TWI755364B - Manufacturing method of optically anisotropic film - Google Patents
Manufacturing method of optically anisotropic film Download PDFInfo
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- TWI755364B TWI755364B TW105130441A TW105130441A TWI755364B TW I755364 B TWI755364 B TW I755364B TW 105130441 A TW105130441 A TW 105130441A TW 105130441 A TW105130441 A TW 105130441A TW I755364 B TWI755364 B TW I755364B
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- film
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- width direction
- optically anisotropic
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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
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/14—Protective coatings, e.g. hard coatings
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- 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
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
- B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
- B29C55/08—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique transverse to the direction of feed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- 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
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/22—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of tubes
- B29C55/24—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of tubes radial
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/02—Diffusing elements; Afocal elements
- G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
- G02B5/0257—Diffusing elements; Afocal elements characterised by the diffusing properties creating an anisotropic diffusion characteristic, i.e. distributing output differently in two perpendicular axes
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3083—Birefringent or phase retarding elements
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
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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
- G02F1/13363—Birefringent elements, e.g. for optical compensation
Abstract
本發明提供一種光學異向性膜,該光學異向性膜不易產生延伸時之膜之斷裂,且寬度方向之光學特性均一而有效寬度較寬。 本發明之異向性光學異向性膜之製造方法包含如下步驟:藉由抓持件(51)抓持帶狀之延伸對象膜(10)之寬度方向兩端部(11e);及一面使抓持件於膜(10)之長度方向(MD)上移動,一面使寬度方向上之抓持件間之距離擴大,藉此,使膜於寬度方向(TD)上延伸。於在延伸對象膜(10)之寬度方向端部(11e)重疊有帶狀之附設膜(15、17)之狀態下,進行利用抓持件(51)之抓持。附設膜之至少1層包含與延伸對象膜之至少1層相同之材料。The present invention provides an optically anisotropic film, the optically anisotropic film is not prone to film breakage during extension, and has uniform optical properties in the width direction and a wide effective width. The manufacturing method of the anisotropic optically anisotropic film of the present invention comprises the steps of: grasping the width direction both ends (11e) of the strip-shaped extending object film (10) by a grasping member (51); The gripper moves in the longitudinal direction (MD) of the film (10), while expanding the distance between the grippers in the width direction, thereby extending the film in the width direction (TD). The gripping by the gripper (51) is performed in a state where the tape-shaped attachment films (15, 17) are superimposed on the widthwise end portion (11e) of the film (10) to be stretched. At least one layer of the attached film contains the same material as at least one layer of the film to be stretched.
Description
本發明係關於一種偏光元件或相位差膜等光學異向性膜之製造方法。The present invention relates to a method for producing an optically anisotropic film such as a polarizing element or a retardation film.
於液晶顯示裝置等顯示器中使用偏光板或相位差板等光學異向性膜。藉由使聚合物膜於至少一方向上延伸而賦予光學異向性。工業上使聚合物膜延伸之情形時,一般地,一面使帶狀之膜於長度方向移動,一面進行延伸處理。 於拉幅機方式之橫向延伸時,藉由夾具等抓持件抓持膜之兩端,以一面使抓持件沿著導軌於長度方向(MD)移動一面使寬度方向(TD)之間隔擴大之方式驅動,藉此,使帶狀膜於寬度方向上延伸。亦可藉由採用線性馬達方式、縮放儀方式、馬達·鏈條方式等驅動方式,而一面改變長度方向之夾具間隔一面擴大寬度方向之夾具間距離,進行縱橫同時雙軸延伸或斜方向延伸(例如參照專利文獻1及專利文獻2)。以下,只要未特別說明,則只要為進行寬度方向上之延伸者,則如縱橫同時雙軸延伸、斜方向延伸般進行長度方向之延伸或收縮之情形亦包含於「橫向延伸」。 橫向延伸於能夠調整膜之光軸方向或能夠製作寬度較大之光學異向性膜之方面有利。另一方面,於橫向延伸時,有時於由針或夾具抓持之部分之附近產生膜之斷裂,寬度方向之延伸倍率越大,則該傾向越顯著。 於專利文獻1中,揭示有如下方法,即,為了防止橫向延伸時之膜之斷裂等而於膜10之兩端部貼合膠帶35(參照圖3B)。於專利文獻3中,揭示有如下方法,即,於成為延伸對象之帶狀膜之端部,重疊撕裂強度較延伸對象高之補強片,並利用針梳拉幅機抓持該重疊部分,藉此,抑制因針孔擴大所致之膜之脫離或斷裂。於專利文獻4中揭示有如下內容,即,藉由使用膜之寬度方向中央部與膜之寬度方向端部由不同之樹脂材料形成之膜,可防止橫向延伸時之膜之寬度方向端部之破裂。 [先前技術文獻] [專利文獻] [專利文獻1]日本專利特開2013-54338號公報 [專利文獻2]日本專利特開2014-54338號公報 [專利文獻3]日本專利特開平11-254521號公報 [專利文獻4]日本專利特開2009-160900號公報Optical anisotropic films, such as a polarizing plate and a retardation plate, are used for displays, such as a liquid crystal display device. Optical anisotropy is imparted by extending the polymer film in at least one direction. When industrially extending a polymer film, generally, the extending process is performed while moving the tape-shaped film in the longitudinal direction. In the lateral extension of the tenter method, the two ends of the film are held by gripping members such as clamps, and the gap in the width direction (TD) is expanded while moving the gripping members along the guide rail in the longitudinal direction (MD) and the width direction (TD). It is driven in such a way that the strip-shaped film is extended in the width direction. It is also possible to use a linear motor method, a pantograph method, a motor-chain method, etc., while changing the distance between the clamps in the length direction and expanding the distance between the clamps in the width direction, to perform vertical and horizontal simultaneous biaxial extension or oblique direction extension (for example Refer to
[發明所欲解決之問題] 對光學膜之薄型化或大面積化之要求提高,要求使厚度更小之膜以高倍率延伸而賦予特定之光學異向性。又,於藉由橫向延伸製作光學異向性膜之情形時,要求防止端部之斷裂或自抓持件脫離,而且要求寬度方向之端部之光學特性均一。若寬度方向之延伸倍率變大,則有如下傾向,即,膜之寬度方向端部附近之光學軸方向之偏差變大,而難以獲得有效寬度較大之膜。 如專利文獻1、2中揭示般,藉由膠帶等補強材對膜端部進行補強之方法可抑制抓持部附近之膜之斷裂,但對於寬度方向之光學特性之均一化而言稱不上有效。 若使用如專利文獻3揭示般之寬度方向之端部包含與中央部不同之材料之膜,則可選擇性地使膜之寬度方向中央部延伸,因此,使中央部均一地延伸,而獲得有效寬度較大之膜。但是,寬度方向之端部包含與中央部不同之材料之膜必須於膜形成時採用特殊之成膜方法,成為成本提高之主要原因。又,若延伸倍率增大,則於中央部與端部之邊界、即異種樹脂材料之接合部附近容易產生斷裂。又,有如下情形,即,隨著延伸倍率增大,而容易於樹脂材料之接合部附近產生應力之不均衡,從而光學特性變得不均一。 鑒於該等情況,本發明之目的在於提供一種光學異向性膜,該光學異向性膜即便於寬度方向之延伸倍率較大之情形時,亦不易產生延伸時之膜之斷裂或自抓持件脫離,且寬度方向之光學特性均一而有效寬度較寬。 [解決問題之技術手段] 本發明之光學異向性膜之製造方法包含如下步驟:藉由抓持件抓持帶狀之延伸對象膜之寬度方向兩端部;及一面使抓持件於延伸對象膜之長度方向上移動,一面使寬度方向上之抓持件間之距離擴大,而使延伸對象膜於寬度方向上延伸。於在延伸對象膜之寬度方向端部重疊有帶狀之附設膜之狀態下,進行利用夾具等抓持件之抓持。 與延伸對象膜重疊之附設膜之至少1層包含與延伸對象膜之至少1層相同之材料。於延伸對象膜為單層膜之情形時,附設膜包含與延伸對象膜相同之材料。於延伸對象膜包含複數層之情形時,附設膜包含含有與構成延伸對象膜之複數層中之至少1層相同之材料之層。 作為重疊包含與延伸對象膜相同之材料之附設膜之方法,可列舉將延伸對象膜之端部折回而折疊之方法或使延伸對象膜之切斷片重疊之方法。較佳為使延伸對象膜與附設膜不經由接著層而重疊。 [發明之效果] 根據本發明之方法,即便於橫向延伸倍率較大之情形時,亦不易產生膜之斷裂或自抓持件脫離,步驟之穩定性優異。進而,根據本發明之方法,獲得寬度方向之光學特性均一而有效寬度較寬之光學異向性膜。THE PROBLEM TO BE SOLVED BY THE INVENTION There is an increasing demand for thinning or increasing the area of optical films, and it is required to extend a film with a smaller thickness at a high magnification to impart specific optical anisotropy. In addition, in the case of producing an optically anisotropic film by lateral stretching, it is required to prevent breakage of the end portion or detachment from the gripper, and to have uniform optical properties of the end portion in the width direction. When the stretching magnification in the width direction becomes large, the variation in the optical axis direction in the vicinity of the end portion in the width direction of the film tends to become large, and it is difficult to obtain a film with a large effective width. As disclosed in
於本發明之光學異向性膜之製造方法中,一面使帶狀之延伸對象膜於長度方向(MD)上移動,一面進行寬度方向(TD)上之延伸(橫向延伸)。藉由夾具等抓持件抓持延伸對象膜之TD兩端部,一面使抓持有膜之抓持件於MD上移動,一面使TD上之抓持件間之距離擴大,藉此,使延伸對象膜於TD上延伸。 [延伸對象膜] 延伸對象膜為帶狀之長條膜。延伸對象膜之寬度一般為200 mm~2500 mm左右。延伸對象膜之長度一般為20 m~5000 m左右。 作為延伸對象膜之材料,可根據目的而使用任意之適當之樹脂材料。例如可列舉乙醯纖維素等纖維素系樹脂、聚酯系樹脂、聚碳酸酯系樹脂、聚醯胺系樹脂、聚醯亞胺系樹脂、馬來醯亞胺系樹脂、聚烯烴系樹脂、(甲基)丙烯酸系樹脂、環狀聚烯烴樹脂(降莰烯系樹脂)、聚芳酯系樹脂、聚苯乙烯系樹脂、聚乙烯醇系樹脂、聚碸系樹脂及該等之混合物或共聚物等。 延伸對象膜之厚度(延伸前)較佳為25 μm~300 μm,更佳為30 μm~200 μm,進而較佳為35 μm~150 μm。若膜之厚度過小,則容易產生抓持件之抓持部分之附近之膜之斷裂或膜自抓持件脫離。另一方面,若膜之厚度過大,則延伸時之張力變得過大,而可能成為膜自抓持件脫離或光學特性之均一性降低之原因。 延伸對象膜可為由1層構成之單層膜,亦可為將複數層密接積層而成之積層膜。作為將複數層密接積層而成之積層膜,可列舉:藉由多層共擠出或重疊塗佈等同時成膜複數層而成之多層膜;利用濺射法或CVD(Chemical Vapor Deposition,化學氣相沈積)法等於支持體膜上形成薄膜而成之積層體;藉由在支持體膜上塗佈樹脂溶液並使其乾燥而將支持體膜與樹脂塗膜密接積層而成之積層體等。 [延伸對象膜之抓持及延伸] 藉由抓持件抓持上述延伸對象膜之TD兩端部後,一面使抓持件於MD長度方向上移動,一面使TD上之抓持件間之距離擴大,藉此進行橫向延伸。 圖1係表示夾具拉幅機方式之橫向延伸之概要之俯視圖。於圖1所示之形態中,沿著一對導軌(未圖示)設置有鏈條,並於各鏈條設置有複數個抓持件51、52。於圖1中,虛線41、42表示鏈條之軌道。抓持件典型地為以將膜自兩面夾入之方式構成之夾具。夾具只要為能夠抓持膜者,則其形狀並無特別限定,可列舉圓形、橢圓形、四邊形等。 於已藉由夾具51、52抓持延伸對象膜10之兩端部之狀態下,使鏈條沿著導軌於MD移動,藉此,將帶狀之延伸對象膜10沿MD搬送。於一對導軌沿著MD以間隔擴大之方式設置之情形時,抓持膜之兩端之夾具51、52間之距離亦沿著MD擴大,因此,延伸對象膜10於TD上延伸。 於本形態中,於鏈條上以等間隔設置有夾具,因此,即便於已使鏈條移動之情形時,亦保持MD之夾具距離,而膜僅於TD上延伸。另一方面,作為使抓持件移動之方法,亦可採用線性馬達方式、縮放儀方式、馬達·鏈條方式等驅動方式,藉由使MD之夾具間隔發生變化而進行縱橫同時雙軸延伸或斜方向延伸。於同時雙軸延伸或斜方向延伸時,亦可藉由使MD之夾具間隔縮小,而使膜一面於TD上延伸一面於MD上收縮。 <膜之抓持> 圖2A~D及圖3A、B分別模式性表示利用夾具51抓持延伸對象膜10之TD端部之狀態,與圖1之II-II線上之剖面相對應。於本發明中,如圖2A~D所示,於延伸對象膜10之TD端部11e重疊與延伸對象膜相同材料之膜作為附設膜,並藉由抓持件抓持重疊有附設膜之部分。 作為重疊與延伸對象膜相同材料之附設膜之方法,可列舉將延伸對象膜於端部進行折疊之方法。於圖2A中,表示如下形態,即,將延伸對象膜10藉由在TD端部之彎折部13彎折180°而折回,於使折回部分15與延伸對象膜10重疊之狀態下藉由夾具51進行抓持。 將延伸對象膜於端部折疊之方法並無特別限定,可使用事先將端部折疊之膜,亦可於利用抓持件進行抓持之前一面搬送膜一面將端部折疊。一面搬送膜一面將膜之端部折疊之方法並無特別限定。例如,亦可藉由沿著平板或剖面U字狀、剖面V狀之導件將膜彎折而將膜折回。膜之端部可折疊成兩層,亦可折疊成三層以上。就效率或準確性之觀點而言,較佳為如圖2A所示般進行兩層之折疊(1次折回)。 將膜之端部折回之方向並無特別限定。於延伸對象膜之端部捲曲之情形時,就使膜向導件之導入或膜之折回容易之觀點而言,較佳為沿著捲曲之方向將膜折回。 膜之折回部分15之寬度只要為夾具51能夠充分地抓持折疊部分之範圍,則並無特別限制。折回部分15之寬度於例如20 mm~100 mm左右之範圍內適當進行調整。為了抓持件能夠確實地抓持折疊部分,較佳為彎折部13位於較抓持件之外緣更靠外側且折回部分15之端部位於較抓持件之內緣更靠內側(中央側)。 於圖2A所示之形態中,折回部分15於在端部折回之膜之彎折部13處相連,但經折疊之複數層膜亦可不必於彎折部連續。例如,即便於折回時或利用抓持件進行抓持時,於彎折部膜產生破裂,而彎折部不連續,只要能夠藉由抓持件抓持折回部分15,則並無影響。 作為重疊與延伸對象膜相同材料之附設膜之方法,除於端部折疊之方法以外,亦可列舉如下方法,即,如圖2B所示,使包含與延伸對象膜10相同之材料之窄幅之帶狀膜17與延伸對象膜10之TD端部11e重疊。作為所重疊之窄幅之帶狀膜,若利用延伸對象膜之切斷片,則無需用於準備附設膜之材料成本,故而較佳。作為切斷片,可使用TD端部之切割片。 切割片等切斷片可藉由事先對延伸對象膜之TD端部進行切割而準備。於該情形時,若材料與延伸對象膜相同,則亦可將不同製造批次之膜端部之切割片與延伸對象膜之端部重疊。亦可將於即將重疊之前自延伸對象膜之端部切除之切割片與切割後之延伸對象膜之端部重疊。例如,若一面使延伸對象膜移行一面進行TD端部之切割,並調整切割片之軋製線,則亦能夠於線內實施端部切割與切割片之重疊。 於使延伸對象膜10與切斷片17重疊之情形時,兩者之端面無須一致,只要夾具51能夠充分地抓持延伸對象膜10與切斷片17之重疊部分即可。重疊部分之寬度於例如20 mm~100 mm左右之範圍內適當進行調整。切斷片17之寬度亦於例如20 mm~100 mm左右之範圍內適當進行調整。為了抓持件能夠確實地抓持折疊部分,較佳為切斷片17之外側端面及延伸對象膜之端面位於較抓持件之外緣更靠外側,且切斷片17之內側端面位於較抓持件之內緣更靠內側(中央側)。 於折回部分15或切斷片17等附設膜與延伸對象膜10重疊之狀態下由夾具51抓持之情形時,抓持部分之厚度較延伸對象膜單獨之情形大,因此,抓持部分及其附近之機械強度增大,而抑制膜之斷裂。 附設膜與延伸對象膜之材料相同。又,延伸對象膜10之TD中央部11c與端部11e之材料亦相同。因此,遍及延伸對象膜之夾具抓持部分及夾具非抓持部分、以及附設膜之整體而材料相同,即便於延伸時之加熱環境等下,膜整體亦表現出同等之機械特性或熱行為。因此,即便於使兩端部之夾具間距離擴大而以高倍率於TD上延伸之情形時,亦不易產生材料之邊界附近之應力集中等局部之力學應變,而獲得寬度方向之光學均一性優異之光學異向性膜。 折回部分15或切斷片17等附設膜可直接重疊於延伸對象膜10上,亦可如圖2C或圖2D所示般經由雙面膠帶等接著層31而貼合於延伸對象膜10上。就使重疊有附設膜之端部與除此以外之部分之材料構成相同而使局部之力學應變減少的觀點而言,較佳為使延伸膜與附設膜不經由接著層等其他構件而重疊。 <橫向延伸> 藉由抓持件抓持重疊有帶狀之附設膜之延伸對象膜之TD端部後,一面使抓持件於MD移動,一面使TD上之抓持件間之距離擴大,藉此進行橫向延伸。 橫向延伸較佳為於加熱環境下進行。延伸方式可為空中延伸,亦可為水中延伸。於製造相位差膜時,一般於加熱爐內進行空中延伸。於製造偏光元件時,亦可藉由在經加熱之水中進行延伸而進行碘等二色性物質之染色或交聯等處理。 延伸溫度或延伸倍率(延伸後之膜寬度W1
相對於延伸前之膜寬度W0
之比W1
/W0
)可根據延伸對象膜之材料或所需之光學特性等而設定為任意之適當之值。延伸溫度代表性地於延伸對象膜之玻璃轉移溫度Tg±50℃左右之範圍內設定。延伸倍率代表性地為1.05倍~4倍左右。 關於橫向延伸後之膜,夾具51之抓持部分之寬度W1
與TD之夾具間距離相等,與此相對,未由夾具抓持之非抓持部之寬度Wni
小於W1
,而膜之端部成為彎曲成弓狀之形狀(縮幅現象)。若產生縮幅,則應力之方向變得不均一,因此,於TD端部,光學軸之配向角容易變得不均一。若縮幅之影響所波及之範圍擴大,則光學軸之配向角於寬度方向上之偏差變大,而光學異向性膜之有效寬度(配向角為特定範圍內之區域)變小。於本發明中,藉由在重疊有與延伸對象膜相同材料之附設膜之狀態下進行延伸,而因縮幅所致之光學軸之不均一化之影響限於TD端部附近,而獲得有效寬度較寬之光學異向性膜。 [積層膜之抓持及延伸] 以上,以延伸對象膜為單層膜之情形為中心進行了說明,但於延伸對象膜為包含複數層之積層膜之情形時,藉由重疊包含與延伸對象膜相同之材料之附設膜,亦獲得寬度方向之光學特性均一之光學異向性膜。 於延伸對象膜包含複數層之情形時,折回部分15或切斷片17等附設膜可為單層之膜,亦可為包含複數層之膜。於附設膜為單層之膜之情形時,附設膜只要與延伸對象膜之至少1層為相同材料即可。於附設膜為包含複數層之膜之情形時,只要使附設膜之至少1層與延伸對象膜之至少1層為相同材料即可。 就使膜整體之機械特性或熱行為同等之觀點而言,附設膜理想的是具有與延伸對象膜相同之積層構成之積層膜。另一方面,於延伸對象膜中之特定之層支配積層膜整體之機械特性或熱行為之情形時,附設膜只要包含含有與延伸對象膜中之特定之層相同之材料之層即可。 例如,於延伸對象膜10為於支持體膜上形成薄膜而成之積層體之情形或為將支持體膜與樹脂塗膜密接積層而成之積層體之情形時,與薄膜或樹脂塗膜相比,支持體膜之厚度較大,因此,延伸對象膜之熱行為、機械行為由支持體膜之特性支配。因此,附設膜只要包含與延伸對象膜之支持體相同之膜,則亦可不於支持體上形成薄膜或樹脂塗膜。 於藉由將樹脂溶液塗佈於支持體膜上並使其乾燥而形成將支持體膜與樹脂塗膜密接積層而成之積層體之情形時,一般地,於支持體膜之兩端部附近不塗佈樹脂溶液,因此,支持體膜之端部附近成為樹脂塗膜非形成部。樹脂塗膜非形成部為支持體膜單體,其積層構成與支持體和塗膜之積層體不同。另一方面,於支持體與塗膜之積層體,樹脂塗膜之厚度比支持體膜小,因此,積層體之熱行為、機械行為與支持體單體同等。因此,塗膜非形成部與塗膜形成部表現出同等之熱行為、機械行為。 於不將支持體膜與樹脂塗膜密接積層而成之積層體之樹脂塗膜非形成部切除而用作延伸對象膜的情形時,端部之折回部分之一部分或全部為樹脂塗膜非形成部。又,於使樹脂塗膜非形成部之切割片與延伸對象膜重疊之情形時,切割片之一部分或全部為樹脂塗膜非形成部。即便如此般重疊於延伸對象膜上之附設膜之面內之一部分或全部為支持體單體之樹脂塗膜非形成部,附設膜之熱行為、機械行為亦與支持體上包含樹脂塗膜之延伸對象膜同等,因此,與使用支持體與樹脂塗膜之積層體作為附設膜之情形同樣地,獲得寬度方向之光學特性均一之光學異向性膜。 使支持體膜與樹脂塗膜密接積層而成之積層體延伸之方法適合於使厚度較小(例如未達25 μm)且於單體之操作或橫向延伸較為困難之膜延伸。只要於使支持體膜與樹脂塗膜密接積層而成之積層體延伸後將支持體膜剝離,則容易獲得厚度較小之光學異向性膜。 又,若使用能夠於MD熱收縮之膜作為支持體膜,則與橫向延伸同時地於MD進行收縮之情形時,能夠進行遍及TD整體均一之收縮,而獲得光學特性之均一性優異之光學異向性膜。能夠於MD熱收縮之支持體膜可藉由預先於MD實施延伸處理而製作。作為能夠熱收縮之支持體膜之材料,較佳為使用聚乙烯、聚丙烯等聚烯烴類或聚酯類。 於支持體膜上密接積層樹脂塗膜而成之積層體有膜之端部容易以塗膜形成面成為內側之方式產生捲曲之傾向。因此,於將積層體於端部折疊之情形時,可容易地進行膜向導件之導入或折回,因此,較佳為沿著捲曲之方向以塗膜形成面側成為內側之方式進行折回。 [作為延伸後之膜之光學異向性膜之使用] 橫向延伸後之膜亦可直接作為相位差膜或偏光元件等光學異向性膜而供於實用。於延伸對象膜為支持體與塗膜之積層膜之情形時,可將積層膜直接用作光學異向性膜,亦可將支持體剝離而將延伸後之樹脂塗膜用作光學異向性膜。亦可將樹脂塗膜轉印至其他膜而形成光學異向性膜。 [實施例] 以下,列舉實施例對本發明更詳細地進行說明,但本發明並不限定於下述實施例。 [實施例1:積層膜之橫向延伸] 於實施例1中,進行於熱收縮性之支持體上形成塗膜而成之積層體之橫向延伸,並對因膜兩端部之抓持方法之差異所致的延伸膜之光學軸之均一性實施評價。 [聚芳酯系樹脂之合成及塗料之製備] 於具備攪拌裝置之反應容器中,使2,2-雙(4-羥基苯基)-4-甲基戊烷540重量份、氯化苄基三乙基銨12重量份溶解於1 M氫氧化鈉溶液中。一面對使對苯二甲醯氯304重量份與間苯二甲醯氯102重量份溶解於氯仿所得之溶液進行攪拌,一面將該溶液一次性添加至上述溶液中,並於室溫下攪拌90分鐘。其後,將聚合溶液靜置分離而分離出包含聚合物之氯仿溶液,繼而,利用乙酸水進行清洗,並利用離子交換水清洗,然後投入至甲醇中使聚合物析出。將所析出之聚合物利用蒸餾水清洗2次,並利用甲醇清洗2次,然後進行減壓乾燥。將所獲得之聚芳酯系樹脂溶解於環戊酮中,製備固形物成分濃度為20%之塗料。 [積層膜製作例1] 利用同時雙軸延伸機之拉幅機夾具抓持未延伸之聚對苯二甲酸乙二醇酯/聚間苯二甲酸乙二酯(PETI)膜之TD兩端部,於保持TD之夾具間距離之狀態下於MD上延伸,而獲得具有熱收縮性之PETI支持體膜(厚度:50 μm、寬度:1490 mm)。一面將該支持體沿MD搬送,一面於90℃下加熱15秒後,塗佈上述塗料,並使其於100℃下乾燥,於支持體上形成厚度21 μm之聚芳酯樹脂塗膜,而獲得厚度71 μm之積層膜。 [積層膜製作例2] 使用厚度50 μm之雙軸延伸聚丙烯(PP)膜作為支持體,除此以外,以與上述製作例1相同之方式獲得積層膜。 [積層膜之橫向延伸] 使用拉幅機夾具方式之雙軸延伸機,針對製作例1(PETI支持體)及製作例2(PP支持體)之各者,於下述水準1~5之條件下利用夾具抓持積層體之兩端部,一面於溫度145℃下於TD上延伸至1.3倍~1.6倍,一面縮小MD之夾具間距離而收縮至0.75倍。 水準1:將積層膜以單體之形式直接利用夾具抓持兩端部(參照圖3A) 水準2:於積層膜之兩端部之各者貼合耐熱膠帶(包括黏著層在內之厚度為79 μm、寬度40 mm),並利用夾具抓持膠帶貼合部分(參照圖3B) 水準3:使積層膜之切割片(寬度40 mm)與積層膜之兩端部重疊,並利用夾具抓持重疊部分(參照圖2B) 水準4:將積層膜之兩端部(寬度40 mm)以塗膜形成面側成為內側之方式折疊,並利用夾具抓持折疊部分(參照圖2A) 水準5:將積層膜之兩端部以塗膜形成面側成為內側之方式折疊,並利用雙面膠帶(厚度108 μm、寬度40 mm)貼合而固定,利用夾具抓持折疊部分(參照圖2C) [評價] (縮幅率) 根據延伸後之積層體之最大寬度(夾具之抓持部分之寬度)W1
與最小寬度(縮幅最大之部分之寬度)求出縮幅率。 縮幅率(%)=100×(W1
-Wni
)/W1
(光學軸之範圍) 自延伸後之積層體剝離支持體,使用偏光・相位差測定系統(Axometrics製造 產品名「AxoScan」),於TD之中央1400 mm之範圍內於TD以10 mm間隔對光學軸之配向角進行測定,將最大值與最小值之差設為光學軸範圍。將光學軸之配向角處於TD中央之光學軸配向角之±1°之範圍之區域之寬度設為有效寬度。 將製作例1(PETI支持體)及製作例2(PP支持體)之積層膜之橫向延伸後之縮幅率、有效寬度及光學軸範圍分別示於表1及表2。將對各水準下之縮幅率與光學軸範圍之關係進行繪圖所得者示於圖4。將對各水準下之延伸倍率與有效寬度之關係進行繪圖所得者示於圖4。再者,於表1及表2、以及下述之表3及表4中,未記載數值者表示於延伸中途膜產生斷裂。 [表1]
10‧‧‧延伸對象膜
11c‧‧‧TD中央部
11e‧‧‧端部
13‧‧‧彎折部
15‧‧‧附設膜(折回部分)
17‧‧‧附設膜(切斷片)
31‧‧‧雙面膠帶
35‧‧‧膠帶
41、42‧‧‧虛線
51‧‧‧抓持件
52‧‧‧抓持件
A‧‧‧抓持區域
B‧‧‧預熱區域
C‧‧‧延伸區域
C1‧‧‧入口側延伸區域
C2‧‧‧出口側延伸區域
D‧‧‧收縮區域
E‧‧‧釋放區域
MD‧‧‧長度方向
TD‧‧‧寬度方向
W0‧‧‧延伸前之膜寬度
W1‧‧‧延伸後之膜寬度
W2‧‧‧夾具間距離
Wni‧‧‧非抓持部之寬度10‧‧‧
圖1係表示橫向延伸之概要之俯視圖。 圖2A~D分別為表示本發明之方法中之膜端部之抓持狀態之模式性剖視圖。 圖3A及B分別為表示先前技術中之膜端部之抓持狀態之模式性剖視圖。 圖4(A)、(B)係對實施例1中之橫向延伸時之縮幅率與光學軸之範圍之關係進行繪圖所得的曲線圖。 圖5(A)、(B)係對實施例1中之橫向延伸時之延伸倍率與有效寬度(光學軸為±1°之範圍之部分)之關係進行繪圖所得的曲線圖。 圖6係用於對實施例2中之斜向延伸方法之概要進行說明之概念圖。FIG. 1 is a plan view showing the outline of the lateral extension. 2A to 2D are schematic cross-sectional views showing the gripping state of the film end in the method of the present invention, respectively. 3A and B are respectively schematic cross-sectional views showing the gripping state of the film end in the prior art. FIGS. 4(A) and (B) are graphs obtained by plotting the relationship between the shrinkage ratio and the range of the optical axis during lateral extension in Example 1. FIG. 5(A) and (B) are graphs obtained by plotting the relationship between the stretching magnification and the effective width (portion within the range of ±1° on the optical axis) during lateral stretching in Example 1. FIG. FIG. 6 is a conceptual diagram for explaining the outline of the oblique stretching method in
10‧‧‧延伸對象膜 10‧‧‧Extension target film
11c‧‧‧TD中央部 11c‧‧‧TD Central
11e‧‧‧端部 11e‧‧‧End
13‧‧‧彎折部 13‧‧‧Bending part
15‧‧‧附設膜(折回部分) 15‧‧‧Film attached (folded back part)
17‧‧‧附設膜(切斷片) 17‧‧‧Film attached (cut piece)
31‧‧‧雙面膠帶 31‧‧‧Double-sided tape
51‧‧‧抓持件 51‧‧‧Grip
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CN106990468A (en) | 2017-07-28 |
KR102512601B1 (en) | 2023-03-21 |
TW201718239A (en) | 2017-06-01 |
JP6836849B2 (en) | 2021-03-03 |
JP2017062459A (en) | 2017-03-30 |
CN106990468B (en) | 2021-04-09 |
KR20170036603A (en) | 2017-04-03 |
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