WO2012026199A1 - 位相差フィルム、及びそれを用いた偏光板、液晶表示装置 - Google Patents
位相差フィルム、及びそれを用いた偏光板、液晶表示装置 Download PDFInfo
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- WO2012026199A1 WO2012026199A1 PCT/JP2011/064381 JP2011064381W WO2012026199A1 WO 2012026199 A1 WO2012026199 A1 WO 2012026199A1 JP 2011064381 W JP2011064381 W JP 2011064381W WO 2012026199 A1 WO2012026199 A1 WO 2012026199A1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3083—Birefringent or phase retarding elements
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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
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/15—Heterocyclic compounds having oxygen in the ring
- C08K5/151—Heterocyclic compounds having oxygen in the ring having one oxygen atom in the ring
- C08K5/1545—Six-membered rings
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
- C08J2301/08—Cellulose derivatives
- C08J2301/10—Esters of organic acids
- C08J2301/12—Cellulose acetate
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K2323/00—Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
- C09K2323/03—Viewing layer characterised by chemical composition
- C09K2323/035—Ester polymer, e.g. polycarbonate, polyacrylate or polyester
Definitions
- the present invention relates to a retardation film, a polarizing plate using the same, and a liquid crystal display device.
- Liquid crystal display devices are widely used in monitors for personal computers and portable devices, and for television applications because of their various advantages such as low voltage and low power consumption, and enabling miniaturization and thinning.
- television-use liquid crystal display devices that are expected to be viewed from various angles on a large screen have strict requirements for viewing angle dependency, and recently, the performance requirements for liquid crystal display devices for monitor use are also increasing. Therefore, various modes in which the viewing angle dependency is reduced by devising the alignment state of the liquid crystal in the liquid crystal cell have been proposed. For example, IPS (In-Plane Switching) mode, OCB (Optically Compensatory Bend) mode, VA
- IPS In-Plane Switching
- OCB Optically Compensatory Bend
- VA Various researches have been made on liquid crystal display devices such as (Vertically Aligned) mode.
- Cellulose ester film is rich in moisture permeability compared to other polymer films, and has high adhesiveness with polarizers of polarizing plates in which PVA having high hydrophilicity is generally used, and has high optical isotropy. Since it is generally used as a protective film for polarizing plates used in various liquid crystal display devices, it has a simple structure without increasing the number of parts by giving it a function as a retardation film. Visibility can be improved.
- Patent Document 1 describes a retardation film provided with a desired retardation value by adding a retardation increasing agent to cellulose triacetate.
- the Ro value is made reverse wavelength dispersible. be able to.
- the cellulose ester is most inferior in moisture resistance.
- the total acyl group substitution degree of the cellulose ester is reduced, for example, when it is 2.55 or less (hereinafter referred to as a low substitution cellulose ester)
- the high substitution The moisture permeability and moisture content are higher than those of cellulose esters, and there is a problem that variations in dimensions and retardation values during use increase.
- an object of the present invention is to provide a retardation film that uses cellulose ester, has less optical variation, has improved retardation variation after saponification treatment, and improved wet heat stability of internal haze, and a polarizing plate and a liquid crystal display device using the same. It is to provide.
- An optical film comprising a cellulose ester resin and a compound represented by the following general formula (1), wherein the compound has an average substitution degree of 3.0 to 6.0 and a substitution degree of 4 or less Is contained in an amount of 30% by mass to 80% by mass.
- R 1 to R 8 represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted allylcarbonyl group, and R 1 to R 8 may be the same or different. .
- B- (GA) nGB (Wherein B is a hydroxy group or carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms)
- A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.
- 3. 3 The retardation film as described in 1 or 2 above, wherein the content ratio of the component having a substitution degree of 8.0 of the compound represented by the general formula (1) is 2% or less.
- a polarizing plate comprising the retardation film according to any one of 1 to 3 on at least one surface of a polarizer.
- a liquid crystal display device using the polarizing plate described in 4 above on at least one surface of a liquid crystal cell.
- a retardation film that uses cellulose ester, has little optical variation, has improved retardation variation after saponification treatment, and improved wet heat stability of internal haze, and a polarizing plate and a liquid crystal display device using the same. be able to.
- ⁇ Optical variation> The deviation between the slow axis of the retardation film of the present invention and the absorption axis of the polarizer and the dispersion of the retardation are evaluated by minute light leakage. It is estimated that the smaller the light leakage, the smaller the optical variation.
- the minute light leakage can be calculated by measuring the in-plane retardation value Ro and the slow axis direction ⁇ in each part of the film with a minute pitch of 0.5 ⁇ m or less (wavelength or less).
- the retardation film is conditioned for 24 hours in an environment of 23 ° C. and relative humidity of 55 ⁇ 3%, and then a 100 ⁇ m square range is 0.5 ⁇ m or less using a light source with an average wavelength ⁇ . Measure in increments to obtain Ro and ⁇ . Using these values, the minute light leakage X can be calculated according to the following equation.
- N represents the number of measurement points. This is measured at 10 points so that the gaps are even in the width direction of the film, and the average value is Xa.
- Xa is preferably 2.5 ⁇ 10 ⁇ 7 or less, more preferably 2.0 ⁇ 10 ⁇ 7 or less, and particularly preferably 1.5 ⁇ 10 ⁇ 7 or less.
- the measuring apparatus is not particularly specified as long as it can measure Ro and ⁇ in 0.5 ⁇ m increments or less.
- the following can be used.
- a phase difference measuring device such as Abrio-IM (manufactured by HINDS Instruments) that combines a liquid crystal phase shifter modulation method with a transmission microscope.
- ⁇ In order of light source, lower polarizing plate, wave plate with rotation mechanism, sample, objective lens, rotary wave plate, upper polarizing plate with absorption axis parallel to the lower polarizing plate, CCD camera A phase difference measuring device that measures Ro and ⁇ by arranging and calculating the Mueller matrix.
- ⁇ In order of the light source in the transmission microscope, the lower polarizing plate, the sample placed on the stage base with the rotation mechanism, the objective lens, the upper polarizing plate arranged with the absorption axis in the orthogonal direction with respect to the lower polarizing plate, and the CCD camera.
- Arranged orientation angle measuring device in this case, Ro required for calculating X is assumed to be substantially constant in a 100 ⁇ m square, and a value measured by another phase difference measuring device is used separately).
- the CCD camera should have 400,000 pixels or more, the polarizing plate should have an extinction ratio of 10 ⁇ 4 or less, the objective lens should have a magnification of 10 times or more, the measurement wavelength ⁇ should be 520 to 560 nm, and the accuracy of the rotation mechanism should be ⁇ 0.1 ° or less. preferable.
- the internal haze in the present invention is a haze generated by a scattering factor inside the film, and the inside is a portion of 5 ⁇ m or more from the film surface.
- the internal haze is measured with a haze meter by dropping a solvent having a refractive index of ⁇ 0.05 on the film interface so that the haze on the film surface can be ignored as much as possible.
- Haze meter (turbidity meter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.)
- the light source uses a 5V9W halogen bulb, and the light receiving unit uses a silicon photocell (with a relative visibility filter).
- the value is 0.02 or less in the haze measurement of the film when a solvent having a refractive index of ⁇ 0.05 is dropped on the film interface with this apparatus.
- the measurement was performed in accordance with JIS K-7136 in an atmosphere of 23 ° C. and 55% RH.
- the blank haze 1 of a measuring instrument other than the film is measured.
- the glass and glycerin used in the above measurement are as follows.
- the compound represented by the general formula (1) of the present invention (hereinafter also referred to as a sugar ester compound) has an average degree of substitution of 3.0 to 6.0, and a component having a degree of substitution of 4 or less is 30% by mass or more. It is characterized by containing 80% by mass or less.
- the degree of substitution of the compound represented by the general formula (1) represents the number of substituents other than hydrogen among the eight hydroxyl groups contained in the general formula (1). Of R 1 to R 8 in the general formula (1), this represents a number containing a group other than hydrogen. Therefore, when all of R 1 to R 8 are substituted with a substituent other than hydrogen, the degree of substitution is 8.0, the maximum value, and when all of R 1 to R 8 are hydrogen atoms, 0.0 It becomes.
- the average degree of substitution of the compound represented by the general formula (1) needs to be 3.0 to 6.0.
- the degree of substitution of the general formula (1) in the present invention it is appropriate to use the average degree of substitution, and the average degree of substitution is measured from the area ratio of the chart showing the degree of substitution distribution by high performance liquid chromatography by the following method. be able to.
- the sugar ester compound has a higher degree of substitution in consideration of only the retardation development.
- the average degree of substitution is slightly lower, and a certain degree of low substitution more than a certain level. It has been found that a mixture of components is preferred.
- the effect mechanism is presumed to be achieved by making the property of phase retardation and compatibility with cellulose ester a mixture of compounds having similar structures.
- the average substitution degree is more preferably 4.0 or more, and the component having a substitution degree of 4 or less is preferably 35% by mass or more.
- R 1 to R 8 represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted allylcarbonyl group, that is, an acyl group, and R 1 to R 8 are the same. Or they may be different (hereinafter, R 1 to R 8 are also referred to as acyl groups).
- sugar as a raw material for synthesizing the sugar ester compound according to the present invention examples include the following, but the present invention is not limited to these.
- Glucose galactose, mannose, fructose, xylose or arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .
- gentiobiose gentiotriose
- gentiotetraose gentiotetraose
- xylotriose galactosyl sucrose
- the monocarboxylic acid used in the synthesis of the sugar ester compound according to the present invention known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used.
- the carboxylic acid used may be one type or a mixture of two or more types.
- Examples of preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, Saturated lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, and laxaric acid
- unsaturated fatty acids such as fatty acids, undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and oc
- Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
- aromatic monocarboxylic acids examples include aromatic monocarboxylic acids in which 1 to 5 alkyl groups or alkoxy groups are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzylic acid, An aromatic monocarboxylic acid having two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, tetralin carboxylic acid, or a derivative thereof can be exemplified, and benzoic acid is particularly preferable.
- the sugar ester compound of the present invention can be produced by reacting a sugar ester with an acylating agent (also referred to as an esterifying agent, for example, an acid halide of acetyl chloride, an anhydride such as acetic anhydride).
- an acylating agent also referred to as an esterifying agent, for example, an acid halide of acetyl chloride, an anhydride such as acetic anhydride.
- the distribution of the degree of substitution is made by adjusting the amount of acylating agent, the timing of addition, and the esterification reaction time, but it is possible to mix sugar ester compounds with different degrees of substitution or compounds with different degrees of substitution purely isolated. By mixing, components having a target average substitution degree and a substitution degree of 4 or less can be adjusted.
- the inside of the Kolben was depressurized to 4 ⁇ 10 2 Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 ⁇ 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off. Then, 1 L of toluene and 300 g of a 0.5% by mass aqueous sodium carbonate solution were added, and the mixture was stirred at 50 ° C. for 30 minutes and then allowed to stand to separate a toluene layer.
- the obtained mixture was analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS). As a result, A-1 was 1.2% by mass, A-2 was 13.2% by mass, and A-3 was 14.2% by mass. %, A-4 was 35.4% by mass, A-5 and the like were 40.0% by mass. The average degree of substitution was 5.2.
- A-5 etc. means a mixture of all components having a substitution degree of 4 or less, that is, compounds having substitution degrees of 4, 3, 2, 1. The average degree of substitution was calculated with A-5 as the degree of substitution of 4.
- the total acyl group substitution degree (that is, acetyl substitution degree) of the cellulose ester is less than 2.00, deterioration in film surface quality due to increase in dope viscosity, haze-up due to increase in stretching tension, etc. may occur. .
- the total acyl group substitution degree is larger than 2.55, it is difficult to obtain a necessary phase difference.
- the method for measuring the degree of acyl substitution can be carried out according to ASTM D-817-91, and the preferred total degree of acyl group substitution is 2.2 to 2.45.
- the number average molecular weight (Mn) of the cellulose ester is preferably strong in the mechanical strength of the film from which the range of 30000-300000 is obtained. Further, those having 50000-200000 are preferably used.
- the ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose ester is preferably 1.4 to 3.0.
- the number average molecular weight (Mn) and weight average molecular weight (Mw) of the cellulose ester were measured using gel permeation chromatography (GPC).
- the measurement conditions are as follows.
- cellulose used as the raw material for the cellulose ester there are no particular limitations on the cellulose used as the raw material for the cellulose ester, and examples include cotton linters, wood pulp (derived from conifers and hardwoods), and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.
- the cellulose ester according to the present invention can be produced by a known method. Specifically, it can be synthesized with reference to the methods described in JP-A Nos. 10-45804 and 2009-161701.
- the optical film of the present invention preferably contains an ester compound represented by the following general formula (2) from the viewpoint of retardation stability when the polarizing plate changes in the environment.
- 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
- alkylene glycols having 2 to 12 carbon atoms are particularly preferable because of excellent compatibility with cellulose esters.
- aryl glycol component having 6 to 12 carbon atoms examples include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol and the like, and these glycols can be used as one kind or a mixture of two or more kinds.
- Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like. These glycols include one kind or two or more kinds. Can be used as a mixture.
- alkylene dicarboxylic acid component having 4 to 12 carbon atoms examples include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and the like. Used as a mixture of two or more.
- arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid.
- the retardation film of the present invention can contain a plasticizer in addition to the compound represented by the general formula (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.
- Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these.
- triethylene glycol triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.
- monocarboxylic acid used for polyhydric alcohol ester there is no restriction
- Preferred examples of the monocarboxylic acid include the following, but the present invention is not limited to this.
- 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 particularly preferably 1-10.
- acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also 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-hexanoic 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, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.
- Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
- aromatic monocarboxylic acids examples include those in which 1 to 3 alkoxy groups such as alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable.
- the molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose ester.
- 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.
- 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.
- Preferred examples of the polyvalent carboxylic acid include the following, but the present invention is not limited to these.
- Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal
- An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used.
- the alcohol used in the polyvalent carboxylic acid ester compound that can be used in the present invention is not particularly limited, and known alcohols and phenols can be used.
- an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms.
- alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof
- aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can be preferably used.
- the alcoholic or phenolic hydroxyl group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid.
- monocarboxylic acids include the following, but the present invention is not limited thereto.
- aliphatic monocarboxylic acid a straight-chain or side-chain fatty acid having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms.
- 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, and laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.
- Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
- aromatic monocarboxylic acids examples include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid.
- benzoic acid and toluic acid examples include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid.
- the aromatic monocarboxylic acid which has, or those derivatives can be mentioned.
- Particularly preferred are acetic acid, propionic acid, and benzoic acid.
- 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 ester.
- 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.
- the acid value of the polyvalent carboxylic acid ester compound that can be used in the present invention is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. By setting the acid value within the above range, retardation fluctuations are also suppressed, which is preferable.
- the acid value refers to the number of milligrams of potassium hydroxide necessary to neutralize the acid (carboxyl group present in the sample) contained in 1 g of the sample.
- the acid value is measured according to JIS K0070.
- tributyl trimellitic acid and tetrabutyl pyromellitic acid.
- the retardation 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 ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body.
- These are commercially available products made by BASF Japan and can be preferably used.
- the UV absorbers preferably used in the present invention are benzotriazole UV absorbers, benzophenone UV absorbers, and triazine UV absorbers, particularly preferably benzotriazole UV absorbers and benzophenone UV absorbers. .
- a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as an ultraviolet absorber.
- the polarizing plate protective film according to the present invention preferably contains two or more kinds of ultraviolet absorbers.
- a polymeric ultraviolet absorber can be preferably used, and in particular, a polymer type ultraviolet absorber described in JP-A-6-148430 is preferably used.
- the method of adding the UV absorber can be added to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane or a mixed solvent thereof. Or you may add directly in dope composition.
- an alcohol such as methanol, ethanol or butanol
- an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane or a mixed solvent thereof.
- inorganic powders that do not dissolve in organic solvents use a dissolver or sand mill in the organic solvent and cellulose ester to disperse them before adding them to the dope.
- 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.
- Antioxidants are also called anti-degradation agents. For example, they have the role of delaying or preventing the film from decomposing due to the residual solvent halogen in the film or phosphoric acid of the phosphoric acid plasticizer. preferable.
- 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 ester.
- the retardation 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, and aluminum silicate in order to improve handling properties. It is preferable to contain inorganic fine particles such as magnesium silicate and calcium phosphate and fine particles 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.
- These fine particles preferably form secondary particles having a particle size of 0.1 to 5 ⁇ m and are contained in the retardation film, and the preferable average particle size is 0.1 to 2 ⁇ m, more preferably 0.2 to 0.6 ⁇ m.
- irregularities having a height of about 0.1 to 1.0 ⁇ m are formed on the film surface, thereby providing appropriate slipperiness to the film surface.
- the primary average particle diameter of the fine particles used in the present invention is measured by observing the particles with a transmission electron microscope (magnification of 500,000 to 2,000,000 times), observing 100 particles, measuring the particle diameter, and measuring the average. The value was taken as the primary average particle size.
- the apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter, and particularly preferably 100 to 200 g / liter.
- a larger apparent specific gravity makes it possible to produce a high-concentration dispersion, which improves haze and agglomerates, and is particularly preferred when preparing a dope having a high solid content concentration. .
- Silicon dioxide fine particles having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more are, for example, a mixture of vaporized silicon tetrachloride and hydrogen burned in air at 1000 to 1200 ° C. Can be obtained. For example, it is marketed with the brand name of Aerosil 200V and Aerosil R972V (above, Nippon Aerosil Co., Ltd. product), and can use them.
- the apparent specific gravity described above is calculated by the following equation by taking a certain amount of silicon dioxide fine particles in a graduated cylinder, measuring the weight at this time.
- Apparent specific gravity (g / liter) silicon dioxide mass (g) / volume of silicon dioxide (liter)
- Examples of the method for preparing the fine particle dispersion used in the present invention include the following three types.
- Preparation Method A After stirring and mixing the solvent and fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. The fine particle dispersion is added to the dope solution and stirred.
- Preparation Method B After stirring and mixing the solvent and fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. Separately, a small amount of cellulose ester is added to the solvent and dissolved by stirring. The fine particle dispersion is added to this and stirred. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.
- Preparation Method C Add a small amount of cellulose ester to the solvent and dissolve with stirring. Fine particles are added to this and dispersed by a disperser. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.
- Preparation method A is excellent in dispersibility of silicon dioxide fine particles
- preparation method C is excellent in that silicon dioxide fine particles are difficult to re-aggregate.
- the preparation method B described above is a preferable preparation method that is excellent in both dispersibility of the silicon dioxide fine particles and difficulty in reaggregation of the silicon dioxide fine particles.
- the concentration of silicon dioxide when the silicon dioxide fine particles are mixed with a solvent and dispersed is preferably 5% by mass to 30% by mass, more preferably 10% by mass to 25% by mass, and most preferably 15% by mass to 20% by mass.
- a higher dispersion concentration is preferable because liquid turbidity with respect to the added amount tends to be low, and haze and aggregates are improved.
- the solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.
- the amount of silicon dioxide fine particles added to the cellulose ester is preferably 0.01 parts by mass to 5.0 parts by mass and more preferably 0.05 parts by mass to 1.0 part by mass with respect to 100 parts by mass of the cellulose ester. Preferably, 0.1 to 0.5 parts by mass is most preferable. The larger the added amount, the better the dynamic friction coefficient, and the smaller the added amount, the less aggregates.
- Disperser can be a normal disperser. Dispersers can be broadly divided into media dispersers and medialess dispersers. For dispersing silicon dioxide fine particles, a medialess disperser is preferred because of its low haze. Examples of the media disperser include a ball mill, a sand mill, and a dyno mill.
- the medialess disperser there are an ultrasonic type, a centrifugal type, a high pressure type, and the like.
- a high pressure disperser is preferable.
- the high pressure dispersion device is a device that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a narrow tube.
- the maximum pressure condition inside the apparatus is preferably 9.807 MPa or more in a thin tube having a tube diameter of 1 to 2000 ⁇ m.
- Examples of the high-pressure dispersing apparatus include an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation or a nanomizer manufactured by Nanomizer. And UHN-01 manufactured by Sanwa Machinery Co., Ltd.
- casting a dope containing fine particles so as to be in direct contact with the casting support is preferable because a film having high slip properties and low haze can be obtained.
- the film is peeled off, dried and wound into a roll, and then a functional thin film such as a hard coat layer or an antireflection layer is provided.
- a functional thin film such as a hard coat layer or an antireflection layer is provided.
- packaging is usually performed in order to protect the product from dirt, static electricity, and the like.
- the packaging material is not particularly limited as long as the above purpose can be achieved, but a material that does not hinder volatilization of the residual solvent from the film is preferable.
- Specific examples include polyethylene, polyester, polypropylene, nylon, polystyrene, paper, various non-woven fabrics, and the like. Those in which the fibers are mesh cloth are more preferably used.
- the retardation 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 retardation film of the present invention by the solution casting method is a step of preparing a dope by dissolving a cellulose ester and an additive 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 acetate 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 retardation film of the present invention it is particularly preferable to stretch in the width direction (lateral direction) by a tenter method in which both ends of the web are gripped by 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 retardation 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 retardation 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 retardation film of the present invention has a retardation value Ro defined by the following formula (i) of 30 to 90 nm and a retardation value Rth defined by the following formula (ii) of 70 to 300 nm, which will be described later. This is a preferable phase difference in enlarging the viewing angle of a VA type (MVA, PVA) liquid crystal display device.
- a retardation value Ro defined by the following formula (i) of 30 to 90 nm and a retardation value Rth defined by the following formula (ii) of 70 to 300 nm, which will be described later.
- Formula (i) Ro (nx ⁇ ny) ⁇ d
- Formula (ii) Rth ⁇ (nx + ny) / 2 ⁇ nz ⁇ ⁇ d (Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is (The thickness of the film (nm).)
- the retardation values Ro and Rth can be measured using an automatic birefringence meter. For example, using KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), the wavelength can be determined at 589 nm in an environment of a temperature of 23 ° C. and a humidity of 55% RH.
- the retardation film has the structure of the present invention, and further, 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 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.
- the moisture permeability of the optical 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, particularly 40 to 1300 g / m 2 ⁇ 24 h. preferable.
- the moisture permeability can be measured according to the method described in JIS Z 0208.
- the breaking elongation of the optical film of the present invention is preferably 10 to 80%, more preferably 20 to 50%.
- the visible light transmittance of the optical film of the present invention is preferably 90% or more, and more preferably 93% or more.
- the haze of the optical film of the present invention is preferably less than 1%, particularly preferably 0 to 0.1%.
- the optical 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 is characterized in that it is a polarizing plate in which the retardation film of the present invention is bonded to at least one surface of a polarizer.
- the liquid crystal display device of the present invention is characterized in that the polarizing plate according to the present invention is bonded to at least one liquid crystal cell surface via an adhesive layer or the like.
- the polarizing plate of the present invention can be produced by a general method.
- the retardation side of the retardation film of the present invention is preferably bonded to at least one surface of a polarizer prepared by subjecting the polarizer side to alkali saponification treatment and immersion drawing in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution.
- cellulose ester films for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC8UX-RHA, KC8UX-RHA, KC8UX KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.
- cellulose ester films for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC8UX-RHA, KC8UX-RHA, KC8UX KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.
- 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%.
- the 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.
- 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.
- a protective film is normally bonded by the both sides or one side.
- 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 retardation film of the present invention can be used for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), VA-IPS, TBA, IPS, OCB.
- VA vertical alignment type liquid crystal display device
- VA-IPS VA-IPS
- TBA TBA
- liquid crystal display device with a 30-inch screen or more can obtain a liquid crystal display device with excellent visibility such as uneven coloring and front contrast with little environmental fluctuation, reduced light leakage.
- Example 1 Preparation of retardation film 101> ⁇ Fine particle dispersion 1> Fine particles (Aerosil R812 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. A cellulose ester having an acetyl substitution degree of 2.00 was added to 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 dope solution was prepared by dissolving with stirring.
- 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 retardation film was stretched 20% in the width direction using a tenter while applying heat at 170 ° C.
- the residual solvent at the start of stretching was 15%.
- the drying temperature was 130 ° C. and the transport tension was 100 N / m.
- a retardation film 101 having a dry film thickness of 40 ⁇ m was obtained.
- the retardation conditions 102 to 126 were prepared by changing the production conditions such as the materials shown in Tables 2 and 3 and the stretching ratios and temperatures shown in Table 4 to adjust to desired retardations.
- ⁇ Preparation of retardation film 127> The following two types of dopes were prepared, and a laminated retardation film 127 having a core and a skin part was prepared by co-casting.
- each of the above compositions was put into a mixing tank and stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 ⁇ m and a sintered metal filter having an average pore size of 10 ⁇ m to prepare each cellulose ester dope.
- the dope was co-cast with a band casting machine so as to have a three-layer structure of skin layer / core layer / skin layer.
- the core layer was made thickest by adjusting the casting amount of each dope, and as a result, simultaneous multilayer casting was performed so that the film thickness of the stretched film was 40 ⁇ m.
- the film peeled off from the band with a residual solvent amount of about 30% by mass was heated to 140 ° C with a tenter and widened to a stretch rate of 32%, and then relaxed at 140 ° C for 60 seconds so that the stretch rate was 30%. I let you. Thereafter, the tenter transport was shifted to the roll transport, and further dried at 120 to 150 ° C. and wound up.
- a halogen light source a bandpass filter (center wavelength 550 nm, half width) 80 nm), lower polarizing plate, wave plate with rotation mechanism, retardation film, 20 ⁇ objective lens, rotary wave plate, lower upper polarizing plate, CCD camera (4 million pixels), and using a measuring device in which components are arranged in this order. Measurement was performed while rotating the two wave plates, and a Mueller matrix for each pixel was calculated from the change in the amount of light, and Ro, ⁇ , and X were calculated from the values.
- This measurement was repeated at equal intervals in the width direction of the film to obtain 10 points of X, and the average value was set to Xa and evaluated according to the following criteria.
- the size of each pixel was 0.33 ⁇ m, and the number of measurement data for position measurement was 91809 points.
- the prepared retardation film was immersed in a 2 mol / L potassium hydroxide solution at 40 ° C. for 30 seconds, then washed with water and dried in an oven at 60 ° C. dry for 5 minutes, and the retardation was measured by the following procedure to obtain an initial value. .
- a 35 mm ⁇ 35 mm sample was cut out from the obtained retardation film, conditioned at 25 ° C. and 55% RH for 2 hours, and measured with an automatic birefringence meter (KOBRAWR, Oji Scientific Co., Ltd.) from the vertical direction at 589 nm From the extrapolated value of the retardation value measured in the same manner while tilting the film surface, the following formula was used.
- Formula (i) Ro (nx ⁇ ny) ⁇ d
- Formula (ii) Rth ⁇ (nx + ny) / 2 ⁇ nz ⁇ ⁇ d (Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is (The thickness of the film (nm).)
- the retardation values Ro and Rth were measured using KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) in an environment of a temperature of 23 ° C. and a humidity of 55% RH at a wavelength of 589 nm.
- Evaluation criteria were determined by the difference between before and after the wet heat endurance test, and evaluated according to the following definitions.
- the retardation film of the present invention has a slight light leakage and retardation desirable as a retardation film, and the retardation change rate before and after the wet heat durability test is small, and the internal haze difference before and after the wet heat durability test is also small. It can be seen that the retardation film has excellent wet heat durability.
- Example 2 ⁇ Preparation of retardation films 201 and 205> A film formed in the same manner as the retardation film 101 of Example 1 was immersed in a 4 mol / L potassium hydroxide solution at 50 ° C. for 90 seconds, then washed with water, dried in an oven at 60 ° C. dry for 5 minutes, and saponified. A retardation film was obtained (saponification condition 2). This film was designated as a retardation film 201.
- a film formed in the same manner as the retardation film 101 of Example 1 was immersed in a 1.5 mol / L potassium hydroxide solution at 30 ° C. for 30 seconds, then washed with water and dried in an oven at 60 ° C. dry for 5 minutes.
- a saponified retardation film was obtained (saponification condition 3).
- This film was designated as a retardation film 205.
- Retardation films 202 to 204 and 206 to 211 that were respectively treated under the saponification conditions were prepared in the same manner as the retardation films 201 and 205 except that the cellulose esters listed in Table 5 were used.
- Example 1 Except that the saponification treatment carried out in Example 1 was not carried out, the same as in Example 1, minute light leakage, measurement of retardation Ro and Rth before and after wet heat durability test, measurement of internal haze difference before and after wet heat durability test Went. The results are shown in Table 5.
- the retardation film of the present invention can form a retardation film having a small haze change by lowering the draw ratio by using a cellulose ester having a lower substitution degree when weakly saponified.
- Example 3 Preparation of retardation films 301 and 302> Except that the composition of the main dope of Example 1 was changed as follows, the film formed and saponified under saponification conditions 1 and 2 in the same manner as in Example 1 were used as retardation films 301 and 302, respectively. The same evaluation was performed. The results are shown in Table 6.
- Example 4 Preparation of retardation film 401>
- the sugar ester compound 15 was prepared by adding 1.3% by mass of A-1 to the sugar ester compound 1 and 2.5% of the A-1 component. All of the average substitution degrees are 5.2.
- a retardation film containing these compounds was produced in the same manner as in Example 1, and a film obtained by saponification treatment (saponification treatment condition 1) was used as a retardation film 401, and the same evaluation as in Example 1 was performed. The results are shown in Table 7.
- Table 7 shows that when the content mass ratio of the component having a substitution degree of 8.0 of the sugar ester compound is 2.0% or less, the retardation film is more excellent in wet heat durability.
- Example 5 Preparation of polarizing plate> A polyvinyl alcohol film having a thickness of 120 ⁇ m was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times).
- polarizers, the retardation film, and Konica Minolta Tack KC4UY (cellulose ester film manufactured by Konica Minolta Opto Co., Ltd.) were bonded to the back side to prepare polarizing plates 1 to 41.
- 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 retardation film and Konica Minoltack KC8UY.
- 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 lightly wiped off and placed on the retardation film treated in Step 1.
- Step 4 The retardation film, the polarizer and the back side Konica Minol Tack KC8UY laminated in Step 3 were bonded at a pressure of 20-30 N / cm 2 and a conveying speed of about 2 m / min.
- Step 5 A sample obtained by bonding the polarizer, the retardation film, and the Konica Minolta Tack KC8UY produced in Step 4 in a dryer at 80 ° C. is dried for 2 minutes, and a polarizing plate corresponding to the retardation film is produced. did.
- a liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics as a liquid crystal display device were evaluated.
- the double-sided polarizing plates of Sony 40-type display BRAVIA X1 were peeled off, and the prepared polarizing plates were bonded to both surfaces of the glass surface of the liquid crystal cell.
- front contrast of liquid crystal display device 40-50 ⁇ : 20 to less than 40 ⁇ : 10 to less than 20 (front contrast of liquid crystal display device)
- the front contrast of each liquid crystal display device was measured.
- the front contrast was measured by a front contrast measuring device (EZ-contrast) manufactured by ELDIM, and the light quantity during white display and black display was measured.
- the measurement results were ranked according to superiority or inferiority according to the value of the front contrast as follows.
- Front contrast ratio 3000: 1 or more
- B: Front contrast ratio 2999: 1 to 2000: 1
- ⁇ : Front contrast ratio 1999: 1 to 1000: 1
- X: Front contrast ratio 999: 1 or less
- Tables 8 and 9 show that the retardation film of the present invention, the polarizing plate using the retardation film, and the liquid crystal display device are superior in viewing angle and front contrast as compared with the comparative example.
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Abstract
Description
2.下記一般式(2)で表されるエステル化合物を含有することを特徴とする前記1に記載の位相差フィルム。
(式中、Bはヒドロキシ基またはカルボン酸残基、Gは炭素数2~12のアルキレングリコール残基または炭素数6~12のアリールグリコール残基または炭素数が4~12のオキシアルキレングリコール残基、Aは炭素数4~12のアルキレンジカルボン酸残基または炭素数6~12のアリールジカルボン酸残基を表す。nは1以上の整数を表す。)
3.一般式(1)で示される化合物の置換度8.0である成分の含有質量比率が2%以下であることを特徴とする前記1または2に記載の位相差フィルム。
<光学ばらつき>
本発明の位相差フィルムの遅相軸と偏光子の吸収軸とのずれと位相差のばらつきをいい、微少光漏れによって評価される。微少光漏れが小さいほど光学ばらつきが小さいと評価される。
・透過型顕微鏡に、光源、下偏光板、サンプル、対物レンズ、フォトニック結晶による集積型偏光板(CCDの画素毎に吸収軸方向を変化させている)付きカメラという順に配置した装置を用い、回転検光子法と同様の解析法により位相差・遅相軸方向を測定する装置。
・透過型顕微鏡に液晶位相子変調法を組み合わせたAbrio-IM(HINDS Instruments社製)などの位相差測定装置。
・透過型顕微鏡に光源、下偏光板、回転機構付き波長板、サンプル、対物レンズ、回転式波長板、下偏光板と平行方向に吸収軸を持つように配置した上偏光板、CCDカメラという順に配置し、ミューラーマトリクスを算出することによりRo、φを測定する位相差測定装置。
・透過型顕微鏡に光源、下偏光板、回転機構付きステージ台に設置されたサンプル、対物レンズ、下偏光板に対して直交方向に吸収軸を持つように配置した上偏光板、CCDカメラという順に配置した配向角測定装置(この場合、Xを算出する際に必要となるRoは、100μm角中ではほぼ一定と仮定し、別途他の位相差測定機で測定した値を使用する)。
<内部ヘイズ>
本発明でいう内部ヘイズとは、フィルムの内部の散乱因子により発生するヘイズであり、内部とは、フィルム表面から5μm以上の部分である。
ヘイズメーター(濁度計)(型式:NDH 2000、日本電色(株)製)
光源は、5V9Wハロゲン球、受光部は、シリコンフォトセル(比視感度フィルター付き)を用いている。
2.その上にカバーガラスを載せる。カバーガラスは押さえなくてもグリセリンは広がる。
図1参照
5.その上に測定する試料フィルムを載せる。
6.試料フィルム上にグリセリンを滴下する。(0.05ml)
図3参照
7.その上にカバーガラスを載せる。
8.ヘイズメーターにセットしヘイズ2を測定する。
グリセリン: 関東化学製 鹿特級
<一般式(1)で表される化合物>
本発明の一般式(1)で表される化合物(以下、糖エステル化合物ともいう)の平均置換度は3.0~6.0であり、かつ置換度が4以下の成分を30質量%以上80質量%以下含有することを特徴とする。
1)LC部
装置:日本分光(株)製カラムオーブン(JASCO CO-965)、ディテクター(JASCO UV-970-240nm)、ポンプ(JASCO PU-980)、デガッサ-(JASCO DG-980-50)
カラム:Inertsil ODS-3 粒子径5μm 4.6×250mm(ジーエルサイエンス(株)製)
カラム温度:40℃
流速:1ml/min
移動相:THF(1%酢酸):H2O(50:50)
注入量:3μl
2)MS部
装置:LCQ DECA(Thermo Quest(株)製)
イオン化法:エレクトロスプレーイオン化(ESI)法
Spray Voltage:5kV
Capillary温度:180℃
Vaporizer温度:450℃
<セルロースエステル>
本発明の光学フィルムに使用することができる、セルロースエステルとしては、公知の光学フィルムに使用することができる、セルローストリアセテート、セルロースジアセテート、セルロースエステルプロピオネート等があげられる。
カラム: Shodex K806、K805、K803G(昭和電工(株)製を3本接続して使用した)
カラム温度:25℃
試料濃度: 0.1質量%
検出器: RI Model 504(GLサイエンス社製)
ポンプ: L6000(日立製作所(株)製)
流量: 1.0ml/min
校正曲線: 標準ポリスチレンSTK standard ポリスチレン(東ソー(株)製)Mw=1000000~500の13サンプルによる校正曲線を使用した。13サンプルは、ほぼ等間隔に用いる。
<一般式(2)で表されるエステル化合物>
本発明の光学フィルムには、特に偏光板の環境変化でのリタデーション安定性の観点から、下記一般式(2)で表されるエステル化合物を含有することが好ましい。
(式中、Bはヒドロキシ基またはカルボン酸残基、Gは炭素数2~12のアルキレングリコール残基または炭素数6~12のアリールグリコール残基または炭素数が4~12のオキシアルキレングリコール残基、Aは炭素数4~12のアルキレンジカルボン酸残基または炭素数6~12のアリールジカルボン酸残基を表す。nは1以上の整数を表す。)
一般式(2)において、炭素数2~12のアルキレングリコール成分としては、エチレングリコール、1,2-プロピレングリコール、1,3-プロピレングリコール、1,2-ブタンジオール、1,3-ブタンジオール、1,2-プロパンジオール、2-メチル1,3-プロパンジオール、1,4-ブタンジオール、1,5-ペンタンジオール、2,2-ジメチル-1,3-プロパンジオール(ネオペンチルグリコール)、2,2-ジエチル-1,3-プロパンジオール(3,3-ジメチロールペンタン)、2-n-ブチル-2-エチル-1,3プロパンジオール(3,3-ジメチロールヘプタン)、3-メチル-1,5-ペンタンジオール1,6-ヘキサンジオール、2,2,4-トリメチル1,3-ペンタンジオール、2-エチル1,3-ヘキサンジオール、2-メチル1,8-オクタンジオール、1,9-ノナンジオール、1,10-デカンジオール、1,12-オクタデカンジオール等があり、これらのグリコールは、1種または2種以上の混合物として使用される。
(可塑剤)
本発明の位相差フィルムは、本発明の効果を得る上で必要に応じて一般式(2)で表される化合物以外に可塑剤を含有することができる。
但し、R11はn価の有機基、nは2以上の正の整数、OH基はアルコール性、および/またはフェノール性水酸基を表す。
式中、R12は(m1+n1)価の有機基、m1は2以上の正の整数、n1は0以上の整数、COOH基はカルボキシル基、OH基はアルコール性またはフェノール性水酸基を表す。
本発明の位相差フィルムは、紫外線吸収剤を含有することもできる。紫外線吸収剤は400nm以下の紫外線を吸収することで、耐久性を向上させることを目的としており、特に波長370nmでの透過率が10%以下であることが好ましく、より好ましくは5%以下、更に好ましくは2%以下である。
酸化防止剤は劣化防止剤ともいわれ、例えば、フィルム中の残留溶媒のハロゲンやリン酸系可塑剤のリン酸等によりフィルムが分解するのを遅らせたり、防いだりする役割を有するので含有させるのが好ましい。
本発明の位相差フィルムには、取扱性を向上させる為、例えば二酸化ケイ素、二酸化チタン、酸化アルミニウム、酸化ジルコニウム、炭酸カルシウム、カオリン、タルク、焼成ケイ酸カルシウム、水和ケイ酸カルシウム、ケイ酸アルミニウム、ケイ酸マグネシウム、リン酸カルシウム等の無機微粒子や架橋高分子などの微粒子を含有させることが好ましい。中でも二酸化ケイ素がフィルムのヘイズを小さくできるので好ましい。
本発明に用いられる微粒子の分散液を調製する方法としては、例えば以下に示すような3種類が挙げられる。
溶剤と微粒子を攪拌混合した後、分散機で分散を行う。これを微粒子分散液とする。微粒子分散液をドープ液に加えて攪拌する。
溶剤と微粒子を攪拌混合した後、分散機で分散を行う。これを微粒子分散液とする。別に溶剤に少量のセルロースエステルを加え、攪拌溶解する。これに前記微粒子分散液を加えて攪拌する。これを微粒子添加液とする。微粒子添加液をインラインミキサーでドープ液と十分混合する。
溶剤に少量のセルロースエステルを加え、攪拌溶解する。これに微粒子を加えて分散機で分散を行う。これを微粒子添加液とする。微粒子添加液をインラインミキサーでドープ液と十分混合する。
二酸化珪素微粒子を溶剤などと混合して分散する時の二酸化珪素の濃度は5質量%~30質量%が好ましく、10質量%~25質量%が更に好ましく、15~20質量%が最も好ましい。分散濃度は高い方が、添加量に対する液濁度は低くなる傾向があり、ヘイズ、凝集物が良化するため好ましい。
<光学フィルムの製造方法>
次に、本発明の光学フィルムであって、特に位相差フィルムの場合の製造方法について説明する。
尚、Mはウェブまたはフィルムを製造中または製造後の任意の時点で採取した試料の質量で、NはMを115℃で1時間の加熱後の質量である。
式(ii) Rth={(nx+ny)/2-nz}×d
(式中、nxはフィルム面内の遅相軸方向の屈折率であり、nyはフィルム面内の進相軸方向の屈折率であり、nzはフィルムの厚み方向の屈折率であり、dはフィルムの厚さ(nm)である。)
なお、リタデーション値Ro、Rthは、自動複屈折率計を用いて測定することができる。例えば、KOBRA-21ADH(王子計測機器株式会社製)を用いて、温度23℃、湿度55%RHの環境下で、波長が589nmで求めることができる。
<光学フィルムの物性>
本発明の光学フィルムの透湿度は、40℃、90%RHで300~1800g/m2・24hが好ましく、更に400~1500g/m2・24hが好ましく、40~1300g/m2・24hが特に好ましい。透湿度はJIS Z 0208に記載の方法に従い測定することができる。
<偏光板>
本発明の光学フィルムは、偏光板、それを用いた液晶表示装置に使用することができる。
<液晶表示装置>
本発明の偏光板を液晶表示装置に用いることによって、種々の視認性に優れた本発明の液晶表示装置を作製することができる。
<位相差フィルム101の作製>
〈微粒子分散液1〉
微粒子(アエロジル R812 日本アエロジル(株)製)11質量部
エタノール 89質量部
以上をディゾルバーで50分間攪拌混合した後、マントンゴーリンで分散を行った。
メチレンクロライドを入れた溶解タンクに十分攪拌しながら、微粒子分散液1をゆっくりと添加した。更に、二次粒子の粒径が所定の大きさとなるようにアトライターにて分散を行った。これを日本精線(株)製のファインメットNFで濾過し、微粒子添加液1を調製した。
微粒子分散液1 5質量部
下記組成の主ドープ液を調製した。まず加圧溶解タンクにメチレンクロライドとエタノールを添加した。溶剤の入った加圧溶解タンクにアセチル置換度2.00のセルロースエステルを攪拌しながら投入した。これを加熱し、攪拌しながら、完全に溶解し。これを安積濾紙(株)製の安積濾紙No.244を使用して濾過し、主ドープ液を調製した。
メチレンクロライド 340質量部
エタノール 64質量部
セルロースエステル(アセチル置換度2.00) 100質量部
糖エステル化合物1 12質量部
微粒子添加液1 1質量部
以上を密閉されている主溶解釜1に投入し、攪拌しながら溶解してドープ液を調製した。
<位相差フィルム102~126の作製>
以下、表2、3に記載の材料、表4記載の延伸倍率、温度など製造条件変更して、所望のリタデーションに調整し、位相差フィルム102~126を作製した。
下記2種のドープを作製し、共流延によってコア、スキン部分を有する積層位相差フィルム127を作製した。
セルロースエステル(アセチル置換度2.45) 100質量部
トリフェニルフォスフェート 20質量部
下記リタデーション発現剤X 4質量部
下記剥離促進剤 0.03質量部
ジクロロメタン 406質量部
メタノール 61質量部
(スキン層用セルロースエステルドープの調製)
セルロースエステル(アセチル置換度2.89) 100質量部
トリフェニルフォスフェート 12質量部
下記リタデーション発現剤X 4質量部
下記剥離促進剤 0.03質量部
ジクロロメタン 406質量部
メタノール 61質量部
得られた各々の位相差フィルムについて、下記方法で微少光漏れ、湿熱耐久性試験前後のリタデーション値を測定した。更に湿熱耐久性試験前後の内部ヘイズ差を測定した。なお、測定・評価は、特に断りが無い限り、23℃55%RHの雰囲気下で行った。結果を表4に示す。
<微少光漏れの測定>
平均波長550nmの光源を用いて、ほこりや傷のない100μm角試料(23℃、55±3%RHの環境下で24時間調湿した)、ハロゲン光源、バンドパスフィルター(中心波長550nm、半値幅80nm)、下偏光板、回転機構付き波長板、位相差フィルム、20倍対物レンズ、回転式波長板、下上偏光板、CCDカメラ(400万画素)という順に部品が配置された測定装置を用い、2枚の波長板を回転させながら測定し光量変化からピクセル毎のミューラーマトリクスを算出し、その値からRo、φ、Xを算出した。
○:1.5×10-7以上、2.0×10-7未満
△:2.0×10-7以上、2.5×10-7未満
×:2.5×10-7以上
<湿熱耐久性試験前後のリタデーションRo、Rthの測定>
(鹸化処理)
作製した位相差フィルムを40℃の2モル/Lの水酸化カリウム溶液に30秒間浸漬し、次いで水洗し60℃dryのオーブンで5分乾燥して、下記手順でリタデーションを測定し初期値とした。
式(ii) Rth={(nx+ny)/2-nz}×d
(式中、nxはフィルム面内の遅相軸方向の屈折率であり、nyはフィルム面内の進相軸方向の屈折率であり、nzはフィルムの厚み方向の屈折率であり、dはフィルムの厚さ(nm)である。)
なお、リタデーション値Ro、Rthは、KOBRA-21ADH(王子計測機器株式会社製)を用いて、温度23℃、湿度55%RHの環境下で、波長が589nmで測定した。
上記鹸化処理した位相差フィルムを60℃90%RHに設定された恒温槽に入れ、300時間後に取り出し、その後、初期値の測定と同様にリタデーションRo、Rthを測定して湿熱耐久試験前後の変化率を算出した。
◎:0~1%
○:2~3%
×:4%以上
<湿熱耐久性試験前後の内部ヘイズ差>
(鹸化処理条件1)
作製した位相差フィルムを40℃の2モル/Lの水酸化カリウム溶液に30秒間浸漬し、次いで水洗し60℃dryのオーブンで5分乾燥して、下記手順で内部ヘイズを測定し初期値とした。
上記作製した位相差フィルムについて、前述の方法により内部ヘイズ値を測定した。
上記の鹸化処理を行った後、更に位相差フィルムを60℃90%RHに設定された恒温槽に入れ、300時間後に取り出し、その後、初期値の測定と同様に内部ヘイズを測定しその変化量を算出した。
◎:0.00~0.01
○:0.02~0.03
×:0.04以上
<位相差フィルム201、205の作製>
実施例1の位相差フィルム101と同様に製膜したフィルムを、4モル/Lの水酸化カリウム溶液に50℃90秒間浸漬し、次いで水洗し60℃dryのオーブンで5分乾燥し鹸化処理済み位相差フィルムを得た(鹸化処理条件2)。このフィルムを位相差フィルム201とした。
<位相差フィルム202~204、206~211の作製>
表5に記載のセルロースエステルを用いた以外は位相差フィルム201、205と同様にして、上記鹸化条件で各々処理を行った位相差フィルム202~204、206~211を作製した。
実施例1で行った鹸化処理は行わなかった以外は実施例1と同様にして、微少光漏れ、湿熱耐久性試験前後のリタデーションRo、Rthの測定、湿熱耐久性試験前後の内部ヘイズ差の測定を行った。結果を表5に示す。
<位相差フィルム301、302の作製>
実施例1の主ドープの組成を以下のように変更した以外は実施例1と同様に製膜、鹸化処理条件1および2で鹸化処理したフィルムをそれぞれ位相差フィルム301、302として、実施例1と同様な評価を行った。結果を表6に示す。
メチレンクロライド 340質量部
エタノール 64質量部
セルロースエステル(アセチル置換度2.4) 100質量部
糖エステル化合物1 10質量部
一般式(2)で表されるエステル化合物:2-15 3質量部
微粒子添加液1 1質量部
<位相差フィルム401の作製>
糖エステル化合物1にA-1を1.3質量%添加し、A-1成分を2.5%である糖エステル化合物15を作製した。平均置換度がいずれも5.2である。これらの化合物を含む位相差フィルムを、実施例1と同様に製膜、鹸化処理(鹸化処理条件1)したフィルムを位相差フィルム401として、実施例1と同様な評価を行った。結果を表7に示す。
<偏光板の作製>
厚さ、120μmのポリビニルアルコールフィルムを、一軸延伸(温度110℃、延伸倍率5倍)した。
<液晶表示装置の作製>
視野角測定を行う液晶パネルを以下のようにして作製し、液晶表示装置としての特性を評価した。
(視野角の評価)
上記作製した各液晶表示装置について、測定機(EZ-Contrast160D、ELDIM社製)を用いて極角が60°における上下左右方向で、コントラスト比(白透過率/黒透過率)の平均値求めた。
○:20~40未満
×:10~20未満
(液晶表示装置の正面コントラスト)
液晶表示装置について、それぞれの正面コントラストを測定した。正面コントラストの測定は、ELDIM社製の正面コントラスト測定装置(EZ-contrast)により行い、白表示時と黒表示時の光量を測定した。測定結果を、正面コントラストの値によって、下記のように優劣を付けてランク付けを行った。
○:正面コントラスト比=2999:1~2000:1
△:正面コントラスト比=1999:1~1000:1
×:正面コントラスト比=999:1以下
Claims (5)
- 下記一般式(2)で表されるエステル化合物を含有することを特徴とする請求項1に記載の位相差フィルム。
一般式(2) B-(G-A)n-G-B
(式中、Bはヒドロキシ基またはカルボン酸残基、Gは炭素数2~12のアルキレングリコール残基または炭素数6~12のアリールグリコール残基または炭素数が4~12のオキシアルキレングリコール残基、Aは炭素数4~12のアルキレンジカルボン酸残基または炭素数6~12のアリールジカルボン酸残基を表す。nは1以上の整数を表す。) - 一般式(1)で示される化合物の置換度8.0である成分の含有質量比率が2%以下であることを特徴とする請求項1または2に記載の位相差フィルム。
- 請求項1~3のいずれか1項に記載の位相差フィルムを偏光子の少なくとも一方の面に用いたことを特徴とする偏光板。
- 請求項4に記載の偏光板を液晶セルの少なくとも一方の面に用いたことを特徴とする液晶表示装置。
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JP2013202829A (ja) * | 2012-03-27 | 2013-10-07 | Konica Minolta Inc | セルロースアシレート積層フィルムおよびその製造方法、並びにそれを用いた偏光板および液晶表示装置 |
JP2013245209A (ja) * | 2012-05-29 | 2013-12-09 | Dai Ichi Kogyo Seiyaku Co Ltd | エステル化化合物の製造方法 |
JP2017072775A (ja) * | 2015-10-09 | 2017-04-13 | コニカミノルタ株式会社 | 位相差フィルム、偏光板および液晶表示装置 |
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JP5996516B2 (ja) * | 2013-11-29 | 2016-09-21 | 住友化学株式会社 | 偏光子及びそれを含む偏光板 |
JP2016206540A (ja) * | 2015-04-27 | 2016-12-08 | コニカミノルタ株式会社 | 位相差フィルム、偏光板、垂直配向型液晶表示装置及び位相差フィルムの製造方法 |
TWI826607B (zh) | 2018-12-07 | 2023-12-21 | 美商思娜公司 | 顯示系統、空間光調變器系統及顯示系統的形成方法 |
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KR101440738B1 (ko) | 2014-09-17 |
US8652591B2 (en) | 2014-02-18 |
TW201221570A (en) | 2012-06-01 |
US20130135565A1 (en) | 2013-05-30 |
CN103080787A (zh) | 2013-05-01 |
TWI504654B (zh) | 2015-10-21 |
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