JP2000275437A - Optical film, optical member and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical optical film excellent in scattering anisotropy with respect to linearly polarized light, being easy to be manufactured, and being excellent in thermal stability, and an optical element using the same. SOLUTION: An optical film 1 comprises a resin film containing microareas (e) in a dispersed fashion, which microareas consist of a polymer liquid crystal with a polymerization degree of 8 or more, and differences Δn1, Δn2 in refractive index between the microareas and other portions are 0.03 or more (Δn1) in a direction perpendicular to an axial direction in which the maximum transmission of linear polarization is shown, and are 50% or less (Δn2) of Δn1 in the axial direction of the maximum transmission. An optical element comprises at least either one of a polarizing plate or a phase difference plate and a laminate having one or two or more layers of the optical films. Thus, a heat- resistant liquid-crystal display device can be obtained which provides linearly polarized light that shows scattering anisotropy such that it is scattered in the direction of Δn1 and transmitted in the direction of Δn2, and which absorbs little light so that it is excellent in brightness and visibility as well as in thermal stability of optical functions, so that it can be put to practical use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical film and an optical element having excellent scattering anisotropy and thermal stability of linearly polarized light and suitable for improving visibility, luminance, durability and the like of a liquid crystal display device.

[0002]

BACKGROUND OF THE INVENTION Conventionally, an optical film exhibiting scattering anisotropy with respect to linearly polarized light by dispersing a region having a refractive index anisotropy in a base material is composed of a combination of a thermoplastic resin and a low-molecular liquid crystal. Those comprising a combination of a low-molecular liquid crystal and a photocrosslinkable low-molecular liquid crystal, those comprising a combination of a polyester and an acrylic resin or polystyrene, and those comprising a combination of a polyvinyl alcohol and a low-molecular liquid crystal were known. (USP 212390, WO 87/01822, EP 050617, WO 97/32224, WO 97/41484, Japanese Patent Application Laid-Open No. 9-2741.
08 publication).

[0003] The above optical film is expected to improve the visibility and luminance of a liquid crystal display device and the like by a polarization separation function and a light diffusion function based on scattering anisotropy with respect to linearly polarized light. However, the conventional optical film has a problem that its production is complicated and has poor practical stability such as heat resistance.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to develop a practical optical film which has excellent scattering anisotropy with respect to linearly polarized light, can be easily manufactured and has excellent thermal stability, and an optical element using the same. And

[0005]

According to the present invention, there is provided a resin film in which a minute region composed of a polymer liquid crystal having a degree of polymerization of 8 or more is dispersed and contained, and a refractive index difference between the minute region and another portion is {n1,}.
n2 is 0.03 or more (△ n1) in a direction orthogonal to the axial direction showing the maximum transmittance of linearly polarized light, and 50% or less of the △ n1 (△ n2) in the axial direction of the maximum transmittance. And an optical element comprising a laminate having at least one of a polarizing plate and a retardation plate, and one or more layers of the optical film.

[0006]

According to the optical film of the present invention, in the axial direction (Δn2 direction) showing the maximum transmittance of linearly polarized light, linearly polarized light is transmitted while maintaining its polarization state in a good condition, and is orthogonal to the Δn2 direction. In the direction (Δn1 direction), linearly polarized light is scattered based on the refractive index difference Δn1 between the resin film and the minute region, and the polarization state is relaxed or eliminated, and excellent scattering anisotropy is exhibited.

Further, the resin film is made of a resin film containing a polymer-based microregion having a degree of polymerization of 8 or more in a dispersed state. The microfilm has excellent handleability, is easy to manufacture an optical film, and has excellent uniformity. The obtained optical film shows excellent thermal stability, and has excellent stability of optical functions and excellent practicality. By the way, it is possible to form a material having no change in optical characteristics such as appearance and scattering even at a high temperature of 80 ° C. or higher.

As a result, loss and heat generation due to light absorption can be prevented based on the polarization characteristics and the like due to the scattering anisotropy.
In addition, a liquid crystal display device which is excellent in luminance and visibility based on good heat resistance, has excellent thermal stability of optical functions, and has sufficient heat resistance for practical use can be obtained.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The optical film according to the present invention is composed of a resin film in which minute regions composed of high-molecular liquid crystal having a degree of polymerization of 8 or more are dispersed and contained, and the refractive index difference Δn1, between the minute regions and other parts, Δn2 is 0.03 or more (Δn) in the direction orthogonal to the axial direction showing the maximum transmittance of linearly polarized light.
1) and in the axial direction of the maximum transmittance,
0% or less (△ n2). Figure 1 shows an example
It was shown to. 1 is an optical film, and e is its minute area. Reference numeral 2 denotes an adhesive layer formed of an adhesive layer for adhering to the adherend, and reference numeral 21 denotes a separator for temporarily covering the adhesive layer.

The optical film is formed, for example, by mixing one or more of a resin for forming a resin film and one or more of a liquid crystal polymer for forming a fine region, It can be carried out by a method of forming a resin film containing liquid crystal dispersedly in a fine region, orienting it by an appropriate method, and forming regions having different birefringence characteristics.

As the resin forming the resin film, any suitable resin having excellent light transmittance, particularly, excellent light transmittance can be used, and there is no particular limitation. Accordingly, heat resistance and the like can be set as appropriate. Incidentally, examples of the resin include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, styrene resins such as polystyrene and acrylonitrile-styrene copolymer, polyethylene and polypropylene, and polyolefin and ethylene having a cyclo or norbornene structure.
An olefin resin such as a propylene copolymer can be used.

Acrylic resins such as polymethyl methacrylate, cellulose resins such as cellulose diacetate and cellulose triacetate, amide resins such as nylon and aromatic polyamide, carbonate resins, vinyl chloride resins, imide resins, and the like. Sulfone resins, polyethersulfone resins and polyetheretherketone resins, polyphenylene sulfide resins and vinyl alcohol resins, vinylidene chloride resins and vinyl butyral resins,
Allylate-based resins, polyoxymethylene-based resins, and blends thereof are also examples of the above-mentioned resins.

The resin which can be preferably used from the viewpoint of heat resistance and the like has a weight deflection temperature of 80 ° C. or more and a glass transition temperature of 110 ° C. or more, especially 115 ° C. or more, particularly 120 ° C. or more. When used in a liquid crystal display device or the like, a resin having excellent light transmittance in a visible light region can be preferably used. The weight deflection temperature described above is JIS K 720
While applying a bending stress of 18.5 kgf / cm ² to a test piece having a height of 10 mm in a heating bath, the heat transfer medium was heated at a rate of 2 ° C./min according to the method described in No. 7, and the deflection of the test piece was reduced to 0.32 mm. It is defined by the temperature of the heat transfer medium when it is reached.

On the other hand, as the high-molecular liquid crystal forming the minute region, an appropriate liquid crystal polymer such as a main chain type or a side chain type having a degree of polymerization of 8 or more can be used, and the type thereof is not particularly limited. In a liquid crystal having a degree of polymerization of less than 8, when mixed with a resin for forming a film, a minute region formed has a large variation, and the particle size distribution becomes wide, resulting in poor uniformity of optical characteristics.

The degree of polymerization of the high-molecular liquid crystal which can be preferably used from the viewpoints of the formability of a uniform particle size distribution of the fine regions, the thermal stability, the moldability into a film, and the ease of alignment treatment is as follows.
0 or more, especially 120,000 to 10000, especially 15 to 2000.

The refractive index difference Δn ¹ ,
△ n from the viewpoint of the ^second controllability has a glass transition temperature of 50
Those exhibiting a nematic liquid crystal phase in a temperature range lower than the glass transition temperature of the resin forming the combined resin film at a temperature of at least ° C can be preferably used. Incidentally, specific examples thereof include a side chain type liquid crystal polymer having a monomer unit represented by the following general formula.

General formula:

In the above general formula, X is a skeletal group forming the main chain of the liquid crystal polymer, and may be formed by an appropriate connecting chain such as linear, branched or cyclic. Incidentally, examples thereof include polyacrylates and polymethacrylates, poly-α-haloacrylates and poly-α-cyanoacrylates, polyacrylamides and polyacrylonitriles, polymethacrylonitriles and polyamides, polyesters and Examples include polyurethanes, polyethers, polyimides, and polysiloxanes.

Y is a spacer group branched from the main chain, and a preferable spacer group Y from the viewpoint of forming an optical film such as controlling the refractive index is, for example, ethylene, propylene, butylene, pentylene, hexylene and the like. , Especially ethylene.

On the other hand, Z is a mesogenic group for imparting nematic orientation, and examples thereof include the following compounds.

The terminal substituent A in the compound may be, for example, a cyano group, an alkyl group, an alkenyl group, an alkoxy group, an oxaalkyl group, a haloalkyl group in which at least one of hydrogen is substituted by fluorine or chlorine, a haloalkoxy group, It may be an appropriate one such as a haloalkenyl group.

In the above, the spacer group Y and the mesogen group Z may be bonded via an ether bond, that is, via —O—. In the phenyl group in the mesogen group Z, one or two hydrogens may be substituted with a halogen. In this case, the halogen is preferably chlorine or fluorine.

The nematic alignment side chain type liquid crystal polymer may be any suitable thermoplastic resin such as a homopolymer or a copolymer having a monomer unit represented by the above general formula. Excellent ones are preferred.

In the formation of the optical film using the nematic-oriented polymer liquid crystal, for example, a resin for forming a resin film and a glass exhibiting a nematic liquid crystal phase in a temperature range lower than the glass transition temperature of the resin are used. A polymer liquid crystal having a transition temperature of 50 ° C. or higher, particularly 60 ° C. or higher, particularly 70 ° C. or higher is mixed to form a resin film containing the polymer liquid crystal dispersed in a fine region, and then the fine region is formed. The polymer liquid crystal to be formed can be subjected to a heat treatment to align the liquid crystal in a nematic liquid crystal phase, and the alignment state can be fixed by cooling.

The combination of the resin for forming the resin film and the polymer liquid crystal used in the above is a combination in which the materials are not completely compatible with each other in view of the dispersion distribution of the minute regions in the obtained optical film. It is preferable to use a combination for separation. The dispersion distribution can be controlled by the compatibility of the combination. The phase separation can be performed by an appropriate method such as a method in which an incompatible material is made into a solution with a solvent or a method in which the materials are mixed while heating and melting.

The formation of a resin film containing a polymer liquid crystal dispersed in a minute area, ie, a film to be subjected to an alignment treatment, is performed by, for example, a casting method, an extrusion molding method, an injection molding method, a roll molding method, a casting method, or the like. It can be obtained by an appropriate method, and can also be applied to a method of developing in a monomer state, polymerizing it by a heat treatment or a radiation treatment such as ultraviolet rays, and forming a film.

From the viewpoint of obtaining an optical film having excellent uniform distribution of minute regions, a method of forming a mixed solution of a forming material through a solvent by a casting method, a casting method, or the like is preferable. In this case, the size and distribution of the minute region can be controlled by the type of the solvent, the viscosity of the mixed solution, the drying speed of the mixed solution developing layer, and the like. Incidentally, in order to reduce the area of the minute region, it is advantageous to lower the viscosity of the mixed liquid and to increase the drying rate of the mixed liquid developing layer.

The thickness of the film to be subjected to the orientation treatment can be determined as appropriate, but is generally 1 μm
３3 mm, especially 5 μm to 1 mm, especially 10 to 500 μm. In forming the film, for example, appropriate additives such as a dispersant, a surfactant, an ultraviolet absorber, a color tone adjuster, a flame retardant, a release agent, and an antioxidant can be blended.

In the alignment treatment, for example, the polymer liquid crystal dispersed and distributed as fine regions in the resin film is heated and melted to a temperature at which a desired liquid crystal phase such as a nematic phase is exhibited. Then, rapid cooling is performed to fix the alignment state. The orientation state is preferably in a mono-domain state as much as possible from the viewpoint of preventing variations in optical characteristics.

The above-mentioned alignment regulating force may be, for example, a stretching force by a method of stretching a resin film at an appropriate magnification, a sharing force at the time of film formation, an electric field or a magnetic field, etc. It is possible to apply the one or more kinds of restricting force to perform the alignment treatment of the polymer liquid crystal.

Therefore, the portion of the optical film other than the microscopic region composed of the liquid crystal polymer may exhibit birefringence or may be isotropic. The entire optical film having birefringence can be obtained by the molecular orientation or the like in the film forming process described above by using an orientation birefringent resin for the film forming resin, and if necessary, for example, a stretching treatment or the like. The birefringence can be imparted or controlled by adding known orientation means. In addition, an optical film having an isotropic portion other than the minute region is, for example, a method of using an isotropic resin for forming a film and stretching the film in a temperature region equal to or lower than the glass transition temperature of the resin. Can be obtained by

In the optical film according to the present invention, the refractive index differences Δn1 and Δn2 between the minute region composed of the polymer liquid crystal and the other region, that is, the region composed of the resin film, indicate the maximum transmittance of linearly polarized light in the axial direction. Is controlled to be 0.03 or more (△ n1) in the direction perpendicular to the direction and to 50% or less (△ n2) of the Δn1 in the axial direction of the maximum transmittance. By setting such a refractive index difference,
It can be excellent in scattering in the Δn1 direction and excellent in maintaining the polarization state in the Δn2 direction and in straight transmissivity.

It is preferable that the refractive index difference Δn1 in the Δn1 direction is appropriately large from the viewpoint of scattering properties and the like.
It is preferable that the refractive index difference Δn1 is 4 to 1, especially 0.045 to 0.5. On the other hand, the refractive index difference Δn2 in the Δn2 direction is preferably as small as possible from the viewpoint of maintaining the polarization state, and is preferably 0.03 or less, particularly 0.02 or less, and particularly preferably 0.02 or less.
It is preferable that the refractive index difference Δn2 is 1 or less.

Therefore, the above-mentioned alignment treatment of the minute region is performed by aligning the polymer liquid crystal forming the minute region in a certain direction as much as possible to increase the refractive index difference in the Δn1 direction or in the Δn2 direction. Can be positioned as an operation to reduce the refractive index difference of the two or an operation to achieve both of them.

Therefore, from the viewpoint of achieving the above-mentioned refractive index difference characteristic, the refractive index of the resin forming the resin film matches as much as possible the ordinary light refractive index of the polymer liquid crystal forming the minute area, It is advantageous to form an optical film using a combination of a resin and a polymer liquid crystal having a relationship that is significantly different from the refractive index.

It is preferable that the minute regions in the optical film are dispersed and distributed as uniformly as possible from the viewpoint of homogeneity such as the scattering effect. The size of the minute region, particularly the length in the △ n1 direction, which is the scattering direction, is related to backscattering (reflection) and wavelength dependency. Improvement of light use efficiency and prevention of coloring due to wavelength dependence, prevention of visual obstruction of fine regions or prevention of clear display, and more preferable size of micro regions from the viewpoint of film forming property and film strength, Especially △
The preferred length in the n1 direction is 0.05-500 μm, especially 0.1-250 μm, especially 1-100 μm. The minute region is usually present in the optical film in the state of a domain, but the length in the Δn2 direction is not particularly limited.

The proportion of the minute area occupying in the optical film can be appropriately determined in view of the scattering property in the Δn1 direction and the like, but is generally 0.1 to 70 in consideration of the film strength and the like.
% By weight, especially 0.5 to 50% by weight, especially 1 to 30% by weight
It is said.

The optical film according to the present invention can be used as a single layer 1 as illustrated in FIG. 1, or can be used as an optical member in which two or more layers are overlapped. FIG. 2 shows an example of the optical member. 11, 13, 15, and 17 are optical films, and 12, 14, and 16 are adhesive layers.

By superposing such optical films, a synergistic scattering effect more than an increase in thickness can be exhibited. The optical member may be formed by laminating optical films at an arbitrary arrangement angle in the △ n1 direction or the △ n2 direction,
It is preferable that the Δn1 direction is superposed so that the upper and lower layers are in a parallel relationship from each other, for example, from the viewpoint of expansion of the scattering effect. The number of superimposed optical films can be an appropriate number of two or more layers.

The optical film to be superimposed is Δn1 or Δn
2 may be the same or different. The parallel relationship between the upper and lower layers in the Δn1 direction and the like is preferably as parallel as possible, but deviation due to a work error is allowed. If there is variation in the △ n1 direction or the like, it is based on the average direction.

The optical films of the optical members may be simply placed on top of each other. However, the optical films may be provided through an adhesive layer or the like in order to prevent displacement in the Δn1 direction or the like and to prevent foreign substances from entering each interface. Preferably, they are adhered. For the bonding, for example, a suitable adhesive such as a hot melt type or an adhesive type can be used. From the viewpoint of suppressing the reflection loss, an adhesive layer having a refractive index difference as small as possible from the optical film is preferable, and it is also possible to adhere with a resin forming the optical film.

The optical film and the optical member according to the present invention include:
Based on the characteristics showing the transmission and scattering properties of the linearly polarized light, it can be used for various purposes such as forming and controlling polarized light such as a polarizing plate. Incidentally, when used as a polarizing plate, unlike the dichroic absorption polarizing plate, the principle of forming a polarized light is unlikely to absorb light, as described above. Further, there is a possibility that the efficiency of light utilization can be improved by converting the scattered light into polarized light by another optical component or the like and reusing it.

Therefore, when the optical film or optical member according to the present invention is put to practical use, one or two or more layers are formed from a laminate in which one or both of suitable optical components such as a polarizing plate and / or a retardation plate are disposed. It can also be used as an optical element. An example is shown in FIG. 3 is an optical component. Such a laminate may be simply stacked, or may be bonded via an adhesive layer or the like.
The adhesive layer can conform to the case of the above-mentioned superposition of the optical films.

The optical components to be laminated are not particularly limited, and may be, for example, a suitable one such as a backlight such as a polarizing plate, a retardation plate, or a light guide plate, a reflecting plate, a polarized light separating plate composed of a multilayer film, a liquid crystal cell, or the like. It may be. Optical components such as a polarizing plate and a retardation plate may be of various types.

That is, for a polarizing plate, an absorption type, a reflection type, or a scattering type, and for a retardation plate, a 板 wavelength plate or 1
/ 2 wavelength plate, stretched film type with uniaxial or biaxial orientation, tilted film type with molecular orientation in the thickness direction, liquid crystal polymer type, type that compensates for phase difference due to viewing angle or birefringence, laminated There are various types such as the type described above, and any of these types can be used in the present invention.

Incidentally, specific examples of the above-mentioned polarizing plate include iodine and diols on a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene / vinyl acetate copolymer-based partially saponified film. Absorption type polarizing films which are drawn by adsorbing a dichroic substance such as a coloring dye, and polyene oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride are exemplified.

Further, a polarizing plate having a transparent protective layer formed of a plastic coating layer or a film laminating layer on one or both sides of the polarizing film for the purpose of protecting water resistance or the like can also be mentioned. Further, in the transparent protective layer, for example, inorganic fine particles that may be conductive such as silica or alumina, titania or zirconia, tin oxide or indium oxide, cadmium oxide or antimony oxide having an average particle size of 0.5 to 20 μm, Alternatively, a transparent fine particle such as an organic fine particle such as an uncrosslinked polymer may be contained to impart a fine uneven structure to the surface.

On the other hand, specific examples of the retardation plate include a stretched film made of the resin exemplified in the above optical film and a liquid crystal polymer, especially a liquid crystal polymer having a twisted orientation.

Further, as a specific example of the light guide plate, a linear light source such as a (cold or hot) cathode tube or a light source such as a light emitting diode or EL is disposed on a side surface of a transparent resin plate. Light transmitted to one side of the plate by diffusion, reflection, diffraction, interference, or the like may be used.

In forming an optical element including a light guide plate,
A prism array layer composed of a prism sheet or the like for controlling the light emission direction, a diffusion plate for obtaining uniform light emission,
Auxiliary means such as a light source holder for guiding the light emitted from the linear light source to the side surface of the light guide plate may be provided by appropriately arranging one or more layers at predetermined positions such as the upper and lower surfaces and side surfaces of the light guide plate. It can be a combination.

The laminate for forming the optical element according to the present invention may be one using one kind of optical component.
It may use one or more kinds of optical components. Further, for example, two or more layers of the same type of optical component such as a phase difference plate may be laminated, and in this case, the characteristics of the phase difference plate or the like of the optical component may be the same or different. Good. The optical film or the optical member in the optical element has one or two or more layers at appropriate positions inside or outside the laminate such as one or both outer surfaces of the laminate and one or both sides of the optical component forming the laminate. May be arranged.

When the optical element includes a polarizing plate,
The optical film or the optical member is preferably arranged such that the Δn1 direction or the Δn2 direction is parallel to the transmission axis of the polarizing plate from the viewpoint of effectively utilizing the transmission / scattering characteristics of the optical film. . The parallel relationship can be based on the case where the optical films described above are superimposed.

An optical element such as an optical film, which is arranged so that the Δn1 direction and the transmission axis of the polarizing plate are in a parallel relationship, can scatter linearly polarized light transmitted through the polarizing plate through the Δn1 direction of the optical film or the like. . Therefore, for example, the optical element is arranged on the viewing side such that the polarizing plate is on the liquid crystal cell side, which is effective for expanding the viewing angle in a liquid crystal display device or the like.

On the other hand, an optical element such as an optical film having a parallel relationship between the Δn2 direction and the transmission axis of the polarizing plate is capable of scattering linearly absorptive linearly polarized light through the Δn1 direction of the optical film or the like. Can be. Therefore, for example, it is effective to increase the amount of light transmitted through the polarizing plate by disposing the optical element so that light enters the polarizing plate via an optical film or the like.

[0055]

EXAMPLE 1 A 20% by weight dichloromethane solution containing 950 parts (parts by weight, hereinafter the same) of a norbornene resin (ARTON, manufactured by JSR) having a weighted deflection temperature of 165 ° C. and a glass transition temperature of 185 ° C. Is 29 (weight average molecular weight in terms of polystyrene is 12000, glass transition temperature is 8)
(0 ° C., nematic liquid crystal forming temperature: 100 to 290 ° C.) 50 parts of a polymer liquid crystal is dissolved and cast to a thickness of 100 ° C.
A μm resin film was obtained.

The above resin film is obtained by dispersing polymer liquid crystals in a domain form in a film made of a norbornene-based resin. The diameter of the domain was measured by observing a cross section of the film with a scanning electron microscope. .2 to 1.5
μm. Next, the resin film is stretched three times at 180 ° C. and then quenched, so that microscopic regions composed of high-molecular liquid crystal are dispersed and distributed in the birefringent resin film.
An optical film having a refractive index difference Δn1 of 0.230 and Δn2 of 0.029 was obtained.

Example 2 The optical film obtained in Example 1 and a commercially available total light transmittance of 4
An optical element was obtained by bonding a polarizing plate of 1% and having a degree of polarization of transmitted light of 99% via an acrylic adhesive layer having a thickness of 20 μm such that the transmission axis coincides with the Δn1 direction.

Comparative Example 1 A resin film was obtained in the same manner as in Example 1 except that a polymer liquid crystal having a degree of polymerization of 5 (weight average molecular weight in terms of polystyrene of 2,000) was used, and the resulting resin film was stretched to obtain a refractive index difference. An optical film having Δn1 of 0.230 and Δn2 of 0.029 was obtained. The diameter of the domain composed of the polymer liquid crystal in the resin film was in the range of 0.05 to 3 μm, and the particle size distribution was large.

Comparative Example 2 The optical film obtained in Comparative Example 1 and a commercially available total light transmittance of 4
An optical element was obtained by bonding a polarizing plate of 1% and having a degree of polarization of transmitted light of 99% via an acrylic adhesive layer having a thickness of 20 μm so that the transmission axis coincides with the Δn2 direction.

Evaluation Test 1 The optical films obtained in Example 1 and Comparative Example 1
Polarized light parallel or perpendicular to the stretching direction was made incident in an atmosphere of ° C., and the scattering state was visually observed. Further, at room temperature, polarized light parallel or perpendicular to the stretching direction was applied, and the haze was measured with a Poick integrating sphere haze meter according to ASTM D1003-61. The results are shown in the following table. Note that the scattering state in an atmosphere at 90 ° C.
Shown within.

[0061] scattering state f size b parallel vertical parallel vertical Example 1 scattering (scattered) transmission (transmission) 92 9 Comparative Example 1 Scattering (transmission) transmission (transmission) 85 9

As can be seen from the table, in each case, at room temperature, anisotropy in which the scattering characteristics are different depending on the polarization direction is exhibited. In Example 1, the characteristics are favorably maintained even at a high temperature. It can be seen that the anisotropy disappears and the thermal stability is poor. Further, in Comparative Example 1, the haze in the parallel direction was low, and it was found that, even with the same composition, the degree of polymerization of the polymer liquid crystal was large and small, and the formation state of the minute region was changed, thereby affecting the optical characteristics.

Evaluation Test 2 The optical elements obtained in Example 2 and Comparative Example 2 were disposed through the optical film side, and a commercially available iodine-based polarizing plate was disposed adjacent to the light-emitting lens of a projector lamp (metal halide lamp 250W). The change after 300 hours of cumulative irradiation was visually observed. As a result, the commercially available polarizing plate was remarkably reddened and deteriorated to a level unusable for use, and the optical element of Comparative Example 2 was also discolored and significantly deformed. Little change was observed.

From the above results, it can be seen that the optical film and the optical element according to the present invention exhibit strong scattering anisotropy in the polarization direction of the incident linearly polarized light and have excellent thermal stability. It can be expected to improve visibility, brightness, durability and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of an optical film.

FIG. 2 is a cross-sectional view of another example of an optical film.

FIG. 3 is a cross-sectional view of an example of an optical element.

[Explanation of symbols]

 1, 11, 13, 15, 17: optical film e: minute area 2: adhesive layer 3: optical component

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H049 BA02 BA06 BA24 BA25 BA42 BB03 BB16 BB43 BB44 BB45 BB46 BB47 BB48 BB49 BB51 BB62 2H091 FA08X FA08Z FA11X FA11Z FA21Z FA23Z FA50X FA50Z FB02 FC01 FC01 FC23 FC23

Claims (9)

[Claims] 1. A resin film in which minute regions composed of a polymer liquid crystal having a degree of polymerization of 8 or more are dispersed and contained, and the refractive index differences Δn1 and Δn2 between the minute regions and other portions are the maximum transmission of linearly polarized light. 0 in the direction orthogonal to the axial direction indicating the rate.
An optical film characterized by being at least 03 (Δn1) and at most 50% (Δn2) of the Δn1 in the axial direction of the maximum transmittance. 2. The optical film according to claim 1, wherein the fine region is dispersed and contained by phase separation. 3. The method according to claim 1, wherein the 領域
An optical film having a length in the n1 direction of 0.05 to 500 µm. 4. The method according to claim 1 or 2, wherein
An optical film having a length in the n1 direction of 1 to 100 μm. 5. The nematic liquid crystal phase according to claim 1, wherein the polymer liquid crystal forming the minute region has a glass transition temperature of 50 ° C. or higher and a temperature lower than the glass transition temperature of the resin forming the resin film. An optical film that exhibits 6. The optical film according to claim 1, wherein the resin forming the resin film has a glass transition temperature of 110 ° C. or more having a weight deflection temperature of 80 ° C. or more. 7. The optical film according to claim 1, wherein
An optical member comprising a plurality of layers overlapped so that the Δn1 direction is in a parallel relationship between upper and lower layers. 8. An optical element comprising a laminate having at least one of a polarizing plate and a retardation plate and one or more layers of the optical film according to claim 1. Description: 9. The optical element according to claim 8, comprising a polarizing plate, wherein the transmission axis of the polarizing plate and the Δn1 direction or the Δn2 direction of the optical film are in a parallel relationship.