200821122 九、發明說明 【發明所屬之技術領域】 本發明係關於一種藉由熔融流鑄製膜法所製作的光學 薄膜，特別是用於液晶顯示裝置（LCD )等的偏光板用保 護薄膜、相位差薄膜、擴大視角薄膜、也可利用於電漿顯 示器的抗反射膜等的各種功能薄膜或有機EL顯示器等所 使用的各種功能薄膜等之光學薄膜及其製造方法。 【先前技術】 液晶顯示裝置，與傳統的CRT顯示裝置比較，因節 省空間、節省能源，被廣泛使用作爲監視器。更進一步， 作爲電視（TV )用也逐漸普及。於如此的液晶顯示裝置， 使用偏光薄膜、相位差薄膜等的各種光學薄膜。 可是，液晶顯示裝置所使用的偏光板的偏光薄膜，係 於延伸的聚乙烯醇薄膜所構成的偏光子的單面或兩面，層 合纖維素酯薄膜所構成的光學薄膜作爲保護膜。而且，相 位差薄膜，係因擴大視角、提高對比的目的而使用，將聚 碳酸酯、環狀聚烯烴樹脂、纖維素酯等的薄膜延伸等賦予 遲滯者。亦稱爲光學補償薄膜。 這些光學薄膜，被要求沒有光學缺陷、均勻的遲滯， 特別是沒有相位軸的不均的情況。特別是隨監視器、TV 的大型化、高精細化的進展，這些的要求品質，逐漸變得 口口 r 嚴可。 於光學薄膜的製造方法，大致分爲熔融流鑄製膜法與 -4- 200821122 溶液流鑄製膜法。前者是將聚合物加熱溶解，流鑄於支持 體上，冷卻固化，再依需要進行延伸的方法，而後者是將 聚合物溶解於溶劑中，將該溶液流鑄於支持體上，使溶劑 蒸發，再依需要進行延伸的方法。 任一種製膜法，都是使熔融的聚合物或聚合物溶液在 支持體上冷卻固化、乾燥固化。所以，聚合物薄膜從支持 體剝離後’使用複數傳送滾輪，一邊傳送一邊進行乾燥、 延伸等的處理。 溶液流鑄製膜法，藉由使用大量的溶劑，變成對環境 負荷大的課題。另一方面’熔融流鑄製膜法因不使用溶劑 ，可期待提高生產性，且從環境保護的觀點較理想。 傳統上，作爲藉由熔融流鑄製膜法之薄片•薄膜的成 形裝置，提案下述專利文獻1所記載的裝置。 於專利文獻1，揭露從擠出成形機擠出之薄片狀熔融 樹脂，導入主滾輪及壓迫滾輪（接觸滾輪）之間進行擠壓 成形之薄片•薄膜成形用滾輪裝置，主滾輪係由高剛性的 金屬滾輪構成，接觸滾輪係由具有可撓性的薄壁金屬外筒 與騰出冷卻流體的流動空間與該薄壁金屬外筒同一軸心狀 內嵌的高剛性金屬內筒所構成之由雙重筒構成之薄片•薄 膜成形用滾輪裝置。 於該專利文獻1 ’利用薄壁金屬外筒的彈性變形’可 確保與橡膠滾輪擠壓成形法同樣地對主滾輪的接觸長度’ 藉此可以藉由無儲存的擠壓成形，可製造無殘留彎曲’無 光的不規則反射、雙折射現象之光學上優異的樹脂薄膜· -5- 200821122 薄片。 〔專利文獻1〕日本專利第3 1 94904號公報 【發明內容】 〔發明所欲解決之課題〕 但是，一般藉由接觸滾輪的擠壓壓力，改變薄膜的遲 滯，若寬度變寬時，接觸滾輪的擠壓壓力的寬度方向的均 勻性難以保持。 接觸滾輪的壓力，因在中央部有變低的傾向，於專利 文獻1中，揭露以鼓狀（王冠狀）的接觸滾輪，可提高均 勻性。但是，製膜中改變樹脂的溫度時，滾輪的溫度也改 變，滾輪因熱變形，王冠狀値從最適値偏移，擠壓壓力的 寬度方向的分佈改變，有薄膜的遲滯改變的問題。 本發明的目的，在於解決上述傳統技術的問題，提供 薄膜的遲滯在寬度方向的均勻性提高，得到光學特性佳的 光學薄膜，以及藉由熔融流鑄製膜法製造該薄膜的方法。 〔解決課題之手段〕 爲了達成上述目的，請求範圍第1項的發明，其係熔 融非晶性熱塑性樹脂，使其從流鑄的模頭朝旋轉的支持體 上擠出，該支持體上的溶融樹脂藉由迫緊機構壓於該支持 體的表面，冷卻固化成爲薄膜，將該薄膜從支持體剝離， 以傳送機構傳送後，藉由捲取裝置捲取之藉由熔融流鑄製 膜法之光學薄膜的製造方法，其特徵爲藉由設置於該傳送 -6- 200821122 機構的傳送途中之遲滯測定器，測定該薄膜的遲滯値，根 據該測定器所測定的遲滯値，即時調整該迫緊機構對該支 持體的壓力，控制使該薄膜的遲滯値爲既定的範圍內。 請求範圍第2項的發明，其係如請求範圍第1項的發 明記載之光學薄膜的製造方法，其中該遲滯測定器，在寬 度方向的複數處測定薄膜的遲滯値。 請求範圍第3項的發明，其係如請求範圍第1項的發 明記載之光學薄膜的製造方法，其中使該遲滯測定器所測 定的遲滯値的最大値及最小値的差爲4nm以下，即時調整 該迫緊機構對該支持體的壓力。 上述遲滯値，可爲面內方向之遲滯値或厚度方向之遲 滯値。 而且，根據本發明的光學薄膜的製造方法，捲取時薄 膜的寬度爲1 .5m以上、4.0m以下較理想，捲取（r〇ii up )時薄膜的厚度爲1 5 μ in以上、6 0 μ m以下較理想。 根據本發明的光學薄膜的發明，其特徵爲藉由上述光 學薄膜的製造方法製造，且薄膜寬度方向及長度方向內之 遲滯値的最大値與最小値的差爲4nm以下。 〔發明的效果〕 請求範圍第1項的發明，其係熔融非晶性熱塑性樹脂 ，使其從流鑄的模頭朝旋轉的支持體上擠出，該支持體上 的熔融樹脂藉由迫緊機構壓於該支持體的表面，冷卻固化 成爲薄膜，將該薄膜從支持體剝離，以傳送機構傳送後， 200821122 藉由捲取裝置捲取之藉由熔融流鑄製膜法之光學薄膜的製 造方法，因藉由設置於該傳送機構的傳送途中之遲滯測定 器，測定該薄膜的遲滯値，根據該測定器所測定的遲滯値 ，即時調整該迫緊機構對該支持體的壓力，控制使該薄膜 的遲滯値爲既定的範圍內，根據本發明，可發揮提高上述 薄膜的遲滯在寬度方向的均勻性，可得光學特性佳的光學 薄膜之效果。 請求範圍第2項的發明，其係如請求範圍第1項的發 明記載之光學薄膜的製造方法，因該遲滯測定器在寬度方 向的複數處測定薄膜的遲滯値，根據本發明，可發揮提高 上述薄膜的遲滯在寬度方向的均勻性，可得光學特性佳的 光學薄膜之效果。 請求範圍第3項的發明，其係如請求範圍第1項的發 明記載之光學薄膜的製造方法，因使該遲滯測定器所測定 的遲滯値的最大値及最小値的差爲4nm以下，即時調整該 迫緊機構對該支持體的壓力，根據本發明，可發揮提高上 述薄膜的遲滯在寬度方向的均勻性，可得光學特性佳的光 學薄膜之效果。 根據本發明的光學薄膜的發明，由於藉由上述光學薄 膜的製造方法製造，且薄膜寬度方向及長度方向內之遲滯 値的最大値與最小値的差爲4nm以下，根據本發明，可發 揮提高上述薄膜的遲滯在寬度方向的均勻性，可得光學特 性佳的光學薄膜之效果。 -8- 200821122 【實施方式】 以下’對實施本發明之最佳形態’參照圖面，詳細說 明，但本發明不限於這些。 本發明關於可利用於特別是液晶顯示裝置（LCD )的 偏光板用保護薄膜等之光學薄膜的製造方法。 所使用的薄膜構成材料，以水分、溶劑等爲代表之揮 發成分，在製膜前，或加熱時除去較理想。除去的方法， 可適用習知所謂的乾燥方法，可以加熱法、減壓法、加熱 減壓法等的方法進行，可在空氣中或除濕空氣中或選擇氮 氣爲不活性氣體之環境下進行。進行這些習知的乾燥方法 時’在不分解薄膜構成材料之溫度範圍下進行，從薄膜的 品質上較理想。 製膜前藉由乾燥，可減少揮發成分的產生，樹脂單獨 或樹脂與薄膜構成材料內樹脂以外的至少一種以上的混合 物或相溶物分開’也可進行乾燥。乾燥溫度爲8(rc以上較 理想。乾燥的材料存在具有玻璃轉化溫度之物質時，在比 該玻璃轉化溫度局的乾燥溢度進行加熱時，因材料熔融， 變得難以使用，乾燥溫度爲玻璃轉化溫度以下較理想。複 數的物質具有玻璃轉化溫度時’以玻璃轉化溫度低者爲基 準。乾燥時間爲0.5〜2 4小時較理想，1〜丨8小時更理想 ，1 · 5〜1 2小時更加理想。乾燥溫度太低時，揮發成分的 除去率變低’且乾燥時間太長。而且，乾燥步驟可分爲2 階段以上’例如乾燥步驟包含材料保管用的預先乾燥步驟 以及製膜前〜1週前之間進行的前乾燥步驟。 -9- 200821122 熔融流鑄製膜法，被分類爲加熱熔融的成形法，可適 用溶融擠出成形法、濟壓成形法、充氣（i n fl a t i ο η )法、 射出成形法、吹脹（b 1 〇 w )成形法、延伸成形法等。這些 之中，爲了得到機械強度及表面精度等佳之光學薄膜，熔 融擠出法較理想。以下，以熔融擠出法爲例，說明本發明 的薄膜之製造方法。 圖1表示實施本發明的光學薄膜的製造方法之裝置的 全部構成之槪略流程圖。 參照相同的圖，根據本發明的光學薄膜之製造方法， 混合纖維素樹脂等的薄膜材料後，使用擠出機1，從流鑄 模頭4熔融擠出於第1冷卻滾輪5上，使其與第1冷卻滾 輪5外切。再依序使其與第2冷卻滾輪7、第3冷卻滾輪 8的共3個冷卻滾輪外切，冷卻固化成爲薄膜1 0。然後， 藉由剝離滾輪9剝離之薄膜1 0，再藉由延伸裝置1 2，抓 住薄膜的兩端部，在寬度方向延伸後，由捲取裝置16進 行捲取。而且，爲了矯正平面性，設置接觸滾輪6，以挾 壓熔融薄膜於第1冷卻滾輪5的表面。該接觸滾輪6的表 面具有彈性，在與第1冷卻滾輪5之間形成夾持（nip ) 〇 此處，所謂冷卻滾輪5定義爲挾壓薄膜的2個滾輪中 ，傳送薄膜，與薄膜的接觸時間長的滾輪，冷卻滾輪6定 義爲挾壓時隔著薄膜，從冷卻滾輪5的相反側與薄膜連接 的滾輪。 根據本發明的光學薄膜之製造方法，於接觸滾輪6， -10- 200821122 具備無圖示之壓力控制單元，於該傳送機構的傳 設置遲滯測定器20，在線上測定傳送薄膜的遲滯 該測定器20之遲滯測定値信號電傳輸給接觸滾: 力控制單元，控制單元中，根據該遲滯測定値信 調整接觸滾輪6的壓力，控制傳送薄膜的遲滯値 範圍內。 接觸滾輪6的壓力控制單元，根據來自該ί 之遲滯測定値信號，使傳送的薄膜之遲滯値的最 小値的差維持4nm以下，運算接觸滾輪6對熔融 卻滾輪5表面之壓力，即時調整接觸滾輪6的壓 此處，第1冷卻滾輪5與接觸滾輪6的壓力 使用壓力感測器，一邊測定第1冷卻滾輪5與接 的壓力，一邊藉由馬達調整位置，藉由氣壓缸或 壓力調整，可控制滾輪間的壓力成爲適合的壓力 滾輪6的壓力控制單元，根據來自該測定器2 0 定値信號，可進行藉由這些馬達調整位置、或藉 或油壓缸的壓力調整。 於本發明，即時調整接觸滾輪6的壓力，可 SMC公司製的氣壓缸MBL-1 00。 而且，於本發明，在線上測定傳送薄膜的遲 滯測定器20，可使用例如利用非接觸式的光電管 測機器公司製的Kobra-WX15〇K° 而且，傳送薄膜的遲滯測定器20的設置， 裝置1 2的所謂上游側，也可在下游側。 送途中， :値，來自 輪6的壓 號，即時 .在既定的 則定器2 0 大値及最 薄膜的冷 力。 調整，係 ^觸滾輪6 油壓缸的 。於接觸 之遲滯測 由氣壓缸 使用例如 滯値之遲 之王子計 可在延伸 -11 - 200821122 此處’由遲滯測定器2 0線上測定的傳送薄膜的遲滯 値可爲面內方向的遲滯値（r〇)或厚度方向的遲滯値（Rt )中任一者。而且，Ro表示面內遲滯値，係面內長度方 向MD的折射率與寬度方向T]D的折射率之差乘以厚度者 ，而Rt表示厚度方向的遲滯値，係面內的折射率（長度 方向MD與寬度方向TD的平均）與厚度方向的折射率之 差乘以厚度者。 根據本發明的光學薄膜的製造方法，捲取時薄膜的寬 度爲1 .5m以上、4.0m以下，薄膜的長度例如爲1〇〇〇m以 上，260 0m以下較理想。 而且，根據本發明的光學薄膜的製造方法，捲取時薄 膜的厚度爲1 5 μιη以上、60μηι以下較理想。 根據本發明的光學薄膜的製造方法，熔融擠出的條件 ’可使用其他聚酯等熱塑性樹脂所使用的相同條件進行。 預先乾燥材料較理想。以真空或減壓乾燥機、除濕熱風乾 燥機等’期望使水分爲l〇〇〇ppm以下，較理想爲200ppm 以下進行乾燥。 例如以熱風、真空或減壓下乾燥的纖維素酯樹脂，使 用擠出機1，在擠出溫度200〜300 °C的程度下熔融，以葉 盤狀過濾器2等進行過濾，除去異物。 從供應漏斗（圖示省略）導入擠出機1時，在真空下 或減壓下、不活性氣體環境下，可防止氧化分解等較理想 〇 沒有預先混合可塑劑等添加劑的情況下，可在擠出機 -12- 200821122 的中途拌入。爲了均勻地添加，使用靜態混合器3等的混 合裝置較理想。 於本發明，纖維素樹脂與依需要添加的安定化劑等的 添加劑，熔融前先混合較理想。纖維素樹脂與安定化劑在 最開始時混合更理想。混合可藉由混合機等進行，或可在 上述纖維素樹脂調製的過程中混合。於使用混合機的情況 ’可使用V型混合機、圓錐螺桿型混合機、水平圓筒型混 合機等、漢塞（Henschel )混合機、帶式混合機（ribb〇n mixer )等一般的混合機。混合，在除濕空氣或氮氣等不 活性氣體環境下進行較理想。 如上述薄膜構成材料混合後，其混合物使用擠出機1 可直接熔融製膜，一旦薄膜構成材料顆粒化後，可將該顆 粒以擠出機1熔融製膜。而且，薄膜構成材料含有熔點相 異的複數種材料的情況下，可在只熔融熔點低的材料之溫 度下’製作所謂疙瘩狀半熔融物，將半熔融物投入擠出機 1製膜。於薄膜構成材料含有易熱分解的材料的情況，在 減少熔融次數的目的下，不製作顆粒而直接製膜的方法、 從製作上述疙瘩狀半熔融物而製膜的方法較理想。 擠出機1可使用市場可取得之各種擠出機，以熔融擠 出機較理想，可爲單軸擠出機，也可爲2軸擠出機。從薄 膜構成材料，不製作顆粒，直接進行製膜的情況下，因需 要適當的混練度，使用2軸擠出機較理想，即使是單軸擠 出機，藉由螺桿的形狀變更爲莫達（Maddoc )型、優梅（ U n i m e 11 )型、道美基（D u 1 m a d g e )等混練型螺桿，可得 -13- 200821122 到適當的混練而可能使用。也適合使用全螺紋型螺桿（ full flight screw )、雙螺旋型螺桿（double flight screw )。作爲薄膜構成材料，一旦使用顆粒、疙瘩狀的半熔融 物的情況，單軸擠出機、2軸擠出機都可使用。 擠出機1內及擠出後的冷卻步驟，藉由氮氣等不活性 氣體的取代或減壓，降低氧的濃度較理想。 擠出機1內的薄膜構成材料的熔融溫度，隨薄膜構成 材料的黏度、吐出量、所製造的薄片厚度等，而有不同之 較理想的條件，一般對薄膜的玻璃轉化溫度Tg而言，爲 Tg以上、Tg+l〇〇°C以下，較理想爲Tg+10°C以上、Tg + 90 °C以下。擠出時的熔融黏度爲1 〇〜1 〇 〇 〇 〇 〇泊（p 0丨s e )， 較理想爲100〜1 0000泊。而且，在擠出機1內薄膜構成 材料的滯留時間短較理想，5分鐘以內，較理想爲3分鐘 以內’更理想爲2分鐘以內。滯留時間，雖隨擠出機1的 種類、擠出條件而改變，藉由調整材料的供應量、L/D、 螺桿旋轉數、螺桿的溝槽深度等，而可能縮短。L/D爲1 〇 以上4 0以下較理想，更理想爲2 〇以上3 5以下。壓縮比 爲2以上4以下較理想。 擠出機1的螺桿形狀、旋轉數，可依據薄膜構成材料 的黏度、吐出量等進行適當選擇。本發明之擠出機1的剪 切速度爲1/秒〜1 00 〇〇/秒，較理想爲5/秒〜1 〇〇〇/秒，更 理想爲1 0/秒〜1 〇〇/秒。 作爲本發明所使用的擠出機1，可使用一般塑膠成形 機。 -14- 200821122 從擠出機1擠出之薄膜構成材料，送至流鑄模頭4， 從流鑄模頭4的狹縫擠出成薄膜狀。流鑄模頭4只要是用 以製造薄膜者即可，無特別限制。作爲流鑄模頭4的材質 ，可將硬鉻、碳化鉻、氮化鉻、碳化鈦、碳氮化鈦、氮化 鈦、超鋼、陶瓷（碳化鎢、氧化鋁、氧化鉻）等熱噴塗或 電鍍，進行例如作爲表面加工的拋光（buff )、使用# 1 000紗線支數以後的磨石之磨光（lapping )、使用# 1 〇〇〇紗線支數以後的鑽石磨石之平面切削（切削方向爲垂 直樹脂流動的方向）、電解硏磨、電解複合硏磨等的加工 。流鑄模頭4的唇部的較理想材質爲與流鑄模頭4相同。 而且，唇部的表面精度爲0.5S以下較理想，0.2S以下更 理想。 該流鑄模頭4的狹縫，係間隙爲可調整之構成。雖然 圖示省略，形成流鑄模頭4的狹縫的一對唇中，一者爲剛 性低容易變形之可撓性唇，另一者爲固定的唇。所以，多 數加熱螺栓，在流鑄模頭4的寬度方向，亦即狹縫的長度 方向，以一定的間隔排列。於各加熱螺栓，設置具備埋入 的電熱器與冷卻媒體的通路之區塊，各加熱螺栓縱向貫通 各區塊。螺栓的基部固定於模頭本體，前端與可撓性唇鄰 接。所以一邊經常地空氣冷卻區塊，一邊增減埋入電熱器 的輸入功率，使區塊的溫度上下，藉此使加熱螺栓熱伸縮 ’改變可撓性唇的位置，調整薄膜的厚度。於模頭下游的 需要處設置厚度計，藉此檢測出的薄膜厚度資料回饋給控 制裝置，比較該厚度資料與控制裝置所設定的資料，藉由 -15- 200821122 源自同裝置的修正控制量，控制加熱螺栓的發熱體的電力 或開啓率。加熱螺栓，較理想爲長度20〜40cm、直徑7〜 20mm的圓柱或者是一邊爲5〜20mm的角柱。所以，複數 例如數十個加熱螺栓，較理想爲以間隔20〜40mm排列。 也可設置以藉由手動在軸方向前後移動調節狹縫的間隙之 螺栓爲主體之間隙調節構件，取代加熱螺栓。藉由間隙調 節構件調節的狹縫間隙，通常爲5 0 0〜1 5 0 0 μ m較理想。 於本發明，第1冷卻滾輪5、第2冷卻滾輪7較理想 的材質，例如爲碳鋼、不銹鋼、樹脂、陶瓷等。而且，表 面精度高較理想，表面粗糙度爲〇. 3 S以下，更理想爲 0.1 S以下。 弟2冷卻滾輪7的壁厚，以〇.5mm〜10mm較理想， 更理想爲2mm〜5mm。 第1冷卻滾輪5與第2冷卻滾輪7的振動爲100μιη以 下較理想，更理想爲5 0 μιη以下，冷卻滾輪的真圓度爲 ΙΟΟμπι以下較理想，更理想爲50μηι以下，冷卻滾輪的圓 筒度爲1 〇 〇 μηι以下較理想，更理想爲5 〇 μιη以下。於冷卻 滾輪的內部’使溫水或油流動可保溫之構造較理想。冷卻 滾輪的表面溫度的最大値與最小値的差爲2度以內較理想 〇 第1冷卻滾輪5與第2冷卻滾輪7的間隙，係使用壓 力感測器’一邊測定第1冷卻滾輪5與第2冷卻滾輪7之 間的壓力’一邊藉由馬達調整，藉由氣壓缸或油壓缸的壓 力調整可適當控制冷卻滾輪間的壓力。 -16- 200821122 流鑄模頭4附近設置吸引裝置，除去昇華物較理想。 不使吸引裝置本身成爲昇華物的附著處，進行以加熱器加 熱等的處理較理想。於本發明，吸引壓力太小時，因無法 有效地吸引昇華物，必須有適當的吸引壓力。 於本發明，從T型模頭4依序使熔融狀態的薄膜狀纖 維素酯系樹脂，與第1冷卻滾輪5、第2冷卻滾輪7以及 第3冷卻滾輪8密合，一邊傳送一邊冷卻固化，得到未延 伸的纖維素酯系樹脂薄膜1 0。 於圖1所示的本發明的實施態樣，從第3冷卻滾輪8 ，藉由剝離滾輪9剝離冷卻固化的未延伸之樹脂薄膜1 0， 經過跳動滾輪（dancer roll ;薄膜張力調整滾輪）1 1，導 至延伸裝置1 2，此處延伸薄膜1 〇的橫方向（寬度方向） 。藉由該延伸，使薄膜中的分子配向。 延伸薄膜的橫方向之方法，可使用習知的拉幅機等較 理想。特別是延伸方向爲寬度方向，與偏光薄膜的層合在 成捲形態下實施較理想。因延伸寬度方向，使纖維素酯系 樹脂薄膜所構成的光學薄膜之延遲相位軸爲寬度方向。 另一方面，偏光薄膜的透過軸，也通常爲寬度方向。 因使偏光薄膜的透過軸與光學薄膜之延遲相位軸平行而層 合之偏光板，組裝於液晶顯示裝置，可提高液晶顯示裝置 的對比，且可得良好的視角。 薄膜構成材料的玻璃轉化溫度Tg，可藉由使薄膜構 成材料的種類與構成材料的比例不同而控制。於製作相位 差薄膜作爲光學薄膜的情況，Tg爲120 °C以上，較理想爲 -17- 200821122 135c以上。於液晶顯示裝置，圖像的顯示狀態下，因裝 置本身的溫度上升，例如源自光源的溫度上升，薄膜的溫 度環境改變。此時薄膜的Tg比薄膜的使用環境溫度低時 ’來自藉由延伸而於薄膜內部被固定之分子的配向狀態之 遲滯値以及作爲薄膜的尺寸形狀蒙受大變化。薄膜的Tg 太高時，因薄膜構成材料薄膜化時的溫度變高，能量消耗 變高’且薄膜化時材料本身會分解，因此產生著色，所以 ，Tg爲25 0 °c以下較理想。 而且’延伸步驟，也可以進行習知的熱固定條件、冷 卻、緩和處理，適當地調整使其具有作爲目的的光學薄膜 所要求的特性。 爲了達成液晶顯示裝置的視角擴大用的相位差薄膜之 功能，適當選擇進行上述延伸步驟、熱固定處理。 延伸後，薄膜的端部藉由切割器1 3裁斷成製品的寬 度後，藉由壓花環1 4以及背輪1 5所構成的刻痕加工裝置 ，於薄膜兩端部進行刻痕加工（壓花加工），藉由捲取機 1 6捲取，防止光學薄膜（原卷）F中的貼附、擦傷的產生 〇 刻痕加工的方法，係將側面具有凹凸圖案的金屬環藉 由加熱、加壓，可進行加工。而且，薄膜兩端部的夾鉗的 保持部分通常變形，因無法使用作爲薄膜製品而切除，再 利用爲原料。 於相位差薄膜爲偏光板保護薄膜的情況，該保護薄膜 的厚度爲1 5〜6 0 μπι較理想。相位差薄膜厚時，偏光板加 -18- 200821122 工後的偏光板變得太厚，對筆記型電腦、攜帶型電子機 所使用的液晶顯示’特別是輕、薄的目的，並不適用。 一方面，相位差薄膜薄時，作爲相位差薄膜的遲滯値變 難以發現，且薄膜的透濕性變高，因保護偏光子免受濕 的能力降低，所以不理想。 根據本發明的光學薄膜，係由本發明之光學薄膜的 造方法製造，且薄膜寬度方向及長度方向內之遲滯値的 大値與最小値的差爲4nm以下。根據本發明的光學薄膜 提高上述薄膜的遲滯在寬度方向的均勻性，光學薄膜的 學特性佳。 以上所得的寬度方向被延伸之光學薄膜，藉由延伸 分子配向，保持一定大小的遲滯値。通常薄膜的面內方 遲滯値（R〇)爲20〜200nm，厚度方向遲滯値（Rt)爲 〜400nm;薄膜的面內方向遲滯値（Ro)爲 20〜lOOnm 厚度方向遲滯値（Rt )爲90〜200nm較理想。而且， 與Ro的比·· Rt/Ro爲0.5〜2.5較理想，特別是1.0〜2 較理想。 而且，薄膜的延遲相位軸方向的折射率爲Nx，前 相位軸的折射率爲N y，厚度方向的折射率爲N z，薄膜 膜厚爲d ( nm )時， R〇=(Nx-Ny)xd200821122 IX. DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an optical film produced by a melt casting method, particularly a protective film for a polarizing plate of a liquid crystal display device (LCD), and a phase thereof. The optical film and the manufacturing method of various functional films used for various functional films, such as an antireflection film of a plasma display, or an organic EL display, etc., and the manufacturing method of the film can also be used. [Prior Art] A liquid crystal display device is widely used as a monitor because it saves space and saves energy compared with a conventional CRT display device. Further, it has become popular as a television (TV). In such a liquid crystal display device, various optical films such as a polarizing film and a retardation film are used. However, the polarizing film of the polarizing plate used in the liquid crystal display device is a single layer or both surfaces of a polarizer composed of a stretched polyvinyl alcohol film, and an optical film composed of a cellulose ester film is laminated as a protective film. Further, the phase difference film is used for the purpose of widening the viewing angle and improving the contrast, and imparts retardation such as stretching of a film such as polycarbonate, a cyclic polyolefin resin or a cellulose ester. Also known as optical compensation film. These optical films are required to have no optical defects, uniform hysteresis, and particularly, there is no unevenness of the phase axis. In particular, with the progress of the large-scale and high-definition of monitors and TVs, the quality of these requirements has gradually become strict. The method for producing an optical film is roughly classified into a melt casting method and a -4-200821122 solution casting method. The former is a method in which a polymer is heated and dissolved, cast on a support, cooled and solidified, and then extended as needed, while the latter dissolves the polymer in a solvent, and the solution is cast on a support to evaporate the solvent. And then extend the method as needed. In any of the film forming methods, the molten polymer or polymer solution is cooled, solidified, and solidified on a support. Therefore, after the polymer film is peeled off from the support, the processing is carried out by drying or stretching while transferring using a plurality of transfer rollers. The solution casting method has a problem that the environmental load is large by using a large amount of solvent. On the other hand, the melt casting film forming method is expected to improve productivity without using a solvent, and is preferable from the viewpoint of environmental protection. Conventionally, as a forming apparatus for a sheet and a film by a melt casting method, the apparatus described in Patent Document 1 below is proposed. Patent Document 1 discloses a sheet-like molten resin extruded from an extrusion molding machine, and a sheet for forming a sheet formed by extrusion between a main roller and a pressing roller (contact roller), and a main roller is made of high rigidity. The metal roller is composed of a high-rigidity metal inner cylinder in which a flexible thin metal outer cylinder and a flow space for venting a cooling fluid are embedded in the same axial shape as the thin metal outer cylinder. Sheet made of double cylinders • Roller for film forming. Patent Document 1 'Using the elastic deformation of the thin-walled metal outer cylinder' ensures the contact length of the main roller in the same manner as the rubber roller extrusion molding method, whereby the residue can be produced without storage, and no residue can be produced. Optically excellent resin film that bends 'no light irregular reflection and birefringence phenomenon. · -5- 200821122 Sheet. [Patent Document 1] Japanese Patent No. 3 1 94904 [Disclosure] [Problems to be Solved by the Invention] However, the hysteresis of the film is generally changed by the pressing pressure of the contact roller, and the contact roller is used when the width is widened. The uniformity of the width direction of the extrusion pressure is difficult to maintain. The pressure of the contact roller tends to become lower at the center portion. In Patent Document 1, a roller-shaped (crown-shaped) contact roller is disclosed to improve uniformity. However, when the temperature of the resin is changed in the film formation, the temperature of the roller is also changed, and the roller is thermally deformed, the crown-shaped ridge is displaced from the optimum enthalpy, and the distribution in the width direction of the squeezing pressure is changed, and the hysteresis of the film is changed. SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the above conventional techniques, to provide an improvement in uniformity of hysteresis of a film in the width direction, to obtain an optical film excellent in optical characteristics, and a method of producing the film by a melt casting method. [Means for Solving the Problem] In order to achieve the above object, the invention of claim 1 is a molten amorphous thermoplastic resin which is extruded from a die-casting die onto a rotating support, on the support The molten resin is pressed against the surface of the support by a pressing mechanism, cooled and solidified into a film, and the film is peeled off from the support, transferred by a conveying mechanism, and then wound by a winding device to form a film by melt casting. The method for producing an optical film is characterized in that the hysteresis 该 of the film is measured by a hysteresis measuring device provided in the middle of the transport of the transmission -6-200821122, and the forced stagnation is immediately adjusted according to the hysteresis measured by the measuring device. The pressure of the tensioning mechanism on the support is controlled such that the hysteresis of the film is within a predetermined range. The invention of claim 2 is the method for producing an optical film according to the invention of claim 1, wherein the hysteresis measuring device measures the hysteresis of the film at a plurality of points in the width direction. The invention of claim 3 is the method for producing an optical film according to the invention of claim 1, wherein the difference between the maximum enthalpy and the minimum enthalpy of the hysteresis measured by the hysteresis measuring device is 4 nm or less. Adjust the pressure of the pressing mechanism to the support. The above retardation 値 may be a hysteresis in the in-plane direction or a retardation in the thickness direction. Further, according to the method for producing an optical film of the present invention, the width of the film at the time of winding is preferably 1.5 m or more and 4.0 m or less, and when the film is wound up, the thickness of the film is 15 μ in or more. Below 0 μm is preferred. According to the invention of the optical film of the invention, it is characterized in that the difference between the maximum 値 and the minimum 迟 of the hysteresis 薄膜 in the width direction and the longitudinal direction of the film is 4 nm or less. [Effects of the Invention] The invention of claim 1 is a molten amorphous thermoplastic resin which is extruded from a die-casting die toward a rotating support, and the molten resin on the support is pressed The mechanism is pressed against the surface of the support, cooled and solidified into a film, and the film is peeled off from the support, and then transported by a transport mechanism, 200821122 is produced by a melt-casting film-forming optical film by a winding device. According to the method, the hysteresis 该 of the film is measured by a hysteresis measuring device provided in the middle of the transport of the transport mechanism, and the pressure of the supporting mechanism is immediately adjusted according to the hysteresis measured by the measuring device, and the control is performed. According to the present invention, the hysteresis of the film is in a predetermined range, and the effect of improving the uniformity of the hysteresis of the film in the width direction can be obtained, and an optical film having excellent optical characteristics can be obtained. The invention of claim 2 is the method for producing an optical film according to the invention of claim 1, wherein the hysteresis measuring device measures the hysteresis of the film at a plurality of points in the width direction, and is improved according to the present invention. The hysteresis of the above film in the width direction gives an effect of an optical film having excellent optical characteristics. The invention of claim 3 is the method for producing an optical film according to the invention of claim 1, wherein the difference between the maximum enthalpy and the minimum enthalpy of the hysteresis measured by the hysteresis measuring device is 4 nm or less. According to the present invention, it is possible to improve the uniformity of the hysteresis of the film in the width direction, and to obtain an optical film having excellent optical characteristics. According to the invention of the optical film of the present invention, the difference between the maximum 値 and the minimum 迟 of the hysteresis 薄膜 in the width direction and the longitudinal direction of the film is 4 nm or less, which is improved by the present invention. The hysteresis of the above film in the width direction gives an effect of an optical film having excellent optical characteristics. [Embodiment] Hereinafter, the best mode for carrying out the invention will be described in detail with reference to the drawings, but the invention is not limited thereto. The present invention relates to a method for producing an optical film which can be used, for example, as a protective film for a polarizing plate of a liquid crystal display device (LCD). The film constituting material to be used is a volatile component typified by water, a solvent, etc., and is preferably removed before film formation or heating. The method of removal can be carried out by a conventional drying method, which can be carried out by a heating method, a reduced pressure method, a heating and decompression method, or the like, and can be carried out in the air or in a dehumidified air or in an environment where nitrogen is selected as an inert gas. When these conventional drying methods are carried out, it is carried out at a temperature range in which the film constituent material is not decomposed, and the quality of the film is preferable. Drying before film formation can reduce the generation of volatile components, and the resin alone or the resin can be separated from at least one kind of mixture or a mixture other than the resin in the film constituent material. The drying temperature is preferably 8 or more. When the dried material has a glass transition temperature, when it is heated at a drying degree higher than the glass transition temperature, the material becomes molten and becomes difficult to use, and the drying temperature is glass. The conversion temperature is preferably below. When the plurality of materials have a glass transition temperature, the temperature is lower than the glass transition temperature. The drying time is 0.5 to 2 4 hours, more preferably 1 to 8 hours, and 1 to 5 to 12 hours. More preferably, when the drying temperature is too low, the removal rate of the volatile component becomes low and the drying time is too long. Moreover, the drying step can be divided into two or more stages. For example, the drying step includes a pre-drying step for material storage and before film formation. Pre-drying step performed between 1 week ago. -9- 200821122 Melt casting method, which is classified into a hot melt forming method, can be applied to melt extrusion molding, pressure forming, and inflation (in fl ati ο η) method, injection molding method, inflation (b 1 〇w) molding method, extension molding method, etc. Among them, in order to obtain optical thinness such as mechanical strength and surface precision The melt extrusion method is preferred. Hereinafter, a method for producing a film of the present invention will be described by taking a melt extrusion method as an example. Fig. 1 is a schematic flow chart showing the overall configuration of an apparatus for carrying out the method for producing an optical film of the present invention. Referring to the same drawing, according to the method for producing an optical film of the present invention, a film material such as a cellulose resin is mixed, and then melted and extruded from the casting die 4 onto the first cooling roller 5 using an extruder 1 to form a film. The first cooling roller 5 is circumscribed, and then three cooling rollers of the second cooling roller 7 and the third cooling roller 8 are sequentially cut out, and cooled and solidified into a film 10. Then, the peeling roller 9 is peeled off. The film 10 is further grasped at both ends of the film by the stretching device 12, and is stretched in the width direction, and then taken up by the winding device 16. Further, in order to correct the flatness, the contact roller 6 is provided to be pressed. The molten film is on the surface of the first cooling roller 5. The surface of the contact roller 6 has elasticity, and a nip is formed between the first cooling roller 5, and the cooling roller 5 is defined as a rolled film. Among the scroll wheels The film, the roller having a long contact time with the film, and the cooling roller 6 are defined as a roller which is connected to the film from the opposite side of the cooling roller 5 while being pressed by the film. The method for manufacturing the optical film according to the present invention is to contact the roller 6 , -10- 200821122 Having a pressure control unit (not shown), the hysteresis detector 20 of the transmission mechanism is used to measure the hysteresis of the transport film on the line. The hysteresis measurement of the measuring device 20 is transmitted to the contact roller: force control In the unit, the control unit adjusts the pressure of the contact roller 6 according to the hysteresis measurement signal to control the hysteresis range of the transport film. The pressure control unit of the contact roller 6 determines the transmitted film based on the hysteresis signal from the ί. The difference of the minimum enthalpy of the hysteresis 维持 is maintained below 4 nm, and the pressure of the contact roller 6 on the surface of the molten roller 5 is calculated, and the pressure of the contact roller 6 is adjusted immediately, and the pressure of the first cooling roller 5 and the contact roller 6 is sensed using pressure. While measuring the pressure of the first cooling roller 5 and the connection, the position is adjusted by the motor, and the pneumatic cylinder or pressure adjustment is controllable. Pressure rollers between the pressure rollers become suitable pressure control unit 6, based on the pressure measurement device 20 to the predetermined signal Zhi, these motors can be adjusted by position, or by the hydraulic cylinder or from the adjustment. In the present invention, the pressure of the contact roller 6 can be adjusted in real time, and the pneumatic cylinder MBL-1 00 manufactured by SMC can be used. Further, in the present invention, the hysteresis measuring device 20 for measuring the transport film on the line can be used, for example, by Kobel-WX15〇K° manufactured by Photoelectric Tube Co., Ltd., which is a non-contact type, and the hysteresis measuring device 20 for transporting the film, the device. The so-called upstream side of 1 2 can also be on the downstream side. On the way to the delivery, :値, the pressure from the wheel 6, instant. In the established, the temperature of the 20 値 and the most film cooling. Adjust, press ^ roller 6 hydraulic cylinder. The hysteresis of the contact is measured by the pneumatic cylinder using, for example, the late prince of the stagnation. The delay of the transport film measured by the hysteresis detector 20 line can be the hysteresis in the in-plane direction (Extension -11 - 200821122) R〇) or any of the retardation 値(Rt) in the thickness direction. Further, Ro represents the in-plane retardation 値, the difference between the refractive index of the MD in the longitudinal direction of the system plane and the refractive index of the width direction T]D is multiplied by the thickness, and Rt represents the retardation 厚度 in the thickness direction, and the refractive index in the plane ( The difference between the average of the length direction MD and the width direction TD and the refractive index in the thickness direction is multiplied by the thickness. According to the method for producing an optical film of the present invention, the film has a width of 1.5 m or more and 4.0 m or less at the time of winding, and the film has a length of, for example, 1 μm or more and 260 0 m or less. Further, according to the method for producing an optical film of the present invention, the thickness of the film at the time of winding is preferably 15 μm or more and 60 μη or less. According to the method for producing an optical film of the present invention, the conditions of melt extrusion can be carried out under the same conditions as those used for thermoplastic resins such as other polyesters. Pre-dried materials are ideal. In a vacuum or a vacuum dryer, a dehumidifying hot air dryer, etc., it is desirable to dry the water to be 1 〇〇〇 ppm or less, preferably 200 ppm or less. For example, the cellulose ester resin which is dried by hot air, vacuum or under reduced pressure is melted by an extruder 1 at an extrusion temperature of 200 to 300 ° C, and filtered by a disk-shaped filter 2 or the like to remove foreign matter. When the extruder 1 is introduced from the supply funnel (not shown), it is possible to prevent oxidative decomposition or the like under vacuum or under reduced pressure or in an inert gas atmosphere. When an additive such as a plasticizer is not preliminarily mixed, Stir in the middle of the extruder -12- 200821122. In order to uniformly add, a mixing device using a static mixer 3 or the like is preferable. In the present invention, an additive such as a cellulose resin and a stabilizer which is added as needed is preferably mixed before melting. It is more desirable to mix the cellulose resin with the stabilizer at the very beginning. The mixing may be carried out by a mixer or the like, or may be mixed during the preparation of the above cellulose resin. In the case of using a mixer, a general mixing such as a V-type mixer, a conical screw type mixer, a horizontal cylinder type mixer, a Hanschel mixer, or a belt mixer (ribb〇n mixer) can be used. machine. Mixing is preferably carried out in an inert gas atmosphere such as dehumidified air or nitrogen. After the above-mentioned film constituting materials are mixed, the mixture can be directly melt-molded using the extruder 1, and once the film constituting material is granulated, the granules can be melt-formed by the extruder 1. Further, when the film constituent material contains a plurality of materials having different melting points, the so-called hazel-like semi-molten can be produced at a temperature at which only a material having a low melting point is melted, and the semi-melt can be introduced into the extruder 1 to form a film. In the case where the film constituent material contains a material which is easily decomposed by heat, a method of directly forming a film without forming particles and a method of forming a film from the above-described braided semi-melt are preferable for the purpose of reducing the number of times of melting. The extruder 1 can use various extruders available in the market, and it is preferable to use a melt extruder, which may be a single-shaft extruder or a 2-axis extruder. When forming a film directly from a film constituting material without granules, it is preferable to use a 2-axis extruder because of the need for appropriate kneading. Even a single-axis extruder is changed to a Moda shape by a screw. Mixing screws such as (Maddoc), U nime 11 and D u 1 madge can be used from -13 to 200821122 to proper mixing. It is also suitable to use a full flight screw or a double flight screw. As the film constituting material, a single-screw extruder or a 2-axis extruder can be used once a pellet or a halo-like semi-molten is used. In the cooling step in the extruder 1 and after the extrusion, it is preferable to reduce the concentration of oxygen by substitution or decompression of an inert gas such as nitrogen. The melting temperature of the film constituent material in the extruder 1 varies depending on the viscosity of the film constituent material, the amount of discharge, the thickness of the sheet to be produced, and the like, and generally, the glass transition temperature Tg of the film is generally It is Tg or more and Tg+l〇〇°C or less, and preferably Tg+10°C or more and Tg+90°C or less. The melt viscosity at the time of extrusion is 1 〇 1 1 〇 〇 〇 〇 (p 0丨s e ), preferably 100 to 1 0000 poise. Further, the residence time of the film constituent material in the extruder 1 is preferably short, and within 5 minutes, preferably within 3 minutes, more preferably within 2 minutes. The residence time varies depending on the type of the extruder 1 and the extrusion conditions, and may be shortened by adjusting the supply amount of the material, the L/D, the number of screw rotations, the groove depth of the screw, and the like. L/D is preferably 1 〇 or more and 4 or less, more preferably 2 〇 or more and 3 5 or less. The compression ratio is preferably 2 or more and 4 or less. The screw shape and the number of rotations of the extruder 1 can be appropriately selected depending on the viscosity of the film constituent material, the discharge amount, and the like. The shearing speed of the extruder 1 of the present invention is from 1/sec to 1 00 〇〇/sec, preferably from 5/sec to 1 〇〇〇/sec, more preferably from 10/sec to 1 〇〇/sec. . As the extruder 1 used in the present invention, a general plastic molding machine can be used. -14- 200821122 The film constituent material extruded from the extruder 1 is sent to the casting die 4, and extruded into a film shape from the slit of the casting die 4. The cast molding die 4 is not particularly limited as long as it is used for producing a film. As a material of the casting die 4, thermal chrome, chromium carbide, chromium nitride, titanium carbide, titanium carbonitride, titanium nitride, ultra-steel, ceramics (tungsten carbide, alumina, chrome oxide) or the like can be thermally sprayed or Electroplating, for example, buffing as a surface finish, lapping using a #1 000 yarn count, and diamond cutting of a diamond grindstone after using a #1 〇〇〇 yarn count (The cutting direction is the direction in which the vertical resin flows), electrolytic honing, electrolytic composite honing, and the like. The preferred material of the lip of the cast die 4 is the same as that of the cast die 4. Further, the surface accuracy of the lip portion is preferably 0.5 S or less, and more preferably 0.2 S or less. The slit of the casting die 4 has an adjustable gap. Although not shown in the drawings, one of the pair of lips forming the slit of the casting die 4 is a flexible lip which is low in rigidity and easily deformed, and the other is a fixed lip. Therefore, most of the heating bolts are arranged at a constant interval in the width direction of the casting die 4, that is, in the longitudinal direction of the slit. A block having a passage for the embedded electric heater and the cooling medium is provided in each of the heating bolts, and each of the heating bolts extends through the blocks in the longitudinal direction. The base of the bolt is fixed to the body of the die, and the front end is adjacent to the flexible lip. Therefore, while constantly cooling the block by air, the input power of the embedded electric heater is increased or decreased, and the temperature of the block is raised and lowered, whereby the heating bolt is thermally stretched and the position of the flexible lip is changed to adjust the thickness of the film. A thickness gauge is disposed at a position downstream of the die, and the detected film thickness data is fed back to the control device to compare the thickness data with the data set by the control device, and the correction control amount derived from the same device by -15-200821122 , controlling the power or opening rate of the heating element of the heating bolt. The heating bolt is preferably a cylinder having a length of 20 to 40 cm and a diameter of 7 to 20 mm or a corner column having a side of 5 to 20 mm. Therefore, for example, a plurality of heating bolts are preferably arranged at intervals of 20 to 40 mm. Instead of the heating bolt, it is also possible to provide a gap adjusting member mainly composed of a bolt which manually moves the gap of the adjusting slit forward and backward in the axial direction. The slit gap adjusted by the gap adjusting member is usually preferably 500 to 1 500 μm. In the present invention, the first cooling roller 5 and the second cooling roller 7 are preferably made of carbon steel, stainless steel, resin, ceramics or the like. Further, the surface precision is preferably high, and the surface roughness is 〇. 3 S or less, more preferably 0.1 S or less. The wall thickness of the cooling roller 7 is preferably from 5 mm to 10 mm, more preferably from 2 mm to 5 mm. The vibration of the first cooling roller 5 and the second cooling roller 7 is preferably 100 μm or less, more preferably 50 μm or less, and the roundness of the cooling roller is preferably ΙΟΟμπι or less, more preferably 50 μm or less, and the cylinder for cooling the roller. The degree is preferably 1 〇〇μηι or less, more preferably 5 〇μιη or less. In the interior of the cooling roller, a structure in which warm water or oil flows can be kept warm is preferable. The difference between the maximum 値 and the minimum 表面 of the surface temperature of the cooling roller is preferably within 2 degrees, and the gap between the first cooling roller 5 and the second cooling roller 7 is preferably measured by using the pressure sensor 'to measure the first cooling roller 5 and the first 2 The pressure between the cooling rollers 7 is adjusted by the motor, and the pressure between the cooling rollers can be appropriately controlled by the pressure adjustment of the pneumatic cylinder or the hydraulic cylinder. -16- 200821122 A suction device is provided near the flow molding die 4, and it is preferable to remove the sublimate. It is preferable that the suction device itself is not attached to the sublimate, and heating by heating or the like is preferably performed. In the present invention, the suction pressure is too small, and since the sublimate cannot be effectively attracted, it is necessary to have an appropriate suction pressure. In the present invention, the film-form cellulose ester-based resin in a molten state is closely adhered to the first cooling roller 5, the second cooling roller 7, and the third cooling roller 8 from the T-die 4, and is cooled and solidified while being conveyed. An unstretched cellulose ester resin film 10 was obtained. In the embodiment of the present invention shown in FIG. 1, the cooled and solidified unstretched resin film 10 is peeled off from the third cooling roller 8 by the peeling roller 9, and the dancer roller (film tension adjusting roller) 1 is passed. 1. Lead to the extension device 1 2, where the transverse direction (width direction) of the film 1 延伸 is extended. By this extension, the molecules in the film are aligned. The method of extending the transverse direction of the film can be preferably carried out by using a conventional tenter or the like. In particular, the extending direction is the width direction, and the lamination of the polarizing film is preferably carried out in a roll form. The retardation phase axis of the optical film composed of the cellulose ester-based resin film is in the width direction in the extending width direction. On the other hand, the transmission axis of the polarizing film is also generally in the width direction. By disposing the polarizing plate in which the transmission axis of the polarizing film is parallel to the retarded phase axis of the optical film, the polarizing plate is assembled in the liquid crystal display device, and the contrast of the liquid crystal display device can be improved, and a good viewing angle can be obtained. The glass transition temperature Tg of the film constituent material can be controlled by making the type of the film-forming material different from the ratio of the constituent materials. In the case of producing a retardation film as an optical film, the Tg is 120 °C or higher, and preferably -17-200821122 135c or more. In the liquid crystal display device, in the display state of the image, the temperature of the film itself changes, for example, the temperature from the light source rises, and the temperature environment of the film changes. At this time, when the Tg of the film is lower than the ambient temperature of the film, the hysteresis 来自 from the alignment state of the molecules fixed by the inside of the film and the dimensional shape of the film are greatly changed. When the Tg of the film is too high, the temperature at which the film constituent material is thinned becomes high, and the energy consumption becomes high. When the film is formed, the material itself is decomposed and coloring occurs. Therefore, the Tg is preferably 25 ° C or less. Further, the 'extension step' can be carried out by conventional heat setting conditions, cooling, and relaxation treatment, and appropriately adjusted to have characteristics required for the intended optical film. In order to achieve the function of the retardation film for expanding the viewing angle of the liquid crystal display device, the above-described stretching step and heat fixing treatment are appropriately selected. After the extension, the end of the film is cut into the width of the product by the cutter 13, and then the scoring processing device formed by the embossing ring 14 and the back wheel 15 is used for scoring at both ends of the film (pressure The method of preventing the occurrence of scratching and scratching in the optical film (original roll) F by the winding of the winder 16 is to heat the metal ring having the concave-convex pattern on the side surface by heating, Pressurized for processing. Further, the holding portion of the clamp at both end portions of the film is usually deformed, and it cannot be used as a film product, and is reused as a raw material. In the case where the retardation film is a polarizing plate protective film, the thickness of the protective film is preferably from 1 5 to 60 μm. When the retardation film is thick, the polarizing plate after the polarizing plate is added -18-200821122 becomes too thick, and the liquid crystal display used for the notebook computer and the portable electronic device is not particularly suitable for the purpose of lightness and thinness. On the other hand, when the retardation film is thin, it is difficult to find the hysteresis of the retardation film, and the moisture permeability of the film is high, which is undesirable because the ability to protect the polarizer from moisture is lowered. The optical film according to the present invention is produced by the method for producing an optical film of the present invention, and the difference between the maximum 値 and the minimum 迟 of the hysteresis in the width direction and the longitudinal direction of the film is 4 nm or less. The optical film according to the present invention improves the uniformity of the hysteresis of the above film in the width direction, and the optical film has excellent academic properties. The optical film extending in the width direction obtained above is maintained in a certain amount of hysteresis by extending molecular alignment. Generally, the in-plane retardation 値(R〇) of the film is 20 to 200 nm, and the retardation 厚度(Rt) in the thickness direction is ～400 nm; the in-plane retardation 薄膜(Ro) of the film is 20 to 100 nm, and the thickness direction retardation R(Rt ) is 90~200nm is ideal. Further, the ratio R·/R of Ro is preferably 0.5 to 2.5, and particularly preferably 1.0 to 2. Further, the refractive index of the film in the retarded phase axis direction is Nx, the refractive index of the front phase axis is N y , the refractive index in the thickness direction is N z , and when the film thickness is d (nm ), R 〇 = (Nx - Ny )xd
Rt={( Nx + Ny)/2-Nz} xd 遲滯値的不均勻越小越好，通常爲1 5 nm以內，較 想爲1 Onm以下，更理想爲4nm以下。 器 另 得 度 製 最 j 光 使 向 90 Rt 進 的 理 -19- 200821122 本發明所使用的樹脂，以乙酸纖維素、丙酸纖維素、 丁酸纖維素、乙酸丙酸纖維素、乙酸丁酸纖維素、乙酸酞 酸纖維素以及酞酸纖維素較理想，但不限於這些。上述纖 維素酯的乙醯基的取代度，至少爲1 . 5以上，因所得的薄 膜尺寸安定性佳，所以較理想。作爲纖維素酯的醯基的取 代度之測定方法，可根據ASTM-D817-91進行。纖維素酯 的分子量，以數量平均分子量爲50,000〜300,000。特別 是60,000〜200，000，因所得的薄膜之機械強度強，所以 較理想。 於本發明，非晶性熱塑性樹脂中，因各種目的，可含 有可塑劑、紫外線吸收劑、抗氧化劑、消光劑、抗靜電劑 、難燃劑、染料以及油劑等的添加劑。 作爲可塑劑，例如磷酸三苯酯、磷酸三甲苯酯、磷酸 甲苯酚二苯酯、磷酸辛基二苯酯、磷酸二苯基聯苯酯、磷 酸三辛酯、磷酸三丁酯、磷酸三萘酯、磷酸三（二甲苯） 酯、亞芳基雙（磷酸芳酯）、磷酸三甲苯酯等磷酸酯系可 塑劑、鄰苯二甲酸二乙酯、鄰苯二甲酸二甲氧基乙酯、鄰 苯二甲酸二甲酯、鄰苯二甲酸二辛酯、鄰苯二甲酸二丁酯 以及鄰苯二甲酸二-2-乙基己酯等鄰苯二甲酸酯系可塑劑、 三醋酸甘油酯、三丁酸甘油酯、鄰苯甲酸丁酯甲醯甘醇酸 丁酯（butyl phthalyl butyl glycolate)、鄰苯甲酸乙酯甲 醯甘醇酸乙酯（ethyl phthalyl ethyl glycolate)、鄰苯甲 酸甲酯甲醯甘醇酸乙酯（methyl phthalyl ethyl glycolate )以及鄰苯甲酸丁酯甲醯甘醇酸丁酯（butyl phthalyl -20- 200821122 butyl glycolate )等甘醇酸酯系可塑劑、乙醯基檸檬酸三 丁酯等檸檬酸系可塑劑、二丙二醇苯甲酸酯、三丙二醇二 苯甲酸酯、；1，3_二丙二醇二苯甲酸酯、四乙二醇二苯甲酸 酯、三羥甲基丙烷三乙酸酯、三羥甲基丙烷三苯甲酸酯等 多價醇酯系可塑劑、其他例如偏苯三酸三（2 -乙基己酯） 等。依據需要可倂用上述2種以上的可塑劑。這些的添加 量，由於兼具可塑劑的效果及流出，對熱塑性樹脂而言爲 1 %〜3 0 %較理想。 而且，也可摻入聚酯醚、聚酯-胺酯、聚酯等使用， 因可改良可塑性，所以較理想。 作爲聚酯醚，以8〜12個碳原子的芳香族二羧酸或脂 環式二羧酸（例如對苯二甲酸、異苯二甲酸、萘二甲酸以 及1，4-環己烷二甲酸）、2〜10個碳原子的脂肪族二醇或 脂環式二醇類（例如乙烯二醇、丙烯二醇、1，4-丁二醇、 新戊二醇、1，6-己二醇、1，4-環己烷二甲醇以及1，5-戊二 醇）、醚單元間具有2〜4個碳原子的聚醚二醇（聚四亞 甲基醚二醇，特別是1，4-環己烷二羧酸、1,4-環己烷二甲 醇以及聚四亞甲基醚二醇爲構成要素之聚酯醚）較理想。 聚酯醚的調配量，對主要的樹脂而言爲5〜3 0質量％較理 想。調配量爲該範圍時，可得呈現良好的可塑性之薄膜。 作爲聚酯-胺酯，例如藉由聚酯與二異氰酸酯反應所 得之聚酯-胺酯。具有下述一般式（1)所表示的重複單元 -21 - 200821122 [化l] (1) ⑵Rt={( Nx + Ny)/2-Nz} xd The unevenness of the hysteresis 越 is as small as possible, and is usually within 15 nm, and is preferably 1 Onm or less, more preferably 4 nm or less. The other method is to make the most J light to 90 Rt. -19- 200821122 The resin used in the present invention is cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate fiber. The cellulose, cellulose acetate phthalate and cellulose phthalate are preferred, but are not limited thereto. The degree of substitution of the fluorenyl group of the cellulose ester is at least 1.5 or more, which is preferable because the obtained film has good dimensional stability. The method for measuring the degree of substitution of the thiol group of the cellulose ester can be carried out in accordance with ASTM-D817-91. The molecular weight of the cellulose ester is 50,000 to 300,000 in terms of a number average molecular weight. In particular, 60,000 to 200,000 is preferable because the obtained film has high mechanical strength. In the amorphous thermoplastic resin of the present invention, additives such as a plasticizer, an ultraviolet absorber, an antioxidant, a matting agent, an antistatic agent, a flame retardant, a dye, and an oil agent may be contained for various purposes. As a plasticizer, for example, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, tri-naphthalene phosphate Phosphate-based plasticizers such as esters, tris(xylylene) phosphate, arylene bis(phosphoric acid ester), and tricresyl phosphate, diethyl phthalate, dimethoxyethyl phthalate, Phthalate-based plasticizers such as dimethyl phthalate, dioctyl phthalate, dibutyl phthalate and di-2-ethylhexyl phthalate, triacetin Ester, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, phthalic acid Glycolate-based plasticizer such as methyl phthalyl ethyl glycolate and butyl phthalyl -20-200821122 butyl glycolate Citric acid plasticizer such as tributyl citrate, dipropylene glycol benzoic acid , tripropylene glycol dibenzoate, 1,3_dipropylene glycol dibenzoate, tetraethylene glycol dibenzoate, trimethylolpropane triacetate, trimethylolpropane triblate A polyvalent alcohol ester-based plasticizer such as an acid ester, or other, for example, tris(2-ethylhexyl) trimellitate. The above two or more kinds of plasticizers can be used as needed. The amount of these additions is preferably from 1% to 30% by weight of the thermoplastic resin because of the effect of the plasticizer and the outflow. Further, it may be blended with a polyester ether, a polyester-amine ester, a polyester or the like, and is preferable because it can improve plasticity. As the polyester ether, an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid having 8 to 12 carbon atoms (for example, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid) An aliphatic diol or an alicyclic diol having 2 to 10 carbon atoms (for example, ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol) , 1,4-cyclohexanedimethanol and 1,5-pentanediol), a polyether diol having 2 to 4 carbon atoms between ether units (polytetramethylene ether glycol, especially 1,4) Preferably, cyclohexanedicarboxylic acid, 1,4-cyclohexanedimethanol, and polytetramethylene ether glycol are constituent ether ethers. The blending amount of the polyester ether is preferably 5 to 30% by mass based on the main resin. When the blending amount is in this range, a film exhibiting good plasticity can be obtained. As the polyester-amine ester, for example, a polyester-amine ester obtained by reacting a polyester with a diisocyanate. The repeating unit represented by the following general formula (1) -21 - 200821122 [Chemical Formula 1] (1) (2)
(6) -Qr^^r 般式（1)中，1表示2、3或4(6) -Qr^^r In the general formula (1), 1 means 2, 3 or 4
，n表示i〜10(^r表示構造單元式（2)〜（7)中所示 的任一構造單元。而且，構造單元式（2)中，P表示2〜 作爲構成聚酯-胺酯的聚酯成分，係二醇成分爲乙二 醇、 1，3 -丙二醇 或 1，4-丁二 醇，二鹼基性酸 成分爲 琥珀酸 、戊 二 1 陵或己二 :酸所構成的 兩端具有羥基之 聚酯， 其聚合 度η 爲 1 〜1 00 3聚酯的分子量，特別期望爲 1,000 〜4,500 者。 作爲構成聚酯-胺酯的 二異氰酸酯成分 ，例如 二異氰 酸伸乙酯、三亞甲基二異氰酸酯、四亞甲基二異氰酸酯、 六亞甲基二異氰酸酯等聚亞甲基二異氰酸酯、二異氰酸 對-伸苯酯、二異氰酸伸甲苯酯（tolylene diisocyanate ) -22- 200821122 、p，p’-二苯基甲烷二異氰酸酯、萘二異氰酸酯等芳香 族二異氰酸酯、二異氰酸m -二甲苯酯等。其中，於二異 氰酸伸甲苯酯、二異氰酸m -二甲苯酯、四亞甲基二異氰 酸酯爲聚胺酯化的情況，因與纖維素酯的相溶性佳，所以 較理想。 聚酯-胺酯的分子量爲2,000〜50,000較理想，又 5,000〜1 5,0 00更理想。聚酯-胺酯的合成，係藉由將上述 聚酯與二異氰酸酯混合，在攪拌下加熱之一般的合成法， 可容易得到。而且，原料的聚酯也可藉由一般方法，相當 的二鹼基性酸或這些的烷酯類與二醇類的聚酯化反應或酯 交換反應之熱熔融縮合法，或這些的酸的醯氯與二醇類界 面縮合法的任一種方法，只要適當調整末端基成爲羥基， 可容易地合成。 聚酯-胺酯的調配量，對主要的樹脂而言爲5〜3 0質 量％較理想。調配量爲該範圍時，可得呈現良好的可塑性 之薄膜。 作爲聚酯，其係聚乙二醇與脂肪族二鹼基性酸所構成 的聚酯，其平均分子量爲700〜1 0,000較理想。 聚乙二醇爲一般式 H0-(CH2CH2-0)n-H (式中η爲整數）表示者。η爲4 以下較理想。 而且，所謂脂肪族二鹼基性酸，係指一般式 HOOC-R-COOH (式中R爲脂肪族二價烴基）所表示 的草酸、丙二酸、琥珀酸、己二酸等，碳數爲9以下較理 -23- 200821122 想。 聚酯的合成，係藉由一般方法，上述二鹼基性酸或這 些的烷酯類與二醇類的聚酯化反應或酯交換反應之熱熔融 縮合法，或這些的酸的醯氯與二醇類界面縮合法的任一種 方法，可容易地合成。 聚酯的調配量，對主要的樹脂而言爲5〜30質量％較 理想。調配量爲該範圍時，可得呈現良好的可塑性之薄膜 〇 作爲抗氧化劑’適合爲受阻酚系化合物，其具體例， 例如2,6-二-第3 丁基-ρ·甲酚、季戊四醇-四[3-(3,5-二-第3 丁基-4-羥基苯基）丙酸酯]、三乙二醇-雙[3- (3-第3 丁基-5-甲基-4-羥基苯基）丙酸酯]、1，6 -己二醇-雙[3-( 3, 5-二-第3 丁基-4-羥基苯基）丙酸酯]、2,4-雙（正-辛硫 基）-6-(4-羥基_3,5-二-第3丁基苯胺基）-1，3,5-三嗪（ triazine ) 、2,2 -硫代一* 亞乙基雙[3-(3,5 - 一 第 3 丁基-4- 羥基苯基）丙酸酯]、十八基-3-(3,5 -二-第3 丁基-4_羥基 苯基）丙酸酯、丨，3,5-三甲基-2,4,6-三（3,5-二-第3 丁基· 4-經基苯甲基）苯以及三（3，5 -二-第3 丁基經基苯甲基 )異氰脲酸酯等。特別是2,6-二-第3 丁基-P-甲酚、季戊 四醇-四[3- ( 3,5-二-第3 丁基-4-羥基苯基）丙酸酯]以及 三乙二醇-雙[3- ( 3-第3 丁基-5·甲基-4-羥基苯基）丙酸酯 ]較理想。而且，也可倂用例如N，N'-雙[3 - ( 3，5 -二-第3 丁基-4-羥基苯基）丙醯基]肼等的肼（hydrazine)系金屬 不活性劑、三（2，4 -二-第3 丁基苯基）亞磷酸酯等磷系加 -24- 200821122 工安定劑。這些化合物的添加量，爲了達到其效果，對熱 塑性樹脂而言，以質量比例爲1 Ppm〜1 · 〇 %較理想，；[〇〜 1 0 0 0 p p m特別理想。 於本發明，作爲可使用之紫外線吸收劑，例如氧二苯 甲酮系化合物、苯並三唑系化合物、水楊酸酯系化合物、 二苯甲酮系化合物、氰基丙烯酸酯系化合物、鎳錯鹽系化 合物等，以著色少之苯並三唑系化合物較理想。此外，使 用特開平10- 1 8262 1號公報、特開平8-3 3 75 74號公報記載 之紫外線吸收劑、特開平6- 1 4843 0號公報記載之高分子 紫外線吸收劑較理想。 作爲紫外線吸收劑，從防止偏光子、液晶劣化的觀點 ’波長3 7 Onm以下的紫外線吸收能力佳，且從液晶顯示性 的觀點，波長40 Onm以上的可見光吸收少者較理想。 於本發明，作爲有用的紫外線吸收劑的具體例，例如 2- ( 2’ -羥基- 5’-甲基苯基）苯並三唑、2- ( 2，-羥基- 3，，5，-二第3 丁基苯基）苯並三唑、2- (2' -羥基- 3，-第3 丁基- 5，-甲基苯基）苯並三唑、2- (2，-羥基- 3，，5，-二第 3 丁基苯基 )-5 -氯苯並三唑、2 - ( 2 ’ -羥基-3，- ( 3，，，4 ’，，5，，，6 ’，·四氫鄰苯 二甲醯亞胺基甲基）-5' -甲基苯基）苯並三唑、2,2-亞甲基 雙（4-(1，1，3,3-四甲基丁基）-6-(21^-苯並三唑-2-基） 酚）、2- (2’ -羥基-3，_第3 丁基- 5，-甲基苯基）-5 -氯苯並 三唑、2- ( 2H-苯並三唑-2_基）-6 (直鏈及側鏈十二烷基 )-4 -甲基酚、辛基- 3-[3-第3 丁基-4-羥基- 5-(氯- 2H-苯 並三唑-2-基）苯基]丙酸酯與2-乙基己基3-[3-第3 丁基- -25- 200821122 4-羥基-5- ( 5-氯-2H-苯並三唑-2-基）苯基]丙酸酯的混合 物等，但不限於這些。而且，作爲市售品，可使用其奴賓 (TINUVIN ) 109、 ( TINUVIN ) 171、 ( TINUVIN ) 326 (皆爲千葉（Ciba)特殊化學公司製）較理想。 作爲二苯甲酮系化合物的具體例，例如2,4-二羥基二 苯甲酮、2,2’-二羥基-4-甲氧基二苯甲酮、2-羥基-4-甲氧 基-5-硫二苯甲酮、雙（2-甲氧基-4-羥基-5-苯甲醯基苯基 甲烷）等，但不限於這些。 這些紫外線吸收劑的調配量，對熱塑性樹脂而言爲 0.01〜10質量％的範圍較理想，又0.1〜5質量％更理想 。使用量太少時，有紫外線吸收效果不足的情形，太多時 ，有薄膜的透明性劣化的情形。紫外線吸收劑爲熱安定性 高者較理想。 於本發明，爲了賦予薄膜滑動性，添加微粒子較理想 。作爲本發明所使用的微粒子，只要熔融時具有耐熱性， 無機化合物或有機化合物任一種皆可，例如作爲無機化合 物，以含矽的化合物、二氧化矽、氧化鋁、氧化鉻、碳酸 鈣、滑石、黏土、燒成的高嶺土、燒成的矽酸鈣、水合矽 酸鈣、矽酸鋁、矽酸鎂以及磷酸鈣等較理想，更理想爲含 矽的無機化合物、氧化銷。其中，由於可抑制霧度，使用 二氧化矽特別理想。作爲二氧化矽的具體例，可使用具有 AEROSIL 200V、AEROSIL R972V、AEROSIL R972、R974 、R812、200、3 00、R202 > 0X50、TT600 (以上爲日本 AEROSIL公司製）等商品名之市售品較理想。 -26- 200821122 由本發明所得的光學薄膜，藉由貼合於偏光薄膜的至 少一面，可成爲橢圓偏光板。 偏光薄膜係傳統所使用之例如聚乙烯醇薄膜的可延伸 配向的薄膜，以如碘的二色性染料處理、縱延伸者。偏光 薄膜本身，因不具有充分的強度、耐久性，一般於其兩面 黏著作爲保護膜之無異向性纖維素三乙酸酯薄膜而成爲偏 光板。由本發明所得的光學薄膜，可貼合於上述附有保護 膜之偏光板而製作，也可兼具保護膜，直接與偏光薄膜貼 合而製作。 特別是由本發明所得的光學薄膜，因於寬度方向具有 延遲相位軸，在不裁斷下可與偏光薄膜以長卷彼此貼合， 偏光板的生產性飛快地提升。 偏光板係於其單面或兩面介由感壓性黏著劑層（例如 丙烯酸系感壓性黏著劑層等）層合剝離性薄片之貼合型者 (藉由剝離剝離性薄片，可容易地黏貼於液晶胞等）。 如此所得的偏光板，可使用於各種顯示裝置。特別是 使用無外加電壓時液晶性分子實質上垂直配向之V A模式 的液晶胞之液晶顯示裝置較理想。 〔實施例〕 以下，舉實施例具體地說明本發明，但本發明不限於 這些。 實施例1 -27- 200821122 100質量份 乙酸丙酸纖維素 (乙醯基取代度1.4、丙醯基取代度1 . 3 5 總醯基取代度、數量平均分子量60000) 三羥甲基丙烷三苯甲酸酯（可塑劑） 添加劑（IRGANOX-XP-420/FD) 1 〇質量份 1質量份 (千葉特殊化學公司製） 1 . 5質量份 紫外線吸收劑 Ti928 (千葉特殊化學公司製） 消光劑（平均粒徑0.3 μηα氧化矽微粒子） 0.1質量份 (SeahosterKEP-30:日本觸媒公司製） 此外，乙醯基、丙醯基、丁醯基等的烯基取代度的測 定方法係根據AS TM_D 8 17-96的規定進行測定。 將上述材料的混合物以V型混合機混合3 0分鐘後， 以圖1所示的2軸擠出機（PCM30、池貝公司製）於220 °C使其熔融，製作長度4mm、直徑3mm的圓筒形顆粒。 此時，從擠出機1的入口，與材料同時添加氮氣，使氧氣 濃度降低。 然後’將顆粒供應給裝配T型模頭4之直徑5 0mm的 單軸擠出機（GT-50、公司塑膠工學硏究所製）1，進行製 膜。擠出機1的設定溫度爲2 5 0 °C，T型模頭4爲衣架式 〇 設定流鑄模頭4的溫度，使從T型模頭4出口擠出的 材料之溫度T 1爲2 5 0 °C。將熔融擠出的薄膜，使同時接 -28- 200821122 觸調整溫度爲100 °C之直徑3 5 0mm的鍍鉻鏡面第i冷卻滾 輪5以及接觸滾輪6地，滴落於第1冷卻滾輪5以及接觸 滾輪6所成的間隙。密合於第1冷卻滾輪5的薄膜，使第 1冷卻滾輪5的中心角5 °的圓周部分傳送後，以接觸滾輪 6壓住。對薄膜的寬度1500mm的全面，以〇.39MPa的壓 力接觸。 根據本發明的光學薄膜的製造方法，於接觸滾輪6具 備未圖示之壓力控制單元，傳送薄膜的途中，於寬度方向 騰出既定的間隔設置2台傳送薄膜的遲滯値測定器20，在 線上測定傳送薄膜在寬度方向的2個相異點的遲滯値，來 自該測定器20的遲滯値信號電傳輸給接觸滾輪6的壓力 控制單元，控制單元中，根據該遲滯測定値信號，即時調 整接觸滾輪6的壓力，控制傳送薄膜的遲滯値爲既定的範 圍內。 接觸滾輪6的壓力控制單元中’係根據來自測定器2 0 之遲滯測定値信號，使傳送薄膜的遲滯之最大値與最小値 的差一直爲4nm以下，計算接觸滾輪6對熔融薄膜的冷卻 滾輪5表面的壓力，即時調整接觸滾輪6的壓力。 於該實施例，第1冷卻滾輪5與接觸滾輪6的間隙’ 係藉由氣壓缸的壓力調整，以控制滾輪間的壓力。接觸滾 輪6的壓力控制單元，根據來自該測定器2 0的遲滯値信 號，進行氣壓缸的壓力調整。此處’氣壓缸係使用SMC 公司製氣壓缸MBL-100，即時調整接觸滾輪6的壓力。 而且，該實施例中，作爲在線上測定傳送薄膜的遲滯 -29- 200821122 値之遲滯値測定器20，係使用利用非接觸式光電管之王子 計測機器公司製Kobra-WX150K，該遲滯値測定器20設置 於延伸裝置1 2與捲取裝置1 6之間。而且，藉由遲滯値測 定器20線上所測定之傳送薄膜的遲滯値，係面內方向遲 滯値（R〇 )。 藉由遲滯値測定器20所測定之傳送薄膜的面內方向 遲滯値（Ro ) ，2點之中，左側的最小値（Min )爲 29.7nm，左側的最大値（Max)爲30.6nm，右側的最小値 (Min)爲29.5nm，右側的最大値（Max)爲30.3nm，任 一傳送薄膜的面內方向遲滯値（R〇 )的最大値與最小値的 差爲4nm以下。 被擠壓的薄膜接觸第1冷卻滾輪5的中心角150°的圓 周部分後，依序與第2冷卻滾輪7及第3冷卻滾輪8密接 ，一邊傳送一邊使其冷卻，得到未延伸的纖維素酯系樹脂 薄膜1 〇。 圖1所示的本發明之實施態樣，從第3冷卻滾輪8， 藉由剝離滾輪9剝離之未延伸樹脂薄膜1 〇，經過跳動滾輪 (薄膜張力調整滾輪）11，引導至延伸裝置12，在此薄膜 1 〇進行橫方向（寬度方向）的延伸。藉由該延伸，使薄膜 中的分子配向。 延伸後，薄膜的端部藉由切割器1 3裁斷成製品的寬 度後，藉由壓花環1 4以及背輪1 5所構成的刻痕加工裝置 ，於薄膜兩端部進行刻痕加工（壓花加工），藉由捲取機 16捲取，得到寬度1500mm及長度2600m的纖維素乙酸 -30- 200821122 酯丙酸酯薄膜（原卷）F。使捲取的薄膜F的厚度爲4 0 μπι ，調整擠出量及捲取滾輪的旋轉數。 比較例1 爲了進行比較，與上述實施例1的情況同樣地進行， 與實施例1的情況不同之處在於設置傳送薄膜的遲滯値測 定器2 0，在線上測定2點的傳送薄膜的面內方向遲滯（ R〇 )値，不根據該傳送薄膜的面內方向遲滯（Ro )値，進 行接觸滾輪6的壓力控制。 結果，於該比較例1，由遲滯値測定器2 0所測定的傳 送薄膜的面內方向遲滯（R〇 )値，2點之中，左側的最小 値（Min)爲27.2nm，左側的最大値（Max)爲35.7nm， 右側的最小値（Min )爲28.3nm，右側的最大値（Max ) 爲3 7.2nm，任一傳送薄膜的面內方向遲滯値（R〇 )的最 大値與最小値的差都超過8nm。 如此，根據本發明的實施例1之纖維素乙酸酯丙酸酯 薄膜，薄膜在寬度方向及長度方向內之面內方向遲滯（Ro )値的最大値與最小値之差爲4nm以下，薄膜的遲滯在寬 度方向的均勻性提高，光學特性佳。 實施例2 然後，與上述實施例1的情況同樣地進行，與實施例 1的情況不同之處在於藉由遲滯値測定器2 0線上測定之傳 送薄膜的遲滯値，爲厚度方向遲滯（Rt )値。 -31 - 200821122 結果’由遲滯値測定器20所測定的傳送薄 方向遲滯（Rt )値，2點之中，左側的最小値（ 118.0nm’左側的最大値（Max)爲l20.2nm，右 値（Min )爲1 1 7.3nm，右側的最大値（Max )爲 ’任一傳送薄膜的面內方向遲滯値（Rt )的最大 値的差爲4nm以下。 比較例2 爲了進行比較，與上述實施例2的情況同樣 與實施例2的情況不同之處在於設置傳送薄膜的 定器20，在線上測定2點的傳送薄膜的厚度方向 )値，不根據該傳送薄膜的厚度方向遲滯（Rt ) 接觸滾輪6的壓力控制。 結果，於該比較例2，由遲滯値測定器20所 送薄膜的厚度方向遲滯（Rt )値，2點之中，左 値（Min )爲1 16.4nm，左側的最大値（Max )爲 ，右側的最小値（Min)爲1 14.2nm，右側的最大 )爲122.3 nm，任一傳送薄膜的厚度方向遲滯値 最大値與最小値的差都超過7nm。 如此，根據本發明的實施例2之纖維素乙酸 薄膜，薄膜在寬度方向及長度方向內之厚度方向 )値的最大値與最小値之差爲4nm以下，薄膜的 度方向的均勻性提高，光學特性佳。 膜的厚度 M i η )爲 側的最小 1 1 9.7nm 値與最小 地進行， 遲滯値測 遲滯（Rt 値，進行 測定的傳 側的最小 1 2 3.7 nm 値（M a X (Rt )的 酯丙酸酯 遲滯（Rt 遲滯在寬 -32- 200821122 【圖式簡單說明】 圖1表示實施本發明的光學薄膜的製造方法之裝置之 -實施態樣之槪略流程圖。 【主要元件符號說明】 1 :擠出機 2 :過濾器 3 :靜態混合器 4 :流鑄模頭 5 :第1冷卻滾輪 6 :接觸滾輪 7 :第2冷卻滾輪 8 :第3冷卻滾輪 9 :剝離滾輪 1 0 :未延伸薄膜 1 1 :跳動滾輪（薄膜張力調整滾輪） 1 2 :延伸裝置 13 :切割器 14 :壓花環 1 5 :背輪 1 6 :捲取機 20 :遲滯測定器 F :光學薄膜 -33·n represents i to 10 (^r represents any of the structural units shown in the structural unit formulas (2) to (7). Further, in the structural unit formula (2), P represents 2~ as a constituent polyester-amine ester The polyester component is a glycol component of ethylene glycol, 1, 3-propanediol or 1,4-butanediol, and the dibasic acid component is composed of succinic acid, pentane or diacetyl: acid. A polyester having a hydroxyl group at both ends, the degree of polymerization η is from 1 to 1 00 3 The molecular weight of the polyester is particularly preferably from 1,000 to 4,500. As a diisocyanate component constituting the polyester-amine ester, for example, diisocyanate Polymethylene diisocyanate such as ester, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, p-phenylene diisocyanate, tolylene diisocyanate -22- 200821122, aromatic diisocyanate such as p,p'-diphenylmethane diisocyanate or naphthalene diisocyanate, m-xylylene diisocyanate, etc. Among them, toluene diisocyanate, diiso) M-cylylene cyanate and tetramethylene diisocyanate are polyurethanes In view of the fact that it has good compatibility with cellulose ester, it is preferred. The molecular weight of the polyester-amine ester is preferably 2,000 to 50,000, and more preferably 5,000 to 1,500,000. Synthesis of polyester-amine ester It can be easily obtained by a general synthesis method in which the above polyester is mixed with a diisocyanate and heated under stirring. Moreover, the polyester of the raw material can also be obtained by a general method, a comparable dibasic acid or these. Any one of a method of a polyester melt reaction or a transesterification reaction of a glycol ester or a transesterification reaction, or a method of interfacial condensation of an acid of the above-mentioned anthracene chloride and a glycol, as long as the terminal group is appropriately adjusted to a hydroxyl group The amount of the polyester-amine ester is preferably from 5 to 30% by mass based on the main resin. When the amount is within this range, a film exhibiting good plasticity can be obtained. It is a polyester composed of polyethylene glycol and an aliphatic dibasic acid, and its average molecular weight is preferably 700 to 10,000. Polyethylene glycol is a general formula H0-(CH2CH2-0)nH (wherein η is Integer) is represented by η of 4 or less. The aliphatic dibasic acid refers to oxalic acid, malonic acid, succinic acid, adipic acid, etc. represented by the general formula HOOC-R-COOH (wherein R is an aliphatic divalent hydrocarbon group), and the carbon number is 9 The following is a comparison of -23-200821122. The synthesis of polyester is a general melt-condensation method of the above dibasic acid or the polyesterification or transesterification of these alkyl esters with diols by a general method. Or any of the acid osmium chloride and diol-based interfacial condensation methods can be easily synthesized. The blending amount of the polyester is preferably 5 to 30% by mass based on the main resin. When the blending amount is in this range, a film which exhibits good plasticity can be obtained as an antioxidant, which is suitable as a hindered phenol-based compound, and specific examples thereof include, for example, 2,6-di-butyl ketone and pentaerythritol. Tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4) -hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,4-double (n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine (triazine), 2,2-thio-a* Ethyl bis[3-(3,5-1,3-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-butyl -4- hydroxybenzene) Propionate, hydrazine, 3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-ylbenzyl)benzene and tris(3,5 -di-tert-butylbenzylaminomethylisocyanurate or the like. In particular, 2,6-di-tert-butyl-P-cresol, pentaerythritol-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] and triethylene Alcohol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate] is preferred. Further, a hydrazine-based metal inactive agent such as N,N'-bis[3 -(3,5-di-tert-butyl-4-hydroxyphenyl)propanyl]hydrazine may also be used. Phosphate such as tris(2,4-di-tert-butylphenyl) phosphite is added to -24-21122122. In order to achieve the effect of the addition amount of these compounds, it is preferable that the thermoplastic resin has a mass ratio of 1 Ppm to 1 · 〇 %; [〇~1 0 0 0 p p m is particularly preferable. In the present invention, as the ultraviolet absorber which can be used, for example, an oxybenzophenone-based compound, a benzotriazole-based compound, a salicylate-based compound, a benzophenone-based compound, a cyanoacrylate-based compound, and nickel are used. A salt-based compound or the like is preferably a benzotriazole-based compound having less coloration. Further, it is preferable to use the ultraviolet absorber described in the Japanese Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. From the viewpoint of preventing deterioration of polarizers and liquid crystals, the ultraviolet ray absorbing ability of the wavelength of 3 7 Onm or less is preferable, and the absorption of visible light having a wavelength of 40 Onm or more is preferable from the viewpoint of liquid crystal display properties. In the present invention, specific examples of useful ultraviolet absorbers include, for example, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2,-hydroxy-3,5,- Di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3,-tert-butyl-5,-methylphenyl)benzotriazole, 2-(2,-hydroxy- 3,5,-di-3 butylphenyl)-5-chlorobenzotriazole, 2 - ( 2 '-hydroxy-3,- ( 3,,, 4 ',, 5,,, 6 ', · Tetrahydrophthalic acid imidomethyl)-5'-methylphenyl)benzotriazole, 2,2-methylenebis(4-(1,1,3,3-tetramethyl) Butyl)-6-(21^-benzotriazol-2-yl)phenol), 2-(2'-hydroxy-3,_3 butyl-5,-methylphenyl)-5- Chlorobenzotriazole, 2-( 2H-benzotriazol-2-yl)-6 (linear and side chain dodecyl)-4-methylphenol, octyl-3- [3- 3 Butyl-4-hydroxy-5-(chloro-2H-benzotriazol-2-yl)phenyl]propionate with 2-ethylhexyl 3-[3- 3 butyl- -25- 200821122 4 a mixture of -hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate, etc., but is not limited thereto. Further, as a commercially available product, it is preferable to use a TINUVIN 109, a (TINUVIN) 171, and a (TINUVIN) 326 (all manufactured by Chiba Special Chemical Co., Ltd.). Specific examples of the benzophenone-based compound include, for example, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and 2-hydroxy-4-methoxy group. -5-thiobenzophenone, bis(2-methoxy-4-hydroxy-5-benzimidylphenylmethane), and the like, but is not limited thereto. The amount of the ultraviolet absorber to be added is preferably 0.01 to 10% by mass in terms of the thermoplastic resin, and more preferably 0.1 to 5% by mass. When the amount used is too small, there is a case where the ultraviolet absorbing effect is insufficient, and when there is too much, the transparency of the film is deteriorated. Ultraviolet absorbers are preferred for those with high thermal stability. In the present invention, in order to impart slidability to the film, it is preferred to add fine particles. The fine particles used in the present invention may be any one of an inorganic compound or an organic compound as long as it has heat resistance upon melting, for example, as an inorganic compound, a cerium-containing compound, cerium oxide, aluminum oxide, chromium oxide, calcium carbonate, or talc. Clay, calcined kaolin, calcined calcium citrate, hydrated calcium citrate, aluminum citrate, magnesium citrate and calcium phosphate are preferred, and more preferably an inorganic compound containing cerium or an oxidized pin. Among them, cerium oxide is particularly preferable because it can suppress haze. As a specific example of cerium oxide, a commercial product having a trade name such as AEROSIL 200V, AEROSIL R972V, AEROSIL R972, R974, R812, 200, 300, R202 > 0X50, TT600 (above, Japan AEROSIL) can be used. More ideal. -26- 200821122 The optical film obtained by the present invention can be an elliptically polarizing plate by being bonded to at least one side of the polarizing film. The polarizing film is an extendable film of a conventionally used polyvinyl alcohol film, which is treated with a dichroic dye such as iodine and longitudinally stretched. The polarizing film itself is a polarizing plate because it does not have sufficient strength and durability, and generally has an anisotropic cellulose triacetate film which is bonded to the protective film on both sides. The optical film obtained by the present invention can be produced by laminating the polarizing plate with the protective film described above, or can be formed by directly bonding a polarizing film. In particular, the optical film obtained by the present invention has a retardation phase axis in the width direction, and can be bonded to the polarizing film in a long roll without cutting, and the productivity of the polarizing plate is rapidly improved. The polarizing plate is a laminated type in which a peelable sheet is laminated on one or both sides via a pressure-sensitive adhesive layer (for example, an acrylic pressure-sensitive adhesive layer) (by peeling off the peelable sheet, it is easy to Adhered to the liquid crystal cell, etc.). The polarizing plate thus obtained can be used for various display devices. In particular, it is preferable to use a liquid crystal display device of a liquid crystal cell of a V A mode in which a liquid crystal molecule is substantially vertically aligned without an applied voltage. [Examples] Hereinafter, the present invention will be specifically described by way of Examples, but the present invention is not limited thereto. Example 1 -27- 200821122 100 parts by mass of cellulose acetate propionate (acetamyl substitution degree 1.4, propyl ketone substitution degree 1. 3 5 total thiol substitution degree, number average molecular weight 60000) Trimethylolpropane triphenyl Formate (plasticizer) Additive (IRGANOX-XP-420/FD) 1 〇 parts by mass of 1 part by mass (manufactured by Chiba Specialty Chemical Co., Ltd.) 1. 5 parts by mass of UV absorber Ti928 (manufactured by Chiba Specialty Chemical Co., Ltd.) Matting agent ( 0.1 μηη 矽 矽 矽 矽 0.1 0.1 Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea Sea The measurement of 96 is carried out. The mixture of the above materials was mixed in a V-type mixer for 30 minutes, and then melted at 220 ° C in a 2-axis extruder (PCM30, manufactured by Ikebukuro Co., Ltd.) shown in Fig. 1 to prepare a circle having a length of 4 mm and a diameter of 3 mm. Tubular particles. At this time, nitrogen gas was added from the inlet of the extruder 1 to the material to lower the oxygen concentration. Then, the pellets were supplied to a single-axis extruder (GT-50, manufactured by the company's plastics engineering research institute) 1 of a diameter of 50 mm in which the T-die 4 was assembled, and film formation was carried out. The set temperature of the extruder 1 is 2500 ° C, and the T-die 4 is a coat hanger type which sets the temperature of the casting die 4 so that the temperature T 1 of the material extruded from the outlet of the T-die 4 is 2 5 . 0 °C. The melt-extruded film is immersed in the first cooling roller 5 and contacted by a chrome-plated mirror i-th cooling roller 5 and a contact roller 6 which are simultaneously adjusted to a temperature of 100 ° C and a contact temperature of 100 ° C. The gap formed by the roller 6. The film which is in close contact with the first cooling roller 5 is conveyed by the contact roller 6 after the circumferential portion of the first cooling roller 5 having a central angle of 5° is conveyed. The film was made to have a total width of 1500 mm and was brought into contact with a pressure of 〇39 MPa. According to the method for producing an optical film of the present invention, the contact roller 6 is provided with a pressure control unit (not shown), and a hysteresis detector 20 for arranging two transport films at a predetermined interval in the width direction is transported on the line, on the line. The hysteresis 2 of the two different points in the width direction of the transport film is measured, the hysteresis signal from the measuring device 20 is electrically transmitted to the pressure control unit of the contact roller 6, and the control unit adjusts the contact according to the hysteresis signal. The pressure of the roller 6 controls the hysteresis of the transport film to be within a predetermined range. In the pressure control unit of the contact roller 6, the difference between the maximum 値 and the minimum 迟 of the hysteresis of the transport film is 4 nm or less based on the hysteresis measurement signal from the measuring device 20, and the cooling roller of the contact roller 6 for the molten film is calculated. 5 The pressure on the surface instantly adjusts the pressure of the contact roller 6. In this embodiment, the gap between the first cooling roller 5 and the contact roller 6 is adjusted by the pressure of the pneumatic cylinder to control the pressure between the rollers. The pressure control unit that contacts the roller 6 performs pressure adjustment of the pneumatic cylinder based on the hysteresis signal from the measuring device 20. Here, the pneumatic cylinder uses the pneumatic cylinder MBL-100 manufactured by SMC to instantly adjust the pressure of the contact roller 6. Further, in this embodiment, as the hysteresis 値 measuring device 20 for measuring the hysteresis of the transport film on the line -29-200821122, the Kobra-WX150K manufactured by Oji Scientific Instruments Co., Ltd. using the non-contact photocell is used, and the hysteresis sputum measuring device 20 is used. It is disposed between the extension device 12 and the winding device 16. Further, the hysteresis 传送 of the transport film measured on the line of the hysteresis 値 20 20 is delayed in the in-plane direction 〇 (R 〇 ). The in-plane retardation Ro(Ro ) of the transport film measured by the hysteresis enthalometer 20, among the two points, the minimum 値 (Min) on the left side is 29.7 nm, and the maximum 値 (Max) on the left side is 30.6 nm, on the right side. The minimum 値 (Min) is 29.5 nm, and the maximum 値 (Max) on the right side is 30.3 nm, and the difference between the maximum 値 and the minimum 迟 of the in-plane retardation 値(R〇) of any of the transport films is 4 nm or less. The pressed film contacts the circumferential portion of the first cooling roller 5 at a central angle of 150°, and then closely adheres to the second cooling roller 7 and the third cooling roller 8 to be cooled while being conveyed, thereby obtaining unstretched cellulose. The ester resin film 1 〇. In the embodiment of the present invention shown in FIG. 1, the unstretched resin film 1 剥离 peeled off by the peeling roller 9 from the third cooling roller 8 is guided to the extension device 12 via the dancer roller (film tension adjusting roller) 11. In this film, 1 〇 is extended in the lateral direction (width direction). By this extension, the molecules in the film are aligned. After the extension, the end of the film is cut into the width of the product by the cutter 13, and then the scoring processing device formed by the embossing ring 14 and the back wheel 15 is used for scoring at both ends of the film (pressure The flower processing) was taken up by a coiler 16 to obtain a cellulose acetate-30-200821122 ester propionate film (original roll) F having a width of 1500 mm and a length of 2600 m. The thickness of the wound film F was set to 40 μm, and the amount of extrusion and the number of rotations of the take-up reel were adjusted. Comparative Example 1 In order to carry out the comparison, the same procedure as in the first embodiment was carried out, and the difference from the case of the first embodiment was that the hysteresis 値 measuring device 20 for transporting the film was provided, and the in-plane of the two-point transport film was measured on the line. The direction retardation (R〇) 値 does not control the pressure of the contact roller 6 based on the in-plane retardation (Ro ) 该 of the transport film. As a result, in the comparative example 1, the in-plane retardation (R〇) 传送 of the transport film measured by the hysteresis enthalpy measuring device 20, among the two points, the minimum 値 (Min) on the left side was 27.2 nm, and the maximum on the left side.値(Max) is 35.7nm, the smallest 値 (Min) on the right side is 28.3nm, and the maximum 値(Max) on the right side is 3 7.2nm. The maximum 値 and minimum of the in-plane retardation 〇(R〇) of any transport film The difference in enthalpy is more than 8 nm. As described above, according to the cellulose acetate propionate film of Example 1 of the present invention, the difference between the maximum 値 and the minimum 迟 of the retardation (Ro ) 面 in the in-plane direction in the width direction and the longitudinal direction is 4 nm or less. The hysteresis of the hysteresis is improved in the width direction and the optical characteristics are good. Example 2 Then, in the same manner as in the case of the above-described first embodiment, the difference from the case of the first embodiment is that the retardation 传送 of the transport film measured by the hysteresis 値 measuring device 20 line is the thickness direction retardation (Rt). value. -31 - 200821122 Result 'Transfer thin direction hysteresis (Rt) 测定 measured by hysteresis 値 finder 20, among the 2 points, the smallest 左侧 on the left side (118.0 nm' maximum 値 (Max) on the left side is l20.2 nm, right値 (Min) is 1 1 7.3 nm, and the maximum 値 (Max ) on the right side is 'the difference in the maximum 値 of the in-plane retardation 値(Rt ) of any of the transport films is 4 nm or less. Comparative Example 2 For comparison, The case of the second embodiment is also different from the case of the second embodiment in that the fixed film 20 for transporting the film is provided, and the thickness direction of the transfer film at two points is measured on the line), and the retardation (Rt) is not based on the thickness direction of the transfer film. Pressure control of the contact roller 6. As a result, in the comparative example 2, the retardation (Rt) 厚度 in the thickness direction of the film fed by the hysteresis enthalometer 20, among the two points, the left 値 (Min) was 1.16 nm, and the left maximum 値 (Max ) was The minimum 値 (Min) on the right side is 1 14.2 nm, and the maximum on the right side is 122.3 nm. The retardation in the thickness direction of any of the transport films 差 the difference between the maximum 値 and the minimum 都 exceeds 7 nm. As described above, according to the cellulose acetate film of Example 2 of the present invention, the difference between the maximum 値 and the minimum 値 of the 在 in the thickness direction of the film in the width direction and the longitudinal direction is 4 nm or less, and the uniformity of the film in the directional direction is improved, and the optical Good characteristics. The thickness of the film M i η ) is the minimum of 1 9.7 nm 侧 on the side and is minimally performed, hysteresis hysteresis (Rt 値, the minimum of 1 2 3.7 nm 値 (M a X (Rt )) of the measured side Propionate Hysteresis (Rt Hysteresis in Width -32 - 200821122) BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic flow chart showing an embodiment of an apparatus for producing an optical film of the present invention. 1 : extruder 2 : filter 3 : static mixer 4 : cast molding die 5 : first cooling roller 6 : contact roller 7 : second cooling roller 8 : third cooling roller 9 : peeling roller 1 0 : not extended Film 1 1 : Jumping roller (film tension adjusting roller) 1 2 : Extension device 13 : Cutter 14 : Embossing ring 15 : Back wheel 1 6 : Coiler 20 : Hysteresis measuring device F : Optical film - 33 ·