200846179 九、發明說明： 【發明所屬之技術領域】 本發明係有關於一種使用於大畫面且高亮度的液晶顯 示器的背光板模組、照明裝置等之光擴散性薄膜。更詳言 之，係有關於一種表面光擴散性聚酯薄膜，其兼具光擴散 性及光線透射率、且伴隨溫度變化之所產生捲曲較小。 【先前技術】 近年來，液晶顯示器的技術進步顯著，被廣泛地使用 於個人電腦或電視、行動電話等的顯示裝置。該等液晶顯 示器因爲液晶顯示模組單獨並未具有發光功能，所以在其 背面設置背光模組而能夠進行顯示。 背光板模組有各種方式，大致可分成2種。通常最多 的方式係正下方型方式，係在光面的內側具有光源之方 式。該方式因爲能將多數根冷陰極線管等的光源配置在照 光面的正下方，所以能夠得到極高的亮度，又，具有光損 失小的特徵。因此，大量地被使用於大型液晶T V等大型 且必須高亮度之液晶顯示器。 另一種方式係所謂端面照光（edge light)型方式，光源 係配置於照光面以外，係在配置於照光面之由透明丙烯酸 樹脂板等所構成的導光板的一邊或二邊，黏附螢光燈（多半 是冷陰極放電管）等大略線狀發光體，並設置由反射體所構 成的燈罩來將光線導入導光板內之方式。該方式具有消耗 電子小、能夠小型、薄型化之特徵。因此，被廣泛地使用 於筆記型個人電腦等小型顯示器等、特別是要求薄型化、 200846179 輕量化之用途。 端面照光型背光板模組的導光板被要求的功能有將從 端部入射的光線往前方發送的功能、及將所發送的光線往 液晶顯示元件側射出之功能。前者的功能係取決於所使用 材料及界面反射特性。又，後者的功能係取決於用以避免 全光射條件之導光板表面的形狀。該導光板表面的形狀之 形成方法已知有在導光板表面賦予白色的擴散材之方法； 及在導光板表面賦予雙凸型透鏡或稜鏡的菲湼耳形狀之方 法。但是，從具有此等表面形狀之導光板所射出的光線， 會有起因於其形狀之不均勻分布。因此，爲了得到高品質 的影像而設法在導光板上設置光擴散性薄膜，使從導光板 所射出的光線擴散、散射，來使照光面的亮度均勻。 此等背光板模組爲更提高其正面亮度，爲了提升其正 面亮度，會有使用稱爲稜鏡薄片、或透鏡薄片之具有聚光 功能的薄片來使透射擴散性薄膜的光線盡可能聚集於正面 方向之情形。在該薄片的表面有多數稜鏡狀或波長、角錐 狀等微小的凹凸排列著，使透射擴散性薄膜的射出光線聚 集於正面，來提升照光面的亮度。此種稜鏡薄片係在前述 擴散性薄膜的表面側配設1片或重疊2片而使用。 而且，爲了使配設上述棱鏡薄片所產生的亮度不均或 稜鏡薄片的缺陷不顯著化（提高遮蔽性），亦有在棱鏡薄片 的表面側配設光擴散性薄膜之情形。 如上述的背光板模組所使用的光擴散性薄膜，係以在 雙軸拉伸聚酯薄膜的表面塗布由含有微粒子的透明樹脂所 200846179 構成之光擴散層而得到者（例如參照專利文獻1 專利文獻1 :特開平6-59 1 08號公報 專利文獻2 :特許第3698978號說明書 但是，該方法由於必須在基材薄膜的一面 設置光擴散層，而會有因光擴散層與基材薄膜 數不同，光擴散性薄膜成爲雙金屬狀的結構、 加熱而產生捲曲的問題。該問題特別是在近年 TV等採用大型且必須高亮度的正下方型背光 晶顯示器，逐漸成爲重要問題。因爲光擴散性 積化時，捲曲變爲越顯著，而且，因爲液晶顯 度化時’光源的消耗電力、亦即背光板模組的蜜 爲了解決此問題，必須謀求消除雙金屬狀 材薄膜的光擴散層表面，係形有數微米至數十 硬塗層（非光擴散性層），係採用夾住光擴散層 線膨脹應力平衡之對策。 但是，前述硬塗層的厚度本來係不需要的 性薄膜增加不需要的厚度時，會成爲造成製造 原因。而且，使表背的線膨脹應力平衡的對策友 在如上述之大畫面、高亮度顯示器，只能夠得 效果。 又，近年來，爲了使背光板模組組件數目 程的簡略化、低成本化之目的，亦進行許多將 膜與其他光學功能性薄膜整體化之硏討。 例如有揭示一種稜鏡薄片（參照專利文獻： 、2 )爲主流。 藉由塗布來 的線膨脹係 或是容易因 來大型液晶 板模組之液 薄膜越大面 示器越高亮 丨熱量越大。 。通常在基 微米厚度之 的兩面來使 ，使光擴散 成本增加的 R有其限度， 到不充分的 減少、或製 光擴散性薄 5) ’其特徵係 200846179 在具有第1面及第2面的二主表面之板狀透光性基材的第 1面側形成稜鏡列，並在上述基材的第2面側形成含有多 數透光性顆粒之光擴散層。 又，有揭示一種液晶顯示裝置用透鏡薄片（參照專利文 獻4)，其特徵係層積光擴散層及稜鏡形狀形成層之至少2 層而構成，該光擴散層係由混煉光擴散劑而成的熱塑性樹 脂層所構成的，而該稜鏡形狀形成層係在未混煉光擴散劑 之熱塑性樹脂層的表面形成稜鏡形狀而成。 ® 而且，有揭示一種稜鏡薄片用光散射性雙軸拉伸聚酯 薄膜（參照專利文獻5)，係藉由在薄膜內部所添加的光散射 劑及在其周圍所產生的空隙來賦予光擴散性。 專利文獻3 :特開平9-281310號公報 專利文獻4 :特許第3 73 22 5 3號說明書 專利文獻5 :特開2005 - 1 8 1 648號公報 但是專利文獻3所揭示的方法，因爲具有透鏡作用之 透光性顆粒係設置在光線的入射面側，會有所謂逆擴散狀 ^ 態而致使正面亮度大幅度地下降之問題。因此，該方法無 法賦予充分的亮度及光擴散性。 另一方面，在專利文獻4或專利文獻5所揭示的方法， 因爲係藉由基材內部的光散射物質來賦予光擴散性，會有 一部分的入射光在後方產生散射而致使光線透射率降低之 問題。 又，近年來，進行許多使兼具優良的耐熱性、機械強 度、厚度均勻性之雙軸拉伸聚酯薄膜本身賦予光擴散性之 200846179 硏究。使本質上係單一材料所構成的聚酯薄膜具有光擴散 性’能夠解決前述加熱捲曲的問題、或亦能夠打開使擴散 薄片與稜鏡薄片功能整體化的途徑，其工業上的價値係非 常大的。 但是’以往所提案使雙軸拉伸聚酯薄膜本身具有光擴 散性之試驗’任一者都會損害雙軸拉伸聚酯薄膜本身本來 所具有的某種特長（耐熱性、機械強度等），或是損害光線 透射率或光擴散性光擴散性薄膜所應具備的特性，而無法 達成實用化。 例如’在前述專利文獻5所揭示的薄膜，推斷具有優 良的耐熱性、機械強度、優良的厚度均勻性之雙軸拉伸聚 酯薄膜原本所具有特長，但是因爲光擴散性係藉由在層的 內部所存在的氣泡來賦予，會有光線透射率低落的問題。 在薄膜的雙軸拉伸製程所產生的氣泡（空隙）相對於薄膜表 面係具有平行的平板狀形態。因此，作爲光擴散性薄膜用 於背光板模組時，從照光面所射出的光線，多半往後方散 射，致使光線透射率受到損害。實際上，如實施例所示之 總光線透射率最局者亦只有8 5 . 3 %。 又，有揭示一種積層光擴散性薄膜（參照專利文獻6)， 係由內部光擴散性薄膜及至少在一面層積而成的PET薄膜 所構成，該內部光擴散性薄膜之構成含有微粒子的光擴散 層之聚酯樹脂，係使用在聚對酞酸乙二酯（PET)使25莫耳％ 異對酞酸成分進行共聚合而成的非晶性聚酯而成。 專利文獻6 :特開200 1 -2725 08號公報 200846179 在上述方法，因爲顧慮到空隙的消滅，所以能夠改良 光線透射率。但是，即便在該方法，就光擴散性係藉由薄 膜內部的光散射來賦予而言係相同的，仍然無法避免伴隨 著入射光往後方散射而造成光線透射率的低落。 又，專利文獻6的薄膜時，基材層的構成樹脂（pet同 元聚合物）與光擴散層的構成樹脂（非晶性聚酯）的結晶性顯 著不同。結果所得到的雙軸拉伸薄膜本身成爲雙金屬狀結 構，雙軸拉伸薄膜本身因加熱容易產生捲曲。因此，在後 ^ 加工製程，會有因熱處理或液晶顯示器的使用環境（溫度） 而產生捲曲之情形。 又，有揭示一種薄膜（參照專利文獻7〜1 3)，係以光擴 散性薄膜作爲中間層，並在其兩面層積結晶性聚酯樹脂層 而成，該光擴散性薄膜係以熔點爲2 1 0°C以下、或非晶性 的聚酯作爲構成樹脂，並調配由對該構成樹脂非相溶的粒 子或熱塑性樹脂所構成的光擴散性添加劑而成。 專利文獻7 :特開200 1 -3 24606號公報 專利文獻8 :特開2002- 1 625 08號公報 專利文獻9 :特開2002- 1 820 1 3號公報 專利文獻10 :特開2002- 1 96 1 1 3號公報 專利文獻11 :特開2002-3 72606號公報 專利文獻12:特開2004-2 1 943 8號公報 專利文獻13 :特開2004-3 545 5 8號公報 此等方法係因爲薄膜結構成爲表背對象’而對非對稱 結構所產生的捲曲能夠得到某種程度的改善。但是’在光 -10- 200846179 擴散性中間層與表面層之間，結晶性的重大差異並沒有改 變，由於若干層厚度變動或表背的物性變動，內部存在有 溫度變化時會有平面性產生顯著變差之問題。 又，因爲該等方法時薄膜的大部分係由非晶性、或顯 著缺乏結晶性的聚酯所構成，無法得到雙軸拉伸薄膜本來 優良的耐熱性、機械強度及厚度均勻性。 又，有揭示一種雙軸拉伸聚對酞酸乙二酯薄膜（參照專 利文獻1 4)，係調配特定粒徑的球狀或凸透鏡狀的粒子而 •成。 專利文獻14:特開2002-3 789 8號公報 在專利文獻1 4，於實施例揭示一種薄膜，係使用聚對 酞酸乙二酯作爲聚酯的原料，且具有88%的總光線透射率 及68%的擴散透射率。而且，揭示一種具有85 %的總光線 透射率及63%的擴散透射率之薄膜。但是，該等薄膜的耐 熱性、機械強度及厚度精確度等基本的特性係沒有任何揭 示，亦完全無法認定能夠得到雙軸拉伸聚對酞酸乙二酯本 ^ 來的特徵之耐熱性 '、機械強度及高厚度精確度之可能性。 這是因爲該等薄膜儘管係藉由將厚度200微米的未拉 伸薄膜往縱、橫兩方向各拉伸3 · 0倍、亦即以面積倍率9 . 〇 倍拉伸而得到的薄膜，其厚度爲5 0微米，以拉伸前後的厚 度比率來計算之實際面積拉伸倍率只有4.0倍。亦即，認 爲由於縱拉伸時所產生的寬度收縮、或是橫拉伸時所產生 的拉伸倍率分布、且因熱處理時的尺寸變化等的影響，拉 伸設備的設定倍率與實際的拉伸倍率顯著地背離掉。而 -11- 200846179 且，實際的面積拉伸倍率爲4倍左右的拉伸，即便能夠得 到優良的光線透射率，究竟是不可能達成雙軸拉伸薄膜本 來特徵之耐熱性、機械強度及高厚度精確度。 【發明內容】 · 發明所欲解決之課題 如上述，雙金屬狀的薄膜基材係隨著液晶顯示器用背 光板模組的大型化、高輸出功率化，容易產生捲曲之問題 逐漸地顯著存在化，爲了解決上述問題，以使用實際拉伸 ® 薄膜本身而不使用離線塗布的方法爲佳（專利文獻1、2)。 但是，使雙軸拉伸薄膜本身具有光擴散性之方法，無法避 免光擴散粒子產生空隙，會有總光線透射率降低之問題（專 利文獻3、4、5 )。避免產生空隙的方法，先前所進行之變 更樹脂性狀或拉伸條件並無法解決捲曲的問題（專利文獻 6)，或是會有薄膜的力學強度低落的問題（專利文獻7-14)。 亦即，因爲雙軸拉伸薄膜的力學特性與光學特性具有矛盾 (antinomy)的關係，無法得到任一者都能夠滿足的特性之薄 • 膜。因此，在綜合品質方面，無法比得上藉由後加工來對 透明基材薄膜賦予光擴散層之先前的方法，上述方法尙無 法達成實用化。 本發明的目的係提供一種表面光擴散性聚酯薄膜，具 有雙軸拉伸聚酯薄膜本來優良的耐熱性、機械強度及厚度 精確度等，且兼具總光線透射率及光擴散性，而且能夠抑 制來自雙金屬狀結構所產生的加熱捲曲。 解決課題之手段 -12- 200846179 能夠解決上述課題之本發明的表面光擴散性聚酯薄膜 係由以下構成。 亦即，本發明之如申請專利範圍第1項之發明的構 成，係一種由雙軸配向聚酯薄膜所構成之光擴散性聚酯薄 膜，其特徵係滿足下述必要條件（1)〜（5)， (1 )具有支撐層及光擴散層，該支撐層係由結晶性同元聚 酯、或含有共聚合成分之結晶性聚酯所構成；而該光擴散 層係在該支撐層的至少一面藉由共擠壓法層積而成，且係 ® 由50〜99質量份含有熔點爲23 5〜2 5 5 °C的共聚合成分之 結晶性聚酯及與該聚酯爲非相溶性的1〜5 0質量份添加劑 之調配組成物所構成； (2) 下述式所定義之薄膜的面配向係數ΔΡ爲〇.〇8〜0.16， △ P = (nx + ny)/2-nz 在此，nx、ny、nz係各自表示長度方向的折射率、寬 度方向的折射率及厚度方向的折射率； (3) 表面霧度爲15%以上； ^ (4)內部霧度係小於表面霧度；及 (5)在150 °C之尺寸變化率係縱向及橫向都是3%以下、拉伸 強度係縱向及橫向都是l〇〇MPa以上。 如申請專利範圍第2項之發明的構成係如申請專利範 圍第1項之發明，其中總光線透射率爲86%以上、且在梳 子寬度爲2毫米之影像鮮明度爲4 0 %以下。 如申請專利範圍第3項之發明的構成係如申請專利範 圍第1項之發明，其中在前述光擴散層的表面具有塗布 -13- .200846179 層，該塗布層係在薄膜的拉伸、配向完成前設置而成且以 共聚合聚酯樹脂、聚胺基甲酸酯系樹脂、或是丙烯酸樹脂 之至少1種以上作爲主成分。 如申請專利範圍第4項之發明的構成係如申請專利範 圍第1項之發明，其中在前述光擴散層側及支撐層側之雙 方的面，具有以共聚合聚酯樹脂、聚胺基甲酸酯系樹脂、 或是丙烯酸樹脂之至少1種以上作爲主成分之塗布層。 如申請專利範圍第5項之發明的構成，如申請專利範 ® 圍第1項之表面光擴散性聚酯薄膜係稜鏡薄片用，係在光 擴散層相反面，具有以共聚合聚酯樹脂、聚胺基甲酸酯系 樹脂、或是丙烯酸樹脂之至少1種以上作爲主成分之塗布 層。 發明之效果 因爲本發明的表面光擴散性聚酯薄膜係由支撐層及光 擴散層任一者都是以結晶性聚酯爲主原料之多層結構所構 _ 成，能夠抑制來自雙金屬狀結構之產生力日熱捲曲，同時具 有雙軸拉伸聚酯薄膜本來優良的耐熱性、機械強度及厚度 精確度。 又，因爲本發明的表面光擴散性聚酯薄膜係以含有共 聚合成分之結晶性聚酯作爲光擴散層的主原料，而且因爲 將薄膜整體的面配向係數控制在特定範圍內，在添加於光 擴散層之非相溶性的添加劑的周圍，實質上不會產生空 隙’且在光擴散層具有凹凸結構。因此，兼具優良的表面 光擴散性及高光線透射率。 -14- 200846179 【實施方式】 本發明係提供一種表面光擴散性聚酯薄膜，能夠抑制 因加熱所產生的翹曲，且具有雙軸拉伸聚酯薄膜本來優良 的力學特性，而且兼具總光線透射率及光擴散性。爲了謀 求兼具上述特性’本發明者等特別著眼於薄膜的面配向係 數與內部霧度及表面霧度的關係，進行專心硏討。結果發 現藉由採用下述（1)〜（7)所敘述的手段，能夠兼具此種矛盾 (anti no my)的特性，而完成了本發明。因此，首先說明此等 ^ 達成手段的特徵。又，爲了兼具上述矛盾的特性，認爲只 有下述（1)〜（7)的手段內的特定任一種並無法有效地貢 獻，必須是組合使用（1)〜（7)的手段才能夠兼具上述矛盾的 特性。 (1) 光擴散層的樹脂熔點的控制 (2) 熔點差異的控制 (3) 光擴散層的積層構成的控制 (4) 光擴散層的厚度控制 ^ (5)光擴散層構成樹脂的固有黏度的控制 (6) 基材聚合物與非相溶樹脂的熔融黏度差異的控制 (7) 拉伸溫度與熱處理溫度條件的控制 (1)光擴散層（B)之樹脂熔點的控制 本發明的表面光擴散性聚酯薄膜具有由結晶性同元聚 酯、或含有共聚合成分之結晶性聚酯所構成的支撐層（A)， 且具有由含有共聚合成分之結晶性聚酯與該非相溶性的添 加劑的調配組成物所構成的光擴散層（B)。在此，結晶性聚 .200846179 酯/結晶性同元聚酯係指具有熔點之聚酯/同元聚酯。熔點 係指差示掃描熱量測定（DSC)的一次升溫時所檢測出之熔 解時的吸熱尖峰溫度。使用差示掃描熱量計測定時，聚酯/ 同元聚酯能夠被觀測到作爲熔點之明顯的結晶熔解熱尖峰 時’係含有結晶性聚酯/結晶性同元聚酯。 從薄膜的耐熱性、機械強度、厚度精確度而言，樹脂 的熔點以較高爲佳。但是樹脂的熔點高時，因爲伴隨拉伸 時所產生的拉伸應力增加，在樹脂中若有非相溶粒子時容 ^ 易產生空隙（空洞），致使總光線透射率降低。空隙的產生 容易性亦受到後述的拉伸條件影響，但與所製造的薄膜之 面配向係數有強烈的關聯性。面配向係數係表示在拉伸後 的薄膜所形成高分子鏈的配向狀態，雖然此種配向狀態越 高，力學強度越強，但是在薄膜內亦產生許多空隙。爲了 使薄膜的面配向係數降低，來抑制空隙的產生，構成光擴 散層（B)之樹脂的熔點以控制在一定範圍內爲佳。含有構成 0 光擴散層（B)的共聚合成分之結晶性聚酯的熔點的下限以 2 3 5 °C爲佳，以2 4 0 °C爲更佳。熔點若在2 3 5 °C以上時，能 夠得到可以發揮較佳耐熱性、機械強度及厚度精確度程度 之配向係數。又，含有構成光擴散層（B)的共聚合成分之 結晶性聚酯的熔點的上限以2 5 5 °C爲佳。熔點若在2 5 5 °C以 下時’因爲能夠抑制在光擴散層（B)內產生空隙，乃是較佳。 (2)熔點差異的控制 本發明的表面光擴散性聚酯薄膜具有由結晶性同元聚 酯或含有共聚合成分之結晶性聚酯所構成的支撐層（A)。爲 -16- ,200846179 了得到作爲薄膜之規定的耐熱性、機械強度及厚度精確 度，構成支撐層（A)之結晶性聚酯/結晶性同元聚酯的熔點 係較高爲佳。但是構成支撐層（A)及光擴散層（B)的2層之 樹脂的熔點大時，容易產生起因於雙金屬狀結構之捲曲。 因此，構成支撐層（A)之結晶性聚酯/結晶性同元聚酯與構 成光擴散層（B)之結晶性聚酯的熔點差異以25 °C以內爲 佳，以20°C以內爲較佳，以l〇°C以內爲更佳，以8°C以內 爲又更佳，以5艺以下爲特佳。熔點差異爲25 t：以下時， ^ 雙金屬狀結構所產生的捲曲能夠抑制在實用範圍以內。 又，因爲構成光擴散層（B)之樹脂的熔點以上述範圍爲佳， 構成支撐層（A)之結晶性聚酯/結晶性同元聚酯的熔點的上 限以270°C爲佳。 構成支撐層（A)及光擴散層（B)之結晶性聚酯的熔點能 夠藉由導入共聚合成分來控制。特別是本發明以在構成光 擴散層（B)的結晶性聚酯導入規定量的共聚合成分爲佳。藉 由在聚酯中導入共聚合成分，能夠控制雙軸拉伸薄膜的面 配向係數，能夠兼具光線透射率及光擴散性。但是過量地 導入共聚合成分時，因爲聚酯的熔點降低而無法得到雙軸 拉伸薄膜本來優良的特性，所以必須加以注意。共聚合成 分的導入量係相對於芳香族二碳成分全體、或二醇成分全 體，以3莫耳％以上爲佳，以5莫耳％以上爲更佳，以7莫 耳°/。以上爲最佳，以8莫耳％以上爲特佳。共聚合成分的含 量大於3莫耳％以上時，因爲能夠抑制產生空隙，且容易 高度地兼具光線透射率及光擴散性，乃是較佳。另一方面， -17- 200846179 共聚合成分的導入量的上限係相對於上述成分以2〇莫耳％ 以下爲佳，以18旲耳％以下爲更佳，以15莫耳％以下爲特 佳。使共聚合成分爲20莫耳％以下時，因爲雙金屬狀結構 所產生的捲曲能夠抑制在實用範圍以內，乃是較佳。又， 在本發明能夠使用的共聚合成分的組成係如後述。 (3 )光擴散層（B)的積層構成的控制 本發明的表面光擴散性聚酯薄膜藉由共擠壓法在支撐 層（A)(由含有前述結晶性同元聚酯、或共聚合成分之結晶 ^ 性聚酯所構成）的至少一面層積光擴散層（B)(由含有前述共 聚合成分之結晶性聚酯及與該聚酯爲非相溶性的添加劑的 調配組成物所構成）係重要的。 在光擴散層（B)之光的擴散能夠分成起因於薄膜的表 面結構之散射、及起因於薄膜的內部結構之散射。前述散 射能夠評價作爲表面霧度，而後述散射能夠評價作爲內部 霧度。空隙寺內部結構引起之光的散射係帶有後方散射， 無法得到高總光線透射率。另一方面，表面結構引之光的 0 散射能夠得到高的光擴散性，且不會使總光線透射率大幅 度地降低。但是，爲了藉由光擴散層（B)來達成有效的表面 霧度，避免伴隨雙金屬狀結構所產生的捲曲係困難的。本 發明藉由採用（1)至（7)所揭示的手段，可提供一種能夠抑制 產生捲曲且同時表面霧度高的薄膜。亦即，本發明的表面 光擴散性聚酯薄膜藉由採用上述的多層結構、且藉由起因 於非相溶性的添加劑之光擴散層（B)表面的凹凸結構來賦 予光擴散性，能夠抑制在薄膜內部之光散射（內部霧度）來 200846179 達成高的總光線透射率。藉此，能夠謀求兼具高的光透射 性及光擴散性。 將本發明表面光擴散性聚酯薄膜作爲稜鏡薄片使用 時，能夠藉由將在支撐層（A)的一面層積光擴散層（B)而成 的薄膜作爲基材，並在光擴散層（B)相反面賦予稜鏡結構而 適合使用。本發明的表面光擴散性聚酯薄膜的層構成亦可 以是如上述之2層構成，若能夠得到本發明的效果時，按 照必要亦可以是3層以上的多層構成。在平坦的透明組件 重疊表面平坦的（未具有凹凸結構）薄膜時，會有產生牛頓 環致使視認性低落的情形。因此，將發明的薄膜單獨使用 作爲光擴散薄片時，爲了防止因與導光板或棱鏡薄片疊合 產生牛頓環，以在支撐層（A)的兩面層積光擴散層（B)爲 佳。又’在本發明能夠使用的非相溶性的添加劑的組成係 如後述。 (4)光擴散層（B)的厚度控制 本發明的表面光擴散性聚酯薄膜係有支撐層（A)及光 擴散層（B)，爲了得到本發明的表面光擴散性聚酯薄膜，光 擴散層（B)的厚度係重要的。光擴散層（B)的表面霧度係表 面凹凸越大時，有越高的傾向。因此，光擴散層（B)的添加 劑的粒徑係以較大爲佳。爲了得到對表面霧度有效的粒 徑’光擴散層（B)的厚度下限以3微米以上爲佳，以4微米 爲更佳，以5微米爲特佳。 另一方面，光擴散層（B)的厚度若是大於非相溶性的添 加劑的粒徑相當程度時，難以形成有效的表面凹凸結構。 .200846179 因此，若使光擴散層（B)的厚度增厚時，表面凹凸形成減 少，致使表面霧度降低。又，依照光擴散層（B)的厚度，起 因於光擴散層（B)的內部結構之內部霧度變高，致使總光線 透射率降低。爲了謀求兼具高總光線透射率及光擴散性， 以將光擴散層（B)的厚度控制在規定以下的範圍爲佳。因 此，光擴散層（B)的厚度上限以50微米爲佳，以30微米爲 更佳，以25微米爲又更佳，以20微米爲特佳。 又，光擴散層（B)相對於薄膜全體厚度（A + B)的比率提 ^ 高時，會使因雙金屬狀結構產生捲曲變爲容易。而且，因 爲與支撐層（A)比較時熔點相對較低的光擴散層（B)的比率 增加，薄膜全體變爲容易產生厚度不均，會損害表面平滑 性。又，因爲光擴散層（B)含有大量的共聚合成分，薄膜全 體之配向係數降低、且力學特性降低。另一方面，光擴散 層（B)相對於薄膜全體厚度之比率降低時，光擴散層（B)中 的添加劑會有在薄膜表面滲出的情形、或是脫落的情形。 因此，以將光擴散層（B)相對於薄膜全體厚度的比率控制在 ^ 規定範圍爲佳，以2〜50%的範圍爲佳。光擴散層（B)相對 於薄膜全體厚度（A + B)的比率的下限，以2%爲佳，以3%爲 更佳，以4%爲特佳。另一方面，光擴散層（B)相對於薄膜 全體厚度的比率的上限以50%爲佳，以35%爲更佳，以20% 爲特佳。 (5)光擴散層（B)構成樹脂的固有黏度的控制 本發明的特徵係藉由共擠壓法來賦予光擴散層（B)。因 爲本發明的表面光擴散性聚酯薄膜係以光學用途作爲目 -20- 200846179 的，所以異物所引起的光學缺點以較少爲佳，藉由共擠壓 法供給樹脂時以在熔融管線設置有用以除去異物之過濾器 爲佳。雖然使樹脂通過異物除去過濾器時，必須有一定的 擠壓壓力，但是若樹脂的固有黏度低時，因爲熔融樹脂在 擠壓時的吐出安定性降低，所以難以安定地製膜。又，樹 脂的固有黏度低時，所得到的光擴散層（B)的面配向係數降 低、且薄膜的力學強度降低。因此，認爲含有構成光擴散 層（B)的共聚合成分之結晶性聚酯的固體成分以較高爲 ^ 佳。然而，本發明者發現在該聚酯的固有黏度與表面霧度 之間有如下所述之値得驚訝的關聯性。 該結晶性聚酯的固有黏度若提高時，熔融攪拌時之剪 切力增加。因此，在擠壓機內攪拌混合該結晶性聚酯與對 其非相溶性的添加劑時，該結晶性聚酯的固有黏度越高 時，在熔融攪拌的剪切力增加、添加劑的分散性提高。認 爲這是藉由溶劑的剪切力使添加劑細粒化的緣故。如此， 添加劑的粒徑變小，且光擴散層（B)表面無法到賦予良好的 ^ 凹凸結構程度之有效的分散徑，致使表面霧度降低。因此， 得知爲了謀求兼具光擴散層（B)的力學強度及良好的光特 性，以將含有構成光擴散層樹脂層的共聚合成分之結晶性 聚酯的固有黏度控制在規定範圍爲佳。 該結晶性聚酯的固有黏度的下限以〇.5 〇dl/g爲佳，以 0.52dl/g爲更佳。固有黏度小於〇.50dl/g時，在熔融管線 設置異物除去用過濾器時，在熔融樹脂的擠出時會有吐出 安定性降低的傾向。又，該結晶性聚酯的固有黏度的上限 -21 - 200846179 以 0.61dl/g爲佳’以 0.59dl/g爲更佳。固有黏度大於 0 · 6 1 dl/g時，前述添加劑在聚酯中的分散徑變小，光擴散 性會有降低的傾向。 (6)基材聚合物與非相溶樹脂的熔融黏度差異的控制 本發明者發現構成光擴散層（B)之該結晶性聚酯與非 相溶性的添加劑之熔融黏度差異與薄膜的表面霧度之間有 下述的關聯性。在本發明，藉由光擴散層（B )中的非相溶性 的添加劑能夠形成表面凹凸，來得到規定的表面霧度。含 W 有構成光擴散層（B )的共聚合成分之結晶性聚酯與非相溶 性的添加劑能夠在擠壓機內攪拌混合。非相溶性的添加劑 的態樣以熱塑性樹脂爲佳，該結晶性聚酯的熔融黏度與該 添加劑的熔融黏度爲相同程度時，二成分能夠容易地分 散’而將添加劑細粒化。減小該添加劑的分散徑時，無法 在光擴散層（B)表面得到良好的凹凸結構，致使表面霧度降 低。因此，在本發明，含有構成光擴散層（B)的共聚合成分 0 之結晶性聚酯與非相溶性的添加劑之熔融黏度差異以較大 爲佳。在270°C時之該熔融黏度差異以35Pa · s以上爲佳， 以4 0Pa · s以上爲更佳。熔融黏度差異爲35Pa · s以上時， 添加劑在聚酯中時添加劑具有良好的分散徑，能夠得到良 好的光擴散性。 (7)拉伸溫度與熱處理溫度條件的控制 薄膜的力學特性或光學特性亦能夠藉由製膜條件來控 制。提高薄膜的拉伸溫度時，因爲拉伸應力降低，所以配 向係數變低，能夠抑制產生空隙。又，因爲亦能夠更容易 -22- 200846179 地藉由非相溶性的添加劑來形成表面凹凸，從兼具總光線 透射率及光擴散性而言，以高溫拉伸爲佳。又，在高溫進 行熱處理時，因爲空隙消失而能夠降低內部霧度，而且， 熱尺寸變化率亦降低，在熱處理時不容易產生捲曲。但是， 提高拉伸溫度時，薄膜的厚度變動變大，致使產生厚度不 均，而難以得到薄膜本來的力學特性。在本發明的表面光 擴散性聚酯薄膜，爲了謀求優良的力學特性、及兼具總光 線透射率與光擴散性，以按照樹脂特性或要求特性來適當 ® 地控制製膜條件、特別是拉伸時的溫度及熱處理時的溫度 爲佳。 將聚酯樹脂拉伸來製造本發明的表面光擴散性聚酯薄 膜時，其橫向拉伸時的溫度以120°C至160 °C的溫度範圍內 爲佳。又，熱處理以在風爲25公尺/分鐘以上的條件下且 23 5至25 0 °C的溫度設定範圍內，在5秒至100秒的範圍內 進行熱處理爲佳。又，此時，薄膜溫度若大於240°C時， 會有光學特性降低的情形。又，在熱處理同時或熱處理後， ® 施加縱向或橫向的鬆弛處理亦無妨。 爲了達成如申請專利範圍第1項之必要條件（1 )，能夠 藉由實施上述手段（1)〜（3)的條件控制來達成。 爲了達成如申請專利範圍第1項之必要條件（2)，能夠 藉由實施上述手段（4)〜（7)的條件控制來達成。 爲了達成如申請專利範圍第1項之必要條件（3 )，能夠 藉由實施上述手段（3)〜（7)的條件控制來達成。 爲了達成如申請專利範圍第1項之必要條件（4)，能夠 -23- 200846179 藉由實施上述手段（3)〜（7)的條件控制來達成。 爲了達成如申請專利範圍第1項之必要條件（5)，能夠 藉由實施上述手段（1)〜（4)、（7)的條件控制來達成。 在本發明，認爲上述（1)〜（7)的手段係互相關聯且能夠 得到兼具上述矛盾特性之規定的效果。但是，在未脫離本 發明的宗旨的範圍時，亦能夠藉由與上述方法不同的方法 來達成。具體上，可舉出以下的手段。 上述（2)係顯示了抑制起因於雙金屬狀結構所產生的 ^ 捲曲之方法。上述說明係揭示在高度地兼具光線透射率及 光擴散性之後，如何進行來使光擴散層（B)與支撐層（A)的 線膨脹係數的差異減少時，能夠得到本發明的表面光擴散 性聚酯薄膜之技術思想。若是該業者時，能夠藉由與上述 方法不同的方法來容易地實施此種技術思想，來得到本發 明的表面光擴散性聚酯薄膜。 亦即，構成支撐層（A)之結晶性聚酯/結晶性同元聚酯 與構成光擴散層（B)之結晶性聚酯的熔點差異即便大於25 ^ 它時，在拉伸製程藉由在支撐層（A)與光擴散層（B)之各自 的面賦予拉伸溫度差異，而在支撐層（A)面側與光擴散層 (B)面側設置因拉伸所引起的配向狀態差異，並藉由控制薄 膜兩面的線膨脹係數的差異，能夠得到已控制起因於雙金 屬狀結構所產生的捲曲而成之表面光擴散性聚酯薄膜。 又，上述在上述（5)，係顯示了控制表面凹凸（藉由由添 加分散的添加劑所形成）所產生的表面霧度之方法。上述說 明係揭如何進行來控制添加劑的分散徑之技術思想，若是 -24- 200846179 該業者時，能夠藉由與上述方法不同的方法來容易地實施 此種技術思想。 亦即，即便含有構成光擴散層（B)的共聚合成分之結晶 性聚酯的固有黏度大於〇.61dl/g時，亦能夠藉由控制從擠 壓機內的混煉部後的聚合物管至模頭出口之添加劑的滯留 時間，來確保細粒化後的添加劑凝聚的時間，藉由控制添 加劑的分散徑能夠得到形成的表面凹凸所產生表面霧度。 又，藉由控制T模頭的狹縫間·隔，並藉由控制熔融樹脂吐 ® 出時的剪切力，能夠控制添加劑的分散徑。而且，對於一 次分散而成的熔融樹脂，藉由在混煉後的聚合物管內添加 具有使細粒化後的添加劑凝聚的效果之凝聚劑，能夠控制 添加劑的分散徑。例如，使用聚苯乙烯樹脂作爲添加劑時， 添加丙烯酸-苯乙烯共聚物等作爲凝聚劑時，能夠促進苯乙 烯樹脂的凝聚，能夠得到對光擴散有效的分散徑。此種丙 烯酸-苯乙烯共聚物能夠藉由使1莫耳的甲基丙烯酸環氧丙 酯與2莫耳苯乙烯單體共聚合等而得到。 又，在上述（7)的說明，係顯示了藉由控制薄膜的拉伸 溫度、控制拉伸應力，來控制空隙產生之方法。上述說明 係揭如何進行來使拉伸應力減小之技術思想，若是該業者 時，能夠藉由與上述方法不同的方法來容易地實施此種技 術思想。亦即/即便薄膜的拉伸溫度爲很低時，藉由使用 同時雙軸拉伸機，藉由使拉伸速度爲低速，能夠控制拉伸 應力，來抑制產生空隙。 而且’爲了得到本發明的表面光擴散性聚酯薄膜之構 -25- 200846179 成及特性，係如以下詳述。 (原料） 在本發明作爲薄膜原料所使用的結晶性同元聚酯有對 酞酸、異酞酸、萘二甲酸等芳香族二羧酸或其酯、與乙二 醇、二甘醇、1，3 -丙二醇、ΐ，4·丁二醇、新戊二醇等二醇進 行縮聚所製造的聚酯。該等聚酯除了能夠藉由使芳香族二 羧酸與二醇進行酯交換反應之直接聚合法來製造以外，亦 能夠藉由使芳香族二羧酸的烷酯與二醇進行酯交換反應 ® 後，使其縮聚之方法，或是使芳香族二羧酸的二甘醇酯縮 聚等之方法來製造。 前述聚酯的代表例可舉出聚對酞酸乙二酯、聚對酞酸 伸丙二酯、聚對酞酸丁二酯、聚2，6 -萘二甲酸乙二酯。前 述的聚酯可以是同元聚酯，在實質上未損害其結晶性的範 圍，亦可以是共聚合第三成分而成者。此等聚酯之中，對 酞酸乙二酯單位或是2,6-萘二甲酸乙二酯單位爲70莫耳％ 以上，以80莫耳％以上爲佳，以90莫耳％以上之聚酯爲更 佳。 又，在本發明能夠使用之含有共聚合成分的結晶性聚 酯，係指以上述的結晶性同元聚酯作爲基本骨架，並在主 鏈中導入第3成分（共聚合成分）而成的聚酯，其結構、分 子量及組成可以任意而沒有限定。 又，本發明的表面光擴散性聚酯薄膜以在原料的一部 分或全部使用由芳香族二羧酸成分與由乙二醇、及含有分 枝狀脂肪族二醇或脂環族二醇之至少1種二醇成分所構成 -26- 200846179 的共聚合聚酯爲佳。 分枝狀脂肪族二醇係例如可例示新戊二醇、1，2_丙二 醇、1，2-丁二醇。又，脂環族二醇可例示1，4-環己烷二甲醇、 二羥甲基三環癸烷等。 此等之中，以新戊二醇或1，4環己烷二甲醇爲特佳。 而且，在本發明，除了上述二醇成分以外，以使用1，3-丙 二醇、或1，4-丁二醇作爲共聚合成分爲較佳的實施態樣。 藉由在前述範圍導入該等二醇作爲共聚合成分而使用時， ® 因爲能夠賦予前述特性，乃是較佳，而且，從減少光擴散 層內的空隙來高度地兼具光線透射率及光擴散性而言，亦 是較佳。 而且，按照必要亦可在前述聚酯並用1種或2種以上 之下述的二羧酸成分及/或二醇成分作爲共聚合成分。 能夠與對酞酸或是其酯形成性衍生物一同並用之其他 的一羧酸成分可舉出（1)異對酞酸、2,6 -萘二竣酸、二苯基 I _4，4’·二羧酸、二苯氧基乙烷二羧酸、二苯基颯二羧酸、5-鈉磺酸基異酞酸、酞酸等芳香族二羧酸或其等的酯形成性 衍生物；（2)草酸、琥珀酸、己二酸、癸二酸、二聚物、順 丁嫌二酸、反丁烯二酸、戊二酸等脂肪族二羧酸或其等的 酯形成性衍生物；（3)環己烷二羧酸等脂環族二羧酸或其等 的酯形成性衍生物；及（4)對羥基苯甲酸、羥基己酸等羥基 羧酸或其等的酯形成性衍生物等。 另一方面’能夠與乙二醇及分枝狀脂肪族二醇及/或脂 環族二醇並用之其他的二醇成分可舉出例如戊二醇、己二 -27- 200846179 醇等脂肪族二醇、雙酚A及雙酚S等芳香族二醇及其等環 氧乙烷加成物、二甘醇、三甘醇及高碳數聚二醇等。 而且，按照必要亦能夠使1，2,4-苯三甲酸、1，3,5·苯三 甲酸及三羥甲基丙烷等多官能化合物對前述聚酯進行共聚 合。 在製造前述聚酯時所使用的觸媒，能夠使用例如鹼土 類金屬化合物、猛化合物、銘化合物、銘化合物、鍊化合 物、鈦化合物、鈦/矽複合氧化物及鍺化合物等。此等之中， ® 就觸媒活性而言，以鈦化合物、銻化合物、鍺化合物及鋁 化合物爲佳。 在製造前述聚酯時，以添加磷化合物作爲熱安定劑爲 佳。前述磷化合物例如較佳爲磷酸、亞磷酸等。 本發明的表面光擴散性聚酯薄膜可以將前述共聚合聚 酯直接使用作爲薄膜原料，亦可以使共聚合成分多的共聚 合聚酯與同元聚酯（例如聚對酞酸乙二酯）摻合，來調整共 聚合成分量。 ^ 特別是藉由使用後者的摻合法來製造薄膜，能夠兼具 與只有使用共聚合聚酯時同等的光擴散性及總光線透射 率，同時能夠調整含有具有高熔點（耐熱性）的共聚合成分 之結晶性聚酯。 又，採用熔融混合不同2種類的結晶性聚酯，並利用 兩者的酯交換反應而在主鏈中導入第3成分（共聚合成分） 之方法亦佳。特別是摻合至少1種以上前述共聚合聚酯、 聚對酞酸乙二酯、及聚對酞酸乙二酯以外的同元聚酯（例如 -28- 200846179 聚對酞酸伸丁二酯或聚對酞酸丁二酯），來使用作爲本發明 的表面光擴散性聚酯薄膜的原料，就減少空隙而言乃是更 佳。 又，構成前述支撐層（A)之聚酯以實質上未含有粒子爲 佳。又，構成光擴散層之結晶性共聚合聚酯以實質上未含 有後述之添加劑以外的粒子爲佳。上述「實質上未含有粒 子」係意指例如無機粒子時，藉由螢光X線分析定量無機 元素時爲50ppm以下，以l〇ppm以下爲佳，以檢測界限以 下的含量爲特佳。如此地，藉由使用無雜質、潔淨的聚酯 原料，在液晶顯不器能夠抑制產生光學缺點。 (添加劑 <表面凹凸賦予劑>) 在本發明之添加劑係爲了賦予光擴散層表面凹凸，來 顯現表面光擴散性之目的而添加。往光擴散層入射（從光擴 散層射出）之光線，藉由被賦予在薄膜表面的凹凸而往無規 的方向折射、擴散，來顯現表面光擴散性。上述添加劑若 是與聚酯爲非相溶性的材料時可任意使用而沒有任何限 制，以使用如下述的材料爲佳。 (與聚酯爲非相溶性的熱塑性樹脂） 在本發明能夠使用之最優良添加劑，係對前述聚酯非 相溶性的熱塑性樹脂。亦即，活用聚酯與熱塑性樹脂之非 相溶性，在雙軸拉伸薄膜的製程（熔融、擠壓製程），能夠 在由聚酯所構成的基質中形成由與該聚酯爲非相溶性的熱 塑性樹脂所構成的領域，來活用作爲表面凹凸形成劑之技 術。藉由使用該技術’在薄膜的熔融、擠壓製程藉由高精 -29- 200846179 度的過濾器來過濾異物，能夠達成作爲液晶顯示器用薄膜 所必要的潔淨度。 對此，使用後述的非熔融性的聚合物粒子或無機粒子 作爲添加劑時，在薄膜的製程能夠使用的過濾器的孔眼開 度的微細度有其限度’咼精度地除去異物係困難的。而且 使用聚合物粒子或無機粒子時，在粒子與聚酯的界面容易 產生空隙，高度地兼具光擴散性總光線透射率係困難的。 能夠使用作爲前述添加劑之與聚酯爲非相溶性的熱塑 性樹脂，可舉出例如以下的材料。亦即聚乙烯、聚丙烯、 聚甲基戊烯、各種環狀烯烴系聚合物等的聚烯烴、聚碳酸 酯、無規聚苯乙烯、間規聚苯乙烯、順聯聚苯乙烯等的苯 乙烯、聚醯胺、聚醚、聚酯型醯胺、聚苯硫、聚苯醚、聚 醚酯、聚氯乙烯、聚甲基丙烯酸酯等丙烯酸樹脂、及以此 等作爲主成分之共聚合物、或該樹脂的混合物等。 此等之中，爲了製造具有高光線透射率之薄膜，以使 用非晶性的透明聚合物爲特佳。相對地，使用結晶性聚合 物作爲添加劑時，有結晶性聚合物白濁致使薄膜內部霧度 變大、光線透射率降低之可能性。 在本發明能夠使用的非結晶性透明聚合物可舉出例如 以下之物。亦即聚苯乙烯（PS樹脂）、丙烯腈-苯乙烯共聚物 (AS樹脂）、甲基丙烯酸甲酯-苯乙烯共聚物（MS樹脂）、環 狀烯烴系聚合物、甲基丙烯酸樹脂及PMMA等。 此等之中，就減少空隙而言，以選擇聚合物的表面張 力相對於由聚酯構成的基質較爲接近之非晶性透明聚合物 -30- 200846179 爲更佳。該等表面張力接近聚酯之非晶性透明聚合物，以 聚苯乙烯（PS樹脂）、PMMA爲特佳。 (非熔融性聚合物粒子） 能夠使用作爲本發明的添加劑之非熔融性聚合物粒 子，若是使用熔點測定裝置（Standford Research Systems 公司製、MPA 1 0 0型），從3 0 °C以1 〇 °C /分鐘升溫至3 5 0 °C時， 不會因溶融而造成流動變形的粒子時，其組成沒有限定。 可舉出例如丙烯酸系樹脂、聚苯乙烯系樹脂、聚烯烴系樹 脂、聚酯系樹脂、聚醯胺系樹脂、聚醯亞胺系樹脂、氟系 樹脂、脲系樹脂、三聚氰胺系樹脂及有機矽系樹脂等。粒 子形狀以球狀或橢圓狀爲佳。又，該粒子可具有細孔，亦 可未具有細孔。而且亦能夠並用兩者。 上述的非熔融性聚合物粒子係由具有3 5 0 °C以上的熔 點之聚合物所構成時，雖然亦可以使用非交聯聚合物，但 是就耐熱性而言，以使用具有交聯結構之聚合物所構成的 交聯聚合物粒子爲佳。 上述的非熔融性聚合物粒子的平均粒徑以0.1〜5 0微 米爲佳。上述非熔融性聚合物粒子的平均粒徑的下限以0.5 微米爲更佳，以5微米爲特佳。爲了發揮良好的光擴散效果， 上述非熔融性聚合物粒子的平均粒徑以0.1微米以上爲佳。 另一方面，上述非熔融性聚合物粒子的平均粒徑的上 限以3 0微米爲更佳，以20微米爲特佳。上述非熔融性聚 合物粒子的平均粒徑大於5 0微米時，薄膜強度或總光線透 射率容易下降。該非熔融性聚合物粒子以盡可能使用具有 200846179 尖銳的粒子分布之粒子爲佳。 上述非熔融性聚合物粒子可使用1種類，亦可使用2 種類上。並用具有尖銳的粒子分布（係意指粒子的粒徑均 勻）、且不同平均粒徑之複數種非熔融性聚合物粒子，因爲 能夠抑制成爲薄膜缺點之粗大粒子的混入，乃是較佳的實 施形態。 又，上述粒子的平均粒徑的測定係依照以下方法來進 行。 ^ 使用掃描型電子顯微鏡（SEM)拍攝粒子照片，以最小粒 子1個大小成爲2〜5毫米的倍率，測定300〜500個粒子 的最大直徑（最離開2點間的距離），並以其平均値作爲平 均粒徑。又，在薄膜中所含有的粒子係單獨時，係測定各 個粒子的最大直徑，並以其平均値作爲平均粒徑。 (無機粒子） 能夠使用作爲添加劑之無機粒子，可舉出二氧化矽、 碳酸鈣、硫酸鋇、硫酸鈣、氧化鋁、高嶺土及滑石等。 上述無機粒子的平均粒徑通常以〇 . 1〜5 0微米爲佳。 以0.5〜30微米爲較佳，以1〜20微米爲更佳。平均粒徑 小於〇 . 1微米時無法得到良好的光擴散效果。相反地，大 於50微米時，與薄膜強度降低等有關聯，乃是不佳。該無 機粒子的粒子分布以盡可能使用尖銳者。有必要擴大粒子 分布時，以調配複數種尖銳的粒子分布的粒子來對應爲 佳。藉由該對應，能夠抑制成爲薄膜缺點之粗大粒子的混 入。 -32- 200846179 又，上述粒子的平均粒徑的測定係依照以下方法來進 行。 使用掃描型電子顯微鏡（SEM)拍攝粒子照片，以最小粒 子1個大小成爲2〜5毫米的倍率，測定3 0 0〜5 0 0個粒子 的最大直徑（最離開2點間的距離），並以其平均値作爲平 均粒徑。又，測定薄中所含有粒子的最大直徑，並以其平 均値作爲平均粒徑。 上述無機粒子的形狀沒有限定，以實質上爲球狀或是 ^ 真球狀爲佳。又，該粒子可以是無孔或多孔型之任一者。 而且，亦可並用兩者。 本發明所使用的添加劑可以是上述3種中的1種，亦 可以並用2種以上。 (添加劑的混合比率） 在本發明的表面光擴散性聚酯薄膜之光擴散層，係由 5 0〜9 9質量份含有前述共聚合成分之結晶性聚酯及1〜5 〇 質量份與該聚酯爲非相溶性的添加劑之調配組成物所構 成。兩者的較佳調配比率係75〜98質量份聚酯與2〜25質 量份添加劑之調配，更佳係8 0〜9 7質量份聚酯與3〜2 0質 量份添加劑之調配。 而且，上述添加劑的混合比率小於1質量份時，添加 劑所引起的表面凹凸形成能力不足，無法得到充分的表面 光擴散性能。另一方面，添加劑的混合比率大於5 0質量份 時，在添加劑/聚醋界面的光散射增大，同時聚酯的拉伸應 力增大而在添加劑周圍容易產生空隙。結果，光擴散層的 -33 - 200846179 內部霧度變大，總光線透射率有下降的傾向。而且，在薄 膜的雙軸拉伸時添加劑容易脫落，而該脫落物有可能成爲 異物的原因。 [光擴散性聚酯薄膜的特性] (面配向係數） 本發明的表面光擴散性聚酯薄膜之面配向係數（△ P) 爲0.0 8〜0.16係重要的。面配向係數（△ P)的下限以0.09 爲較佳，以0.10爲特佳。另一方面，面配向係數（△ P)的上 ® 限以〇 · 1 5爲較佳，以0 · 1 4爲特佳。 面配向係數（ΔΡ)爲0.16以下時，光擴散層（B)表面的 凹凸能夠有效地形成，因爲藉由表面凹凸產生光擴散效果 (表面霧度）能夠發揮，乃是較佳。 又，面配向係數（ΔΡ)大於0.16時，雖然亦取決於所使 用添加劑的種類，在添加劑的周圍產生空隙的數目或大小 有增加的傾向。因此，內部散射（內部霧度）變大，致使總 光線透射率有降低的傾向。總之，面配向係數（△ P)爲0.1 6 以下時，能夠謀求兼具總光線透射率與光擴散性。 另一方面，面配向係數爲0.0 8以上時，能夠發揮作爲 雙軸拉伸薄膜的特徵，耐熱性、機械強度及厚度均勻性等 良好，且能夠抑制加熱捲曲的產生。 將面配向係數控制在上述範圍內之方法係任意，例如 能夠藉由共聚合成分在含有前述共聚合成分之結晶性聚酯 中的比率來控制。光擴散層中或是支撐層（A)中的共聚合成 分的比率增大時，面配向係數降低，又，若降低共聚合成 -34- ,200846179 分的比率時，能夠使面配向係數上升。較佳的共聚 比率係如前述。 又，藉由聚合物摻合、或是共聚合來控制含有 聚合成分之結晶性聚酯的玻璃轉移點亦無妨。使玻 點降低時，在後述的雙軸拉伸製程的配向降低，能 配向係數降低。又，使光擴散層所使用原料聚酯的 度降低，亦能夠得到同樣的效果。較佳的固有黏度 述。 ® 而且，藉由調整後述雙軸拉伸的條件，亦能夠 度控制面配向係數。爲了降低面配向係數，可將縱 或橫向拉伸的拉伸溫度設定爲較高，或是將拉伸倍 爲較低，或是將熱處理溫度設定爲較高。較佳的雙 條件係如後述。 (光學特性） 接著，本發明之特徵係表面霧度爲15 %以上、 • 霧度小於表面霧度。表面霧度係來自表面凹凸的特 此，從薄膜表面射出光線時，或是光線入射薄膜表 藉由在光擴散層的表面凹凸，光線產生折射而使表 變高。因此，表面霧度基本上係與總光線透射率無 因此，藉由提高表面霧度，能夠在抑制總光線透射 低之狀態，來提高光擴散性。 另一方面，內部霧度係來自薄膜內部的光散 性。因此，由於入射光往後方散射的影響，總光線 降低。因此，爲了製造具有優良的光擴散性及高總 合成分 前述共 璃轉移 夠使面 固有黏 係如前 某種程 向拉伸 率設定 軸拉伸 且內部 性。因 面時， 面霧度 關係。 率的降 射之特 透射率 光線透 -35- 200846179 射率之光擴散性聚酯薄膜，在提高表面霧度的同時，極力 地減小內部霧度係有效的手段。 本發明的表面光擴散性聚酯薄膜的表面霧度爲1 5%以 上。表面霧度的較佳下限爲20%，下限以25%爲更佳，下 限以30%爲特佳。表面霧度爲15%以上時，對導光板的印 刷花紋、或冷陰極管的燈管影像能夠有效地發揮擴散效 果，作爲光擴散性薄膜能夠得到有效的光擴散性能。 另一方面，表面霧度之較佳上限値爲6 0 %，上限値以 ^ 7 0 %爲較佳，上限値以8 0 %爲更佳。表面霧度爲8 0 %以下 時，內部霧度受到抑制，而使總光線透射率有變高的傾向。 又，內部霧度小於表面霧度係重要的。內部霧度的上 限値以40%爲佳，以30%爲較佳，以20%爲更佳，以10% 爲特佳。 內部霧度與表面霧度相同或是大於表面霧度時，內部 霧度變成擔任薄膜的光擴散功能之主體，在薄膜內部產生 0 光散射（伴隨後方反射），致使總光線透射率大幅度地降 低。另一方面，內部霧度的下限以1 %爲佳。內部霧度小於 1 %的薄膜有無法得到充分的表面霧度之傾向。 又，本發明的表面光擴散性聚酯薄膜以86%以上的總 光線透射率爲佳。總光線透射率的下限値以87%爲較佳， 下限値以88%爲更佳。[Technical Field] The present invention relates to a light diffusing film such as a backlight panel module or an illumination device used for a large-screen and high-brightness liquid crystal display. More specifically, it relates to a surface light diffusing polyester film which has both light diffusibility and light transmittance, and which has a small curl due to temperature change. [Prior Art] In recent years, the technical progress of liquid crystal displays has been remarkable, and it has been widely used for display devices such as personal computers or televisions, mobile phones, and the like. Since the liquid crystal display module does not have a light-emitting function alone, the liquid crystal display device can be displayed by providing a backlight module on the back surface. There are various ways for the backlight panel module, which can be roughly divided into two types. The most common method is the direct type, which has a light source on the inside of the glossy surface. In this method, since a light source such as a plurality of cold cathode tubes can be disposed directly under the illuminating surface, it is possible to obtain extremely high luminance and to have a characteristic of light loss. Therefore, it is widely used for a large-sized liquid crystal display having a high brightness such as a large liquid crystal TV. Another method is an edge light type method in which a light source is disposed on one side or both sides of a light guide plate which is disposed on a light-emitting surface, such as a transparent acrylic plate, and is attached to a fluorescent lamp. A large linear illuminator such as a cold cathode discharge tube (a cold cathode discharge tube) is provided, and a light cover made of a reflector is provided to introduce light into the light guide plate. This method has the characteristics of small consumption of electrons, small size, and thinness. Therefore, it is widely used for small displays such as notebook PCs, and is particularly required to be thinner and lighter in 200846179. The light guide plate of the end-illuminated backlight module is required to have a function of transmitting light incident from the end portion forward and a function of emitting the transmitted light toward the liquid crystal display element side. The function of the former depends on the materials used and the reflective properties of the interface. Moreover, the latter function depends on the shape of the surface of the light guide plate to avoid full light exposure conditions. A method of forming the shape of the surface of the light guide plate is known as a method of imparting a white diffusing material to the surface of the light guide plate; and a method of imparting a Fresnel shape of a lenticular lens or a crucible to the surface of the light guide plate. However, the light emitted from the light guide plate having such surface shapes may be unevenly distributed due to its shape. Therefore, in order to obtain a high-quality image, a light diffusing film is provided on the light guiding plate, and the light emitted from the light guiding plate is diffused and scattered to make the brightness of the illuminating surface uniform. In order to increase the front brightness of the backlight module, a sheet having a collecting function called a enamel sheet or a lens sheet is used to concentrate the light of the diffusing film as much as possible. The situation in the front direction. On the surface of the sheet, a large number of irregularities such as a ridge shape, a wavelength, and a pyramid shape are arranged, and the emitted light of the transmission-diffusing film is collected on the front surface to enhance the brightness of the illuminating surface. Such a ruthenium sheet is used by arranging one sheet or two sheets on the surface side of the diffusing film. Further, in order to make the luminance unevenness caused by the arrangement of the prism sheet or the defect of the sheet thinner (improve the shielding property), a light diffusing film may be disposed on the surface side of the prism sheet. The light-diffusing film used in the above-described backlight module is obtained by coating a light-diffusing layer made of a transparent resin containing fine particles 200846179 on the surface of a biaxially stretched polyester film (for example, see Patent Document 1). Patent Document 1: Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. 3,698,978. However, this method requires a light diffusion layer on one side of the base film and a light diffusion layer and a base film. The number of the light-diffusing film is a bimetallic structure and is heated to cause curling. This problem has become an important issue in recent years, such as the use of a large-sized, high-brightness direct-back type backlight crystal display. In the case of diffusive integration, the curl becomes more conspicuous, and since the power consumption of the light source, that is, the honey of the backlight module, in order to solve this problem, the light diffusion of the bimetal film must be eliminated. The layer surface has a number of micrometers to tens of hard coatings (non-light diffusing layers), and is a countermeasure against the linear expansion stress balance of the light diffusion layer. However, when the thickness of the hard coat layer is originally an unnecessary thickness of the undesired film, it may cause manufacturing. Moreover, the countermeasure for balancing the linear expansion stress of the front and back is as large as the above-mentioned large screen and high brightness. In addition, in recent years, in order to simplify the number of backlight module components and to reduce the cost, many proposals have been made to integrate the film with other optical functional films. It is revealed that a ruthenium sheet (refer to Patent Document: 2) is the mainstream. The line expansion system by coating or the liquid film which is easy to be used for a large liquid crystal panel module has a larger surface area, and the heat is increased. Generally, on both sides of the thickness of the base micron, the R which increases the light diffusion cost has a limit, and the reduction is not sufficient, or the light diffusibility is thin. 5) The characteristic system 200846179 has the first surface and the second surface. The first surface side of the plate-shaped light-transmitting substrate on the two main surfaces of the surface is formed in a matrix, and a light diffusion layer containing a plurality of light-transmitting particles is formed on the second surface side of the substrate. Further, a lens sheet for a liquid crystal display device (see Patent Document 4) characterized in that at least two layers of a light diffusion layer and a ruthenium shape formation layer are laminated, and the light diffusion layer is composed of a kneading light diffusion agent The formed thermoplastic resin layer is formed by forming a crucible shape on the surface of the thermoplastic resin layer to which the light diffusing agent is not kneaded. Further, there is disclosed a light-scattering biaxially stretched polyester film for a tantalum sheet (refer to Patent Document 5), which is provided by a light scattering agent added inside the film and a void generated around the film. Diffusion. Patent Document 3: Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. The light-transmitting particles which are actuated are disposed on the incident surface side of the light, and there is a problem that the front side luminance is drastically lowered due to the so-called reverse diffusion state. Therefore, this method cannot impart sufficient brightness and light diffusibility. On the other hand, in the method disclosed in Patent Document 4 or Patent Document 5, since the light diffusing property is imparted by the light scattering material inside the substrate, a part of the incident light is scattered behind and the light transmittance is lowered. The problem. Further, in recent years, a number of 200846179 studies have been conducted to impart light diffusibility to a biaxially stretched polyester film which has excellent heat resistance, mechanical strength, and thickness uniformity. The polyester film composed of a single material is inherently light diffusing' can solve the problem of the above-mentioned heating curl, or can open the way to integrate the function of the diffusion sheet and the sheet, and the industrial price is very large. of. However, any of the "tests that have been proposed to make the biaxially stretched polyester film itself light diffusing" may impair the inherent strength (heat resistance, mechanical strength, etc.) inherent in the biaxially stretched polyester film itself. It is not suitable for practical use because it impairs the light transmittance or the characteristics of the light diffusing light diffusing film. For example, in the film disclosed in the above Patent Document 5, it is presumed that the biaxially stretched polyester film having excellent heat resistance, mechanical strength, and excellent thickness uniformity originally has a characteristic, but since the light diffusibility is in the layer There are bubbles in the interior to give a problem that the light transmittance is low. The bubbles (voids) generated in the biaxial stretching process of the film have a parallel plate-like morphology with respect to the film surface. Therefore, when the light diffusing film is used for the backlight module, most of the light emitted from the illuminating surface is scattered toward the rear, and the light transmittance is impaired. In fact, the total light transmittance as shown in the example is only 8 5 . 3 %. Further, a laminated light diffusing film (see Patent Document 6) is disclosed in which an internal light diffusing film and a PET film laminated on at least one surface are formed, and the internal light diffusing film is composed of light containing fine particles. The polyester resin of the diffusion layer is obtained by using an amorphous polyester obtained by copolymerizing 25 mol% of an isomeric acid component with polyethylene terephthalate (PET). Patent Document 6: JP-A-2001-2725 08-A-200846179 In the above method, since the void is eliminated, the light transmittance can be improved. However, even in this method, the light diffusibility is the same by the light scattering inside the film, and it is unavoidable that the light transmittance is lowered as the incident light is scattered backward. Further, in the film of Patent Document 6, the structural resin (pet homopolymer) of the base material layer and the constituent resin (amorphous polyester) of the light diffusion layer are significantly different in crystallinity. As a result, the obtained biaxially stretched film itself became a bimetallic structure, and the biaxially stretched film itself was easily curled by heating. Therefore, in the post-processing process, there is a case where the film is curled due to heat treatment or the environment (temperature) of the liquid crystal display. Further, a film (see Patent Documents 7 to 13) is disclosed in which a light diffusing film is used as an intermediate layer, and a crystalline polyester resin layer is laminated on both surfaces thereof, and the light diffusing film has a melting point of A polyester having a temperature of 2 to 10 ° C or less is used as a constituent resin, and a light diffusing additive composed of particles or a thermoplastic resin which are incompatible with the constituent resin is prepared. [Patent Document 7] JP-A-2002- 1 245, 08, pp. Japanese Unexamined Patent Publication No. Hei No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. The film structure becomes the front and back object' and the curl generated by the asymmetric structure can be improved to some extent. However, there is no significant difference in crystallinity between the diffusive intermediate layer and the surface layer in light-10-200846179. Due to variations in the thickness of several layers or changes in the physical properties of the surface, there is a flatness in the presence of temperature changes inside. Significantly worse. Further, since most of the film is composed of a polyester having a remarkable degree or a lack of crystallinity in such a method, excellent heat resistance, mechanical strength, and thickness uniformity of the biaxially stretched film cannot be obtained. Further, a biaxially stretched polyethylene terephthalate film (refer to Patent Document 14) is disclosed, and spherical or convex lens-like particles having a specific particle diameter are prepared. Patent Document 14: Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. And 68% diffusion transmittance. Moreover, a film having a total light transmittance of 85% and a diffused transmittance of 63% is disclosed. However, the basic properties such as heat resistance, mechanical strength and thickness accuracy of the films are not disclosed, and it is impossible to determine the heat resistance of the biaxially-stretched polyethylene terephthalate. , mechanical strength and the possibility of high thickness accuracy. This is because the films are stretched by a factor of 3, 0, i.e., by an area ratio of 9, by stretching the unstretched film having a thickness of 200 μm in both the longitudinal and transverse directions. The film obtained by stretching twice has a thickness of 50 μm, and the actual area stretching ratio calculated by the thickness ratio before and after stretching is only 4. 0 times. In other words, it is considered that the set magnification and the actual value of the stretching apparatus are affected by the width shrinkage generated during the longitudinal stretching, the stretching magnification distribution generated during the transverse stretching, and the dimensional change due to the heat treatment. The draw ratio is significantly deviated. And -11-200846179, the actual area stretching ratio is about 4 times of stretching, and even if excellent light transmittance can be obtained, it is impossible to achieve the heat resistance, mechanical strength and high intrinsic characteristics of the biaxially stretched film. Thickness accuracy. SUMMARY OF THE INVENTION The problem to be solved by the invention is that the double-metal-shaped film substrate is gradually becoming more and more prone to curling due to an increase in size and a high output of a backlight module for a liquid crystal display. In order to solve the above problems, it is preferable to use the actual stretched film itself without using off-line coating (Patent Documents 1 and 2). However, the method of imparting light diffusibility to the biaxially stretched film itself does not prevent the light-diffusing particles from generating voids, and there is a problem that the total light transmittance is lowered (Patent Documents 3, 4, and 5). In the method of avoiding the occurrence of voids, the resin property or the stretching condition previously performed does not solve the problem of curl (Patent Document 6), or there is a problem that the mechanical strength of the film is lowered (Patent Documents 7-14). That is, since the mechanical properties of the biaxially stretched film have an antinomy relationship with the optical characteristics, it is impossible to obtain a thin film which can satisfy any of the properties. Therefore, in terms of overall quality, the conventional method of imparting a light-diffusing layer to a transparent base film by post-processing cannot be comparable, and the above method cannot be put into practical use. An object of the present invention is to provide a surface light diffusing polyester film which has excellent heat resistance, mechanical strength and thickness precision, and which has both total light transmittance and light diffusibility, and is capable of The heating curl generated from the bimetallic structure is suppressed. Means for Solving the Problem -12- 200846179 The surface light diffusing polyester film of the present invention which can solve the above problems has the following constitution. That is, the constitution of the invention of the first aspect of the invention is a light diffusing polyester film composed of a biaxially oriented polyester film, which is characterized by satisfying the following requirements (1) to (1) 5), (1) having a support layer and a light diffusion layer, the support layer being composed of a crystalline homopolyester or a crystalline polyester containing a copolymerization component; and the light diffusion layer is attached to the support layer At least one side is laminated by a co-extrusion method, and the system is composed of 50 to 99 parts by mass of a crystalline polyester having a copolymerization component having a melting point of 23 5 to 2 5 5 ° C and is non-phase with the polyester. a composition of 1 to 50 parts by mass of a soluble additive; (2) The surface alignment coefficient ΔΡ of the film defined by the following formula is 〇. 〇8~0. 16, Δ P = (nx + ny)/2-nz Here, nx, ny, and nz each indicate a refractive index in the longitudinal direction, a refractive index in the width direction, and a refractive index in the thickness direction; (3) the surface haze is 15% or more; ^ (4) The internal haze is less than the surface haze; and (5) the dimensional change rate at 150 °C is 3% or less in the longitudinal and transverse directions, and the tensile strength is longitudinal and horizontal. 〇 MPa or more. The invention of the invention of claim 2 is the invention of claim 1, wherein the total light transmittance is 86% or more, and the image sharpness at a comb width of 2 mm is 40% or less. The invention of claim 3 is the invention of claim 1, wherein the surface of the light diffusing layer has a coating of -13-. In the layer of 200846179, the coating layer is provided before stretching and alignment of the film, and at least one of a copolymerized polyester resin, a polyurethane resin, or an acrylic resin is used as a main component. The invention of claim 4 is the invention of claim 1, wherein the surface of both the light diffusion layer side and the support layer side has a copolymerized polyester resin or a polyamine group. A coating layer containing at least one of an acid ester resin or an acrylic resin as a main component. The composition of the invention of claim 5, for example, for the surface light diffusing polyester film-based enamel sheet of the first application of the patent specification, on the opposite side of the light diffusion layer, having a copolymerized polyester resin, A coating layer containing at least one of a polyurethane resin or an acrylic resin as a main component. Advantageous Effects of Invention Since the surface light diffusing polyester film of the present invention is composed of a multilayer structure in which a crystalline polyester is used as a main raw material, either of the support layer and the light diffusion layer, it is possible to suppress the structure derived from the bimetallic structure. Produces a force of daily heat curling, while having a biaxially stretched polyester film which is inherently excellent in heat resistance, mechanical strength and thickness accuracy. In addition, the surface light diffusing polyester film of the present invention contains a crystalline polyester containing a copolymer component as a main raw material of the light diffusion layer, and is added to the light because the surface alignment coefficient of the entire film is controlled within a specific range. The periphery of the non-compatible additive of the diffusion layer does not substantially generate voids and has a textured structure in the light-diffusing layer. Therefore, it has excellent surface light diffusibility and high light transmittance. [Embodiment] The present invention provides a surface light diffusing polyester film capable of suppressing warpage caused by heating, and having excellent mechanical properties of a biaxially stretched polyester film, and having total light Transmittance and light diffusivity. In order to achieve the above-mentioned characteristics, the inventors of the present invention paid particular attention to the relationship between the surface alignment coefficient of the film, the internal haze and the surface haze. As a result, it has been found that the characteristics described in the following (1) to (7) can be combined with the characteristics of such anti-my, and the present invention has been completed. Therefore, the characteristics of these means of achievement are first explained. Further, in order to have the above contradictory characteristics, it is considered that only one of the following means (1) to (7) cannot be effectively contributed, and it is necessary to use the means of (1) to (7) in combination. Both have the characteristics of the above contradictions. (1) Control of resin melting point of light diffusion layer (2) Control of difference in melting point (3) Control of laminated structure of light diffusion layer (4) Thickness control of light diffusion layer ^ (5) Intrinsic viscosity of resin constituting light diffusion layer Control (6) Control of the difference in melt viscosity between the base polymer and the incompatible resin (7) Control of the stretching temperature and heat treatment temperature conditions (1) Control of the melting point of the resin of the light diffusion layer (B) Surface light of the present invention The diffusible polyester film has a support layer (A) composed of a crystalline homopolyester or a crystalline polyester containing a copolymer component, and has a crystalline polyester containing a copolymerization component and the incompatible property. The light diffusing layer (B) composed of the additive composition. Here, crystalline polycondensation. 200846179 Ester/crystalline homopolymer The polyester refers to a polyester/covalent polyester having a melting point. Melting point is the endothermic peak temperature at the time of melting at the time of one temperature rise of differential scanning calorimetry (DSC). When measured by a differential scanning calorimeter, the polyester/isoester polyester can be observed as a distinct crystal melting heat peak as a melting point, which contains a crystalline polyester/crystalline homopolymer. The melting point of the resin is preferably higher in terms of heat resistance, mechanical strength, and thickness accuracy of the film. However, when the melting point of the resin is high, the tensile stress generated during stretching increases, and if there are non-compatible particles in the resin, voids (voids) are easily formed, resulting in a decrease in total light transmittance. The easiness of generation of voids is also affected by the stretching conditions described later, but has a strong correlation with the surface alignment coefficient of the film to be produced. The surface alignment coefficient indicates the alignment state of the polymer chain formed by the film after stretching. Although the alignment state is higher, the mechanical strength is stronger, but a large number of voids are also formed in the film. In order to reduce the surface alignment coefficient of the film, the generation of voids is suppressed, and the melting point of the resin constituting the light-diffusing layer (B) is preferably controlled within a certain range. The lower limit of the melting point of the crystalline polyester containing the copolymerization component constituting the light diffusing layer (B) is preferably 2 3 5 ° C, more preferably 240 ° C. When the melting point is at 2 3 5 ° C or higher, an alignment coefficient which can exhibit a desired degree of heat resistance, mechanical strength and thickness accuracy can be obtained. Further, the upper limit of the melting point of the crystalline polyester containing the copolymerization component constituting the light-diffusing layer (B) is preferably 255 °C. When the melting point is below 25 ° C, it is preferable because it is possible to suppress generation of voids in the light-diffusing layer (B). (2) Control of difference in melting point The surface light diffusing polyester film of the present invention has a support layer (A) composed of a crystalline homopolyester or a crystalline polyester containing a copolymer component. In the case of -16-, 200846179, the heat resistance, mechanical strength and thickness accuracy of the film are obtained, and the melting point of the crystalline polyester/crystalline homopolyester constituting the support layer (A) is preferably higher. However, when the melting point of the resin constituting the two layers of the support layer (A) and the light-diffusing layer (B) is large, curling due to the bimetallic structure is likely to occur. Therefore, the difference in melting point between the crystalline polyester/crystalline homopolyester constituting the support layer (A) and the crystalline polyester constituting the light-diffusing layer (B) is preferably within 25 ° C, and within 20 ° C. Preferably, it is more preferably within 1 〇 ° C, more preferably within 8 ° C, and more preferably 5 Å or less. When the difference in melting point is 25 t: or less, the curl generated by the bimetallic structure can be suppressed within the practical range. Further, the melting point of the resin constituting the light-diffusing layer (B) is preferably in the above range, and the upper limit of the melting point of the crystalline polyester/crystalline homo-polyester constituting the support layer (A) is preferably 270 °C. The melting point of the crystalline polyester constituting the support layer (A) and the light diffusion layer (B) can be controlled by introducing a copolymerization component. In particular, in the present invention, it is preferable to introduce a predetermined amount of copolymerization synthesis into the crystalline polyester constituting the light-diffusing layer (B). By introducing a copolymerization component into the polyester, it is possible to control the surface alignment coefficient of the biaxially stretched film, and it is possible to have both light transmittance and light diffusibility. However, when the copolymerization component is excessively introduced, it is necessary to pay attention to the fact that the melting point of the polyester is lowered and the biaxially stretched film is not excellent in properties. The amount of the copolymerization component to be introduced is preferably 3 mol% or more, more preferably 5 mol% or more, and more preferably 7 mol%, based on the total amount of the aromatic dicarbon component or the diol component. The above is the best, and it is particularly good at 8 mol% or more. When the content of the copolymerization component is more than 3 mol% or more, it is preferable because the occurrence of voids can be suppressed and the light transmittance and light diffusibility are easily combined. On the other hand, the upper limit of the amount of introduction of the copolymerization component is preferably 2 〇 mol% or less, more preferably 18 旲% or less, and particularly preferably 15 mol% or less. . When the copolymerization is divided into 20 mol% or less, the curl generated by the bimetallic structure can be suppressed to be within the practical range, which is preferable. Moreover, the composition of the copolymerization component which can be used in the present invention is as follows. (3) Control of the laminated structure of the light-diffusing layer (B) The surface light-diffusing polyester film of the present invention is supported by the co-extrusion method in the support layer (A) (containing the aforementioned crystalline homo-polyester or copolymerized component) The light-diffusing layer (B) is laminated on at least one surface of the crystalline polyester (formed by a blended composition of a crystalline polyester containing the copolymerizable component and an additive which is incompatible with the polyester) It is important. The diffusion of light in the light-diffusing layer (B) can be divided into scattering due to the surface structure of the film and scattering due to the internal structure of the film. The above-mentioned scattering can be evaluated as the surface haze, and the scattering described later can be evaluated as the internal haze. The scattering system of the light caused by the internal structure of the gap temple has backscattering, and high total light transmittance cannot be obtained. On the other hand, the zero scattering of the light guided by the surface structure can obtain high light diffusibility without greatly reducing the total light transmittance. However, in order to achieve an effective surface haze by the light-diffusing layer (B), it is difficult to avoid the curling system accompanying the bimetallic structure. The present invention can provide a film capable of suppressing generation of curl and high surface haze by the means disclosed in (1) to (7). In other words, the surface light diffusing polyester film of the present invention can be suppressed in light diffusing property by using the above-described multilayer structure and the uneven structure of the surface of the light diffusion layer (B) which is caused by the incompatible additive. Light scattering (internal haze) inside the film to 200846179 achieves a high total light transmission. Thereby, it is possible to achieve both high light transmittance and light diffusibility. When the surface light diffusing polyester film of the present invention is used as a ruthenium sheet, a film obtained by laminating a light diffusion layer (B) on one surface of the support layer (A) can be used as a substrate and in the light diffusion layer ( B) The opposite side is given to the crucible structure and is suitable for use. The layer structure of the surface light-diffusing polyester film of the present invention may be composed of two layers as described above, and if the effects of the present invention can be obtained, a multilayer structure of three or more layers may be used as necessary. In the case where the flat transparent member overlaps the film having a flat surface (having no uneven structure), there is a case where the Newton's ring is caused to cause a drop in visibility. Therefore, when the film of the invention is used alone as a light-diffusing sheet, it is preferable to laminate the light-diffusing layer (B) on both sides of the support layer (A) in order to prevent the Newton ring from being formed by overlapping with the light guide plate or the prism sheet. Further, the composition of the incompatible additive which can be used in the present invention is as follows. (4) Thickness Control of Light-Diffusion Layer (B) The surface light-diffusing polyester film of the present invention has a support layer (A) and a light-diffusing layer (B), and light diffusion is performed in order to obtain the surface light-diffusing polyester film of the present invention. The thickness of layer (B) is important. When the surface haze of the light-diffusing layer (B) is larger as the surface unevenness, the higher the tendency is. Therefore, the particle size of the additive of the light-diffusing layer (B) is preferably larger. In order to obtain a particle diameter effective for surface haze, the lower limit of the thickness of the light-diffusing layer (B) is preferably 3 μm or more, more preferably 4 μm, and particularly preferably 5 μm. On the other hand, when the thickness of the light-diffusing layer (B) is larger than the particle diameter of the incompatible additive, it is difficult to form an effective surface uneven structure. . In the case where the thickness of the light-diffusing layer (B) is increased, the surface unevenness is reduced, and the surface haze is lowered. Further, according to the thickness of the light-diffusing layer (B), the internal haze of the internal structure of the light-diffusing layer (B) becomes high, so that the total light transmittance is lowered. In order to achieve both high total light transmittance and light diffusibility, it is preferable to control the thickness of the light diffusion layer (B) to a predetermined range or less. Therefore, the upper limit of the thickness of the light-diffusing layer (B) is preferably 50 μm, more preferably 30 μm, still more preferably 25 μm, and particularly preferably 20 μm. Further, when the ratio of the light-diffusing layer (B) to the total thickness (A + B) of the film is increased, it becomes easy to cause curling due to the bimetallic structure. Further, since the ratio of the light-diffusing layer (B) having a relatively low melting point when compared with the support layer (A) increases, the entire film becomes liable to cause thickness unevenness and impairs surface smoothness. Further, since the light-diffusing layer (B) contains a large amount of copolymerized components, the alignment coefficient of the entire film is lowered and the mechanical properties are lowered. On the other hand, when the ratio of the light-diffusing layer (B) to the entire thickness of the film is lowered, the additive in the light-diffusing layer (B) may bleed out on the surface of the film or may fall off. Therefore, it is preferable to control the ratio of the light diffusion layer (B) to the thickness of the entire film to a predetermined range, preferably in the range of 2 to 50%. The lower limit of the ratio of the light diffusion layer (B) to the total thickness (A + B) of the film is preferably 2%, more preferably 3%, and particularly preferably 4%. On the other hand, the upper limit of the ratio of the light diffusion layer (B) to the total thickness of the film is preferably 50%, more preferably 35%, and particularly preferably 20%. (5) Control of the intrinsic viscosity of the resin constituting the light-diffusing layer (B) The present invention is characterized in that the light-diffusing layer (B) is provided by a co-extrusion method. Since the surface light diffusing polyester film of the present invention is used for optical purposes as the target of -20-200846179, the optical disadvantage caused by the foreign matter is preferably less, and it is useful to provide the resin in the melt line by the co-extrusion method. It is preferable to use a filter for removing foreign matter. When the resin is removed from the filter by the foreign matter, it is necessary to have a certain pressing pressure. However, if the inherent viscosity of the resin is low, the discharge stability of the molten resin at the time of extrusion is lowered, so that it is difficult to form a film stably. Further, when the intrinsic viscosity of the resin is low, the surface alignment coefficient of the obtained light-diffusing layer (B) is lowered, and the mechanical strength of the film is lowered. Therefore, it is considered that the solid content of the crystalline polyester containing the copolymerization component constituting the light-diffusing layer (B) is preferably higher. However, the inventors have found that there is a surprising correlation between the intrinsic viscosity of the polyester and the surface haze as described below. When the intrinsic viscosity of the crystalline polyester is increased, the shearing force at the time of melt stirring is increased. Therefore, when the crystalline polyester is stirred and mixed with an additive which is incompatible with the extruder, the intrinsic viscosity of the crystalline polyester increases, and the shearing force in melt stirring increases, and the dispersibility of the additive increases. . It is considered that this is because the shearing force of the solvent causes the additive to be finely granulated. Thus, the particle diameter of the additive becomes small, and the surface of the light-diffusing layer (B) cannot reach an effective dispersion diameter imparting a good degree of the uneven structure, resulting in a decrease in surface haze. Therefore, it has been found that it is preferable to control the intrinsic viscosity of the crystalline polyester containing the copolymer component constituting the light-diffusing layer resin layer to a predetermined range in order to achieve both the mechanical strength of the light-diffusing layer (B) and the excellent light characteristics. . The lower limit of the intrinsic viscosity of the crystalline polyester is 〇. 5 〇 dl / g is better, with 0. 52dl/g is better. Intrinsic viscosity is less than 〇. When the filter for foreign matter removal is provided in the molten line at 50 dl/g, the discharge stability tends to decrease at the time of extrusion of the molten resin. Further, the upper limit of the intrinsic viscosity of the crystalline polyester is -21 - 200846179 at 0. 61dl/g is better than 0. 59 dl / g is better. When the intrinsic viscosity is more than 0 · 6 1 dl/g, the dispersion diameter of the above-mentioned additive in the polyester becomes small, and the light diffusibility tends to be lowered. (6) Control of Melt Viscosity Difference Between Substrate Polymer and Incompatible Resin The present inventors have found that the difference in melt viscosity of the crystalline polyester constituting the light diffusion layer (B) and the incompatible additive and the surface mist of the film There is the following correlation between degrees. In the present invention, surface irregularities can be formed by the incompatible additive in the light-diffusing layer (B) to obtain a predetermined surface haze. The crystalline polyester containing W having a copolymerization component constituting the light-diffusing layer (B) and the non-compatible additive can be stirred and mixed in an extruder. The aspect of the non-compatible additive is preferably a thermoplastic resin. When the melt viscosity of the crystalline polyester is the same as the melt viscosity of the additive, the two components can be easily dispersed to finely granulate the additive. When the dispersion diameter of the additive is reduced, a good uneven structure cannot be obtained on the surface of the light-diffusing layer (B), resulting in a decrease in surface haze. Therefore, in the present invention, the difference in melt viscosity between the crystalline polyester containing the copolymer component 0 constituting the light-diffusing layer (B) and the non-compatible additive is preferably large. The difference in melt viscosity at 270 ° C is preferably 35 Pa · s or more, more preferably 40 Pa · s or more. When the difference in melt viscosity is 35 Pa·s or more, the additive has a good dispersion diameter in the polyester, and good light diffusibility can be obtained. (7) Control of stretching temperature and heat treatment temperature conditions The mechanical properties or optical properties of the film can also be controlled by film forming conditions. When the stretching temperature of the film is increased, the tensile stress is lowered, so that the alignment coefficient is lowered, and generation of voids can be suppressed. Further, since it is also easier to form the surface unevenness by the incompatible additive, it is preferable to apply the high-temperature stretching in terms of the total light transmittance and the light diffusing property. Further, when the heat treatment is performed at a high temperature, the internal haze can be lowered because the voids disappear, and the rate of change in the thermal dimensionality is also lowered, so that curling is less likely to occur during the heat treatment. However, when the stretching temperature is raised, the thickness variation of the film becomes large, resulting in uneven thickness, and it is difficult to obtain the original mechanical properties of the film. In the surface light diffusing polyester film of the present invention, in order to obtain excellent mechanical properties and to have both total light transmittance and light diffusibility, it is possible to appropriately control film forming conditions, particularly stretching, in accordance with resin properties or required properties. The temperature at the time and the temperature at the time of heat treatment are preferred. When the polyester resin is stretched to produce the surface light diffusing polyester film of the present invention, the temperature in the transverse stretching is preferably in the range of from 120 °C to 160 °C. Further, the heat treatment is preferably carried out in the range of 5 seconds to 100 seconds in a temperature setting range of 25 m/min or more and 23 5 to 25 ° C. Further, at this time, when the film temperature is more than 240 ° C, the optical characteristics may be lowered. Also, after the heat treatment or after the heat treatment, it is possible to apply longitudinal or lateral relaxation treatment. In order to achieve the necessary condition (1) as in the first aspect of the patent application, it is possible to achieve the conditional control by the above means (1) to (3). In order to achieve the condition (2) necessary for the first item of the patent application range, it can be achieved by implementing the conditional control of the above means (4) to (7). In order to achieve the condition (3) necessary for the first item of the patent application, it can be achieved by implementing the conditional control of the above means (3) to (7). In order to achieve the necessary condition (4) as in the first paragraph of the patent application, it is possible to implement the conditional control of the above means (3) to (7) by -23-200846179. In order to achieve the requirement (5) of the first item of the patent application range, it is possible to achieve the conditional control by the above means (1) to (4) and (7). In the present invention, it is considered that the means (1) to (7) described above are related to each other and the effect of the above-described contradictory characteristics can be obtained. However, it can be achieved by a method different from the above method without departing from the scope of the invention. Specifically, the following means can be mentioned. The above (2) shows a method of suppressing the occurrence of the curl caused by the bimetallic structure. The above description reveals how the surface light diffusion of the present invention can be obtained when the difference in linear expansion coefficient between the light diffusion layer (B) and the support layer (A) is reduced after highly having both light transmittance and light diffusibility. The technical idea of polyester film. In the case of the manufacturer, the technical idea of the present invention can be easily carried out by a method different from the above method to obtain the surface light diffusing polyester film of the present invention. That is, the difference in melting point between the crystalline polyester/crystalline homopolyester constituting the support layer (A) and the crystalline polyester constituting the light-diffusing layer (B) is greater than 25 ^, in the stretching process by the stretching process The stretching temperature difference is given to the respective faces of the support layer (A) and the light diffusion layer (B), and the alignment state due to stretching is provided on the surface side of the support layer (A) and the surface side of the light diffusion layer (B). By the difference, and by controlling the difference in linear expansion coefficients on both sides of the film, it is possible to obtain a surface light diffusing polyester film which has been controlled to be curled by the bimetallic structure. Further, in the above (5), there is shown a method of controlling the surface haze generated by the surface unevenness (formed by adding a dispersed additive). The above description discloses a technical idea of how to control the dispersion diameter of the additive. If the manufacturer is in the same manner as described above, the technical idea can be easily implemented by a method different from the above method. That is, even if the crystalline polyester containing the copolymer component constituting the light-diffusing layer (B) has an intrinsic viscosity greater than 〇. At 61 dl/g, it is also possible to ensure the time for the aggregation of the finely granulated additives by controlling the residence time of the additive from the polymer tube after the kneading section in the extruder to the die outlet, by controlling the additive The dispersion diameter can obtain the surface haze produced by the surface irregularities formed. Further, by controlling the slit between the T-die and the shear force at the time of controlling the discharge of the molten resin, the dispersion diameter of the additive can be controlled. Further, the molten resin which is once dispersed can be controlled by adding a coagulant having an effect of agglomerating the finely granulated additives in the polymer tube after kneading, whereby the dispersion diameter of the additive can be controlled. For example, when a polystyrene resin is used as an additive, when an acrylic acid-styrene copolymer or the like is added as a coagulant, aggregation of the styrene resin can be promoted, and a dispersion diameter effective for light diffusion can be obtained. Such an acrylic acid-styrene copolymer can be obtained by copolymerizing 1 mol of propylene methacrylate with 2 mol styrene monomer. Further, in the above description of (7), a method of controlling the generation of voids by controlling the stretching temperature of the film and controlling the tensile stress is shown. The above description is directed to the technical idea of how to reduce the tensile stress. If the manufacturer is concerned, such a technical idea can be easily implemented by a method different from the above method. That is, even when the stretching temperature of the film is low, by using a simultaneous biaxial stretching machine, by making the stretching speed low, the tensile stress can be controlled to suppress generation of voids. Further, in order to obtain the characteristics and characteristics of the surface light diffusing polyester film of the present invention, it will be described in detail below. (Materials) The crystalline homopolymer used as a raw material of the film of the present invention is an aromatic dicarboxylic acid such as citric acid, isophthalic acid or naphthalene dicarboxylic acid or an ester thereof, and ethylene glycol, diethylene glycol, and 1 A polyester produced by polycondensation of a diol such as 3-propanediol, hydrazine, 4, butanediol or neopentyl glycol. These polyesters can be produced by a direct polymerization method in which an aromatic dicarboxylic acid and a diol are transesterified, and can also be transesterified by an alkyl ester of an aromatic dicarboxylic acid with a diol. Thereafter, it is produced by a method of polycondensation or a method of polycondensing a diethylene glycol ester of an aromatic dicarboxylic acid. Representative examples of the polyester include polyethylene terephthalate, propylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate. The polyester described above may be a homopolyester, and may not substantially impair the crystallinity thereof, or may be a copolymerized third component. Among these polyesters, the unit of ethylene phthalate or the unit of ethylene 2,6-naphthalate is 70 mol% or more, preferably 80 mol% or more, and 90 mol% or more. Polyester is better. In addition, the crystalline polyester containing a copolymerization component which can be used in the present invention means that the above-mentioned crystalline homopolyester is used as a basic skeleton, and a third component (copolymerization component) is introduced into the main chain. The structure, molecular weight and composition of the polyester may be arbitrarily and without limitation. Further, the surface light diffusing polyester film of the present invention uses at least one of an aromatic dicarboxylic acid component and ethylene glycol, and a branched aliphatic diol or an alicyclic diol in part or all of the raw material. It is preferred that the diol component constitutes a copolymerized polyester of -26-200846179. The branched aliphatic diol may, for example, be neopentyl glycol, 1,2-propylene glycol or 1,2-butanediol. Further, the alicyclic diol may, for example, be 1,4-cyclohexanedimethanol or dimethyloltricyclodecane. Among them, neopentyl glycol or 1,4 cyclohexanedimethanol is particularly preferred. Further, in the present invention, in addition to the above diol component, the use of 1,3-propanediol or 1,4-butanediol as a copolymerization synthesis is classified into a preferred embodiment. When the diol is introduced as a copolymerization component in the above range, ® is preferable because it can impart the above characteristics, and the light transmittance and light are highly combined from the voids in the light diffusion layer. In terms of diffusivity, it is also better. Further, one or two or more kinds of the following dicarboxylic acid component and/or diol component may be used as a copolymerization component in the polyester as necessary. Other monocarboxylic acid components which can be used together with citric acid or an ester-forming derivative thereof include (1) isomeric decanoic acid, 2,6-naphthalenedicarboxylic acid, and diphenyl I _4, 4'. An ester-forming derivative of an aromatic dicarboxylic acid such as a dicarboxylic acid, a diphenoxyethane dicarboxylic acid, a diphenylphosphonium dicarboxylic acid, a 5-sodium sulfonate isophthalic acid or a citric acid or the like (2) Ester-forming derivative of oxalic acid, succinic acid, adipic acid, sebacic acid, dimer, succinic acid, fumaric acid, glutaric acid, etc. (3) an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid or an ester-forming derivative thereof; and (4) an ester formation of a hydroxycarboxylic acid such as p-hydroxybenzoic acid or hydroxycaproic acid or the like Sex derivatives, etc. On the other hand, the other diol component which can be used in combination with ethylene glycol and a branched aliphatic diol and/or an alicyclic diol may, for example, be an aliphatic group such as pentanediol or hexa-27-200846179 alcohol. An aromatic diol such as a diol, a bisphenol A or a bisphenol S, or an ethylene oxide adduct thereof, diethylene glycol, triethylene glycol or a high carbon polyglycol. Further, the polyester may be copolymerized with a polyfunctional compound such as 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid or trimethylolpropane as necessary. As the catalyst to be used in the production of the above polyester, for example, an alkaline earth metal compound, a stimulating compound, a compound, a compound, a chain compound, a titanium compound, a titanium/ruthenium composite oxide, a ruthenium compound or the like can be used. Among these, ® is preferably a titanium compound, a ruthenium compound, a ruthenium compound or an aluminum compound in terms of catalyst activity. In the production of the aforementioned polyester, it is preferred to add a phosphorus compound as a thermal stabilizer. The phosphorus compound is preferably, for example, phosphoric acid, phosphorous acid or the like. The surface light diffusing polyester film of the present invention can directly use the above-mentioned copolymerized polyester as a film raw material, and can also blend a copolymerized polyester having a large copolymerization component with a homopolyester (for example, polyethylene terephthalate). In order to adjust the copolymerization component. ^ In particular, by using the latter doping method to produce a film, it is possible to achieve the same light diffusibility and total light transmittance as when only a copolymerized polyester is used, and to adjust the copolymerization having a high melting point (heat resistance). A crystalline polyester of the composition. Further, it is also preferable to melt-mix two kinds of crystalline polyesters and introduce a third component (copolymerization component) into the main chain by a transesterification reaction between the two. In particular, a blend of at least one of the foregoing copolymerized polyester, polyethylene terephthalate, and polyethylene terephthalate (for example, -28-200846179 polybutylene terephthalate) is blended. Or, as the raw material of the surface light diffusing polyester film of the present invention, it is more preferable to reduce the voids. Further, the polyester constituting the support layer (A) is preferably substantially free of particles. Further, the crystalline copolymerized polyester constituting the light-diffusing layer preferably contains no particles other than the additives described later. The above-mentioned "substantially no particles" means that, for example, when the inorganic particles are quantified by fluorescent X-ray analysis, the content is 50 ppm or less, preferably 10 ppm or less, and particularly preferably the content below the detection limit. Thus, by using a non-impurity and clean polyester raw material, it is possible to suppress optical defects in the liquid crystal display. (additive <Surface unevenness imparting agent> The additive of the present invention is added for the purpose of imparting surface unevenness to the surface of the light-diffusing layer to exhibit surface light diffusibility. The light incident on the light-diffusing layer (ejected from the light-diffusing layer) is refracted and diffused in a random direction by being provided with irregularities on the surface of the film to exhibit surface light diffusibility. The above additives may be used arbitrarily if they are incompatible with the polyester without any limitation, and it is preferred to use a material as described below. (The thermoplastic resin which is incompatible with the polyester) The most excellent additive which can be used in the present invention is a thermoplastic resin which is incompatible with the above polyester. That is, the incompatibility between the polyester and the thermoplastic resin, in the process of biaxially stretched film (melting, extrusion process), can be formed in a matrix composed of polyester to be incompatible with the polyester. The field of thermoplastic resin is used as a technique for forming a surface unevenness forming agent. By using this technique, the foreign matter is filtered by a high-precision -29-200846179 degree filter in the melting and extruding process of the film, and the cleanliness necessary for the film for liquid crystal display can be achieved. On the other hand, when non-melting polymer particles or inorganic particles to be described later are used as the additive, the fineness of the opening of the filter which can be used in the process of the film has a limit, and it is difficult to remove the foreign matter with high precision. Further, when polymer particles or inorganic particles are used, voids are likely to occur at the interface between the particles and the polyester, and it is difficult to have a high light diffusing total light transmittance. A thermoplastic resin which is incompatible with the polyester as the above-mentioned additive can be used, and examples thereof include the following materials. That is, polyolefins such as polyethylene, polypropylene, polymethylpentene, various cyclic olefin polymers, polycarbonate, atactic polystyrene, syndiotactic polystyrene, cis-polystyrene, etc. Acrylic resins such as ethylene, polyamine, polyether, polyester decylamine, polyphenylene sulfide, polyphenylene ether, polyether ester, polyvinyl chloride, polymethacrylate, etc., and copolymerization thereof as a main component a substance, or a mixture of the resins, and the like. Among these, in order to produce a film having high light transmittance, it is particularly preferable to use an amorphous transparent polymer. On the other hand, when a crystalline polymer is used as an additive, the crystal polymer is turbid, which causes the internal haze of the film to increase and the light transmittance to decrease. The amorphous transparent polymer which can be used in the present invention may, for example, be as follows. That is, polystyrene (PS resin), acrylonitrile-styrene copolymer (AS resin), methyl methacrylate-styrene copolymer (MS resin), cyclic olefin polymer, methacrylic resin and PMMA Wait. Among these, in terms of reducing voids, it is more preferable to select the amorphous transparent polymer -30-200846179 whose surface tension of the polymer is relatively close to that of the matrix composed of polyester. These surface tensions are close to the amorphous transparent polymer of polyester, and are particularly excellent in polystyrene (PS resin) and PMMA. (Non-melt polymer particles) Non-melting polymer particles which are additives of the present invention can be used, and a melting point measuring device (MPA 1 0 0 type manufactured by Standford Research Systems Co., Ltd.) can be used, and 1 〇 from 30 ° C. When the temperature is raised to 550 ° C at ° C / min, the composition is not limited by the flow deformation of the particles due to melting. Examples thereof include an acrylic resin, a polystyrene resin, a polyolefin resin, a polyester resin, a polyamide resin, a polyimide resin, a fluorine resin, a urea resin, a melamine resin, and an organic compound. Lanthanum resin and the like. The shape of the particles is preferably spherical or elliptical. Further, the particles may or may not have fine pores. And it is also possible to use both. When the non-melting polymer particles described above are composed of a polymer having a melting point of 350 ° C or higher, a non-crosslinked polymer may be used, but in terms of heat resistance, a crosslinked structure is used. Crosslinked polymer particles composed of a polymer are preferred. The above non-melting polymer particles preferably have an average particle diameter of 0.1 to 50 μm. The lower limit of the average particle diameter of the non-melting polymer particles is more preferably 0.5 μm, and particularly preferably 5 μm. In order to exhibit a good light diffusing effect, the non-melting polymer particles preferably have an average particle diameter of 0.1 μm or more. On the other hand, the upper limit of the average particle diameter of the non-melting polymer particles is more preferably 30 μm, and particularly preferably 20 μm. When the average particle diameter of the non-melting polymer particles is more than 50 μm, the film strength or the total light transmittance is liable to lower. The non-melting polymer particles preferably use particles having a sharp particle distribution of 200846179 as much as possible. The non-melting polymer particles may be used in one type or in two types. It is preferable to use a plurality of types of non-melting polymer particles having a sharp particle distribution (which means that the particle diameter of the particles is uniform) and different average particle diameters because it is possible to suppress the incorporation of coarse particles which are disadvantages of the film. form. Further, the measurement of the average particle diameter of the above particles was carried out in accordance with the following method. ^ Using a scanning electron microscope (SEM) to take a photograph of the particles, using a minimum particle size of 2 to 5 mm, measuring the maximum diameter of 300 to 500 particles (the distance between the two points), and taking the average値 as the average particle size. Further, when the particles contained in the film are used alone, the maximum diameter of each particle is measured, and the average enthalpy is used as the average particle diameter. (Inorganic Particles) The inorganic particles which are additives can be used, and examples thereof include cerium oxide, calcium carbonate, barium sulfate, calcium sulfate, alumina, kaolin, and talc. The average particle diameter of the above inorganic particles is usually from 1 to 50 μm. It is preferably 0.5 to 30 μm, more preferably 1 to 20 μm. The average particle diameter is less than 〇. A good light diffusion effect cannot be obtained at 1 μm. On the contrary, when it is larger than 50 μm, it is associated with a decrease in film strength or the like, which is not preferable. The particle distribution of the inorganic particles is as sharp as possible. When it is necessary to expand the particle distribution, it is preferable to formulate a plurality of particles having a sharp particle distribution. By this correspondence, it is possible to suppress the incorporation of coarse particles which are disadvantages of the film. -32- 200846179 Further, the measurement of the average particle diameter of the above particles was carried out in accordance with the following method. A photograph of the particles was taken using a scanning electron microscope (SEM), and the maximum diameter (the distance between the two points) of 300 to 500 particles was measured with a minimum particle size of 2 to 5 mm. The average enthalpy is taken as the average particle diameter. Further, the maximum diameter of the particles contained in the thin film was measured, and the average enthalpy was used as the average particle diameter. The shape of the inorganic particles is not limited, and it is preferably a spherical shape or a true spherical shape. Further, the particles may be either non-porous or porous. Moreover, both can be used in combination. The additive to be used in the present invention may be one of the above three types, or two or more types may be used in combination. (mixing ratio of the additive) The light-diffusing layer of the surface light-diffusing polyester film of the present invention is composed of 50 to 99 parts by mass of the crystalline polyester containing the copolymerization component and 1 to 5 parts by mass of the polymer. The ester is composed of a blending composition of an incompatible additive. The preferred blending ratio of the two is 75 to 98 parts by mass of the polyester and 2 to 25 parts by mass of the additive, and more preferably 80 to 9 parts by mass of the polyester and 3 to 20 parts by mass of the additive. Further, when the mixing ratio of the above additives is less than 1 part by mass, the surface unevenness forming ability by the additive is insufficient, and sufficient surface light diffusing performance cannot be obtained. On the other hand, when the mixing ratio of the additive is more than 50 parts by mass, light scattering at the additive/polyester interface is increased, and the tensile stress of the polyester is increased to easily cause voids around the additive. As a result, the internal haze of the light diffusion layer -33 - 200846179 becomes large, and the total light transmittance tends to decrease. Further, the additive tends to fall off during biaxial stretching of the film, and the shedding material may be a foreign matter. [Characteristics of Light-Diffusing Polyester Film] (Face Matching Coefficient) It is important that the surface light-diffusing polyester film of the present invention has a surface alignment coefficient (ΔP) of 0.08 to 0.16. The lower limit of the surface alignment coefficient (Δ P) is preferably 0.09, and particularly preferably 0.10. On the other hand, the upper limit of the face alignment coefficient (Δ P) is preferably 〇 · 15 , and particularly preferably 0 · 1 4 . When the surface alignment coefficient (ΔΡ) is 0.16 or less, the unevenness on the surface of the light-diffusing layer (B) can be effectively formed, and it is preferable that the light-diffusion effect (surface haze) can be exhibited by the surface unevenness. Further, when the surface alignment coefficient (ΔΡ) is more than 0.16, the number or size of voids generated around the additive tends to increase depending on the type of the additive to be used. Therefore, internal scattering (internal haze) becomes large, and the total light transmittance tends to decrease. In short, when the surface alignment coefficient (?P) is 0.16 or less, it is possible to achieve both total light transmittance and light diffusibility. On the other hand, when the surface alignment coefficient is 0.08 or more, the characteristics of the biaxially stretched film can be exhibited, and heat resistance, mechanical strength, thickness uniformity, and the like are excellent, and generation of heat curl can be suppressed. The method of controlling the surface alignment coefficient within the above range is arbitrary, and can be controlled, for example, by the ratio of the copolymerization component in the crystalline polyester containing the copolymerization component. When the ratio of the copolymerization component in the light-diffusing layer or the support layer (A) is increased, the surface alignment coefficient is lowered, and when the ratio of the copolymerization -34- and 200846179 is decreased, the surface alignment coefficient can be increased. The preferred copolymerization ratio is as described above. Further, it is also possible to control the glass transition point of the crystalline polyester containing the polymerization component by polymer blending or copolymerization. When the glass frit is lowered, the alignment of the biaxial stretching process described later is lowered, and the alignment coefficient is lowered. Further, the same effect can be obtained by lowering the degree of the raw material polyester used in the light-diffusing layer. The preferred intrinsic viscosity is described. ® Moreover, the surface alignment coefficient can be controlled by adjusting the conditions of the biaxial stretching described later. In order to lower the surface alignment coefficient, the stretching temperature in the longitudinal or transverse stretching may be set to be higher, or the stretching ratio may be lower, or the heat treatment temperature may be set higher. The preferred dual conditions are as described later. (Optical Characteristics) Next, the present invention is characterized in that the surface haze is 15% or more, and the haze is smaller than the surface haze. The surface haze is derived from the surface unevenness, and when the light is emitted from the surface of the film, or the light is incident on the film surface, the surface of the light diffusion layer is embossed and the light is refracted to make the surface high. Therefore, the surface haze is basically the same as the total light transmittance. Therefore, by increasing the surface haze, the light diffusibility can be improved while suppressing the low total light transmission. On the other hand, the internal haze is derived from the light dispersion inside the film. Therefore, the total light is reduced due to the influence of the incident light scattering toward the back. Therefore, in order to produce excellent light diffusibility and high total composition, the above-mentioned conjugate transfer is sufficient to set the axial intrinsic adhesion to a certain axial elongation and axial elongation and internality. The surface haze relationship is due to the surface. Rate of Transmittance Transmittance Light Transmittance -35- 200846179 The light diffusing polyester film of the illuminance is an effective means to reduce the internal haze while minimizing the internal haze. The surface light diffusing polyester film of the present invention has a surface haze of 1 5% or more. The lower limit of the surface haze is preferably 20%, the lower limit is preferably 25%, and the lower limit is preferably 30%. When the surface haze is 15% or more, the printing pattern of the light guide plate or the tube image of the cold cathode tube can effectively exhibit the diffusion effect, and effective light diffusion performance can be obtained as the light diffusing film. On the other hand, the upper limit of the surface haze is 60%, the upper limit is preferably 270%, and the upper limit is preferably 80%. When the surface haze is 80% or less, the internal haze is suppressed, and the total light transmittance tends to be high. Also, the internal haze is less than the surface haze. The upper limit of the internal haze is preferably 40%, preferably 30%, more preferably 20%, and 10%. When the internal haze is the same as the surface haze or greater than the surface haze, the internal haze becomes the main function of the light diffusion function of the film, and 0 light scattering (with back reflection) is generated inside the film, resulting in a large total light transmittance. reduce. On the other hand, the lower limit of the internal haze is preferably 1%. A film having an internal haze of less than 1% tends to have insufficient surface haze. Further, the surface light diffusing polyester film of the present invention has a total light transmittance of 86% or more. The lower limit of the total light transmittance is preferably 87%, and the lower limit is preferably 88%.
又，光擴散性薄膜的光擴散性能例如能夠藉由影像鮮 明度來定量性評價。影像鮮明度係指通過薄膜觀察螢光燈 等的光源時之鮮明度指標，係藉由通常的方法依據Π S K -36 - 200846179 7 1 05「塑膠的光學性試驗方法」進行測定並評價之鮮明度。 影像鮮明度較小時，係表示遮蔽性良好，且光擴散性優良。 本發明的表面光擴散性聚酯薄膜在光學梳子寬度爲2 毫米的透射法，能夠得到40%以下的影像鮮明度。影像鮮 明度的上限値以20%爲較佳，上限値以15%爲更佳。影像 鮮明度以越小越佳，但是使影像鮮明度低於必要以上時， 內部霧度變高而致使總光線透射率降低。在本發明，影像 鮮明度的下限値以1%爲佳，以3%爲更佳。 ® 又，光擴散性薄膜的光擴散性能例如能夠藉由村上色 彩技術硏究所製Goniophotometer(配光曲線儀）GP-200之 藉由透射光強度來進一步進行定量性評價。將透射光強度 中之受光角度〇度的値作爲1(0)、受光角度N度的値作爲 I(N)，並依照下述的計算式所求得的透射光強度比爲S(N) 時，例如N=1度時的S(l)的値大時，因爲在0度的透射光 的周邊被擴散的透射光變多，能夠使通過薄膜所觀察到的 影像鮮明度降低，能夠得到良好的遮蔽性。本發明的表面 ® 光擴散性聚酯薄膜能夠得到s(l)爲75%以上的値。透射光 強度比越大時，表示遮蔽性越良好，且光擴散性越優良。 S(l)的値小於75%時，因爲光擴散性降低，無法得到良好 的遮蔽性，乃是不佳。 S(N) = I(N)/I(0)x 1 00 又，雖然透射光強度越大時，光擴散性越優良，但是 使透射光強度大於必要以上時，有許多情況係1(〇)降低， 結果在背光板模組之正面亮度降低。在本發明的表面光擴 -37 - 200846179 散性聚酯薄膜，s(l)的上限値以99%爲佳，以95 %爲較佳’ 以85%爲更佳。 (力學特性） 又，在本發明，因爲使用結晶性聚酯作爲薄膜的原料’ 能夠得到雙軸拉伸薄膜本來優良的耐熱性、機械強度及優 良的厚度精確度。 關於耐熱性，在1 5 0 °C之尺寸變化率於橫向、縱向的 任一者都是以6%爲佳，較佳的上限爲4%，特佳的上限爲 ^ 3%。更佳的上限爲2.5%，又更佳上限爲2%，特佳的上限 爲1 . 5 %，又特佳的上限爲1 %。另一方面，在1 5 0 °C於橫向、 縱向的尺寸變化率以較小爲佳，認爲下限爲〇%。尺寸變化 率3 %以下時，在高溫加工或是在高溫環境使用，尺寸變化 或平面性不會變差，能夠保持良好的平面性。結果，能夠 使背光板模組之光射出面的亮度均勻。又，在本發明，橫 向係指製膜時薄膜的流動方向（捲取方向）”縱向係指與其 垂直的方向。 又，在橫向、縱向.中任一者之薄膜的拉伸強度的下限 都是以lOOMPa爲佳，以130MPa爲更佳，以160MPa爲特 佳。拉伸強度爲l〇〇MPa以上時，雙軸拉伸薄膜的力學強 度能拉伸強度能夠發揮，在薄膜的加工製程不容易產生破 碎、破裂、折斷及裂開等不良。 又，本發明的表面光擴散性聚酯薄膜之厚度不均以 5.0%以下爲佳。 薄膜的厚度不均爲5.0%以下時，將薄膜捲繞於輥上 -38- 200846179 時，不容易產生皺紋或鼓起、能夠保持平面性。結果，在 背光板模組，光射出面的亮度變爲均勻，能夠達成光擴散 性薄膜的本來目的。 又’本發明的表面光擴散性聚酯薄膜在無負荷的狀 態，在loot加熱處理30分鐘後的捲曲値以5毫米以下爲 佳。 捲曲値爲5毫米以下時，例如作爲光擴散性薄膜而組 人最後製品時，在無拉伸下的作業時，處理性變爲良好。 m — 又’即便在高溫加工或高溫環境使用，亦能夠抑制產生薄 膜變形，在背光板模組能夠達成使光射出面的亮度均勻之 光擴散性薄膜的本來目的。 關於捲曲的抑制，如前述，能夠藉由控制支撐層（A) 與光擴散層（B)的熔點差異來調整，而且，爲了控制以起因 於擠壓時表背冷卻的冷卻速度差異所引起薄膜厚度方向的 結晶化度爲始、及在預熱、拉伸、冷卻、捲取等各製程所 0 賦予薄膜表背的結構差異所產生之捲曲，以應用積極地使 薄膜表背所產生的結構差異與必然性的結構差異互相補足 來使捲曲値接近零之方法爲佳。 具體上，係藉由在縱向拉伸或橫向拉伸等的拉伸製程 及熱處理製程使薄膜表背的溫度或是熱量爲不同的値，獨 立地控制薄膜表背的配向度，並採用薄膜表背的結構或兼 具物性之條件，來實現零捲曲的製膜。 又，爲了作爲在跨及全寬度範圍爲低捲曲狀態且能夠 穩定地生產之基本條件，使用厚度不均較少的拉伸處方係 -39- .200846179 是重要的。 更具體地，對於剛製膜後在縱向捲曲，係控制縱向拉 伸時之薄膜背表的的結構差異，且橫向捲曲係藉由控制橫 向拉伸及熱固定時之薄膜背表的結構差異，來製造相反方 向的內部應變，使其與必然產生之薄膜表背的結構差異所 引起的內部應變同時具有，來抑制捲曲爲佳。 又，本發明的表面光擴散性聚酯薄膜的厚度係任意， 沒有特別限制，以在25〜500微米的範爲佳，以在75〜350 β微米的範圍爲更佳。 (雙軸拉伸薄膜的製造） 在本發明，能夠滿足前述特性之方法，以使用例如以 下的製造方法爲佳。 以下，對本發明的表面光擴散性聚酯薄膜的較佳製造 方法，詳細說明含有共聚合成分（光擴散層（Β)的原料）之結 晶性聚酯係使用聚對酞酸乙二酯共聚物（以下，亦有簡稱聚 I 酯之情形）的顆粒而成之代表例。 移送上述顆粒通常係使用規定的配管藉由空氣輸送來 進行，此時爲了防止麈埃混入空氣，以使用HERA過濾器 並使用潔淨化過的空氣爲佳。此時所使用的 HERA過濾 器，係以使用公稱過濾精度爲具有截留95%以上0.5微米 以上的塵埃的性能之過濾器爲佳。 首先，係將薄膜原料之聚酯及與聚酯爲非相溶性的熱 塑性樹脂各自藉由真空乾燥或熱風乾燥進行乾燥，來使水 分率小於1 0 0 p p m。接著，計量、混合各原料並供給至擠壓 -40-Further, the light diffusing property of the light diffusing film can be quantitatively evaluated by, for example, image sharpness. The sharpness of the image refers to the sharpness index when the light source such as a fluorescent lamp is observed through a film, and is measured and evaluated in accordance with Π SK -36 - 200846179 7 1 05 "Optical Test Method for Plastics" by a usual method. degree. When the image sharpness is small, it means that the shielding property is good and the light diffusibility is excellent. The surface light diffusing polyester film of the present invention can provide image sharpness of 40% or less in a transmission method having an optical comb width of 2 mm. The upper limit of image sharpness is preferably 20%, and the upper limit is preferably 15%. The sharpness of the image is preferably as small as possible, but when the image sharpness is lower than necessary, the internal haze becomes high and the total light transmittance is lowered. In the present invention, the lower limit of the image sharpness is preferably 1%, more preferably 3%. Further, the light diffusing property of the light diffusing film can be further quantitatively evaluated by the transmitted light intensity by, for example, a Goniophotometer GP-200 manufactured by Murakami Paint Research Co., Ltd. The 値 of the received light intensity in the transmitted light intensity is 1 (0), and the 受 of the received light angle is N (I), and the transmitted light intensity ratio obtained by the following calculation formula is S (N). In the case where S(l) at the time of N=1 degrees is large, the transmitted light that is diffused around the transmitted light of 0 degrees increases, and the image sharpness observed by the film can be reduced, and the image can be obtained. Good shelter. The surface ® light diffusing polyester film of the present invention can give 値(l) of 75% or more. When the transmitted light intensity ratio is larger, it means that the shielding property is better, and the light diffusibility is more excellent. When the enthalpy of S(l) is less than 75%, since the light diffusibility is lowered, good shielding properties are not obtained, which is not preferable. S(N) = I(N)/I(0)x 1 00 Further, although the light transmittance is more excellent as the transmitted light intensity is larger, there are many cases when the transmitted light intensity is more than necessary. ) Lowering, as a result, the brightness of the front side of the backlight module is lowered. In the surface light diffusing film of the present invention, the upper limit of s(l) is preferably 99%, more preferably 95%, and more preferably 85%. (Mechanical properties) Further, in the present invention, since a crystalline polyester is used as a raw material of a film, excellent heat resistance, mechanical strength, and excellent thickness accuracy of the biaxially stretched film can be obtained. Regarding the heat resistance, the dimensional change rate at 150 ° C is preferably 6% in either the transverse direction and the longitudinal direction, and the preferred upper limit is 4%, and the particularly preferred upper limit is ^ 3%. A better upper limit is 2.5%, and a better upper limit is 2%, a particularly good upper limit is 1.5%, and a particularly good upper limit is 1%. On the other hand, the dimensional change ratio in the transverse direction and the longitudinal direction at 150 ° C is preferably small, and the lower limit is considered to be 〇%. When the dimensional change rate is 3% or less, it is used in high-temperature processing or in a high-temperature environment, and the dimensional change or planarity does not deteriorate, and good planarity can be maintained. As a result, the brightness of the light exit surface of the backlight module can be made uniform. Further, in the present invention, the lateral direction means that the flow direction (winding direction) of the film when forming a film refers to a direction perpendicular thereto. Further, the lower limit of the tensile strength of the film in either the transverse direction or the longitudinal direction is It is preferably 100 MPa, more preferably 130 MPa, and more preferably 160 MPa. When the tensile strength is l 〇〇 MPa or more, the tensile strength of the mechanical strength of the biaxially stretched film can be exerted, and the processing of the film is not Further, the surface light diffusing polyester film of the present invention has a thickness unevenness of 5.0% or less. When the thickness of the film is not more than 5.0%, the film is wound. When the roller is on -38 to 200846179, it is less likely to cause wrinkles or bulging, and the flatness can be maintained. As a result, in the backlight module, the brightness of the light exit surface becomes uniform, and the original purpose of the light diffusing film can be achieved. The surface light diffusing polyester film of the present invention is preferably in a no-load state, and the crimp entanglement after the heat treatment for 30 minutes is preferably 5 mm or less. When the crimp enthalpy is 5 mm or less, for example, as a light diffusing film When the final product of the group is used, the handleability becomes good when the work is performed without stretching. m - Also, even in high-temperature processing or high-temperature environment, film deformation can be suppressed, and the backlight module can achieve light. The original purpose of the light diffusing film having uniform brightness on the emitting surface is as follows. The suppression of the curl can be adjusted by controlling the difference in melting point between the supporting layer (A) and the light diffusing layer (B) as described above, and for controlling the cause. The difference in the cooling rate of the surface-back cooling during extrusion causes the degree of crystallization in the thickness direction of the film, and the structural difference caused by the surface of the film in the processes of preheating, stretching, cooling, and coiling. Curl is preferably applied by actively applying the structural difference between the surface of the film and the inevitable structural difference to make the crimped crucible close to zero. Specifically, it is pulled by longitudinal stretching or transverse stretching. Stretching process and heat treatment process make the temperature or heat of the film back are different, independently control the orientation of the film back, and adopt the structure or combination of the film back The condition of the property is to achieve a film formation with zero curl. Further, in order to be a basic condition capable of stable production in a low-wrinkle state across the full width range, a stretching prescription system having a small thickness unevenness is used. More specifically, in the longitudinal direction after the film is formed, the structural difference of the film back surface during longitudinal stretching is controlled, and the transverse curl is controlled by the film back when the transverse stretching and heat setting are controlled. The structural difference of the table is to produce the internal strain in the opposite direction so as to have the internal strain caused by the structural difference of the film back surface which is inevitable, so as to suppress the curl. Further, the surface light diffusing polyester film of the present invention. The thickness is arbitrary, and is not particularly limited, and is preferably in the range of 25 to 500 μm, and more preferably in the range of 75 to 350 μm. (Production of Biaxially Stretched Film) In the present invention, a method capable of satisfying the above characteristics is preferably used, for example, in the following production method. Hereinafter, a preferred method for producing the surface light diffusing polyester film of the present invention will be described in detail. The crystalline polyester containing a copolymerization component (a material of a light diffusion layer) is a polyethylene terephthalate copolymer ( Hereinafter, a representative example of the particles of the case of the poly(I) ester is also referred to. The transfer of the above-mentioned particles is usually carried out by air transportation using a predetermined pipe. In order to prevent the air from entering the air, it is preferable to use a HERA filter and use cleaned air. The HERA filter used at this time is preferably a filter having a performance of cutting dust having a nominal filtration accuracy of 95% or more and 0.5 μm or more. First, the polyester of the film raw material and the thermoplastic resin which is incompatible with the polyester are each dried by vacuum drying or hot air drying to have a water content of less than 100 p p m. Next, meter and mix the raw materials and supply them to the extrusion -40-
200846179 機，並進行熔融擠壓成爲薄片狀。而且，使用靜電 來使熔融狀態的薄片黏附於已控制表面溫度爲1 0〜 金屬製的旋轉滾筒（冷卻滾筒），並且從相反面噴吹 而冷卻固化，來得到未拉伸PET薄片。 此時，藉由將從擠壓機的熔融部、混煉部、聚合 齒輪泵、過濾器爲止的樹脂溫度控制爲2 2 0〜2 9 0 °C 隨後的聚合物管、模頭爲止的樹脂溫度控制爲2 1 °C，因爲能夠抑制劣化物等異物的產生，乃是較佳 又，熔融樹脂係在能夠保持於一定溫度2 7 5 °C 場所進行高精度過濾，用以除去樹脂中所含有的異 融樹脂的高精度過濾所使用的濾材，因爲除去樹 Si、Ti、Sb、Ge、Cu作爲主成分之凝聚物或高熔點 物之性能優良，以不鏽鋼燒結體爲佳。進行高精度站 熔融樹脂的溫度若低於275 °C時，由於濾壓上升而 原料樹脂的吐出量降低等之操作。 而且，濾材的過濾粒子尺寸（初期過濾效率爲 20微米以下，以1 5微米以下爲佳。濾材的過濾粒子 期過濾效率爲95%)大於20微米以上時，難以充分 大於20微米以上之大的異物。藉由使用過濾粒子 期過濾效率爲95%)爲20微米以下的濾材來進行燒 的高精度過濾，雖然會有生產力降低的情形，但是 到粗大粒子所引起光學缺點少的薄膜係重要的製程 在本發明，藉由使用與結晶性共聚酯爲非相溶性的 樹脂作爲添加劑，上述的高精度過濾變爲可能。在 施加法 5 0〇C 之 冷風來 k物管、 ，並將 0 〜2 9 5 〇 之任何 物。熔 脂中以 的有機 i濾時， 進行使 95%)爲 尺寸（初 •地除去 尺寸（初 1融樹脂 :爲了得 [。又， 丨熱塑性 ί此，初 -41- 200846179 期過濾效率係指依據ANSI/B93.36- 1 973所測定的數値。 爲了將光擴散層（B)與支撐層（A)共擠壓並層積，係使 用2台以上的擠壓機，來擠壓各層的原料，並使用具有多 層供料塊（例如具有方型合流部之合流塊）來使兩層合流， 且從狹縫狀的模頭擠壓成薄片狀，並使其在鑄塑滾筒上冷 卻固化來製造未拉伸薄膜。或者亦可使用多岐管模頭來代 替多層供料塊。 又，在本發明的表面光擴散性聚酯薄膜，以在至少一 ^ 方的表面具有塗布層爲佳，以在兩面具有塗布層爲更佳。 較佳的乾燥後塗布量爲0.005〜0·20克/平方公尺的範圍。 藉由在光擴散層的表面設置塗布層，能夠抑制在薄膜表面 產生反射光，能夠更提高總光線透射率。又，在與光擴散 層相反面設置塗布層，並對該塗布層的表面施加稜鏡薄片 加工或硬塗加工時，能夠賦予易黏著性。 此時，在藉由前述方法所得到的未拉伸薄膜設置塗布 0 層後，進行雙軸拉伸。可以是同時雙軸拉伸、亦可以是逐 次雙軸拉伸，藉由逐次拉伸法進行時，係對在縱或橫向進 行單軸拉伸後的薄膜設置易黏著層後在正交方向進行拉 伸，來進行雙軸拉伸。 爲了在未拉伸薄膜或單軸拉伸薄膜塗布塗布層形成用 塗布液之方法，能夠選自眾所周知的任意方法，可舉出例 如逆輥塗布法、凹版塗布法、吻合塗布法、模頭塗布法、 輥刷法、噴霧塗布法、氣動刮塗法、繞線棒塗布法、管刮 刀法、浸漬塗布法及簾流塗布法等，此等方法可單獨或組 -42- 200846179 合塗布。 從在棱鏡薄片用途或光擴散性薄膜用途，確保與其他 光學功能層之更優良的黏附性之觀點，構成塗布層之樹脂 係以共聚合聚酯樹脂、聚胺基甲酸酯系樹脂、或是丙燒酸 系樹脂之至少1種以上作爲主成分爲佳。又，從抑制在光 擴散層的表面產生反射光的觀點，亦推薦該等樹脂。又， 在構成塗布層的樹脂，前述「主成分」係意指相對於1〇〇 質量％構成該樹脂層之樹脂，前述樹脂的至少1種係含有 • 50質量％以上。 又，爲了提高薄膜的透明性，若在支撐層（A)中未含有 粒子、或是只有含有少量不阻礙透明性程度的粒子時，薄 膜的易滑性變爲不充分，會有處理性變差的情形。因此， 在上述的塗布層，爲了賦予易滑性之目的，以含有粒子爲 佳。爲了確保透明性，該等粒子使用平均粒徑極小（可見光 線的波長下）的粒子係重要的。 上述粒子可舉出碳酸鈣、磷酸鈣、二氧化矽、高嶺土、 ® 滑石、二氧化鈦、氧化鋁、硫酸鋇、氟化鈣、氟化鋰、沸 石、硫化鉬等的無機粒子；交聯高分子；草酸鈣等的有機 粒子等。以上述共聚合聚酯.樹脂作爲主體來形成塗布層 時，以二氧化矽爲特佳。因爲二氧化矽的折射率與聚酯較 爲接近，從能夠確保透明性更優良的表面光擴散性聚酯薄 膜而言，乃是最佳。 就確保薄膜的透明性、處理性及耐擦傷性而言，在塗 布層所含有的粒子之平均粒徑（藉由SEM所觀察之個數基 -43- .200846179 準的粒子平均最大直徑）爲0.005〜1·〇微米。就透明性而 言’粒子的平均粒徑的上限以0.5微米爲更佳，以〇 . 2微米 爲特佳。又，就處理性及耐擦傷性而言，粒子的平均粒徑 的下限，以〇·〇1微米爲更佳，以0.03微米爲特佳。 又，上述的粒子平均粒徑的測定係依照以下方法來進 行。 使用掃描型電子顯微鏡（SEM)拍攝粒子照片，以最小粒 子1個大小成爲2〜5毫米的倍率，測定3 0 0〜5 0 0個粒子 ^ 的最大直徑，並以其平均値作爲平均粒徑。又，求取在塗 布層所含有粒子的平均粒徑時，係使用透射型電子顯微鏡 (ΤΕΜ)，以最小粒子1個大小成爲2〜5毫米的倍率，拍攝 塗布薄膜的剖面，並求取存在於塗布層的剖面之粒子的最 大直徑。由凝聚體所構成的粒平均粒徑係使用光學顯微鏡 以倍率200倍拍攝3 00〜5 00個塗布薄膜的塗布層剖面，並 測定其最大直徑。 就確保光學用積層薄膜的透明性、黏附性、處理性及 0 耐擦傷性而言，相對於構成塗布層之組成物，塗布層中的 粒子含量以0.1〜60質量％爲佳。就透明性及黏附性而言， 粒子含量的上限以50質量％爲更佳，以40質量％爲特佳。 又，就處理性及耐擦傷性而言，粒子含量的下限以1質量 %爲更佳，以0.5質量％爲特佳。 上述粒子亦可並用2種類以上，亦可調配同種粒子而 不同粒徑者，任一者之粒子全體的平均粒徑及合計含量以 滿足上述範圍爲佳。 -44 - 200846179 接著，將依照上述方法所得到的未拉伸薄膜同時雙軸 拉伸或逐次雙軸拉伸，接著進行熱處理。 上述的雙軸拉伸在縱、橫兩方向以2·8倍以上的拉伸 倍率進行係重要的。又，在本發明所定義的拉伸倍率係指 薄膜實際上被拉伸的實際拉伸倍率。該拉伸倍率係在各拉 伸製程前後之平均單位面積的質量變化率、或是能夠藉由 在未拉伸薄膜記入格子狀的倍率標誌來把握。 縱向或橫向之任一者的拉伸倍率小於2.8倍時，所得 ^ 到薄膜的厚度不均降低，同時無法得到雙軸拉伸薄膜本來 優良的耐熱性及機械強度。又，薄膜的厚度均勻性顯著地 變差。在本發明之較佳拉伸倍率的下限3.0倍，更佳的下 限爲3.2倍。又，拉伸倍率的較佳上限爲5倍。又，較佳 拉伸溫度條件係如前述。 實施例 接著，使用實施例及比較例，來具體地說明本發明。 首先，在本發明所使用的特性値之評價方法係如下所示。 [評價方法] (1) 固有黏度 依據 JIS Κ 7 3 6 7-5，溶劑係使用苯酚（60質量％)與 1，1，2,2-四氯乙烷（40質量％)的混合溶劑，在30°C測定。 (2) 結晶熔解熱量、熔點及玻璃轉移溫度 使用SII Nano Techno logy公司製DSC6220型差示掃描 型熱量計來求取。在氮氣環境下，將樹脂試樣於30(TC加 熱熔融5分鐘後，使用液態氮急速冷卻，並以2 0 °C /分鐘的 -45- •200846179 速度將已粉碎的ι〇毫克樹脂試樣升溫，並進行差示熱量分 析。結晶熔解熱量係依照JIS-K7 1 2 1 - 1 987、9-1項所定義之 將包圍熔解尖峰溫度（Tpm)、外插熔解開始溫度（Tim)及外 插熔解結束溫溫度之DSC曲線積分來求取。又，將該熔解 尖峰溫度（Tpm)作爲熔點。而且，依據JIS-K7 1 2 1 - 1 987、9-3 項，來求取玻璃轉移溫度（Tg)。 (3) 熔融黏度 樹脂試樣的黏度係依據JIS K 7199「使用塑膠毛細管 W 流變計及狹縫模頭流變計之塑膠流動特性試驗方法」之第 5.1.3項的方法 A(毛細管模頭）來測定。使用東洋精機製 CAVIROGRAPH 1B、並使用0 1毫米、L/D=l 0的毛細管模 頭，在保持在270°C的圓筒內，塡充乾燥的樹脂試樣，並 熔融1分鐘後’在剪切速度60 8 .OsecT1下測定熔融黏度。 又，使用複數種樹脂作爲基材聚合物時，前述基材聚合物 的熔融黏度，係預先充分地混合複數種樹脂試樣後，塡充 0 在圓筒，並藉由與上述同樣的方法來測定熔融黏度。 (4) 薄膜的厚度不均 捲取橫向爲3公尺、縱向爲5公分的長度之連續的帶 狀試樣，並使用薄膜厚度連續測定機（Anritsu股份公司製） 測定薄膜厚度，並記錄在記錄器。從圖表求取厚度的最大 値（dmax)、最小値（dmin)、平均値（d)，並依照下述算出厚 度不均（％)。又，橫向的長度小於3公尺時，係連接在一起 而進行。又.，將連接部分從上述的數據刪除。 厚度不均（Q/°) = ((dmax-dmin)/d)xl00 -46- .200846179 測定係進行3次並求取其平均値，依照下述的基準來 評價。 〇：厚度不均爲5%以下 X :厚度不均爲大於5 % (5) 霧度、總光線透射率 薄膜試片的霧度（濁價）及總光線透射率係依據ns K 7 1 05「塑膠的光學特性試驗方法」來測定。使薄膜試片的 薄膜長度方向往垂直方向，並將光擴散層（B)面朝向光源側 ® 而設置，並使用日本電色工業股份公司製NDH-300A型濁 度計來測定。 (6) 內部霧度、總霧度、表面霧度 將在薄膜試片的兩面以2片塗布柏木油（塗布量：每面 2 0士10克/平方公尺）、霧度爲小於1.0%的高透明聚對酞酸 乙二酯薄膜（例如，東洋紡績公司製、A43 00、厚度1〇〇微 米）夾在一起而成者，作爲內部霧度測定用試料。又，將2 _ 片該高明聚對酞酸乙二酯薄膜疊合而成者作空白試料。 接著，依照（5)所記載的方法測定內部霧度測定用試料 及空白試料的霧度。並且，從內部霧度測定用試料的霧度 値減去空白試料的霧度値來求取內部霧度。又，將依照（5 ) 所記載的方法所測定之在薄膜試片單體的霧度作爲總霧 度，從總霧度減去內部霧度來求取表面霧度。 (7) 影像鮮明度 將依據JIS K 7105「塑膠的光學特性試驗方法」影像 鮮明度，依照透射法來測定。將薄膜試片的薄膜長度方向 -47- 200846179 作爲垂直方向，並將光擴散層（B)面朝向光源側來測定。測 定器係使用SUGA試驗機公司製ICM-1T型影像鮮明性測 定器。 (8)光擴散性 光擴散性係使用村上色彩技術硏究所製Goniophotometer (配光曲線儀）GP-200來測定。光源係使用鹵素燈（12V、 5 0W)，光源發出的光係通過聚光透鏡、針孔、平行光管而 以水平的平行光的方式射出後，藉由透射率爲1 %的ND濾 ^ 光器減光而使用。光源光束光圈爲10.5毫米，受光器的受 光光圈爲9.1毫米。以試料之薄膜光擴散層的面作爲光源 側，並以薄膜主面係與光源光束垂直、且薄膜的縱向係上 下的方式將薄膜試片安裝在試料保持器。使光源光束在同 軸上延長的方向爲〇度，並使受光器以光源光束的光軸與 薄膜的入射面的交點作爲中心的方式在水平方向旋轉，以 0.1度刻度在-80度至+80度的範圍測定透射光強度。 _ 將依照上述方法所測定之角度〇度的透射光強度作爲 1(0)，並將角度±N度的透射光強度作爲I(N)時，將依照下 述的計算式所求得的透射光強度比S(N)[%]作爲光擴散性 的指標。在本發明係使用S(l)，其被認定係與通過光擴散 性薄膜所觀察到影像鮮明性互相有關聯之値。 S(l)爲75%以上時，評價爲〇，S(l)爲小於75%時，評價爲X。 S(N) = I(N)/I(0)x 100 (9)拉伸強度 依據：FIS C 23 1 8- 1 997 5.3.3(拉伸強度及延伸率）來測定。 -48- .200846179 (10) 尺寸變化率 . 依據Jis C 2 3 1 8 - 1 997 5.3.4(尺寸變化）來測定。 (11) 面配向係數（△ P) 依據JIS K 7 1 42- 1 996 5.1 (A法），使用鈉d線作光源 並藉由阿貝折射計，來測定薄膜長度方向的折射率（nx)、 寬度方向的折射率（ny)及厚度方向的折射率（nz)，並依照下 述式來算出面配向係數（ΔΡ)。 Δ P = (nx + ny)/2-nz β (12)捲曲値 將薄膜單片狀地切取縱向1〇〇毫米、橫向50毫米，並 在無負荷的狀態於100 °C加熱處理30分鐘後，使薄膜的凸 部朝下而靜置在水平的玻璃板上，使用規尺並以最小刻度 0.5毫米單位測定玻璃板與升起的薄膜4個角落的下端之 垂直距離，來求取該4個位置的測定値之平均値。對3個 薄膜試片進行同樣的測定，並將該平均値作爲捲曲値，且 依照下述的基準來評價。 〇：捲曲値爲5毫米以下 x :捲曲値爲5毫米以上 實施例1 (1)結晶性同元聚酯（Ml)的製造 將酯化反應罐升溫，在到達2 0 0 °C的時點，加入由8 6.4 質量份對酞酸及64.4質量份乙二醇所構成的漿體，並邊攪 拌邊添加0 · 0 1 7質量份三氧化銻及0.1 6質量份三乙胺。接 著，進行加壓升溫，並在表壓爲3.5kgf/cm2、240°C的條件， -49- 200846179 進行加壓酯化反應。隨後，使酯化反應罐內恢復常β ’並 添加0.071質量份四水合乙酸鎂 '接著添加0.014質量份磷 酸三甲酯。而且以15分鐘升溫至2601：，添加0·012質量 份磷酸三甲酯、接著添加0.003 6質量份乙酸鈉。在15分 鐘後，將所得到的酯化反應生成物移送至縮聚反應罐’並 在減壓下慢慢地從2 6 0 °C升溫至2 8 0 °C，且在2 8 5 °C進行縮 聚反應至達到規定的固有黏度爲止。 縮聚反應結束後，使用過濾粒子尺寸5微米（初期過濾 效率：95%)的耐綸製過濾器進行過濾處理，並從噴嘴股線 狀地擠出，且使用已預先進行過濾處理（孔徑：1微米以下） 過的冷卻水將其冷卻、固化，且切割成顆粒狀。所得到的 結晶性同元聚酯（Ml)之結晶熔解熱爲3 5mJ/mg、熔點爲256 °C、固有黏度爲0.56dl/g、熔融黏度爲91Pa · s、Sb含量 爲144ppm、Mg含量爲58 ppm、P含量爲40 ppm，顏色L 値爲5 6 · 2、顏色b値爲1 .6。又，實質上未含有惰性粒子及 內部析出粒子。 (2) 共聚合聚酯樹脂（M2)的製造 以1 0 0莫耳％酞酸單位作爲芳香族二羧酸成分、以7 〇 莫耳％乙二醇及30莫耳％新戊二醇作二醇成分，依據（M1) 的製造方法來製造固有黏度爲 〇.59dl/g、熔融黏度爲 121Pa*s的共聚合聚酯樹脂（M2)。 (3) 苯乙烯（M3) 使用熔融黏度爲l47Pa · s的聚苯乙烯樹脂（ps)。 (4) 塗布液（M4)的調製 -50- 200846179 將95質量份對酞酸二甲酯、95質量份異酞酸二甲酯、 35質量份乙二醇、145質量份新戊二醇、0·1質量份乙酸鋅 及0.1質量份三氧化銻加入反應容器’並在180 °C進行酯交 換反應3小時。接著’添加6·0質量份5-鈉磺酸基異酞酸’ 在2 4 0 °C以1小時進彳了酯化反應後’在2 5 0 °C減壓下（1 0〜 0 · 2毫米H g )，以2小時進行縮聚反應’來得到數量平均分 子量爲19,5〇〇的共聚合聚酯系樹脂。 將7 · 5質量份所得到的共聚合聚酯系樹脂的3 0質量％ 水分散液、1 1 ·3質量份以亞硫酸酸氫鈉嵌段而成之含有異 氰酸酯基的自交聯型聚胺基甲酸酯系樹脂的20質量％水溶 液、0.3質量份有機錫系觸媒、3 9.8質量份水及3 7 · 4質量 份異丙醇各自混合° 而且，添加〇 · 6質量份氟系非離子型界面活性劑的1 0 質量％水溶液、2·3質量份粒子A之膠體二氧化矽（平均粒 徑40奈米）的20質量％水分散液、0.5質量份粒子B之乾 式法二氧化矽（平均粒徑200奈米、平均一次粒徑40奈米） 的3 . 5質量％水分散液。接著，使用5質量％的碳酸氫鈉水 溶液將塗布液的PH調整爲6·2,並使用過濾粒子尺寸（初期 過濾效率：95%)爲10微米的氈型聚丙烯製過濾器進行精密 過濾，來調整塗布液（M4)。 (5)表面光擴散性聚酯薄膜的製造 將光擴散層（B)的原料之65質量份結晶性同元聚酯 (Ml)、20質量份共聚合聚酯（M2)及15質量份聚苯乙烯（M3) 各自在1 3 5 °C減壓乾燥（1托）6小時後，混合並供給至擠壓 200846179 機2。又’支撐層（A)的原料之7 6.7質量份結晶性同元聚醋 (Ml)、23.3質量份共聚合聚酯（M2)各自減壓乾燥（1托）6小 時後，混合並供給至擠壓機1。 使各擠壓機的熔融部、混煉部、聚合物管、齒輪泵、 過濾器爲止的設定溫度爲275 °C，使過濾器後的聚合物管 的設定溫度爲27 0°C，將從擠壓機2及擠壓機1所供給的 各原料使用2層合流塊層積，並從噴嘴薄片地熔融擠出。 又’（A)層及（B)的厚度比率係使用各層的齒輪泵以成 爲9 0對1 0的方式控制。又，在上述的過濾器，任一者都 是使用不鏽鋼燒結體的濾材（公稱過濾精度：截留9 5 % 1 0 微米粒子）。又，噴嘴的溫度係以被擠出的樹脂溫度爲275 °C的方式控制。 使用靜電施加法使被擠出的樹脂黏附於表面溫度爲3 0 °C的冷卻轉筒而冷卻固化，並製成未拉伸薄膜。此時，使 (A)層面作爲接觸冷卻轉筒的面。又，冷卻轉牽引未拉伸薄 膜的速度爲12公尺/分鐘。 將所得到的未拉伸薄膜使用預熱輥加熱至79 °C，並藉 由不同周速的輥之間，在縱向拉伸3.4倍。此時使用紅外 線放射溫度計監控薄膜溫度，並以薄膜的最高溫度爲1 00 °C的方式控制加熱器溫度。 拉伸結束後，將所得到的單軸拉伸薄膜冷卻至5 0 °C 後，在薄膜的一面（A層側）塗布塗布液（M4)。塗布液係以 濕式塗布量爲約1 5克/平方公尺的方式控制。隨後，使用 乾燥爐乾燥塗布面。 -52- 200846179 使用夾子把持具有塗布層之單軸拉伸薄膜的兩端，並 引導至拉幅器，預熱至1 2 0 °C後，於1 3 5 °C在橫向拉伸2.5 倍後，於140°C在橫向拉伸1.6倍，進而於240 °C熱處理10 秒，並在冷卻至60°C的過程在橫向進行3. 3 %的鬆弛處理， 來製成總厚度爲1 00微米的表面光擴散性聚酯薄膜。 又’爲了測定各層的聚酯之熔點及固有黏度，暫時停 止（B)層的吐出而採取（A)層單獨的未拉伸薄膜。同樣地， 暫時停止（A)層的吐出而採取（B)單獨的未拉伸薄膜。 •⑷薄膜特性 本實施例1所得到的薄膜特性係如表1所示。由表1 可以得知，本發明所得到的表面光擴散性聚酯薄膜具有雙 軸拉伸薄膜本來優良的耐熱性及機械強度、厚度精確度。 又’內部霧度小且具有高光線透射率。而且，得知總霧度 的大部分係藉由表面霧度來賦予，且其光擴散性亦優良。 實施例2 0 <結晶性共聚合聚酯樹脂（M5)的製造> 構成成分係包含以1 〇 〇莫耳％對酞酸單位作爲芳香族 二羧酸成分；及以70莫耳％乙二醇單位及30%環己烷二甲 醇單丨1/1作爲二醇成分，來製造固有黏度爲〇6〇dl/g、熔融 黏度爲197Pa*s的結晶性共聚合聚酯樹脂（M5)。 在實施例1，以共聚合成分之含有率（相對於二醇成分 總量之共聚合成分的莫耳比率）、及聚苯乙烯的含量係如表 1所示組成的方式，並使用樹脂Ml、M3、M5來調整（A)、 (B)各層的原料調配。除了上述以外係使用與實施例1同樣 -53 - •200846179 的方法，來製造表面光擴散性聚酯薄膜。 本實施例2所得到的薄膜特性係如表1所示。從表i 能夠得知本實施例2與實施例1同樣地具有優良的特性。 實施例3 除了在薄膜的兩面塗布層以外，使用與實施例1同樣 的方法來製造表面光擴散性聚酯薄膜。塗布係使用與實施 例1同樣的材料、方法，並兩面同時進行，以兩面的濕式 塗布量都是約15克/平方公尺的方式控制。 ® 所得到薄膜的特性係如表1所示。得知本實施例3藉 由在光擴散面設置塗布層，能夠比實施例1更提高總光線 透射率。 實施例4 在實施例1，以共聚合成分之含有率、及聚苯乙烯的 含量係如表1所示組成的方式，並使用樹脂Μ 1〜Μ 3來調 整（A)、（Β)各層的原料調配。又，以（Α)層及（Β)的厚度比率 0 爲96對4的方式，來控制各擠壓機的齒輪泵。在製造未拉 伸薄膜時，以雙軸拉伸後的薄膜厚度爲250微米的方式， 來調整冷卻轉筒的牽引速度。又，沿著冷卻轉筒的外周設 置多導管（冷卻風的吹出噴嘴及吸引噴嘴係交替地連續配 置而成），並從離開冷卻轉筒約30毫米的位置將（Β)層面空 氣冷卻。除了上述以典，依照與實施例1同樣的方法，來 製造未拉伸薄膜。 接著，將所得到的未拉伸薄膜，使用與實施例1同樣 的設備，並使用表1所記載的條件來進行縱向拉伸、塗布、 -54- .200846179 橫向拉伸及熱處理’來製造總厚度爲250微米的表面光擴 散性聚酯薄膜。塗布係使用與實施例1同樣的材料、方法， 並兩面同時進行，以兩面的濕式塗布量都是約15克/平方 公尺的方式控制。 所得到薄膜的特性係如表1所示。在本實施例，因爲 在支擦層（A)使用結晶性同元聚酯，得知具有比實施例1優 良的強度、及與實施例1同等的優良耐熱性。又，具有非 馨 常優良的厚度精確度。另一方面，在支撐層（A)及光擴散層 (B)，因爲原料聚酯的熔點能觀察到若干差異，能夠認定有 伴隨而來的若干捲曲，但是實用上係在完全無問題的範圍。 又’在本實施例4，內部霧度比實施例1〜3更小，且 表面霧度更大。伴隨著，同時提高了總光線透射率及光擴 散性的特性。在實施例4，伴隨著使其總厚度變厚，在冷 卻轉筒的牽引速度、亦薄膜的製造速度變慢。薄膜的製造 速度變慢時’預測縱向拉伸時薄膜承受應力降低。藉此， φ 認爲在光擴散層的添加劑周圍所顯現的空隙減少，如上述 結果，內部霧度變小。 實施例5 在實施例4，以共聚合成分之含有率、及聚苯乙烯的 含S係如表1所示組成的方式，並使用樹脂Μ 1〜M3來調 整（Β)層的原料調配。又，以（Α)層及（Β)的厚度比率爲9〇 對1 〇的方式’來控制各擠壓機的齒輪泵。此外使用與實施 4 H _的方法，來製造總厚度爲25〇微米的表面光擴散 性聚酯薄膜。 -55- .200846179 所得到薄膜的特性係如表1所示。在本實施例5，內 部霧度比實施例4少許上升，總光線透射率亦少許下降， 但是具有充分優良的特性。 實施例6 除了在薄膜的一面（B層側）設置塗布層以外，使用與實 施例4完全同樣的方法，來製造表面光擴散性聚酯薄膜。 所得到薄膜的特性係如表1所示。在本實施例6，總 光線透射率比實施例4少許降低，但是具有充分優良的特 響性。 實施例7、8 在實施例4’以共聚合成分之含有率、及聚苯乙烯的 含量係如表1所示組成的方式，並使用樹脂Μ 1〜M3麥調 整（Β)的原料調配。又，以（Α)層及（Β)的厚度比率爲84對 1 6的方式，來控制各擠壓機的齒輪泵。此外使用與實施例 4同樣的方法，來製造總厚度爲〗8 8微米的表面光擴散性 φ 聚酯薄膜。所得到的薄膜特性係如表1所示。 實施例9〜1 1 在實施例4，以共聚合成分之含有率、及聚苯乙烯的 含量係如表1所示組成的方式，並使用樹脂Μ 1〜M3來調 整（Β)的原料調配。又，以（Α)層及（Β)的厚度比率爲89對 1 1的方式，來控制各擠壓機的齒輪泵。在製造未拉伸薄膜 時’係以雙軸拉伸後的薄膜厚度爲188微米的方式，來調 整冷卻轉筒的牽引速度。此外使用與實施例4同樣的方 法’來製造未拉伸薄膜。 -56- 200846179 接著，將所得到的未拉伸薄膜，使用與實施例1同樣 的設備，並使用表1所記載的條件來進行縱向拉伸、塗布、 橫向拉伸及熱處理，來製造總厚度爲1 8 8微米的表面光擴 散性聚酯薄膜。塗布係使用與實施例4同樣的材料、方法， 並兩面同時進行，以兩面的濕式塗布量都是約15克/平方 公尺的方式控制。所得到薄膜的特性係如表1所示。 比較例1 在實施例1，將光擴散層（B)的原料調配變更爲85質量 份結晶性同元聚酯（Ml)、及15質量份聚苯乙烯（M4)的混合 物。又’將支撐層（A)的原料變更爲結晶性同元聚酯（Ml)。 此外使用與實施例1同樣的方法，來製造總厚度爲1 0 〇微 米的聚酯薄膜。 所得到薄膜的特性係如表1所示。在本比較例1，因 爲面配向係數太大，內部霧度大、總光線透射率大幅度地 降低。又，在聚苯乙烯的周圍形成有空隙。 _ 比較例2 在實施例5,以（B)層的共聚合成分的含量成爲22莫耳 %的方式調整樹脂Μ 1〜Μ 3。使用與實施例1同樣的設置， 並以表1所記載的條件，進行縱向拉伸、塗布、橫向拉伸 及熱處理，來製造總厚度爲25 0微米的表面光擴散性聚酯 薄膜。塗布係使用與實施例1同樣的材料、方法，並兩面 同時進行，以兩面的濕式塗布量都是約1 5克/平方公尺的 方式控制。 所得到薄膜的特性係如表1所示。雖然本比較例的薄 -57- 200846179 膜之總光線透射率高、光擴散性亦優良，但是面配向係數 大、尺寸安定性差、捲曲値亦大。所得到的薄膜之捲曲劇 烈，而無法進行熱尺寸安定性的評價。200846179 Machine, and melt-extruded into a flake. Further, static electricity was used to adhere the sheet in a molten state to a rotating drum (cooling drum) having a controlled surface temperature of 10 to metal, and was blown from the opposite surface to be cooled and solidified to obtain an unstretched PET sheet. At this time, the resin temperature from the melting section of the extruder, the kneading section, the polymerization gear pump, and the filter is controlled to 2 2 0 to 2 0 0 ° C, followed by the resin tube and the resin of the die. The temperature is controlled to 2 1 ° C. Since it is possible to suppress the generation of foreign matter such as deteriorated substances, it is preferable that the molten resin is subjected to high-precision filtration at a temperature of 27.5 ° C at a constant temperature to remove the resin. The filter medium used for high-precision filtration of the contained isomer resin is excellent in the performance of removing aggregates of Si, Ti, Sb, Ge, and Cu as main components or high-melting substances, and is preferably a stainless steel sintered body. When the temperature of the molten resin is lower than 275 °C, the amount of discharge of the raw material resin is lowered due to an increase in the filtration pressure. Further, when the filter particle size of the filter medium (initial filtration efficiency is 20 μm or less, preferably 15 μm or less, and the filtration particle filtration efficiency of the filter medium is 95%) is more than 20 μm or more, it is difficult to sufficiently larger than 20 μm or more. foreign matter. By using a filter material having a filtration particle-stage filtration efficiency of 95%) of 20 μm or less to perform high-precision filtration, although there is a case where productivity is lowered, an important process for a film having a small optical defect caused by coarse particles is In the present invention, by using a resin which is incompatible with the crystalline copolyester as an additive, the above-described high-precision filtration becomes possible. Apply a cold air of 50 °C to the k-tube, and place anything from 0 to 2 9 5 . When the organic i filter is used in the melt, 95%) is used for the size (the initial removal of the size (the first 1 melt resin: in order to get [. Also, 丨 thermoplastic 此 this, the initial -41-200846179 period filtration efficiency refers to According to the number measured by ANSI/B93.36-1 973. In order to co-extrude and laminate the light diffusion layer (B) and the support layer (A), two or more extruders are used to extrude the layers. Raw material, and using a multi-layer feeding block (for example, a confluent block having a square junction) to join the two layers, and extruding from a slit-like die into a sheet shape, and cooling it on a casting drum Curing to produce an unstretched film. Alternatively, a multi-tube die may be used instead of the multilayer feed block. Further, in the surface light diffusing polyester film of the present invention, it is preferred to have a coating layer on at least one surface. It is more preferable to have a coating layer on both sides. The preferred amount of coating after drying is in the range of 0.005 to 0·20 g/m 2 . By providing a coating layer on the surface of the light diffusion layer, reflection on the surface of the film can be suppressed. Light, which can increase the total light transmittance. When the coating layer is provided on the opposite surface of the layer, and the surface of the coating layer is subjected to enamel sheet processing or hard coating processing, adhesion can be imparted. At this time, the unstretched film obtained by the above method is coated with 0 layers. After that, biaxial stretching is carried out, which may be simultaneous biaxial stretching or sequential biaxial stretching, and when it is carried out by the sequential stretching method, it is easy to set the film after uniaxial stretching in the longitudinal or transverse direction. After the adhesive layer is stretched in the orthogonal direction, the biaxial stretching is carried out. The method for applying the coating liquid for forming a coating layer to an unstretched film or a uniaxially stretched film can be selected from any known method. For example, reverse roll coating method, gravure coating method, conformal coating method, die coating method, roll brush method, spray coating method, pneumatic blade coating method, wire bar coating method, tube doctor method, dip coating method, and curtain coating The method can be applied separately or in combination with -42-200846179. From the viewpoint of ensuring better adhesion to other optical functional layers in the use of prism sheets or light diffusing films, the coating layer is formed. The resin is preferably a main component of at least one of a copolymerized polyester resin, a polyurethane resin, or an alkoxylate resin, and further suppresses generation of reflected light on the surface of the light diffusion layer. In the resin constituting the coating layer, the term "main component" means a resin constituting the resin layer with respect to 1% by mass, and at least one of the resins contains 50 mass. Further, in order to improve the transparency of the film, if the support layer (A) does not contain particles or contains only a small amount of particles which do not inhibit the degree of transparency, the slipperiness of the film may be insufficient. In the case of the above-mentioned coating layer, it is preferable to contain particles for the purpose of imparting slipperiness. In order to ensure transparency, the particles have an extremely small average particle diameter (at a wavelength of visible light). Particle systems are important. Examples of the particles include inorganic particles such as calcium carbonate, calcium phosphate, cerium oxide, kaolin, talc, titanium dioxide, aluminum oxide, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide; and a crosslinked polymer; Organic particles such as calcium oxalate. When the coating layer is formed by using the above-mentioned copolymerized polyester resin as a main component, cerium oxide is particularly preferable. Since the refractive index of cerium oxide is close to that of polyester, it is preferable from a surface light diffusing polyester film which can ensure transparency more. In order to ensure the transparency, handleability and scratch resistance of the film, the average particle diameter of the particles contained in the coating layer (the average maximum diameter of the particles observed by SEM-43-.200846179) is 0.005~1·〇micron. In terms of transparency, the upper limit of the average particle diameter of the particles is more preferably 0.5 μm, and particularly preferably 2 μm. Further, in terms of handleability and scratch resistance, the lower limit of the average particle diameter of the particles is more preferably 〇·〇1 μm, and particularly preferably 0.03 μm. Further, the above measurement of the average particle diameter of the particles was carried out in accordance with the following method. A photograph of the particles was taken using a scanning electron microscope (SEM), and the maximum diameter of 3 0 0 to 500 particles was measured with a minimum particle size of 2 to 5 mm, and the average 値 was used as the average particle diameter. . Further, when the average particle diameter of the particles contained in the coating layer is determined, a cross section of the coated film is taken and a thickness is obtained by using a transmission electron microscope (magnification) with a minimum particle size of 2 to 5 mm. The maximum diameter of the particles in the cross section of the coating layer. The average particle diameter of the particles composed of the aggregates was taken by an optical microscope at a magnification of 200 times to take a coating layer cross section of 300 to 500 coated films, and the maximum diameter thereof was measured. In order to ensure the transparency, adhesion, handleability, and scratch resistance of the optical laminated film, the content of the particles in the coating layer is preferably 0.1 to 60% by mass based on the composition constituting the coating layer. In terms of transparency and adhesion, the upper limit of the particle content is more preferably 50% by mass, and particularly preferably 40% by mass. Further, in terms of handleability and scratch resistance, the lower limit of the particle content is more preferably 1% by mass, and particularly preferably 0.5% by mass. The above-mentioned particles may be used in combination of two or more kinds, and the same kind of particles may be blended, and the average particle diameter and the total content of the particles in any of the particles may be in the above range. -44 - 200846179 Next, the unstretched film obtained according to the above method is simultaneously biaxially stretched or sequentially biaxially stretched, followed by heat treatment. The biaxial stretching described above is important in the longitudinal and transverse directions at a stretching ratio of 2·8 or more. Further, the draw ratio defined in the present invention means the actual draw ratio at which the film is actually stretched. The draw ratio is determined by the mass change rate of the average unit area before and after each stretch process, or by the mark of the magnification in which the unstretched film is marked in a lattice shape. When the draw ratio of either the machine direction or the cross direction is less than 2.8 times, the thickness unevenness of the film is lowered, and the excellent heat resistance and mechanical strength of the biaxially stretched film cannot be obtained at the same time. Further, the thickness uniformity of the film is remarkably deteriorated. The lower limit of the preferred draw ratio of the present invention is 3.0 times, and the lower limit is 3.2 times. Further, the preferred upper limit of the draw ratio is 5 times. Further, the preferred stretching temperature conditions are as described above. EXAMPLES Next, the present invention will be specifically described using examples and comparative examples. First, the evaluation method of the characteristics used in the present invention is as follows. [Evaluation method] (1) The intrinsic viscosity is based on JIS Κ 7 3 6 7-5, and the solvent is a mixed solvent of phenol (60% by mass) and 1,1,2,2-tetrachloroethane (40% by mass). Measured at 30 °C. (2) Crystal melting heat, melting point, and glass transition temperature were determined using a DSC6220 differential scanning calorimeter manufactured by SII Nano Technology. The resin sample was heated and melted for 30 minutes in a nitrogen atmosphere, and then rapidly cooled with liquid nitrogen, and the pulverized ι 〇 mg resin sample was taken at a rate of -45- •200846179 at 20 ° C /min. The temperature is raised and the differential heat analysis is performed. The heat of crystal melting is surrounded by the melting peak temperature (Tpm), the external melting start temperature (Tim) and the outside as defined in JIS-K7 1 2 1 - 1 987, 9-1. The melt melting solution is obtained by integrating the DSC curve at the end of the temperature. Further, the melting peak temperature (Tpm) is taken as the melting point. Further, the glass transition temperature is determined according to JIS-K7 1 2 1 - 1 987, 9-3. (Tg) (3) The viscosity of the melt-resistance resin sample is based on the method of Section 5.1.3 of JIS K 7199 "Testing methods for plastic flow characteristics using a plastic capillary W rheometer and a slit die rheometer". A (capillary die) was used for the measurement. Using a Toyo Seiki CAVIROGRAPH 1B and using a capillary die of 0 1 mm and L/D = 10, the dry resin was tested in a cylinder maintained at 270 °C. After melting for 1 minute, the melt viscosity was measured at a shear rate of 60 8 .OsecT1. Further, when a plurality of resins are used as the base polymer, the melt viscosity of the base polymer is sufficiently mixed with a plurality of resin samples in advance, and then the mixture is filled in a cylinder, and the same method as described above is used. The thickness of the film was measured. (4) Thickness of the film was measured by winding a continuous strip-shaped sample having a length of 3 mm in the transverse direction and a length of 5 cm in the longitudinal direction, and measuring the film thickness using a film thickness continuous measuring machine (manufactured by Anritsu Co., Ltd.). And recorded in the recorder. The maximum 値(dmax), minimum 値(dmin), and average 値(d) of the thickness are obtained from the chart, and the thickness unevenness (%) is calculated according to the following. Further, the lateral length is less than 3 When the meter is used, it is connected together. Also, the joint is deleted from the above data. Thickness unevenness (Q/°) = ((dmax-dmin)/d)xl00 -46- .200846179 The average enthalpy is obtained three times and evaluated according to the following criteria: 〇: thickness is not more than 5% X: thickness is not more than 5% (5) haze, total light transmittance, film of the test piece Degree (turbidity) and total light transmittance are based on ns K 7 1 05 "Plastic The test method was used to measure the film length of the film test piece in the vertical direction, and the light diffusion layer (B) surface was set toward the light source side ®, and the NDH-300A type turbidity system manufactured by Nippon Denshoku Industries Co., Ltd. was used. (6) Internal haze, total haze, surface haze will be coated on two sides of the film test piece with 2 pieces of cedar oil (coating amount: 20 g / 10 g / m ^ 2 per side), fog A highly transparent polyethylene terephthalate film (for example, manufactured by Toyobo Co., Ltd., A43 00, thickness: 1 μm) having a degree of less than 1.0% is used as a sample for internal haze measurement. Further, a blank sample was prepared by laminating 2 _ sheets of the high-density poly(ethylene terephthalate) film. Next, the haze of the internal haze measurement sample and the blank sample was measured in accordance with the method described in (5). Then, the internal haze was obtained by subtracting the haze of the blank sample from the haze of the internal haze measurement sample. Further, the haze of the film test piece alone measured in accordance with the method described in (5) was taken as the total haze, and the internal haze was subtracted from the total haze to obtain the surface haze. (7) Image sharpness It is measured according to the transmission method in accordance with JIS K 7105 "Test method for optical properties of plastics". The film length direction -47 - 200846179 of the film test piece was measured as a vertical direction, and the light diffusion layer (B) surface was measured toward the light source side. The calibrator was an ICM-1T image sharpness determinator manufactured by SUGA Test Machine Co., Ltd. (8) Light diffusibility The light diffusivity was measured using a Goniophotometer (Glowing Light Meter) GP-200 manufactured by Murakami Color Technology Research Institute. The light source is a halogen lamp (12V, 50W), and the light emitted from the light source is emitted by horizontal condensing light through a collecting lens, a pinhole, and a collimator, and is ND filtered by a transmittance of 1%. The light is used for dimming. The aperture of the light source beam is 10.5 mm, and the aperture of the light receiver is 9.1 mm. The film test piece was attached to the sample holder so that the surface of the thin film light-diffusing layer of the sample was used as the light source side, and the film main surface was perpendicular to the light source beam and the longitudinal direction of the film was up-and-down. The direction in which the light source beam is extended on the coaxial line is twisted, and the light receiver is rotated in the horizontal direction with the intersection of the optical axis of the light source beam and the incident surface of the film as a center, at -80 degrees to +80 at 0.1 degree scale. The range of degrees measures the transmitted light intensity. _ When the transmitted light intensity of the angle width measured according to the above method is 1 (0) and the transmitted light intensity of the angle ± N degrees is taken as I (N), the transmission obtained according to the following calculation formula is used. The light intensity ratio S(N) [%] is used as an indicator of light diffusibility. In the present invention, S(l) is used, which is identified as being related to the sharpness of the image observed by the light diffusing film. When S(l) is 75% or more, the evaluation is 〇, and when S(l) is less than 75%, it is evaluated as X. S(N) = I(N)/I(0)x 100 (9) Tensile strength According to: FIS C 23 1 8- 1 997 5.3.3 (tensile strength and elongation). -48- .200846179 (10) Dimensional change rate. Measured according to Jis C 2 3 1 8 - 1 997 5.3.4 (dimension change). (11) Surface alignment coefficient (Δ P) According to JIS K 7 1 42- 1 996 5.1 (method A), the refractive index (nx) in the longitudinal direction of the film is measured by using a sodium d-line as a light source and an Abbe refractometer. The refractive index (ny) in the width direction and the refractive index (nz) in the thickness direction, and the surface alignment coefficient (ΔΡ) was calculated according to the following formula. Δ P = (nx + ny)/2-nz β (12) Curly 値 The film was cut into a sheet of 1 mm in the longitudinal direction and 50 mm in the transverse direction, and heat-treated at 100 ° C for 30 minutes in an unloaded state. The convex portion of the film is placed facing down and rested on a horizontal glass plate, and the vertical distance between the glass plate and the lower end of the four corners of the raised film is measured using a gauge and a minimum scale of 0.5 mm. The average of the measured positions is 値. The same measurement was carried out on the three film test pieces, and the average enthalpy was used as a crimp enthalpy, and evaluated according to the following criteria. 〇: Curl 値 is 5 mm or less x: Curl 値 is 5 mm or more. Example 1 (1) Production of crystalline homopolyester (Ml) The esterification reactor is heated, and when it reaches 200 ° C, A slurry composed of 8 6.4 parts by mass of p-citric acid and 64.4 parts by mass of ethylene glycol was added, and 0.07 parts by mass of antimony trioxide and 0.16 parts by mass of triethylamine were added with stirring. Subsequently, the temperature was raised by pressurization, and the pressure esterification reaction was carried out under the conditions of a gauge pressure of 3.5 kgf/cm2 and 240 °C, -49-200846179. Subsequently, the inside of the esterification reaction tank was returned to normal ?' and 0.071 parts by mass of magnesium acetate tetrahydrate was added, followed by the addition of 0.014 parts by mass of trimethyl phosphate. Further, the temperature was raised to 2601 at 15 minutes, and 0. 012 parts by mass of trimethyl phosphate was added, followed by 0.003 parts by mass of sodium acetate. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction tank' and slowly heated from 260 ° C to 280 ° C under reduced pressure, and at 285 ° C. The polycondensation reaction is carried out until the specified intrinsic viscosity is reached. After completion of the polycondensation reaction, filtration treatment was carried out using a nylon filter having a filter particle size of 5 μm (initial filtration efficiency: 95%), and extruded from the nozzle strands in a line shape, and filtration treatment was performed in advance (pore diameter: 1 The cooling water that passes below micron is cooled, solidified, and cut into pellets. The obtained crystalline homopolyester (Ml) has a crystal heat of fusion of 35 mJ/mg, a melting point of 256 ° C, an intrinsic viscosity of 0.56 dl/g, a melt viscosity of 91 Pa·s, a Sb content of 144 ppm, and a Mg content. It is 58 ppm, the P content is 40 ppm, the color L 値 is 5 6 · 2, and the color b 値 is 1.6. Further, substantially no inert particles and internal precipitated particles are contained. (2) The copolymerized polyester resin (M2) is produced by using 100% by mole of decanoic acid as the aromatic dicarboxylic acid component, 7 〇 mol% ethylene glycol, and 30 mol% neopentyl glycol. The diol component was produced according to the production method of (M1), and a copolymerized polyester resin (M2) having an intrinsic viscosity of 〇59 dl/g and a melt viscosity of 121 Pa*s was produced. (3) Styrene (M3) A polystyrene resin (ps) having a melt viscosity of 147 Pa·s was used. (4) Preparation of coating liquid (M4) -50-200846179 95 parts by mass of dimethyl phthalate, 95 parts by mass of dimethyl isononanoate, 35 parts by mass of ethylene glycol, 145 parts by mass of neopentyl glycol, 0.1 part by mass of zinc acetate and 0.1 part by mass of antimony trioxide were added to the reaction vessel' and transesterification was carried out at 180 ° C for 3 hours. Then 'add 6·0 parts by mass of 5-sodium sulfonate isononanoic acid' at a temperature of 2400 °C for 1 hour, and then under reduced pressure at 250 °C (1 0~0 · 2 mm H g ), a polycondensation reaction was carried out for 2 hours to obtain a copolymerized polyester resin having a number average molecular weight of 19,5 Å. 7 parts by mass of the obtained 30% by mass aqueous dispersion of the copolymerized polyester resin and 11.3 parts by mass of the self-crosslinking type polycondensate containing the isocyanate group blocked by sodium hydrogen sulfite a 20% by mass aqueous solution of a urethane-based resin, 0.3 parts by mass of an organotin-based catalyst, 39.8 parts by mass of water, and 37.7% by mass of isopropyl alcohol are each mixed. Further, 6 parts by mass of fluorine is added. 10% by mass aqueous solution of nonionic surfactant, 20% by mass of colloidal ceria (average particle size of 40 nm) of water dispersion of 20% by mass, and dry mass of 0.5 part by mass of particle B 5.5% by mass aqueous dispersion of cerium oxide (having an average particle diameter of 200 nm and an average primary particle diameter of 40 nm). Then, the pH of the coating liquid was adjusted to 6.2 using a 5% by mass aqueous solution of sodium hydrogencarbonate, and the filter was filtered using a felt-type polypropylene filter having a filter particle size (initial filtration efficiency: 95%) of 10 μm. To adjust the coating liquid (M4). (5) Production of surface light-diffusing polyester film 65 parts by mass of the crystalline homopolymer (Ml), 20 parts by mass of the copolymerized polyester (M2), and 15 parts by mass of polyphenylene of the raw material of the light-diffusing layer (B) Ethylene (M3) was each dried under reduced pressure (1 Torr) at 1 3 5 ° C for 6 hours, and then mixed and supplied to a press 200846179 machine 2. Further, 76.7 parts by mass of the raw material of the support layer (A), crystalline homologous polyester (Ml), and 23.3 parts by mass of the copolymerized polyester (M2) were each dried under reduced pressure (1 Torr) for 6 hours, and then mixed and supplied. Extruder 1. The set temperature of the melted portion, the kneading portion, the polymer tube, the gear pump, and the filter of each extruder was 275 ° C, and the set temperature of the polymer tube after the filter was 27 0 ° C. Each of the raw materials supplied from the extruder 2 and the extruder 1 is laminated using two layers of confluent blocks, and is melt-extruded from the nozzle sheets. Further, the thickness ratio of the layers (A) and (B) is controlled by using a gear pump of each layer to form 90 to 10 . Further, in the above-mentioned filter, either of them is a filter material using a stainless steel sintered body (nominal filtration accuracy: 95% of 10 μm particles are trapped). Further, the temperature of the nozzle was controlled so that the temperature of the extruded resin was 275 °C. The extruded resin was adhered to a cooling drum having a surface temperature of 30 ° C by electrostatic application to be cooled and solidified, and an unstretched film was produced. At this time, the (A) plane is used as the surface contacting the cooling drum. Further, the speed at which the unstretched film was cooled and pulled was 12 m/min. The obtained unstretched film was heated to 79 °C using a preheating roll, and stretched 3.4 times in the longitudinal direction by means of rolls of different peripheral speeds. At this time, the temperature of the film was monitored using an infrared radiation thermometer, and the temperature of the heater was controlled at a maximum temperature of 100 ° C. After the completion of the stretching, the obtained uniaxially stretched film was cooled to 50 ° C, and then the coating liquid (M4) was applied to one surface (layer A side) of the film. The coating liquid was controlled in such a manner that the wet coating amount was about 15 g/m 2 . Subsequently, the coated surface was dried using a drying oven. -52- 200846179 Hold both ends of the uniaxially stretched film with the coating layer using a clamp and guide it to the tenter. After preheating to 1 20 °C, after stretching 2.5 times in the transverse direction at 1 35 °C , at a temperature of 140 ° C, stretching 1.6 times in the transverse direction, and further heat treatment at 240 ° C for 10 seconds, and in the process of cooling to 60 ° C in the transverse direction of 3. 3 % relaxation treatment, to a total thickness of 100 microns Surface light diffusing polyester film. Further, in order to measure the melting point and the intrinsic viscosity of the polyester of each layer, the discharge of the layer (B) was temporarily stopped, and a separate unstretched film of the layer (A) was used. Similarly, the discharge of the (A) layer was temporarily stopped and (B) a separate unstretched film was taken. (4) Film characteristics The film properties obtained in Example 1 are shown in Table 1. As is apparent from Table 1, the surface light diffusing polyester film obtained by the present invention has excellent heat resistance, mechanical strength, and thickness precision which are excellent in biaxially stretched film. Also, the internal haze is small and has a high light transmittance. Further, it was found that most of the total haze was imparted by surface haze, and the light diffusibility thereof was also excellent. Example 2 <Production of Crystalline Copolymerized Polyester Resin (M5)> The constituent component contains 1 〇〇 mol% of a decanoic acid unit as an aromatic dicarboxylic acid component; and 70 mol% of B A diol unit and 30% cyclohexanedimethanol monohydrazine 1/1 as a diol component to produce a crystalline copolymerized polyester resin (M5) having an intrinsic viscosity of 〇6〇dl/g and a melt viscosity of 197Pa*s. . In Example 1, the content of the copolymerization component (the molar ratio of the copolymerization component with respect to the total amount of the diol component) and the content of the polystyrene were as shown in Table 1, and the resin M1 was used. , M3, M5 to adjust the raw material blending of each layer (A), (B). A surface light diffusing polyester film was produced by the same method as in Example 1 except that the above was carried out in the same manner as in Example 1. The film properties obtained in the second embodiment are shown in Table 1. It can be seen from Table i that the second embodiment has excellent characteristics similarly to the first embodiment. Example 3 A surface light diffusing polyester film was produced in the same manner as in Example 1 except that the film was applied to both surfaces of the film. The coating was applied in the same manner and in the same manner as in Example 1, and both surfaces were simultaneously controlled, and the wet coating amounts on both sides were controlled to be about 15 g/m 2 . The characteristics of the obtained film are shown in Table 1. It was found that in the third embodiment, by providing the coating layer on the light diffusion surface, the total light transmittance can be improved more than in the first embodiment. Example 4 In Example 1, each of the layers (A) and (Β) was adjusted by using the resin Μ 1 to Μ 3 in such a manner that the content of the copolymerization component and the content of the polystyrene were as shown in Table 1. Raw material blending. Further, the gear pump of each extruder was controlled so that the thickness ratio 0 of the (Α) layer and the (Β) was 96 to 4. In the manufacture of the unstretched film, the pulling speed of the cooling drum was adjusted in such a manner that the film thickness after biaxial stretching was 250 μm. Further, a plurality of ducts (the cooling air blowing nozzles and the suction nozzles are alternately arranged continuously) are provided along the outer circumference of the cooling drum, and the air is cooled by a space of about 30 mm from the cooling drum. An unstretched film was produced in the same manner as in Example 1 except for the above. Next, the obtained unstretched film was subjected to longitudinal stretching, coating, -54-.200846179 transverse stretching and heat treatment using the same equipment as in Example 1 and using the conditions described in Table 1. A surface light diffusing polyester film having a thickness of 250 μm. The coating was carried out using the same materials and methods as in Example 1, and both surfaces were simultaneously controlled, and the wet coating amounts on both sides were controlled to be about 15 g/m 2 . The characteristics of the obtained film are shown in Table 1. In the present embodiment, since the crystalline homopolyester was used in the rubbing layer (A), it was found that it had excellent strength superior to that of the first embodiment and excellent heat resistance equivalent to that of the first embodiment. Moreover, it has a thickness accuracy that is not very good. On the other hand, in the support layer (A) and the light-diffusing layer (B), since a certain difference can be observed in the melting point of the raw material polyester, it is possible to recognize that there are a number of curls accompanying it, but it is practically in a problem-free range. . Further, in the present Example 4, the internal haze was smaller than that of Examples 1 to 3, and the surface haze was larger. Along with this, the characteristics of total light transmittance and light diffusibility are improved. In the fourth embodiment, as the total thickness is increased, the pulling speed of the cooling drum and the manufacturing speed of the film are also slow. When the film is manufactured at a slower speed, it is predicted that the film is subjected to stress reduction in the longitudinal stretching. Thereby, φ is considered to reduce the voids appearing around the additive of the light-diffusing layer, and as the above result, the internal haze becomes small. [Example 5] In Example 4, the raw material blending of the (Β) layer was adjusted by using the contents of the copolymerization component and the composition of the polystyrene containing the S system as shown in Table 1 and using the resins Μ 1 to M3. Further, the gear pump of each extruder was controlled in such a manner that the thickness ratio of the (Α) layer and the (Β) was 9 〇 to 1 ’. Further, a method of performing 4 H _ was used to produce a surface light diffusing polyester film having a total thickness of 25 μm. -55-.200846179 The characteristics of the obtained film are shown in Table 1. In the present Example 5, the internal haze was slightly increased as compared with Example 4, and the total light transmittance was also slightly lowered, but it was sufficiently excellent. (Example 6) A surface light diffusing polyester film was produced in the same manner as in Example 4 except that the coating layer was provided on one surface (B layer side) of the film. The characteristics of the obtained film are shown in Table 1. In the present embodiment 6, the total light transmittance was slightly lower than that of the embodiment 4, but it was sufficiently excellent in characteristics. Examples 7 and 8 In the example 4', the content of the copolymerization component and the content of the polystyrene were as shown in Table 1, and the raw materials of the resin Μ 1 to M3 wheat were adjusted. Further, the gear pump of each extruder was controlled so that the thickness ratio of the (Α) layer and the (Β) layer was 84 to 16. Further, in the same manner as in Example 4, a surface light diffusing φ polyester film having a total thickness of 8 8 μm was produced. The properties of the obtained film are shown in Table 1. Example 9 to 1 1 In Example 4, the content of the copolymerization component and the content of the polystyrene were as shown in Table 1, and the resin Μ 1 to M3 was used to adjust the (原料) raw material blending. . Further, the gear pump of each extruder was controlled so that the thickness ratio of the (Α) layer and the (Β) layer was 89 to 11. In the case of producing an unstretched film, the pulling speed of the cooling drum was adjusted in such a manner that the thickness of the film after biaxial stretching was 188 μm. Further, an unstretched film was produced by the same method as in Example 4. -56- 200846179 Next, the obtained unstretched film was subjected to longitudinal stretching, coating, transverse stretching, and heat treatment using the same equipment as in Example 1 and using the conditions described in Table 1 to obtain a total thickness. A light diffusing polyester film of 1 8 8 μm surface. The coating was carried out using the same materials and methods as in Example 4, and both surfaces were simultaneously controlled, and the wet coating amounts on both sides were controlled to be about 15 g/m 2 . The characteristics of the obtained film are shown in Table 1. Comparative Example 1 In Example 1, the raw material blending of the light-diffusing layer (B) was changed to a mixture of 85 parts by mass of the crystalline homopolyester (M1) and 15 parts by mass of polystyrene (M4). Further, the raw material of the support layer (A) was changed to a crystalline homopolyester (Ml). Further, a polyester film having a total thickness of 10 μm was produced in the same manner as in Example 1. The characteristics of the obtained film are shown in Table 1. In Comparative Example 1, since the surface alignment coefficient was too large, the internal haze was large and the total light transmittance was drastically lowered. Further, a void is formed around the polystyrene. _ Comparative Example 2 In Example 5, the resin crucibles 1 to 3 were adjusted so that the content of the copolymerization component of the layer (B) was 22 mol%. Using the same arrangement as in Example 1, longitudinal stretching, coating, transverse stretching and heat treatment were carried out under the conditions described in Table 1, to produce a surface light diffusing polyester film having a total thickness of 25 μm. The coating was carried out using the same materials and methods as in Example 1 and simultaneously performed on both sides, and the wet coating amounts on both sides were controlled to be about 15 g/m 2 . The characteristics of the obtained film are shown in Table 1. Although the thin film of the comparative example has a high total light transmittance and excellent light diffusibility, the surface alignment coefficient is large, the dimensional stability is poor, and the curling flaw is large. The curl of the obtained film was severe, and the evaluation of the thermal dimensional stability could not be performed.
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W\ m 最 I » Φ 象 II top 撕 $ 蒙 ia m P M SI _ 螋 癒 急 酲 m tnij 脚 η S » 鑀 塗布液(M4)的塗布 采 藜 m 赃 m s 概 g 躯 it s OQ 幽 <1 & IS /^N P m s _ « m P a m 歲 m s CO 幽 m < i? 3 K 錤 画 s PQ m 贜 槲 m s 顱 « £ S S 二 滕ώ is feo «δ S m 鹱 m g 驄 m g « m 8s K 驄 m δέ s 屮 » *2? 螂s cs趣 經 m 俚 m m ST If m it 租 尺寸變 化率(％) 拉伸強 度(MPa) 二醇 成分 iS ' |添加劑 縱向 橫向 Y聚酯層A 光擴散層(B) 製造條件 光學特性 耐熱性 薄膜特性 200846179 * 產業上之利用可能性 本發明的表面光擴散性聚酯薄膜能夠使用於液晶顯示 器的背光板模組、照明裝置等作爲光擴散性薄膜。又，能 夠使用作爲棱鏡用基材薄膜。因此對產業界有重大的貢獻。 【圖式簡單說明】 無。 【元件符號說明】 無。Rrwi Οί I 8 r—4 1 CN 03⁄4 1 i?y 0-. oo PQ < \r\ § CO CO t vo On ir> ON 5 vq QO cn cO <S 03 (Νϊ 〇α CO Both sides ( M 0.07 oo CM cs oo cs 0,58 S to to 〇X mm Μ m 〇〇VO S 〇X i 8 r—1 1 〇• I κη 〇Η wn o A/B ON ο ·—« inch cn 1 § Cn 1 O oi o 〇ο CO CO One side A side § o 0.17 VO 0.56 VO cn oo sv〇X ο ro ο o (N OO cn cs 〇〇tH 1 gs 1 , 〇〇〇〇cs 1 CO CU f— H t—i § ο CO CO 1 gi—H m cn tH o inch oi vq oo cri v〇CO 04 oo o Two-sided 〇〇〇〇1—^ s 0.11 C<3 0.58 S oo VO oo s MD 〇VO OO As <N CN CN C 〇0 1 _ § , 〇〇QO c< 1 οο un f-^ r-H 1 A/B ON sm oS s — \n cn o inch · inch <N vq i- HI oo (TV OO m cN oo two sides 〇〇〇〇s 0.11 art 0.58 oo VO sv〇0 ON g cn cs C 〇σ> 1 § 1 〇〇〇〇c< 1 ίχ r-^ A/B ON CO ΓΛ 1 W^> CO o 寸 c<i vq oo CO oo cn CN Γ- τ—4 cn Two-sided 〇〇〇〇st—H f—< CS Art inch 0.58 s oo \〇u^i CO vr> \〇ο ΓΟ oo 〇〇〇0 1 〇2 1 〇〇〇〇cs 1 ^0 Οι \n \〇1 A/B as or—< CO CO summer u-> cr o inch oi v 〇oo ro o 二CO Ψ^4 two sides 〇〇〇〇i—* 0.09 CS s 0.58 sm ON ο cn OO ov〇oo cn CN 〇〇i i S 1 On 〇〇1—^ r* 1 (X. VC PC a\ o 1—4 cn a 1 § cn o S vq oo ... o cs CO 1—< two sides oo oo rH 0.10 inch ra 0.58 宗〇 ov〇〇CN cn oo cn 〇〇v〇1 thorn S 1 o Οο P PQ < σ\ or—H c〇CO 1 § VO cn rH o inch c4 vq oo cri , cs 04 CO rH — face B layer side oo 0.14 oo oo 0.57 >〇V〇m ΟΪ Bu 〇σ \卜〇sr-^ CN CN} 〇〇uo mo 1—« • CO σ\ 卜 1 4—» GO CU 〇o A/B ON om CO 1 ur> CO o 1-1 inch oi vq oo rn o ca (Ν cs CO ^ two sides o ir> cs m S cs oa inch i 0.57 s CO P Hi 〇rH cn 〇fH oo 0 <N 01 I I cO 1 K o rH • go 1 〇〇o inch 55 < ; ON 0 1 < CO CO 1 g VO CO o inch oi vq oo cn o CN <Ν c<i cn two sides 〇 o 0.14 oo s oo 1 0.57 v〇CO <N 〇 〇 ON 卜 o CO ON Oi cN CS 〇〇s 卜 CO ON 卜 1 (V2 cu in o OQ < 〇\ of-H CO 1 s 1 -< mo IT) oi Vq po C<1 ο CO CO Both sides O »—4 o 0.12 1 03⁄4 s 1 0.57 as § o cn cn 〇C^· o csi o cn *—1 § 〇〇<N | iT> 〇〇wo ir ^ O〇νΊ w GO S o as < On o 1 § CO o XT) 03 vq O inch yn cn cs ο CO «ri 1 I® 1 < o T-<! o 0.09 1 o (N 1 0.58 - ON oo σ\ cn OO CO ON 〇CO rH osf—1 oo 〇〇^―* mm « 卜c〇ON 卜1 4-* 00 cu o < 〇\ o inch CO fw^> co o ir\ C4 vq o inch · 〇cs ο cn CO ¥1 1 < oo 0.12 1 <M 1 0.57 as 〇〇〇r- mm r- 〇Γ — CD CN rH o ON 〇〇gw 赇S α g « o ω赇ο ζ § W Η a ο 骏 e |M] _ m M » aj -1A fe! it s PQ _ 1S * 1 cheek « 1 虏i: » >—N s vertical /^*NP m IS P « m φ 归1 tat 战κ-s •P m 虏教11 inD. W\ m Most I » Φ 象 II top tearing $ 蒙 m PM SI _ healing 酲 m tnij foot η S » 鑀 coating liquid (M4 Coating pick m 赃ms gg ot s OQ 幽<1 & IS /^NP ms _ « m P am years ms CO 幽m < i? 3 K 錤画s PQ m 贜槲ms Cranial « £ SS II ώ is feo «δ S m 鹱mg 骢mg « m 8s K 骢m δέ s 屮» *2? 螂s cs fun m 俚mm ST If m it Rent size change rate (%) Tensile strength (MPa) II Alcohol component iS '|Additive longitudinal direction Y polyester layer A Light diffusion layer (B) Manufacturing conditions Optical characteristics Heat resistant film characteristics 200846179 * Industrial use possibility The surface light diffusing polyester film of the present invention can be used for a liquid crystal display A backlight module, an illumination device, or the like is used as a light diffusing film. Further, a base film for a prism can be used. Therefore, it has made significant contributions to the industry. [Simple description of the diagram] None. [Component Symbol Description] None.
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