WO2014017541A1 - 偏光板及び液晶表示装置 - Google Patents
偏光板及び液晶表示装置 Download PDFInfo
- Publication number
- WO2014017541A1 WO2014017541A1 PCT/JP2013/070056 JP2013070056W WO2014017541A1 WO 2014017541 A1 WO2014017541 A1 WO 2014017541A1 JP 2013070056 W JP2013070056 W JP 2013070056W WO 2014017541 A1 WO2014017541 A1 WO 2014017541A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- film
- protective film
- polarizing plate
- thickness
- ene
- Prior art date
Links
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
-
- 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
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
-
- G02B1/105—
-
- 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
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/14—Protective coatings, e.g. hard coatings
-
- 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
- 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
- G02F1/13356—Structural association of cells with optical devices, e.g. polarisers or reflectors characterised by the placement of the optical elements
- G02F1/133565—Structural association of cells with optical devices, e.g. polarisers or reflectors characterised by the placement of the optical elements inside the LC elements, i.e. between the cell substrates
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
- Y10T428/269—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension including synthetic resin or polymer layer or component
Definitions
- the present invention relates to a polarizing plate and a liquid crystal display device.
- Liquid crystal display devices consume less power and are increasingly used year by year as space-saving image display devices.
- a liquid crystal display device has a major drawback that the viewing angle dependency of a display image is large.
- a wide viewing angle liquid crystal mode such as a VA mode and an IPS mode has been put into practical use.
- the demand for liquid crystal display devices is rapidly expanding even in the market where such images are required.
- liquid crystal display devices are required to have a large size and high quality texture.
- a bezel at the periphery of the screen, and this width is becoming narrower in order to achieve a high quality texture.
- the bezel has the role of aesthetically finishing the display by concealing the edge of the polarizing plate, but as the bezel becomes narrower, a higher level of accuracy is required for the bonding accuracy between the liquid crystal cell and the polarizing plate. It was.
- a polarizing plate used in a liquid crystal display device is generally composed of a polarizer made of a polyvinyl alcohol film or the like on which iodine or dye is adsorbed and oriented, and a transparent protective film (polarizing plate protective film) on both sides of the polarizer. It has a configuration.
- a polarizing plate protective film a cellulose acylate type polarizing plate protective film typified by cellulose acetate is widely used because it has high transparency and can easily ensure adhesion with polyvinyl alcohol used in a polarizer. I came. Adhesion is generally obtained by saponifying the protective film to impart hydrophilicity to the surface.
- a synthetic polymer film is also used as the polarizing plate protective film.
- Patent Document 1 discloses a polarizing plate having a cycloolefin polymer film on one side of the polarizer and a cellulose acylate film on the other side as a protective film for the polarizer.
- Patent Document 2 discloses a polarizing plate having an acrylic film on one side of the polarizer and a cellulose acylate film on the other side as a protective film for the polarizer.
- Patent Document 3 discloses a polarizing plate having an acrylic film, a polyimide film, or a norbornene film on one side of a polarizer and a cellulose acylate film on the other side as a protective film for the polarizer. Yes.
- a film containing a synthetic polymer such as a cycloolefin-based polymer has a property of having a low water absorption and a small photoelastic coefficient with respect to a cellulose acylate film. Therefore, when a synthetic polymer film is used as a polarizing plate protective film, unevenness in photoelasticity is suppressed, but moisture is not dried when a polarizing plate is produced by a conventional method using polyvinyl alcohol paste. There was a problem that the polarization performance deteriorated.
- the polarizing plate of Patent Document 1 has a structure having a cycloolefin polymer on one side of the polarizer and a cellulose acylate film on the other side as a protective film for the polarizer, drying after the production of the polarizing plate is sufficient. It is considered that the characteristics of the cycloolefin polymer can be utilized.
- the polarizing plate of Patent Document 1 has a cellulose acylate film on the flat plate side (lower side) and a cycloolefin polymer film on the upper side.
- the warp (curl) of the polarizing plate is observed, curling may occur so that the four corners of the polarizing plate are lifted. Such a curl is called a “minus curl”.
- a negatively curled polarizing plate is attached to a liquid crystal cell using a cycloolefin polymer film as an inner side film, air bubbles enter between the inner side film and the liquid crystal cell, resulting in a decrease in the performance of the liquid crystal display device. There is.
- an inner side film refers to the film arrange
- a protective film having a thickness of 60 ⁇ m or more is used, but in recent years, a protective film having a thinner film has been demanded. Further, when the protective film is thin, there is a problem that curling is more likely to occur.
- An object of the present invention is to provide a polarizing plate which is excellent in polarizing plate processing suitability and excellent in manufacturing suitability of a liquid crystal display device from the viewpoint of curling even if it is a thin film.
- the curl in the polarizing plate using a synthetic polymer film having a thickness of 30 ⁇ m or less as the first protective film on one side of the polarizer is the second side on the other side of the polarizer.
- the thickness greatly changed depending on the thickness, elastic modulus, and humidity dimensional change rate of the protective film.
- it was found that the curl is small when a film having a high elastic modulus and at the same time a high humidity dimensional change rate is used for a synthetic polymer film having a low elastic modulus and a low humidity dimensional change rate. This cannot be explained only by the loss of the balance of elastic modulus, which is estimated to be the cause of curling in Patent Document 1.
- the polarizing plate As a result of investigations based on this concept, it was found that curling can be reduced by setting the relationship between the elastic modulus in the TD direction, the thickness, and the humidity dimensional change rate in the TD direction within a specific range as the second protective film. It was. That is, as a protective film for a polarizer, in a polarizing plate having a first protective film including a synthetic polymer film on one side of the polarizer and a second protective film on the other side, the polarizing plate is a cross-sectional view thereof.
- a polarizing plate having a first protective film, a polarizer, and a second protective film in this order The first protective film is a film comprising a synthetic polymer, has a thickness of 30 ⁇ m or less, an elastic modulus in the TD direction of 2 GPa to 2.5 GPa, and is represented by the following formula (1)
- Direction humidity dimensional change rate is 0.1% or less
- TD direction humidity dimensional change rate (%) [ ⁇ (film length in TD direction at 25 ° C., 80% relative humidity) ⁇ (film length in TD direction at 25 ° C., 10% relative humidity) ⁇ / (25 TD, film length in TD direction at 60% relative humidity)] ⁇ 100
- Evaluation value Elastic modulus (GPa) in the TD direction of the second protective film / humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (thickness ( ⁇ m) of the second protective film / first Protective film thickness ( ⁇ m)) 2 ⁇ ⁇ (30 / polarizer thickness ( ⁇ m)) ⁇ 1/2 [2]
- a polarizing plate having a first protective film, a polarizer, and a second protective film in this order
- the first protective film is a film comprising a synthetic polymer, has a thickness of 30 ⁇ m or less, and has an elastic modulus in the TD direction of 2.0 GPa to 2.5 GPa
- the polarizer has a thickness of 20 ⁇ m
- the polarizing plate in which the second protective film has an evaluation value A represented by the following formula (2 ′) of 5.7 to 9.0.
- Evaluation value A Elastic modulus (GPa) in the TD direction of the second protective film / Humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (Thickness ( ⁇ m) of the second protective film / First Protective film thickness ( ⁇ m)) 2 [7]
- the first protective film is a film comprising a synthetic polymer, has a thickness of 30 ⁇ m or less, and has an elastic modulus in the TD direction of 2.0 GPa to 2.5 GPa,
- the polarizer has a thickness of 25 ⁇ m
- the polarizing plate in which the second protective film has an evaluation value A represented by the following formula (2 ′) of 6.5 to 10.0.
- Evaluation value A Elastic modulus (GPa) in the TD direction of the second protective film / Humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (Thickness ( ⁇ m) of the second protective film / First Protective film thickness ( ⁇ m)) 2 [8]
- the first protective film is a film comprising a synthetic polymer, has a thickness of 30 ⁇ m or less, and has an elastic modulus in the TD direction of 2.0 GPa to 2.5 GPa,
- the polarizer has a thickness of 30 ⁇ m
- the polarizing plate in which the second protective film has an evaluation value A represented by the following formula (2 ′) of 7.0 to 11.0.
- Evaluation value A Elastic modulus (GPa) in the TD direction of the second protective film / Humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (Thickness ( ⁇ m) of the second protective film / First Protective film thickness ( ⁇ m)) 2 [9]
- a liquid crystal display device comprising a liquid crystal cell and at least one polarizing plate according to any one of [1] to [8], wherein the first protective film in the polarizing plate is disposed on the liquid crystal cell side. Arranged liquid crystal display device.
- a polarizing plate which is excellent in polarizing plate processing suitability and excellent in manufacturing suitability of a liquid crystal display device from the viewpoint of curling even if it is a thin film.
- the polarizing plate of the present invention is a polarizing plate having a first protective film, a polarizer, and a second protective film in this order
- the first protective film is a film comprising a synthetic polymer, has a thickness of 30 ⁇ m or less, an elastic modulus in the TD direction of 2 GPa to 2.5 GPa, and is represented by the following formula (1)
- Direction humidity dimensional change rate is 0.1% or less
- the second protective film is a polarizing plate having an evaluation value represented by the following formula (2) of 7.0 to 11.0.
- TD direction humidity dimensional change rate (%) [ ⁇ (film length in TD direction at 25 ° C., 80% relative humidity) ⁇ (film length in TD direction at 25 ° C., 10% relative humidity) ⁇ / (25 TD, film length in TD direction at 60% relative humidity)] ⁇ 100
- Evaluation value Elastic modulus (GPa) in the TD direction of the second protective film / humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (thickness ( ⁇ m) of the second protective film / first Protective film thickness ( ⁇ m)) 2 ⁇ ⁇ (30 / polarizer thickness ( ⁇ m)) ⁇ 1/2
- a TD direction is a direction orthogonal to the film conveyance direction (MD direction) at the time of film manufacture.
- MD direction film conveyance direction
- the direction perpendicular to the absorption axis of the polarizer is usually the TD direction.
- the polarizing plate of the present invention has a first protective film, a polarizer, and a second protective film in this order.
- An example of the polarizing plate of the present invention is shown in FIG.
- the polarizing plate 10 in FIG. 1 has the 1st protective film 1, the polarizer 3, and the 2nd protective film 2 in this order.
- the polarizer and the protective film constituting the polarizing plate of the present invention will be described.
- polarizer there is no restriction
- Polyvinyl alcohol resin As the polyvinyl alcohol-based resin (hereinafter also referred to as “PVA”), a polymer material obtained by saponifying polyvinyl acetate is preferable.
- PVA polyvinyl alcohol-based resin
- vinyl acetate such as unsaturated carboxylic acid, unsaturated sulfonic acid, olefins, and vinyl ethers can be used. You may contain the component which can be copolymerized.
- modified PVA containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group, or the like can also be used.
- the polarizer in the present invention includes a PVA film having a 1,2-glycol bond amount of 1.5 mol% or less described in Japanese Patent No. 3021494, and Japanese Patent Application Laid-Open No. 2001-316492.
- PVA film having 500 ⁇ m or less of optical foreign matters of 5 ⁇ m or more per 100 cm 2 and PVA film having hot water cutting temperature spots in the TD direction of 1.5 ° C. or less of the film described in JP-A No.
- the saponification degree of the polyvinyl acetate is not particularly limited.
- the saponification degree is preferably 90% or more, more preferably 95% or more, and particularly preferably 99% or more.
- the weight average molecular weight of the polyvinyl alcohol resin used for the polarizer in the present invention is not particularly limited, but is preferably 100,000 to 300,000, more preferably 140000 to 260000, and more preferably 150,000 to 200,000. Particularly preferred.
- the polarizer in the present invention preferably contains a dichroic dye.
- the dichroic dye refers to a dye having a different absorbance depending on the direction, and includes, for example, iodine ions, diazo dyes, quinone dyes, and other known dichroic dyes. It is.
- I 3 - and I 5 - can be preferably used an iodine ion or a dichroic dye higher such.
- higher-order iodine ions are particularly preferably used. Higher-order iodine ions can be found in “Applications of Polarizing Plates” by Ryo Nagata, CMC Publishing and Industrial Materials, Vol. 28, No.
- PVA is immersed in at least one of a solution obtained by dissolving iodine in a potassium iodide aqueous solution and a boric acid aqueous solution, and can be produced in a state of being adsorbed and oriented in PVA.
- the method for producing a polarizer in the present invention includes a step of forming a polyvinyl alcohol resin solution containing a polyvinyl alcohol resin into a film, a step of stretching the polyvinyl alcohol resin film, and two colors. It is preferable to include a step of dyeing the polyvinyl alcohol-based resin film after stretching with a functional dye.
- the manufacturing method of the polarizer in the order of the preparation process of the PVA resin solution, the casting process, the swelling process, the dyeing process, the hardening process, the stretching process, and the drying process.
- an on-line surface inspection process may be provided during or after the aforementioned process.
- Preparation of PVA resin solution In the step of preparing the PVA resin solution, it is preferable to prepare a stock solution in which the PVA resin is added to water or an organic solvent by adding the PVA resin while stirring with respect to water.
- concentration of the polyvinyl alcohol resin in the stock solution is preferably 5 to 20% by mass.
- the obtained slurry may be dehydrated to once prepare a polyvinyl alcohol resin wet cake having a water content of about 40%.
- steam from the tank bottom is preferable, for example.
- the internal resin temperature is preferably 50 to 150 ° C., and the inside of the system may be pressurized.
- a method of casting the PVA resin solution stock solution prepared above to form a film is generally preferably used.
- the casting method is not particularly limited, but the heated PVA-based resin solution stock solution is supplied to a biaxial extruder and is supported by a gear pump from discharge means (preferably a die, more preferably a T-type slit die). It is preferable to form a film by flowing upward.
- discharge means preferably a die, more preferably a T-type slit die.
- the support is preferably a cast drum, and the drum diameter, width, rotation speed, and surface temperature are not particularly limited.
- the diameter (R1) of the cast drum is preferably 2000 to 5000 mm, particularly preferably 2500 to 4500 mm, and particularly preferably 3000 to 3500 mm.
- the width of the cast drum is preferably 2 to 6 m, particularly preferably 3 to 5 m, and particularly preferably 4 to 5 m.
- the rotation speed of the cast drum is preferably 2 to 20 m / min, particularly preferably 4 to 12 m / min, and particularly preferably 5 to 10 m / min.
- the cast drum surface temperature of the cast drum is preferably 40 to 140 ° C., particularly preferably 60 to 120 ° C., and particularly preferably 80 to 100 ° C.
- the resin temperature at the exit of the T-shaped slit die is preferably 40 to 140 ° C., particularly preferably 60 to 120 ° C., and particularly preferably 80 to 100 ° C. Thereafter, it is preferable to perform drying while alternately passing the back and front surfaces of the obtained roll through the drying roll.
- the diameter (R2) of the drying roll is preferably 200 to 450 mm, particularly preferably 250 to 400 mm, and particularly preferably 300 to 350 mm.
- the length of the obtained film It can be set as a long film of 2000 m or more, Preferably it is 4000 m or more.
- the width of the film is not particularly limited, but is preferably 2 to 6 m, and more preferably 3 to 5 m.
- the swelling step is preferably performed only with water. However, as described in JP-A-10-153709, the optical performance is stabilized and wrinkle generation of the polyvinyl alcohol-based resin film on the production line is avoided. Therefore, the degree of swelling of the polarizing plate substrate can be controlled by swelling the polyvinyl alcohol-based resin film with an aqueous boric acid solution.
- the temperature and time of the swelling step can be arbitrarily determined, but are preferably 10 ° C. to 60 ° C. and 5 seconds to 2000 seconds. Note that the film may be slightly stretched during the swelling step. For example, an aspect of stretching 1.05 times to 1.5 times is preferable, and an aspect of stretching about 1.3 times is more preferable.
- the method described in JP-A-2002-86554 can be used. Further, as a dyeing method, not only immersion but any means such as application or spraying of iodine or a dye solution can be used. Further, as described in JP-A-2002-290025, iodine concentration, dyeing bath temperature, stretching ratio in the bath, and a method of dyeing while stirring the bath liquid in the bath may be used.
- iodine ions when higher-order iodine ions are used as the dichroic dye, in order to obtain a high-contrast polarizing plate, it is preferable to use a solution in which iodine is dissolved in a potassium iodide aqueous solution in order to obtain a high-contrast polarizing plate.
- a solution in which iodine is dissolved in a potassium iodide aqueous solution in order to obtain a high-contrast polarizing plate.
- the embodiment described in JP-A-2007-086748 can be used.
- boron compounds such as boric acid and borax may be added to the dyeing solution.
- the hardening step it is preferable to immerse the PVA film in a crosslinking agent solution or apply the solution to include a crosslinking agent. Further, as described in JP-A-11-52130, the hardening process can be performed in several steps.
- the crosslinking agent those described in US Pat. No. 2,328,977 can be used, and as described in Japanese Patent No. 3357109, a polyhydric aldehyde is used as a crosslinking agent in order to improve dimensional stability. Although it can be used, boric acids are most preferably used.
- metal ions may be added to the boric acid-potassium iodide aqueous solution.
- Zinc chloride is preferred as the metal ion, but as described in JP 2000-35512 A, zinc halides such as zinc iodide, zinc sulfates such as zinc acetate, and zinc salts such as zinc acetate are used instead of zinc chloride. It can also be used.
- a boric acid-potassium iodide aqueous solution to which zinc chloride is added may be prepared, and a PVA film may be dipped to perform hardening, and the method described in JP-A-2007-086748 can be used.
- the stretching step preferably uses a longitudinal uniaxial stretching method as described in US Pat. No. 2,454,515 or the like, or a tenter method as described in JP-A-2002-86554. Can do.
- the preferred draw ratio is 2 to 12 times, more preferably 3 to 10 times. The relationship between the draw ratio, the thickness of the original fabric and the thickness of the polarizer is described in JP-A No.
- drying step a method known in JP-A-2002-86554 can be used, but a preferable temperature range is 30 ° C. to 100 ° C., and a preferable drying time is 30 seconds to 60 minutes.
- heat treatment is performed such that the fading temperature in water is 50 ° C. or higher, or as described in Japanese Patent Laid-Open Nos. 07-325215 and 07-325218.
- aging in a temperature and humidity controlled atmosphere can be preferably performed.
- a thin polarizer can be formed by a manufacturing method using a coating method described in Japanese Patent No. 4691205 and Japanese Patent No. 4751481.
- control of a film thickness can be controlled by a well-known method, for example, it can control by setting the die slit width in the said casting process, and extending
- the thickness of the polarizer is not particularly limited, but is preferably 5 ⁇ m or more and 30 ⁇ m or less, and more preferably 10 ⁇ m or more and 20 ⁇ m or less from the viewpoint of the degree of polarization and warpage. If the film thickness of a polarizer is 30 micrometers or less, since the contraction force of a polarizer does not increase and the curvature of the liquid crystal panel which bonded this does not become large, it is preferable. On the other hand, if the thickness of the polarizer is 5 ⁇ m or more, it is preferable because the light of one polarized light passing through the polarizer can be sufficiently absorbed and the degree of polarization does not decrease.
- the protective film (also referred to as “polarizing plate protective film”) used for the polarizing plate of the present invention will be described.
- the polarizing plate of the present invention has a first protective film, a polarizer, and a second protective film in this order.
- the first protective film is a film comprising a synthetic polymer, has a thickness of 30 ⁇ m or less, an elastic modulus in the TD direction of 2 GPa to 2.5 GPa, and is represented by the following formula (1)
- the humidity dimensional change rate in the direction is 0.1% or less.
- TD direction humidity dimensional change rate (%) [ ⁇ (film length in TD direction at 25 ° C., 80% relative humidity) ⁇ (film length in TD direction at 25 ° C., 10% relative humidity) ⁇ / (25 TD, film length in TD direction at 60% relative humidity)] ⁇ 100
- the second protective film has an evaluation value represented by the following formula (2) of 7.0 to 11.0.
- Evaluation value Elastic modulus (GPa) in the TD direction of the second protective film / humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (thickness ( ⁇ m) of the second protective film / first Protective film thickness ( ⁇ m)) 2 ⁇ ⁇ (30 / polarizer thickness ( ⁇ m)) ⁇ 1/2
- the first protective film is a film comprising a synthetic polymer.
- the synthetic polymer is preferably a cycloolefin polymer such as norbornene, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, polyarylate, polysulfone, (meth) acrylic resin, (meth) acrylic resin, cycloolefin. From the viewpoint of stability against humidity, a cycloolefin polymer is most preferable.
- the cycloolefin polymer is preferably a cyclic olefin addition polymer containing a structural unit (a) represented by the following general formula (1) and a structural unit (b) represented by the following general formula (2) in an appropriate ratio. .
- a 1 , A 2 , A 3 and A 4 in the general formula (1) are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group, a cycloalkyl group having 4 to 15 carbon atoms, or a halogen atom. It is.
- a 1 to A 4 also include an alkylene group formed from A 1 and A 2 , A 1 and A 3, or A 2 and A 4 .
- r represents an integer of 0-2.
- Such a structural unit (a) is formed by addition polymerization of a cyclic olefin compound represented by the following general formula (3) (hereinafter referred to as “specific monomer (1)”).
- [A 1 , A 2 , A 3 and A 4 in the general formula (3) are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group, a cycloalkyl group having 4 to 15 carbon atoms, a halogen atom, Is an atom.
- a 1 to A 4 also include alkylene groups and alkylidene groups formed from A 1 and A 2 , A 1 and A 3, or A 2 and A 4 .
- r represents an integer of 0-2.
- Specific examples of the “specific monomer (1)” represented by the general formula (3) include bicyclo [2.2.1] hept-2-ene, 5-methyl-bicyclo [2.2.1]. ] Hept-2-ene, 5-ethyl-bicyclo [2.2.1] hept-2-ene, 5-propyl-bicyclo [2.2.1] hept-2-ene, 5-butyl-bicyclo [2] 2.1] hept-2-ene, 5-pentyl-bicyclo [2.2.1] hept-2-ene, 5-hexyl-bicyclo [2.2.1] hept-2-ene, 5-heptyl -Bicyclo [2.2.1] hept-2-ene, 5-octyl-bicyclo [2.2.1] hept-2-ene, 5-decyl-bicyclo [2.2.1] hept-2-ene , 5-dodecyl-bicyclo [2.2.1] hept-2-ene, 5,6-dimethyl-bic
- hept-2-ene 5-methyl-5-ethyl-bicyclo [2.2.1] hept-2-ene, 5-phenyl-bicyclo [2.2.1] hept-2-ene, 5 Cyclohexyl-bicyclo [2.2.1] hept-2-ene, 5-cyclooctyl-bicyclo [2.2.1] hept-2-ene, 5-fluoro-bicyclo [2.2.1] hept-ene 2-ene, 5-chloro-bicyclo [2.2.1] hept-2-ene, tricyclo [4.2.0.1 5,8 ] non-2-ene, 1-methyltricyclo [4.2 .0.1 5,8] non-2-ene, 6-methyl tricyclo [4.2.0.1 5,8] non-2-ene, tricyclo [5.2.1.0 2, 6] dec-8-ene, 3-methyl-tricyclo [5.2.1.0 2, 6] dec-8-ene, 4-methyl-tricyclo [5.2.
- dec-8-ene tricyclo [6.2.1.0 2, 7] undec-9-ene, 1-methyl-tricyclo [6.2.1.0 2, 7] undec - 9-ene, 3-methyltricyclo [6.2.1.0 2,7 ] undec-9-ene, 1-ethyltricyclo [6.2.1.0 2,7 ] undec-9-ene, 3-ethyltricyclo [6.2.1.0 2,7 ] undec-9-ene, tricyclo [8.2.1.0 2,9 ] tridec-11-ene, 1-methyltricyclo [8.
- 5-vinyl-bicyclo [2.2.1] hept-2-ene, 5- (1-butenyl) -bicyclo [2.2.1] hept-2-ene, tricyclo [5.2.1. 0 2,6 ] deca-3,8-diene, 1-methyltricyclo [5.2.1.0 2,6 ] deca-3,8-diene, 1-ethyltricyclo [5.2.1. 0 2,6 ] deca-3,8-diene and other cyclic diolefin compounds are subjected to addition polymerization, and then the cyclic olefinically unsaturated bond present in the side chain is hydrogenated to obtain the structural unit (a) It can be.
- the endo-form content is preferably 80% or more.
- the cyclic olefin polymer obtained by using these is not only excellent in transparency and heat resistance, but also becomes a polymer having low water absorption, low dielectric property, and high toughness.
- the “specific monomer (1)” can be used alone or in combination of two or more.
- the structural unit (b) represented by the following general formula (2) undergoes addition polymerization of a cyclic olefin represented by the following general formula (4) (hereinafter referred to as “specific monomer (2)”). Is formed.
- B 1 to B 4 are each independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a halogenated alkyl group, a hydrolyzable silyl group, or — (CH 2 ).
- j represents a polar group represented by X, and at least one of B 1 to B 4 contains a hydrolyzable silyl group or a polar group represented by — (CH 2 ) j X.
- X is —C (O) OR 1 or —OC (O) R 2
- R 1 and R 2 are each an alkyl group, alkenyl group, cycloalkyl group, aryl group having 1 to 10 carbon atoms, or A substituent selected from the group consisting of these halogen substituents
- j is an integer of 0 to 3.
- B 1 to B 4 also include an alkylene group formed from B 1 and B 3 or B 2 and B 4 , and an alkylidenyl group formed from B 1 and B 2 or B 3 and B 4 .
- r represents an integer of 0-2.
- B 1 to B 4 are the same as in the general formula (2).
- r represents an integer of 0-2.
- Specific examples of such “specific monomer (2)” include, for example, the following compounds, but the present invention is not limited to these specific examples.
- the proportion of the structural unit (b) contained in the cyclic olefin polymer that can be used in the present invention is from 30 to 99 mol%, preferably from 40 to 95 mol%, more preferably from 50 to 90 mol, based on all structural units. %.
- the proportion of the structural unit (b) of the cyclic olefin polymer is in the above range, the adhesion and adhesion with the polyvinyl alcohol used in the polarizer is good, and the hygroscopicity is not increased and the dimension is stable. Excellent in properties.
- the arrangement of the structural units (b) is not limited in the cyclic olefin polymer, such as random or block, but is preferably random.
- the cyclic olefin addition polymer containing the structural unit (b) having a reactive substituent such as a hydrolyzable silyl group, an ester group, an acryloyl group, or a methacryloyl group as a side chain substituent uses a crosslinking agent described later.
- a reactive substituent such as a hydrolyzable silyl group, an ester group, an acryloyl group, or a methacryloyl group as a side chain substituent.
- a structural unit (c) obtained by addition polymerization of a “specific ⁇ -olefin compound” can be further introduced.
- specific ⁇ -olefin compound examples include ethylene, propylene, 1-butene, 1-hexene, 1-octene, trimethylsilylethylene, triethylsilylethylene, styrene, and the like. is there.
- the glass transition temperature of the cyclic olefin polymer that can be used in the present invention can be controlled.
- the proportion of the repeating unit (c) contained in the cyclic olefin polymer that can be used in the present invention is 0 to 30 mol%, preferably 0 to 20 mol%.
- the glass transition temperature of the cyclic olefin polymer that can be used in the present invention is not lower than 170 ° C. and the heat resistance is not lowered when the ratio of the repeating unit (c) is in the above range.
- the molecular weight of the cyclic olefin polymer that can be used in the present invention is expressed in terms of polystyrene, the number average molecular weight is preferably 10,000 to 300,000, and the weight average molecular weight is preferably 20,000 to 700,000, More preferably, the number average molecular weight is 20,000 to 200,000, the weight average molecular weight is 50,000 to 500,000, still more preferably the number average molecular weight is 50,000 to 150,000, and the weight average molecular weight is 100,000 to 300,000.
- the film has excellent toughness and is difficult to break when made into a film, and the solution viscosity does not increase, and the workability of film formation by the solution casting method and the obtained film The surface is good.
- the glass transition temperature of the cyclic olefin polymer that can be used in the present invention is 180 to 450 ° C., preferably 200 to 400 ° C. in an uncrosslinked state.
- the glass transition temperature of the polymer is in the above range, the heat resistance is sufficient, and the film has excellent toughness and is difficult to break.
- the cyclic olefin polymer that can be used in the present invention is mainly composed of the “specific monomer (1)” and, if necessary, a “specific monomer (2) for crosslinking formation or adhesion / adhesion imparting. ) ”And, if necessary, for the control of the glass transition temperature, it is produced using“ specific ⁇ -olefin compound ”.
- the manufacturing method will be described.
- a polymerization catalyst As a polymerization catalyst, [1] a single complex catalyst such as Pd and Ni, [2] a multi-component catalyst comprising a combination of a palladium complex having a ⁇ or ⁇ , ⁇ bond and an organic aluminum or a super strong acid salt, [3] 1 A transition metal compound selected from nickel compounds, cobalt compounds, titanium compounds or zirconium compounds, 2) a compound selected from superacids, Lewis acids and ionic boron compounds, and 3) a multicomponent catalyst comprising an organoaluminum compound.
- the present invention is not limited to these examples.
- These polymerization catalysts are described in [0132] to [0139] of JP-T-2008-529038 and can also be referred to in the present invention.
- Transition metal compounds such as nickel compounds, palladium compounds, cobalt compounds, titanium compounds and zirconium compounds are used in an amount of 0.02 to 100 millimole atoms per mole of monomer, and organoaluminum compounds are used per mole of transition metal compound.
- the amount of the super strong acid, Lewis acid, and ionic boron compound is preferably 0 to 100 mol per 1 mol atom of the transition metal compound.
- the cyclic olefin-based polymer that can be used in the present invention uses a single complex catalyst or a multi-component catalyst composed of the above components, an alicyclic hydrocarbon solvent such as cyclohexane, cyclopentane, methylcyclopentane, hexane, heptane. , Aliphatic hydrocarbon solvents such as octane, aromatic hydrocarbon solvents such as toluene, benzene, xylene, mesitylene, halogenated dichloromethane, 1,2-dichloroethane, 1,1-dichloroethane, tetrachloroethane, chlorobenzene, dichlorobenzene, etc. It can be obtained by polymerization in a temperature range of ⁇ 20 to 120 ° C. in a solvent selected from one or more hydrocarbon solvents.
- cycloolefin ring-opening polymer As the cycloolefin polymer that can be used in the present invention, a ring-opening polymer having monomer units of the following general formulas (5) and (6) can also be preferably used.
- R 1 to R 4 each independently represents a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom which may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom, 1 Represents 30 hydrocarbon groups; or polar groups.
- R 1 and R 2 , R 3 and R 4 or R 2 and R 3 are bonded to each other to form a carbocyclic or heterocyclic ring having a monocyclic structure or other ring condensed to form a polycyclic structure.
- the formed carbocyclic or heterocyclic ring may be an aromatic ring or a non-aromatic ring.
- Y represents a vinylene group (—CH ⁇ CH—) or an ethylene group (—CH 2 CH 2 —), and R 5 to R 8 each independently represents a hydrogen atom; a halogen atom A substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom; or a polar group.
- R 5 and R 6 , R 7 and R 8 or R 6 and R 7 are bonded to each other, and a carbocyclic or heterocyclic ring having a polycyclic structure by condensing a monocyclic structure or another ring (provided that (Except for the structure represented by the general formula (5)), and the formed carbocyclic or heterocyclic ring may be an aromatic ring or a non-aromatic ring.
- the polymers of the general formulas (5) and (6) are synthesized as (co) polymers of monomers (hereinafter also referred to as “specific polymers”) shown in the following (a) to (d).
- A A ring-opening polymer of a compound represented by the following general formula (7) (hereinafter also referred to as “specific monomer d”).
- B A ring-opening polymer of the specific monomer d and a compound copolymerizable with the specific monomer d (hereinafter also referred to as “copolymerizable monomer”).
- C A hydrogenated product of the above ring-opening polymer (a) or (b) the ring-opening polymer.
- D A compound obtained by cyclization of the ring-opened polymer of (a) or (b) by a Friedel-Craft reaction or a hydrogenated product thereof.
- m is an integer of 1 or more
- p is 0 or an integer of 1 or more
- R 1 to R 4 are each independently a hydrogen atom; a halogen atom; an oxygen atom, a nitrogen atom, sulfur.
- R 1 and R 2 , R 3 and R 4 or R 2 and R 3 are bonded to each other to form a carbocyclic or heterocyclic ring having a monocyclic structure or other ring condensed to form a polycyclic structure.
- the formed carbocyclic or heterocyclic ring may be an aromatic ring or a non-aromatic ring.
- the specific polymer uses a compound represented by the following general formula (8) as a copolymerizable monomer (hereinafter also referred to as “specific monomer e”), a specific monomer d and a specific monomer. It is preferable that it is obtained by copolymerizing the body e. According to the specific polymer having such a configuration, the finally obtained specific retardation film has more excellent mechanical properties such as toughness, and is required for the specific retardation film by stretching. It becomes easy to obtain a desired phase difference.
- R 5 to R 8 each independently represents a hydrogen atom; a halogen atom; an optionally substituted group that does not contain a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom.
- R 5 and R 6 , R 7 and R 8 or R 6 and R 7 are bonded to each other, and a monocyclic structure or other ring is condensed with a carbocyclic or heterocyclic ring having a polycyclic structure (provided that (Except for the structure represented by the general formula (5)), and the formed carbocyclic or heterocyclic ring may be an aromatic ring or a non-aromatic ring. ]
- the specific polymer is a ring-opening polymer of the specific monomer d and the specific monomer e, and is a structural unit derived from the specific monomer d represented by the general formula (5) (hereinafter referred to as “the structural unit”). And a structural unit derived from the specific monomer e represented by the general formula (6) (hereinafter also referred to as “structural unit e”). It is preferable.
- the specific polymer having such a configuration is preferable in that a balance between heat resistance and heat processability by stretching or the like can be achieved.
- Examples of the halogen atom in the general formulas (5) to (8) include a fluorine atom, a chlorine atom, and a bromine atom.
- Examples of the hydrocarbon group having 1 to 30 carbon atoms include alkyl groups such as methyl, ethyl and propyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; alkenyl groups such as vinyl, allyl and propenyl Etc.
- the substituted or unsubstituted hydrocarbon group in the general formula (5) to the general formula (8) may be directly bonded to the ring structure or may be bonded via a linking group.
- the linking group include a divalent hydrocarbon group having 1 to 10 carbon atoms [for example, an alkylene group represented by — (CH 2 ) q — (wherein q is an integer of 1 to 10)]; oxygen A linking group containing an atom, nitrogen atom, sulfur atom or silicon atom [for example, a carbonyl group (—CO—), an oxycarbonyl group (—O (CO) —), a sulfone group (—SO 2 —), an ether bond (— O—), thioether bond (—S—), imino group (—NH—), amide bond (—NHCO—, —CONH—), siloxane bond (—OSi (R 9 ) 2 — (where R 9 is Alkyl groups such as methyl and ethyl)
- Examples of the polar group include a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group, an amide group, an imide ring-containing group, a triorganosiloxy group, a triorganosilyl group, and an amino group.
- examples of the alkoxy group include a methoxy group and an ethoxy group; examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group; examples of the aryloxycarbonyl group include Examples thereof include phenoxycarbonyl group, naphthyloxycarbonyl group, fluorenyloxycarbonyl group, biphenylyloxycarbonyl group and the like; examples of triorganosiloxy group include trimethylsiloxy group and triethylsiloxy group; Includes a trimethylsilyl group, a triethylsilyl group and the like; examples of the amino group include a primary amino group; examples of the alkoxysilyl group include a trimethoxysilyl group and a triethoxysilyl group.
- Specific examples of the specific monomer d include tetracyclo [4.4.0.1 2,5 . 1 7,10 ] -3-dodecene, pentacyclo [9.2.1.1 3,9 . 0 2,10 . 0 4,8]-12-pentadecene, pentacyclo [9.2.1.1 5,8. 0 2,10 . 0 4,9 ] -12-pentadecene, 8-methoxycarbonyltetracyclo [4.4.0.1 2,5 . 1 7,10] -3-dodecene, 8-ethoxycarbonyl tetracyclo [4.4.0.1 2, 5.
- R 1 and R 3 are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms
- R 2 and R 4 correspond to a hydrogen atom or a monovalent organic group
- at least one of R 2 and R 4 is a polar group other than a hydrogen atom and a hydrocarbon group, This is preferable because it improves the adhesiveness and adhesiveness.
- the content of the polar group in the obtained specific polymer is determined by a desired function or the like required for the finally obtained specific retardation film, and is not particularly limited.
- the structural unit derived from the specific monomer d having a polar group in all structural units derived from the monomer d is usually 1 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, All structural units derived from the specific monomer d may have a polar group.
- R 2 and R 4 has a polar group represented by the general formula (9).
- the glass transition temperature and the water absorption are preferred because of easy control.
- n is an integer of 0 to 5
- R 10 is a monovalent organic group.
- n is an integer of 0 to 5, preferably an integer of 0 to 2, and more preferably 0. The smaller the value of n, the higher the glass transition temperature of the specific polymer obtained, which is preferable.
- the specific monomer d having n of 0 is preferable in terms of easy synthesis.
- the specific monomer d is preferably one in which an alkyl group is further bonded to the carbon atom to which the polar group represented by the general formula (9) is bonded in the general formula (7). It is possible to achieve a balance between heat resistance and water absorption of the specific polymer.
- the number of carbon atoms of the alkyl group is preferably 1 to 5, more preferably 1 to 2, and particularly preferably 1.
- the specific monomer d those in which m is 1 and p is 0 in the general formula (7) are preferable in that a specific polymer having a high glass transition temperature is obtained.
- Specific examples of the specific monomer e include bicyclo [2.2.1] hept-2-ene, tricyclo [5.2.1.0 2,6 ] dec-8-ene, and tricyclo [6.2. 1.0 2,7 ] undec-9-ene, 5-methylbicyclo [2.2.1] hept-2-ene, 5-ethylbicyclo [2.2.1] hept-2-ene, 5-methoxy Carbonylbicyclo [2.2.1] hept-2-ene, 5-methyl-5-methoxycarbonylbicyclo [2.2.1] hept-2-ene, 5-phenoxycarbonylbicyclo [2.2.1] hept -2-ene, 5-methyl-5-phenoxycarbonylbicyclo [2.2.1] hept-2-ene, 5-cyanobicyclo [2.2.1] hept-2-ene, 5-ethylidenebicyclo [2 2.1] Hept-2-ene, 5-phenylbicycl B [2.2.1] hept-2-ene, 5- (2
- the specific polymer obtained by copolymerizing the specific monomer d and the specific monomer e is copolymerized with other copolymerizable monomers other than the specific monomer d and the specific monomer e. It may be made.
- other copolymerizable monomers include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.
- the number of carbon atoms in the cycloolefin is preferably 4-20, and more preferably 5-12.
- a specific single amount in the presence of an unsaturated hydrocarbon polymer having an olefinically unsaturated bond in the main chain such as polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-nonconjugated diene copolymer, and polynorbornene.
- an unsaturated hydrocarbon polymer having an olefinically unsaturated bond in the main chain such as polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-nonconjugated diene copolymer, and polynorbornene.
- the specific monomer e may be polymerized as required, and the specific polymer thus obtained is useful as a raw material for a resin having high impact resistance.
- the specific viscosity ( ⁇ inh ) of the specific polymer measured in chloroform at 30 ° C. is preferably 0.2 to 5 dl / g. More preferably, it is 0.3-4 dl / g, and particularly preferably 0.5-3 dl / g. In the above range, since the solution viscosity does not increase, the processability is good and the film strength is sufficient.
- the polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is usually 8,000 to 1,000,000, preferably 10,000 to 500. , More preferably 20,000 to 100,000, particularly preferably 30,000 to 100,000, and the weight average molecular weight (Mw) is usually 20,000 to 3,000,000, preferably 30 , 1,000 to 1,000,000, more preferably 40,000 to 500,000, particularly preferably 40,000 to 300,000.
- the molecular weight distribution of the specific polymer is such that the above Mw / Mn is usually 1.5 to 10, preferably 2 to 8, more preferably 2.5 to 5, particularly preferably 2.5 to 4.5. .
- the glass transition temperature (Tg) of the specific polymer may be appropriately changed by adjusting the type of the structural unit d and the structural unit e of the specific polymer, the ratio of the structural unit d to the structural unit e, or the addition of an additive. However, it is usually 100 to 250 ° C, preferably 110 to 200 ° C, more preferably 120 to 180 ° C. A Tg of 100 ° C. or higher is preferable because the heat distortion temperature is not lowered, there is no possibility of problems in heat resistance, and the optical properties of the finally obtained film are hardly affected by the temperature. Further, when the Tg is 250 ° C. or lower, the thermoplastic cycloolefin-based resin, preferably the thermoplastic norbornene-based resin, is less likely to be thermally deteriorated when heated to the vicinity of Tg for stretching or the like, which is preferable.
- the proportion of the structural unit d is in the above range, the effect of improving toughness and desired optical characteristics can be sufficiently expected, the glass transition temperature is not lowered, and there is no problem in heat resistance.
- the ratio (composition ratio) between the structural unit d and the structural unit e in the polymer has small variation in the entire molecular weight distribution range.
- the composition ratio at an arbitrary molecular weight is within ⁇ 50%, preferably within ⁇ 30%, more preferably relative to the ratio of the specific monomer d and the specific monomer e subjected to the polymerization reaction.
- the ring-opening polymerization reaction of the monomer is performed in the presence of a metathesis catalyst.
- the metathesis catalyst includes (a) at least one selected from compounds of W, Mo and Re, (b) a Deaming Periodic Table Group IA element (for example, Li, Na, K, etc.), a IIA Group element (for example, Mg, Ca, etc.), Group IIB elements (eg, Zn, Cd, Hg, etc.), Group IIIB elements (eg, B, Al, etc.), Group IVA elements (eg, Ti, Zr, etc.) or Group IVB elements (eg, Si, Sn, etc.) Pb or the like) and a catalyst comprising a combination with at least one selected from those having at least one of the element-carbon bond or the element-hydrogen bond.
- an additive (c) described later may be added.
- W, Mo or Re compounds suitable as component (a) include compounds described in JP-A-1-240517 such as WCl 6 , MoCl 5 and ReOCl 3 .
- Specific examples of the component (b) include n-C 4 H 9 Li, (C 2 H 5 ) 3 Al, (C 2 H 5 ) 2 AlCl, (C 2 H 5 ) 1.5 AlCl 1.5 , (C 2 H 5 )
- the compounds described in JP-A-1-240517 such as AlCl 2 , methylalumoxane and LiH can be mentioned.
- alcohols, aldehydes, ketones, amines and the like can be preferably used, and compounds described in JP-A-1-240517 can also be used.
- the amount of the metathesis catalyst used is the molar ratio of the component (a) to the specific monomer d and the specific monomer e (hereinafter referred to as “specific monomer”).
- the specific monomer is usually in the range of 1: 500 to 1: 50,000, preferably in the range of 1: 1,000 to 1: 10,000.
- the ratio of the component (a) to the component (b) is such that “(a) :( b)” is 1: 1 to 1:50, preferably 1: 2 to 1:30 in terms of metal atom ratio.
- the ratio of the component (a) to the component (c) is such that “(c) :( a)” is in a molar ratio of 0.005: 1 to 15: 1, preferably 0.05: 1 to 7: 1. It is.
- the molecular weight of the specific polymer can be adjusted depending on the polymerization temperature, the type of catalyst, and the type of solvent. In the present invention, it is preferable to adjust the molecular weight by allowing a molecular weight regulator to coexist in the reaction system.
- Suitable molecular weight regulators include, for example, ⁇ -olefins such as ethylene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and styrene. Of these, 1-butene and 1-hexene are preferred. These molecular weight regulators can be used alone or in combination of two or more. The amount of the molecular weight regulator used is 0.005 to 0.6 mol, preferably 0.02 to 0.5 mol, per 1 mol of the specific monomer subjected to the polymerization reaction.
- Solvent for ring-opening polymerization reaction examples include alkanes such as pentane, hexane, heptane, octane, nonane, decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane; benzene, toluene, xylene Aromatic hydrocarbons such as ethylbenzene and cumene; halogenated hydrocarbon compounds such as chlorobutane, bromohexane, methylene chloride, dichloroethane, hexamethylene dibromide, chlorobenzene, chloroform, and tetrachloroethylene; ethyl acetate, n-butyl acetate, acetic acid Saturated carboxylic acid esters such as iso-butyl and methyl
- the ring-opening copolymer obtained by the above ring-opening polymerization can be used as a specific polymer as it is, but a hydrogenated product in which the olefinically unsaturated bond remaining in the ring-opening copolymer is hydrogenated and It is preferable to do.
- This hydrogenated product has excellent thermal stability, and its characteristics are not easily deteriorated by heating at the time of film formation, stretching, or use as a product.
- the hydrogenation rate with respect to the olefinically unsaturated bond is 50% or more, preferably 70% or more, more preferably 90% or more, and particularly preferably 98% or more.
- the aromatic ring is not substantially hydrogenated after hydrogenation.
- a hydrogenation catalyst is added to an ordinary method, that is, a solution of the ring-opening copolymer, and hydrogen gas at normal pressure to 300 atm, preferably 3 to 200 atm, is added thereto at 0 to 200 ° C., preferably It is carried out by operating at 20 to 180 ° C.
- a hydrogenation catalyst what is used for the hydrogenation reaction of a normal olefinic compound can be used.
- a heterogeneous catalyst and a homogeneous catalyst are known.
- the heterogeneous catalyst include solid catalysts in which noble metals such as palladium, platinum, nickel, rhodium, and ruthenium are supported on a carrier such as carbon, silica, alumina, and titania.
- homogeneous catalysts include nickel naphthenate / triethylaluminum, nickel acetylacetonate / triethylaluminum, cobalt octenoate / n-butyllithium, titanocene dichloride / diethylaluminum monochloride, rhodium acetate, chlorotris (triphenylphosphine) rhodium. Dichlorotris (triphenylphosphine) ruthenium, chlorohydrocarbonyltris (triphenylphosphine) ruthenium, dichlorocarbonyltris (triphenylphosphine) ruthenium, and the like.
- the form of the catalyst may be powder or granular.
- These hydrogenation catalysts are used in such a ratio that the ring-opening polymer: hydrogenation catalyst (mass ratio) is 1: 1 ⁇ 10 ⁇ 6 to 1: 2.
- the humidity dependence of an elastic modulus can be adjusted by making the hydrophilicity of a monomer unit into the range of following formula (G) the cycloolefin type polymer film of this invention.
- G the cycloolefin type polymer film of this invention.
- logP (i) is the octanol / water partition coefficient of the i-th structural unit
- Mi is the mole fraction of the i-th structural unit.
- the octanol / water partition coefficient can be determined by actual measurement or calculation. More preferably, 1 ⁇ logP (i) ⁇ Mi ⁇ 4, and most preferably 2 ⁇ logP (i) ⁇ Mi ⁇ 3.5.
- thermoplastic cycloolefin resin comprising a specific polymer, preferably a thermoplastic norbornene resin
- a solvent casting method from the viewpoint of obtaining a pre-processed film having high uniformity of the surface and good surface smoothness.
- a film forming liquid containing a thermoplastic cycloolefin resin at an appropriate concentration is prepared by dissolving or dispersing a thermoplastic cycloolefin resin in a solvent. Can be poured or coated on a suitable carrier, dried, and then peeled off from the carrier.
- the concentration of the cycloolefin resin is usually 0.1 to 90% by weight, preferably 1 to 50% by weight, more preferably 10 to 35% by weight. To do. When this concentration is within the above range, a pre-processed film having a required thickness can be obtained, and when removing the solvent by drying, foaming or the like hardly occurs with evaporation of the solvent, and surface smoothness is good. Can be obtained, and since the solution viscosity of the film forming liquid does not increase, a film having a uniform thickness and surface condition can be obtained.
- the viscosity of the film-forming solution is usually 1 to 1,000,000 (mPa ⁇ s), preferably 10 to 100,000 (mPa ⁇ s), more preferably 100 to 50,000 (mPa ⁇ s) at room temperature. s), particularly preferably 1,000 to 40,000 (mPa ⁇ s).
- Solvents used for the preparation of the film forming liquid include aromatic solvents such as benzene, toluene and xylene, cellosolve solvents such as methyl cellosolve, ethyl cellosolve and 1-methoxy-2-propanol, diacetone alcohol, acetone and cyclohexanone.
- Ketone solvents such as methyl ethyl ketone, 4-methyl-2-pentanone, ethyl cyclohexanone, ester solvents such as methyl lactate and ethyl lactate, 2,2,3,3-tetrafluoro-1-propanol, methylene chloride, chloroform, etc.
- halogen-containing solvents tetrahydrofuran, dioxane and other ether solvents, 1-pentanol, 1-butanol and other alcohol solvents, and 1,2-dimethylcyclohexane.
- the SP value is usually 10 to 30 (MPa 1/2 ), preferably 10 to 25 (MPa 1/2 ), more preferably 15 to 25 (MPa 1/2).
- a solvent in the range of 15 to 20 (MPa 1/2 ) is used, a processed film having good surface uniformity and optical properties can be obtained.
- the SP value range of the obtained mixed solvent is preferably within the above range.
- the SP value of the mixed solvent can be obtained from the weight ratio of each solvent constituting the mixed solvent.
- a light diffusing function can be obtained by combining a good solvent with a poor solvent for a thermoplastic cycloolefin resin, preferably a thermoplastic norbornene resin.
- the film before processing which has can be obtained.
- the SP value of the thermoplastic cycloolefin resin is SPx
- the SP value of the good solvent of the thermoplastic cycloolefin resin is SPy
- the SP value of the poor solvent of the thermoplastic cycloolefin resin is SPz
- the difference between SPx and SPy is preferably 7 or less, more preferably 5 or less, particularly preferably 3 or less
- the difference between SPx and SPz is preferably 7 or more, more preferably 8 or more, particularly preferably 9 or more.
- the difference between SPy and SPz is preferably 3 or more, more preferably 5 or more, and even more preferably 7 or more, so that a light diffusing function can be imparted to the resulting pre-processed film.
- the specific retardation film thus obtained can have a light diffusion function.
- the proportion of the poor solvent in the mixed solvent is preferably 50% by weight or less, more preferably 30% by weight or less, particularly preferably 15% by weight or less, and most preferably 10% by weight or less.
- the difference between the boiling point of the poor solvent and the boiling point of the good solvent is preferably 1 ° C. or higher, more preferably 5 ° C. or higher, particularly preferably 10 ° C. or higher, and most preferably 20 ° C. or higher. It is preferably higher than the boiling point of the good solvent.
- the temperature at which the thermoplastic cycloolefin resin, preferably the thermoplastic norbornene resin is dissolved or dispersed in the solvent may be room temperature or high temperature, and the thermoplastic cycloolefin resin is uniformly dissolved or stirred by sufficient stirring. A dispersed film-forming solution is obtained.
- coloring agents such as a dye and a pigment, can be suitably added to a film forming liquid as needed, and thereby a colored film before processing can be obtained.
- leveling agents various ones can be used as long as they are general, and specific examples thereof include fluorine-based nonionic surfactants, special acrylic resin-based leveling agents, silicone-based leveling agents, and the like. .
- a carrier for forming the liquid layer of the film forming liquid a metal drum, a steel belt, a polyester film made of polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), a polytetrafluoroethylene belt, or the like may be used. it can.
- a method for applying the film forming liquid a method using a die or a coater, a spray method, a brush coating method, a roll coating method, a spin coating method, a dipping method, or the like can be used.
- the thickness and surface smoothness of the pre-processed film obtained can also be controlled by repeatedly applying the film forming liquid.
- a surface-treated film When a polyester film is used as the carrier, a surface-treated film may be used.
- a hydrophilic treatment method generally performed, for example, a method of laminating an acrylic resin or a sulfonate group-containing resin by coating or lamination, or a hydrophilic property of the film surface by corona discharge treatment or the like. The method etc. which improve are mentioned.
- a specific method for removing the solvent in the liquid layer is not particularly limited, and a commonly used drying treatment method, for example, a method of passing through a drying furnace by a large number of rollers is used.
- a drying treatment method for example, a method of passing through a drying furnace by a large number of rollers.
- the drying process is performed in two or more stages. It is preferable to control the temperature or the air volume in each step.
- the amount of residual solvent in the pre-processed film thus obtained is usually 10% by weight or less, preferably 5% by weight or less, more preferably 1% by weight or less, and particularly preferably 0.5% by weight or less.
- the residual solvent amount in the pre-processed film is in the above range, the dimensional change with time is preferably small when a specific retardation film obtained by stretching the pre-processed film is actually used.
- the residual solvent is preferable because the glass transition temperature is not lowered and the heat resistance is not lowered.
- the amount of residual solvent in the unprocessed film is usually 10 to 0.1% by weight, preferably 5 to 0.1% by weight, in order to stably and uniformly develop the retardation in the film by the stretching and orientation treatment. %, More preferably 1 to 0.1% by weight.
- the thickness of the film before processing is usually 1 to 30 ⁇ m (1,000 to 60,000 nm), preferably 5 to 30 ⁇ m (500 to 30,000 nm), more preferably 10 to 20 ⁇ m (10,000 to 20). , 000 nm).
- the thickness distribution of the film before processing is usually within ⁇ 20%, preferably within ⁇ 10%, more preferably within ⁇ 5%, particularly preferably within ⁇ 3% with respect to the average value.
- the variation in thickness per cm is usually 10% or less, preferably 5% or less, more preferably 1% or less, and particularly preferably 0.5% or less.
- the stretching method for producing the specific retardation film include known uniaxial stretching methods and biaxial stretching methods. That is, by the horizontal uniaxial stretching method by the tenter method, the inter-roll compression stretching method, the longitudinal uniaxial stretching method using two sets of rolls having different circumferences, or the biaxial stretching method combining the horizontal uniaxial and the longitudinal uniaxial, the inflation method A stretching method or the like can be used.
- the stretching speed is usually 1 to 5,000% / min, preferably 50 to 1,000% / min, more preferably 100 to 1,000% / min, particularly preferably. Is 100 to 500% / min.
- stretching may be performed in two directions at the same time, or the stretching may be performed in a direction different from the first stretching direction after uniaxial stretching.
- the intersecting angle of the two stretching axes for controlling the shape of the refractive index ellipsoid of the stretched film is not particularly limited because it is determined by desired characteristics, but is usually in the range of 120 to 60 degrees. is there.
- the stretching speed may be the same or different in each stretching direction, and is usually 1 to 5,000% / min, preferably 50 to 1,000% / min, and more preferably It is 100 to 1,000% / min, and particularly preferably 100 to 500% / min.
- the treatment temperature in the stretching orientation treatment is not particularly limited, but is usually Tg ⁇ 30 ° C., preferably based on the glass transition temperature Tg of the thermoplastic cycloolefin resin used, preferably the thermoplastic norbornene resin. Tg ⁇ 15 ° C., more preferably in the range of Tg ⁇ 5 ° C. to Tg + 15 ° C.
- the draw ratio is not particularly limited because it is determined by desired properties, but is usually 1.01 to 10 times, preferably 1.03 to 5 times, and more preferably 1.03 to 3 times. When the draw ratio is in the above range, it is easy to control the phase difference.
- the stretched film may be cooled as it is, but is kept in a temperature atmosphere of Tg-20 ° C. to Tg for at least 10 seconds or more, preferably 30 seconds to 60 minutes, more preferably 1 minute to 60 minutes. It is preferable to do. As a result, a stable retardation film can be obtained with little change over time in the retardation of transmitted light.
- the dimensional shrinkage due to heating of the specific retardation film is usually 10% or less, preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less when heated at 100 ° C. for 500 hours. .
- the specific monomer a, the specific monomer b or other copolymerizable monomer it can be controlled by a casting method or a stretching method.
- the dimensional shrinkage ratio due to heating of the pre-processed film in a state where the stretch orientation treatment has not been performed is usually 5% or less, preferably 3% or less, more preferably 1% when heating at 100 ° C. is performed for 500 hours.
- it is particularly preferably 0.5% or less.
- the film stretched as described above gives a phase difference to transmitted light due to the orientation of molecules by stretching.
- This phase difference is determined by the type of thermoplastic norbornene resin used as a raw material, It can be controlled by adjusting the magnification, the stretching temperature or the thickness of the film before stretching (film before processing).
- the magnification the stretching temperature or the thickness of the film before stretching (film before processing).
- the absolute value of the retardation of transmitted light tends to increase as the draw ratio increases.
- a film that imparts a retardation to transmitted light can be obtained.
- the thickness of the film before stretching (film before processing) even if the stretching ratio is the same, the larger the thickness of the film before stretching, the larger the absolute value of the phase difference given to transmitted light tends to increase.
- a retardation film that imparts a desired retardation to transmitted light By changing the thickness of the film before stretching, a retardation film that imparts a desired retardation to transmitted light can be obtained.
- the stretching treatment temperature the lower the stretching temperature, the greater the absolute value of the retardation of the transmitted light. Therefore, by changing the stretching temperature, a retardation film that gives the desired retardation to the transmitted light is obtained. be able to.
- the thickness of the specific retardation film in order to adjust the thickness of the specific retardation film, it can be controlled by adjusting the thickness of the pre-processed film, the draw ratio, and the like. Specifically, for example, the thickness of the retardation film can be reduced by reducing the thickness of the film before processing or increasing the draw ratio.
- the number of bright spots when converted per 1 m 2 on the film surface is 10 or less, preferably 7 or less, more preferably 5 or less, and particularly preferably 3 Hereinafter, it is most preferably 0 or 1.
- the “bright spot” is a partial light leakage confirmed with the naked eye when a specific retardation film is sandwiched between polarizing plates in a crossed Nicol state, and usually has an outer diameter of 1 ⁇ m or more (circular shape). If it is, the diameter is measured, and if it is other shape, the length in the longitudinal direction is measured. Of course, depending on the required performance, a smaller one may be measured as a bright spot.
- Such bright spots are considered to be caused by partial unevenness of the phase difference in a minute region. That is, when foreign matter, bubbles, etc. are present in the film before processing, even if they are of a size that cannot be confirmed with the naked eye, when the stretch process is performed, stress concentrates on the part where foreign matter, bubbles, etc. exist, The phase difference in the stress concentrated portion may be different from the phase difference in the peripheral portion, and it is considered that light leaks due to the difference in the phase difference.
- the number of foreign matters when converted to 1 m 2 on the film surface is preferably 10 or less, more preferably 5 or less, particularly preferably 3 or less, and most preferably 0. Or it is set to 1.
- the term “foreign matter” as used herein substantially prevents light transmission when light is transmitted through the specific retardation film.
- the size of the foreign matter to be measured is usually an outer diameter of 1 ⁇ m or more (the diameter of a circular one, the length in the longitudinal direction of other shapes), but depending on the required performance Something smaller than this may be measured as a foreign object.
- the first protective film preferably has at least one surface subjected to a hydrophilic treatment in order to ensure adhesion with the polarizer.
- a hydrophilic treatment for example, a method of providing an adhesive layer described in JP-A No. 2000-24167, JP-A No. 10-130402, JP-A No. 2002-148436, JP-A No. 2002-90546, JP-A No. 2001-350017, Further, hydrophilicity can be imparted by surface treatment such as corona discharge treatment described in JP-A-2001-350018.
- the first protective film may be either an unstretched film or a stretched film.
- a stretched film either a uniaxially stretched film or a biaxially stretched film may be used.
- a biaxially stretched film either a simultaneous biaxially stretched film or a sequential biaxially stretched film may be used.
- biaxial stretching the mechanical strength is improved and the film performance is improved.
- the synthetic polymer film can suppress an increase in retardation even when stretched by mixing other thermoplastic resins, and can maintain optical isotropy.
- the stretching temperature is preferably in the vicinity of the glass transition temperature of the thermoplastic resin composition as the film raw material, and specifically, preferably (glass transition temperature ⁇ 30 ° C.) to (glass transition temperature + 100 ° C.), more preferably Is in the range of (glass transition temperature ⁇ 20 ° C.) to (glass transition temperature + 80 ° C.). If the stretching temperature is less than (glass transition temperature-30 ° C.), a sufficient stretching ratio may not be obtained. On the other hand, if the stretching temperature exceeds (glass transition temperature + 100 ° C.), the resin composition may flow, and stable stretching may not be performed.
- the draw ratio defined by the area ratio is preferably 1.1 to 25 times, more preferably 1.3 to 10 times.
- the stretching speed in one direction is preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min. When the stretching speed is less than 10% / min, it takes time to obtain a sufficient stretching ratio, and the production cost may increase. If the stretching speed exceeds 20,000% / min, the stretched film may be broken.
- the first protective film can be subjected to a heat treatment (annealing) or the like after the stretching treatment in order to stabilize its optical isotropy and mechanical properties.
- Arbitrary appropriate conditions can be employ
- the thickness of the first protective film is 30 ⁇ m or less, preferably 1 to 30 ⁇ m, more preferably 5 to 30 ⁇ m, and still more preferably 10 to 20 ⁇ m, from the viewpoint of difficulty in generating unevenness.
- the thickness exceeds 30 ⁇ m not only the transparency is lowered, but also the moisture permeability becomes small, and when a water-based adhesive is used, there is a possibility that the drying rate of water as the solvent becomes slow.
- a durability test of high temperature and high humidity is applied, there is a risk of uneven light leakage in the screen of the liquid crystal display device.
- the thickness of the first protective film is an average film thickness measured by optical microscope observation of the film cross section.
- the first protective film preferably has a humidity dimensional change rate represented by the following formula (1) in the TD direction of 0.1% or less from the viewpoint of stability of optical characteristics, and is 0% or more and 0.00. 1% or less is more preferable, and 0% or more and 0.05% or less is still more preferable.
- TD direction humidity dimensional change rate (%) [ ⁇ (film length in TD direction at 25 ° C., 80% relative humidity) ⁇ (film length in TD direction at 25 ° C., 10% relative humidity) ⁇ / (25 TD, film length in TD direction at 60% relative humidity)] ⁇ 100 ...
- the first protective film has a humidity dimensional change rate represented by the formula (1) in a direction parallel to the absorption axis of the polarizer (film transport direction during film production: MD direction), as in the TD direction. From the viewpoint of the stability of optical properties, 0.5% or less is preferable, 0.25% or less is more preferable, and 0.1% or less is even more preferable. As the humidity dimensional change rate of the first protective film is smaller, the shrinkage or expansion of the first protective film that occurs when the humidity change occurs is reduced. This reduces the force applied to the pressure-sensitive adhesive for bonding the polarizing plate to the glass or liquid crystal cell constituting the liquid crystal cell, and as a result, light leakage due to photoelasticity is reduced.
- the wetting tension on the surface of the first protective film is preferably 40 mN / m or more, more preferably 50 mN / m or more, and further preferably 55 mN / m or more.
- the surface wetting tension is at least 40 mN / m or more, the adhesive strength between the (meth) acrylic resin film and the polarizer is further improved.
- Any suitable surface treatment can be applied to adjust the surface wetting tension. Examples of the surface treatment include corona discharge treatment, plasma treatment, ozone spraying, ultraviolet irradiation, flame treatment, and chemical treatment. Of these, corona discharge treatment and plasma treatment are preferable.
- the elastic modulus in the TD direction of the first protective film is 2.0 GPa to 2.5 GPa.
- the elastic modulus in the TD direction is 2.5 GPa or less, the occurrence of unevenness due to photoelasticity is reduced.
- the first protective film is preferably disposed on the liquid crystal cell side (inner side) when the polarizing plate of the present invention is incorporated in a liquid crystal display device.
- the first protective film is preferable from the viewpoint of suppressing occurrence of unevenness when used for a long time under high temperature and high humidity.
- the second protective film has an evaluation value represented by the following formula (2) of 7.0 to 11.0.
- Formula (2): Evaluation value Elastic modulus (GPa) in the TD direction of the second protective film / humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (thickness ( ⁇ m) of the second protective film / first Protective film thickness ( ⁇ m)) 2 ⁇ ⁇ (30 / polarizer thickness ( ⁇ m)) ⁇ 1/2
- the humidity dimensional change rate in the TD direction of the second protective film is represented by the following formula (1).
- TD direction humidity dimensional change rate (%) [ ⁇ (film length in TD direction at 25 ° C., 80% relative humidity) ⁇ (film length in TD direction at 25 ° C., 10% relative humidity) ⁇ / (25 TD, film length in TD direction at 60% relative humidity)] ⁇ 100
- FIG. 4 shows the relationship between the curl floating amount of the polarizing plate and the humidity dimensional change rate in the TD direction of the second protective film. From FIG. 4, no relationship can be found between the dimensional change rate of humidity in the TD direction of the second protective film and the curl floating amount of the polarizing plate. Next, regarding the curl floating amount, the relationship between the dimensional change rate in the TD direction of the second protective film and the elastic modulus in the TD direction of the second protective film was examined.
- FIG. 5 shows a curl map showing the dimensional change rate of the humidity in the TD direction of the second protective film and the contour line of the elastic modulus and the curl floating amount of the second protective film in the TD direction.
- Evaluation value 2 elastic modulus (GPa) in the TD direction of the second protective film / humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (thickness ( ⁇ m) of the second protective film / first Protective film thickness ( ⁇ m)) 2
- FIG. 7 shows the relationship between the curl floating amount and the evaluation value 2 when the thickness of the polyvinyl alcohol film of the polarizer is 30 ⁇ m.
- FIG. 7 shows that the curl floating amount and the evaluation value 2 correspond well.
- the thickness of the polarizer was changed, the relationship between the evaluation value 2 and the curl floating amount was examined.
- FIG. 8 shows the relationship between the curl floating amount and the evaluation value 2 when the film thickness of the polyvinyl alcohol of the polarizer is 30 ⁇ m and 20 ⁇ m. From FIG. 8, it was found that when the thickness of the polarizer changes, the preferable region of the evaluation value 2 changes. More specifically, it was found that when the thickness of the polarizer is reduced, the slope of the straight line indicating the correspondence between the curl floating amount and the evaluation value 2 is reduced. And it is set as the evaluation value represented by following formula (2) as an evaluation value which added correction
- Evaluation value Elastic modulus (GPa) in the TD direction of the second protective film / humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (thickness ( ⁇ m) of the second protective film / first Protective film thickness ( ⁇ m)) 2 ⁇ ⁇ (30 / polarizer thickness ( ⁇ m)) ⁇ 1/2
- FIG. 9 shows the relationship between the evaluation value (evaluation value 3) according to the expression (2) and the curl floating amount. From FIG. 9, it can be seen that the evaluation value according to the equation (2) and the curl floating amount are on a straight line, and the correspondence is good.
- the evaluation value represented by the formula (2) is preferably 7.0 to 11.0 from the viewpoint of less frequent occurrence of errors such as entrainment of bubbles and misalignment at the time of bonding a polarizing plate to a liquid crystal cell. 9.0 to 10.0 is more preferable, 9.0 to 9.8 is particularly preferable, and 9.0 to 9.6 is most preferable.
- the material constituting the second protective film is not particularly limited.
- the second protective film preferably contains a resin.
- a resin a known resin can be used, and is not particularly limited as long as it does not contradict the gist of the present invention.
- (Meth) acrylic resins, cycloolefin resins and polyester resins can be mentioned, and cellulose acylate is preferred.
- the degree of substitution of cellulose acylate means the ratio of acylation of three hydroxyl groups present in the structural unit of cellulose (glucose having a ( ⁇ ) 1,4-glycoside bond).
- the degree of substitution can be calculated by measuring the amount of bound fatty acid per unit mass of cellulose.
- the degree of substitution of the cellulose body is determined from the peak intensity ratio of the carbonyl carbon in the acyl group by dissolving the cellulose body in a solvent such as dimethyl sulfoxide substituted with deuterium and measuring the 13 C-NMR spectrum. This can be calculated.
- the total acyl substitution degree of the cellulose acylate is preferably 2.0 to 2.97, more preferably 2.2 to 2.95, and particularly preferably 2.3 to 2.95.
- As the acyl group of cellulose acylate an acetyl group, a propionyl group, and a butyryl group are particularly preferable, and an acetyl group is particularly preferable.
- a mixed fatty acid ester composed of two or more kinds of acyl groups can also be preferably used as the cellulose acylate in the present invention.
- the acyl group is preferably an acetyl group and an acyl group having 3 to 4 carbon atoms.
- the substitution degree of an acetyl group is preferably less than 2.5, and more preferably less than 1.9.
- the substitution degree of the acyl group having 3 to 4 carbon atoms is preferably 0.1 to 1.5, more preferably 0.2 to 1.2, and 0.5 to 1.1. It is particularly preferred.
- two types of cellulose acylates having different substituents and / or degree of substitution may be used in combination, mixed, or from a plurality of layers composed of different cellulose acylates by the co-casting method described later.
- a film may be formed.
- mixed acid esters having a fatty acyl group and a substituted or unsubstituted aromatic acyl group described in [0023] to [0038] of JP-A-2008-20896 can also be preferably used in the present invention.
- the cellulose acylate preferably has a mass average degree of polymerization of 250 to 800, more preferably 300 to 600.
- the cellulose acylate preferably has a number average molecular weight of 70000 to 230,000, more preferably a number average molecular weight of 75000 to 230,000, and most preferably a number average molecular weight of 78000 to 120,000.
- Cellulose acylate can be synthesized using an acid anhydride or acid chloride as an acylating agent.
- an organic acid for example, acetic acid
- methylene chloride is used as a reaction solvent.
- a protic catalyst such as sulfuric acid can be used as the catalyst.
- the acylating agent is an acid chloride
- a basic compound can be used as a catalyst.
- cellulose is an organic acid corresponding to acetyl group and other acyl groups (acetic acid, propionic acid, butyric acid) or acid anhydrides thereof (acetic anhydride, propionic anhydride, butyric anhydride).
- a cellulose ester is synthesized by esterification with a mixed organic acid component containing.
- cellulose such as cotton linter or wood pulp is activated with an organic acid such as acetic acid and then esterified using a mixture of organic acid components as described above in the presence of a sulfuric acid catalyst.
- the organic acid anhydride component is generally used in an excess amount relative to the amount of hydroxyl groups present in the cellulose.
- a hydrolysis reaction depolymerization reaction
- the degree of polymerization of the cellulose ester is lowered, and the physical properties of the cellulose ester film to be produced are lowered. Therefore, the reaction conditions such as the reaction temperature are preferably determined in consideration of the degree of polymerization and molecular weight of the resulting cellulose ester.
- the 2nd protective film may contain the well-known additive used for an organic acid and another polarizing plate protective film, unless it is contrary to the meaning of this invention. This can help control the rate of change in humidity.
- the molecular weight of the additive is not particularly limited, but the additives described below can be preferably used.
- the film can be modified to improve thermal properties, optical properties, mechanical properties, impart flexibility, absorb water resistance, reduce moisture permeability, etc. It shows useful effects in terms of quality.
- control of mechanical properties includes the addition of a plasticizer to a film.
- plasticizers that can be used as reference include various known esters such as phosphate esters, citrate esters, trimellitic acid esters, and sugar esters. Reference can be made to the description of ester plasticizers and polyester polymers in paragraph numbers 0042 to 0068 of International Publication No. 2011/102492.
- the description of paragraph numbers 0069 to 0072 of International Publication No. 2011/102492 can be referred to, and adjustment of the retardation of the film
- a known retardation adjusting agent can be used for controlling expression. This can help control the rate of change in humidity.
- the molecular weight of the additive is not particularly limited, but the additives described below can be preferably used.
- the thickness of the second protective film is preferably 5 to 30 ⁇ m, more preferably 10 to 30 ⁇ m, and particularly preferably 15 to 25 ⁇ m. A thickness of 30 ⁇ m or less is preferable from the viewpoint of slimming the liquid crystal display. On the other hand, when the thickness is 5 ⁇ m or more, the surface of the polarizing plate is not easily damaged because it is difficult to break during conveyance during processing of the polarizing plate.
- the thickness of the second protective film is an average film thickness measured by optical microscope observation of the film cross section.
- the amount of the additive added is preferably 10% by mass or more, more preferably 15% by mass or more, and more preferably 20% by mass or more with respect to cellulose acylate from the viewpoint of developing the various effects described above. More preferably it is. As an upper limit, it is preferable that it is 80 mass% or less, and it is preferable that it is 65 mass% or less. When two or more kinds of additives are used, the total amount is preferably within the above range.
- the moisture permeability of the second protective film is preferably 10 g / m 2 ⁇ day or more from the viewpoint of the drying speed during the production of the polarizing plate.
- Moisture permeability of the second protective film is more preferably 10 ⁇ 500g / m 2 ⁇ day , more preferably in a 100 ⁇ 500g / m 2 ⁇ day , is 200 ⁇ 450g / m 2 ⁇ day More particularly preferred.
- ⁇ Method for producing second protective film About the manufacturing method of said 2nd protective film, as a manufacturing method of the film using (meth) acrylic-type resin, cycloolefin type resin, and polyester-type resin, although it does not specifically limit,
- resin and Other polymers, additives, and the like can be sufficiently mixed by any appropriate mixing method to obtain a thermoplastic resin composition in advance, and then formed into a film.
- the resin and other polymers, additives, and the like may be made into separate solutions and mixed to form a uniform mixed solution, and then formed into a film.
- the film raw material is pre-blended with any appropriate mixer such as an omni mixer, and then the obtained mixture is extrusion kneaded.
- the mixer used for extrusion kneading is not particularly limited, and for example, any suitable mixer such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader may be used.
- the film forming method include any appropriate film forming method such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method.
- the solution casting method (solution casting method) and the melt extrusion method are preferable.
- the method for producing the second protective film will be described in detail by taking as an example the case where the second protective film is a film containing cellulose acylate (also referred to as “cellulose acylate film”).
- the cellulose acylate film can be produced by a solvent cast method.
- the manufacturing method of the polarizing plate protective film containing the said organic acid is demonstrated taking the example which used the cellulose acylate as a base material, when using other resin, the said polarizing plate protective film is similarly demonstrated.
- the solvent cast method a film is produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent.
- the organic solvent is selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to include a solvent.
- the ether, ketone and ester may have a cyclic structure.
- a compound having two or more functional groups of the ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent.
- the organic solvent may have another functional group such as an alcoholic hydroxyl group.
- the number of carbon atoms is preferably within the above-described preferable range of carbon atoms of the solvent having any functional group.
- Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
- Examples of the ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
- esters having 3 to 12 carbon atoms examples include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
- organic solvent having two or more kinds of functional groups examples include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
- the number of carbon atoms of the halogenated hydrocarbon having 1 to 6 carbon atoms is preferably 1 or 2, and most preferably 1.
- the halogen of the halogenated hydrocarbon is preferably chlorine.
- the proportion of halogen atoms in the halogenated hydrocarbon substituted with halogen is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferably 40 to 60 mol%.
- Methylene chloride is a representative halogenated hydrocarbon. Two or more kinds of organic solvents may be mixed and used.
- the cellulose acylate solution can be prepared by a general method comprising processing at a temperature of 0 ° C. or higher (room temperature or high temperature).
- the cellulose acylate solution can be prepared using a dope preparation method and apparatus in a normal solvent cast method.
- a halogenated hydrocarbon particularly methylene chloride
- the amount of cellulose acylate in the cellulose acylate solution is adjusted so that it is contained in an amount of 10 to 40% by mass in the resulting solution.
- the amount of cellulose acylate is more preferably 10 to 30% by mass.
- Arbitrary additives described later may be added to the organic solvent (main solvent).
- the cellulose acylate solution can be prepared by stirring cellulose acylate and an organic solvent at room temperature (0 to 40 ° C.). High concentration solutions may be stirred under pressure and heating conditions. Specifically, cellulose acylate and an organic solvent are placed in a pressure vessel and sealed, and stirred while heating to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil.
- the heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., more preferably 80 to 110 ° C.
- Each component may be roughly mixed in advance and then placed in a container. Moreover, you may put into a container sequentially. The container must be configured to allow stirring. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.
- an inert gas such as nitrogen gas
- a jacket type heating device can be used.
- the entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
- Stirring is preferably performed using a stirring blade provided inside the container.
- the stirring blade preferably has a length that reaches the vicinity of the wall of the container.
- a scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
- instruments such as a pressure gauge and a thermometer may be installed. Each component is dissolved in a solvent in a container.
- the prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.
- a cellulose acylate solution can also be prepared by a cooling dissolution method.
- the techniques described in [0115] to [0122] of JP-A-2007-86748 can be used.
- a cellulose acylate film is produced from the prepared cellulose acylate solution (dope) by a solvent cast method. It is preferable to add a retardation developer to the dope.
- the dope is cast on a drum or band and the solvent is evaporated to form a film.
- the dope before casting is preferably adjusted in concentration so that the solid content is 18 to 35%.
- the surface of the drum or band is preferably finished in a mirror state.
- the dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less.
- the obtained film can be peeled off from the drum or band and further dried with high-temperature air whose temperature is successively changed from 100 ° C. to 160 ° C. to evaporate the residual solvent.
- the above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.
- cellulose acylate solution Using the prepared cellulose acylate solution (dope), two or more layers can be cast to form a film.
- a cellulose acylate film by a solvent cast method.
- the dope is cast on a drum or band and the solvent is evaporated to form a film.
- the dope before casting is preferably adjusted in concentration so that the solid content is in the range of 10 to 40% by mass.
- the surface of the drum or band is preferably finished in a mirror state.
- a film may be produced while casting and laminating solutions containing cellulose acylate.
- the methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be used.
- a film can be formed by casting a cellulose acylate solution from two casting ports.
- JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, JP-A-61-104413, JP-A-61-158413, and JP-A-6- The method described in each publication of No. 134933 can be used. Further, a flow of a cellulose acylate film described in JP-A-56-162617 is wrapped in a cellulose acylate solution having a low viscosity, and the cellulose acylate solution having a high and low viscosity is simultaneously extruded. A rolling method can also be used.
- the film formed on the support by the first casting port is peeled off, and the second casting is performed on the side in contact with the support surface to produce a film.
- the same solution may be used, or two or more different cellulose acylate solutions may be used.
- a cellulose acylate solution corresponding to the function may be extruded from each casting port.
- the cellulose acylate solution in the present invention can be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, an ultraviolet absorbing layer, a polarizing layer, etc.).
- the timing of the addition is not particularly limited as long as it is added at the time of film formation. For example, you may add at the time of the synthesis
- a degradation inhibitor for example, an antioxidant, a peroxide decomposer, a radical inhibitor, a metal deactivator, an acid scavenger, an amine, etc.
- a degradation inhibitor may be added to the second protective film.
- Degradation inhibitors are described in JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854.
- the addition amount of the deterioration inhibitor is preferably 0.01 to 1% by mass, more preferably 0.01 to 0.2% by mass of the solution (dope) to be prepared.
- the addition amount is 0.01% by mass or more, the effect of the deterioration inhibitor is sufficiently exhibited, and if the addition amount is 1% by mass or less, the deterioration inhibitor bleeds out to the film surface And the like are less likely to occur.
- particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).
- fine particles as a matting agent to the second protective film.
- the fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate.
- Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.
- the silicon dioxide fine particles preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more.
- the apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.
- These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 ⁇ m, and these fine particles are present in the film as aggregates of primary particles, and 0.1 to 3.0 ⁇ m on the film surface. An unevenness of 3.0 ⁇ m is formed.
- the secondary average particle size is preferably 0.2 ⁇ m to 1.5 ⁇ m, more preferably 0.4 ⁇ m to 1.2 ⁇ m, and most preferably 0.6 ⁇ m to 1.1 ⁇ m.
- the primary and secondary particle sizes were determined by observing the particles in the film with a scanning electron microscope and determining the diameter of a circle circumscribing the particles as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.
- silicon dioxide fine particles for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used.
- Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.
- Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and while maintaining low turbidity of the optical film, friction This is particularly preferable because the effect of reducing the coefficient is great.
- a fine particle dispersion prepared by stirring and mixing a solvent and fine particles is prepared in advance, and this fine particle dispersion is added to a separately prepared small amount of cellulose acylate solution and stirred and dissolved. Further, the main cellulose acylate solution (dope solution) There is a way to mix.
- This method is a preferred preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate.
- the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 20%. Mass% is most preferred. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved.
- the amount of the matting agent fine particles added to the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, more preferably 0.08 to 0.16 g per m 3. Is most preferred.
- 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 winder used for producing the polarizing plate protective film in the present invention may be a commonly used winding machine such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, and the like. It can be wound up by a take-up method.
- the second protective film can be stretched.
- a desired retardation can be imparted to the polarizing plate protective film by the stretching treatment.
- the stretching direction of the cellulose acylate film is preferably either the width direction or the longitudinal direction. Methods for stretching in the width direction are described in, for example, JP-A-62-115035, JP-A-4-152125, JP-A-4284221, JP-A-4-298310, and JP-A-11-48271. Yes.
- the stretching of the second protective film is preferably carried out under heating conditions.
- the film can be stretched by a treatment during drying, and is particularly effective when the solvent remains.
- the film is stretched by adjusting the speed of the film transport roller so that the film winding speed is higher than the film peeling speed.
- the film can also be stretched by conveying while holding the width of the film with a tenter and gradually widening the width of the tenter. After the film is dried, it can be stretched using a stretching machine (preferably uniaxial stretching using a long stretching machine).
- the stretching of the second protective film is preferably performed at a temperature of (Tg ⁇ 5 ° C.) to (Tg + 40 ° C.), more preferably Tg to (Tg + 35 ° C.), using the glass transition temperature Tg of the film. And (Tg + 10 ° C.) to (Tg + 30 ° C.).
- Tg ⁇ 5 ° C. to (Tg + 40 ° C.)
- Tg + 35 ° C. using the glass transition temperature Tg of the film.
- Tg + 10 ° C. to (Tg + 30 ° C.).
- 130 ° C. to 200 ° C. is preferable.
- stretching can be performed at a temperature lower than that of the dry film, and in this case, 100 ° C. to 170 ° C. is preferable.
- the stretch ratio of the second protective film is preferably 1% to 200%, more preferably 5% to 150%.
- stretching in the width direction is preferably 1% to 200%, more preferably 5% to 150%, and particularly preferably 30 to 45%.
- the stretching speed is preferably 1% / min to 300% / min, more preferably 10% / min to 300% / min, and most preferably 30% / min to 300% / min.
- the second protective film is manufactured through a step (hereinafter, also referred to as “relaxation step”) of holding for a certain period of time at a draw ratio lower than the maximum draw ratio after being drawn to the maximum draw ratio. It is preferable.
- the stretching ratio in the relaxation step is preferably 50% to 99% of the maximum stretching ratio, more preferably 70% to 97%, and most preferably 90% to 95%.
- the time for the relaxation step is preferably 1 second to 120 seconds, and more preferably 5 seconds to 100 seconds.
- the said polarizing plate protective film can be preferably manufactured by including the shrinkage
- the film width is held by a pantograph type or linear motor type tenter.
- the film can be shrunk by gradually narrowing the interval between the clips in the conveying direction while stretching in the direction.
- Ichikin Kogyo Co., Ltd. is a stretching apparatus that specifically performs a stretching process that stretches either the longitudinal direction or the width direction of the film as described above and simultaneously shrinks the other and simultaneously increases the film thickness of the film.
- a company-made FITZ machine or the like can be desirably used. This apparatus is described in (Japanese Patent Laid-Open No. 2001-38802).
- the stretching ratio in the stretching step and the shrinkage rate in the shrinking step can be arbitrarily selected depending on the target in-plane retardation (Re) and thickness direction retardation (Rth).
- the stretching ratio in the stretching step is preferably 10% or more
- the shrinkage rate in the shrinking step is preferably 5% or more.
- it preferably includes a stretching step of stretching 10% or more in the width direction of the film and a shrinking step of contracting the transport direction of the film by 5% or more while holding the film in the width direction of the film.
- the shrinkage rate as used in the field of this invention means the ratio of the contracted length of the film after contraction with respect to the length of the film before contraction in the contraction direction.
- the shrinkage is preferably 5 to 40%, particularly preferably 10 to 30%.
- the second protective film is preferably arranged on the outer side (opposite side of the liquid crystal cell) when the polarizing plate of the present invention is incorporated in a liquid crystal display device.
- Using the second protective film as the outer film is preferable from the viewpoint of being hard to be damaged on the surface of the liquid crystal display device.
- the polarizing plate protective film (the first protective film and the second protective film) is subjected to alkali saponification treatment to provide adhesion with a polarizer material such as polyvinyl alcohol, and used as a polarizing plate protective film. Can do. Regarding the saponification method, the methods described in JP02-86748, [0211] and [0212] can be used.
- the alkali saponification treatment for the polarizing plate protective film is preferably performed in a cycle of immersing the film surface in an alkaline solution, neutralizing with an acidic solution, washing with water and drying.
- the alkaline solution include a potassium hydroxide solution and a sodium hydroxide solution, and the concentration of hydroxide ions is preferably in the range of 0.1 to 5.0 mol / L, and preferably 0.5 to 4.0 mol / L. More preferably, it is in the range of L.
- the alkaline solution temperature is preferably in the range of room temperature to 90 ° C, and more preferably in the range of 40 to 70 ° C.
- the manufacturing method of the polarizing plate of this invention includes the process of laminating
- the manufacturing method of the polarizing plate of this invention it is preferable to produce by the method of bonding a polarizing plate protective film to both surfaces of a polarizer using an adhesive agent by alkali treatment.
- the adhesive used for bonding the treated surface of the polarizing plate protective film and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, and vinyl latexes such as butyl acrylate. It is done.
- the polarizing plate of the present invention is a film transport direction during the production of the absorption axis of the polarizer and the polarizing plate protective film (the first protective film and the second protective film) from the viewpoint of roll-to-roll production suitability. It is preferable that the layers are stacked so that the direction orthogonal to the direction (TD direction) is substantially orthogonal.
- substantially orthogonal means that the angle formed by the absorption axis of the polarizer and the TD direction of the polarizing plate protective film is 85 ° to 95 °, preferably 89 ° to 91 °.
- FIG. 2 shows an example of the polarizing plate of the present invention.
- the absorption axis 13 of the polarizer 3 is orthogonal to the TD direction 11 when the first protective film 1 is manufactured and the TD direction 12 when the second protective film 2 is manufactured.
- the shape of the polarizing plate of the present invention is not only a polarizing plate in the form of a film piece cut into a size that can be incorporated into a liquid crystal display device as it is, but also produced in a long shape by continuous production, and in a roll shape.
- a polarizing plate in a rolled up mode (for example, a roll length of 2500 m or longer or 3900 m or longer) is also included.
- the width of the polarizing plate is preferably 1470 mm or more.
- the thickness of the polarizing plate is preferably from 40 ⁇ m to 80 ⁇ m, more preferably from 45 ⁇ m to 70 ⁇ m, still more preferably from 50 ⁇ m to 60 ⁇ m. If the thickness of the polarizing plate is 80 ⁇ m or less, the liquid crystal display is less likely to warp due to contraction of the polarizing plate, and is preferably 60 ⁇ m or less. On the other hand, if the thickness of the polarizing plate is 40 ⁇ m or more, it is preferable that bending during the polarizing plate processing hardly occurs and it is easy to pass through the processing line.
- the polarizing plate of this invention contains the polarizing plate and the polarizing plate protective film laminated
- the film that comes to the liquid crystal cell side when bonded to the liquid crystal cell is called an inner film
- the opposite film is called an outer film.
- the first protective film is an inner film
- the second protective film is an outer film.
- the polarizing plate of the present invention preferably further comprises a protective film on one surface of the polarizing plate and a separate film on the other surface. The protect film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate, product inspection, and the like.
- the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate.
- a separate film is used in order to cover the contact bonding layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal plate.
- the polarizing plate of the present invention is a function that is combined with an optical film having functional layers such as an antireflection film, a brightness enhancement film, a hard coat layer, a forward scattering layer, and an antiglare (antiglare) layer for improving the visibility of the display. It is also preferably used as a polarizing plate.
- the antireflection film, brightness enhancement film, other functional optical film, hard coat layer, forward scattering layer, and antiglare layer for functionalization are described in JP-A-2007-86748, [0257] to [0276].
- a functionalized polarizing plate can be created based on these descriptions.
- the polarizing plate of the present invention is preferably in any of the following aspects.
- a polarizing plate having a first protective film, a polarizer, and a second protective film in this order The first protective film is a film comprising a synthetic polymer, has a thickness of 30 ⁇ m or less, and an elastic modulus in the TD direction is 2.0 GPa to 2.5 GPa, The polarizer has a thickness of 20 ⁇ m;
- the polarizing plate in which the second protective film has an evaluation value A represented by the following formula (2 ′) of 5.7 to 9.0.
- Evaluation value A Elastic modulus (GPa) in the TD direction of the second protective film / Humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (Thickness ( ⁇ m) of the second protective film / First Protective film thickness ( ⁇ m)) 2
- the first protective film is a film comprising a synthetic polymer, has a thickness of 30 ⁇ m or less, and an elastic modulus in the TD direction is 2.0 GPa to 2.5 GPa,
- the polarizer has a thickness of 25 ⁇ m;
- Evaluation value A Elastic modulus (GPa) in the TD direction of the second protective film / Humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (Thickness ( ⁇ m) of the second protective film / First Protective film thickness ( ⁇ m)) 2 (3)
- the first protective film is a film comprising a synthetic polymer, has a thickness of 30 ⁇ m or less, and an elastic modulus in the TD direction is 2.0 GPa to 2.5 GPa,
- the polarizer has a thickness of 30 ⁇ m;
- Evaluation value A Elastic modulus (GPa) in the TD direction of the second protective film / Humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (Thickness ( ⁇ m) of the second protective film / First Protective film thickness ( ⁇ m)) 2
- the liquid crystal display device of the present invention has the polarizing plate of the present invention as at least one of a backlight side polarizing plate and a viewing side polarizing plate.
- the first protective film containing the (meth) acrylic resin in the polarizing plate of the present invention so as to be on the liquid crystal cell side (inner side).
- FIG. 3 A schematic diagram of a preferred example of the liquid crystal display device of the present invention is shown in FIG.
- the liquid crystal display device 100 shown in FIG. 3 has the polarizing plate 10 of the present invention having the first protective film 1, the polarizer 3, and the second protective film 2 on both sides of the liquid crystal cell 20.
- the liquid crystal display device 100 includes the polarizing plate 10 so that the first protective film 1 is disposed on the liquid crystal cell 20 side (inner side).
- the absorption axes of the polarizers 3 in the two polarizing plates 10 are preferably arranged so as to be orthogonal to each other.
- the polymerization conversion rate in this polymerization reaction was 96%, and the intrinsic viscosity ( ⁇ inh) in chloroform at 30 ° C. of the ring-opening copolymer constituting the obtained ring-opening copolymer solution was measured to be 0.64 dl. / G.
- the autoclave was charged with 4,000 parts of the obtained ring-opening copolymer solution, and carbonylchlorohydridotris (triphenylphosphine) ruthenium: RuHCl (CO) [P (C 6 H 5 ) was added to the ring-opening copolymer solution. 3 ] 3 0.48 part was added, and the hydrogenation reaction was performed by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm 2 and a reaction temperature of 165 ° C. After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. The reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a hydrogenated polymer (hereinafter “resin (a-1)”).
- the hydrogenation rate was measured by means of a 400 MHz 1H-NMR spectrum and found to be 99.9%. Further, the proportion of the structural unit e derived from 5-methoxycarbonylbicyclo [2.2.1] hept-2-ene in the resin (a-1) was measured by 400 MHz 1H-NMR spectrum, and about 3.7 ppm. Appearing in 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 2,5 .
- Resin (a-1) was dissolved in toluene to a concentration of 30%.
- the solution viscosity at room temperature of the obtained solution was 30,000 mPa ⁇ s.
- pentaerythrityltetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] as an antioxidant was added in an amount of 0.1 to 100 parts by weight of the resin (a-1).
- the resulting solution was filtered using a metal fiber sintered filter made by Nippon Pole with a pore diameter of 5 ⁇ m while controlling the flow rate of the solution so that the differential pressure was within 0.4 MPa.
- PET film with a thickness of 100 ⁇ m manufactured by Toray Industries, Inc.
- the obtained liquid layer is subjected to a primary drying treatment at 50 ° C., and further subjected to a secondary drying treatment at 90 ° C., and then peeled from the PET film to form a film 1 having a thickness of 25 ⁇ m. did.
- the film 1 thus obtained had a residual solvent amount of 0.5% by weight and a light transmittance of 93% or more.
- the polymerization conversion in this polymerization reaction was 95%, and the intrinsic viscosity ( ⁇ inh) in chloroform at 30 ° C. of the ring-opening copolymer constituting the obtained ring-opening copolymer solution was measured to be 0.68 dl. / G.
- the autoclave was charged with 4,000 parts of the obtained ring-opening copolymer solution, and carbonylchlorohydridotris (triphenylphosphine) ruthenium: RuHCl (CO) [P (C 6 H 5 ) was added to the ring-opening copolymer solution. 3 ] 3 0.48 part was added, and the hydrogenation reaction was performed by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm 2 and a reaction temperature of 165 ° C. After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released.
- reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a hydrogenated polymer (hereinafter referred to as “resin (a-2)”).
- resin (a-2) a hydrogenated polymer
- the hydrogenation rate was measured to be 99.9% according to 400 MHz 1H-NMR spectrum.
- the proportion of the structural unit e derived from bicyclo [2.2.1] hept-2-ene in the resin (a-2) is measured by 400 MHz 1H-NMR spectrum and appears in the vicinity of about 3.7 ppm. 8-methyl-8-methoxycarbonyl-9-methoxycarbonyltetracyclo [4.4.0.1 2,5 .
- Resin film (a-2) having a residual solvent amount of 0.4 wt% was obtained in the same manner as in film 1 except that resin (a-2) was used instead of resin (a-1). Was made.
- the resin film (a-2) was heated to 120 ° C. (Tg + 10 ° C.) in a tenter and stretched 1.2 times in the longitudinal direction in the in-plane direction of the film at a stretching rate of 300% / min.
- the film 25 was obtained by cooling while maintaining this state for 1 minute in an atmosphere of 20 ° C. (Tg-20 ° C.), further cooling at room temperature, and taking out from the tenter.
- the thickness was 25 ⁇ m.
- the resin film (a-2) is heated in a tenter to 120 ° C. (Tg + 10 ° C.) and stretched 1.05 times in the longitudinal direction in the in-plane direction of the film at a stretching rate of 300% / min, and then in the in-plane direction of the film The film is stretched 1.2 times in the transverse direction, and then cooled while maintaining this state for 1 minute in an atmosphere of 90 ° C. (Tg ⁇ 20 ° C.), further cooled at room temperature, and taken out from the tenter. Film 26 was obtained. The thickness was 25 ⁇ m.
- the acetyl substitution degree of cellulose acylate was measured by the following method. The degree of acetyl substitution was measured according to ASTM D-817-91.
- the elastic modulus of the film was measured according to the method described in JIS K7127. Let the winding direction of a film roll be a longitudinal direction (MD direction) and the width direction (TD direction) orthogonal to a longitudinal direction. A film sample having a length of 15 cm in the measurement direction and a width of 1 cm was cut out with the width direction as the measurement direction. The sample was placed on a strograph V10-C made by Toyo Seiki so that the chuck interval in the longitudinal direction was 10 cm, and a load was applied to widen the chuck interval at a stretching speed of 10 mm / min, and the force at that time was measured. did. The elastic modulus was calculated from the thickness, force, and elongation of the film previously measured with a micrometer.
- the humidity dimensional change rate of the film was measured by the following method. Let the winding direction of a film roll be a longitudinal direction (MD direction) and the width direction (TD direction) orthogonal to a longitudinal direction. Using the width direction as the measurement direction, a film sample having a length of 12 cm and a width of 3 cm was cut out in the measurement direction. Pin holes were made in the sample at intervals of 10 cm along the measurement direction, and after adjusting the humidity for 24 hours at 25 ° C. and a relative humidity of 60%, the distance between the pin holes was measured with a pin gauge. Next, after adjusting the humidity at 25 ° C. and 10% relative humidity for 24 hours, the interval between the pin holes was measured with a pin gauge.
- Humidity dimensional change rate in TD direction (%) [ ⁇ (Pin hole interval at 25 ° C., relative humidity 80%) ⁇ (Pin hole interval at 25 ° C., 10% relative humidity) ⁇ / (25 ° C., relative humidity Pin hole spacing at 60%)] ⁇ 100
- cellulose acetate powder is a dissolver type in which powder is put into a dispersion tank and stirred at a peripheral shear speed of 5 m / sec (shear stress 5 ⁇ 10 4 kgf / m / sec 2 ) at first.
- eccentric stirring shaft and were dispersed for 30 minutes during the stirring has an anchor blade to the central axis at a peripheral speed of 1 m / sec (shear stress 1 ⁇ 10 4 kgf / m / sec 2).
- the starting temperature of dispersion was 25 ° C., and the final temperature reached 48 ° C.
- the high-speed stirring was stopped, and the peripheral speed of the anchor blade was set to 0.5 m / sec and further stirred for 100 minutes to swell the cellulose acetate flakes.
- the inside of the tank was pressurized to 0.12 MPa with nitrogen gas. At this time, the oxygen concentration in the tank was less than 2 vol%, and the state of no problem was maintained in terms of explosion protection.
- the water content in the dope was confirmed to be 0.5% by mass or less, specifically 0.3% by mass.
- the swollen solution was heated from the tank to 50 ° C. with a jacketed pipe, and further heated to 90 ° C. by pressurization at 2 MPa to completely dissolve. The heating time was 15 minutes. Next, the temperature was lowered to 36 ° C., and a dope was obtained by passing through a filter medium having a nominal pore diameter of 8 ⁇ m. At this time, the primary pressure of filtration was 1.5 MPa, and the secondary pressure was 1.2 MPa.
- the filters, housings, and pipes exposed to high temperatures were made of Hastelloy alloy and had excellent corrosion resistance, and those having a jacket for circulating a heat medium for heat insulation and heating were used.
- the pre-concentration dope thus obtained was flushed at 80 ° C. in a normal pressure tank, and the evaporated solvent was recovered and separated by a condenser.
- the solid concentration of the dope after flashing was 21.8% by mass.
- the condensed solvent was sent to a recovery process to be reused as a solvent in the preparation process (recovery is carried out by a distillation process, a dehydration process, etc.).
- a flash tank having an anchor blade on the central axis was used for defoaming by stirring at a peripheral speed of 0.5 m / sec.
- the temperature of the dope in the tank was 25 ° C., and the average residence time in the tank was 50 minutes.
- the shear viscosity measured at 25 ° C. after collecting this dope was 450 (Pa ⁇ s) at a shear rate of 10 (sec ⁇ 1 ).
- bubbles were removed by irradiating the dope with weak ultrasonic waves. Thereafter, under a pressure of 1.5 MPa, first, a sintered fiber metal filter having a nominal pore diameter of 10 ⁇ m was passed, and then, a 10 ⁇ m sintered fiber filter was also passed. Respective primary pressures were 1.5 and 1.2 MPa, and secondary pressures were 1.0 and 0.8 MPa.
- the dope temperature after filtration was adjusted to 36 ° C. and stored in a 2000 L stainless steel stock tank. By using a stock tank having an anchor blade on the central axis and stirring constantly at a peripheral speed of 0.3 m / sec, an intermediate layer dope 1 was obtained. In addition, when the dope was prepared from the dope before concentration, no problem such as corrosion occurred at all in the wetted part of the dope.
- the dope 1 in the stock tank was fed by a feedback pump control using an inverter motor so that the primary pressure of the high precision gear pump became 0.8 MPa with a gear pump for primary pressure increase.
- the high-precision gear pump had a volume efficiency of 99.2% and a discharge rate variation of 0.5% or less.
- the discharge pressure was 1.5 MPa.
- dope 2 for support layer Matting agent (silicon dioxide (particle size 20 nm)) and release accelerator (citric acid ethyl ester (citric acid, monoethyl ester, diethyl ester, triethyl ester mixture)) and the intermediate
- the layer dope 1 was mixed through a static mixer to prepare a support layer dope 2.
- the addition amount was such that the total solid content concentration was 20.5% by mass, the matting agent concentration was 0.05% by mass, and the release accelerator concentration was 0.03% by mass.
- a matting agent (silicon dioxide (particle size: 20 nm)) was mixed with the intermediate layer dope 1 through a static mixer to prepare an air layer dope 3. The amount added was such that the total solid content concentration was 20.5% by mass and the matting agent concentration was 0.1% by mass.
- the cast dope film was dried on a drum with a drying air at 30 ° C. and peeled off from the drum with a residual solvent of 150%. During peeling, 20% stretching was performed in the transport direction (longitudinal direction). Furthermore, it dried further by conveying between the rolls of the heat processing apparatus, and the film 3 was manufactured.
- the produced cellulose acylate film had a residual solvent amount of 0.2% and a thickness of 25 ⁇ m.
- the flow rate of each dope is adjusted, the stretching strength in the transport direction and the stretching ratio in the width direction are adjusted, and the others are the same as the film 3, and the thickness, the elastic modulus in the TD direction, and the humidity dimensional change rate in the TD direction.
- Films 4 to 24 and 27 having different sizes were produced. Table 1 shows the thicknesses of the films 1 to 27, the elastic modulus in the TD direction, and the humidity dimensional change rate in the TD direction.
- a polyvinyl alcohol resin aqueous solution (liquid temperature: 147 ° C.) was supplied from the gear pump 1 to the biaxial extruder, defoamed, and then discharged by the gear pump 2.
- the discharged polyvinyl alcohol-based resin aqueous solution was cast from a T-type slit die (straight manifold hole die) onto a cast drum to form a film.
- the conditions for casting film formation are as follows.
- Cast drum diameter (R1) 3200 mm, Cast drum width 4.3m, Cast drum rotation speed: 8m / min, Cast drum surface temperature: 90 ° C Resin temperature at T-type slit die outlet: 95 ° C Drying was performed while alternately passing a plurality of drying rolls on the front and back surfaces of the obtained film under the following conditions.
- the polyvinyl alcohol film (length 4000 m, width 4 m, thickness 75 ⁇ m) produced above was immersed in warm water at 40 ° C. for 2 minutes, swelled, and stretched 1.30 times.
- the obtained film was prepared by using boric acid (Societa Chimica Ladderello sp. A company) 28.6 g / L, iodine (made by Junsei Kagaku) 0.25 g / L, potassium iodide (made by Junsei Kagaku) 1. It was immersed in an aqueous solution containing 0 g / L at 30 ° C. for 2 minutes and dyed with iodine and iodide.
- the film obtained by the dyeing treatment was treated for 5 minutes in a 50 ° C. aqueous solution containing 30.0 g / L of boric acid while being uniaxially stretched 5.0 times.
- the obtained film was dried at 70 ° C. for 9 minutes. Thereby, a polarizer having a thickness of 30 ⁇ m was obtained.
- a polyvinyl alcohol film having a length of 4000 m, a width of 4 m, and a thickness of 50 ⁇ m was prepared in the same manner as the polarizers 1 and 2, and the film was immersed in warm water at 40 ° C. for 2 minutes and swelled, and then 1.30 times Stretched.
- the obtained film was prepared by using boric acid (manufactured by Societa Chirda Ladderello sp.) 28.6 g / L, iodine (manufactured by Junsei Kagaku) 0.25 g / L, potassium iodide (manufactured by Junsei Kagaku) 1.
- Polyester urethane (Mitsui Takeda Chemical Co., Takelac XW-74-C154) 10 parts by weight and isocyanate cross-linking agent (Mitsui Takeda Chemical Co., Takenate WD-725) 1 part by weight are dissolved in water and the solid content is dissolved. A solution adjusted to 20% by mass was prepared. This was used as an adhesive.
- Evaluation value Elastic modulus (GPa) in the TD direction of the second protective film / humidity dimensional change rate (%) in the TD direction of the second protective film ⁇ (thickness ( ⁇ m) of the second protective film / first Protective film thickness ( ⁇ m)) 2 ⁇ ⁇ (30 / polarizer thickness ( ⁇ m)) ⁇ 1/2
- the films 1, 2, 25, and 26 used as the inner side films are the first protective films
- the films 3 to 24 and 27 used as the outer side films are the second protective films.
- the average lift of the four corners is particularly preferably ⁇ 2 mm or more and less than 4 mm, and is preferably A, ⁇ 8 mm or more and less than ⁇ 2 mm, or 4 mm or more and less than 16 mm is next preferred, and B is less than ⁇ 8 mm, or 16 mm or more. C.
- This example relates to a form having no hard coat layer on the outer side surface, but it is considered that the same tendency is observed when the hard coat layer is present on the surface.
- Elongated optical films 1, 2, 25, and 26 were prepared by the above method, and the surface was subjected to corona treatment. Subsequently, the long optical films 3 to 24 and 27 were subjected to saponification treatment. In order to sandwich the polarizer between the corona-treated optical film and the saponified tack film, using a polyvinyl alcohol-based adhesive, the roll-to-roll with a roll machine is applied to both sides of the polarizer, and at 70 ° C. for 10 minutes. Dried over.
- a combination of optical films shown in Table 2 was selected as an air side (viewing side) protective film and a cell side protective film, and a polarizing plate sample was prepared.
- a polarizing plate sample having a film length of 500 m, an absorption axis in the longitudinal direction, a slow axis in the direction perpendicular to the longitudinal direction, and both surfaces protected by the optical film was obtained.
- laminate film lamination A laminate film (film thickness: 38 ⁇ m) mainly composed of polyethylene terephthalate with a pressure-sensitive adhesive was attached to each of the produced polarizing plate samples on the air-side protective film side by roll-to-roll using a roll machine.
- a crosslinking agent manufactured by Nippon Polyurethane Co., Ltd., trade name “Coronate L” mainly composed of a compound having an isocyanate group with respect to 100 parts by mass of the solid content of the acrylic polymer solution;
- a silane coupling agent 0.02 part by mass of ⁇ -glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM-403”) is blended in this order to prepare an adhesive solution. did.
- the pressure-sensitive adhesive solution was uniformly coated on the cell side protective film side of the prepared polarizing plate sample with a slot die coater, passed through a 155 ° C. air circulating thermostat for 5 minutes, and the polarizing plate surface had a thickness of 15 ⁇ m.
- the pressure-sensitive adhesive layer was formed.
- a separate film film thickness: 38 ⁇ m
- polyethylene terephthalate as a main component was bonded with a roll machine in a roll-to-roll manner.
- a polarizing plate which is excellent in polarizing plate processing suitability and excellent in manufacturing suitability of a liquid crystal display device from the viewpoint of curling even if it is a thin film.
Abstract
Description
特許文献2には、偏光子の保護フィルムとして、偏光子の片側にアクリル系フィルムを有し、他方の片側にセルロースアシレートフィルムを有する偏光板が開示されている。
特許文献3には、偏光子の保護フィルムとして、偏光子の片側にアクリル系フィルム、ポリイミド系フィルム、又はノルボルネン系フィルムを有し、他方の片側にセルロースアシレートフィルムを有する偏光板が開示されている。
特許文献1の偏光板は、偏光子の保護フィルムとして、偏光子の一方の側にシクロオレフィン系ポリマー、他方の側にセルロースアシレートフィルムを有する構成であるため、偏光板製造後の乾燥が十分に行われ、かつシクロオレフィン系ポリマーの特徴が生かせると考えられる。
偏光板のカールはMD方向に発生するものも、TD方向に発生するものも、どちらも問題となり、重要である。しかし偏光板を構成する材料を設計する場合、特にTD方向に発生するカールの対策が重要である。この理由は、偏光板を作成するプロセスによるカールの調整のしやすさの違いによる。MD方向のカールについては、偏光板を構成するインナー側フィルム、偏光子、アウター側フィルムを貼合、乾燥するために搬送する時の搬送方向へのテンションを変えることでカールを調整できる幅が広い。しかしTD方向のカールについては、乾燥条件を変えることで僅かに調整できるだけで、制御する手段がない。そのため特にTD方向について、好ましいフィルムの組み合わせを設計することが重要となる。
ここでインナー側フィルムとは偏光子を挟む二枚の保護フィルムの内、液晶セル側に配置されるフィルムを指す。また、液晶セルの反対側に配置されるフィルムをアウター側フィルムと呼ぶ。
特許文献1に記載された偏光板においては、厚みが60μm以上の保護フィルムを用いているが、近年では更に薄膜の保護フィルムが求められている。また、保護フィルムを薄くすると、よりカールが発生しやすくなるという課題がある。
すなわち、偏光子の保護フィルムとして、偏光子の一方の側に合成ポリマーフィルムを含む第1の保護フィルム、他方の側に第2の保護フィルムを有する構成の偏光板において、偏光板がその断面図において第1の保護フィルムを内側に有する円弧形状をなすようにカール(マイナスカール)することを抑制するためには、第2の保護フィルムの厚み、TD方向の弾性率、及びTD方向の湿度寸法変化率を好適に設計する必要があることがわかった。
第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
上記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2GPa~2.5GPaであり、下記式(1)で表されるTD方向の湿度寸法変化率が0.1%以下であり、
上記第2の保護フィルムが、下記式(2)で表される評価値が7.0~11.0である、偏光板。
式(1):
TD方向の湿度寸法変化率(%)=[{(25℃、相対湿度80%におけるTD方向のフィルム長さ)-(25℃、相対湿度10%におけるTD方向のフィルム長さ)}/(25℃、相対湿度60%におけるTD方向のフィルム長さ)]×100
式(2):
評価値=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2×{(30/偏光子の厚み(μm))}1/2
[2]
上記第2の保護フィルムが、セルロースアシレートを含んでなるフィルムである、[1]に記載の偏光板。
[3]
上記第1の保護フィルムに含まれる合成ポリマーがシクロオレフィン系ポリマーである、[1]又は[2]に記載の偏光板。
[4]
上記式(2)で表される評価値が9.0~10.0である、[1]~[3]のいずれか一項に記載の偏光板。
[5]
偏光板の厚みが、80μm以下である、[1]~[4]のいずれか一項に記載の偏光板。
[6]
第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
上記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2.0GPa~2.5GPaであり、
上記偏光子の厚みが20μmであり、
上記第2の保護フィルムが、下記式(2’)で表される評価値Aが5.7~9.0である、偏光板。
式(2’):
評価値A=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2
[7]
第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
上記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2.0GPa~2.5GPaであり、
上記偏光子の厚みが25μmであり、
上記第2の保護フィルムが、下記式(2’)で表される評価値Aが6.5~10.0である、偏光板。
式(2’):
評価値A=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2
[8]
第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
上記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2.0GPa~2.5GPaであり、
上記偏光子の厚みが30μmであり、
上記第2の保護フィルムが、下記式(2’)で表される評価値Aが7.0~11.0である、偏光板。
式(2’):
評価値A=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2
[9]
液晶セルと、[1]~[8]のいずれか1項に記載の偏光板を少なくとも1枚有する液晶表示装置であって、上記偏光板における上記第1の保護フィルムが、上記液晶セル側に配置された液晶表示装置。
前記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2GPa~2.5GPaであり、下記式(1)で表されるTD方向の湿度寸法変化率が0.1%以下であり、
前記第2の保護フィルムが、下記式(2)で表される評価値が7.0~11.0である、偏光板である。
式(1):
TD方向の湿度寸法変化率(%)=[{(25℃、相対湿度80%におけるTD方向のフィルム長さ)-(25℃、相対湿度10%におけるTD方向のフィルム長さ)}/(25℃、相対湿度60%におけるTD方向のフィルム長さ)]×100
式(2):
評価値=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2×{(30/偏光子の厚み(μm))}1/2
また、偏光板においては、通常、偏光子の吸収軸に直交する方向がTD方向である。
以下、本発明の偏光板を構成する偏光子、及び保護フィルムについて説明する。
本発明の偏光板における偏光子としては、特に制限はなく、公知の偏光子を用いることができるが、ポリビニルアルコール系樹脂と、二色性色素とを含有することが好ましい。
ポリビニルアルコール系樹脂(以下、「PVA」とも言う)としては、ポリ酢酸ビニルを鹸化したポリマー素材が好ましいが、例えば不飽和カルボン酸、不飽和スルホン酸、オレフィン類、ビニルエーテル類のような酢酸ビニルと共重合可能な成分とを含有しても構わない。また、アセトアセチル基、スルホン酸基、カルボキシル基、オキシアルキレン基等を含有する変性PVAも用いることができる。
この他、本発明における偏光子には、特許第3021494号公報に記載されている1、2-グリコール結合量が1.5モル%以下のPVAフィルム、特開2001-316492号公報に記載されている5μm以上の光学的異物が100cm2当たり500個以下であるPVAフィルム、特開2002-030163号に記載されているフィルムのTD方向の熱水切断温度斑が1.5℃以下であるPVAフィルム、更にグリセリンなどの3~6価の多価アルコ-ルを1~100質量%混合した溶液や、特開平06-289225号公報に記載されている可塑剤を15質量%以上混合した溶液から製膜したPVAフィルムを好ましく用いることができる。
これらの中でも、本発明における偏光子に用いる前記ポリビニルアルコール系樹脂としては、ポリ酢酸ビニルをけん化したものが製造コストの観点から好ましい。なお、前記ポリ酢酸ビニルのけん化度については特に制限はないが、例えば、けん化度90%以上とすることが好ましく、95%以上とすることがより好ましく、99%以上とすることが特に好ましい。
本発明における偏光子は、二色性色素を含むことが好ましい。ここで、二色性色素とは、本明細書においては、方向により吸光度の異なる色素のことを言い、例えば、ヨウ素イオン、ジアゾ系色素、キノン系色素、その他公知の二色性染料などが含まれる。前記二色性色素としては、I3 -やI5 -などの高次のヨウ素イオン若しくは二色性染料を好ましく使用することができる。
本発明では高次のヨウ素イオンが特に好ましく使用される。高次のヨウ素イオンは、「偏光板の応用」永田良編、CMC出版や工業材料、第28巻、第7号、p.39~p.45に記載されているようにヨウ素をヨウ化カリウム水溶液に溶解した液及びホウ酸水溶液の少なくとも一方にPVAを浸漬し、PVAに吸着・配向した状態で生成することができる。
本発明における偏光子の製造方法としては、特に制限はない。
例えば、PVAとヨウ素とを含有する偏光子の製造方法としては、前記PVAをフィルム化した後、ヨウ素を導入して偏光子を構成することが好ましい。PVAフィルムの製造は、特開2007-86748号公報の〔0213〕~〔0237〕に記載の方法、特許登録第3342516号明細書、特開平09-328593号公報、特開2001-302817号公報、特開2002-144401号公報等を参考にして行うことができる。
前記PVA系樹脂溶液の調製工程では、水に対して攪拌しながらPVA系樹脂を添加し、PVA系樹脂を水又は有機溶媒に溶解した原液を調製することが好ましい。原液中のポリビニルアルコール系樹脂の濃度は、好ましくは5~20質量%である。また、得られたスラリーを脱水し、含水率40%程度のポリビニルアルコール系樹脂ウェットケーキを一度調製してもよい。更にその後添加剤を加える場合は、例えば、PVAのウェットケーキを溶解槽に入れ、可塑剤、水を加え、槽底から水蒸気を吹き込みながら攪拌する方法が好ましい。内部樹脂温度は50~150℃に加温することが好ましく、系内を加圧してもよい。
前記流延工程は、上記にて調製したPVA系樹脂溶液原液を流延して成膜する方法が一般に好ましく用いられる。流延の方法としては、特に制限はないが、加熱した前記PVA系樹脂溶液原液を2軸押し出し機に供給し、ギアポンプにより排出手段(好ましくはダイ、より好ましくはT型スリットダイ)から支持体上に流涎して製膜することが好ましい。また、ダイからの排出される樹脂溶液の温度については特に制限はない。
前記支持体としては、キャストドラムが好ましく、ドラムの直径、幅、回転速度、表面温度については、特に制限はない。その中でも、前記キャストドラムの直径(R1)は2000~5000mmであることが好ましく、2500~4500mmであることが特に好ましく、3000~3500mmであることが特に好ましい。
前記キャストドラムの幅は2~6mであることが好ましく、3~5mであることが特に好ましく、4~5mであることが特に好ましい。
前記キャストドラムの回転速度は2~20m/分であることが好ましく、4~12m/分であることが特に好ましく、5~10m/分であることが特に好ましい。
前記キャストドラムのキャストドラム表面温度は40~140℃であることが好ましく、60~120℃であることが特に好ましく、80~100℃であることが特に好ましい。
前記T型スリットダイ出口の樹脂温度は40~140℃であることが好ましく、60~120℃であることが特に好ましく、80~100℃であることが特に好ましい。
その後、得られたロールの裏面と表面とを乾燥ロールに交互に通過させながら乾燥を行なうことが好ましい。前記乾燥ロールの直径、幅、回転速度、表面温度については、特に制限はない。その中でも、前記乾燥ロールの直径の直径(R2)は200~450mmであることが好ましく、250~400mmであることが特に好ましく、300~350mmであることが特に好ましい。
また、得られたフィルムの長さについても特に制限はなく、2000m以上、好ましくは4000m以上の長尺のフィルムとすることができる。フィルムの幅についても、特に制限はないが、2~6mであることが好ましく、3~5mであることが好ましい。
前記膨潤工程は、水のみで行うことが好ましいが、特開平10-153709号公報に記載されているように、光学性能の安定化及び、製造ラインでのポリビニルアルコール系樹脂フィルムのシワ発生回避のために、ポリビニルアルコール系樹脂フィルムをホウ酸水溶液により膨潤させて、偏光板基材の膨潤度を管理することもできる。
また、膨潤工程の温度、時間は、任意に定めることができるが、10℃~60℃、5秒~2000秒が好ましい。
なお、膨潤工程のときにわずかに延伸を行ってもよく、例えば1.05倍~1.5倍に延伸する態様が好ましく、1.3倍程度に延伸する態様がより好ましい。
前記染色工程は、特開2002-86554号公報に記載の方法を用いることができる。また、染色方法としては浸漬だけでなく、ヨウ素あるいは染料溶液の塗布あるいは噴霧等、任意の手段が可能である。また、特開2002-290025号公報に記載されているように、ヨウ素の濃度、染色浴温度、浴中の延伸倍率、及び浴中の浴液を攪拌させながら染色させる方法を用いてもよい。
前記二色性色素として高次のヨウ素イオンを用いる場合、高コントラストの偏光板を得るためには、染色工程はヨウ素をヨウ化カリウム水溶液に溶解した液を用いることが好ましい。この場合のヨウ素-ヨウ化カリウム水溶液のヨウ素とヨウ化カリウムの質量比については特開2007-086748号公報に記載の態様を用いることができる。
また、特許第3145747号公報に記載されているように、染色液にホウ酸、ホウ砂等のホウ素系化合物を添加してもよい。
前記硬膜工程は、PVAフィルムを架橋剤溶液に浸漬、又は溶液を塗布して架橋剤を含ませるのが好ましい。また、特開平11-52130号公報に記載されているように、硬膜工程を数回に分けて行うこともできる。
前記架橋剤としては米国再発行特許第232897号明細書に記載のものが使用でき、特許第3357109号公報に記載されているように、寸法安定性を向上させるため、架橋剤として多価アルデヒドを使用することもできるが、ホウ酸類が最も好ましく用いられる。硬膜工程に用いる架橋剤としてホウ酸を用いる場合には、ホウ酸-ヨウ化カリウム水溶液に金属イオンを添加してもよい。金属イオンとしては塩化亜鉛が好ましいが、特開2000-35512号公報に記載されているように、塩化亜鉛の変わりに、ヨウ化亜鉛などのハロゲン化亜鉛、硫酸亜鉛、酢酸亜鉛などの亜鉛塩を用いることもできる。
また、塩化亜鉛を添加したホウ酸-ヨウ化カリウム水溶液を作製し、PVAフィルムを浸漬させて硬膜を行ってもよく、特開2007-086748号公報に記載の方法を用いることができる。
前記延伸工程は、米国特許2,454,515号明細書などに記載されているような、縦一軸延伸方式、若しくは特開2002-86554号公報に記載されているようなテンター方式を好ましく用いることができる。好ましい延伸倍率は2倍~12倍であり、更に好ましくは3倍~10倍である。また、延伸倍率と原反厚さと偏光子厚さの関係は特開2002-040256号公報に記載されている(保護フィルム貼合後の偏光子膜厚/原反膜厚)×(全延伸倍率)>0.17としたり、最終浴を出た時の偏光子の幅と保護フィルム貼合時の偏光子幅の関係は特開2002-040247号公報に記載されている0.80≦(保護フィルム貼合時の偏光子幅/最終浴を出た時の偏光子の幅)≦0.95としたりすることも好ましく行うことができる。
前記乾燥工程は、特開2002-86554号公報で公知の方法を使用できるが、好ましい温度範囲は30℃~100℃であり、好ましい乾燥時間は30秒~60分である。また、特許第3148513号公報に記載されているように、水中退色温度を50℃以上とするような熱処理を行ったり、特開平07-325215号公報や特開平07-325218号公報に記載されているように温湿度管理した雰囲気でエージングしたりすることも好ましく行うことができる。
また膜厚が薄い偏光子は、特許第4691205号公報や特許第4751481号公報に記載の塗布法を用いた製造方法により形成する事ができる。なお、膜厚の制御は、公知の方法で制御することができ、例えば前記流延工程におけるダイスリット幅や、延伸条件を適切な値に設定することで制御できる。
偏光子の膜厚は、特に限定されないが、偏光度と反りの観点から5μm以上30μm以下が好ましく、10μm以上20μm以下がより好ましい。偏光子の膜厚が30μm以下であれば偏光子の収縮力が増加せず、これを貼合した液晶パネルの反りが大きくならないため好ましい。一方、偏光子の膜厚が5μm以上であれば、偏光子を透過する一方の偏光の光を十分に吸収することができ、偏光度が低下しないため好ましい。
次に、本発明の偏光板に用いられる保護フィルム(「偏光板保護フィルム」とも言う)について説明する。
本発明の偏光板は、第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する。
前記第1の保護フィルムは、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2GPa~2.5GPaであり、下記式(1)で表されるTD方向の湿度寸法変化率が0.1%以下である。
式(1):
TD方向の湿度寸法変化率(%)=[{(25℃、相対湿度80%におけるTD方向のフィルム長さ)-(25℃、相対湿度10%におけるTD方向のフィルム長さ)}/(25℃、相対湿度60%におけるTD方向のフィルム長さ)]×100
前記第2の保護フィルムは、下記式(2)で表される評価値が7.0~11.0である。
式(2):
評価値=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2×{(30/偏光子の厚み(μm))}1/2
第1の保護フィルムは、合成ポリマーを含んでなるフィルムである。
前記合成ポリマーとしては、ノルボルネン等のシクロオレフィン系ポリマー、ポリエチレンテレフタレート、ポリエチレンナフタレート、ポリカーボネート、ポリスチレン、ポリアリレート、ポリスルフォン、(メタ)アクリル系樹脂などが好ましく、(メタ)アクリル系樹脂、シクロオレフィン系ポリマーがより好ましく、湿度に対する安定性の観点からシクロオレフィン系ポリマーが最も好ましい。
シクロオレフィン系ポリマーについて詳しく説明する。
(シクロオレフィン系付加重合体)
シクロオレフィン系ポリマーは下記一般式(1)で表される構造単位(a)と下記一般式(2)で表される構造単位(b)を適度の比率で含む環状オレフィン系付加重合体が好ましい。
本発明に用いることのできるシクロオレフィン系ポリマーとしては、下記一般式(5)及び(6)のモノマーユニットを有する開環重合体も好ましく用いることができる。
更に、R1とR2、R3とR4又はR2とR3は、互いに結合して、単環構造若しくは他の環が縮合して多環構造を有する炭素環又は複素環を形成していてもよく、形成される炭素環又は複素環は芳香環であってもよいし非芳香環であってもよい。]
上記一般式(5)及び(6)のポリマーは下記の(イ)~(ニ)に示す単量体の(共)重合体(以下、「特定重合体」ともいう。)として合成される。(イ)下記一般式(7)で表される化合物(以下、「特定単量体d」ともいう。)の開環重合体。(ロ)特定単量体dと、当該特定単量体dと共重合可能な化合物(以下、「共重合性単量体」ともいう。)との開環重合体。(ハ)上記(イ)の開環重合体又は(ロ)の開環重合体の水素添加物。(ニ)上記(イ)の開環重合体又は(ロ)の開環重合体をフリーデルクラフト反応により環化して得られた化合物若しくはその水素添加物。
炭素原子数1~30の炭化水素基としては、例えばメチル基、エチル基、プロピル基等のアルキル基;シクロペンチル基、シクロヘキシル基等のシクロアルキル基;ビニル基、アリル基、プロペニル基等のアルケニル基などが挙げられる。
連結基としては、例えば炭素原子数1~10の2価の炭化水素基〔例えば、-(CH2)q-(式中、qは1~10の整数)で表されるアルキレン基〕;酸素原子、窒素原子、イオウ原子若しくはケイ素原子を含む連結基〔例えば、カルボニル基(-CO-)、オキシカルボニル基(-O(CO)-)、スルホン基(-SO2-)、エーテル結合(-O-)、チオエーテル結合(-S-)、イミノ基(-NH-)、アミド結合(-NHCO-,-CONH-)、シロキサン結合(-OSi(R9)2-(式中、R9はメチル、エチル等のアルキル基))〕、あるいはこれらの2種以上が結合されたものなどが挙げられる。
また、一般式(9)において、nは0~5の整数、好ましくは0~2の整数、より好ましくは0である。nの値が小さいものほど得られる特定重合体のガラス転移温度が高くなるので好ましく、特にnが0である特定単量体dは、その合成が容易である点で好ましい。
また、特定単量体dとしては、一般式(7)においてmが1でありpが0であるものは、ガラス転移温度の高い特定重合体が得られる点で好ましい。
他の共重合性単量体としては、例えばシクロブテン、シクロペンテン、シクロヘプテン、シクロオクテン、ジシクロペンタジエンなどのシクロオレフィンを挙げることができる。シクロオレフィンの炭素原子数としては、4~20が好ましく、更に好ましくは5~12である。更にポリブタジエン、ポリイソプレン、スチレン-ブタジエン共重合体、エチレン-非共役ジエン共重合体、ポリノルボルネンなどの主鎖にオレフィン性不飽和結合を有する不飽和炭化水素系ポリマーなどの存在下に特定単量体d及び必要に応じて特定単量体eを重合させてもよく、このようにして得られる特定重合体は、耐衝撃性の大きい樹脂の原料として有用である。
また、特定重合体の分子量分布は、上記のMw/Mnが通常1.5~10、好ましくは2~8、更に好ましくは2.5~5、特に好ましくは2.5~4.5である。
単量体の開環重合反応は、メタセシス触媒の存在下に行われる。
このメタセシス触媒は、(a)W、Mo及びReの化合物から選ばれた少なくとも1種と、(b)デミングの周期律表IA族元素(例えばLi、Na、Kなど)、IIA族元素(例えばMg、Caなど)、IIB族元素(例えばZn、Cd、Hgなど)、IIIB族元素(例えばB、Alなど)、IVA族元素(例えばTi、Zrなど)あるいはIVB族元素(例えばSi、Sn、Pbなど)の化合物であって、少なくとも1つの当該元素-炭素結合あるいは当該元素-水素結合を有するものから選ばれた少なくとも1種との組合せからなる触媒である。またこの場合に触媒の活性を高めるために、後述の添加剤(c)が添加されたものであってもよい。
(b)成分の具体例としては、n-C4H9Li、(C2H5)3Al、(C2H5)2AlCl、(C2H5)1.5AlCl1.5、(C2H5)AlCl2、メチルアルモキサン、LiHなど特開平1-240517号公報に記載の化合物を挙げることができる。
(c)成分の代表例としては、アルコール類、アルデヒド類、ケトン類、アミン類などが好適に用いることができるが、更に特開平1-240517号公報に記載の化合物を使用することができる。
(a)成分と(b)成分との割合は、金属原子比で「(a):(b)」が1:1~1:50、好ましくは1:2~1:30の範囲である。
(a)成分と(c)成分との割合は、モル比で「(c):(a)」が0.005:1~15:1、好ましくは0.05:1~7:1の範囲である。
特定重合体の分子量の調節は重合温度、触媒の種類、溶媒の種類によっても行うことができるが、本発明においては、分子量調節剤を反応系に共存させることにより調節することが好ましい。好適な分子量調節剤としては、例えばエチレン、プロペン、1-ブテン、1-ペンテン、1-ヘキセン、1-ヘプテン、1-オクテン、1-ノネン、1-デセンなどのα-オレフィン類及びスチレンを挙げることができ、これらのうち、1-ブテン、1-ヘキセンが好ましい。
これらの分子量調節剤は、単独であるいは2種以上を併用して用いることができる。分子量調節剤の使用量としては、重合反応に供される特定単量体1モルに対して0.005~0.6モル、好ましくは0.02~0.5モルである。
開環重合反応において用いられる溶媒としては、例えばペンタン、ヘキサン、ヘプタン、オクタン、ノナン、デカンなどのアルカン類;シクロヘキサン、シクロヘプタン、シクロオクタン、デカリン、ノルボルナンなどのシクロアルカン類;ベンゼン、トルエン、キシレン、エチルベンゼン、クメンなどの芳香族炭化水素類;クロロブタン、ブロムヘキサン、塩化メチレン、ジクロロエタン、ヘキサメチレンジブロミド、クロロベンゼン、クロロホルム、テトラクロロエチレンなどのハロゲン化炭化水素化合物類;酢酸エチル、酢酸n-ブチル、酢酸iso-ブチル、プロピオン酸メチルなどの飽和カルボン酸エステル類;ジメトキシエタン、ジブチルエーテル、テトラヒドロフランなどのエーテル類を挙げることができ、これらは単独であるいは2種以上を併用して用いることができる。これらの中でも、上記芳香族炭化水素類が好ましい。
溶媒の使用量としては、溶媒:特定単量体(重量比)が、通常1:1~10:1となる量、好ましくは1:1~5:1となる量である。
以上の開環重合により得られる開環共重合体は、そのまま特定重合体として使用することもできるが、当該開環共重合体において残留するオレフィン性不飽和結合を水素添加された水素添加物とすることが好ましい。
これらの水素添加触媒は、開環重合体:水素添加触媒(質量比)が、1:1×10-6~1:2となる割合で使用される。
更に本発明のシクロオレフィン系ポリマーフィルムはモノマーユニットの親水性を下記式(G)の範囲にすることにより、弾性率の湿度依存性を調節できる。0≦logP(i)×Mi≦4.5 (G)
ここでlogP(i)はi番目の構造単位のオクタノール/水分配係数、Miはi番目の構造単位のモル分率である。オクタノール/水分配係数は実測あるいは計算により求めることができる。
更に好ましくは、1≦logP(i)×Mi≦4であり、最も好ましくは2≦logP(i)×Mi≦3.5である。
logP(i)×Miが上記範囲であると、吸水による光学特性変化、寸度変化が小さく、また、偏光子のポリビニルアルコールとの密着が十分である。
本発明においては、特定重合体よりなる熱可塑性シクロオレフィン系樹脂、好ましくは熱可塑性ノルボルネン系樹脂は溶融成形法あるいは溶液流延法(溶剤キャスト法)などによりフィルムに成形することができるが、厚みの均一性が高く、表面平滑性が良好な加工前フィルムが得られる点で、溶剤キャスト法を利用することが好ましい。溶剤キャスト法としては、例えば、熱可塑性シクロオレフィン系樹脂を溶媒に溶解又は分散させることにより、熱可塑性シクロオレフィン系樹脂が適度の濃度で含有されてなるフィルム形成液を調製し、このフィルム形成液を適当なキャリヤー上に注ぐか又は塗布し、これを乾燥した後、キャリヤーから剥離させる方法が挙げられる。
また、混合溶媒中に占める貧溶媒の割合は、好ましくは50重量%以下、更に好ましくは30重量%以下、特に好ましくは15重量%以下、最も好ましくは10重量%以下である。また、貧溶媒の沸点と良溶媒の沸点との差は好ましくは1℃以上、更に好ましくは5℃以上、特に好ましくは10℃以上、最も好ましくは20℃以上であり、特に貧溶媒の沸点が良溶媒の沸点より高いことが好ましい。
また、得られる加工前フィルムの表面平滑性を向上させることを目的として、フィルム形成液にレベリング剤を添加してもよい。かかるレベリング剤としては、一般的なものであれは種々のものを用いることができ、その具体例としては、フッ素系ノニオン界面活性剤、特殊アクリル樹脂系レベリング剤、シリコーン系レベリング剤などが挙げられる。
また、フィルム形成液を繰り返し塗布することにより、得られる加工前フィルムの厚みや表面平滑性を制御することもできる。
表面処理の方法としては、一般的に行われている親水化処理方法、例えばアクリル系樹脂やスルホン酸塩基含有樹脂をコーテイングやラミネートにより積層する方法、あるいは、コロナ放電処理等によりフィルム表面の親水性を向上させる方法等が挙げられる。
加工前フィルムの厚み分布は、平均値に対して通常±20%以内、好ましくは±10%以内、更に好ましくは±5%以内、特に好ましくは±3%以内である。また、1cmあたりの厚みの変動は、通常は10%以下、好ましくは5%以下、更に好ましくは1%以下、特に好ましくは0.5%以下である。加工前フィルムの厚み分布を上記の範囲内に制御することにより、当該加工前フィルムに対して延伸配向処理を行う際に、位相差ムラが発生することを防止することができる。
すなわち、テンター法による横一軸延伸法、ロール間圧縮延伸法、円周の異なる二組のロールを利用する縦一軸延伸法等あるいは横一軸と縦一軸を組合わせた二軸延伸法、インフレーション法による延伸法等を用いることができる。
一軸延伸法の場合、延伸速度は通常1~5,000%/分であり、好ましくは50~1,000%/分であり、更に好ましくは100~1,000%/分であり、特に好ましくは100~500%/分である。
二軸延伸法の場合、同時2方向に延伸を行う場合や一軸延伸後に最初の延伸方向と異なる方向に延伸処理する場合がある。この時、延伸後のフィルムの屈折率楕円体の形状を制御するための2つの延伸軸の交わり角度は、所望の特性により決定されるため特に限定はされないが、通常120~60度の範囲である。また、延伸速度は各延伸方向で同じであってもよく、異なっていてもよく、通常1~5,000%/分であり、好ましくは50~1,000%/分であり、更に好ましくは100~1,000%/分であり、特に好ましくは100~500%/分である。
延伸倍率は、所望の特性により決定されるため特に限定はされないが、通常1.01~10倍、好ましくは1.03~5倍、更に好ましくは1.03~3倍である。延伸倍率が上記範囲であると、位相差の制御が容易である。
寸法収縮率を上記範囲内にするためには、熱可塑性シクロオレフィン系樹脂の原料である、例えば特定単量体a、特定単量体bあるいはその他の共重合性単量体の選択に加え、キャスト方法や延伸方法によりコントロールすることが可能である。
なお、延伸配向処理を施していない状態の加工前フィルムの加熱による寸法収縮率は、100℃における加熱を500時間行った場合に、通常5%以下、好ましくは3%以下、更に好ましくは1%以下、特に好ましくは0.5%以下である。
ここに、「輝点」とは、特定位相差フィルムをクロスニコル状態の偏光板に挟んで観察したときに肉眼で確認される部分的な光の漏れであり、通常外径1μm以上(円形のものであればその直径、その他の形状のものであれば長手方向の長さ)のものを計測する。
もちろん、要求される性能によっては、これよりも小さいものを輝点として計測する場合がある。また、かかる輝点は、微小領域における位相差の部分的なムラが原因と考えられている。すなわち、加工前フィルム中に異物や泡等が存在すると、それらが肉眼では確認できないような大きさであっても、延伸加工した際に、異物や泡等が存在する部分に応力が集中し、この応力が集中した部分の位相差が周辺部分の位相差と異なってしまうことがあり、係る位相差の違いにより光が漏れてしまうと考えられている。
ここでいう「異物」とは、特定位相差フィルムに光を透過させた場合に、実質的に光の透過を妨げるものである。このような異物が特定位相差フィルム中に存在する場合には、透過光強度に影響を与え、液晶表示素子等に用いた場合、画素抜けや特性の低下を招くおそれがある。
なお、計測すべき異物の大きさは、通常外径1μm以上(円形のものであればその直径、その他の形状のものであれば長手方向の長さ)であるが、要求される性能によっては、これよりも小さいものを異物として計測する場合がある。
第1の保護フィルムは偏光子との密着を確保するため、少なくとも一方の表面が親水化処理されていることが好ましい。
表面処理方法としては、例えば特開2000-24167号、特開平10-130402号、特開2002-148436号、特開2002-90546号、特開2001-350017号に記載の接着層を設ける方法、また、特開2001-350018号に記載のコロナ放電処理等の表面処理により親水性を付与することもできる。
延伸温度は、フィルム原料である熱可塑性樹脂組成物のガラス転移温度近傍であることが好ましく、具体的には、好ましくは(ガラス転移温度-30℃)~(ガラス転移温度+100℃)、より好ましくは(ガラス転移温度-20℃)~(ガラス転移温度+80℃)の範囲内である。延伸温度が(ガラス転移温度-30℃)未満であると、充分な延伸倍率が得られないおそれがある。逆に、延伸温度が(ガラス転移温度+100℃)超えると、樹脂組成物の流動(フロー)が起こり、安定な延伸が行えないおそれがある。
面積比で定義した延伸倍率は、好ましくは1.1~25倍、より好ましくは1.3~10倍である。延伸倍率が1.1倍未満であると、延伸に伴う靭性の向上につながらないおそれがある。延伸倍率が25倍を超えると、延伸倍率を上げるだけの効果が認められないおそれがある。
延伸速度は、一方向で、好ましくは10~20,000%/min、より好ましく100~10,000%/minである。延伸速度が10%/min未満であると、充分な延伸倍率を得るために時間がかかり、製造コストが高くなるおそれがある。延伸速度が20,000%/minを超えると、延伸フィルムの破断等が起こるおそれがある。
第1の保護フィルムの厚さは、ムラの発生しにくさの観点から30μm以下であり、好ましくは1~30μm、より好ましくは5~30μm、更に好ましくは10~20μmである。厚さが30μmを超えると、透明性が低下するだけでなく、透湿性が小さくなり、水系接着剤を用いた場合、その溶剤である水の乾燥速度が遅くなるおそれがある。また高温高湿の耐久試験を掛けた時に液晶表示装置の画面内に光漏れのムラが発生するおそれがある。厚さが1μm以上であると、強度が向上し、偏光板の耐久性試験を行うと捲縮が大きくならず好ましい。
前記第1の保護フィルムの厚さは、フィルム断面の光学顕微鏡観察により測定される平均膜厚である。
第1の保護フィルムは、TD方向の下記式(1)で表される湿度寸法変化率が、光学特性の安定性の観点から、0.1%以下であることが好ましく、0%以上0.1%以下がより好ましく、0%以上0.05%以下が更に好ましい。
TD方向の湿度寸法変化率(%)=[{(25℃、相対湿度80%におけるTD方向のフィルム長さ)-(25℃、相対湿度10%におけるTD方向のフィルム長さ)}/(25℃、相対湿度60%におけるTD方向のフィルム長さ)]×100
・・・式(1)
前記第1の保護フィルムをインナー側フィルムとすることで、高温高湿下で長期使用した場合のムラ発生が抑えられるという観点で好ましい。
第2の保護フィルムは、下記式(2)で表される評価値が7.0~11.0である。
式(2):
評価値=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2×{(30/偏光子の厚み(μm))}1/2
なお、第2の保護フィルムのTD方向の湿度寸法変化率は、下記式(1)で表される。
式(1):
TD方向の湿度寸法変化率(%)=[{(25℃、相対湿度80%におけるTD方向のフィルム長さ)-(25℃、相対湿度10%におけるTD方向のフィルム長さ)}/(25℃、相対湿度60%におけるTD方向のフィルム長さ)]×100
まず、偏光板のカール浮き量と第2の保護フィルムのTD方向の湿度寸法変化率についての関係を図4に示す。図4より、第2の保護フィルムのTD方向の湿度寸法変化率と偏光板のカール浮き量については、関係性を見出すことはできない。
次に、カール浮き量について、第2の保護フィルムのTD方向の湿度寸法変化率、及び第2の保護フィルムのTD方向の弾性率との関連性を調べた。第2の保護フィルムのTD方向の湿度寸法変化率、及び第2の保護フィルムのTD方向の弾性率とカール浮き量の等高線を示したカールマップを図5に示す。
図5より、カールの等高線はTD方向の弾性率とTD方向の湿度寸法変化率が同時に上下する方向に現れることが分かった。これより、TD方向の弾性率とTD方向の湿度寸法変化率の比に好ましい範囲があると推察される。
そこで、下記式(3)で表される評価値1とカール浮き量の関係を調べた。
式(3):
評価値1=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)
図6には、偏光子のポリビニルアルコールの膜厚が30μmであり、第1の保護フィルムであるシクロオレフェン系ポリマーフィルムの膜厚が25μmである場合に、第2の保護フィルムであるセルロースアシレートフィルムの膜厚が15μm、20μm、及び25μmの場合のカール浮き量と評価値1の関係を示した。
図6より、セルロースアシレートフィルムの厚みが一定である場合は、評価値1とカール浮き量の関係が直線に乗るが、厚みが異なる場合は対応しないことが分かる。
そこで、厚みの補正を加えた下記式(4)で表される評価値2とカール浮き量との関係について検討した。
式(4):
評価値2=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2
図7に、偏光子のポリビニルアルコールの膜厚が30μmである場合のカール浮き量と評価値2の関係を示した。
図7より、カール浮き量と評価値2とは対応が良いことが分かる。
次に、偏光子の厚みを変化させた場合について、評価値2とカール浮き量との関係について検討した。
図8に、偏光子のポリビニルアルコールの膜厚が30μmである場合、及び20μmである場合のカール浮き量と評価値2の関係を示した。
図8より、偏光子の厚みが変わると評価値2の好ましい領域が変化することが分かった。より詳細には、偏光子の厚みが減少するとカール浮き量と評価値2の対応関係を示す直線の傾きが低減することが分かった。
そして、偏光子の厚みの補正を加えた評価値として、下記式(2)で表される評価値としたものである。
式(2):
評価値=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2×{(30/偏光子の厚み(μm))}1/2
図9に、式(2)による評価値(評価値3)とカール浮き量との関係を示した。
図9より、式(2)による評価値とカール浮き量とは直線に乗っており、対応が良いことが分かる。
前記第2の保護フィルムは、樹脂を含んでなることが好ましく、前記樹脂としては、公知の樹脂を用いることができ、本発明の趣旨に反しない限りにおいて特に制限はないが、セルロースアシレート、(メタ)アクリル系樹脂、シクロオレフィン系樹脂、ポリエステル系樹脂を挙げることができ、セルロースアシレートが好ましい。
以下、第2の保護フィルムに用いることができるセルロースアシレートについて、詳しく説明する。
セルロースアシレートの置換度は、セルロースの構成単位((β)1,4-グリコシド結合しているグルコース)に存在している、3つの水酸基がアシル化されている割合を意味する。置換度(アシル化度)は、セルロースの構成単位質量当りの結合脂肪酸量を測定して算出することができる。本発明において、セルロース体の置換度はセルロース体を重水素置換されたジメチルスルフォキシド等の溶剤に溶解して13C-NMRスペクトルを測定し、アシル基中のカルボニル炭素のピーク強度比から求めることにより算出することができる。セルロースアシレートの残存水酸基をセルロースアシレート自身が有するアシル基とは異なる他のアシル基に置換したのち、13C-NMR測定により求めることができる。測定方法の詳細については、手塚他(Carbohydrate.Res.,273(1995)83-91)に記載がある。
セルロースアシレートのアシル基としては、アセチル基、プロピオニル基、ブチリル基が特に好ましく、アセチル基がより特に好ましい。
本発明においては、置換基及び/又は置換度の異なる2種のセルロースアシレートを併用、混合して用いてもよいし、後述の共流延法などにより、異なるセルロースアシレートからなる複数層からなるフィルムを形成してもよい。
またセルロースアシレートは、70000~230000の数平均分子量を有することが好ましく、75000~230000の数平均分子量を有することが更に好ましく、78000~120000の数平均分子量を有することが最も好ましい。
第2の保護フィルムは、有機酸やその他の偏光板保護フィルムに用いられる公知の添加剤を、本発明の趣旨に反しない限りにおいて、含んでいてもよい。これによって湿度寸法変化率の制御の一助とすることができる。添加剤の分子量は特に制限されないが、後述の添加剤を好ましく用いることができる。
添加剤を加えることによって、湿度寸法変化率の制御に加えて、フィルムの熱的性質、光学的性質、機械的性質の改善、柔軟性付与、耐吸水性付与、水分透過率低減等のフィルム改質の観点で、有用な効果を示す。
第2の保護フィルムの厚みは5~30μmが好ましく、10~30μmより好ましく、15~25μmが特に好ましい。厚みが30μm以下であると、液晶ディスプレイのスリム化の観点で好ましい。一方、厚みが5μm以上であると、偏光板加工時の搬送時に破断しにくく、偏光板の表面に傷が付きにくい。
前記第2の保護フィルムの厚さは、フィルム断面の光学顕微鏡観察により測定される平均膜厚である。
添加剤の添加量としては、上記種々の効果を発現させる観点から、セルロースアシレートに対して10質量%以上であることが好ましく、15質量%以上であることがより好ましく、20質量%以上であることが更に好ましい。上限としては、80質量%以下であることが好ましく、65質量%以下であることが好ましい。添加剤を2種類以上用いた場合には、その合計量が上記範囲にあることが好ましい。
第2の保護フィルムの透湿度は、偏光板製造時の乾燥速度の観点から、10g/m2・day以上であることが好ましい。第2の保護フィルムの透湿度は、10~500g/m2・dayであることがより好ましく、100~500g/m2・dayであることが更に好ましく、200~450g/m2・dayであることがより特に好ましい。
本明細書中における透湿度の値は、JIS Z0208の透湿度試験(カップ法)に準じて、温度40℃、相対湿度92%の雰囲気中、面積1m2の試料を24時間に通過する水蒸気の質量(g)を測定した値である。
前記第2の保護フィルムの製造方法について、(メタ)アクリル系樹脂、シクロオレフィン系樹脂、ポリエステル系樹脂を用いたフィルムの製造方法としては、特に限定されるものではないが、例えば、樹脂と、その他の重合体や添加剤等を、任意の適切な混合方法で充分に混合し、予め熱可塑性樹脂組成物としてから、これをフィルム成形することができる。あるいは、樹脂と、その他の重合体や添加剤等を、それぞれ別々の溶液にしてから混合して均一な混合液とした後、フィルム成形してもよい。
上記熱可塑性樹脂組成物を製造するには、例えば、オムニミキサー等、任意の適切な混合機で上記のフィルム原料をプレブレンドした後、得られた混合物を押出混練する。この場合、押出混練に用いられる混合機は、特に限定されるものではなく、例えば、単軸押出機、二軸押出機等の押出機や加圧ニーダー等、任意の適切な混合機を用いることができる。
上記フィルム成形の方法としては、例えば、溶液キャスト法(溶液流延法)、溶融押出法、カレンダー法、圧縮成形法等、任意の適切なフィルム成形法が挙げられる。これらのフィルム成形法のうち、溶液キャスト法(溶液流延法)、溶融押出法が好ましい。
第2の保護フィルムの製造方法について、第2の保護フィルムがセルロースアシレートを含むフィルム(「セルロースアシレートフィルム」とも言う)である場合を例として詳細に説明する。
セルロースアシレートフィルムは、ソルベントキャスト法により製造することができる。以下、前記有機酸を含む偏光板保護フィルムの製造方法について、基材としてセルロースアシレートを用いた態様を例に挙げて説明するが、その他の樹脂を用いた場合も同様に前記偏光板保護フィルムを製造することができる。ソルベントキャスト法では、セルロースアシレートを有機溶媒に溶解した溶液(ドープ)を用いてフィルムを製造する。
前記エーテル、ケトン及びエステルは、環状構造を有していてもよい。また、前記エーテル、ケトン及びエステルの官能基(すなわち、-O-、-CO-及び-COO-)のいずれかを2つ以上有する化合物も、前記有機溶媒として用いることができる。前記有機溶媒は、アルコール性水酸基のような他の官能基を有していてもよい。2種類以上の官能基を有する有機溶媒の場合、その炭素原子数はいずれかの官能基を有する溶媒の上述の好ましい炭素原子数範囲内であることが好ましい。
前記炭素原子数が3~12のケトン類の例には、アセトン、メチルエチルケトン、ジエチルケトン、ジイソブチルケトン、シクロヘキサノン及びメチルシクロヘキサノンが含まれる。
前記炭素原子数が3~12のエステル類の例には、エチルホルメート、プロピルホルメート、ペンチルホルメート、メチルアセテート、エチルアセテート及びペンチルアセテートが含まれる。
また、2種類以上の官能基を有する有機溶媒の例には、2-エトキシエチルアセテート、2-メトキシエタノール及び2-ブトキシエタノールが含まれる。
また、2種類以上の有機溶媒を混合して用いてもよい。
セルロースアシレート溶液に対し、有機酸を添加する場合、その添加のタイミングは、製膜される時点で添加されていれば特に限定されない。例えば、セルロースアシレートの合成時点で添加してもよいし、ドープ調製時にセルロースアシレートと混合してもよい。
第2の保護フィルムには、劣化防止剤(例えば、酸化防止剤、過酸化物分解剤、ラジカル禁止剤、金属不活性化剤、酸捕獲剤、アミン等)を添加してもよい。劣化防止剤については、特開平3-199201号、同5-1907073号、同5-194789号、同5-271471号、同6-107854号の各公報に記載がある。また、前記劣化防止剤の添加量は、調製する溶液(ドープ)の0.01~1質量%であることが好ましく、0.01~0.2質量%であることが更に好ましい。添加量が0.01質量%以上であれば、劣化防止剤の効果が十分に発揮されるので好ましく、添加量が1質量%以下であれば、フィルム表面への劣化防止剤のブリードアウト(滲み出し)などが生じにくいので好ましい。特に好ましい劣化防止剤の例としては、ブチル化ヒドロキシトルエン(BHT)、トリベンジルアミン(TBA)を挙げることができる。
使用される溶剤は低級アルコール類としては、好ましくはメチルアルコール、エチルアルコール、プロピルアルコール、イソプロピルアルコール、ブチルアルコール等が挙げられる。低級アルコール以外の溶媒としては特に限定されないが、セルロースエステルの製膜時に用いられる溶剤を用いることが好ましい。
第2の保護フィルムには、延伸処理を行うこともできる。延伸処理により偏光板保護フィルムに所望のレターデーションを付与することが可能である。セルロースアシレートフィルムの延伸方向は幅方向、長手方向のいずれでも好ましい。
幅方向に延伸する方法は、例えば、特開昭62-115035号、特開平4-152125号、同4-284211号、同4-298310号、同11-48271号などの各公報に記載されている。
また、流延後にドープ溶剤が残存した状態で延伸を行う場合、乾膜よりも低い温度で延伸が可能となり、この場合、100℃~170℃が好ましい。
延伸速度は1%/分~300%/分が好ましく、10%/分~300%/分が更に好ましく、30%/分~300%/分が最も好ましい。
フィルムの幅方向に延伸する延伸工程と、フィルムの搬送方向(長手方向)に収縮させる収縮工程を含むことを特徴とする製造方法においてはパンタグラフ式あるいはリニアモーター式のテンターによって保持し、フィルムの幅方向に延伸しながら搬送方向にはクリップの間隔を徐々に狭めることでフィルムを収縮させることが出来る。
特に、フィルムの幅方向に10%以上延伸する延伸工程と、フィルムの幅方向にフィルムを把持しながらフィルムの搬送方向を5%以上収縮させる収縮工程とを含むことが好ましい。
なお、本発明でいう収縮率とは、収縮方向における収縮前のフィルムの長さに対する収縮後のフィルムの収縮した長さの割合を意味する。
収縮率としては5~40%が好ましく、10~30%が特に好ましい。
前記第2の保護フィルムをアウター側フィルムとすることは、液晶表示装置表面への傷の付きにくさの観点で好ましい。
以下、本発明の偏光板の製造方法について、偏光板保護フィルムと偏光子の積層方法、偏光板の機能化の順に説明する。
前記偏光板保護フィルム(第1の保護フィルム、及び第2の保護フィルム)はアルカリ鹸化処理することによりポリビニルアルコールのような偏光子の材料との密着性を付与し、偏光板保護フィルムとして用いることができる。
鹸化の方法については、特開2007-86748号公報の〔0211〕と〔0212〕に記載される方法を用いることができる。
本発明の偏光板の製造方法は、上記にて得られた本発明の偏光子の両面に、2枚の偏光板保護フィルムを積層する工程を含むことが好ましい。
前記偏光板保護フィルムの処理面と偏光子を貼り合わせるのに使用される接着剤としては、例えば、ポリビニルアルコール、ポリビニルブチラール等のポリビニルアルコール系接着剤や、ブチルアクリレート等のビニル系ラテックス等が挙げられる。
図2に本発明の偏光板の一例を示す。図2において、偏光子3の吸収軸13と、第1の保護フィルム1のフィルム製造時のTD方向11及び第2の保護フィルム2のフィルム製造時のTD方向12とは直交している。
<偏光板の性能>
本発明の偏光板の好ましい光学特性等については特開2007-086748号公報の〔0238〕~〔0255〕に記載されており、これらの特性を満たすことが好ましい。
本発明の偏光板の形状は、液晶表示装置にそのまま組み込むことが可能な大きさに切断されたフィルム片の態様の偏光板のみならず、連続生産により、長尺状に作製され、ロール状に巻き上げられた態様(例えば、ロール長2500m以上や3900m以上の態様)の偏光板も含まれる。大画面液晶表示装置用とするためには、偏光板の幅は1470mm以上とすることが好ましい。
偏光板の厚みは、40μm以上80μm以下が好ましく、45μm以上70μm以下がより好ましく、50μm以上60μm以下が更に好ましい。偏光板の厚みが80μm以下であれば、偏光板の収縮による液晶ディスプレイの反りが発生しにくいため好ましく、60μm以下であることが特に好ましい。一方、偏光板の厚みが40μm以上であれば、偏光板加工において搬送中にたわみが発生しにくく、加工ラインを通しやすいため好ましい。
前記プロテクトフィルム及び前記セパレートフィルムは偏光板出荷時、製品検査時等において偏光板を保護する目的で用いられる。この場合、プロテクトフィルムは、偏光板の表面を保護する目的で貼合され、偏光板を液晶板へ貼合する面の反対面側に用いられる。また、セパレートフィルムは液晶板へ貼合する接着層をカバーする目的で用いられ、偏光板を液晶板へ貼合する面側に用いられる。
本発明の偏光板は、ディスプレイの視認性向上のための反射防止フィルム、輝度向上フィルムや、ハードコート層、前方散乱層、アンチグレア(防眩)層等の機能層を有する光学フィルムと複合した機能化偏光板としても好ましく使用される。機能化のための反射防止フィルム、輝度向上フィルム、他の機能性光学フィルム、ハードコート層、前方散乱層、アンチグレア層については、特開2007-86748号公報の〔0257〕~〔0276〕に記載され、これらの記載を基に機能化した偏光板を作成することができる。
(1) 第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
前記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2.0GPa~2.5GPaであり、
前記偏光子の厚みが20μmであり、
前記第2の保護フィルムが、下記式(2’)で表される評価値Aが5.7~9.0である、偏光板。
式(2’):
評価値A=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2
(2) 第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
前記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2.0GPa~2.5GPaであり、
前記偏光子の厚みが25μmであり、
前記第2の保護フィルムが、下記式(2’)で表される評価値Aが6.5~10.0である、偏光板。
式(2’):
評価値A=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2
(3) 第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
前記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2.0GPa~2.5GPaであり、
前記偏光子の厚みが30μmであり、
前記第2の保護フィルムが、下記式(2’)で表される評価値Aが7.0~11.0である、偏光板。
式(2’):
評価値A=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2
本発明の液晶表示装置は、前記本発明の偏光板を、バックライト側偏光板、及び視認側偏光板の少なくとも一方として有する。
特に、本発明の偏光板における、(メタ)アクリル系樹脂を含んでなる第1の保護フィルムを、液晶セル側(インナー側)となるように含むことが好ましい。
本発明の液晶表示装置の好ましい一例の模式図を図3に示す。
図3に示した液晶表示装置100は、液晶セル20の両側に、第1の保護フィルム1、偏光子3、及び第2の保護フィルム2を有する本発明の偏光板10を有する。液晶表示装置100は、液晶セル20側(インナー側)に第1の保護フィルム1が配置されるように偏光板10を有している。
ノーマリーブラックの液晶表示装置とするためには、2枚の偏光板10における偏光子3の吸収軸は、互いに直交するように配置されることが好ましい。
[フィルム1]
<樹脂a-1の合成>
窒素置換した反応容器に、特定単量体dとして8-メチル-8-メトキシカルボニルテトラシクロ[4.4.0.12,5.17,10]-3-ドデセン 227部と、特定単量体eとして5-メトキシカルボニルビシクロ[2.2.1]ヘプト-2-エン 26部と、分子量調節剤として1-ヘキセン 17部と、溶媒としてトルエン 753部とを仕込み、この溶液を60℃に加熱した。次いで、反応容器内の溶液に、重合触媒としてトリエチルアルミニウム1.5モル/lを含有するトルエン溶液0.62部と、t-ブタノール及びメタノールで変性した六塩化タングステン(t-ブタノール:メタノール:タングステン=0.35モル:0.3モル:1モル)を含有する濃度0.05モル/lのトルエン溶液3.8部とを添加し、この系を85℃で3時間加熱撹拌することにより開環共重合反応させて開環共重合体溶液を得た。
この重合反応における重合転化率は96%であり、得られた開環共重合体溶液を構成する開環共重合体の30℃のクロロホルム中における固有粘度(ηinh)を測定したところ、0.64dl/gであった。
得られた反応溶液(水素添加重合体溶液)を冷却した後、水素ガスを放圧した。この反応溶液を大量のメタノール中に注いで凝固物を分離回収し、これを乾燥して、水素添加重合体(以下、「樹脂(a-1)」)を得た。
また、樹脂(a-1)における5-メトキシカルボニルビシクロ[2.2.1]ヘプト-2-エンに由来の構造単位eの割合を、400MHz 1H-NMRスペクトルを測定し、約3.7ppm付近に出現する、8-メチル-8-メトキシカルボニルテトラシクロ[4.4.0.12,5.17,10]-3-ドデセンに由来の構造単位dのメチルエステルのメチルのプロトンの吸収ピークと、0.15~3ppmに出現する構造単位d及び構造単位eの脂環構造のプロトンの吸収ピークとに基づいて算出したところ、19.5%であった。また、ゲルパーミエーションクロマトグラフィー(GPC)により、ポリスチレン換算重量平均分子量Mwが1万以下のもの、1万を超えて3万以下の範囲のもの、及び3万を超えたものを分取し、それぞれの構造単位eの割合を、400MHz 1H-NMRスペクトルにより確認したところ、樹脂(a-1)全体における割合である19.5%の値に対するバラツキは、いずれも15%以内であった。
この溶液に、酸化防止剤としてペンタエリスリチルテトラキス[3-(3,5-ジ-t-ブチル-4-ヒドロキシフェニル)プロピオネート]を、樹脂(a-1)100重量部に対して0.1重量部を添加し、得られた溶液を日本ポール製の孔径5μmの金属繊維焼結フィルターを用い、差圧が0.4MPa以内に収まるように溶液の流速をコントロールしながら濾過した後、クラス1000のクリーンルーム内に設置した井上金属工業製の「INVEXラボコーター」を用い、アクリル酸系表面処理剤によって親水化(易接着性化)処理された、厚みが100μmのPETフィルム(東レ(株)製の「ルミラーU94」)に塗布した。
次いで、得られた液層に対して、50℃で一次乾燥処理を行い、更に、90℃で二次乾燥処理を行った後、PETフィルムから剥離させることにより、厚さ25μmのフィルム1を形成した。得られたフィルム1の残留溶媒量は0.5重量%であり、光線透過率は93%以上であった。
フィルム1と同様の方法で、PETフィルムへの塗布量を調整し、厚さ20μmのフィルム2を形成した。
窒素置換した反応容器に、特定単量体dとして8-メチル-8-メトキシカルボニル-9-メトキシカルボニルテトラシクロ[4.4.0.12,5.17,10]-3-ドデセン 225部と、特定単量体eとしてビシクロ[2.2.1]ヘプト-2-エン 25部と、分子量調節剤として1-ヘキセン 18部と、溶媒としてトルエン 753部とを仕込み、この溶液を60℃に加熱した。次いで、反応容器内の溶液に、重合触媒としてトリエチルアルミニウム1.5モル/lを含有するトルエン溶液0.62部と、t-ブタノール及びメタノールで変性した六塩化タングステン(t-ブタノール:メタノール:タングステン=0.35モル:0.3モル:1モル)を含有する濃度0.05モル/lのトルエン溶液3.8部とを添加し、この系を85℃で3時間加熱撹拌することにより開環共重合反応させて開環共重合体溶液を得た。
この重合反応における重合転化率は95%であり、得られた開環共重合体溶液を構成する開環共重合体の30℃のクロロホルム中における固有粘度(ηinh)を測定したところ、0.68dl/gであった。
得られた反応溶液(水素添加重合体溶液)を冷却した後、水素ガスを放圧した。この反応溶液を大量のメタノール中に注いで凝固物を分離回収し、これを乾燥して、水素添加重合体(以下、「樹脂(a-2)」)を得た。
得られた樹脂(a-2)について、水素添加率を、400MHz 1H-NMRスペクトルにより測定したところ、99.9%であった。
また、樹脂(a-2)におけるビシクロ[2.2.1]ヘプト-2-エンに由来の構造単位eの割合を、400MHz 1H-NMRスペクトルを測定し、約3.7ppm付近に出現する、8-メチル-8-メトキシカルボニル-9-メトキシカルボニルテトラシクロ[4.4.0.12,5.17,10]-3-ドデセンに由来の構造単位dのメチルエステルのメチルのプロトンの吸収ピークと、0.15~3ppmに出現する構造単位d及び構造単位eの脂環構造のプロトンの吸収ピークとに基づいて算出したところ、19.4%であった。また、ゲルパーミエーションクロマトグラフィー(GPC)により、ポリスチレン換算重量平均分子量Mwが1万以下のもの、1万を超えて3万以下の範囲のもの、及び3万を超えたものを分取し、それぞれの構造単位eの割合を、400MHz 1H-NMRスペクトルにより確認したところ、樹脂(a-2)全体における割合である19.4%の値に対するバラツキは、いずれも15%以内であった。
樹脂フィルム(a-2)をテンター内で、120℃(Tg+10℃)に加熱し、延伸速度300%/分でフィルム面内方向の縦方向に1.05倍に延伸した後、フィルム面内方向の横方向に1.2倍に延伸し、その後、90℃(Tg-20℃)の雰囲気下で1分間この状態を保持しながら冷却し、更に室温で冷却し、テンター内から取り出すことにより、フィルム26を得た。厚みは25μmであった。
[フィルム3~24、27]
セルロースアシレートのアセチル置換度については以下の方法で測定した。
アセチル置換度は、ASTM D-817-91に準じて測定した。
フィルムの弾性率はJIS K7127に記載の方法に従って測定した。
フィルムロールの巻き方向を長手方向(MD方向)、長手方向と直交する幅手方向(TD方向)とする。該幅手方向を測定方向として、該測定方向に15cmの長さで、幅1cmのフィルム試料を切り出した。該試料を東洋精機製のストログラフV10-Cに、長手方向のチャック間隔が10cmとなるように設置し、延伸速度10mm/分でチャック間隔が広がるように加重を加えて、その時の力を測定した。予めマイクロメーターで測定していたフィルムの厚み、力、伸び量から弾性率を算出した。
フィルムの湿度寸法変化率は以下の方法で測定した。
フィルムロールの巻き方向を長手方向(MD方向)、長手方向と直交する幅手方向(TD方向)とする。該幅手方向を測定方向として、該測定方向に12cmの長さで、幅3cmのフィルム試料を切り出した。該試料に測定方向に沿って10cmの間隔でピン孔を空け、25℃、相対湿度60%にて24時間調湿後、ピン孔の間隔をピンゲージで測長した。次に25℃、相対湿度10%にて24時間調湿後、ピン孔の間隔をピンゲージで測長した。次いで、試料を25℃、相対湿度80%にて24時間調湿後、ピン孔の間隔をピンゲージで測長した。これらの測定値を用いて前記式(1)に対応する下記式(1’)によりTD方向の湿度寸法変化率を算出した。
式(1’):
TD方向の湿度寸法変化率(%)=[{(25℃、相対湿度80%におけるピン孔の間隔)-(25℃、相対湿度10%におけるピン孔の間隔)}/(25℃、相対湿度60%におけるピン孔の間隔)]×100
(1)中間層用ドープの調製
下記組成の中間層用ドープ1を調製した。
―――――――――――――――――――――――――――――――――
ドープ1の組成
―――――――――――――――――――――――――――――――――
・セルロースアセテート(アセチル化度2.86、重合度370)
100質量部
・メチレンクロライド(第1溶媒) 320質量部
・メタノール(第2溶媒) 83質量部
・1-ブタノール(第3溶媒) 3質量部
・トリフェニルフォスフェート 7.6質量部
・ビフェニルジフェニルフォスフェート 3.8質量部
―――――――――――――――――――――――――――――――――
攪拌羽根を有する4000Lのステンレス性溶解タンクに、上記混合溶媒をよく攪拌・分散しつつ、セルロースアセテート粉体(フレーク)、トリフェニルフォスフェート及びビフェニルジフェニルフォスフェートを徐々に添加し、全体が2000kgになるように調製した。なお、溶媒は、すべてその含水率が0.5質量%以下のものを使用した。まず、セルロースアセテートの粉末は、分散タンクに粉体を投入して、攪拌剪断速度を最初は5m/sec(剪断応力5×104kgf/m/sec2)の周速で攪拌するディゾルバータイプの偏芯攪拌軸及び、中心軸にアンカー翼を有して周速1m/sec(剪断応力1×104kgf/m/sec2)で攪拌する条件下で30分間分散した。分散の開始温度は25℃であり、最終到達温度は48℃となった。分散終了後、高速攪拌は停止し、アンカー翼の周速を0.5m/secとして更に100分間攪拌し、セルロースアセテートフレークを膨潤させた。膨潤終了までは窒素ガスでタンク内を0.12MPaになるように加圧した。この際のタンク内の酸素濃度は2vol%未満であり防爆上で問題のない状態を保った。またドープ中の水分量は0.5質量%以下であることを確認し、具体的には0.3質量%であった。
次に36℃まで温度を下げ、公称孔径8μmの濾材を通過させドープを得た。この際、濾過1次圧は1.5MPa、2次圧は1.2MPaとした。高温にさらされるフィルター、ハウジング、及び配管はハステロイ合金製で耐食性の優れたものを利用し保温加熱用の熱媒を流通させるジャケットを有する物を使用した。
マット剤(二酸化ケイ素(粒径20nm))と剥離促進剤(クエン酸エチルエステル(クエン酸、モノエチルエステル、ジエチルエステル、トリエチルエステル混合物))と前記中間層用ドープ1を、静止型混合器を介して混合させて支持体層用ドープ2を調製した。添加量は、全固形分濃度が20.5質量%,マット剤濃度が0.05質量%,剥離促進剤濃度が0.03質量%となるように行った。
マット剤(二酸化ケイ素(粒径20nm))を静止型混合器を介して前記中間層用ドープ1に混合させて、エアー層用ドープ3を調製した。添加量は、全固形分濃度が20.5質量%,マット剤濃度が0.1質量%となるように行った。
流延ダイとして、幅が1.8mであり共流延用に調整したフィードブロックを装備して、主流のほかに両面にそれぞれ積層して3層構造のフィルムを成形できるようにした装置を用いた。以下の説明において、主流から形成される層を中間層と称し、支持体面側の層を支持体層と称し、反対側の面をエアー層と称する。なお、ドープの送液流路は、中間層用、支持体層用、エアー層用の3流路を用いた。
各ドープの流量を調整し、また搬送方向の延伸強度、幅手方向の延伸倍率を調整して、その他はフィルム3と同様にして、厚み、TD方向の弾性率、TD方向の湿度寸法変化率が異なるフィルム4~24、27を製造した。フィルム1~27の厚み、TD方向の弾性率、TD方向の湿度寸法変化率を表1に示す。
作製したインナー側フィルム及びアウター側フィルムを、2.3mol/Lの水酸化ナトリウム水溶液に、55℃で3分間浸漬した。室温の水洗浴槽中で洗浄し、30℃で0.05mol/Lの硫酸を用いて中和した。再度、室温の水洗浴槽中で洗浄し、更に100℃の温風で乾燥した。このようにして、各フィルムについて表面の鹸化処理を行った。
500Lのタンクに18℃の水200kgを入れ、攪拌しながら、重量平均分子量165000、ケン化度99.8モル%のポリビニルアルコール系樹脂42kgを加え、15分間攪拌した。得られたスラリーを脱水し、含水率40%のポリビニルアルコール系樹脂ウェットケーキを得た。
キャストドラム幅4.3m、
キャストドラム回転速度:8m/分、
キャストドラム表面温度:90℃、
T型スリットダイ出口の樹脂温度:95℃
得られた膜の表面と裏面とを下記の条件にて複数の乾燥ロールを交互に通過させながら乾燥を行った。
乾燥ロール幅:4.3m、
乾燥ロール本数(n):10本、
乾燥ロール回転速度:8m/分、
乾燥ロール表面速度:50℃
偏光子1と同様の作り方で、長さ4000m、幅4m、厚み63μmのポリビニルアルコールフィルムを作製し、このフィルムを40℃の温水に2分間浸漬し、膨潤処理した後、1.30倍に延伸した。得られたフィルムを、ホウ酸(Societa Chimica Larderello s.p.a社製)28.6g/L、ヨウ素(純正化学社製)0.25g/L、ヨウ化カリウム(純正化学社製)1.0g/Lを含有した水溶液中で30℃、2分浸漬してヨウ素及びヨウ化物による染色処理を行なった。染色処理して得られたフィルムを5.0倍に一軸延伸しながらホウ酸30.0g/L含有した50℃の水溶液中で5分間処理を行った。得られたフィルムを70℃で9分間乾燥処理を行った。これにより厚み25μmの偏光子を得た。
偏光子1、2と同様の作り方で、長さ4000m、幅4m、厚み50μmのポリビニルアルコールフィルムを作製し、このフィルムを40℃の温水に2分間浸漬し、膨潤処理した後、1.30倍に延伸した。得られたフィルムを、ホウ酸(Societa Chimica Larderello s.p.a社製)28.6g/L、ヨウ素(純正化学社製)0.25g/L、ヨウ化カリウム(純正化学社製)1.0g/Lを含有した水溶液中で30℃、2分浸漬してヨウ素及びヨウ化物による染色処理を行なった。染色処理して得られたフィルムを5.0倍に一軸延伸しながらホウ酸30.0g/L含有した50℃の水溶液中で5分間処理を行った。得られたフィルムを70℃で9分間乾燥処理を行った。これにより厚み20μmの偏光子を得た。
ポリエステル系ウレタン(三井武田ケミカル社製、タケラックXW-74―C154)10質量部及びイソシアネート系架橋剤(三井武田ケミカル社製、タケネートWD-725)1質量部を、水に溶解し、固形分を20質量%に調整した溶液を調製した。これを接着剤として用いた。
上記方法にて製造し、鹸化処理したインナー側フィルムを、上記接着剤を用いて、上記方法にて製造した偏光子の片側に貼り付けた。次に上記方法にて製造し、鹸化処理したアウター側フィルムを、上記接着剤を用いて、インナー側の偏光板保護フィルムを貼り付けてある側とは反対側の偏光子の面に貼り付けた。
この際、作成した偏光子の吸収軸と、インナー側及びアウター側の両方の保護フィルムのTD方向とは直交するように配置した。
このようにして偏光板試料1~30を作製した。作製した偏光板の構成を表2に示す。表中に下記式(2)で求める評価値の値を記した。
式(2):
評価値=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2×{(30/偏光子の厚み(μm))}1/2
ここで、インナー側フィルムとして用いたフィルム1、2、25、26が第1の保護フィルムであり、アウター側フィルムとして用いたフィルム3~24、27が第2の保護フィルムである。
このようにして作製した偏光板を15cm×15cmの大きさに裁断し、25℃、相対湿度60%の温度湿度環境に4時間置いた後、4隅の浮き上がり量を計測した。その結果を表2に示す。この際、アウター側を上向きに置いた時の浮き上がり量をプラス方向とする。作製したサンプルがインナー側に反っている時は、アウター側を上向きに置いても浮き上がり量を計測できないため、フィルムの上下を引っくり返してインナー側を上向きに置いて浮き上がり量を計測し、マイナス符号を付与する。
4隅の平均の浮き上がり量の良し悪しは、-2mm以上4mm未満が特に好ましくAとし、-8mm以上-2mm未満又は4mm以上16mm未満が次に好ましくBとし、-8mm未満、又は16mm以上は好ましくなくCとした。
前記の方法で長尺状の光学フィルム1、2、25、26を作製し、表面にコロナ処理を施した。次いで、長尺状の光学フィルム3~24、27にけん化処理を施した。コロナ処理した光学フィルムとけん化処理したタックフィルムとで偏光子を挟持するように、ポリビニルアルコール系接着剤を用いて、ロール機によるロールツーロールで偏光子の両面に貼り合わせ、70℃で10分以上乾燥した。このときエア側(視認側)保護フィルムとセル側保護フィルムとして表2に記載の光学フィルムの組み合わせを選択し、偏光板試料を作成した。これにより、フィルム長さ500m、吸収軸は長手方向、遅相軸は長手と直交方向であり、両面が光学フィルムによって保護された偏光板試料を得た。
作製した各偏光板試料に、粘着剤の付いたポリエチレンテレフタレートを主成分とするラミネートフィルム(膜厚38μm)をロール機によるロールツーロールで、エア側保護フィルム側に貼り合わせた。
(粘着剤の調製)
冷却管、窒素導入管、温度計及び撹拌装置を備えた反応容器に、アクリル酸イソオクチル100質量部、アクリル酸6-ヒドロキシヘキシル0.085質量部及び2,2´-アゾビスイソブチロニトリル0.4質量部を酢酸エチルと共に加えて溶液を調製した。次いで、この溶液に窒素ガスを吹き込みながら撹拌して、60℃で4時間反応させて、重量平均分子量175万のアクリル系ポリマーPAを含有する溶液を得た。更に、このアクリル系ポリマーPAを含有する溶液に、酢酸エチルを加えて固形分濃度を30質量%に調整したアクリル系ポリマー溶液を得た。
上記粘着剤溶液を、作製した偏光板試料のセル側保護フィルム側にスロットダイコーターで均一に塗工し、155℃の空気循環式恒温槽を5分間通過させ、偏光板表面に、厚さ15μmの粘着剤層を形成した。形成した粘着剤層の上に、ポリエチレンテレフタレートを主成分とするセパレートフィルム(膜厚38μm)をロール機でロールツーロールで貼り合わせた。
作製した偏光板を42インチの液晶表示装置に貼合するため、下記のサイズで打ち抜いた。
・フロント側
MD方向 929.8mm
TD方向 523.0mm
・リア側
MD方向 523.0mm
TD方向 929.8mm
上記サイズで打ち抜いた偏光板を、アルミ防湿袋(エーディーワイ株式会社製)に投入し、温度を180℃に設定したヒートシーラーで密封した。偏光板を封入したアルミ防湿袋は温度25℃の環境で保管した。
市販のIPS型液晶テレビ(LG電子製42LA6900)からフロント側、リア側の各偏光板をはがし、実験用の液晶セルを用意した。その後、偏光板からセパレートフィルムを剥がし、用意した液晶セルのフロント側及びリア側に偏光板を一枚ずつ貼り付けた。この時、フロント側の偏光板の吸収軸が長手方向(左右方向)に、そして、リア側の偏光板の透過軸が長手方向(左右方向)になるように、クロスニコル配置とした。またこの時の環境は温度25℃相対湿度60%だった。表2においてカールが良好だった偏光板を液晶セルに貼り合わせて作製した液晶表示装置は偏光板の端部への気泡の混入が少なく美観が良好だった。
本出願は、2012年7月27日出願の日本特許出願(特願2012-167653)に基づくものであり、その内容はここに参照として取り込まれる。
2 第2の保護フィルム
3 偏光子
10 偏光板
11 第1の保護フィルムのTD方向
12 第2の保護フィルムのTD方向
13 偏光子の吸収軸
20 液晶セル
100 液晶表示装置
Claims (9)
- 第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
前記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2GPa~2.5GPaであり、下記式(1)で表されるTD方向の湿度寸法変化率が0.1%以下であり、
前記第2の保護フィルムが、下記式(2)で表される評価値が7.0~11.0である、偏光板。
式(1):
TD方向の湿度寸法変化率(%)=[{(25℃、相対湿度80%におけるTD方向のフィルム長さ)-(25℃、相対湿度10%におけるTD方向のフィルム長さ)}/(25℃、相対湿度60%におけるTD方向のフィルム長さ)]×100
式(2):
評価値=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2×{(30/偏光子の厚み(μm))}1/2 - 前記第2の保護フィルムが、セルロースアシレートを含んでなるフィルムである、請求項1に記載の偏光板。
- 前記第1の保護フィルムに含まれる合成ポリマーがシクロオレフィン系ポリマーである、請求項1又は2に記載の偏光板。
- 前記式(2)で表される評価値が9.0~10.0である、請求項1~3のいずれか一項に記載の偏光板。
- 偏光板の厚みが、80μm以下である、請求項1~4のいずれか一項に記載の偏光板。
- 第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
前記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2.0GPa~2.5GPaであり、
前記偏光子の厚みが20μmであり、
前記第2の保護フィルムが、下記式(2’)で表される評価値Aが5.7~9.0である、偏光板。
式(2’):
評価値A=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2 - 第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
前記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2.0GPa~2.5GPaであり、
前記偏光子の厚みが25μmであり、
前記第2の保護フィルムが、下記式(2’)で表される評価値Aが6.5~10.0である、偏光板。
式(2’):
評価値A=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2 - 第1の保護フィルムと、偏光子と、第2の保護フィルムとをこの順に有する偏光板であって、
前記第1の保護フィルムが、合成ポリマーを含んでなるフィルムであり、厚さが30μm以下であり、TD方向の弾性率が2.0GPa~2.5GPaであり、
前記偏光子の厚みが30μmであり、
前記第2の保護フィルムが、下記式(2’)で表される評価値Aが7.0~11.0である、偏光板。
式(2’):
評価値A=第2の保護フィルムのTD方向の弾性率(GPa)/第2の保護フィルムのTD方向の湿度寸法変化率(%)×(第2の保護フィルムの厚み(μm)/第1の保護フィルムの厚み(μm))2 - 液晶セルと、請求項1~8のいずれか1項に記載の偏光板を少なくとも1枚有する液晶表示装置であって、前記偏光板における前記第1の保護フィルムが、前記液晶セル側に配置された液晶表示装置。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201380040030.9A CN104508521B (zh) | 2012-07-27 | 2013-07-24 | 偏光板及液晶显示装置 |
KR1020157002254A KR101641473B1 (ko) | 2012-07-27 | 2013-07-24 | 편광판 및 액정 표시 장치 |
JP2014526975A JP5816755B2 (ja) | 2012-07-27 | 2013-07-24 | 偏光板及び液晶表示装置 |
US14/605,163 US9417477B2 (en) | 2012-07-27 | 2015-01-26 | Polarizing plate and liquid crystal display device |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2012-167653 | 2012-07-27 | ||
JP2012167653 | 2012-07-27 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/605,163 Continuation US9417477B2 (en) | 2012-07-27 | 2015-01-26 | Polarizing plate and liquid crystal display device |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2014017541A1 true WO2014017541A1 (ja) | 2014-01-30 |
Family
ID=49997350
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2013/070056 WO2014017541A1 (ja) | 2012-07-27 | 2013-07-24 | 偏光板及び液晶表示装置 |
Country Status (6)
Country | Link |
---|---|
US (1) | US9417477B2 (ja) |
JP (1) | JP5816755B2 (ja) |
KR (1) | KR101641473B1 (ja) |
CN (1) | CN104508521B (ja) |
TW (1) | TW201407212A (ja) |
WO (1) | WO2014017541A1 (ja) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015145656A1 (ja) * | 2014-03-27 | 2015-10-01 | 日東電工株式会社 | 偏光子および画像表示装置 |
KR20160000732A (ko) * | 2014-06-25 | 2016-01-05 | 동우 화인켐 주식회사 | 초박형 편광판 및 이를 구비하는 액정표시장치 |
JP2016014696A (ja) * | 2014-06-30 | 2016-01-28 | 富士フイルム株式会社 | 偏光板および画像表示装置 |
KR20160121043A (ko) * | 2015-04-09 | 2016-10-19 | 주식회사 엘지화학 | 광학 필름용 조성물, 광학 필름, 이를 포함하는 플렉서블 디스플레이 소자 및 플렉서블 태양전지 소자 |
JP2017083548A (ja) * | 2015-10-26 | 2017-05-18 | コニカミノルタ株式会社 | 偏光板保護フィルム及び偏光板 |
WO2017115786A1 (ja) * | 2015-12-28 | 2017-07-06 | 富士フイルム株式会社 | 積層体、並びに、この積層体を用いた偏光板及び画像表示装置 |
KR20180084774A (ko) * | 2015-11-13 | 2018-07-25 | 스미또모 가가꾸 가부시키가이샤 | 편광판, 액정 표시 장치 및 유기 일렉트로루미네선스 표시 장치 |
JP2020140217A (ja) * | 2020-06-10 | 2020-09-03 | コニカミノルタ株式会社 | 偏光板保護フィルム及び偏光板 |
WO2022085726A1 (ja) * | 2020-10-23 | 2022-04-28 | コニカミノルタ株式会社 | 偏光板およびその製造方法、ならびに表示装置の製造方法 |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR102344721B1 (ko) * | 2014-03-12 | 2021-12-31 | 스미또모 가가꾸 가부시키가이샤 | 편광판의 제조 방법 |
TWI656011B (zh) * | 2014-03-14 | 2019-04-11 | 日東電工股份有限公司 | 層合體、延伸層合體、延伸層合體之製造方法、使用此等之包括偏光膜之光學膜層合體之製造方法、及偏光膜 |
KR101867347B1 (ko) * | 2014-04-07 | 2018-06-15 | 후지필름 가부시키가이샤 | 액정 표시 장치 |
KR101813755B1 (ko) * | 2015-05-28 | 2017-12-29 | 삼성에스디아이 주식회사 | 편광판 및 이를 포함하는 표시장치 |
JP2017009795A (ja) * | 2015-06-22 | 2017-01-12 | 日東電工株式会社 | 偏光板及び偏光板の製造方法 |
WO2017014225A1 (ja) * | 2015-07-21 | 2017-01-26 | 富士フイルム株式会社 | 液晶パネルおよび液晶表示装置 |
JP2017090523A (ja) * | 2015-11-04 | 2017-05-25 | 日東電工株式会社 | 偏光板 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007069474A1 (ja) * | 2005-12-12 | 2007-06-21 | Konica Minolta Opto, Inc. | 偏光板の製造方法、偏光板及び液晶表示装置 |
JP2008107499A (ja) * | 2006-10-24 | 2008-05-08 | Fujifilm Corp | 偏光板及び液晶表示装置 |
JP2008529038A (ja) * | 2005-02-03 | 2008-07-31 | 富士フイルム株式会社 | 偏光板および液晶表示装置 |
JP2009198666A (ja) * | 2008-02-20 | 2009-09-03 | Fujifilm Corp | 偏光板の製造方法、偏光板およびそれを用いた液晶表示装置 |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPWO2006118038A1 (ja) * | 2005-04-28 | 2008-12-18 | コニカミノルタオプト株式会社 | 光学フィルム、偏光板及び横電界スイッチングモード型液晶表示装置 |
JP2008102475A (ja) * | 2006-09-21 | 2008-05-01 | Fujifilm Corp | 偏光板及び液晶表示装置 |
JP2008203400A (ja) | 2007-02-19 | 2008-09-04 | Nitto Denko Corp | 表面保護フィルム付偏光板、表面保護フィルム付液晶パネル、および画像表示装置 |
JP2008260919A (ja) * | 2007-03-16 | 2008-10-30 | Fujifilm Corp | セルロースアセテートプロピオネートフィルム、セルロースアセテートプロピオネートフィルムの製造方法、光学補償シート、偏光板および液晶表示装置 |
JP5134353B2 (ja) * | 2007-12-14 | 2013-01-30 | 富士フイルム株式会社 | 光学補償フィルムおよびその製造方法 |
JP2009292869A (ja) | 2008-06-02 | 2009-12-17 | Fujifilm Corp | アクリルフィルム、その製造方法、偏光板、光学補償フィルム、反射防止フィルムおよび液晶表示装置 |
JP2011105924A (ja) | 2009-06-05 | 2011-06-02 | Fujifilm Corp | セルロースエステルフィルム、光学補償フィルム、偏光板、及び液晶表示装置 |
US8648982B2 (en) | 2010-02-19 | 2014-02-11 | Fujifilm Corporation | Optical film, polarizing plate and liquid crystal display device |
WO2011145495A1 (ja) * | 2010-05-20 | 2011-11-24 | コニカミノルタオプト株式会社 | 位相差フィルム付きの偏光板 |
JP2013018895A (ja) * | 2010-07-20 | 2013-01-31 | Fujifilm Corp | 光学フィルム、位相差フィルム、偏光板及び液晶表示装置 |
WO2013175927A1 (ja) * | 2012-05-24 | 2013-11-28 | 富士フイルム株式会社 | 偏光板及び液晶表示装置 |
-
2013
- 2013-07-24 WO PCT/JP2013/070056 patent/WO2014017541A1/ja active Application Filing
- 2013-07-24 CN CN201380040030.9A patent/CN104508521B/zh active Active
- 2013-07-24 KR KR1020157002254A patent/KR101641473B1/ko active IP Right Grant
- 2013-07-24 JP JP2014526975A patent/JP5816755B2/ja active Active
- 2013-07-26 TW TW102126781A patent/TW201407212A/zh unknown
-
2015
- 2015-01-26 US US14/605,163 patent/US9417477B2/en active Active
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008529038A (ja) * | 2005-02-03 | 2008-07-31 | 富士フイルム株式会社 | 偏光板および液晶表示装置 |
WO2007069474A1 (ja) * | 2005-12-12 | 2007-06-21 | Konica Minolta Opto, Inc. | 偏光板の製造方法、偏光板及び液晶表示装置 |
JP2008107499A (ja) * | 2006-10-24 | 2008-05-08 | Fujifilm Corp | 偏光板及び液晶表示装置 |
JP2009198666A (ja) * | 2008-02-20 | 2009-09-03 | Fujifilm Corp | 偏光板の製造方法、偏光板およびそれを用いた液晶表示装置 |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015145656A1 (ja) * | 2014-03-27 | 2015-10-01 | 日東電工株式会社 | 偏光子および画像表示装置 |
KR20160000732A (ko) * | 2014-06-25 | 2016-01-05 | 동우 화인켐 주식회사 | 초박형 편광판 및 이를 구비하는 액정표시장치 |
US10495799B2 (en) * | 2014-06-25 | 2019-12-03 | Dongwoo Fine-Chem Co., Ltd. | Ultra-thin polarizing plate and liquid crystal display device having same |
KR102172750B1 (ko) * | 2014-06-25 | 2020-11-02 | 동우 화인켐 주식회사 | 초박형 편광판 및 이를 구비하는 액정표시장치 |
JP2016014696A (ja) * | 2014-06-30 | 2016-01-28 | 富士フイルム株式会社 | 偏光板および画像表示装置 |
KR20160121043A (ko) * | 2015-04-09 | 2016-10-19 | 주식회사 엘지화학 | 광학 필름용 조성물, 광학 필름, 이를 포함하는 플렉서블 디스플레이 소자 및 플렉서블 태양전지 소자 |
JP2017083548A (ja) * | 2015-10-26 | 2017-05-18 | コニカミノルタ株式会社 | 偏光板保護フィルム及び偏光板 |
KR20180084774A (ko) * | 2015-11-13 | 2018-07-25 | 스미또모 가가꾸 가부시키가이샤 | 편광판, 액정 표시 장치 및 유기 일렉트로루미네선스 표시 장치 |
KR102444055B1 (ko) * | 2015-11-13 | 2022-09-15 | 스미또모 가가꾸 가부시키가이샤 | 편광판, 액정 표시 장치 및 유기 일렉트로루미네선스 표시 장치 |
WO2017115786A1 (ja) * | 2015-12-28 | 2017-07-06 | 富士フイルム株式会社 | 積層体、並びに、この積層体を用いた偏光板及び画像表示装置 |
JP2020140217A (ja) * | 2020-06-10 | 2020-09-03 | コニカミノルタ株式会社 | 偏光板保護フィルム及び偏光板 |
WO2022085726A1 (ja) * | 2020-10-23 | 2022-04-28 | コニカミノルタ株式会社 | 偏光板およびその製造方法、ならびに表示装置の製造方法 |
Also Published As
Publication number | Publication date |
---|---|
TW201407212A (zh) | 2014-02-16 |
US20150146140A1 (en) | 2015-05-28 |
JPWO2014017541A1 (ja) | 2016-07-11 |
JP5816755B2 (ja) | 2015-11-18 |
US9417477B2 (en) | 2016-08-16 |
KR101641473B1 (ko) | 2016-07-20 |
CN104508521A (zh) | 2015-04-08 |
KR20150020253A (ko) | 2015-02-25 |
CN104508521B (zh) | 2016-08-03 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5816755B2 (ja) | 偏光板及び液晶表示装置 | |
JP5080258B2 (ja) | 液晶表示装置 | |
KR101628597B1 (ko) | 액정 표시 장치 | |
TWI597544B (zh) | 液晶顯示裝置 | |
TWI353461B (en) | Optical film, optical compensation film, polarizin | |
JP4991170B2 (ja) | 光学樹脂フィルム、偏光板及び液晶表示装置 | |
TWI446025B (zh) | 光學樹脂薄膜、光學補償片、偏光板及液晶顯示器 | |
JP2014006505A (ja) | 液晶表示装置 | |
TW201447402A (zh) | 偏光板、其製造方法及影像顯示裝置 | |
WO2013175927A1 (ja) | 偏光板及び液晶表示装置 | |
JP2006293342A (ja) | 光学樹脂フィルム、偏光板及び液晶表示装置 | |
WO2006098162A1 (en) | Optical compensation sheet, polarizing plate and liquid crystal display | |
WO2007139138A1 (ja) | 偏光板およびその製造方法 | |
WO2007043573A1 (ja) | 位相差フィルムの製造方法、位相差フィルムおよびその用途 | |
JP5169842B2 (ja) | 偏光板、及び液晶表示装置 | |
TWI637850B (zh) | 偏光板及液晶顯示裝置 | |
JP2016122176A (ja) | 光学フィルム、光学フィルムの製造方法、光学フィルムを用いた偏光板、及び画像表示装置 | |
JP2014066955A (ja) | 偏光板及び液晶表示装置 | |
TW200821642A (en) | Retardation film | |
JP5821850B2 (ja) | 偏光板長尺ロール及び光学表示装置の製造システム | |
JP2006317922A (ja) | セルロースアシレートフィルム、光学補償フィルム、これらの製造方法、偏光板および液晶表示装置 | |
TW202101040A (zh) | 附相位差層之偏光板 | |
JP2023011320A (ja) | 位相差フィルムの製造方法 | |
TW202020028A (zh) | 相位差膜、附相位差層之偏光板、及相位差膜之製造方法 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 13822359 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2014526975 Country of ref document: JP Kind code of ref document: A |
|
ENP | Entry into the national phase |
Ref document number: 20157002254 Country of ref document: KR Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 13822359 Country of ref document: EP Kind code of ref document: A1 |