Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/0073—Optical laminates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
  • B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/0074—Production of other optical elements not provided for in B29D11/00009- B29D11/0073
  • B29D11/00788—Producing optical films
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D11/00—Producing optical elements, e.g. lenses or prisms
  • B29D11/00865—Applying coatings; tinting; colouring
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D7/00—Producing flat articles, e.g. films or sheets
  • B29D7/01—Films or sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/02—Physical, chemical or physicochemical properties
  • B32B7/023—Optical properties
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics

Definitions

• the present invention relates to an optical film, a multilayer film that can be usefully used as a member for manufacturing the optical film, and a method for manufacturing the same.
• a film having an Nz coefficient of 0 ⁇ Nz ⁇ 1 is called a three-dimensional retardation film. It is known that when a three-dimensional retardation film is provided in a display device such as a liquid crystal display device, it can exhibit an effect of reducing the coloring of the display surface when viewed from an inclined direction. In particular, a three-dimensional retardation film having a so-called inverse wavelength dispersion in which the relationship between the retardation and the wavelength has a so-called inverse wavelength dispersion can obtain a desired optical effect in a wide wavelength range. Further, due to the demand for thinning of the display device, the thickness of the three-dimensional retardation film is also required to be thin.
• the three-dimensional retardation film has a larger phase difference in the z-axis direction (that is, the thickness direction) than the phase difference in the y-axis direction (that is, the in-plane direction orthogonal to the in-plane slow phase axis direction). Therefore, it cannot be manufactured by a normal method for manufacturing a retardation film, such as simply stretching a resin for an optical film whose natural birefringence is positive. Therefore, it has been proposed so far to produce a three-dimensional retardation film or a film similar thereto by combining a resin having a positive birefringence and a resin having a negative intrinsic birefringence (for example, Patent Documents 1 and 2).
• the method for producing a three-dimensional retardation film in which a resin having a positive birefringence and a resin having a negative birefringence which has been proposed so far, requires a complicated stretching step and a bonding step after stretching. There was a problem such as a large amount of labor for positioning. In particular, it is difficult to easily produce a product having a reverse wavelength dispersibility. Further, in such a combination, it is required to increase the proportion of the resin having a negative intrinsic birefringence to some extent or more, but since many resins having a negative intrinsic birefringence generally have low mechanical strength. If the proportion of such a resin is increased, a problem of low mechanical strength may occur. The low mechanical strength can cause problems especially when the film is thin. In addition, there is a problem that haze occurs due to the stretching of the resin, which may impair the display quality of the display device.
• an object of the present invention is that a good effect can be exhibited as a three-dimensional retardation film in a wide wavelength range, the mechanical strength is high, the thickness is thin, and the display quality of a display device can be improved. It is an object of the present invention to provide a film that can be easily produced and a production method that can easily produce such a film.
• the present inventor has studied to solve the above-mentioned problems. As a result, the present inventor has adopted a particular material as one of a multilayer film in which a layer of a material having a positive intrinsic birefringence and a layer of a material having a negative intrinsic birefringence are combined in a wide wavelength range. It has been found that a multilayer film that can exhibit a good effect as a three-dimensional retardation film and can be easily manufactured can be formed. Based on this finding, the inventor has completed the present invention. That is, the present invention includes the following.
• a multilayer film comprising a pA layer made of a crystalline resin (a) having a positive birefringence and a pB layer made of a material (b) having a negative birefringence.
• nx (pA), ny (pA) and nz (pA) are the main refractive indexes of the pA layer.
• nx (pB), ny (pB) and nz (pB) are the main refractive indexes of the pB layer.
• Re (450), Re (550) and Re (650) are the in-plane retardation of the optical film at a wavelength of 450 nm, the in-plane retardation of the optical film at a wavelength of 550 nm, and the optical film at a wavelength of 650 nm, respectively.
• Nz is the Nz coefficient of the optical film.
• a production method comprising a step (II) of obtaining a multilayer film including the pA layer and the pB layer by changing the birefringence in the direction to form a pA layer.
• the method for producing an optical film according to any one of [5] to [9].
• the step (I) of preparing the film oA made of the crystalline resin (a) and A liquid composition containing a solvent and a material (b) having a negative intrinsic birefringence dissolved in the solvent is applied to one or both sides of the film oA to form a pB layer and the thickness of the film oA.
• a production method comprising the step (III) of co-stretching the multilayer film.
• a good effect can be exhibited as a three-dimensional retardation film in a wide wavelength range, the mechanical strength is high, the thickness is thin, the display quality of a display device can be improved, and the display quality can be easily improved.
• an optical film that can be manufactured a multilayer film that can be usefully used as a member for manufacturing such an optical film, and a manufacturing method that can easily manufacture such a multilayer film and an optical film. Ru.
• the NZ coefficient of the film-like structure is a value represented by (nx-nz) / (nx-ny) unless otherwise specified.
• Nx, ny and nz are the main refractive indexes of the film-like structure unless otherwise specified.
• the main refractive indexes nx, ny and nz are refractive indexes in three orthogonal directions with the nx direction as the slow phase axis direction and the nz direction as the thickness direction. That is, nx represents the refractive index in the direction perpendicular to the thickness direction (in-plane direction) of the film-like structure and in the direction giving the maximum refractive index.
• ny represents the refractive index in the in-plane direction of the film-like structure and orthogonal to the direction of nx.
• nz represents the refractive index of the film-like structure in the thickness direction.
• d represents the thickness of the film-like structure.
• the measurement wavelength is 590 nm unless otherwise specified.
• the optical characteristics of a structure with a certain symbol are expressed by a combination of a symbol representing the optical characteristics (for example, nx, ny, nz, Re, Rth, NZ, etc.) and the symbol of the structure. do.
• the main refractive indexes nx, ny and nz of the A layer can be expressed as nx (A), ny (A) and nz (A), respectively.
• the main refractive indexes nx, ny and nz of the pA layer can be expressed as nx (pA), ny (pA) and nz (pA), respectively.
• a material having a 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.
• the material having a negative intrinsic 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.
• the value of the intrinsic birefringence can be calculated from the permittivity distribution.
• the "long" film means a film having a length of 5 times or more with respect to the width, preferably a film having a length of 10 times or more, and specifically, a roll.
• the slow-phase axis of the film-like structure is the in-plane slow-phase axis unless otherwise specified.
• the multilayer film of the present invention includes a pA layer made of a crystalline resin (a) having a positive intrinsic birefringence and a pB layer made of a material (b) having a negative intrinsic birefringence.
• nx (pA), ny (pA) and nz (pA) are the main refractive indexes of the pA layer
• nx (pB), ny (pB) and nz (pB) are the main refractive indexes of the pB layer.
• the pA layer satisfying the formulas (1) to (2) and the pB layer satisfying the formulas (3) to (4) are called positive C plates.
• the ratio of nz (pA) to nx (pA), that is, nz (pA) / nx (pA) is larger than 1, preferably 1.0002 or more.
• the upper limit of the ratio may be, for example, 2 or less.
• the ratio of nz (pB) to nx (pB), that is, nz (pB) / nx (pB) is larger than 1, preferably 1.0002 or more.
• the upper limit of the ratio may be, for example, 2 or less.
• the slow phase axial directions of the pA layer and the pB layer can be appropriately adjusted so that the optical characteristics of the multilayer film and the optical film prepared using the same are desired values, but the pA layer and the pB layer can be adjusted. Since both nx and ny are exactly the same or almost the same, the direction of the slow axis can be arbitrary.
• the multilayer film of the present invention can be a long film.
• the "long” film means a film having a length of 5 times or more with respect to the width, preferably having a length of 10 times or more, and specifically being wound into a roll.
• the multilayer film of the present invention may include a pA layer and a pB layer one by one.
• the multilayer film of the present invention may also have two or more pA layers, or may have two or more pB layers.
• the multilayer film of the present invention includes one layer each of a pA layer and a pB layer.
• the multilayer film of the present invention preferably has one layer of pA and two layers of pB formed on both sides thereof. That is, the multilayer film of the present invention can be a film having a layer structure of (pB layer) / (pA layer) / (pB layer).
• the optical characteristics of those in which they are stacked in the same relationship as their planar positional relationship in the multilayer film can be used as the optical characteristics of the pA layer described above.
• the optical characteristics of those in which they are stacked in the same relationship as their planar positional relationship in the multilayer film can be used as the optical characteristics of the pB layer described above. ..
• the multilayer film of the present invention may include any layer other than the pA layer and the pB layer.
• an adhesive layer may be provided between the pA layer and the pB layer.
• the pA layer and the pB layer are in direct contact with each other.
• the multilayer film in which the pA layer and the pB layer are in direct contact makes it possible to impart good optical characteristics to the optical film while reducing the thickness of the obtained optical film.
• Such a multilayer film can be easily manufactured by the method for manufacturing a multilayer film of the present invention described later.
• an optical film used for a device such as a display device requires a certain thickness or more in order to exhibit optical characteristics, but is required to be thin due to a demand for thinning of the device.
• the thickness of the multilayer film of the present invention is not particularly limited, but by satisfying the requirements of the present invention, it is possible to form a member capable of forming an optical film satisfying desired optical characteristics even if the thickness is thin.
• the thickness of the multilayer film of the present invention can be preferably 150 ⁇ m or less, more preferably 100 ⁇ m or less.
• the lower limit of the thickness of the multilayer film is not particularly limited, but may be, for example, 10 ⁇ m or more.
• the thickness of each of the pA layer and the pB layer can be appropriately adjusted so as to obtain desired optical characteristics.
• the thickness of the pA layer is preferably 10 ⁇ m or more, more preferably 30 ⁇ m or more, while preferably 100 ⁇ m or less, more preferably 80 ⁇ m or less.
• the thickness of the pB layer is preferably 1 ⁇ m or more, more preferably 5 ⁇ m or more, while preferably 20 ⁇ m or less, more preferably 15 ⁇ m or less.
• the total thickness thereof can be adjusted to the above-mentioned preferable range.
• the total thickness thereof can be adjusted to the above-mentioned preferable range.
• the crystalline resin (a) constituting the pA layer can be a resin containing a polymer having crystallinity.
• the "polymer having crystallinity” represents a polymer having a melting point Tm. That is, the "polymer having crystallinity” represents a polymer whose melting point can be observed with a differential scanning calorimeter (DSC).
• DSC differential scanning calorimeter
• a polymer having crystallinity may be referred to as a “crystalline polymer”.
• the crystalline resin is preferably a thermoplastic resin.
• the crystalline polymer has a positive intrinsic birefringence.
• a crystalline polymer having positive intrinsic birefringence an optical film having desired optical properties can be easily produced in combination with the material (b).
• the crystalline polymer may be, for example, a polyester such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN); a polyolefin such as polyethylene (PE) or polypropylene (PP); and is not particularly limited. It preferably contains an alicyclic structure.
• PET polyethylene terephthalate
• PEN polyethylene naphthalate
• PP polypropylene
• the polymer containing an alicyclic structure represents a polymer having an alicyclic structure in the molecule.
• the polymer containing such an alicyclic structure can be, for example, a polymer obtained by a polymerization reaction using a cyclic olefin as a monomer or a hydride thereof.
• Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure. Among these, a cycloalkane structure is preferable because it is easy to obtain a retardation film having excellent properties such as thermal stability.
• the number of carbon atoms contained in one alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, and particularly preferably 15 or less. be. When the number of carbon atoms contained in one alicyclic structure is within the above range, mechanical strength, heat resistance, and moldability are highly balanced.
• the ratio of the structural unit having an alicyclic structure to all the structural units is preferably 30% by weight or more, more preferably 50% by weight or more, and particularly preferably 70% by weight. % Or more. Heat resistance can be improved by increasing the proportion of structural units having an alicyclic structure as described above.
• the ratio of structural units having an alicyclic structure to all structural units may be 100% by weight or less.
• the balance other than the structural unit having an alicyclic structure is not particularly limited and may be appropriately selected depending on the purpose of use.
• Examples of the crystalline polymer containing an alicyclic structure include the following polymers ( ⁇ ) to ( ⁇ ). Among these, the polymer ( ⁇ ) is preferable because it is easy to obtain a retardation film having excellent heat resistance.
• Polymer ( ⁇ ) An addition polymer of a cyclic olefin monomer having crystallinity.
• Polymer ( ⁇ ) A hydride of the polymer ( ⁇ ) that has crystallinity.
• the crystalline polymer containing an alicyclic structure includes a ring-opening polymer of dicyclopentadiene having crystalline property and a hydride of a ring-opening polymer of dicyclopentadiene. Those having crystalline properties are more preferable. Of these, a hydride of a ring-opening polymer of dicyclopentadiene, which has crystallinity, is particularly preferable.
• the ratio of the structural unit derived from dicyclopentadiene to all the structural units is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. More preferably, it refers to a polymer of 100% by weight.
• the hydride of the ring-opening polymer of dicyclopentadiene preferably has a high proportion of racemic diad.
• the proportion of the repeating unit racemic diad in the hydride of the ring-opening polymer of dicyclopentadiene is preferably 51% or more, more preferably 70% or more, and particularly preferably 85% or more.
• a high proportion of racemic diads indicates a high syndiotactic stereoregularity. Therefore, the higher the proportion of racemic diad, the higher the melting point of the hydride of the ring-opening polymer of dicyclopentadiene tends to be.
• the proportion of racemo diads can be determined based on the 13 C-NMR spectral analysis described in Examples described below.
• polymer ( ⁇ ) to the polymer ( ⁇ ) a polymer obtained by the production method disclosed in International Publication No. 2018/062067 can be used.
• the melting point Tm of the crystalline polymer is preferably 200 ° C. or higher, more preferably 230 ° C. or higher, and preferably 290 ° C. or lower.
• the crystalline polymer has a glass transition temperature Tg.
• the specific glass transition temperature Tg of the crystalline polymer is not particularly limited, but is usually 85 ° C. or higher and usually 170 ° C. or lower.
• 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 weight average molecular weight (Mw) of the crystalline polymer is preferably 1,000 or more, more preferably 2,000 or more, preferably 1,000,000 or less, and more preferably 500,000 or less.
• a crystalline polymer having such a weight average molecular weight has an excellent balance between molding processability and heat resistance.
• the molecular weight distribution (Mw / Mn) of the crystalline polymer is preferably 1.0 or more, more preferably 1.5 or more, preferably 4.0 or less, and more preferably 3.5 or less.
• Mn represents a number average molecular weight.
• a crystalline polymer having such a molecular weight distribution is excellent in molding processability.
• the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the polymer can be measured as polystyrene-equivalent values by gel permeation chromatography (GPC) using tetrahydrofuran as a developing solvent.
• the crystallinity of the crystalline polymer contained in the retardation film is not particularly limited, but 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.
• one type may be used alone, or two or more types may be used in combination at any ratio.
• the proportion of the crystalline polymer in the crystalline resin (a) is preferably 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more.
• the ratio of the crystalline polymer is at least the above lower limit value, the birefringence expression and heat resistance of the retardation film can be enhanced.
• the upper limit of the proportion of the crystalline polymer may be 100% by weight or less.
• the crystalline resin (a) may contain any component in addition to the crystalline polymer.
• Optional components include, for example, antioxidants such as phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants; light stabilizers such as hindered amine-based light stabilizers; petroleum-based waxes, Fishertroph waxes, etc.
• Waxes such as polyalkylene wax; sorbitol compounds, metal salts of organic phosphates, metal salts of organic carboxylic acids, nucleating agents such as kaolin and talc; diaminostilben derivatives, coumarin derivatives, azole derivatives (eg, benzoxazole derivatives, etc.) Fluorowhitening agents such as benzotriazole derivatives, benzoimidazole derivatives, and benzothiazole derivatives), carbazole derivatives, pyridine derivatives, naphthalic acid derivatives, and imidazolone derivatives; benzophenone-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, benzotriazole-based UV absorbers such as UV absorbers; Inorganic fillers such as talc, silica, calcium carbonate, glass fibers; Colorants; Flame retardants; Flame retardant aids; Antistatic agents; Plastics; Near infrared absorbers; Lubricants; Fillers ; And any polymer other than the crystalline
• the crystalline resin (a) constituting the pA layer may contain an organic solvent. This organic solvent is usually incorporated into the film in the step (II) of the production method of the present invention.
• the organic solvent incorporated into the film in step (II) can enter the inside of the polymer. Therefore, it is difficult to completely remove the solvent even if the drying is performed above the boiling point of the organic solvent. Therefore, the pA layer usually contains an organic solvent.
• the crystalline polymer may not be dissolved in the step of the production method of the present invention described later.
• Preferred organic solvents include, for example, hydrocarbon solvents such as toluene, limonene and decalin; ketones such as methyl ethyl ketone; carbon disulfide;
• the type of the organic solvent may be one kind or two or more kinds.
• the ratio (solvent content) of the organic solvent contained therein to 100% by weight of the crystalline resin (a) is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 0.1% by weight. It is as follows.
• the material (b) constituting the pB layer has a negative intrinsic birefringence.
• a resin having a negative intrinsic birefringence as the material (b) and combining this with a crystalline resin (a) having a positive intrinsic birefringence, it is particularly easy to produce a multilayer film satisfying the requirements of the present invention. can.
• the resin having a negative intrinsic birefringence is usually a thermoplastic resin and contains a polymer having a negative intrinsic birefringence.
• polymers having a negative intrinsic compound refraction include homopolymers and copolymers of styrene or styrene derivatives, and polystyrene-based polymers containing styrene or styrene derivatives and arbitrary monomers; Examples thereof include acrylonitrile polymers; polymethylmethacrylate polymers; or multiple copolymer polymers thereof; and cellulose compounds such as cellulose esters.
• examples of the optional monomer copolymerizable with styrene or a styrene derivative include acrylonitrile, maleic anhydride, methyl methacrylate, and butadiene.
• examples of the optional monomer copolymerizable with styrene or a styrene derivative include acrylonitrile, maleic anhydride, methyl methacrylate, and butadiene.
• polystyrene-based polymers and cellulosic compounds are preferable.
• one of these polymers may be used alone, or two or more of these polymers may be used in combination at any ratio.
• the proportion of the polymer in the resin having a negative intrinsic birefringence is preferably 50% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, and particularly preferably 90% by weight to 100% by weight.
• the proportion of the polymer is in the above range, the pB layer can be easily imparted with desired optical properties.
• the material (b) preferably contains a plasticizer.
• a plasticizer By using a plasticizer, the glass transition temperature of the material (b) can be appropriately adjusted.
• the plasticizer include phthalates, fatty acid esters, phosphate esters, epoxy derivatives and the like. Specific examples of the plasticizer include those described in JP-A-2007-233114. In addition, one type of plasticizer may be used alone, or two or more types may be used in combination at any ratio.
• phosphoric acid ester is preferable because it is easily available and inexpensive.
• phosphoric acid esters include trialkyl phosphates such as triethyl phosphate, tributyl phosphate and trioctyl phosphate; halogen-containing trialkyl phosphates such as trichloroethyl phosphate; triphenyl phosphate and tricresyl.
• Triaryl phosphates such as phosphates, tris (isopropylphenyl) phosphates, cresyldiphenyl phosphates; alkyl-diaryl phosphates such as octyldiphenyl phosphates; tri (alkoxyethyl) phosphates such as tri (butoxyethyl) phosphates. Alkyl) phosphate; etc.
• the amount thereof is preferably 0.001% by weight or more, more preferably 0.005% by weight or more, and particularly preferably 0. It is 1% by weight or more, preferably 20% by weight or less, more preferably 18% by weight or less, and particularly preferably 15% by weight or less.
• the amount of the plasticizer is in the above range, the glass transition temperature of the material (b) can be appropriately adjusted, so that the pB layer can be easily imparted with desired optical properties.
• the material (b) may further contain any component other than the polymer and the plasticizer in combination with the polymer and the plasticizer.
• the optional component include the same examples as any component that the crystalline resin (a) can contain. Any component may be used alone or in combination of two or more at any ratio.
• the glass transition temperature of the material (b) is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, still more preferably 100 ° C. or higher, particularly preferably 110 ° C. or higher, and particularly preferably 120 ° C. or higher.
• the upper limit of the glass transition temperature of the material (b) is not particularly limited, but is usually 200 ° C. or lower.
• the optical film of the present invention is a uniaxial co-stretched product of the multilayer film of the present invention. That is, the film of the present invention is formed by co-stretching the pA layer and the pB layer by stretching the multilayer film of the present invention. By such co-stretching, all the layers contained in the multilayer film are stretched at the same stretching ratio and stretching direction, and the polymer molecules contained in these layers are oriented in the direction corresponding to the stretching direction. Since the multilayer film has the specific requirements specified by the formulas (1) to (4), it has optical properties that are difficult to obtain by a normal method for producing an retardation film, such as simply stretching a resin for an optical film. An optical film can be easily obtained.
• the optical film of the present invention includes an A layer made of a crystalline resin (a) having a positive intrinsic birefringence and a B layer made of a material (b) having a negative intrinsic birefringence.
• the layer A can be a layer obtained as a result of stretching the pA layer.
• the B layer can be a layer obtained as a result of stretching the pB layer. Therefore, the specific examples of the material constituting the A layer and the material constituting the B layer can be the same as those examples for the pA layer and the pB layer.
• the optical film of the present invention satisfies the following formulas (5) and (6).
• the optical film of the present invention satisfies the following formula (7) or the following formula (8).
• Re (450), Re (550) and Re (650) are in-plane lettering at an optical film wavelength of 450 nm, in-plane lettering at an optical film wavelength of 550 nm, and in-plane lettering of an optical film at a wavelength of 650 nm, respectively.
• Nz is the Nz coefficient of the optical film.
• a film satisfying the formula (5) is called a reverse wavelength dispersive film.
• a film satisfying the formula (5) can obtain a desired optical effect in a wide wavelength range.
• the film satisfying the formula (8) is called a three-dimensional retardation film.
• the film satisfying both the formulas (5) and (8) had to be produced by a complicated process in the prior art, but the optical film of the present invention is the multilayer film of the present invention having a specific configuration. Since it is used in manufacturing, it can be easily manufactured by its uniaxial stretching. Further, when the optical film of the present invention is a film satisfying the formulas (5) and (7), it is easily converted into a film satisfying both the formulas (5) and (8) by further uniaxially stretching the film. sell.
• the lower limit of Re (450) / Re (550) is not limited, but is preferably 0.60 or more, more preferably 0.70 or more, and particularly preferably 0.75 or more. be.
• Re (450), Re (550) and Re (650) can be adjusted to the values suitable for the application of the optical film.
• Re (550) is preferably 80 nm or more, more preferably 100 nm or more, particularly preferably 120 nm or more, preferably 180 nm or less, more preferably 160 nm or less. It is particularly preferably 150 nm or less.
• the preferred range of Re (550) may be 275 nm or a value close to it, specifically, preferably 260 to 290 nm, and more preferably 265 to 285 nm.
• Nz is greater than 0 and less than 1.
• the NZ coefficient of the retardation film is preferably 0.2 or more, more preferably 0.4 or more, preferably 0.8 or less, and more preferably 0.6 or less.
• the uniaxial co-stretching for obtaining a uniaxial co-stretched product can be vertical uniaxial co-stretching, horizontal uniaxial co-stretching, or diagonal uniaxial co-stretching.
• the vertical uniaxial stretching is the stretching along the longitudinal direction of the film
• the horizontal uniaxial stretching is the stretching along the width direction of the film
• the diagonal uniaxial stretching is the stretching along the diagonal direction of the film. It is an extension, and here, the diagonal direction is a direction perpendicular to the thickness direction, and the angle formed by the width direction is neither 0 ° nor 90 ° (that is, the angle formed by the width direction is 0 °). Direction that is less than 90 °).
• the optical film of the present invention is a stretched product of the specific multilayer film, the formulas (5) and (6), more preferably the formula (5), are not performed without complicated stretching such as biaxial stretching.
• (8) can be a film.
• the optical film of the present invention can be a long film. Since the optical film is a long film, efficient production of the optical film can be achieved.
• the optical film of the present invention may include an A layer and a B layer one by one.
• the multilayer film of the present invention may also have two or more layers A and may have two or more layers B.
• the optical film of the present invention preferably includes an A layer and a B layer, one layer at a time, from the viewpoint of efficiently performing the method for producing an optical film.
• the optical film of the present invention preferably has one layer A and two layers B formed on both sides thereof. That is, the optical film of the present invention can be a film having a layer structure of (B layer) / (A layer) / (B layer). When having such a layer structure, it is preferable because an optical film having desired optical characteristics can be easily obtained even if the thickness of the B layer per layer is thin.
• the optical characteristics of those in which they are stacked in the same relationship as their planar positional relationship in the optical film can be the optical characteristics of the A layer described above.
• the optical characteristics of those in which they are stacked in the same relationship as their planar positional relationship in the optical film can be used as the optical characteristics of the B layer described above. ..
• the optical film of the present invention may include any layer other than the A layer and the B layer.
• an adhesive layer may be provided between the A layer and the B layer.
• the thickness of the optical film of the present invention is not particularly limited, but it is possible to obtain an optical film that satisfies desired optical characteristics even if the thickness is thin.
• the thickness of the optical film of the present invention can be preferably 100 ⁇ m or less, more preferably 80 ⁇ m or less.
• the lower limit of the thickness of the optical film is not particularly limited, but may be, for example, 10 ⁇ m or more.
• the thickness of each of the A layer and the B layer can be appropriately adjusted so as to obtain desired optical characteristics.
• the thickness of the layer A is preferably 10 ⁇ m or more, more preferably 20 ⁇ m or more, while preferably 100 ⁇ m or less, more preferably 80 ⁇ m or less.
• the thickness of the B layer is preferably 1 ⁇ m or more, more preferably 5 ⁇ m or more, while preferably 20 ⁇ m or less, more preferably 15 ⁇ m or less.
• the multilayer film of the present invention can be produced by a production method including the following steps (I) to (II). Further, the optical film of the present invention can be produced by a production method including the following steps (III) in addition to the following steps (I) to (II).
• a manufacturing method will be described as a method for manufacturing a multilayer film of the present invention and a method for manufacturing an optical film of the present invention.
• Step (I) The step (I) can be performed by molding the crystalline resin (a) into the shape of a film. Step (I) may also be performed simply by obtaining a commercially available film. Any molding method can be adopted as a method for molding the crystalline resin (a) into the shape of a film. From the viewpoint of production efficiency, melt extrusion molding is preferable.
• the thickness of the film oA can be appropriately adjusted so that the thickness of the pA layer in the multilayer film as a product and the thickness of the A layer in the optical film are desired.
• Step (II): Liquid composition a liquid composition containing a solvent and material (b) is used.
• the solvent include the same examples as those mentioned above as examples of the organic solvent that may exist as a state contained in the crystalline resin (a) constituting the pA layer. More specifically, hydrocarbon solvents such as toluene, limonene and decalin; ketones such as methyl ethyl ketone; and carbon disulfide can be mentioned.
• a ketone such as methyl ethyl ketone or a mixed solvent of the ketone and another solvent is particularly preferable.
• the type of the solvent contained in the liquid composition may be one type or two or more types.
• the same example as described above can be given. That is, the liquid composition is the same as that described above as an example of any component that can be contained in the polymer having a negative intrinsic birefringence and the other material (b) constituting the material (b). Can include.
• the ratio of the solvent to the material (b) in the liquid composition can be appropriately adjusted so that the B layer having a desired thickness can be formed and the degree of change in the film oA can be within a desired range.
• the ratio of the polymer having a negative intrinsic birefringence constituting the material (b) to the total of the solvent and the material (b) can be adjusted to a ratio of 1 to 50% by weight.
• step (II): Coating the liquid composition is applied to one or both sides of the film oA.
• the specific operation of coating is not particularly limited, but it is preferable that the coating thickness can be precisely controlled from the viewpoint of forming the B layer having a uniform desired thickness. Specifically, for example, coating with a coater such as a die coater is preferable.
• the solvent which is a component of the liquid composition, comes into contact with the surface of the oA layer.
• the birefringence in the thickness direction of the film oA can be changed by the contact between the film oA and the solvent. can.
• a resin having a normal intrinsic birefringence of nz (pA)> nx (pA) ⁇ ny (pA) is formed by a normal film forming and stretching process. Optical properties that are difficult to obtain with a film can be easily obtained.
• step (II) the pB layer is formed on the surface of the film oA, and at the same time, such a change in the film oA can be achieved.
• a multilayer film which is difficult to obtain normally and has both a layer of a material having a positive intrinsic birefringence and a layer of a material having a negative intrinsic birefringence, both of which have the optical characteristics of a positive C plate. Can be manufactured to.
• Step (III) In the step (III), the multilayer film obtained in the step (II) is uniaxially co-stretched. By such co-stretching, the molecules of the polymer contained in the pA layer and the pB layer of the multilayer film are oriented in the direction corresponding to the stretching direction. Since the multilayer film has undergone the step (II), as a result of the step (III), an optical film having optical characteristics that are difficult to obtain by a normal method for producing an retardation film, such as simply stretching a resin for an optical film, is obtained. It can be easily obtained.
• the stretching direction in the step (III) is not limited, and examples thereof include a longitudinal direction, a width direction, and an oblique direction.
• the manufacturing method of the present invention is advantageous from the viewpoint of manufacturing efficiency because the optical film of the present invention can be obtained only by uniaxial stretching.
• 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 strength of the optical film as a product.
• the stretching ratio is equal to or higher than the lower limit, the birefringence can be significantly changed by stretching.
• the draw ratio is not more than the upper limit value, the direction of the slow phase axis can be easily controlled and the breakage of the film can be effectively suppressed.
• the stretching temperature is preferably "Tg + 5 ° C.” or higher, more preferably “Tg + 10 ° C.” or higher, preferably “Tg + 100 ° C.” or lower, and more preferably “Tg + 90 ° C.” or lower.
• Tg represents the glass transition temperature of the crystalline polymer.
• the stretching temperature is equal to or higher than the lower limit, the film can be sufficiently softened and stretched uniformly. Further, when the stretching temperature is not more than the upper limit value, the film can be suppressed from being cured due to the progress of crystallization of the crystalline polymer, so that stretching can be smoothly performed, and large birefringence is exhibited by stretching. be able to.
• the haze of the resulting multilayer film can usually be reduced to increase transparency.
• the Nz coefficient can be adjusted. Therefore, by stretching by the step (III), a film satisfying the requirements of the formula (7) or the formula (8) described above can be obtained.
• the obtained film can be used as it is as the optical film of the present invention.
• the obtained film can be further subjected to arbitrary treatment to obtain the optical film of the present invention. Examples of the arbitrary step include heat treatment while maintaining the stretched dimensions, or adjustment of birefringence by treatment such as relaxation treatment by shrinking the stretched dimensions.
• the method for producing a multilayer film of the present invention and the method for producing an optical film of the present invention may further include any step in combination with the above-mentioned steps.
• step (II) the step of drying the solvent in the liquid composition may be included.
• the method for producing an optical film of the present invention may include a preheat treatment step for bringing the temperature of the multilayer film to a stretching temperature or a temperature close to the stretching temperature before the step (III).
• the preheating temperature and the stretching temperature are the same, but may be different.
• the preheating temperature is preferably T1-10 ° C. or higher, more preferably T1-5 ° C. or higher, preferably T1 + 5 ° C. or lower, and more preferably T1 + 2 ° C. or lower with respect to the stretching temperature T1.
• the preheating time is arbitrary, preferably 1 second or longer, more preferably 5 seconds or longer, and preferably 60 seconds or shorter, more preferably 30 seconds or shorter.
• the long optical film obtained in step (III) can be wound into a roll as needed to form a film roll. Further, if necessary, it can be cut into a desired shape such as a rectangle.
• the optical film of the present invention can be used as a component of an optical device such as a display device after being processed into a desired shape such as a rectangle, if necessary.
• an optical device such as a display device
• a desired shape such as a rectangle
• it is possible to improve the display quality such as the viewing angle, contrast, and image quality of the image displayed on the display device.
• the free-end uniaxial stretching of the film is uniaxial stretching performed in a mode that allows shrinkage in the direction orthogonal to the stretching direction in the in-plane direction.
• uniaxial stretching in which the dimensions in the direction orthogonal to the stretching direction are fixed and contraction in the direction is not allowed is called fixed end uniaxial stretching.
• uniaxial stretching other than free-end uniaxial stretching in the longitudinal direction is fixed-end uniaxial stretching unless otherwise specified.
• ⁇ Evaluation method ⁇ (Method for measuring weight average molecular weight Mw and number average molecular weight Mn of polymer)
• the weight average molecular weight Mw and the number average molecular weight Mn of the polymer were measured as polystyrene-equivalent values using a gel permeation chromatography (GPC) system (“HLC-8320” manufactured by Tosoh Corporation).
• GPC gel permeation chromatography
• the hydrogenation rate of the polymer was measured by 1 H-NMR measurement at 145 ° C. using orthodichlorobenzene - d4 as a solvent.
• 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 ratio of racemic diads in the polymer was measured as follows. 13 C-NMR measurement of the polymer was carried out by applying the inverted-gated decoupling method at 200 ° C. using ordichlorobenzene - d4 as a solvent. In the results of this 13 C-NMR measurement, the signal of 43.35 ppm derived from meso-diad and the signal of 43.43 ppm derived from racemic diad were used as the reference shift with the peak of 127.5 ppm of orthodichlorobenzene - d4 as a reference shift. Was identified. Based on the intensity ratios of these signals, the proportion of racemic diads in the polymer was determined.
• the optical properties of the film were measured using a phase difference meter (“AxoScan” manufactured by Axometrics). The measurement wavelength was 590 nm unless otherwise specified.
• the procedure for separating each layer of the film including the A layer (or pA layer) and the B layer (or pB layer) was as follows. The B layer (or pB layer) side of the film was attached to the glass plate via the adhesive layer. Then, using a cutter, a cut was made in the edge of the plate to separate the A layer (or pA layer) and the B layer (or pB layer). The optical characteristics of each of the peeled A layer (or pA layer) and the B layer (or pB layer) on the glass plate were measured separately.
• Crystallinity The crystallinity (%) of the crystalline polymer was measured by an X-ray diffraction method.
• the film as a sample was subjected to a planar unloaded U-shaped expansion / contraction test using a desktop durability tester (“DLDMLLH-FS” manufactured by Yuasa System Equipment Co., Ltd.). In this test, the film was repeatedly bent under the conditions of a width of 50 mm, a bending radius of 1 mm, and an expansion / contraction speed of 80 times / minute. After 1000 times of bending, the apparatus was stopped, the film was visually confirmed, and the film was evaluated according to the following evaluation criteria. "Good”: No breakage, cracking, or whitening of the film piece was observed. "Defective”: Either the film piece was broken, cracks were generated, or whitening was observed.
• a long linear polarizing film having an absorption axis in the longitudinal direction was prepared.
• This linearly polarizing film and the optical film to be evaluated were bonded together.
• the angle was adjusted so that the absorption axis of the linear polarizing film and the absorption axis of the optical film formed an angle of 45 °.
• This bonding was performed using an adhesive (“CS-9621” manufactured by Nitto Denko Corporation). As a result, a circularly polarizing film was obtained.
• 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 the mixture in the 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 8,830 and 29,800, respectively, and the molecular weight distribution (Mw / Mn) obtained from these. was 3.37.
• the hydride contained in the reaction solution and the solution were separated using a centrifuge and dried under reduced pressure at 60 ° C. for 24 hours to obtain a hydride of a crystallized dicyclopentadiene ring-opening polymer 28. I got 5 copies.
• the hydrogenation rate of this hydride was 99% or more, the glass transition temperature Tg was 97 ° C., the melting point Tm was 266 ° C., and the ratio of racemo diad was 89%.
• the obtained crystalline resin (a) was put into a twin-screw extruder (“TEM-37B” manufactured by Toshiba Machine Co., Ltd.) equipped with four die holes having an inner diameter of 3 mm ⁇ .
• the resin was hot melt extruded using a twin-screw extruder to form a strand-shaped molded product.
• This molded product was shredded with a strand cutter to obtain pellets of the crystalline resin (a).
• the operating conditions of the twin-screw extruder are shown below. -Barrel set temperature: 270 ° C to 280 ° C ⁇ Die set temperature: 250 °C ⁇ Screw rotation speed: 145 rpm ⁇ Feeder rotation speed: 50 rpm
• the pellet of the crystalline resin (a) obtained in Production Example 2 was dried at 100 ° C. for 5 hours.
• the dried pellets were fed to the film forming machine.
• the film forming machine is equipped with an extruder, a polymer pipe, a polymer filter and a T-die in this order in the resin flow path, melts the pellets charged in the extruder, and extrudes the pellets from the T-die into a film shape through the flow path. It is a device.
• As the operating conditions of the film forming machine a barrel temperature of 280 ° C.
• the molten crystalline resin (a) was extruded into a film having a width of 500 mm toward a rotating cast roll.
• the rotation speed of the cast roll at this time was set to 6 m / min.
• the crystalline resin (a) was cooled on a roll to be formed into a long film.
• a film oA made of the crystalline resin (a) was obtained.
• the thickness of the obtained film oA was 68 ⁇ m.
• the obtained film oA was wound around a core and collected to obtain a film roll.
• the in-plane retardation Re (oA) of the film oA at a wavelength of 590 nm was 5 nm
• the thickness direction retardation Rth (oA) was 5 nm
• the slow phase axial direction was the width direction with respect to the longitudinal direction.
• the film oA obtained in (1-1) was pulled out from the film roll, and the liquid composition was applied on the surface of one of the films. Then, the liquid composition was dried. As a result, a layer of a styrene-maleic anhydride copolymer (thickness 10 ⁇ m) was formed as a pB layer, and the refractive index of the film oA in the thickness direction changed to become a pA layer (thickness 68 ⁇ m), and the pA layer and pB. A multilayer film with layers was obtained. The obtained multilayer film was wound around a core and collected to obtain a film roll.
• the pA layer and the pB layer of the multilayer film were peeled off, the optical characteristics of each were measured, and the Re, Rth and Nz coefficients were determined.
• the in-plane retardation Re (pA) of the pA layer is 8 nm
• the thickness direction retardation Rth (pA) is -42 nm
• the birefringence Rth (pA) / d in the thickness direction is -0.6 ⁇ 10 -3 .
• the NZ coefficient NZ (pA) was ⁇ 4.53.
• the in-plane retardation Re (pB) of the pB layer is 1 nm
• the thickness direction retardation Rth (pB) is -59 nm
• the birefringence Rth (pA) / d in the thickness direction is -5.9 ⁇ 10 -3 .
• the NZ coefficient NZ (pA) was 2.50.
• Re (450), Re (550) and Re (650) of the optical film were measured and evaluated whether or not they had reverse wavelength dispersibility. Moreover, the Nz coefficient at the wavelength of 590 nm of the optical film was measured. Furthermore, the bending durability, haze, and display quality improving effect of the optical film were evaluated.
• the A layer and the B layer of the optical film were peeled off, the thickness and the optical characteristics of each were measured, and the Re, Rth and Nz coefficients were obtained. Moreover, the crystallinity of the A layer was measured.
• Example 2 A multilayer film and an optical film were obtained and evaluated by the same operation as in Example 1 except for the following changes.
• the film was stretched by free-end uniaxial stretching along the longitudinal direction, the stretching temperature was 140 ° C., and the stretching ratio was 1.20.
• Tables 1 and 2 show the outlines and results of Examples and Comparative Examples.
• the measurement target is shown in parentheses, for example, the measurement results for the pA layer, pB layer, A layer, and B layer are (pA), (pB), (A) and (A), respectively. It is shown as (B).
• the measured wavelength is shown in parentheses, for example, the measurement result at 590 nm is shown as (590 nm).
• the units are also shown in parentheses.
• the optical film of the present invention produced based on the multilayer film obtained by the production method of the present invention exhibits a good effect as a three-dimensional retardation film in a wide wavelength range. It can be seen that the film can be made into a film having high mechanical strength and a thin thickness, the display quality of the display device can be improved, and the film can be easily manufactured by uniaxial co-stretching.

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