JP2012226158A - Film for improving viewing angle, film laminate for improving viewing angle, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film for improving a viewing angle achieving both of a viewing angle improving effect and suppression of decrease in front brightness in high levels while suppressing changes in tones and being installed on an observer's side with respect to a liquid crystal layer of a liquid crystal display device.SOLUTION: The film for improving a viewing angle is a multilayer light diffusion film formed by superposing, at least on one surface of a light diffusion layer composed of primarily two kinds of polyolefin resins incompatible with each other, an improved adhesive layer composed of polyolefin resin primarily including a polar group, with its laid on the topmost layer. The film simultaneously satisfies the following characteristics. (1) A half width of a luminous intensity distribution pattern in a main diffusion direction of light having a wavelength of 440 nm that is measured by a method described in the specifications is 18 degrees or less. (2) A ratio (I30/I0×100) measured by the method described in the specifications, of the transmittance (I0) at an emission angle of 0 degree of light having a wavelength of 440 nm in the main diffusion direction to the transmittance (I30) at an emission angle of 30 degrees is 0.25 to 5.5%.

Description

  The present invention is a viewing angle improvement film installed on the viewer side from the liquid crystal layer of the liquid crystal display device, which achieves both a viewing angle improvement effect that suppresses a change in color tone depending on the viewing angle and a suppression of a decrease in front luminance, at a high level, The present invention relates to a laminate of the viewing angle enhancement film and a polarizing plate, and a liquid crystal display device that achieves both a viewing angle improvement effect using the laminate and suppression of a decrease in front luminance at a high level.

  Liquid crystal display devices are widely used as flat panel displays by taking advantage of their features such as thinness, light weight, and low power consumption, and their applications are yearly as display devices for information such as mobile phones, personal digital assistants (PDAs), personal computers, and televisions. It is expanding.

However, the liquid crystal display device has a problem that the viewing angle is narrower than that of the CRT.
The viewing angle means that when the angle at which the screen of the liquid crystal display device is observed is changed, the angle with respect to the vertical line of the screen is increased, that is, the screen image is larger than when viewed from the front as it becomes more oblique. This refers to the phenomenon of image quality degradation. Examples of the image quality include phenomena such as hue of a color image, image contrast, luminance of a white display image, and white blur due to light leakage of a black display image. In the deterioration of the image quality, the change in the hue of the color image is particularly important.

  The color change is, for example, the degree of change in the color tone of a phenomenon in which when a white image is observed at a different angle, an image that appears white in frontal observation is observed obliquely, the color changes to a yellowish color. Determined. Hereinafter, the degree of color change is referred to as a color shift degree, and the effect of suppressing the color shift is referred to as a viewing angle improvement effect.

  As a method for expressing the above viewing angle improvement effect, a method of installing a light diffusion film on the viewing side of a liquid crystal cell of a liquid crystal display device is known. Since this method can provide an improvement effect without changing the liquid crystal alignment in the liquid crystal layer, the electrode structure, and the like, the manufacturing process of the liquid crystal display device is simple and useful without increasing the number of steps. However, since the light emitted from the screen passes through the diffusion film and the transmitted light is scattered, the brightness of the screen when viewed from the front, that is, the brightness is lowered, and the image becomes dark. Hereinafter, this is referred to as a decrease in front luminance. That is, the effect of improving the viewing angle and the suppression of the decrease in front luminance are anti-paradoxical events and are difficult to achieve both. Therefore, a viewing angle enhancement film that can exhibit a large viewing angle improvement effect with a reduction in front luminance as low as possible is desired.

For example, Patent Document 1 proposes that a light diffusing film having a function of scattering and transmitting incident light is provided on a liquid crystal display screen. This film is obtained by melt-extruding a composition having a transparent island resin having a different refractive index as a sea-island structure into a sheet shape and further stretching, but the diffuse transmitted light of the film shown in FIGS. The following points are suggested from the intensity distribution (hereinafter also referred to as a light distribution pattern).
Although the effect of improving the viewing angle in the direction of FIG. 3 is excellent, the reduction in front luminance becomes large. On the other hand, in the direction of FIG. 4, a decrease in front luminance is suppressed, but the viewing angle improvement effect is inferior. In the case of a so-called anisotropic diffusion film in which the light diffusibility is different in the film direction, the decrease in the front luminance is large because the decrease in the front luminance is governed by the larger diffusion degree.
That is, in both directions, the viewing angle improvement effect and the suppression of the decrease in front luminance cannot be achieved.

  Further, Patent Document 2 proposes a spectrally anisotropic scattering film having a scattering angle distribution that varies depending on the wavelength and that has a different diffused light distribution in two directions that differ by 90 degrees in azimuth with respect to the film surface. From the light distribution pattern of the film shown in FIGS. 3 (a) and 3 (b) of Patent Document 2, this film has an excellent viewing angle improvement effect on both the left and right and upper and lower sides as in Patent Document 1. However, it is suggested that the reduction in the front luminance is large and the viewing angle improvement effect and the suppression of the reduction in the front luminance are not compatible.

  Furthermore, Patent Document 3 proposes a transmitted light scattering control film made of a single thermoplastic resin and having a portion containing a large number of fine pores inside. This film is obtained by drawing a melt-formed polycarbonate and utilizing light scattering caused by groove-shaped cracks. From the light distribution pattern of the film of FIG. 13 of Patent Document 3, α = ± 90 °. It is suggested that both the azimuth and α = 0 and 180 ° azimuth are good with little reduction in front luminance, but the effect of improving the viewing angle is not sufficient.

  Further, Patent Document 4 proposes a method using a lens film. From the light distribution distribution pattern of the film shown in FIGS. 8 (left and right direction) and 9 (up and down direction) of Patent Document 4, with respect to the left and right direction in FIG. On the other hand, it is suggested that the effect of improving the viewing angle is not sufficient in the vertical direction of FIG. As described above, when an anisotropic diffusion film is used as described above, the reduction in front luminance is governed by the greater diffusivity, so in the disclosed technique, the front luminance reduction is performed regardless of the direction of use of the film. Is big.

  Furthermore, Patent Document 5 proposes a transmitted light scattering control film in which a light diffusing layer made of translucent particles and a translucent resin is formed on the surface of a base film. From the light distribution distribution pattern of the film shown in FIG. 2 of Patent Document 5, the front luminance reduction is small and good, but the viewing angle improvement effect is not sufficient.

  As described above, some conventional methods for improving the viewing angle with a light diffusing film satisfy either the viewing angle improvement effect or the suppression of the decrease in front luminance, but both characteristics are advanced. At present, there is no one that can achieve both levels.

Japanese Patent Laid-Open No. 7-114013 JP 2004-341309 A Japanese Patent Laid-Open No. 10-206836 JP 09-179113 A JP 2003-270409 A

  The present invention was devised in view of the current state of the prior art, and the purpose of the present invention is to provide a liquid crystal display device that achieves both a viewing angle improvement effect that suppresses a change in color tone and a reduction in front luminance reduction at a high level. An object of the present invention is to provide a viewing angle improving film excellent in adhesiveness with a polarizing plate placed closer to the viewer than the liquid crystal layer. In addition, the present invention provides a laminate of the viewing angle improving film and the polarizing plate, and a liquid crystal display device in which a viewing angle improvement effect and a suppression of a decrease in front luminance are achieved at a high level by incorporating the laminate. It is in.

  As a result of diligent studies to achieve the above object, the present inventor has controlled the optical characteristics of a light diffusion film obtained by melt-molding a resin mixture having a specific composition within a specific range, thereby achieving a trade-off event. As a result, it was found that the effect of improving the viewing angle and suppressing the decrease in front luminance can be achieved at a high level, and the present invention has been completed.

That is, the present invention is as follows.
1. It is a multilayer light diffusing film in which an adhesion improving layer made of a polyolefin resin mainly containing polar groups is laminated on at least one surface of a light diffusing layer made mainly of two types of incompatible polyolefin resins. A viewing angle improving film characterized by simultaneously satisfying the following characteristics:
(1) The half-value width of the light distribution pattern in the main diffusion direction of light having a wavelength of 440 nm measured by the method described in the specification is 18 degrees or less;
(2) Ratio of transmittance (I0) at an exit angle of 0 ° and transmittance (I30) at an exit angle of 30 ° (I30 / I) in the main diffusion direction measured by the method described in the specification
I0 × 100) is 0.25 to 5.5%.

2. 2. The viewing angle improving film as described in 1 above, wherein the degree of anisotropy measured by the method described in the specification is 2.0 or more.

3. 3. The viewing angle improving film according to any one of 1 or 2 above, wherein at least one of the incompatible resins is a polyolefin resin.

4). The viewing angle improving film as described in 3 above, wherein the two types of incompatible resins are polyolefin resins.

5. 6. The viewing angle improving film as described in 3 or 5 above, wherein the polyolefin resin is selected from any one of a polyethylene resin, a polypropylene resin, and a cyclic polyolefin resin.

6). A viewing angle improving film laminate comprising the viewing angle improving film according to any one of 1 to 5 laminated on a polarizing plate surface.

7). 7. The viewing angle improving film laminate as described in 6 above, wherein the lamination is performed through an adhesive.

8). A liquid crystal display device comprising at least a backlight device and a liquid crystal cell, wherein the viewing angle improving film laminate according to the above 6 or 7 is used as a polarizer of the liquid crystal cell.

The viewing angle improving film of the present invention has a light distribution pattern having both characteristics of straight transmission and diffuse transmission, and the wavelength dependence of the emitted light depends on the angle of the emitted light. It is controlled to work effectively for improvement effect and front luminance reduction, so installing it on the viewing side of the liquid crystal cell of the liquid crystal display device has advanced anti-paradox phenomenon of viewing angle improvement effect and suppression of front luminance reduction. Can be balanced at the level. Furthermore, since the viewing angle improving film of the present invention is excellent in adhesiveness with a polarizing plate, it can be easily laminated with a polarizing plate and can be incorporated into a liquid crystal display device as a laminated body with a polarizing plate. Therefore, it is possible to provide a liquid crystal display device in which both the viewing angle improvement effect and the front luminance reduction suppression are compatible.

FIG. 6 is a diagram showing an example of luminance change depending on the observation angle when the viewing angle is improved with a highly diffusive light diffusion film. It is a figure which shows an example of the preferable light distribution pattern of the viewing angle improvement film of this invention.

(Basic characteristics of viewing angle enhancement film)
The viewing angle improving film of the present invention is such that the adhesion improving layer mainly made of a polyolefin resin containing a polar group is the outermost surface on at least one surface of a light diffusion layer mainly made of two incompatible polyolefin-based resins. A laminated multilayer light diffusing film, characterized by simultaneously satisfying the following characteristics:
(1) The half-value width of the light distribution pattern in the main diffusion direction of light having a wavelength of 440 nm measured by the method described in the specification is 18 degrees or less;
(2) Ratio of transmittance (I0) at an exit angle of 0 ° and transmittance (I30) at an exit angle of 30 ° (I30 / I) in the main diffusion direction measured by the method described in the specification
I0 × 100) is 0.25 to 5.5%.

(Half width diffusivity)
The viewing angle enhancing film of the present invention has a wavelength 44 measured by the method described in the examples.
It is important that the half width of the light distribution pattern in the main diffusion direction of 0 nm light is 18 degrees or less.
When the half-value width exceeds 18 degrees, when used in the viewing angle characteristic improving method of the present invention, a decrease in front luminance of the liquid crystal display device increases, and the intended effect of the present invention cannot be obtained.
A preferable upper limit of the half width is 16 degrees, and a more preferable upper limit is 14 degrees. The lower limit of the half width is not particularly limited, but is preferably 3 degrees, and more preferably 4 degrees.
Generally, diffusivity is evaluated by the half width (angle at half the height of the peak top of the light distribution pattern). The larger the half width, the stronger the diffusivity, and the smaller the half width, the poor diffusivity. . Said half width is measured by the method described in an Example. It is a measure of diffusivity that has been widely used. Hereinafter, the measured value may be referred to as a half-value width diffusivity.
However, diffusivity in a light distribution pattern suitable for achieving both a viewing angle improvement effect and a front luminance reduction suppression described later cannot be accurately shown only by using the half-value width diffusion degree as an index.
As described above, it is known that the light diffusion film can exhibit the effect of improving the viewing angle. As shown in FIG. 1, when a highly diffusive film having a half width of 57 degrees is used in the method of the present invention, the luminance when observed from an oblique direction (high angle) can be improved. The corner improvement effect can be exhibited, but at the same time, the front brightness is greatly reduced. Therefore, the viewing angle improvement effect and the front luminance reduction are anti-contradictory events.
The angle dependency of luminance in FIG. 1 was measured by the following method.

[Measurement method of luminance angle dependence]
Measurement was performed using RISA-COLOR / ONE-II (manufactured by Highland). A commercially available VA type liquid crystal display device test was installed horizontally on the pedestal and 131 × in the center of this panel.
131mm white image (Nokia monitor test for wi
nados V 1.0 (Nokia's Farbe mode) is displayed, and 3 drops of water are dropped on the white image with a dropper on the white image, and a light diffusion film is placed thereon, and water between the panel and the film is displayed. The distance between the CCD camera and the display is 1 m in a vertical state, and the CCD camera is −70 ° to +7 with respect to the panel surface of the liquid crystal display device.
The brightness was measured under the following conditions by moving on the equator up to 0 °, and the profile of the angle dependence of the brightness was obtained.
In the blank measurement, the same measurement was performed without attaching the viewing angle improving film.
The brightness was obtained by dividing the white image into 25 parts of 5 × 5, measuring the brightness of all the pixels of 9 parts of 3 × 3 at the center, and displaying the average value.

Therefore, in order to overcome the contradictory phenomenon of the effect of improving the viewing angle and suppressing the decrease in front luminance and to make both characteristics compatible at a high level, the half-value width diffusivity needs to be set to a rather low range as described above. In addition, it is necessary to impart diffusibility that can exhibit a viewing angle improvement effect.

(Preferable light distribution pattern)
The present inventors have intensively studied a method for solving the seemingly contradictory problem, and the viewing angle improvement effect is evaluated by the spread of the light distribution pattern even when the half-value width diffusivity is within the above range. It has been found that it can be expressed by increasing the diffusibility, and that the diffusivity can be evaluated with a transmittance of an emission angle of 30 degrees.

An example of a preferable light distribution pattern for satisfying the above optical characteristics is shown in FIG. That is, it is a light distribution pattern having a characteristic characteristic that has both the straight transmission and the diffuse transmission.
This light distribution pattern is obtained by measurement by the following method.
[Measurement method of light distribution pattern]
The measurement was performed using an automatic variable angle photometer (GP-200: manufactured by Murakami Color Research Co., Ltd.).
Transmission measurement mode, light incident angle: 0 ° (angle that is perpendicular to the sample surface both vertically and horizontally),
Light receiving angle: -90 ° to 90 ° (angle on the equator line), filter: using ND10, light beam stop: 10.5 mm (VS-1 3.0), light receiving stop: 9.1 mm (VS-3) 0) is fixed to the sample stage so that the main diffusion direction is the horizontal direction, and SENSITIVI is set so that the peak top value of the variable light intensity curve of the transmitted light is in the range of about 80% with respect to the full scale.
The setting of TY and HIGH VOLTON was adjusted and the variable-angle luminous intensity curve of the transmitted light was calculated | required.

(Spread spreading spread)
The viewing angle enhancing film used in the present invention preferably has a light transmittance of 0.7 to 10 at a wavelength of 440 nm at an exit angle of 30 degrees in the main diffusion direction as measured by the method described in the examples. 0.8-9 is more preferable and 1.0-8 is still more preferable. The upper limit is further preferably 7 or less, particularly preferably 6 or less, and most preferably 5.5 or less.
The relative transmittance at a wavelength of 440 nm at the emission angle of 30 degrees is a measure of diffusivity focusing on the spread of the light distribution pattern of the emitted light when light is incident in a direction perpendicular to the film surface, The larger the value, the wider the skirt, that is, the angle until the emitted light becomes zero. Hereinafter, this characteristic is referred to as a skirt spread diffusion degree.
If the skirt spreading diffusivity is less than 0.7, it is not preferable because the diffusibility is insufficient and the effect of improving the viewing angle is insufficient.
On the other hand, when the skirt spread diffusion degree exceeds 10, the effect of improving the viewing angle becomes excessive, and the color tone becomes bluish when observed obliquely, which is not preferable. In addition, the effect of suppressing the decrease in front luminance may be reduced.
The skirt spreading diffusion degree is a novel diffusibility evaluation scale newly created by the present inventors in the present invention.

(Spread spread ratio)
The above-mentioned spreading spread is important for the viewing angle improvement effect, but it is a sufficient characteristic to overcome the contradictory phenomenon of the viewing angle improvement effect and the suppression of the decrease in front luminance and to make both characteristics compatible at a high level. It can not be said.
In the preferable light distribution distribution pattern, it is preferable that the straight transmission is high in terms of suppressing a decrease in front luminance. That is, it is preferable that the transmittance is high at an emission angle of 0 degree. Therefore,
In order to make both of the above characteristics compatible at a high level, it is important to balance the transmittance at the exit angle of 0 degrees and the skirt spread ratio. It was found that this balance can be displayed by the ratio (I30 / I0 × 100) of the transmittance (I0) at the exit angle 0 ° and the transmittance (I30) at the exit angle 30 °, and the present invention was completed.
That is, the ratio of the transmittance (I0) at the exit angle of 0 ° and the transmittance (I30) at the exit angle of 30 ° (I30 / I0 × X) of light having a wavelength of 440 nm in the main diffusion direction measured by the method described in the examples. 100) is important to be 0.25 to 5.5%.
The skirt spreading diffusivity ratio is more preferably 0.30 to 5.0%, and further preferably 0.35 to 4.5%.
Hereinafter, the above characteristic is referred to as a skirt spread diffusion ratio.
Only when the skirt spread diffusivity ratio is satisfied within the above range can the above-mentioned characteristics of the antinomy event be made compatible at a high level. In other words, if the skirt spreading diffusivity is less than 0.25%, the suppression of lowering the front brightness is good, but the effect of improving the viewing angle is insufficient, such being undesirable. Conversely, if the skirt spread ratio exceeds 5.5%, it is not preferable because the front luminance decreases greatly. In some cases, the color shift correction effect is excessive and the color tone is bluish.
The skirt spreading diffusivity ratio is more preferably 0.30 to 5.0%, and further preferably 0.35 to 4.5%.
For example, when the main spreading spread ratio is obtained from the figures described in the above-mentioned patent documents, the high diffusivity side of Patent Document 1, the (b) of FIG. The side diffusivity ratios are 88%, 60% and 78%, respectively. Therefore, it can be said that the preferable skirt spread ratio described above is in a significantly lower range than the films disclosed in these patent documents.

(Wavelength dispersion)
It is also important to pay attention to the wavelength “440 nm” in the definition of the skirt spread diffusivity and the skirt spread diffusivity ratio. As described above, the phenomenon that the viewing angle characteristic is low is caused by the fact that the color tone that appears white when viewed from the front becomes a yellowish tone when observed from a high angle. The present inventors consider that it is important for blue light to be more easily transmitted at a high angle in order to cancel such color change as one means for expressing the viewing angle improvement effect. We focused on the wavelength of 440 nm.
Accordingly, it can be said that the above-described skirt spread diffusivity and skirt spread diffusivity ratio are novel characteristic values that combine two factors of diffusibility and wavelength dispersion.
That is, the viewing angle improving film of the present invention is completely different in optical design from a conventionally known diffusion film.
In the present invention, attention is paid to the wavelength 440 nm for the half-value width diffusivity. As will be described later, the wavelength of 550 nm is important for the reduction in front luminance. Since the influence of the wavelength of light is small with respect to the half-value width diffusivity, there is no big difference even if it is evaluated at a wavelength of 550 nm.
(Anisotropy)
The viewing angle improving film used in the present invention preferably has an anisotropy of 2.0 or more as measured by the method described in the examples. 5.0 or more is more preferable, and 10 or more is more preferable.
If it is less than the said lower limit, since the effect of anisotropy falls, it is not preferable.
On the other hand, the upper limit is not limited, but 200 or more is technically difficult, and the effect of imparting anisotropy is saturated.
By satisfy | filling the said range, the viewing angle improvement effect and the suppression effect of a front luminance fall can be balanced in a more preferable direction.

In the case of a film having a high degree of anisotropy, the effect of improving the viewing angle in the main diffusion direction, which is the direction in which the degree of diffusion is high, is increased. Therefore, it is necessary to change the installation direction of the viewing angle enhancement film depending on the direction in which the viewing angle needs to be improved. That is, when improving the viewing angle in the left-right direction of the liquid crystal display device, conversely, when improving the viewing angle in the up-down direction so that the main diffusion direction is parallel to the left-right direction of the panel, the main diffusion direction is It is preferable to install so as to be parallel to the vertical direction.
By this correspondence, there is also a merit that the effect of improving the viewing angle only in the necessary direction can be expressed.

(Total light transmittance)
The viewing angle enhancement film of the present invention has a wavelength of 55 measured by the method described in the examples.
The total light transmittance of 0 nm light is 79 to 95%.
If the total light transmittance is less than 79%, the brightness of the liquid crystal display device due to the film installation is remarkably reduced, and the front brightness is greatly reduced regardless of the effect of improving the viewing angle. The upper limit of the almost total light transmittance is 100%.
Note that the total light transmittance of light having a wavelength of 550 nm is focused on the human eye at a wavelength of 55.
This is because light near 0 nm is considered to have the highest spectral luminous efficiency.

(Action mechanism)
It is publicly known that a viewing angle improvement effect can be exhibited by a light diffusion film. Certainly, as described above, the brightness when observed from an oblique direction (high angle) can be improved by using a highly diffusive film evaluated by a conventionally known half width method diffusion degree, but at the same time, the brightness of the front surface Is significantly reduced. Therefore, the viewing angle improvement effect and the front luminance reduction are anti-contradictory events.
In order to overcome the contradictory phenomenon of the viewing angle improvement effect and the front luminance reduction suppression, it is important to use the light distribution pattern shown in FIG. That is, it is important to set the skirt spreading diffusivity ratio within a specific range. Furthermore, the wavelength dispersion of the emitted light that has passed through the viewing angle improving film is also important. That is, it is important that the light emitted in the direction with a higher angle from the normal to the film surface contributing to the viewing angle improvement effect is designed so that the relative transmittance of light having a wavelength of 440 nm close to blue is high. It is presumed that the viewing angle improvement effect and front luminance can be achieved at a high level due to the synergistic effect of these factors.
The importance of some of the individual factors described above has been disclosed in the prior art, but the anti-contradictory phenomenon of improving viewing angle and reducing front luminance has been overcome by the mechanism of action by simultaneously satisfying all the above factors. An anisotropic light diffusing film can be achieved for the first time in the present invention.

The reason why it is possible to balance the effect of improving the viewing angle and the effect of suppressing the decrease in front luminance in a more favorable direction by increasing the degree of anisotropy is not clear, but by increasing the degree of anisotropy, the emitted light is condensed in a specific direction It is speculated that this is caused by the difference in the contribution of the light collection effect between the viewing angle improvement effect and the front luminance reduction.

(Preferable range of decrease in front brightness)
Although the degree of reduction in front luminance of the present invention is not limited, it is possible to achieve a viewing angle improvement effect within the allowable range of front luminance reduction without changing the system configuration of the entire liquid crystal display device such as improvement in luminance of the backlight device. , The luminance reduction rate displayed in% when the viewing angle improvement film is installed when the luminance when the viewing angle improvement film is not installed is 100% (hereinafter including the front luminance reduction rate) The standard expression for lowering the front brightness is preferably 20% or less. 18% or less is more preferable, and 15% or less is more preferable.
Although the absolute value of the front luminance varies depending on the method and type of the panel, it has been confirmed that when the evaluation is performed based on the above reduction in front luminance, the value is almost constant even if the method and type of the panel are changed.
By satisfying the total light transmittance, the above-described reduction in front luminance can be made a preferable range.

(Preferable range of viewing angle improvement effect)
In the present invention, the viewing angle improvement effect was evaluated by the method described in the examples. That is, a white image is displayed on the panel of a commercially available liquid crystal display device, the CCD camera is moved on the equator of the image, the angle dependency of the x value of the YIE system of the CIE color system is measured, and The x value (x0) at 0 degrees and the x value (x70) at 70 degrees are obtained, and Δx (70 degrees) = x0−
x70 was evaluated with the calculated value. Hereinafter, the value (Δx (70 degrees)) is referred to as a color shift degree. In general, a panel of a liquid crystal display device has a positive color shift degree. The y value also behaves almost the same as the x value and is displaced in the green and red directions, resulting in a yellowish color. Since both the x value and the y value exhibit almost similar behavior, the x value is used as a representative value in the present invention.
By canceling the shift of the color shift degree to the positive side, the effect of improving the viewing angle appears. Therefore, it is preferable that the color coordinates of the viewing angle improving film are shifted in the negative direction. The color shift degree varies depending on the panel type and type. For example, in the case of the VA system, −0.006 to −0.02 is preferable. -0.008 to -0.018 is more preferable.
If it exceeds -0.006, the degree of color shift is insufficient and the effect of improving the viewing angle is reduced, which is not preferable. On the other hand, if it is less than -0.02, the degree of color shift is too high, so that the effect of improving the viewing angle becomes excessive, and the white image when viewed obliquely becomes a bluish tone, which is not preferable.

(Configuration of viewing angle enhancement film)
The viewing angle improving film of the present invention is such that the adhesion improving layer mainly made of a polyolefin resin containing a polar group is the outermost surface on at least one surface of a light diffusion layer mainly made of two incompatible polyolefin-based resins. It is important to have a laminated multilayer structure.

(Light diffusion layer)
The light diffusion layer of the present invention is preferably mainly composed of two types of incompatible polyolefin resins. Usually, a polyolefin-based resin does not have an aromatic ring and thus has a feature that it is not easily deteriorated by ultraviolet irradiation. Therefore, since it has the characteristic that yellowing by ultraviolet irradiation is suppressed, it is suitable as a constituent material of a light-diffusion film.

  The two types of incompatible polyolefin resins are not limited as long as they are a combination of resins that are incompatible with each other, but are preferably formed of a polypropylene resin and a polyolefin resin containing ethylene and / or butene. It is.

  Moreover, it is a preferable embodiment that the two types of incompatible polyolefin resins are composed of a cyclic polyolefin resin and a polyethylene resin.

With the above combination, control of optical characteristics by the light diffusion layer described later can be stably performed in a wide range. Moreover, it can be said that it is preferable also from the point of light resistance and economical efficiency.
In addition to the above combination, a nanocrystalline structure control polyolefin elastomer resin may be further combined.

The said polyolefin resin will not be limited if the 70 mol% consists of olefin monomers. It is preferable that 90% or more is composed of an olefin monomer. More preferably, 95% or more consists of olefinic monomers, and more preferably 98% or more consists of olefinic monomers.
Examples of the polyolefin resins include polyethylene resins, polypropylene resins, polybutene resins, polyolefin resins such as cyclic polyolefin resins and polymethylpentene resins, and copolymers thereof. In addition, modified polyolefin resins in which functional groups such as carboxyl groups, ester groups, and hydroxyl groups are introduced into these resins are also preferably used.
Moreover, you may be a copolymer of the monomer which does not have aromatic rings, such as acrylic acid, methacrylic acid, and these ester derivatives.

  The polyethylene resin may be a single polymer or a copolymer. In the case of a copolymer, it is preferable that 50 mol% or more is an ethylene component. The density and polymerization method of the polyethylene resin are not limited, but it is preferable to use a copolymer having a density of 0.909 or less. For example, a copolymer with octene is mentioned. The polymerization method may be either a metallocene catalyst method or a nonmetallocene catalyst method.

  The polypropylene resin may be a single polymer or a copolymer. In the case of a copolymer, it is preferable that 50 mol% or more is a propylene component. The production method, molecular weight and the like of the resin are not particularly limited, but those having high crystallinity are preferable from the viewpoint of heat resistance. Specifically, the crystallinity is determined by the heat of fusion measured by a differential scanning calorimeter (DSC), and preferably has a heat of fusion of 65 J / g or more.

  Examples of polyolefin resins containing ethylene and / or butene include homopolyethylene resins, homopolybutene resins, copolymers of these resins with other olefinic monomers, acrylic acid, methacrylic acid, and ester derivatives thereof. And the like. In the case of a copolymer with other olefinic monomers, any of random, block and graft copolymers may be used. Further, a dispersion such as EP rubber may be used. There are no particular limitations on the production method and molecular weight of the resin. For example, use of the above-described polyethylene resin or a copolymer of ethylene and butene is preferable.

  Examples of the cyclic polyolefin-based resin include those having a cyclic polyolefin structure such as norbornene and tetracyclododecene. For example, (1) a ring-opening (co) polymer of a norbornene monomer is subjected to polymer modification such as maleic acid addition or cyclopentadiene addition as necessary, and then a hydrogenated resin, (2) a norbornene monomer Examples include addition-polymerized resins, and (3) addition-copolymerized resins with norbornene monomers and olefin monomers such as ethylene and α-olefin. The polymerization method and the hydrogenation method can be performed by conventional methods.

  The nano-crystal structure control type polyolefin elastomer resin is a thermoplastic polyolefin-based elastomer in which the crystal / amorphous structure of the polymer is controlled in the nano order and the crystal has a network structure in the nano order. For example, manufactured by Mitsui Chemicals, Inc. Notio (registered trademark). The conventional polyolefin-based elastomer resin has a crystal size on the order of microns, whereas the nanocrystal structure control-type polyolefin-based elastomer resin has a feature that the crystal size is controlled on the order of nanometers. For this reason, it is often superior in transparency, heat resistance, flexibility, rubber elasticity and the like as compared with conventional polyolefin-based elastomer resins. Therefore, there are cases where the appearance of the resulting film can be improved by blending the nanocrystalline structure control polyolefin elastomer resin.

  The blending ratio of the at least two incompatible polyolefin resins is preferably 10/90 to 90/10, more preferably 20/80 to 80/20, and more preferably 30/70 to 30/70, respectively. A ratio of 70/30 is more preferred. The at least two incompatible polyolefin-based resins may be blended in the film forming process, or may be used in a form blended in advance by a kneading method or the like.

  In the present invention, three or more kinds of resins may be blended, and additives such as a compatibilizing agent and a dispersion diameter adjusting agent for improving the conformability of each resin may be used in combination. Moreover, you may mix | blend additives, such as stabilizers, such as antioxidant and a ultraviolet absorber, and antistatic agent. Further, fine particles such as inorganic particles and polymer beads may be added as long as the above optical characteristics are not impaired.

  The melt flow rate of the at least two incompatible polyolefin resins is not particularly limited as long as the above optical characteristics are satisfied. Each thermoplastic resin is appropriately selected in the range of a melt flow rate measured at 230 ° C. of 0.1 to 100, preferably 0.2 to 50.

The melt flow rate of the resin is appropriately selected in consideration of the resin composition, composition ratio, which resin is used as the sea, desired optical characteristics, and the like.
The guideline is that the higher the composition ratio and the lower the melt flow rate becomes the sea. In the case of the same amount, the higher the melt flow rate, the more likely to become the sea. When the melt flow rate with a higher composition ratio is high, a simple sea / island structure may be formed instead of a co-continuous phase, for example.

In the present invention, as described above, it is preferable to impart anisotropy to the diffusivity. In order to impart this characteristic, it is preferable to give anisotropy to the island structure. In order to form an island structure having such a shape, it is preferable to make a difference in melt viscosity between the sea component resin and the island component resin. In particular, it is preferable to lower the melt viscosity of the island component than the sea component. For this purpose, for example, it is preferable to provide a difference in melt flow rate, and it is preferable to increase the melt flow rate of the island component rather than the sea component. It is also preferable to make a difference between the rigidity of the sea component resin and the island component resin. In particular, it is preferable to lower the rigidity of the island component than the sea component.

In addition, when the melt flow rate of the island component is low, it is difficult to apply a force for thinning the island component due to the share or draft in the die, and the anisotropy may decrease. Mass ratio is 50
This tendency becomes stronger as the distance from / 50 increases. Each characteristic is adjusted in consideration of these tendencies.

When the two types of resins are both polyolefin-based resins, a combination of a cyclic polyolefin-based resin and a polyethylene-based resin or a polypropylene-based resin, or the combination of the three types is easy to obtain a film having the above-mentioned characteristics and is economical. Is preferable.

In the case of a combination of a cyclic polyolefin resin and a polyethylene resin or polypropylene resin, the polyethylene resin or polypropylene resin is used as the sea phase, and the melt flow rate of the polyethylene resin or polypropylene resin in the sea phase is changed to the island phase. It is preferably higher than the melt flow rate of the cyclic polyolefin resin.

In the case of a combination of a cyclic polyolefin resin and a polyethylene resin or polypropylene resin, it is preferable that 10 to 60 mass% of the cyclic polyolefin resin is blended in the total resin amount, and more preferably 10 to 50 mass%. is there.
The said range is preferable with respect to the implementation | achievement of the preferable embodiment which makes the below-mentioned polyethylene-type resin and polypropylene-type resin a sea phase.
When the cyclic polyolefin resin, which is the reverse of the above configuration, is used as the sea phase, the desired optical properties, especially the degree of anisotropy, are related to the share in the die and the flexibility and fluidity of the sea phase. High viewing angle improvement film is difficult to obtain.

According to the above embodiment, even when the film forming apparatus is changed, there is an effect that a light diffusion film having desired optical characteristics can be stably obtained. I don't know why,
Even if there is a change in share due to differences in extrusion conditions or die shapes that occur when the film forming equipment is changed, by making the sea phase resin softer than the island phase resin and increasing its fluidity , I guess that the effect will be mitigated.

The size of the island phase when both of the two types are made of polyolefin resin is not particularly limited, but the average size of the minor axis determined by the laser scattering method is preferably 0.1 to 2 μm. If it is less than 0.1 μm, the degree of diffusion is insufficient, which is not preferable. Conversely, if it exceeds 2 μm, the degree of backscattering increases and the total light transmittance decreases, which is not preferable.

(Adhesion improvement layer)
The polyolefin resin containing a polar group in the present invention preferably contains at least one monomer of ethylene, propylene, butene, hexene, octene, methylpentene and cyclic olefin as its skeleton.
It may be a homopolymer using one kind of the above monomers or a copolymer using two or more kinds of monomers.

The polyolefin resin containing the polar group in the present invention preferably contains at least one kind of polar group. Examples of polar groups include carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, hydroxyl groups, glycidyl groups, isocyanate groups, amino groups, imide groups, oxazoline groups, ester groups, ether groups, carboxylic acid metal bases, sulfonic acid metal bases, Examples thereof include phosphonic acid metal bases, tertiary amine bases, and quaternary amine bases. The polar group may be one kind or two or more kinds.
It is a preferred embodiment that it contains at least a carboxyl group, which may be appropriately selected depending on the composition of the polyolefin-based resin constituting the light diffusion layer, the type of member to be adhered, the necessary adhesion, and the like.

  In the polyolefin resin containing a polar group in the present invention, even if the polar group is directly introduced into the polymer chain of the polyolefin resin, it is in a state of being introduced, added and mixed in another resin. It doesn't matter. Further, in some cases, the polyolefin resin of the present invention can be used after being modified by reacting, for example, a carboxylic acid group or a hydroxyl group with a compound capable of reacting with them, which is introduced at the end or inside of the molecular chain. .

  In the present invention, the polar group-containing polyolefin resin may be used alone or in a blended composition containing two or more. Moreover, the compounding composition which mix | blended polyolefin resin and other types of resin which do not contain a polar group may be sufficient. In the case of the blended composition, it is preferable that the polyolefin resin containing the polar group is contained in an amount of 10% by mass or more. More preferably, it is 30 mass% or more.

  The adhesion improving layer may be either a single area layer or a double-sided laminate. Although total thickness is not limited, 10-500 micrometers is preferable. Although the thickness composition ratio is not limited, it is preferable that the thickness of the adhesion layer is 2 to 100 μm on one side.

    The thickness constitution ratio of the light diffusion layer / adhesion improving layer is preferably 100/1 to 3/1, and more preferably 10/1 to 4/1. By doing so, the effect of improving the viewing angle and the effect of improving the adhesiveness can be balanced.

(Production method of viewing angle improving film)
The method for producing the viewing angle improving film of the present invention is not particularly limited as long as it satisfies the above-mentioned optical characteristics, but a method of forming a film by melt extrusion molding is preferred from the viewpoint of economy.
In the present invention, since it is not necessary to contain non-meltable fine particles in order to impart light diffusibility, clogging of the filtration filter of the molten resin in the film forming process is reduced even when the melt extrusion method is used. It has the characteristics that it is excellent in productivity and the clarity of the film obtained is high.

The film forming method by the melt extrusion method is not particularly limited, and may be, for example, either a T-die method or an inflation method. Moreover, the film may be an unstretched film or may be subjected to a stretching process.

In the melt extrusion molding method, generally, a resin melted by an extruder is extruded from a die into a sheet shape, and the sheet is brought into close contact with a cooling roll to be cooled and solidified to form a film. The close contact with the cooling roll may be performed by pressing with a generally used pressure roll. However, in the point of imparting anisotropy, the close contact portion may It is preferable that no liquid pool zone (sometimes referred to as a bank) is formed at the entrance. Since the formation of the liquid pool zone occurs when it is pressed against the cooling roll, that is, when it is pressed with a strong pressure, it is preferable to reduce the contact pressure during the contact. For example, it is better to avoid the method of being brought into close contact by pressing with a generally used pressure roll.
Although it will not be limited if it is the method of making it adhere | attach with a weak pressure, For example, the resin fuse | melted with the extruder is extruded to a sheet form from die | dye, and this sheet | seat is pressed by the gas pressure and / or the suction method and / or the electrostatic contact method. It is preferable that the film is formed by close contact and cooling and solidification. By this method, a viewing angle improving film having anisotropy can be stably obtained.

There is no limitation on the method of pressing by the gas pressure and / or the method of adhering and cooling and solidifying by the suction method and / or the electrostatic adhesion method. For example, as a pressing method by gas pressure, for example,
Examples thereof include a method such as a so-called air knife method in which the gas is pressed with a gas pressure such as air, a vacuum chamber method in which the gas is sucked and adhered by a vacuum nozzle, and an electrostatic adhesion method in which it is adhered by an electrostatic force. The method may be used alone or a plurality of methods may be used in combination. The latter is a preferred embodiment in that it can increase the thickness accuracy of the film obtained.

The viewing angle improving film of the present invention may be produced by either a non-stretching method or a stretching method. For example, when a polyester resin is used for the light diffusion layer, it is preferable to perform uniaxial stretching. The draw ratio is preferably 2 times or more. The upper limit is not limited, but is preferably less than 10 times. By this correspondence, the island phase is stretched in the stretching direction to form an elongated structure, the light diffusibility in the direction orthogonal to the orientation direction of the island phase is remarkably improved, and an anisotropic and high diffusibility can be secured.

When manufacturing by a non-stretching method, you may manufacture by the method of extending | stretching before melt-extruding the sheet | seat extruded by extrusion, ie, the method of raising a draft rate.

In addition, the viewing angle improving film of the present invention may be a single layer or a multilayer structure of two or more layers. In the case of a multilayer structure, as long as at least one layer is a layer made of a light diffusion film having the above structure, the other layer may be a simple transparent layer having no light diffusibility. Moreover, the structure of the light-diffusion layer may be sufficient as all the layers.
In the case of the multilayer structure, it may be produced by a multilayer coextrusion method, or may be carried out by an extrusion lamination method or a dry lamination method.

The mixture of the at least two incompatible thermoplastic resins may be blended with each of the thermoplastic resins by an extruder in the film forming process, or in a form that has been previously mixed by a kneading method or the like. It may be used.

10-500 micrometers is preferable and the thickness of the viewing angle improvement film of this invention has 20-500 micrometers.
More preferably, 20 to 200 μm is more preferable, but it varies greatly depending on the type of resin component of the light diffusion layer, the compounding ratio, the layer configuration, the production method, and the like.
When the thickness is adjusted, if the sea-island structure changes greatly due to changes in draft ratio, extrusion flow rate, lip width, etc., the above tendency may be reversed or extremely increased.

(Polarizer)
The polarizing plate in the present invention is not tested if a film or sheet having a polarizing function is prepared. For example, iodine or dichroic dye is dyed on PVA. Moreover, a polarizing plate single-piece | unit may be sufficient, for example, the composite_body | complex with various protective films may be sufficient.

(Viewing angle improving film laminate and adhesive)
The viewing angle improvement film laminated body of this invention is a laminated body formed by bonding together said viewing angle improvement film and a polarizing plate with an adhesive agent.
The adhesive is not limited as long as it is transparent and has adhesiveness with both the viewing angle improving film and the polarizing plate. For example, what has crosslinking | crosslinking property by active rays, such as a heat | fever and UV, is mentioned. For example, both the viewing angle improving film and the polarizing plate are familiar, and a blend of transparent monomers, oligomers and polymers and a crosslinking agent can be mentioned. Moreover, what has the functional group which causes a crosslinking reaction in the said method in the molecule | numerator of the said transparent monomer, oligomer, and polymer, or the compounded body of this component and a crosslinking agent may be sufficient.
Since many polarizing plates have a PVA polymer as a main component, the adhesive is preferably made of a PVA polymer. For example, polyvinyl alcohol obtained by saponifying polyvinyl acetate; derivatives thereof; saponified products of copolymers with vinyl acetate and monomers having copolymerizability; acetalization, urethanization, etherification of polyvinyl alcohol Modified polyvinyl alcohol obtained by grafting or phosphoric esterification. Examples of the monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof; α-olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkyl malate), disulfonic acid soda alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivatives, and the like. . These polyvinyl alcohol resins may be used alone or in combination of two or more.
The saponification degree of the PVA polymer is not limited, but is preferably 60 to 85%.
Although it does not specifically limit as a crosslinking agent at the time of using this PVA-type polymer, A water-soluble or water-dispersible thing is preferable. For example, it is not particularly limited as long as it has crosslinkability with a hydroxyl group, and examples thereof include melamine-based, isocyanate-based, carbodiimide-based, oxazoline-based, and epoxy-based compounds. From the viewpoint of the stability of the coating solution over time, melamine-based, isocyanate-based, carbodiimide-based, and oxazoline-based compounds are exemplified. Furthermore, the crosslinking agent is preferably a polyvinyl alcohol melamine compound or an isocyanate compound. Moreover, in order to promote a crosslinking reaction, you may use a catalyst etc. suitably as needed.

(Viewing angle characteristics improvement method)
The viewing angle characteristic improving method in the present invention is a liquid crystal display device having at least the viewing angle improving film or the viewing angle improving film laminate in a backlight source, a liquid crystal cell, and a polarizing plate disposed on the viewing side of the liquid crystal cell. The viewing angle improving film is placed on the viewing side of the polarizing plate, or the viewing angle improving film laminate is used as a polarizing plate disposed on the viewing side. Therefore, the method can be improved without increasing the number of steps of manufacturing the liquid crystal display device, and can be applied to any liquid crystal display device. Therefore, the method is very economical and has a wide application range.

  When laminating the above polarizing plate or a polarizing plate and a polarizing plate protective film and laminating them into a liquid crystal display device, the absorption axis of the polarizing plate used on the viewing side due to the mode difference of the liquid crystal display device It is preferable to deal with the difference in direction.

When the viewing angle improving film is installed on the viewing side of the polarizing plate in the viewing angle characteristic improving method, for example, the viewing side of the polarizing plate disposed on the viewing side of the liquid crystal cell with an adhesive or an adhesive having a small reflection loss. It is preferable to stick to.
The adhesive and the pressure-sensitive adhesive are not limited as long as the viewing angle improving film and the object can be fixed, but it is preferable to use an optical product.

(Liquid crystal display device)
The liquid crystal display device to which the present invention can be applied is not limited as long as the liquid crystal display device has at least a backlight light source, a liquid crystal cell, and a polarizer disposed on the viewing side of the liquid layer cell. For example, T
Examples include N, VA, OCB, IPS, and ECB mode liquid crystal display devices.

(Combination use of functional layers such as hard coat layers)
In the liquid crystal display device of the present invention, it is preferable that at least one functional layer selected from a hard coat layer, a reflection reducing layer, and an antiglare layer is combined on the surface on the viewer side of the viewing angle improving film. Each of the functional layers may have a single configuration, or a plurality of functions may be used in combination.
Combing the hard coat layer improves the scratch resistance of the viewing angle improving film surface. Also,
Due to the combination of the reflection reducing layer and / or the antiglare layer, even when the liquid crystal display device is used in an environment where external light is reflected, the reflection of external light is reduced and the visibility of the image is improved. In addition, even when used in a bright environment, the reduction in viewing angle improvement effect cannot be seen. The surface of the reflection reducing layer or the antiglare layer only needs to have an antireflection function. For example, an antiglare type, an antireflection type, or a type having both functions can be used. In particular, the latter two are preferred.
The functional layer may be combined directly on the surface of the viewing angle improving film, or may be combined with a plastic film such as TAC or PET having the functional layer.
The latter may be preferable because it can be carried out using products widely distributed in the market.
In the latter method, the film having the functional layer is preferably fixed with a pressure-sensitive adhesive or an adhesive, but may be simply overlapped and fixed with a jig.
The adhesive and the pressure-sensitive adhesive are not limited as long as the viewing angle improving film and the film having the functional layer can be fixed, but it is preferable to use an optical product.

(Attaching direction of viewing angle improving film)
The viewing angle improving film of the present invention can change the direction in which the viewing angle improving effect of the liquid crystal display device is manifested by increasing the degree of anisotropy.
For example, TVs are required to improve the viewing angle in the horizontal direction, but monitors for personal computers and various devices and display devices for digital signage may also be required to improve the viewing angle in the vertical direction.
Answering this requirement can be achieved by changing the installation direction of the viewing angle enhancement film.
That is, since the viewing angle in the main diffusion direction of the viewing angle enhancement film is improved, for example, when it is desired to improve the viewing angle in the lateral (horizontal) direction, the main diffusion direction of the viewing angle enhancement film is the abbreviation of the liquid crystal display device. It is preferable to install in the horizontal (horizontal) direction. On the other hand, when it is desired to improve the viewing angle in the vertical (vertical) direction, it is preferable that the main diffusion direction of the viewing angle improving film is set in the substantially vertical (vertical) direction of the liquid crystal display device.
The installation direction is displayed in the direction when the liquid crystal display device is installed in the vertical direction. Therefore, the horizontal (horizontal) direction can be expressed as the left-right direction, and the vertical (vertical) direction can also be expressed as the up-down direction.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and is implemented with appropriate modifications within a range that can be adapted to the gist of the present invention. These are all included in the technical scope of the present invention. The measurement / evaluation methods employed in the examples are as follows. In the examples, “parts” means “parts by mass” unless otherwise specified, and “%” means “% by mass” unless otherwise specified.
In this example, a comparative film that does not satisfy the characteristics of the present invention is also referred to as a viewing angle improving film for convenience.

1. Half-value width diffusivity (half-value width of the light distribution pattern in the main diffusion direction of light having a wavelength of 440 nm)
Measurement was performed using a variable angle spectrophotometric system GCMS-4 type (GSP-2 type: manufactured by Murakami Color Research Co., Ltd., variable angle spectrophotometer GPS-2 type). Transmission measurement mode, light incident angle: 0 °
(Film normal direction), light receiving angle: -80 ° to 80 ° (polar angle from film normal, azimuth is horizontal), light source: D65, field of view: 2 °, the main diffusion direction of the sample is horizontal The sample was fixed to the sample stage so as to be in the direction, and a variable angle spectrophotometric curve of the transmitted light was obtained. The tilt angle was 0 °.
In actual use, the deviation between the axis of the sample stage and the axis in the main diffusion direction is allowed up to about 20 degrees.
Measurements were taken at 5 ° pitch.
The angle at half the height of the peak top of the light distribution pattern obtained by the above measurement was determined and used as the half-value width diffusivity.
Prior to the measurement, the apparatus was calibrated using a transmission diffusion standard plate (opal glass) for GCMS-4 manufactured by Murakami Color Research Co., Ltd., and the transmitted light intensity at the light receiving angle of 0 degrees was used as a reference ( Relative permeability was measured as 1.000). The transmission diffusion standard plate is
The transmittance at 440 nm was 0.3069 when the air layer was set to 1.000 by integrating sphere spectroscopic measurement.
In this measurement, each sample was measured three times and displayed as an average value.
When the surface roughness is different between the two surfaces of the sample, it is preferable to measure the sample while fixing the sample so that the light transmission directions coincide when used as a viewing angle improving film. In the present invention, the measurement was carried out with the surface being fixed in the direction in which light enters from the lower surface roughness.
The main diffusion direction is the direction in the film plane where the maximum light diffusibility can be obtained, and can be easily determined using a laser pointer or the like.

2. Spreading skirt spread (relative transmittance of light having a wavelength of 440 nm at an emission angle of 30 degrees in the main diffusion direction)
Measurement was performed using a variable angle spectrophotometric system GCMS-4 type (GSP-2 type: manufactured by Murakami Color Research Co., Ltd., variable angle spectrophotometer GPS-2 type). Transmission measurement mode, light incident angle: 0 °
(Film normal direction), light receiving angle: 0 ° to 80 ° (polar angle from film normal, azimuth angle is horizontal), light source: D65, field of view: 2 °, main diffusion direction of sample is horizontal (The deviation between the axis of the sample stage and the axis of the main diffusion direction is allowed up to about 20 degrees)
A variable angle spectrophotometric curve of the transmitted light was obtained. The tilt angle was 0 °.
Measurement was performed at a 1 ° pitch from a light receiving angle of 0 ° to 10 °, and at a 5 ° pitch from 10 ° to 80 °.
Prior to the measurement, the apparatus was calibrated using a transmission diffusion standard plate (opal glass) for GCMS-4 manufactured by Murakami Color Research Co., Ltd., and the transmitted light intensity at the light receiving angle of 0 degrees was used as a reference ( Relative permeability was measured as 1.000). The transmission diffusion standard plate is
The transmittance at 440 nm was 0.3069 when the air layer was set to 1.000 by integrating sphere spectroscopic measurement.
In this measurement, each sample was measured three times and displayed as an average value. The transmittance was displayed at a wavelength of 440 nm at a light receiving angle (hereinafter referred to as an emission angle) of 30 degrees.
When the surface roughness is different between the two surfaces of the sample, it is preferable to measure the sample while fixing the sample so that the light transmission directions coincide when used as a viewing angle improving film. In the present invention, the measurement was carried out with the surface being fixed in the direction in which light enters from the lower surface roughness.
The main diffusion direction is the direction in the film plane where the maximum light diffusibility can be obtained, and can be easily determined using a laser pointer or the like.

3. Bottom spread diffusivity ratio (ratio of transmittance (I0) at an output angle of 0 ° and transmittance (I30) at an output angle of 30 ° (I30 / I0 × 100) of light having a wavelength of 440 nm in the main diffusion direction)
The transmittance at the emission angle of 0 ° and 30 ° with a wavelength of 440 nm is measured by the same method as the above-described spread spread, and the transmittance at the emission angle of 0 ° (I0) and the transmittance at the emission angle of 30 ° (I30
) Ratio (I30 / I0 × 100) was calculated and expressed in%.
When the surface roughness is different between the two surfaces of the sample, the sample is fixed in the direction in which the light transmission directions in actual use coincide with each other. In the present invention, the measurement was carried out with the surface being fixed in the direction in which light enters from the lower surface roughness.

4). Anisotropy The skirt spread diffusivity obtained by the above skirt spread diffusivity measurement method was defined as (I30) H.
Further, in the skirt spread diffusion degree measuring method described above, the sample is fixed to the sample stage so that the main diffusion direction of the sample is vertical, and the skirt spread in the direction perpendicular to the (I30) H is performed in the same manner as described above. The diffusivity (I30) V was determined.
The degree of anisotropy was calculated by the following (1).
(I30) H / (I30) V (1)

5. Total light transmittance Self-recording spectrophotometer (UV-3150; manufactured by Shimadzu Corporation) with integrating sphere attachment device (ISR-31)
00; manufactured by Shimadzu Corporation), and a spectral range was measured by scanning a range of wavelengths of 300 to 800 nm at a high speed with a slit width of 12 nm, and the transmittance was displayed at 550 nm.
In the measurement, the value when the measurement was performed with the sample fixed to the sample fixing device so that the main diffusion direction of the sample was horizontal was used. The main diffusion direction was determined by applying light to the sample with a laser marker and detecting the diffusion direction of the emitted light.
In actual use, the deviation between the axis of the sample stage and the axis in the main diffusion direction is allowed up to about 20 degrees.
When the surface roughness differs between the two surfaces of the sample, it is better to measure by fixing the sample in the direction in which the light transmission direction in actual use matches. In the present invention, the measurement was carried out with the surface being fixed in the direction in which light enters from the lower surface roughness.

6). Front brightness reduction RISA-COLOR / ONE-II (manufactured by Highland) was used for measurement. A commercially available VA type liquid crystal display device is installed horizontally on the pedestal and 131 x 131 mm in the center of this panel.
Size white image (Nokia monitor test for windows
V 1.0 (Nokia's Farbe mode) is displayed, drop 3 drops of water on the white image with a dropper, and place a sample film on it to evenly distribute the water between the panel and the film. The CCD camera was fixed at a position 1 m in the vertical direction from the display surface, and the luminance was measured under the following conditions. The obtained luminance was defined as Is.
On the other hand, the luminance of the panel itself without the sample film was measured by the same method.
The calculated luminance was set to Ib, the front luminance reduction was calculated by the following formula (1), and the front luminance reduction was displayed in%.
Decrease in luminance = (Ib−Is / Ib) × 100 (%) (1)
The brightness was obtained by dividing the white image into 25 parts of 5 × 5, measuring the brightness of all the pixels of 9 parts of 3 × 3 at the center, and displaying the average value.
In addition, the sample film was installed and measured such that the main diffusion direction was substantially parallel to the horizontal (horizontal) direction of the panel.

7). Viewing angle improvement effect RISA-COLOR / ONE-II (manufactured by Highland) was used for measurement. A commercially available VA type liquid crystal display device is installed horizontally, and a white image (Nokia monitor test for windows V 1 in the size of 131 × 131 mm is provided at the center of the panel.
. 0 (manufactured by Nokia)), drop 3 drops of water on the white image with a dropper, and place a viewing angle enhancement film on it to evenly distribute the water between the panel and the film. Widen and close contact, the distance between the CCD camera and the display is 1 m in the vertical state, the CCD camera is moved on the equator between -70 ° and + 70 ° with respect to the panel surface of the liquid crystal display device, and the following conditions Then, the angle dependency of the x value of the YIE system of the CIE color system is measured, and the x value (x70) at 70 degrees is obtained from the x value (x0) at 0 degrees with respect to the perpendicular, and Δx ( 70 degrees) = x0−x70.
For the x value, the white image was divided into 25 parts of 5 × 5, and the luminance of all the pixels of 9 parts of 3 × 3 at the center was measured and displayed as an average value.
In addition, the sample film was installed and measured such that the main diffusion direction was substantially parallel to the horizontal (horizontal) direction of the panel.
In addition, when evaluating the viewing angle improvement effect in the horizontal (horizontal) direction of the screen of the liquid crystal display device, the liquid crystal display was installed so that the horizontal direction of the liquid crystal screen was the equator direction. On the other hand, when evaluating the viewing angle improvement effect of the liquid crystal display device in the vertical (vertical) direction of the screen, the liquid crystal display was installed so that the vertical (vertical) direction of the liquid crystal screen was the equator direction.

8). Adhesiveness From the block polyisocyanate crosslinking agent and organotin compound obtained by polymerizing the polyvinyl alcohol polymer aqueous solution having a saponification degree of 74 mol% adjusted to a solid content concentration of 5% by mass on the surface of the viewing angle improving film by the following method. In the wire bar so that the thickness of the polyvinyl alcohol polymer layer after drying is 5 μm. It was applied and dried at 70 ° C. for 5 minutes. As the polyvinyl alcohol polymer aqueous solution, a solution in which a red dye was added so as to facilitate the determination was used. The prepared sample for evaluation was attached to a glass plate having a thickness of 5 mm to which a double-sided tape was attached, and the opposite surface of the evaluation sample on which the polyvinyl alcohol polymer layer was formed was attached to the double-sided tape. Next, 100 grid-like cuts that penetrated the polyvinyl alcohol polymer layer and reached the base film were made using a cutter guide having a gap interval of 2 mm. Then, an adhesive tape (Nichiban Co., Ltd. cello tape (registered trademark) CT-24; 24 mm width) was attached to the grid-shaped cut surface. The air remaining at the interface at the time of pasting was pushed with an eraser to bring it into close contact, and then the adhesive tape was peeled vertically and vigorously peeled once. The number of squares on which the polyvinyl alcohol polymer layer was not peeled was counted to evaluate the adhesion. The case where the number of the squares from which the polyvinyl alcohol polymer layer was peeled off was 20 or less, and the case where it exceeded 20 was regarded as bad.

(Polymerization of block polyisocyanate crosslinking agent)
In a flask equipped with a stirrer, a thermometer, and a reflux condenser, 100 parts by mass of an aqueous polyisocyanate compound having an isocyanurate structure using hexamethylene diisocyanate as a raw material (manufactured by Asahi Kasei Chemicals, Duranate TPA), 55 parts by mass of propylene glycol monomethyl ether acetate, 30 parts by mass of polyethylene glycol monomethyl ether (average molecular weight 750) was charged and held at 70 ° C. for 4 hours in a nitrogen atmosphere. Thereafter, the reaction solution temperature was lowered to 50 ° C., and 47 parts by mass of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction solution was measured to confirm that the absorption of the isocyanate group had disappeared, and a block polyisocyanate aqueous dispersion having a solid content of 75% by mass was obtained.

Example 1
Using two melt extruders and a first extruder as a base layer, cyclic polyolefin resin (TOPAS (TM) 6013F-04 Topas Advanced Polymers melt flow rate: 2.0 (230 ° C.)) 10 mass And 90 parts by mass of polypropylene resin 2011D (Sumitomo Chemical Co., Ltd., Sumitomo Noblen Melt Flow Rate: 2.5 (230 ° C.)) are kneaded in advance and supplied as a surface layer with a second extruder. Adhesive Resin (Admer (TM) QF570, Mitsui Chemicals, Ltd., Melt Flow Rate: 3.7 (190 ° C.)) and Polypropylene Adhesive Resin (Admer (TM) QE870, Mitsui Chemicals, Melt Flow Rate: 9. 2 (190 ° C)) is kneaded in advance and supplied, and melt coextrusion by the T-die method Then, the viewing angle improving film with a total thickness of 110 μm was obtained by cooling with a satin cooling roll. The outlet temperatures were 245 and 250 ° C, respectively. Further, the film was adhered to the cooling roll during the cooling by an electrostatic adhesion method. The surface temperature of the cooling roll was set to 20 ° C. The film was wound up at a speed of 3 m / min. Just before winding, corona treatment was performed on both sides. The layer thickness configuration was 10/90/10 (μm).
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this example has a reduction in front luminance within 20%, exhibits a significant viewing angle improving effect, and has excellent adhesiveness with a PVA-based adhesive. It was high quality.
Note that Δx (70 degrees) of the panel itself when the viewing angle improving film is not attached is +0.
016.

(Example 2)
Using two melt extruders and a first extruder as a base layer, a cyclic polyolefin-based resin (TOPAS ™ 6013S-04 Topas Advanced
Polymer copolymer melt flow rate: 2.0 (230 ° C.) 35 parts by mass and block copolymer resin consisting of ethylene and octene (Dow Chemical INFUSE (TM) D9817.15 Melt flow rate: 26 (230 ° C.) ) 65 parts by mass kneaded in advance and supplied as a surface layer using a second extruder, polypropylene adhesive resin (Admer (TM) QF551, Mitsui Chemicals, Ltd., melt flow rate: 5.7 (190 ° C.)) )), Melt coextruded by a T-die method, and cooled with a satin cooling roll to obtain a 56-μm thick viewing angle improving film. The film was adhered to the cooling roll at the time of cooling using a vacuum chamber. The first extruder and the second extruder were both uniaxial, and the outlet temperatures were 230 and 250 ° C., respectively. The surface temperature of the cooling roll was set to 50 ° C. The film was wound up at a speed of 21 m / min. The layer thickness configuration was 8/40/8 (μm).
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this example was higher in quality than the viewing angle improving film obtained in Example 1 with less reduction in front luminance.

(Example 3)
In the method of Example 2, the film thickness and the layer thickness constitution were 40 μm and 6/28/6 (
μm), a viewing angle improving film was obtained in the same manner as in Example 2 except that both the outlet temperatures of the extruder were changed to 270 ° C. and the winding speed was changed to 18 m / min.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this example was excellent in both the viewing angle improving effect and the front luminance reduction, and was high quality.

Example 4
Using two melt extruders and a first extruder as a base layer, a cyclic polyolefin resin (TOPAS (TM) 5013S-04 Topas Advanced)
Polymer copolymer melt flow rate: 8.6 (230 ° C.) 50 parts by mass, block copolymer resin composed of ethylene and octene (Dow Chemical Co. INFUSE (TM)
) D9100.15 Melt flow rate: 2.4 (230 ° C.)) 50 parts by mass were supplied, and as a surface layer, polypropylene resin 2011D (Sumitomo Chemical Co., Ltd., Sumitomo Noblene melt flow rate: 2. 5 (230 ° C.), melt coextrusion by the T-die method, and cooling with a mirror-cooled roll, the thickness is 115 μm, and the layer thickness is 30/5
A 5/30 (μm) viewing angle improving film was obtained. The film was adhered to the cooling roll at the time of cooling using a vacuum chamber. The first extruder was a biaxial system, and the second extruder was a uniaxial system. The outlet temperature was 250 ° C. for both extruders. The surface temperature of the cooling roll was set to 20 ° C. The film was wound up at a speed of 3.0 m / min.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improvement film obtained in this example was slightly inferior to the viewing angle improvement film obtained in Example 1, but the front luminance reduction was small and high quality.

(Example 5)
In the method of Example 2, the outlet temperatures of the first extruder and the second extruder were 250 and 230 ° C., respectively, except that the surface of the cooling roll was changed to a satin surface and the winding speed was changed to 15 m / min. A viewing angle improving film was obtained in the same manner as described above.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improvement film obtained in this example was slightly worse in front luminance than the viewing angle improvement film obtained in Example 2, but the viewing angle improvement effect was improved.

(Example 6)
In the method of Example 2, the resin compound composition supplied to the first extruder was a cyclic polyolefin resin (TOPAS (TM) 6013F-04 Topas Advanced Polymers melt flow rate: 2.0 (230 ° C.)). Implementation was performed except that the blending ratio of polypropylene resin 2011D (Sumitomo Chemical Co., Ltd., Sumitomo Nobrene melt flow rate: 2.5 (230 ° C.)) was 35 parts by mass and 65 parts by mass, respectively, and the thickness of the base layer was changed to 30 μm. A viewing angle improving film was obtained in the same manner as in Example 1.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this example is less effective in improving the viewing angle than the viewing angle improving film obtained in Example 1, but the front luminance reduction is improved.

(Example 7)
A viewing angle improving film was obtained in the same manner as in Example 1 except that the thickness of the base layer was changed to 60 μm by the method of Example 1.
Table 1 shows the characteristics of the obtained viewing angle improving film.
Although the viewing angle improvement film obtained in the present example has a lower front luminance than the viewing angle improvement film obtained in Example 1, the effect of improving the viewing angle is reduced.

(Example 8)
In Example 2, the resin composition supplied to the first extruder was a cyclic polyolefin resin (TOPAS (TM) 6013S-04 Topas Advanced Polymer).
rs melt flow rate: 2.0 (230 ° C.) 20 parts by mass, block copolymer resin composed of ethylene and octene (INFUSE (TM) D9817 manufactured by Dow Chemical Co., Ltd.)
. 15 Melt flow rate: 26 (230 ° C.) Viewing angle improving film in the same manner as in Example 2 except that the film thickness and layer thickness constitution are changed to 108 μm and 24/60/24 (μm) to 80 parts by mass. Got.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this example was excellent in both the viewing angle improving effect and the front luminance reduction, and was high quality.

Example 9
In the method of Example 2, the resin composition supplied to the first extruder was a cyclic polyolefin-based resin (TOPAS (TM) 6013S-04 Topas Advanced).
Polymer copolymer melt flow rate: 2.0 (230 ° C.) 10 parts by mass and block copolymer resin consisting of ethylene and octene (Dow Chemical Co. INFUSE (TM)
) D9817.15 Melt flow rate: 26 (230 ° C.)) Field of view in the same manner as in Example 2 except that the thickness was changed to 108 μm and the layer thickness configuration to 24/60/24 (μm). A corner enhancement film was obtained.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle enhancement film obtained in this example had the same characteristics as the viewing angle enhancement film obtained in Example 2 and was of high quality.

(Example 10)
In the method of Example 2, a viewing angle improving film was obtained in the same manner as in Example 2 except that the thickness was changed to 84 μm and the layer thickness configuration was changed to 12/60/12 (μm).
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this example had a higher front angle reduction than the viewing angle improving film obtained in Example 2, but the viewing angle improving effect was improved and the quality was high.

(Comparative Example 1)
In the method of Example 1, a viewing angle improving film was obtained in the same manner as in Example 1 except that the thickness of the base layer was 30 μm.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example had a little reduction in front luminance, but had a small viewing angle improving effect and poor viewing angle improving characteristics.

(Comparative Example 2)
In the method of Example 6, a viewing angle improving film was obtained in the same manner as in Example 6 except that the thickness of the base layer was changed to 150 μm.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example has a good viewing angle improving effect, but has a large reduction in front luminance and poor viewing angle improving characteristics.

(Comparative Example 3)
10 parts by mass of cyclic polyolefin resin (TOPAS (TM) 6013F-04 Topas Advanced Polymers melt flow rate: 2.0 (230 ° C.)) and polypropylene resin 2011D (Sumitomo Chemical Co., Ltd., Sumitomo Nobrene melt flow rate: 2. 5 (230 ° C.)) 90 parts by mass is melt-mixed at a resin temperature of 250 ° C. using a PCM45 extruder manufactured by Ikekai Tekko Co., Ltd., extruded with a T-die, and cooled with a mirror-like cooling roll to obtain a 90 μm thick field of view. A corner enhancement film was obtained. The film was adhered to the cooling roll during the cooling by an electrostatic adhesion method. The surface temperature of the cooling roll was set to 20 ° C. The film was wound up at a speed of 3 m / min. Just before winding, corona treatment was performed on both sides.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example has the same viewing angle improving property as that of Example 1, but has poor adhesion to the PVA adhesive.

(Comparative Example 4)
In the method of Example 1, a viewing angle improving film was obtained in the same manner as in Example 1 except that the resin supplied to the second extruder was changed to polypropylene resin (Sumitomo Chemical Co., Ltd., Sumitomo Nobrene FS2011DG3). .
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example was inferior in quality with respect to the PVA adhesive and was low in quality.

(Comparative Example 5)
In the method of Example 2, a viewing angle improving film is obtained in the same manner as in Example 1 except that the resin supplied to the second extruder is changed to the same compound as the resin compound supplied to the first extruder. It was.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example was inferior in quality with respect to the PVA adhesive and was low in quality.

(Comparative Example 6)
In the method of Example 9, a viewing angle improving film was obtained in the same manner as in Example 9 except that the thickness was changed to 28 μm and the layer thickness configuration was changed to 6/16/6 (μm).
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example had a low front luminance, but the effect of improving the viewing angle was poor and the quality was low.

(Comparative Example 7)
A viewing angle improving film was obtained in the same manner as in Example 5 except that the thickness was changed to 175 μm and the layer thickness configuration was changed to 25/125/25 (μm) by the method of Example 2.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example has a good viewing angle improving effect, but has a large reduction in front luminance and low quality.

(Comparative Example 8)
In the method of Example 9, a viewing angle improving film was obtained in the same manner as in Example 9 except that the total film thickness was changed to 216 μm and the layer thickness configuration was changed to 48/120/48 (μm).
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example has a good viewing angle improving effect, but has a large reduction in front luminance and low quality.

(Comparative Example 9)
Polypropylene resin (Sumitomo Chemical Co., Ltd., Sumitomo Nobrene FS2011DG3) 50 parts by mass, ethylene butene copolymer (Mitsui Chemicals, Tuffmer A0585X) 30 parts by mass and nanocrystal structure control type polyolefin elastomer resin (Mitsui Chemicals, Notio P
N3560) A kneaded polyolefin resin composition obtained by melt-extruding 20 parts by mass with a biaxial extruder in advance at a resin temperature of 240 ° C. in a 60 mmφ single screw extruder (L / D; 22). After melt mixing and extruding with a T-die, the unstretched sheet was obtained by cooling with a 20 ° C. casting roll. Next, this unstretched sheet was stretched 4.5 times at a stretching temperature of 118 ° C. using the difference in roll peripheral speed of a longitudinal stretching machine, and further stretched 8.2 times at 145 ° C. in the transverse direction at 158 degrees. Heat set. Next, corona treatment was applied to one side to obtain a thickness of 25μ
m light diffusion film was obtained.
The viewing angle improving film obtained in this comparative example had a low front luminance, but the effect of improving the viewing angle was poor and the quality was low.

(Comparative Example 10)
Using two melt extruders, supplying 100 parts by mass of polypropylene resin WF836DG3 (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Nobrene) as the A layer of the base material layer using the first extruder, as the B layer of the diffusion layer, In the second extruder, 17 parts by mass of polypropylene resin WF836DG3 (Sumitomo Chemical Co., Ltd., Sumitomo Nobrene) and 83 parts by mass of propylene / ethylene copolymer HF3101C (Nippon Polypro Co., Ltd.) were supplied. Thus, after melt coextrusion by the T-die method, the unstretched sheet was obtained by cooling with a 20 ° C. casting roll. Next, this unstretched sheet was stretched 4.8 times at a stretching temperature of 120 ° C. using the difference in roll peripheral speed of a longitudinal stretching machine, and subsequently, 165 ° C. by a tenter-type stretching machine.
After heating, the film was stretched 9 times in the transverse direction at a stretching temperature of 155 ° C. Subsequently, the film was heat-set at 166 ° C. to obtain viewing angle improving films in which the thicknesses of the A layer and the B layer were 22.2 μm and 2.8 μm, respectively. The corona treatment was performed on the surface of the base layer A immediately before winding.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example had a low front luminance, but the effect of improving the viewing angle was poor and the quality was low.

(Comparative Example 11)
Highly transparent polyester film with a thickness of 100 μm (Cosmo Shine A4 manufactured by Toyobo Co., Ltd.)
300) on one side, a mixed part of 50 parts by mass of spherical acrylic resin particles (Toughtick (TM) FH-S300 manufactured by Toyobo Co., Ltd.) having an average particle diameter of 3 μm and a polyurethane resin of 50 parts by mass has a thickness of 30 μm after drying. Thus, the viewing angle improvement film was obtained by apply | coating and drying using a coating machine.
Table 1 shows the characteristics of the obtained viewing angle improving film.
The viewing angle improving film obtained in this comparative example has a good viewing angle improving effect, but has a large reduction in front luminance and low quality.

(Example 11 and Example 12)
An anti-reflection type protective film for display manufactured by Kureha Elastomer Co., Ltd. was attached to one side of the viewing angle improving film used in Examples 1 and 2 to obtain a viewing angle improving film composite in which a reflection reducing layer was combined. . The main diffusion direction is formed on the surface of a commercially available VA liquid crystal display device of the same type as that used in Examples 1 to 10 with the double-sided adhesive tape for optical use so that the reflection-reducing layer is on the viewing side. The liquid crystal display device was attached so as to be in a substantially horizontal (horizontal) direction, and the effect of improving the viewing angle and the reduction in front luminance were evaluated.
Results equivalent to those in Examples 1 and 2 were obtained. Furthermore, since an antireflection effect is added, even when the liquid crystal panel is observed in a bright environment, the viewing angle improvement effect is not reduced. In addition, even when used in a place where external light is reflected, since the reflection of external light is suppressed, the visibility of the image is improved.

(Example 13 and Example 14)
An anti-glare type protective film for display manufactured by Kureha Elastomer Co., Ltd. was attached to one side of the viewing angle improving film used in Examples 1 and 2, and a reflection reducing layer was combined to obtain a viewing angle improving film composite. The main diffusion direction is formed on the surface of a commercially available VA liquid crystal display device of the same type as that used in Examples 1 to 10 with the double-sided adhesive tape for optical use so that the reflection-reducing layer is on the viewing side. The liquid crystal display device was attached so as to be in a substantially horizontal (horizontal) direction, and the effect of improving the viewing angle and the reduction in front luminance were evaluated.
Results equivalent to those in Examples 1 and 2 were obtained. Furthermore, since an antireflection effect is added, even when the liquid crystal panel is observed in a bright environment, the viewing angle improvement effect is not reduced. In addition, even when used in a place where external light is reflected, since the reflection of external light is suppressed, the visibility of the image is improved.

(Example 15 and Example 16)
In Examples 11 and 12, the sticking direction of the main diffusion direction film was changed so that the main diffusion direction of the viewing angle improving film was substantially the vertical (vertical) direction of the panel. The effect of improving the viewing angle in the vertical direction of the panel image was developed.

(Example 17 and Example 18)
The liquid crystal display device is changed to the TN type using the viewing angle improving film obtained in the method of Example 1 and Example 2, and the main diffusion direction is an abbreviation of the liquid crystal display device in each of the attaching directions of the viewing angle improving film. Adhering with a double-sided adhesive tape for optics so as to be in the horizontal (horizontal) direction, the effect of improving the viewing angle in the horizontal (horizontal) direction and the reduction in front luminance were evaluated.
The results are shown in Table 2.

(Example 19 and Example 20)
In the methods of Examples 17 and 18, the viewing angle improving film was attached in the substantially vertical (vertical) direction, and the vertical (vertical) viewing angle improvement effect and front luminance reduction were evaluated.
The results are shown in Table 2.

(Comparative Example 12 and Comparative Example 13)
In the methods of Example 17 and Example 18, except that the films attached to the liquid crystal display devices are changed to use the films obtained in Comparative Example 1 and Comparative Example 7, respectively, Example 17 and Example 18 The results of evaluation in the same manner are shown in Table 2.

(Comparative Example 14 and Comparative Example 15)
In the methods of Example 19 and Example 20, Example 19 and Example 20 except that the film adhered to the liquid crystal display device is changed to use the film obtained in Comparative Example 1 and Comparative Example 7, respectively. Table 2 shows the results evaluated in the same manner as above.

(Reference Example 1)
Table 2 shows the x value (x70) of a TN type liquid crystal display device itself to which an anisotropic light diffusion film is not attached.

From Table 2, the following can be said.
With respect to the horizontal (horizontal) direction, the use of the viewing angle improving film of the present invention can improve viewing angle characteristics in a manner that suppresses a decrease in front luminance as in the case of a VA type liquid crystal display device.
In the vertical (vertical) direction, the improvement effect differs between the observation from the upper side and the observation from the lower side. Viewing from the lower direction is less effective than the horizontal (horizontal) direction, but can improve viewing angle characteristics. However, the effect of improving the viewing angle characteristics when observed from above is negligible. In the observation from the upper side, it is assumed that the difference in behavior is caused by the superior viewing angle characteristics of the liquid crystal display device compared to the observation from the lower side and the observation in the horizontal (horizontal) direction. Yes.
In the TN type liquid crystal display device, the magnitude of color tone inversion is considered to be important. Although the above-described effect of the color shift in the upward direction is slight, the color tone reversal property is markedly improved in any direction including the upward direction in the viewing angle improving film of the present invention. Therefore, it can be said that the viewing angle characteristic improving method of the present invention is also effective for a TN type liquid crystal display device.

(Example 21 and Example 22)
In the adhesive evaluation method, the viewing angle improving film obtained in Examples 1 and 2 is applied to one side of the polarizing plate made of PVA and iodine, respectively, so that the absorption axis of the polarizing film and the main diffusion direction of the viewing angle improving film are perpendicular to each other. The film was laminated with the described PVA adhesive to obtain a viewing angle improving film laminate. A TAC film (manufactured by FUJIFILM Corporation, thickness 80 μm) was attached to the opposite surface of the laminate to the viewing angle improving film to prepare a polarizing plate.
The polarizing plate on the upper surface side of the panel of the commercially available VA type liquid crystal display device was peeled off and changed to the polarizing plate, and the viewing angle improvement effect and the front luminance reduction were evaluated.
Results equivalent to those in Examples 1 and 2 were obtained.

(Example 23 and Example 24)
Adherence of the viewing angle improving films obtained in Examples 1 and 2 on one side of a polarizer composed of PVA and iodine, respectively, so that the absorption axis of the polarizing film and the main diffusion direction of the viewing angle improving film are 45 degrees. The film was laminated with the PVA adhesive described in the evaluation method to obtain a viewing angle improving film laminate. A TAC film (manufactured by FUJIFILM Corporation, thickness 80 μm) was attached to the opposite surface of the laminate to the viewing angle improving film to prepare a polarizing plate.
The polarizing plate on the upper surface side of the panel of a commercially available TN type liquid crystal display device was peeled off and changed to the polarizing plate, and the viewing angle improvement effect and the front luminance reduction were evaluated.
Results equivalent to those of Examples 17 to 20 were obtained.

The viewing angle improving film of the present invention has a light distribution pattern having both characteristics of straight transmission and diffuse transmission, and the wavelength dependence of the emitted light depends on the angle of the emitted light. It is controlled to work effectively for improvement effect and front luminance reduction, so installing it on the viewing side of the liquid crystal cell of the liquid crystal display device has advanced anti-paradox phenomenon of viewing angle improvement effect and suppression of front luminance reduction. Can be balanced at the level. Furthermore, since the viewing angle improving film of the present invention is excellent in adhesiveness with a polarizing plate, it can be easily laminated with a polarizing plate and can be incorporated into a liquid crystal display device as a laminated body with a polarizing plate. Therefore, it is possible to provide a liquid crystal display device in which both the viewing angle improvement effect and the front luminance reduction suppression are compatible. Therefore, the contribution to the industry is great.

Claims (8)

It is a multilayer light diffusing film in which an adhesion improving layer made of a polyolefin resin mainly containing polar groups is laminated on at least one surface of a light diffusing layer made mainly of two types of incompatible polyolefin resins. A viewing angle improving film characterized by simultaneously satisfying the following characteristics:
(1) The half-value width of the light distribution pattern in the main diffusion direction of light having a wavelength of 440 nm measured by the method described in the specification is 18 degrees or less;
(2) Ratio of transmittance (I0) at an exit angle of 0 ° and transmittance (I30) at an exit angle of 30 ° (I30 / I) in the main diffusion direction measured by the method described in the specification
I0 × 100) is 0.25 to 5.5%.   The viewing angle improving film according to claim 1, wherein the degree of anisotropy measured by the method described in the specification is 2.0 or more. The viewing angle improving film according to claim 1, wherein at least one of the incompatible resins is a polyolefin resin. The viewing angle improving film according to claim 3, wherein the two types of incompatible resins are polyolefin resins. The viewing angle improving film according to claim 3 or 5, wherein the polyolefin resin is selected from any one of a polyethylene resin, a polypropylene resin, and a cyclic polyolefin resin.   A viewing angle improving film laminate comprising the viewing angle improving film according to any one of claims 1 to 5 laminated on a polarizing plate surface.   The viewing angle improving film laminate according to claim 6, wherein the lamination is performed via an adhesive. A liquid crystal display device comprising at least a backlight device and a liquid crystal cell, wherein the viewing angle improving film laminate according to claim 6 or 7 is used as a polarizer of the liquid crystal cell.