JP5428155B2 - Optical film resin composition and optical film comprising the same - Google Patents

Description

  The present invention relates to a resin composition for an optical film and an optical film using the resin composition for a retardation film of a liquid crystal display (hereinafter referred to as LCD) requiring control of birefringence.

  Liquid crystal displays (LCDs) require many optical films to improve their display characteristics, and optical films such as retardation films for widening the viewing angle and compensating for color tone to increase the visibility of display characteristics. Is used.

  Transparent resin materials are frequently used as optical films in terms of lightness, productivity, and cost.

  In recent years, in order to improve the characteristics of LCDs, the retardation film has also been given importance as a broad-band property capable of controlling the phase difference in the visible light region. For example, in a reflective LCD, a film (also referred to as a circularly polarizing plate) that exhibits a quarter-wave phase difference in a wide band is used.

  For example, for these, a ½ wavelength retardation film is used to offset the wavelength dispersion characteristics to a single retardation film made of polycarbonate, cyclic polyolefin, or the like that exhibits a ¼ wavelength retardation at a single wavelength. It has been proposed that a wide bandwidth is exhibited by laminating layers (see, for example, Non-Patent Document 1). However, this method increases the thickness and weight because two films are laminated. In addition, there are problems such as a very complicated manufacturing process.

  Therefore, as a method for improving the wavelength dependence of retardation with a single film and exhibiting broadband properties, a combination of a molecular structural unit exhibiting positive birefringence and a molecular structural unit exhibiting negative birefringence is combined. A film using a coalescence or a blend of a polymer exhibiting positive birefringence and a polymer exhibiting negative birefringence has been proposed (for example, see Patent Documents 1 to 3).

  However, those proposed in Patent Documents 1 to 3 are not sufficient although the wavelength dependency of the phase difference is improved.

  In addition, optical materials such as optical films and optical adhesives using optically anisotropic particles have been proposed (see, for example, Patent Documents 4 to 7 and Non-Patent Document 2).

  The proposals in Patent Document 4 and Non-Patent Document 2 relate to a zero birefringent material, but there is no mention of a dispersant.

  Patent Documents 5 to 7 relate to a retardation film, and as a proposal of an optical film using optically anisotropic particles, mention is made of a description regarding the aspect ratio and upper limit particle size of the particles, and the blending amount. There is no mention of.

  In the methods proposed in Patent Documents 4 to 7, these optically anisotropic particles tend to aggregate in the film production process. When aggregation of optically anisotropic particles occurs, there are problems such as deterioration of optical properties such as retardation and transparency of the obtained film, and deterioration of film surface properties. In order to manufacture these optical films stably industrially, it is a big subject to suppress aggregation of optically anisotropic particles.

  There has been proposed an optical film obtained by adding a dispersant to fine particles having optical anisotropy, dispersing in a solvent to obtain a fine particle dispersion, and dissolving a transparent polymer (see, for example, Patent Document 8). ). However, Patent Document 8 describes a phosphate dispersant but does not describe a polymer dispersant. When a phosphate ester dispersant is used, the stability of a solution (hereinafter referred to as a dope solution) in which particles are dispersed by dissolving in a solvent in which the transparent polymer and the dispersant are soluble and stirring and mixing. However, since the agglomeration is likely to occur over time, the phase difference of the obtained film is deteriorated.

JP 2000-137116 A JP 2001-337222 A JP 2001-235622 A JP-A-11-293116 JP 2005-156862 A JP 2005-156863 A JP 2005-156864 A JP 2007-140011 A SID '02 Digest, p862 (2002) Polymer Science Society Proceedings Vol. 52, no. 4, p748 (2003)

  The object of the present invention has been made in view of the above-mentioned facts. The object of the present invention is to provide a stable dope because it is excellent in dispersibility and dispersion stability and hardly causes aggregation of optically anisotropic particles. It is to stably provide an optical film having a large in-plane retardation and a small wavelength dependency of a resin composition for an optical film excellent in transparency, and a film obtained by processing the solution. .

  As a result of intensive studies, the present inventors have found that as a resin composition for an optical film, at least one kind of needle-like or spindle-like particles (A), a transparent polymer (B) and a polymer having optical anisotropy. By using a dispersing agent (C), it discovered that the resin composition for optical films in which particle | grains were disperse | distributing efficiently can be obtained, and came to complete this invention.

  That is, the present invention provides at least one or more kinds of needle-like or spindle-like particles (A) having an optical anisotropy (A) of 5 to 50% by weight, transparent polymer (B) of 35 to 94.95% by weight, and polymer dispersion. It is related with the optical film obtained by processing the resin composition for optical films which consists of 0.05-15 weight% of agents (C), and this.

  The present invention is described in detail below.

  The needle-like or spindle-like particles (A) having optical anisotropy in the resin composition for an optical film of the present invention are preferably particles having negative optical anisotropy. Minerals such as calcium carbonate, magnesium carbonate, zirconium carbonate, strontium carbonate, cobalt carbonate, manganese carbonate; inorganic compounds such as ceramics and organic compounds such as styrene oligomers and oligomers of benzyl methacrylate, among which minerals, ceramics, etc. Inorganic compounds are preferable, and strontium carbonate, calcium carbonate, magnesium carbonate, cobalt carbonate, and manganese carbonate are particularly preferable. One or more kinds of these particles can be used.

  Further, the shape of the particles is preferably such that the ratio of the minor axis diameter to the major axis diameter (aspect ratio) is 1.5 or more, particularly 3 or more. Furthermore, the average dimension of the major axis diameter of the particles is preferably 50 nm or more and less than 400 nm, particularly preferably 50 nm or more and 300 nm or less, and more preferably 100 nm or less.

  The particles may be subjected to a surface treatment when dispersed in the transparent polymer. Examples of the surface treatment include fatty acid treatment, alkylammonium treatment, epoxy resin treatment, silane treatment, titanate treatment, and urethane treatment.

  The transparent polymer (B) in the present invention is preferably a transparent resin having positive birefringence, such as polycarbonate, polyarylate, polysulfone, polyethersulfone, polyimide, polyetherimide, polyethylene terephthalate, polyethylene naphthalate. Examples include phthalates, fluorene polyesters, fluorene polycarbonates, acrylic resins, cyclic polyolefins, maleimide copolymers, among which polycarbonates, polyarylates, polyether sulfones, cyclic polyolefins, maleimide copolymers are preferred, and polycarbonates are particularly preferred. Polyarylate and maleimide copolymer are preferred.

  Further, since the transparent polymer (B) becomes a resin composition for optical films having excellent heat resistance, the glass transition temperature (hereinafter referred to as Tg) is preferably 120 ° C. or higher, particularly 130 ° C. or higher. preferable.

  The polymer dispersant (C) in the present invention is blended for the purpose of improving the dispersibility of the needle-like or spindle-like particles having optical anisotropy in the solvent and the affinity for the transparent polymer. Polymer, phosphoric acid ester salt polymer, carboxylic acid polymer, carboxylate polymer, amine polymer, amine salt polymer, etc. Alternatively, phosphoric acid ester-based polymers, phosphoric acid ester-based polymers, carboxylic acid-based polymers, carboxylate-based polymers and the like are preferable because of excellent dispersibility of spindle-shaped particles. Products, carboxylic acid polymers, and amine polymers are preferred. One or more of these can be used. The molecular weight of the polymer dispersant (C) is preferably a weight average molecular weight of 500 to 30,000, particularly 1,000 to 20,000, because of excellent particle dispersibility and affinity for a transparent polymer. Preferably there is. As the polymer dispersant, commercially available products such as Disperbyk110, Disperbyk140 (manufactured by BYK-Chemie), Marialim AAB-0851 (manufactured by NOF Corporation) can be used.

  In the present invention, the blending ratio of the needle-like or spindle-like particles (A) having at least one type of optical anisotropy, the transparent polymer (B), and the polymer dispersant (C) is at least one type of optical. Anisotropy of needle-like or spindle-like particles (A) 5 to 50% by weight, transparent polymer (B) 35 to 94.95% by weight and polymer dispersant (C) 0.05 to 15% by weight Among them, for the purpose of controlling the optical anisotropy of the optical film resin composition, the blending amount of the acicular or spindle-shaped particles (A) having one or more kinds of optical anisotropy is 5 to 40% by weight. Particularly preferred is 5 to 20% by weight. The blending amount of the transparent polymer (B) is preferably 40 to 94.95% by weight, particularly preferably 50 to 94.25% by weight. The blending amount of the polymer dispersant is preferably 0.1 to 12% by weight.

  Moreover, since the compounding quantity of a polymer dispersing agent (C) can provide the birefringence stable to the resin composition for optical films obtained, the needle-shaped or spindle-shaped particle | grains (optical anisotropy ( The weight ratio of A) to the polymer dispersant (C) is preferably 3.3 to 100, and particularly preferably 5 to 20.

  As a method for producing the resin composition for an optical film of the present invention, for example, needle-like or spindle-like particles having optical anisotropy and a polymer dispersing agent are refined by stirring and mixing in a solvent, and reaggregation is performed. A method in which a transparent polymer or a solution prepared by dissolving a transparent polymer in a solvent is added to the resulting mixture and mixed by stirring (Manufacturing Method 1); a needle having optical anisotropy Alternatively, a method in which spindle-shaped particles are preliminarily treated with a polymer dispersant in a solvent and dried to disperse the prepared powder in a transparent resin monomer and polymerize (Production Method 2); Alternatively, a method in which spindle-shaped particles are preliminarily treated with a polymer dispersant in a solvent and dried to melt and knead the powder and the transparent polymer with an extruder, a roll or the like (production method 3); Can be mentioned.

  As a method of stirring and mixing in the production method 1, a widely known method can be used. For example, a homogenizer, a bead mill stirring device, a high-speed stirring mixer, a thin-film swirling mixer, or the like can be used.

  Further, the solution for dissolving the transparent polymer in the production method 1 is not particularly limited as long as the transparent polymer is dissolved, and examples thereof include toluene, methyl ethyl ketone (MEK), tetrahydrofuran (THF), chloroform, dichloromethane and the like. be able to.

  As the polymerization method in the production method 2, a known polymerization method can be used. For example, it can be produced by a bulk polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, or the like.

  As a method of melt kneading in production method 3, for example, melt kneading is performed under conditions of a temperature at which mixing and dispersion are possible and a shear rate condition using an apparatus such as a single screw kneading extruder, a twin screw kneading extruder, an internal mixer, or a planetary mixer. A method is mentioned.

  The resin composition for an optical film of the present invention may contain a plasticizer in order to improve the moldability of the film. Examples of the plasticizer include phthalates and polycondensates thereof, fatty acid esters such as adipic acid and polycondensates thereof, styrene polymers, acrylic polymers, terphenyl compounds and substituted derivatives thereof, among others. Particularly preferred are phthalates having a glass transition temperature of less than 100 ° C. and a molecular weight of less than 30,000, polycondensates of aliphatic esters such as adipic acid, styrenic and acrylic polymers, and copolymers thereof.

  The resin composition for an optical film of the present invention may contain an antioxidant or the like in order to increase the thermal stability of the film forming or the retardation film itself. Examples of the antioxidant include hindered phenol antioxidants, phosphorus antioxidants, and other antioxidants. These antioxidants may be used alone or in combination, and synergistically. It is preferable to use a hindered phenol-based antioxidant and a phosphorus-based antioxidant in combination because the antioxidant action is 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. Examples of the light stabilizer include a hindered amine light stabilizer, and a hindered amine light stabilizer having a molecular weight of 1,000 or more is preferable because it provides a resin composition for an optical film excellent in thermal coloring and light stabilization.

  Furthermore, the resin composition for an optical film of the present invention may contain an ultraviolet ray inhibitor in order to suppress ultraviolet ray deterioration of the film. Examples of the UV inhibitor include UV absorbers such as benzotriazole, benzophenone, triazine, and benzoate.

  The optical film resin composition of the present invention is preferably an optical film. Examples of methods for producing the optical film include needle-like or spindle-like particles (A) having optical anisotropy, and transparent polymers. (B) and a polymer dispersant (C) are dispersed and dissolved in a solvent, and this is formed into a film and dried to form a film (solution casting method); acicular or spindle-shaped particles having optical anisotropy (A ), A transparent polymer (B) and a polymer dispersant (C), a resin composition for optical films can be produced by a method of forming a film by melt extrusion (melt casting method). Moreover, the obtained film can be manufactured by extending | stretching this film to a uniaxial or biaxial or more as needed.

  More specifically, the solution casting method includes a method of obtaining a film by casting a dope solution on a support substrate and then removing the solvent by heating or the like. As a method for casting the dope, any method may 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, such as a glass film, a metal substrate, a plastic film such as a polyethylene terephthalate resin film, and the like. Can be used. Moreover, as a solvent to be used, it is sufficient that the transparent polymer can be dissolved, and examples thereof include toluene, methyl ethyl ketone (MEK), tetrahydrofuran (THF), chloroform, dichloromethane and the like.

  In order to form a film having high transparency, high thickness accuracy, and excellent surface smoothness by the solution casting method, the solution viscosity of the dope is preferably 700 to 30,000 cps, particularly 1,000 to 10,000 cps. Is preferred. Further, the film thickness when formed into a film by the solution casting method is preferably 10 to 500 μm, and particularly preferably 20 to 300 μm because it becomes an optical film excellent in mechanical properties and productivity.

  Further, in the melt casting method, more specifically, for example, a powder and transparency prepared by drying needle-shaped or spindle-shaped particles having optical anisotropy in advance in a solvent by treating with a polymer dispersant. Examples include a method in which a resin composition for an optical film made of a polymer is melted in an extruder and extruded from a narrow slit die such as a T die into a film, and then molded while being cooled with a cooling roll or air. At this time, the film thickness can be controlled with high accuracy by optimizing the flow path of the molten resin inside the die and controlling the clearance of the die lip.

  Thus, the obtained film can be made into the optical film by which the phase difference was controlled by extending | stretching to uniaxial or biaxial or more as needed. At that time, the stretching method may be any method as long as the film can be stretched. For example, the stretching process may be performed as a process connected to the T-die melt extrusion process, which is a melt casting method; A method of performing a stretching process as a step connected to the solution casting method; a method of performing a stretching process by a stretching apparatus after drying and winding.

  Examples of the film stretching method include uniaxial or biaxial stretching methods. Examples of the uniaxial stretching method include free width uniaxial stretching, a method of stretching with a tenter, a method of rolling and stretching with a calendar, and a roll. Examples of the biaxial stretching method include a method of stretching with a tenter, and a method of expanding and stretching in a tube shape. Further, a small stretching apparatus for experiments that enables these uniaxial and / or biaxial stretching can also be used. As stretching conditions in the stretching method, it is difficult to generate atsumi unevenness, and it becomes an optical film excellent in mechanical characteristics and optical characteristics, so that the glass transition temperature of the transparent polymer (B) is + 10 ° C. to + 40 ° C. Under the stretching temperature condition, the stretching ratio is preferably stretched in the range of 1.1 to 5 times.

  The in-plane retardation of the optical film may be appropriately selected according to the intended application, and is usually preferably 20 nm or more, particularly preferably 50 nm or more, and more preferably 80 nm or more. When used as a circularly polarizing film, the in-plane retardation of the film is preferably in the range of 100 to 200 nm, and when used as a half-wave film, the in-plane retardation of the film is in the range of 200 to 400 nm. It is preferable. The in-plane retardation of the film here is a value at a measurement wavelength of 589 nm.

  As the in-plane retardation of the film, of the two orthogonal axes in the film plane, the slow axis direction is the x axis, and the axis orthogonal to this is the y axis, and the refractive indexes corresponding to the respective axes are nx, ny When the film thickness is d, the in-plane retardation of the film Re = (nx−ny) × d.

  The wavelength dependence of the optical film is determined by measuring the phase difference at the reference wavelengths of 550 nm, 450 nm, and 630 nm, and the ratio of the phase difference of these reference wavelengths is Re (450) / Re (550), Re (630, respectively. ) / Re (550). When used as a quarter-wave plate or a half-wave plate, Re (450) / Re (550) is preferably 1.0 or less, particularly preferably 0.99, more preferably 0.98 or less. is there. Further, Re (650) / Re (550) is preferably 1.0 or more, and particularly preferably 1.01 or more.

  Furthermore, after the dope solution of the resin composition for an optical film of the present invention was allowed to stand at room temperature for 1 week, the in-plane retardation and wavelength dependence of the film of the optical film produced by the same method as described above were measured after 1 week. However, it has the characteristic that the change is small (excellent stability of the dope solution).

  The optical film of the present invention is preferably a retardation film since the in-plane retardation of the film is large and the wavelength dependency is small. The retardation film can be laminated with a polarizing plate to form an elliptical polarizing plate. In this case, the elliptically polarizing plate is useful for an antireflection film such as an organic EL display, a brightness enhancement film, and the like in addition to the reflective liquid crystal display. It can also laminate | stack with this retardation film or another retardation film. Further, a polarizing plate laminated with a polarizer made of a dichroic dye such as polyvinyl alcohol / iodine can be used, and a liquid crystal element using the retardation film as a plastic substrate can also be used. When laminating the retardation film, it may be bonded through an adhesive layer, and a known water-soluble or oil-soluble adhesive can be used as the adhesive layer.

  The resin composition for an optical film of the present invention is a resin composition for an optical film having excellent transparency obtained by blending optically anisotropic particles having a specific particle size at a high concentration and improving the dispersibility of the particles. There is an optical film with a large in-plane retardation and small wavelength dependency obtained by processing this film. Particularly, the retardation film is useful for an antireflection film such as a compensation film for liquid crystal displays and an organic EL display. is there.

  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 weight average molecular weight of polymer dispersant-
Using a gel permeation chromatography (GPC) apparatus (HLC8020 manufactured by Tosoh Corporation), chloroform was used as a solvent, and measurement was performed at 40 ° C. to obtain a standard polystyrene equivalent value.

~ Measurement of glass transition temperature ~
Using a differential scanning calorimeter (trade name DSC200, manufactured by Seiko Denshi Kogyo Co., Ltd.), the temperature rising rate was 10 ° C./min. Measured with

-Judgment of presence or absence of aggregates in film-
The presence or absence of agglomerated particles of several tens of μm was evaluated as a size that can be visually discriminated.

~ Measurement of light transmittance of film ~
Based on JIS-K-7361-1, it measured with the haze meter (Nippon Denshoku Industries Co., Ltd. make, brand name NDH-2000).

~ Measurement of retardation of film ~
Using an automatic birefringence meter (trade name KOBRA-WR, manufactured by Oji Scientific Instruments Co., Ltd.), the in-plane retardation Re of the film was measured and converted into an in-plane retardation of the film at a thickness of 60 μm.

  The wavelength dependence of the phase difference is measured by measuring the phase difference at the reference wavelengths of 550 nm, 450 nm and 630 nm, and the ratio of the phase difference of these reference wavelengths is Re (450) / Re (550), Re (630) / The wavelength dependence was determined by evaluating Re (550).

Example 1
89% by weight of dichloromethane, strontium carbonate particles exhibiting negative birefringence (stearic acid-treated product, average size of major axis system 250 nm, aspect ratio 3.5, average intrinsic birefringence = na − ((nb + nc) / 2) = -0.1475) A bead mill comprising a mixture of 10% by weight and 1% by weight of a phosphate ester-based polymer (BYK-Chemie, trade name Disperbyk-140 (weight average molecular weight 20,000)) as a polymer dispersant. A strontium carbonate dispersion was obtained by stirring using a stirrer.

  To this strontium carbonate dispersion, polycarbonate (manufactured by Teijin Chemicals, trade name Panlite, glass transition temperature 141 ° C.), strontium carbonate 20% by weight, polycarbonate 78% by weight, polymer dispersant (phosphate ester-based polymer) 2 The resin composition for an optical film was obtained by blending so as to have a weight%. Furthermore, the mixture which mix | blended 5 weight part of diethyl hexyl phthalates with respect to 100 weight part of this resin composition for optical films was obtained. A solution (dope solution) obtained by dissolving and dispersing this mixture in a dichloromethane solvent using a bead mill stirrer so as to be 25% by weight in a dichloromethane solvent was formed on a polyethylene terephthalate resin film, and then dried at 160 ° C. to form a film-like optical film. A resin composition for a film was obtained. The obtained film had a Tg of 157 ° C. The obtained film was stretched at 170 ° C. 2.0 times by free-width uniaxial stretching using a biaxial stretching apparatus (manufactured by Imoto Seisakusho, model 16A1) to obtain a film. The appearance of the obtained film was good, and no aggregate was confirmed.

  The obtained film had a total light transmittance of 90%. The in-plane retardation Re of the film was 85 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 0.97 and Re (630) / Re (550) = 1.01.

The appearance of the film formed and stretched in the same manner after 1 week from the dope solution was good, and no aggregates were observed. The total light transmittance was 90%. The in-plane retardation of the film is 85 nm, the wavelength dependence of the retardation is Re (450) / Re (550) = 0.97, Re (630) / Re (550) = 1.01, the in-plane retardation of the film and wavelength dependence did not change even after the lapse of one week.

  From these results, the obtained film is suitable for an optical film, particularly a retardation film, because the in-plane retardation of the film is large and the wavelength dependency is small.

Example 2
A film was obtained by carrying out the same operation except that the dissolution / dispersion apparatus in Example 1 was replaced with a TK-Robomix homogenizer manufactured by Primics instead of the bead mill stirring apparatus. The film appearance was good and no aggregates were observed.

  The total light transmittance of the obtained film was 89%. The in-plane retardation Re of the film was 80 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 0.97 and Re (630) / Re (550) = 1.00.

  The appearance of the film formed and stretched in the same manner after 1 week from the dope solution was good, and no aggregates were observed. The total light transmittance was 90%. In-plane retardation of the film Re80 nm, wavelength dependence of retardation Re (450) / Re (550) = 0.97, Re (630) / Re (550) = 1.00, in-plane retardation of the film and The wavelength dependence did not change even after 1 week.

  From these results, the obtained film is suitable for an optical film, particularly a retardation film, because the in-plane retardation of the film is large and the wavelength dependency is small.

Example 3
A film was obtained by carrying out the same operation except that the dissolving / dispersing apparatus of Example 1 was changed to a thin film swirl mixer (trade name: Filmics 56-50) manufactured by PRIMIX instead of the bead mill stirring apparatus. The film appearance was good and no aggregates were observed.

  The obtained film had a total light transmittance of 90%. The in-plane retardation Re of the film was 130 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 0.97 and Re (630) / Re (550) = 1.00.

  The appearance of the film formed and stretched in the same manner after 1 week from the dope solution was good, and no aggregates were observed. The total light transmittance was 90%. In-plane retardation Re of the film 130 nm, wavelength dependence of retardation Re (450) / Re (550) = 0.97, Re (630) / Re (550) = 1.00, in-plane retardation of the film and The wavelength dependence did not change even after 1 week.

  From these results, the obtained film is suitable for an optical film, particularly a retardation film, because the in-plane retardation of the film is large and the wavelength dependency is small.

Example 4
A film was obtained in the same manner as in Example 1 except that 40% by weight of strontium carbonate, 48% by weight of polycarbonate, and 12% by weight of the polymer dispersant were used. The film appearance was good and no aggregates were observed.

  The total light transmittance of the obtained film was 82%. The in-plane retardation Re of the film was 200 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 0.95 and Re (630) / Re (550) = 1.05.

  The appearance of the film formed and stretched in the same manner after 1 week from the dope solution was good, and no aggregates were observed. The total light transmittance was 80%. The in-plane retardation Re of the film is 180 nm, the wavelength dependency of the retardation is Re (450) / Re (550) = 0.96, Re (630) / Re (550) = 1.05, and the in-plane retardation of the film and The wavelength dependence hardly changed even after one week.

  From these results, the obtained film is suitable for an optical film, particularly a retardation film, because the in-plane retardation of the film is large and the wavelength dependency is small.

Example 5
In place of Disperbyk-140 manufactured by BYK-Chemie as a polymer dispersant of Example 1, a carboxylic acid polymer (manufactured by NOF Corporation, trade name Marialim AAB-0851 (weight average molecular weight 16,000)) was used, and strontium carbonate. A film was obtained by carrying out the same operation except that 10 wt%, polycarbonate 89.9 wt%, polymer dispersant 0.1 wt%, and diethylhexyl phthalate was not used.

  The obtained film had a total light transmittance of 90%. The in-plane retardation Re of the film was 80 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 1.00 and Re (630) / Re (550) = 1.00.

  The appearance of the film formed and stretched in the same manner after 1 week from the dope solution was good, and no aggregates were observed. The total light transmittance was 90%. The in-plane retardation Re of the film is 80 nm, the wavelength dependency of the retardation is Re (450) / Re (550) = 1.00, Re (630) / Re (550) = 1.00, the in-plane retardation of the film and The wavelength dependence did not change even after 1 week.

  From these results, the obtained film is suitable for an optical film, particularly a retardation film, because the in-plane retardation of the film is large and the wavelength dependency is small.

Example 6
In Example 1, instead of polycarbonate, N-methylmaleimide / isobutene copolymer (number average molecular weight 120,000, glass transition temperature 159 ° C.), as polymer dispersant, instead of Disperbyk-140 manufactured by BYK-Chemie An amine polymer (Disperbyk-112 manufactured by BYK-Chemie) (weight average molecular weight: 17,000) Chloroform was used in place of dichloromethane, and the same operation was carried out except that the stretching temperature was 200 ° C., to obtain a film.

  The total light transmittance of the obtained film was 88%. The in-plane retardation Re of the film was 120 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 0.95 and Re (630) / Re (550) = 1.02.

  The appearance of the film formed and stretched in the same manner after 1 week from the dope solution was good, and no aggregates were observed. The total light transmittance was 85%. In-plane retardation Re120 nm of film, wavelength dependence of retardation Re (450) / Re (550) = 0.95, Re (630) / Re (550) = 1.02, in-plane retardation of film and The wavelength dependence did not change even after 1 week.

  From these results, the obtained film is suitable for an optical film, particularly a retardation film, because the in-plane retardation of the film is large and the wavelength dependency is small.

Example 7
In Example 1, instead of polycarbonate, polyarylate (manufactured by Unitika, trade name U polymer P-3001, glass transition temperature 159 ° C.), as polymer dispersant, amine-based polymerization instead of BYK-Chemie Disperbyk-140 Product (BYK-Chemie Disperbyk-112 (weight average molecular weight 17,000), calcium carbonate instead of strontium carbonate (stearic acid-treated product, average size of major axis diameter 160 nm, aspect ratio 4.0, average intrinsic birefringence) = Na-((nb + nc) / 2) =-0.172), and a film was obtained by carrying out the same operation except that the stretching temperature was 200 ° C.

  The obtained film had a total light transmittance of 90%. The in-plane retardation Re of the film was 75 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 0.97 and Re (630) / Re (550) = 1.01.

  The appearance of the film formed and stretched in the same manner after 1 week from the dope solution was good, and no aggregates were observed. The total light transmittance was 88%. The in-plane retardation of the film is 75 nm, the wavelength dependence of the retardation is Re (450) / Re (550) = 0.97, Re (630) / Re (550) = 1.01, the in-plane retardation of the film and The wavelength dependence did not change even after 1 week.

  From these results, the obtained film is suitable for an optical film, particularly a retardation film, because the in-plane retardation of the film is large and the wavelength dependency is small.

Comparative Example 1
A film was obtained in the same manner as in Example 1 except that the polymer dispersant was not used and 20% by weight of strontium carbonate and 80% by weight of polycarbonate were used.

  Many agglomerated particles were confirmed in the obtained film.

The total light transmittance of the obtained film was 80%. The in-plane retardation Re of the film was −10 nm. The wavelength dependence of the phase difference is Re (450) / Re (550) = 1.05, Re (630) / Re (550) = 0.99.
A film in which the dope solution was formed in the same manner after one week had severe particle aggregation, and a uniform film could not be obtained.

  Since the polymer dispersant was not used, there were many aggregated particles, the in-plane retardation of the film was small, and it was not suitable for an optical film.

Comparative Example 2
The same operation was carried out except that a phosphoric acid ester dispersant (trade name Phosmer M (molecular weight: 271) manufactured by Unichemical Co., Ltd.) was used in place of Dispersbyk-140 manufactured by BYK-Chemie of the polymer dispersant of Example 1. To obtain a film.

  Although the obtained film appearance was good, aggregated particles were confirmed.

  The total light transmittance of the obtained film was 87%. The in-plane retardation Re of the film was 65 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 0.99 and Re (630) / Re (550) = 1.01.

  Many agglomerates were confirmed in the film formed in the same manner after 1 week from the dope solution. The total light transmittance was 85%. In-plane retardation Re30 nm of the film, wavelength dependence of retardation Re (450) / Re (550) = 1.03, Re (630) / Re (550) = 0.99, in-plane retardation of the film and The wavelength dependence changed greatly with the passage of one week.

  Since the phosphoric acid ester dispersant was used and the polymer dispersant was not used, there were many aggregated particles, the in-plane retardation of the film was small, and it was not suitable for an optical film.

Comparative Example 3
A film was obtained in the same manner as in Example 1 except that 40% by weight of strontium carbonate, 44% by weight of polycarbonate, and 16% by weight of the polymer dispersant were used.

  Although no aggregate was confirmed in the obtained film, the turbidity was severe.

  The total light transmittance of the obtained film was 80%. The in-plane retardation Re of the film was 30 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 1.01 and Re (630) / Re (550) = 0.99.

  Many agglomerates were confirmed in the film formed in the same manner after 1 week from the dope solution. The total light transmittance was 80%. The in-plane retardation Re of the film is 20 nm, the wavelength dependence of the retardation is Re (450) / Re (550) = 1.01, Re (630) / Re (550) = 0.99, and the in-plane retardation of the film and The wavelength dependence changed greatly with the passage of one week.

  Since the amount of the polymer dispersant is large, the aggregated particles are large, the in-plane retardation of the film is small, and it is not suitable for an optical film.

Comparative Example 4
A film was obtained in the same manner as in Example 1 except that strontium carbonate was 4% by weight, polycarbonate was 95.6% by weight, the polymer dispersant was 0.4% by weight, and diethylhexyl phthalate was not used. .

  The film appearance was good and no aggregates were observed.

  The total light transmittance of the obtained film was 92%. The in-plane retardation Re of the film was 20 nm. The wavelength dependence of the phase difference was Re (450) / Re (550) = 1.03 and Re (630) / Re (550) = 0.97.

  The appearance of the film formed in the same manner after one week from the dope solution was good, and no aggregates were confirmed. Further, the total light transmittance is 90%, the in-plane retardation Re of the film is 20 nm, the wavelength dependence of the retardation Re (450) / Re (550) = 1.03, Re (630) / Re (550) = 0.97, the in-plane retardation and wavelength dependence of the film varied greatly over the course of one week.

  The amount of optically anisotropic particles was small, the in-plane retardation of the film was small, and it was not suitable for an optical film.

Comparative Example 5
A film was obtained in the same manner as in Example 1 except that 55% by weight of strontium carbonate, 39.5% by weight of polycarbonate, and 5.5% by weight of the polymer dispersant were used.

  Aggregates were not confirmed in the obtained film appearance, but turbidity was exaggerated.

  Moreover, it was not possible to perform stretching.

  Due to the large amount of optically anisotropic particles, the molding processability was poor.

Claims (7)

5 to 50% by weight of particles (A) selected from the group consisting of acicular or spindle-shaped strontium carbonate, calcium carbonate, magnesium carbonate, cobalt carbonate, manganese carbonate having at least one kind of optical anisotropy, positive compound Transparent polymer (B) 35-94.95% by weight selected from the group consisting of polycarbonate, polyarylate, polyether sulfone, cyclic polyolefin, maleimide copolymer having refractive properties, and phosphate ester polymer, phosphoric acid From 0.05 to 15% by weight of a polymer dispersant (C) selected from the group consisting of ester salt polymer, carboxylic acid polymer, carboxylate polymer, amine polymer, and amine salt polymer. And the weight ratio of the needle-like or spindle-like particles (A) having optical anisotropy to the polymer dispersant (C) is 5 to 20. A beam for a resin composition, the ratio of the minor axis diameter and major axis diameter of the acicular or spindle-shaped particles having the optical anisotropy (A) (aspect ratio) is 3 or more, the average of the major axis diameter light optical film resin composition for you, wherein the dimension is less than or more 50 nm 300 nm. The resin composition for an optical film according to claim 1, wherein the transparent polymer (B) has a glass transition temperature of 120 ° C. or higher. An optical film comprising the resin composition for an optical film according to claim 1 . Disperse and dissolve the needle-like or spindle-like particles (A) having optical anisotropy, the transparent polymer (B), and the polymer dispersant (C) in a solvent, and form the film by drying and forming the film. The optical film according to claim 3 . Forming a resin composition for an optical film comprising needle-like or spindle-shaped particles (A) having optical anisotropy, a transparent polymer (B) and a polymer dispersant (C) by melt extrusion. The optical film according to claim 3 or 4 , characterized by the above. The optical film according to any one of claims 3 to 5 , wherein the optical film is stretched uniaxially or more. A retardation film comprising the optical film according to any one of claims 3 to 6 .