WO2012008242A1 - Dispositif d'affichage à cristaux liquides - Google Patents

Dispositif d'affichage à cristaux liquides Download PDF

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Publication number
WO2012008242A1
WO2012008242A1 PCT/JP2011/063032 JP2011063032W WO2012008242A1 WO 2012008242 A1 WO2012008242 A1 WO 2012008242A1 JP 2011063032 W JP2011063032 W JP 2011063032W WO 2012008242 A1 WO2012008242 A1 WO 2012008242A1
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Prior art keywords
polarizing plate
film
liquid crystal
cellulose ester
display device
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PCT/JP2011/063032
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English (en)
Japanese (ja)
Inventor
梅田　博紀
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コニカミノルタオプト株式会社
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Priority to JP2012524494A priority Critical patent/JP5720683B2/ja
Publication of WO2012008242A1 publication Critical patent/WO2012008242A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133603—Direct backlight with LEDs
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/08—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 light absorbing layer
    • G02F2201/086—UV absorbing
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/50—Protective arrangements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/01—Function characteristic transmissive

Definitions

  • the present invention relates to a liquid crystal display device having an LED backlight.
  • a protective film is usually bonded to both surfaces of a polarizer having polarizing ability via an adhesive layer.
  • the polarizing performance of the polarizing plate fluctuates when the polarizing plate is exposed to heat and humidity due to long-term use, and further, the display performance of the liquid crystal display device deteriorates.
  • liquid crystal display devices are used in various ways, and durability is required not only in high-temperature and high-humidity environments, but also in low-temperature and high-humidity environments. -It has been found that the durability of the polarizing plate in a high-humidity environment is improved, so that the durability in other environments may be impaired.
  • An object of the present invention is to provide a liquid crystal display device having an optical film group that does not cause reddish discoloration in a polarizing plate and does not deteriorate display image quality in a liquid crystal display device using an LED as a backlight.
  • a viewing side polarizing plate having a structure sandwiched between two polarizing plate protective films, a liquid crystal cell, a backlight side polarizing plate having a structure sandwiched between two polarizing plate protective films, and an LED backlight
  • the two polarizing plate protective films of the viewing side polarizing plate are both cellulose ester films
  • the polarizing plate protective film on the liquid crystal cell side of the backlight side polarizing plate Is a cellulose ester film.
  • a liquid crystal display device using an LED as a backlight it is possible to obtain a liquid crystal display device that does not cause reddish discoloration in the polarizing plate and does not deteriorate display image quality.
  • the liquid crystal display device of the present invention is a viewing side polarizing plate having a structure sandwiched between two polarizing plate protective films, a liquid crystal cell, a backlight side polarizing plate having a structure sandwiched between two polarizing plate protective films, And the LED backlight in this order from the viewing side, the two polarizing plate protective films of the viewing side polarizing plate are both cellulose ester films, and the liquid crystal cell of the backlight side polarizing plate
  • the polarizing plate protective film on the side is a cellulose ester film.
  • FIG. 1 is a schematic view of a basic liquid crystal display device of the present invention.
  • the backlight is an LED, and in that case, a polarizing plate protective film T1 (viewing side polarizing plate protective film of the viewing side polarizing plate) and T2 (liquid crystal cell side polarizing plate protection of the viewing side polarizing plate).
  • Film) and T3 (liquid crystal cell side polarizing plate protective film of the backlight side polarizing plate) are cellulose ester films.
  • a cellulose acetate film having an acetyl group substitution degree X of T2 of 2.1 ⁇ X ⁇ 2.5 is preferable.
  • cellulose ester film As the main component of the cellulose ester film of T1 to T3 of the present invention, cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, and cellulose acetate propionate are preferable, and among these, cellulose diacetate is preferably used.
  • the cellulose ester film of T1 of the present invention is X, Y when the substitution degree of acetyl groups is X and the substitution degree of other acyl groups is Y, particularly from the viewpoint of optical isotropy required for a polarizing plate protective film.
  • a cellulose triacetate film is preferable.
  • Another resin may be mixed as long as the function of the present invention is not impaired, and various additives may be added according to the purpose.
  • T1 a commercially available cellulose triacetate film used with a normal polarizing plate protective film can be used.
  • the cellulose ester film of T2 and T3 of the present invention has high retardation development and can be made into a thin film even when it is a retardation film having a high retardation, stretching for expressing the retardation. From the viewpoint of keeping the magnification low, a film made of cellulose ester that satisfies the range of the following formula is used.
  • the cellulose ester film of T2 and T3 of the present invention is preferably a cellulose acetate film in which T2 is 2.1 ⁇ X ⁇ 2.5, and T2 and T3 are simultaneously 2.1 ⁇ X ⁇ 2.5. Most preferred is a cellulose diacetate film.
  • the cellulose acetate films T2 and T3 of the present invention can appropriately adjust the retardation required for the required optical compensation effect, and from the viewpoint of taking advantage of high retardation development, retardation Ro in the in-plane direction.
  • Is preferably 30 nm or more, more preferably in the range of 30 to 200 nm
  • the retardation Rth in the thickness direction is preferably 70 nm or more, and more preferably in the range of 70 to 300 nm.
  • the method of adjusting the phase difference is not particularly limited, but a method of adjusting by stretching is common. A detailed adjustment method will be described later.
  • cellulose acetates used for the polarizing plate protective film and the retardation film of the present invention can be synthesized by a known method.
  • the cellulose used as a raw material of cellulose acetate used in the retardation film and polarizing plate protective film of the present invention is not particularly limited, and examples thereof include cotton linters, wood pulp (derived from coniferous trees, derived from hardwoods), kenaf and the like. . Moreover, the cellulose acetate obtained from them can be mixed and used in arbitrary ratios, respectively.
  • the cellulose acetate of the present invention can be produced by a known method. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.
  • a dope preparation method a method of preparing at a temperature of 0 ° C. or higher (normal temperature or high temperature) and a cooling preparation method of preparing at a low temperature are known.
  • a halogenated hydrocarbon particularly methylene chloride
  • the Invention Association public technique public technical number 2001-1745, published on March 15, 2001, hereinafter abbreviated as public technique 2001-1745
  • paragraphs 12 to 15 the preparation method is described in the items 22 to 25.
  • the viscosity of the cellulose acetate solution of the present invention is preferably 15 to 140 Pa ⁇ s, and the temperature of the dope during dissolution and filtration is preferably 20 ° C. or higher and 30 ° C. or lower. More preferably, the viscosity of the low-viscosity cellulose acetate solution is 30 to 90 Pa ⁇ s.
  • the viscosity of the cellulose acetate solution of the present invention can be measured at 25 ° C. using a B-type viscometer Model VS-A1 (Shibaura System Co., Ltd.) according to the method described in JIS Z 8803.
  • the molecular weight of the cellulose ester is preferably 100,000 to 200,000, more preferably 130,000 to 160,000 in terms of weight average molecular weight (Mw).
  • the cellulose acetate used in the present invention preferably has a Mn / Mw ratio of 1.0 or more and less than 5.0, more preferably 2.5 or more and less than 4.0.
  • the degree of polymerization of cellulose acetate is preferably 200 to 800, more preferably 250 to 650, still more preferably 250 to 450, and particularly preferably 250 to 400 in terms of viscosity average degree of polymerization.
  • the viscosity average degree of polymerization can be measured according to Uda et al.'S limiting viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pp. 105-120, 1962). A method for measuring the viscosity average degree of polymerization is also described in JP-A-9-95538.
  • the cellulose ester film of the present invention preferably contains a sugar ester compound represented by the general formula (1) as a physical property improving agent.
  • the cellulose ester film of the present invention preferably contains an ester compound represented by the general formula (2) as a plasticizer.
  • the alkylene glycol component having 2 to 12 carbon atoms includes ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propan
  • the compound represented by the general formula (1) or (2) can be appropriately used in the range of 1 to 40% by mass of the cellulose ester film.
  • the cellulose acetate film of the present invention can contain a plasticizer other than the compounds represented by the general formulas (1) and (2) as necessary for obtaining the effects of the present invention.
  • the plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyhydric alcohol ester plasticizer, or an ester plasticizer. Agent, acrylic plasticizer and the like.
  • At least one is preferably a polyhydric alcohol ester plasticizer.
  • the polyhydric alcohol ester plasticizer is a plasticizer composed of 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.
  • a divalent to 20-valent aliphatic polyhydric alcohol ester is preferred.
  • the polyhydric alcohol preferably used in the present invention is represented by the following general formula (a).
  • R 11 represents an n-valent organic group
  • n represents a positive integer of 2 or more
  • the OH group represents an alcoholic and / or phenolic hydroxyl group.
  • the glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used.
  • alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl
  • phthalate ester plasticizer examples include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.
  • citrate plasticizer examples include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.
  • fatty acid ester plasticizers examples include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.
  • phosphate ester plasticizer examples include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.
  • the polyvalent carboxylic acid ester compound is composed of an ester of a divalent or higher, preferably a divalent to 20valent polyvalent carboxylic acid and an alcohol.
  • the aliphatic polyvalent carboxylic acid is preferably divalent to 20-valent, and in the case of an aromatic polyvalent carboxylic acid or alicyclic polyvalent carboxylic acid, it is preferably trivalent to 20-valent.
  • the polyvalent carboxylic acid is represented by the following general formula (b).
  • R 12 (COOH) m1 (OH) n1
  • R 12 represents an (m1 + n1) -valent organic group
  • m1 represents a positive integer of 2 or more
  • n1 represents an integer of 0 or more
  • a COOH group represents a carboxyl group
  • an OH group represents an alcoholic or phenolic hydroxyl group.
  • the molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750.
  • the larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose acetate.
  • the alcohol used for the polyvalent carboxylic acid ester that can be used in the present invention may be one kind or a mixture of two or more kinds.
  • Examples of particularly preferable polyvalent carboxylic acid ester compounds include, for example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, Acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like can be mentioned.
  • the plasticizer can be appropriately used in the range of 1 to 40% by mass of the cellulose ester film.
  • the cellulose ester film of the present invention can also contain an ultraviolet absorber.
  • the ultraviolet absorber is intended to improve durability by absorbing ultraviolet light having a wavelength of 400 nm or less, and the transmittance at a wavelength of 370 nm is particularly preferably 10% or less, more preferably 5% or less. Preferably it is 2% or less.
  • the amount of the UV absorber used is not uniform depending on the type of UV absorber, the operating conditions, etc., but when the dry film thickness of the polarizing plate protective film is 30 to 200 ⁇ m, the amount used is 0.5 to the polarizing plate protective film. Is preferably 10 to 10% by mass, and more preferably 0.6 to 4% by mass.
  • Antioxidant are also referred to as deterioration inhibitors.
  • a liquid crystal image display device or the like When a liquid crystal image display device or the like is placed in a high humidity and high temperature state, the cellulose acetate film may be deteriorated.
  • the antioxidant has a role of delaying or preventing the cellulose acetate film from being decomposed by, for example, the residual solvent amount of halogen in the cellulose acetate film or phosphoric acid of the phosphoric acid plasticizer. It is preferable to make it contain in a film.
  • a hindered phenol compound is preferably used.
  • 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate] triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], oct Decyl-3- (3,5-di-t-butyl-4-hydroxyphenyl
  • 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred.
  • hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.
  • the amount of these compounds added is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose derivative.
  • the cellulose ester film of the present invention has, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate in order to improve handleability. Further, it is preferable to contain inorganic fine particles such as magnesium silicate and calcium phosphate and a matting agent such as a crosslinked polymer. Of these, silicon dioxide is preferable because it can reduce the haze of the film.
  • the primary average particle diameter of the fine particles is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm.
  • the amount added can be appropriately determined.
  • the cellulose ester film of the present invention can be preferably used regardless of whether it is a film produced by a solution casting method or a film produced by a melt casting method.
  • Production of the cellulose ester film of the present invention by the solution casting method is a step of preparing a dope by dissolving cellulose ester and additives in a solvent, a step of casting the dope on an endless metal support that moves infinitely It is performed by a step of drying the cast dope as a web, a step of peeling from the metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding up the finished film.
  • the concentration of cellulose ester in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose ester is too high, the load during filtration increases and the filtration accuracy is poor. Become.
  • the concentration that achieves both of these is preferably 10 to 35% by mass, and more preferably 15 to 25% by mass.
  • the solvent used in the dope may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester.
  • a preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent.
  • the good solvent and the poor solvent change depending on the average acetylation degree (acetyl group substitution degree) of the cellulose ester.
  • the good solvent used in the present invention is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.
  • the poor solvent used in the present invention is not particularly limited, but for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone and the like are preferably used.
  • the dope preferably contains 0.01 to 2% by mass of water.
  • the solvent used for dissolving the cellulose ester is used by collecting the solvent removed from the film by drying in the film-forming process and reusing it.
  • the recovery solvent may contain trace amounts of additives added to the cellulose ester, such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are included, they are preferably reused. Can be purified and reused if necessary.
  • additives added to the cellulose ester such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are included, they are preferably reused. Can be purified and reused if necessary.
  • a general method can be used. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure.
  • a method in which a cellulose ester is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.
  • Pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside.
  • a jacket type is preferable because temperature control is easy.
  • the heating temperature with the addition of the solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates.
  • the preferred heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C.
  • the pressure is adjusted so that the solvent does not boil at the set temperature.
  • a cooling dissolution method is also preferably used, whereby the cellulose ester can be dissolved in a solvent such as methyl acetate.
  • the cellulose ester solution is filtered using an appropriate filter medium such as filter paper.
  • an appropriate filter medium such as filter paper.
  • the filter medium it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small.
  • a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable.
  • the material of the filter medium there are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable.
  • Bright spot foreign matter means that when two polarizing plates are placed in a crossed Nicol state, an optical film or the like is placed between them, light is applied from one polarizing plate side, and observation is performed from the other polarizing plate side. It is a point (foreign matter) where light from the opposite side appears to leak, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm 2 or less.
  • it is 100 pieces / cm 2 or less, still more preferably 50 pieces / m 2 or less, still more preferably 0 to 10 pieces / cm 2 . Further, it is preferable that the number of bright spots of 0.01 mm or less is small.
  • the dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration.
  • the increase in the difference (referred to as differential pressure) is small and preferable.
  • the preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.
  • the filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.
  • the metal support in the casting process is preferably a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support.
  • the cast width can be 1 ⁇ 4m.
  • the surface temperature of the metal support in the casting step is ⁇ 50 ° C. to less than the boiling point of the solvent, and a higher temperature is preferable because the web drying speed can be increased. May deteriorate.
  • the preferred support temperature is 0 to 55 ° C, more preferably 25 to 50 ° C.
  • the method for controlling the temperature of the metal support is not particularly limited, but there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.
  • the amount of residual solvent when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Particularly preferred is 20 to 30% by mass or 70 to 120% by mass.
  • the amount of residual solvent is defined by the following formula.
  • Residual solvent amount (% by mass) ⁇ (MN) / N ⁇ ⁇ 100 M is the mass of a sample collected during or after the 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, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, Particularly preferred is 0 to 0.01% by mass or less.
  • a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.
  • the cellulose ester film of the present invention it is particularly preferable to perform stretching in the width direction (lateral direction) by a tenter method in which both ends of the web are held with clips or the like. Peeling is preferably performed at a peeling tension of 300 N / m or less.
  • the means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but is preferably performed with hot air in terms of simplicity.
  • drying temperature in the web drying process is increased stepwise from 40 to 200 ° C.
  • the film thickness of the cellulose ester film is not particularly limited, but 10 to 200 ⁇ m is used.
  • the film thickness is particularly preferably 10 to 100 ⁇ m. More preferably, it is 20 to 60 ⁇ m.
  • the cellulose ester film of the present invention has a width of 1 to 4 m. Particularly, those having a width of 1.4 to 4 m are preferably used, and particularly preferably 1.6 to 3 m. If it exceeds 4 m, conveyance becomes difficult.
  • the cellulose ester film has the structure of the present invention, and the refractive index is controlled by controlling the transport tension and stretching.
  • the retardation value can be changed by lowering or increasing the tension in the longitudinal direction.
  • the film can be biaxially or uniaxially stretched sequentially or simultaneously in the longitudinal direction (film forming direction) of the film and the direction orthogonal to the longitudinal direction of the film, that is, the width direction.
  • the draw ratios in the biaxial directions perpendicular to each other are preferably in the range of 0.8 to 1.5 times in the casting direction and 1.1 to 2.5 times in the width direction, respectively. It is preferable to carry out in the range of 0.8 to 1.0 times in the direction and 1.2 to 2.0 times in the width direction.
  • the stretching temperature is preferably 120 ° C. to 200 ° C., more preferably 150 ° C. to 200 ° C., more preferably more than 150 ° C. and 190 ° C. or less.
  • the residual solvent in the film is preferably 20 to 0%, more preferably 15 to 0%.
  • the residual solvent is stretched by 11% at 155 ° C., or the residual solvent is stretched by 2% at 155 ° C. Alternatively, it is preferable that the residual solvent is stretched at 11% at 160 ° C, or the residual solvent is stretched at less than 1% at 160 ° C.
  • the method of stretching the web For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination.
  • a tenter it may be a pin tenter or a clip tenter.
  • the slow axis or the fast axis of the cellulose ester film of the present invention exists in the film plane, and ⁇ 1 is preferably ⁇ 1 ° or more and + 1 ° or less, assuming that the angle formed with the film forming direction is ⁇ 1. More preferably, it is 5 ° or more and + 0.5 ° or less.
  • This ⁇ 1 can be defined as an orientation angle, and the measurement of ⁇ 1 can be performed using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).
  • ⁇ 1 satisfying the above relationship can contribute to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to obtaining faithful color reproduction in a color liquid crystal display device.
  • ⁇ Physical properties of cellulose ester film> The moisture permeability of the cellulose ester film of the present invention is preferably 300 to 1800 g / m 2 ⁇ 24 h at 40 ° C. and 90% RH, more preferably 400 to 1500 g / m 2 ⁇ 24 h, and 40 to 1300 g / m 2 ⁇ 24 h. Particularly preferred.
  • the moisture permeability can be measured according to the method described in JIS Z 0208.
  • the cellulose ester film of the present invention has a breaking elongation of preferably 10 to 80%, more preferably 20 to 50%.
  • the visible light transmittance of the cellulose ester film of the present invention is preferably 90% or more, and more preferably 93% or more.
  • the haze of the cellulose ester film of the present invention is preferably less than 1%, particularly preferably 0 to 0.1%.
  • the cellulose ester film of the present invention can be used for a polarizing plate and a liquid crystal display device using the polarizing plate.
  • the polarizing plate of the present invention can be produced by a general method.
  • the cellulose ester film of the present invention is preferably bonded to at least one surface of a polarizer produced by subjecting the polarizer side to alkali saponification treatment and immersion drawing in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution.
  • Examples of the polarizing plate protective film for T1 and T4 of the present invention include a commercially available cellulose ester film (for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC4UE, KC8UE, KC8UY-X, -RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) are also preferably used.
  • a commercially available cellulose ester film for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC4UE, KC8UE, KC8UY-X, -RHA, KC
  • the polarizing plate used on the surface side of the display device preferably has an antireflection layer, an antistatic layer, an antifouling layer, and a backcoat layer in addition to the antiglare layer or the clear hard coat layer.
  • a polarizer which is a main component of a polarizing plate, is an element that allows only light of a plane of polarization in a certain direction to pass.
  • a typical polarizer currently known is a polyvinyl alcohol-based polarizing film, which is polyvinyl alcohol.
  • iodine is dyed on a system film and one in which dichroic dye is dyed.
  • the polarizer is formed by forming a polyvinyl alcohol aqueous solution into a film and dyeing the film by uniaxial stretching or dyeing or uniaxially stretching, and then performing a durability treatment with a boron compound.
  • the film thickness of the polarizer is preferably 5 to 30 ⁇ m, particularly preferably 10 to 20 ⁇ m.
  • the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%
  • the degree of polymerization is 2000 to 4000
  • the degree of saponification is 99.0 to 99.99 mol%.
  • Ethylene-modified polyvinyl alcohol is also preferably used.
  • an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used.
  • the difference in hot water cutting temperature between two points 5 cm away in the TD direction of the film is more preferably 1 ° C. or less in order to reduce color spots, and two points separated 1 cm in the TD direction of the film. In order to reduce color spots, it is more preferable that the difference in the hot water cutting temperature is 0.5 ° C. or less.
  • a polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability performance and has few color spots, and is particularly preferably used for a large liquid crystal display device.
  • the polarizer obtained as described above is usually used as a polarizing plate with a protective film bonded to both sides or one side thereof.
  • the adhesive used for pasting include a PVA-based adhesive and a urethane-based adhesive. Among them, a PVA-based adhesive is preferably used.
  • the polarizing plate of the present invention preferably uses a polarizing plate protective film.
  • the LED called the pseudo-white type has two peaks around 480 nm (blue) and 570 nm (yellow), and the LED called the high color rendering white type has 530 nm (green) and 620 nm (red) in addition to blue. 3 peaks are observed. However, since the wavelength characteristics are different from those of the cold cathode tube, white reproduction is different.
  • the effect becomes remarkable when it is a vertical alignment ECB type liquid crystal display device described in JP-A-2009-301010. This is because the liquid crystal display device has a high aperture ratio of 65% or more, so that the red color change of the polarizing plate can be clearly seen.
  • Example 1 ⁇ Production of Cellulose Ester Film 101> ⁇ Fine particle dispersion 1> Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by mass Ethanol 89 parts by mass The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.
  • Fine particle addition liquid 1 The fine particle dispersion 1 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. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.
  • a main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate C was charged into a pressure dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.
  • the above was put into a closed container and dissolved while stirring to prepare a dope solution.
  • the dope solution was uniformly cast on a stainless steel belt support at a temperature of 33 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 30 ° C.
  • the solvent was evaporated until the amount of residual solvent in the cast (cast) film reached 75%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m.
  • the peeled cellulose acetate film was stretched 36% in the width direction using a tenter while applying heat at 160 ° C.
  • the residual solvent at the start of stretching was 15%.
  • aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water, and then 3 g of potassium iodide and 7. It was immersed in a 45 ° C. aqueous solution consisting of 5 g and 100 g of water and uniaxially stretched (temperature 55 ° C., stretch ratio 5 times). This was washed with water and dried to obtain a polarizer.
  • a polarizer, the cellulose acetate film, and Konica Minolta Tack KC4UY (a cellulose triacetate film manufactured by Konica Minolta Opto Co., Ltd., acetyl group substitution degree 2.90) are bonded to the back side in accordance with the following steps 1 to 5.
  • a plate was made.
  • Step 1 Soaked in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to obtain a saponified cellulose acetate film on the side to be bonded to the polarizer.
  • Step 2 The polarizer was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.
  • Step 3 Excess adhesive adhered to the polarizer in Step 2 was gently wiped off and placed on the cellulose ester film treated in Step 1.
  • Step 4 The cellulose ester film, the polarizer and the back side cellulose ester film laminated in Step 3 were bonded at a pressure of 20 to 30 N / cm 2 and a conveying speed of about 2 m / min.
  • Step 5 A sample obtained by bonding the polarizer, the cellulose ester film, and Konica Minoltack KC4UY prepared in Step 4 in a dryer at 80 ° C. is dried for 2 minutes, and a polarizing plate corresponding to the cellulose ester film is prepared. did.
  • COP means ZEONOR film ZF14-060 manufactured by Nippon Zeon Co., Ltd., and bonding with a polarizer was subjected to corona discharge treatment, and thereafter a polarizing plate was produced in the same manner.
  • the above-described LED backlight unit of the liquid crystal display is diverted to a liquid crystal display device using a liquid crystal cell (opening ratio: 67%) described in FIG. 18 of JP2009-301010A to produce a liquid crystal display device.
  • a polarizing plate was bonded to the substrate.
  • the liquid crystal display device was conditioned at 23 ° C. and 55% RH for 24 hours, and then a white image was displayed.
  • the front color was visually observed and the transmission spectrum was observed (CS2000 manufactured by Konica Minolta Sensing Co., Ltd.).
  • CS2000 manufactured by Konica Minolta Sensing Co., Ltd.
  • the visual tint on the front of the bonded polarizing plate was the same.
  • no difference was observed in the transmission spectrum.
  • the liquid crystal display device was placed at 23 ° C. and 95% RH for 48 hours. It was taken out and a white image was displayed, which was similarly observed in an atmosphere of 23 ° C. and 55% RH.
  • the observation results are shown in Table 3.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Polarising Elements (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)

Abstract

La présente invention concerne un dispositif d'affichage à cristaux liquides qui utilise une diode électroluminescente (DEL) comme rétroéclairage, et qui est équipé d'un groupe de films optiques qui n'entraînent ni décoloration en rouge de la plaque de polarisation, ni dégradation de la qualité de l'image d'affichage. Il est décrit, en particulier, un dispositif d'affichage à cristaux liquides qui comprend une plaque de polarisation côté visualisation dont la structure est prise en sandwich entre deux films de protection de plaque de polarisation, une cellule à cristaux liquides, une plaque de polarisation côté rétroéclairage dont la structure est prise en sandwich entre deux films de protection de plaque de polarisation, et un rétroéclairage par DEL, dans cet ordre en partant du côté visualisation. Ledit dispositif est caractérisé en ce que chacun des deux films de protection de plaque de polarisation situés dans la plaque de polarisation côté visualisation est un film d'ester de cellulose et en ce que le film de protection de plaque de polarisation situé côté cellule à cristaux liquides de la plaque de polarisation côté rétroéclairage est un film d'ester de cellulose.
PCT/JP2011/063032 2010-07-12 2011-06-07 Dispositif d'affichage à cristaux liquides WO2012008242A1 (fr)

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
WO2012140990A1 (fr) * 2011-04-12 2012-10-18 コニカミノルタアドバンストレイヤー株式会社 Film de compensation optique et son procédé de fabrication, plaque de polarisation et dispositif d'affichage à cristaux liquides
CN107302665A (zh) * 2017-08-18 2017-10-27 联想(北京)有限公司 一种摄像装置、光圈调节方法和电子设备

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JP2009001744A (ja) * 2007-06-25 2009-01-08 Konica Minolta Opto Inc セルロースエステルフィルム、セルロースエステルフィルムの製造方法、それを用いた偏光板、及び液晶表示装置
JP2009300599A (ja) * 2008-06-11 2009-12-24 Sony Corp 偏光板、表示装置および電子機器

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JP5140513B2 (ja) * 2008-07-28 2013-02-06 富士フイルム株式会社 セルロースエステルフィルム、それを用いた位相差フィルム、偏光板、及び液晶表示装置

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JP2007080735A (ja) * 2005-09-15 2007-03-29 Nec Corp 光源装置及びその製造方法、表示装置及びその製造方法、並びに表示装置の駆動方法
JP2009001744A (ja) * 2007-06-25 2009-01-08 Konica Minolta Opto Inc セルロースエステルフィルム、セルロースエステルフィルムの製造方法、それを用いた偏光板、及び液晶表示装置
JP2009300599A (ja) * 2008-06-11 2009-12-24 Sony Corp 偏光板、表示装置および電子機器

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012140990A1 (fr) * 2011-04-12 2012-10-18 コニカミノルタアドバンストレイヤー株式会社 Film de compensation optique et son procédé de fabrication, plaque de polarisation et dispositif d'affichage à cristaux liquides
CN107302665A (zh) * 2017-08-18 2017-10-27 联想(北京)有限公司 一种摄像装置、光圈调节方法和电子设备

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