WO2022145169A1 - Film optique ainsi que procédé de fabrication de celui-ci, et plaque de polarisation - Google Patents

Film optique ainsi que procédé de fabrication de celui-ci, et plaque de polarisation Download PDF

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Publication number
WO2022145169A1
WO2022145169A1 PCT/JP2021/044208 JP2021044208W WO2022145169A1 WO 2022145169 A1 WO2022145169 A1 WO 2022145169A1 JP 2021044208 W JP2021044208 W JP 2021044208W WO 2022145169 A1 WO2022145169 A1 WO 2022145169A1
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Prior art keywords
film
optical film
polymer
birefringence
crystalline
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PCT/JP2021/044208
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English (en)
Japanese (ja)
Inventor
恭輔 井上
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日本ゼオン株式会社
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Priority to JP2022572946A priority Critical patent/JPWO2022145169A1/ja
Priority to CN202180085915.5A priority patent/CN116685610A/zh
Priority to KR1020237019618A priority patent/KR20230121743A/ko
Publication of WO2022145169A1 publication Critical patent/WO2022145169A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3083—Birefringent or phase retarding elements
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F12/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F12/02—Monomers containing only one unsaturated aliphatic radical
    • C08F12/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F12/06—Hydrocarbons
    • C08F12/08—Styrene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C08L101/12—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements

Definitions

  • the present invention relates to an optical film, a method for producing the same, and a polarizing plate.
  • Patent Documents 1 to 3 Conventionally, a film manufacturing technique using a resin has been proposed (Patent Documents 1 to 3).
  • a resin may be used to manufacture an optical film having anisotropy in the refractive index.
  • Such an optical film having anisotropy in the refractive index may have birefringence.
  • the optical film having birefringence can be provided in the display device as a film such as a reflection suppression film and a viewing angle compensation film.
  • the optical film When the optical film is provided in the display device, it is required to appropriately adjust the balance between the birefringence in the thickness direction and the birefringence in the in-plane direction perpendicular to the thickness direction.
  • the balance between the birefringence in the thickness direction and the birefringence in the in-plane direction can be expressed by the NZ coefficient of the optical film. For example, if an optical film having an NZ coefficient of more than 0.0 and less than 1.0 is obtained, the optical film makes it possible to improve the display quality when the display surface is viewed from an inclined direction.
  • the optical film is required to have reverse wavelength dispersibility.
  • An optical film having a reverse wavelength dispersibility can usually exhibit its optical function in a wide wavelength range.
  • a wave plate as an optical film having anti-wavelength dispersibility can be used as a wide-band wave plate capable of functioning in a wide wavelength range.
  • an optical film having an NZ coefficient of more than 0.0 and less than 1.0 Conventionally, a method for manufacturing an optical film having an NZ coefficient of more than 0.0 and less than 1.0 is known. Further, an optical film having a reverse wavelength dispersibility is conventionally known. However, it has not been conventionally achieved to realize an optical film having an NZ coefficient of more than 0.0 and less than 1.0 and having anti-wavelength dispersibility by a film having negative birefringence characteristics.
  • the present invention was devised in view of the above problems, and is an optic having a negative birefringence characteristic, a reverse wavelength dispersibility, and an NZ coefficient larger than 0.0 and less than 1.0. It is an object of the present invention to provide a film and a method for producing the same; and a polarizing plate provided with the above-mentioned optical film;
  • the present inventor has diligently studied to solve the above-mentioned problems. As a result, the present inventor has used a method including a step of bringing a resin film containing a crystalline polymer into contact with a solvent to change birefringence in the thickness direction and a step of stretching the resin film in this order. For example, they have found that the above-mentioned problems can be solved, and have completed the present invention. That is, the present invention includes the following.
  • An optical film containing a crystalline polymer The optical film has a negative birefringence characteristic and The in-plane retardations Re (450), Re (550) and Re (650) of the optical film at the measurement wavelengths of 450 nm, 550 nm and 650 nm satisfy the formula (1).
  • the optical film according to [1] wherein the optical film has a single-layer structure.
  • the crystalline polymer having a negative intrinsic birefringence is a polystyrene-based polymer.
  • a polarizing plate comprising the optical film according to any one of [1] to [8] and a polarizing film.
  • a step of preparing a resin film made of a resin containing a crystalline polymer having a negative intrinsic birefringence and a thermoplastic polymer having a positive intrinsic birefringence comprising the steps of stretching the resin film in this order.
  • a polarizing plate provided with an optical film; can be provided.
  • the birefringence in the in-plane direction of the film is a value represented by (nx-ny), and is therefore represented by Re / d, unless otherwise specified.
  • the birefringence in the thickness direction of the film is a value represented by [ ⁇ (nx + ny) / 2 ⁇ -nz], and is therefore represented by Rth / d, unless otherwise specified.
  • the NZ coefficient of the film is a value represented by (nx-nz) / (nx-ny) unless otherwise specified.
  • nx represents the refractive index in the direction perpendicular to the thickness direction of the film (in-plane direction) and in the direction giving the maximum refractive index.
  • ny represents the refractive index in the in-plane direction of the film and perpendicular to the direction of nx.
  • nz represents the refractive index in the thickness direction of the film.
  • d represents the thickness of the film.
  • the measurement wavelength is 550 nm unless otherwise specified.
  • the material having positive intrinsic birefringence means a material in which the refractive index in the stretching direction is larger than the refractive index in the direction perpendicular to it, unless otherwise specified. Therefore, a polymer having positive intrinsic birefringence means a polymer in which the refractive index in the stretching direction is larger than the refractive index in the direction perpendicular to the refractive index, unless otherwise specified.
  • the material having negative birefringence means a material in which the refractive index in the stretching direction is smaller than the refractive index in the direction perpendicular to the refractive index, unless otherwise specified. Therefore, a polymer having negative intrinsic birefringence means a polymer in which the refractive index in the stretching direction is smaller than the refractive index in the direction perpendicular to the refractive index, unless otherwise specified.
  • the "long" shape means a shape having a length of 5 times or more, preferably 10 times or more, and specifically a roll. It refers to the shape of a film that has a length that allows it to be rolled up and stored or transported. There is no particular limitation on the upper limit of the length, but it is usually 100,000 times or less with respect to the width.
  • the directions of the elements are "parallel”, “vertical” and “orthogonal”, and include errors within a range that does not impair the effect of the present invention, for example, within a range of ⁇ 5 °, unless otherwise specified. You may go out.
  • the angle formed by the optical axis (absorption axis, transmission axis, slow phase axis, etc.) of each film in the member including a plurality of films represents the angle when the film is viewed from the thickness direction.
  • the "polarizing plate”, “circular polarizing plate”, “wave plate” and “negative C plate” are not only rigid members but also flexible members such as resin films. Also includes. It was
  • optical film contains a crystalline polymer. This optical film meets the following requirements (A) to (C) in combination.
  • Requirement (A) The optical film has negative birefringence characteristics.
  • optical film has been difficult to manufacture in the past, but it can be easily manufactured when a specific manufacturing method described later is used.
  • the optical film according to this embodiment has a negative birefringence characteristic.
  • the film has negative birefringence characteristics means that when the film is stretched in one stretching direction, the amount of increase in the refractive index in the direction perpendicular to the stretching direction is larger than the amount of increase in the refractive index in the stretching direction. , Say big. Further, the film "has a positive birefringence characteristic” means that when the film is stretched in one stretching direction, the amount of increase in the refractive index in the stretching direction is the amount of increase in the refractive index in the direction perpendicular to the stretching direction. It means that it is bigger than.
  • the stretching direction is usually perpendicular to the thickness direction, and thus may be in-plane.
  • the birefringence characteristics of the optical film can be examined by stretching the optical film.
  • the birefringence characteristics of an optical film usually depend on the composition of the optical film. Therefore, when a resin film having the same composition as an optical film is stretched to produce an optical film as in the manufacturing method described later, the birefringence characteristics of the optical film are usually examined by stretching the resin film as well. be able to. Specifically, when the resin film is stretched in one stretching direction, if the amount of increase in the refractive index in the direction perpendicular to the stretching direction is larger than the amount of increase in the refractive index in the stretching direction, it is obtained from the resin film.
  • the birefringence characteristic of the optical film to be obtained can be negative.
  • the optical film of the present embodiment having a negative birefringence characteristic and an NZ coefficient satisfying the formula (2) is an optical film that has never existed before. Its industrial value is high.
  • the in-plane retardation Re (450) at a measurement wavelength of 450 nm, the in-plane retardation Re (550) at a measurement wavelength of 550 nm, and the in-plane retardation Re (650) at a measurement wavelength of 650 nm according to the present embodiment are Equation (1) is satisfied.
  • An optical film having an in-plane retardation satisfying the formula (1) usually has a reverse wavelength dispersibility. Therefore, the in-plane retardation of this optical film can be larger as the measurement wavelength is longer. Therefore, the optical film can exhibit its optical function in a wide wavelength range. For example, when the optical film can function as a 1/4 wave plate at one wavelength, the optical film can also function as a 1/4 wave plate in a wide wavelength range other than the one wavelength. Further, for example, when the optical film can function as a 1/2 wave plate at one wavelength, the optical film can also function as a 1/2 wave plate in a wide wavelength range other than the one wavelength.
  • NZ coefficient of optical film The NZ coefficient Nz of the optical film according to the present embodiment satisfies the formula (2).
  • the three-dimensional birefringence nx, ny and nz of the optical film having the NZ coefficient Nz satisfying this equation (2) can satisfy nx>nz> ny. 0 ⁇ Nz ⁇ 1 (2)
  • the NZ coefficient Nz of the optical film is usually greater than 0.0, preferably greater than 0.1, more preferably greater than 0.2, and usually less than 1.0, preferably less than 0.9. , More preferably less than 0.8.
  • An optical film having an NZ coefficient satisfying the formula (2) is not only in the polarized state of light passing through the optical film in the thickness direction, but also in the polarized state of light passing in an inclined direction that is neither parallel nor perpendicular to the thickness direction. Can be changed appropriately. Therefore, the optical film can exert its optical function not only for light in the thickness direction but also for light in the tilt direction. For example, when the optical film can give a phase difference of 1/4 wavelength to the light passing in the thickness direction, the optical film also gives a phase difference of 1/4 wavelength to the light passing in the tilt direction. sell. Further, for example, when the optical film can give a phase difference of 1/2 wavelength to the light passing in the thickness direction, the optical film has a phase difference of 1/2 wavelength to the light passing in the tilt direction. Can be given.
  • the optical film according to an embodiment of the present invention contains a crystalline polymer.
  • the crystalline polymer represents a polymer having crystallinity.
  • the crystalline polymer represents a polymer having a melting point Tm. That is, the crystalline polymer represents a polymer whose melting point Tm can be observed with a differential scanning calorimeter (DSC).
  • a resin containing a crystalline polymer may be referred to as a "crystalline resin”.
  • This crystalline resin is preferably a thermoplastic resin.
  • the optical film preferably contains a crystalline resin, and more preferably consists only of the crystalline resin.
  • the crystalline polymer preferably has a negative intrinsic birefringence.
  • a crystalline polymer having negative intrinsic birefringence When a crystalline polymer having negative intrinsic birefringence is stretched, it can exhibit a large refractive index in the direction perpendicular to the stretching direction. Therefore, when a crystalline polymer having a negative intrinsic birefringence is used, an optical film having a negative birefringence characteristic can be easily obtained. Further, when the crystalline polymer having negative intrinsic birefringence is used as described above, the in-plane retardation satisfying the formula (1) and the NZ coefficient satisfying the formula (2) can be easily achieved. ..
  • crystalline polystyrene-based polymer As the crystalline polymer having negative intrinsic birefringence, a polymer containing an aromatic ring is preferable, and examples thereof include polystyrene-based polymers.
  • the polystyrene-based polymer having crystallinity may be referred to as "crystalline polystyrene-based polymer”.
  • the crystalline polystyrene-based polymer can be a polymer of a styrene-based monomer. Therefore, the crystalline polystyrene-based polymer can be a polymer containing a structural unit having a structure formed by polymerizing a styrene-based monomer (hereinafter, appropriately referred to as “styrene-based unit”).
  • the styrene-based monomer may be an aromatic vinyl compound such as styrene or a styrene derivative.
  • the styrene derivative include compounds in which the benzene ring of styrene or the ⁇ -position or ⁇ -position is substituted with a substituent.
  • styrene-based monomer examples include styrene, alkylstyrene, halogenated styrene, halogenated alkylstyrene, alkoxystyrene, vinyl benzoic acid ester, and hydrogenated polymers thereof.
  • alkyl styrene examples include methyl styrene, ethyl styrene, isopropyl styrene, t-butyl styrene, 2,4-dimethyl styrene, phenyl styrene, vinyl naphthalene, and vinyl styrene.
  • halogenated styrene examples include chlorostyrene, bromostyrene, and fluorostyrene.
  • halogenated alkyl styrenes examples include chloromethyl styrene.
  • alkoxystyrene examples include methoxystyrene and ethoxystyrene.
  • styrene-based monomers styrene, methylstyrene, ethylstyrene, and 2,4-dimethylstyrene are preferable. Further, one type of styrene-based monomer may be used, or two or more types may be used in combination.
  • the crystalline polystyrene-based polymer preferably has an isotactic structure or a syndiotactic structure, and more preferably has a syndiotactic structure.
  • the fact that the crystalline polystyrene-based polymer has a syndiotactic structure means that the stereochemical structure of the crystalline polystyrene-based polymer has a syndiotactic structure.
  • the syndiotactic structure is a three-dimensional structure in which phenyl groups, which are side chains, are alternately located in opposite directions with respect to the main chain formed by a carbon-carbon bond in the Fischer projection formula. Compared with the polystyrene-based polymer having an atactic structure, the polystyrene-based polymer having a syndiotactic structure usually has a low specific density and is excellent in hydrolysis resistance, heat resistance and chemical resistance.
  • the tacticity of a crystalline polystyrene-based polymer can be quantified by a nuclear magnetic resonance method ( 13 C-NMR method) using isotope carbon.
  • 13 C-NMR method nuclear magnetic resonance method
  • the tacticity measured by the C-NMR method can be indicated by the abundance ratio of a plurality of consecutive constituent units. In general, for example, when there are two consecutive building blocks, it is a diad, when there are three, it is a triad, and when there are five, it is a pentad.
  • the crystalline polystyrene-based polymer having a syndiotactic structure may have a syndiotacticity of usually 75% or more, preferably 85% or more in diad (racemic diad), or pentad (racemic pen).
  • (Tad) may have a syndiotacticity of usually 30% or more, preferably 50% or more.
  • the crystalline polystyrene-based polymer may be a homopolymer or a copolymer. Therefore, the crystalline polystyrene-based polymer may be a homopolymer of one kind of styrene-based monomer, or may be a copolymer of two or more kinds of styrene-based monomers.
  • the ratio of each styrene-based unit to 100% by weight of the entire crystalline polystyrene-based polymer is preferably 5% by weight. As described above, it is more preferably 10% by weight or more, preferably 95% by weight or less, and more preferably 90% by weight or less.
  • the crystalline polystyrene-based polymer may be a copolymer of one or more types of styrene-based monomers and a monomer other than the styrene-based monomers.
  • the proportion of the styrene-based unit contained in the crystalline polystyrene-based polymer is preferably 80% by weight or more, more preferably 83% by weight or more, still more preferably 85% by weight or more from the viewpoint of obtaining an optical film having desired optical properties. Is.
  • the ratio of a certain structural unit contained in the crystalline polystyrene-based polymer can match the ratio of the monomer corresponding to the structural unit to all the monomers of the crystalline polystyrene-based polymer. Therefore, the ratio of the styrene-based unit contained in the crystalline polystyrene-based polymer may match the ratio of the styrene-based monomer to all the monomers of the crystalline polystyrene-based polymer.
  • the crystalline polystyrene-based polymer is obtained, for example, by polymerizing a styrene-based monomer in an inert hydrocarbon solvent or in the absence of a solvent, using a titanium compound and a condensation product of water and trialkylaluminum as a catalyst. It can be manufactured (see Japanese Patent Application Laid-Open No. 62-187708).
  • one type may be used alone, or two or more types may be used in combination at any ratio.
  • the weight average molecular weight Mw of the crystalline polymer is preferably 130,000 or more, more preferably 140,000 or more, particularly preferably 150,000 or more, preferably 500,000 or less, and more preferably 450,000 or less. Particularly preferably, it is 400,000 or less. Since the crystalline polymer having such a weight average molecular weight Mw can have a high glass transition temperature Tg, the heat resistance of the optical film can be enhanced.
  • the weight average molecular weight (Mw) of the polymer can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC) using 1,2,4-trichlorobenzene as a developing solvent.
  • the glass transition temperature Tg of the crystalline polymer is preferably 85 ° C. or higher, more preferably 90 ° C. or higher, and particularly preferably 95 ° C. or higher.
  • the glass transition temperature of the crystalline polymer is preferably 160 ° C. or lower, more preferably 155 ° C. or lower, and particularly preferably 150 ° C. or lower.
  • the melting point Tm of the crystalline polymer is preferably 200 ° C. or higher, more preferably 210 ° C. or higher, particularly preferably 220 ° C. or higher, preferably 300 ° C. or lower, more preferably 290 ° C. or lower, and particularly preferably 280 ° C. or lower. Is.
  • Tm of the crystalline polymer is within the above range, when the crystalline resin is molded to obtain a resin film, unintended progress of crystallization of the crystalline polymer and generation of foreign substances due to thermal decomposition are suppressed. can. Therefore, an optical film having good appearance and optical characteristics can be easily obtained.
  • the glass transition temperature Tg and melting point Tm of the polymer can be measured by the following methods. First, the polymer is melted by heating, and the melted polymer is rapidly cooled with dry ice. Subsequently, using this polymer as a test piece, the glass transition temperature Tg and melting point Tm of the polymer were measured at a heating rate of 10 ° C./min (heating mode) using a differential scanning calorimeter (DSC). Can be measured.
  • the amount of the crystalline polymer in 100% by weight of the crystalline resin is preferably 30% by weight or more, more preferably 40% by weight or more, and particularly preferably 45% by weight or more from the viewpoint of obtaining an optical film having desired optical properties. It is preferably 80% by weight or less, more preferably 70% by weight or less, and particularly preferably 65% by weight or less.
  • the crystallinity of the crystalline polymer contained in the optical film is usually higher than a certain level.
  • the specific range of crystallinity is preferably 10% or more, more preferably 15% or more, and particularly preferably 30% or more.
  • the crystallinity of the crystalline polymer can be measured by X-ray diffraction.
  • the crystalline resin may contain an amorphous polymer having no crystallinity in combination with the crystalline polymer.
  • a thermoplastic polymer is usually used. Above all, this amorphous thermoplastic polymer preferably has a positive intrinsic birefringence. When a polymer having positive intrinsic birefringence is used in combination with the above-mentioned crystalline polymer having negative intrinsic birefringence, the inverse wavelength dispersibility of the optical film can be easily obtained.
  • polyphenylene ether is preferable from the viewpoint of transparency and toughness.
  • Polyphenylene ethers can usually have excellent compatibility with crystalline polystyrene-based polymers.
  • Polyphenylene ether represents a polymer having a phenylene ether skeleton. Substituents may or may not be attached to the benzene ring of the phenylene ether skeleton. Polyphenylene ether usually has a phenylene ether skeleton in its backbone. As the polyphenylene ether, a polymer containing a phenylene ether unit represented by the following formula (I) is preferable.
  • Q 1 is independently a halogen atom, a lower alkyl group (for example, an alkyl group having 1 or more and 7 or less carbon atoms), a phenyl group, a haloalkyl group, an aminoalkyl group, a hydrocarbon oxy group, or Represents a halohydrocarbon oxy group (where the halogen atom and the oxygen atom are separated by at least two carbon atoms).
  • a halogen atom for example, an alkyl group having 1 or more and 7 or less carbon atoms
  • a phenyl group for example, an alkyl group having 1 or more and 7 or less carbon atoms
  • a phenyl group for example, a phenyl group, a haloalkyl group, an aminoalkyl group, a hydrocarbon oxy group, or Represents a halohydrocarbon oxy group (where the halogen atom and the oxygen atom are separated by at least two carbon atoms
  • Q 2 is independently a hydrogen atom, a halogen atom, a lower alkyl group (for example, an alkyl group having 1 or more and 7 or less carbon atoms), a phenyl group, a haloalkyl group, a hydrocarbon oxy group, or a halo.
  • a hydrocarbon oxy group where the halogen atom and the oxygen atom are separated by at least two carbon atoms.
  • a hydrogen atom is preferable as Q2 .
  • the polyphenylene ether may be a homopolymer having one kind of structural unit or a copolymer having two or more kinds of structural units.
  • the polymer containing the structural unit represented by the formula (I) is a homopolymer
  • a preferred example of the homopolymer is 2,6-dimethyl-1,4-phenylene ether unit ("-(”.
  • Examples thereof include homopolymers having a structural unit (represented by C 6 H 2 (CH 3 ) 2 -O)-”.
  • the polymer containing the structural unit represented by the formula (I) is a copolymer
  • preferred examples of the copolymer include 2,6-dimethyl-1,4-phenylene ether unit and 2,3. , 6-trimethyl-1,4-phenylene ether unit (structural unit represented by "-(C 6 H (CH 3 ) 3 -O-)-”) and a random copolymer having a combination thereof.
  • the polyphenylene ether may contain structural units other than the phenylene ether unit.
  • the polyphenylene ether can be a copolymer having a phenylene ether unit and other structural units.
  • the ratio of structural units other than the phenylene ether unit in the polyphenylene ether is preferably small as long as the desired optical properties can be obtained.
  • the content of the phenylene ether unit in 100% by weight of the polyphenylene ether is preferably 50% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, still more preferably 90% by weight or more. Particularly preferably, it is 95% by weight or more.
  • polyphenylene ethers having other substituents grafted on the polymer chain can also be mentioned.
  • Such polyphenylene ethers can be synthesized, for example, by grafting another substituent onto the polyphenylene ether by an appropriate method.
  • Specific examples include polyphenylene ether grafted with a polymer such as polystyrene, polybutadiene, or other vinyl-containing polymer.
  • polyphenylene ether may be produced by the method described in JP-A-11-302259.
  • amorphous polymer one type may be used alone, or two or more types may be used in combination at any ratio.
  • the weight average molecular weight Mw of the amorphous polymer such as polyphenylene ether is preferably 15,000 or more, more preferably 25,000 or more, particularly preferably 35,000 or more, and preferably 100,000 or less. It is preferably 85,000 or less, and particularly preferably 70,000 or less.
  • the weight average molecular weight Mw of the amorphous polymer is not more than the lower limit of the above range, the mechanical strength of the optical film can be increased. Further, when the weight average molecular weight Mw of the amorphous polymer is not more than the upper limit of the above range, the crystalline polymer and the amorphous polymer can be uniformly mixed at a high level.
  • the glass transition temperature of an amorphous polymer such as polyphenylene ether is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, particularly preferably 120 ° C. or higher, preferably 350 ° C. or lower, more preferably 300 ° C. or lower. Particularly preferably, it is 250 ° C. or lower.
  • the glass transition temperature of the amorphous polymer is at least the lower limit of the above range, the heat resistance of the optical film can be enhanced. Further, when the glass transition temperature of the amorphous polymer is not more than the upper limit of the above range, stretching in the manufacturing process of the optical film can be smoothly performed.
  • the amount of the amorphous polymer in 100% by weight of the crystalline resin is preferably 20% by weight or more, more preferably 30% by weight or more, and particularly preferably 35% by weight from the viewpoint of obtaining an optical film having desired optical properties. % Or more, preferably 70% by weight or less, more preferably 60% by weight or less, and particularly preferably 55% by weight or less.
  • the weight ratio (thermoplastic polymer / crystalline polymer) is , Preferably within a specific range. Specifically, the weight ratio (thermoplastic polymer / crystalline polymer) is preferably 3/7 or more, more preferably 3.5 / 6.5 or more, and particularly preferably 4/6 or more. Is 8/2 or less, more preferably 7.5 / 2.5 or less, and particularly preferably 7/3 or less.
  • the weight ratio (thermoplastic polymer / crystalline polymer) is in the above range, the inverse wavelength dispersibility of the optical film can be easily obtained.
  • the crystalline resin may contain any component in combination with the above-mentioned crystalline polymer and amorphous polymer.
  • Optional components include, for example, lubricants; layered crystal compounds; fine particles such as inorganic fine particles; antioxidants, heat stabilizers, light stabilizers, weathering stabilizers, ultraviolet absorbers, stabilizers such as near-infrared absorbers; plastics. Agents; colorants such as dyes and pigments; antistatic agents; and the like. Any component may be used alone or in combination of two or more. The amount of any component can be appropriately determined as long as the effect of the present invention is not significantly impaired. The amount of any component may be, for example, in the range where the total light transmittance of the optical film can be maintained at 85% or more.
  • the optical film may have a multi-layer structure including a plurality of layers, but preferably has a single-layer structure.
  • the single-layer structure represents a structure having only a single layer having the same composition and not having a layer having a composition different from the above-mentioned composition. Therefore, it is preferable that the optical film has a single layer formed of the crystalline resin.
  • the optical film preferably has an in-plane retardation in an appropriate range according to the application.
  • the specific in-plane retardation Re of the optical film may be preferably 100 nm or more, more preferably 110 nm or more, particularly preferably 120 nm or more, and preferably 180 nm or less, more preferably 170 nm or less at a measurement wavelength of 550 nm. Particularly preferably, it may be 160 nm or less.
  • the optical film can function as a 1/4 wave plate.
  • the specific in-plane retardation Re of the optical film may be preferably 245 nm or more, more preferably 265 nm or more, particularly preferably 270 nm or more, and preferably 320 nm or less, more preferably 300 nm at a measurement wavelength of 550 nm.
  • it may be particularly preferably 295 nm or less.
  • the optical film can function as a 1/2 wave plate.
  • the film retardation can be measured using a phase difference meter (for example, "AXoScan OPMF-1" manufactured by AXOMETRICS).
  • a phase difference meter for example, "AXoScan OPMF-1" manufactured by AXOMETRICS.
  • the optical film preferably has high transparency.
  • the specific total light transmittance of the optical film is preferably 80% or more, more preferably 85% or more, and particularly preferably 88% or more.
  • the total light transmittance of the film can be measured in the wavelength range of 400 nm to 700 nm using an ultraviolet / visible spectrometer.
  • the optical film preferably has a small haze.
  • the haze of the optical film is preferably less than 1.0%, more preferably less than 0.8%, particularly preferably less than 0.5%, ideally 0.0%.
  • the haze of the film can be measured using a haze meter (for example, "NDH5000" manufactured by Nippon Denshoku Kogyo Co., Ltd.).
  • the optical film may contain a solvent.
  • This solvent may be incorporated into the film in the step of bringing the resin film into contact with the solvent in the production method described later. Specifically, all or part of the solvent incorporated into the film upon contact with the resin film can enter the interior of the polymer. Therefore, it is difficult to completely remove the solvent even if the drying is performed above the boiling point of the solvent. Therefore, the optical film may contain a solvent.
  • the optical film is preferably a stretched film.
  • the stretched film represents a film produced through a stretching treatment.
  • the optical film is preferably a uniaxially stretched film.
  • the uniaxially stretched film represents a film that is positively stretched only in one direction and is not positively stretched in any other direction. Since the uniaxially stretched film can be manufactured by stretching in only one direction, the manufacturing process can be simplified, and thus simple manufacturing can be realized.
  • the optical film may be a single-wafer film or a long film having a long shape.
  • the optical film has a long shape, it is possible to continuously manufacture a polarizing plate by laminating the optical film and the long polarizing film.
  • the thickness of the optical film can be set appropriately according to the application of the optical film.
  • the specific thickness of the optical film is preferably 5 ⁇ m or more, more preferably 10 ⁇ m or more, particularly preferably 30 ⁇ m or more, preferably 400 ⁇ m or less, more preferably 300 ⁇ m or less, and particularly preferably 200 ⁇ m or less.
  • the above-mentioned optical film is The step (i) of preparing a resin film made of a crystalline resin containing a crystalline polymer having a negative intrinsic birefringence and a thermoplastic polymer having a positive intrinsic birefringence; The step (ii) of bringing the resin film into contact with a solvent to change the birefringence in the thickness direction; The step of stretching the resin film (iii) and Can be manufactured by a manufacturing method containing the above in this order.
  • the resin film before being brought into contact with the solvent in step (ii) is referred to as "raw film”, and the resin film after being brought into contact with the solvent in step (ii) is referred to as "pre-stretched film”. ".
  • the present inventor presumes that the mechanism for obtaining the above-mentioned optical film by the above-mentioned manufacturing method is as follows. However, the technical scope of the present invention is not limited by the following mechanism.
  • an optical film is manufactured using a resin film containing a crystalline polymer having a negative intrinsic birefringence.
  • a crystalline polymer having a negative intrinsic birefringence When a crystalline polymer having a negative intrinsic birefringence is oriented in a certain orientation direction, it can exhibit a small refractive index in the orientation direction and a large refractive index in the direction perpendicular to the orientation direction. Therefore, the resin film and the optical film containing this crystalline polymer can have negative birefringence characteristics as represented by the requirement (A).
  • the optical film may contain a thermoplastic polymer having a positive intrinsic birefringence in combination with a crystalline polymer having a negative intrinsic birefringence.
  • a thermoplastic polymer having positive intrinsic birefringence When oriented in a certain orientation direction, a large refractive index may be developed in the orientation direction, and a small refractive index may be developed in the direction perpendicular to the orientation direction. Therefore, when oriented in a certain orientation direction, the direction in which the refractive index of the crystalline polymer is maximized and the direction in which the refractive index of the thermoplastic polymer is maximized can be perpendicular to each other.
  • the entire birefringence of the optical film containing the combination of the crystalline polymer and the thermoplastic polymer may reflect the difference between the birefringence of the crystalline polymer and the birefringence of the thermoplastic polymer.
  • the difference between the birefringence of the crystalline polymer and the birefringence of the thermoplastic polymer is small at a short measurement wavelength and large at a long measurement wavelength. Therefore, the optical film obtained by the above-mentioned manufacturing method can have a reverse wavelength dispersibility as represented by the requirement (B).
  • the solvent infiltrates into the raw fabric film.
  • the action of the infiltrated solvent causes microBrownian motion in the molecules of the crystalline polymer in the film, and the molecular chains are oriented. According to the study of the present inventor, it is considered that the solvent-induced crystallization phenomenon of the crystalline polymer may proceed when the molecular chain is oriented.
  • the surface area of the film is large on the front surface and the back surface, which are the main surfaces. Therefore, as for the infiltration rate of the solvent, the infiltration rate in the thickness direction through the front surface or the back surface is high. Then, the orientation of the molecules of the crystalline polymer can proceed so that the molecules of the polymer are oriented in the thickness direction. Therefore, in the step (ii), the molecules of the crystalline polymer can be oriented in the thickness direction.
  • the pre-stretched film as a resin film in which the molecules of the crystalline polymer are oriented in the thickness direction in the step (ii) is stretched in the step (iii).
  • the molecules of the polymer contained in the pre-stretched film can be oriented in a direction perpendicular to the thickness direction. Therefore, by combining the orientation in the thickness direction in the step (iii) and the orientation in the direction perpendicular to the thickness direction in the step (iii), the orientation direction of the polymer molecules can be three-dimensionally adjusted. can. Therefore, the optical film obtained by the above-mentioned manufacturing method can have an NZ coefficient in an appropriate range as represented by the requirement (C).
  • Step of preparing a resin film includes a step of preparing a raw film as a resin film before contacting with a solvent.
  • a crystalline resin containing a crystalline polymer can be used as the material of the raw film prepared in the step (i).
  • the raw film is preferably made of only crystalline resin.
  • the crystalline resin contained in the raw film may be the same as the crystalline resin contained in the optical film.
  • the crystallinity of the crystalline polymer contained in the raw film is preferably small.
  • the specific crystallinity is preferably less than 10%, more preferably less than 5%, and particularly preferably less than 3%. If the crystallinity of the crystalline polymer contained in the raw film before contact with the solvent is low, many molecules of the crystalline polymer can be oriented in the thickness direction by contact with the solvent, so that in a wide range.
  • the NZ coefficient can be adjusted.
  • the raw film preferably has optical isotropic properties. Therefore, the raw film preferably has a small birefringence Re / d in the in-plane direction, and preferably has a small absolute value
  • the birefringence Re / d of the raw film in the in-plane direction is preferably less than 1.0 ⁇ 10 -3 , more preferably less than 0.5 ⁇ 10 -3 , and particularly preferably 0.3 ⁇ . It is less than 10 -3 .
  • of the birefringence in the thickness direction of the raw film is preferably less than 1.0 ⁇ 10 -3 , more preferably less than 0.5 ⁇ 10 -3 , and particularly preferably 0.3. It is less than ⁇ 10 -3 .
  • Having optical isotropic properties as described above indicates that the molecular orientation of the crystalline polymer contained in the raw film is low and is substantially non-oriented.
  • the raw film preferably has a small solvent content, and more preferably does not contain a solvent.
  • the ratio (solvent content) of the solvent contained in the raw film to 100% by weight of the raw film is preferably 1% or less, more preferably 0.5% or less, and particularly preferably 0.1% or less. Ideally, it is 0.0%. Since the amount of the solvent contained in the raw film before contact with the solvent is small, many molecules of the crystalline polymer can be oriented in the thickness direction by the contact with the solvent, so that the NZ coefficient can be adjusted in a wide range. Is possible.
  • the solvent content of the raw film can be measured by the density.
  • the haze of the raw film is preferably less than 1.0%, preferably less than 0.8%, more preferably less than 0.5%, and ideally 0.0%.
  • the thickness of the raw film is set according to the thickness of the optical film to be manufactured.
  • the thickness is increased by contacting with the solvent in the step (ii).
  • the thickness becomes smaller. Therefore, the thickness of the raw film may be set in consideration of the change in thickness in the step (ii) and the step (iii) as described above.
  • the raw film may be a single-wafer film, but it is preferably a long film.
  • a long raw film it is possible to continuously produce an optical film by a roll-to-roll method, so that the productivity of the optical film can be effectively increased.
  • a method for producing the raw fabric film since a raw fabric film containing no solvent can be obtained, an injection molding method, an extrusion molding method, a press molding method, an inflation molding method, a blow molding method, a calendar molding method, and a casting molding method.
  • a resin molding method such as a compression molding method is preferable.
  • the extrusion molding method is preferable because the thickness can be easily controlled.
  • the manufacturing conditions in the extrusion molding method are preferably as follows.
  • the cylinder temperature (molten resin temperature) is preferably Tm or higher, more preferably “Tm + 20 ° C” or higher, preferably “Tm + 100 ° C” or lower, and more preferably “Tm + 50 ° C” or lower.
  • the cooling body that the molten resin extruded into a film comes into contact with first is not particularly limited, but a cast roll is usually used.
  • the cast roll temperature is preferably "Tg-50 ° C.” or higher, preferably "Tg + 70 ° C.” or lower, and more preferably "Tg + 40 ° C.” or lower.
  • the raw fabric film When the raw fabric film is manufactured under such conditions, the raw fabric film having a thickness of 1 ⁇ m to 1 mm can be easily manufactured.
  • Tm represents the melting point of the crystalline polymer
  • Tg represents the glass transition temperature of the crystalline polymer.
  • the method for producing an optical film includes a step (ii) in which a resin film as a raw film is brought into contact with a solvent after the step (i). By this step (ii), the birefringence in the thickness direction of the raw film is changed, and a pre-stretched film having a birefringence in the thickness direction different from that of the raw film is obtained.
  • an organic solvent is usually used.
  • a solvent that can penetrate into the resin film without dissolving the crystalline polymer contained in the resin film can be used, and for example, a hydrocarbon solvent such as cyclohexane, toluene, limonene, and decalin can be used. ; Carbon disulfide;
  • the type of the solvent may be one type or two or more types.
  • the contact method between the resin film and the solvent there are no restrictions on the contact method between the resin film and the solvent.
  • Examples of the contact method include a spray method in which a solvent is sprayed on a resin film; a coating method in which a solvent is applied to a resin film; a dipping method in which a resin film is immersed in a solvent; and the like. Above all, the dipping method is preferable because continuous contact can be easily performed.
  • the temperature of the solvent in contact with the resin film is arbitrary as long as the solvent can maintain the liquid state, and therefore can be set in the range of the melting point or more and the boiling point or less of the solvent.
  • the contact time is preferably 0.5 seconds or longer, more preferably 1.0 seconds or longer, and particularly preferably 5.0 seconds or longer.
  • the upper limit is not particularly limited and may be, for example, 24 hours or less. However, since the degree of progress of orientation tends not to change significantly even if the contact time is lengthened, it is preferable that the contact time is short as long as the desired optical characteristics can be obtained.
  • the birefringence Rth / d in the thickness direction of the resin film changes.
  • the amount of change in birefringence Rth / d in the thickness direction caused by contact with the solvent is preferably 0.1 ⁇ 10 -3 or more, more preferably 0.2 ⁇ 10 -3 or more, and particularly preferably 0.3 ⁇ 10 It is -3 or more, preferably 50.0 ⁇ 10 -3 or less, more preferably 30.0 ⁇ 10 -3 or less, and particularly preferably 20.0 ⁇ 10 -3 or less.
  • the amount of change in the birefringence Rth / d in the thickness direction represents an absolute value of the change in the birefringence Rth / d in the thickness direction of the resin film.
  • the specific amount of change in the birefringence Rth / d in the thickness direction is obtained by subtracting the birefringence Rth / d in the thickness direction of the original film from the birefringence Rth / d in the thickness direction of the unstretched film and obtaining it as an absolute value. Be done.
  • the birefringence Rth / d in the thickness direction is increased by contact between the resin film and the solvent.
  • the birefringence Re / d in the in-plane direction of the resin film may or may not change due to contact with the solvent. From the viewpoint of simplifying the control of the in-plane retardation Re of the optical film, it is preferable that the change in the birefringence Re / d in the in-plane direction caused by the contact with the solvent is small, and it is more preferable that the change does not occur. preferable.
  • the amount of change in birefringence Re / d in the in-plane direction caused by contact with the solvent is preferably 0.0 ⁇ 10 -3 to 0.2 ⁇ 10 -3 , more preferably 0.0 ⁇ 10 -3 to 0.
  • the amount of change in the birefringence Re / d in the in-plane direction represents an absolute value of the change in the birefringence Re / d in the in-plane direction of the resin film.
  • the specific amount of change in the in-plane birefringence Re / d is obtained by subtracting the in-plane birefringence Re / d of the raw film from the in-plane birefringence Re / d of the unstretched film. Obtained as a value.
  • the pre-stretched film as the resin film after contact with the solvent is a negative C plate. Therefore, it is preferable that the refractive index nz in the thickness direction of the unstretched film is smaller than the refractive indexes nx and ny in the in-plane direction. Further, it is preferable that the refractive indexes nx and ny in the in-plane direction of the unstretched film are the same value or close to each other.
  • the difference between the refractive index nx and the refractive index ny is relatively small, the difference between the refractive index nz and the refractive index nz is relatively large, and the difference between the refractive index ny and the refractive index nz is relatively large. It is preferably relatively large.
  • the difference between the rate nz and the in-plane refractive indexes nx and ny can be expressed.
  • the birefringence Rth / d in the thickness direction of the unstretched film is preferably 0.05 ⁇ 10 -3 or more, preferably 0.1 ⁇ 10 -3 or more, and particularly preferably 0.2 ⁇ 10 -3 or more. It is preferably 10 ⁇ 10 -3 or less, more preferably 6.0 ⁇ 10 -3 or less, and particularly preferably 4.0 ⁇ 10 -3 or less.
  • the birefringence Re / d in the in-plane direction of the pre-stretched film may be smaller than the birefringence Rth / d in the thickness direction of the pre-stretched film.
  • the specific range of birefringence Re / d in the in-plane direction of the unstretched film is preferably 0.01 ⁇ 10 -3 or more, preferably 0.05 ⁇ 10 -3 or more, and particularly preferably 0.1 ⁇ 10. It is -3 or more, preferably 1.0 ⁇ 10 -3 or less, more preferably 0.5 ⁇ 10 -3 or less, and particularly preferably 0.2 ⁇ 10 -3 or less.
  • the pre-stretched film as the resin film after contact with the solvent has an NZ coefficient greater than 1.0.
  • the specific NZ coefficient of the pre-stretched film is preferably greater than 1.0, more preferably greater than 5.0, particularly preferably greater than 10, and preferably less than 50, more preferably less than 40, particularly preferred. Is less than 30.
  • the thickness of the resin film is usually increased due to the infiltration of the solvent in contact with the resin film into the resin film.
  • the lower limit of the rate of change in the thickness of the resin film at this time may be, for example, 1% or more, 2% or more, or 3% or more.
  • the upper limit of the change rate of the thickness may be, for example, 80% or less, 50% or less, or 40% or less.
  • the rate of change in the thickness of the resin film is a ratio obtained by dividing the difference in thickness between the raw film and the unstretched film by the thickness of the raw film.
  • the method for producing an optical film includes a step (iii) of stretching a resin film as a pre-stretching film after the step (iii).
  • the molecules of the polymer contained in the resin film can be oriented in a direction corresponding to the stretching direction. Therefore, according to the stretching in the step (iii), the in-plane birefringence Re / d, the in-plane retardation Re, the thickness direction birefringence Rth / d, the thickness direction birefringence Rth, and the NZ coefficient
  • the above-mentioned optical film can be obtained by adjusting the optical characteristics such as.
  • the stretching direction there is no limitation on the stretching direction, and examples thereof include a longitudinal direction, a width direction, and an oblique direction.
  • the diagonal direction is a direction perpendicular to the thickness direction and is neither parallel nor perpendicular to the width direction.
  • the stretching direction may be one direction or two or more directions, but one direction is preferable. Further, among the stretching in one direction, free uniaxial stretching in which no binding force is applied in a direction other than the stretching direction is further preferable. According to these stretchings, the above-mentioned optical film can be easily manufactured.
  • the pre-stretched film usually has negative birefringence characteristics
  • an optical film having a slow axis in the direction perpendicular to the stretching direction can be obtained. Therefore, since the slow phase axis direction of the optical film can be adjusted by the stretching direction, the stretching direction may be selected according to the direction of the slow phase axis to be expressed in the optical film.
  • a long polarizing film has an absorption axis in its longitudinal direction and a transmission axis in its width direction.
  • the pre-stretched film is stretched in the longitudinal direction to obtain an optical film having a slow phase axis in the width direction. You may get it. In this case, it is possible to efficiently manufacture a polarizing plate by roll-to-roll using a long optical film and a long polarizing film.
  • the draw ratio is preferably 1.1 times or more, more preferably 1.2 times or more, preferably 20.0 times or less, more preferably 10.0 times or less, still more preferably 5.0 times or less, particularly. It is preferably 2.0 times or less. It is desirable to appropriately set the specific draw ratio according to factors such as the optical characteristics, thickness, and mechanical strength of the optical film to be manufactured.
  • the stretching ratio is equal to or higher than the lower limit of the above range, the birefringence can be significantly changed by stretching. Further, when the draw ratio is not more than the upper limit of the above range, the direction of the slow phase axis can be easily controlled and the film breakage can be effectively suppressed.
  • the stretching temperature is preferably "Tg R " or higher, more preferably “Tg R + 10 ° C” or higher, preferably “Tg R + 100 ° C” or lower, and more preferably “Tg R + 90 ° C” or lower.
  • Tg R represents the glass transition temperature of the crystalline resin.
  • the stretching temperature is equal to or higher than the lower limit of the above range, the resin film can be sufficiently softened and stretched uniformly. Further, when the stretching temperature is not more than the upper limit of the above range, the curing of the resin film due to the progress of crystallization of the crystalline polymer can be suppressed, so that the stretching can be smoothly performed, and the stretching causes a large birefringence. Can be expressed. In addition, the haze of the resulting optical film can usually be reduced to increase transparency.
  • an optical film can be obtained as a stretched resin film.
  • the balance between the birefringence Rth / d in the thickness direction and the birefringence Re / d in the in-plane direction can be adjusted to obtain a desired NZ coefficient. ..
  • the optical properties such as retardation are exhibited by the orientation of the polymer due to the contact with the solvent in the step (iii) and the orientation of the polymer due to the stretching in the step (iii), so that the optical film is desired. It can have optical properties.
  • the method for producing an optical film may be combined with the above-mentioned steps (i) to (iii) and further include any step.
  • a step of preheating the pre-stretched film before the step (iii) a step of heat-treating the optical film obtained in the step (iii) to promote the crystallization of the crystalline polymer, and the like.
  • Examples thereof include a step of drying the optical film to reduce the amount of the solvent in the film, a step of heat-shrinking the optical film to remove residual stress in the film, and the like.
  • a long optical film can be manufactured by using a long raw film.
  • the method for producing an optical film may include a step of winding the long optical film thus produced into a roll shape. Further, the method for producing an optical film may include a step of cutting a long optical film into a desired shape.
  • the polarizing plate according to the embodiment of the present invention includes the above-mentioned optical film and a polarizing film.
  • the polarizing film can usually function as a linear splitter. Therefore, the polarizing plate can transmit a part of the polarized light and block the other polarized light.
  • the polarizing film usually has an absorption axis and a transmission axis perpendicular to the absorption axis. Then, it is possible to absorb the linear polarization having a vibration direction parallel to the absorption axis and transmit the linear polarization having a vibration direction parallel to the transmission axis.
  • the vibration direction of linearly polarized light means the vibration direction of the electric field of linearly polarized light. At this time, it is preferable that the absorption axis of the polarizing film and the slow axis of the optical film form a specific angle.
  • the angle formed by the absorption axis of the polarizing film and the slow axis of the optical film is preferably 80 ° or more, more preferably 85 ° or more, particularly preferably 88 ° or more, and preferably 100 ° or less. It is more preferably 95 ° or less, and particularly preferably 92 ° or less.
  • the optical film preferably has an in-plane retardation that can function as a 1/2 wave plate.
  • the polarizing plate according to this example can be used as a polarizing plate capable of compensating the viewing angle when provided in an image display device.
  • the angle formed by the absorption axis of the polarizing film and the slow axis of the optical film is preferably 40 ° or more, more preferably 42 ° or more, particularly preferably 44 ° or more, and preferably 50 °. Below, it is more preferably 48 ° or less, and particularly preferably 46 ° or less.
  • the optical film preferably has an in-plane retardation that can function as a 1/4 wave plate.
  • the polarizing plate according to this example can be used as a circular polarizing plate capable of transmitting circular polarization in one rotation direction and blocking circular polarization in the other rotation direction. By providing this circularly polarizing plate on the display surface of the display device, it is possible to suppress the reflection of external light. It was
  • any polarizing film can be used as the polarizing film.
  • An example of a polarizing film is a film obtained by adsorbing iodine or a dichroic dye on a polyvinyl alcohol film and then uniaxially stretching it in a boric acid bath; adsorbing iodine or a dichroic dye on the polyvinyl alcohol film. Examples thereof include a film obtained by stretching and further modifying a part of polyvinyl alcohol units in the molecular chain to polyvinylene units. Of these, the polarizing film preferably contains polyvinyl alcohol. It was
  • the degree of polarization of this polarizing film is not particularly limited, but is preferably 98% or more, more preferably 99% or more.
  • the thickness of the polarizing film is preferably 5 ⁇ m to 80 ⁇ m. It was
  • the above-mentioned polarizing plate may further include an arbitrary layer.
  • the optional layer may be, for example, a polarizing element protective film layer; an adhesive layer for bonding a polarizing film and an optical film; a hard coat layer such as an impact-resistant polymethacrylate resin layer; a matte layer for improving the slipperiness of the film; Examples thereof include a reflection suppressing layer; an antifouling layer; an antistatic layer; and the like. Any of these layers may be provided with only one layer, or may be provided with two or more layers.
  • the glass transition temperature Tg and the melting point Tm of the polymer were measured as follows. First, the polymer was melted by heating, and the melted polymer was rapidly cooled with dry ice. Subsequently, using this polymer as a test piece, the glass transition temperature Tg and melting point Tm of the polymer were measured at a heating rate of 10 ° C./min (heating mode) using a differential scanning calorimeter (DSC). It was measured.
  • the weight average molecular weight of this polymer was measured by gel permeation chromatography at 135 ° C. using 1,2,4-trichlorobenzene as a solvent. As a result, the weight average molecular weight Mw of this polymer was 350,000. Further, it was confirmed by measuring the melting point Tm and 13 C-NMR that the obtained polymer was crystalline polystyrene having a syndiotactic structure. The melting point Tm of crystalline polystyrene was 270 ° C., and the glass transition temperature was 100 ° C. By repeating this operation, crystalline polystyrene having the syndiotactic structure required for evaluation was prepared.
  • 0.014 parts of the tetrachlorotungsten phenylimide (tetrahydrofuran) complex was dissolved in 0.70 parts of toluene to prepare a solution.
  • 0.061 part of a diethylaluminum ethoxide / n-hexane solution having a concentration of 19% was added and stirred for 10 minutes to prepare a catalytic solution.
  • This catalyst solution was added to a pressure resistant reactor to initiate a ring-opening polymerization reaction. Then, the reaction was carried out for 4 hours while maintaining 53 ° C. to obtain a solution of a ring-opening polymer of dicyclopentadiene.
  • the number average molecular weight (Mn) and weight average molecular weight (Mw) of the obtained ring-opening polymer of dicyclopentadiene are 8,750 and 28,100, respectively, and the molecular weight distribution (Mw / Mn) obtained from these. was 3.21.
  • the hydride and the solution contained in the reaction solution were separated using a centrifuge and dried under reduced pressure at 60 ° C. for 24 hours to open dicyclopentadiene as a crystalline polymer having positive intrinsic birefringence. 28.5 parts of the hydride of the ring polymer was obtained.
  • the hydrogenation rate of this hydride was 99% or more, the glass transition temperature Tg was 93 ° C., the melting point Tm was 262 ° C., and the ratio of racemo diad was 89%.
  • Crystalline resin pellets are melt-extruded using a thermal melt extrusion film forming machine equipped with a T-die (“Measuring Extruder Type Me-20 / 2800V3” manufactured by Optical Control Systems) and rolled at a speed of 1.5 m / min. A long raw film was obtained as a resin film having a width of about 120 mm before contacting with a solvent.
  • the operating conditions of the film forming machine are itemized below.
  • the thickness of the original film was 158 ⁇ m.
  • a pre-stretched film was obtained. The pre-stretched film was taken out from cyclohexane, the cyclohexane adhering to the film surface was wiped off, and then the film was naturally dried in the air. The thickness of the obtained pre-stretched film was 160 ⁇ m.
  • the unstretched film was cut into a rectangle of 100 mm x 100 mm. Both ends of this rectangular pre-stretched film were gripped by the five clips of the stretching device, respectively.
  • the pre-stretched film was pulled with a clip and freely uniaxially stretched in the longitudinal direction of the long raw film obtained in the extrusion film formation step.
  • the stretching temperature was 138 ° C. and the stretching ratio was 1.2 times. By this stretching, an optical film as a uniaxially stretched film was obtained.
  • the direction of the slow axis of the optical film was perpendicular to the stretching direction. Further, the NZ coefficient at the measurement wavelength of 550 nm was 0.45.
  • step (1-2) The line speed in step (1-2) was changed to change the thickness of the long raw film to 115 ⁇ m.
  • the raw film was not immersed in the solvent in step (1-3).
  • step (1-4) the raw film was stretched instead of the pre-stretched film, the stretching temperature was changed to 132 ° C., and the stretching ratio was changed to 2.2 times.
  • the optical film was manufactured by the same method as in Example 1 except for the above items.
  • a mixture of a hydride of a ring-opening polymer of dicyclopentadiene and an antioxidant was formed into a strand by hot melt extrusion molding, and then shredded with a strand cutter to obtain pellets of a crystalline resin.
  • a polarizing film (“HLC2-5618S” manufactured by Sanritz Co., Ltd., a polarizing element having a thickness of 180 ⁇ m and a polarization transmission axis in the width direction) was prepared. With respect to one surface of the polarizing film and the optical films obtained in Examples 1 to 3 and Comparative Examples 1 and 2, the polarization transmission axis of the polarizing film and the slow axis of the optical film form an angle of 45 °.
  • a circular polarizing plate was obtained by laminating with a pressure-sensitive adhesive layer (“CS9621” manufactured by Nitto Denko).
  • a mirror was prepared and the prepared circular polarizing plate was placed on the mirror so that the optical film was on the mirror side.
  • the circularly polarizing plate was illuminated with a fluorescent lamp, and the reflected light from the mirror was observed in the front direction and in the tilt direction with a polar angle of about 60 °.
  • the front direction is the front direction of the mirror and represents a direction parallel to the thickness direction of the circularly polarizing plate. In each observation direction, " ⁇ " if the coloring is not visible, “ ⁇ ” if the coloring is visible but very slight, and " ⁇ " if the coloring is visible at an unacceptable level. And said.
  • Example 4 [Evaluation of Optical Film Obtained in Example 4] Two polarizing films (“HLC2-5618S” manufactured by Sanritz, 180 ⁇ m in thickness, and a polarizing element having a polarizing transmission axis in the width direction) were prepared and placed on a cross Nicol.
  • Cross Nicol means that the polarization transmission axis is vertical when viewed from the thickness direction.
  • the optical film obtained in Example 4 is placed on the polarizing transmission axis of the polarizing film on the viewing side (that is, the polarizing film on the viewing side when installed in a backlight described later) and the slow axis of the optical film. It was installed so that it matches.
  • a polarizing film and an optical film were bonded to each other via an adhesive layer (“CS9621” manufactured by Nitto Denko) to obtain a laminated body.
  • a backlight was prepared in a dark room, and the prepared laminate was placed on the backlight. With the backlight turned on, the light transmitted through the laminate was observed in the front direction and in the tilting direction with a polar angle of about 60 °. At each observation position, “ ⁇ ” is visible if the tint is not visible, “ ⁇ ” if the tint is visible but very slight, and the tint and light leakage are visible at an unacceptable level. If it is, it is set as "x".
  • crystalline polystyrene is used as the crystalline polymer having negative intrinsic birefringence to produce an optical film.
  • the delayed phase axis was developed in the direction perpendicular to the stretching direction in all the examples, so that the obtained optical film was negatively birefringent. It can be confirmed that it has a refraction characteristic.
  • all of the optical films obtained in the examples have an in-plane retardation satisfying the formula (1) and an NZ coefficient satisfying the formula (2).
  • the optical film obtained in the examples has a reverse wavelength dispersibility, its optical function can be exhibited in a wide wavelength range. Therefore, the optical films of Examples 1 to 3 can function as a quarter wave plate in a wide wavelength range. Therefore, the circularly polarizing plate provided with the optical film can suppress the reflection of light in a wide wavelength range as a reflection suppressing film. Therefore, it is possible to suppress the coloring caused by the light of a part of the wavelength passing through the circularly polarizing plate. Further, the optical film of Example 4 can function as a 1/2 wave plate in a wide wavelength range. Therefore, the optical film can convert the vibration direction of linearly polarized light in a wide wavelength range transmitted through the optical film by 90 °. Therefore, it is possible to suppress coloring and light leakage due to the passage of light having a part of wavelengths through the laminate.
  • the optical film obtained in the examples has an appropriate NZ coefficient, not only the light transmitted through the optical film in the thickness direction but also the polarization of the light transmitted in the inclined direction which is neither parallel nor perpendicular to the thickness direction.
  • the state can also be changed appropriately. Therefore, since the optical films of Examples 1 to 3 can suppress the reflection of the light transmitted through the circularly polarizing plate in the tilting direction, the tinting can be suppressed not only in the front direction but also in the tilting direction. Further, since the optical film of Example 4 can suppress the passage of light of the laminated body in the inclined direction, it is possible to suppress coloring and light leakage not only in the front direction but also in the inclined direction.

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  • Moulding By Coating Moulds (AREA)

Abstract

Selon l'invention, un film optique est fabriqué selon un procédé de fabrication incluant dans l'ordre : une étape au cours de laquelle est préparé un film de résine qui est constitué d'une résine contenant un polymère cristallin doté d'une biréfringence intrinsèque négative et un polymère thermoplastique doté d'une biréfringence intrinsèque positive ; une étape au cours de laquelle le film de résine est mis en contact avec un solvant, et la biréfringence dans une direction épaisseur est modifiée ; et une étape au cours de laquelle le film de résine est étiré.
PCT/JP2021/044208 2020-12-28 2021-12-02 Film optique ainsi que procédé de fabrication de celui-ci, et plaque de polarisation WO2022145169A1 (fr)

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JP2022572946A JPWO2022145169A1 (fr) 2020-12-28 2021-12-02
CN202180085915.5A CN116685610A (zh) 2020-12-28 2021-12-02 光学膜及其制造方法以及偏振片
KR1020237019618A KR20230121743A (ko) 2020-12-28 2021-12-02 광학 필름 및 그 제조 방법, 그리고 편광판

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003161832A (ja) * 2001-11-22 2003-06-06 Fuji Photo Film Co Ltd 位相差板
JP2007191505A (ja) * 2006-01-17 2007-08-02 Fujifilm Corp セルロースアシレートフィルム、偏光板及び液晶表示装置
US20150042928A1 (en) * 2013-08-09 2015-02-12 Samsung Display Co., Ltd. Display device
JP2015157928A (ja) * 2013-06-07 2015-09-03 東ソー株式会社 樹脂組成物およびそれを用いた光学補償フィルム
JP2016079377A (ja) * 2014-10-15 2016-05-16 東ソー株式会社 樹脂組成物およびそれを用いた光学補償フィルム
WO2019188205A1 (fr) * 2018-03-30 2019-10-03 日本ゼオン株式会社 Corps stratifié optique anisotrope, lame polarisante et dispositif d'affichage d'image

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4592004B2 (ja) 2005-02-02 2010-12-01 日東電工株式会社 位相差フィルムおよびその製造方法、ならびに該位相差フィルムを用いた画像表示装置
WO2017145935A1 (fr) 2016-02-22 2017-08-31 富士フイルム株式会社 Film optique, procédé de fabrication de film optique, et dispositif d'affichage
KR20210107650A (ko) 2018-12-27 2021-09-01 니폰 제온 가부시키가이샤 광학 이방성 적층체 및 그 제조 방법, 원 편광판, 그리고 화상 표시 장치

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003161832A (ja) * 2001-11-22 2003-06-06 Fuji Photo Film Co Ltd 位相差板
JP2007191505A (ja) * 2006-01-17 2007-08-02 Fujifilm Corp セルロースアシレートフィルム、偏光板及び液晶表示装置
JP2015157928A (ja) * 2013-06-07 2015-09-03 東ソー株式会社 樹脂組成物およびそれを用いた光学補償フィルム
US20150042928A1 (en) * 2013-08-09 2015-02-12 Samsung Display Co., Ltd. Display device
JP2016079377A (ja) * 2014-10-15 2016-05-16 東ソー株式会社 樹脂組成物およびそれを用いた光学補償フィルム
WO2019188205A1 (fr) * 2018-03-30 2019-10-03 日本ゼオン株式会社 Corps stratifié optique anisotrope, lame polarisante et dispositif d'affichage d'image

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CN116685610A (zh) 2023-09-01
KR20230121743A (ko) 2023-08-21
TW202232136A (zh) 2022-08-16
JPWO2022145169A1 (fr) 2022-07-07

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