WO2022145172A1 - Film multicouche et son procédé de production - Google Patents

Film multicouche et son procédé de production Download PDF

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Publication number
WO2022145172A1
WO2022145172A1 PCT/JP2021/044537 JP2021044537W WO2022145172A1 WO 2022145172 A1 WO2022145172 A1 WO 2022145172A1 JP 2021044537 W JP2021044537 W JP 2021044537W WO 2022145172 A1 WO2022145172 A1 WO 2022145172A1
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Prior art keywords
layer
film
multilayer film
polymer
stretching
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PCT/JP2021/044537
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English (en)
Japanese (ja)
Inventor
直紀 村田
Original Assignee
日本ゼオン株式会社
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Publication date
Application filed by 日本ゼオン株式会社 filed Critical 日本ゼオン株式会社
Priority to KR1020237019587A priority Critical patent/KR20230122006A/ko
Priority to JP2022572949A priority patent/JPWO2022145172A1/ja
Priority to CN202180085769.6A priority patent/CN116635209A/zh
Publication of WO2022145172A1 publication Critical patent/WO2022145172A1/fr

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Classifications

    • 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
    • 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
    • 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
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks

Definitions

  • the present invention relates to a multilayer film that can be usefully used as an optical film and a method for producing 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.
  • 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.
  • 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. Further, in the case of producing the film as a long film, if the production includes a step of stretching in the width direction, there is a remarkable problem that the long film is likely to be broken during transportation.
  • an object of the present invention is a film that can exhibit a good effect as a three-dimensional retardation film in a wide wavelength range and can be easily manufactured, and a three-dimensional retardation film in a wide wavelength range. It is an object of the present invention to provide a production method capable of easily producing a film capable of exhibiting a good effect.
  • 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 long multilayer film including an A layer made of a crystalline resin (a) and a B layer made of a material (b).
  • One of the crystalline resin (a) and the material (b) is a material having a positive intrinsic birefringence, and the other is a material having a negative intrinsic birefringence.
  • the multilayer film satisfies both the following formulas (1) and (2).
  • the layer B is a multilayer film that satisfies all of the following formulas (3), (4) and (7), or all of the following formulas (5), (6) and (7): Re (450) ⁇ Re (550) ⁇ Re (650) ... (1) 0 ⁇ Nz ⁇ 1 ... (2) nx (b)> ny (b) ...
  • Re (450), Re (550) and Re (650) are the in-plane retardation of the multilayer film at a wavelength of 450 nm, the in-plane retardation of the multilayer film at a wavelength of 550 nm, and the multilayer film at a wavelength of 650 nm, respectively.
  • Nz is the Nz coefficient of the multilayer film
  • nx (b) is the refractive index of the B layer in the in-plane slow phase axial direction Dx of the multilayer film
  • ny (b) is the refractive index of the B layer in the in-plane direction of the multilayer film and in the direction Dy orthogonal to the direction Dx
  • nz (b) is the refractive index of the B layer in the thickness direction Dz of the multilayer film.
  • the crystalline resin (a) and the material (b) are coextruded into a film to provide a pA layer made of the crystalline resin (a) and a pB layer made of the material (b).
  • a multilayer film that can exhibit a good effect as a three-dimensional retardation film in a wide wavelength range and can be easily manufactured, and a good three-dimensional retardation film in a wide wavelength range.
  • a production method capable of easily producing a multilayer film capable of exhibiting various effects.
  • the Nz coefficient of the layered structure 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 layered structure (in-plane direction) and in the direction giving the maximum refractive index.
  • ny represents the refractive index in the in-plane direction of the layered structure and orthogonal to the direction of nx.
  • nz represents the refractive index in the thickness direction of the layered structure.
  • d represents the thickness of the layered structure.
  • the measurement wavelength is 550 nm unless otherwise specified.
  • definitions of nx and ny of the layers constituting the multilayer film definitions different from these definitions are adopted as described separately below.
  • 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 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 slow-phase axis of the layered structure is the in-plane slow-phase axis unless otherwise specified.
  • the multilayer film of the present invention includes an A layer made of a crystalline resin (a) and a B layer made of a material (b).
  • One of the crystalline resin (a) and the material (b) is a material having a positive intrinsic birefringence, and the other is a material having a negative intrinsic birefringence. From the viewpoint of easy availability of the material, it is preferable that the crystalline resin (a) is a material having a positive intrinsic birefringence and the material (b) is a material having a negative intrinsic birefringence.
  • the multilayer film satisfies both the following formulas (1) and (2).
  • Re (450), Re (550) and Re (650) are in-plane lettering at a wavelength of 450 nm for multilayer films, in-plane lettering at wavelengths of 550 nm for multilayer films, and in-plane letters at wavelengths of 650 nm for multilayer films, respectively. It is a ration.
  • Nz is the Nz coefficient of the multilayer film.
  • a film satisfying the formula (1) is called a reverse wavelength dispersive film.
  • a film satisfying the formula (1) can obtain a desired optical effect in a wide wavelength range.
  • the film satisfying the formula (2) is called a three-dimensional retardation film.
  • the film satisfying the formula (2) When the film satisfying the formula (2) is provided in the display device, it can exhibit an effect of reducing the coloring of the display surface when viewed from the tilting direction.
  • the film satisfying both the formulas (1) and (2) had to be produced by a complicated process in the prior art, but the multilayer film of the present invention uses a crystalline resin as the A layer. It can be a film that can be easily manufactured.
  • Re (550) / Re (450) is larger than 1, preferably 1.005 or more.
  • the upper limit of Re (550) / Re (450) may be, for example, 1.5 or less.
  • Re (650) / Re (550) is larger than 1, preferably 1.002 or more.
  • the upper limit of Re (650) / Re (550) may be, for example, 1.5 or less.
  • the values of Re (450), Re (550) and Re (650) can be adjusted to the values suitable for the application of the multilayer film.
  • the preferred range for Re (550) can be 137.5 nm or close to, specifically 127.5 to 147.5 nm, more preferably 130.5 to 144.5 nm.
  • the multilayer film can be used as the ⁇ / 4 wave plate.
  • the preferred range for Re (550) may be at or near 275 nm, specifically preferably in the range of 265 to 285 nm, more preferably in the range of 268 to 282 nm.
  • the multilayer film can be used as the ⁇ / 2 wave plate.
  • Nz is larger than 0, preferably 0.2 or more, while smaller than 1, preferably 0.8 or less.
  • the angle formed by the in-plane slow axis Dx of the multilayer film and the longitudinal direction of the multilayer film can be adjusted to an angle suitable for the application of the multilayer film, but from the viewpoint of ease of manufacture, Dx is a multilayer film. It is preferably at or near the longitudinal direction. In one example, the angle between the in-plane slow axis Dx and the longitudinal direction may be 0 ° or close to it, specifically 0 ° to 5 °, more preferably 0 ° to 3 °.
  • the angle between the in-plane slow axis Dx and the longitudinal direction may be 45 ° or close to it, specifically preferably 40 ° to 50 °, more preferably 42 ° to 48 °. ..
  • the yield can be high when the multilayer film is used for a rectangular display device screen, and the yield can be increased during manufacturing.
  • the transportability of the multilayer film is also improved.
  • the B layer in the multilayer film satisfies all of the following formulas (3), (4) and (7), or satisfies all of the following formulas (5), (6) and (7).
  • Nx (b) and ny (b) are defined with reference to the in-plane slow phase axial direction of the multilayer film, unlike the general definition of the main refractive indexes nx and ny. That is, nx (b) is the refractive index of the B layer in the in-plane slow phase axial direction Dx of the multilayer film, and ny (b) is the in-plane direction of the multilayer film and is orthogonal to the direction Dx. It is the refractive index of the B layer in Dy. nz (b) is the refractive index of the B layer in the thickness direction Dz of the multilayer film.
  • the B layer satisfies all of the formulas (3), (4) and (7) are called positive A plates, and the B layer satisfies all of the formulas (5), (6) and (7).
  • the thing is called a negative A plate.
  • the B layer is a material having a positive birefringence
  • the B layer may satisfy all of the formulas (3), (4) and (7).
  • the B layer is a material having a negative intrinsic birefringence index
  • the B layer may satisfy all of the formulas (5), (6) and (7).
  • the ratio of nx (b) to the larger of ny (b) and nz (b) is larger than 1, preferably 1.0005 or more.
  • the upper limit of the ratio may be, for example, 1.002 or less.
  • the ratio of the smaller of ny (b) and nz (b) to nx (b) is larger than 1, preferably 1.0005 or more.
  • the upper limit of the ratio may be, for example, 1.002 or less.
  • nx (a), ny (a) and nz (a) of the A layer in the multilayer film can be appropriately adjusted so that the optical characteristics of the multilayer film become desired values.
  • nx (a) is the refractive index of the A layer in the in-plane slow phase axial direction Dx of the multilayer film
  • ny (a) is the in-plane direction of the multilayer film and is orthogonal to the direction Dx. It is the refractive index of the A layer in the direction Dy.
  • nz (a) is the refractive index of the A layer in the thickness direction Dz of the multilayer film.
  • the slow axis directions of the A layer and the B layer can be appropriately adjusted so that the optical characteristics of the multilayer film become a desired value, but usually, of the A layer and the B layer, the natural birefringence value is positive.
  • the slow axis direction of the layer of material is parallel to the slow axis direction of the multilayer film, and the slow axis direction of the other layer is orthogonal to or close to the slow axis direction of the multilayer film. Therefore, the slow-phase axial direction of the A layer and the slow-phase axial direction of the B layer are orthogonal to each other or have an angle close to each other.
  • the angle formed by the slow-phase axial direction of the A layer and the slow-phase axial direction of the B layer can be preferably 85 to 90 °, more preferably 88 to 90 °.
  • the multilayer film of the present invention is 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 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 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 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 multilayer film can be used as the optical characteristics of the B layer described above. ..
  • the optical characteristics of the layer in which the two A layers are stacked with the slow axes aligned are shown above. It can be the optical property of the A layer described in 1.
  • the multilayer film has a plurality of A layers, they are made of the same material, and the optical characteristics are uniformly exhibited, the optical characteristics irrelevant to the thickness (nx (a), ny ( For a) and nz (a), etc.), the result of measurement for one of them can be used as the optical property for the A layer.
  • the multilayer film of the present invention it is preferable that one or more layers of A layer are located on the surface of the multilayer film. That is, it is preferable that one or both surfaces of the multilayer film are surfaces in which the A layer is exposed. Having such a configuration makes it particularly easy to manufacture a multilayer film by the manufacturing method of the present invention. Further, it is more preferable that the multilayer film has a layer structure of (A layer) / (B layer) / (A layer). More specifically, it is preferable that the multilayer film has two A layers and a B layer located between them, and both surfaces of the multilayer film are surfaces in a state where the A layer is exposed.
  • the desired optical characteristics of the layer A can be more easily exhibited, and the multilayer film is placed in a high temperature and high humidity environment. It is possible to satisfactorily suppress the occurrence of curl in the case of being scratched.
  • the multilayer 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.
  • 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 obtain a film that satisfies desired optical characteristics even if the thickness is small.
  • the thickness of the multilayer film of the present invention can be preferably 150 ⁇ m or less, more preferably 120 ⁇ m or less, still more preferably 100 ⁇ m or less, and particularly preferably 40 ⁇ m or less.
  • a multilayer film having such a thin thickness can be easily produced by the production method of the present invention.
  • the lower limit of the thickness of the multilayer film is not particularly limited, but may be, for example, 20 ⁇ 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 1 ⁇ m or more, more preferably 3 ⁇ 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 3 ⁇ m or more, while preferably 120 ⁇ m or less, more preferably 100 ⁇ m or less.
  • the multilayer film of the present invention is preferably a co-stretched product. That is, the multilayer film of the present invention is preferably a film obtained by stretching a raw film having a plurality of layers and thereby having a plurality of stretched layers.
  • the raw film is preferably a coextruded product. That is, it is preferable that the raw film is formed into a film having a plurality of layers by extruding a plurality of types of materials from an extruder for coextrusion.
  • An extruder for coextrusion is a member (specifically, coextrusion) having a plurality of inlets into which each of a plurality of types of materials flows in and one outlet in which those materials flow out in layers. It is a device equipped with a die). Specific examples of such co-extrusion and co-stretching will be described later.
  • the crystalline resin (a) constituting the A layer may 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 preferably has a positive intrinsic birefringence.
  • a crystalline polymer having a positive intrinsic birefringence By using a crystalline polymer having a positive intrinsic birefringence, a multilayer film satisfying the requirements of the present invention, particularly the requirement of the formula (2), can be produced particularly easily.
  • 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 layer A 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 layer A usually contains an organic solvent.
  • the organic solvent may not dissolve the crystalline polymer.
  • Preferred organic solvents include, for example, hydrocarbon solvents such as toluene, limonene, decalin; 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 B layer preferably 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, the requirements of the present invention, particularly the requirements of the formula (2), can be met.
  • the filled multilayer film can be produced particularly easily.
  • 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 desired optical properties can be easily imparted to the B layer.
  • 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 desired optical properties can be easily imparted to the B layer.
  • 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 multilayer film of the present invention can be produced by a production method including the following steps (I) to (III).
  • a manufacturing method will be described as a manufacturing method for the multilayer film of the present invention.
  • the step (I) can be performed by co-extruding the crystalline resin (a) and the material (b) with an extruder equipped with a normal co-extrusion molding die.
  • a film forming apparatus equipped with a two-kind three-layer coextrusion molding die is used.
  • a film (I) having a layer structure of (pA layer) / (pB layer) / (pA layer) can be produced.
  • step (II) the surface of the film (I) where the pA layer is located is brought into contact with the solvent.
  • a solvent that can penetrate into the crystalline resin (a) without dissolving it can be appropriately selected.
  • an organic solvent is usually used. Examples of organic solvents include hydrocarbon solvents such as toluene, limonene, decalin; and carbon disulfide.
  • the type of the solvent may be one type or two or more types.
  • the contact in step (II) can be achieved by any operation.
  • Examples of the contact operation include a spray method in which a solvent is sprayed on the surface of the pA layer; a coating method in which the solvent is applied to the surface of the pA layer; and a dipping method in which the film (I) is immersed in the solvent.
  • the dipping method is preferable from the viewpoint of facilitating continuous contact.
  • an efficient treatment can be performed by the dipping method.
  • the pB layer may be dissolved by contact with a solvent.
  • an operation capable of achieving contact of the solvent with only one surface of the film (I) is preferable, and such an operation is an operation other than the dipping method, and is specific.
  • the temperature of the solvent at the time of contact in step (II) is arbitrary as long as the solvent can maintain the liquid state, and thus 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, particularly preferably 5.0 seconds or longer, and preferably 120 seconds or longer. Below, it is more preferably 80 seconds or less, and particularly preferably 60 seconds or less.
  • the contact time is equal to or longer than the lower limit, the Nz coefficient of the A layer can be effectively adjusted by contact with the solvent.
  • the adjustment amount of the Nz coefficient tends not to change significantly. Therefore, when the contact time is equal to or less than the upper limit value, the productivity can be improved without impairing the quality of the layer A.
  • step (II) the refractive index of the pA layer changes to form the qA layer.
  • Such changes caused by contact with a solvent are difficult to obtain by a usual method for producing a retardation film, such as simply stretching a resin for an optical film. Therefore, as a result of such changes, the multilayer film of the present invention can be easily manufactured.
  • Step (III) In the step (III), the film (II) obtained in the step (II) is uniaxially stretched. By stretching the film (II), the qA layer and the pB layer of the film (II) are co-stretched. By such stretching, the molecules of the polymer contained in these layers are oriented in a direction corresponding to the stretching direction. Since the film (II) has undergone the step (II), as a result of the step (III), the film 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. (III) can be easily obtained.
  • the stretching direction in the step (III) there is no limitation on the stretching direction in the step (III), 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 the angle formed by the width direction is neither 0 ° nor 90 ° (that is, the angle formed by the width direction is more than 0 ° and 90 °). Direction that is less than).
  • a film having optical characteristics equivalent to that of the multilayer film of the present invention is to be manufactured by a manufacturing method that does not involve step (II)
  • a plurality of complicated stretching steps are usually required.
  • stretching in the width direction is often required as one of such a plurality of stretching steps, and stretching in the width direction may reduce the strength in the longitudinal direction of the film and cause breakage during transportation.
  • the production method of the present invention is advantageous from the viewpoint of production efficiency because the multilayer film of the present invention can be obtained only by uniaxial stretching.
  • the stretching step can be completed only by stretching in the longitudinal direction or stretching in the diagonal direction without stretching in the width direction, the possibility of breakage during transportation of the film can be reduced.
  • 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 multilayer film as a product.
  • the stretching ratio is equal to or higher than the lower limit, the birefringence can be significantly changed by stretching. Further, when 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 film (III) as a film having desired optical properties can be obtained by stretching in the step (III).
  • the obtained film (III) can be used as it is as the multilayer film of the present invention.
  • the film (III) may be further subjected to an arbitrary treatment to obtain the multilayer film of the present invention.
  • 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 may further include any step in combination with the above-mentioned steps.
  • the step (II) may include a step of removing the solvent adhering to the film (II).
  • Examples of the method for removing the solvent include drying and wiping.
  • the method for producing a multilayer film of the present invention may include a preheat treatment step for bringing the temperature of the film (II) 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 multilayer film obtained in step (III) can be wound into a roll as needed to form a film roll.
  • the multilayer film of the present invention can be produced by a method other than the production method of the present invention described above.
  • the multilayer film of the present invention can also be produced by separately forming a film for a pA layer and a film for a pB layer, laminating them, and using them in place of the film (I).
  • the multilayer 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 thickness of the film was measured using a contact thickness meter (Code No. 543-390 manufactured by Mitutoyo Co., Ltd.). The thickness of each layer in the film composed of a plurality of layers was calculated by observing the cross section of the film under a microscope to determine the thickness ratio, and from the ratio and the thickness of the entire film.
  • the refractive index and in-plane lettering of the film were performed using an ellipsometer (product name "AXoScan", manufactured by AXOMETRICS). As for the measurement positions, nine measurement points were determined at intervals of one tenth of the film width on a line parallel to the width direction of the film, and the average of them was calculated.
  • Measurements were made at each measurement point at wavelengths of 450 nm, 550 nm and 650 nm, and in-plane retardation Re450 (unit: nm) at measurement wavelength 450 nm, in-plane retardation Re550 (unit: nm) at measurement wavelength 550 nm, and measurement wavelength.
  • the in-plane retardation Re650 (unit: nm) at 650 nm and nx, ny and nz at the measurement wavelength of 550 nm were determined.
  • the slow-phase axial direction of the film is determined by measurement using an ellipsometer, and the film is formed.
  • the refractive index of the layers constituting the above was determined with reference to the direction.
  • the NZ coefficient of the multilayer film and the crossing angle of the slow axis of the A layer and the B layer were also measured.
  • the crystallinity of the A layer was confirmed by X-ray diffraction according to JIS K0131. Specifically, a wide-angle X-ray diffractometer (“RINT 2000” manufactured by Rigaku Co., Ltd.) was used to obtain the diffracted X-ray intensity from the crystallized portion, and the following formula was obtained from the ratio with the total diffracted X-ray intensity. The crystallinity was determined by (I).
  • Xc K ⁇ Ic / It (I)
  • Xc represents the crystallinity of the test sample
  • Ic represents the diffraction X-ray intensity from the crystallized portion
  • It represents the entire diffraction X-ray intensity
  • K represents the correction term.
  • the obtained multilayer film (for example, in Examples 1 and 2 immediately after the end of step (III)) was conveyed at a speed of 20 m / min, and the transferred state in the step of forming a take-up film roll was observed, and the multilayer film was transferred. The presence or absence of defects due to breakage was evaluated.
  • the sample was observed from the top surface, and the difference in dimensional change between one of the two layers (A layer and B layer) constituting the sample and the other was evaluated. Specifically, on each of the four sides of the sample, the distance from the side of the layer located on the outer side of the two types of layers to the side of the layer located on the inner side was measured.
  • the maximum value of the four measured values of the three samples is less than 1 mm, it is regarded as "good”, when it is 1 mm or more and less than 2 mm, it is regarded as "possible”, and when it is 2 mm or more, it is regarded as "impossible". evaluated.
  • 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 8,750 and 28,100, respectively, and the molecular weight distribution (Mw / Mn) obtained from these. was 3.21.
  • 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 93 ° C., the melting point (Tm) was 262 ° C., and the ratio of racemo diad was 89%.
  • Antioxidant tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane was added to 100 parts of the hydride of the obtained ring-opening polymer of dicyclopentadiene.
  • BASF Japan "Irganox (registered trademark) 1010" After mixing 1.1 parts, a twin-screw extruder equipped with four die holes with an inner diameter of 3 mm ⁇ (product name "TEM-37B", manufactured by Toshiba Machine Co., Ltd.) ).
  • a mixture of a hydride of a ring-opening polymer of dicyclopentadiene and an antioxidant is formed into a strand by hot melt extrusion molding, and then shredded with a strand cutter to form a crystal as a crystalline resin (a).
  • Pellets of sex resin COP1 were obtained.
  • a solution was prepared in which 2.2 parts of maleic anhydride and 0.04 parts of benzoyl peroxide were dissolved in 9 parts of methyl ethyl ketone. This solution was added to the mixture in the autoclave 10 hours after the start of heating. After the addition, the temperature was kept at 80 ° C. for another 2 hours to continue the reaction. As a result, the reaction solution 1 was obtained. 20 parts of methyl ethyl ketone was added to the reaction solution 1 and the mixture was cooled to room temperature. This was poured into 120 parts of methanol with vigorous stirring, separated by filtration and dried to obtain a white powdery polymer.
  • the white powder polymer was extruded with a uniaxial extruder having a screw diameter of 40 mm at a cylinder temperature of 220 ° C. and a screw rotation speed of 100 rpm to obtain pellets of the styrene-maleic anhydride copolymer PS1 as the material (b).
  • the glass transition temperature of PS1 was 128 ° C.
  • a film forming device for coextrusion molding of two types and three layers a type of forming device that can form a three-layer structure film with two types of resin
  • a uniaxial extruder equipped with a double flight type screw equipped with a uniaxial extruder equipped with a double flight type screw.
  • the pellets of COP1 obtained in Production Example 1 were put into one of the single-screw extruders of the film forming apparatus and melted. Further, the pellets of PS1 obtained in Production Example 2 were put into the other uniaxial extruder of the film forming apparatus and melted.
  • the melted COP1 at 290 ° C. was supplied to one manifold of the multi-manifold die (die slip surface roughness Ra: 0.1 ⁇ m) through a leaf disk-shaped polymer filter having an opening of 10 ⁇ m. Further, the melted PS1 at 250 ° C. was supplied to the other manifold of the multi-manifold die through a leaf disk-shaped polymer filter having an opening of 10 ⁇ m.
  • COP1 and PS1 were simultaneously extruded from the multi-manifold die at 300 ° C. to form a film.
  • the molded film-shaped molten resin was cast on a cast roll adjusted to a surface temperature of 80 ° C. to obtain a long film (I) including a pA layer made of COP1 and a pB layer made of PS1. At this time, the thickness of the film (I) was adjusted by adjusting the rotation speed of the screw and the rotation speed of the cast roll.
  • a part of the obtained film (II) was cut out, and the thickness of each layer and the slow phase axial direction were measured. Further, the qA layer and the pB layer were peeled off to form separate films, and the slow phase axial direction and the refractive index were measured for each.
  • the refractive indexes nx (qa), ny (qa) and nz (qa) of the qA layer, and the refractive indexes nx (pb), ny (pb) and nz (pb) of the pB layer are the slow axes of the film (II). The direction was determined as the nx direction.
  • the slow axis of the qA layer coincided with the slow axis of the film (II), which was parallel to the longitudinal direction of the film (II).
  • the transportability of the multilayer film was evaluated by observing the transport state immediately after the step (III). A part of the obtained multilayer film was cut out, and the total thickness of the multilayer film, the thickness of each layer, the slow phase axial direction, Re (450), Re (550), Re (650) and the NZ coefficient were measured. The A layer and the B layer were peeled off to form separate films, and the slow phase axial direction and the refractive index were measured for each, and the intersection angle between the slow phase axis of the A layer and the slow phase axis of the B layer was determined.
  • the refractive indexes nx (a), ny (a) and nz (a) of the A layer, and the refractive indexes nx (b), ny (b) and nz (b) of the B layer are in the slow phase axial direction of the multilayer film. It was calculated as the nx direction.
  • the slow-phase axis of the A layer coincided with the slow-phase axis of the multilayer film, and these were in the direction parallel to the longitudinal direction of the multilayer film.
  • the crystallinity of layer A was measured.
  • Example 2 A multilayer film was obtained and evaluated by the same operation as in Example 1 except for the following changes. -The thickness of the film (I) was changed by changing the molding conditions of the film (I) in (1-1). -The stretching conditions of (1-3) were changed. An oblique stretching machine was used as the stretching machine, and the film was uniaxially stretched in a direction of 45 ° with respect to the longitudinal direction of the film. However, the stretching ratio and the stretching temperature were not changed and were set to 1.7 times and 140 ° C.
  • the slow axis of the qA layer in the film (II) coincided with the slow axis of the film (II), and these were in the direction parallel to the longitudinal direction of the film (II).
  • the slow-phase axis of layer A in the multilayer film coincided with the slow-phase axis of the multilayer film, and these were oriented at an angle of 45 ° with the longitudinal direction of the multilayer film.
  • Example 3 (3-1. Film for pA layer) An extruder equipped with a leaf disk-shaped polymer filter (filtration accuracy 10 ⁇ m), a single-screw extruder with a screw diameter of 50 mm, and a T-shaped die was prepared. Using this extrusion molding apparatus, the pellets of COP1 obtained in Production Example 1 were melt-extruded into a film at an extrusion temperature of 300 ° C. The extruded film-like resin is cooled by passing it through three cooling drums (diameter 250 mm, drum temperature 80 ° C., take-up speed 1.0 m / s) to form a pA layer film having a thickness of 26 ⁇ m and a width of 600 mm. A transparent film was obtained.
  • Steps (II) and (III)) A multilayer film was obtained and evaluated by the same operations as in (1-2) (step (II)) and (1-3) (step (III)) of Example 1 except for the following changes. -The film (I') obtained in (3-3) was used instead of the film (I) obtained in (1-1). -The stretching conditions of (1-3) were changed. An oblique stretching machine was used as the stretching machine, and the film was uniaxially stretched in a direction of 45 ° with respect to the longitudinal direction of the film. However, the stretching ratio and the stretching temperature were not changed and were set to 1.7 times and 140 ° C (same as in Example 2).
  • the slow axis of the qA layer in the film (II) coincided with the slow axis of the film (II), and these were in the direction parallel to the longitudinal direction of the film (II).
  • the slow-phase axis of layer A in the multilayer film coincided with the slow-phase axis of the multilayer film, and these were oriented at an angle of 45 ° with the longitudinal direction of the multilayer film.
  • the transportability was evaluated by observing the transport condition immediately after bonding.
  • the slow-phase axial direction, Re (450), Re (550) and Re (650) and NZ coefficient of the obtained multilayer film were measured.
  • the shrinkage and curl of the multilayer film due to high temperature and high humidity load were evaluated.
  • the obtained multilayer film was cut off, and the A'layer and the B'layer were peeled off to form separate films, and the slow phase axial direction and the refractive index were measured for each.
  • the slow axis of the A'layer coincided with the slow axis of the multilayer film, which were at an angle of 90 ° with the longitudinal direction of the multilayer film.
  • Table 1 shows the outline and results of Examples and Comparative Examples.
  • the measurement results for the A'layer and the B'layer are shown in the corresponding rows of the A layer and the B layer.

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  • General Physics & Mathematics (AREA)
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Abstract

L'invention concerne un long film multicouche comprenant : une couche A comprenant une résine cristalline (a) ; et une couche B comprenant un matériau (b). La résine cristalline (a) ou le matériau (b) est un matériau ayant une biréfringence intrinsèque positive et l'autre est un matériau ayant une biréfringence intrinsèque négative. Le retard et les indices de réfraction du film multicouche et de la couche B satisfont des conditions spécifiées. Le film multicouche est idéalement co-étiré. L'invention concerne également un procédé de production de film multicouche qui comprend une étape dans laquelle un film long spécifié (I) est mis en contact avec un solvant.
PCT/JP2021/044537 2020-12-28 2021-12-03 Film multicouche et son procédé de production WO2022145172A1 (fr)

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