WO2013021818A1 - 光学積層体、光学積層体のセットおよびそれらを用いた液晶パネル - Google Patents
光学積層体、光学積層体のセットおよびそれらを用いた液晶パネル Download PDFInfo
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- WO2013021818A1 WO2013021818A1 PCT/JP2012/068791 JP2012068791W WO2013021818A1 WO 2013021818 A1 WO2013021818 A1 WO 2013021818A1 JP 2012068791 W JP2012068791 W JP 2012068791W WO 2013021818 A1 WO2013021818 A1 WO 2013021818A1
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- polarizing film
- liquid crystal
- optical
- stretching
- laminated body
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
- G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
- G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
- G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
- G02F1/133536—Reflective polarizers
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
- G02F2201/54—Arrangements for reducing warping-twist
Definitions
- the present invention relates to an optical laminate, a set of optical laminates, and a liquid crystal panel using them.
- Patent Document 1 a technique for adjusting the thickness of the protective layer of each polarizing film in the optical layered body disposed on both sides of the liquid crystal cell, or moisture of each optical layered body
- Patent Document 2 A technique for adjusting the rate
- the present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an optical laminate that can remarkably suppress warping of a liquid crystal panel and realize high contrast. It is in.
- the optical layered body of the present invention has a polarizing film having a thickness of 10 ⁇ m or less and a reflective polarizing film.
- the polarizing film is obtained by transverse stretching.
- a set of optical laminates is provided.
- This set of optical laminates includes a first optical laminate that is the optical laminate described above, and a second optical laminate that includes a polarizing film that is 5 ⁇ m or more thicker than the polarizing film of the first optical laminate. It consists of.
- a liquid crystal panel is provided.
- the liquid crystal panel of this invention has a liquid crystal cell and said optical laminated body.
- Another liquid crystal panel of the present invention includes a liquid crystal cell and the set of the optical laminate, the second optical laminate is disposed on the viewing side, and the first optical laminate is opposite to the viewing side. Arranged on the side.
- an optical laminate having a thin polarizing film and a reflective polarizing film by using an optical laminate (first optical laminate) and a second optical laminate having a polarizing film thicker than the polarizing film of the first optical laminate as a set, the above-mentioned The effect can be more pronounced.
- FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.
- the optical laminate 100 has a polarizing film 110 and a reflective polarizing film 120.
- the polarizing film 110 has a thickness of 10 ⁇ m or less.
- the polarizing film 110 and the reflective polarizing film 120 may be laminated via any appropriate adhesive layer (specifically, a pressure-sensitive adhesive layer or an adhesive layer), and are in close contact (without an adhesive layer). It may be laminated. According to the present invention, it is possible to suppress warpage of the liquid crystal panel by laminating such a thin polarizing film and a reflective polarizing film.
- the optical laminate of the present invention (hereinafter also referred to as the first optical laminate when referring to the set of optical laminates), and the first optical laminate
- the optical laminated body having a polarizing film thicker than the polarizing film as a set
- the optical layered body (first optical layered body) of the present invention is disposed on the side opposite to the viewing side of the liquid crystal cell, and the second optical layered body is disposed on the viewing side of the liquid crystal cell.
- the use efficiency of the backlight can be improved by including the reflective polarizing film in the optical laminate.
- the price of liquid crystal display devices has been reduced, leading to a reduction in luminance of liquid crystal panels.
- the optical laminate of the present invention can also contribute to the suppression of such reduction in luminance. That is, according to the optical layered body of the present invention, two effects of suppressing the warpage of the liquid crystal panel and preventing the reduction in luminance can be realized at the same time. Furthermore, according to the optical layered body of the present invention, a liquid crystal panel having high contrast can be realized.
- the transmission axis of the polarizing film 110 and the transmission axis of the reflective polarizing film 120 can form any suitable angle depending on the purpose.
- the transmission axis of the polarizing film 110 and the transmission axis of the reflective polarizing film 120 are substantially parallel.
- the polarizing film 110 has a thickness of 10 ⁇ m or less, preferably 7 ⁇ m or less, and more preferably 5 ⁇ m or less.
- stacked such a thin polarizing film and the reflective polarizing film can suppress the curvature of a liquid crystal panel.
- the thickness is preferably 1 ⁇ m or more.
- the thickness is less than 1 ⁇ m, sufficient optical properties may not be obtained. Furthermore, according to the present invention, it is possible to maintain high contrast while suppressing warping of the liquid crystal panel using a very thin polarizing film. In general, the thinner the polarizing film, the lower its optical characteristics tend to be. However, according to the present invention, by integrating the thin polarizing film with the reflective polarizing film, the thickness of the polarizing film can be reduced. An excellent effect of suppressing warpage can be realized, and a decrease in optical characteristics due to the thinning of the polarizing film can be compensated. Such coexistence of effects is particularly remarkable when the optical laminate of the present invention is used on the side opposite to the viewing side of the liquid crystal panel. This is because the reflective polarizing film enhances the utilization efficiency of the backlight, thereby making it possible to compensate for the deterioration of the optical characteristics of the thin polarizing film very well.
- the polarizing film 110 is composed of a polyvinyl alcohol resin (hereinafter referred to as “PVA resin”) film containing a dichroic substance.
- PVA resin polyvinyl alcohol resin
- dichroic substance examples include iodine and organic dyes. These may be used alone or in combination of two or more. Preferably, iodine is used.
- any appropriate resin can be used as the PVA resin for forming the PVA resin film.
- Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer.
- Polyvinyl alcohol is obtained by saponifying polyvinyl acetate.
- the ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer.
- the degree of saponification of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. .
- the degree of saponification can be determined according to JIS K 6726-1994. By using a PVA resin having such a saponification degree, a polarizing film having excellent durability can be obtained. If the degree of saponification is too high, there is a risk of gelation.
- the average degree of polymerization of the PVA resin can be appropriately selected according to the purpose.
- the average degree of polymerization is usually 1000 to 10,000, preferably 1200 to 4500, and more preferably 1500 to 4300.
- the average degree of polymerization can be determined according to JIS K 6726-1994.
- the polarizing film preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm.
- the degree of polarization at a single transmittance of 42% of the polarizing film is preferably 99.0% or more, more preferably 99.9% or more.
- the contrast of the display device can be improved by using the reflective polarizing film in combination with a polarizing film.
- a linearly polarized light separation type reflective polarizing film is typically mentioned.
- FIG. 2 is a schematic cross-sectional view of an example of the reflective polarizing film used in the present invention.
- the reflective polarizing film 120 is a multilayer laminate in which layers A having birefringence and layers B having substantially no birefringence are alternately laminated.
- the refractive index nx in the x-axis direction of the A layer is larger than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction and the refractive index ny in the y-axis direction of the B layer are substantially equal.
- the difference in refractive index between the A layer and the B layer is large in the x-axis direction and is substantially zero in the y-axis direction.
- the x-axis direction becomes the reflection axis
- the y-axis direction becomes the transmission axis.
- the refractive index difference in the x-axis direction between the A layer and the B layer is preferably 0.2 to 0.3.
- the x-axis direction corresponds to the stretching direction of the reflective polarizing film in the production method (A-5) described later.
- the A layer is preferably made of a material that exhibits birefringence by stretching.
- Typical examples of such materials include naphthalene dicarboxylic acid polyester (for example, polyethylene naphthalate), polycarbonate, and acrylic resin (for example, polymethyl methacrylate). Polyethylene naphthalate is preferred.
- the B layer is preferably made of a material that does not substantially exhibit birefringence even when stretched.
- a typical example of such a material is a copolyester of naphthalenedicarboxylic acid and terephthalic acid.
- the reflective polarizing film transmits light having a first polarization direction (for example, p-wave) at the interface between the A layer and the B layer, and has a second polarization direction orthogonal to the first polarization direction. (For example, s wave) is reflected.
- the reflected light is partially transmitted as light having the first polarization direction and partially reflected as light having the second polarization direction at the interface between the A layer and the B layer.
- the light utilization efficiency can be increased by repeating such reflection and transmission many times inside the reflective polarizing film.
- the reflective polarizing film 120 includes a reflective layer R as the outermost layer opposite to the polarizing film 110 as shown in FIG.
- a reflective layer R as the outermost layer opposite to the polarizing film 110 as shown in FIG.
- the total thickness of the reflective polarizing film can be appropriately set according to the purpose, the total number of layers included in the reflective polarizing film, and the like.
- the total thickness of the reflective polarizing film is preferably 50 ⁇ m to 600 ⁇ m.
- the reflective polarizing film for example, those described in JP-T-9-507308 can be used.
- the reflective polarizing film 120 a commercially available product may be used as it is, or a commercially available product may be used after secondary processing (for example, stretching).
- a commercial item 3M company brand name DBEF is mentioned, for example.
- a protective film may be disposed on at least one side of the polarizing film (not shown).
- the material for forming the protective film include (meth) acrylic resins, cellulose resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin resins, olefin resins such as polypropylene, and ester resins such as polyethylene terephthalate resin. Examples thereof include resins, polyamide resins, polycarbonate resins, and copolymer resins thereof.
- the thickness of the protective film is preferably 20 ⁇ m to 100 ⁇ m.
- the protective film may be laminated on the polarizing film via an adhesive layer (specifically, an adhesive layer or an adhesive layer), or may be laminated in close contact with the polarizing film (without an adhesive layer). Also good.
- the adhesive layer is formed of any appropriate adhesive. Examples of the adhesive include a vinyl alcohol adhesive.
- the polarizing film 110 is manufactured by any appropriate method as long as the thickness can be satisfied.
- the polarizing film is typically produced by subjecting a PVA resin film to treatments such as stretching and dyeing as appropriate.
- the PVA resin film may be, for example, a PVA resin film or a PVA resin layer formed on a substrate.
- stretching method examples include fixed end stretching using a tenter stretching machine, free end stretching using rolls having different peripheral speeds, biaxial stretching using a simultaneous biaxial stretching machine, and sequential biaxial stretching. These may be employed alone or in combination of two or more.
- a PVA-based resin film is passed through rolls having different peripheral speeds and stretched in the transport direction (MD) (free end stretching), for example, it can be combined with stretching in a direction perpendicular to the transport direction (TD).
- MD transport direction
- TD transport direction perpendicular to the transport direction
- the said polarizing film forms the PVA-type resin layer on a thermoplastic resin base material, and produces the laminated body (laminated body preparation process), and the process of extending
- laminated body preparation process laminated body preparation process
- stretch a laminated body stretch stretching a laminated body
- a laminated body is produced by forming a PVA-type resin layer on a thermoplastic resin base material.
- the laminate is typically formed in a long shape.
- thermoplastic resin substrate has any appropriate configuration as long as it can support the PVA resin layer and the obtained polarizing film from one side.
- the thickness of the thermoplastic resin substrate (before stretching) is preferably 50 ⁇ m to 250 ⁇ m. If it is less than 50 ⁇ m, there is a risk of breaking during stretching. In addition, the thickness may become too thin after stretching, which may make conveyance difficult. If it exceeds 250 ⁇ m, an excessive load may be applied to the stretching machine. Moreover, there exists a possibility that conveyance may become difficult.
- thermoplastic resin substrate examples include ester resins such as polyethylene terephthalate resin, cycloolefin resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. Can be mentioned. Among these, cycloolefin resins (for example, norbornene resins) and amorphous polyethylene terephthalate resins are preferable. Specific examples of the amorphous polyethylene terephthalate resin include a copolymer further containing isophthalic acid as a dicarboxylic acid, and a copolymer further containing cyclohexanedimethanol as a glycol.
- ester resins such as polyethylene terephthalate resin, cycloolefin resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. Can be mentioned. Among these, cycloolefin
- the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 170 ° C. or lower. By using such a thermoplastic resin base material, it is possible to stretch the laminate at a temperature at which crystallization of the PVA resin does not proceed rapidly, and defects due to the crystallization (for example, the PVA resin layer due to stretching). Which prevents orientation).
- the glass transition temperature (Tg) is a value determined according to JIS K 7121.
- the surface of the thermoplastic resin substrate may be subjected to surface modification treatment (for example, corona treatment), or an easy adhesion layer may be formed on the thermoplastic resin substrate.
- surface modification treatment for example, corona treatment
- an easy adhesion layer may be formed on the thermoplastic resin substrate.
- a PVA-based resin layer is formed by applying a coating solution containing a PVA-based resin on a thermoplastic resin substrate and drying it.
- the coating solution is typically a solution obtained by dissolving the PVA resin in a solvent.
- the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These may be used alone or in combination of two or more. Among these, water is preferable.
- the concentration of the PVA resin in the solution is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the thermoplastic resin substrate can be formed.
- Additives may be added to the coating solution.
- the additive include a plasticizer and a surfactant.
- the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin.
- the surfactant include nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability and stretchability of the resulting PVA resin layer.
- any appropriate method can be adopted as a coating method of the coating solution. Examples thereof include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (comma coating method, etc.).
- the drying temperature is preferably not higher than the glass transition temperature (Tg) of the thermoplastic resin substrate, more preferably not higher than Tg-20 ° C.
- Tg glass transition temperature
- the thermoplastic resin base material is prevented from being deformed before the PVA resin layer is formed, and the orientation of the resulting PVA resin layer is prevented from deteriorating. Can do.
- the thermoplastic resin substrate can be deformed well together with the PVA-based resin layer, and the later-described laminate can be satisfactorily contracted and stretched. As a result, good orientation can be imparted to the PVA-based resin layer, and a polarizing film having excellent optical properties can be obtained.
- the thickness of the PVA-based resin layer can be set to any appropriate value depending on the desired polarizing film. In one embodiment, the thickness is preferably 20 ⁇ m or less, more preferably 5 ⁇ m to 15 ⁇ m. Even such a thin thickness can be satisfactorily stretched by using the thermoplastic resin substrate. As a result, a thin polarizing film suitable for the present invention can be obtained favorably.
- the moisture content of the PVA resin layer is preferably 20% or less, more preferably 15% or less.
- the stretching of the laminate may be performed in one stage or in multiple stages. When performed in multiple stages, the stretch ratio of the laminate described later is the product of the stretch ratios of the respective stages. Moreover, the extending
- the stretching temperature of the laminate can be set to any appropriate value depending on the material for forming the thermoplastic resin substrate.
- the stretching temperature is typically not less than the glass transition temperature (Tg) of the thermoplastic resin substrate, preferably Tg + 10 ° C. or more, more preferably Tg + 15 ° C. or more of the thermoplastic resin substrate. It is.
- the stretching temperature of the laminate is preferably 170 ° C. or lower.
- the stretching temperature is preferably 85 ° C. or lower, more preferably 30 ° C. to 65 ° C. If the temperature exceeds 85 ° C., there is a risk that iodine adsorbed on the PVA-based resin may be eluted, or that the PVA-based resin may be eluted, and the optical characteristics of the obtained polarizing film may be deteriorated.
- a thermoplastic resin substrate that can be stretched even at the above temperature is selected.
- amorphous polyethylene terephthalate resin, olefin resin (for example, polymethylpentene) or the like is used as the forming material.
- the PVA resin layer can be provided with rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water.
- boric acid can generate a tetrahydroxyborate anion in an aqueous solution and can be cross-linked with a PVA resin by hydrogen bonding, and can impart rigidity and water resistance.
- the aqueous boric acid solution is obtained by dissolving boric acid and / or borate in water as a solvent.
- the boric acid concentration is usually 1 to 10 parts by weight per 100 parts by weight of water.
- the immersion time of the laminate in the stretching bath is preferably about 15 seconds to 5 minutes.
- the laminate is contracted in the first direction and stretched in the second direction.
- the uniaxiality in the second direction can be improved and excellent optical properties can be obtained.
- the second direction is substantially the absorption axis direction of the obtained polarizing film.
- the shrinkage of the laminate may be performed simultaneously with the stretching or may be performed at another timing. Further, the order is not limited, and the laminate may be contracted in one stage or may be contracted in multiple stages. In one embodiment, preferably, the laminate is contracted in the first direction and then stretched in the second direction. In another embodiment, the laminate is preferably contracted in the first direction while being stretched in the second direction.
- a method of shrinking the laminate separately from stretching a method of heating (thermally shrinking) the laminate is preferable. The heating temperature is preferably equal to or higher than the glass transition temperature (Tg) of the thermoplastic resin substrate.
- the shrinkage rate in the first direction of the laminate is preferably 40% or less. With such a shrinkage rate, excellent durability can be achieved. On the other hand, the shrinkage rate is preferably 5% or more.
- the second direction can be set to any appropriate direction depending on the polarizing film.
- the second direction and the first direction are orthogonal to each other.
- the first direction is the direction (MD) of transporting the thermoplastic resin substrate
- the second direction is preferably a direction (TD) orthogonal to the transport direction.
- the first direction is a direction (TD) orthogonal to the transport direction
- the second direction is preferably a transport direction (MD) direction.
- the second direction is a direction (TD) orthogonal to the transport direction.
- the thermoplastic resin substrate is in a state before stretching by stretching in the second direction, heat, or the like. And the laminate can be contracted more uniformly in the first direction. Thus, excellent in-plane uniformity can be obtained even with a high shrinkage rate.
- the draw ratio in the second direction of the laminate is preferably 4.0 times or more with respect to the original length of the laminate. By contracting in the first direction, stretching at such a high magnification becomes possible, and a polarizing film having excellent optical properties can be obtained.
- the upper limit of the draw ratio in the single-stage drawing is about 5.0 times. This is because the laminate may be broken.
- a step of stretching the laminate in the air at a high temperature for example, 95 ° C. or more
- a high temperature for example, 95 ° C. or more
- Such an air stretching step can be positioned as preliminary or auxiliary stretching for boric acid water stretching, and is hereinafter referred to as “air-assisted stretching”.
- the laminate can be stretched at a higher magnification by combining air-assisted stretching.
- a thin polarizing film having more excellent optical characteristics for example, the degree of polarization
- the laminate can be stretched at a higher magnification by stretching while suppressing the orientation of the thermoplastic resin substrate.
- the orientation of the PVA-based resin can be improved, whereby the orientation of the PVA-based resin can be improved even after stretching in boric acid water.
- the PVA resin is easily cross-linked with boric acid during boric acid water stretching, and boric acid is a nodal point. It is presumed that the orientation of the PVA-based resin is increased even after stretching in boric acid solution by being stretched in such a state. As a result, a thin polarizing film having excellent optical characteristics (for example, the degree of polarization) can be produced.
- the stretching method for air-assisted stretching may be fixed-end stretching or free-end stretching (for example, uniaxial stretching through a laminate between rolls having different peripheral speeds).
- the stretching may be performed in one stage or in multiple stages. When performed in multiple stages, the draw ratio described below is the product of the draw ratios at each stage.
- the stretching direction in this step is preferably substantially the same as the second direction.
- the stretching ratio in the air auxiliary stretching is preferably 3.5 times or less.
- the stretching temperature in the air auxiliary stretching is preferably equal to or higher than the glass transition temperature (Tg) of the PVA resin.
- the stretching temperature is preferably 95 ° C to 150 ° C.
- the maximum draw ratio in the case of combining the air auxiliary stretching and the boric acid solution stretching is preferably 5.0 times or more, more preferably 5.5 times or more, and further preferably, the original length of the laminate. Is 6.0 times or more.
- Examples of the process for producing the polarizing film include a dyeing process, an insolubilizing process, a crosslinking process, a washing process, and a drying process in addition to the stretching process. These processes can be performed at any appropriate timing.
- the dyeing process is typically a process of dyeing a PVA resin film with the dichroic substance.
- the dichroic substance is adsorbed on the PVA resin film.
- the adsorption method for example, a method of immersing a PVA resin film (laminate) in a staining liquid containing a dichroic substance, a method of applying a staining liquid to a PVA resin film, and a staining liquid on a PVA resin film The method of spraying etc. are mentioned.
- it is a method of immersing a PVA resin film (laminated body) in a staining solution containing a dichroic substance. It is because a dichroic substance can adsorb
- both surfaces of the laminate may be immersed in the dyeing solution, or only one surface may be immersed.
- the staining solution is preferably an iodine aqueous solution.
- the amount of iodine is preferably 0.04 to 5.0 parts by weight per 100 parts by weight of water.
- an iodide salt is added to the aqueous iodine solution.
- Examples of the iodide salt include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide.
- Examples include titanium. Among these, potassium iodide and sodium iodide are preferable.
- the blending amount of the iodide salt is preferably 0.3 to 15 parts by weight with respect to 100 parts by weight of water.
- the liquid temperature during staining of the staining liquid is preferably 20 ° C. to 40 ° C.
- the immersion time is preferably 5 seconds to 300 seconds. Under such conditions, the dichroic substance can be sufficiently adsorbed on the PVA resin film.
- the insolubilization treatment and the crosslinking treatment are typically performed by immersing a PVA resin film in an aqueous boric acid solution.
- the cleaning treatment is typically performed by immersing a PVA resin film in an aqueous potassium iodide solution.
- the drying temperature in the drying treatment is preferably 30 ° C. to 100 ° C.
- a reflective polarizing film can be produced by a combination of coextrusion and transverse stretching. Coextrusion can be performed in any suitable manner. For example, a feed block method or a multi-manifold method may be used. For example, the material constituting the A layer and the material constituting the B layer are extruded in a feed block, and then multilayered using a multiplier. Such a multi-layer apparatus is known to those skilled in the art. Next, the obtained multilayer laminate is typically stretched in a direction (TD) perpendicular to the transport direction.
- TD direction
- the material constituting the A layer increases the refractive index only in the stretching direction due to the transverse stretching, and as a result, develops birefringence.
- the refractive index of the material constituting the B layer does not increase in any direction even by the transverse stretching.
- a reflective polarizing film having a reflection axis in the stretching direction (TD) and a transmission axis in the transport direction (MD) can be obtained (TD corresponds to the x-axis direction in FIG. 2 and MD is in the y-axis direction). Corresponding to).
- stretching operation can be performed using arbitrary appropriate apparatuses.
- A-5-3 Method for Producing Optical Laminate
- an adhesive layer typically, an adhesive layer or a pressure-sensitive adhesive layer.
- the polarizing film and the reflective film can be bonded together by roll-to-roll.
- the set of optical laminates of the present invention is 5 ⁇ m or more than the thickness of the optical laminate (first optical laminate) described in the above section A and the polarizing film of the first optical laminate. It is comprised with the 2nd optical laminated body containing a thick polarizing film.
- the second optical “laminate” is referred to, but the second optical laminate may be composed of a polarizing film alone. Practically, the second optical laminate is provided with a protective film on at least one side of the polarizing film. Any appropriate polarizing film can be adopted as the polarizing film as long as the above thickness condition is satisfied. Specific examples include polarizing films according to the polarizing films described in the above sections A-2 and A-5-1.
- a PVA film is used as the PVA resin film.
- Any appropriate film can be adopted as the protective film. Typical examples include the protective film described in the above section A-4.
- the first optical laminate is disposed on the side opposite to the viewing side of the liquid crystal cell, and the second optical laminate is disposed on the viewing side of the liquid crystal cell.
- the difference between the thickness of the polarizing film of the second optical laminate and the thickness of the polarizing film of the first optical laminate is preferably 10 ⁇ m or more.
- the difference in thickness is preferably 30 ⁇ m or less. If the difference in thickness exceeds 30 ⁇ m, the liquid crystal panel may be warped (in this case, a convex warp on the side opposite to the viewing side) due to the difference in thickness.
- the thickness of the polarizing film of the second optical laminate is preferably 15 ⁇ m or more, more preferably 18 ⁇ m or more.
- the thickness of the polarizing film of the second optical laminate is preferably 30 ⁇ m or less.
- the difference between the thickness of the polarizing film of the second optical laminated body and the thickness of the polarizing film of the first optical laminated body is set to a desired range. Easy to set.
- FIG. 3 is a schematic sectional view of a liquid crystal panel according to a preferred embodiment of the present invention.
- the liquid crystal panel 400 includes the liquid crystal cell 200, the second optical laminate 300 disposed on the viewing side of the liquid crystal cell 200, and the optical laminate 100 of the present invention disposed on the opposite side of the viewing side of the liquid crystal cell 200. And have.
- the optical layered body 100 of the present invention is disposed on the side opposite to the viewing side of the liquid crystal cell. As described above, the optical layered body 100 of the present invention is practically provided with a protective film on at least one side of the polarizing film, and the polarizing film 110 is disposed on the liquid crystal cell side.
- the second optical laminate is also practically provided with a protective film on at least one side of the polarizing film, and is arranged so that the polarizing film is on the liquid crystal cell side (not shown).
- the absorption axis of the polarizing film of the second optical laminate 300 and the absorption axis of the polarizing film 110 of the optical laminate 100 are orthogonal to each other.
- the absorption axis (extension axis) of the polarizing film of the second optical laminate 300 and the reflection axis (extension axis) of the reflective polarizing film 120 of the optical laminate 100 are orthogonal to each other.
- the liquid crystal panel 400 may further include any appropriate optical member. Examples of the optical member include a protective film and a retardation film.
- the liquid crystal cell 200 includes a pair of substrates 210 and 210 ′ and a liquid crystal layer 220 as a display medium sandwiched between the substrates 210 and 210 ′.
- One substrate color filter substrate
- the other substrate active matrix substrate
- a signal line (not shown) for supplying a source signal and a pixel electrode (not shown) are provided.
- the color filter may be provided on the active matrix substrate side.
- a distance (cell gap) between the substrates 210 and 210 ′ is controlled by a spacer (not shown).
- a spacer for example, an alignment film (not shown) made of polyimide is provided on the side of the substrates 210 and 210 ′ in contact with the liquid crystal layer 220.
- any appropriate driving mode can be adopted as the driving mode of the liquid crystal cell.
- the drive mode include STN (Super Twisted Nematic) mode, TN (Twisted Nematic) mode, IPS (In-Plane Switching) mode, VA (Vertical Aligned AlignedHiddenHide) Examples include Aligned Nematic mode, ASM (Axial Symmetrical Aligned Microcell) mode, ECB (Electrically Controlled Birefringence) mode, and the like.
- thermoplastic resin base material As a thermoplastic resin base material, a long cycloolefin resin film (trade name “ARTON” manufactured by JSR Corporation) having a thickness of 200 ⁇ m and a Tg of 123 ° C. was used.
- thermoplastic resin base material a long cycloolefin resin film (trade name “ARTON” manufactured by JSR Corporation) having a thickness of 200 ⁇ m and a Tg of 123 ° C. was used.
- PVA Polyvinyl alcohol
- PVA polyvinyl alcohol
- saponification degree of 98 to 99% trade name “GOHSENOL (registered trademark) NH-18” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.
- An aqueous polyvinyl alcohol solution was prepared.
- the coating solution was applied to one side of the thermoplastic resin substrate by a die coater (die coating method), and then dried at 100 ° C. for 180 seconds to form a PVA resin layer having a thickness of 11 ⁇ m. In this way, a long laminate was produced.
- ⁇ Crosslinking treatment> The layered product after dyeing was immersed in an aqueous boric acid solution at 60 ° C. (boric acid concentration: 5% by weight, potassium iodide concentration: 5% by weight) for 60 seconds.
- a protective film (TAC film manufactured by Fuji Film Co., Ltd., trade name “Fujitac”, thickness: 40 ⁇ m) was bonded to the polarizing film side of the laminate through a vinyl alcohol adhesive. Furthermore, the thermoplastic resin base material was peeled from this laminate, and the same protective film was bonded to the side of the polarizing film from which the thermoplastic resin base material was peeled. Thus, the polarizing film 1 was produced.
- thermoplastic resin base material As a thermoplastic resin substrate, an isophthalic acid copolymerized polyethylene terephthalate film (thickness: 200 ⁇ m) obtained by copolymerizing 6 mol% of isophthalic acid having a Tg of 75 ° C. was used.
- PVA Polyvinyl alcohol
- a polyvinyl alcohol aqueous solution was prepared. (Formation of PVA resin layer)
- the coating solution was applied to one side of the thermoplastic resin substrate by a die coater (die coating method), and then dried at 60 ° C. for 300 seconds to form a PVA resin layer having a thickness of 10 ⁇ m. In this way, a long laminate was produced.
- ⁇ Boric acid underwater stretching treatment> Thereafter, the laminate was immersed in a boric acid aqueous solution (an aqueous solution obtained by blending 5 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70 ° C.
- a boric acid aqueous solution an aqueous solution obtained by blending 5 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water
- uniaxial stretching was performed in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds to obtain an optical film laminate.
- the draw ratio in the boric acid underwater drawing treatment was 3.3 times, and the total draw ratio was 6.0 times.
- the optical film laminate was immersed in a washing bath (an aqueous solution obtained by blending 3 parts by weight of potassium iodide with respect to 100 weights of water) and then dried with hot air at 60 ° C. In this way, a polarizing film having a thickness of 4.5 ⁇ m was obtained on the thermoplastic resin substrate.
- a washing bath an aqueous solution obtained by blending 3 parts by weight of potassium iodide with respect to 100 weights of water
- a protective film (TAC film manufactured by Fuji Film Co., Ltd., trade name “Fujitac”, thickness: 40 ⁇ m) was bonded to the polarizing film side of the laminate through a vinyl alcohol adhesive. Furthermore, the thermoplastic resin base material was peeled from this laminate, and the same protective film was bonded to the side of the polarizing film from which the thermoplastic resin base material was peeled. Thus, the polarizing film 2 was produced.
- the obtained stretched film was immersed in an aqueous solution containing 5% by weight of potassium iodide for 10 seconds and dried in an oven at 40 ° C. for 3 minutes to obtain a polarizing film having a thickness of 20 ⁇ m.
- a protective film (TAC film manufactured by Fuji Film Co., Ltd., trade name “Fujitac”, thickness: 40 ⁇ m) was bonded to both sides of this polarizing film via a vinyl alcohol adhesive to obtain a polarizing film 3.
- Example 1 Production of optical laminate
- the polarizing film 1 obtained in Reference Example 1 and a commercially available reflective polarizing film (manufactured by 3M, trade name “DBEF”, thickness: 100 ⁇ m) are bonded together with a roll-to-roll via a vinyl alcohol adhesive, and optical.
- a laminate 1 was obtained.
- the film was bonded so that the transmission axis of the polarizing film and the transmission axis of the reflective polarizing film were parallel.
- Example 2 Production of optical laminate
- An optical laminate 2 was obtained in the same manner as in Example 1 except that the polarizing film 2 obtained in Reference Example 2 was used.
- Example 3 Production of liquid crystal panel
- the optical laminated body 1 was mounted on the liquid crystal cell by removing the optical laminated body on the side opposite to the viewing side of the liquid crystal panel (manufactured by Sharp Corporation, VA mode, panel size 400 mm ⁇ 220 mm).
- the optical layered body on the viewing side was removed, and the polarizing film 3 was mounted on the liquid crystal cell.
- the polarizing film 3 was mounted on the liquid crystal cell.
- the absorption axis of the polarizing film of the optical laminated body 1 and the absorption axis of the polarizing film of the polarizing film 3 may mutually cross substantially orthogonally.
- a liquid crystal panel was thus produced.
- This liquid crystal panel was subjected to the evaluations (1) and (2) above. The evaluation results are shown in Table 1 together with the results of Example 4 described later and Comparative Examples 2 to 3 and Reference Example 4.
- Example 4 Comparative Examples 2 to 3 and Reference Example 4
- a liquid crystal panel was produced in the same manner as in Example 3 except that the members were used in the combinations shown in Table 1 above.
- the obtained liquid crystal panel was subjected to the same evaluation as in Example 3. The evaluation results are shown in Table 1.
- the liquid crystal panel in which the optical laminate of the present invention is disposed on the side opposite to the viewing side and a relatively thick polarizing film is disposed on the viewing side (in other words, the set of the optical laminate of the present invention is It can be seen that the arranged liquid crystal panel) has very little warpage and high contrast.
- optical laminate and the liquid crystal panel of the present invention can be suitably used for a liquid crystal display device.
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Abstract
Description
好ましい実施形態においては、上記偏光膜は横延伸により得られたものである。
本発明の別の局面によれば、光学積層体のセットが提供される。この光学積層体のセットは、上記の光学積層体である第1の光学積層体と、該第1の光学積層体の偏光膜の厚みよりも5μm以上厚い偏光膜を含む第2の光学積層体とで構成される。
本発明のさらに別の局面によれば、液晶パネルが提供される。本発明の液晶パネルは、液晶セルと上記の光学積層体とを有する。
本発明の別の液晶パネルは、液晶セルと上記の光学積層体のセットとを有し、上記第2の光学積層体が視認側に配置され、上記第1の光学積層体が視認側と反対側に配置されている。
A-1.光学積層体の全体の構成
図1は、本発明の1つの実施形態による光学積層体の概略断面図である。光学積層体100は、偏光膜110と反射偏光フィルム120とを有する。偏光膜110は、その厚みが10μm以下である。偏光膜110と反射偏光フィルム120とは、任意の適切な接着層(具体的には、粘着剤層、接着剤層)を介して積層されていてもよく、密着(接着層を介さずに)積層されていてもよい。本発明によれば、このような薄い偏光膜と反射偏光フィルムとを積層することにより、液晶パネルの反りを抑制することができる。また、詳細は後述するように、本発明の光学積層体(以下、光学積層体のセットに関して言及する際には第1の光学積層体とも称する場合がある)と、当該第1の光学積層体の偏光膜よりも厚い偏光膜を有する第2の光学積層体をセットとして用いることにより、このような効果がより顕著なものとなり得る。より具体的には、本発明の光学積層体(第1の光学積層体)を液晶セルの視認側と反対側に配置し、かつ、第2の光学積層体を液晶セルの視認側に配置することにより、液晶パネルの反りを顕著に抑制し、結果として表示ムラや光漏れを防止することができる。さらに、本発明によれば、光学積層体に反射偏光フィルムが含まれていることにより、バックライトの利用効率を向上させることができる。近年、液晶表示装置の低価格化が進むことにより液晶パネルの低輝度化につながっているところ、本発明の光学積層体は、このような低輝度化の抑制にも貢献し得る。すなわち、本発明の光学積層体によれば、液晶パネルの反りの抑制と低輝度化の防止という2つの効果を同時に実現することができる。さらに、本発明の光学積層体によれば、高いコントラストを有する液晶パネルを実現することができる。
偏光膜110は、上記のとおり、その厚みが10μm以下であり、好ましくは7μm以下であり、より好ましくは5μm以下である。上記のとおり、このような薄い偏光膜と反射偏光フィルムとを積層した本発明の光学積層体は、液晶パネルの反りを抑制することができる。特に、本発明の光学積層体(第1の光学積層体)を、当該第1の光学積層体の偏光膜よりも厚い偏光膜を有する第2の光学積層体とセットで用いることにより、液晶パネルの反りを顕著に抑制することができる。一方で、厚みは、好ましくは1μm以上である。厚みが1μm未満であると、十分な光学特性が得られないおそれがある。さらに、本発明によれば、非常に薄い偏光膜を用いて液晶パネルの反りを抑制しつつ、高いコントラストを維持することができる。一般に、偏光膜を薄くすればするほどその光学特性は低下する傾向にあるが、本発明によれば、薄い偏光膜を反射偏光フィルムと一体化することにより、偏光膜の薄型化による液晶パネルの反りの抑制という優れた効果を実現し、かつ、偏光膜の薄型化による光学特性の低下を補填することができる。このような効果の両立は、本発明の光学積層体を液晶パネルの視認側と反対側に用いる場合に特に顕著である。反射偏光フィルムがバックライトの利用効率を高めることにより、薄型偏光膜の光学特性の低下を非常に良好に補填することができるからである。
本発明の光学積層体においては、反射偏光フィルムを偏光膜と組み合わせて用いることにより、表示装置のコントラストを向上させることができる。反射偏光フィルム120としては、代表的には、直線偏光分離型の反射偏光フィルムが挙げられる。図2は、本発明に用いられる反射偏光フィルムの一例の概略断面図である。反射偏光フィルム120は、複屈折性を有する層Aと複屈折性を実質的に有さない層Bとが交互に積層された多層積層体である。例えば、図示例では、A層のx軸方向の屈折率nxがy軸方向の屈折率nyより大きく、B層のx軸方向の屈折率nxとy軸方向の屈折率nyとは実質的に同一である。したがって、A層とB層との屈折率差は、x軸方向において大きく、y軸方向においては実質的にゼロである。その結果、x軸方向が反射軸となり、y軸方向が透過軸となる。A層とB層とのx軸方向における屈折率差は、好ましくは0.2~0.3である。なお、x軸方向は、後述する製造方法(A-5項)における反射偏光フィルムの延伸方向に対応する。
本発明の光学積層体においては、偏光膜の少なくとも一方の側に保護フィルムが配置されてもよい(図示せず)。保護フィルムの形成材料としては、例えば、(メタ)アクリル系樹脂、ジアセチルセルロース、トリアセチルセルロース等のセルロース系樹脂、シクロオレフィン系樹脂、ポリプロプレン等のオレフィン系樹脂、ポリエチレンテレフタレート系樹脂等のエステル系樹脂、ポリアミド系樹脂、ポリカーボネート系樹脂、これらの共重体樹脂等が挙げられる。なお、上記C項の熱可塑性樹脂基材を、そのまま保護フィルムとして用いてもよい。
A-5-1.偏光膜の製造方法
偏光膜110は、上記厚みを満足し得る限り、任意の適切な方法により製造される。偏光膜は、代表的には、PVA系樹脂膜に、適宜、延伸、染色等の処理を施すことにより製造される。PVA系樹脂膜は、例えば、PVA系樹脂フィルムであってもよいし、基材上に形成されたPVA系樹脂層であってもよい。
積層体は、熱可塑性樹脂基材上にPVA系樹脂層を形成することにより作製される。積層体は、代表的には、長尺状に形成される。
積層体の延伸は、一段階で行ってもよいし、多段階で行ってもよい。多段階で行う場合、後述の積層体の延伸倍率は、各段階の延伸倍率の積である。また、本工程における延伸方式は、特に限定されず、空中延伸方式でもよいし、水中延伸方式でもよい。
偏光膜を製造するための処理としては、延伸処理以外に、例えば、染色処理、不溶化処理、架橋処理、洗浄処理、乾燥処理等が挙げられる。これらの処理は、任意の適切なタイミングで施し得る。
反射偏光フィルムは、代表的には、共押出と横延伸とを組み合わせて作製され得る。共押出は、任意の適切な方式で行われ得る。例えば、フィードブロック方式であってもよく、マルチマニホールド方式であってもよい。例えば、フィードブロック中でA層を構成する材料とB層を構成する材料とを押出し、次いで、マルチプライヤーを用いて多層化する。なお、このような多層化装置は当業者に公知である。次いで、得られた多層積層体を代表的には搬送方向に直交する方向(TD)に延伸する。A層を構成する材料(例えば、ポリエチレンナフタレート)は、当該横延伸により延伸方向においてのみ屈折率が増大し、結果として複屈折性を発現する。B層を構成する材料(例えば、ナフタレンジカルボン酸とテレフタル酸とのコポリエステル)は、当該横延伸によってもいずれの方向にも屈折率は増大しない。結果として、延伸方向(TD)に反射軸を有し、搬送方向(MD)に透過軸を有する反射偏光フィルムが得られ得る(TDが図2のx軸方向に対応し、MDがy軸方向に対応する)。なお、延伸操作は、任意の適切な装置を用いて行われ得る。
上記A-5-1項で得られた偏光膜と上記A-5-2項で得られた反射偏光フィルムとを任意の適切な方法で積層することにより、本発明の光学積層体が得られる。代表的には、偏光膜と反射フィルムとは接着層(代表的には、接着剤層または粘着剤層)を介して貼り合わせられる。上記のように、偏光膜がTDに吸収軸を有する実施形態においては、偏光膜と反射フィルムとをロールトゥロールで貼り合わせることができる。
本発明の光学積層体のセットは、上記A項に記載した光学積層体(第1の光学積層体)と、当該第1の光学積層体の偏光膜の厚みよりも5μm以上厚い偏光膜を含む第2の光学積層体とで構成される。なお、便宜上、第2の光学「積層体」と称しているが、第2の光学積層体は、偏光膜単独で構成されてもよい。実用的には、第2の光学積層体は、偏光膜の少なくとも片側に保護フィルムが設けられている。偏光膜としては、上記厚みの条件を満足する限り、任意の適切な偏光膜が採用され得る。具体例としては、上記A-2項およびA-5-1項に記載の偏光膜に準じた偏光膜が挙げられ、好ましくは、PVA系樹脂膜としてPVA系フィルムが用いられる。保護フィルムとしては、任意の適切なフィルムが採用され得る。代表例としては、上記A-4項に記載の保護フィルムが挙げられる。代表的には、第1の光学積層体は液晶セルの視認側と反対側に配置され、第2の光学積層体は液晶セルの視認側に配置される。このような光学積層体のセットをこのような位置関係で用いることにより、液晶パネルの反りをきわめて良好に抑制することができる。
C-1.液晶パネルの全体構成
図3は、本発明の好ましい実施形態による液晶パネルの概略断面図である。液晶パネル400は、液晶セル200と、液晶セル200の視認側に配置された第2の光学積層体300と、液晶セル200の視認側とは反対側に配置された本発明の光学積層体100とを有する。本発明の光学積層体100は、液晶セルの視認側と反対側に配置される。本発明の光学積層体100は、上記したように、実用的には偏光膜の少なくとも片側に保護フィルムが設けられて、偏光膜110が液晶セル側となるよう配置されている。第2の光学積層体もまた、実用的には偏光膜の少なくとも片側に保護フィルムが設けられており、偏光膜が液晶セル側となるよう配置されている(図示せず)。液晶パネル400においては、第2の光学積層体300の偏光膜の吸収軸と光学積層体100の偏光膜110の吸収軸とは直交している。その結果、第2の光学積層体300の偏光膜の吸収軸(延伸軸)と光学積層体100の反射偏光フィルム120の反射軸(延伸軸)とは、直交している。図示しないが、液晶パネル400は、任意の適切な光学部材をさらに有していてもよい。光学部材としては、例えば、保護フィルム、位相差フィルム等が挙げられる。
液晶セル200は、一対の基板210、210’と、基板210、210’間に挟持された表示媒体としての液晶層220とを有する。一方の基板(カラーフィルター基板)には、カラーフィルターおよびブラックマトリクス(いずれも図示せず)が設けられている。他方の基板(アクティブマトリクス基板)には、液晶の電気光学特性を制御するスイッチング素子(代表的にはTFT)(図示せず)と、このスイッチング素子にゲート信号を与える走査線(図示せず)およびソース信号を与える信号線(図示せず)と、画素電極(図示せず)とが設けられている。なお、カラーフィルターは、アクティブマトリクス基板側に設けてもよい。基板210、210’の間隔(セルギャップ)は、スペーサー(図示せず)によって制御されている。基板210、210’の液晶層220と接する側には、例えば、ポリイミドからなる配向膜(図示せず)が設けられている。
実施例および比較例で得られた液晶パネルを80℃のオーブンに24時間投入した。液晶パネルをオーブンから取り出して1時間後に反り量を測定した。反り量は、測定すべき液晶パネルをその凸面が下側になるようにガラス板に載置して、ガラス板から液晶パネルの4つの角の高さをそれぞれ測定した。4角のうち一番大きい値で評価した。本実施例では、視認側と反対側に凸の反りを+で表し、視認側に凸の反りを-で表す。
(2)パネルコントラスト
実施例および比較例で得られた液晶パネルについて、BM-5(トプコン(株)製)を用いて当該液晶パネルの黒表示と白表示の輝度を測定し、その比(白輝度/黒輝度)として算出した。
(3)透過率
紫外可視分光光度計(日本分光社製、製品名「V7100」)を用いて、薄型偏光膜の単体透過率(Ts)、平行透過率(Tp)および直交透過率(Tc)を測定した。なお、上記Ts、TpおよびTcは、JIS Z 8701の2度視野(C光源)により測定し、視感度補正を行ったY値である。
<積層体の作製>
(熱可塑性樹脂基材)
熱可塑性樹脂基材として、長尺状で厚み200μm、Tg123℃のシクロオレフィン系樹脂フィルム(JSR社製、商品名「ARTON」)を用いた。
(塗布液の調製)
重合度1800、ケン化度98~99%のポリビニルアルコール(PVA)樹脂(日本合成化学工業社製、商品名「ゴーセノール(登録商標)NH-18」)を水に溶解させて、濃度7重量%のポリビニルアルコール水溶液を調製した。
(PVA系樹脂層の形成)
上記熱可塑性樹脂基材の片面に、上記塗布液をダイコーター(ダイコート法)により塗布した後、100℃で180秒間乾燥して、厚み11μmのPVA系樹脂層を形成した。このようにして、長尺の積層体を作製した。
得られた長尺の積層体を、テンター延伸機を用いて、140℃で、積層体の長手方向と直交する方向に4.5倍に空中延伸した。
次いで、積層体を、25℃のヨウ素水溶液(ヨウ素濃度:0.5重量%、ヨウ化カリウム濃度:10重量%)に30秒間浸漬させた。
染色後の積層体を、60℃のホウ酸水溶液(ホウ酸濃度:5重量%、ヨウ化カリウム濃度:5重量%)に60秒間浸漬させた。
架橋処理後、積層体を、25℃のヨウ化カリウム水溶液(ヨウ化カリウム濃度:5重量%)に5秒間浸漬させた。
このようにして、熱可塑性樹脂基材上に、厚み2μmの偏光膜を作製した(偏光膜の単体透過率(Ts):41%)。
積層体の偏光膜側にビニルアルコール系接着剤を介して保護フィルム(富士フィルム社製TACフィルム、商品名「フジタック」、厚み:40μm)を貼り合わせた。さらに、この積層体から熱可塑性樹脂基材を剥離し、偏光膜の熱可塑性樹脂基材が剥離された側に同じ保護フィルムを貼り合わせた。このようにして、偏光フィルム1を作製した。
<積層体の作製>
(熱可塑性樹脂基材)
熱可塑性樹脂基材として、Tg75℃のイソフタル酸を6モル%共重合させたイソフタル酸共重合ポリエチレンテレフタレートフィルム(厚み:200μm)を用いた。
(塗布液の調製)
重合度2600、ケン化度99.9%のポリビニルアルコール(PVA)樹脂(日本合成化学工業社製、商品名「ゴーセノール(登録商標)NH-26」)を水に溶解させて濃度7重量%のポリビニルアルコール水溶液を調製した。
(PVA系樹脂層の形成)
上記熱可塑性樹脂基材の片面に、上記塗布液をダイコーター(ダイコート法)により塗布した後、60℃で300秒間乾燥して、厚み10μmのPVA系樹脂層を形成した。このようにして、長尺の積層体を作製した。
得られた長尺の積層体を、130℃のオーブン内で周速の異なるロール間で縦方向(長手方向)に1.8倍に自由端一軸延伸した。
その後、積層体を液温30℃の不溶化浴(水100重量部に対して、ホウ酸を3重量部配合して得られたホウ酸水溶液)に30秒間浸漬させた。
次いで、液温30℃の染色浴(水100重量部に対して、ヨウ素を0.2重量部配合し、ヨウ化カリウムを1.4重量部配合して得られたヨウ素水溶液)に、最終的に得られる薄型偏光膜の単体透過率(Ts)が41%となるように浸漬させた。
次いで、液温30℃の架橋浴(水100重量部に対して、ヨウ化カリウムを3重量部配合し、ホウ酸を3重量部配合して得られたホウ酸水溶液)に60秒間浸漬させた。
その後、積層体を、液温70℃のホウ酸水溶液(水100重量部に対して、ホウ酸を5重量部配合し、ヨウ化カリウムを5重量部配合して得られた水溶液)に浸漬させながら、周速の異なるロール間で縦方向(長手方向)に一軸延伸を行い、光学フィルム積層体を得た。ホウ酸水中延伸処理における延伸倍率を3.3倍とし、総延伸倍率は6.0倍であった。
その後、光学フィルム積層体を洗浄浴(水100重量に対して、ヨウ化カリウムを3重量部配合して得られた水溶液)に浸漬させた後、60℃の温風で乾燥させた。
このようにして、熱可塑性樹脂基材上に厚み4.5μmの偏光膜を得た。
積層体の偏光膜側にビニルアルコール系接着剤を介して保護フィルム(富士フィルム社製TACフィルム、商品名「フジタック」、厚み:40μm)を貼り合わせた。さらに、この積層体から熱可塑性樹脂基材を剥離し、偏光膜の熱可塑性樹脂基材が剥離された側に同じ保護フィルムを貼り合わせた。このようにして、偏光フィルム2を作製した。
厚み75μmのポリビニルアルコールフィルムを、28℃温水中に60秒間浸漬して膨潤させた。次に、ヨウ素およびヨウ化カリウム(重量比1:10)を含む水溶液に浸漬して、3.3倍まで延伸しながら、所定の単体透過率となるように染色した。その後、3重量%のホウ酸および2重量%のヨウ化カリウムを含む水溶液中に10秒間浸漬し、60℃の4重量%のホウ酸および3重量%のヨウ化カリウムを含む水溶液中で延伸倍率が計6.0倍となるように延伸した。その後、得られた延伸フィルムを、5重量%のヨウ化カリウムを含む水溶液に10秒間浸漬し、40℃のオーブンで3分間乾燥して、厚み20μmの偏光膜を得た。この偏光膜の両側にビニルアルコール系接着剤を介して保護フィルム(富士フィルム社製TACフィルム、商品名「フジタック」、厚み:40μm)を貼り合わせ、偏光フィルム3を得た。
参考例1で得られた偏光フィルム1と市販の反射偏光フィルム(3M社製、商品名「DBEF」、厚み:100μm)とを、ビニルアルコール系接着剤を介してロールトゥロールで貼り合わせ、光学積層体1を得た。貼り合わせに際しては、偏光膜の透過軸と反射偏光フィルムの透過軸とが平行となるように貼り合わせた。
参考例2で得られた偏光フィルム2を用いたこと以外は実施例1と同様にして、光学積層体2を得た。
参考例3で得られた偏光フィルム3を用いたこと以外は実施例1と同様にして、光学積層体3を得た。
液晶パネル(シャープ社製、VAモード、パネルサイズ400mm×220mm)の視認側とは反対側の光学積層体を取り除いて、液晶セルに光学積層体1を実装した。次に、視認側の光学積層体を取り除いて、液晶セルに偏光フィルム3を実装した。ここで、光学積層体1の偏光膜の吸収軸と偏光フィルム3の偏光膜の吸収軸とが互いに実質的に直交するように実装した。このようにして液晶パネルを作製した。この液晶パネルを上記(1)~(2)の評価に供した。評価結果を後述の実施例4ならびに比較例2~3および参考例4の結果と併せて表1に示す。
上記表1の組み合わせで部材を用いたこと以外は実施例3と同様にして液晶パネルを作製した。得られた液晶パネルを実施例3と同様の評価に供した。評価結果を表1に示す。
110 偏光膜
120 反射偏光フィルム
200 液晶セル
300 第2の光学積層体
400 液晶パネル
Claims (5)
- 厚み10μm以下の偏光膜と反射偏光フィルムとを有する、光学積層体。
- 前記偏光膜が横延伸により得られたものである、請求項1に記載の光学積層体。
- 請求項1または2に記載の光学積層体である第1の光学積層体と、該第1の光学積層体の偏光膜の厚みよりも5μm以上厚い偏光膜を含む第2の光学積層体とで構成される、光学積層体のセット。
- 液晶セルと請求項1または2に記載の光学積層体とを有する、液晶パネル。
- 液晶セルと請求項3に記載の光学積層体のセットとを有する液晶パネルであって、
前記第2の光学積層体が視認側に配置され、前記第1の光学積層体が視認側と反対側に配置されている、
液晶パネル。
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CN201280038201.XA CN103718073B (zh) | 2011-08-05 | 2012-07-25 | 光学层压体、光学层压体套件和使用所述光学层压体或所述光学层压体套件的液晶面板 |
EP12821906.0A EP2741112A4 (en) | 2011-08-05 | 2012-07-25 | LAMINATED OPTICAL BODY, SET OF LAMINATED OPTICAL BODIES AND LIQUID CRYSTAL PLATE WITH THE LAMINATED OPTICAL BODY OR THE SET OF LAMINATED OPTICAL BODIES |
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US14/130,211 US9164210B2 (en) | 2011-08-05 | 2012-07-25 | Optical laminated body, optical laminated body set, and liquid crystal panel using optical laminated body or optical laminated body set |
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JP6083924B2 (ja) | 2017-02-22 |
TW201312176A (zh) | 2013-03-16 |
JP2013037115A (ja) | 2013-02-21 |
EP2741112A1 (en) | 2014-06-11 |
KR101972186B1 (ko) | 2019-04-24 |
CN103718073A (zh) | 2014-04-09 |
KR101983881B1 (ko) | 2019-05-29 |
EP2741112A4 (en) | 2015-03-04 |
CN103718073B (zh) | 2016-03-09 |
US9164210B2 (en) | 2015-10-20 |
US20140125925A1 (en) | 2014-05-08 |
KR20140041821A (ko) | 2014-04-04 |
KR20150142071A (ko) | 2015-12-21 |
TWI571658B (zh) | 2017-02-21 |
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