以下，對本發明之代表性之實施形態進行說明，但本發明並不限定於該等實施形態。
(用語及符號之定義)
本說明書中之用語及符號之定義如下所述。
(1)折射率(nx、ny、nz)
「nx」係面內之折射率成為最大之方向(即遲相軸方向)之折射率，「ny」係於面內與遲相軸正交之方向(即進相軸方向)之折射率，「nz」係厚度方向之折射率。
(2)面內相位差(Re)
「Re(λ)」係利用23℃下之波長λnm之光測定所得之膜之面內相位差。例如，「Re(450)」係利用23℃下之波長450 nm之光測定所得之膜之面內相位差。於將膜之厚度設為d(nm)時，Re(λ)係藉由式：Re＝(nx－ny)×d而求出。
(3)厚度方向之相位差(Rth)
「Rth(λ)」係利用23℃下之波長550 nm之光測定所得之膜之厚度方向之相位差。例如，「Rth(450)」係利用23℃下之波長450 nm之光測定所得之膜之厚度方向之相位差。於將膜之厚度設為d(nm)時，Rth(λ)係藉由式：Rth＝(nx－nz)×d而求出。
(4)Nz係數
Nz係數係藉由Nz＝Rth/Re而求出。
(5)nx＝ny、nx＝nz、ny＝nz
所謂nx＝ny，不僅包含nx與ny完全相同之情形，亦包含nx與ny實質上相同之情形。關於nx＝nz及ny＝nz之關係亦相同。
(6)實質上正交或平行
「實質上正交」及「大致正交」之表述包含2個方向所成之角度為90°±10°之情形，較佳為90°±7°，進而較佳為90°±5°。「實質上平行」及「大致平行」之表述包含2個方向所成之角度為0°±10°之情形，較佳為0°±7°，進而較佳為0°±5°。進而，簡稱為「正交」或「平行」時，亦可包含實質上正交或實質上平行之狀態。
(7)角度
於本說明書中，言及角度時，只要未特別明確記載，則該角度包含順時針及逆時針之兩方向之角度。
A.液晶顯示裝置之整體構成
圖1係本發明之一實施形態之液晶顯示裝置之概略剖視圖。於圖式中，為了便於觀察，各層及各光學構件之厚度之比率與實物不同。本實施形態之液晶顯示裝置500具備液晶面板100、配置於液晶面板100之視認側之相位差層200、及自背面側對液晶面板100進行照明之背光光源300。於圖示例中，亦可於液晶面板100與相位差層200之間進而配置另一相位差層400。根據目的、構成及所需特性等，亦可省略另一相位差層。再者，為便於說明，有時將相位差層200稱為第1相位差層，將另一相位差層400稱為第2相位差層。於本發明之實施形態中，第1相位差層200之面內相位差Re(550)為100 nm～180 nm，較佳為110 nm～170 nm，進而較佳為120 nm～160 nm，尤佳為135 nm～155 nm。進而，第1相位差層200滿足Re(450)＜Re(550)＜Re(650)之關係。此外，於本發明之實施形態中，背光光源300具有非連續之發光光譜。
液晶面板100包含液晶單元10、配置於液晶單元10之視認側之第1偏光元件20、及配置於液晶單元10之背面側之第2偏光元件30。第1偏光元件20之吸收軸相對於液晶面板100(液晶單元10)之長邊實質上正交或平行。又，第2偏光元件30之吸收軸亦相對於液晶面板100(液晶單元10)之長邊實質上正交或平行。再者，液晶面板之長邊既可為顯示畫面之左右方向，亦可為上下方向。第1偏光元件20之吸收軸與第2偏光元件30之吸收軸實質上正交。亦可於第1偏光元件20之單側或兩側配置保護膜(未圖示)。同樣地，亦可於第2偏光元件30之單側或兩側配置保護膜(未圖示)。
第1相位差層200之遲相軸與液晶面板100之長邊所成之角度為35°～55°，較佳為38°～52°，更佳為40°～50°，進而較佳為42°～48°，尤佳為44°～46°，尤佳為約45°。因此，第1相位差層200之遲相軸與第1偏光元件20之吸收軸所成之角度較佳為35°～55°，更佳為38°～52°，進而較佳為40°～50°，尤佳為42°～48°，尤佳為44°～46°，最佳為約45°。
於一實施形態中，亦可於第1偏光元件20與液晶單元10之間設置導電層(未圖示)。藉由設置此種導電層，液晶顯示裝置可作為於顯示單元(液晶單元)與偏光元件之間組入有觸控感測器之所謂之內置觸控面板型輸入顯示裝置發揮功能。
亦可視需要於第1偏光元件20與液晶單元10之間、及/或第2偏光元件30與液晶單元10之間配置任意適當之光學補償層(又一相位差層)。此種光學補償層之配置數量、組合、配置位置、配置順序、光學特性(例如折射率橢球、面內相位差、厚度方向相位差、Nz係數)、機械特性等可根據目的、液晶顯示裝置之構成及所需特性而適當地設定。
以下，對液晶顯示裝置之構成要素(光學膜、光學構件)進行說明。
B.液晶面板
B-1.液晶單元
液晶單元10具有一對基板11、12、及夾持於該基板間之作為顯示介質之液晶層13。於一般之構成中，於一基板11設置有彩色濾光片及黑矩陣，於另一基板12設置有控制液晶之電光學特性之開關元件、對該開關元件提供閘極信號之掃描線及提供源極信號之信號線、像素電極及對向電極。上述基板11、12之間隔(單元間隙)可藉由間隔件等進行控制。可於上述基板11、12之與液晶層13相接之側設置例如包含聚醯亞胺之配向膜等。
於一實施形態中，液晶層13包含於不存在電場之狀態下配向成沿面排列之液晶分子。代表性而言，此種液晶層(結果為液晶單元)之折射率橢球顯示出nx＞ny＝nz之關係。作為使用此種顯示出三維折射率之液晶層之驅動模式之代表例，可列舉橫向電場效應(IPS)模式、邊緣場切換(FFS)模式等。IPS模式包含採用V字型電極或鋸齒狀電極等之Super·In plane switching(S-IPS)模式或Advanced·Super·In plane switching(AS-IPS)模式。FFS模式包含採用V字型電極或鋸齒狀電極等之Advanced·Fringe-Field Switching(A-FFS)模式或Ultra Fringe-Field Switching(U-FFS)模式。使用此種於不存在電場之狀態下配向成沿面排列之液晶分子之驅動模式(例如IPS模式、FFS模式)中，不存在傾斜之階調顛倒，且傾斜視角較寬，故而具有自傾斜方向觀察時之視認性優異的優勢。
於另一實施形態中，液晶層13包含於不存在電場之狀態下配向成垂直排列之液晶分子。作為使用於不存在電場之狀態下配向成垂直排列之液晶分子之驅動模式，例如可列舉垂直配向(VA)模式。VA模式包含多疇VA(MVA)模式。使用此種於不存在電場之狀態下配向成垂直排列之液晶分子之驅動模式(例如VA模式)中，由於傾斜方向之半色調之透過率高於正面方向之半色調之透過率，因此具有自傾斜方向觀察之半色調明亮而發黑較少的優勢。
B-2.偏光元件
作為第1偏光元件20及第2偏光元件30，可採用任意適當之偏光元件。第1偏光元件20及第2偏光元件30之材料、厚度、光學特性等既可相同，亦可不同。以下，有時將第1偏光元件20及第2偏光元件30統稱為偏光元件。
形成偏光元件之樹脂膜既可為單層之樹脂膜，亦可為兩層以上之積層體。
作為由單層之樹脂膜構成之偏光元件之具體例，可列舉對聚乙烯醇(PVA)系膜、局部縮甲醛化PVA系膜、乙烯-乙酸乙烯酯共聚物系局部皂化膜等親水性高分子膜實施利用碘或二色性染料等二色性物質而進行之染色處理及延伸處理所成者、PVA之脫水處理物或聚氯乙烯之脫鹽酸處理物等多烯系配向膜等。就光學特性優異之方面而言，較佳為使用利用碘對PVA系膜進行染色並使之單軸延伸而獲得之偏光元件。
藉由上述碘而進行之染色例如可藉由將PVA系膜浸漬於碘水溶液中而進行。上述單軸延伸之延伸倍率較佳為3～7倍。延伸可於染色處理後進行，亦可一面進行染色一面進行延伸。又，亦可於延伸後進行染色。可視需要對PVA系膜實施膨潤處理、交聯處理、洗淨處理、乾燥處理等。例如，於染色之前將PVA系膜浸漬於水中進行水洗，藉此不僅可將PVA系膜表面之污漬或抗結塊劑洗淨，亦可使PVA系膜膨潤而防止染色不均等。
作為使用積層體而獲得之偏光元件之具體例，可列舉使用樹脂基材與積層於該樹脂基材之PVA系樹脂層(PVA系樹脂膜)之積層體、或者樹脂基材與塗佈形成於該樹脂基材之PVA系樹脂層之積層體而獲得之偏光元件。使用樹脂基材與塗佈形成於該樹脂基材之PVA系樹脂層之積層體而獲得之偏光元件例如可藉由如下而製作：將PVA系樹脂溶液塗佈於樹脂基材，使之乾燥而於樹脂基材上形成PVA系樹脂層，獲得樹脂基材與PVA系樹脂層之積層體；對該積層體進行延伸及染色而將PVA系樹脂層作為偏光元件。於本實施形態中，代表性而言，延伸包含使積層體浸漬於硼酸水溶液中後延伸。進而，延伸可進而包含視需要於在硼酸水溶液中延伸之前將積層體於高溫(例如95℃以上)下進行空中延伸。所獲得之樹脂基材/偏光元件之積層體可直接使用(即，亦可將樹脂基材作為偏光元件之保護層)，亦可將樹脂基材自樹脂基材/偏光元件之積層體剝離，並於該剝離面積層與目的相應之任意適當之保護層後使用。此種偏光元件之製造方法之詳細內容例如記載於日本專利特開2012-73580號公報。關於該公報，其整體之記載係作為參考而引用至本說明書中。
偏光元件之厚度較佳為15 μm以下，更佳為1 μm～12 μm，進而較佳為3 μm～10 μm，尤佳為3 μm～8 μm。若偏光元件之厚度為此種範圍，則可良好地抑制加熱時之捲曲及可獲得良好之加熱時之外觀耐久性。進而，若偏光元件之厚度為此種範圍，則可有助於液晶顯示裝置之薄型化。
偏光元件較佳為於波長380 nm～780 nm之任一波長下顯示出吸收二色性。偏光元件之單體透過率較佳為43.0%～46.0%，更佳為44.5%～46.0%。偏光元件之偏光度較佳為97.0%以上，更佳為99.0%以上，進而較佳為99.9%以上。
如上所述，可於第1偏光元件20之單側或兩側配置保護膜，亦可於第2偏光元件30之單側或兩側配置保護膜。即，偏光元件既可單獨作為液晶顯示裝置之構成要素，亦可以包含偏光元件與保護膜之偏光板之形式作為液晶顯示裝置之構成要素。進而，亦可將偏光元件與保護膜分開積層(即偏光元件及保護膜分別)作為液晶顯示裝置之構成要素。
保護膜係由任意適當之膜形成。作為成為該膜之主成分之材料之具體例，可列舉：三乙醯纖維素(TAC)等纖維素系樹脂或聚酯系、聚乙烯醇系、聚碳酸酯系、聚醯胺系、聚醯亞胺系、聚醚碸系、聚碸系、聚苯乙烯系、聚降𦯉烯系、聚烯烴系、(甲基)丙烯酸系、乙酸酯系等之透明樹脂等。又，亦可列舉：(甲基)丙烯酸系、胺基甲酸酯系、(甲基)丙烯酸胺基甲酸酯系、環氧系、聚矽氧系等之熱硬化型樹脂或紫外線硬化型樹脂等。此外，例如亦可列舉矽氧烷系聚合物等玻璃質系聚合物。又，亦可使用日本專利特開2001-343529號公報(WO01/37007)所記載之聚合物膜。作為該膜之材料，例如可使用含有側鏈具有經取代或未經取代之醯亞胺基之熱塑性樹脂及側鏈具有經取代或未經取代之苯基以及腈基之熱塑性樹脂之樹脂組合物，例如可列舉具有包含異丁烯與N-甲基馬來醯亞胺之交替共聚物及丙烯腈-苯乙烯共聚物之樹脂組合物。該聚合物膜例如可為上述樹脂組合物之擠出成形物。
保護膜之厚度較佳為20 μm～200 μm，更佳為30 μm～100 μm，進而較佳為35 μm～95 μm。
於在第1偏光元件20及/或第2偏光元件30之液晶單元10側配置有保護膜(內側保護膜)之情形時，該內側保護膜較佳為光學各向同性。於本說明書中，所謂「光學各向同性」，係指面內相位差Re(550)為0 nm～10 nm且厚度方向之相位差Rth(550)為-10 nm～+10 nm。
C.第1相位差層
如上所述，第1相位差層200之面內相位差Re(550)為100 nm～180 nm，較佳為110 nm～170 nm，進而較佳為120 nm～160 nm，尤佳為135 nm～155 nm。即，第1相位差層可作為所謂之λ/4板發揮功能。因此，第1相位差層具有將自偏光元件出射至視認側之直線偏光轉換成橢圓偏光或圓偏光之功能。如此一來，藉由將可作為λ/4板發揮功能之第1相位差層以如上述之特定之軸關係配置於較視認側偏光元件(第1偏光元件20)更靠視認側，即便於經由具有偏光作用之光學構件(例如偏光太陽眼鏡)視認顯示畫面之情形時，亦可實現優異之視認性。因此，本發明之液晶顯示裝置可較佳地於室外使用。
進而，如上所述，第1相位差層滿足Re(450)＜Re(550)＜Re(650)之關係。即，第1相位差層顯示出相位差值對應於測定光之波長而增大之逆分散之波長依存性。第1相位差層之Re(450)/Re(550)較佳為0.8以上且未達1.0，更佳為0.8～0.95。Re(550)/Re(650)較佳為0.8以上且未達1.0，更佳為0.8～0.97。
代表性而言，第1相位差層之折射率特性顯示出nx＞ny之關係，且具有遲相軸。如上所述，第1相位差層200之遲相軸與第1偏光元件20之吸收軸所成之角度較佳為35°～55°，更佳為38°～52°，進而較佳為40°～50°，尤佳為42°～48°，尤佳為44°～46°，最佳為約45°。若該角度為此種範圍，則藉由將第1相位差層設為λ/4板、及將第1相位差層配置於較第1偏光元件(視認側偏光元件)更靠視認側，即便於經由具有偏光作用之光學構件(例如偏光太陽眼鏡)視認顯示畫面之情形時，亦可實現優異之視認性。因此，本發明之液晶顯示裝置於室外亦可較佳地使用。
第1相位差層只要具有nx＞ny之關係，則會顯示出任意適當之折射率橢球。較佳為第1相位差層之折射率橢球顯示出nx＞nz＞ny之關係。第1相位差層之Nz係數較佳為0.2～0.8，更佳為0.3～0.7，進而較佳為0.4～0.6，尤佳為約0.5。藉由滿足此種關係，具有抑制經由具有偏光作用之光學構件(例如偏光太陽眼鏡)自傾斜方向觀察之情形時之著色的優勢。
第1相位差層包含光彈性係數之絕對值較佳為2×10-11
m2
/N以下、更佳為2.0×10-13
m2
/N～1.5×10-11
m2
/N、進而較佳為1.0×10-12
m2
/N～1.2×10-11
m2
/N之樹脂。若光彈性係數之絕對值為此種範圍，則於產生加熱時之收縮應力之情形時不易產生相位差變化。其結果，可良好地防止液晶顯示裝置之熱不均。
第1相位差層之厚度可以可作為λ/4板最佳地發揮功能之方式進行設定。換言之，厚度可以獲得所需之面內相位差之方式進行設定。具體而言，厚度較佳為1 μm～80 μm，更佳為10 μm～80 μm，進而較佳為10 μm～60 μm，尤佳為30 μm～50 μm。
第1相位差層係由可滿足如上述之特性之任意適當之樹脂形成。作為形成第1相位差層之樹脂，可列舉：聚碳酸酯樹脂、聚乙烯醇縮醛樹脂、環烯烴系樹脂、丙烯酸系樹脂、纖維素酯系樹脂等。較佳為聚碳酸酯樹脂。
作為上述聚碳酸酯樹脂，只要可獲得本發明之效果，則可使用任意適當之聚碳酸酯樹脂。較佳為聚碳酸酯樹脂包含源自茀系二羥基化合物之結構單元、源自異山梨酯系二羥基化合物之結構單元、及源自選自由脂環式二醇、脂環式二甲醇、二、三或聚乙二醇、以及伸烷基二醇或螺二醇所組成之群中之至少1種二羥基化合物之結構單元。較佳為聚碳酸酯樹脂包含源自茀系二羥基化合物之結構單元、源自異山梨酯系二羥基化合物之結構單元、源自脂環式二甲醇之結構單元以及/或者源自二、三或聚乙二醇之結構單元；進而較佳為包含源自茀系二羥基化合物之結構單元、源自異山梨酯系二羥基化合物之結構單元、及源自二、三或聚乙二醇之結構單元。聚碳酸酯樹脂亦可視需要包含其他源自二羥基化合物之結構單元。再者，可較佳地用於本發明之聚碳酸酯樹脂之詳細內容例如記載於日本專利特開2014-10291號公報、日本專利特開2014-26266號公報，且該記載係作為參考引用至本說明書中。
聚碳酸酯樹脂之玻璃轉移溫度較佳為110℃以上且250℃以下，更佳為120℃以上且230℃以下。若玻璃轉移溫度過低，則有耐熱性變差之傾向，於膜成形後可能會引起尺寸變化，又，存在會降低所獲得之液晶顯示裝置之圖像品質之情形。若玻璃轉移溫度過高，則存在膜成形時之成形穩定性變差之情形，又，存在會損害膜之透明性之情形。再者，玻璃轉移溫度係依據JIS K 7121(1987)而求出。
上述聚碳酸酯樹脂之分子量可由還原黏度表示。還原黏度係使用二氯甲烷作為溶劑，將聚碳酸酯濃度精準地製備成0.6 g/dL，並於溫度20.0℃±0.1℃下使用烏氏黏度管而測定。還原黏度之下限通常較佳為0.30 dL/g，更佳為0.35 dL/g以上。還原黏度之上限通常較佳為1.20 dL/g，更佳為1.00 dL/g，進而較佳為0.80 dL/g。若還原黏度小於上述下限值，則存在會產生成形品之機械強度減小之問題之情形。另一方面，若還原黏度大於上述上限值，則存在會產生成形時之流動性降低、生產性或成形性降低之問題之情形。
構成第1相位差層之相位差膜例如可藉由使由上述聚碳酸酯系樹脂形成之膜延伸而獲得。作為由聚碳酸酯系樹脂形成膜之方法，可採用任意適當之成形加工法。作為具體例，可列舉：壓縮成形法、轉移成形法、射出成形法、擠出成形法、吹塑成形法、粉末成形法、FRP(Fiber Reinforced Plastics，纖維強化塑膠)成形法、澆鑄塗佈法(例如流延法)、軋光成形法、熱壓法等。較佳為擠出成形法或澆鑄塗佈法。原因在於可提高所獲得之膜之平滑性，從而可獲得良好之光學均勻性。成形條件可根據所使用之樹脂之組成或種類、相位差膜所需之特性等而適當設定。
樹脂膜(未延伸膜)之厚度可根據所獲得之相位差膜之所需之厚度、所需之光學特性、下述延伸條件等而設定為任意適當之值。較佳為50 μm～300 μm。
上述延伸可採用任意適當之延伸方法、延伸條件(例如延伸溫度、延伸倍率、延伸方向)。具體而言，即可將自由端延伸、固定端延伸、自由端收縮、固定端收縮等各種延伸方法單獨地使用，亦可同時或者逐次使用。關於延伸方向，亦可於長度方向、寬度方向、厚度方向、傾斜方向等各種方向或維度進行。
藉由適當選擇上述延伸方法、延伸條件，可獲得具有上述所需之光學特性(例如折射率特性、面內相位差、Nz係數)之相位差膜。
於一實施形態中，相位差膜係藉由使樹脂膜單軸延伸或者固定端單軸延伸而製作。作為固定端單軸延伸之具體例，可列舉一面使樹脂膜沿長度方向移動，一面使之沿寬度方向(橫向)延伸之方法。延伸倍率較佳為1.1倍～3.5倍。
於另一實施形態中，相位差膜可藉由使長條狀之樹脂膜相對於長度方向沿特定角度之方向連續地傾斜延伸而製作。藉由採用傾斜延伸，可獲得相對於膜之長度方向具有特定角度之配向角(於特定角度之方向上具有遲相軸)之長條狀之延伸膜，例如於與偏光元件積層時可進行輥對輥，從而可使製造步驟簡略化。再者，上述特定角度於液晶顯示裝置中可為第1偏光元件之吸收軸與第1相位差層之遲相軸所成之角度。如上所述，該角度較佳為35°～55°，更佳為38°～52°，進而較佳為40°～50°，尤佳為42°～48°，尤佳為44°～46°，最佳為約45°。
作為用於傾斜延伸之延伸機，例如可列舉可於橫向及/或縱向上賦予左右不同速度之傳送力或者拉伸力或抽取力之拉幅機式延伸機。拉幅機式延伸機有橫向單軸延伸機、同步雙軸延伸機等，只要可使長條狀之樹脂膜連續地傾斜延伸，則可使用任意適當之延伸機。
於上述延伸機中，藉由分別適當地控制左右之速度，可獲得具有上述所需之面內相位差且於上述所需之方向上具有遲相軸之相位差膜(實質上為長條狀之相位差膜)。
作為傾斜延伸之方法，例如可列舉日本專利特開昭50-83482號公報、日本專利特開平2-113920號公報、日本專利特開平3-182701號公報、日本專利特開2000-9912號公報、日本專利特開2002-86554號公報、日本專利特開2002-22944號公報等所記載之方法。
可較佳地用於本發明之實施形態之相位差膜(即Nz係數未達1.0之相位差膜)可藉由經由例如丙烯酸系黏著劑將熱收縮膜貼合於樹脂膜之單面或兩面而形成積層體，並將該積層體供於如上述之延伸而製作。藉由調整熱收縮膜之構成(例如收縮力)及延伸條件(例如延伸溫度)，可獲得具有所需之Nz係數之相位差膜。
上述膜之延伸溫度可根據相位差膜所需之面內相位差值及厚度、所使用之樹脂之種類、所使用之膜之厚度、延伸倍率等而變化。具體而言，延伸溫度較佳為Tg－30℃～Tg＋30℃，進而較佳為Tg－15℃～Tg＋15℃，最佳為Tg－10℃～Tg＋10℃。藉由於此種溫度下延伸，於本發明中可獲得具有適當之特性之相位差膜。再者，Tg係膜之構成材料之玻璃轉移溫度。
亦可使用市售之膜作為聚碳酸酯系樹脂膜。作為市售品之具體例，可列舉：帝人公司製造之商品名「PURE-ACEWR-S」、「PURE-ACEWR-W」、「PURE-ACEWR-M」、日東電工公司製造之商品名「NRF」。可直接使用市售之膜，亦可根據目的對市售之膜進行2次加工(例如延伸處理、表面處理)後使用。
D.背光光源
背光光源300包含於背光單元(未圖示)中。背光單元除光源以外，代表性而言亦包含導光板、擴散片及稜鏡片等。如上所述，背光光源具有非連續之發光光譜。所謂「具有非連續之發光光譜」，係指於紅色(R)、綠色(G)及藍色(B)之各個波長區域存在明確之波峰且該各個波峰被明確地區別。圖2係模式性地表示非連續之發光光譜之一例之圖。如圖2所示，背光光源之發光光譜於較佳為430 nm～470 nm、更佳為440 nm～460 nm之波長區域(藍色之波長區域)具有波峰P1，於較佳為530 nm～570 nm、更佳為540 nm～560 nm之波長區域(綠色之波長區域)具有波峰P2，及於較佳為630 nm～670 nm、更佳為640 nm～660 nm之波長區域(紅色之波長區域)具有波峰P3。較佳為波峰P1之波長λ1、高度hP1及半值寬Δλ1、波峰P2之波長λ2、高度hP2及半值寬Δλ2、波峰P3之波長λ3、高度hP3及半值寬Δλ3、波峰P1與波峰P2之間之波谷之高度hB1、以及波峰P2與波峰P3之間之波谷之高度hB2滿足下述關係式(1)～(3)：
(λ2－λ1)/(Δλ2＋Δλ1)＞1・・・(1)
(λ3－λ2)/(Δλ3＋Δλ2)＞1・・・(2)
0.8≦{hP2－(hB2＋hB1)/2}/hP2≦1・・・(3)。
式(1)之(λ2－λ1)/(Δλ2＋Δλ1)更佳為1.01～2.00，進而較佳為1.10～1.50。式(2)之(λ3－λ2)/(Δλ3＋Δλ2)更佳為1.01～2.00，進而較佳為1.10～1.50。式(3)之{hP2－(hB2＋hB1)/2}更佳為0.85～1，進而較佳為0.9～1。式(1)意指藍色光與綠色光之關係係作為光源並未混色而獨立。式(2)意指綠色光與紅色光之關係係作為光源並未混色而獨立。式(3)意指波峰P1、P2及P3之間之谷底較低且藍色光、綠色光及紅色光之波峰被明確地區別。藉由規定式(1)～(3)，具有色再現性提高之優勢。藉由具有滿足式(1)～式(3)之發光光譜之背光光源300與上述第1相位差層200之協同效應，可實現色再現性優異且通過具有偏光作用之光學構件視認時之視認性優異及顏色不均得以抑制之液晶顯示裝置。例如，與具有圖3所示般之發光光譜之先前之背光光源(僅將發出紅色光、綠色光及藍色光之LED組合而成之白色光源)相比，可使色再現性、通過具有偏光作用之光學構件視認時之視認性及顏色不均全部顯著地改善。
背光光源成為可實現如上述之發光光譜之任意適當之構成。於一實施形態中，背光光源包含發出紅色之LED、發出綠色之LED及發出藍色之LED，且發出紅色之LED之螢光體係由四價錳離子活化。藉由使發出紅色之LED之螢光體活化，可縮小圖3所示之發光光譜中之紅色光與綠色光之重合，從而可實現圖2所示般之發光光譜。作為此種由四價錳離子活化之紅色螢光體之較佳之具體例，可列舉William M.Yen and Marvin J.Weber著 CRC出版之「INORGANIC PHOSPHORS」 p.212(SECTION4：PHOSPHOR DATA之4.10 Miscellaneous Oxides)所例示之Mn4 ＋
活化Mg氟鍺酸鹽螢光體(2.5MgO・MgF2
：Mn4 ＋
)及Journal of the Electrochemical Society：SOLID-STATE SCIENCE AND TECHNOLOGY、July 1973、p942所例示之M1 2
M2
F6
：Mn4 ＋
(M1
＝Li、Na、K、Rb、Cs；M2
＝Si、Ge、Sn、Ti、Zr)螢光體。使用此種紅色螢光體之背光光源例如記載於日本專利特開2015-52648號公報。又，包含發出紅色之LED、發出綠色之LED、及發出藍色之LED之一般構成之背光光源例如記載於日本專利特開2012-256014號公報。該等公報之記載係作為參考而引用至本說明書中。
於另一實施形態中，背光光源包含發出藍色之LED及包含量子點之波長轉換層。若為此種構成，則自LED發出之藍色光之一部分藉由波長轉換層而轉換成紅色光及綠色光，藍色光之另一部分直接以藍色光之形式出射。其結果，可實現白色光。進而，藉由適當地構成波長轉換層，可實現紅色光、綠色光及藍色光之波峰明確且各色光之重合較小之發光光譜(圖2所示般之發光光譜)。
代表性而言，波長轉換層包含基質及分散於該基質中之量子點。作為構成基質之材料(以下亦稱為基質材料)，可使用任意適當之材料。作為此種材料，可列舉樹脂、有機氧化物、無機氧化物。基質材料較佳為具有較低之透氧性及透濕性、具有較高之光穩定性及化學穩定性、具有特定之折射率、具有優異之透明性、及/或對量子點具有優異之分散性。若綜合地考慮到該等，則基質材料較佳為樹脂。樹脂既可為熱塑性樹脂，亦可為熱硬化性樹脂，亦可為活性能量線硬化性樹脂(例如電子束硬化型樹脂、紫外線硬化型樹脂、可見光線硬化型樹脂)。較佳為熱硬化性樹脂或紫外線硬化型樹脂，更佳為熱硬化性樹脂。樹脂可單獨使用，亦可組合(例如摻合、共聚合)後使用。
量子點可控制波長轉換層之波長轉換特性。具體而言，藉由將具有不同發光中心波長之量子點適當地組合使用，可形成實現具有所需之發光中心波長之光之波長轉換層。量子點之發光中心波長可藉由量子點之材料及/或組成、粒子尺寸、形狀等進行調整。作為量子點，例如已知有於600 nm～680 nm之範圍之波長頻帶中具有發光中心波長之量子點(以下稱為量子點A)、於500 nm～600 nm之範圍之波長頻帶中具有發光中心波長之量子點(以下稱為量子點B)、於400 nm～500 nm之波長頻帶中具有發光中心波長之量子點(以下稱為量子點C)。量子點A經激發光(於本發明中係來自背光光源之光)激發而發出紅色光，量子點B發出綠色光，量子點C發出藍色光。藉由將該等適當地組合，並使特定波長之光(來自背光光源之光)入射並通過波長轉換層時，可實現於所需之波長頻帶具有發光中心波長之光。
量子點可由任意適當之材料構成。量子點可由較佳為無機材料、更佳為無機導體材料或無機半導體材料構成。作為半導體材料，例如可列舉II-VI族、III-V族、IV-VI族、及IV族之半導體。作為具體例，可列舉Si、Ge、Sn、Se、Te、B、C(包含金剛石)、P、BN、BP、BAs、AlN、AlP、AlAs、AlSb、GaN、GaP、GaAs、GaSb、InN、InP、InAs、InSb、ZnO、ZnS、ZnSe、ZnTe、CdS、CdSe、CdSeZn、CdTe、HgS、HgSe、HgTe、BeS、BeSe、BeTe、MgS、MgSe、GeS、GeSe、GeTe、SnS、SnSe、SnTe、PbO、PbS、PbSe、PbTe、CuF、CuCl、CuBr、CuI、Si3
N4
、Ge3
N4
、Al2
O3
、(Al、Ga、In)2
(S、Se、Te)3
、Al2
CO。該等可單獨使用，亦可將2種以上組合使用。量子點亦可包含p型摻雜劑或n型摻雜劑。
量子點之尺寸可根據所需之發光波長而採用任意適當之尺寸。量子點之尺寸較佳為1 nm～10 nm，更佳為2 nm～8 nm。若量子點之尺寸為此種範圍，則綠色及紅色分別顯示出鮮明之發光，從而可實現高演色性。例如，綠色光可以量子點之尺寸為7 nm程度發光，紅色光可以3 nm程度發光。關於量子點之尺寸，於量子點為例如真球狀之情形時，係平均粒徑，於為除此以外之形狀之情形時，係沿該形狀中之最小軸之尺寸。再者，作為量子點之形狀，可根據目的而採用任意適當之形狀。作為具體例，可列舉真球狀、鱗片狀、板狀、橢圓球狀、不規則狀。
量子點相對於基質材料100重量份，可以較佳為1重量份～50重量份、更佳為2重量份～30重量份之比率調配。若量子點之調配量為此種範圍，則可實現RGB之全部色相平衡性優異之液晶顯示裝置。
量子點之詳細內容例如記載於日本專利特開2012-169271號公報、日本專利特開2015-102857號公報、日本專利特開2015-65158號公報、日本專利特表2013-544018號公報、日本專利特表2013-544018號公報、日本專利特表2010-533976號公報，且該等公報之記載係作為參考而引用至本說明書中。量子點亦可使用市售品。
波長轉換層之厚度較佳為1 μm～500 μm，更佳為100 μm～400 μm。若波長轉換層之厚度為此種範圍，則可使轉換效率及耐久性優異。
波長轉換層於背光單元中，係以膜之形式配置於LED(光源)之出射側。
E.第2相位差層
如上所述，第2相位差層400之折射率特性顯示出nz＞nx≧ny之關係。第2相位差層之厚度方向之相位差Rth(550)較佳為-260 nm～-10 nm，更佳為-230 nm～-15 nm，進而較佳為-215 nm～-20 nm。藉由設置具有此種光學特性之第2相位差層，經由具有偏光作用之光學構件(例如偏光太陽眼鏡)自傾斜方向觀察時之著色顯著地得到改善，結果，可獲得具有非常優異之視角特性之液晶顯示裝置。
於一實施形態中，第2相位差層之折射率顯示出nx＝ny之關係。於另一實施形態中，第2相位差層之折射率顯示出nx＞ny之關係。因此，存在第2相位差層具有遲相軸之情形。於此情形時，第2相位差層之遲相軸相對於第1偏光元件20之吸收軸實質上正交或平行。又，第2相位差層之面內相位差Re(550)較佳為10 nm～150 nm，更佳為10 nm～80 nm。
第2相位差層可由任意適當之材料形成。較佳為固定成垂直配向之液晶層。可垂直配向之液晶材料(液晶化合物)既可為液晶單體，亦可為液晶聚合物。作為該液晶化合物及該液晶層之形成方法之具體例，可列舉日本專利特開2002-333642號公報之[0020]～[0042]所記載之液晶化合物及形成方法。於此情形時，厚度較佳為0.1 μm～5 μm，更佳為0.2 μm～3 μm。
作為另一較佳之具體例，第2相位差層亦可為由日本專利特開2012-32784號公報所記載之反丁烯二酸二酯系樹脂形成之相位差膜。於此情形時，厚度較佳為5 μm～80 μm，更佳為10 μm～50 μm。
F.導電層
代表性而言，導電層(未圖示)透明(即導電層為透明導電層)。藉由於第1偏光元件20與液晶單元10之間形成導電層，液晶顯示裝置可作為所謂之內置觸控面板型輸入顯示裝置發揮功能。
導電層既可單獨地作為液晶顯示裝置之構成層，亦可以與基材之積層體(附基材之導電層)之形式供於液晶顯示裝置。於由導電層單獨構成之情形時，導電層可自形成有該導電層之基材轉印至液晶顯示裝置之特定之位置。
導電層可視需要進行圖案化。藉由圖案化，可形成導通部與絕緣部。結果，可形成電極。電極可作為感知與觸控面板之接觸之觸控感測器電極發揮功能。圖案之形狀較佳為作為觸控面板(例如靜電電容方式觸控面板)良好地動作之圖案。作為具體例，可列舉日本專利特表2011-511357號公報、日本專利特開2010-164938號公報、日本專利特開2008-310550號公報、日本專利特表2003-511799號公報、日本專利特表2010-541109號公報所記載之圖案。
導電層之總光線透過率較佳為80%以上，更佳為85%以上，進而較佳為90%以上。例如，若使用下述導電性奈米線，則可形成形成有開口部之透明導電層，從而可獲得透光率較高之透明導電層。
導電層之密度較佳為1.0 g/cm3
～10.5 g/cm3
，更佳為1.3 g/cm3
～3.0 g/cm3
。
導電層之表面電阻值較佳為0.1 Ω/□～1000 Ω/□，更佳為0.5 Ω/□～500 Ω/□，進而較佳為1 Ω/□～250 Ω/□。
作為導電層之代表例，可列舉包含金屬氧化物之導電層、包含導電性奈米線之導電層、包含金屬網之導電層。較佳為包含導電性奈米線之導電層或包含金屬網之導電層。原因在於其耐彎曲性優異，即便彎曲，導電性亦不易消失，因此可形成可良好地彎折之導電層。其結果，可將液晶顯示裝置構成為可彎曲。
包含金屬氧化物之導電層可藉由任意適當之成膜方法(例如真空蒸鍍法、濺鍍法、CVD(Chemical Vapor Deposition，化學氣相沈積)法、離子鍍敷法、噴霧法等)於任意適當之基材上使金屬氧化物膜成膜而形成。作為金屬氧化物，例如可列舉氧化銦、氧化錫、氧化鋅、銦-錫複合氧化物、錫-銻複合氧化物、鋅-鋁複合氧化物、銦-鋅複合氧化物。其中，較佳為銦-錫複合氧化物(ITO)。
包含導電性奈米線之導電層可將使導電性奈米線分散於溶劑中而成之分散液(導電性奈米線分散液)塗佈於任意適當之基材上後，使塗佈層乾燥而形成。作為導電性奈米線，只要可獲得本發明之效果，則可使用任意適當之導電性奈米線。所謂導電性奈米線，係指形狀為針狀或線狀且直徑為奈米尺寸之導電性物質。導電性奈米線既可為直線狀，亦可為曲線狀。如上所述，包含導電性奈米線之導電層之耐彎曲性優異。又，包含導電性奈米線之導電層藉由使導電性奈米線彼此形成隙間而成為網格狀，即便為少量之導電性奈米線，亦可形成良好之導電路徑，從而可獲得電阻較小之導電層。進而，藉由使導電性奈米線成為網格狀，可於網格之隙間形成開口部而獲得透光率較高之導電層。作為導電性奈米線，例如可列舉由金屬構成之金屬奈米線、包含奈米碳管之導電性奈米線等。
導電性奈米線之粗細度d與長度L之比(縱橫比：L/d)較佳為10～100,000，更佳為50～100,000，進而較佳為100～10,000。若使用縱橫比如此大之導電性奈米線，則導電性奈米線良好地交叉而可表現出高於少量之導電性奈米線之導電性。其結果，可獲得透光率較高之導電層。再者，於本說明書中，所謂「導電性奈米線之粗細度」，於導電性奈米線之剖面為圓狀之情形時，意指其直徑，於為橢圓狀之情形時，意指其短徑，於為多邊形之情形時，意指最長之對角線。導電性奈米線之粗細度及長度可藉由掃描型電子顯微鏡或穿透式電子顯微鏡進行確認。
導電性奈米線之粗細度較佳為未達500 nm，更佳為未達200 nm，進而較佳為1 nm～100 nm，尤佳為1 nm～50 nm。若為此種範圍，則可形成透光率較高之導電層。導電性奈米線之長度較佳為2.5 μm～1000 μm，更佳為10 μm～500 μm，進而較佳為20 μm～100 μm。若為此種範圍，則可獲得導電性較高之導電層。
作為構成導電性奈米線(金屬奈米線)之金屬，只要為導電性較高之金屬，則可使用任意適當之金屬。金屬奈米線較佳為由選自由金、鉑、銀及銅所組成之群中之1種以上之金屬構成。其中，就導電性之觀點而言，較佳為銀、銅或金，更佳為銀。又，亦可使用對上述金屬進行了鍍敷處理(例如鍍金處理)之材料。
作為奈米碳管，可使用任意適當之奈米碳管。例如，可使用所謂之多層奈米碳管、兩層奈米碳管、單層奈米碳管等。其中，就導電性較高之方面而言，可較佳地使用單層奈米碳管。
作為金屬網，只要可獲得本發明之效果，則可使用任意適當之金屬網。例如，可使用設置於膜基材上之金屬配線層之圖案形成為網格狀者。
導電性奈米線及金屬網之詳細內容例如記載於日本專利特開2014-113705號公報及日本專利特開2014-219667號公報。該公報之記載係作為參考而引用至本說明書中。
導電層之厚度較佳為0.01 μm～10 μm，更佳為0.05 μm～3 μm，進而較佳為0.1 μm～1 μm。若為此種範圍，則可獲得導電性及光透過性優異之導電層。再者，於導電層包含金屬氧化物之情形時，導電層之厚度較佳為0.01 μm～0.05 μm。
G.黏著劑層或接著劑層
關於構成本發明之液晶顯示裝置之各層及光學構件之積層，可使用任意適當之黏著劑層或接著劑層。代表性而言，黏著劑層係由丙烯酸系黏著劑形成。代表性而言，接著劑層係由聚乙烯醇系接著劑形成。
[實施例]
以下，藉由實施例對本發明具體地進行說明，但本發明並不受該等實施例限定。再者，各特性之測定方法如下所述。又，只要未特別明確記載，則實施例中之「份」及「%」為重量基準。
(1)厚度
使用針盤量規(PEACOCK公司製造，製品名「DG-205」，針盤量規支架(製品名「pds-2」))進行測定。
(2)相位差
自各相位差膜及液晶固化層切取50 mm×50 mm之樣品作為測定樣品，並使用Axometrics公司製造之Axoscan進行測定。測定波長為450 nm、550 nm，測定溫度為23℃。
又，使用Atago公司製造之阿貝折射率計測定平均折射率，並根據所獲得之相位差值算出折射率nx、ny、nz。
(3)吸水率
依據JIS K 7209所記載之「塑膠之吸水率及沸騰吸水率試驗方法」進行測定。試片之大小為邊長50 mm之正方形，藉由使試片於水溫25℃之水中浸漬24小時後，測定浸水前後之重量變化而求出。單位為%。
(4)背光光譜測定
使各實施例及各比較例中所獲得之液晶顯示裝置顯示白色圖像，並使用Topcon公司製造之SR-UL1R測定發光光譜。基於與所獲得之發光光譜相關之圖2所示之波長λ1、波長λ2、波長λ3、高度hP1、高度hP2、高度hP3、高度hB1、高度hB2、半值寬Δλ1、半值寬Δλ2、及半值寬Δλ3，求出以下之式(4)、(5)、及(6)所示之值。再者，使液晶顯示裝置顯示白色圖像時之顯示光之光譜與背光光源之發光光譜大致相等，因此將顯示白色圖像時之顯示光之光譜設為背光光源之發光光譜。
(λ2－λ1)/(Δλ2＋Δλ1)・・・(4)
(λ3－λ2)/(Δλ3＋Δλ2)・・・(5)
{hP2－(hB2＋hB1)/2}/hP2・・・(6)
(5)視認性評價
使各實施例及各比較例中所獲得之液晶顯示裝置顯示白色圖像，並基於以下之基準對通過偏光太陽眼鏡觀察圖像時之視認性進行評價。
良好・・・未產生著色及虹不均
不良・・・產生著色
＜實施例1＞
(構成第1相位差層之相位差膜A之製作)
使用包含2台具備攪拌翼及控制為100℃之回流冷凝器之縱型反應器的批量聚合裝置進行聚合。將9,9-[4-(2-羥基乙氧基)苯基]茀(BHEPF)、異山梨酯(ISB)、二乙二醇(DEG)、碳酸二苯酯(DPC)、及乙酸鎂4水合物按以莫耳比率計成為BHEPF/ISB/DEG/DPC/乙酸鎂＝0.348/0.490/0.162/ 1.005/1.00×10-5
之方式添加。於對反應器內充分地進行氮氣置換後(氧濃度0.0005～0.001 vol%)，利用熱介質進行加溫，並於內溫成為100℃之時點開始攪拌。於升溫開始40分鐘後使內溫達到220℃，並以保持該溫度之方式進行控制，同時開始減壓，於達到220℃後之90分鐘內設成13.3 kPa。將與聚合反應一起副生成之苯酚蒸氣導入至100℃之回流冷凝器中，使包含於苯酚蒸氣中之若干量之單體成分返回至反應器，將未冷凝之苯酚蒸氣導入至45℃之冷凝器並回收。
於將氮氣導入至第1反應器中並暫時恢復成大氣壓後，將第1反應器內之經低聚物化之反應液轉移至第2反應器。繼而，開始進行第2反應器內之升溫及減壓，於50分鐘內設成內溫240℃、壓力0.2 kPa。其後，進行聚合直至達到特定之攪拌動力。於達到特定動力之時點將氮氣導入至反應器中進行複壓，將反應液以線料之形態取出，並利用旋轉式切割機進行顆粒化，獲得BHEPF/ISB/DEG＝34.8/49.0/16.2[mol%]之共聚合組成之聚碳酸酯樹脂。該聚碳酸酯樹脂之還原黏度為0.430 dL/g，玻璃轉移溫度為128℃。於使所獲得之聚碳酸酯樹脂於80℃下真空乾燥5小時後，使用具備單軸擠出機(五十鈴化工機公司製造，螺桿直徑25 mm，汽缸設定溫度：220℃)、T字模(寬度900 mm，設定溫度：220℃)、冷卻輥(設定溫度：125℃)及捲取機之膜製膜裝置，製作厚度70 μm之聚碳酸酯樹脂膜。所獲得之聚碳酸酯樹脂膜之吸水率為1.2%。使所獲得之聚碳酸酯樹脂膜於133℃下單軸延伸成2.0倍，藉此獲得相位差膜A(厚度50 μm)。所獲得之相位差膜A之Re(550)為140 nm，Rth(550)為140 nm，Re(450)/Re(550)為0.89。
(偏光元件之製作)
準備A-PET(非晶-聚對苯二甲酸乙二酯)膜、(三菱樹脂(股)製造，商品名：NOVACLEAR SH046 200 μm)作為基材，並對表面實施電暈處理(58 W/m2
/min)。另一方面，準備添加有1 wt%之乙醯乙醯基改性PVA(日本合成化學工業(股)製造 商品名：GOHSEFIMER Z200(聚合度1200、皂化度99.0%以上、乙醯乙醯基改性度4.6%))之PVA(聚合度4200、皂化度99.2%)，以乾燥後之膜厚成為12 μm之方式塗佈於基材上，於60℃之環境下藉由熱風乾燥使之乾燥10分鐘，製作於基材上設置有PVA系樹脂層之積層體。
繼而，使該積層體首先於空氣中於130℃下沿MD方向(Machine direction，機械方向)延伸成2.0倍，而生成延伸積層體。繼而，進行藉由將延伸積層體於液溫30℃之硼酸不溶化水溶液中浸漬30秒，而使延伸積層體中所包含之PVA分子經配向之PVA層不溶化之步驟。該步驟中之不溶化用硼酸水溶液係製成為相對於水100重量份包含3重量份之硼酸含量者。藉由對經過不溶化步驟之該延伸積層體進行染色，而生成著色積層體。該著色積層體係藉由將延伸積層體浸漬於染色液中而使延伸積層體中所包含之PVA層吸附碘。染色液包含碘及碘化鉀，染色液之液溫設為30℃，將水作為溶劑，將碘濃度設為0.08～0.25重量%之範圍內，將碘化鉀濃度設為0.56～1.75重量%之範圍內。碘與碘化鉀之濃度之比設為1對7。作為染色條件，以構成偏光元件之PVA系樹脂層之單體透過率成為40.9%之方式設定碘濃度及浸漬時間。
繼而，進行藉由將著色積層體於30℃之交聯用硼酸水溶液中浸漬60秒，而對吸附有碘之PVA層之PVA分子彼此實施交聯處理之步驟。該交聯步驟所使用之交聯用硼酸水溶液係將硼酸含量相對於水100重量份設為3重量份，將碘化鉀含量相對於水100重量份設為3重量份。進而，進行藉由使所獲得之著色積層體於硼酸水溶液中，於延伸溫度70℃下沿與之前之空氣中之延伸相同之方向延伸成2.7倍而使最終之延伸倍率成為5.4倍之延伸，獲得包含供試用偏光元件之光學膜積層體。該延伸步驟中所使用之硼酸水溶液將硼酸含量相對於水100重量份設為4.0重量份，將碘化鉀含量相對於水100重量份設為5重量份。將所獲得之光學膜積層體自硼酸水溶液中取出，並利用相對於水100重量份包含4重量份之碘化鉀含量之水溶液將附著於PVA層之表面之硼酸洗淨。藉由利用60℃之熱風而進行之乾燥步驟使經洗淨之光學膜積層體乾燥，獲得積層於PET膜之厚度為5 μm之偏光元件。
(附相位差層之偏光板之製作)
於以如上方式製作之偏光元件中，針對積層於PET膜之厚度為5 μm之偏光元件，經由UV(Ultraviolet，紫外線)硬化型接著劑將上述相位差膜A以其遲相軸與偏光元件之吸收軸之角度實質上成為45°之方式貼附於與PET為相反側之面。進而，將PET膜自該積層體剝離，獲得附相位差層之偏光板。
(液晶顯示裝置之製作)
將液晶面板自具備IPS方式之液晶顯示裝置之智慧型手機(SONY公司製造 XperiaZ4：背光光源之發光光譜為非連續)之液晶顯示裝置中取出，將配置於液晶單元之視認側之偏光板去除，並將該液晶單元之玻璃面洗淨。接下來，經由丙烯酸系黏著劑(厚度20 μm)將上述附相位差板之偏光板之偏光元件側之面以偏光元件之吸收軸相對於該液晶單元之初始配向方向成為正交之方式(第1相位差層之遲相軸與液晶面板之長邊所成之角度成為45°，偏光元件之吸收軸與液晶面板之長邊所成之角度成為0°之方式)積層於上述液晶單元之視認側之表面，獲得液晶面板。將上述智慧型手機之背光單元安裝於積層有附相位差板之偏光板之上述液晶面板，作為本實施例之液晶顯示裝置。使該液晶顯示裝置顯示白色圖像，並於白色圖像狀態下對通過偏光太陽眼鏡之視認性進行評價。將評價結果示於表1。
＜實施例2＞
(構成第1相位差層之相位差膜B之製作)
使以與實施例1相同之方式獲得之聚碳酸酯樹脂(10 kg)溶解於二氯甲烷(73 kg)中，製備雙折射層形成材料。接下來，於收縮性膜(縱向單軸延伸聚丙烯膜，東京油墨(股)製造，商品名「Noblen」)上直接塗佈上述雙折射層形成材料，使其塗膜於乾燥溫度30℃下乾燥5分鐘，於80℃下乾燥5分鐘，形成收縮性膜/雙折射層之積層體。使用同步2軸延伸機使所獲得之積層體於延伸溫度155℃下沿MD方向以收縮倍率0.80延伸，沿TD方向(Transverse Direction，垂直方向)延伸成1.3倍，藉此，於收縮性膜上形成相位差膜B。接下來，將該相位差膜B自收縮性膜剝離。
以如上方式獲得相位差膜B(厚度60 μm)。所獲得之相位差膜B之Re(550)為140 nm，Rth(550)為70 nm，Re(450)/Re(550)為0.89。相位差膜B之遲相軸方向相對於長度方向為90°。
(附相位差層之偏光板及液晶顯示裝置之製作)
使用上述相位差膜B代替相位差膜A，除此以外，以與實施例1相同之方式製作附相位差層之偏光板，使用該附相位差層之偏光板，除此以外，以與實施例1相同之方式製作液晶顯示裝置。使該液晶顯示裝置顯示白色圖像，並於白色圖像狀態下對通過偏光太陽眼鏡之視認性進行評價。將評價結果示於表1。
＜實施例3＞
(構成第2相位差層之液晶固化層之製作)
將下述化學式(I)(式中之數字65及35表示單體單元之莫耳%，為便於說明而以嵌段聚合物表示：重量平均分子量5000)所示之側鏈型液晶聚合物20重量份、顯示向列型液晶相之聚合性液晶(BASF公司製造：商品名Paliocolor LC242)80重量份及光聚合起始劑(Ciba Specialty Chemicals公司製造：商品名Irgacure 907)5重量份溶解於環戊酮200重量份中而製備液晶塗佈液。接下來，藉由棒式塗佈機將該塗佈液塗佈於基材膜(降𦯉烯系樹脂膜：日本ZEON(股)製造，商品名「ZEONEX」)後，於80℃下加熱乾燥4分鐘，藉此使液晶配向。對該液晶層照射紫外線而使液晶層硬化，藉此於基材膜上形成成為第2相位差層之液晶固化層(厚度：1.10 μm)。該液晶固化層之Re(550)為0 nm，Rth(550)為-100 nm，顯示出nz＞nx＝ny之折射率特性。
[化1]
(附相位差層之偏光板之製作)
針對以與實施例1相同之方式獲得之PET膜與偏光元件之積層體，經由UV硬化型接著劑將上述液晶固化層以將基材膜去除時之基材膜之剝離方向與偏光元件之吸收軸實質上成為平行之方式貼附於與PET膜為相反側之面。進而，將上述基材膜去除，並經由UV硬化型接著劑將以與實施例1相同之方式製作之相位差膜A以其遲相軸與偏光元件之吸收軸之角度實質上成為45°之方式貼附於液晶固化層之與偏光元件相反之側。進而，將PET膜自該積層體剝離後，經由UV硬化型接著劑貼合丙烯酸系保護膜，或者視需要貼合相位差層，而製作附相位差層之偏光板。
(液晶顯示裝置之製作)
使用上述附相位差層之偏光板、及使用具備不同之背光光源之智慧型手機，除此以外，以與實施例1相同之方式製作液晶顯示裝置。使該液晶顯示裝置顯示白色圖像，並於白色圖像狀態下對通過偏光太陽眼鏡之視認性進行評價。將評價結果示於表1。
＜實施例4＞
(構成第1相位差層之相位差膜C之製作)
將以與實施例1相同之方式獲得之聚碳酸酯樹脂於80℃下真空乾燥5小時後，使用具備單軸擠出機(五十鈴化工機公司製造，螺桿直徑25 mm，汽缸設定溫度：220℃)、T字模(寬度900 mm，設定溫度：220℃)、冷卻輥(設定溫度：125℃)及捲取機之膜製膜裝置，製作厚度130 μm之聚碳酸酯樹脂膜。所獲得之聚碳酸酯樹脂膜之吸水率為1.2%。
利用依據日本專利特開2014-194483號公報之實施例1之方法使上述聚碳酸酯樹脂膜傾斜延伸，獲得相位差膜C。
相位差膜C之具體之製作順序如下所述：將聚碳酸酯樹脂膜(厚度130 μm，寬度765 mm)於延伸裝置之預熱區域預熱至142℃。於預熱區域，左右之夾具之夾具間距為125 mm。繼而，將膜放入至第1傾斜延伸區域C1，同時開始增大右側夾具之夾具間距，於第1傾斜延伸區域C1自125 mm增大至177.5 mm。夾具間距變化率為1.42。於第1傾斜延伸區域C1，關於左側夾具之夾具間距，開始減少夾具間距，於第1傾斜延伸區域C1自125 mm減少至90 mm。夾具間距變化率為0.72。進而，將膜放入至第2傾斜延伸區域C2，同時開始增大左側夾具之夾具間距，於第2傾斜延伸區域C2自90 mm增大至177.5 mm。另一方面，右側夾具之夾具間距於第2傾斜延伸區域C2維持為177.5 mm。又，與上述傾斜延伸同時地亦於寬度方向上進行1.9倍之延伸。再者，上述傾斜延伸係於135℃下進行。繼而，於收縮區域進行MD收縮處理。具體而言，使左側夾具及右側夾具之夾具間距均自177.5 mm減少至165 mm。MD收縮處理中之收縮率為7.0%。
以如上方式獲得相位差膜C(厚度40 μm)。所獲得之相位差膜C之Re(550)為140 nm，Rth(550)為168 nm，Re(450)/Re(550)為0.89。相位差膜C之遲相軸方向相對於長度方向為45°。
(附相位差層之偏光板及液晶顯示裝置之製作)
使用上述相位差膜C代替相位差膜A，除此以外，以與實施例1相同之方式製作附相位差層之偏光板，使用該附相位差層之偏光板，除此以外，以與實施例1相同之方式製作液晶顯示裝置。使該液晶顯示裝置顯示白色圖像，並於白色圖像狀態下對通過偏光太陽眼鏡之視認性進行評價。將評價結果示於表1。
＜比較例1＞
(構成第1相位差層之相位差膜D之製作)
經由丙烯酸系黏著劑層(厚度15 μm)將雙軸延伸聚丙烯膜(Toray製造，商品名「Torayfan」(厚度60 μm))貼合於市售之ARTON膜(JSR公司製造，厚度70 μm)之兩側。其後，利用輥延伸機保持膜之長度方向並於147℃之空氣循環式恆溫烘箱內使之延伸至1.45倍而獲得相位差膜D。所獲得之相位差膜D之Re(550)為140 nm，Rth(550)為70 nm，Re(450)/Re(550)為1.00。
(附相位差層之偏光板及液晶顯示裝置之製作)
使用上述相位差膜D代替相位差膜A，除此以外，以與實施例1相同之方式製作附相位差層之偏光板，使用該附相位差層之偏光板，除此以外，以與實施例1相同之方式製作液晶顯示裝置。使該液晶顯示裝置顯示白色圖像，並於白色圖像狀態下對通過偏光太陽眼鏡之視認性進行評價。將評價結果示於表1。
＜比較例2＞
(構成第1相位差層之相位差膜E之製作)
針對市售之ARTON膜(JSR公司製造，厚度100 μm)，利用輥延伸機保持膜之長度方向，並於147℃之空氣循環式恆溫烘箱內使之延伸至1.8倍而獲得相位差膜E。所獲得之相位差膜E之Re(550)為140 nm，Rth(550)為140 nm，Re(450)/Re(550)為1.00。
(附相位差層之偏光板之製作)
使用上述相位差膜E，除此以外，以與實施例1相同之方式製作附相位差層之偏光板。
(液晶顯示裝置之製作)
自具備IPS方式之液晶顯示裝置之智慧型手機(Apple公司製造iphone5：背光光源之發光光譜為連續)之液晶顯示裝置中取出液晶面板，將配置於液晶單元之視認側之偏光板去除，並將該液晶單元之玻璃面洗淨。接下來，經由丙烯酸系黏著劑(厚度20 μm)將上述附相位差板之偏光板之偏光元件側之面以偏光元件之吸收軸相對於該液晶單元之初始配向方向成為正交之方式積層於上述液晶單元之視認側之表面而獲得液晶面板。將積層有附相位差板之偏光板之上述液晶面板安裝於上述智慧型手機而作為本實施例之液晶顯示裝置。使該液晶顯示裝置顯示白色圖像，並於白色圖像狀態下對通過偏光太陽眼鏡之視認性進行評價。將評價結果示於表1。
＜比較例3＞
(構成第1相位差層之相位差膜F之製作)
使用作為碳酸酯前驅物質之碳醯氯、作為芳香族二價苯酚成分之(A)2,2-雙(4-羥基苯基)丙烷及(B)1,1-雙(4-羥基苯基)-3,3,5-三甲基環己烷，並依據常規方法獲得(A)：(B)之重量比為4：6並且包含重量平均分子量(Mw)為60,000之下述化學式(II)及(III)之重複單元之聚碳酸酯系樹脂[數量平均分子量(Mn)＝33,000，Mw/Mn＝1.78]。將上述聚碳酸酯系樹脂70重量份及重量平均分子量(Mw)為1,300之苯乙烯系樹脂[數量平均分子量(Mn)＝716，Mw/Mn＝1.78](三洋化成製造之HIMER SB75)30重量份添加至二氯甲烷300重量份中，並於室溫下攪拌混合4小時而獲得透明之溶液。將該溶液澆鑄於玻璃板上，並於室溫下放置15分鐘後自玻璃板剝離，於80℃之烘箱中乾燥10分鐘，於120℃下乾燥20分鐘，獲得厚度40 μm、玻璃轉移溫度(Tg)為140℃之高分子膜。所獲得之高分子膜之波長590 nm下之透光率為93%。又，上述高分子膜之面內相位差值：Re(590)為5.0 nm，厚度方向之相位差值：Rth(590)為12.0 nm。平均折射率為1.576。
使所獲得之高分子膜於150℃之空氣循環式恆溫烘箱內單軸延伸至1.5倍而獲得相位差膜F。所獲得之相位差膜F之Re(550)為140 nm、Rth(550)為140 nm、Re(450)/Re(550)為1.06。
[化2]
(附相位差層之偏光板及液晶顯示裝置之製作)
使用上述相位差膜F代替相位差膜A，除此以外，以與實施例1相同之方式製作附相位差層之偏光板，使用該附相位差層之偏光板，除此以外，以與實施例1相同之方式製作液晶顯示裝置。使該液晶顯示裝置顯示白色圖像，並於白色圖像狀態下對通過偏光太陽眼鏡之視認性進行評價。將評價結果示於表1。
[表1] 第1相位差層 第2相位差層 背光光源 視認性
面內相位差Re550(nm) 波長分散特性(Re450/Re550) Nz係數 厚度方向相位差Rth550(nm) 光譜 (λ2－λ1)/(△λ2＋△λ1) (λ3－λ2)/(△λ3＋△λ2) {hP2－(hB2＋hB1)/2}/hP2
實施例1 140 0.89 1.0 - 非連續 1.38 1.63 0.90 良好
實施例2 140 0.89 0.5 - 非連續 1.38 1.63 0.90 良好
實施例3 140 0.89 1.0 -100 非連續 1.22 1.71 0.85 良好
實施例4 140 0.89 1.2 - 非連續 1.38 1.63 0.90 良好
比較例1 140 1.00 0.5 - 非連續 1.38 1.63 0.90 不良
比較例2 140 1.00 1.0 - 連續 0.88 0.44 0.55 不良
比較例3 140 1.06 1.0 - 非連續 1.38 1.63 0.90 不良
[產業上之可利用性]
本發明之液晶顯示裝置可較佳地用於可攜式資訊終端(PDA)、行動電話、鐘錶、數相位機、可攜式遊戲機等行動裝置、電腦監視器、筆記型電腦、影印機等辦公自動化設備、攝錄影機、液晶電視、微波爐等家用電氣設備、後部監視器、汽車導航系統用監視器、汽車音響等車載用設備、商業店鋪用資訊用監視器等展示設備、監視用監視器等警戒設備、護理用監視器、醫療用監視器等護理、醫療機器等各種用途。Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments.
(Definition of terms and symbols)
The definitions of terms and symbols in this manual are as follows.
(1) Refractive index (nx, ny, nz)
"Nx" refers to the refractive index in the direction in which the in-plane refractive index becomes the largest (i.e., the direction of the late axis), and "ny" refers to the refractive index in the direction orthogonal to the late axis (i.e., the direction of the advancing axis) in the plane, "Nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
"Re(λ)" measures the in-plane retardation of the resulting film using light with a wavelength of λnm at 23°C. For example, "Re(450)" uses light with a wavelength of 450 nm at 23°C to measure the in-plane retardation of the resulting film. When the thickness of the film is d (nm), Re (λ) is obtained by the formula: Re=(nx-ny)×d.
(3) Phase difference in thickness direction (Rth)
"Rth(λ)" is measured using light with a wavelength of 550 nm at 23°C in the thickness direction of the film obtained. For example, "Rth(450)" uses light with a wavelength of 450 nm at 23°C to measure the retardation in the thickness direction of the resulting film. When the thickness of the film is d (nm), Rth(λ) is obtained by the formula: Rth=(nx-nz)×d.
(4) Nz coefficient
The Nz coefficient is obtained by Nz=Rth/Re.
(5) nx=ny, nx=nz, ny=nz
The so-called nx=ny includes not only the case where nx and ny are exactly the same, but also the case where nx and ny are substantially the same. The same applies to the relationship between nx=nz and ny=nz.
(6) Substantially orthogonal or parallel
The expressions "substantially orthogonal" and "substantially orthogonal" include the case where the angle formed by the two directions is 90°±10°, preferably 90°±7°, and more preferably 90°±5°. The expressions "substantially parallel" and "substantially parallel" include the case where the angle formed by the two directions is 0°±10°, preferably 0°±7°, and more preferably 0°±5°. Furthermore, when it is simply referred to as "orthogonal" or "parallel", it may also include a state of being substantially orthogonal or substantially parallel.
(7) Angle
In this specification, when referring to an angle, unless specifically stated otherwise, the angle includes the angle in both the clockwise and counterclockwise directions.
A. The overall structure of the liquid crystal display device
Fig. 1 is a schematic cross-sectional view of a liquid crystal display device according to an embodiment of the present invention. In the drawings, in order to facilitate observation, the ratio of the thickness of each layer and each optical member is different from the actual product. The liquid crystal display device 500 of the present embodiment includes a liquid crystal panel 100, a retardation layer 200 arranged on the visible side of the liquid crystal panel 100, and a backlight light source 300 that illuminates the liquid crystal panel 100 from the back side. In the example shown in the figure, another retardation layer 400 may be further disposed between the liquid crystal panel 100 and the retardation layer 200. Depending on the purpose, configuration, required characteristics, etc., the other retardation layer may be omitted. In addition, for convenience of description, the retardation layer 200 may be referred to as a first retardation layer, and the other retardation layer 400 may be referred to as a second retardation layer. In the embodiment of the present invention, the in-plane retardation Re(550) of the first retardation layer 200 is 100 nm to 180 nm, preferably 110 nm to 170 nm, and more preferably 120 nm to 160 nm, especially Preferably, it is 135 nm to 155 nm. Furthermore, the first retardation layer 200 satisfies the relationship of Re(450)<Re(550)<Re(650). In addition, in the embodiment of the present invention, the backlight light source 300 has a non-continuous emission spectrum.
The liquid crystal panel 100 includes a liquid crystal cell 10, a first polarizing element 20 arranged on the visible side of the liquid crystal cell 10, and a second polarizing element 30 arranged on the back side of the liquid crystal cell 10. The absorption axis of the first polarizing element 20 is substantially perpendicular or parallel to the long side of the liquid crystal panel 100 (liquid crystal cell 10). In addition, the absorption axis of the second polarizing element 30 is also substantially orthogonal or parallel to the long side of the liquid crystal panel 100 (liquid crystal cell 10). Furthermore, the long side of the liquid crystal panel can be either the left-right direction of the display screen or the up-down direction. The absorption axis of the first polarizing element 20 and the absorption axis of the second polarizing element 30 are substantially orthogonal. A protective film (not shown) may be disposed on one side or both sides of the first polarizing element 20. Similarly, a protective film (not shown) may be disposed on one side or both sides of the second polarizing element 30.
The angle formed by the slow axis of the first retardation layer 200 and the long side of the liquid crystal panel 100 is 35°-55°, preferably 38°-52°, more preferably 40°-50°, and more preferably 42°～48°, particularly preferably 44°～46°, particularly preferably about 45°. Therefore, the angle formed by the slow axis of the first retardation layer 200 and the absorption axis of the first polarizer 20 is preferably 35° to 55°, more preferably 38° to 52°, and still more preferably 40° to 50°, particularly preferably 42°～48°, particularly preferably 44°～46°, most preferably about 45°.
In one embodiment, a conductive layer (not shown) may be provided between the first polarizing element 20 and the liquid crystal cell 10. By providing such a conductive layer, the liquid crystal display device can function as a so-called built-in touch panel type input display device in which a touch sensor is integrated between the display unit (liquid crystal unit) and the polarizing element.
Optionally, any appropriate optical compensation layer (another retardation layer) may be disposed between the first polarizing element 20 and the liquid crystal cell 10 and/or between the second polarizing element 30 and the liquid crystal cell 10 as needed. The arrangement number, combination, arrangement position, arrangement sequence, optical characteristics (such as refractive index ellipsoid, in-plane retardation, thickness direction retardation, Nz coefficient), mechanical characteristics of such optical compensation layers can be based on the purpose, and the liquid crystal display device The composition and required characteristics are appropriately set.
Hereinafter, the constituent elements (optical film, optical member) of the liquid crystal display device will be described.
B. LCD panel
B-1. Liquid crystal cell
The liquid crystal cell 10 has a pair of substrates 11 and 12, and a liquid crystal layer 13 as a display medium sandwiched between the substrates. In a general configuration, a color filter and a black matrix are provided on one substrate 11, and a switching element for controlling the electro-optical characteristics of liquid crystal is provided on the other substrate 12, a scanning line for providing gate signals to the switching element, and providing Source signal signal line, pixel electrode and counter electrode. The interval (cell gap) between the above-mentioned substrates 11 and 12 can be controlled by a spacer or the like. For example, an alignment film containing polyimide or the like may be provided on the side of the substrates 11 and 12 that is in contact with the liquid crystal layer 13.
In one embodiment, the liquid crystal layer 13 includes liquid crystal molecules that are aligned along the plane in the absence of an electric field. Typically, the refractive index ellipsoid of such a liquid crystal layer (the result is a liquid crystal cell) shows a relationship of nx>ny=nz. As a representative example of a driving mode using such a liquid crystal layer exhibiting a three-dimensional refractive index, a lateral electric field effect (IPS) mode, a fringe field switching (FFS) mode, etc. can be cited. The IPS mode includes Super·In plane switching (S-IPS) mode or Advanced·Super·In plane switching (AS-IPS) mode using V-shaped electrodes or zigzag electrodes. The FFS mode includes Advanced·Fringe-Field Switching (A-FFS) mode or Ultra Fringe-Field Switching (U-FFS) mode using V-shaped electrodes or zigzag electrodes. In the driving mode (such as IPS mode, FFS mode) of liquid crystal molecules aligned along the surface in the absence of an electric field, there is no tilt inversion, and the tilt viewing angle is wide, so it can be viewed from the tilt direction The advantage of the excellent visibility of Time.
In another embodiment, the liquid crystal layer 13 includes liquid crystal molecules that are aligned in a vertical arrangement in the absence of an electric field. As a driving mode used for liquid crystal molecules aligned in a vertical arrangement in the absence of an electric field, for example, a vertical alignment (VA) mode can be cited. The VA mode includes the multi-domain VA (MVA) mode. In the driving mode (such as VA mode) that uses liquid crystal molecules aligned vertically in the absence of an electric field, since the transmissivity of the halftone in the oblique direction is higher than the transmissivity of the halftone in the front direction, it has self-contained The halftones viewed obliquely have the advantage of being brighter and less black.
B-2. Polarizing element
As the first polarizing element 20 and the second polarizing element 30, any appropriate polarizing element can be used. The material, thickness, optical characteristics, etc. of the first polarizing element 20 and the second polarizing element 30 may be the same or different. Hereinafter, the first polarizing element 20 and the second polarizing element 30 may be collectively referred to as a polarizing element.
The resin film forming the polarizing element may be a single-layer resin film or a laminate of two or more layers.
Specific examples of polarizing elements composed of a single-layer resin film include polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, ethylene-vinyl acetate copolymer-based partially saponified films, etc., which are highly hydrophilic. The molecular film is formed by dyeing and stretching using dichroic substances such as iodine or dichroic dyes, and polyene-based alignment films such as dehydrated PVA or dehydrated polyvinyl chloride. In terms of excellent optical characteristics, it is preferable to use a polarizing element obtained by dyeing a PVA-based film with iodine and uniaxially stretching it.
The dyeing by the above-mentioned iodine can be performed by immersing the PVA-based film in an iodine aqueous solution, for example. The stretching magnification of the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching can be done after dyeing, or it can be stretched while dyeing. Also, dyeing may be performed after stretching. The PVA-based film may be subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment, etc. as needed. For example, by immersing the PVA-based film in water for washing before dyeing, not only the stains or anti-caking agent on the surface of the PVA-based film can be washed away, but also the PVA-based film can be swollen to prevent uneven dyeing.
As a specific example of a polarizing element obtained by using a laminate, a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a coating formed on the resin substrate A polarizing element obtained by a laminate of PVA-based resin layers of the resin base material. A polarizing element obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying it. A PVA-based resin layer is formed on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; the laminate is extended and dyed to use the PVA-based resin layer as a polarizing element. In this embodiment, the stretching typically includes stretching after immersing the laminate in an aqueous boric acid solution. Furthermore, stretching may further include performing aerial stretching of the laminate at a high temperature (for example, 95° C. or higher) before stretching in an aqueous boric acid solution as necessary. The obtained resin substrate/polarizing element laminate can be used directly (that is, the resin substrate can also be used as a protective layer for the polarizing element), or the resin substrate can be peeled from the resin substrate/polarizing element laminate. And use it after peeling off any suitable protective layer corresponding to the purpose of the area layer. The details of the manufacturing method of such a polarizing element are described in, for example, Japanese Patent Laid-Open No. 2012-73580. Regarding this gazette, the entire description is cited in this specification as a reference.
The thickness of the polarizing element is preferably 15 μm or less, more preferably 1 μm-12 μm, still more preferably 3 μm-10 μm, and particularly preferably 3 μm-8 μm. If the thickness of the polarizing element is in this range, curling during heating can be well suppressed and good appearance durability during heating can be obtained. Furthermore, if the thickness of the polarizing element is in this range, it can contribute to the thinning of the liquid crystal display device.
The polarizing element preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The monomer transmittance of the polarizing element is preferably 43.0%-46.0%, more preferably 44.5%-46.0%. The degree of polarization of the polarizing element is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.
As described above, a protective film may be disposed on one side or both sides of the first polarizing element 20, and a protective film may be disposed on one side or both sides of the second polarizing element 30. That is, the polarizing element may be used as a constituent element of the liquid crystal display device alone, or the form of a polarizing plate including the polarizing element and a protective film may be used as the constituent element of the liquid crystal display device. Furthermore, the polarizing element and the protective film may be laminated separately (that is, the polarizing element and the protective film are separated) as a constituent element of the liquid crystal display device.
The protective film is formed of any suitable film. Specific examples of the material that becomes the main component of the film include: cellulose resins such as triacetyl cellulose (TAC) or polyester, polyvinyl alcohol, polycarbonate, polyamide, polyamide, etc. Transparent resins such as imine, polyether ether, polystyrene, polystyrene, polynorene, polyolefin, (meth)acrylic, acetate, etc. In addition, thermosetting resins such as (meth)acrylic, urethane, (meth)acrylate urethane, epoxy, silicone, etc., or UV-curable resins can also be cited Resin etc. In addition, for example, glassy polymers such as silicone polymers can also be cited. In addition, the polymer film described in Japanese Patent Laid-Open No. 2001-343529 (WO01/37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted amide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used For example, a resin composition having an alternating copolymer containing isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be cited. The polymer film may be, for example, an extrusion molded product of the above-mentioned resin composition.
The thickness of the protective film is preferably 20 μm to 200 μm, more preferably 30 μm to 100 μm, and still more preferably 35 μm to 95 μm.
When a protective film (inner protective film) is disposed on the liquid crystal cell 10 side of the first polarizing element 20 and/or the second polarizing element 30, the inner protective film is preferably optically isotropic. In this specification, "optical isotropy" means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm.
C. The first retardation layer
As described above, the in-plane retardation Re(550) of the first retardation layer 200 is 100 nm to 180 nm, preferably 110 nm to 170 nm, more preferably 120 nm to 160 nm, and particularly preferably 135 nm ~155 nm. That is, the first retardation layer can function as a so-called λ/4 plate. Therefore, the first retardation layer has a function of converting the linearly polarized light emitted from the polarizing element to the visible side into elliptical polarized light or circularly polarized light. In this way, by arranging the first retardation layer that can function as a λ/4 plate in a specific axial relationship as described above on the viewing side of the viewing side polarizing element (first polarizing element 20), When viewing the display screen through an optical member with a polarizing effect (such as polarized sunglasses), excellent visibility can also be achieved. Therefore, the liquid crystal display device of the present invention can be preferably used outdoors.
Furthermore, as described above, the first retardation layer satisfies the relationship of Re(450)<Re(550)<Re(650). That is, the first retardation layer shows the wavelength dependence of the inverse dispersion whose retardation value increases in accordance with the wavelength of the measurement light. The Re(450)/Re(550) of the first retardation layer is preferably 0.8 or more and less than 1.0, more preferably 0.8 to 0.95. Re(550)/Re(650) is preferably 0.8 or more and less than 1.0, more preferably 0.8 to 0.97.
Typically, the refractive index characteristic of the first retardation layer shows a relationship of nx>ny and has a slow axis. As described above, the angle formed by the slow axis of the first retardation layer 200 and the absorption axis of the first polarizing element 20 is preferably 35° to 55°, more preferably 38° to 52°, and still more preferably 40 °～50°, particularly preferably 42°～48°, particularly preferably 44°～46°, most preferably about 45°. If the angle is in this range, by setting the first retardation layer as a λ/4 plate and arranging the first retardation layer on the viewing side more than the first polarizing element (viewing side polarizing element), even Excellent visibility can also be achieved when viewing the display screen through an optical member with a polarizing effect (such as polarized sunglasses). Therefore, the liquid crystal display device of the present invention can also be preferably used outdoors.
As long as the first retardation layer has a relationship of nx>ny, any appropriate refractive index ellipsoid will be shown. Preferably, the refractive index ellipsoid of the first retardation layer shows a relationship of nx>nz>ny. The Nz coefficient of the first retardation layer is preferably 0.2 to 0.8, more preferably 0.3 to 0.7, still more preferably 0.4 to 0.6, and particularly preferably about 0.5. By satisfying this relationship, there is an advantage of suppressing coloration when viewed from an oblique direction through an optical member having a polarizing effect (for example, polarized sunglasses).
The absolute value of the first retardation layer including the photoelastic coefficient is preferably 2×10-11
m2
/N or less, preferably 2.0×10-13
m2
/N～1.5×10-11
m2
/N, more preferably 1.0×10-12
m2
/N～1.2×10-11
m2
/N of resin. If the absolute value of the photoelastic coefficient is in this range, the phase difference will not change easily when the shrinkage stress during heating occurs. As a result, heat unevenness in the liquid crystal display device can be prevented favorably.
The thickness of the first retardation layer can be set in such a way that the λ/4 plate functions optimally. In other words, the thickness can be set in such a way that the required in-plane phase difference can be obtained. Specifically, the thickness is preferably 1 μm to 80 μm, more preferably 10 μm to 80 μm, still more preferably 10 μm to 60 μm, and particularly preferably 30 μm to 50 μm.
The first retardation layer is formed of any appropriate resin that can satisfy the above-mentioned characteristics. Examples of the resin forming the first retardation layer include polycarbonate resins, polyvinyl acetal resins, cycloolefin resins, acrylic resins, and cellulose ester resins. Preferably it is a polycarbonate resin.
As the above-mentioned polycarbonate resin, any appropriate polycarbonate resin can be used as long as the effects of the present invention can be obtained. Preferably, the polycarbonate resin contains a structural unit derived from a stilbene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from alicyclic diol, alicyclic dimethanol, two The structural unit of at least one dihydroxy compound in the group consisting of, tri- or polyethylene glycol, and alkylene glycol or spirodiol. Preferably, the polycarbonate resin contains a structural unit derived from a stilbene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from alicyclic dimethanol, and/or a structural unit derived from two, three Or a structural unit of polyethylene glycol; more preferably, it contains a structural unit derived from a stilbene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di-, tri-, or polyethylene glycol Structural units. The polycarbonate resin may optionally contain other structural units derived from dihydroxy compounds. Furthermore, the details of the polycarbonate resin that can be preferably used in the present invention are described in, for example, Japanese Patent Laid-Open No. 2014-10291 and Japanese Patent Laid-Open No. 2014-26266, and the description is incorporated by reference. In this manual.
The glass transition temperature of the polycarbonate resin is preferably 110°C or higher and 250°C or lower, more preferably 120°C or higher and 230°C or lower. If the glass transition temperature is too low, the heat resistance tends to be deteriorated, which may cause dimensional changes after the film is formed, and may also reduce the image quality of the obtained liquid crystal display device. If the glass transition temperature is too high, the forming stability during film forming may deteriorate, and the transparency of the film may be impaired. In addition, the glass transition temperature is determined based on JIS K 7121 (1987).
The molecular weight of the above polycarbonate resin can be represented by reduced viscosity. The reduced viscosity is measured by using dichloromethane as the solvent to accurately prepare the polycarbonate concentration to 0.6 g/dL and using a Ubbelohde viscosity tube at a temperature of 20.0°C±0.1°C. The lower limit of the reduction viscosity is usually preferably 0.30 dL/g, more preferably 0.35 dL/g or more. The upper limit of the reduction viscosity is generally preferably 1.20 dL/g, more preferably 1.00 dL/g, and still more preferably 0.80 dL/g. If the reduction viscosity is less than the above lower limit, there may be a problem that the mechanical strength of the molded product decreases. On the other hand, if the reduction viscosity is greater than the above upper limit, there may be a problem of reduced fluidity during molding, and reduced productivity or moldability.
The retardation film constituting the first retardation layer can be obtained by, for example, stretching a film formed of the above-mentioned polycarbonate resin. As a method of forming a film from a polycarbonate-based resin, any appropriate forming method can be adopted. Specific examples include: compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP (Fiber Reinforced Plastics, fiber reinforced plastic) molding method, casting coating method (For example, casting method), calender forming method, hot pressing method, etc. Preferably, it is an extrusion molding method or a cast coating method. The reason is that the smoothness of the obtained film can be improved, so that good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition or type of the resin used, the required characteristics of the retardation film, and the like.
The thickness of the resin film (unstretched film) can be set to any appropriate value according to the required thickness of the obtained retardation film, the required optical properties, the following stretching conditions, and the like. Preferably, it is 50 μm to 300 μm.
Any appropriate stretching method and stretching conditions (e.g. stretching temperature, stretching magnification, stretching direction) can be used for the above-mentioned stretching. Specifically, various extension methods such as free end extension, fixed end extension, free end contraction, and fixed end contraction can be used individually, or simultaneously or successively. Regarding the extension direction, it may be performed in various directions or dimensions such as the length direction, the width direction, the thickness direction, and the oblique direction.
By appropriately selecting the above-mentioned stretching method and stretching conditions, a retardation film having the above-mentioned required optical characteristics (for example, refractive index characteristics, in-plane retardation, and Nz coefficient) can be obtained.
In one embodiment, the retardation film is produced by uniaxially extending a resin film or uniaxially extending a fixed end. As a specific example of uniaxial extension of the fixed end, a method of moving the resin film in the longitudinal direction on one side and extending in the width direction (lateral direction) on the other side can be cited. The stretching ratio is preferably 1.1 to 3.5 times.
In another embodiment, the retardation film can be produced by continuously extending a long resin film obliquely in a direction at a specific angle with respect to the longitudinal direction. By adopting oblique stretching, it is possible to obtain a long stretched film with a specific angle of alignment (having a late phase axis in the direction of a specific angle) with respect to the longitudinal direction of the film. For example, it can be rolled when laminated with a polarizing element. The rollers can simplify the manufacturing steps. Furthermore, the above-mentioned specific angle may be the angle formed by the absorption axis of the first polarizing element and the slow axis of the first retardation layer in the liquid crystal display device. As mentioned above, the angle is preferably 35°-55°, more preferably 38°-52°, still more preferably 40°-50°, particularly preferably 42°-48°, particularly preferably 44°-46 °, the best is about 45 °.
As the stretching machine used for oblique stretching, for example, a tenter-type stretching machine that can impart conveying force or stretching force or extracting force at different speeds in the lateral direction and/or longitudinal direction can be exemplified. Tenter-type stretching machines include horizontal uniaxial stretching machines, synchronous biaxial stretching machines, etc. Any suitable stretching machine can be used as long as the long resin film can be stretched continuously and obliquely.
In the above stretching machine, by appropriately controlling the left and right speeds, respectively, a retardation film having the required in-plane retardation and a slow axis in the required direction (substantially a long strip) can be obtained. The retardation film).
As the method of oblique extension, for example, Japanese Patent Laid-Open No. 50-83482, Japanese Patent Laid-Open No. 2-113920, Japanese Patent Laid-Open No. 3-182701, Japanese Patent Laid-Open No. 2000-9912, Methods described in Japanese Patent Laid-Open No. 2002-86554 and Japanese Patent Laid-Open No. 2002-22944.
The retardation film that can be preferably used in the embodiment of the present invention (that is, the retardation film with an Nz coefficient of less than 1.0) can be bonded to one side or both sides of the resin film by using, for example, an acrylic adhesive. Then, a laminated body is formed, and the laminated body is subjected to the above-mentioned stretching to be produced. By adjusting the structure of the heat shrinkable film (for example, shrinking force) and stretching conditions (for example, stretching temperature), a retardation film with the required Nz coefficient can be obtained.
The stretching temperature of the above-mentioned film can be changed according to the required in-plane retardation value and thickness of the retardation film, the type of resin used, the thickness of the film used, the stretching ratio, etc. Specifically, the stretching temperature is preferably Tg-30°C to Tg+30°C, more preferably Tg-15°C to Tg+15°C, and most preferably Tg-10°C to Tg+10°C. By stretching at such a temperature, a retardation film with appropriate characteristics can be obtained in the present invention. Furthermore, Tg is the glass transition temperature of the constituent material of the film.
A commercially available film can also be used as the polycarbonate resin film. As specific examples of commercially available products, we can cite: the product names "PURE-ACEWR-S", "PURE-ACEWR-W", "PURE-ACEWR-M" manufactured by Teijin, and the product names "NRF" manufactured by Nitto Denko ". The commercially available film can be used directly, or the commercially available film can be used after secondary processing (such as elongation treatment, surface treatment) according to the purpose.
D. Backlight
The backlight light source 300 is included in a backlight unit (not shown). In addition to the light source, the backlight unit typically includes a light guide plate, a diffuser sheet, and a scallop sheet. As mentioned above, the backlight light source has a non-continuous emission spectrum. The so-called "having a non-continuous emission spectrum" means that there are clear peaks in the respective wavelength regions of red (R), green (G), and blue (B) and the respective peaks are clearly distinguished. Fig. 2 is a diagram schematically showing an example of a discontinuous emission spectrum. As shown in FIG. 2, the emission spectrum of the backlight light source has a peak P1 in the wavelength region (blue wavelength region) preferably from 430 nm to 470 nm, more preferably from 440 nm to 460 nm, and preferably from 530 nm to 530 nm. The wavelength region of 570 nm, more preferably 540 nm to 560 nm (wavelength region of green) has a peak P2, and the wavelength region of preferably 630 nm to 670 nm, more preferably 640 nm to 660 nm (wavelength of red) Area) has a peak P3. Preferably, the wavelength λ1 of the peak P1, the height hP1 and the half-value width Δλ1, the wavelength λ2 of the peak P2, the height hP2 and the half-value width Δλ2, the wavelength λ3 of the peak P3, the height hP3 and the half-value width Δλ3, the peak P1 and the peak P2 The height of the trough between hB1 and the height of the trough hB2 between the crest P2 and the crest P3 satisfy the following relations (1) to (3):
(λ2－λ1)/(Δλ2＋Δλ1)＞1・・・(1)
(λ3－λ2)/(Δλ3＋Δλ2)＞1・・・(2)
0.8≦{hP2－(hB2＋hB1)/2}/hP2≦1・・・(3).
(Λ2-λ1)/(Δλ2+Δλ1) in formula (1) is more preferably 1.01 to 2.00, and still more preferably 1.10 to 1.50. (Λ3-λ2)/(Δλ3+Δλ2) in the formula (2) is more preferably 1.01 to 2.00, and still more preferably 1.10 to 1.50. {HP2-(hB2+hB1)/2} of formula (3) is more preferably 0.85-1, and still more preferably 0.9-1. Equation (1) means that the relationship between blue light and green light is independent as a light source without color mixing. The formula (2) means that the relationship between green light and red light is independent as a light source without mixing colors. The formula (3) means that the bottom of the valley between the peaks P1, P2, and P3 is low and the peaks of blue light, green light, and red light are clearly distinguished. By defining formulas (1) to (3), there is an advantage of improved color reproducibility. The synergistic effect of the backlight light source 300 that satisfies the emission spectrum of the formula (1) to the formula (3) and the first retardation layer 200 can achieve excellent color reproducibility and visual recognition by optical members with polarizing effects. A liquid crystal display device with excellent performance and suppressed color unevenness. For example, compared with the previous backlight light source (a white light source combining only red, green, and blue LEDs) with the emission spectrum shown in FIG. 3, the color reproducibility can be achieved through the use of polarized light. The visibility and color unevenness of the functional optical components are all significantly improved.
The backlight light source has any suitable configuration that can realize the above-mentioned emission spectrum. In one embodiment, the backlight light source includes a red emitting LED, a green emitting LED, and a blue emitting LED, and the fluorescent system of the red emitting LED is activated by tetravalent manganese ions. By activating the phosphor of the red emitting LED, the overlap of the red light and the green light in the emission spectrum shown in FIG. 3 can be reduced, so that the emission spectrum shown in FIG. 2 can be realized. As a preferred specific example of this red phosphor activated by tetravalent manganese ions, one can cite William M. Yen and Marvin J. Weber's "INORGANIC PHOSPHORS" p.212 (SECTION 4: PHOSPHOR DATA 4.10 Miscellaneous) published by CRC. Oxides) exemplified by Mn4 +
Activated Mg fluorogermanate phosphor (2.5MgO・MgF2
: Mn4 +
) And the Journal of the Electrochemical Society: SOLID-STATE SCIENCE AND TECHNOLOGY, July 1973, p942 exemplified M1 2
M2
F6
: Mn4 +
(M1
=Li, Na, K, Rb, Cs; M2
=Si, Ge, Sn, Ti, Zr) phosphors. A backlight light source using such a red phosphor is described in, for example, Japanese Patent Laid-Open No. 2015-52648. In addition, a backlight light source having a general configuration including red-emitting LEDs, green-emitting LEDs, and blue-emitting LEDs is described in, for example, Japanese Patent Laid-Open No. 2012-256014. The records in these bulletins are cited in this specification as a reference.
In another embodiment, the backlight light source includes a blue-emitting LED and a wavelength conversion layer including quantum dots. With this configuration, part of the blue light emitted from the LED is converted into red light and green light by the wavelength conversion layer, and the other part of the blue light is directly emitted in the form of blue light. As a result, white light can be realized. Furthermore, by appropriately configuring the wavelength conversion layer, it is possible to realize a light emission spectrum with clear peaks of red light, green light, and blue light and a small overlap of each color light (emission spectrum as shown in FIG. 2).
Typically, the wavelength conversion layer includes a matrix and quantum dots dispersed in the matrix. As the material constituting the matrix (hereinafter also referred to as matrix material), any appropriate material can be used. Examples of such materials include resins, organic oxides, and inorganic oxides. The matrix material preferably has low oxygen permeability and moisture permeability, high light stability and chemical stability, has a specific refractive index, has excellent transparency, and/or has excellent dispersibility for quantum dots . Taking these into consideration comprehensively, the matrix material is preferably a resin. The resin may be a thermoplastic resin, a thermosetting resin, or an active energy ray-curing resin (for example, electron beam curing resin, ultraviolet curing resin, visible light curing resin). Preferably it is a thermosetting resin or an ultraviolet curable resin, More preferably, it is a thermosetting resin. The resin can be used alone or in combination (for example, blending, copolymerization).
Quantum dots can control the wavelength conversion characteristics of the wavelength conversion layer. Specifically, by appropriately combining quantum dots with different emission center wavelengths, a wavelength conversion layer that realizes light with a desired emission center wavelength can be formed. The emission center wavelength of quantum dots can be adjusted by the material and/or composition of the quantum dots, particle size, shape, etc. As quantum dots, for example, there are known quantum dots having a center wavelength of emission in the wavelength band of 600 nm to 680 nm (hereinafter referred to as quantum dot A), and emitting light in the wavelength band of 500 nm to 600 nm. A quantum dot with a central wavelength (hereinafter referred to as quantum dot B), a quantum dot with a central wavelength of emission in the wavelength band of 400 nm to 500 nm (hereinafter referred to as quantum dot C). The quantum dot A is excited by the excitation light (light from the backlight source in the present invention) to emit red light, the quantum dot B emits green light, and the quantum dot C emits blue light. By appropriately combining these, and when light of a specific wavelength (light from a backlight light source) is incident and passed through the wavelength conversion layer, light with a luminous center wavelength in the required wavelength band can be realized.
The quantum dots can be made of any suitable material. The quantum dots can be composed of preferably inorganic materials, more preferably inorganic conductive materials or inorganic semiconductor materials. As the semiconductor material, for example, semiconductors of Group II-VI, Group III-V, Group IV-VI, and Group IV can be cited. Specific examples include Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdSeZn, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si3
N4
, Ge3
N4
, Al2
O3
, (Al, Ga, In)2
(S, Se, Te)3
, Al2
CO. These can be used individually or in combination of 2 or more types. The quantum dots may also contain p-type dopants or n-type dopants.
The size of the quantum dot can be any appropriate size according to the required emission wavelength. The size of the quantum dot is preferably 1 nm to 10 nm, more preferably 2 nm to 8 nm. If the size of the quantum dot is in this range, green and red respectively show bright light emission, so that high color rendering can be achieved. For example, green light can emit light at a quantum dot size of about 7 nm, and red light can emit light at about 3 nm. Regarding the size of the quantum dot, when the quantum dot is, for example, a true spherical shape, it is the average particle diameter, and in the case of other shapes, it is the size along the smallest axis of the shape. Furthermore, as the shape of the quantum dot, any appropriate shape can be adopted according to the purpose. Specific examples include a true spherical shape, a scaly shape, a plate shape, an elliptical spherical shape, and an irregular shape.
The quantum dots can be formulated in a ratio of preferably 1 part by weight to 50 parts by weight, more preferably 2 parts by weight to 30 parts by weight relative to 100 parts by weight of the host material. If the deployment amount of quantum dots is in this range, a liquid crystal display device with excellent balance of all RGB hues can be realized.
The details of quantum dots are described in, for example, Japanese Patent Publication No. 2012-169271, Japanese Patent Publication No. 2015-102857, Japanese Patent Publication No. 2015-65158, Japanese Patent Publication No. 2013-544018, Japanese Patent Japanese Patent Application Publication No. 2013-544018 and Japanese Patent Application Publication No. 2010-533976, and the descriptions in these publications are incorporated into this specification by reference. Commercially available quantum dots can also be used.
The thickness of the wavelength conversion layer is preferably 1 μm to 500 μm, more preferably 100 μm to 400 μm. If the thickness of the wavelength conversion layer is in this range, the conversion efficiency and durability can be excellent.
The wavelength conversion layer in the backlight unit is arranged on the emitting side of the LED (light source) in the form of a film.
E. Second retardation layer
As described above, the refractive index characteristic of the second retardation layer 400 shows the relationship of nz>nx≧ny. The thickness direction retardation Rth(550) of the second retardation layer is preferably -260 nm to -10 nm, more preferably -230 nm to -15 nm, and still more preferably -215 nm to -20 nm. By providing a second retardation layer with such optical characteristics, the color when viewed from an oblique direction through an optical member having a polarizing effect (such as polarized sunglasses) is significantly improved. As a result, very excellent viewing angle characteristics can be obtained. The liquid crystal display device.
In one embodiment, the refractive index of the second retardation layer shows a relationship of nx=ny. In another embodiment, the refractive index of the second retardation layer shows a relationship of nx>ny. Therefore, there are cases where the second retardation layer has a slow axis. In this case, the slow axis of the second retardation layer is substantially perpendicular or parallel to the absorption axis of the first polarizing element 20. In addition, the in-plane retardation Re(550) of the second retardation layer is preferably 10 nm to 150 nm, more preferably 10 nm to 80 nm.
The second retardation layer can be formed of any appropriate material. Preferably, it is a liquid crystal layer fixed in a vertical alignment. The liquid crystal material (liquid crystal compound) capable of vertical alignment can be either a liquid crystal monomer or a liquid crystal polymer. As specific examples of the liquid crystal compound and the method of forming the liquid crystal layer, the liquid crystal compound and the method of forming described in [0020] to [0042] of JP 2002-333642 A can be cited. In this case, the thickness is preferably 0.1 μm to 5 μm, more preferably 0.2 μm to 3 μm.
As another preferable specific example, the second retardation layer may be a retardation film formed of a fumarate diester resin described in JP 2012-32784 A. In this case, the thickness is preferably 5 μm to 80 μm, more preferably 10 μm to 50 μm.
F. Conductive layer
Typically, the conductive layer (not shown) is transparent (that is, the conductive layer is a transparent conductive layer). Since a conductive layer is formed between the first polarizing element 20 and the liquid crystal cell 10, the liquid crystal display device can function as a so-called built-in touch panel type input display device.
The conductive layer can be used alone as a constituent layer of the liquid crystal display device, or it can be provided to the liquid crystal display device in the form of a laminate with a substrate (conductive layer with a substrate). In the case of a conductive layer alone, the conductive layer can be transferred from the substrate on which the conductive layer is formed to a specific position of the liquid crystal display device.
The conductive layer may be patterned as needed. By patterning, the conductive portion and the insulating portion can be formed. As a result, electrodes can be formed. The electrode can function as a touch sensor electrode that senses contact with the touch panel. The shape of the pattern is preferably a pattern that functions well as a touch panel (for example, an electrostatic capacitance type touch panel). Specific examples include Japanese Patent Publication No. 2011-511357, Japanese Patent Application Publication No. 2010-164938, Japanese Patent Application Publication No. 2008-310550, Japanese Patent Application Publication No. 2003-511799, and Japanese Patent Application Publication. The pattern described in the 2010-541109 Bulletin.
The total light transmittance of the conductive layer is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more. For example, if the following conductive nanowires are used, a transparent conductive layer with openings can be formed, and a transparent conductive layer with high light transmittance can be obtained.
The density of the conductive layer is preferably 1.0 g/cm3
～10.5 g/cm3
, More preferably 1.3 g/cm3
～3.0 g/cm3
.
The surface resistance of the conductive layer is preferably 0.1 Ω/□～1000 Ω/□, more preferably 0.5 Ω/□～500 Ω/□, and still more preferably 1 Ω/□～250 Ω/□.
Representative examples of the conductive layer include a conductive layer containing a metal oxide, a conductive layer containing a conductive nanowire, and a conductive layer containing a metal mesh. Preferably, it is a conductive layer containing conductive nanowires or a conductive layer containing metal mesh. The reason is that it is excellent in bending resistance, even if it is bent, the conductivity is not easy to disappear, so it can form a conductive layer that can be bent well. As a result, the liquid crystal display device can be configured to be flexible.
The conductive layer containing metal oxide can be formed by any suitable film forming method (such as vacuum evaporation, sputtering, CVD (Chemical Vapor Deposition, chemical vapor deposition) method, ion plating method, spray method, etc.) A metal oxide film is formed on any suitable substrate. Examples of metal oxides include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferred.
The conductive layer containing conductive nanowires can be coated on any suitable substrate by applying a dispersion of conductive nanowires in a solvent (conductive nanowire dispersion) to make the coating layer Dry and form. As the conductive nanowire, any appropriate conductive nanowire can be used as long as the effects of the present invention can be obtained. The so-called conductive nanowire refers to a conductive material with a needle-like or thread-like shape and a nanometer-sized diameter. Conductive nanowires can be linear or curved. As described above, the conductive layer containing conductive nanowires has excellent bending resistance. In addition, the conductive layer containing conductive nanowires is formed into a grid by forming gaps between the conductive nanowires. Even a small amount of conductive nanowires can form a good conductive path and obtain resistance. Smaller conductive layer. Furthermore, by making the conductive nanowires into a grid shape, openings can be formed in the gaps of the grids to obtain a conductive layer with high light transmittance. Examples of conductive nanowires include metal nanowires made of metal, conductive nanowires containing carbon nanotubes, and the like.
The ratio of the thickness d of the conductive nanowire to the length L (aspect ratio: L/d) is preferably 10 to 100,000, more preferably 50 to 100,000, and still more preferably 100 to 10,000. If a conductive nanowire with a size such as this large is used, the conductive nanowires cross well and the conductivity can be higher than that of a small amount of conductive nanowires. As a result, a conductive layer with high light transmittance can be obtained. Furthermore, in this specification, the "thickness of the conductive nanowire" means the diameter when the cross-section of the conductive nanowire is round, and when it is elliptical, it means The short diameter, in the case of a polygon, means the longest diagonal. The thickness and length of the conductive nanowires can be confirmed with a scanning electron microscope or a transmission electron microscope.
The thickness of the conductive nanowire is preferably less than 500 nm, more preferably less than 200 nm, still more preferably 1 nm to 100 nm, and particularly preferably 1 nm to 50 nm. If it is in this range, a conductive layer with high light transmittance can be formed. The length of the conductive nanowire is preferably 2.5 μm to 1000 μm, more preferably 10 μm to 500 μm, and still more preferably 20 μm to 100 μm. If it is in this range, a conductive layer with higher conductivity can be obtained.
As the metal constituting the conductive nanowire (metal nanowire), any suitable metal can be used as long as it is a metal with relatively high conductivity. The metal nanowire is preferably composed of one or more metals selected from the group consisting of gold, platinum, silver, and copper. Among them, from the viewpoint of conductivity, silver, copper, or gold is preferred, and silver is more preferred. In addition, a material obtained by plating the above-mentioned metal (for example, gold plating) can also be used.
As the carbon nanotube, any appropriate carbon nanotube can be used. For example, so-called multi-layer carbon nanotubes, two-layer carbon nanotubes, single-layer carbon nanotubes, etc. can be used. Among them, in terms of higher conductivity, single-layer carbon nanotubes can be preferably used.
As the metal mesh, any appropriate metal mesh can be used as long as the effects of the present invention can be obtained. For example, the pattern of the metal wiring layer provided on the film base material can be formed into a mesh shape.
The details of the conductive nanowire and the metal mesh are described in, for example, Japanese Patent Application Publication No. 2014-113705 and Japanese Patent Application Publication No. 2014-219667. The description of this gazette is cited in this specification as a reference.
The thickness of the conductive layer is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 3 μm, and still more preferably 0.1 μm to 1 μm. If it is in this range, a conductive layer excellent in conductivity and light transmittance can be obtained. Furthermore, when the conductive layer contains a metal oxide, the thickness of the conductive layer is preferably 0.01 μm to 0.05 μm.
G. Adhesive layer or adhesive layer
Regarding the build-up of each layer and optical member constituting the liquid crystal display device of the present invention, any suitable adhesive layer or adhesive layer can be used. Typically, the adhesive layer is formed of an acrylic adhesive. Typically, the adhesive layer is formed of a polyvinyl alcohol-based adhesive.
[Example]
Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited by these examples. In addition, the measuring method of each characteristic is as follows. In addition, as long as it is not specifically described, the "parts" and "%" in the examples are based on weight.
(1) Thickness
A dial gauge (manufactured by PEACOCK, product name "DG-205", dial gauge holder (product name "pds-2")) was used for measurement.
(2) Phase difference
A 50 mm×50 mm sample was cut from each retardation film and liquid crystal cured layer as a measurement sample, and the measurement was performed using Axoscan manufactured by Axometrics. The measurement wavelength is 450 nm and 550 nm, and the measurement temperature is 23°C.
In addition, the average refractive index was measured using an Abbe refractometer manufactured by Atago, and the refractive indexes nx, ny, and nz were calculated based on the obtained retardation value.
(3) Water absorption
It is measured in accordance with the "Test Method for Water Absorption and Boiling Water Absorption of Plastics" described in JIS K 7209. The size of the test piece is a square with a side length of 50 mm, which is determined by immersing the test piece in water at 25°C for 24 hours and measuring the weight change before and after the immersion. the unit is%.
(4) Backlight spectrum measurement
The liquid crystal display device obtained in each example and each comparative example was allowed to display a white image, and the emission spectrum was measured using SR-UL1R manufactured by Topcon Corporation. Based on the wavelength λ1, wavelength λ2, wavelength λ3, height hP1, height hP2, height hP3, height hB1, height hB2, half-value width Δλ1, half-value width Δλ2, and half-value width shown in Fig. 2 related to the obtained luminescence spectrum The value width Δλ3 is calculated by the following formulas (4), (5), and (6). Furthermore, the spectrum of the display light when the liquid crystal display device displays a white image is approximately equal to the emission spectrum of the backlight light source, so the spectrum of the display light when the white image is displayed is set as the emission spectrum of the backlight light source.
(λ2－λ1)/(Δλ2＋Δλ1)・・・(4)
(λ3－λ2)/(Δλ3＋Δλ2)・・・(5)
{hP2－(hB2＋hB1)/2}/hP2・・・(6)
(5) Visibility evaluation
The liquid crystal display devices obtained in each Example and each Comparative Example were allowed to display a white image, and the visibility when the image was observed through polarized sunglasses was evaluated based on the following criteria.
Good・・・No coloring and uneven rainbow
Defect...coloring occurs
<Example 1>
(Production of retardation film A constituting the first retardation layer)
The polymerization was carried out using a batch polymerization device including two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. Combine 9,9-[4-(2-hydroxyethoxy)phenyl] 茀 (BHEPF), isosorbide (ISB), diethylene glycol (DEG), diphenyl carbonate (DPC), and magnesium acetate The tetrahydrate becomes BHEPF/ISB/DEG/DPC/magnesium acetate in molar ratio = 0.348/0.490/0.162/ 1.005/1.00×10-5
The way to add. After the inside of the reactor is sufficiently replaced with nitrogen (the oxygen concentration is 0.0005 to 0.001 vol%), it is heated with a heating medium, and stirring is started when the internal temperature reaches 100°C. 40 minutes after the temperature rise started, the internal temperature was brought to 220°C, and the temperature was maintained at that temperature. The pressure was started at the same time, and the temperature was set to 13.3 kPa within 90 minutes after reaching 220°C. The phenol vapor that is by-produced with the polymerization reaction is introduced into a reflux condenser at 100°C, a certain amount of monomer components contained in the phenol vapor are returned to the reactor, and the uncondensed phenol vapor is introduced to 45°C for condensation And recycle.
After introducing nitrogen into the first reactor and temporarily returning to atmospheric pressure, the oligomerized reaction liquid in the first reactor is transferred to the second reactor. Then, the heating and depressurization in the second reactor was started, and the internal temperature was 240° C. and the pressure was 0.2 kPa within 50 minutes. Thereafter, polymerization is carried out until a specific stirring power is reached. At the time when the specific power is reached, nitrogen is introduced into the reactor for recompression, the reaction liquid is taken out in the form of strands, and pelletized by a rotary cutting machine to obtain BHEPF/ISB/DEG=34.8/49.0/16.2[ mol%] polycarbonate resin composed of copolymerization. The reduced viscosity of the polycarbonate resin is 0.430 dL/g, and the glass transition temperature is 128°C. After drying the obtained polycarbonate resin in vacuum at 80°C for 5 hours, a single-screw extruder (manufactured by Isuzu Chemical Industry Co., Ltd., screw diameter 25 mm, cylinder setting temperature: 220°C) and T-die (width 900 mm, set temperature: 220°C), cooling roll (set temperature: 125°C), and film forming device of the coiler to produce a polycarbonate resin film with a thickness of 70 μm. The water absorption rate of the obtained polycarbonate resin film was 1.2%. The obtained polycarbonate resin film was uniaxially stretched 2.0 times at 133°C, thereby obtaining a retardation film A (thickness 50 μm). The Re(550) of the obtained retardation film A is 140 nm, the Rth(550) is 140 nm, and the Re(450)/Re(550) is 0.89.
(Production of polarizing element)
Prepare A-PET (amorphous-polyethylene terephthalate) film, (manufactured by Mitsubishi Plastics Co., Ltd., trade name: NOVACLEAR SH046 200 μm) as a substrate, and apply corona treatment (58 W/ m2
/min). On the other hand, it is prepared to add 1 wt% of acetyl acetyl modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: GOHSEFIMER Z200 (polymerization degree 1200, saponification degree of 99.0% or more, acetyl acetate modified) 4.6%)) PVA (polymerization degree 4200, saponification degree 99.2%), coated on the substrate so that the film thickness after drying becomes 12 μm, and dried by hot air drying at 60°C For 10 minutes, a laminate with a PVA-based resin layer provided on the base material was produced.
Then, the layered body was first stretched 2.0 times in the MD direction (Machine direction) at 130°C in air to produce an elongated layered body. Then, a step of immersing the stretched laminate in a boric acid insoluble aqueous solution at a liquid temperature of 30° C. for 30 seconds to insolubilize the PVA layer in which the PVA molecules contained in the stretched laminate are aligned is performed. The boric acid aqueous solution for insolubilization in this step is made to contain 3 parts by weight of boric acid content with respect to 100 parts by weight of water. The colored layered body is produced by dyeing the stretched layered body that has passed the insolubilization step. In this colored laminate system, the stretched laminate is immersed in a dyeing solution so that the PVA layer contained in the stretched laminate adsorbs iodine. The dyeing solution contains iodine and potassium iodide, the temperature of the dyeing solution is set to 30°C, water is used as a solvent, the iodine concentration is set to be in the range of 0.08 to 0.25% by weight, and the potassium iodide concentration is set to be in the range of 0.56 to 1.75% by weight. The ratio of the concentration of iodine to potassium iodide is set to 1 to 7. As the dyeing conditions, the iodine concentration and immersion time were set so that the transmittance of the monomer of the PVA-based resin layer constituting the polarizing element became 40.9%.
Next, a step of immersing the colored laminate in an aqueous solution of boric acid for crosslinking at 30°C for 60 seconds to crosslink the PVA molecules of the PVA layer with iodine adsorbed to each other is performed. The boric acid aqueous solution for crosslinking used in this crosslinking step has a boric acid content of 3 parts by weight relative to 100 parts by weight of water, and a potassium iodide content of 3 parts by weight relative to 100 parts by weight of water. Furthermore, the obtained colored layered body is stretched 2.7 times in the same direction as the previous stretch in air at a stretching temperature of 70°C in a boric acid aqueous solution, so that the final stretch magnification becomes 5.4 times. Obtained an optical film laminate containing a polarizing element for trial use. In the boric acid aqueous solution used in this extension step, the content of boric acid was 4.0 parts by weight relative to 100 parts by weight of water, and the content of potassium iodide was set to 5 parts by weight relative to 100 parts by weight of water. The obtained optical film laminate was taken out from the boric acid aqueous solution, and the boric acid adhering to the surface of the PVA layer was washed with an aqueous solution containing 4 parts by weight of potassium iodide content relative to 100 parts by weight of water. The cleaned optical film laminate was dried by a drying step performed with hot air at 60° C. to obtain a polarizing element with a thickness of 5 μm laminated on the PET film.
(Production of polarizing plate with retardation layer)
In the polarizing element produced in the above manner, for the polarizing element laminated on the PET film with a thickness of 5 μm, the retardation film A is set between its slow axis and the polarizing element through a UV (Ultraviolet) curing adhesive. The angle of the absorption axis is substantially 45°, and it is attached to the surface on the opposite side of the PET. Furthermore, the PET film was peeled from this laminated body, and the polarizing plate with retardation layer was obtained.
(Production of liquid crystal display device)
The liquid crystal panel is taken out of the liquid crystal display device of a smartphone equipped with an IPS method liquid crystal display device (Xperia Z4 manufactured by SONY: the emission spectrum of the backlight light source is non-continuous), and the polarizing plate arranged on the visible side of the liquid crystal cell is removed, And clean the glass surface of the liquid crystal cell. Next, through the acrylic adhesive (thickness 20 μm), the surface of the polarizer side of the polarizing plate with phase difference plate is set so that the absorption axis of the polarizing element is orthogonal to the initial alignment direction of the liquid crystal cell (No. 1 The angle formed by the retardation axis of the retardation layer and the long side of the liquid crystal panel becomes 45°, and the angle formed by the absorption axis of the polarizing element and the long side of the liquid crystal panel becomes 0°) Laminating on the above-mentioned liquid crystal cell On the side surface, a liquid crystal panel is obtained. The backlight unit of the smart phone is mounted on the liquid crystal panel laminated with a polarizing plate with a phase difference plate as the liquid crystal display device of this embodiment. The liquid crystal display device was allowed to display a white image, and the visibility through polarized sunglasses was evaluated in the white image state. The evaluation results are shown in Table 1.
<Example 2>
(Production of retardation film B constituting the first retardation layer)
The polycarbonate resin (10 kg) obtained in the same manner as in Example 1 was dissolved in dichloromethane (73 kg) to prepare a birefringent layer forming material. Next, the above-mentioned birefringent layer forming material was directly coated on a shrinkable film (longitudinal uniaxially stretched polypropylene film, manufactured by Tokyo Ink Co., Ltd., trade name "Noblen"), and the coating film was dried at a drying temperature of 30°C. Dry for 5 minutes and at 80°C for 5 minutes to form a laminate of shrinkable film/birefringent layer. Using a synchronous 2-axis stretching machine, the obtained laminate was stretched in the MD direction with a shrinkage ratio of 0.80 at a stretching temperature of 155°C, and stretched to 1.3 times in the TD direction (Transverse Direction), thereby on the shrinkable film The retardation film B is formed. Next, this retardation film B is peeled from the shrinkable film.
The retardation film B (thickness 60 μm) was obtained in the above manner. Re(550) of the obtained retardation film B is 140 nm, Rth(550) is 70 nm, and Re(450)/Re(550) is 0.89. The slow axis direction of the retardation film B is 90° with respect to the longitudinal direction.
(Production of polarizing plate with retardation layer and liquid crystal display device)
The above-mentioned retardation film B was used instead of the retardation film A, except that the polarizing plate with the retardation layer was produced in the same manner as in Example 1, and the polarizing plate with the retardation layer was used. The liquid crystal display device was fabricated in the same manner as in Example 1. The liquid crystal display device was allowed to display a white image, and the visibility through polarized sunglasses was evaluated in the white image state. The evaluation results are shown in Table 1.
<Example 3>
(Production of liquid crystal cured layer constituting the second retardation layer)
The following chemical formula (I) (the numbers 65 and 35 in the formula represent the molar% of the monomer unit, and for the convenience of description, it is expressed as a block polymer: a weight average molecular weight of 5000), which is a side chain liquid crystal polymer 20 Parts by weight, 80 parts by weight of polymerizable liquid crystal (manufactured by BASF Corporation: trade name Paliocolor LC242) showing a nematic liquid crystal phase, and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) dissolved in the ring A liquid crystal coating liquid was prepared in 200 parts by weight of pentanone. Next, the coating solution was applied to the base film (Non-ene-based resin film: manufactured by Japan ZEON Co., Ltd., trade name "ZEONEX") with a bar coater, and then heated and dried at 80°C 4 minutes, thereby aligning the liquid crystal. The liquid crystal layer is irradiated with ultraviolet rays to harden the liquid crystal layer, thereby forming a liquid crystal cured layer (thickness: 1.10 μm) that becomes the second retardation layer on the base film. The Re (550) of the liquid crystal cured layer is 0 nm, and the Rth (550) is -100 nm, showing the refractive index characteristic of nz>nx=ny.
[化1]
(Production of polarizing plate with retardation layer)
Regarding the laminate of the PET film and the polarizing element obtained in the same manner as in Example 1, the above-mentioned liquid crystal cured layer was cured through a UV curable adhesive to remove the substrate film in the peeling direction of the substrate film and the absorption of the polarizing element It is attached to the surface on the opposite side of the PET film so that the axis becomes substantially parallel. Furthermore, the above-mentioned base film was removed, and the retardation film A produced in the same manner as in Example 1 through a UV-curable adhesive, the angle between the slow axis and the absorption axis of the polarizing element became substantially 45° The method is attached to the side of the liquid crystal cured layer opposite to the polarizing element. Furthermore, after peeling the PET film from the laminate, an acrylic protective film or, if necessary, a retardation layer is bonded via a UV curable adhesive to produce a polarizing plate with a retardation layer.
(Production of liquid crystal display device)
A liquid crystal display device was produced in the same manner as in Example 1, except that the above-mentioned polarizing plate with retardation layer and a smart phone equipped with a different backlight light source were used. The liquid crystal display device was allowed to display a white image, and the visibility through polarized sunglasses was evaluated in the white image state. The evaluation results are shown in Table 1.
<Example 4>
(Production of retardation film C constituting the first retardation layer)
The polycarbonate resin obtained in the same manner as in Example 1 was vacuum dried at 80°C for 5 hours, and then a single-screw extruder (manufactured by Isuzu Chemical Industry Co., Ltd., screw diameter 25 mm, cylinder setting temperature: 220°C) ), T-die (width 900 mm, set temperature: 220°C), cooling roll (set temperature: 125°C), and film-making device of the coiler to produce a polycarbonate resin film with a thickness of 130 μm. The water absorption rate of the obtained polycarbonate resin film was 1.2%.
The above-mentioned polycarbonate resin film was obliquely stretched by the method according to Example 1 of Japanese Patent Laid-Open No. 2014-194483 to obtain a retardation film C.
The specific production sequence of the retardation film C is as follows: the polycarbonate resin film (thickness 130 μm, width 765 mm) is preheated to 142°C in the preheating zone of the stretching device. In the preheating zone, the clamp spacing between the left and right clamps is 125 mm. Then, the film was put into the first inclined extension area C1, and at the same time, the clamp spacing of the right clamp was increased. In the first inclined extension area C1, it increased from 125 mm to 177.5 mm. The rate of change in clamp spacing is 1.42. In the first oblique extension area C1, the distance between the clamps on the left side of the clamp began to decrease. In the first oblique extension area C1, it was reduced from 125 mm to 90 mm. The rate of change in clamp spacing is 0.72. Furthermore, the film was placed in the second oblique extension area C2, and at the same time, the clamp spacing of the left clamp was increased. In the second oblique extension area C2, it was increased from 90 mm to 177.5 mm. On the other hand, the clamp spacing of the right clamp is maintained at 177.5 mm in the second inclined extension area C2. In addition, at the same time as the above-mentioned oblique extension, the extension is 1.9 times in the width direction. Furthermore, the above-mentioned oblique stretching was performed at 135°C. Then, MD shrinking treatment is performed on the shrinking area. Specifically, the clamp spacing between the left clamp and the right clamp was reduced from 177.5 mm to 165 mm. The shrinkage rate in MD shrinking treatment is 7.0%.
The retardation film C (thickness 40 μm) was obtained in the above manner. Re(550) of the obtained retardation film C is 140 nm, Rth(550) is 168 nm, and Re(450)/Re(550) is 0.89. The slow axis direction of the retardation film C is 45° with respect to the longitudinal direction.
(Production of polarizing plate with retardation layer and liquid crystal display device)
The above-mentioned retardation film C was used instead of the retardation film A, except that a polarizing plate with a retardation layer was produced in the same manner as in Example 1, and the polarizing plate with a retardation layer was used. The liquid crystal display device was fabricated in the same manner as in Example 1. The liquid crystal display device was allowed to display a white image, and the visibility through polarized sunglasses was evaluated in the white image state. The evaluation results are shown in Table 1.
＜Comparative example 1＞
(Production of retardation film D constituting the first retardation layer)
A biaxially stretched polypropylene film (manufactured by Toray, trade name "Torayfan" (thickness 60 μm)) is bonded to a commercially available ARTON film (manufactured by JSR, thickness 70 μm) through an acrylic adhesive layer (thickness 15 μm) On both sides. After that, the length direction of the film was maintained by a roll stretcher and stretched to 1.45 times in an air circulation constant temperature oven at 147°C to obtain a retardation film D. Re(550) of the obtained retardation film D is 140 nm, Rth(550) is 70 nm, and Re(450)/Re(550) is 1.00.
(Production of polarizing plate with retardation layer and liquid crystal display device)
The above-mentioned retardation film D was used instead of the retardation film A. Other than that, a polarizing plate with a retardation layer was produced in the same manner as in Example 1, and the polarizing plate with a retardation layer was used. The liquid crystal display device was fabricated in the same manner as in Example 1. The liquid crystal display device was allowed to display a white image, and the visibility through polarized sunglasses was evaluated in the white image state. The evaluation results are shown in Table 1.
＜Comparative example 2＞
(Production of retardation film E constituting the first retardation layer)
Regarding the commercially available ARTON film (manufactured by JSR, thickness 100 μm), the length direction of the film was maintained by a roll stretcher and stretched to 1.8 times in an air circulation constant temperature oven at 147°C to obtain a retardation film E. Re(550) of the obtained retardation film E is 140 nm, Rth(550) is 140 nm, and Re(450)/Re(550) is 1.00.
(Production of polarizing plate with retardation layer)
Except for using the above-mentioned retardation film E, in the same manner as in Example 1, a polarizing plate with a retardation layer was produced.
(Production of liquid crystal display device)
Take out the liquid crystal panel from the liquid crystal display device of the smart phone (iPhone5 manufactured by Apple Inc.: the emission spectrum of the backlight light source is continuous) with the liquid crystal display device of the IPS method, remove the polarizing plate arranged on the viewing side of the liquid crystal cell, and The glass surface of the liquid crystal cell is cleaned. Next, through an acrylic adhesive (thickness 20 μm), the surface of the polarizing element side of the polarizing plate with phase difference plate was laminated so that the absorption axis of the polarizing element became orthogonal to the initial alignment direction of the liquid crystal cell. The surface of the visible side of the above-mentioned liquid crystal cell obtains a liquid crystal panel. The above-mentioned liquid crystal panel on which a polarizing plate with a phase difference plate was laminated was mounted on the above-mentioned smartphone as the liquid crystal display device of the present embodiment. The liquid crystal display device was allowed to display a white image, and the visibility through polarized sunglasses was evaluated in the white image state. The evaluation results are shown in Table 1.
<Comparative Example 3>
(Production of retardation film F constituting the first retardation layer)
Use carbon chloride as a precursor of carbonate, (A) 2,2-bis(4-hydroxyphenyl)propane and (B) 1,1-bis(4-hydroxyphenyl) as an aromatic divalent phenol component )-3,3,5-trimethylcyclohexane, and obtained according to conventional methods (A): (B) with a weight ratio of 4:6 and containing the following chemical formula (II) with a weight average molecular weight (Mw) of 60,000 ) And (III) polycarbonate resin [number average molecular weight (Mn)=33,000, Mw/Mn=1.78]. 70 parts by weight of the above polycarbonate resin and a styrene resin with a weight average molecular weight (Mw) of 1,300 [number average molecular weight (Mn) = 716, Mw/Mn = 1.78] (HIMER SB75 manufactured by Sanyo Chemical Industry) 30 weight 1 part was added to 300 parts by weight of dichloromethane, and stirred and mixed at room temperature for 4 hours to obtain a transparent solution. The solution was cast on a glass plate, and placed at room temperature for 15 minutes, then peeled from the glass plate, dried in an oven at 80°C for 10 minutes, and dried at 120°C for 20 minutes to obtain a thickness of 40 μm and a glass transition temperature ( Tg) is a polymer film at 140°C. The light transmittance of the obtained polymer film at a wavelength of 590 nm was 93%. In addition, the in-plane retardation value of the polymer film: Re(590) is 5.0 nm, and the thickness direction retardation value: Rth(590) is 12.0 nm. The average refractive index is 1.576.
The obtained polymer film was uniaxially stretched to 1.5 times in an air circulating constant temperature oven at 150° C. to obtain a retardation film F. Re(550) of the obtained retardation film F is 140 nm, Rth(550) is 140 nm, and Re(450)/Re(550) is 1.06.
[化2]
(Production of polarizing plate with retardation layer and liquid crystal display device)
The above-mentioned retardation film F was used instead of the retardation film A. Except for this, a polarizing plate with a retardation layer was produced in the same manner as in Example 1, and the polarizing plate with a retardation layer was used. The liquid crystal display device was fabricated in the same manner as in Example 1. The liquid crystal display device was allowed to display a white image, and the visibility through polarized sunglasses was evaluated in the white image state. The evaluation results are shown in Table 1.
[Table 1] 1st retardation layer Second retardation layer Backlight light source Visibility
In-plane phase difference Re550(nm) Wavelength dispersion characteristics (Re450/Re550) Nz coefficient Thickness direction retardation Rth550(nm) spectrum (λ2－λ1)/(△λ2＋△λ1) (λ3－λ2)/(△λ3＋△λ2) {hP2－(hB2＋hB1)/2}/hP2
Example 1 140 0.89 1.0 - non-continuous 1.38 1.63 0.90 good
Example 2 140 0.89 0.5 - non-continuous 1.38 1.63 0.90 good
Example 3 140 0.89 1.0 -100 non-continuous 1.22 1.71 0.85 good
Example 4 140 0.89 1.2 - non-continuous 1.38 1.63 0.90 good
Comparative example 1 140 1.00 0.5 - non-continuous 1.38 1.63 0.90 bad
Comparative example 2 140 1.00 1.0 - continuous 0.88 0.44 0.55 bad
Comparative example 3 140 1.06 1.0 - non-continuous 1.38 1.63 0.90 bad
[Industrial availability]
The liquid crystal display device of the present invention can be preferably used in portable information terminals (PDA), mobile phones, clocks, digital phase machines, portable game consoles and other mobile devices, computer monitors, notebook computers, photocopiers, etc. Office automation equipment, camcorders, LCD TVs, LCD TVs, microwave ovens and other household electrical equipment, rear monitors, car navigation system monitors, car audio and other automotive equipment, commercial store information monitors and other display equipment, surveillance monitoring Various applications such as security equipment such as monitors, nursing care monitors, and medical monitors, etc.
