# US 8,771,454 B2 · Polarizing film, optical film laminate including polarizing film, and method for manufacturing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,454 B2 - Document ID: US8771454B2 - Status: Granted - Kind: B2 - Application number: 13/225,333 - Filed: 2011-09-02 - Published: 2012-03-08 - Granted: 2014-07-08 - Earliest claimed: 2010-09-03 - Assignees: Nitto Denko Corporation - Applicants: Shusaku Goto; Takeharu Kitagawa; Minoru Miyatake; Tomohiro Mori; Takashi Kamijo - Inventors: Shusaku Goto; Takeharu Kitagawa; Minoru Miyatake; Tomohiro Mori; Takashi Kamijo - Web page: https://patentgrep.com/patent/US8771454B2 ## CPC - G02B 5/30: Polarising elements (light-modulating devices with active elements G02F1/00) - B29C 55/026: {of preformed plates or sheets coated with a solution, a dispersion or a melt of thermoplastic material} - B29C 65/00: Joining {or sealing} of preformed parts {, e.g. welding of plastics materials}; Apparatus therefor {(general aspects of processes or apparatus for joining preformed parts B29C66/00; using porous material formed by internal pressure generated therein for joining preformed parts B29C44/1228, B29C44/326)} - G02B 5/3033: {in the form of a thin sheet or foil, e.g. Polaroid} - G02B 5/3083: {Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001)} - G02F 1/133528: {Polarisers} - B29D 11/00: Producing optical elements, e.g. lenses or prisms (grinding or polishing of optical elements B24B; constructional form of optical elements G02B; {optical parts of spectacles G02C7/00}) - B29K 2029/04: {PVOH, i.e. polyvinyl alcohol (B29K2031/04 takes precedence)} - B29K 2067/00: Use of polyesters {or derivatives thereof}, as moulding material - B29K 2995/0034: Polarising - C09K 2323/031: Polarizer or dye - G02B 1/14: Protective coatings, e.g. hard coatings - G02F 1/133638: {Waveplates, i.e. plates with a retardation value of lambda/n} - G02F 2201/50: Protective arrangements - G02F 2202/22: Antistatic materials or arrangements - G02F 2202/28: Adhesive materials or arrangements - Y10T 428/2495: Thickness [relative or absolute] - Y10T 428/265: 1 mil or less - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - 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 - B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00) - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An optical film laminate includes a substrate including a crystallizable ester type thermoplastic resin in the form of a continuous web; and a polarizing film including a polyvinyl alcohol type resin layer formed on the substrate, said polarizing film including a dichroic material impregnated therein in a molecularly oriented state, wherein the polarizing film is formed by providing a laminate including the polyvinyl alcohol type resin layer formed on a substrate including a crystallizable ester type thermoplastic resin in an amorphous state and subjecting the laminate to a 2-stage stretching process including a preliminary in-air stretching and an in-boric-acid-solution stretching under a temperature maintaining the amorphous state of the substrate, such that the polyvinyl alcohol type resin layer is stretched to a thickness of 10 μm or less, the polarizing film having optical properties based on the formulae P>−(100.929T−42.4−1) ×100 (where T<42.3) and P≧99.9 (where T≧42.3). ## Claims ### Claim 1 A method for manufacturing an optical film laminate in which a polarizing film made of a polyvinyl alcohol type resin having a dichroic material impregnated therein in a molecularly oriented state is formed on a substrate made of a crystallizable ester type thermoplastic resin in the form of a continuous web, comprising steps of: forming a stretched laminate comprising a stretched intermediate made of a molecularly oriented polyvinyl alcohol type resin by subjecting a laminate comprising a substrate made of a crystallizable ester type thermoplastic resin in an amorphous state and a polyvinyl alcohol type resin layer formed on the substrate to a preliminary in-air stretching under a temperature in which the amorphous state of the substrate can be maintained; forming a dyed laminate including a dyed intermediate comprising the polyvinyl alcohol type resin layer having a dichroic material impregnated therein in a molecularly oriented state by impregnating the dichroic material in the stretched laminate; and forming the optical film laminate including a polarizing film which is made of the polyvinyl alcohol type resin having the dichroic material impregnated therein in a molecularly oriented state and has a thickness of 10 μm or less, by stretching the dyed laminate in a boric acid solution, wherein the polarizing film having optical properties which satisfy conditions represented by the formulae: P>−(100.929T−42.4−1)×100 (where T<42.3); and P≧99.9 (where T≧42.3), where T represents a single layer transmittance, and P represents a polarization rate. ### Claim 2 (depends on 1) The method as defined in claim 1, wherein a stretching ratio of the preliminary in-air stretching is 3.5 or less. ### Claim 3 (depends on 1) The method as defined in claim 1, wherein the preliminary in-air stretching is performed at a temperature greater than a glass transition temperature of the polyvinyl alcohol type resin. ### Claim 4 (depends on 1) The method as defined in claim 1, wherein the stretching temperature of the preliminary in-air stretching is in a range of 80° C. to 120° C. ### Claim 5 (depends on 1) The method as defined in claim 1, wherein the dyed laminate is formed by immersing the stretched laminate in a dyeing solution comprised of the dichroic material. ### Claim 6 (depends on 5) The method as defined in claim 5, wherein the dyeing solution contains water as a solvent and iodine with a concentration in a range of 0.12 to 0.30 weight %. ### Claim 7 (depends on 1) The method as defined in claim 1, which further comprises a first insolubilization step of applying insolubilization to the stretched intermediate included in the stretched laminate before immersing the stretched laminate in the dyeing solution comprised of the dichroic material. ### Claim 8 (depends on 7) The method as defined in claim 7, wherein the first insolubilization step includes immersing the stretched laminate in a boric acid solution having a solution temperature of no more than 40° C. ### Claim 9 (depends on 1) The method as defined in claim 1, wherein the dyed laminate is stretched in the boric acid solution to allow the polarizing film to have a thickness of 10 μm or less. ### Claim 10 (depends on 1) The method as defined in claim 1, which further comprises an insolubilization step of applying insolubilization to the dyed laminate before stretching the dyed laminate in the boric acid solution. ### Claim 11 (depends on 1) The method as defined in claim 1, wherein the dyed laminate is subjected to the preliminary in-air stretching and the in-boric-acid-solution stretching to attain a total stretching ratio of 5.0 or more. ### Claim 12 (depends on 1) The method as defined in claim 1, wherein a solution temperature of the boric acid solution for the in-boric-acid-solution stretching is 60° C. or more. ### Claim 13 (depends on 1) The method as defined in claim 1, wherein, when the preliminary in-air stretching is performed in an end-free uniaxial stretching, a total stretching ratio for the dyed laminate is in a range of 5.0 to 7.5. ### Claim 14 (depends on 1) The method as defined in claim 1, wherein, when the preliminary in-air stretching is performed in an end-fixed uniaxial stretching, a total stretching ratio for the dyed laminate is in a range of 5.0 to 8.5. ### Claim 15 (depends on 1) The method as defined in claim 1, which further comprises a step of cleaning the optical film laminate including the polarizing film which is made of the polyvinyl alcohol type resin having the dichroic material impregnated therein in the molecularly oriented state and has a thickness of 10 μm or less, by a solution containing iodide salt having a solution temperature of no more than 40° C. ### Claim 16 (depends on 1) The method as defined in claim 1, which further comprises a step of attaching a separator film through an adhesive agent to a surface of the polarizing film opposite to the surface which is attached to the substrate included in the optical film laminate. ### Claim 17 (depends on 1) The method as defined in claim 1, which further comprises a step of attaching an optically functional film through a bonding agent to a surface of the polarizing film opposite to the surface which is attached to the substrate included in the optical film laminate. ### Claim 18 (depends on 17) The method as defined in claim 17, which further comprises a step of attaching a separator film through an adhesive agent to a surface of the optically functional film opposite to the surface which is attached to the polarizing film. ### Claim 19 A method for manufacturing an optical film laminate in which a polarizing film made of a polyvinyl alcohol type resin having a dichroic material impregnated therein in a molecularly oriented state is formed on a substrate made of a crystallizable ester type thermoplastic resin in the form of a continuous web, comprising steps of: forming a stretched laminate comprising a stretched intermediate made of a molecularly oriented polyvinyl alcohol type resin by subjecting a laminate comprising a substrate made of a crystallizable ester type thermoplastic resin in an amorphous state and a polyvinyl alcohol type resin layer formed on the substrate to a preliminary in-air stretching under a temperature in which the amorphous state of the substrate can be maintained; forming a dyed laminate including a dyed intermediate comprising the polyvinyl alcohol type resin layer having a dichroic material impregnated therein in a molecularly oriented state by impregnating the dichroic material in the stretched laminate; forming the optical film laminate including a polarizing film which is made of the polyvinyl alcohol type resin having the dichroic material impregnated therein in a molecularly oriented state and has a thickness of 10 μm or less, by stretching the dyed laminate in a boric acid solution; and a first insolubilization step of applying insolubilization to the stretched intermediate included in the stretched laminate before immersing the stretched laminate in the dyeing solution comprised of the dichroic material. ### Claim 20 (depends on 19) The method as defined in claim 19, wherein the polarizing film having optical properties which satisfy conditions represented by the formulae: P>−(100.929T−42.4−1)×100 (where T<42.3); and P≧99.9 (where T≧42.3), where T represents a single layer transmittance, and P represents a polarization rate. ### Claim 21 (depends on 19) The method as defined in claim 19, wherein a stretching ratio of the preliminary in-air stretching is 3.5 or less. ### Claim 22 (depends on 19) The method as defined in claim 19, wherein the dyed laminate is formed by immersing the stretched laminate in a dyeing solution comprised of the dichroic material, the dyeing solution contains water as a solvent and iodine with a concentration in a range of 0.12 to 0.30 weight %. ### Claim 23 (depends on 19) The method as defined in claim 19, wherein the first insolubilization step includes immersing the stretched laminate in a boric acid solution having a solution temperature of no more than 40° C. ### Claim 24 (depends on 19) The method as defined in claim 19, wherein the dyed laminate is stretched in the boric acid solution to allow the polarizing film to have a thickness of 10 μm or less. ### Claim 25 (depends on 19) The method as defined in claim 19, which further comprises a second insolubilization step of applying insolubilization to the dyed laminate before stretching the dyed laminate in the boric acid solution. ### Claim 26 (depends on 19) The method as defined in claim 19, wherein the dyed laminate is subjected to the preliminary in-air stretching and the in-boric-acid-solution stretching to attain a total stretching ratio of 5.0 or more. ### Claim 27 (depends on 19) The method as defined in claim 19, wherein, when the preliminary in-air stretching is performed in an end-fixed uniaxial stretching, a total stretching ratio for the dyed laminate is in a range of 5.0 to 8.5. ### Claim 28 (depends on 19) The method as defined in claim 19, which further comprises a step of cleaning the optical film laminate including the polarizing film which is made of the polyvinyl alcohol type resin having the dichroic material impregnated therein in the molecularly oriented state and has a thickness of 10 μm or less, by a solution containing iodide salt having a solution temperature of no more than 40° C. ### Claim 29 (depends on 19) The method as defined in claim 19, which further comprises a step of attaching an optically functional film through a bonding agent to a surface of the polarizing film opposite to the surface which is attached to the substrate included in the optical film laminate.