  4>

The organic nanofibers prepared in Example 1 and the transparent polymer resin (TPX

Figure pat00006
RT 18) were mixed at a weight ratio of 5: 5 and co-extruded, to prepare a light diffusion film.

< Comparative Example  1>

In Example 1, the transparent polymer resin layer (TPX

Figure pat00007
RT 18), a light diffusion film having a single layer structure in which nanofiber layers arranged in parallel in one direction were arranged.

< Comparative Example  2>

The organic nanofibers prepared in Example 1 and the transparent polymer resin (TPX

Figure pat00008
RT 18) were mixed in an 8: 2 weight ratio and co-extruded, to prepare a light diffusion film.

< Experimental Example  1> Boldness  Measure

The transmittance of the light diffusion film prepared in Example 1 was measured at an interval of 45 ° or 0 ° with respect to the cross polarizer.

In FIG. 4, a shows a high transmittance as a result of observing the film surface at an interval of 45 degrees with respect to the crossed polarizer, while a transmittance zero value when b is set at 0 degrees is confirmed.

The above results are in agreement with the theoretical birefringence results calculated by the following formulas (1) and (2) in the case of a single-layered nanofiber layer disposed in parallel in one direction in the isotropic transparent polymer resin layer, Of the nanofibers are well formed.

Figure pat00009

Figure pat00010

< Experimental Example  2> Nano fiber layer  Surface measurement

FIG. 5 shows the result of measurement of the nano-fiber layer used in the permeability experiment performed in Experimental Example 1 with a scanning electron microscope. As a result, nanofibers smaller in size than microsize were identified.

< 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 a backlight unit to observe the pattern.

The results are shown in Fig. Specifically, when only the LGP is laid, dot-shaped spots are clearly observed, and when a single-layered nanofiber layer is arranged, the light incident parallel to the long axis of the nanofiber is reflected by the refractive index (n e ) (N p ) of the polymer resin layer, and the perpendicular light to the long axis of the nanofiber is transmitted by matching the refractive index (n o ) of the nanofiber and the refractive index (n p ) of the transparent polymer resin layer Therefore, only the long axis direction of the nanofibers was scattered, and dot-shaped spots were still observed.

On the other hand, the light-diffusing film of Example 1 exhibited excellent hiding power with almost no dot-shaped spot. These results confirmed that the light diffusion film of Example 1 was two-dimensionally scattered by incident light due to the structural feature that the nanofiber layer was alternately arranged in the transparent polymer resin layer and the two-layered structure.

< Experimental Example  4> Light diffusion  Film Light distribution angle  Measure

The contour map and the distribution of the light according to the horizontal (0 °), oblique (45 °) and vertical (90 °) directions were measured by using ELDIM (EZ Contrast XL88 system).

7 shows the result of measurement of only LGP without the light diffusing film of the present invention. FIG. 7 (a) shows the case where only the LGP is measured without the light diffusion film of the present invention, (45 °) and vertical (90 °) directions because the incident light passes through the light diffusion film of Example 1 through the LGP, 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 layers of nanofiber layers arranged in parallel in one direction are alternately arranged in a transparent polymer resin layer.

The light diffusion film of the present invention realizes a uniform light diffusion effect irrespective of the direction of the initial incident light due to the two-dimensional scattering of the incident light source by the nanofiber layer arranged alternately in multiple axes in the transparent polymer resin layer, A light diffusion film may be used instead.

Further, 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.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

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

Claims (13)

In the transparent polymer resin layer,
A matrix type light diffusion film in which at least two fibrous layers arranged in parallel in one direction are alternately arranged. The light-diffusing film according to claim 1, wherein the transparent polymer resin layer is made of an isotropic or anisotropic polymer resin. The light-diffusing film according to claim 1, wherein when the fiber layers are arranged in one direction, a gap between the adjacent fibers is maintained. The light-diffusing film according to claim 1, wherein at least two layers of the fibrous layer are alternately arranged in a multi-axis arrangement at angles of 90 占 and 占 占 or 占 占 after arranging 90 占. The light-diffusing film according to claim 1, wherein the fibrous layer is alternately arranged in two to five layers. The light-diffusing film according to claim 1, wherein the fiber layer is a birefringent organic fiber. The light diffusion film according to claim 6, wherein the refractive index of the organic fiber is designed to be 0.05 or more higher than the refractive index of the polymer resin of the transparent polymer resin layer. 8. The light-diffusing film according to claim 7, wherein the refractive index of the light-diffusing film is 40% or more. 8. The optical fiber according to claim 7, wherein the cross section of the organic fiber is selected from a circle, triangle or square; Or a modified cross section of these combinations. 1) a transparent polymer resin component and a birefringent fiber component are arranged in parallel in one direction in a transparent polymer resin layer through a two-component composite nozzle, and an angle of 90 [deg.] Or an angle of 90 [ The fiber layers are formed so that at least two layers are arranged alternately in multiple axes by angular combination of?
2) After the above step, the stretching and cooling steps are performed. 1) A single-layer fiber layer disposed in parallel in one direction in a transparent polymer resin layer is formed,
2) mating at least two or more layers in an arrangement angle of 90 ° with respect to the arrangement direction of the fiber layers of the single layer or an angle combination of ± θ after 90 ° arrangement,
3) A process for producing a light-diffusing film comprising the step of compounding the same. 12. The method of claim 11, wherein the compounding is selected from the group consisting of a double belt press method, a lamination method and a calendar method. A backlight unit for a liquid crystal display employing the light diffusion film according to any one of claims 1 to 9.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11513263B2 (en) 2019-05-15 2022-11-29 Samsung Electronics Co., Ltd. Light-diffuser, light diffusing adhesive, light diffusing hard coat member, light diffusion film, and image forming apparatus including light diffusion film

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11513263B2 (en) 2019-05-15 2022-11-29 Samsung Electronics Co., Ltd. Light-diffuser, light diffusing adhesive, light diffusing hard coat member, light diffusion film, and image forming apparatus including light diffusion film

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