KR20120079074A - Light-diffusing film, manufacturing method therefor, light-diffusing polarizing plate, and liquid-crystal display device - Google Patents

Abstract

This invention has a light-diffusion layer laminated | stacked on the base film, and in which the translucent microparticles | fine-particles were disperse | distributed, From the base film direction from the normal direction of the light-diffusion layer side with respect to the intensity | strength of the laser beam of wavelength 543.5 which injects in the normal direction of a light-diffusion film The ratio of the intensity of the laser beam transmitted in the 40 ° aura direction is 0.0002 to 0.001%, the sum of the transmission clarity obtained through the four optical combs is 70 to 180%, the total haze and the internal haze is 40 to 70%, and the surface of the light diffusion layer It is a light-diffusion film whose surface haze resulting from shape is less than 2%, and the center line average roughness of the surface of a light-diffusion layer is 0.2 micrometer or less, its manufacturing method, the light-diffusion polarizing plate using this, and a liquid crystal display device.

Description

LIGHT-DIFFUSING FILM, MANUFACTURING METHOD THEREFOR, LIGHT-DIFFUSING POLARIZING PLATE, AND LIQUID-CRYSTAL DISPLAY DEVICE}

The present invention relates to a light diffusing film and a method of manufacturing the same. Moreover, this invention relates to the light-diffusion polarizing plate and the liquid crystal display device which used the said light-diffusion film.

Background Art In recent years, liquid crystal display devices are rapidly being developed for use in mobile phones, PC monitors, televisions, liquid crystal projectors, and the like. In general, the liquid crystal display device operates the liquid crystal in display modes such as twisted nematic (TN) mode, vertical alignment (VA) mode, and in-plane switching (IPS) mode, and electrically controls the light passing through the liquid crystal. Differences in contrast are shown on the screen to display text and images.

In the conventional liquid crystal display device, when the display screen is viewed in the oblique direction, a high contrast cannot be obtained, and furthermore, a good display characteristic cannot be obtained due to the gray level inversion phenomenon in which the contrast of the image is reversed, that is, the viewing angle is different. The problem of being narrow has been pointed out.

As a method for solving the above problems, a technique of providing a light diffusing film on a viewing side surface of a liquid crystal display is known in the art. For example, JP2007-94369-A and JP2002-107512-A disclose a light diffusion film (light diffusion sheet) having a high haze light diffusion layer formed by applying a coating liquid containing fine particles onto a substrate. . By arrange | positioning such a light-diffusion film on the visual recognition side surface of a liquid crystal display device, when viewing the display screen of a liquid crystal display device at an angle, it is possible to widen a viewing angle by the improvement of the contrast fall of an image, or the improvement of the gradation inversion phenomenon.

However, in the conventional light-diffusion film, when sufficient light-diffusion property is provided in order to obtain a wide viewing angle, the transmission sharpness of a display image falls, and also the front contrast of a display image falls, and also the surface diffuse reflection of a light-diffusion layer There was a problem that the so-called whitening that caused the entire screen to appear cloudy occurred. On the contrary, if it was intended to provide sufficient transmission clarity, light diffusivity was insufficient, and a wide viewing angle could not be obtained.

This invention is made | formed in order to solve the said subject, The objective is that both sufficient light diffusivity and sufficient transmission clarity are compatible, Therefore, when applied to a liquid crystal display device, a viewing angle is wide and the front contrast of a display image is high, and the surface It is an object of the present invention to provide a light diffusing film and a method for producing the same, wherein whitening due to diffuse reflection does not occur. Another object of the present invention is to provide a light diffusing polarizing plate and a liquid crystal display device using the light diffusing film.

The present invention includes the following.

As a light-diffusion film which has a <1> base film and the light-diffusion layer laminated | stacked on the said base film, and the translucent microparticles | fine-particles disperse | distributed,

The ratio L ₂ of the intensity L ₂ of the laser beam transmitted in a 40 ° tilt direction from the normal direction on the light diffusion layer side to the intensity L ₁ of the laser light having a wavelength of 543.5 nm incident on the normal direction of the light diffusing film from the base film side. / L ₁ is 0.0002% or more and 0.001% or less,

The sum of transmission sharpness obtained by passing through the optical combs of 0.125 mm, 0.5 mm, 1.0 mm and 2.0 mm is 70% or more and 180% or less,

The total haze is 40% or more and 70% or less, the internal haze is 40% or more and 70% or less, and the surface haze resulting from the surface shape of the light diffusion layer is less than 2%,

The light-diffusion film whose center line average roughness Ra of the surface of the said light-diffusion layer is 0.2 micrometer or less.

The light-diffusion film as described in <1> whose sum of the <2> above-mentioned transmission clarity is 70% or more and 150% or less.

<3> The light-diffusion film as described in <1> or <2> whose said surface haze is 1% or less.

<4> The light-diffusion film in any one of <1>-<3> whose said centerline average roughness Ra is 0.1 micrometer or less.

The light-diffusion film in any one of <1>-<4> whose layer thickness of the <5> said light-diffusion layer is 1 times or more and 3 times or less with respect to the weight average particle diameter of the said translucent microparticles | fine-particles.

<6> The light-diffusion film in any one of <1>-<5> which further contains the reflection prevention layer laminated | stacked on the said light-diffusion layer.

<7> As a manufacturing method of the light-diffusion film as described in <1>,

A method of producing a light-diffusion film comprising the step of applying a resin liquid in which the light-transmitting fine particles are dispersed on the base film, and the step of transferring the mirror surface or uneven surface of the mold to the surface of the layer containing the resin liquid.

The light-diffusion polarizing plate containing the polarizing plate which has <8> at least a polarizing film, and the light-diffusion film in any one of <1>? <6> laminated | stacked on the said polarizing plate so that the said base film side may face the said polarizing plate.

<9> The light-diffusion polarizing plate as described in <8> in which the said polarizing film and the said light-diffusion film are bonded together through an adhesive bond layer.

<10> A liquid crystal display device comprising a backlight device, a light deflecting means, a backlight side polarizing plate, a liquid crystal cell, and a light diffusing polarizing plate according to <8> or <9> in this order.

<11> The said optical deflecting means has two prism films which have a some linear prism on the surface opposing the said backlight side polarizing plate,

One prism film is arranged so that the direction of the ridge line of the linear prism is substantially parallel to the transmission axis of the backlight-side polarizing plate, and the other prism film has the direction of the ridge line of the linear prism of the light diffusing polarizing plate. The liquid crystal display device as described in <10> arrange | positioned so that it may become substantially parallel with a transmission axis.

<12> The liquid crystal display device according to <10> or <11>, further comprising light diffusing means between the backlight device and the light deflecting means.

ADVANTAGE OF THE INVENTION According to this invention, the light-diffusion film and light-diffusion polarizing plate by which sufficient light-diffusion and the outstanding transmission clarity are compatible can be provided. The liquid crystal display device to which the light-diffusion film or light-diffusion polarizing plate with such excellent optical characteristics is applied exhibits a wide viewing angle and high front contrast, and can also prevent whitening due to surface diffuse reflection.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows a preferable example of the light-diffusion film of this invention.
2 is a schematic cross-sectional view showing another preferred example of the light diffusing film of the present invention.
Fig. 3 shows the incident direction of laser light and the direction of transmission scattered light intensity when laser light is incident from the normal line direction on the base film side and the transmission scattered light intensity of the laser light transmitted in the 40 ° tilt direction from the light diffusion layer side normal line direction is measured. It is a perspective view which shows typically.
4 is a schematic cross-sectional view showing still another preferred example of the light diffusing film of the present invention.
5 is a schematic view showing an example of an apparatus for producing the light diffusing film of the present invention.
6 is a schematic cross-sectional view showing a preferred example of the light diffusing polarizing plate of the present invention.
7 is a schematic cross-sectional view showing a preferred example of the liquid crystal display of the present invention.
It is a schematic perspective view for demonstrating the relationship between the ridgeline direction of the linear prism which a prism film has, and the transmission axis direction of a polarizing plate.
9 is a schematic cross-sectional view showing another preferred example of the liquid crystal display of the present invention.
FIG. 10 is a view showing a relationship between light scattering angles (inclined angle with respect to the normal line of the light diffusing film in the emission direction of the transmitted scattered laser light) and relative scattered light intensity in the light diffusing film prepared in Example 1. FIG.
11 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
12 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
It is a schematic sectional drawing which shows another preferable example of the light-diffusion polarizing plate of this invention.
14 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
15 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
16 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
17 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
18 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
19 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
20 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
21 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.
22 is a schematic cross-sectional view showing another preferred example of the light diffusing polarizing plate of the present invention.

<Light Diffusion Film>

1 and 2 are schematic cross-sectional views each showing a preferred example of the light diffusing film of the present invention. The light-diffusion films 100 and 200 shown in FIG. 1 and FIG. 2 which concern on this invention contain the base film 101 and the light-diffusion layer 102 laminated | stacked on the base film 101. FIG. The light diffusing layer 102 is a layer based on the light transmitting resin 103, and the light transmitting fine particles 104 are dispersed in the light transmitting resin 103. In the light diffusing film of the present invention, as in the example shown in FIG. 1, the surface of the light diffusing layer 102 may be formed of a flat surface, or as shown in FIG. 2, the center line average roughness Ra described later is 0.2 μm. As long as it is the following, it may be comprised from the uneven surface. Hereinafter, the light-diffusion film of this invention is demonstrated in detail.

[Optical Properties of Light Diffusion Film]

(1) relative scattered light intensity

Light-diffusing film of the present invention, the 40 ° cant direction from the normal direction of the side light-diffusing layer 102 to the wavelength intensity of laser light L ₁ of the 543.5 nm incident in the normal direction of the light diffusing film from the base film 101 side The ratio L ₂ / L ₁ (relative scattered light intensity) of the intensity L ₂ of the transmitted laser light is within a range of 0.0002% or more and 0.001% or less. That is, with reference to Figure 3, incident from the base film 101 side of the light-scattering film, a wavelength of 543.5 nm in the normal direction A1 of the light diffusion film and the intensity of L ₁ of laser light (He-Ne laser with a collimated light) The relative scattered light intensity L ₂ / L ₁ obtained by measuring the transmitted scattered light intensity L ₂ of the laser beam transmitted from the normal A2 direction on the light-diffusion layer 102 side to 40 ° inclined direction A3 is within the range of 0.0002% or more and 0.001% or less. do. The direction A3 inclined at 40 degrees from the normal A2 direction on the light diffusing layer 102 side, which is the measurement direction of the transmitted scattered light intensity, is one direction in a plane including the normal (normal lines A1 and A2) directions of the light diffusing film.

When the relative scattered light intensity L ₂ / L ₁ is less than 0.0002%, the light scattering property is insufficient and the viewing angle is narrowed. Moreover, when it exceeds 0.001%, since light scattering is too strong, when this light-diffusion film is applied to a liquid crystal display device, the light which leaks obliquely with respect to the front direction of a liquid crystal display device in black display, for example, The front contrast decreases due to scattering in the front direction by the light diffusion layer, and the display quality deteriorates. The relative scattered light intensity L ₂ / L ₁ is preferably 0.0003% or more and 0.0008% or less.

The measurement of relative scattered light intensity L ₂ / L ₁ is performed on a sample for measurement in which a light diffusing film is bonded to a glass substrate on the base film 101 side using an optically transparent adhesive. Thereby, the curvature of the film at the time of a measurement can be prevented, and measurement reproducibility can be improved.

The parallel light (wavelength 543.5 nm) of a He-Ne laser is made to enter from the glass substrate surface side of this sample for a measurement to the normal line direction of a light-diffusion film, and it transmits in the direction A3 by 40 degrees from the normal line direction on the light-diffusion layer 102 side. The intensity of the laser light is measured. The value of the intensity of the transmitted scattered light divided by the light intensity of the light source is the relative scattered light intensity L ₂ / L ₁ . For measuring the relative scattered light intensity, an optical power meter (for example, "3292 03 Optical Power Sensor" manufactured by Yokogawa Denki Co., Ltd. and "3292 Optical Power Meter" manufactured by the company) is used.

(2) transmission clarity

The light-diffusion film of this invention is 70% or more and 180% or less of sum total of the transmission clarity (henceforth simply "transmission clarity") obtained through the optical comb of 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. `` Sum of transmission clarity obtained by passing through optical combs of 0.125 mm, 0.5 mm, 1.0 mm and 2.0 mm '' means the ratio of the width of the dark part and the wrist is 1: 1 in accordance with JIS K 7105, and the width is 0.125 mm, It is the sum of transmission clarity (image clarity) measured using four types of optical combs of 0.5 mm, 1.0 mm and 2.0 mm. Therefore, the maximum value of "transmission sharpness" here is 400%.

Since light scattering is too strong when the transmission clarity of the light diffusing film is less than 70%, when the light diffusing film is applied to a liquid crystal display device, for example, in the white display, light in the front direction of the liquid crystal display device is applied to the light diffusion layer. The front contrast decreases due to excessive scattering, and the display quality deteriorates. Moreover, when transmission clarity exceeds 180%, the moire of transmitted light by the interference of the regular matrix structure which the surface asperity structure of the prism film on the backlight side of a liquid crystal display device, and the color filter of a liquid crystal cell generate | occur | produce occurs. The transmission clarity of the light diffusion film is preferably 70% or more and 150% or less, and more preferably 90% or more and 140% or less.

The measurement of transmission sharpness is performed about the measurement sample which bonded the light-diffusion film to the glass substrate at the base film 101 side using the optically transparent adhesive similarly to the measurement of a relative scattered light intensity. Thereby, the curvature of the film at the time of a measurement can be prevented, and measurement reproducibility can be improved. As a measuring apparatus, the filamentous measuring instrument (for example, "ICM-1DP by the Sugashi Kenki Co., Ltd.") based on JISK7105 can be used.

(3) Hayes

In the light-diffusion film of the present invention, the total haze is 40% or more and 70% or less, and the internal haze is 40% or more and 70% or less. Moreover, the surface haze resulting from the surface shape of the light-diffusion layer 102 becomes less than 2%. Here, "whole haze" is based on the ratio of the total light transmittance (Tt) which shows the total amount of light transmitted by irradiating light to the light diffusing film, and the diffuse light transmittance (Td) diffused and transmitted by the light diffusing film. Equation (1):

Total haze (%) = (Td / Tt) × 100 (1)

.

The total light transmittance Tt is the sum of the parallel light transmittance Tp and the diffuse light transmittance Td transmitted while being coaxial with the incident light. Total light transmittance Tt and diffused light transmittance Td are the values measured based on JISK7361.

In addition, "internal haze" of a light-diffusion film is haze other than haze (surface haze) resulting from the surface shape of the light-diffusion layer 102 among all the haze.

If the total haze and / or the internal haze is less than 40%, light scattering properties are insufficient, resulting in a narrow viewing angle. In addition, when the total haze and / or the internal haze exceeds 70%, light scattering is too strong, so when this light-diffusion film is applied to the liquid crystal display device, for example, in the black display, the front direction of the liquid crystal display device is used. The front contrast decreases due to the fact that the light leaking out obliquely is scattered in the front direction by the light diffusion layer, and the display quality deteriorates. Moreover, when the total haze and / or the internal haze exceeds 70%, the transparency of the light diffusion film tends to be impaired. The total haze and the internal haze are preferably 50% or more and 65% or less, respectively.

Moreover, when the surface haze resulting from the surface shape of the light-diffusion layer 102 exceeds 2%, whitening generate | occur | produces by surface diffuse reflection. In order to prevent whitening more effectively, it is preferable that surface haze is 1% or less.

The total haze, internal haze, and surface haze of the light diffusing film are specifically measured as follows. That is, first, in order to prevent the film from bending, the base film 101 side is bonded to the glass substrate so that the light diffusing film is the surface of the light diffusing film using an optically transparent adhesive to prepare a sample for measurement. The total haze value is measured for the measurement sample. The total haze value is a total light transmittance (Tt) and a diffusion using a haze transmittance meter (for example, haze meter "HM-150" manufactured by Murakamishiki Saigi Jutsu Kenkyujo Co., Ltd.) in accordance with JIS K 7136. Light transmittance Td is measured and it is computed by said formula (1).

Subsequently, a triacetyl cellulose film having a haze of almost 0% is bonded to the surface of the light diffusion layer 102 using glycerin, and the haze is measured in the same manner as the above-described measurement of all haze. Since the said haze almost disappeared by the triacetyl cellulose film which the surface haze resulting from the surface shape of the light-diffusion layer 102 bonded together, it can be considered as "internal haze" of a light-diffusion film. Therefore, "surface haze" of a light-diffusion film is following formula (2):

Surface haze (%) = total haze (%)-internal haze (%) (2)

.

[Surface Shape of Light Diffusion Film]

In the light diffusing film of the present invention, the centerline average roughness Ra according to JIS B 0601 of the surface of the light diffusing layer 102 (the surface opposite to the base film 101) is 0.2 m or less, preferably 0.1 m or less. When the centerline average roughness Ra of the surface of the light diffusion layer 102 exceeds 0.2 µm, whitening becomes remarkable. The center line average roughness Ra according to JIS B 0601 is taken out from the roughness curve only the reference length l (L) in the direction of the average line, the x axis is taken in the direction of the average line of the pulled out portion, and the y axis is taken in the direction of the vertical magnification. When is expressed as Y = f (x), the following equation (3):

It means what expressed the value calculated by micrometer (micrometer) unit. The centerline average roughness Ra is a program that can calculate Ra based on the above formula (3) using a confocal interference microscope (for example, "PLμ2300" manufactured by Optical Solutions, Inc.) in accordance with JIS B 0601. It can calculate by software.

Next, the structure of the light-diffusion film of this invention which has the above optical characteristics and surface shape is demonstrated more concretely.

[Base film]

As the base film 101 used by this invention, what is necessary is just what is translucent, for example, glass, a plastic film, etc. can be used. What is necessary is just to have appropriate transparency and mechanical strength as a plastic film. Specifically, for example, cellulose acetate-based resins such as TAC (triacetyl cellulose), acrylic resins, polycarbonate resins, polyester-based resins such as polyethylene terephthalate, polyolefin-based resins such as polyethylene and polypropylene, and the like can be given. Can be. The layer thickness of the base film 101 is 10-500 micrometers, for example, Preferably it is 20-300 micrometers.

[Light diffusion layer]

The light-diffusion film of this invention contains the light-diffusion layer 102 laminated | stacked on the base film 101. As shown in FIG. The light diffusing layer 102 is a layer based on the light transmitting resin 103, and the light transmitting fine particles 104 are dispersed in the light transmitting resin 103. As described above, the centerline average roughness Ra according to JIS B 0601 of the surface of the light diffusion layer 102 (the surface opposite to the base film 101) is 0.2 µm or less, preferably 0.1 µm or less. Moreover, you may have another layer (including an adhesive layer) between the base film 101 and the light-diffusion layer 102. FIG.

The light-transmissive resin 103 is not particularly limited as long as it has a light-transmitting property, and for example, a cured product of an ionizing radiation curable resin or a thermosetting resin such as an ultraviolet curable resin or an electron beam curable resin, a cured product of a thermoplastic resin, or a metal alkoxide. Etc. can be used. Especially, ionizing radiation curable resin is preferable at the point which has high hardness and can provide high scratch resistance as a light-diffusion film provided in the liquid crystal display device surface. When using ionizing radiation curable resin, thermosetting resin, or a metal alkoxide, the translucent resin 103 is formed by hardening the said resin by irradiation or heating of ionizing radiation.

As an ionizing radiation curable resin, Polyfunctional acrylate like acrylic acid or methacrylic acid ester of polyhydric alcohol; The polyfunctional urethane acrylate synthesize | combined with the diisocyanate, the polyhydric alcohol, and the hydroxy ester of acrylic acid or methacrylic acid, etc. are mentioned. In addition to these, polyether resins having a acrylate-based functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiolpolyene resins, and the like can also be used.

As a thermosetting resin, in addition to the thermosetting urethane resin containing an acryl polyol and an isocyanate prepolymer, a phenol resin, urea melamine resin, an epoxy resin, an unsaturated polyester resin, and a silicone resin are mentioned.

As a thermoplastic resin, Cellulose derivatives, such as acetyl cellulose, nitrocellulose, acetylbutyl cellulose, ethyl cellulose, and methyl cellulose; Vinyl-based resins such as vinyl acetate and its copolymer, vinyl chloride and its copolymer, vinylidene chloride and its copolymer; Acetal resins such as polyvinyl formal and polyvinyl butyral; Acrylic resins such as acrylic resins and copolymers thereof, methacryl resins and copolymers thereof; Polystyrene resin; Polyamide-based resins; Polyester-based resins; Polycarbonate resin etc. are mentioned.

As a metal alkoxide, the silicon oxide matrix etc. which use the silicon alkoxide system material as a raw material can be used. Specifically, it is tetramethoxysilane, tetraethoxysilane, etc., and it can be set as an inorganic type or organic-inorganic composite matrix (translucent resin) by hydrolysis or dehydration condensation.

As the light-transmitting fine particles 104 used in the present invention, organic particles or inorganic fine particles having light transparency can be used. For example, organic fine particles containing acrylic resin, melamine resin, polyethylene, polystyrene, organic silicone resin, acrylic-styrene copolymer, and the like, calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, glass and the like The inorganic fine particle containing these etc. are mentioned. Moreover, the balloon and the glass hollow bead of an organic polymer can also be used. The translucent microparticles | fine-particles 104 may be comprised from one type of microparticles | fine-particles, and may contain two or more types of microparticles | fine-particles. The shape of the light-transmitting fine particles 104 may be any of a spherical shape, a flat shape, a plate shape, a needle shape, and an irregular shape, but a spherical shape or a substantially spherical shape is preferable.

Here, it is preferable that they are 0.5 micrometer or more and 15 micrometers or less, and, as for the weight average particle diameter of the translucent microparticles | fine-particles, it is more preferable that they are 4 micrometers or more and 8 micrometers or less. If the weight average particle diameter of the light-transmitting fine particles 104 is less than 0.5 µm, the visible light having a wavelength range of 380 nm to 800 nm cannot be scattered sufficiently, and the light diffusivity of the light diffusing film is insufficient, so that the relative scattered light intensity L ₂ / L ₁ does not become 0.0002% or more, and as a result, a wide viewing angle may not be obtained. In addition, when the weight average particle diameter exceeds 15 µm, when light transmittance is adjusted to 70% or more and 180% or less, sufficient light scattering properties cannot be obtained because light scattering becomes too weak. Similarly, relative scattered light intensity L ₂ / L ₁ is 0.0002. It may not be more than%.

It is preferable that the ratio (standard deviation / weight average particle diameter) of the standard deviation of the particle diameter and the weight average particle diameter of the translucent microparticle 104 is 0.5 or less, and it is more preferable that it is 0.4 or less. When the ratio exceeds 0.5, the particles having extremely large particle diameters are included as the light-transmitting fine particles, and protruding defects are generated on the surface of the light diffusing layer, so that the surface haze and / or the center line average roughness Ra of the light diffusing film is There may be a deviation from a predetermined range. In addition, the weight average particle diameter and the standard deviation of the particle diameter of the translucent microparticles | fine-particles 104 are measured using the Coulter multisizer (manufactured by Beckman Coulter) using the Coulter principle (pore electrical resistance method).

The content of the light transmitting fine particles 104 in the light diffusion layer 102 is preferably 25 parts by weight or more and 60 parts by weight or less, more preferably 30 parts by weight or more and 50 parts by weight or less based on 100 parts by weight of the light-transmissive resin 103. Do. When the content of the light-transmitting fine particles 104 is less than 25 parts by weight with respect to 100 parts by weight of the light-transmitting resin, the light diffusivity of the light-diffusion film becomes insufficient, so that the relative scattered light intensity L ₂ / L ₁ does not become 0.0002% or more. A viewing angle may not be obtained, and as a result, a moiré may generate | occur | produce as a result of transmission clarity exceeding 180%. When the content of the light-transmitting fine particles 104 exceeds 60 parts by weight with respect to 100 parts by weight of the translucent resin, the relative scattered light intensity L ₂ / L ₁ exceeds 0.001%, or the total haze and / or internal haze exceeds 70%. The fall of the front contrast and the fall of the transparency of a light-diffusion film may arise.

It is preferable to make the refractive index of the translucent microparticle 104 larger than the refractive index of the translucent resin 103, and the difference is preferably in the range of 0.04 to 0.15. By setting the difference in refractive index between the light-transmitting fine particles 104 and the light-transmitting resin 103 within the above ranges, proper internal scattering occurs due to the difference in refractive index between the light-transmitting fine particles 104 and the light-transmitting resin 103, and the overall haze and the inside of the light diffusing film It becomes easy to control haze within the said predetermined range, it becomes easy to suppress transmission clarity suitably, and to control within the said predetermined range.

Moreover, it is preferable that the surface (surface on the opposite side to the base film 101) of the light-diffusion layer is formed only from the translucent resin 103. That is, it is preferable that the light-transmitting fine particles 104 do not protrude from the surface of the light diffusion layer 102 and are completely embedded in the light diffusion layer 102. For this reason, it is preferable that the layer thickness of the light-diffusion layer 102 is 1 times or more and 3 times or less with respect to the weight average particle diameter of the translucent fine particle 104. When the layer thickness of the light-diffusion layer 102 is less than 1 times the weight average particle diameter of the light-transmitting fine particles 104, it is difficult to control the surface haze of the light-diffusion film within the above range, and whitening may occur accordingly. Moreover, when the layer thickness of the light-diffusion layer 102 exceeds three times the weight average particle diameter of the translucent microparticles | fine-particles, the film thickness of the light-diffusion layer 102 will become too thick, and the light-diffusion property of a light-diffusion film will be accordingly made. because too strong, relative scattered light intensity L ₂ / L ₁ is exceeds 0.001%, and as a result, there is a case where the front contrast deterioration.

As for the layer thickness of the light-diffusion layer 102, the range of 1-30 micrometers is preferable. When the layer thickness of the light-diffusion layer 102 is less than 1 micrometer, sufficient scratch resistance required for the light-diffusion film arrange | positioned at the visual side of a liquid crystal display device may not be provided. Moreover, when layer thickness exceeds 30 micrometers, the quantity of curl which generate | occur | produces in the produced light-diffusion film will become large, and the handleability in bonding to another film, a board | substrate, etc. will worsen.

In addition, the light-diffusion film of this invention may have the resin layer 105 containing translucent resin laminated | stacked on the light-diffusion layer 102 like the light-diffusion film 300 shown in FIG. In this case, the center line average roughness Ra of the surface of the resin layer 105 becomes 0.2 micrometer or less.

Moreover, the light-diffusion film of this invention may further contain the antireflection layer laminated | stacked on the light-diffusion layer 102 (surface on the opposite side to the base film 101). The antireflection layer may be directly formed on the diffusion film, or separately prepared an antireflection film having an antireflection layer formed on the transparent film, and may be laminated on the diffusion film using an adhesive or an adhesive. The antireflective layer is formed to keep the reflectance infinitely low, and the reflection glare on the display screen can be prevented by the formation of the antireflective layer. Examples of the antireflection layer include a low refractive index layer made of a material lower than the refractive index of the light diffusing layer 102; The laminated structure of the high refractive index layer which consists of a material higher than the refractive index of the light-diffusion layer 102, and the low refractive index layer which consists of a material lower than the refractive index of this high refractive index layer, etc. are mentioned. When laminating | stacking an antireflection film to a diffusion film using an adhesive or an adhesive agent, a commercially available antireflection film can be used.

Moreover, as for the light-diffusion film of this invention, the surface unevenness | corrugation laminated | stacked on the light-diffusion layer 102 (surface on the opposite side to the base film 101) as long as the centerline average roughness Ra of the surface of the light-diffusion layer 102 is 0.2 micrometer or less. You may further include the layer which has. The layer having the surface irregularities may be directly formed on the diffusion film, or separately prepared a film having the surface irregularities in which the layer having the surface irregularities is formed on the transparent film, and laminated on the diffusion film using an adhesive or an adhesive. good.

As a layer which has surface unevenness, an anti-glare layer is mentioned, for example. An anti-glare layer is provided in order to reduce the reflection glare to a display screen using the diffuse reflection on the surface. Although a well-known method is used when providing an anti-glare layer on the light-diffusion layer 102, it is obtained, for example on the light-diffusion layer 102 by coating and hardening | curing the ultraviolet curable resin composition containing translucent microparticles on a thin film. Can be. When laminating | stacking an anti-glare film to a diffusion film using an adhesive or an adhesive agent, a commercially available anti-glare film may be used and what formed the anti-glare layer on the transparent film based on the said method may be produced and used.

[Manufacturing Method of Light Diffusion Film]

Next, the method for manufacturing the light-diffusion film of this invention is demonstrated. The light-diffusion film of this invention is preferably manufactured by the method containing following process (A) and (B).

(A) Process of apply | coating resin liquid in which translucent microparticles | fine-particles 104 were disperse | distributed on the base film 101, and

(B) The process of transferring the mirror surface or uneven surface of a metal mold | die to the surface of the layer containing the said resin liquid.

The resin liquid used in the said process (A) is the translucent resin 103 which comprises the translucent microparticles 104 and the light-diffusion layer 102, or resin which forms this (for example, ionizing radiation hardening type resin, thermosetting resin, or metal). Alkoxide) and other components, such as a solvent, as needed. When ultraviolet curable resin is used as resin which forms translucent resin 103, the said resin liquid contains a photoinitiator (radical polymerization initiator). As a photoinitiator, an acetophenone type photoinitiator, a benzoin type photoinitiator, a benzophenone type photoinitiator, a thioxanthone type photoinitiator, a triazine type photoinitiator, an oxadiazole type photoinitiator, etc. are used, for example. Moreover, as a photoinitiator, For example, 2,4,6-trimethylbenzoyldiphenyl phosphine oxide, 2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'- tetraphenyl- 1,2'-biimidazole, 10-butyl-2-chloroacridone, 2-ethylanthraquinone, benzyl, 9,10-phenanthrenequinone, camphorquinone, methyl phenylglyoxylate, titanocene compound and the like are also available. Can be. The usage-amount of a photoinitiator is 0.5-20 weight part with respect to 100 weight part of resin normally contained in resin liquid, Preferably it is 1-5 weight part. In addition, in order to make the optical characteristic and surface shape of a light-diffusion film homogeneous, it is preferable that the dispersion | distribution of the translucent microparticles 104 in a resin solution is isotropic dispersion.

Application of the resin solution onto the base film can be performed by, for example, a gravure coating method, a microgravure coating method, a rod coating method, a knife coating method, an air knife coating method, a kiss coating method, a die coating method, or the like. . In application | coating of resin liquid, it is preferable to adjust coating film thickness so that the film thickness of the light-diffusion layer 102 may become 1 times or more and 3 times or less with respect to the weight average particle diameter of the translucent microparticles | fine-particles 104 as mentioned above.

For the purpose of improving the coating property of the resin liquid or the adhesiveness with the light diffusing layer 102, various surface treatments may be performed on the surface (light diffusing layer side surface) of the base film 101. Examples of the surface treatment include corona discharge treatment, glow discharge treatment, acid surface treatment, alkali surface treatment, ultraviolet irradiation treatment, and the like. Moreover, you may make it form another layer, such as a primer layer, on a base film, and apply | coat a resin liquid on another layer.

Moreover, when using the light-diffusion film of this invention as a protective film of the polarizing film mentioned later, in order to improve the adhesiveness of the base film 101 and a polarizing film, the surface of a base film 101 (with a light-diffusion layer) Surface on the opposite side) is preferably hydrophilized by various surface treatments.

In the said process (B), the mirror surface or uneven surface of a metal mold | die is transferred to the surface of the layer containing the said resin liquid. Specifically, in order to obtain the light-diffusion layer which has a flat surface as shown in FIG. 1, the said mirror surface of the metal mold | die (mirror mold) which has a mirror surface adheres to the surface of the layer containing the said resin liquid, and a mirror surface is transferred. Moreover, in order to obtain the light-diffusion layer which has the uneven | corrugated surface shape as shown in FIG. 2, the said uneven surface of the metal mold | die (mold for embossing) which has an uneven surface adheres to the surface of the layer containing the said resin liquid, and the uneven surface Warriors The mirror metal mold | die may be a mirror metal roll, and the metal mold | die for embossing may be a metal roll for embossing. In this manner, by transferring the mirror surface or the concave-convex surface of the mold onto the surface of the light diffusion layer 102, it is possible to reliably prevent the light-transmitting fine particles from protruding onto the surface of the light diffusion layer, thereby forming a light diffusion layer having a desired surface shape. .

When ionizing radiation curable resin, thermosetting resin, or a metal alkoxide is used as resin which forms translucent resin 103, the layer containing the said resin liquid is formed, if necessary, it is made to dry (removal of a solvent), and The mirror surface or the uneven surface of the mold is brought into close contact with the surface of the layer containing the resin liquid, or after being brought into close contact with each other, irradiation of ionizing radiation (when using an ionizing radiation curable resin) or heating (thermosetting resin or metal alkoxide) When used), the layer containing the resin liquid is cured. Although ionizing radiation can be suitably selected from ultraviolet-ray, electron beam, near-ultraviolet, visible light, near-infrared, infrared rays, X-rays, etc. according to the kind of resin contained in resin liquid, ultraviolet-ray and an electron beam are preferable among these, and especially handling is easy. Ultraviolet light is preferable in that high energy can be obtained.

As the ultraviolet light source, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. Moreover, ArF excimer laser, KrF excimer laser, an excimer lamp, a synchrotron radiation, etc. can also be used. Among these, an ultra high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a xenon arc, and a metal halide lamp are used preferably.

Moreover, as an electron beam, 50-1000 keV emitted from various electron beam accelerators, such as a cocroft Walton type | mold, a half-degraph type | mold, a resonance transformation type | mold, an insulation core transformer type | mold, a linear type | shaft, a dynamtron type | mold type, and a high frequency type | mold, preferably 100 Electron beams with an energy of? 300 keV.

Next, preferable embodiment for manufacturing the light-diffusion film of this invention is described. In the manufacturing method according to the above preferred embodiment, in order to continuously manufacture the light-diffusion film of the present invention, a step of continuously sending the base film 101 wound in a roll shape, and coating a resin liquid in which the light-transmitting fine particles 104 are dispersed. And the process of drying as needed, the process of hardening the layer containing resin liquid, and the process of winding up the obtained light-diffusion film are included. Such a manufacturing method can be performed using the manufacturing apparatus shown in FIG. 5, for example. Hereinafter, the manufacturing method which concerns on said preferable embodiment is demonstrated, referring FIG.

First, the base film 101 is continuously unwinded by the unwinding device 501. Next, the resin liquid in which the translucent microparticles | fine-particles 104 were disperse | distributed is coated on the unwinding base film 101 using the coating apparatus 502 and the backup roll 503 which opposes this. Next, when a solvent is contained in the resin liquid, it is dried by passing the dryer 504. Next, the base film 101 in which the layer containing the resin liquid was formed is between a mirror metal roll or the embossing metal roll 505, and the nip roll 506, and the layer containing this resin liquid is a mirror metal roll Or it is wound so that it may be in close contact with the metal roll 505 for embossing. As a result, the mirror surface of the mirror metal roll or the uneven surface of the metal roll for embossing is transferred to the surface of the layer containing the resin liquid. Next, the layer containing a resin liquid by irradiating an ultraviolet-ray from the ultraviolet irradiation device 508 through the base film 101 in the state wound around the mirror metal roll or the embossing metal roll 505. Harden. Since the irradiation surface becomes high temperature by ultraviolet irradiation, it is preferable that the mirror surface metal roll or the embossing metal roll 505 includes the cooling apparatus for adjusting the surface temperature in room temperature to about 80 degreeC inside. . In addition, the ultraviolet irradiation device 508 can use one device or a plurality of devices. The base film 101 (light-diffusion film) in which the light-diffusion layer 102 was formed is peeled from the mirror metal roll or the embossing metal roll 505 by the peeling roll 507. FIG. The light-diffusion film produced as mentioned above is wound up by the winding-up apparatus 509. FIG. At this time, in order to protect the light-diffusion layer 102, you may wind up while sticking the protective film containing polyethylene terephthalate, polyethylene, etc. on the surface of the light-diffusion layer 102 via the adhesive layer which has re-peelability.

In addition, after peeling from the mirror metal roll or the embossing metal roll 505 by the peeling roll 507, you may perform further ultraviolet irradiation. Moreover, instead of performing ultraviolet irradiation in the state wound around the mirror metal roll or the embossing metal roll 505, the base film 101 in which the layer containing the uncured resin liquid was formed was mirror-finished metal roll or metal roll for embossing. After peeling from 505, you may irradiate and harden an ultraviolet-ray.

In manufacturing the light-diffusion film of this invention, in order to make various physical properties in a light-diffusion film into the range prescribed | regulated by this invention, it can carry out using the following method, for example.

First, various physical properties (L ₂ / L ₁ , transmission clarity) of the light diffusion film obtained by arbitrarily selecting the base film, the light-transmitting fine particles, the light-transmitting resin, or the resin forming the light-transmitting resin, and producing a light-diffusion film by the above method. , Total haze, internal haze, centerline average roughness Ra, surface haze, and the like) are measured. And when compared with the value or range of a value which aims at the value, when it deviates, the refractive index difference of a translucent microparticle and a translucent resin, content of a translucent microparticle, the thickness of a light-diffusion layer, the weight of a translucent microparticle, for example Any of the average particle diameter, the surface roughness of the light diffusing layer, or two or more conditions thereof are adjusted according to the following criteria (1) to (5) to produce a light diffusing film, and the various physical properties thereof are measured. This operation can be made into the target light-diffusion film by repeating until the obtained light-diffusion film shows various target physical properties.

(1) The larger the refractive index between the translucent particles and the translucent resin, L is the value of the direction of enlarging the ₂ / L _1, the value of the total haze is the increase direction. On the contrary, when the refractive index difference between the light-transmitting fine particles and the light-transmissive resin is made small, the value of L ₂ / L ₁ becomes a direction of decreasing, and the value of the total haze becomes a direction of decreasing. In addition, adjustment of the refractive index difference of translucent microparticles | fine-particles and translucent resin can be performed by changing the kind of translucent microparticles | fine-particles and / or translucent resin to be used.

(2) Increasing the content of the light-transmitting fine particles, the value of L ₂ / L ₁ becomes a direction to increase, the value of the transmission sharpness becomes a direction to decrease, the value of the total haze becomes a direction to increase, the value of the center line average roughness Ra Becomes the direction of increase. On the contrary, when the content of the light-transmitting fine particles is reduced, the value of L ₂ / L ₁ becomes a direction that decreases, the value of transmission sharpness becomes a direction that increases, and the value of the overall haze becomes a direction that decreases, and the value of the centerline average roughness Ra is It becomes smaller direction.

(3) When the thickness of the light diffusing layer is increased, the value of L ₂ / L ₁ becomes the direction of increasing, the value of transmission sharpness becomes the direction of decreasing, and the value of the total haze becomes the direction of increasing, and the value of the internal haze is It becomes a direction which becomes large, and the value of centerline average roughness Ra becomes a direction which becomes small. On the contrary, when the thickness of the light diffusion layer is reduced, the value of L ₂ / L ₁ is in the direction of decreasing, the value of transmission sharpness is in the direction of increasing, and the value of the total haze is in the direction of decreasing, and the value of the internal haze is It becomes a direction which becomes small, and the value of centerline average roughness Ra becomes a direction which becomes large.

(4) When the weight average particle diameter of the translucent microparticles | fine-particles is enlarged, the value of internal haze will become a direction which becomes small, and the value of center line average roughness Ra will become a direction which becomes large. On the contrary, when the weight average particle diameter of the translucent microparticles | fine-particles is made small, the value of internal haze will become a large direction, and the value of center line average roughness Ra will become a small direction.

(5) The smaller the difference between the total haze value and the internal haze value is, the smaller the surface haze value is, on the contrary, the greater the difference between the total haze value and the internal haze value is, the larger the surface haze value is.

<Light diffusing polarizer>

The light-diffusion film of this invention mentioned above can be made into a light-diffusion polarizing plate by combining with a polarizing plate. The light diffusing polarizing plate is a multifunctional film having a polarizing function and an antiglare (light diffusing) function. The light-diffusion polarizing plate of this invention contains the polarizing plate which has a polarizing film at least, and the light-diffusion film of this invention laminated | stacked on the said polarizing plate via an adhesive layer or an adhesive bond layer so that a base film side may face the said polarizing plate. will be. A conventionally well-known structure may be sufficient as a polarizing plate, For example, it is common to have a protective film in one side or both sides of a polarizing film. Moreover, the polarizing film itself may be sufficient as a polarizing plate. 6 is a schematic cross-sectional view showing a preferred example of the light diffusing polarizing plate of the present invention. The light diffusing polarizing plate 600 shown in FIG. 6 includes a polarizing film 601, a protective film 602 adhered to one side of the polarizing film 601, and a light diffusing film 100 adhered to the other side. It includes. The light-diffusion film 100 is stuck so that the base film 101 side may face the polarizing film 601 of a polarizing plate. The light diffusion film 100 and the protective film 602 are adhered to the polarizing film 601 through an adhesive layer not shown. Such a structure in which the polarizing film and the light diffusing film are adhered through the adhesive layer, that is, the structure using the light diffusing film as a protective film of the polarizing film is advantageous for thinning the light diffusing polarizing plate.

As the polarizing film 601, for example, a dichroic dye or a polyvinyl alcohol-based resin, a polyvinyl acetate resin, an ethylene / vinyl acetate (EVA) resin, a polyamide resin, a polyester-based resin, or the like. Polyvinyl alcohol / polyvinylene copolymers containing oriented molecular chains of dichroic dehydration products of polyvinyl alcohol (polyvinylene) in adsorption-orientated iodine and molecularly oriented polyvinyl alcohol films. have. In particular, a polyvinyl alcohol-based resin film having a dichroic dye or iodine adsorptively oriented is preferably used as a polarizing film. Although the thickness of a polarizing film is not specifically limited, Generally, from a viewpoint of thickness reduction of a polarizing plate, etc., 100 micrometers or less are preferable, More preferably, it is the range of 10-50 micrometers, More preferably, it is the range of 25-35 micrometers. .

As the protective film 602 of the polarizing film 601, a film containing a polymer having low birefringence and excellent in transparency, mechanical strength, thermal stability, moisture shielding, and the like is preferable. As such a film, For example, Cellulose acetate type resins, such as TAC (triacetyl cellulose); Acrylic resins; Fluorine resins such as tetrafluoroethylene / hexafluoropropylene copolymers; Polycarbonate resins; Polyester-based resins such as polyethylene terephthalate; Polyimide resin; Polysulfone resins; Polyether sulfone resin; Polystyrene resin; Polyvinyl alcohol-based resins; Polyvinyl chloride resins; The thing which molded-processed resin, such as polyolefin resin or polyamide resin, into a film form is mentioned. Among them, a triacetyl cellulose film obtained by saponifying a surface with an alkali or the like or a norbornene-based thermoplastic resin film can be preferably used in terms of polarization characteristics, durability, and the like. Since norbornene-type thermoplastic resin films are highly moist and heat resistant, the durability of the polarizing plate can be greatly improved, and because of the low hygroscopicity, high dimensional stability is particularly preferable. Although the thickness of the protective film which can use the conventionally well-known method of the casting method, the calendering method, and the extrusion method for the shaping | molding process with respect to a film is 500 micrometers or less from a viewpoint of thinning of a polarizing plate, etc., More preferably, Is in the range of 5 to 300 µm, more preferably in the range of 5 to 150 µm.

The light-diffusion polarizing plate of the above structure is typically adhered to the glass substrate of a liquid crystal panel via an adhesive layer etc. so that a light-diffusion film may become a light emission side (viewing side) when it attaches to a liquid crystal display device. It is inserted into the liquid crystal display device.

In addition, the light diffusing polarizing plate may further include an antireflection layer laminated on the light diffusing layer. As a light-diffusion polarizing plate containing an anti-reflection layer, For example, the light-diffusion polarizing plate which laminated | stacked the anti-reflective layer 106 directly on the surface of the light-diffusion layer 102 which consists of a flat surface (refer FIG. 11); The light-diffusion polarizing plate which laminated | stacked the anti-reflective film which consists of a laminated body of the transparent film 107 and the anti-reflective layer 106 on the surface of the light-diffusion layer 102 which consists of flat surfaces via the adhesive bond layer or the adhesive layer 108. (See Figure 12); A light diffusing polarizing plate in which the antireflection layer 106 is laminated directly on the surface of the light diffusing layer 102 having irregularities (see FIG. 13); A light diffusing polarizing plate in which an antireflection film made of a laminate of the transparent film 107 and the antireflection layer 106 is laminated on the surface of the light diffusing layer 102 having irregularities via an adhesive layer or an adhesive layer 108 ( See FIG. 14); A light diffusing polarizing plate (see FIG. 15) in which an antireflection layer 106 is laminated directly on the surface of the resin layer 105 containing the translucent resin laminated on the surface of the light diffusing layer 102 having irregularities; On the surface of the resin layer 105 containing the translucent resin laminated | stacked on the surface of the light-diffusion layer 102 which has an unevenness | corrugation, the anti-reflective film which consists of a laminated body of the transparent film 107 and the anti-reflective layer 106 is an adhesive bond layer, or The light-diffusion polarizing plate (refer FIG. 16) etc. which were laminated | stacked through the adhesive layer 108 are mentioned.

The light diffusing polarizing plate may further include a layer having surface irregularities such as an antiglare layer laminated on the light diffusing layer. As a light diffusing polarizing plate including a layer having surface irregularities, for example, a light diffusing polarizing plate in which a layer 801 having surface irregularities is laminated directly on the surface of the light diffusing layer 102 formed of a flat surface (FIG. 17); The light diffusivity which laminated | stacked the film which consists of a laminated body of the transparent film 107 and the layer 801 which has surface unevenness | corrugation on the surface of the light-diffusion layer 102 which consists of a flat surface via the adhesive bond layer or the adhesive layer 108 Polarizer (see FIG. 18); A light diffusing polarizing plate in which a layer 801 having surface irregularities is laminated directly on the surface of the light diffusing layer 102 having irregularities (see FIG. 19); The light-diffusion polarizing plate which laminated | stacked the film which consists of a laminated body of the transparent film 107 and the layer 801 which has surface unevenness | corrugation on the surface of the light-diffusion layer 102 which has an unevenness via the adhesive bond layer or the adhesive layer 108. (See FIG. 20); A light-diffusing polarizing plate in which a layer 801 having surface irregularities is laminated directly on the surface of the resin layer 105 containing the translucent resin laminated on the surface of the light diffusing layer 102 having irregularities (see FIG. 21); An adhesive layer is a film made of a laminated body of a transparent film 107 and a layer 801 having surface irregularities on the surface of the resin layer 105 containing a translucent resin laminated on the surface of the light diffusion layer 102 having irregularities. Or the light-diffusion polarizing plate (refer FIG. 22) etc. which were laminated | stacked through the adhesive layer 108 is mentioned.

<Liquid Crystal Display Device>

Next, a liquid crystal display device according to the present invention will be described. The liquid crystal display device of the present invention includes a backlight device, a light deflecting means, a backlight side polarizing plate, a liquid crystal cell, and the light diffusing polarizing plate of the present invention in this order. 7 is a schematic cross-sectional view showing a preferred example of the liquid crystal display device of the present invention. The liquid crystal display device of FIG. 7 is a TN type liquid crystal display device of a normal white mode, and includes a backlight device 702, a light diffusion plate 703, two prism films 704a and 704b as light deflection means, and a backlight side polarizing plate. 705, a liquid crystal cell 701 in which a liquid crystal layer 712 is formed between a pair of transparent substrates 711a and 711b, and a viewing side polarizer 706 and a light diffusion film 707 according to the present invention. The light diffusing polarizing plate is arranged in this order.

As shown in FIG. 8, the backlight side polarizing plate 705 and the viewing side polarizing plate 706 are arrange | positioned so that these transmission axes may become orthogonal Nicole relationship. In addition, the two prism films 704a and 704b each have a flat surface on the light incident side (backlight device side) and a surface on the light exit side (viewing side) (surface facing the backlight side polarizing plate 705). A plurality of linear prisms 741a and 741b are formed in parallel. And the prism film 704a is arrange | positioned so that the direction of the ridgeline 742a of the linear prism 741a may become substantially parallel to the transmission axis direction of the backlight side polarizing plate 705, and the prism film 704b is the The direction of the ridge line 742b of the linear prism 741b is arranged to be substantially parallel to the transmission axis direction of the viewing side polarizing plate 706 constituting the light diffusing polarizing plate. However, the direction of the ridge line 742b of the linear prism 741b of the prism film 704b is arranged to be substantially parallel to the transmission axis direction of the backlight side polarizing plate 705, and the linear prism 741a of the prism film 704a. It is also possible to arrange | position so that the direction of the ridge line 742a of () may be substantially parallel to the transmission axis direction of the viewing side polarizing plate 706 which comprises a light-diffusion polarizing plate. Hereinafter, the structural member which comprises the liquid crystal display device of this invention is demonstrated in detail.

[Liquid crystal cell]

The liquid crystal cell 701 is a liquid crystal layer 712 formed by sealing a liquid crystal between a pair of transparent substrates 711a and 711b facing each other at a predetermined distance by a spacer and the pair of transparent substrates 711a and 711b. It includes. A pair of transparent substrates 711a and 711b are formed by laminating transparent electrodes and an alignment film, respectively, and a liquid crystal is aligned by applying a voltage based on display data between the transparent electrodes. Although the display system of the liquid crystal cell 701 is a TN system in the said example, display systems, such as an IPS system and VA system, are also used.

[Backlight device]

The backlight device 702 includes a rectangular parallelepiped case 721 having an upper surface opened, and a cold cathode tube 722 as a linear light source arranged in parallel in a plurality of cases 721. The case 721 is formed of a resin material or a metal material, and from the viewpoint of reflecting light emitted from the cold cathode tube 722 from the case inner circumferential surface, the case inner circumferential surface is preferably white or silver. As a light source, LEDs of various shapes, such as linear shape, can be used besides a cold cathode tube. In the case of using a linear light source, the number of linear light sources to be disposed is not particularly limited, but it is preferable that the distance between the centers of adjacent linear light sources is in a range of 15 mm to 150 mm from the viewpoint of suppressing luminance unevenness of the light emitting surface. . Incidentally, the backlight device 702 used in the present invention is not limited to the type of the direct type shown in Fig. 7, but may be various types such as a side light type or a planar light source type in which a linear light source or a point light source is disposed on the side of the light guide plate. Can be used.

[Light diffusion means]

The liquid crystal display of the present invention may include a light diffusing plate 703 as light diffusing means disposed between the backlight device 702 and the light deflecting means. The light diffusion plate 703 is a film or sheet obtained by dispersing and dispersing a diffusion agent in a substrate. As the base material, polycarbonate resin, methacryl resin, copolymer resin of methyl methacrylate and styrene, copolymer resin of acrylonitrile and styrene, copolymer resin of methacrylic acid and styrene, polystyrene resin, polyvinyl chloride resin Polyolefin resins such as polypropylene and polymethylpentene, cyclic polyolefin resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resins, polyarylate resins, and polyimide resins. In addition, the light-diffusion means may use together a light-diffusion plate and a light-diffusion film.

Moreover, as a diffusing agent mixed-dispersed to a base material, organic fine particles containing acrylic resin, melamine resin, polyethylene resin, polystyrene resin, organic silicone resin, copolymer of acryl and styrene, etc. different from the material of a base material, and carbonic acid Inorganic fine particles containing calcium, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, glass, and the like. The kind of diffusing agent to be used may be one type or two or more types. Moreover, the balloon and glass hollow bead of an organic polymer can also be used as a diffusing agent. The weight average particle diameter of the diffusing agent is preferably in the range of 0.5 to 30 µm. The shape of the diffusing agent may be spherical, flat, plate, needle, or the like, but is preferably spherical.

[Prism film (light deflection means)]

The prism films 704a and 704b are polygons having a light incidence plane side (backlight device side) having a flat surface and having a pointed end surface on a surface on the light emission side (a surface opposite to the backlight side polarizing plate 705). The triangular linear prism 741a, 741b is formed in parallel. As a material of the prism films 704a and 704b, for example, polycarbonate resin, ABS resin, methacryl resin, copolymer resin of methyl methacrylate and styrene, polystyrene resin, copolymer resin of acrylonitrile and styrene And ionizing radiation curable resins such as polyolefin resins such as polyethylene and polypropylene or ultraviolet curable resins and electron beam curable resins. As a manufacturing method of a prism film, it can manufacture by well-known methods, such as a mold extrusion method, a press molding method, an injection molding method, a roll transfer method, a laser blading method, a mechanical cutting method, a mechanical grinding method, a photopolymer process method. These methods may be used independently, respectively, or may combine 2 or more types of methods. The thickness of the prism films 704a and 704b is 0.1-15 mm normally, Preferably it is 0.5-10 mm.

The cross-sectional shape in the vertical cross section orthogonal to the ridge lines 742a and 742b of the linear prisms 741a and 741b is, for example, in the case of a triangle, the vertex angle θ of the vertex forming the ridge line among the vertices of the triangle (see Fig. 8). Is preferably in the range of 90 to 110 degrees. In addition, although each side may be an equilateral side or an equilateral side, this triangle is preferably an isosceles triangle with two sides on the light exit side condensing in the front direction (normal direction of the display surface of the liquid crystal display device). . The cross-sectional shape of the linear prism may be set in accordance with the characteristics of the light emitted from the surface light source, or may be a shape other than a triangle such as giving a curve.

In the prism films 704a and 704b, for example, a plurality of linear prisms 741a and 741b having a triangular cross section are sequentially arranged such that the bottom edges facing the vertex angle of the triangle are adjacent to each other, and the plurality of linear prisms It is preferable to have a structure in which the ridge lines 742a and 742b of 741a and 741b are arranged to be substantially parallel to each other. In this case, as long as the condensing ability is not significantly reduced, the vertices of the cross-sectional shape of the linear prisms 741a and 741b may be curved at their vertices. The distance between each ridgeline is usually in the range of 10 to 500 µm, and preferably in the range of 30 to 200 µm.

[Polarizing plate]

The backlight side polarizing plate 705 constituting the light diffusing polarizing plate can use the above-mentioned one. In addition, a conventionally well-known thing can be used as the viewing side polarizing plate 706.

[Retardation film]

The liquid crystal display of the present invention may include a phase difference plate 708 as shown in FIG. 9. In FIG. 9, the retardation plate 708 is disposed between the backlight side polarizer 705 and the liquid crystal cell 701. This retardation plate 708 has a phase difference of almost zero in a direction perpendicular to the surface of the liquid crystal cell 701, and has no optical effect from the front. Compensation for the phase difference occurring at 701. As a result, a wider viewing angle can be obtained, and superior display quality and color reproducibility can be obtained. The phase difference plate 708 can be disposed between one or both of the backlight side polarizer 705 and the liquid crystal cell 701, and between the viewer side polarizer 706 and the liquid crystal cell 701.

As the retardation plate 708, for example, a polycarbonate resin or a cyclic olefin polymer resin is used as a film, the film is further biaxially stretched, a liquid crystalline monomer is applied to the film, and the molecules are subjected to a photopolymerization reaction. And immobilized arrays. Since the phase difference plate 708 optically compensates for the arrangement of the liquid crystal, one having a refractive index characteristic opposite to that of the liquid crystal arrangement is used. Specifically, for the liquid crystal cell of the TN mode, for example, "WV film" (manufactured by FUJIFILM Corporation), and for the liquid crystal display cell of the STN mode, for example, "LC film" (Shin Nihon Sekiyu Co., Ltd. product) ), A liquid crystal display cell in the IPS mode, for example, a biaxial retardation film, a liquid crystal display cell in the VA mode, for example, a retardation plate or a biaxial retardation film in which A plate and C plate are combined, liquid crystal of π cell mode As the display cell, for example, "WV film for OBC" (manufactured by Fujifilm Co., Ltd.) or the like can be preferably used.

In the liquid crystal display device having the above configuration, with reference to FIG. 7, the light emitted from the backlight device 702 is diffused by the light diffusion plate 703 and then enters the prism film 704a. In a vertical cross section orthogonal to the transmission axis direction of the backlight side polarizing plate 705, light incident obliquely to the lower surface of the prism film 704a is emitted with its path changed in the front direction. Next, in the prism film 704b, the light incident obliquely to the lower surface of the prism film 704b in the cross section orthogonal to the transmission axis direction of the viewing-side polarizing plate 706 passes in the front direction as described above. Is changed to exit. Therefore, the light which passed the two prism films 704a and 704b is condensed by the front direction in all the vertical cross sections, and the brightness of a front direction improves.

Subsequently, light imparted with directivity in the front direction is polarized by the backlight side polarizer 705 and enters the liquid crystal cell 701. Light incident on the liquid crystal cell 701 is emitted from the liquid crystal cell 701 by controlling the polarization plane for each pixel by the orientation of the liquid crystal layer 712 controlled by the electric field. And the light radiate | emitted from the liquid crystal cell 701 passes through the viewing side polarizing plate 706, and passes further through the light-diffusion film 707, and it exits to the display surface side.

In this way, when two prism films 704a and 704b are used as the light deflecting means, the directivity in the front direction of the light incident on the liquid crystal cell 701 can be further improved, whereby the luminance in the front direction is further improved. You can. Moreover, since the light-diffusion film of this invention is used, the outstanding light-diffusion and high transmission clarity can be obtained, without reducing the front contrast.

Example

Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples. In addition, the measuring method of the optical characteristic and surface shape of the light-diffusion film in the following examples, the layer thickness of a light-diffusion layer, and the weight average particle diameter of the translucent microparticles | fine-particles used were as follows.

(a) relative scattered light intensity

It measured using the sample for the measurement which bonded the light-diffusion film to the glass substrate at the base film side using the optically transparent adhesive. Intensity of the laser beam transmitted from the glass substrate surface side of the sample for measurement to a normal light direction (wavelength 543.5 nm) of a He-Ne laser in the normal direction of the light-diffusion film and transmitted in the direction A3 inclined at 40 ° from the normal direction on the light-diffusion layer side. L ₂ was measured and the relative scattered light intensity L ₂ / L ₁ was calculated as a value obtained by dividing the intensity L ₂ of the transmitted scattered light by the light intensity L ₁ of the light source. Yokogawa Denki Co., Ltd. "3292 03 optical power sensor" and the company's "3292 optical power meter" were used for the measurement.

At the time of this measurement, the light source which irradiates a He-Ne laser was arrange | positioned at the position of 430 mm from the said glass substrate. The said power meter which is a light receiver was arrange | positioned at the position of 280 mm from the emission point of a laser beam, and moved this power meter so that it might become the said predetermined angle, and measured the intensity of the emitted laser beam.

The intensity of the laser light irradiated to the light diffusing layer, that is, the intensity of the laser light irradiated from the light source is measured by measuring the intensity of light incident directly on the power meter from the light source without providing a glass substrate bonded to the light diffusing layer. Saved. In addition, the said intensity | strength was measured by arrange | positioning the said power meter in the position of 710 mm (= 430 mm + 280 mm) from the said light source.

(b) transmission clarity

It measured using the sample for the measurement which bonded the light-diffusion film to the glass substrate at the base film side using the optically transparent adhesive. A filamentous measuring instrument ("ICM-1DP" manufactured by Sugashi Kenki Co., Ltd.) in accordance with JIS K 7105 was used for the measurement.

(c) haze

It measured using the sample for the measurement which bonded the light-diffusion film to the glass substrate at the base film side using the optically transparent adhesive. The haze transmittance | permeability meter (haze meter "HM-150" by Murakamishikisaiki Jutsu Kenkyujo Co., Ltd.) based on JISK7136 was used for the measurement of all the haze value and internal haze. Based on the result, surface haze was computed in said Formula (2).

(d) Centerline mean roughness Ra

It measured using the confocal interference microscope (for example, "PLmicro 2300" by the optical solution company) according to JIS B 0601.

(e) Layer thickness of the light diffusing layer

The layer thickness of the light diffusion film was measured using NIKON DIGIMICRO MH-15 (main body) and ZC-101 (counter), and the layer thickness of the light diffusion layer was measured by subtracting the substrate thickness of 80 µm from the measurement layer thickness. .

(f) Weight average particle diameter of translucent microparticles

The measurement was carried out using a Coulter multisizer (manufactured by Beckman Coulter) using the Coulter principle (pore electrical resistance method).

&Lt; Example 1 >

(1) Production of mirror metal rolls

Industrial chrome plating was performed to the surface of the iron roll (STKM13A by JIS) of diameter 200mm, and the surface was then mirror-polished, and the mirror metal roll was produced. The Vickers hardness of the chromium plating surface of the obtained mirror metal roll was 1000. In addition, the Vickers hardness was measured based on JISZ2244 using the ultrasonic hardness meter MIC10 (made by Krautkramer) (the Vickers hardness measurement method is the same also in the following example).

(2) Preparation of light diffusing film

60 parts by weight of pentaerythritol triacrylate and 40 parts by weight of polyfunctional urethane acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate) were mixed with a propylene glycol monomethyl ether solution to obtain a solid content of 60% by weight. It adjusted and the ultraviolet curable resin composition was obtained. Moreover, the refractive index of the hardened | cured material after removing propylene glycol monomethyl ether from the said composition and UV-curing was 1.53.

Next, with respect to 100 weight part of solid content of the said ultraviolet curable resin composition, 30 weight part of polystyrene-type particle | grains whose weight average particle diameter is 12.0 micrometers, and a standard deviation are 4.17 micrometers as translucent microparticles | fine-particles, and "Lucirine TPO" which is a photoinitiator ( 5 weight part of 2,4,6-trimethylbenzoyldiphenylphosphine oxide) by BASF Corporation was added, and it diluted with propylene glycol monomethyl ether so that solid content might be 60 weight%, and the coating liquid was prepared.

This coating liquid was apply | coated on the triacetyl cellulose (TAC) film (base film) of thickness 80micrometer, and it dried for 1 minute in the dryer set to 80 degreeC. The base film after drying was pressed and adhered to the mirror surface of the mirror surface metal roll produced by said (1) with a rubber roll so that an ultraviolet curable resin composition layer might become a roll side. In this state, light from a high-pressure mercury lamp having an intensity of 20 mW / cm 2 is irradiated so as to be 300 mJ / cm 2 in the amount of h-line converted light, the ultraviolet curable resin composition layer is cured, and a light diffusion layer having a flat surface. The light-diffusion film of the structure shown in FIG. 1 containing a base film was obtained.

10 shows the relationship between the light scattering angle (an inclination angle with respect to the normal line of the light diffusing film in the emission direction of the transmitted and scattered laser light) and the relative scattered light intensity in the obtained light diffusing film.

<Example 2>

A light-diffusion film was produced in the same manner as in Example 1 except that 35 parts by weight of polystyrene particles having a weight average particle diameter of 6.0 μm and a standard deviation of 2.19 μm were used as the light-transmitting fine particles.

<Example 3>

(1) Fabrication of metal rolls for embossing

The thing which copper ballad plating was given to the surface of the iron roll (STKM13A by JIS) of diameter 200mm was prepared. Copper ballad plating consisted of a copper plating layer / thin silver plating layer / surface copper plating layer, and the thickness of the whole plating layer was about 200 micrometers. The copper plating surface was mirror-polished, and zirconia bead TZ-B125 (made by Tosoh Corporation, average particle diameter: 125 micrometers) was blurred to the polishing surface using a blast apparatus (manufactured by Fuji Seisakusho Co., Ltd.). The blast pressure was further blistered at 0.05 MPa (gauge pressure, the same as below) and the amount of fine particles used at 16 g / cm 2 (the amount used per 1 cm 2 of roll, hereinafter equal) to form irregularities on the surface. On the uneven surface, zirconia bead TZ-SX-17 (manufactured by Tosoh Corporation, average particle diameter: 20 µm) was used with a blast apparatus (manufactured by Fuji Seisakusho Co., Ltd.), and the blast pressure was 0.1 MPa and the amount of fine particles used. The surface irregularities were finely adjusted by blasting at 4 g / cm <2>. The obtained copper plated iron roll with irregularities was subjected to etching treatment with a cupric chloride liquid. The etching amount at that time was set to be 3 micrometers. Then, chrome plating process was performed and the metal roll for embossing was produced. At this time, it set so that chrome plating thickness might be set to 4 micrometers. The Vickers hardness of the chromium plating surface of the obtained metal roll for embossing was 1000.

(2) Preparation of light diffusing film

60 parts by weight of pentaerythritol triacrylate and 40 parts by weight of polyfunctional urethane acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate) were mixed with a propylene glycol monomethyl ether solution to obtain a solid content of 60% by weight. It adjusted and the ultraviolet curable resin composition was obtained. Moreover, the refractive index of the hardened | cured material after removing propylene glycol monomethyl ether from the said composition and UV-curing was 1.53.

Next, with respect to 100 parts by weight of the solid content of the ultraviolet curable resin composition, 35 parts by weight of polystyrene-based particles having a weight average particle diameter of 7.2 μm and a standard deviation of 0.52 μm as light-transmitting fine particles, and “Lucirine TPO” which is a photoinitiator ( 5 weight part of 2,4,6-trimethylbenzoyldiphenylphosphine oxide) by BASF Corporation was added, and it diluted with propylene glycol monomethyl ether so that solid content might be 60 weight%, and the coating liquid was prepared.

This coating liquid was apply | coated on the triacetyl cellulose (TAC) film (base film) of thickness 80micrometer, and it dried for 1 minute in the dryer set to 80 degreeC. The base film after drying was pressed and adhere | attached on the uneven surface of the metal roll for embossing produced by said (1) with a rubber roll so that an ultraviolet curable resin composition layer may become a roll side. In this state, light from a high-pressure mercury lamp having a strength of 20 mW / cm 2 is irradiated so as to be 300 mJ / cm 2 in the amount of h-line converted light, the ultraviolet curable resin composition layer is cured, and the light diffusion layer having irregularities on the surface. And the light-diffusion film of the structure shown in FIG. 2 containing a base film.

<Example 4>

As a light-transmitting microparticle, the light-diffusion film was produced like Example 1 except having used the weight average particle diameter of 6.0 micrometers and 30 weight part of polystyrene-type particle | grains whose standard deviation is 2.19 micrometers.

&Lt; Comparative Example 1 &

A light-diffusion film was produced in the same manner as in Example 1 except that 10 parts by weight of polystyrene particles having a weight average particle diameter of 6.0 µm and a standard deviation of 2.19 µm were used as the light-transmitting fine particles.

Comparative Example 2

A light-diffusion film was produced in the same manner as in Example 1 except that 70 parts by weight of polystyrene particles having a weight average particle diameter of 6.0 μm and a standard deviation of 2.19 μm were used as the light-transmitting fine particles.

&Lt; Comparative Example 3 &

A light-diffusion film was produced in the same manner as in Example 1 except that 20 parts by weight of polystyrene particles having a weight average particle diameter of 7.2 m and a standard deviation of 0.52 m were used as the light-transmitting fine particles.

&Lt; Comparative Example 4 &

A light-diffusion film was produced in the same manner as in Example 1 except that 40 parts by weight of polystyrene particles having a weight average particle diameter of 7.2 m and a standard deviation of 0.52 m were used as the light-transmitting fine particles.

&Lt; Comparative Example 5 &

As a light-transmitting microparticle, the light-diffusion film was produced like Example 1 except having used 60 weight part of polystyrene particle | grains whose weight average particle diameter is 7.2 micrometers, and the standard deviation is 0.52 micrometers.

&Lt; Comparative Example 6 >

The light-diffusion film was produced like Example 2 except having hardened the ultraviolet curable resin composition layer of the base film after drying, without making it adhere to the mirror surface of the mirror surface metal roll.

Table 1 summarizes the optical properties, surface shape and the like of the obtained light-diffusion film.

Moreover, the liquid crystal display device was produced using the obtained light-diffusion film, and the front contrast, viewing angle, the degree of moiré, and the degree of whitening were evaluated. First, on the backlight device of Panasonic 32 type liquid crystal television "VIERA TH-32LZ85" of IPS mode, the light-diffusion plate whose luminance value in a 70 degree direction with respect to a normal line direction is 10% of the luminance value in a normal line direction is arrange | positioned, Two prism films in which a plurality of linear prisms at 95 degrees were arranged in parallel were used, and these were disposed between the light diffusion plate and the backlight side polarizing plate. At this time, one prism film (backlight device side prism film) is arrange | positioned so that the direction of the ridgeline of the linear prism may become substantially parallel to the transmission axis of a backlight side polarizing plate, and the other prism film (backlight side polarizing plate side prism film) ) Was arranged so that the direction of the ridge line of the linear prism was substantially parallel to the transmission axis of the viewing-side polarizing plate described later.

Moreover, the visual recognition side polarizing plate was peeled and the iodine type polarizing plate ("TRW842AP7" by Sumitomo Chemical Co., Ltd.) was bonded so that it might become cross nicol with respect to a backlight side polarizing plate, and it produced in Examples 1-4 or Comparative Examples 1-6 on it. The light-diffusion film was bonded together through the adhesive layer, and the liquid crystal display device was obtained.

Table 2 shows the evaluation results of the front contrast, the viewing angle, the degree of moiré and the degree of whitening. These measurement methods and evaluation criteria are as follows.

(a) front contrast

The obtained liquid crystal display device was started in the dark room, the front brightness in black display state and white display state was measured using the luminance meter BM5A type | mold (made by Topcon Co., Ltd.), and front contrast was computed. The front contrast is the ratio of the front luminance in the white display state to the front luminance in the black display state.

(b) viewing angle

The display quality of the obtained liquid crystal display device was evaluated in the directions whose viewing angles (angle formed with the front direction of a liquid crystal display device) are 40 degrees, 50 degrees, and 60 degrees. Evaluation criteria are as follows.

(Double-circle): An abnormality is not seen at all in display quality.

(Circle): An abnormality is hardly seen in display quality.

(Triangle | delta): Gradation collapse and inversion are seen slightly.

X: Gradation collapse and inversion are seen.

(c) moiré

The obtained liquid crystal display device was started and the degree of moire was visually evaluated. Evaluation criteria are as follows.

(Double-circle): Moire is not seen at all.

○: Moiré is slightly observed.

X: Moire is remarkably observed.

(d) whitening

The obtained liquid crystal display device was visually observed in the bright room where fluorescent lamp was lighted, and the degree of whitening was evaluated. Evaluation criteria are as follows.

(Double-circle): Whitening is not seen at all.

(Circle): Whitening is observed slightly.

X: Whitening is observed remarkably.

As shown in Table 2, the liquid crystal display device using the light-diffusion film of Examples 1-4 has high front contrast, was excellent in viewing angle and moire resolution, and whitening did not occur.

On the other hand, in the liquid crystal display device using the light diffusing film of Comparative Example 1, since the compounding quantity of the translucent microparticles | fine-particles is small, the light-diffusion property of a light-diffusion film becomes inadequate, As a result, since a viewing angle is narrow and transmission transparency is high, it is moire-removable Fell. Since the liquid crystal display device using the light-diffusion film of the comparative example 2 has many compounding quantities of translucent microparticles | fine-particles, as a result, the light diffusivity of the light-diffusion film was too high and the front contrast fell. The liquid crystal display device using the light-diffusion film of Comparative Examples 3-5 was inferior to the moire-resolving property, since the transparency of transmission of the light-diffusion film was high. Since the liquid crystal display device using the light-diffusion film of the comparative example 6 has a large centerline average roughness Ra of a light-diffusion film, and the surface is rough, transmission clarity becomes low, As a result, front contrast falls and whitening is remarkable.

<Example 5>

(Preparation of Water-soluble Adhesive)

3 parts of carboxyl group-modified polyvinyl alcohol (KL-318 by Kuraray Co., Ltd.) is melt | dissolved with respect to 100 parts of water, and the polyamide epoxy additive (Sumika ChemteX Co., Ltd. product) which is a water-soluble epoxy compound in the aqueous solution. Sumirez resin 650 (30), and an aqueous solution of 30% solid content concentration] 1.5 parts were added to obtain a water-soluble adhesive.

(Preparation of acrylic pressure sensitive adhesive)

The organic solvent solution which urethane acrylate oligomer and the isocyanate type crosslinking agent were mix | blended with the copolymer of butyl acrylate and acrylic acid was dried by the die coater on the mold release surface of the polyethylene terephthalate film (separator) of thickness 38micrometer in which the mold release process was performed. It coated and dried so that the thickness might be 25 micrometers, and it was set as the acrylic adhesive (with a separate film).

(Manufacture of Polarizing Plate)

The light-diffusion film created in Example 1 to which the saponification process was performed was bonded to one surface of the polarizer in which iodine is adsorbed-oriented to a polyvinyl alcohol film, and saponification process is performed as a liquid crystal side transparent protective film to the other surface. The transparent protective film [KC4UEW by Konica Minolta Opto Co., Ltd. product] containing the triacetyl cellulose of 40 micrometers of thickness which were added was bonded together, and the light-diffusion polarizing plate was produced. For bonding, the polarizer and the transparent protective film were adhere | attached by drying at 80 degreeC after bonding for 5 minutes using the water-soluble adhesive prepared above, respectively.

The acrylic adhesive (with a separate film) prepared above was bonded to the 40 micrometer-thick transparent protective film side of this polarizing plate at the adhesive side, and it was set as the polarizing plate with an adhesive.

<Example 6>

(Production of antireflection film)

10 parts by weight of dipentaerythritol triacrylate, 10 parts by weight of pentaerythritol tetraacrylate, 30 parts by weight of urethane acrylate (`` UA-306T '' manufactured by Kyoeisha Chemical Co., Ltd.), and `` Suncure 184 '' as a photopolymerization initiator. Chiba Japan Co., Ltd.) 2.5 weight part, 50 weight part of methyl ethyl ketones, and 50 weight part of butyl acetate were mixed as a solvent, and the coating liquid for hard-coat layer formation which is an ultraviolet curable resin composition was prepared. This coating liquid was apply | coated with the wire bar coater on the transparent resin film (refractive index 1.49) which is a 80-micrometer-thick TAC film, and it dried for 1 minute in the dryer set to 80 degreeC. About the transparent resin film after drying, the hard-coat layer was formed by irradiating ultraviolet-ray for 10 second from the distance of 20 cm by the output of 120 W using the metal halide lamp. The obtained hard coat layer had a thickness of 5 µm and a refractive index of 1.52.

Next, isopropyl alcohol and 0.1 N hydrochloric acid were added and hydrolyzed to tetraethoxysilane, and the solution containing the polymer of tetraethoxysilane which consists of oligomers was obtained. The solution was mixed with antimony-doped tin oxide (ATO) fine particles having a primary particle size of 8 nm, and isopropyl alcohol was added to contain 2.5% by weight of a polymer of tetraethoxysilane and 2.5% by weight of antimony-doped tin oxide particles. The coating liquid for antistatic layer formation was obtained. On the other hand, the TAC film on which the hard coat layer was formed was immersed in an aqueous 1.5 N-NaOH solution at 50 ° C. for 2 minutes, subjected to alkali treatment, washed with water, and then neutralized by immersing in a 0.5% by weight aqueous solution of H ₂ SO ₄ at room temperature for 30 seconds. The mixture was washed with water again and dried. The antistatic layer was formed by apply | coating the said antistatic layer formation liquid on the hard-coat layer which carried out the alkali treatment by the wire bar coater, and drying for 1 minute in the dryer set to 120 degreeC. The obtained antistatic layer had a thickness of 163 nm, a refractive index of 1.53, and an optical film thickness of 250 nm.

Next, isopropyl alcohol and 0.1 N hydrochloric acid were added to a 95: 5 (molar ratio) mixture of tetraethoxysilane and 1H, 1H, 2H, and 2H-perfluorooctyltrimethoxysilane to form a oligomer. A solution containing a polymer of organosilicon compound was obtained. The low refractive index silica fine particles having voids therein were mixed with this solution, and isopropyl alcohol was added to obtain a coating solution for forming a low refractive index layer containing 2 wt% of an organosilicon compound and 2 wt% of low refractive index silica fine particles. . The low refractive index layer was formed by apply | coating the obtained coating liquid for low refractive index layer formation on the antistatic layer with the wire bar coater, and drying for 1 minute in the dryer set to 120 degreeC. The obtained low refractive index layer had a thickness of 91 nm, a refractive index of 1.37 and an optical film thickness of 125 nm. As described above, an antireflection film including a hard coat layer, an antistatic layer, and a low refractive index layer was prepared on the transparent resin film.

(Creation of antireflection film laminated light diffusing polarizing plate)

The anti-reflective film produced above was laminated | stacked on the light-diffusion film side of the polarizing plate with an adhesive produced in Example 5 through the general-purpose acrylic transparent adhesive, and the light-diffusing polarizing plate to which anti-reflective processing was performed was obtained.

Moreover, the liquid crystal display device was produced using the obtained light-diffusion polarizing plate, and the viewing angle, the degree of moire, and the grade of whitening were evaluated. The 32-inch type liquid crystal television "VIERA" made by Panasonic in the IPS mode was subjected to the same evaluation as above except that the viewing-side polarizing plate was peeled off and the light diffusing polarizing plates produced in Examples 6 and 7 were bonded so as to be cross nicol with respect to the backlight-side polarizing plate. TH-32LZ85 "to obtain a liquid crystal display device.

The evaluation method and evaluation criteria are the same as the above evaluation.

Table 3 shows the evaluation results of the viewing angle, the degree of moiré, and the degree of whitening.

As shown in Table 3, the liquid crystal display device using the light-diffusion polarizing plates of Examples 5 and 6 had the same display characteristics as Example 1, was excellent in viewing angle and moiré resolution, and did not produce whitening.

100, 200, 300, 707: light diffusing film 101: base film
102: light diffusing layer 103: translucent resin
104: light transmitting fine particles 105: resin layer
106: antireflection layer 107: transparent film
108: adhesive layer or pressure-sensitive adhesive layer 501: unwinding device
502: coating apparatus 503: backup roll
504: dryer
505: Mirror metal roll or metal roll for embossing
506: nip roll 507: peeling roll
508: ultraviolet irradiation device 509: winding device
600: light diffusing polarizing plate 601: polarizing film
602: protective film 701: liquid crystal cell
702: backlight device 703: light diffusion plate
704a and 704b: prism film 705: backlight side polarizing plate
706: viewer side polarizer 708: phase difference plate
711a and 711b transparent substrate 712 liquid crystal layer
721 case 722 cold cathode tube
741a, 741b: linear prism 742a, 742b: ridge of linear prism
801: layer with surface irregularities

Claims (12)

As a light-diffusion film which has a base film and a light-diffusion layer laminated | stacked on the said base film, and the translucent microparticles | fine-particles disperse | distributed,
The ratio L ₂ of the intensity L ₂ of the laser beam transmitted in a 40 ° tilt direction from the normal direction on the light diffusion layer side to the intensity L ₁ of the laser light having a wavelength of 543.5 nm incident on the normal direction of the light diffusing film from the base film side. / L ₁ is 0.0002% or more and 0.001% or less,
The sum of transmission sharpness obtained by passing through the optical combs of 0.125 mm, 0.5 mm, 1.0 mm and 2.0 mm is 70% or more and 180% or less,
The total haze is 40% or more and 70% or less, the internal haze is 40% or more and 70% or less, the surface haze resulting from the surface shape of the light diffusing layer is less than 2%,
The light-diffusion film whose center line average roughness Ra of the surface of the said light-diffusion layer is 0.2 micrometer or less. The light-diffusion film of Claim 1 whose sum of the said transmission clarity is 70% or more and 150% or less. The light diffusing film according to claim 1 or 2, wherein the surface haze is 1% or less. The light-diffusion film in any one of Claims 1-3 whose said centerline average roughness Ra is 0.1 micrometer or less. The light-diffusion film in any one of Claims 1-4 whose layer thickness of the said light-diffusion layer is 1 times or more and 3 times or less with respect to the weight average particle diameter of the said translucent microparticles. The light diffusing film according to any one of claims 1 to 5, further comprising an antireflection layer laminated on the light diffusing layer. As a manufacturing method of the light-diffusion film of Claim 1,
Applying a resin liquid containing the light-transmitting fine particles dispersed on the base film;
A step of transferring the mirror surface or uneven surface of the mold to the surface of the layer containing the resin liquid
Method for producing a light diffusing film comprising a. A polarizing plate having at least a polarizing film,
The light-diffusion film in any one of Claims 1-6 laminated | stacked on the said polarizing plate so that the said base film side may face the said polarizing plate.
Light diffusing polarizing plate comprising a. The light diffusing polarizing plate according to claim 8, wherein the polarizing film and the light diffusing film are bonded to each other via an adhesive layer. A liquid crystal display device comprising a backlight device, a light deflecting means, a backlight side polarizing plate, a liquid crystal cell, and the light diffusing polarizing plate according to claim 8 or 9. The said optical deflecting means has two prism films which have a some linear prism in the surface which opposes the said backlight side polarizing plate,
One prism film is arranged so that the direction of the ridge line of the linear prism is substantially parallel to the transmission axis of the backlight-side polarizing plate, and the other prism film has the direction of the ridge line of the linear prism of the light diffusing polarizing plate. A liquid crystal display device arranged to be substantially parallel to the transmission axis. The liquid crystal display device according to claim 10 or 11, further comprising light diffusing means between the backlight device and the light deflecting means.

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