WO2022145174A1 - Film optique et son procédé de fabrication - Google Patents

Film optique et son procédé de fabrication Download PDF

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Publication number
WO2022145174A1
WO2022145174A1 PCT/JP2021/044567 JP2021044567W WO2022145174A1 WO 2022145174 A1 WO2022145174 A1 WO 2022145174A1 JP 2021044567 W JP2021044567 W JP 2021044567W WO 2022145174 A1 WO2022145174 A1 WO 2022145174A1
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film
optical film
optical
polymer
thickness direction
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PCT/JP2021/044567
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English (en)
Japanese (ja)
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浩成 摺出寺
恭輔 井上
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日本ゼオン株式会社
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Priority to JP2022572951A priority Critical patent/JPWO2022145174A1/ja
Publication of WO2022145174A1 publication Critical patent/WO2022145174A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements

Definitions

  • the present invention relates to an optical film and a method for manufacturing the same.
  • a resin containing a crystalline polymer is generally superior in heat resistance to a resin containing an amorphous polymer. Therefore, a resin containing a crystalline polymer is used as a material for an optical film that is required to have heat resistance (Patent Documents 1 and 2).
  • the optical film When the optical film is used as a protective film for an optical element such as a polarizing element, it is preferable that the optical film does not change the optical characteristics required for the optical element. However, when an optical film made of a resin containing a crystalline polymer is combined with another optical element, the original optical characteristics of the optical element may be significantly changed. For example, when a polarizing plate in which a polarizing element and an optical film are combined is incorporated into an image display device, the optical film may change the color tone when observed from an inclined direction. On the other hand, the optical element can be used in a high temperature environment.
  • the optical film is less deformed at a high temperature, and for example, it is preferable that the occurrence of wrinkles at a high temperature is reduced. Therefore, it is an optical film made of a crystalline resin, and when combined with other optical elements, the original optical characteristics of the optical element are not significantly changed, and the occurrence of wrinkles at high temperatures is reduced. A film and a method for manufacturing the optical film are required.
  • the present inventor has formed an optical film from a resin having crystalline properties, and the retardation Rth, the in-plane retardation, and the heat of the optical film in the thickness direction of the optical film.
  • the above problems can be solved by keeping the expansion rate within a predetermined range, and have completed the present invention. That is, the present invention provides the following.
  • the optical film has a first surface and a second surface.
  • the central part which is the part including the center in the thickness direction
  • the first outer portion which is outside in the thickness direction with respect to the central portion and includes the first surface, and the first outer portion. It is composed of a second outer portion, which is outside in the thickness direction with respect to the central portion and is a portion including the second surface.
  • the retardation Rth in the thickness direction is positive in the central portion, and the retardation Rth is positive.
  • the retardation Rth in the thickness direction is negative in at least one of the first outer portion and the second outer portion.
  • the optical film according to [1]. [3] The optical film according to [1] or [2], which is long. [4] The optical film according to any one of [1] to [3], wherein the intrinsic birefringence value of the resin containing the crystalline polymer is positive.
  • the total thickness of the solvent layer formed on at least one surface of the film (a) in the step (2) is 10 ⁇ m or less. Manufacturing method of optical film.
  • an optical film made of a crystalline resin does not significantly change the original optical characteristics of the optical element when combined with other optical elements, and the occurrence of wrinkles at high temperatures is reduced. It is possible to provide an optical film and a method for manufacturing the optical film.
  • FIG. 1 is a sectional view schematically showing an optical film according to an embodiment of the present invention.
  • 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 upper limit of the length of the film is not particularly limited and may be, for example, 100,000 times or less with respect to the width.
  • the angle formed by the optical axis (slow phase axis, transmission axis, absorption axis, etc.) of each layer in the member having a plurality of layers is the angle when the layer is viewed from the thickness direction unless otherwise specified. Represents.
  • the diagonal direction of a long film indicates an in-plane direction of the film, which is neither parallel nor perpendicular to the longitudinal direction of the film, unless otherwise specified.
  • the front direction of a certain film means the normal direction of the main surface of the film, and specifically, the direction of the polar angle 0 ° and the azimuth angle 0 ° of the main surface, unless otherwise specified. Point to.
  • the tilting direction of a film means a direction that is neither parallel nor perpendicular to the main surface of the film, and specifically, the polar angle of the main surface is larger than 0 ° and 90. Points in a range smaller than °.
  • 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.
  • nx represents the refractive index in the direction perpendicular to the thickness direction of the layer or film (in-plane direction) and in the direction giving the maximum refractive index.
  • ny represents the refractive index in the in-plane direction of the layer or film and orthogonal to the direction of nx.
  • nz represents the refractive index in the thickness direction of the layer or film.
  • d represents the thickness of the layer or film.
  • the measurement wavelength is 590 nm unless otherwise specified.
  • the longitudinal direction of the long film is usually parallel to the film transport direction in the production line.
  • the MD direction (machine direction) is the transport direction of the film in the production line, and is usually parallel to the longitudinal direction of the long film.
  • the TD direction (transverse direction) is a direction parallel to the film surface, a direction perpendicular to the MD direction, and usually parallel to the width direction of a long film.
  • the optical film according to the embodiment of the present invention is made of a resin containing a polymer having crystallinity, the absolute value of the retardation Rth in the thickness direction is 15 nm or less, and the in-plane retardation Re is 10 nm or less. Yes, the coefficient of thermal expansion is 0% or more and 7.5% or less.
  • the optical film of the present embodiment is combined with other optical elements, the original optical characteristics of the optical elements are not significantly changed, and the occurrence of wrinkles at high temperatures is reduced. Even if the optical film of the present embodiment is incorporated into an image display device as a polarizing plate in combination with a polarizing element, for example, the color tone when observed from an inclined direction does not change significantly.
  • the optical film according to the present embodiment is made of a resin containing a polymer having crystallinity, and is formed of the resin.
  • 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).
  • a polymer having crystallinity may be referred to as a “crystalline polymer”.
  • a resin containing a crystalline polymer may be referred to as a "crystalline resin”. This crystalline resin is preferably a thermoplastic resin.
  • the crystalline polymer preferably has a positive intrinsic birefringence.
  • a crystalline polymer having positive intrinsic birefringence an optical film having desired optical properties can be easily produced.
  • 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.
  • the cycloalkane structure is preferable because it is easy to obtain an optical 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 an optical 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 optical film is not particularly limited, but is usually higher than a certain level.
  • the high crystallinity of the crystalline polymer contained in the optical film can be confirmed by the magnitude of the coefficient of thermal expansion described later.
  • 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 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 not more than the lower limit of the above range, the heat resistance of the optical film can be enhanced.
  • the upper limit of the proportion of the crystalline polymer may be 100% by weight or less.
  • the crystalline resin 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 absolute value of retardation Rth in the thickness direction is usually 15 nm or less, preferably 3 nm or less, more preferably 1 nm or less, usually 0 nm or more, and ideally 0 nm.
  • the absolute value of the retardation Rth in the thickness direction is equal to or less than the upper limit value, it is possible to prevent the optical characteristics of the optical element from being significantly changed when combined with other optical elements.
  • an optical film is used as an element of an image display device (for example, a protective film for a polarizing element), it is possible to reduce a change in the tint of an image when observed from an inclined direction.
  • the sign of the retardation Rth in the thickness direction (hereinafter, "letteration in the thickness direction” is also simply referred to as "Rth") changes in the thickness direction.
  • the Rth code is different between the central portion in the thickness direction of the optical film and at least one of the first outer portion and the second outer portion of the optical film, and the Rth of the central portion.
  • the sign is positive and the sign of at least one of the first outer portion and the second outer portion is negative, and the sign of Rth in the central portion is positive and the first outer portion.
  • the sign of Rth of both of the second outer portions is negative.
  • FIG. 1 is a sectional view schematically showing an optical film according to an embodiment of the present invention.
  • the optical film 100 is composed of a central portion 110, a first outer portion 121, and a second outer portion 122.
  • the optical film 100 has a first surface 100U and a second surface 100D.
  • the center 111 in the thickness direction of the optical film 100 is a surface equidistant from the first surface 100U and the second surface 100D.
  • the central portion 110 is a portion including the central 111 in the thickness direction.
  • the first outer portion 121 is located outside the central portion 110 in the thickness direction and includes the first surface 100U.
  • the second outer portion 122 is located outside the central portion 110 in the thickness direction and includes the second surface 100D.
  • the Rth value of the central portion 110 is positive, and the Rth value of the first outer portion 121 and the second outer portion 122 are both negative.
  • the optical film 100 in which the Rth value of the central portion 110 is positive and the Rth value of the first outer portion 121 and the second outer portion 122 is negative is manufactured from the crystalline resin by extrusion molding. It can be produced by a production method including coating an organic solvent on both sides of the extruded film to form a solvent layer. The reason why the optical film 100 can be manufactured by this manufacturing method is presumed as follows, but the present invention is not limited.
  • the extruded film is slightly stretched in the transport direction when the crystalline resin is extruded, and the thickness direction retardation Rth has a positive value.
  • the solvent penetrates into the extruded film. It is considered that the action of the infiltrated solvent causes microBrownian motion in the molecules of the crystalline polymer in the extruded film, and the molecular chains of the extruded film are oriented.
  • the surface area of the extruded film is large on the front surface and the back surface, which are the main surfaces. Therefore, as for the infiltration rate of the solvent, the infiltration rate in the thickness direction through the front surface or the back surface is high. Then, the orientation of the molecular chains of the crystalline polymer can proceed so that the molecules of the polymer are oriented in the thickness direction. Further, by applying the solvent to the extruded film instead of immersing the extruded film in the solvent, the solvent penetrates into the outer portion in the thickness direction of the extruded film, but reaches the central portion in the thickness direction of the extruded film. It is thought that it will not be reached.
  • the Rth in the central portion of the optical film is a positive value that is the same as or close to the value of the extruded film before the solvent is applied, and the first outer portion and the second outer portion of the optical film. It is considered that the refractive index in the thickness direction becomes large and Rth becomes a negative value.
  • the outer part of the optical film including the surface coated with the solvent has a large refractive index in the thickness direction, and the outer part has a negative Rth. It is considered to be a value. Further, it is considered that the outer portion of the optical film including the surface not coated with the solvent has a positive Rth value as in the central portion.
  • the optical film of the present embodiment has an in-plane retardation Re of usually 10 nm or less, preferably 5 nm or less, more preferably 3 nm or less, and usually 0 nm or more.
  • the in-plane retardation Re is not more than the upper limit value, the influence of the optical film on the original optical characteristics of the optical element can be reduced when the optical film is used as a protective film for the optical element.
  • the film retardation can be measured using a phase difference meter (for example, "AXoScan OPMF-1" manufactured by AXOMETRICS).
  • a phase difference meter for example, "AXoScan OPMF-1" manufactured by AXOMETRICS.
  • the optical film of the present embodiment has a coefficient of thermal expansion of usually 7.5% or less, preferably 7% or less, more preferably 6.5% or less, and usually 0% or more.
  • the coefficient of thermal expansion of the optical film is not more than the upper limit value, the heat resistance of the optical film can be improved.
  • the coefficient of thermal expansion is a value measured under the following conditions.
  • a sample is obtained by cutting out an optical film into a rectangular shape. This cutting is performed so that the longitudinal direction of the rectangular sample coincides with the MD direction (longitudinal direction in the long film) or the TD direction (width direction in the long film) of the film.
  • the linear expansion ⁇ L from a temperature of 20 ° C. to 130 ° C. is measured at a heating rate of 10 ° C./min.
  • the coefficient of thermal expansion RTMA of the optical film measured under the above conditions can be an index of the degree of crystallinity of the crystalline resin contained in the optical film.
  • the coefficient of thermal expansion of the optical film is within the above range, the heat resistance of the optical film can be improved.
  • the thickness of the optical film can be appropriately set according to the application of the optical film.
  • the thickness d of the optical film is preferably 5 ⁇ m or more, more preferably 10 ⁇ m or more, preferably 80 ⁇ m or less, and more preferably 70 ⁇ m or less.
  • the thickness d of the optical film is not less than the lower limit of the above range, the handleability can be improved and the strength can be increased. Further, when the thickness d of the optical film is not more than the upper limit value, it is easy to wind the long optical film.
  • the optical film of the present embodiment may be a single-wafer film or a long film.
  • Optical films are usually manufactured as long films. Long optical films can be efficiently combined with other long optical elements using the roll-to-roll method. Therefore, the optical film is preferably long.
  • the optical film of the present embodiment preferably has high transparency.
  • the specific total light transmittance of the optical film is preferably 80% or more, more preferably 85% or more, and particularly preferably 88% or more.
  • the total light transmittance of the optical film is usually 100% or less.
  • the total light transmittance of the optical film can be measured in the wavelength range of 400 nm to 700 nm using an ultraviolet / visible spectrometer.
  • the optical film of the present embodiment can be produced by any method.
  • the optical film can be manufactured by a manufacturing method including the following steps.
  • Step (1) A step of extruding a resin containing a crystalline polymer to obtain a film (a).
  • Step (2) A step of applying a solvent on at least one of the two surfaces of the film (a) to form a solvent layer to obtain a film (a').
  • Step (3) A step of drying the solvent layer of the film (a') to obtain the film (b).
  • the normal step (2) is performed after the step (1).
  • the normal step (3) is performed after the step (2).
  • the method for producing an optical film of the present embodiment may include any step in addition to the steps (1) to (3).
  • the resin containing the crystalline polymer is extruded to obtain a film (a).
  • the resin containing the crystalline polymer used in the step (1) can be the same as the resin containing the crystalline polymer contained in the optical film.
  • the crystallinity of the crystalline polymer contained in the film (a) is preferably small.
  • the specific crystallinity is preferably less than 10%, more preferably less than 5%, and particularly preferably less than 3%.
  • the manufacturing conditions by the extrusion molding method are as follows, for example.
  • the cylinder temperature (molten resin temperature) is preferably Tm or higher, more preferably “Tm + 20 ° C” or higher, preferably “Tm + 100 ° C” or lower, and more preferably “Tm + 50 ° C” or lower.
  • the cooling body that the molten resin extruded into a film comes into contact with first is not particularly limited, but a cast roll is usually used.
  • the cast roll temperature is preferably "Tg-50 ° C.” or higher, preferably "Tg + 70 ° C.” or lower, and more preferably "Tg + 40 ° C.” or lower.
  • the cooling roll temperature is preferably "Tg ⁇ 70 ° C.” or higher, more preferably “Tg ⁇ 50 ° C.” or higher, preferably “Tg + 60 ° C.” or lower, and more preferably “Tg + 30 ° C.” or lower.
  • Tm represents the melting point of the crystalline polymer
  • Tg represents the glass transition temperature of the crystalline polymer.
  • the thickness of the film (a) is preferably set according to the thickness of the optical film to be manufactured. Usually, by applying the solvent to the film (a) in the step (2), the thickness of the film is increased. On the other hand, when the method for producing an optical film includes a stretching step, the thickness of the film is reduced by stretching. Therefore, the thickness of the film (a) may be set in consideration of the change in the thickness in the step after the step (1) as described above. According to extrusion molding, the thickness of the film (a) can be easily controlled.
  • the film (a) may be a single-wafer film, but is preferably a long film.
  • the optical film can be continuously produced by the roll-to-roll method, so that the productivity of the optical film can be effectively increased.
  • the film (a) preferably has a small content of the organic solvent, and more preferably does not contain the organic solvent.
  • the ratio (solvent content) of the organic solvent contained in the film (a) to 100% by weight of the film (a) is preferably 1% or less, more preferably 0.5% or less, still more preferably 0.1%. It is less than or equal to, ideally 0.0%. Since the amount of the organic solvent contained in the film (a) before applying the organic solvent is small, it becomes easy to control the retardation Rth in the thickness direction of the optical film by the amount of the organic solvent applied.
  • a film (a) having a small content of organic solvent and usually containing no organic solvent can be obtained.
  • the solvent content of the film (a) can be measured by the density.
  • the in-plane retardation Re of the film (a) is preferably 10 nm or less, more preferably 8 nm or less, still more preferably 5 nm or less, and usually 0 nm or more.
  • the retardation Rth of the film (a) in the thickness direction is preferably 15 nm or less, more preferably 10 nm or less, still more preferably 8 nm or less, preferably 0 nm or more, more preferably 0.5 nm or more, still more preferably 1 nm or more. Is.
  • Such a low phase difference of the film (a) makes it easy to adjust the phase difference of the optical film to a desired range.
  • step (2) a solvent is applied on at least one surface of the two surfaces of the film (a) to form a solvent layer to obtain a film (a').
  • a film having a changed refractive index in the thickness direction in the vicinity of the surface can be obtained.
  • the solvent is usually an organic solvent.
  • the organic solvent a solvent that does not dissolve the crystalline polymer can be used.
  • preferable organic solvents include hydrocarbon solvents such as toluene, limonene and decalin; carbon disulfide; preferably toluene.
  • the type of the organic solvent may be one kind or two or more kinds.
  • the solvent may be applied on one surface, or the solvent may be applied on both of the two surfaces.
  • a method capable of controlling the thickness of the solvent layer formed on the surface of the film (a) by coating is preferably used.
  • the coating method include a wire bar coating method, a spray method, a roll coating method, a gravure coating method, a die coating method, a curtain coating method, a slide coating method, and an extrusion coating method, and the die coating method is preferable.
  • the total thickness of the solvent layer formed on at least one surface of the film (a) is usually 10 ⁇ m or less, preferably 9 ⁇ m or less, more preferably 8 ⁇ m or less, and usually larger than 0 ⁇ m.
  • the total thickness is the total thickness of the two solvent layers when the solvent is applied to both of the two surfaces of the film (a) to form the two solvent layers, and the film (a).
  • the solvent is applied to only one of the two surfaces to form only one solvent layer, it is the thickness of the one solvent layer.
  • the absolute value of the retardation Rth in the thickness direction of the optical film can be adjusted to a desired range. As the total thickness of the solvent layer is increased, the retardation Rth in the thickness direction of the film (b) tends to be smaller.
  • the absolute value of the retardation Rth in the thickness direction of the film (b) can be adjusted by adjusting the total thickness of the solvent layer according to the value of the retardation Rth in the thickness direction of the film (a). Further, by keeping the total thickness of the solvent layer within the above range, it is possible to reduce the occurrence of wrinkles in the film conveyed in the step (3) and improve the handleability of the film.
  • the solvent layer of the film (a') is dried to obtain the film (b). Thereby, the solvent in the solvent layer can be removed.
  • the drying method any method can be adopted depending on the boiling point of the solvent used. Examples of the drying method include natural drying, heat drying, vacuum drying, vacuum heating drying and the like.
  • the film (b) may contain a solvent.
  • the size of the retardation Rth in the thickness direction can be adjusted in the film (b).
  • the film (b) can be obtained as an optical film.
  • the method for producing the optical film may optionally include the step (4) in addition to the steps (1) to (3).
  • the step (4) is a step of stretching the film (b) obtained in the step (3). By stretching, the molecules of the crystalline polymer contained in the film (b) can be oriented in a direction corresponding to the stretching direction. Therefore, according to the step (4), optical characteristics such as birefringence Re / d in the in-plane direction, birefringence Re / d in the thickness direction, birefringence Rth / d in the thickness direction, and retardation Rth in the thickness direction of the film (b). In addition, the thickness d can be adjusted.
  • the stretching direction there is no limitation on the stretching direction, and examples thereof include a longitudinal direction, a width direction, and an oblique direction.
  • the diagonal direction is a direction perpendicular to the thickness direction and is neither parallel nor perpendicular to the width direction.
  • the stretching direction may be one direction or two or more directions.
  • a uniaxial stretching method such as a method of uniaxially stretching the film in the longitudinal direction (longitudinal uniaxial stretching method), a method of uniaxially stretching the film in the width direction (horizontal uniaxial stretching method); Biaxial stretching method such as simultaneous biaxial stretching method in which the film is stretched in the direction and width direction at the same time, and sequential biaxial stretching method in which the film is stretched in one of the longitudinal direction and the width direction and then stretched in the other direction; A method of stretching in a direction (diagonal stretching method); and the like can be mentioned.
  • the uniaxial stretching method there are a fixed uniaxial stretching method in which the end portion of the film is fixed, and a free uniaxial stretching method in which the end portion of the film is not fixed.
  • the draw ratio is preferably 1 time or more, more preferably 1.01 times or more, preferably 1.5 times or less, and more preferably 1.4 times or less. It is desirable that the specific draw ratio is appropriately set according to factors such as the optical characteristics, thickness, and strength of the film (b) to be stretched. When the stretching ratio is equal to or higher than the lower limit of the above range, the birefringence can be significantly changed by stretching. Further, when the draw ratio is not more than the upper limit of the above range, the direction of the slow phase axis can be easily controlled and the 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.
  • a film (c) as a stretched film (b) can be obtained.
  • the thickness direction retardation Rth of the film (c) can be adjusted. Therefore, by stretching the film (b) by the step (4), the optical characteristics of the film (c) can be adjusted to a desired range as an optical film, and the film (c) can be obtained as an optical film.
  • the step (4) may further include any of the following steps in addition to the step of stretching the film (b) (referred to as step (4b)).
  • Step (4a) A step of preheating the film (b).
  • Step (4c) A step of heat-treating the film (b).
  • Step (4d) A step of cooling the film (c).
  • step (4) includes step (4a)
  • step (4a) is performed before normal step (4b).
  • step (4) includes step (4c) is performed after normal step (4b).
  • step (4d) is performed after the normal steps (4a) to (4c).
  • the heat treatment By heat treatment, the crystallinity of the crystalline polymer contained in the stretched film (b) can be promoted, and the coefficient of thermal expansion can usually be lowered. Therefore, the heat resistance of the optical film can be improved by the step (4c).
  • the heat treatment temperature is usually equal to or higher than the glass transition temperature of the crystalline polymer and lower than the melting point of the crystalline polymer of Tm. More specifically, the heat treatment temperature is preferably Tg ° C. or higher, more preferably Tg + 10 ° C. or higher, preferably Tm-20 ° C. or lower, and more preferably Tm-40 ° C. or lower. In the above temperature range, crystallization of the crystalline polymer can be rapidly promoted while suppressing white turbidity due to the progress of crystallization.
  • the heat treatment treatment time is preferably 1 second or longer, more preferably 5 seconds or longer, preferably 30 minutes or shorter, and more preferably 15 minutes or shorter.
  • the preheating temperature in the step (4a) is usually the same as the stretching temperature in the step (4b), 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 cooling temperature in the step (4d) is set lower than the heating temperature in the step (step (4b) or step (4c)) performed before the step (4d).
  • the cooling time is arbitrary, preferably 1 second or longer, more preferably 5 seconds or longer, and preferably 30 seconds or shorter, more preferably 20 seconds or shorter.
  • the method for manufacturing the optical film includes the step (4)
  • the optical film after the step (4) may contain residual stress. Therefore, the method for producing an optical film may include, for example, a step of thermally shrinking the stretched film to remove residual stress.
  • residual stress can usually be removed by causing the film to undergo thermal shrinkage in an appropriate temperature range while keeping the stretched film flat.
  • a long film (a) can be manufactured from a crystalline resin, and a long optical film can be manufactured from the film (a).
  • the method for producing an optical film may include a step of winding the long optical film thus produced into a roll shape. Further, the method for producing an optical film may include a step of cutting a long optical film into a desired shape.
  • the optical film of the present embodiment is suitable for optical applications such as a protective film for an optical element and a base film for forming an optical element.
  • the hydrogenation rate of the polymer was measured by 1 H-NMR 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 film to be measured was cut to a size of 50 mm ⁇ 150 mm to obtain a film piece.
  • a tensile tester with a constant temperature and humidity chamber (“5564 type” manufactured by Instron) was used to freely uniaxially stretch the film piece.
  • the stretching temperature was (Tg + 15 ° C. of the resin forming the film), and the tensile speed was 1.5 times / min.
  • the slow-phase axial direction of the stretched film piece is determined by "AXoScan OPMF-1" manufactured by AXOMETRICS, and when the stretched direction and the slow-phase axial direction are parallel, the intrinsic birefringence of the resin constituting the film piece is determined. Is positive, and when the stretching direction and the slow-phase axial direction are perpendicular to each other, the intrinsic birefringence of the resin constituting the film piece is negative.
  • 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 retardation Rth in the thickness direction of the film to be measured was measured and set to Rth0.
  • the measurement was performed by "AXoScan OPMF-1" manufactured by AXOMETRICS.
  • the measurement was performed at a wavelength of 590 nm.
  • the following measurements were also performed with a similar device at a measurement wavelength of 590 nm.
  • the film was thinned by scraping a thickness of 1 ⁇ m from one surface of the film with sandpaper (Nos. 4000, 8000, 15000).
  • the retardation Rth in the thickness direction of the thinned film was measured and set to Rth1.
  • the operation of scraping a 1 ⁇ m surface layer from one surface of the film to thin the film and then measuring the retardation Rth of the thinned film is that the retardation Rth1 in the thickness direction of the thinned film has a code different from the code of Rth0. I repeated until it became. However, even if the surface layer is scraped to the center in the thickness direction of the film, if the sign of the retardation Rth1 in the thickness direction is not different from that of Rth0, the operation of scraping the surface layer of the film is completed.
  • Rth1 has a code different from the code of Rth0 while the surface layer is scraped to the center in the thickness direction of the film
  • the code of retardation Rth in the thickness direction of the central portion of the film to be measured is opposite to that of Rth0. It is a code, and the code of the retardation Rth in the thickness direction of the first outer part and the second outer part is the same as the code of Rth0. If the sign of the lettering Rth1 in the thickness direction does not differ from that of Rth0 even if the surface layer is scraped to the center in the thickness direction of the film, the lettering in the thickness direction of the center part, the first outer part, and the second outer part It is assumed that Rth has the same code as Rth0, respectively.
  • the thickness of the film was measured using a contact thickness meter (Code No. 543-390 manufactured by Mitutoyo Co., Ltd.).
  • the liquid crystal display device is a so-called O-mode device in which the pretilt angle of the liquid crystal cell is 1 ° and the absorption axis of the backlight side polarizing element is parallel to the slow axis of the liquid crystal cell when no voltage is applied. Is.
  • the absorption axis of the viewing side polarizing element and the absorption axis of the backlight side polarizing element are orthogonal to each other.
  • the liquid crystal display device was disassembled, the film to be evaluated was inserted between the backlight side polarizing element and the liquid crystal cell, and the film was reassembled to obtain a liquid crystal display device for evaluation.
  • the liquid crystal display device includes, from the visual side, a visual viewing side polarizing element, a color filter, a liquid crystal cell, the film, a backlight side polarizing element, and a backlight in this order.
  • the color of the obtained liquid crystal display device was evaluated at a polar angle of 60 °.
  • the slow-phase axial directions of the liquid crystal cell provided in the liquid crystal display device in a state where no voltage is applied are set to azimuth angles of 0 ° and 180 °, and the azimuth angles are 45 °, 135 °, 225 °, and 315 °.
  • the color was evaluated. Good; the color is black. Defective; the color is red or blue.
  • 0.014 parts of the tetrachlorotungsten phenylimide (tetrahydrofuran) complex was dissolved in 0.70 parts of toluene to prepare a solution.
  • 0.061 part of a diethylaluminum ethoxide / n-hexane solution having a concentration of 19% was added and stirred for 10 minutes to prepare a catalytic solution.
  • This catalyst solution was added to a pressure resistant reactor to initiate a ring-opening polymerization reaction. Then, the reaction was carried out for 4 hours while maintaining 53 ° C. to obtain a solution of a ring-opening polymer of dicyclopentadiene.
  • the number average molecular weight (Mn) and weight average molecular weight (Mw) of the obtained ring-opening polymer of dicyclopentadiene are 8,750 and 28,100, respectively, and the molecular weight distribution (Mw / Mn) obtained from these. was 3.21.
  • the hydride 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 267 ° 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 was formed into a strand shape by hot melt extrusion molding, and then shredded with a strand cutter to obtain a pellet-shaped crystalline resin A. ..
  • the crystalline resin A produced in Production Example 1 is molded using a heat melt extrusion film molding machine equipped with a T-die to obtain an extruded film (thickness 38 ⁇ m) as a long film (a) having a width of about 400 mm. rice field.
  • the obtained extruded film was wound into a roll.
  • the evaluation results of the film (a) are as shown in the table below. Further, as a result of confirming the sign of the intrinsic birefringence value of the crystalline resin A using the film (a), the sign of the intrinsic birefringence value of the crystalline resin A was “positive”.
  • Step (3) Drying step
  • the film (a') was heated and dried in an oven at 100 ° C. for 2 minutes to obtain a long film (b).
  • the obtained film (b) was wound into a roll form.
  • the evaluation results of the film (b) are as shown in the table below.
  • the film (b) is supplied to a transverse stretching machine using the tenter method, and while adjusting the take-up tension and the tenter chain tension, the film (c) is fixed and uniaxially stretched 1.1 times in the lateral direction to form an optical film (c). ) was produced. Stretching was performed by preheating (4a): film (b) to 160 ° C, then; (4b): preheated film (b) at 160 ° C, and then; (4c): stretched film (b). ) Was kept tense at a temperature of 160 ° C.
  • Example 2 An optical film was obtained in the same manner as in Example 1 except that the following items were changed.
  • the thickness of the film (b) was 38 ⁇ m.
  • -In (1-2. Step (2)) the thickness of the toluene to be coated was changed to a thickness of 1.1 ⁇ m per one side (that is, a total thickness of 2.2 ⁇ m on both sides).
  • (1-4. Step (4)) was not performed on the film (b), and the obtained film (b) was evaluated as an optical film.
  • the temperature of all four preheating rolls was set to 100 ° C.
  • the temperatures of the two stretch rolls were all set to 160 ° C.
  • the temperatures of the two cooling rolls were all set to 60 ° C.
  • the rotation speeds of the two stretching rolls were adjusted, and the film (b) was stretched uniaxially at a magnification of 1.1 times.
  • Example 4 An optical film was obtained in the same manner as in Example 1 except that the following items were changed. -In (1-2. Step (2)), the thickness of the toluene to be coated was changed to a thickness of 30 ⁇ m per one side (that is, a total thickness of 60 ⁇ m on both sides). -In (1-4. Step (4)), instead of fixed uniaxial stretching using a transverse stretching machine, the film (b) was freely uniaxially stretched to obtain a film (c). The free uniaxial stretching was performed in the same operation as in Comparative Example 3.
  • Example 5 An optical film was obtained in the same manner as in Example 1 except that the following items were changed. -The film (b) was obtained by performing the following solvent dipping step on the film (a) without performing the steps (1-2. Step (2)) and (1-3. Step (3)). .. The film (a) was immersed in toluene by passing the film (a) through a bathtub filled with toluene. The time for the film (a) to pass through the bathtub (that is, the time for the film (a) to come into contact with toluene) was 5 seconds. The film (a) passed through the bathtub was passed through an oven at 80 ° C. to dry the film (a) immersed in toluene to obtain a film (b).
  • the optical film of Example 1 (film (c)) and the optical film of Example 2 (film (b)) have an absolute value of retardation of 15 nm or less in the thickness direction and an in-plane retardation Re of 10 nm or less.
  • R TMA is 0% or more and 7.5% or less.
  • the optical film of the example has a good evaluation of the viewing angle characteristic, and the number of wrinkles generated in the 105 ° C. heat resistance test is small.
  • the optical film of Comparative Example 1 having an RTMA of 7.5% or more has a large number of wrinkles generated in the 105 ° C. heat resistance test.
  • the optical films of Comparative Examples 2 to 5 in which the absolute value of the retardation in the thickness direction is larger than 15 nm or the in-plane retardation Re is larger than 10 nm have a poor evaluation of the viewing angle characteristics, and are inherent in the polarizing element. It can be seen that the optical characteristics are greatly changed.
  • optical films of Comparative Examples 1 and 2 obtained by the manufacturing method not including the step (2) and the step (3), and the comparative example obtained by the manufacturing method having a coating thickness larger than 10 ⁇ m in the step (2).
  • the optical films of 3 to 5 have poor viewing angle characteristics.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Polarising Elements (AREA)

Abstract

Film optique comprenant une résine qui contient un polymère ayant une propriété cristalline, la valeur absolue du retard Rth dans le sens de l'épaisseur étant inférieure ou égale à 15 nm, le retard dans le plan Re étant inférieur ou égal à 10 nm et le coefficient de dilatation thermique étant compris entre 0 % et 7,5 %.
PCT/JP2021/044567 2020-12-28 2021-12-03 Film optique et son procédé de fabrication WO2022145174A1 (fr)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007106794A (ja) * 2005-10-11 2007-04-26 Fujifilm Corp セルロースエステルフィルム、セルロースエステルフィルムの製造方法、光学補償フィルム、偏光板、および画像表示装置
JP2008265268A (ja) * 2007-03-22 2008-11-06 Fujifilm Corp 熱可塑性樹脂フィルムの製造方法及び液晶表示板用光学補償フィルム及び偏光板
JP2008307831A (ja) * 2007-06-15 2008-12-25 Fujifilm Corp 環状ポリオレフィン系樹脂フィルム及びその製造方法
WO2015030118A1 (fr) * 2013-08-30 2015-03-05 株式会社日本触媒 Résine (méth)acrylique
JP2015171819A (ja) * 2015-04-30 2015-10-01 日東電工株式会社 粘着剤層付光学フィルムの製造方法
JP2018018096A (ja) * 2013-03-08 2018-02-01 富士フイルム株式会社 光学フィルム、偏光板及び液晶表示装置
WO2018124137A1 (fr) * 2016-12-28 2018-07-05 日本ゼオン株式会社 Film optique et plque polarisante

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007106794A (ja) * 2005-10-11 2007-04-26 Fujifilm Corp セルロースエステルフィルム、セルロースエステルフィルムの製造方法、光学補償フィルム、偏光板、および画像表示装置
JP2008265268A (ja) * 2007-03-22 2008-11-06 Fujifilm Corp 熱可塑性樹脂フィルムの製造方法及び液晶表示板用光学補償フィルム及び偏光板
JP2008307831A (ja) * 2007-06-15 2008-12-25 Fujifilm Corp 環状ポリオレフィン系樹脂フィルム及びその製造方法
JP2018018096A (ja) * 2013-03-08 2018-02-01 富士フイルム株式会社 光学フィルム、偏光板及び液晶表示装置
WO2015030118A1 (fr) * 2013-08-30 2015-03-05 株式会社日本触媒 Résine (méth)acrylique
JP2015171819A (ja) * 2015-04-30 2015-10-01 日東電工株式会社 粘着剤層付光学フィルムの製造方法
WO2018124137A1 (fr) * 2016-12-28 2018-07-05 日本ゼオン株式会社 Film optique et plque polarisante

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