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WO2014087593A1 - Film retardateur, plaque polarisante circulaire et dispositif d'affichage d'image - Google Patents

Film retardateur, plaque polarisante circulaire et dispositif d'affichage d'image Download PDF

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Publication number
WO2014087593A1
WO2014087593A1 PCT/JP2013/006815 JP2013006815W WO2014087593A1 WO 2014087593 A1 WO2014087593 A1 WO 2014087593A1 JP 2013006815 W JP2013006815 W JP 2013006815W WO 2014087593 A1 WO2014087593 A1 WO 2014087593A1
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WIPO (PCT)
Prior art keywords
film
group
retardation film
cellulose acylate
resin
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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PCT/JP2013/006815
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English (en)
Japanese (ja)
Inventor
賢治 三島
幸仁 中澤
理英子 れん
範江 谷原
田代　耕二
翠 木暮
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Konica Minolta Inc
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Konica Minolta Inc
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Priority to JP2014550900A priority Critical patent/JPWO2014087593A1/ja
Publication of WO2014087593A1 publication Critical patent/WO2014087593A1/fr
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    • 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
    • B29C55/045—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique in a direction which is not parallel or transverse to the direction of feed, e.g. oblique
    • 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
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/80—Constructional details
    • H10K59/8791—Arrangements for improving contrast, e.g. preventing reflection of ambient light

Definitions

  • the present invention relates to a retardation film, a circularly polarizing plate, and an image display device.
  • An organic electroluminescence element is a light source for a flat illumination device, a light source for an optical fiber, a backlight for a liquid crystal display device, a liquid crystal projector device from the viewpoints of high luminous efficiency, low voltage drive, light weight, and low cost.
  • the use as a light source such as a backlight for a display and a light source of an organic EL display device (OLED) has been widely studied.
  • a light emitting layer is provided between electrodes, and when a voltage is applied between the electrodes, electrons are injected from the cathode into the light emitting layer, and holes from the anode are injected into the light emitting layer.
  • the light emitting layer emits light by the energy generated by the bonding.
  • the organic EL element has an anode made of indium tin oxide (ITO) because of its high electrical conductivity, relatively high work function, and high hole injection efficiency among transparent conductive materials. , Mainly used.
  • a metal electrode is usually used for the cathode.
  • Mg, Mg / Ag, Mg / In, Al, Li / Al, etc. are mainly used from the viewpoint of work function in consideration of electron injection efficiency.
  • These metal electrodes have a high light reflectivity, and in addition to the function as an electrode (cathode), they also have a function of reflecting the light emitted from the light emitting layer and increasing the amount of emitted light (light emission luminance).
  • the amount of light (emission luminance) can be increased.
  • the cathode of the organic EL element has a mirror surface with strong light reflectivity, external light reflection is likely to occur when light is not emitted. For this reason, in an apparatus using an organic EL element as a light source, for example, an organic EL display device (OLED) or the like, reflection of indoor lighting or the like occurs, it is difficult to express black in a bright place, and the contrast is lowered. There was a problem.
  • OLED organic EL display device
  • optical films having various functions are used in apparatuses using organic EL elements as light sources.
  • an optical film used in an apparatus using an organic EL element as a light source as described above, since the organic EL element is likely to reflect outside light in a state where it does not emit light, in order to prevent this reflection, polarized light is used.
  • the retardation film that can be used to form a circularly polarizing plate having antireflection properties by bonding to a child.
  • the retardation film for exhibiting such antireflection properties include a ⁇ / 4 retardation film whose retardation is about 1 ⁇ 4 of the measurement wavelength ⁇ .
  • the phase difference is 1 / wavelength of light over the entire visible light wavelength range. It is required to be about 4. Therefore, the phase difference imparted to the long wavelength light is larger than the phase difference imparted to the short wavelength light. It is required to do.
  • a ⁇ / 4 retardation film having an in-plane retardation value Ro (550) at a wavelength of 550 nm of approximately 120 to 160 nm is preferable.
  • the retardation film is required not only to have a phase difference of about 1 ⁇ 4 of the wavelength of light in the entire visible light wavelength range, but also to reduce the thickness of the film in order to satisfy the requirements for downsizing the apparatus. Yes.
  • An object of the present invention is to provide a retardation film having an in-plane retardation value Ro that can realize a ⁇ / 4 retardation film and having sufficiently high transparency. Moreover, it aims at providing the circularly-polarizing plate and image display apparatus provided with the said retardation film.
  • One aspect of the present invention is a long retardation film containing a cellulose acylate resin, wherein the cellulose acylate resin satisfies the following formulas (1) and (2): A resin and a second cellulose acylate resin satisfying the following formula (3) and the following formula (4), and the resin constituting the retardation film has a weight average molecular weight of 190,000 to 300,000 And the value obtained by dividing the weight average molecular weight by the number average molecular weight is 2.4 to 3.3, and is the weight average molecular weight of the first cellulose acylate resin and the second cellulose acylate resin.
  • the absolute value of the difference is 50,000 or more and 120,000 or less, and the angle formed by the in-plane slow axis of the retardation film and the width direction of the retardation film is 40 to 50 °.
  • a retardation film according to symptoms is 50,000 or more and 120,000 or less, and the angle formed by the in-plane slow axis of the retardation film and the width direction of the retard
  • X represents the degree of substitution of acetyl groups of the cellulose acylate resin
  • Y represents the degree of substitution of acyl groups other than acetyl groups of the cellulose acylate resin.
  • Another aspect of the present invention is a circularly polarizing plate provided with the retardation film.
  • Another aspect of the present invention is an image display device including the retardation film.
  • FIG. 1 is a schematic diagram for explaining the shrinkage ratio in oblique stretching.
  • FIG. 2 is a schematic view showing an example of a rail pattern of an oblique stretching machine that can be applied to manufacture of a retardation film according to an embodiment of the present invention.
  • FIG. 3 is a schematic diagram illustrating a method for producing a retardation film according to an embodiment of the present invention (an example in which the film is drawn from a long film original fabric roll and then obliquely stretched).
  • FIG. 4 is a schematic view showing a method for producing a retardation film according to an embodiment of the present invention (an example in which a long film original is continuously stretched obliquely without being wound up).
  • FIG. 5 is a schematic diagram showing an example of the configuration of the organic EL display device according to the embodiment of the present invention.
  • the present invention has been made in view of such circumstances, and even in a sufficiently thin cellulose acylate film, the in-plane retardation value Ro is a value that can realize a ⁇ / 4 retardation film,
  • An object is to provide a retardation film having sufficiently high transparency. Moreover, it aims at providing the circularly-polarizing plate and image display apparatus provided with the said retardation film.
  • the retardation film according to the embodiment of the present invention is a long retardation film containing a cellulose acylate resin.
  • the cellulose acylate resin satisfies the above formula (1) and the above formula (2), and the second cellulose acylate satisfies the above formula (3) and the above formula (4).
  • the resin constituting the retardation film has a weight average molecular weight of 190,000 to 300,000, and a value obtained by dividing the weight average molecular weight by the number average molecular weight is 2.4 to 3.3. is there.
  • the difference in weight average molecular weight between the first cellulose acylate resin and the second cellulose acylate resin is 50,000 or more and 120,000 or less.
  • the retardation film has an angle between the in-plane slow axis and the width direction of the retardation film of 40 to 50 °.
  • the in-plane retardation value Ro is a value that can realize a ⁇ / 4 retardation film, for example, an in-plane retardation value at a wavelength of 550 nm.
  • Ro (550) is about 120 to 160 nm.
  • such a retardation film has sufficiently high transparency. Therefore, even if the cellulose acylate film is sufficiently thin, a ⁇ / 4 retardation film having a retardation of about 1 ⁇ 4 of the wavelength with respect to light in a wide range of visible light wavelengths can be obtained.
  • “retardation film” refers to a film having a function of converting linearly polarized light having a specific wavelength into circularly polarized light or converting circularly polarized light into linearly polarized light.
  • a “retardation film” refers to a film having an in-plane retardation of the film of about 1 ⁇ 4 with respect to a predetermined wavelength of light (usually in the visible light region).
  • the ⁇ / 4 retardation film obtains almost perfect circularly polarized light in the visible light wavelength range, so that the broadband ⁇ / 4 phase difference has a phase difference of approximately 1 ⁇ 4 of the wavelength in the visible light wavelength range.
  • a film is preferred.
  • “a phase difference of approximately 1 ⁇ 4 in the wavelength range of visible light” means that in a wavelength range of 400 to 700 nm, a longer wavelength has a reverse wavelength dispersion characteristic that has a larger phase difference value.
  • the optical film such as a retardation film preferably has a smaller variation in resin component, molecular weight, etc. in order to make the properties uniform.
  • the in-plane retardation value Ro is preferably a value that can realize a ⁇ / 4 retardation film, for example, the in-plane retardation value Ro (550) at a wavelength of 550 nm is preferably about 120 to 160 nm.
  • the cellulose acylate resin includes the first cellulose ester resin and the second cellulose ester resin, and the weight average of the resin constituting the retardation film.
  • the value obtained by dividing the molecular weight or the weight average molecular weight by the number average molecular weight is in the above range, it is considered that an in-plane retardation value Ro suitable for obtaining a ⁇ / 4 retardation film can be realized. Details will be described later.
  • the cellulose acylate resin includes the first cellulose acylate resin that satisfies the above formula (1) and the above formula (2), and the first cellulose acylate resin that satisfies the above formula (3) and the above formula (4). 2 cellulose acylate resins. Further, the cellulose acylate resin may contain other resins as long as these two kinds of cellulose acylate resins are contained.
  • the resin which combined 1st cellulose acylate resin and 2nd cellulose acylate resin satisfy
  • X represents the substitution degree of the acetyl group of the cellulose acylate resin as in the above formulas (1) to (4).
  • the resin constituting the retardation film has a weight average molecular weight of 190,000 to 300,000, preferably 200,000 to 280,000, and 210,000 to 270,000. Is more preferable. If the weight average molecular weight is within such a range, the in-plane retardation value Ro can be made suitable and the breakage can be suppressed by adjusting the following dispersibility value. Therefore, a ⁇ / 4 retardation film is obtained that is sufficiently thin and has a phase difference of about 1 ⁇ 4 of the wavelength for light in a wide range of visible light wavelengths.
  • the resin constituting the retardation film has a value obtained by dividing the weight average molecular weight by the number average molecular weight of 2.4 to 3.3, and preferably 2.4 to 2.9. More preferably, it is 5 to 2.7.
  • the value obtained by dividing the weight average molecular weight by the number average molecular weight indicates dispersibility, which is the spread of the molecular weight distribution of the resin, and the smaller the value, the narrower the molecular weight distribution. For example, if this value is 1, it is monodispersed and has a single molecular weight. If the value indicating such dispersibility is within the above range, the in-plane retardation value Ro can be made suitable, and breakage can be suppressed.
  • the dispersibility value is as described above, a resin having a relatively low molecular weight and a resin having a relatively high molecular weight are mixed.
  • a resin having a relatively low molecular weight can suppress breakage that may occur due to stretching or the like, but has a tendency to hardly exhibit a phase difference.
  • a resin having a relatively high molecular weight tends to exhibit a phase difference, but tends not to sufficiently suppress breakage that may occur due to stretching or the like. Therefore, the weight average molecular weight is within the above range, the first cellulose acylate resin and the second cellulose acylate resin satisfying the above relationship are included, and the value indicating dispersibility is as described above.
  • the in-plane retardation value Ro is a value that can realize a ⁇ / 4 retardation film, for example, the in-plane retardation value Ro (550) at a wavelength of 550 nm is 120.
  • a retardation film having a thickness of about 160 nm is obtained. That is, even if the cellulose acylate film is sufficiently thin, a ⁇ / 4 retardation film having a retardation of about 1 ⁇ 4 of the wavelength with respect to light in a wide range of visible light wavelengths can be obtained.
  • the retardation film has a weight average molecular weight difference ⁇ a between the first cellulose acylate resin and the second cellulose acylate resin of 50,000 to 120,000, and 70,000 to 120, 000 is preferable, and 90,000 to 115,000 is more preferable. If ⁇ a is within the above range, a resin having a relatively low molecular weight and a resin having a relatively high molecular weight are mixed. Accordingly, as described above, the in-plane retardation value Ro is a value that can realize a ⁇ / 4 retardation film, for example, the in-plane retardation value Ro (550) at a wavelength of 550 nm is about 120 to 160 nm. A retardation film is obtained.
  • the retardation film preferably has an angle ⁇ formed by the in-plane slow axis and the width direction thereof, that is, an orientation angle ⁇ of 40 ° or more and 50 ° or less, and 41 ° or more and 48 °. More preferably, it is 43 degrees or more and 47 degrees or less.
  • the orientation angle ⁇ is in the above range, the film is unwound from the roll body and has a retardation film having a slow axis in an oblique direction with respect to the longitudinal direction, and the transmission film unwound from the roll body and parallel to the longitudinal direction.
  • a circularly polarizing plate can be easily produced by laminating a polarizer film having an axis with a roll-to-roll so that the longitudinal directions thereof are overlapped with each other. Thereby, there is little cut loss of a film and it is advantageous on production.
  • the retardation film satisfies the above formula (1) and the above formula (2)
  • the second cellulose acylate resin satisfies the above formula (3) and the above formula (4).
  • the resin film is unwound from a raw film made of a roll of a long resin film containing a core member rolled into a core member, and the resin film is obtained by stretching the unwound resin film. Is preferred.
  • the retardation film is obtained by such off-line stretching, the dried resin film can be appropriately stretched. Therefore, the in-plane retardation value Ro is suitable as a value for realizing a ⁇ / 4 retardation film, and a retardation film having a small thickness can be obtained.
  • Such stretching is preferably oblique stretching. By doing so, a retardation film having an orientation angle ⁇ within the above range can be easily obtained.
  • the retardation film preferably has an in-plane retardation value Ro (550) at a wavelength of 550 nm of 120 to 160 nm, and preferably 130 to 150 nm.
  • Ro (550) is within the above range, ⁇ / 4 can be suitably realized.
  • the retardation film preferably has an in-plane retardation value at a wavelength of 550 nm of 130 to 150 nm and a thickness of the retardation film of 20 to 60 ⁇ m.
  • the retardation film according to the present embodiment the retardation film can be thinned, and an apparatus for applying it,
  • a retardation film capable of realizing ⁇ / 4 with the above-described thickness that can contribute to downsizing of the image display device can be obtained.
  • the thinner the retardation film the better, but it is considered that the limit is substantially about 20 ⁇ m. From this, the preferred range of the thickness of the retardation film is 20 to 60 ⁇ m.
  • the retardation film preferably has a thickness direction retardation value Rth (550) at a wavelength of 550 nm of 50 nm or more and 250 nm or less.
  • the retardation film has an in-plane retardation value Ro (450) at a wavelength of 450 nm, an in-plane retardation value Ro (550) at a wavelength of 550 nm, and an in-plane retardation value Ro (650) at a wavelength of 650 nm. It is preferable that the following formula (i) and the following formula (ii) are satisfied.
  • Ro (450) / Ro (550) is preferably 0.72 or more and 0.93 or less, and preferably 0.79 or more and 0.89 or less, as described above. More preferably, it is 0.81 or more and 0.87 or less. Further, Ro (550) / Ro (650) is preferably 0.83 or more and 0.97 or less, more preferably 0.84 or more and 0.93 or less, as described above, and 0.85. More preferably, it is 0.93 or less.
  • Ro ( ⁇ ) is the in-plane retardation value Ro at a wavelength ⁇ under the condition of 23 ° C. and 55% RH
  • Rth ( ⁇ ) is the wavelength ⁇ under the condition of 23 ° C. and 55% RH.
  • the thickness direction retardation value Rth is an in-plane retardation value Ro at a wavelength of 550 nm under the condition of 23 ° C. and 55% RH.
  • Ro and Rth in the optical film are defined by the following equations, respectively.
  • Formula 2: Rth ⁇ (nx + ny) / 2 ⁇ nz ⁇ ⁇ d (nm)
  • nx represents the refractive index in the slow axis direction x where the refractive index is maximum in the in-plane direction of the optical film
  • ny is the slow axis direction in the in-plane direction of the optical film.
  • the refractive index in the direction y orthogonal to x is represented
  • nz represents the refractive index in the thickness direction z of an optical film
  • d (nm) represents the thickness of an optical film.
  • Ro and Rth can be measured using an automatic birefringence meter.
  • the automatic birefringence system include AxoScan manufactured by Axometrics, KOBRA-21ADH manufactured by Oji Scientific Instruments, and the like. Specifically, it can be measured by the following method.
  • phase difference R ( ⁇ ) when light of 450 nm, 550 nm, or 650 nm is incident is measured.
  • the phase difference R ( ⁇ ) can be measured at 6 points every 10 ° within a range of ⁇ from 0 ° to 50 °.
  • the in-plane slow axis of the optical film can be confirmed with AxoScan manufactured by Axometrics.
  • nx, ny and nz are calculated by AxoScan manufactured by Axometrics. Then, based on the above formula, thickness direction retardations Rth (450), Rth (550) or Rth (650) at the measurement wavelengths of 450 nm, 550 nm or 650 nm are respectively calculated.
  • Ro (450) / Ro (550) can be calculated from the obtained Ro (450) and Ro (550). Then, Ro (550) / Ro (650) can be calculated from the obtained Ro (550) and Ro (650).
  • the resin constituting the retardation film may contain other resins as long as the first cellulose acylate resin and the second cellulose acylate resin satisfying the above relationship are included.
  • the other resin may be a cellulose acylate resin or a resin other than the cellulose acylate resin.
  • Cellulose acylate resin used in the present embodiment is not particularly limited as long as it satisfies the above-described relationship.
  • Cellulose acylate resin is a compound obtained by esterifying cellulose and carboxylic acid. That is, the cellulose acylate resin is a compound obtained by dehydrating and condensing a cellulose hydroxyl group and a carboxyl group of a carboxylic acid to form an acyl group.
  • the carboxylic acid is not particularly limited, and examples thereof include an aliphatic carboxylic acid having about 2 to 22 carbon atoms and an aromatic carboxylic acid having about 2 to 22 carbon atoms. Among these, lower fatty acids having 6 or less carbon atoms are preferable.
  • carboxylic acid may be used independently, you may use it in combination of 2 or more type.
  • the acyl group of the cellulose acylate resin is not particularly limited, and may be linear or branched. Moreover, the acyl group may have a cyclic structure and may have other substituents. When the total acyl substitution degree of the cellulose acylate resin is constant, the birefringence tends to decrease as the carbon number of the acyl group increases. Therefore, the carbon number of the acyl group is preferably 2 to 6, more preferably 2 to 4, and further preferably 2 to 3 from the viewpoint of transparency and the like.
  • acyl group examples include an acetyl group, a propionyl group, a butanoyl group, a heptanoyl group, a hexanoyl group, an octanoyl group, a decanoyl group, a dodecanoyl group, a tridecanoyl group, a tetradecanoyl group, a hexadecanoyl group, an octadecanoyl group, and an octadecanoyl group.
  • Examples include decanoyl group, isobutanoyl group, tert-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, and cinnamoyl group.
  • the cellulose acylate resin include mixed fatty acid esters such as cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, and cellulose acetate phthalate in addition to cellulose acetate such as triacetyl cellulose. Etc. Among these, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and the like are preferable.
  • the butyryl group that can be contained in the cellulose acylate resin may be linear or branched.
  • substitution degree of the acyl group of the cellulose acylate resin satisfies the above relationship.
  • the substitution degree of the acyl group of the cellulose acylate resin can be measured by a method prescribed in ASTM-D817-96.
  • the number average molecular weight (Mn) of the cellulose acylate resin is preferably in the range of 6 ⁇ 10 4 to 3 ⁇ 10 5 from the viewpoint of increasing the mechanical strength of the obtained film, and preferably 7 ⁇ 10 4 to A range of 2 ⁇ 10 5 is more preferable.
  • the molecular weight of the cellulose acylate resin such as weight average molecular weight (Mw) and number average molecular weight (Mn) is measured using gel permeation chromatography (GPC).
  • Mw weight average molecular weight
  • Mn number average molecular weight
  • the content of residual sulfuric acid in the cellulose acylate resin is preferably in the range of 0.1 to 45 ppm by mass in terms of elemental sulfur, and more preferably in the range of 1 to 30 ppm by mass. Sulfuric acid is considered to remain in the film in a salt state. If the content of residual sulfuric acid exceeds 45 ppm by mass, the film tends to break when it is hot-stretched or when it is cut (slit) after heat-stretching.
  • the content of residual sulfuric acid can be measured by the method prescribed in ASTM D817-96.
  • the content of the free acid in the cellulose acylate resin is preferably 1 to 500 ppm by mass, more preferably 1 to 100 ppm by mass, and further preferably 1 to 70 ppm by mass.
  • the content of free acid can be measured by the method prescribed in ASTM D817-96.
  • the cellulose acylate resin may contain a trace amount of metal components. It is considered that the trace amount of the metal component is derived from water used in the cellulose acylate resin synthesis process. Like these metal components, the content of components that can become insoluble nuclei is preferably as small as possible.
  • metal ions such as iron, calcium, and magnesium may form a salt with a resin decomposition product or the like that may contain an organic acidic group to form an insoluble material.
  • the calcium (Ca) component easily forms a coordination compound (that is, a complex) with an acidic component such as a carboxylic acid or a sulfonic acid, and many ligands. Insoluble starch, turbidity) may be formed.
  • the content of the iron (Fe) component in the cellulose acylate resin is preferably 1 mass ppm or less.
  • the content of the calcium (Ca) component in the cellulose acylate resin is preferably 60 ppm by mass or less, more preferably 0 to 30 ppm by mass.
  • the content of the magnesium (Mg) component in the cellulose acylate resin is preferably 0 to 70 ppm by mass, and particularly preferably 0 to 20 ppm by mass.
  • the content of metal components such as iron (Fe) component, calcium (Ca) component, and magnesium (Mg) component is the same as that obtained by subjecting an absolutely dry cellulose acylate resin to microdigest wet decomposition equipment (sulfuric acid decomposition) and alkali melting. After the treatment, it can be measured using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer).
  • the contents of residual alkaline earth metal, residual sulfuric acid and residual acid can be adjusted by thoroughly washing the cellulose acylate resin obtained by synthesis.
  • the method for producing the cellulose acylate resin is not particularly limited as long as the cellulose acylate resin can be produced, and a known production method may be mentioned. Specifically, if an example is given, it can be synthesized with reference to the method described in JP-A-10-45804.
  • the cellulose as a raw material of the cellulose acylate resin is not particularly limited, and may be cotton linter, wood pulp, kenaf, and the like.
  • a cellulose acylate resin produced from a single raw material may be used, or two or more cellulose acylate resins of different raw materials may be used in combination.
  • the retardation film may contain a resin other than the cellulose acylate resin.
  • a thermoplastic resin may be contained.
  • thermoplastic resin refers to a resin that has the characteristics that it softens when heated to the glass transition temperature or melting point and can be molded into the desired shape.
  • thermoplastic resin examples include polyethylene (PE), high density polyethylene, medium density polyethylene, low density polyethylene, polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene (PS), polyvinyl acetate ( PVAc), polytetrafluoroethylene (PTFE), acrylonitrile butadiene styrene resin (ABS resin), AS resin, acrylic resin (PMMA), and the like can be used.
  • PE polyethylene
  • PVC polyvinyl chloride
  • PS polyvinylidene chloride
  • PS polystyrene
  • PVAc polyvinyl acetate
  • PTFE polytetrafluoroethylene
  • ABS resin acrylonitrile butadiene styrene resin
  • AS resin acrylic resin
  • PMMA acrylic resin
  • PBT polyethylene terephthalate
  • GF-PET glass fiber reinforced polyethylene terephthalate
  • COP cyclic polyolefin
  • PPS polyphenylene sulfide
  • PTFE polytetrafluoroethylene
  • PI thermoplastic polyimide
  • PAI polyamideimide
  • the retardation film preferably contains a compound represented by the following general formula (A) as an optical performance modifier.
  • L 1 and L 2 are each independently a single bond or a divalent linking group
  • R 1 , R 2 and R 3 each independently represent a substituent
  • n is from 0 to 2
  • Wa and Wb each represent a hydrogen atom or a substituent
  • Wa and Wb may be bonded to each other to form a ring.
  • At least one of Wa and Wb has a ring structure.
  • at least one of Wa and Wb may be an alkenyl group or an alkynyl group.
  • L 1 and L 2 are preferably O, COO, and OCO.
  • R 1 , R 2 and R 3 include halogen atoms (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkyl groups (methyl group, ethyl group, n-propyl group, isopropyl group, tert- Butyl group, n-octyl group, 2-ethylhexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc.), alkenyl group (vinyl group, allyl group, etc.), cycloalkenyl group ( 2-cyclopenten-1-yl, 2-cyclohexen-1-yl group, etc.), alkynyl group (ethynyl group, propargyl group etc.), aryl group (phenyl group, p-tolyl group, naphthyl group etc.),
  • Fo group acyl group (acetyl group, pivaloylbenzoyl group, etc.), carbamoyl group (carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-octylcarbamoyl group, N -(Methylsulfonyl) carbamoyl group and the like.
  • R 1 and R 2 are preferably a substituted or unsubstituted benzene ring or a substituted or unsubstituted cyclohexane ring, more preferably a substituted benzene ring or a substituted cyclohexane ring, and a 4-position substituent.
  • a benzene ring is particularly preferred from the viewpoint that the main chain of the compound of the general formula (A) can be oriented in the slow axis direction of the ⁇ / 4 retardation film to increase the slow axis direction refractive index nx.
  • Wa and Wb include a halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkyl group (eg, methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n -Octyl group, 2-ethylhexyl group, etc.), cycloalkyl group (for example, cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, etc.), cycloalkenyl group ( For example, 2-cyclopenten-1-yl, 2-cyclohexen-1-yl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.), aryl group (eg, phenyl
  • the above substituent may be further substituted with the above substituent.
  • R 4 , R 5 and R 6 each represent a hydrogen atom or a substituent, and examples of the substituent include the same groups as the specific examples of the substituent represented by R 1 , R 2 and R 3 above. be able to.
  • each of A 1 and A 2 independently represents O, S, NR X (R X represents a hydrogen atom or a substituent) or CO.
  • R X represents a hydrogen atom or a substituent
  • Examples of the substituent represented by R X has the same meaning as specific examples of substituents represented by the Wa and Wb.
  • X is a substituent containing a nonmetallic atom of Group 14 to 16 after the third period, or a nonmetallic atom of Group 14 to 16 or a conjugated system after the third period.
  • X is preferably O, S, NRc, or C (Rd) Re.
  • Rc, Rd, and Re represent substituents, and are synonymous with specific examples of the substituents represented by Wa and Wb, for example.
  • L 1, L 2, R 1 , R 2, R 3, n is L 1, L 2, R 1 , same meanings as R 2, R 3, n in the general formula (A).
  • the synthesis of the compound represented by the general formula (A) is not particularly limited as long as the above compound can be synthesized, and can be performed by applying a known synthesis method.
  • a known synthesis method refer to the methods described in Journal of Chemical Crystallography ((1997); 27 (9); 512-526), JP 2010-31223 A, and JP 2008-107767 A, for example. And can be synthesized.
  • the retardation film according to this embodiment can contain various additives in addition to the resin component and the optical performance modifier.
  • a solvent can be used to prepare a cellulose acylate solution or dope by dissolving a cellulose acylate resin.
  • the solvent include a solvent that can dissolve the cellulose acylate resin.
  • organic solvents such as chlorinated organic solvents and non-chlorinated organic solvents.
  • chlorinated organic solvent examples include methylene chloride (methylene chloride).
  • Non-chlorine organic solvents include, for example, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoro Ethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, Examples include 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. From the viewpoint of recent environmental problems, non-chlorine organic solvents are preferably used.
  • the insoluble matter is reduced by a known dissolution method such as a dissolution method at normal temperature, a high-temperature dissolution method, a cooling dissolution method, and a high-pressure dissolution method. It is preferable.
  • a known dissolution method such as a dissolution method at normal temperature, a high-temperature dissolution method, a cooling dissolution method, and a high-pressure dissolution method. It is preferable.
  • methylene chloride can be used, but methyl acetate, ethyl acetate, and acetone are preferably used, and among them, methyl acetate is particularly preferable.
  • an organic solvent having good solubility in the cellulose acylate resin is referred to as a good solvent, and has a main effect on dissolution, and an organic solvent used in a large amount among them is mainly (organic). Solvent or main (organic) solvent.
  • the dope used for forming the retardation film according to this embodiment preferably contains an alcohol having 1 to 4 carbon atoms in the range of 1 to 40% by mass in addition to the organic solvent.
  • These alcohols after casting the dope on a metal support, start to evaporate the organic solvent, and when the relative proportion of the alcohol component increases, the dope film (web) gels, making the web strong and supporting the metal It can act as a gelling solvent that facilitates peeling from the body, and when the proportion of these alcohols is low, it also has a role of promoting dissolution of the cellulose acylate resin of a non-chlorine organic solvent.
  • Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, it is preferable to use ethanol from the viewpoints of excellent dope stability, relatively low boiling point, and good drying properties. These alcohols are categorized as poor solvents because they are not soluble in cellulose acylate resin alone.
  • the cellulose acylate concentration in the dope is preferably in the range of 15 to 30% by mass, and the dope viscosity is preferably adjusted in the range of 100 to 500 Pa ⁇ s from the viewpoint of obtaining excellent film surface quality. .
  • additives examples include plasticizers, ultraviolet absorbers, antioxidants, deterioration inhibitors, peeling aids, surfactants, dyes, and fine particles.
  • additives other than the fine particles may be added when preparing the cellulose acylate solution, or may be added when preparing the fine particle dispersion. It is preferable to add a plasticizer, an antioxidant, an ultraviolet absorber, or the like that imparts heat and moisture resistance to the polarizing plate used in the image display device.
  • plasticizers can be used in combination as additives for the purpose of improving the fluidity and flexibility of the composition.
  • plasticizers include phthalate plasticizers, fatty acid ester plasticizers, trimellitic ester plasticizers, phosphate ester plasticizers, polyester plasticizers, sugar ester plasticizers, and epoxy plasticizers.
  • polyhydric alcohol ester plasticizers It can be applied to a wide range of uses by selecting or using these plasticizers according to the use.
  • the additive is not particularly limited, but for example, an aromatic terminal ester compound and a compound having a triazine ring are preferable.
  • the aromatic terminal ester compound may be either an oligoester type or a polyester type, and the molecular weight is preferably in the range of 100 to 10,000, more preferably in the range of 350 to 3000.
  • An acid value of 1.5 mgKOH / g or less and a hydroxyl value of 25 mgKOH / g or less can be used, more preferably an acid value of 0.5 mgKOH / g or less and a hydroxyl value of 15 mgKOH / g or less. can do.
  • the polyhydric alcohol ester preferably used in the present embodiment is an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.
  • the polyhydric alcohol used in the present embodiment is represented by the following general formula (a).
  • R 1 represents an n-valent organic group, and n represents an integer of 2 or more.
  • the OH group represents an alcoholic or phenolic hydroxy group (hydroxyl group).
  • polyhydric alcohols examples include, for example, adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol Galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. Of these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol
  • the monocarboxylic acid used in the polyhydric alcohol ester is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, and the like can be used.
  • alicyclic monocarboxylic acid or aromatic monocarboxylic acid for the retardation film according to the present embodiment, moisture permeability and retention can be improved.
  • Preferred examples of the monocarboxylic acid include the following, but are not limited to these in the present embodiment.
  • aliphatic monocarboxylic acid a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used.
  • the number of carbon atoms is more preferably 1-20, and even more preferably 1-10.
  • compatibility with cellulose acylate can be improved by using acetic acid, it is preferable to use a mixture of acetic acid and another monocarboxylic acid.
  • Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, Examples thereof include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.
  • Preferred examples of the alicyclic monocarboxylic acid include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
  • Preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and aromatics having two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid.
  • the molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably in the range of 300 to 1500, and more preferably in the range of 350 to 750. It is preferable that the molecular weight is large to some extent because volatilization is difficult. From the viewpoint of moisture permeability and compatibility with the cellulose acylate resin, a certain small amount is preferable. From these points, the molecular weight is preferably within the above range.
  • the carboxylic acid used in the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.
  • polyhydric alcohol esters Specific compounds of polyhydric alcohol esters are shown below, but polyhydric alcohol esters that can be used in the present embodiment are not limited to these.
  • the compound having a triazine ring is preferably a discotic compound from the viewpoint of developing retardation in a ⁇ / 4 retardation film and reducing water content, and has a molecular weight of 300 to 2,000. It is preferable that In the present embodiment, the boiling point of the discotic compound is preferably 260 ° C. or higher. The boiling point can be measured using a commercially available measuring device (for example, TG / DTA100, manufactured by Seiko Electronics Industry Co., Ltd.).
  • the protective film used in the retardation film according to the present embodiment or the circularly polarizing plate described later preferably contains an ultraviolet absorber.
  • UV absorbers examples include benzotriazole UV absorbers, 2-hydroxybenzophenone UV absorbers, and salicylic acid phenyl ester UV absorbers.
  • an ultraviolet absorber having a molecular weight of 400 or more is less likely to volatilize at a high boiling point and is difficult to disperse even during high temperature molding, and therefore weather resistance can be effectively improved with a relatively small amount of addition.
  • Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis ( ⁇ , ⁇ -dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- ( Benzotriazoles such as 1,1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, Hindered amines such as bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl Bis (1,2,2,6,6-pentamethyl-4-piperidyl) malonate, 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl Oxy] ethyl] -4- [3- (3,5
  • 2- [2-hydroxy-3,5-bis ( ⁇ , ⁇ -dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3-tetrabutyl) ) -6- (2H-benzotriazol-2-yl) phenol] is preferred.
  • Commercially available products may be used, and for example, TINUVIN such as TINUVIN 109, TINUVIN 171, TINUVIN 234, TINUVIN 326, TINUVIN 327, TINUVIN 328, and TINUVIN 928 manufactured by BASF Japan Ltd. can be preferably used.
  • antioxidants can be added to the ⁇ / 4 retardation film in order to improve the thermal decomposability and thermal colorability during molding.
  • an antistatic agent can be added to impart antistatic performance to the ⁇ / 4 retardation film.
  • a flame retardant acrylic resin composition containing a phosphorus flame retardant may be used.
  • Phosphorus flame retardants include red phosphorus, triaryl phosphate ester, diaryl phosphate ester, monoaryl phosphate ester, aryl phosphonate compound, aryl phosphine oxide compound, condensed aryl phosphate ester, halogenated alkyl phosphate ester, Examples thereof include one or a mixture of two or more selected from halogen-condensed phosphoric acid esters, halogen-containing condensed phosphonic acid esters, halogen-containing phosphorous acid esters, and the like.
  • triphenyl phosphate 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris ( ⁇ -chloroethyl) phosphate, tris (dichloropropyl) Examples thereof include phosphate and tris (tribromoneopentyl) phosphate.
  • the retardation film according to the present embodiment has, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, and hydrated calcium silicate in order to improve handling properties. It is preferable to contain a matting agent such as inorganic fine particles such as aluminum silicate, magnesium silicate and calcium phosphate and a crosslinked polymer. Among these, silicon dioxide is preferably used because it can reduce the haze of the film.
  • the average primary particle diameter of the fine particles is preferably 20 nm or less, more preferably 5 to 16 nm, and further preferably 5 to 12 nm.
  • a film having a width in the range of 1 to 4 m can be used. Those having a width of 1.4 to 4 m are preferably used, and those having a width of 1.6 to 3 m are preferably used. If the width is 4 m or less, the conveyance stability can be ensured.
  • the arithmetic average roughness of the retardation film surface according to the present embodiment is about 2 to 4 nm, preferably 2.5 to 3.5 nm.
  • the dimensional change rate is preferably less than 0.5%, and more preferably less than 0.3%.
  • the defects having a diameter of 5 ⁇ m or more in the film surface are preferably 1 piece / 10 cm square or less, more preferably 0.5 pieces / 10 cm square or less, and 0.1 pieces / 10 cm square or less. More preferably.
  • the “defect” refers to a void in the film (foaming defect) generated due to rapid evaporation of the solvent in the drying step in film formation by the solution casting method described later, film formation This refers to foreign matter (foreign matter defect) in the film due to foreign matter in the stock solution or foreign matter mixed during film formation.
  • the diameter of the defect indicates the diameter when the defect is circular, and when the defect is not circular, the range of the defect is determined by observing with a microscope according to the following method, and the maximum diameter (diameter of circumscribed circle) is determined. .
  • the defect range is measured by the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope.
  • the defect is accompanied by a change in the surface shape such as transfer of a roller flaw or an abrasion
  • the size is confirmed by observing the defect with reflected light of a differential interference microscope.
  • aluminum or platinum is deposited on the surface for observation.
  • the film may be broken starting from the defects and productivity may be reduced.
  • the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.
  • the retardation film according to this embodiment has a breaking elongation of 10% or more in at least one direction (the width direction (TD direction) or the conveyance direction (MD direction)) in the measurement based on JIS-K7127-1999. It is preferable that it is 20% or more.
  • the upper limit of the elongation at break is not particularly limited, and is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.
  • the retardation film according to this embodiment preferably has a total light transmittance of 90% or more, and more preferably 93% or more.
  • the upper limit of the total light transmittance is not particularly limited, and is practically about 99%.
  • it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.
  • reduce the surface roughness of the film surface by reducing the surface roughness of the film contact area (cooling roller, calender roller, drum, belt, coating substrate in solution casting, transport roller, etc.) during film formation. It is effective to reduce the diffusion and reflection of light on the film surface.
  • the retardation film according to this embodiment can be formed according to a known method. Hereinafter, typical solution casting methods and melt casting methods will be described.
  • the retardation film according to this embodiment can be produced by a solution casting method.
  • a step of preparing a dope by heating and dissolving cellulose acylate resin and additives in an organic solvent a step of casting the prepared dope on a belt-shaped or drum-shaped metal support, casting A step of drying the dope as a web, a step of peeling from the metal support, a step of stretching or shrinking the peeled web, a step of drying, a step of winding up the finished film, and the like.
  • the cellulose acylate resin in the dope preferably has a higher concentration because the drying load after casting on the metal support can be reduced, but if the concentration of the cellulose acylate resin is too high, The load increases and the filtration accuracy deteriorates.
  • the concentration at which these are compatible is preferably in the range of 10 to 35% by mass, more preferably in the range of 15 to 25% by mass.
  • the metal support used preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used.
  • the cast width is preferably in the range of 1 to 4 m.
  • the surface temperature of the metal support in the casting step is appropriately selected and set within a range of ⁇ 50 ° C. to a temperature at which the solvent boils and does not foam. A higher temperature is preferable because the web can be dried faster, but if it is too high, the web may foam and flatness may deteriorate.
  • a preferable support temperature is appropriately determined within the range of 0 to 100 ° C. A temperature range of 5 to 30 ° C. is more preferred.
  • the web can be gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.
  • the method for controlling the temperature of the metal support is not particularly limited, but there are a method of blowing warm air or cold air, and a method of bringing hot water into contact with the back side of the metal support.
  • the method using hot water is preferable because the heat transfer is performed efficiently, and the time until the temperature of the metal support becomes constant is short.
  • warm air considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there is a case where wind at a temperature higher than the target temperature is used while preventing foaming. is there.
  • the amount of residual solvent when peeling the web from the metal support is preferably set within the range of 10 to 150% by mass, more preferably 20%. It is in the range of ⁇ 40 mass% or 60 to 130 mass%, more preferably in the range of 20 to 30 mass% or 70 to 120 mass%.
  • the residual solvent amount is defined by the following formula.
  • Residual solvent amount (% by mass) ⁇ (MN) / N ⁇ ⁇ 100 (Wherein, M is the mass of a sample taken at any time during or after production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.)
  • the web is peeled off from the metal support and further dried, so that the residual solvent amount is preferably 1.0% by mass or less, more preferably 0 to 0.01% by mass.
  • a roller drying method for example, a method in which webs are alternately passed through a number of upper and lower rollers and a method in which a web is dried while being conveyed by a tenter method is employed.
  • the ⁇ / 4 retardation film of the present embodiment preferably has an in-plane retardation Ro550 measured at a wavelength of 550 nm of 115 to 160 nm, and such retardation is imparted by stretching the film. obtain.
  • the stretching method is not particularly limited, for example, a method in which a circumferential speed difference is provided to a plurality of rollers, and a longitudinal stretching is performed using the roller circumferential speed difference therebetween, and both ends of the web are fixed with clips or pins.
  • a method of extending the distance between pins in the traveling direction and extending in the vertical direction, a method of expanding in the horizontal direction and extending in the horizontal direction, or a method of extending the vertical and horizontal directions simultaneously and extending in both the vertical and horizontal directions may be employed alone or in combination. it can. That is, the film may be stretched in the transverse direction, longitudinally, or in both directions with respect to the film forming direction, and when stretched in both directions, simultaneous stretching or sequential stretching may be used. May be. In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.
  • the film is usually stretched in the width direction (TD direction) and contracted in the transport direction (MD direction), but when contracted, it is easy to match the main chain direction when transported in an oblique direction. In addition, the phase difference effect is even greater.
  • the shrinkage rate can be determined by the transport angle.
  • FIG. 1 is a schematic diagram for explaining the shrinkage ratio in oblique stretching.
  • reference numeral 111 is a stretching direction (TD direction)
  • reference numeral 113 is a transport direction (MD direction)
  • reference numeral 114 indicates a slow axis.
  • the ⁇ / 4 retardation film according to the present embodiment has an orientation angle of 45 ° ⁇ 2 ° with respect to the transport direction. Bonding with can be performed, which is preferable.
  • the orientation angle of the film can be freely set, and the orientation axis of the film can be set to the left and right with high precision across the film width direction.
  • a film stretching apparatus that can be oriented and can control the film thickness and retardation with high accuracy is preferable.
  • FIG. 2 is a schematic view showing an example of a rail pattern of an oblique stretching apparatus applicable to the production of a ⁇ / 4 retardation film according to this embodiment.
  • the figure shown here is an example, Comprising: The extending
  • the feeding direction D1 of the long film original is different from the winding direction D2 of the stretched film after stretching, and forms a feeding angle ⁇ i. is doing.
  • the feeding angle ⁇ i can be arbitrarily set to a desired angle in the range of more than 0 ° and less than 90 °.
  • the term “long” refers to a film having a length of at least about 5 times the width of the film, preferably a film having a length of 10 times or more.
  • the long film original is gripped by the right and left grippers (tenters) at the entrance of the oblique stretching apparatus (position A in the figure), and travels as the grippers travel.
  • the left and right gripping tools are the left and right gripping tools Ci and Co at the entrance of the oblique stretching apparatus (position A in the figure) and facing the direction substantially perpendicular to the film traveling direction (feeding direction D1).
  • the film travels on the asymmetric rails Ri and Ro, and the film gripped by the tenter is released at the position at the end of stretching (position B in the figure).
  • the gripping tools Ci and Co that are opposed to the film feeding direction D1 at the oblique stretching apparatus entrance (the gripping start position by the film gripping tool) A are positions at the end of the film stretching.
  • the straight line connecting the grippers Ci and Co is inclined by an angle ⁇ L with respect to a direction substantially perpendicular to the film winding direction D2.
  • the original film is obliquely stretched so that the orientation angle is ⁇ L, and a retardation film is obtained.
  • substantially vertical indicates that the angle is in a range of 90 ⁇ 1 °.
  • This stretching device is a device that heats the film fabric to an arbitrary temperature at which stretching is possible and stretches it obliquely.
  • This stretching apparatus includes a heating zone, a pair of rails on the left and right on which a gripping tool for transporting the film travels, and a number of gripping tools that travel on the rails. Both ends of the film sequentially supplied to the inlet of the stretching apparatus are gripped by a gripping tool, the film is guided into the heating zone, and the film is released from the gripping tool at the outlet of the stretching apparatus. The film released from the gripping tool is wound around the core.
  • Each of the pair of rails has an endless continuous track, and the gripping tool which has released the grip of the film at the outlet portion of the stretching apparatus travels outside and is sequentially returned to the inlet portion.
  • the rail pattern of the stretching device has an asymmetric shape on the left and right, and the rail pattern can be adjusted manually or automatically depending on the orientation angle, stretch ratio, etc. given to the long stretched film to be manufactured. It has become.
  • the position of each rail portion and the rail connecting portion can be freely set, and the rail pattern can be arbitrarily changed (the ⁇ portion in FIG. 2 indicates an example of the connecting portion).
  • the gripping tool of the stretching apparatus travels at a constant speed with a constant distance from the front and rear gripping tools.
  • the traveling speed of the gripping tool can be selected as appropriate, but is usually 1 to 100 m / min.
  • the difference in travel speed between the pair of left and right grippers is usually 1% or less, preferably 0.5% or less, more preferably 0.1% or less of the travel speed. This is because if there is a difference in the traveling speed between the left and right sides of the film at the exit of the stretching process, wrinkles and shifts will occur at the exit of the stretching process, so the speed difference between the left and right gripping tools is required to be substantially the same speed. Because. In general stretching equipment, etc., there is a speed unevenness that occurs in the order of seconds or less depending on the period of the sprocket teeth driving the chain, the frequency of the drive motor, etc. This does not correspond to the speed difference described in the embodiment.
  • a large bending rate is often required for the rail that regulates the locus of the gripping tool, particularly in a portion where the film is transported obliquely.
  • the trajectory of the gripping tool draws a curve at the bent portion.
  • the long film original fabric is gripped by the right and left grippers sequentially at the entrance of the oblique stretching apparatus (position A in the figure), and travels as the grippers travel.
  • the left and right gripping tools facing the direction substantially perpendicular to the film traveling direction (feeding direction D1) at the entrance of the oblique stretching apparatus (position A in the figure) run on a rail that is asymmetrical to the preheating zone. Through a heating zone having a stretching zone and a heat setting zone.
  • the preheating zone refers to a section where the distance between the gripping tools gripping both ends is kept constant at the heating zone entrance.
  • the stretching zone refers to the interval until the gap between the gripping tools that grips both ends starts to reach a predetermined interval.
  • the oblique stretching as described above is performed, but the stretching may be performed in the longitudinal direction or the transverse direction before and after the oblique stretching as necessary.
  • there is contraction in the MD direction (fast axis direction) which is a direction perpendicular to the slow axis during bending.
  • an optical adjustment agent for example, the general formula (described above) that is deviated from the main chain of the cellulose acylate that is the matrix resin by performing a shrinkage treatment following the stretching treatment.
  • the orientation of the compound represented by A) is contracted in the direction perpendicular to the stretching direction (the fast axis direction) to rotate the orientation state of the optical adjusting agent, and the main axis of the optical adjusting agent is a matrix resin. It can be matched with the main chain of cellulose acylate.
  • the refractive index ny 280 in the fast axis direction in the ultraviolet region 280 nm can be increased, and the slope of the ny forward wavelength dispersion in the visible light region can be made steep.
  • the heat setting zone refers to the section in which the gripping tools at both ends run parallel to each other during the period when the spacing between the gripping tools after the stretching zone becomes constant again. You may pass through the area (cooling zone) by which the temperature in a zone is set to below the glass transition temperature Tg of the thermoplastic resin which comprises a film, after passing through a heat setting zone. At this time, in consideration of shrinkage of the film due to cooling, a rail pattern that narrows the gap between the opposing grippers in advance may be used.
  • the temperature of each zone is the glass transition temperature Tg of the thermoplastic resin
  • the temperature of the preheating zone is within the range of Tg to Tg + 30 ° C
  • the temperature of the stretching zone is within the range of Tg to Tg + 30 ° C
  • the temperature of the cooling zone is It is preferably set within the range of Tg-30 ° C. to Tg.
  • a temperature difference in the width direction may be applied in the stretching zone.
  • a method of adjusting the opening degree of the nozzle for sending warm air into the temperature-controlled room so as to make a difference in the width direction, or controlling the heating by arranging the heaters in the width direction is known. Can be used.
  • the lengths of the preheating zone, stretching zone, shrinkage zone and cooling zone can be appropriately selected.
  • the length of the preheating zone is usually in the range of 100 to 150% with respect to the length of the stretching zone, and the length of the fixed zone Is usually in the range of 50 to 100%.
  • the draw ratio (W / W0) in the drawing step is preferably in the range of 1.3 to 3.0, more preferably in the range of 1.5 to 2.8. When the draw ratio is within this range, the thickness unevenness in the width direction can be reduced. In the stretching zone of the oblique stretching apparatus, the thickness direction unevenness can be further improved by making a difference in the stretching temperature in the width direction.
  • W0 represents the width of the film before stretching
  • W represents the width of the film after stretching.
  • the oblique stretching method applicable in this embodiment includes the stretching methods shown in FIGS. 3 (a) to 3 (c) and FIGS. 4 (a) and 4 (b). Can be mentioned.
  • FIG. 3 is a schematic view showing a method for producing a retardation film according to an embodiment of the present invention (an example in which the film is drawn from a long film roll and then obliquely stretched), and is a length once wound into a roll shape. The pattern which draws out the original film and draws it diagonally is shown.
  • FIG. 4 is a schematic diagram illustrating a method for producing a retardation film according to an embodiment of the present invention (an example in which a long film original is continuously stretched obliquely without winding up). The pattern which performs a diagonal stretch process continuously, without winding up is shown.
  • reference numeral 15 is an oblique stretching apparatus
  • reference numeral 16 is a film feeding apparatus
  • reference numeral 17 is a conveying direction changing apparatus
  • reference numeral 18 is a winding apparatus
  • reference numeral 19 is a film forming apparatus. Yes.
  • reference numerals indicating the same components may be omitted.
  • the film feeding device 16 is slidable and swivelable or slidable so that the film can be sent out at a predetermined angle with respect to the oblique stretching device inlet. It is preferable to be able to send FIGS. 3A to 3C show patterns in which the arrangement of the film feeding device 16 and the conveyance direction changing device 17 is changed. FIGS. 4A and 4B show a pattern in which the film formed by the film forming apparatus 19 is directly fed to a stretching apparatus.
  • the width of the entire manufacturing apparatus can be further reduced, and the film feeding position and angle can be finely controlled.
  • by making the film feeding device 16 and the transport direction changing device 17 movable it is possible to effectively prevent the left and right clips from being caught in the film.
  • the winding device 18 is arranged so that the film can be pulled at a predetermined angle with respect to the outlet of the oblique stretching device, so that it is possible to finely control the film take-up position and angle, and there are variations in film thickness and optical value.
  • a small elongated stretched film can be obtained. Therefore, the generation of wrinkles in the film can be effectively prevented, and the winding property of the film is improved, so that the film can be wound up in a long length.
  • the take-up tension T (N / m) of the stretched film can be adjusted within a range of 100 N / m ⁇ T ⁇ 300 N / m, preferably 150 N / m ⁇ T ⁇ 250 N / m. preferable.
  • the above-mentioned ⁇ / 4 retardation film may be formed by a melt film forming method.
  • the melt film-forming method is a molding method in which a composition containing an additive such as a resin and a plasticizer is heated and melted to a temperature exhibiting fluidity, and then a melt containing a fluid thermoplastic resin is cast. .
  • the molding method for heating and melting can be classified into, for example, a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, and a stretch molding method.
  • the melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy.
  • the plurality of raw materials used in the melt extrusion method are usually preferably kneaded in advance and pelletized.
  • Pelletization can be performed by a known method, for example, dry cellulose acylate, plasticizer, and other additives are fed to an extruder with a feeder, and kneaded using a single or twin screw extruder, It can be obtained by extruding into a strand form from a die, cooling with water or air, and cutting.
  • the additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.
  • a small amount of additives such as fine particles and antioxidants are preferably mixed in advance in order to mix uniformly.
  • the extruder used for pelletization preferably has a method of processing at as low a temperature as possible so that pelletization is possible so that the shearing force is suppressed and the resin does not deteriorate (molecular weight reduction, coloring, gel formation, etc.).
  • a twin screw extruder it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.
  • Film formation is performed using the pellets obtained as described above.
  • the raw material powder can be put into a feeder as it is, supplied to an extruder, heated and melted, and then directly formed into a film without being pelletized.
  • the melting temperature is in the range of 200 to 300 ° C.
  • T A film is cast from the die, the film is nipped by a cooling roller and an elastic touch roller, and solidified on the cooling roller.
  • the extrusion flow rate is preferably carried out stably by introducing a gear pump.
  • a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances.
  • a stainless steel fiber sintered filter is a product in which a stainless steel fiber body is intricately intertwined and compressed, and the contact points are sintered and integrated. The density is changed according to the thickness of the fiber and the amount of compression, and filtration is performed. The accuracy can be adjusted.
  • Additives such as plasticizers and fine particles may be mixed with the resin in advance, or may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer.
  • the film temperature on the touch roller side when the film is nipped between the cooling roller and the elastic touch roller is preferably in the range of Tg to Tg + 110 ° C. of the film.
  • a known elastic touch roller can be used as the elastic touch roller having an elastic surface used for such a purpose.
  • the elastic touch roller is also called a pinching rotary body, and a commercially available one can also be used.
  • the film obtained as described above can be subjected to a stretching and shrinking treatment by a stretching operation after passing through a step of contacting a cooling roller.
  • a known roller stretching device or oblique stretching device as described above can be preferably used as a method of stretching and shrinking.
  • the stretching temperature is usually preferably in the temperature range of Tg to Tg + 60 ° C. of the resin constituting the film.
  • the end Before winding, the end may be slit and cut to the product width, and knurled (embossed) may be applied to both ends to prevent sticking or scratching during winding.
  • the knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing.
  • grip part of the clip of both ends of a film is cut out and reused.
  • the above-described ⁇ / 4 retardation film can be formed into a circularly polarizing plate by laminating so that the angle between the slow axis and the transmission axis of the polarizer described later is substantially 45 °.
  • substantially 45 ° means within a range of 40 to 50 °.
  • the angle between the in-plane slow axis of the ⁇ / 4 retardation film and the transmission axis of the polarizer is preferably in the range of 41 to 49 °, and in the range of 42 to 48 °. Is more preferably within a range of 43 to 47 °, and particularly preferably within a range of 44 to 46 °.
  • the circularly polarizing plate (long circular polarizing plate) according to this embodiment is a long roll having a long protective film, a long polarizer and a long ⁇ / 4 retardation film in this order. It is made by cutting. Since the elongate circularly polarizing plate according to the present embodiment is produced using the above-described ⁇ / 4 retardation film, it can be applied to a wide range of visible light wavelengths by applying it to an organic EL display device described later. An effect of shielding the specular reflection of the metal electrode of the EL element can be exhibited. As a result, reflection during observation can be prevented and black expression can be improved.
  • the long circularly polarizing plate has an ultraviolet absorbing function.
  • the protective film on the viewing side has an ultraviolet absorbing function from the viewpoint that both the polarizer and the organic EL element can exhibit a protective effect against ultraviolet rays.
  • the ⁇ / 4 retardation film on the light emitter side also has an ultraviolet absorbing function, when used in an organic EL display described later, deterioration of the organic EL element can be further suppressed.
  • the long circularly polarizing plate according to the present embodiment has the ⁇ / 4 phase difference adjusted so that the angle of the slow axis (that is, the orientation angle ⁇ ) is “substantially 45 °” with respect to the longitudinal direction.
  • the film By using a film, it is possible to form an adhesive layer and bond the polarizing film and the ⁇ / 4 retardation film plate with a consistent production line. Specifically, after finishing the step of producing the polarizing film by stretching, the step of bonding the polarizing film and the ⁇ / 4 retardation film can be incorporated during or after the subsequent drying step, Each can be continuously supplied, and can be connected in a production line that is consistent with the next process by winding in a roll state after bonding.
  • a protective film when bonding a polarizing film and (lambda) / 4 phase difference film, a protective film can also be simultaneously supplied in a roll state and can also be bonded continuously. From the viewpoint of performance and production efficiency, it is preferable to simultaneously bond a ⁇ / 4 retardation film and a protective film to the polarizing film. That is, after finishing the step of producing the polarizing film by stretching, after the subsequent drying step or after the drying step, the protective film and the ⁇ / 4 retardation film are bonded to both sides with an adhesive, It is also possible to obtain a rolled circularly polarizing plate.
  • the polarizer is preferably sandwiched between the ⁇ / 4 retardation film and the protective film, and a cured layer is preferably laminated on the viewing side of the protective film.
  • An image display device for example, an organic EL display device (organic EL image display device) is manufactured using the long circularly polarizing plate. More specifically, the organic EL display device according to this embodiment includes a long circular polarizing plate using the ⁇ / 4 retardation film and an organic EL element.
  • the screen size of the organic EL display is not particularly limited, and can be 20 inches or more.
  • FIG. 5 is a schematic explanatory diagram of the configuration of the organic EL display of the present embodiment.
  • the configuration of the organic EL display of the present embodiment is not limited to that shown in FIG.
  • the organic EL element B having 8 (can be omitted) the above-described long circularly polarizing plate C having the polarizer 10 sandwiched between the above-described ⁇ / 4 retardation film 9 and the protective film 11 is provided, and an organic EL display device A is configured.
  • the protective film 11 is preferably laminated with a cured layer 12.
  • the hardened layer 12 not only prevents scratches on the surface of the organic EL display device but also has an effect of preventing warpage due to the long circularly polarizing plate. Further, an antireflection layer 13 may be provided on the cured layer.
  • the thickness of the organic EL element itself is about 1 ⁇ m.
  • an organic EL display device a metal electrode, an organic light emitting layer, and a transparent electrode are sequentially laminated on a transparent substrate to form an element (organic EL element) that is a light emitter.
  • the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene,
  • a structure having various combinations such as a laminate of such a light emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light emitting layer, and electron injection layer is known. It has been.
  • holes and electrons are injected into an organic light emitting layer by applying a voltage to a transparent electrode and a metal electrode, and the energy generated by recombination of these holes and electrons excites the fluorescent material. It emits light on the principle that it emits light when the excited fluorescent material returns to the ground state.
  • the mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.
  • an organic EL display device in order to take out light emitted from the organic light emitting layer, at least one of the electrodes needs to be transparent, and is usually a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO). Is preferably used as the anode. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.
  • ITO indium tin oxide
  • the long circular polarizing plate having the above-mentioned ⁇ / 4 retardation film can be applied to an organic EL display having a large screen having a screen size of 20 inches or more, that is, a diagonal distance of 50.8 cm or more.
  • the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. Therefore, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate.
  • the display surface of the organic EL display device looks like a mirror surface.
  • an organic EL display device including an organic EL element having a transparent electrode on the surface side of an organic light emitting layer that emits light by applying a voltage and a metal electrode on the back side of the organic light emitting layer, the surface side of the transparent electrode (visible)
  • a polarizing plate can be provided on the side), and a retardation plate can be provided between the transparent electrode and the polarizing plate.
  • the retardation film and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action.
  • the retardation film is composed of a quarter retardation film and the angle formed by the polarization direction of the polarizing plate and the retardation film is adjusted to ⁇ / 4, the mirror surface of the metal electrode can be completely shielded. it can.
  • the external light incident on the organic EL display device is transmitted only by the linearly polarized light component by the polarizing plate, and this linearly polarized light is generally elliptically polarized light by the phase difference plate.
  • the retardation film has a ⁇ / 4 phase difference. When the angle between the polarization direction of the polarizing plate and the retardation film is ⁇ / 4, the film is circularly polarized.
  • This circularly polarized light is transmitted through the transparent substrate, transparent electrode, and organic thin film, reflected by the metal electrode, again transmitted through the organic thin film, transparent electrode, and transparent substrate, and becomes linearly polarized light again on the retardation film. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate
  • One aspect of the present invention is a long retardation film containing a cellulose acylate resin, wherein the cellulose acylate resin satisfies the following formulas (1) and (2): A resin and a second cellulose acylate resin satisfying the following formula (3) and the following formula (4), and the resin constituting the retardation film has a weight average molecular weight of 190,000 to 300,000 And the value obtained by dividing the weight average molecular weight by the number average molecular weight is 2.4 to 3.3, and is the weight average molecular weight of the first cellulose acylate resin and the second cellulose acylate resin.
  • the absolute value of the difference is 50,000 or more and 120,000 or less, and the angle formed by the in-plane slow axis of the retardation film and the width direction of the retardation film is 40 to 50 °.
  • a retardation film according to symptoms is 50,000 or more and 120,000 or less, and the angle formed by the in-plane slow axis of the retardation film and the width direction of the retard
  • X represents the degree of substitution of acetyl groups of the cellulose acylate resin
  • Y represents the degree of substitution of acyl groups other than acetyl groups of the cellulose acylate resin.
  • the in-plane retardation value Ro is a value that can realize a ⁇ / 4 retardation film, and the retardation is sufficiently high.
  • a film can be provided.
  • the retardation film satisfies the above formula (1) and the above formula (2)
  • the second cellulose acylate resin satisfies the above formula (3) and the above formula (4).
  • the resin film is unwound from a raw film made of a roll of a long resin film containing a core member rolled into a core member, and the resin film is obtained by stretching the unwound resin film. Is preferred.
  • the in-plane retardation value Ro is suitable as a value for realizing a ⁇ / 4 retardation film, and a thin retardation film can be obtained.
  • the stretching is preferably oblique stretching.
  • the in-plane retardation value Ro is suitable as a value for realizing a ⁇ / 4 retardation film, and a thin retardation film can be obtained.
  • an in-plane retardation value of the retardation film at a wavelength of 550 nm is 130 to 150 nm, and a thickness of the retardation film is 20 to 60 ⁇ m.
  • the in-plane retardation value Ro is suitable as a value for realizing a ⁇ / 4 retardation film, and a thin retardation film can be obtained.
  • Another aspect of the present invention is a circularly polarizing plate provided with the retardation film.
  • Another aspect of the present invention is an image display device including the retardation film.
  • cellulose acylate resin examples include triacetyl cellulose (TAC), cellulose acetate propionate (CAP), and diacetyl having the acyl group substitution degree and molecular weight (number average molecular weight Mn and weight average molecular weight Mw) shown in Table 1.
  • TAC triacetyl cellulose
  • CAP cellulose acetate propionate
  • DAC diacetyl having the acyl group substitution degree and molecular weight (number average molecular weight Mn and weight average molecular weight Mw) shown in Table 1.
  • DAC Cellulose
  • the peeled film is uniaxially stretched at a stretch ratio of 1% only in the width direction (TD direction) using a stretching apparatus while being heated at 180 ° C., and transport tension so as not to shrink in the transport direction (MD direction). Adjusted.
  • the residual solvent at the start of stretching was 15% by mass.
  • drying was terminated while the drying zone was conveyed through a number of rollers.
  • the drying temperature was 130 ° C. and the transport tension was 100 N / m.
  • a resin film original fabric in which a resin film having a dry film thickness of 33 ⁇ m was wound into a roll was produced.
  • the resin film is unwound from the resin film original, and the resin film is stretched at a stretching temperature of Tg + 20 ° C., a stretching ratio of 2.0 times, and a bending angle using an oblique stretching apparatus having the configuration shown in FIG. (Drawing angle) ⁇ i was 49 °, shrinkage (MD direction) was 25%, and the orientation angle was 45 °. That is, oblique stretching was performed offline. By doing so, a ⁇ / 4 retardation film was produced.
  • Example 2 and 4 Comparative Examples 1 to 6
  • a retardation film was produced in the same manner as in Example 1 except that the cellulose acylate resin used was changed to that shown in Table 2.
  • Example 3 As the stretching step, a retardation film is produced in the same manner as in Example 1 except that the stretching step is performed as it is without winding the resin film after film formation, instead of the above-described offline stretching. did. That is, a retardation film was produced in the same manner as in Example 1 except that oblique stretching was performed off-line. By doing so, a retardation film was produced.
  • Table 2 below shows the conditions for producing the retardation films according to the examples and comparative examples.
  • orientation angle (Orientation angle) The orientation angle (the angle formed by the in-plane slow axis and the width direction) was also measured using an Axoscan manufactured by Axometers. In addition, in the case where the film breaks at the time of stretching, measurement is impossible, and “ ⁇ ” is shown in Table 3 below.
  • the film thickness was measured using a photoelectric digital length measurement system (MH-15M, counter TC-101, MS-5C, manufactured by Nikon Corporation).
  • the measured film thickness was 20 ⁇ m or more and less than 60 ⁇ m, it was evaluated as “ ⁇ ”, when it was 60 ⁇ m or more and less than 70 ⁇ m, it was evaluated as “ ⁇ ”, and when it was 70 ⁇ m or more, it was evaluated as “X”. Further, in the case where the film breaks at the time of stretching, the evaluation is impossible, and “ ⁇ ” is shown in Table 3 below.
  • Display characteristics were evaluated using an organic EL display device using the retardation films prepared in Examples 1 to 4 and Comparative Examples 1 to 6 as described below.
  • each of the above retardation films was bonded to one side of the above polarizer using a fully saponified polyvinyl alcohol 5% aqueous solution as an adhesive. In that case, it bonded so that the transmission axis of a polarizer and the slow axis of retardation film might be set to 45 degrees.
  • a protective film to be described later was bonded to the other surface of the polarizer by alkali saponification treatment. By doing so, the elongate circularly-polarizing plate provided with each retardation film was produced, respectively.
  • ⁇ Preparation of protective film> 251 g of 1,2-propylene glycol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 2 L four-neck equipped with a thermometer, stirrer, and slow cooling tube The flask was charged and gradually heated with stirring until it reached 230 ° C. in a nitrogen stream. An ester compound was obtained by allowing dehydration condensation reaction for 15 hours, and distilling off unreacted 1,2-propylene glycol under reduced pressure at 200 ° C. after completion of the reaction. The acid value was 0.10 mg KOH / g, and the number average molecular weight was 450.
  • the fine particle dispersion was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. The obtained liquid was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. By doing so, the fine particle addition liquid was prepared.
  • the belt casting apparatus was used to uniformly cast on a stainless steel band support.
  • the solvent was evaporated until the residual solvent amount reached 100%, and the stainless steel band support was peeled off.
  • the peeled film web was evaporated at 35 ° C, the solvent was evaporated, slit to a width of 1.65m, and 30% in the TD direction (the width direction of the film) with a stretching device while applying heat at 160 ° C. Was stretched 1%.
  • the residual solvent amount when starting stretching was 20%. Then, after drying for 15 minutes while transporting the inside of a drying device at 120 ° C.
  • each organic EL display device After applying an adhesive to the surface of the retardation film of each circularly polarizing plate produced as described above, each organic EL display device was produced by bonding to the viewing side of the organic EL cell.
  • a black image is displayed on the organic EL display device and the screen (image display area) is viewed from the front under an environmental condition in which the fluorescent lamp is uniformly irradiated so that the illuminance at a position 5 cm higher than the outermost surface of the organic EL display device is 1000 Lx. saw. At that time, the following criteria were evaluated.
  • Table 3 shows the evaluation results.
  • the resin obtained by mixing the cellulose acylate resin No. 2 has a weight average molecular weight of 190,000 to 300,000, and a value obtained by dividing the weight average molecular weight by the number average molecular weight is 2.4 to 3.3.
  • the absolute value of the difference in weight average molecular weight between the first cellulose acylate resin and the second cellulose acylate resin is from 50,000 to 120,000, and the orientation angle is from 40 to 50 When it is ° (Examples 1 to 4), it is sufficiently thin as compared with Comparative Examples 1 to 6, and the in-plane retardation value Ro is a value that can realize a ⁇ / 4 retardation film, Highly transparent retardation film Film was obtained.
  • image display is better than when the retardation films according to Comparative Examples 1 to 6 are used.
  • the in-plane retardation value Ro is a value capable of realizing a ⁇ / 4 retardation film, and a retardation film having sufficiently high transparency is obtained.
  • the circularly-polarizing plate and image display apparatus provided with the said retardation film are provided.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
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  • Optics & Photonics (AREA)
  • Polarising Elements (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

Selon un mode de réalisation, la présente invention concerne un film retardateur qui contient : une première résine d'acylate de cellulose conforme à 2 ≤ X + Y ≤ 3 (X représentant le degré de substitution des groupes acétyle, et Y représentant le degré de substitution des groupes acyle, sauf les groupes acétyle) et à 0 ≤ Y ≤ 1,5 ; ainsi qu'une seconde résine d'acylate de cellulose conforme à 2,4 ≤ X + Y ≤ 2,7 et à 0,7 ≤ Y ≤ 1. Ce film retardateur est caractérisé en ce que : les résines composant le film retardateur ont une masse moléculaire moyenne en poids de 190 000 à 300 000 ; la valeur obtenue grâce à la division de la masse moléculaire moyenne en poids par la masse moléculaire moyenne en nombre est de 2,4 à 3,3 ; la valeur absolue de la différence entre les masses moléculaires moyennes en poids des première et seconde résines d'acylate de cellulose est de 50 000 à 120 000 (inclus) ; et l'angle entre l'axe lent dans le plan et le sens de la largeur est de 40 à 50°.
PCT/JP2013/006815 2012-12-07 2013-11-20 Film retardateur, plaque polarisante circulaire et dispositif d'affichage d'image Ceased WO2014087593A1 (fr)

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WO2016158353A1 (fr) * 2015-03-31 2016-10-06 日本ゼオン株式会社 Procédé de fabrication de film étiré et film étiré
CN107405822A (zh) * 2015-03-31 2017-11-28 日本瑞翁株式会社 拉伸膜的制造方法及拉伸膜
KR20170132162A (ko) * 2015-03-31 2017-12-01 니폰 제온 가부시키가이샤 연신 필름의 제조 방법 및 연신 필름
JPWO2016158353A1 (ja) * 2015-03-31 2018-01-25 日本ゼオン株式会社 延伸フィルムの製造方法、及び、延伸フィルム
US20180093409A1 (en) * 2015-03-31 2018-04-05 Zeon Corporation Stretched film manufacturing method and stretched film
TWI702133B (zh) * 2015-03-31 2020-08-21 日商日本瑞翁股份有限公司 延伸膜之製造方法以及延伸膜
KR102496307B1 (ko) * 2015-03-31 2023-02-03 니폰 제온 가부시키가이샤 연신 필름의 제조 방법 및 연신 필름

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