JP2008242430A - Resin composition for optical film, and optical film comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for an optical film having excellent selective transmittance of polarized light, and specifically to provide a resin composition which can be utilized in a polarized light scattering optical member applicable to a device utilizing optical characteristics or a light-utilizing mechanism member which is combined with the optical member. <P>SOLUTION: The resin composition for the optical film is characterized by comprising: 1 to 30 wt.% of at least one kind or more fibrous or columnar particles having an average shorter axis diameter of 1 to 70 nm and an average longer axis diameter of 600 nm to 5 μm; and 70 to 99 wt.% of a transparent resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a resin composition for an optical film excellent in the selective transmission of polarized light, and in detail, a combination of the same member and a polarization-scattering optical member that can be used for equipment using optical characteristics. The present invention relates to a resin composition that can be used for a light utilization mechanism component.

  Conventionally, the technology to obtain a specific polarization is the ordinary light refraction using the method known as Brewster's law that utilizes the demultiplexing of the polarization component of the light by reflection and transmission by the prism as an optical component, or calcite that exhibits birefringence. In addition, there are Glan-Foucult polarizers and Glan-Thomson polarizers that demultiplex the polarization component by extraordinary light refraction, and Wollaston prisms that can split and emit two polarization components by combining a prism and a birefringent element. Beam splitters are known. In addition, light absorbing polarizers using a dichroic material that absorbs only a specific polarization component of light components and transmits a polarization component orthogonal thereto can be used for polarizing plates such as liquid crystal displays. Are known.

  When considering the use of these polarizers as a display having a display function in a large area, conventional glass polarizers are difficult to increase in size and thickness and cannot be used. Therefore, a polarizing film in which an iodine compound or an organic dye is dispersed and oriented in a resin film is used as a dichroic material that absorbs specific polarized light in a state where molecules are oriented.

  However, a polarizer using a dichroic material absorbs a polarized light component parallel to the molecular chain orientation of the dichroic molecule when light is incident, and passes only a polarized light component orthogonal thereto. That is, even if the surface reflection and scattering components of light are ignored, 50% of the polarized light components are absorbed without being used, and energy is wasted.

  For example, in the use of a polarizer for a liquid crystal display or the like, from the viewpoint of energy use efficiency, the use of a polarizer using a dichroic material means that the energy of the light source is discarded without using about 50%. In order to ensure constant brightness and luminance, a light source with excessive brightness is required.

  In view of this, a display using such a dichroic polarizer is expected to have an energy saving technique for reducing energy loss.

  In order to effectively use the light of the light source, polarization control with a small absorption loss is required, and examples thereof include a refraction control type and a scattering control type.

  In the scattering type polarizer, the polarized light component orthogonal to the polarized light on the light transmitting side is scattered inside, so the polarized light scattered by the light scatterer or diffuser inside or behind the polarizer is converted into non-polarized light. It is considered possible to increase utilization efficiency by returning and reusing.

  The principle of polarization control technology using anisotropic light scattering is old, and it has been reported that it originates from the use of silver iodide needle crystal grains (see, for example, Non-Patent Document 1). In addition, there has been reported a polarizer in which a glass plate on the side sandwiching a plate-like material crystallized with a sodium nitrate single crystal on mica is roughly polished and held with a certain gap (for example, non-patent) Reference 2).

  The polarizer in Non-Patent Document 2 has optical anisotropy, and light passes when the refractive index of the glass plate and the ordinary light refractive index of the internal plate match, and the refractive index of the glass plate and the internal A polarization control method has been reported that utilizes the fact that light does not pass through because light is reflected and scattered internally when the extraordinary refractive index of the plate-like material does not match.

  In addition to this, as a polarization control technique using light scattering, a method of stretching a film member made of birefringent rod-shaped aragonite-based calcium carbonate and birefringent resin has been reported (for example, Patent Document 1). In the method of Patent Document 1, by controlling the direction in which the consistency between the refractive index of the particle and the refractive index of the resin is developed and the direction in which the mismatch is developed, only the polarization component in the matched axial direction is allowed to pass. Although a method of reflecting and scattering the polarization component in the misalignment axis direction and returning it to the light source side has been reported, there is a description in the specification that the shape characteristics of the particles do not have to be rod-shaped, and specifics regarding the performance to be manifested There is no description of specific examples and measures for obtaining the consistency of refractive index between particles and resin.

  In addition, a method of controlling scattering polarization by controlling the morphology of a resin blend material has been reported (for example, see Non-Patent Documents 3 and 4). Non-Patent Documents 3 and 4 also report that the function is manifested by making the matching and mismatching of the refractive index of the resin constituting the matrix and the resin constituting the dispersed phase compatible. In addition, a method for controlling the consistency and inconsistency of the refractive index with the resin base material in the case where the material to be blended becomes core-shell type rubber particles has been reported (for example, see Non-Patent Document 5).

  Furthermore, a method has been reported in which fibrous substances are arranged in a resin base material so as to develop matching and inconsistency of refractive index with the base material (see, for example, Patent Document 2).

  A method for producing an optical material in which 0.01 to 30% by weight of a particle having a particle length smaller than the wavelength of light used as an inorganic particle exhibiting birefringence with respect to a resin substrate is reported (from 10 nm) ( For example, see Patent Document 3). In Patent Document 3, the resin composition containing the particles acts as a uniform medium for light, and the birefringence of the birefringence of the birefringent crystal (particles herein) and the birefringence of the resin The size of the birefringent crystal must be smaller than the wavelength of light in order to be regarded as the sum of the above, and the particle sizes in the examples are those using particles of less than 500 nm, It does not describe the behavior when the particles are larger than this, and the behavior when the resin composition containing the particles becomes a non-uniform medium for light. Further, the wavelength of light of a specific optical element is not specified, and the wavelength of light used for evaluation is not described in the examples, and knowledge about particles of 500 nm or more cannot be confirmed.

  In addition, a resin material exhibiting non-birefringence has been reported by blending strontium carbonate exhibiting negative birefringence as particles of 500 nm or less (see, for example, Patent Document 4). In Patent Document 4, assuming that particles of 500 nm or less are desired to maintain transparency as an optical resin material, the method for producing particles of 500 nm or less and the optical properties of the resin using the same show the effect of reducing orientation birefringence. However, it is described that there is a problem in transparency with a size larger than this.

  Non-Patent Documents 1 to 5 and Patent Documents 1 and 2 listed here are reports of scattering-type polarization control in which light is transmitted or scattered between a base material and a substance disposed inside. At that time, Non-Patent Document 1 and Non-Patent Document 2 have not been able to control the consistency and mismatch of the birefringence of the resin with respect to the particle size and the particle refractive index, and have not yet been put into practical use.

  In Non-Patent Documents 3 to 5 and Patent Documents 1 and 2, by manipulating the consistency of the refractive index difference between the base material and the optically anisotropic material disposed therein, light transmission according to the polarization component is performed. In particular, in scattering-type polarization control, control of the refractive index difference between the materials is an important component, but control is very important. It is difficult and has not been put to practical use.

  Patent Document 3 and Patent Document 4 describe a method of reducing birefringence while maintaining transparency by blending particles of a specific size exhibiting birefringence as particles, and the particle size is 500 nm or less or light It is necessary to make it smaller than the wavelength.

Japanese Laid-Open Patent Publication No. 2002-258039 Re-publication 2005-008302 Japanese Laid-Open Patent Publication No. 2004-109355 JP 2004-035347 PR E. H. Land, J .; Opt. Soc. Am. , Vol. 41, no. 21, 957-963 (1951) T.A. Yamaguchi, J. et al. Opt. Soc. Am. , Vol. 45, no. 10, p891-892 (1955) H. Jagt, C.I. Bastianasen et al., Adv. Mater. , Vol. 10, no. 12, 934-937 (1998) T.A. Koyano, I .; Akiba, SEN'I GAKKAISHI, Vol. 60, no. 6, 179-182 (2004) Y. Dirit et al. Appl. Phys. , Vol. 83, no. 6,2927-2933 (1998)

  The object of the present invention has been made in view of the above-mentioned facts, and the object is to provide a resin composition for an optical film comprising fibrous or columnar particles having a specific particle size and a resin having transparency. Another object of the present invention is to provide an optical member that is a film comprising the same and selectively transmits or scatters a polarized component when light is incident on the film.

  As a result of intensive studies, the present inventors have found that a resin composition comprising fibrous or columnar particles having a specific particle size and a resin having transparency solves the above-described problems.

  That is, the present invention relates to at least one kind of fibrous or columnar particles having an average minor axis diameter of 1 to 70 nm and an average major axis diameter of 600 nm to 5 μm. The present invention relates to a resin composition for an optical film comprising 30% by weight and 70 to 99% by weight of a resin having transparency, and an optical film comprising the same.

  The present invention is described in detail below.

  The fibrous or columnar particles used in the present invention have an average minor axis diameter of 1 to 70 nm, particularly preferably 40 to 60 nm, an average major axis diameter of 600 nm to 5 μm, and particularly 600 nm to 3 μm. preferable. If the average dimension of the minor axis diameter of the particles is less than 1 nm, it is difficult to substantially synthesize the particles. If the average dimension exceeds 70 nm, when the resin composition for an optical film is an optical film, the polarization component is parallel to the minor axis direction. Will be scattered. Further, it is necessary that the average dimension of the major axis diameter is 600 nm or more as a sufficient size to scatter the polarized component parallel to the direction of the major axis diameter of the particles. However, when the average major axis diameter is less than 600 nm, selective transmission of light is difficult when the resin composition for an optical film is an optical film, and the polarization component can be sufficiently scattered. When the thickness exceeds 5 μm, the film tends to be broken by shearing or the like, and the moldability of the resin composition for optical films is poor. One or more kinds of these fibrous or columnar particles can be used.

  In particular, it exhibits the effect of selectively transmitting or scattering polarized components in a wider wavelength range, and is useful for improving performance in devices that require brightness enhancement films and high polarization efficiency in polarization control such as liquid crystal displays. Since it becomes possible to use the particles, the fibrous or columnar particles have an average minor axis diameter of 1 to 70 nm and an average major axis diameter of 600 nm or more and less than 800 nm (a) and the minor axis diameter. It is preferable that it consists of particle | grains (b) whose average dimension of 1-70 nm is, and whose average dimension of a major axis diameter is 800 to 5 micrometers. The mixing ratio (weight ratio) of these particles (a) and particles (b) is preferably 10:95 to 95: 5, and particularly preferably 30:70 to 70:30.

  As the fibrous or columnar particles of the present invention, any particles may be used as long as they are within the shape and particle size range defined in the present invention without impairing the object of the present invention. For example, titanium oxide Inorganic crystal particles such as zinc oxide, magnesium oxide, strontium carbonate, calcium carbonate, magnesium carbonate, cobalt carbonate, manganese carbonate, calcium silicate, basic calcium sulfate, aluminum hydroxide oxide, imogolite, silicon carbide, etc. Titanium oxide, zinc oxide, strontium carbonate, silicon carbide and the like are preferable. However, particles that develop color due to light absorption from the ultraviolet region to the visible light region, which may impair the purpose of the present invention, cannot be used. Fibrous or columnar particles may use other types of particles than those described above as long as the object and effect of the present invention can be exhibited regardless of the presence or absence of optical anisotropy (birefringence) due to the crystalline state. Can do.

  The resin having transparency of the present invention may be any resin that does not impair the effects of the present invention, such as polymethyl methacrylate, polystyrene, styrene acrylonitrile copolymer, polyfumaric acid diester, polycarbonate, polyarylate, polyether. Examples include sulfone, cyclic polyolefin, maleimide copolymer, polyethylene terephthalate, and polyethylene naphthalate, and polystyrene, polycarbonate, polyarylate, and the like are particularly preferable. Moreover, the resin having transparency according to the present invention can be used regardless of the presence / absence of birefringence, the sign of birefringence, and the magnitude thereof.

  In addition, when each of them has birefringence as a combination of fibrous or columnar particles and transparent resin, combine them without considering birefringence cancellation as a result of combining them. For example, titanium oxide showing positive birefringence and polycarbonate showing positive birefringence can be used in combination. Similarly, calcium carbonate exhibiting negative birefringence and polystyrene or polymethyl methacrylate exhibiting negative birefringence can be combined.

  The blending ratio of at least one or more kinds of fibrous or columnar particles and transparent resin in the optical film resin composition of the present invention is 1 to 30% by weight of at least one or more kinds of fibrous or columnar particles, transparent Resin is 70 to 99% by weight, preferably fibrous or columnar particles are 5 to 30% by weight, transparent resin is 70 to 95% by weight, particularly preferably fibrous or columnar particles are 10 to 30% by weight. %, And the resin having transparency is 70 to 90% by weight. When the amount of fibrous or columnar particles is less than 1% by weight, when the resin composition for an optical film is an optical film, it is insufficient to cause transmission and scattering of polarized light, and is 30% by weight. When exceeding, the moldability of the resin composition for optical films is inferior.

There is no restriction | limiting in particular as a manufacturing method of the resin composition for optical films of this invention, For example, it can obtain by carrying out dispersion | distribution mixing using a stirring mixing device. Specific examples of the stirring and mixing apparatus include a disk type stirring and mixing apparatus, a cylindrical rotor type stirring and mixing apparatus, and a homogenizer. When using a stirring and mixing device, it is preferable that the fibrous or columnar particles are in a resin having transparency and are in an isolated and uniformly dispersed state, and for that purpose, at a high shear rate. it is preferred to perform dispersion mixture, in particular shear rate is preferably performed by 500～50,000Sec ^-1, further 1,000~25,000sec ^-1.

  In addition, when dispersing and mixing, the surface of the fibrous or columnar particles is treated with a surface treatment agent or the like in advance so that more uniform dispersion is possible. It is preferable to stir and mix using a solvent that exhibits an affinity for both the resin having the above. For the purpose of further controlling the solvent viscosity, volatilization rate and the like, the solvent may be mixed with a poor solvent in which one or both of the fibrous or columnar particles and the resin component having transparency become poor in affinity.

  Any surface treatment agent for the fibrous or columnar particles can be used as long as the effect of the present invention is not impaired. For example, a silane coupling agent, a titanate coupling agent, an acidic sea surface active agent, a basic surfactant can be used. There are surfactants, salt-type surfactants, and the like, and polymer-type surfactants having these molecular weights manipulated can be used. Examples of acid type surfactants include phosphate esters, fatty acid esters, sulfonate esters, and derivatives thereof. Examples of the basic surfactant include alkylamine type derivatives. Examples of the salt surfactant include a salt type in which both an acid type and a base type are mixed, and a type in which an acid and a base are neutralized. Depending on the knowledge of the surface energy, functional group, specific surface area, etc. of the particles, the surface treatment may be used as appropriate, and any surface treatment may be applied as long as the object and effect of the present invention are not impaired.

  The solvent in which both the surface-treated fibrous or columnar particles and the transparent resin have an affinity is not particularly limited. For example, methylene chloride, chloroform, toluene, tetrahydrofuran, acetone, N-methylpyrrolidone, acetic acid ethyl ester , Methyl ethyl ketone, methyl isobutyl ketone, acetonitrile and the like.

  As described above, the solvent is removed from the solution uniformly dispersed in the solution containing the fibrous or columnar particles and the transparent resin, and solidified uniformly in the transparent resin by solidifying. Alternatively, a resin composition for an optical film having a state in which columnar particles are dispersed can be obtained.

  Further, a fiber or columnar particle and a transparent resin previously dispersed and mixed by a method as described above may be further dispersed and mixed by melt mixing to be used for T-die extrusion molding or the like. In this case, a well-known melt kneader can be used, and examples thereof include a roll kneader, a single screw extruder, a twin screw extruder, and the like.

  The film haze value of the resin composition for an optical film of the present invention is preferably 10% or more, which is effective for controlling light transmission and scattering.

Further, the resin composition for an optical film of the present invention is excellent in the selective transmission of polarized light, and specifically, a fibrous or columnar shape with respect to those in which fibrous or columnar particles are oriented. The polarization light intensity (T _// ) when a polarization component from a direction parallel to and perpendicular to the direction corresponding to the major axis of the particle is incident and perpendicular to the major axis of the fibrous or columnar particle The transmitted light intensity ratio is (T _⊥ ) / (T _// )> 1.0 as the relationship of the polarized light intensity (T _⊥ ) when the polarized component is incident.

  The resin composition for an optical film of the present invention may contain an antioxidant or the like in order to increase its thermal stability. As the antioxidant, known ones can be used, and examples thereof include hindered phenol antioxidants, phosphorus antioxidants, and other antioxidants. These antioxidants can be used alone or in combination. It is preferable to use a hindered phenol-based antioxidant and a phosphorus-based antioxidant in combination since the antioxidant action is synergistically improved.

  The resin composition for an optical film of the present invention may contain a light stabilizer for thermal coloring of the film and suppression of light deterioration. Known light stabilizers can be used, such as hindered amine light stabilizers, and those having a molecular weight of 1,000 or more are preferred as being excellent in thermal coloring and light stabilization.

  Furthermore, the resin composition for optical films of the present invention may contain a UV stabilizer in order to suppress UV deterioration of the film. Known ultraviolet stabilizers can be used, and for example, ultraviolet absorbers such as benzotriazole, benzophenone, triazine, and benzoate can be used.

  The optical film resin composition of the present invention is preferably an optical film, and the method for producing the optical film is not particularly limited. For example, a solution comprising a fibrous or columnar particle, a transparent resin, and a solvent. As a solution casting method, a film obtained by uniformly dispersing and mixing can be directly formed into a film, the solvent can be removed, and an optical film can be obtained.

  Moreover, the resin composition for optical films of this invention is grind | pulverized, it is good also as a film by making pellets using a heat-melt extrusion apparatus after making it into flake form, and subsequent T-die extrusion molding.

  In the case of a film by a solution casting method, for example, as described above, a transparent resin and fibrous or columnar particles are dispersed and mixed in a high-speed shear field in a solvent in which the transparent resin is soluble. A method of obtaining a film by casting a solution of the resin composition for an optical film (hereinafter referred to as “dope”) on a support substrate and then removing the solvent by heating or the like can be mentioned. As a method for casting the dope, any method can be used as long as it enables film formation, and examples thereof include a T-die method, a doctor blade method, a bar coater method, a roll coater method, and a lip coater method. . The supporting substrate to be used may be any film as long as it enables film surface smoothness and optical uniformity when formed into a film. For example, a glass substrate, a metal substrate, a plastic film such as polyethylene terephthalate, or the like is used. Can do.

  Since the optical film comprising the resin composition for an optical film of the present invention is an optical film excellent in selective permeability of more polarized light, it is preferable to orient the fibrous or columnar particles in a specific direction, The orientation method is not particularly limited, and for example, a method of orientation in a shear stress field such as an injection molding method, an extrusion molding method, a blow molding method, a pressure forming method, a mechanical stretching method, or the like; Among them, a method of orientation in a shear stress field is preferable, and a mechanical stretching method and an extrusion method are particularly preferable.

  Examples of the mechanical stretching method include, for example, uniaxial stretching, biaxial stretching, etc. Among them, uniaxial stretching is preferable, and in particular, a method of imparting orientation simultaneously with processing into a film by a molding method by T-die extrusion molding, A method of uniaxial stretching with a stretching machine after forming a film is preferred.

  An example of the stretching method is introduced below. Examples of the uniaxial stretching method of the film include a method of stretching with a tenter, a method of rolling and stretching with a calendar, and a method of stretching between rolls. Moreover, a small stretching apparatus for experiment that enables uniaxial stretching can also be used.

  The stretching process conditions for aligning the fibrous or columnar particles in a specific direction by uniaxial stretching of the film include stretching and orientation at a glass transition temperature (Tg) + 10 ° C. to Tg + 40 ° C. of the resin having transparency. In particular, it is preferable to align at Tg + 10 ° C. to Tg + 30 ° C. The draw ratio may be any size that exceeds the original size, preferably 1.1 times or more, and may be further drawn at a higher magnification.

  The extrusion molding method is not particularly limited, and for example, a fiber or columnar particle can be oriented by a T-die extrusion molding method as a melt casting method. As a more specific T-die extrusion molding method, After the resin composition for optical films is extruded into a film shape from a narrow slit die such as a T die, it can be molded while being cooled with a cooling roll or air. When this T-die extrusion molding method is used, it may be a temperature that can be melt-molded in a temperature range equal to or higher than the Tg of the resin having transparency. preferable. The molded product extruded from the T-die may be stabilized by directly fixing the orientation of the fibrous or columnar particles using a cooling roll or the like. Or you may perform the orientation process of columnar particle | grains.

  The resin composition for an optical film of the present invention and the optical film comprising the same can be obtained by the method as described above, and its function can be evaluated as an optical property.

A polarizer using a conventional dichroic material passes one polarized light and absorbs the other polarized light (FIG. 1). However, according to the present invention, the direction corresponding to the major axis of the fibrous or columnar particles is different from that obtained by orienting the fibrous or columnar particles in the optical film comprising the resin composition for an optical film. Polarized light intensity when polarized light component (T _// ) is incident on a polarized light component parallel and perpendicular to the reference, and polarized light component perpendicular to the major axis of the fibrous or columnar particle is incident as a reference. as the relationship of the intensity (T _⊥), the transmitted light intensity _{(T ⊥) / (T //} )> can be obtained 1.0 become one. That is, when the selective transmission characteristic of polarized light is developed, the polarization component that does not transmit is returned to the light source side again by scattering and can be recycled without loss.

This principle will be described with reference to FIG.
a) Light from a light source is incident on an optical film made of the optical film composition.
b) In the optical film comprising the resin composition for an optical film, a large amount of the polarization component passes when the major axis of the fibrous or columnar particles and the light transmission axis of the polarizing plate are perpendicular to each other.
c) In the optical film comprising the resin composition for an optical film, when the major axis of the fibrous or columnar particles and the light transmission axis of the polarizing plate are orthogonal, the polarization component orthogonal to the transmitted polarization component depends on the particles. By being scattered, the amount of transmission decreases, and many components are returned to the light source side.
d) The light returned to the light source side is incident again on the optical film made of the resin composition for optical films.

  The optical film comprising the resin composition for an optical film of the present invention can be used by being laminated with a polarizing plate having a polarizer or a protective layer. Moreover, it can use as a member which laminated | stacked combining a light-guide plate and a polarizing plate.

  Furthermore, the optical film laminated | stacked with the polarizing plate which has a polarizer or a protective layer on the optical film of this invention can be used as a brightness improvement film. In particular, by installing the brightness enhancement film between the polarizing plate and the light source, when the brightness enhancement film selectively converts the light from the light source into polarized light and transmitted light and scattered light, the polarized transmitted light remains polarized. The light absorption loss due to the polarizing plate is reduced because it passes through the plate, and the light utilization efficiency of the light source can be enhanced by the system that uses the scattered light returned to the light source side as reflected light by reflecting it again.

  A resin composition for an optical film comprising a fibrous or columnar particle having a specific particle size and a resin having transparency, with respect to a polarizing component incident on the optical film comprising the resin composition for an optical film The polarization component is selected by forming a state in which the fibrous or columnar particles are oriented so that the refractive index in the major axis direction of the fibrous or columnar particles does not match the refractive index of the transparent resin. The optical film is made to transmit or scatter, and is useful for a device that requires a brightness enhancement film and high polarization efficiency in polarization control such as a liquid crystal display.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

  Hereafter, the method used for evaluation and measurement of an Example is shown.

-Measurement of glass transition temperature of transparent resin-
A differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd., trade name DSC200) was used, and the heating rate was 10 ° C./min. Measured with

~ Measurement method of haze ~
Based on JIS K7136 (2000), it measured using the haze meter (The Nippon Denshoku Industries make, brand name NDH5000).

-Measurement method of total light transmittance-
Based on JIS K7361-1 (1997), it measured using the haze meter (Nippon Denshoku Industries make, brand name NDH5000).

Through T _⊥, measuring and the transmitted light intensity ratio calculation of _{T //} ~
The optical film made of the resin composition for an optical film is laminated and arranged so that the absorption axis of the polarizing plate is orthogonal to the direction in which the long axes of the fibrous or columnar particles in the optical film are oriented. incident light toward, to obtain a T _⊥ the emission light intensity from the optical film was measured by a polarization microscope. On the other hand, light is incident from the side of the polarizing plate toward the optical film by laminating and arranging so that the absorption axis of the polarizing plate is parallel to the direction in which the long axes of the fibrous or columnar particles in the optical film are oriented. The intensity of light emitted from the optical film was measured with a polarizing microscope to obtain T _// . The resulting _{T //} and the transmitted light intensity ratio and a _{T⊥ (T ⊥) / (T} //) was calculated. At this time, an optical wavelength of 400 to 700 nm was used for the measurement. Here, for convenience of calculation, a value at a light wavelength of 550 nm is used as a representative value when one point is measured.

  When evaluating the wavelength dependence of the transmitted light intensity ratio, a value obtained by dividing the transmitted light intensity ratio of 450 nm, 550 nm, and 650 nm by the transmitted light intensity ratio of 550 nm, respectively, was used.

  However, such characteristics are not different in the visible light region of 380 to 780 nm.

Example 1
Zinc oxide particles (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight, average size of short axis diameter 50 nm, average length of long axis diameter 3 μm, refractive index 1.95 as fibrous or columnar particles ) A methylene chloride slurry solution containing 10 wt% was mixed for 5 min. At a shear rate of 10,000 sec ⁻¹ using a φ50 mm laboratory cylindrical rotor type stirring and mixing device. After being dispersed and mixed, polycarbonate (made by Teijin Chemicals, trade name: Panlite, glass transition temperature: 141 ° C., average refractive index: 1.55) is blended as a transparent resin, and zinc oxide and polycarbonate in the solution are mixed. The composition ratio was adjusted to 30% by weight: 70% by weight and the concentration of the non-volatile components in the solution was adjusted to 25% by weight, and a φ30 mm small homogenizer was used at 3,000 rpm for 60 min. Dissolved and mixed. This solution was used as a supporting substrate to form a film on a polyethylene terephthalate resin film, allowed to stand overnight, and then dried at 160 ° C. to obtain a film-like resin composition for an optical film. The obtained film had a Tg of 165 ° C. The film haze value was 34%.

Next, the film obtained for evaluating the transmitted light intensity ratio was stretched 2.0 times at 180 ° C. in a free-width uniaxial stretching mode using a biaxial stretching apparatus (manufactured by Imoto Seisakusho, model 16A1). To obtain an optical film. The obtained optical film had a total light transmittance of 90%. Further, the transmitted light intensity ratio _{(T ⊥) / (T //} ) was 2.5. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Example 2
An optical film was obtained by carrying out the same operation as in Example 1 except that the stretching condition of the film in Example 1 was changed to 3.0 times at 180 ° C. Further, the total light transmittance of 87% obtained optical film, the transmitted light intensity ratio _{(T ⊥) / (T //} ) was 3.0. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Example 3
Oxidation in solution using the zinc oxide particles of Example 1 (treated with 10% by weight of acid phosphoxyethyl methacrylate per particle weight, average minor axis diameter 60 nm, major axis major 700 nm) A film-like resin composition for an optical film and an optical film were obtained by carrying out the same operations as in Example 1 except that the composition ratio of zinc and polycarbonate was 1 wt%: 99 wt%. The obtained film had a Tg of 157 ° C. The film haze was 22%.

The total light transmittance of the optical film was 91%, and the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 1.15. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Example 4
A film-like resin composition for an optical film and an optical film were obtained by carrying out the same operations as in Example 1 except that the composition ratio of zinc oxide and polycarbonate in the solution of Example 1 was 10% by weight: 90% by weight. Got. The obtained film had a Tg of 160 ° C. The film haze value was 24%.

The total light transmittance of the optical film was 90%, and the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 2.0. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Example 5
Titanium oxide particles (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight, average size of minor axis diameter of 40 nm, average size of major axis diameter of 2 μm, average refractive index instead of zinc oxide of Example 1 2.6, using the refractive index 2.7 in the major axis direction, and performing the same operation as in Example 1 except that the composition ratio of titanium oxide and polycarbonate in the solution was 5 wt%: 95 wt%. Thus, a film-like resin composition for an optical film and an optical film were obtained. The obtained film had a Tg of 165 ° C. The film haze value was 39%.

The total light transmittance of the optical film was 90%, and the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 2.2. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Example 6
The film-shaped resin composition for an optical film obtained in Example 1 was pulverized, and a single-screw extruder having a screw diameter of 20 mm and a compression ratio of 3.5 having a T die having a width of 200 mm and a slit gap of 0.25 mm ( Extruder cylinder temperature profile using Toyo Seiki Co., Ltd. (trade name: Laboplast Mill) was extruded at 180 ° C; 200 ° C; 240 ° C; A film was obtained while cooling.

The obtained film was stretched and oriented under the same conditions as in Example 1 to obtain an optical film. The total light transmittance of the optical film was 88%. The transmitted light intensity ratio _{(T ⊥) / (T //} ) was 2.7. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Example 7
The composition ratio of zinc oxide and polyarylate in the solution using polyarylate (made by Unitika, trade name U polymer P-3001, glass transition temperature 160 ° C.) instead of polycarbonate as the resin having transparency in Example 1 10 wt%: A film-like resin composition for an optical film was obtained by performing the same operation as in Example 1 except that the content was 90 wt%. The obtained film had a Tg of 177 ° C. The film haze value was 35%.

An optical film was obtained in the same manner as in Example 1 except that the obtained film was stretched at 195 ° C. The total light transmittance of the optical film was 90%. Further, the transmitted light intensity ratio _{(T ⊥) / (T //} ) was 2.8. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Example 8
Strontium carbonate particles (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight, average size of short axis diameter 60 nm, long axis diameter average size 600 nm, average refractive index instead of zinc oxide of Example 1 1.67, a refractive index of 1.52 in the major axis direction, and a solution using polystyrene (made by Tosoh, standard polystyrene, glass transition temperature 100 ° C.) instead of polycarbonate as the resin having transparency in Example 1. A film-like resin composition for an optical film was obtained by carrying out the same operation as in Example 1 except that the composition ratio of strontium carbonate and polystyrene was 20 wt%: 80 wt%. The obtained film had a Tg of 118 ° C. The film haze value was 32%.

An optical film was obtained in the same manner as in Example 1 except that the film-like resin composition for an optical film was stretched at 140 ° C. The total light transmittance of the optical film was 90%, and the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 2.0. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Example 9
Silicon carbide particles instead of zinc oxide of Example 1 (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight, minor axis diameter average size 50 nm, major axis diameter average size 5 μm, average refractive index 2.6), the same operation as in Example 1 was carried out except that the composition ratio of silicon carbide and polycarbonate in the solution was 10% by weight: 90% by weight. And an optical film were obtained. The obtained film had a Tg of 160 ° C. The film haze value was 40%.

The total light transmittance of the optical film was 88%, and the transmitted light intensity ( _T⊥ ) / (T _// ) was 2.3. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Example 10
Zinc oxide particles (a) treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight as fibrous or columnar particles (average minor axis diameter 50 nm, major axis major dimension 600 nm, refractive index 1.95) and zinc oxide particles (b) (average size of short axis diameter 50 nm, average length of long axis diameter 1 μm, refractive index 1.95), zinc oxide particles in solution The same operation as in Example 1 was carried out except that the composition ratio of (a), zinc oxide particles (b) and polycarbonate was adjusted to 5% by weight: 5% by weight: 90% by weight. A resin composition for an optical film and an optical film were obtained. The obtained film had a Tg of 160 ° C. The film haze value was 30%.

The total light transmittance of the optical film was 90%, and the transmitted light intensity ratio ( _T⊥ ) / (T _// ) at a wavelength of 550 nm was 2.0. The transmitted light intensity ratio at a wavelength of _{450nm (T ⊥) / (T} //) was 2.2, the transmitted light intensity ratio at a wavelength of _{650nm (T ⊥) / (T} //) was 2.0. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin _{composition, (T ⊥) / (T} //)> 1.0, also the transmitted light intensity ratio by the wavelength 450 It was stabilized at 2.2 to 2.0 at 650 nm, and the selective transmission of polarized light was excellent in a wide light wavelength range.

Example 11
As the fibrous or columnar particles, zinc oxide particles (a) (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight, average minor axis diameter of 50 nm, average major axis of 600 nm, refractive 1.95) and titanium oxide particles (b) (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight), average minor axis diameter of 40 nm, average major axis diameter of 2 μm, refractive index of 2 .7), and the composition ratio of zinc oxide particles (a), titanium oxide particles (b) and polycarbonate in the solution is 3% by weight: 7% by weight: 90% by weight. The same operation as in Example 1 was carried out except that the content was adjusted to be%, whereby a film-like resin composition for an optical film and an optical film were obtained. The obtained film had a Tg of 160 ° C. The film haze value was 30%.

The total light transmittance of the optical film was 90%, and the transmitted light intensity ratio ( _T⊥ ) / (T _// ) at a wavelength of 550 nm was 2.3. The transmitted light intensity ratio at a wavelength of _{450nm (T ⊥) / (T} //) is 2.4, the transmitted light intensity ratio at a wavelength of _{650nm (T ⊥) / (T} //) was 2.3. The appearance of the optical film was good.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained resin composition for an optical film is ( _T⊥ ) / (T _// )> 1.0, and the transmitted light intensity ratio depending on the wavelength is 450 nm to It was stabilized at 2.4 to 2.3 at 650 nm, and the selective transmission of polarized light was excellent in a wide light wavelength range.

Example 12
A polarizer having a total light transmittance of 37% as a single polarizer and the optical film obtained in Example 1 are aligned with the direction in which the major axes of the particles are oriented as the stretching direction of the optical film and the absorption axis of the polarizer. The film was laminated as described above. As a result of measuring the total light transmittance by passing the light from the light source through the film laminate in such a manner that a light guide plate for the light source and a light reflection plate on the back side are arranged on the back side of the film laminate, 49 %Met. Further, the transmitted light intensity ratio when the _{(T ⊥) / (T //} ) was 990.

Therefore, the transmitted light intensity ratio of the optical film made of the obtained optical film resin composition is excellent in selective permeability for light polarized because it is _{(T ⊥) / (T //} )> 1.0 It was a thing.

Furthermore, since the obtained laminated film of the optical film and the polarizer has a large transmitted light intensity ratio (( _T⊥ ) / (T _// ) is 990), this laminated film is suitably used as a brightness enhancement film. be able to.

Comparative Example 1
A film-like resin composition was obtained by carrying out the same operation as in Example 1 except that the stretching temperature was changed to 160 ° C. without using zinc oxide in Example 1. The obtained film had a Tg of 140 ° C. The film haze value was 0.1%.

The obtained film was stretched and oriented under the same conditions as in Example 1 to obtain a film. The total light transmittance of the film was 90%. The appearance of the film was good. However, the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 1.0.

Therefore, since it did not use the fibrous or columnar particles, was inferior in selective permeability for light polarized because the transmitted light intensity ratio _{(T ⊥) / (T //} ) = _1.0 .

Comparative Example 2
In Example 1, fibrous or columnar zinc oxide particles (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight, minor axis diameter average dimension 30 nm, major axis diameter average dimension 120 nm, refractive index 1 .95) A methylene chloride slurry solution containing 10 wt% was mixed for 5 min. At a shear rate of 300 sec ⁻¹ using a φ50 mm laboratory cylindrical rotor type stirring and mixing device. A film-like resin composition was obtained by carrying out the same operations as in Example 1 except that the film was dispersed and mixed, and the stretching temperature was 165 ° C. The obtained film had a Tg of 149 ° C. Since there were many large particle clusters due to poor dispersion in the film, the surface was uneven and the appearance was poor.

The obtained film was stretched and oriented under the same conditions as in Example 1 to obtain a film. The total light transmittance of the film was 86%. The transmitted light intensity ratio _{(T ⊥) / (T //} ) was 1.0.

Therefore, used since the average size of the major axis diameter of the particles is as small as 120 nm, poor surface appearance, also the transmitted light intensity ratio _{(T ⊥) / (T //} ) for light polarized from being a _{= 1.0} It was inferior in permselectivity.

Comparative Example 3
Although an operation similar to that in Example 1 was carried out except that the composition ratio of zinc oxide and polycarbonate in the solution was 40% by weight: 60% by weight in Example 1, an attempt was made to produce a film-like resin composition. Since the blending amount of zinc oxide (particles) was as large as 40% by weight, it was very fragile, and fractured with remarkable cracks and wrinkles on the film during the stretching of the film.

  Therefore, the blending ratio of the fibrous or columnar particles is large, and the molding processability is poor.

Comparative Example 4
Example 1 is the same as Example 1 except that zinc oxide (treated with 10% by weight of acid phosphoxyethyl methacrylate per particle weight, average minor axis diameter 200 nm, major axis average 600 nm) is used. The same operation was carried out to obtain a film-like resin composition. The Tg of the film was 160 ° C. The film haze value was 40%.

The obtained film was stretched and oriented under the same conditions as in Example 1 to obtain a film. The appearance of the film was good. The total light transmittance of the film was 81%. However, the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 1.0.

Accordingly, since the average size of the minor axis diameter of the particles is as large as 200nm used, the transmitted light intensity ratio _{(T ⊥) / (T //} ) = 1.0 and was inferior in permselective polarized light .

Comparative Example 5
In Example 1, instead of zinc oxide, strontium carbonate (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight, minor axis diameter average dimension 50 nm, major axis diameter average dimension 250 nm, average refractive index 1 .6, except that the major axis direction refractive index 1.52) was used, the same operation as in Example 1 was carried out to obtain a film-like resin composition. The Tg of the film was 165 ° C. The film haze value was 14%.

The obtained film was stretched and oriented under the same conditions as in Example 1 to obtain a film. The appearance of the film was good. The total light transmittance of the film was 90%. However, the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 1.0.

Therefore, since the average size of the major axis diameter of the particles used is as small as 250 nm, the transmitted light intensity ratio ( _T⊥ ) / (T _// ) = 1.0, which is inferior in the selective permeability of polarized light. .

Comparative Example 6
Example 1 except that spherical colloidal silica (treated with 10% by weight of acid phosphoxyethyl methacrylate per particle weight, average particle diameter of 80 nm, average refractive index of 1.46) was used instead of zinc oxide in Example 1. The same operation as 1 was performed to obtain a film-like resin composition. The Tg of the film was 168 ° C. The film haze value was 8%.

The obtained film was stretched and oriented under the same conditions as in Example 1 to obtain a film. The appearance of the film was good. The total light transmittance of the film was 90%. However, the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 1.0.

Therefore, since spherical particles are used as particles to be used instead of fibrous or columnar particles, the transmitted light intensity ratio ( _TＴ ) / (T _// ) = 1.0, which is inferior in the selective transmission of polarized light. there were.

Comparative Example 7
In Example 1, in place of zinc oxide, strontium carbonate (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight, minor axis diameter average dimension 10 nm, major axis diameter average dimension 60 nm, average refractive index 1 .6, except that the major axis direction refractive index 1.52) was used, the same operation as in Example 1 was carried out to obtain a film-like resin composition. The Tg of the film was 169 ° C. The film haze value was 0.6%.

The obtained film was stretched and oriented under the same conditions as in Example 1 to obtain a film. The appearance of the film was good. The total light transmittance of the film was 90%. However, the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 1.0.

Therefore, since the average dimension of the major axis diameter of the particles used is as small as 60 nm, the transmitted light intensity ratio ( _T⊥ ) / (T _// ) = 1.0, which is inferior in the selective permeability of polarized light. .

Comparative Example 8
In Example 1, in place of zinc oxide, strontium carbonate (treated with 10% by weight of acid phosphooxyethyl methacrylate per particle weight, minor axis diameter average dimension 90 nm, major axis diameter average dimension 500 nm, average refractive index 1 .6, except that the major axis direction refractive index 1.52) was used, the same operation as in Example 1 was carried out to obtain a film-like resin composition. The Tg of the film was 160 ° C. The film haze value was 45%.

The obtained film was stretched and oriented under the same conditions as in Example 1 to obtain a film. The appearance of the film was good. The total light transmittance of the film was 90%. However, the transmitted light intensity ratio ( _T⊥ ) / (T _// ) was 1.0.

Accordingly, since the average size of the large and the average length of the short axis diameter of 90nm particle major axis diameter as small as 500nm used, the transmitted light intensity ratio _{(T ⊥) / (T //} ) = 1.0 and polarized light The selective permeability was inferior.

It is a figure which shows the light transmission behavior of a dichroic polarizer. It is a figure which shows the light transmission of the optical film of this invention, reflection and scattering, and light recycling behavior.

Explanation of symbols

A: Polarizer using a dichroic material B: Optical film comprising the resin composition for an optical film of the present invention a; incident light b; transmitted light c; reflected / scattered light d;

Claims (12)

  At least one or more kinds of fibrous or columnar particles having an average minor axis diameter of 1 to 70 nm and an average major axis diameter of 600 to 5 μm and 1 to 30% by weight of transparency A resin composition for an optical film, comprising 70 to 99% by weight of a resin containing   The fibrous or columnar particles have an average minor axis diameter of 1 to 70 nm, an average major axis diameter of 600 to 800 nm, and an average minor axis diameter of 1 to 70 nm. The resin composition for an optical film according to claim 1, comprising particles (b) having an average major axis diameter of 800 nm to 5 μm.   At least one kind of fibrous or columnar particles is composed of titanium oxide, zinc oxide, magnesium oxide, strontium carbonate, calcium carbonate, magnesium carbonate, cobalt carbonate, manganese carbonate, calcium silicate, basic calcium sulfate, aluminum hydroxide oxide The resin composition for an optical film according to claim 1, wherein the resin composition is selected from the group of inorganic crystal particles consisting of imogolite and silicon carbide.   The transparent resin is made of polymethyl methacrylate, polystyrene, styrene acrylonitrile copolymer, polyfumaric acid diester, polycarbonate, polyarylate, polyether sulfone, cyclic polyolefin, maleimide copolymer, polyethylene terephthalate, polyethylene naphthalate. The resin composition for an optical film according to claim 1, wherein the resin composition is selected from the group consisting of:   The resin composition for an optical film according to any one of claims 1 to 4, wherein the film haze value is 10% or more. The resin composition for an optical film according to any one of claims 1 to 5, wherein a resin having transparency and fibrous or columnar particles are dispersed and mixed at a shear rate of 500 to 50,000 sec- ¹ . object.   An optical film comprising the resin composition for an optical film according to claim 1.   The optical film according to claim 7, which is stretched.   The optical film according to claim 8, wherein the optical film is uniaxially stretched at Tg + 10 ° C. to Tg + 40 ° C. with respect to the glass transition temperature (Tg) of the resin having transparency.   9. The optical film according to claim 8, wherein the film is melt-extruded at Tg + 10 ° C. to Tg + 130 ° C. up to 350 ° C. with respect to the glass transition temperature of the resin having transparency.   An optical film comprising the optical film according to claim 7 laminated with a polarizer or a polarizing plate having a protective layer.   A brightness enhancement film comprising the optical film according to claim 11.

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